AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 1106 AM MDT TUE JUL 29 2008 .UPDATE... UPDATED TEMPERATURES AND DEW POINTS FOR THE REST OF THIS MORNING...TO BETTER REFLECT CURRENT CONDITIONS. UPDATED THE POPS FOR THIS AFTERNOON. DID NOT MAKE ANY CHANGES TO THE WINDS. && .PREV DISCUSSION... /ISSUED 432 AM MDT TUE JUL 29 2008/ SHORT TERM... (TODAY AND TONIGHT) AFTER RATHER ACTIVE WEATHER YESTERDAY...TODAY PROMISES TO BE DRIER AS THE SHORTWAVE AND MOISTURE REMNANTS FROM DOLLY CONTINUES TO SHIFT EASTWARD THROUGH THE CENTRAL PLAINS...AND DRIER AIR WORKS IN FROM THE WEST. LOOKS LIKE ANOTHER WEAK SHORTWAVE IS CURRENTLY MOVING THROUGH CENTRAL UT ATTM JUDGING FROM WV PICS AND RUC UPPER AIR ANALYSIS. THIS FEATURE WILL BE MOVING ACROSS THE AREA THIS AFTERNOON. HOWEVER MOISTURE WILL BE MUCH LESS PREVALENT TODAY WHICH SHOULD LIMIT TSTORM COVERAGE AND STRENGTH. HAVE DECREASED POPS ACROSS THE MOUNTAINS. STILL SOME RESIDUAL MOISTURE ACROSS THE SOUTHEAST PLAINS WITH DEW POINTS LIKELY STAYING IN THE MID 50S ALONG THE CO/KS BORDER TO AROUND 40 FOR THE I-25 CORRIDOR. GIVEN THERE WILL BE SOME WEAK FORCING THIS AFTERNOON...HAVE KEPT SOME ISOLATED POPS ACROSS THE PLAINS WITH LOW GRADE SCATTERED POPS ALONG THE EASTERN SLOPES OF THE SE MTS WHERE UPSLOPE FLOW MAY ALSO HELP INITIATE SOME THUNDERSTORMS. HOWEVER IF GFS QPF SOLN IS CORRECT...THIS COULD BE OVERDONE. DOESN`T APPEAR TO BE MUCH OF A CAP IN MODEL SOUNDINGS THOUGH ACROSS THE EASTERN MTNS/ADJACENT LOWER EASTERN SLOPES...THOUGH CAPE IS CERTAINLY A LOT LESS...AND CONFINED TO A S51OW LAYER BELOW H4. IF SFC DEW POINTS DROP INTO THE MID 30S OR LOWER ALONG THE LOWER EASTERN SLOPES...THEN MAY SEE JUST MODERATE CU AND A FEW LIGHT SHOWERS. SINCE PRECIP WATERS DROP TO .5 INCHES OR LESS ACROSS THE WEST...WITH A LITTLE OVER AN INCH ACROSS THE PLAINS...HEAVY RAIN THREAT WILL DROP OFF CONSIDERABLY. ANY CONVECTION SHOULD DIE OFF QUICKLY AFTER SUNSET. WITH DRIER AIR WORKING IN COULD SEE SOME COOL MIN TEMPS ACROSS THE POORLY DRAINING MOUNTAIN VALLEYS AS EFFICIENT RADIATIONAL COOLING IN DRIER AIR MASS TAKES PLACE. -KT LONG TERM... (WEDNESDAY THROUGH MONDAY) AN UPR RIDGE WL BE OVR THE FORECAST AREA WED THROUGH MON. IT LOOKS GENERALLY DRY OVR THE AREA...WITH PRECIPITABLE WATER VALUES DECREASING FOR WED THROUGH FRI GENERALLY BELOW 0.75 INCH. HOWEVER CHANCES ARE WE WL STILL SEE SOME SHOWERS/TSTMS DEVELOP OVR THE MTS. TEMPS THESE DAYS WILL BE ABOVE NORMAL WITH HIGHS OVR THE SERN PLAINS IN THE 90S TO LOWER 100S. BEGINNING SAT LOW LEVEL S TO SE FLOW IS FORECAST TO BRING AN INCREASE IN LOW LEVEL MSTR TO THE SERN PLAINS...AND PRECIPITABLE WATER VALUES INCREASE TO AROUND 1 INCH...AND INCREASE TO AROUND 1.25 INCHES BY MON. FOR SAT THE GFS SHOWS LITTLE PCPN AND HAS IT MAINLY CONFINED TO THE MTS AS DOES THE ECMWF. THEN FOR SUN NIGHT AND MON SOME WEAK DISTURBANCES MAY MOVE ACRS THE AREA LEADING TO A BETTER CHANCE FOR PCPN. AVIATION... ISOLATED THUNDERSTORMS EXPECTED ACROSS THE LOWER ELEVATIONS WITH ISOLATED TO SCATTERED MOUNTAIN THUNDERSTORMS AFTER 18Z. VFR TO MVFR CIGS EXPECTED WITH THUNDERSTORMS TODAY ALONG WITH ERRATIC WIND GUSTS UP TO 45 MPH AND LIGHT RAINFALL. WINDS WILL STAY PREDOMINANTLY OUT OF THE NORTH ACROSS THE PLAINS TODAY BEFORE LIGHT DRAINAGE WINDS SET UP OVERNIGHT. CONVECTION AND CONVECTIVE DEBRIS CLOUDS SHOULD DISSIPATE QUICKLY THIS EVENING WITH LOSS OF HEATING. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 14/21 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 432 AM MDT TUE JUL 29 2008 .SHORT TERM... (TODAY AND TONIGHT) AFTER RATHER ACTIVE WEATHER YESTERDAY...TODAY PROMISES TO BE DRIER AS THE SHORTWAVE AND MOISTURE REMNANTS FROM DOLLY CONTINUES TO SHIFT EASTWARD THROUGH THE CENTRAL PLAINS...AND DRIER AIR WORKS IN FROM THE WEST. LOOKS LIKE ANOTHER WEAK SHORTWAVE IS CURRENTLY MOVING THROUGH CENTRAL UT ATTM JUDGING FROM WV PICS AND RUC UPPER AIR ANALYSIS. THIS FEATURE WILL BE MOVING ACROSS THE AREA THIS AFTERNOON. HOWEVER MOISTURE WILL BE MUCH LESS PREVALENT TODAY WHICH SHOULD LIMIT TSTORM COVERAGE AND STRENGTH. HAVE DECREASED POPS ACROSS THE MOUNTAINS. STILL SOME RESIDUAL MOISTURE ACROSS THE SOUTHEAST PLAINS WITH DEW POINTS LIKELY STAYING IN THE MID 50S ALONG THE CO/KS BORDER TO AROUND 40 FOR THE I-25 CORRIDOR. GIVEN THERE WILL BE SOME WEAK FORCING THIS AFTERNOON...HAVE KEPT SOME ISOLATED POPS ACROSS THE PLAINS WITH LOW GRADE SCATTERED POPS ALONG THE EASTERN SLOPES OF THE SE MTS WHERE UPSLOPE FLOW MAY ALSO HELP INITIATE SOME THUNDERSTORMS. HOWEVER IF GFS QPF SOLN IS CORRECT...THIS COULD BE OVERDONE. DOESN`T APPEAR TO BE MUCH OF A CAP IN MODEL SOUNDINGS THOUGH ACROSS THE EASTERN MTNS/ADJACENT LOWER EASTERN SLOPES...THOUGH CAPE IS CERTAINLY A LOT LESS...AND CONFINED TO A SHALLOW LAYER BELOW H4. IF SFC DEW POINTS DROP INTO THE MID 30S OR LOWER ALONG THE LOWER EASTERN SLOPES...THEN MAY SEE JUST MODERATE CU AND A FEW LIGHT SHOWERS. SINCE PRECIP WATERS DROP TO .5 INCHES OR LESS ACROSS THE WEST...WITH A LITTLE OVER AN INCH ACROSS THE PLAINS...HEAVY RAIN THREAT WILL DROP OFF CONSIDERABLY. ANY CONVECTION SHOULD DIE OFF QUICKLY AFTER SUNSET. WITH DRIER AIR WORKING IN COULD SEE SOME COOL MIN TEMPS ACROSS THE POORLY DRAINING MOUNTAIN VALLEYS AS EFFICIENT RADIATIONAL COOLING IN DRIER AIR MASS TAKES PLACE. -KT .LONG TERM... (WEDNESDAY THROUGH MONDAY) AN UPR RIDGE WL BE OVR THE FORECAST AREA WED THROUGH MON. IT LOOKS GENERALLY DRY OVR THE AREA...WITH PRECIPITABLE WATER VALUES DECREASING FOR WED THROUGH FRI GENERALLY BELOW 0.75 INCH. HOWEVER CHANCES ARE WE WL STILL SEE SOME SHOWERS/TSTMS DEVELOP OVR THE MTS. TEMPS THESE DAYS WILL BE ABOVE NORMAL WITH HIGHS OVR THE SERN PLAINS IN THE 90S TO LOWER 100S. BEGINNING SAT LOW LEVEL S TO SE FLOW IS FORECAST TO BRING AN INCREASE IN LOW LEVEL MSTR TO THE SERN PLAINS...AND PRECIPITABLE WATER VALUES INCREASE TO AROUND 1 INCH...AND INCREASE TO AROUND 1.25 INCHES BY MON. FOR SAT THE GFS SHOWS LITTLE PCPN AND HAS IT MAINLY CONFINED TO THE MTS AS DOES THE ECMWF. THEN FOR SUN NIGHT AND MON SOME WEAK DISTURBANCES MAY MOVE ACRS THE AREA LEADING TO A BETTER CHANCE FOR PCPN. && .AVIATION... ISOLATED THUNDERSTORMS EXPECTED ACROSS THE LOWER ELEVATIONS WITH ISOLATED TO SCATTERED MOUNTAIN THUNDERSTORMS AFTER 18Z. VFR TO MVFR CIGS EXPECTED WITH THUNDERSTORMS TODAY ALONG WITH ERRATIC WIND GUSTS UP TO 45 MPH AND LIGHT RAINFALL. WINDS WILL STAY PREDOMINANTLY OUT OF THE NORTH ACROSS THE PLAINS TODAY BEFORE LIGHT DRAINAGE WINDS SET UP OVERNIGHT. CONVECTION AND CONVECTIVE DEBRIS CLOUDS SHOULD DISSIPATE QUICKLY THIS EVENING WITH LOSS OF HEATING. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31/28 co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 911 PM MDT MON JUL 28 2008 .SHORT TERM... UPDATED TO REFLECT EVENING PRECIPITATION TRENDS. ALSO ADDED HEAVY RAIN WORDING OVER THE FAR EASTERN PLAINS. FINALLY...ADJUSTED SHORT TERM TRENDS ON TEMPS...DEWPOINTS...WINDS...ETC. .LONG TERM... NO UPDATES AT THIS TIME. && .AVIATION... NO UPDATES AT THIS TIME. && .PREV DISCUSSION... /ISSUED 306 PM MDT MON JUL 28 2008...CORRECTED/ SHORT TERM... (TONIGHT AND TOMORROW) MAIN CONCERNS FOR THIS EVENINGS FORECAST IS IN DETERMINING THE INTERACTION BETWEEN THE INCOMING VORT MAX AND SHORTWAVE...THE REMNANT MOISTURE FROM DOLLY AND THE SPEED OF AN INCOMING BOUNDARY. THE DEW POINTS REMAIN IN THE 50S TO 60S ALONG THE I 25 CORRIDOR AND THE EASTERN PLAINS. THUNDERSTORMS LOOK TO CONTINUE THROUGH THE MOUNTAINS AND THE OUTER SAN LUIS VALLEY. THESE STORMS WILL LINGER AND STRETCHING THE EASTERN PLAINS THROUGH THE EARLY EVENING HOURS. THE NAM AND RUC BOTH HAVE WIDESPREAD PRECIPITATION THROUGHOUT SOUTHERN COLORADO LATE THIS AFTERNOON AND EARLY EVENING. THE SYNOPTIC MOTION LOOKS TO PROPAGATE INTO THE HIGHER DEWPOINTS LEFT BEHIND BY DOLLY. THIS LOOKS TO ALLOW FOR LATE DAY THUNDERSTORMS AND MAY PROVIDE ENOUGH INSTABILITY TO SUSTAIN THEM UNTIL MIDNIGHT. IN COORDINATION EFFORTS I HAVE BROUGHT UP POPS ALONG THE EASTERN COLORADO BORDER LATE TONIGHT. TOMORROW...THE INCOMING SUBSIDENCE WILL NOT OFFER NEAR THE AMOUNT OF DYNAMICS AS TODAY...SO TOMORROWS CONVECTIVE ACTIVITY WILL BE CONTAINED TO THE SOUTHERN MOUNTAINS...THE CORRESPONDING UPSLOPE REGIONS AND A FEW ISOLATED CELLS MAY DRIFT ALONG THE PALMER DIVIDE. JMC LONG TERM... (TUESDAY NIGHT THROUGH MONDAY) NOT A LOT OF CHANGE FROM DAY TO DAY EXPECTED THROUGH THE EXTENDED FORECAST PERIODS...SO WILL GROUP THEM ALL TOGETHER. THE UPPER RIDGE BUILDS IN OVER THE REGION TUESDAY NIGHT AND IS THE DOMINANT FEATURE THROUGH MONDAY. THE RIDGE AXIS IS EXPECTED TO SLIDE EAST OF THE STATE SAT AM...ALLOWING THE MOISTURE PLUME ACROSS TX AND OLD MEXICO TO FINALLY GET DRAWN UP INTO THE 4 CORNERS REGION. THIS WOULD ENHANCE POPS FOR THE CWA OVER THE WEEKEND. HOWEVER...UP UNTIL SAT THE EXTENDED MODELS DO NOT HOLD MUCH PROMISE FOR SIGNIFICANT BENEFICIAL PCPN UNFORTUNATELY. PAST PERFORMANCE HAS SHOWN THAT THE NAM IS OVERDOING THE QPF...WHILE GFS NORMALLY REMAINS SOMEWHAT DRY. TAKING AN AVERAGE OF THE TWO ROUGHLY EQUATES TO ISOLATED TO SCATTERED DIURNAL CONVECTION OVER THE HIGHER TERRAIN...SLOWLY MAKING IT ONTO THE ADJACENT AREAS THROUGH THE EVENING HRS. ANY PCPN THAT DOES MAKE IT TO THE GROUND WILL MOST LIKELY BE LIGHT AT BEST. AS FOR TEMPS...700 AND 850 MB CHARTS DO NOT SHOW A LOT OF CHANGE UNTIL MON. H7 TEMPS OF 20-22 C...AND 850 MB TEMPS AT 32-36 C...POINT TO ABOVE NORMAL MAX TEMPS EACH AFTN ALONG WITH VERY MILD NIGHTS. CLEARING SKIES ALONG WITH GENERALLY LIGHT WINDS AT NIGHT WILL ALLOW FOR EFFICIENT RADIATIONAL COOLING AND INVERSION DEVELOPMENT IN THE MTS. 27 AVIATION... SCATTERED THUNDERSTORMS ACROSS CENTRAL AND SOUTH EASTERN COLORADO TODAY ARE THE MAJOR THREAT. MVFR TO IFR CIGS AND VISIBILITIES REMAIN A POSSIBILITY THIS AFTERNOON AND EVENING. SHOWERS AND THUNDERSTORMS REMAIN ONGOING AS THEY MOVE ACROSS THE MOUNTAINS AND WILL DRAPE ACROSS THE PLAINS AS THE EVENING CONTINUES. HEAVY RAIN AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE. THE THUNDERSTORM THREAT FOR MOST OF THE AREA WILL HAVE DISSIPATED BY 6Z.-JMC && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 50/23 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 306 PM MDT MON JUL 28 2008...CORRECTED .SHORT TERM... (TONIGHT AND TOMORROW) MAIN CONCERNS FOR THIS EVENINGS FORECAST IS IN DETERMINING THE INTERACTION BETWEEN THE INCOMING VORT MAX AND SHORTWAVE...THE REMNANT MOISTURE FROM DOLLY AND THE SPEED OF AN INCOMING BOUNDARY. THE DEW POINTS REMAIN IN THE 50S TO 60S ALONG THE I 25 CORRIDOR AND THE EASTERN PLAINS. THUNDERSTORMS LOOK TO CONTINUE THROUGH THE MOUNTAINS AND THE OUTER SAN LUIS VALLEY. THESE STORMS WILL LINGER AND STRETCHING THE EASTERN PLAINS THROUGH THE EARLY EVENING HOURS. THE NAM AND RUC BOTH HAVE WIDESPREAD PRECIPITATION THROUGHOUT SOUTHERN COLORADO LATE THIS AFTERNOON AND EARLY EVENING. THE SYNOPTIC MOTION LOOKS TO PROPAGATE INTO THE HIGHER DEWPOINTS LEFT BEHIND BY DOLLY. THIS LOOKS TO ALLOW FOR LATE DAY THUNDERSTORMS AND MAY PROVIDE ENOUGH INSTABILITY TO SUSTAIN THEM UNTIL MIDNIGHT. IN COORDINATION EFFORTS I HAVE BROUGHT UP POPS ALONG THE EASTERN COLORADO BORDER LATE TONIGHT. TOMORROW...THE INCOMING SUBSIDENCE WILL NOT OFFER NEAR THE AMOUNT OF DYNAMICS AS TODAY...SO TOMORROWS CONVECTIVE ACTIVITY WILL BE CONTAINED TO THE SOUTHERN MOUNTAINS...THE CORRESPONDING UPSLOPE REGIONS AND A FEW ISOLATED CELLS MAY DRIFT ALONG THE PALMER DIVIDE. JMC .LONG TERM... (TUESDAY NIGHT THROUGH MONDAY) NOT A LOT OF CHANGE FROM DAY TO DAY EXPECTED THROUGH THE EXTENDED FORECAST PERIODS...SO WILL GROUP THEM ALL TOGETHER. THE UPPER RIDGE BUILDS IN OVER THE REGION TUESDAY NIGHT AND IS THE DOMINANT FEATURE THROUGH MONDAY. THE RIDGE AXIS IS EXPECTED TO SLIDE EAST OF THE STATE SAT AM...ALLOWING THE MOISTURE PLUME ACROSS TX AND OLD MEXICO TO FINALLY GET DRAWN UP INTO THE 4 CORNERS REGION. THIS WOULD ENHANCE POPS FOR THE CWA OVER THE WEEKEND. HOWEVER...UP UNTIL SAT THE EXTENDED MODELS DO NOT HOLD MUCH PROMISE FOR SIGNIFICANT BENEFICIAL PCPN UNFORTUNATELY. PAST PERFORMANCE HAS SHOWN THAT THE NAM IS OVERDOING THE QPF...WHILE GFS NORMALLY REMAINS SOMEWHAT DRY. TAKING AN AVERAGE OF THE TWO ROUGHLY EQUATES TO ISOLATED TO SCATTERED DIURNAL CONVECTION OVER THE HIGHER TERRAIN...SLOWLY MAKING IT ONTO THE ADJACENT AREAS THROUGH THE EVENING HRS. ANY PCPN THAT DOES MAKE IT TO THE GROUND WILL MOST LIKELY BE LIGHT AT BEST. AS FOR TEMPS...700 AND 850 MB CHARTS DO NOT SHOW A LOT OF CHANGE UNTIL MON. H7 TEMPS OF 20-22 C...AND 850 MB TEMPS AT 32-36 C...POINT TO ABOVE NORMAL MAX TEMPS EACH AFTN ALONG WITH VERY MILD NIGHTS. CLEARING SKIES ALONG WITH GENERALLY LIGHT WINDS AT NIGHT WILL ALLOW FOR EFFICIENT RADIATIONAL COOLING AND INVERSION DEVELOPMENT IN THE MTS. MOORE && .AVIATION... SCATTERED THUNDERSTORMS ACROSS CENTRAL AND SOUTH EASTERN COLORADO TODAY ARE THE MAJOR THREAT. MVFR TO IFR CIGS AND VISIBILITIES REMAIN A POSSIBILITY THIS AFTERNOON AND EVENING. SHOWERS AND THUNDERSTORMS REMAIN ONGOING AS THEY MOVE ACROSS THE MOUNTAINS AND WILL DRAPE ACROSS THE PLAINS AS THE EVENING CONTINUES. HEAVY RAIN AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE. THE THUNDERSTORM THREAT FOR MOST OF THE AREA WILL HAVE DISSIPATED BY 6Z.-JMC && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 14/27 co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 938 AM MDT MON JUL 28 2008 .UPDATE... UPDATED FORECAST TO LOWER POPS AND WEATHER GRIDS IN THE EAST TO BETTER REFLECT THE CURRENT CONDITIONS. DID NOT MAKE ANY CHANGES TO TEMP/DP OR WINDS. && .PREV DISCUSSION... /ISSUED 411 AM MDT MON JUL 28 2008/ SHORT TERM... (TODAY AND TONIGHT) MAIN CONCERNS FOR SHORT TERM FORECAST REVOLVE AROUND POPS. COMPLICATED PATTERN TODAY WITH CIRCULATION CENTER FROM THE REMNANTS OF DOLLY MOVING SLOWLY OUT OF EASTERN CO INTO WRN KS THIS AM. HARD TO SEE ANY CIRCULATION CENTERS ALOFT ASSOC WITH DOLLY IN WV PICS THOUGH RUC UPPER AIR ANALYSIS SHOWS CIRC CENTER IN H5 WIND FIELD BETWEEN KLAA AND KGCK. SFC LOW IS POSITIONED ACROSS THE SE CORNER OF THE STATE BETWEEN KSPD AND KLAA...WITH EASTERLY WINDS AND LOWER 60 DEW POINTS FUNNELING UP THE ARKANSAS RIVER. AHEAD OF THE SFC LOW... SOUTHERLY WINDS ARE ADVECTING LOWER-MID 60 DEW POINTS ACROSS THE SE CORNER OF THE STATE. MEANWHILE OUT WEST...STRONG SHORTWAVE MOVING INTO WRN CO WITH QUITE A BIT OF LIGHTNING ACROSS WESTERN PORTIONS OF THE STATE FOR THIS HOUR. FOR TODAY...CONCERN WILL BE TIMING AND COVERAGE OF THUNDERSTORMS. REMNANTS OF DOLLY SLOWLY EXITS TO THE EAST TODAY AS SHORTWAVE OUT WEST MOVES IN. STILL LOTS OF MOISTURE TO CONTEND WITH ACROSS THE PLAINS WITH DEW POINTS STAYING IN THE 50S TO LOWER 60S THIS AFTERNOON. PRECIP H20S RANGE FROM 1 TO 1.5+ INCHES ACROSS THE PLAINS...WITH UP TO .75 INCHES ACROSS THE MOUNTAINS. NAM/GFS BREAK OUT ANOTHER ROUND OF SHOWERS/THUNDERSTORMS ALONG THE CO/KS BORDER THIS MORNING ALONG THE EASTERN EDGE OF THE SFC LOW. FROM WV LOOPS THERE COULD BE ANOTHER WEAK SHORTWAVE WITHIN THE MOISTURE PLUME LIFTING INTO THE SE CORNER OF THE STATE FROM REMNANTS OF DOLLY. REGIONAL RADAR MOSAICS HAVE BEEN PERCOLATING THUNDERSTORM ACTIVITY ACROSS THE PANHANDLES AND WRN KS A GOOD PORTION OF THE NIGHT. JUDGING FROM TRAJECTORIES...THESE MAY END UP STAYING OFF TO THE EAST...AND TO MAKE MATTERS MORE DIFFICULT...LATEST RUC13...00Z ECMWF AND 4KM NMM-WRF KEEPS PRECIPITATION AXIS FARTHER TO THE EAST THROUGH THE MORNING HOURS WITH A LULL IN PRECIPITATION IN SUBSIDENT REGION ON BACK SIDE OF DOLLY UNTIL SHORTWAVE OUT WEST MOVES IN LATER THIS AFTERNOON/EVENING. THIS IS A C51ENGING DILEMMA. HAVE BUMPED UP POPS AFTER 15Z TO MATCH UP WITH CONSENSUS OF NEIGHBORING WFOS AND HPC QPF. GIVEN POSITION OF SFC LOW...THIS SCENARIO DOES LOOK PLAUSIBLE. ISOLATED THUNDERSTORMS ARE ALREADY MOVING INTO WRN CO...SO THINK COVERAGE SHOULD RAMP UP BY LATE MORNING OR EARLY AFTERNOON AS SFC HEATING IN CONCERT WITH SHORTWAVE ENERGY ALLOWS SCATTERED THUNDERSTORMS TO REDEVELOP. THUNDERSTORMS WILL THEN SPREAD EASTWARD ACROSS THE ADJACENT PLAINS BY LATE AFTN/EVENING AS SHORTWAVE MOVES ACROSS. MAIN THREAT WITH THUNDERSTORMS TODAY WILL BE LOCALLY HEAVY RAIN...WIND GUSTS UP TO 50 MPH...AND LIGHTNING. COULD SEE SOME SMALL HAIL (GENERALLY LESS THAN 1/2 INCH IN DIAMETER) OVER THE HIGHER TERRAIN OUT WEST. HEAVY RAIN WILL BE THE GREATEST THREAT ACROSS THE EASTERN PLAINS...GENERALLY EAST OF A LINE FROM KLHX TO KIM. HAVE ADDED SOME TRW+ IN THE GRIDS TO ACCOUNT FOR THIS. AGAIN WITH DRY CONDITIONS OF LATE...FFG VALUES ARE STILL FAIRLY HIGH. SO THINK ANY FLASH FLOOD THREAT WILL BE VERY LOCALIZED. STORM MOTIONS ALSO LOOK A LITTLE FASTER TODAY AS WELL. SHOULD SEE THUNDERSTORMS DECREASE FROM WEST TO EAST DURING THE EVENING/OVERNIGHT HOURS WITH A FEW THUNDERSTORMS LINGERING PAST MIDNIGHT ACROSS THE PLAINS BEFORE SHORTWAVE EXITS THE REGION. -KT LONG TERM... (TUESDAY THROUGH SUNDAY) ..ACTIVE WEATHER PATTERN TUESDAY... ..POSSIBLY DRYING OUT AND HEATING UP WEDNESDAY-SUNDAY... TUESDAY...POTENTIALLY STILL AN ACTIVE WEATHER PATTERN. HARD TO FIND OUT WHICH MIDLEVEL SHORTWAVE TROUGH WILL ENHANCE AFTERNOON CONVECTION AND IT COULD POSSIBLY BE THE WAVE OVER SOUTHERN UT RIGHT NOW...BUT THAT MIGHT BE INTO THE CENTRAL PLAINS BY LATE TUESDAY AFTERNOON. TOUGH CALL...ESPECIALLY SINCE THE GFS AND NAM- WRF QPF SCHEMES ARE NIGHT-AND-DAY. THE GFS HAS NO QPF ACROSS CO TUESDAY AFTERNOON...WHILE THE NAM-WRF NEARLY HAS THE EASTERN 1/2 OF CO COVERED IN QPF. LATELY...THE NAM-WRF HAS BEEN WAY OVERDONE WITH ITS COVERAGE AND QPF INTENSITY LEAVING IT SUSPECT. STILL COULDN`T RULE OUT SOME AFTERNOON MOIST CONVECTION OVER THE MOUNTAINS AND POSSIBLY MIGRATING INTO THE NEARBY VALLEYS AND I-25 CORRIDOR. I PLAYED THIS SCENARIO IN THE POP/WX GRIDS. ANY PRECIPITATION SHOULD BE DIURNAL. TEMPERATURES WILL REMAIN ABOVE CLIMO FOR LATE JULY. WEDNESDAY...THIS IS WHEN THE MIDLEVEL HIGH BEGINS TO BUILD OVER THE FOUR CORNERS AREA. THE RELATIVELY DEEP DRIER AIR MASS OVER CA SHOULD MOVE INTO THE CENTRAL ROCKIES. AGAIN...THE GFS AND NAM-WRF ARE AT ODDS WITH QPF COVERAGE AND INTENSITY. WILL GIVE A LEANING NOD TO THE GFS...SINCE THE NAM-WRF HAS BEEN OVERDOING THE QPF LATELY. WILL LIKELY TACK ON A FEW MORE DEGREES TO THE HIGH TEMPERATURES GIVEN 500MB HEIGHT RISES. 700MB TEMPERATURES WARM TO +18C TO +21C ACROSS MUCH OF SOUTHERN CO. HIGH TEMPERATURES AROUND 100F LOOK DOABLE...STILL...AT PUB AND LHX...SO WILL CONTINUE. WITH SUCH WARM TEMPERATURES...IT IS ALWAYS TOUGH GETTING MEASURABLE PRECIPITATION...SO STATISTICALLY THE ODDS ARE GREATER OF GETTING TRACE OR A DRY (RAIN GAGE) BUCKET. THURSDAY THROUGH SUNDAY...ENSEMBLE DATA INCLUDING THE ECMWF WANTS TO BUILD THE LARGE HOT-HIGH CENTER OVER CO WITH THE DGEX KEEPING IT OVER THE FOUR CORNERS AREA. THERE IS THE POTENTIAL FOR SOME S51OW VERY WEAK COLD FRONTAL BOUNDARY SURGES THROUGH EASTERN CO...BUT IT SHOULDN`T AMOUNT TO MUCH...EXCEPT WIND SHIFT LINES AND POSSIBLY TAKING A COUPLE DEGREES OFF THE HIGH TEMPERATURE. FIRST POTENTIAL VERY S51OW "SURGE" COULD BE THURSDAY ACROSS THE SOUTHEAST CO PLAINS...HOWEVER...700MB TEMPERATURES SHOULD REMAIN +18C TO +23C ACROSS MUCH OF SOUTHERN CO. HIGH TEMPERATURES AROUND 100F WILL POSSIBLY CONTINUE AT PUB...LHX...AND PORTIONS OF SOUTHEAST CO PLAINS THURSDAY THROUGH SUNDAY. MEX MOS GUIDANCE FOR 4 RUNS NOW HAVING BEING PROMOTING 100-104F FROM PUB-LHX-LAA FOR WEDNESDAY THROUGH AT LEAST SAT. CONCEPTUALLY...VERY LOW GRADE MOISTURE WOULD BE AVAILABLE OVER THE MOUNTAINS/HIGH VALLEYS...THUS REQUIRING LOW POPS/WX. THE SHOWERS/THUNDERSTORMS WOULD MAINLY BE DIURNAL...IF THEY FORM AT ALL. TRYING TO GET SHOWERS AND THUNDERSTORMS INTO THE SOUTHEASTERN CO PLAINS MIGHT BE EVEN TOUGHER GIVEN WEAK STEERING CURRENTS. SURFACE-BASED INITIATION ACROSS THE SOUTHEASTERN CO PLAINS WILL BE EVEN TOUGHER GIVEN THE THERMAL CAPPING INVERSION...SO ANY PRECIPITATION THAT GETS INTO SOUTHEAST CO WOULD HAVE TO COME FROM THE MOUNTAINS AND POSSIBLY INITIATED FROM OUTFLOW BOUNDARIES...WHICH I`VE SEEN OCCUR. EVEN THE ECMWF...WHOS QPF ALWAYS SEEMS TO BE OVERDONE...DOESN`T HAVE MUCH AND CONFINES MOST OF THE LIGHT QPF OVER ITS VERSION OF THE MOUNTAINS. GIVEN THE LOW GRADE MOISTURE...THE OVERNIGHT AND EARLY MORNING HOURS SHOULD BE CLOUD- FREE AS THE CONVECTIVE DEBRIS CLOUDS DISSIPATE DURING THE EVENING...WITH THE AFTERNOON AND EARLY EVENING HAVING THE GREATER POTENTIAL FOR CLOUD COVER GIVEN MOIST CONVECTION. 17 AVIATION... SCATTERED THUNDERSTORMS POSSIBLE ACROSS MOST OF SOUTH CENTRAL AND SOUTHEAST COLORADO TODAY...WITH SHOWERS AND ISO T ALREADY ONGOING ALONG/WEST OF THE CONTDVD THIS MORNING. MVFR TO IFR CIGS WILL BE POSSIBLE WITH THE STRONGER STORMS THIS AFTERNOON AND EVENING...ALONG WITH HEAVY RAIN AND ERRATIC WIND GUSTS UP TO 50 MPH. THUNDERSTORMS WILL DECREASE FROM WEST TO EAST BETWEEN 00Z-09Z WITH CLEARING SKIES TOWARDS TUES MORNING. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 14/27 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 637 AM EDT MON JUL 28 2008 .SYNOPSIS... AN UPPER LEVEL LOW AND STALLED FRONT JUST OFFSHORE WILL BRING A FEW SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRY AND SEASONABLE WEATHER WITH LOWER HUMIDITY WILL PREVAIL TUE AND TUE NIGHT. DRY WEATHER WILL LINGER INTO A PORTION OF WED...BUT AN APPROACHING LOW PRESSURE SYSTEM WILL BRING A ROUND OF SHOWERS AND THUNDERSTORMS TO THE REGION LATE WED THROUGH THU. && .NEAR TERM /UNTIL 10 AM THIS MORNING/... LITTLE CHANGE TO THE CURRENT FORECAST PACKAGE...MODIFIED HOURLY TEMPS WITH THE RUC MODEL FOR A SLIGHTLY QUICKER WARMUP THIS MORNING. ANY LOW CLOUDS WILL CONTINUE TO BURN OFF QUICKLY THIS MORNING. && .SHORT TERM /10 AM THIS MORNING THROUGH 6 PM TUESDAY/... 28/00Z GFS HAS ISSUES WITH CONVECTIVE FEEDBACK...PRIMARILY THROUGH 18Z TODAY. SO LARGELY IGNORED IT DURING THIS TIME. 28/00Z NAM LOOKS TO HAVE A MUCH BETTER HANDLE ON PRECIPITATION THIS MORNING ANYWAY. THE BIG QUESTION THIS AFTERNOON WILL BE CONVECTIVE POTENTIAL. BEST MID LEVEL LAPSE RATES AND MID LEVEL DYNAMICS REMAIN TO THE NORTH OF I-90 TODAY...SO PLACED HIGHEST RISK OF SHOWERS AND THUNDERSTORMS IN THIS AREA. DECENT UPPER LEVEL DIVERGENCE AND MID LEVEL TROUGH SHOULD BE ENOUGH TO DEVELOP ISOLATED THUNDERSTORMS FARTHER SOUTH INTO NORTHERN CT AND SOUTHEAST MA THOUGH. CONVECTION DIES DOWN THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS SOUTHERN NEW ENGLAND TONIGHT. WEAK HIGH PRESSURE ARRIVES FOR TUESDAY WITH FAIR WEATHER. USED A BLEND OF THE LATEST MOS GUIDANCE FOR TEMPERATURES TODAY INTO TUESDAY. MAV GUIDANCE LOOKS A BIT WARM...PARTICULARLY AT THE HIGHER ELEVATION STATIONS LIKE WORCESTER TODAY...SO THIS BLEND LEANED MORE TOWARD THE MET GUIDANCE TODAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... AN UPPER LEVEL TROUGH PERSISTS ACROSS THE NORTHEAST THROUGH THE EXTENDED TIMEFRAME WITH PERIODIC UNSETTLED WEATHER. TUESDAY NIGHT...MAINLY CLEAR SKIES AND SEASONABLY COOL CONDITIONS PREVAIL. WEDNESDAY...SOME TIMING DIFFERENCES EXIST AMONGST THE MODELS REGARDING THE ARRIVAL TIME OF THE NEXT SHORT WAVE DISTURBANCE FROM THE OHIO VALLEY. THE GFS APPEARS TO BE SUFFERING FROM CONVECTIVE FEEDBACK ISSUES AS ITS SPURIOUS SHORT WAVE DISTURBANCE ACROSS THE GREAT LAKES BRINGS PRECIPITATION TO MUCH OF THE REGION BY WEDNESDAY AFTERNOON. PREFER THE LESS PROGRESSIVE ECMWF/UKMET AND NAM SOLUTIONS WITH RESPECT TO PRECIPITATION CHANCES WEDNESDAY. 21Z SREF SOLUTIONS APPEARED TO SUPPORT THIS. THEREFORE DECIDED TO GO WITH LOW CHANCE POPS WESTERN ZONES AND SLIGHT CHANCE OR LESS ELSEWHERE. USED A BLEND OF PREVIOUS OFFICIAL AND MOS GUIDANCE TEMPERATURES TO DERIVE HIGHS...AS 00Z MOS GUIDANCE APPEARED A BIT COOL. OTHERWISE MUCH OF THE DAY IS EXPECTED TO BE WARM AND DRY. WEDNESDAY NIGHT AND THURSDAY...CONTINUED THE MENTION OF CHANCE POPS AS WEAK SECONDARY LOW PRESSURE DEVELOPS OFF THE COAST AND ALONG AN OLD STALLED COLD FRONT. UNDERCUT MOS TEMPS A FEW DEGREES MAINLY ALONG THE COAST THURSDAY DUE TO LIGHT ONSHORE FLOW AND CONSIDERABLE CLOUDS. FRIDAY THROUGH SUNDAY...SOME LARGE DEVIATIONS OCCUR IN THE 500 MILLIBAR HEIGHT FIELDS IN TERMS OF THE AMPLITUDE AND PLACEMENT OF THE TROUGH AXIS. IN ADDITION THE TIMING OF EACH INDIVIDUAL SHORT WAVE WILL HAVE AN IMPACT ON THE OVERALL PRECIPITATION THREAT. GENERALLY RELIED ON AN ENSEMBLE BLEND WHICH WAS USED BY HPC AS WELL AS THE LATEST 00Z ECMWF. LOW CHANCE POPS WERE ADDED ALL THREE DAYS BUT IT IS EXPECTED TO BE RAIN FREE A PORTION OF THE TIME. TEMPERATURES ARE EXPECTED TO REMAIN NEAR OR SLIGHTLY BELOW SEASONAL NORMS. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AREAS OF MVFR/IFR IN FOG AND STRATUS WILL QUICKLY IMPROVE TO VFR AFTER DAYBREAK. SCATTERED CONVECTION THIS AFTERNOON WILL LEAD TO BRIEF PERIODS OF MVFR. VFR TONIGHT AS A COLD FRONT MOVES THROUGH SOUTHERN NEW ENGLAND. VFR TUESDAY WITH WEAK HIGH PRESSURE. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... TUE NIGHT...VFR. WED...VFR TO START THEN LOWERING TO MVFR ESPECIALLY AT NIGHT FROM WEST TO EAST. THU...MVFR IN PERIODS OF RAIN WITH A LOW RISK OF IFR BOS-PVD-HYA-ACK. FRI...CONDITIONS POSSIBLY IMPROVING TO MVFR OR VFR. && .MARINE... RELATIVELY LIGHT WINDS AND SEAS EXPECTED TODAY THROUGH TUESDAY. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... TUESDAY NIGHT THROUGH FRI...WINDS AND SEAS EXPECTED TO REMAIN BELOW SCA CRITERIA. VSBYS MAY BRIEFLY BE REDUCED WED NIGHT THROUGH THU NIGHT IN SHOWERS AND FOG PATCHES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...STRAUSS NEAR TERM...BELK/STRAUSS SHORT TERM...BELK LONG TERM...STRAUSS AVIATION...BELK/STRAUSS MARINE...BELK/STRAUSS ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 140 AM EDT MON JUL 28 2008 .SYNOPSIS... A COLD FRONT WILL MOVE OFF TO OUR EAST DURING THE PREDAWN HOURS AND WEAKEN TODAY. HOWEVER...AN UPPER LEVEL DISTURBANCE WILL MOVE OVER THE REGION TODAY TRIGGERING ISOLATED TO SCATTERED CONVECTION ESPECIALLY ACROSS THE HIGHER TERRAIN. WEAK HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION TUESDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... OVERALL...ERN NY AND WRN NEW ENGLAND IS MUCH QUIETER THAN EARLIER TODAY WITH SOME ISOLD SHRA/TSRA ACTIVITY SOUTH OF LAKE ONTARIO AND OVER NRN NY AND VT...AS THE SFC COLD FRONT SLOWLY MOVES SOUTHEAST ACROSS NY AND NEW ENGLAND. WE KEPT SLIGHT TO LOW CHANCE POPS OVER LOCATIONS NW OF THE CAPITAL REGION DUE TO THE UPSTREAM RADAR COVERAGE. THE RUC40KM MODEL DOES SHOW A MID LEVEL VORT MAX TIED TO THIS SCT CONVECTION. WE LEFT SOME SLIGHT CHANCE POPS IN OVER THE SRN TIER WITH ISOLD SHRAS THERE. THIS ACTIVITY SHOULD DIMINISH AROUND MIDNIGHT. VARIABLE CLOUDINESS AND PATCHY FOG IS POSSIBLE OVER THE REGION. IT LOOKS LIKE DRIER AIR WILL FILTER INTO THE FCST AREA TOWARDS 1200 UTC WITH THE UPPER LEVEL TROUGH AXIS APPROACHING. OVERALL...THE COLD AIR ADVECTION IS FAIRLY WEAK...BUT SFC DEWPTS SHOULD FALL BACK INTO THE 50S TOMORROW MORNING. MIN TEMPS WERE SLIGHTLY ADJUSTED BY TRENDS AND THE 1800 UTC GMOS GUIDANCE. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... COLD FRONTAL BOUNDARY WEAKENS OFF TO OUR EAST. SHORT WAVE MOVES THROUGH LONGWAVE TROUGH. ALONG WITH DAYTIME HEATING ISOLATED TO SCATTERED CONVECTION WILL OCCUR PARTICULARLY ACROSS THE HIGHER TERRAIN. CONVECTION WILL DIMINISH DURING THE EVENING WITH THE LOSS OF HEATING AND WITH THE TROUGH AXIS SHIFTING OFF TO THE EAST. MINOR HEIGHTS RISE MONDAY NIGHT INTO TUESDAY AS WEAK RIDGING BUILDS IN. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... FOLLOWED HPC CLOSELY FOR EXTENDED PERIOD. THE MODELS AGREE ON THE LONGWAVE PATTERN MAINTAIN TROUGH OVER THE EASTERN NORTH AMERICA. THE RIDGE OVER THE SOUTHWEST AND PLAINS SHOULD EXPANDS EAST TO THE MISSISSIPPI VALLEY BY NEXT WEEKEND. ANOTHER UPPER LOW EXPECTED TO DEVELOP THIS WEEK OVER EASTERN CANADA. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... FLIGHT CONDITIONS HAVE DETERIORATED TO MVFR AT KGFL AND TO IFR AT KALB AND KPOU DURING THE LATE EVENING HOURS WITH LOW CEILINGS AND THE VISIBILITY AT KALB WAS DOWN TO 2 MILES AS WELL. IN THE MEANTIME A CLUSTER OF SHOWERS AND THUNDERSTORMS WERE MOVING DOWN THE MOHAWK VALLEY. THEY WERE SHOWING SOME SIGNS OF WEAKENING AS THEY CONTINUED EAST. THE GOOD NEWS IS THERE MAY BE ENOUGH OF AN IMPULSE LEFT TO STIR OUT SOME OF THE FOG AND STRATUS. WINDS WERE LIGHT FROM THE SOUTH OR CALM OVER THE FORECAST AREA. FLIGHT CONDITIONS SHOULD IMPROVE TO VFR SHORTLY AFTER SUNRISE AT LEAST IN THE HUDSON...MOHAWK...AND HOUSATONIC VALLEYS WITH SCT TO BKN CU/STRATOCU AROUND 5000 FT...WITH AREAS OF MVFR CIGS OVER HIGHER TERRAIN OF THE ADIRONDACKS ALONG WITH SOME WIDELY SCT -SHRA/TSRA DURING THE AFTERNOON. WINDS TODAY WILL GENERALLY BE SW 8 TO 12 KTS. OUTLOOK... TONITE...VFR...POSSIBLY LCLLY MVFR DUE TO MIST. TUE...VFR...NO SIG WX. WED-THU...VFR/MVFR SCT SHRA/TSRA. FRI...VFR/MVFR...SCT SHRA. && .FIRE WEATHER... A COLD FRONT WILL MOVE OFF TO OUR EAST TONIGHT AND WEAKEN MONDAY. HOWEVER...AN UPPER LEVEL DISTURBANCE WILL OVER THE REGION MONDAY TRIGGERING DIURNAL CONVECTION ESPECIALLY ACROSS THE HIGHER TERRAIN. RELATIVE HUMIDITY VALUES WILL RECOVER TO NEAR 100 PERCENT TONIGHT AND DROP TO MINIMUMS OF 45 TO 55 PERCENT MONDAY AFTERNOON WITH 55 TO 65 PERCENT ACROSS THE TERRAIN. && .HYDROLOGY... A FEW RIVERS WERE IMPACTED BY THE HEAVY RAINS SAT/SUN AND SHOWED SHARP RISES...INCLUDING THE HEADWATERS OF THE SCHOHARIE CREEK WHICH CAME UP 2 FT SAT NIGHT...AND THEN ANOTHER 2 FT FROM A SECOND STORM SUNDAY AFTERNOON. EAST OF THE HUDSON THE HOOSIC AND BATTENKILL BOTH CAME UP MORE THAN 3 FT...WITH THE HUDSON RIVER GETTING WITHIN A FOOT OF FLOOD IN THE SCHUYLERVILLE AND STILLWATER AREAS. THERE WAS ALSO A 2 FT RISE ON THE HOUSATONIC. RIVERS WILL RECEDE TODAY AS SHOWERS AND THUNDER STORMS TODAY ARE NOT EXPECTED TO BRING HEAVY RAINFALL. THE NEXT SIGNIFICANT RAINFALL WILL PROBABLY COME WEDNESDAY INTO THURSDAY...WITH 0.5 TO 1.0 INCH OF RAIN...ALTHOUGH SOME HIGHER AMOUNTS COULD OCCUR FROM CONVECTION. THIS STORM SHOULD NOT CAUSE PROBLEMS ON THE RIVERS...BUT WITH CONVECTION IN THE PICTURE...LOCALIZED FLOODING OF ROADS/PARKING AREAS COULD OCCUR. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...RCK NEAR TERM...TAW SHORT TERM...IAA LONG TERM...IAA AVIATION...RCK FIRE WEATHER...IAA/11 HYDROLOGY...RCK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 314 PM CDT TUE JUL 29 2008 .DISCUSSION... 311 PM CDT THERE IS A CHANCE OF THUNDERSTORMS TONIGHT AND WEDNESDAY. SOME OF THE THUNDERSTORMS MAY PRODUCE SMALL HAIL AND HEAVY RAINS. THE HIGH TEMPERATURES ARE FORECAST TO BE IN THE UPPER 90S SATURDAY AND SUNDAY. THERE MAY SOME DANGEROUS HEAT INDEX FOR THOSE DAYS. A SURFACE TROUGH WILL MOVE INTO ILLINOIS THIS EVENING. THIS IS A WIND SHIFT LINE THAT MAY BE A RESULT OF AGEOSTROPHIC CIRCULATION FROM THE APPROACHING 500 MB TROUGH OVER KANSAS AND OKLAHOMA. THIS TROUGH CAN BE SEEN ON THE VISIBLE SATELLITE IMAGERY AS A CIRCULATION. THE VERTICAL MOTION FROM THIS THE ADJUSTMENT CAN BE INFERRED BY THE POTENTIAL TEMPERATURE CHANGES AS THE VORTICITY MAXIMUM MOVES INTO MISSOURI AND ILLINOIS. THERE IS SOME INSTABILITY AS THE LEVEL OF FREE CONVECTION IS AROUND 6,977 FEET AS SEEN ON THE FORECAST SOUNDING AT 2 AM CDT. THE LIFTED CONDENSATION LEVEL IS FORECAST TO BE AROUND 1,858 FEET. THE INSTABILITY IS RATHER DEEP. WE WILL KEEP THE THUNDERSTORM CHANCES TONIGHT WITH THE HIGHEST PROBABILITY BEFORE AND DURING WEDNESDAY MORNING. WE EXPECT SCATTERED THUNDERSTORMS. A COLD FRONT WILL MOVE SOUTH INTO NORTHERN ILLINOIS BY LATE WEDNESDAY MORNING. WE USED THE 12 UTC RUN OF LOCAL WRF MODEL AND 12 UTC RUN OF THE NAM MODELS. FOR WEDNESDAY THIS FRONT WILL WASH OUT OVER NORTHERN ILLINOIS. THERE MAY BE ENOUGH LIFT FOR A CHANCE OF THUNDERSTORMS WEDNESDAY. THE HIGH TEMPERATES ARE EXPECTED TO CLIMB INTO THE UPPER 80S WEDNESDAY AND THURSDAY. THE WEEKEND WILL BE SIGNIFICANT WITH VERY WARM AND HUMID AIR OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE GFS MODEL SHOW A LARGE 500 MB RIDGE OVER NORTHERN ILLINOIS SATURDAY. THIS LESSER DENSE AIR INDICATES VERY HIGH TEMPERATURES. WE HAVE FORECAST THE HIGH TEMPERATURES IN THE UPPER 90S FOR SATURDAY AND SUNDAY. THIS WILL GIVE HEAT INDEX AROUND 100 IN SOME LOCATIONS. WE WILL MONITOR THIS FORECAST FOR POSSIBLE HEAT ADVISORIES AND WARNINGS FOR THE WEEKEND. && .AVIATION... 1236 PM CDT FOR 18Z TAFS...MAIN CONCERN IS WINDS IN SHORT TERM AND CONVECTION POTENTIAL AT TERMINALS NEXT 18 HOURS. RELATIVELY STRONG...FOR LATE JULY...MID LEVEL CIRCULATION NOTED IN RAOB/PROFILER/VAPOR DATA MOVING ACROSS LAKE WINNIPEG AREA OF SOUTHEAST MANITOBA EARLY THIS AFTERNOON. MODEL GUIDANCE IN GOOD AGREEMENT IN CONTINUING TO MOVE THIS FEATURE EAST THROUGH WEDNESDAY MORNING WITH BEST MID LEVEL FORCING/HEIGHT FALLS TRANSLATING ACROSS THE NORTHERN GREAT LAKES. RESULTING SURFACE PRESSURE FALLS ALSO FOCUSED FROM NORTH CENTRAL WI TO LAKE SUPERIOR THIS AFTERNOON... WITH WEAKER SOUTHEASTERLY GRADIENT ACROSS FORECAST AREA EXPECTED TO TIGHTEN A BIT AND BECOME MORE SOUTHERLY WITH TIME. HIGHER RESOLUTION SHORT TERM GUIDANCE INCLUDING NAM/RUC AND LOCALLY RUN NAM ALL SUGGEST CURRENT SOUTHEAST FLOW/LAKE BREEZE WILL BE OVERCOME BY SOUTHERLY WINDS BY MID AFTERNOON. MAIN AREA OF LOW PRESSURE MOVING THROUGH ONTARIO OVERNIGHT/WEDNESDAY TRAILS ACTUAL COLD FRONT ACROSS FORECAST AREA DURING THE MORNING HOURS WEDNESDAY...THOUGH GUIDANCE SUGGESTS MORE OF A BROAD PRESSURE TROUGH AND GRADUAL WIND SHIFT FROM SOUTHWEST TO WESTERLY WEDNESDAY MORNING. TRUE FROPA APPEARS 14-16Z WITH WIND VEERING MORE NORTHWEST. WITH RESPECT TO THUNDERSTORM POTENTIAL...UPSTREAM MORNING RAOBS INDICATE RELATIVELY STEEP LAPSE RATES ABOVE 800 HPA OR SO...THOUGH RECENT ACARS ASCENT SOUNDINGS FROM KORD/KRFD DEPICT MORE STABLE THERMAL PROFILES FARTHER TO THE EAST. RUC/LOCAL NAM FORECAST SOUNDINGS CONTINUE TO INDICATE RATHER MARGINAL LOW LEVEL LAPSE RATES THROUGH THE AFTERNOON WHICH SUGGESTS ORGANIZED CONVECTION MAY HAVE A TOUGH TIME DEVELOPING ACROSS TERMINALS. RADAR TRENDS HAVE INDICATED A FEW RW/TRW THIS MORNING FROM IA/MO BORDER REGION INTO WESTERN IL IN ISENTROPIC ASCENT REGION ALONG AXIS OF WEAK 20 KNOT LOW LEVEL JET. 15Z SURFACE ANALYSIS INDICATES WEAK WARM FRONTAL FEATURE FROM SOUTHEAST IA TO NEAR KSTL...WITH 925-850 HPA THERMAL GRADIENT/ELEVATED WARM FRONT FROM IA TO CENTRAL IL WHICH HAS LIKELY BEEN AIDING DEVELOPMENT OF ISOLATED CONVECTION...THOUGH THESE FEATURES APPEAR TO BECOME MORE DIFFUSE WITH TIME PER RUC/NAM FORECASTS. THUS WHILE ISOLATED/SCATTERED CONVECTION LIKELY TO OCCUR NEAR AND ESPECIALLY WEST/SOUTHWEST OF TERMINALS THIS AFTERNOON... LACK OF CLEAR LOW LEVEL FORCING/FOCUS YIELDS CONFIDENCE TOO LOW FOR POINT FORECAST TAF INCLUSION AT THIS TIME. HAVE ELECTED HOWEVER TO MENTION A VCSH WITH CB CLOUD GROUP FOR KRFD DURING PEAK DIURNAL HEATING LATER THIS AFTERNOON. FWC/MET GUIDANCE SUGGESTS SOME MVFR HAZE BEFORE/AROUND SUNRISE AND THIS APPEARS REASONABLE GIVEN SURFACE DEW POINT TEMPS IN LOWER 70S AND LIGHT SURFACE WINDS. RATZER && .MARINE... 303 PM CDT RELATIVELY DEEP LOW PRESSURE ACROSS WESTERN ONTARIO FOR LATE JULY WILL CONTINUE TO TRACK EASTWARD NORTH OF LAKE SUPERIOR TONIGHT INTO EARLY WEDNESDAY...AND INTO SOUTHERN QUEBEC WEDNESDAY NIGHT. IN THE PROCESS...A TRAILING COLD FRONT WILL MOVE SOUTHEAST ACROSS NORTHERN LAKE MICHIGAN LATE TONIGHT...AND SAG ACROSS SOUTHERN LAKE MICHIGAN WEDNESDAY. SURFACE PRESSURE FALLS ACROSS THE NORTHERN LAKES IN ADVANCE OF THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ESPECIALLY OVER NORTHERN LAKE MICHIGAN THIS EVENING...RESULTING IN STRENGTHENING SOUTHERLY WINDS OVERNIGHT. WINDS WILL THEN SHIFT TO THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT WEDNESDAY...WITH THE GRADIENT QUICKLY DECREASING AS WEAK HIGH PRESSURE MOVES INTO THE WESTERN LAKES WEDNESDAY NIGHT AND THURSDAY. THIS HIGH WILL MOVE SOUTHEAST OF THE LAKE BY SATURDAY...WITH SOUTHERLY FLOW RETURNING AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS. THIS LOW WILL WEAKEN BY EARLY SUNDAY AS ANOTHER LOW PUSHES ACROSS CENTRAL CANADA...AND DRAGS ANOTHER COLD FRONT SOUTHEAST ACROSS THE WESTERN LAKES. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 303 PM CDT TUE JUL 29 2008 .DISCUSSION... 320 AM CDT MAIN CONCERNS FOR THE SHORT TERM WILL FOCUS ON INCREASING HEAT/HUMIDITY AND THUNDER POTENTIAL. THE REGION WILL SEE A RETURN OF TEMPERATURES APPROACHING...AND IN SOME LOCATIONS...EXCEEDING 90 DEGREES TODAY. WITH 850MB TEMPS APPROACHING 20C BY THIS AFTERNOON UNDER A BROAD...BUILDING RIDGE ALOFT...FEEL CONFIDENT THAT MANY LOCATIONS SHOULD SEE 90F TODAY...PARTICULARLY URBANIZED AREAS...AS THERE SHOULD BE LITTLE CLOUDINESS THROUGH THE AFTERNOON TO IMPEDE INSOLATION. WHILE THE GFS BASED MOS PRODUCTS WANT TO BRING ORD/RFD UP TO 93F TODAY...THE NAM BASED GUIDANCE IS MUCH LOWER...ONLY IN THE MIDDLE 80S. THE MAIN DIFFERENCE BETWEEN THESE TWO MODELS IN HOW THEY HANDLE THEIR RESPECTIVE LOW LEVEL MOISTURE FIELDS. THE NAM IS MOISTER...THUS RETARDING THE HEATING...WHILE THE GFS IS DRIER...ALLOWING TEMPS TO CLIMB HIGHER. BASED ON UPSTREAM TRENDS IN LATEST SFC ANALYSIS...FEEL THAT THE MOISTER NAM BASED GUIDANCE IS THE WAY TO GO AND HAVE INCREASED TEMPS A BIT OVER THE GOING FORECAST. HAVE CARRIED THIS IDEA THROUGH THE REMAINDER OF THE SHORT TERM PERIOD AND INTO THE LONGER TERM FORECAST PERIOD... GENERALLY RAISING TEMPS FOR THE GOING FORECAST...INCLUDING WIDESPREAD LOW 90S FOR THE COMING WEEKEND. WITH THE 00Z GFS INDICATING 850MB TEMPS CLIMBING TO 23C...LOW 90S COULD EVEN BE CONSERVATIVE. AS FOR THUNDER POTENTIAL FOR LATER TODAY...HAVE DROPPED ANY MENTION OF POPS OVER THE ENTIRE CWA BEFORE 18Z AND WILL SLOW THE PROGRESSION OF PCPN ACROSS THE CWA FOR 18Z-00Z PERIOD...REMOVING POPS FROM THE ERN SECTIONS...PARTICULARLY THE NWRN INDIANA COUNTIES...THRU 00Z. MODEL SOUNDING INDICATE SOME WEAK CAPPING OVER THE ERN LOCATIONS...BUT A DEVELOPING WARM FRONTAL BOUNDARY CROSSING THE MISSISSIPPI RIVER INTO NWRN IL LATE THIS AFTERNOON SHOULD PROVIDE ADEQUATE FOCUS FOR TS DEVELOPMENT OVER THE FAR WRN PORTIONS OF THE CWA LATE THIS AFTERNOON. THE NAM HAS SHOWN GOOD CONTINUITY ON HANDLING THIS FEATURE AND THE ASSOCIATED MID LEVEL SHORT WAVE MOVING ACROSS NRN IL THIS EVENING...SO HAVE TRENDED TOWARD THIS SOLUTION FOR TIMING OF SWEEPING POPS ACROSS THE AREA TONIGHT. HAVE LIMITED POPS TO HIGHER END CHANCE AS THERE IS STILL A CHANCE FOR A SPLIT IN THE MOST INTENSE AND MOST ORGANIZED CONVECTION AS THE SYSTEM CURRENTLY OVER THE SOUTH HIGH PLAINS LOOKS TO BE TRENDING MORE SOUTHERLY...OVER CNTRL AND SRN ILLINOIS...WHILE THE NRN STREAM MCS ACTIVITY WILL LIKELY AFFECT WISCONSIN. HOWEVER...THE ENVIRONMENT WILL HAVE ADEQUATE OF HEAT AND HUMIDITY IN PLACE TO JUSTIFY THE POP FORECAST. TEMPS SHOULD MODERATE A BIT BY THURSDAY AS A STRONG UPPER LOW CROSSES SRN CANADA...TURNING UPPER FLOW MORE NWLY...BUT STRONG RIDGING WILL QUICKLY BUILD IN BEHIND...BRINGING A SIGNIFICANT WARM UP FOR FRIDAY AND INTO THE WEEKEND. KREIN && .AVIATION... 1236 PM CDT FOR 18Z TAFS...MAIN CONCERN IS WINDS IN SHORT TERM AND CONVECTION POTENTIAL AT TERMINALS NEXT 18 HOURS. RELATIVELY STRONG...FOR LATE JULY...MID LEVEL CIRCULATION NOTED IN RAOB/PROFILER/VAPOR DATA MOVING ACROSS LAKE WINNIPEG AREA OF SOUTHEAST MANITOBA EARLY THIS AFTERNOON. MODEL GUIDANCE IN GOOD AGREEMENT IN CONTINUING TO MOVE THIS FEATURE EAST THROUGH WEDNESDAY MORNING WITH BEST MID LEVEL FORCING/HEIGHT FALLS TRANSLATING ACROSS THE NORTHERN GREAT LAKES. RESULTING SURFACE PRESSURE FALLS ALSO FOCUSED FROM NORTH CENTRAL WI TO LAKE SUPERIOR THIS AFTERNOON... WITH WEAKER SOUTHEASTERLY GRADIENT ACROSS FORECAST AREA EXPECTED TO TIGHTEN A BIT AND BECOME MORE SOUTHERLY WITH TIME. HIGHER RESOLUTION SHORT TERM GUIDANCE INCLUDING NAM/RUC AND LOCALLY RUN NAM ALL SUGGEST CURRENT SOUTHEAST FLOW/LAKE BREEZE WILL BE OVERCOME BY SOUTHERLY WINDS BY MID AFTERNOON. MAIN AREA OF LOW PRESSURE MOVING THROUGH ONTARIO OVERNIGHT/WEDNESDAY TRAILS ACTUAL COLD FRONT ACROSS FORECAST AREA DURING THE MORNING HOURS WEDNESDAY...THOUGH GUIDANCE SUGGESTS MORE OF A BROAD PRESSURE TROUGH AND GRADUAL WIND SHIFT FROM SOUTHWEST TO WESTERLY WEDNESDAY MORNING. TRUE FROPA APPEARS 14-16Z WITH WIND VEERING MORE NORTHWEST. WITH RESPECT TO THUNDERSTORM POTENTIAL...UPSTREAM MORNING RAOBS INDICATE RELATIVELY STEEP LAPSE RATES ABOVE 800 HPA OR SO...THOUGH RECENT ACARS ASCENT SOUNDINGS FROM KORD/KRFD DEPICT MORE STABLE THERMAL PROFILES FARTHER TO THE EAST. RUC/LOCAL NAM FORECAST SOUNDINGS CONTINUE TO INDICATE RATHER MARGINAL LOW LEVEL LAPSE RATES THROUGH THE AFTERNOON WHICH SUGGESTS ORGANIZED CONVECTION MAY HAVE A TOUGH TIME DEVELOPING ACROSS TERMINALS. RADAR TRENDS HAVE INDICATED A FEW RW/TRW THIS MORNING FROM IA/MO BORDER REGION INTO WESTERN IL IN ISENTROPIC ASCENT REGION ALONG AXIS OF WEAK 20 KNOT LOW LEVEL JET. 15Z SURFACE ANALYSIS INDICATES WEAK WARM FRONTAL FEATURE FROM SOUTHEAST IA TO NEAR KSTL...WITH 925-850 HPA THERMAL GRADIENT/ELEVATED WARM FRONT FROM IA TO CENTRAL IL WHICH HAS LIKELY BEEN AIDING DEVELOPMENT OF ISOLATED CONVECTION...THOUGH THESE FEATURES APPEAR TO BECOME MORE DIFFUSE WITH TIME PER RUC/NAM FORECASTS. THUS WHILE ISOLATED/SCATTERED CONVECTION LIKELY TO OCCUR NEAR AND ESPECIALLY WEST/SOUTHWEST OF TERMINALS THIS AFTERNOON... LACK OF CLEAR LOW LEVEL FORCING/FOCUS YIELDS CONFIDENCE TOO LOW FOR POINT FORECAST TAF INCLUSION AT THIS TIME. HAVE ELECTED HOWEVER TO MENTION A VCSH WITH CB CLOUD GROUP FOR KRFD DURING PEAK DIURNAL HEATING LATER THIS AFTERNOON. FWC/MET GUIDANCE SUGGESTS SOME MVFR HAZE BEFORE/AROUND SUNRISE AND THIS APPEARS REASONABLE GIVEN SURFACE DEW POINT TEMPS IN LOWER 70S AND LIGHT SURFACE WINDS. RATZER && .MARINE... 303 PM CDT RELATIVELY DEEP LOW PRESSURE ACROSS WESTERN ONTARIO FOR LATE JULY WILL CONTINUE TO TRACK EASTWARD NORTH OF LAKE SUPERIOR TONIGHT INTO EARLY WEDNESDAY...AND INTO SOUTHERN QUEBEC WEDNESDAY NIGHT. IN THE PROCESS...A TRAILING COLD FRONT WILL MOVE SOUTHEAST ACROSS NORTHERN LAKE MICHIGAN LATE TONIGHT...AND SAG ACROSS SOUTHERN LAKE MICHIGAN WEDNESDAY. SURFACE PRESSURE FALLS ACROSS THE NORTHERN LAKES IN ADVANCE OF THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ESPECIALLY OVER NORTHERN LAKE MICHIGAN THIS EVENING...RESULTING IN STRENGTHENING SOUTHERLY WINDS OVERNIGHT. WINDS WILL THEN SHIFT TO THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT WEDNESDAY...WITH THE GRADIENT QUICKLY DECREASING AS WEAK HIGH PRESSURE MOVES INTO THE WESTERN LAKES WEDNESDAY NIGHT AND THURSDAY. THIS HIGH WILL MOVE SOUTHEAST OF THE LAKE BY SATURDAY...WITH SOUTHERLY FLOW RETURNING AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS. THIS LOW WILL WEAKEN BY EARLY SUNDAY AS ANOTHER LOW PUSHES ACROSS CENTRAL CANADA...AND DRAGS ANOTHER COLD FRONT SOUTHEAST ACROSS THE WESTERN LAKES. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1226 PM CDT MON JUL 28 2008 .DISCUSSION... ISSUED 1020 AM CDT MON JUL 28 2008 DECAYING THUNDERSTORM COMPLEX FROM OVERNIGHT LARGELY STAYING ALONG AND WEST OF THE MISSISSIPPI RIVER. ASSOCIATED CLOUD SHIELD STARTING TO ERODE...ESPECIALLY ACROSS EAST CENTRAL AND SOUTHEAST ILLINOIS. MAIN QUESTION FOR THE DAY WILL BE THE EXTENT OF SUNSHINE...WITH INTERACTION WITH ANY LEFTOVER BOUNDARIES FROM RECENT CONVECTION TO DEVELOP NEW THUNDERSTORMS. WEAK FLOW TO CONTINUE ACROSS THE AREA THIS AFTERNOON. RUC-13 MODEL SHOWS A WEAK BOUNDARY MOVING SOUTHEAST THROUGH THE CWA...BUT IS NOT ALL THAT BULLISH ABOUT DEVELOPING ANY PRECIPITATION EXCEPT FOR SOME STORMS TOWARD LATE AFTERNOON IN SOUTH CENTRAL ILLINOIS. ETA-12 ALSO NOT REALLY SHOWING ANYTHING RAIN-WISE. CAN`T NECESSARILY RULE OUT ANY ISOLATED CONVECTION ANYWHERE THOUGH IN THIS SORT OF PATTERN...SO WILL HANG ON TO 20 PERCENT POPS FOR THE AFTERNOON. EXTRAPOLATION OF CLEARING LINE FROM IOWA HAS IT REACHING THE I-55 CORRIDOR TOWARD 18Z. ALTHOUGH CURRENT HOURLY TEMPERATURE TRENDS RUNNING BEHIND ORIGINAL FORECAST...THINK THERE WILL BE ENOUGH AFTERNOON SUN TO KEEP HIGH TEMPERATURES FAIRLY CLOSE TO THE ORIGINAL VALUES...BUT WILL DROP THEM A DEGREE OR TWO WITH THE LINGERING CLOUDS. UPDATED ZONES/GRIDS OUT BY 1045 AM. GEELHART && .AVIATION... ISSUED 1225 PM CDT MON JUL 28 2008 NARROW BAND OF MVFR CEILINGS HAS BEEN STREAMING SOUTHEAST ACROSS THE KPIA/KBMI TERMINALS THIS MORNING...ALTHOUGH CLOUDS HAVE BEEN ERODING UPSTREAM OF GALESBURG. KEPT THESE LOWER CLOUDS IN FOR A COUPLE HOURS AT THE BEGINNING OF THE TAF FORECAST PERIOD...WITH SOME TEMPO PERIODS AT KCMI AS WELL ALONG THIS TRAJECTORY. AREAS AROUND KSPI/KDEC HAVE LARGELY REMAINED OUTSIDE OF THESE LOWER CLOUDS EXCEPT FOR BRIEF PERIODS. CONTINUED WITH THE SMALL THUNDER CHANCES DURING THE LATE AFTERNOON UNTIL NEAR SUNSET. OVERNIGHT CONVECTION WILL LIKELY BE MORE TOWARD SUNRISE IF IT OCCURS. DEPENDING ON THE AMOUNT OF ASSOCIATED CLOUDS AHEAD OF INCOMING STORMS...SOME LIGHT FOG WILL AGAIN BE POSSIBLE IN THE VICINITY OF SUNRISE. GEELHART && .PREV DISCUSSION... ISSUED 208 AM CDT MON JUL 28 2008 OVERNIGHT CONVECTION CONFINED TO THE SE PART OF THE FORECAST AREA AT 02Z. ALSO MCV SHOWING UP NICELY ON RADAR LOOPS ACROSS THE SE. MCS HAS DEVELOPED ACROSS SOUTHERN IA AND NE MO. ALTHOUGH IT LOOKS LIKE THIS AREA OF CONVECTION WILL TRACK SW OF THE FORECAST AREA...SOME OUTFLOW BOUNDARIES COULD KICK OFF PRECIPITATION ACROSS CENTRAL IL TODAY. THE MCS HAS PUSHED THE FRONTAL BOUNDARY A BIT TO THE WEST OVERNIGHT...INTO CENTRAL MO. STILL IN NW FLOW...WITH RIDGE TO THE W AND TROF TO THE E. MODELS ARE IN DECENT AGREEMENT IN THE SHORT TERM. MEX GUIDANCE A TAD TOO WARM...ALTHOUGH HIGHS IN THE SE HAVE COME DOWN SOME FROM YESTERDAYS RUN. SHORT TERM...TODAY THROUGH WED NIGHT BOTH NAM AND GFS LIFT WARM FRONT NORTH...THROUGH CENT IL DURING THE DAY ON MONDAY. KEPT POPS GOING DURING THE DAY TODAY...WITH THIS FRONTAL PASSAGE. THE GFS TRIES TO DEVELOP AN MCS ACROSS SOUTHERN IL AND IN TUES MORNING...NAM IS DRY AT THIS TIME. THE NAM HAD A MUCH BETTER PLACEMENT OF THE MCS ACROSS MO/IL TODAY WITH YESTERDAY EVENINGS MODEL RUN...WHILE THE GFS WAS TOO FAR NORTH. THEREFORE...I HAVE A LITTLE MORE CONFIDENCE IN THE NAM SOLUTION. MODELS ARE ALL IN AGREEMENT WITH DEVELOPING AN UPPER LEVEL LOW ACROSS THE PLAINS...AND TRACKING IT ACROSS ILLINOIS ON TUE NIGHT. COLD FRONT ALSO DROPS SOUTH AND STALLS OUT ACROSS IL ON TUE NIGHT...RESULTING IN MORE CHANCES FOR RAIN TUES NIGHT/WED MORNING. LONG TERM...THU THROUGH SAT FRONT SLOWLY DRIFTS SOUTH OF THE AREA WED NIGHT AND THU. HIGH PRESSURE RIDGE MOVES IN AT THE SFC...TRYING TO DRY THINGS OUT. HOWEVER IN THE UPPER LEVEL NW FLOW PATTERN...SHORTWAVES COULD STILL TRACK OVER THE RIDGE...BRINGING CHANCES OF PRECIPITATION...HOWEVER WL LEAVE THE FORECAST DRY FOR NOW. NO MAJOR CHANGES TO THE FORECAST PAST FRIDAY. KELLY && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1020 AM CDT MON JUL 28 2008 .DISCUSSION... DECAYING THUNDERSTORM COMPLEX FROM OVERNIGHT LARGELY STAYING ALONG AND WEST OF THE MISSISSIPPI RIVER. ASSOCIATED CLOUD SHIELD STARTING TO ERODE...ESPECIALLY ACROSS EAST CENTRAL AND SOUTHEAST ILLINOIS. MAIN QUESTION FOR THE DAY WILL BE THE EXTENT OF SUNSHINE...WITH INTERACTION WITH ANY LEFTOVER BOUNDARIES FROM RECENT CONVECTION TO DEVELOP NEW THUNDERSTORMS. WEAK FLOW TO CONTINUE ACROSS THE AREA THIS AFTERNOON. RUC-13 MODEL SHOWS A WEAK BOUNDARY MOVING SOUTHEAST THROUGH THE CWA...BUT IS NOT ALL THAT BULLISH ABOUT DEVELOPING ANY PRECIPITATION EXCEPT FOR SOME STORMS TOWARD LATE AFTERNOON IN SOUTH CENTRAL ILLINOIS. ETA-12 ALSO NOT REALLY SHOWING ANYTHING RAIN-WISE. CAN`T NECESSARILY RULE OUT ANY ISOLATED CONVECTION ANYWHERE THOUGH IN THIS SORT OF PATTERN...SO WILL HANG ON TO 20 PERCENT POPS FOR THE AFTERNOON. EXTRAPOLATION OF CLEARING LINE FROM IOWA HAS IT REACHING THE I-55 CORRIDOR TOWARD 18Z. ALTHOUGH CURRENT HOURLY TEMPERATURE TRENDS RUNNING BEHIND ORIGINAL FORECAST...THINK THERE WILL BE ENOUGH AFTERNOON SUN TO KEEP HIGH TEMPERATURES FAIRLY CLOSE TO THE ORIGINAL VALUES...BUT WILL DROP THEM A DEGREE OR TWO WITH THE LINGERING CLOUDS. UPDATED ZONES/GRIDS OUT BY 1045 AM. GEELHART && .PREV DISCUSSION... ISSUED 208 AM CDT MON JUL 28 2008 OVERNIGHT CONVECTION CONFINED TO THE SE PART OF THE FORECAST AREA AT 02Z. ALSO MCV SHOWING UP NICELY ON RADAR LOOPS ACROSS THE SE. MCS HAS DEVELOPED ACROSS SOUTHERN IA AND NE MO. ALTHOUGH IT LOOKS LIKE THIS AREA OF CONVECTION WILL TRACK SW OF THE FORECAST AREA...SOME OUTFLOW BOUNDARIES COULD KICK OFF PRECIPITATION ACROSS CENTRAL IL TODAY. THE MCS HAS PUSHED THE FRONTAL BOUNDARY A BIT TO THE WEST OVERNIGHT...INTO CENTRAL MO. STILL IN NW FLOW...WITH RIDGE TO THE W AND TROF TO THE E. MODELS ARE IN DECENT AGREEMENT IN THE SHORT TERM. MEX GUIDANCE A TAD TOO WARM...ALTHOUGH HIGHS IN THE SE HAVE COME DOWN SOME FROM YESTERDAYS RUN. SHORT TERM...TODAY THROUGH WED NIGHT BOTH NAM AND GFS LIFT WARM FRONT NORTH...THROUGH CENT IL DURING THE DAY ON MONDAY. KEPT POPS GOING DURING THE DAY TODAY...WITH THIS FRONTAL PASSAGE. THE GFS TRIES TO DEVELOP AN MCS ACROSS SOUTHERN IL AND IN TUES MORNING...NAM IS DRY AT THIS TIME. THE NAM HAD A MUCH BETTER PLACEMENT OF THE MCS ACROSS MO/IL TODAY WITH YESTERDAY EVENINGS MODEL RUN...WHILE THE GFS WAS TOO FAR NORTH. THEREFORE...I HAVE A LITTLE MORE CONFIDENCE IN THE NAM SOLUTION. MODELS ARE ALL IN AGREEMENT WITH DEVELOPING AN UPPER LEVEL LOW ACROSS THE PLAINS...AND TRACKING IT ACROSS ILLINOIS ON TUE NIGHT. COLD FRONT ALSO DROPS SOUTH AND STALLS OUT ACROSS IL ON TUE NIGHT...RESULTING IN MORE CHANCES FOR RAIN TUES NIGHT/WED MORNING. LONG TERM...THU THROUGH SAT FRONT SLOWLY DRIFTS SOUTH OF THE AREA WED NIGHT AND THU. HIGH PRESSURE RIDGE MOVES IN AT THE SFC...TRYING TO DRY THINGS OUT. HOWEVER IN THE UPPER LEVEL NW FLOW PATTERN...SHORTWAVES COULD STILL TRACK OVER THE RIDGE...BRINGING CHANCES OF PRECIPITATION...HOWEVER WL LEAVE THE FORECAST DRY FOR NOW. NO MAJOR CHANGES TO THE FORECAST PAST FRIDAY. KELLY && .AVIATION... ISSUED 658 AM CDT MON JUL 28 2008 AS HAS BEEN THE CASE LATELY...VFR CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORMS THROUGH THE 12Z TAF PERIOD. UNFORTUNATELY... PICKING THE FAVORED TIME/LOCATION FOR STORM DEVELOPMENT REMAINS TRICKY FOR THE NEXT 24 HOURS. A WEAK WARM FRONT WILL LIFT THROUGH THE TERMINALS DURING THE PERIOD...AND THIS MAY SERVE AS A FOCUS FOR STORMS. IN ADDITION...OUTFLOW BOUNDARIES LEFT BEHIND BY LAST NIGHTS STORMS ARE ALSO IN THE VICINITY. EXPECT DRY CONDITIONS TO LINGER THROUGH MIDDAY...BUT A FEW STORMS ARE POSSIBLE ONCE THE ATMOSPHERE HEATS UP AGAIN. HOWEVER...DUE TO LOW CONFIDENCE IN THE SPECIFICS...WILL ONLY CARRY VCTS IN ALL TERMINALS AFTER 18Z. BAK && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 845 PM EDT TUE JUL 29 2008 .UPDATE... TSTMS WHICH DEVELOPED ALONG PREFRONTAL TROF OVER ERN IA THIS AFTN PROPAGATING EWD AT 35-40KT ACROSS IL THIS EVE. EXPECT STORMS TO WEAKEN WITH DIURNAL COOLING AND AS THEY MOVE INTO LESS UNSTABLE AIRMASS OVER OUR AREA...HWVR...3-6KM LAPSE RATES AROUND 6C/KM FM DTX EVE SOUNDING SUGGESTS POTENTIAL FOR SUFFICIENT ELEVATED INSTABILITY TO ALLOW STORMS TO PERSIST IN WEAKENED STATE AS THEY MOVE THROUGH OUR AREA TONIGHT. UPDATED TO INCREASE POPS TO HIGH LIKELY OVER SWRN PORTION OF CWA...GOING CHC POPS ACROSS REMAINDER OF THE AREA STILL A REASONABLE ESTIMATE OF POTENTIAL. && .PREV DISCUSSION... AVIATION... CDFNT OVER NORTHWEST WI/NW IA WILL MOVE SE AND CROSS NRN INDIANA WED MORNING. FRONT SHOULD BE RATHER DIFFUSE WITH WINDS GRADUALLY VEERING FROM SW TO WEST AS THE FRONT MOVES THROUGH. TS ONGOING ALONG CDFNT OVER NW WI AND ALONG A PRE-FRONTAL TROUGH OVER WRN IL. ALTHOUGH DIURNAL COOLING WILL LIMIT SURFACE BASED INSTABILITY ACROSS NORTHERN INDIANA TONIGHT... MOISTURE TRANSPORT AND APPROACHING UPPER LEVEL TROUGH SHOULD ALLOW FOR SUFFICIENT ELEVATED INSTABILITY FOR TS OVER IL TO REACH THE TERMINALS IN A WEAKENED STATE LATE TONIGHT. WITH FRONT EXPECTED TO MOVE THROUGH EARLY IN THE DAY...AND GOOD POTENTIAL FOR DEBRIS CLOUDS LIMITING HEATING IN THE MORNING...TS CHANCES WED APPEAR TOO LOW TO MENTION IN TAFS ATTM. && .PREV DISCUSSION... SHORT TERM... TONIGHT THROUGH WEDNESDAY NIGHT 19Z ANALYSIS REVEALS TWO DISTINCT MID LEVEL VORTICIES NEARING THE REGION...A POTENT SW TROUGH ENTERING THE UPPER GREAT LAKES AND A THE REMNANTS OF DOLLY HEADING INTO THE MID MISSISSIPPI VALLEY. BOTH OF THESE FEATURES WILL INTERACT TO HELP INCREASE PRECIP CHANCES TONIGHT INTO TOMORROW. HAVE UTILIZED THE NAM 12 AND AND RUC13 FOR FORECAST DETAILS MAINLY IN TRYING TO TIME THESE FEATURES AND THERE RESULTANT IMPACTS ON THE LOCAL SYNOPTIC/MESOSCALE PATTERN. MOISTURE CONTINUES TO STRUGGLE TO RETURN TO THE REGION PER WEAK MOMENTUM FIELDS GIVEN LIGHT TO CALM WINDS BEING PREDOMINATE OVER THE FA. HIGHEST MOISTURE AXIS CONTINUES TO RESIDE OVER IL/IA/MO AND WILL BEGIN TO SLOWLY PUSH EAST AS LL WINDS RESPOND TO SFC PRESSURE FALLS IN RESPONSE TO THE ADVANCING UPPER TROUGH. WITH INCREASED LL MOISTURE...MID COOLING WILL COMMENCE TONIGHT IN REPONSE TO THE SKIRTING UPPER IMPULSE...INCREASING THE INSTABILITY ACROSS THE REGION. THE INCREASED INSTABILITY IS EVIDENT IN SHOWALTER INDICES PROGS FALLING TO AROUND -3. THIS INCREASED INSTABILITY COUPLED WITH THE ADVANCEMENT OF A SFC BOUNDARY WILL SUPPORT AN INCREASED CHANCE FOR PRECIP TONIGHT. LACK OF DEEP LAYER SHEAR/STRONG UPPER LEVEL FORCING/AND WEAK LL WIND FIELDS WILL BE DETRIMENTAL TO WELL ORGANIZED CONVECTION...ALLOWING THE ADVANCING BOUNDARY AND ANY RESIDUAL OUTFLOW BOUNDARIES TO BE THE SOLE MECHANISM FOR PRODUCTION OF PRECIP. NIGHTTIME FRONTAL ARRIVAL WILL ALSO BE DETRIMENTAL TO PRECIP CHANCES. HENCE...HAVE TRIMMED BACK 50 POPS TO THE WEST WHERE BEST INGREDIENTS WILL BE IN PLACE. FARTHER EAST...HAVE LOWERED TO 40...WHICH MAY EVEN BE TOO HIGH AT THIS POINT...THINKING MAV GUIDANCE MAY BE THE MOST REALISTIC IN THE POP DEPARTMENT. WEDNESDAY...FRONTAL BOUNDARY WILL SAG INTO THE REGION AND STALL IN RESPONSE TO THE ADVANCEMENT OF THE REMNANTS OF DOLLY. THE TRACK OF THIS IMPULSE VARIES IN MODEL SOLUTIONS AND WILL LIKELY CHANGE FROM RUN TO RUN GIVEN FORECAST MODEL POOR HANDLING OF TROPICAL REMNANTS/SLOW MOVING UPPER IMPULSES. CURRENT EXPECTATION IS THAT THIS SYSTEM WILL PHASE WITH THE DEEP NORTHERN STREAM WAVE AND PROGRESS EAST. THUS WITH ADDED LIFT FROM THE UPPER IMPULSE AND INCREASED LL CONVERGENCE FROM THE BOUNDARY IN PLACE...HAVE LET POPS RIDE THROUGH THE DAY WITH HIGHER NUMBERS IN THE SOUTH WHERE BETTER DYNAMICS LOOK TO BE FAVORED. VEERING WINDS IN THE H925 TO H85 LAYER OVERNIGHT WILL BRING AN ADDED SMALL CHANCE OF PRECIP SHIFTING SOUTH OVERNIGHT. HAVE RETAINED LOW POPS FOR THIS. OTHERWISE...TEMPS WILL REMAIN RATHER WARM THROUGH THE PERIOD WITH SLIGHTLY DRIER AIR WORKING INTO THE NORTH WED NIGHT PER NORTHERLY FLOW...ALLOWING COOLER TEMPS THERE. LONG TERM... WARM AND MUGGY WITH LITTLE CHANCE FOR PRECIPITATION IS THE THEME FOR THE EXTENDED PERIOD. MODELS CONTINUE TO ADVERTISE STRONG UPR LEVEL RIDGE BUILDING EASTWARD THOUGH THE WEEKEND WITH H5 HIGH OVER OHIO VALLEY BY SUNDAY NIGHT. GFS BRINGS A WEAK SW THROUGH FRIDAY NIGHT BUT MODEL SOUNDINGS ALREADY CAPPED BY THIS TIME. HEAT BUILDS IN EARNEST BEGINNING SATURDAY WITH H850 TEMPS OVER 20C SAT THROUGH TUESDAY. GUIDANCE...ALREADY BEING UNDERCUT...WARMED EVEN MORE. BUMPED HIGHS INTO LOWER 90S MOST AREAS SAT-SUN WHICH IS STILL BELOW GUIDANCE. WITH ONGOING DRY CONDITIONS THE DOOR IS STILL OPEN TO EVEN WARMER TEMPS THAN CURRENTLY FCST. RIDGE FLATTENS EARLY NEXT WEEK WITH GFS ENSEMBLE MEAN FASTER TO DROP NW FLOW OVER REGION THAN THE OP RUN...WITH BNDRY SAGGING NEAR NORTHERN CWA BY END OF FCST PD. BUT ONCE ESTABLISHED WOULD NOT BE SURPRISED TO SEE RIDGING HOLD LONGER THAN CURRENTLY DEPICTED. EITHER WAY...TEMPS REMAIN ABOVE NORMAL THROUGH THE EXTENDED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LUDINGTON AVIATION/UPDATE...JT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 745 PM EDT TUE JUL 29 2008 .AVIATION... CDFNT OVER NORTHWEST WI/NW IA WILL MOVE SE AND CROSS NRN INDIANA WED MORNING. FRONT SHOULD BE RATHER DIFFUSE WITH WINDS GRADUALLY VEERING FROM SW TO WEST AS THE FRONT MOVES THROUGH. TS ONGOING ALONG CDFNT OVER NW WI AND ALONG A PRE-FRONTAL TROUGH OVER WRN IL. ALTHOUGH DIURNAL COOLING WILL LIMIT SURFACE BASED INSTABILITY ACROSS NORTHERN INDIANA TONIGHT... MOISTURE TRANSPORT AND APPROACHING UPPER LEVEL TROUGH SHOULD ALLOW FOR SUFFICIENT ELEVATED INSTABILITY FOR TS OVER IL TO REACH THE TERMINALS IN A WEAKENED STATE LATE TONIGHT. WITH FRONT EXPECTED TO MOVE THROUGH EARLY IN THE DAY...AND GOOD POTENTIAL FOR DEBRIS CLOUDS LIMITING HEATING IN THE MORNING...TS CHANCES WED APPEAR TOO LOW TO MENTION IN TAFS ATTM. && .PREV DISCUSSION... SHORT TERM... TONIGHT THROUGH WEDNESDAY NIGHT 19Z ANALYSIS REVEALS TWO DISTINCT MID LEVEL VORTICIES NEARING THE REGION...A POTENT SW TROUGH ENTERING THE UPPER GREAT LAKES AND A THE REMNANTS OF DOLLY HEADING INTO THE MID MISSISSIPPI VALLEY. BOTH OF THESE FEATURES WILL INTERACT TO HELP INCREASE PRECIP CHANCES TONIGHT INTO TOMORROW. HAVE UTILIZED THE NAM 12 AND AND RUC13 FOR FORECAST DETAILS MAINLY IN TRYING TO TIME THESE FEATURES AND THERE RESULTANT IMPACTS ON THE LOCAL SYNOPTIC/MESOSCALE PATTERN. MOISTURE CONTINUES TO STRUGGLE TO RETURN TO THE REGION PER WEAK MOMENTUM FIELDS GIVEN LIGHT TO CALM WINDS BEING PREDOMINATE OVER THE FA. HIGHEST MOISTURE AXIS CONTINUES TO RESIDE OVER IL/IA/MO AND WILL BEGIN TO SLOWLY PUSH EAST AS LL WINDS RESPOND TO SFC PRESSURE FALLS IN RESPONSE TO THE ADVANCING UPPER TROUGH. WITH INCREASED LL MOISTURE...MID COOLING WILL COMMENCE TONIGHT IN REPONSE TO THE SKIRTING UPPER IMPULSE...INCREASING THE INSTABILITY ACROSS THE REGION. THE INCREASED INSTABILITY IS EVIDENT IN SHOWALTER INDICES PROGS FALLING TO AROUND -3. THIS INCREASED INSTABILITY COUPLED WITH THE ADVANCEMENT OF A SFC BOUNDARY WILL SUPPORT AN INCREASED CHANCE FOR PRECIP TONIGHT. LACK OF DEEP LAYER SHEAR/STRONG UPPER LEVEL FORCING/AND WEAK LL WIND FIELDS WILL BE DETRIMENTAL TO WELL ORGANIZED CONVECTION...ALLOWING THE ADVANCING BOUNDARY AND ANY RESIDUAL OUTFLOW BOUNDARIES TO BE THE SOLE MECHANISM FOR PRODUCTION OF PRECIP. NIGHTTIME FRONTAL ARRIVAL WILL ALSO BE DETRIMENTAL TO PRECIP CHANCES. HENCE...HAVE TRIMMED BACK 50 POPS TO THE WEST WHERE BEST INGREDIENTS WILL BE IN PLACE. FARTHER EAST...HAVE LOWERED TO 40...WHICH MAY EVEN BE TOO HIGH AT THIS POINT...THINKING MAV GUIDANCE MAY BE THE MOST REALISTIC IN THE POP DEPARTMENT. WEDNESDAY...FRONTAL BOUNDARY WILL SAG INTO THE REGION AND STALL IN RESPONSE TO THE ADVANCEMENT OF THE REMNANTS OF DOLLY. THE TRACK OF THIS IMPULSE VARIES IN MODEL SOLUTIONS AND WILL LIKELY CHANGE FROM RUN TO RUN GIVEN FORECAST MODEL POOR HANDLING OF TROPICAL REMNANTS/SLOW MOVING UPPER IMPULSES. CURRENT EXPECTATION IS THAT THIS SYSTEM WILL PHASE WITH THE DEEP NORTHERN STREAM WAVE AND PROGRESS EAST. THUS WITH ADDED LIFT FROM THE UPPER IMPULSE AND INCREASED LL CONVERGENCE FROM THE BOUNDARY IN PLACE...HAVE LET POPS RIDE THROUGH THE DAY WITH HIGHER NUMBERS IN THE SOUTH WHERE BETTER DYNAMICS LOOK TO BE FAVORED. VEERING WINDS IN THE H925 TO H85 LAYER OVERNIGHT WILL BRING AN ADDED SMALL CHANCE OF PRECIP SHIFTING SOUTH OVERNIGHT. HAVE RETAINED LOW POPS FOR THIS. OTHERWISE...TEMPS WILL REMAIN RATHER WARM THROUGH THE PERIOD WITH SLIGHTLY DRIER AIR WORKING INTO THE NORTH WED NIGHT PER NORTHERLY FLOW...ALLOWING COOLER TEMPS THERE. LONG TERM... WARM AND MUGGY WITH LITTLE CHANCE FOR PRECIPITATION IS THE THEME FOR THE EXTENDED PERIOD. MODELS CONTINUE TO ADVERTISE STRONG UPR LEVEL RIDGE BUILDING EASTWARD THOUGH THE WEEKEND WITH H5 HIGH OVER OHIO VALLEY BY SUNDAY NIGHT. GFS BRINGS A WEAK SW THROUGH FRIDAY NIGHT BUT MODEL SOUNDINGS ALREADY CAPPED BY THIS TIME. HEAT BUILDS IN EARNEST BEGINNING SATURDAY WITH H850 TEMPS OVER 20C SAT THROUGH TUESDAY. GUIDANCE...ALREADY BEING UNDERCUT...WARMED EVEN MORE. BUMPED HIGHS INTO LOWER 90S MOST AREAS SAT-SUN WHICH IS STILL BELOW GUIDANCE. WITH ONGOING DRY CONDITIONS THE DOOR IS STILL OPEN TO EVEN WARMER TEMPS THAN CURRENTLY FCST. RIDGE FLATTENS EARLY NEXT WEEK WITH GFS ENSEMBLE MEAN FASTER TO DROP NW FLOW OVER REGION THAN THE OP RUN...WITH BNDRY SAGGING NEAR NORTHERN CWA BY END OF FCST PD. BUT ONCE ESTABLISHED WOULD NOT BE SURPRISED TO SEE RIDGING HOLD LONGER THAN CURRENTLY DEPICTED. EITHER WAY...TEMPS REMAIN ABOVE NORMAL THROUGH THE EXTENDED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LUDINGTON AVIATION...JT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 347 PM EDT TUE JUL 29 2008 .SHORT TERM... TONIGHT THROUGH WEDNESDAY NIGHT 19Z ANALYSIS REVEALS TWO DISTINCT MID LEVEL VORTICIES NEARING THE REGION...A POTENT SW TROUGH ENTERING THE UPPER GREAT LAKES AND A THE REMNANTS OF DOLLY HEADING INTO THE MID MISSISSIPPI VALLEY. BOTH OF THESE FEATURES WILL INTERACT TO HELP INCREASE PRECIP CHANCES TONIGHT INTO TOMORROW. HAVE UTILIZED THE NAM 12 AND AND RUC13 FOR FORECAST DETAILS MAINLY IN TRYING TO TIME THESE FEATURES AND THERE RESULTANT IMPACTS ON THE LOCAL SYNOPTIC/MESOSCALE PATTERN. MOISTURE CONTINUES TO STRUGGLE TO RETURN TO THE REGION PER WEAK MOMENTUM FIELDS GIVEN LIGHT TO CALM WINDS BEING PREDOMINATE OVER THE FA. HIGHEST MOISTURE AXIS CONTINUES TO RESIDE OVER IL/IA/MO AND WILL BEGIN TO SLOWLY PUSH EAST AS LL WINDS RESPOND TO SFC PRESSURE FALLS IN RESPONSE TO THE ADVANCING UPPER TROUGH. WITH INCREASED LL MOISTURE...MID COOLING WILL COMMENCE TONIGHT IN REPONSE TO THE SKIRTING UPPER IMPULSE...INCREASING THE INSTABILITY ACROSS THE REGION. THE INCREASED INSTABILITY IS EVIDENT IN SHOWALTER INDICES PROGS FALLING TO AROUND -3. THIS INCREASED INSTABILITY COUPLED WITH THE ADVANCEMENT OF A SFC BOUNDARY WILL SUPPORT AN INCREASED CHANCE FOR PRECIP TONIGHT. LACK OF DEEP LAYER SHEAR/STRONG UPPER LEVEL FORCING/AND WEAK LL WIND FIELDS WILL BE DETRIMENTAL TO WELL ORGANIZED CONVECTION...ALLOWING THE ADVANCING BOUNDARY AND ANY RESIDUAL OUTFLOW BOUNDARIES TO BE THE SOLE MECHANISM FOR PRODUCTION OF PRECIP. NIGHTTIME FRONTAL ARRIVAL WILL ALSO BE DETRIMENTAL TO PRECIP CHANCES. HENCE...HAVE TRIMMED BACK 50 POPS TO THE WEST WHERE BEST INGREDIENTS WILL BE IN PLACE. FARTHER EAST...HAVE LOWERED TO 40...WHICH MAY EVEN BE TOO HIGH AT THIS POINT...THINKING MAV GUIDANCE MAY BE THE MOST REALISTIC IN THE POP DEPARTMENT. WEDNESDAY...FRONTAL BOUNDARY WILL SAG INTO THE REGION AND STALL IN RESPONSE TO THE ADVANCEMENT OF THE REMNANTS OF DOLLY. THE TRACK OF THIS IMPULSE VARIES IN MODEL SOLUTIONS AND WILL LIKELY CHANGE FROM RUN TO RUN GIVEN FORECAST MODEL POOR HANDLING OF TROPICAL REMNANTS/SLOW MOVING UPPER IMPULSES. CURRENT EXPECTATION IS THAT THIS SYSTEM WILL PHASE WITH THE DEEP NORTHERN STREAM WAVE AND PROGRESS EAST. THUS WITH ADDED LIFT FROM THE UPPER IMPULSE AND INCREASED LL CONVERGENCE FROM THE BOUNDARY IN PLACE...HAVE LET POPS RIDE THROUGH THE DAY WITH HIGHER NUMBERS IN THE SOUTH WHERE BETTER DYNAMICS LOOK TO BE FAVORED. VEERING WINDS IN THE H925 TO H85 LAYER OVERNIGHT WILL BRING AN ADDED SMALL CHANCE OF PRECIP SHIFTING SOUTH OVERNIGHT. HAVE RETAINED LOW POPS FOR THIS. OTHERWISE...TEMPS WILL REMAIN RATHER WARM THROUGH THE PERIOD WITH SLIGHTLY DRIER AIR WORKING INTO THE NORTH WED NIGHT PER NORTHERLY FLOW...ALLOWING COOLER TEMPS THERE. && .LONG TERM... WARM AND MUGGY WITH LITTLE CHANCE FOR PRECIPITATION IS THE THEME FOR THE EXTENDED PERIOD. MODELS CONTINUE TO ADVERTISE STRONG UPR LEVEL RIDGE BUILDING EASTWARD THOUGH THE WEEKEND WITH H5 HIGH OVER OHIO VALLEY BY SUNDAY NIGHT. GFS BRINGS A WEAK SW THROUGH FRIDAY NIGHT BUT MODEL SOUNDINGS ALREADY CAPPED BY THIS TIME. HEAT BUILDS IN EARNEST BEGINNING SATURDAY WITH H850 TEMPS OVER 20C SAT THROUGH TUESDAY. GUIDANCE...ALREADY BEING UNDERCUT...WARMED EVEN MORE. BUMPED HIGHS INTO LOWER 90S MOST AREAS SAT-SUN WHICH IS STILL BELOW GUIDANCE. WITH ONGOING DRY CONDITIONS THE DOOR IS STILL OPEN TO EVEN WARMER TEMPS THAN CURRENTLY FCST. RIDGE FLATTENS EARLY NEXT WEEK WITH GFS ENSEMBLE MEAN FASTER TO DROP NW FLOW OVER REGION THAN THE OP RUN...WITH BNDRY SAGGING NEAR NORTHERN CWA BY END OF FCST PD. BUT ONCE ESTABLISHED WOULD NOT BE SURPRISED TO SEE RIDGING HOLD LONGER THAN CURRENTLY DEPICTED. EITHER WAY...TEMPS REMAIN ABOVE NORMAL THROUGH THE EXTENDED. && .AVIATION.../18Z TAFS/ WEAK MID LEVEL RIDGING OVER THE REGION PER AN ADVANCING DEEP UPPER TROUGH...WILL CONTINUE TO BRING VFR CONDITIONS TO THE REGION. THIS SAME TROUGH WILL PUSH INTO THE UPPER GREAT LAKES TONIGHT...SUPPORTING THE ADVANCEMENT OF A WEAK COLD FRONT INTO THE REGION. INCREASED INSTABILITY MAY TRIGGER A FEW SHOWERS AND THUNDERSTORMS IN THE EARLY MORNING HOURS ALONG THIS FRONT...WITH THE BEST CHANCE BEING IN THE NORTH. HOWEVER...GIVEN THE LACK OF UPPER LEVEL SUPPORT AND WEAK FORCING PRESENT...HAVE LEFT TEMPO GROUPS OUT OF THE TAFS DUE TO LOW CONFIDENCE IN WIDESPREAD DEVELOPMENT...OPTING FOR A CB MENTION AT THIS TIME. INCREASE LOW LEVEL MOISTURE MAY ALSO SUPPORT BR/FG ONCE AGAIN IN THE EAST WHERE CLOUDS ARE LEAST EXPECTED FOR THE MAJORITY OF THE NIGHT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LUDINGTON AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 629 PM CDT TUE JUL 29 2008 ...UPDATED AVIATION SECTION... .SHORT TERM...TONIGHT 18Z SFC ANALYSIS SHOWS A WEAKENING COLD FRONT INTO NORTHWEST IA WITH A TROUGH AHEAD OF IT FROM NORTHEAST IOWA TO JUST NW OF DSM. A HIGH PRESSURE BUBBLE HAS DEVELOPED BETWEEN THE COLD FRONT AND THE LOW PRESSURE OVER SOUTH CENTRAL KANSAS AND EXTENDS INTO SOUTHWEST IOWA. THIS HIGH PRESSURE IS LIKELY BEING REINFORCED BY RAIN-COOLED AIR ASSOCIATED WITH DEFORMATION AXIS RAINFALL APPROACHING SRN IA. INSTABILITY IN QUESTION THIS AFTERNOON. THE RUC AND SPC ANALYSIS GRAPHICS SHOW MUCH OF THE AREA NOW MODERATELY UNSTABLE WITH LITTLE CAPPING...IF ANY. HOWEVER...LAPS AND RUC SOUNDINGS SHOW A LOWER WARM NOSE. GIVEN DEGREE OF CLOUD COVER OVER SOUTHERN IA...FEEL THAT BEST CHANCES FOR LATE AFTN AND EVENING THUNDERSTORMS WILL BE BETWEEN INTERSTATE 80 AND THE COLD FRONT DROPPING SOUTHEAST...AND ALSO PERHAPS IN THE FAR SOUTHEAST NEAR OTTUMWA. OTHERWISE...FAR SOUTHERN IOWA SHOULD EXPERIENCE A FEW HOURS OF LIGHT TO MODERATE RAIN WITH EMBEDDED THUNDER POSSIBLE. .LONG TERM...WEDNESDAY THROUGH MONDAY HIGH PRESSURE WILL WEAKLY BUILD INTO THE UPPER MIDWEST ON WEDNESDAY BUT REMNANTS OF DOLLY WILL STILL BE EVIDENCED IN NORTHERN/NORTHEAST MO. ADDITIONAL CONVECTION SHOULD DEVELOP IN VICINITY OF THE WASHED OUT FRONT FROM TODAY AND THE MOISTURE FROM DOLLY. THIS MAY CLIP THE FAR SOUTH OR SOUTHEAST BUT WE ARE NOT EXPECTING ANY MAJOR PRECIP OUT OF THAT. LATER ON WEDNESDAY/WEDNESDAY NIGHT...THE HIGH SHIFTS EAST AS A LOW PRESSURE SYSTEM DEVELOPS IN THE HIGH PLAINS IN RESPONSE TO A WEAK SHORTWAVE AND WARM ADVECTION. THE SURFACE LOW WILL SET UP A BOUNDARY OVER NORTHERN IOWA/SOUTHERN MINNESOTA OR SOUTH DAKOTA. THERE IS VIRTUALLY NO SHEAR BUT CAPES BETWEEN 1200 AND 2600 J/KG THROUGH THE WEDNESDAY NIGHT PERIOD. I FELT THIS WARRANTED AT LEAST A MENTION OF SLIGHT CHC OR CHANCE WHICH WAS EXPENDED DURING THE OVERNIGHT PORTION OF THE PERIOD. FOR THURSDAY...WARM ADVECTION REALLY STRENGTHENS AS A THERMAL RIDGE PUSHES IN. THE AFOREMENTIONED SURFACE LOW DRIFTS INTO MN LEAVING IA STRONGLY IN THE WARM SECTOR. MODELS STILL INDICATE A WEAK VORT MAX AND SHORT WAVE PUSHING MAINLY ACROSS THE HIGH PLAINS BUT THE UPPER LEVEL FLOW DOES BECOME MORE NW OVER NORTHERN AND EASTERN IOWA SO SHOULD AN MCS DEVELOP IN THIS VICINITY IT MAY CLIP FAR NORTHERN IOWA LATER THURSDAY NIGHT. THIS HAS BEEN ACCOUNTED FOR ALREADY AND WE WILL KEEP SLIGHT CHANCES IN FOR NOW. MODEL TRENDS HAVE BEEN FURTHER NORTH WITH THIS FEATURE WITH EACH RUN SO THIS MAY BE ADJUSTED/ REMOVED IN LATER PERIODS. FOR THE WEEKEND THE UPPER LEVEL RIDGE BUILD OVER THE UPPER MIDWEST AND WE TURN HOT. TEMPS WILL BE TEMPERED SOME BY CLOUD COVER AND THE AMOUNT OF MOISTURE IN THE AIR BUT MID 90S NOW SEEM LIKELY AND MAYBE EVEN HIGHER READINGS. A LARGE LOW PRESSURE SYSTEM IS SLATED TO FLATTEN THE RIDGE LATE IN THE EXTENDED...BEGINNING SUNDAY NIGHT THROUGH MONDAY NIGHT. BOTH THE GFS AND EURO POINTING TO A MORE ACTIVE PERIOD OVER NORTHERN IOWA AS SEVERAL SHORT WAVES MOVE EAST THROUGH THE PERIOD. BACKED TEMPS DOWN AS WELL FOR SUNDAY AND MONDAY DUE TO CLOUD COVER AND THE POTENTIAL FOR STORMS. && .AVIATION...30/00Z VERY ISOLATED SHRA/TSRA EXPECTED OVER CTL/NRN IA THIS EVENING AND EARLY TONIGHT...BUT PROBABILITY OF IMPACTS ON A TERMINAL SUFFICIENTLY SMALL TO PRECLUDE MENTION IN TAFS ATTM. -RA WILL BE PERSISTENT AT KOTM AT LEAST THROUGH 06Z...BUT SHOULD BE TOO LIGHT TO RESULT IN MVFR VIS. OTHER CONCERN IS BR DURING EARLY MORNING HOURS...WITH A POSSIBILITY OF IFR OR LOWER RESULTING VIS AT A STATION OR TWO. AFTER SUNRISE TOMORROW QUIETER WEATHER WILL RESULT IN PREDOMINATING VFR CONDITIONS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MOYER LONG TERM...FAB AVIATION...LEE ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 305 PM CDT TUE JUL 29 2008 .SHORT TERM...TONIGHT 18Z SFC ANALYSIS SHOWS A WEAKENING COLD FRONT INTO NORTHWEST IA WITH A TROUGH AHEAD OF IT FROM NORTHEAST IOWA TO JUST NW OF DSM. A HIGH PRESSURE BUBBLE HAS DEVELOPED BETWEEN THE COLD FRONT AND THE LOW PRESSURE OVER SOUTH CENTRAL KANSAS AND EXTENDS INTO SOUTHWEST IOWA. THIS HIGH PRESSURE IS LIKELY BEING REINFORCED BY RAIN-COOLED AIR ASSOCIATED WITH DEFORMATION AXIS RAINFALL APPROACHING SRN IA. INSTABILITY IN QUESTION THIS AFTERNOON. THE RUC AND SPC ANALYSIS GRAPHICS SHOW MUCH OF THE AREA NOW MODERATELY UNSTABLE WITH LITTLE CAPPING...IF ANY. HOWEVER...LAPS AND RUC SOUNDINGS SHOW A LOWER WARM NOSE. GIVEN DEGREE OF CLOUD COVER OVER SOUTHERN IA...FEEL THAT BEST CHANCES FOR LATE AFTN AND EVENING THUNDERSTORMS WILL BE BETWEEN INTERSTATE 80 AND THE COLD FRONT DROPPING SOUTHEAST...AND ALSO PERHAPS IN THE FAR SOUTHEAST NEAR OTTUMWA. OTHERWISE...FAR SOUTHERN IOWA SHOULD EXPERIENCE A FEW HOURS OF LIGHT TO MODERATE RAIN WITH EMBEDDED THUNDER POSSIBLE. .LONG TERM...WEDNESDAY THROUGH MONDAY HIGH PRESSURE WILL WEAKLY BUILD INTO THE UPPER MIDWEST ON WEDNESDAY BUT REMNANTS OF DOLLY WILL STILL BE EVIDENCED IN NORTHERN/NORTHEAST MO. ADDITIONAL CONVECTION SHOULD DEVELOP IN VICINITY OF THE WASHED OUT FRONT FROM TODAY AND THE MOISTURE FROM DOLLY. THIS MAY CLIP THE FAR SOUTH OR SOUTHEAST BUT WE ARE NOT EXPECTING ANY MAJOR PRECIP OUT OF THAT. LATER ON WEDNESDAY/WEDNESDAY NIGHT...THE HIGH SHIFTS EAST AS A LOW PRESSURE SYSTEM DEVELOPS IN THE HIGH PLAINS IN RESPONSE TO A WEAK SHORTWAVE AND WARM ADVECTION. THE SURFACE LOW WILL SET UP A BOUNDARY OVER NORTHERN IOWA/SOUTHERN MINNESOTA OR SOUTH DAKOTA. THERE IS VIRTUALLY NO SHEAR BUT CAPES BETWEEN 1200 AND 2600 J/KG THROUGH THE WEDNESDAY NIGHT PERIOD. I FELT THIS WARRANTED AT LEAST A MENTION OF SLIGHT CHC OR CHANCE WHICH WAS EXPENDED DURING THE OVERNIGHT PORTION OF THE PERIOD. FOR THURSDAY...WARM ADVECTION REALLY STRENGTHENS AS A THERMAL RIDGE PUSHES IN. THE AFOREMENTIONED SURFACE LOW DRIFTS INTO MN LEAVING IA STRONGLY IN THE WARM SECTOR. MODELS STILL INDICATE A WEAK VORT MAX AND SHORT WAVE PUSHING MAINLY ACROSS THE HIGH PLAINS BUT THE UPPER LEVEL FLOW DOES BECOME MORE NW OVER NORTHERN AND EASTERN IOWA SO SHOULD AN MCS DEVELOP IN THIS VICINITY IT MAY CLIP FAR NORTHERN IOWA LATER THURSDAY NIGHT. THIS HAS BEEN ACCOUNTED FOR ALREADY AND WE WILL KEEP SLIGHT CHANCES IN FOR NOW. MODEL TRENDS HAVE BEEN FURTHER NORTH WITH THIS FEATURE WITH EACH RUN SO THIS MAY BE ADJUSTED/ REMOVED IN LATER PERIODS. FOR THE WEEKEND THE UPPER LEVEL RIDGE BUILD OVER THE UPPER MIDWEST AND WE TURN HOT. TEMPS WILL BE TEMPERED SOME BY CLOUD COVER AND THE AMOUNT OF MOISTURE IN THE AIR BUT MID 90S NOW SEEM LIKELY AND MAYBE EVEN HIGHER READINGS. A LARGE LOW PRESSURE SYSTEM IS SLATED TO FLATTEN THE RIDGE LATE IN THE EXTENDED...BEGINNING SUNDAY NIGHT THROUGH MONDAY NIGHT. BOTH THE GFS AND EURO POINTING TO A MORE ACTIVE PERIOD OVER NORTHERN IOWA AS SEVERAL SHORT WAVES MOVE EAST THROUGH THE PERIOD. BACKED TEMPS DOWN AS WELL FOR SUNDAY AND MONDAY DUE TO CLOUD COVER AND THE POTENTIAL FOR STORMS. && .AVIATION...29/18Z WILL SEE ISOLATED TO SCATTERED CONVECTION OVER CENTRAL IA THROUGH 02Z WITH LEAST COVERAGE AND EARLIER ENDING AT NRN SITES. UNCERTAINTIES WITH TIMING AND LOCATION PRECLUDE ANYTHING MORE THAN VC OR CB IN TAFS AT THIS TIME. HAVE TO HANG ON TO MVFR CEILINGS AT KOTM FOR A LITTLE WHILE LONGER. AFTER CONVECTION MOVES OUT TONIGHT...DECENT CHANCES OF HAVING MVFR VSBYS DEVELOP...ESPECIALLY WHERE IT CLEARS BEST. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/AVIATION...MOYER LONG TERM...FAB ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 204 PM CDT TUE JUL 29 2008 .DISCUSSION... DAYS 1-2... CHALLENGES IN THE FORECAST INCLUDE WHEN TO SHUT OFF PRECIPITATION CHANCES...POSSIBILITIES FOR FOG TONIGHT...AND AFTERNOON TEMPS OVER THE NEXT COUPLE DAYS. WV LOOP AND RUC ANALYSIS THIS AFTERNOON SHOWED SLOW PROGRESSION OF THE DEEP LAYER CYCLONE TODAY. IN ITS WAKE...SUBSTANTIAL MID LEVEL DRYING WAS EVIDENT ACROSS COLORADO INTO EXTREME WESTERN KANSAS. IN THE LOW LEVELS, A THERMAL TROUGH NORTHWEST OF THE SURFACE LOW HAS HELPED KEEP TEMPS STUCK IN THE 70S ACROSS MUCH OF SOUTHWEST KANSAS...ALONG WITH IT AN ABUNDANCE OF MOISTURE FOR RESULTANT WIDESPREAD STRATIFORM CLOUD COVER. 1000 TO 2000 FOOT CEILINGS WERE STILL HOLDING TOUGH EVEN AT 18Z. I REALLY DO NOT SEE MUCH CHANCE OF THIS DIMINISHING MUCH BEFORE SUNSET GIVEN THE VERY SLOW MOVEMENT OF THE ENTIRE SYSTEM. THE SURFACE LOW HAS SHIFTED ABOUT 70 MILES EAST OVER THE SPAN OF ABOUT 6 HOURS. AN EAST-WEST WEAK SURFACE RIDGE WAS CENTERED NEAR THE THE LENGTH OF THE KANSAS- NEBRASKA BORDER. THIS RIDGE WILL REMAIN ACROSS NORTHERN KANSAS TONIGHT WHICH WILL KEEP SURFACE WINDS OUT THE NORTHEAST FOR THE MOST PART. THIS WILL KEEP LOW LEVEL MOISTURE LOCKED IN WITH SURFACE DEWPOINTS IN THE 65 TO 68F RANGE. THE EVENING WILL START OFF WITH ABOUT A 10F TEMPERATURE-DEWPOINT SPREAD. CEILINGS WILL LOWER ONCE THE SUN SETS AGAIN AND VISIBILITIES ARE EXPECTED TO SLOWLY FALL THROUGH THE NIGHT AS THE TEMPERATURE FALLS INTO THE 67 TO 70 RANGE FOR A LOW. WILL THROW IN SOME PATCHY LIGHT FOG ACROSS A GOOD CHUNK OF THE CENTRAL DDC CWA IN LINE WITH ICT AND GLD FORECAST. THIS LATE AFTERNOON`S WIDELY SCATTERED SHOWER ACTIVITY SHOULD RESIDE MAINLY ACROSS THE EASTERN THIRD OF THE CWA THROUGH EARLY EVENING CLOSER TO THE CENTER OF THE SLOWLY MOVING CYCLONE...BUT AM NOT LOOKING FOR ANY SUBSTANTIAL RAINFALL AMOUNTS WITH THE BEST LIFT OCCURRING EAST OF THE DDC CWA. LOW CLOUDS SHOULD DIMINISH BY MID-MORNING WITH MORE SUBSIDENCE/DRYING INFLUENCING SOUTHWEST KANSAS. SURFACE RIDGE AXIS WILL EVOLVE SLOWLY EASTWARD ACROSS KANSAS DURING THE DAY...KEEPING NORTHEAST WINDS ACROSS SOUTHWEST KS FOR AT LEAST THE FIRST HALF OF THE DAY. BY AFTERNOON...WINDS WILL VEER MORE TO THE EAST AS SURFACE HIGH SHIFTS EAST AND LEESIDE LOW DEVELOPS ACROSS NORTHERN HIGH PLAINS -- THANKS TO A SUBSTANTIAL PACIFIC JET MOVING ACROSS THE PACIFIC NORTHWEST INTO MONTANA. THIS JET WILL HAVE LITTLE INFLUENCE ACROSS SOUTHWEST KANSAS OTHER THAN HELPING ALLOW SURFACE WINDS TO VEER BACK AROUND TO THE SOUTH AS SURFACE LOW DEVELOPS AND RESPONDS TO THE UPPER JET ACROSS THE DAKOTAS. VERY WARM H7-8 TEMPS WILL DEVELOP ONCE AGAIN ACROSS THE CENTRAL ROCKIES AND ADJACENT COLORADO HIGH PLAINS...SETTING THE STAGE FOR A FAIRLY RAPID RETURN TO THE HEAT BY THURSDAY. HAVE INCREASED HIGHS THURSDAY INTO THE 99-100F TERRITORY ACROSS MUCH OF THE DDC CWA, ESPECIALLY WEST. EASTERN CWA (SOUTH CENTRAL KS) WILL STILL BE CLOSE ENOUGH TO THE REMNANT HIGH IN THE WAKE OF THE CURRENT SLOW MOVING SYSTEM...SUCH THAT HIGHS WILL PROBABLY STRUGGLE TO GET TO GET MUCH ABOVE 95 OR SO. -UMSCHEID DAYS 3-7... SUMMERTIME WEATHER CONTINUES WITH RIDGE OF HIGH PRESSURE ACROSS THE SOUTHWESTERN CONUS NORTHEAST INTO THE CENTRAL PLAINS. WEAK SHORTWAVE TROUGHS WILL MOVE THROUGH THE UPPER FLOW WITH LITTLE DAY TO DAY FANFARE. AT THE SURFACE, A LEE SIDE TROUGH WILL PERSIST THROUGH THE WEEKEND. H85 TEMPERATURES SOAR INTO THE MID 20S EAST TO THE LOWER 30S WEST. DEWPOINTS WILL REMAIN IN THE LOWER 60S ACROSS MUCH OF THE EASTERN AND CENTRAL FA WITH UPPER 50S WEST. GIVEN THE PEAK HEATING DURING THE DAYTIME HOURS, SOME MOISTURE AND WEAK SHORTWAVE TROUGHS ACROSS THE AREA, TYPICAL SUMMERTIME ISOLATED THUNDERSTORMS WILL BE POSSIBLE DURING THIS TIME. WILL CONTINUE TO LEAVE GRIDS DRY AS ANY THUNDERSTORMS WILL BE FEW AND FAR BETWEEN. THERE ARE INDICATIONS OF THE RIDGE BREAKING DOWN TO START THE WORKWEEK. MODELS AGREE WITH AN UPPER LOW MOVING ACROSS CANADA WITH TROUGH EXTENDING SOUTH INTO THE NORTHERN/CENTRAL PLAINS. GFS IS SLOWER WITH THIS FEATURE WHILE THE HIRES ECMWF IS MUCH QUICKER. CANADIAN MODEL SPLITS THE DIFFERENCE WITH SOME ENSEMBLE MEMBERS SUPPORTING THE GFS AND OTHER SUPPORTING THE HIRES ECMWF. EITHER WAY, THERE IS JUSTIFICATION IN INSERTING SLIGHT CHANCE POPS ACROSS THE NORTHERN FA DURING THE START OF THE WORKWEEK. SURFACE RESPONSE FROM THE HIRES ECMWF AND GFS PUSHES FRONT ACROSS SOUTHERN KANSAS BY TUESDAY EVENING. FOR NOW, HAVE CONFINED THE POPS TO THE NORTHERN HALF OF THE AREA BUT WILL HAVE TO MONITOR SPEED AND LOCATION OF BOTH UPPER AND SURFACE FEATURES TO START THE WORKWEEK. && .AVIATION... UPPER LOW WILL MOVE EAST ACROSS EASTERN KANSAS THROUGH TONIGHT. LOW CLOUDS WILL LINGER THROUGH MUCH OF THE OVERNIGHT HOURS. LIGHT AND VARIABLE WINDS WILL BE FOUND AT ALL SITES THROUGH THE MORNING HOURS. MVFR TO IFR CONDITIONS WILL PREVAIL THROUGH 13Z TUE. A PERIOD OF LIFR IS POSSIBLE AROUND SUNRISE. ONCE SUNRISE OCCURS, VFR CONDITIONS WILL RETURN TO THE SITES. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 90 69 99 / 10 10 10 0 GCK 66 91 67 100 / 10 10 10 0 EHA 66 93 65 100 / 0 10 10 0 LBL 67 92 67 100 / 10 10 10 0 HYS 66 89 69 98 / 10 10 10 0 P28 72 90 72 97 / 30 10 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN25/30/30 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1141 PM CDT SUN JUL 27 2008 .AVIATION... ISOLATED THUNDERSTORM IN NORTHWEST OK DOES NOT WANT TO DIE. WITH WEAK RIPPLE IN UPPER FLOW MOVING ACROSS THE AREA CLOSER TO DAYBREAK...WILL MAINTAIN MENTION OF CUMULONIMBUS IN WESTERN TAFS DURING THE CLIMATOLOGICALLY FAVORED TIME FRAME. OTHERWISE VFR CONDITIONS EXPECTED THROUGHOUT THE PERIOD. LATEST NORTH AMERICAN MODEL ALSO SUGGESTING SOME PRECIPITATION POSSIBLE BY LATE IN THE FORECAST PERIOD AS STORMS IN WESTERN KS MOVE EAST. WILL ONLY MENTION CUMULONIMBUS FOR THIS AT THIS TIME. -HOWERTON && .PREV DISCUSSION... /ISSUED 635 PM CDT SUN JUL 27 2008/ AVIATION... WATCHING THUNDERSTORMS IN WESTERN KS...CURRENT MODEL TRENDS WOULD PUT THE IN THE AREA AFTER 0600 UTC...BUT NOT ENTIRELY SURE ABOUT THAT TIMING. CURRENT SATELLITE TRENDS/OBSERVATIONS SEEM TO SUGGEST SOME MIDDLE LEVEL MOISTURE ALREADY AS CLOSE AS HYS. AT THIS POINT OPTED TO ONLY GO WITH CUMULONIMBUS AT RSL/HUT FOR NOW AND THEN WATCH TRENDS THE NEXT COUPLE OF HOURS. OTHERWISE FOR NOW WILL KEEP CONDITIONS VFR THROUGHOUT THE PERIOD.-HOWERTON PREV DISCUSSION... /ISSUED 351 PM CDT SUN JUL 27 2008/ DISCUSSION... FORECAST CONCERNS WILL BE POPS ASSOCIATED WITH THE REMNANTS OF DOLLY...THEN DRY AND HOT TREND FOR THE END OF THE WEEK. TONIGHT: WILL KEEP THE REGION THIS EVENING/TONIGHT...AS POP CONCERNS WILL EITHER STAY TO THE WEST OR POSSIBLY THE NORTHEAST OF THE AREA. FIRST AREA IS ACROSS SOUTHWEST KS AS A PIECE OF ENERGY FROM THE REMNANTS OF DOLLY DRIFTS NORTH INTO THE TX/OK PANHANDLE...WITH MODERATELY UNSTABLE AIR JUST TO THE NORTH OF THIS IMPULSE ACROSS SOUTHWEST KS. EXPECT THIS IMPULSE TO HELP TO DEVELOP SOME SHRA/TSRA TO THE WEST OF THE AREA...BUT MOST OF THE CONVECTION WILL REMAIN FAR TO THE WEST OF THE AREA. NEXT AREA OF CONCERN WILL BE ACROSS NE KS/NW MO WHERE VERY UNSTABLE AIRMASS IS PLACE...BUT ATMOSPHERE REMAINS CAPPED. WEAKER CAP EXISTS FURTHER TO THE EAST...AND BELIEVE THIS WILL BE AREA WHERE STORMS WILL DEVELOP...AND STAY TO THE EAST OF THE AREA. SO WILL GO WITH A WARM AND HUMID NIGHT FOR THE AREA. MON-TUE: MODELS SEEM TO BE COMING TOGETHER ON HOW THEY WANT TO HANDLE REMNANTS OF DOLLY FOR THE BEGINNING OF THE WORK WEEK. BUT NOT TOO SURE THE MODELS INITIALIZED VERY WELL AND MAY BE LATCHING ONTO THE CURRENT PIECE OF ENERGY ACROSS THE TX PANHANDLE AND NOT THE MAIN CIRCULATION. SO BELIEVE THAT MODELS MAY BE TOO AGGRESSIVE IN BRINGING POPS INTO SOUTH CENTRAL KS FOR EARLY MON. WOULD PREFER TO HOLD OFF ON POPS UNTIL MON AFTERNOON AT THE EARLIEST. ONCE THE SYSTEM ARRIVES...VERY TROPICAL AIRMASS WITH THIS SYSTEM...COULD LEAD TO SOME VERY EFFICIENT RAIN PRODUCERS FOR MON NIGHT...SO WILL CERTAINLY HAVE TO KEEP AN EYE ON THIS GIVEN SLOW MOVEMENT. SO WILL INCREASE POPS IN MOST LOCATIONS MON NIGHT INTO TUE. SLOW MOVEMENT OF THIS SYSTEM WILL ALSO LEAD TO KEEPING POPS AROUND INTO TUE AS MAIN IMPULSE MAKES VERY SLOW PROGRESS ACROSS KS. VERY TROPICAL AIRMASS AND LOTS OF CLOUD COVER WILL LEAD TO A SHOWERY DAY ACROSS THE AREA...SO WILL REDUCE TEMPS SOME FOR TUE. WED-FRI: THINGS LOOK TO DRY OUT FOR MOST LOCATIONS DURING THIS TIME FRAME. THE ONLY EXCEPTION COULD BE SOUTHEAST KS WHERE SOME LINGERING EFFECTS OF DOLLY REMNANTS COULD STILL LEAD TO SOME SHRA. GFS AND ECMWF BOTH SHOW THIS SLOWER TREND...SO WILL KEEP SOME POPS IN FOR NOW. THE REST OF THE AREA LOOKS TO SEE SUNSHINE RETURN AS SOME UPPER RIDGING MOVES INTO THE PLAINS. REST OF THE EXTENDED: MEDIUM RANGE MODELS DIFFER ON THE TIMING AND STRENGTH OF THE UPPER RIDGE BUILDING ACROSS THE PLAINS. ECMWF IS STRONGER IN BUILDING THE RIDGE ACROSS THE AREA...WHILE THE GFS KEEPS THE RIDGE FURTHER TO WEST...KEEPING PORTIONS OF ERN KS IN THE NW FLOW REGIME. MAIN DIFFERENCE WILL BE HOW WARM IT WILL GET...AS BOTH SOLUTIONS LOOK TO KEEP THINGS DRY. KETCHAM AVIATION... FOR 18Z TAFS...MAIN AVIATION CONCERN WILL AGAIN BE ISOLATED STORM POTENTIAL THIS AFTERNOON. CONFIDENCE REGARDING STORM INITIATION REMAINS LOW THROUGH THE AFTERNOON HOURS. CURRENTLY HAVE SOME REMNANT ENERGY FROM DOLLY MOVING OVER NW TX/OK PANHANDLE. WATER VAPOR IMAGERY ALSO SHOWS THAT THERE MAYBE SOME WEAKER UPPER ENERGY SITUATED OVER NW KS. BOTH LAPSE AND RUC DATA HAVE ONE INSTABILITY AXIS SITUATED FROM NW KS INTO CENTRAL KS WITH ANOTHER AREA OF INSTABILITY OVER EASTERN KS/WESTERN MO. BEST CU DEVELOPMENT REMAINS WEST OF FORECAST AREA OVER THE OK PANHANDLE AND WESTERN KS...THEREFORE HAVE MUCH HIGHER CONFIDENCE IN STORM DEVELOPMENT IN THOSE LOCATIONS. WILL JUST MENTION CB IN THE CLOUD GROUP FOR KCNU WITH TOO LOW OF CONFIDENCE TO MENTION IN OTHER LOCATIONS. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 73 98 74 93 / 10 20 30 40 HUTCHINSON 72 98 73 92 / 10 20 30 40 NEWTON 73 98 74 93 / 10 10 30 40 ELDORADO 73 97 74 93 / 10 10 30 30 WINFIELD-KWLD 73 98 75 93 / 10 20 30 30 RUSSELL 73 97 72 91 / 20 30 40 40 GREAT BEND 72 96 72 90 / 20 40 50 40 SALINA 74 100 75 92 / 10 20 30 40 MCPHERSON 73 99 73 92 / 10 20 30 40 COFFEYVILLE 72 96 74 94 / 10 10 10 30 CHANUTE 72 96 73 94 / 10 10 10 30 IOLA 72 97 74 94 / 20 10 10 30 PARSONS-KPPF 72 97 74 94 / 10 10 10 30 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 436 AM CDT MON JUL 28 2008 .DISCUSSION... THE CURRENT MESOSCALE CONVECTIVE SYSTEM /MCS/ SLOWLY WORKING AND DECAYING SOUTHWARD HAS ENCOUNTERED A SHALLOWER POOL OF MOISTURE AND INSTABILITY...AS INDICATED BY THE GOES SOUNDER/WATER VAPOR IMAGERY. INTEGRATED PRECIPITABLE WATER VALUES WERE UP TO 1/2 INCH LOWER ACROSS THE SOUTHERN 1/3 TO 1/4 OF THE WFO PAH FORECAST AREA...WITH CURRENT LIFTED INDEX VALUES DOWN TO NEAR -2 DEGREES CELSIUS. ALTHOUGH SOMEWHAT DISTURBED BY THE HIGH PRESSURE DOME /COLD POOL OUTFLOW FROM THE MCS/ THE WIND FIELDS TO THE WEST AND NORTH OF THE WFO PAH FORECAST AREA INDICATE THE REFORMING OF A CONVECTIVELY INDUCED FRONTAL BOUNDARY OVER WRN MO/IA/NRN 2/3RDS IL AS OF 4 AM THIS MORNING. THE 13KM RUC AND 40KM GFS INDICATE THAT THIS FEATURE WILL BECOME ENHANCES AS A WEAK BAROCLINIC ZONE DEVELOPS THE NORTHERN LIMB OF THE LOWER MS VALLEY UPPER LEVEL RIDGE. WITH MINOR SHORTWAVES PUSHING DOWN THIS BOUNDARY TODAY...I CANNOT RULE OUT THAT PART OF INTERSTATE 64 CORRIDOR IN SOUTHERN IL AND SOUTHWEST IN...AS WELL AS EXTREME NORTHWEST KY...WILL NOT SEE A CONTINUED CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGHOUT AT LEAST PART OF TODAY. ANOTHER MCS WILL LIKELY DEVELOP LATER TODAY FURTHER NORTH AND MAY IMPACT THE EXTREME EASTERN PORTION OF THE WFO PAH FORECAST AREA DURING THE EVENING AND OVERNIGHT HOURS. THE AFOREMENTIONED UPPER LEVEL RIDGE WILL BE WEAKENED /DAMPENED SOUTHWARD/ SOMEWHAT WITH THE EXTRA-TROPICAL CIRCULATION /MCV/ FROM DOLLY...CURRENTLY OVER EASTERN CO/WRN KS. THIS FEATURE PRODUCE SOME MINOR RIDGING INTO THE WFO PAH FORECAST AREA DURING THE DAY ON TUESDAY...CREATING ENOUGH OF A SUBSIDENCE INVERSION TO EFFECTIVELY CAP ANY CONVECTIVE ACTIVITY. THE CAP SHOULD DIMINISH MARKEDLY FROM THE NORTHWEST...AS THE EXTRA-TROPICAL DOLLY CIRCULATION SPREADS EAST...CREATING LIFT ALONG A DIFFERENTIAL LOW LEVEL THERMAL/MOISTURE BOUNDARY LEFT BY THE CONVECTION TODAY AND TONIGHT. ALTHOUGH THE 40KM GFS HAS EXHIBITED A NORTHERN BIAS WITH THE TRANSLATION OF CONVECTIVE COMPLEXES...I COMPENSATED WITH A FURTHER SOUTHEAST SPATIAL MOVEMENT /175-200 NM/ AND TEMPORAL / UP TO 3 HOUR/ ADJUSTMENT WITH THE PRECIPITATION SHIELD FROM DOLLY. THIS MEANS THAT CONVECTION WILL LIKELY MOVE IN UP TO 6-12 HOURS FASTER THAN FORECAST WITH THE PACKAGE ISSUED SATURDAY MORNING. I HAVE GONE QUITE CONSERVATIVE WITH POP ESTIMATES...BUT LIKELY TO CATEGORICAL POP/WEATHER MAY NOT BE OUT OF THE QUESTION...ESPECIALLY LATE TUESDAY NIGHT INTO WEDNESDAY. ONCE DOLLY MOVES OUT...THE GFS SUGGESTS A MORE PRONOUNCED AND FASTER BUILDING OF THE WESTERN U.S. RIDGE INTO THE AREA. WITH THIS IN MIND...PRECIPITATION IS SHUT OFF FOR THE WFO PAH FORECAST AREA NO LATER THAN THURSDAY EVENING. NO CHANGES WERE MADE TO THE FORECAST PACKAGE BEYOND FRIDAY WITH THIS PACKAGE. GIVEN THE HIGHER HUMIDITY AND TEMPERATURES...A HEADLINE WAS ADDED TO THE TEXT ZONES FOR HEAT INDEX VALUES IN THE 100 TO 105 RANGE OVER SERN MO TODAY AND TUESDAY...AND OVER SWRN IN/WRN KY...AND PART OF SOUTHERN IL TUESDAY AFTERNOON. AS A FINAL NOTE...THE CURRENT PACKAGE INCLUDES PRE-FIRST PERIOD MENTION OF SENSIBLE WEATHER...THAT IS...SHOWERS AND THUNDERSTORMS THROUGH THE EARLY MORNING. ONCE MOST OF THE MESOSCALE CONVECTIVE SYSTEM DECAYS NEAR DAYBREAK...AN UPDATE/REVISION WILL BE MADE TO THE TEXT/TABULAR SUITE OF PRODUCTS. && .AVIATION... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DISSIPATE ACROSS PORTIONS OF MISSOURI...ILLINOIS AND INDIANA. CAN EXPECT MAINLY VFR/MVFR CONDITIONS WITH CLOUDS AND VISIBILITIES THROUGH 13Z. BY MID MORNING EXPECT ONLY SCT CU AND AC. SCT CB IS POSSIBLE AGAIN AFTER 18Z THAT WILL DISSIPATE AFTER 00Z AS HIGH PRESSURE BUILDS OVER THE REGION. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM...ML/SMITH LONG TERM....SMITH AVIATION...ML ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 909 PM EDT TUE JUL 29 2008 .SYNOPSIS... HIGH PRESSURE OFF THE COAST WILL ALLOW FOR A RETURN OF WARMER AND MORE HUMID CONDITIONS. A COLD FRONT OVER THE UPPER GREAT LAKES WILL APPROACH THE REGION WEDNESDAY BEFORE PASSING THROUGH ON THURSDAY. THIS WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. DRIER AIR IS EXPECTED BEHIND THE FRONT LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... WATER VAPOR LOOP SHOWS A TROUGH SWINGING EAST INTO THE CANADIAN MARITIMES AS RIDING BUILDS ACROSS THE OHIO VALLEY. A DUAL STREAM SYSTEM WAS MARCHING EAST ACROSS THE CENTRAL CONUS...WITH UPPER LOWS NORTH OF THE GREAT LAKES AND OVER THE PLAINS. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 50-100KT WESTERLY JET OVER THE UPPER MIDWEST...WHICH TROUGHS OVER NEW ENGLAND. 19Z SURFACE ANALYSIS PLACED A FRONTAL BOUNDARY FROM THE MIDWEST INTO THE TENNESSEE VALLEY...NORTHEAST INTO THE DELMARVA. A TROUGH WAS LOCATED IN THE LEE OF THE CENTRAL APPALACHIANS...WITH 1040MB ANTICYCLONE OVER THE MOUNTAINS. A SECONDARY BOUNDARY WAS STALLING ACROSS THE LOWER GREAT LAKES AND NEW ENGLAND. CONVECTION HAS SHOWED A DOWNWARD DIURNAL TREND THIS EVENING. WHILE 09Z SREF INDICATES A HIGH PROBABILITY OF RETAINING GREATER THAN 250 J/KG OF MUCAPE OVERNIGHT...DOES NOT APPEAR TO BE A TRIGGER AS RIDGING ALOFT SPREADS INTO THE REGION FROM THE OHIO VALLEY. WITH SKIES CLEARING THIS EVENING...AND MOISTURE INCREASING NORTH OF THE BAROCLINIC ZONE...ANTICIPATE AREAS OF FOG TO DEVELOP ESPECIALLY ACROSS THE SOUTHEAST FORECAST AREA (NORTH OF THE BOUNDARY) AND IN CLIMATOLOGICALLY FAVORED VALLEYS OUT WEST. CONVECTION ONGOING ACROSS MIDWEST AHEAD OF NEXT DUAL STREAM SYSTEM IS EXPECTED TO MOVE INTO THE OHIO VALLEY LATER TONIGHT. NAM/GFS SEEM TO BE STRUGGLING WITH THIS DEPICTION...SO HAVE RELIED ON EXPERIMENTAL HIGH RESOLUTION RAPID REFRESH RUC WRF-ARW3 FOR GUIDANCE THROUGH 08Z. THIS ACTIVITY EXPECTED TO INCREASE HIGH LEVEL CLOUDINESS LATE TONIGHT. IF MCV CAN HOLD TOGETHER AND ENOUGH WARMING OCCURS AHEAD OF FEATURE...ORGANIZED CONVECTION WOULD BE POSSIBLE WEDNESDAY. NEXT SHIFT SHOULD HAVE A BETTER HANDLE AS THINGS EVOLVE UPSTREAM. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... DEPENDING UPON WHICH MDL YOU LOOK AT WED AFTN COULD BE FULL OF XCTMNT OR RATEHR QUIET. NAM GIVING CAPES INXS OF 2000 WED AFTN GIVEN THE LATE JUL HEAT/HUMIDITY. I`M UNSURE IF THERE WL BE A TRIGGER TO MAKE WED AFTN MORE THAN SCT HVY RAINERS...WE`LL KEEP AN EYE ON LATER MDL RUNS FOR CLARIFICATION. HIGHS WED IN LM 90S XCPT IN HIGHLANDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... CONVECTION WITH THE TROUGH WEDNESDAY AFTERNOON WILL LINGER INTO THE EVENING HOURS...WEAKENING INTO THE OVERNIGHT. THE ACTUAL COLD FRONTAL PASSAGE ON THURSDAY WILL BRING THE LAST MENTIONABLE CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE FORECAST PERIOD. WHILE WEDNESDAY APPEARS TO BE THE BEST CHANCES FOR SEVERE WEATHER...THURSDAY COULD PROVIDE ITS OWN SET OF WEATHER CONCERNS. NOTABLE SHEAR WITH CONTINUED HEAT AND HUMIDITY ALONG WITH THE COLD FRONT WILL SUPPORT THUNDERSTORM DEVELOPMENT ON THURSDAY. TIMING THURSDAY SHOULD WAIT UNTIL THE AFTERNOON WITH THE BEST HEATING...BUT ANY OVERNIGHT ACTIVITY COULD SIMPLY CONTINUE INTO THURSDAY MORNING. SPC STILL HAS THE REGION UNDER A SLIGHT RISK AREA. WILL CARRY CHANCE POPS FOR THURSDAY WITH THE FRONT. THE FRONT IS EXPECTED TO BE EAST OF THE FORECAST AREA BY THURSDAY NIGHT...BRINGING NORTHWEST WINDS AND GRADUALLY CLEARING SKIES. HIGH PRESSURE AT THE SURFACE WILL BUILD THURSDAY NIGHT INTO FRIDAY AND LAST THROUGH MUCH OF THE FORECAST PERIOD. AS HIGH PRESSURE BUILDS ALOFT LATER IN THE PERIOD...INCREASING TEMPERATURES ARE POSSIBLE BY EARLY NEXT WEEK. WENT WITH THE COOLER HPC GUIDANCE FOR NOW...BUT THE MEX NUMBERS ARE WARMER AND MAY BE THE TREND IN LATER FORECASTS. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... INCREASING MOISTURE SHOULD PROVE FAVORABLE FOR FOG DEVELOPMENT OVERNIGHT...ESPECIALLY ALONG AND SE OF CHO-BWI LINE JUST NORTH OF FRONTAL ZONE...AND CLIMATOLOGICAL VALLEY LOCATIONS OUT WEST. VISIBILITIES EXPECTED TO DROP INTO IFR LATE TONIGHT. THUNDERSTORMS ACROSS OHIO VALLEY LATE TONIGHT EXPECTED TO ENCOURAGE HIGH CLOUDS TO MOVE INTO THE REGION TOMORROW...WITH SCATTERED CONVECTION POSSIBLE BY AFTERNOON. WITH NOT A LOT OF CONFIDENCE OF HOW THIS SCENARIO WILL PLAY OUT YET...SO HAVE INDICATED CONVECTIVE CHANCES WITH A CB GROUP AT THIS TIME. CONVECTION WILL BE ONGOING WEDNESDAY NIGHT AS THE SURFACE TROUGH MOVES THROUGH. CONVECTION CHANCES WILL RETURN ON THURSDAY AS THE COLD FRONT MOVES EAST. MVFR AND IFR CONDITIONS ARE POSSIBLE WITH STORMS WEDNESDAY NIGHT AND THURSDAY. HIGH PRESSURE WILL BUILD FOR THE WEEKEND. && .MARINE... SOUTHERLY FLOW INCREASES OVERNIGHT BUT IS NOT EXPECTED TO CROSS INTO SMALL CRAFT ADVISORY CRITERIA. SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST WEDNESDAY NIGHT AND THURSDAY. SOME STORMS WILL BE STRONG TO SEVERE...ESPECIALLY WEDNESDAY EVENING...PROMPTING SPECIAL MARINE WARNINGS. HIGH PRESSURE WILL BUILD OVER THE WATERS FOR FRIDAY AND CONTINUE THROUGH THE WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...WOODY! NEAR TERM...ROGOWSKI SHORT TERM...WOODY! LONG TERM...SAR AVIATION...ROGOWSKI/SAR MARINE...ROGOWSKI/SAR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 922 PM EDT MON JUL 28 2008 .SYNOPSIS... HIGH PRESSURE WILL SETTLE OVER THE MID ATLANTIC THROUGH TONIGHT...BEFORE MOVING OFFSHORE ON TUESDAY. WARMER AND MORE HUMID CONDITIONS WILL RETURN FOR THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE THROUGH THE AREA ON THURSDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... S/WV STARTING TO SHEAR APART AS IT CROSSES CWFA. DEWPT DEPRESSIONS QUITE LARGE...RESULTING IN DSPTG ECHOES LAST CPL HRS. WITH THAT IN MIND...HV RMVD THE EVE SCHC FOR CNTRL/SRN MD AND DC. HWVR...00Z LWX RAOB DEPICTS SGFNT MSTNG BTWN H8-6. 18Z NAM KEEPS THIS MSTR HANGING ARND...AND BASED ON SATPIX...THAT APPEARS RSNBL. IN ADDITION...21Z LWX WRF-ARW4 AND LTST RUC HINT AT PSBL QPF CNTRL SHEN VLY/INVOF CHO AFTR MIDNGT...AS ANTHR WK WV PASSES BY JUST TO THE S. CANT REALLY PICK OUT A CULPRIT ON WATER VAPOR IMAGERY...BUT BASED ON TRENDS PAST 6 HRS...CANT COMPLETELY DISCOUNT THAT SOLN EITHER. SUBSEQUENT CHGS TO FCST WL BE TO INCR CLDS JUST ABT EVERYWHERE OVRNGT...AND KEEP SCHC POPS SWRN CWFA OVNGT AS WELL. SUSPECT ANY PCPN WL BE SPRNKLY AT MOST. HV REDUCED CITY-OUTLYING MIN-T SPREAD AND INCRSD DEWPTS CONSIDERING ANTICIPATED CLDCVR. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... 18Z NAM KEEPS MID DECK MSTR INTO THE AFTN. AS A CONTINUATION OF 1ST PD CHGS...HV INCRSD CLDCVR TMRW MRNG AS WELL. SFC HIPRES NOT ALL THAT STRONG...AND H8-5 PTTN APPEARS TO BE SLGTLY TROFFY. ON THE WHOLE...DONT WISH TO BE AS PESSIMISTIC AS NAM...BUT CLDS LIKELY TO BE HOVERING BTWN SCT-BKN. WL BE KEEPING MAXT AS IS PER RISING HGTS. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... MODELS SHOW THE HEAT AND HUMIDITY BUILDING ACROSS THE CWA BY WEDNESDAY. MID 90S MAX T WITH NEAR 70 DEWPOINTS WILL MEAN HEAT INDEX VALUES CLOSE TO 100 DEG F. INSTABILITY WILL ALSO BE INCREASED...MAYBE TO 2K J/KG BY AFTERNOON. THIS WILL OCCUR SOUTHEAST OF A COLD FRONT...BUT MODELS ALSO HINT AT A SURFACE TROUGH ACROSS THE CWA. SO...AFTER INITIAL CAPPING...SCATTERED THUNDERSTORMS MAY BE ABLE TO FORM. MORE THUNDERSTORMS ARE EXPECTED THURSDAY AS A COLD FRONT WORKS ITS WAY THROUGH THE CWA. HAVE POPS NEAR 40 PCT. FRONT SHOULD MAKE IT THROUGH THE AREA FOR DRY WEATHER ON FRIDAY. 12Z GFS CONTINUES TO BUILD A STRONGER RIDGE FASTER LATER IN THE WEEKEND. GFS KEEPS CWA GENERALLY DRY INTO MONDAY...WHILE THE ECMWF BRINGS CHANCES OF CONVECTION BACK ON SUNDAY. WILL KEEP THE WEEKEND DRY AS THINK THE ECMWF IS TOO QUICK TO BRING BACK CONVECTION. IF THE RIDGE IS AS STRONG AS THE GFS DEPICTS...NEXT WEEK WILL BEGIN HOT AND DRY. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... VFR TO PREVAIL FOR THE NEXT 24 HOURS...W/ PLENTY OF MID DECK CLDS. CHO MAY ALSO SEE SOME PREDAWN MVFR FOG. THUNDERSTORMS WILL BE POSSIBLE WEDNESDAY THROUGH THURSDAY...AS A COLD FRONT MOVES THROUGH ON THURSDAY. && .MARINE... LIGHT WINDS...10 KNOTS OR LESS...WILL CONTINUE OVER THE WATERS THRU TUE. WILL HAVE TO WATCH SOUTHERLY FLOW WEDNESDAY INTO THURSDAY AS IT COULD TEASE SMALL CRAFT ADVISORY UNTIL A COLD FRONT MOVES THROUGH ON THURSDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...PELOQUIN NEAR TERM...HTS SHORT TERM...HTS LONG TERM...PELOQUIN AVIATION...HTS/PELOQUIN MARINE...HTS/PELOQUIN md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 735 PM EDT TUE JUL 29 2008 UPDATED FOR 00Z AVIATION DISCUSSION .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A LOW OVER WESTERN ONTARIO WITH A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW MOVING THROUGH WESTERN LAKE SUPERIOR AND THE WESTERN U.P. A COLD FRONT EXTENDS FROM A LOW OVER WESTERN ONTARIO THROUGH DULUTH AND THE UPPER MISSISSIPPI RIVER VALLEY. NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS ARE FIRING OVER EASTERN U.P. AND LAKE SUPERIOR. NEW SHOWERS AND THUNDERSTORMS ARE DEVELOPING OVER WESTERN U.P. IN AN AREA OF INSTABILITY AHEAD OF THE FRONTAL BOUNDARY. THESE ARE MOVING EAST AT 35 TO 40 MPH PRODUCING BRIEF HEAVY RAINS. && .SHORT TERM... (TONIGHT AND WEDNESDAY) THE MID LEVEL LOW WILL MOVE INTO CENTRAL ONTARIO...WHILE WEAK SHORTWAVES SWEEP THROUGH THE NORTHERN PART OF THE FORECAST AREA TONIGHT. THE COLD FRONT WILL ADVANCE ACROSS THE U.P. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL GENERATE MORE SHOWERS AND THUNDERSTORMS. AN UPPER LEVEL JET MAX IS OVER NORTHERN MINNESOTA AND WILL CROSS UPPER MICHIGAN PLACING THE STRONGEST UPPER LEVEL DIVERGENCE OVER THE CENTRAL AND EASTERN U.P. WARM AIR ADVECTION AT 850MB AHEAD OF THE FRONT WILL CONTRIBUTE TO DESTABILIZING THE ATMOSPHERE PRODUCING SOME MUCAPE VALUES GREATER THAN 2000J/KG AND A PRONOUNCED THETA-E RIDGE AHEAD OF THE FRONT. CONDITIONS CONTINUE TO LOOK FAVORABLE FOR SEVERE WEATHER DEVELOPMENT. WEAK SHORTWAVE ENERGY PASSING OVER THE EASTERN U.P. WILL PRODUCE JUST A CHANCE OF THUNDERSTORMS OVER THE EASTERN U.P. ON WEDNESDAY. DRY AIR FOLLOWING THE FRONT WILL LIMIT THE SHOWERS AND THUNDERSTORMS. .LONG TERM... (WED NIGHT THRU TUE) WED NIGHT INTO THU...SHORTWAVE RIDGING AND ASSOCIATED SFC HIGH PRES WILL BE MOVING INTO THE UPPER GREAT LAKES ALONG WITH A DRY AIRMASS. SO...TRANQUIL/SEASONABLE WEATHER IS EXPECTED. LAKE BREEZES WILL BE THE RULE NEAR LAKE SUPERIOR THU AS HIGH PRES DRIFTS SE TO LAKE SUPERIOR. IT MAY NOT BE UNTIL LATE IN THE DAY THAT THE LAKE BREEZE DEVELOPS NEAR LAKE MICHIGAN. FRI THRU TUE...MODELS ARE IN REASONABLE AGREEMENT THAT THE RIDGE OVER THE SW CONUS WILL EXPAND EWD LATE WEEK THRU THE WEEKEND SO THAT BY EARLY NEXT WEEK THE RIDGE DOMINATES THE SRN HALF OF THE CONUS. AT THE SAME TIME...A MIDLEVEL LOW WILL TRACK E ACROSS SRN CANADA TOWARD JAMES BAY BY MON PER ECMWF/GFS AND GFS ENSEMBLES. RESULT WILL BE AN EWD EXPANSION OF HEAT ACROSS THE CONUS WITH THE UPPER GREAT LAKES BECOMING FAVORED FOR POTENTIAL OF PERIODIC CONVECTION ON THE EDGE OF THE HEAT AND UNDER THE UPPER JET. PATTERN SUPPORTS THE POSSIBILITY OF AN EPISODE OF STRONG OR SVR STORMS. THU NIGHT/FRI OFFERS THE FIRST OPPORTUNITY OF SHRA/TSRA AS APPROACHING SUBTLE SHORTWAVE INCREASES LOW-LEVEL JET. HOWEVER...LOCATION OF THE NOSE OF LOW-LEVEL JET/STRONGEST THETA-E ADVECTION SUGGESTS A SE MOVING CLUSTER OF SHRA/TSRA SHOULD PASS TO THE SW AND S OF THE FCST AREA. THERE MAY BE ADDITIONAL SCT CONVECTION FARTHER N ALONG APPROACHING 850MB TROF... BUT CONFIDENCE IN PCPN OCCURRING IS TOO LOW TO INCLUDE POPS ACROSS THE AREA WITH THIS FEATURE LATE THU NIGHT/FRI. THERE IS LITTLE CONFIDENCE IN TIMING PCPN CHANCES BEYOND FRI...BUT RIGHT NOW IT APPEARS THAT THERE WILL BE AT LEAST ONE OPPORTUNITY FOR SHRA/TSRA SAT/SUN AS COLD FRONT APPROACHES. WILL OPT FOR DRY WEATHER MON/TUE IN THE WAKE OF THE COLD FRONT ASSOCIATED WITH EWD MOVING CLOSED LOW ACROSS SRN CANADA. TEMPS WILL BE ABOVE SEASONAL NORMALS THRU THE WEEKEND...THEN RETURN CLOSER TO NORMAL MON/TUE. IT WILL PROBABLY BE UNCOMFORTABLY HOT/HUMID AT LEAST ONE OF THE DAYS (MOST LIKELY SAT) PRIOR TO FROPA LATE IN THE WEEKEND. IN ADDITION...DEPENDING ON PCPN OCCURRENCE...WOULD NOT BE SURPRISED IF MIN TEMPS SAT NIGHT DON`T FALL BELOW 70F IN SOME AREAS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... ISOLATED THUNDERSTORMS HAVE DEVELOPED DURING THE AFTERNOON HOURS...BUT HAVE REMAINED AWAY FROM THE TAF SITES. CHANCES FOR THUNDERSTORMS IN CMX AREA APPEAR TO HAVE DIMINISHED...BUT WILL KEEP MENTION OF CB IN FOR SAW WHILE THUNDERSTORMS REMAIN ACROSS THE REGION. VFR CONDITIONS SHOULD THEN PERSIST DURING THE OVERNIGHT HOURS BEHIND THE COLD FRONT. ADDITIONAL MOIST AIR SHOULD MOVE ACROSS LAKE SUPERIOR TOMORROW...AND MAY DROP VISIBILITIES TO MVFR AT CMX. COOLER TEMPERATURES SHOULD SUPPORT MIXING A LITTLE WIND TO SURFACE BY LATE MORNING INTO THE AFTERNOON...SO WILL BE LOOKING FOR SOME GUSTY CONDITIONS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS COLD FRONT MOVES ACROSS LAKE SUPERIOR TONIGHT...WINDS AHEAD OF THE FRONT WILL BE SOUTHERLY AND MAY INCREASE TO 25 KT. WIND SPEEDS WILL DIMINISH SLIGHTLY BEHIND THE FRONT AS THE DIRECTION SHIFTS TO THE WEST. FURTHER DIMINISHING OF WINDS IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS HIGH PRESSURE DROPS OUT OF CANADA ACROSS LAKE SUPERIOR. LOOK FOR WINDS TO GRADUALLY PICK UP FRIDAY AFTERNOON INTO SAT AS ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE PLAINS. SPEEDS SHOULD REMAIN UNDER 25 KNOTS THROUGH THE REST OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...ROLFSON AVIATION...TAG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 355 PM EDT TUE JUL 29 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A LOW OVER WESTERN ONTARIO WITH A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW MOVING THROUGH WESTERN LAKE SUPERIOR AND THE WESTERN U.P. A COLD FRONT EXTENDS FROM A LOW OVER WESTERN ONTARIO THROUGH DULUTH AND THE UPPER MISSISSIPPI RIVER VALLEY. NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS ARE FIRING OVER EASTERN U.P. AND LAKE SUPERIOR. NEW SHOWERS AND THUNDERSTORMS ARE DEVELOPING OVER WESTERN U.P. IN AN AREA OF INSTABILITY AHEAD OF THE FRONTAL BOUNDARY. THESE ARE MOVING EAST AT 35 TO 40 MPH PRODUCING BRIEF HEAVY RAINS. && .SHORT TERM... (TONIGHT AND WEDNESDAY) THE MID LEVEL LOW WILL MOVE INTO CENTRAL ONTARIO...WHILE WEAK SHORTWAVES SWEEP THROUGH THE NORTHERN PART OF THE FORECAST AREA TONIGHT. THE COLD FRONT WILL ADVANCE ACROSS THE U.P. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL GENERATE MORE SHOWERS AND THUNDERSTORMS. AN UPPER LEVEL JET MAX IS OVER NORTHERN MINNESOTA AND WILL CROSS UPPER MICHIGAN PLACING THE STRONGEST UPPER LEVEL DIVERGENCE OVER THE CENTRAL AND EASTERN U.P. WARM AIR ADVECTION AT 850MB AHEAD OF THE FRONT WILL CONTRIBUTE TO DESTABILIZING THE ATMOSPHERE PRODUCING SOME MUCAPE VALUES GREATER THAN 2000J/KG AND A PRONOUNCED THETA-E RIDGE AHEAD OF THE FRONT. CONDITIONS CONTINUE TO LOOK FAVORABLE FOR SEVERE WEATHER DEVELOPMENT. WEAK SHORTWAVE ENERGY PASSING OVER THE EASTERN U.P. WILL PRODUCE JUST A CHANCE OF THUNDERSTORMS OVER THE EASTERN U.P. ON WEDNESDAY. DRY AIR FOLLOWING THE FRONT WILL LIMIT THE SHOWERS AND THUNDERSTORMS. .LONG TERM... (WED NIGHT THRU TUE) WED NIGHT INTO THU...SHORTWAVE RIDGING AND ASSOCIATED SFC HIGH PRES WILL BE MOVING INTO THE UPPER GREAT LAKES ALONG WITH A DRY AIRMASS. SO...TRANQUIL/SEASONABLE WEATHER IS EXPECTED. LAKE BREEZES WILL BE THE RULE NEAR LAKE SUPERIOR THU AS HIGH PRES DRIFTS SE TO LAKE SUPERIOR. IT MAY NOT BE UNTIL LATE IN THE DAY THAT THE LAKE BREEZE DEVELOPS NEAR LAKE MICHIGAN. FRI THRU TUE...MODELS ARE IN REASONABLE AGREEMENT THAT THE RIDGE OVER THE SW CONUS WILL EXPAND EWD LATE WEEK THRU THE WEEKEND SO THAT BY EARLY NEXT WEEK THE RIDGE DOMINATES THE SRN HALF OF THE CONUS. AT THE SAME TIME...A MIDLEVEL LOW WILL TRACK E ACROSS SRN CANADA TOWARD JAMES BAY BY MON PER ECMWF/GFS AND GFS ENSEMBLES. RESULT WILL BE AN EWD EXPANSION OF HEAT ACROSS THE CONUS WITH THE UPPER GREAT LAKES BECOMING FAVORED FOR POTENTIAL OF PERIODIC CONVECTION ON THE EDGE OF THE HEAT AND UNDER THE UPPER JET. PATTERN SUPPORTS THE POSSIBILITY OF AN EPISODE OF STRONG OR SVR STORMS. THU NIGHT/FRI OFFERS THE FIRST OPPORTUNITY OF SHRA/TSRA AS APPROACHING SUBTLE SHORTWAVE INCREASES LOW-LEVEL JET. HOWEVER...LOCATION OF THE NOSE OF LOW-LEVEL JET/STRONGEST THETA-E ADVECTION SUGGESTS A SE MOVING CLUSTER OF SHRA/TSRA SHOULD PASS TO THE SW AND S OF THE FCST AREA. THERE MAY BE ADDITIONAL SCT CONVECTION FARTHER N ALONG APPROACHING 850MB TROF... BUT CONFIDENCE IN PCPN OCCURRING IS TOO LOW TO INCLUDE POPS ACROSS THE AREA WITH THIS FEATURE LATE THU NIGHT/FRI. THERE IS LITTLE CONFIDENCE IN TIMING PCPN CHANCES BEYOND FRI...BUT RIGHT NOW IT APPEARS THAT THERE WILL BE AT LEAST ONE OPPORTUNITY FOR SHRA/TSRA SAT/SUN AS COLD FRONT APPROACHES. WILL OPT FOR DRY WEATHER MON/TUE IN THE WAKE OF THE COLD FRONT ASSOCIATED WITH EWD MOVING CLOSED LOW ACROSS SRN CANADA. TEMPS WILL BE ABOVE SEASONAL NORMALS THRU THE WEEKEND...THEN RETURN CLOSER TO NORMAL MON/TUE. IT WILL PROBABLY BE UNCOMFORTABLY HOT/HUMID AT LEAST ONE OF THE DAYS (MOST LIKELY SAT) PRIOR TO FROPA LATE IN THE WEEKEND. IN ADDITION...DEPENDING ON PCPN OCCURRENCE...WOULD NOT BE SURPRISED IF MIN TEMPS SAT NIGHT DON`T FALL BELOW 70F IN SOME AREAS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH A COLD FRONT MOVING IN...THERE SHOULD BE MORE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS...BUT LOCATION IS HIGHLY UNCERTAIN. THEREFORE TEMPO GROUPS CONTINUE AT BOTH TAF SITES...LONGEST AT SAW WHERE THE COLD FRONT DOES NOT PASS UNTIL LATE IN THE EVENING. NO MENTION OF TS GIVEN UNCERTAIN LOCATION OF DEVELOPMENT...BUT CB GROUPS ARE WARRANTED. VFR CONDITIONS EXPECTED IN THE WAKE OF THE COLD FRONT. COOLER TEMPERATURES SHOULD SUPPORT MIXING A LITTLE WIND TO SURFACE BY LATE MORNING SO WILL BE LOOKING FOR SOME GUSTY CONDITIONS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS COLD FRONT MOVES ACROSS LAKE SUPERIOR TONIGHT...WINDS AHEAD OF THE FRONT WILL BE SOUTHERLY AND MAY INCREASE TO 25 KT. WIND SPEEDS WILL DIMINISH SLIGHTLY BEHIND THE FRONT AS THE DIRECTION SHIFTS TO THE WEST. FURTHER DIMINISHING OF WINDS IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS HIGH PRESSURE DROPS OUT OF CANADA ACROSS LAKE SUPERIOR. LOOK FOR WINDS TO GRADUALLY PICK UP FRIDAY AFTERNOON INTO SAT AS ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE PLAINS. SPEEDS SHOULD REMAIN UNDER 25 KNOTS THROUGH THE REST OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...ROLFSON AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 PM EDT TUE JUL 29 2008 .SHORT TERM...TODAY. WATER VAPOR IMAGERY AND RUC SHOWING A LOW OVER WESTERN ONTARIO WITH A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW MOVING THROUGH WESTERN LAKE SUPERIOR AND THE WESTERN U.P. A COLD FRONT EXTENDS FROM A LOW OVER WESTERN ONTARIO THROUGH DULUTH AND THE UPPER MISSISSIPPI RIVER VALLEY. NUMEROUS THUNDERSTORMS ARE FIRING IN A LINE STRETCHING FROM HOUGHTON TO EAGLE RIVER WI. THESE ARE MOVING EAST AT 35 TO 40 MPH PRODUCING BRIEF HEAVY RAINS. WEAK SHORTWAVES WILL SWEEP THROUGH THE NORTHERN PART OF THE FORECAST AREA THIS AFTERNOON AS THE COLD FRONT ADVANCES INTO THE U.P. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL GENERATE MORE SHOWERS AND THUNDERSTORMS THIS AFTERNOON. AN UPPER LEVEL JET MAX IS OVER NORTHERN MINNESOTA AND WILL MOVE INTO WESTERN LAKE SUPERIOR THIS AFTERNOON PLACING THE STRONGEST UPPER LEVEL DIVERGENCE OVER THE CENTRAL CENTRAL U.P. WARM AIR ADVECTION AT 850MB AHEAD OF THE FRONT WILL CONTRIBUTE TO DESTABILIZING THE ATMOSPHERE PRODUCING SOME MUCAPE VALUES GREATER THAN 2000J/KG AND A THETA-E RIDGE AHEAD OF THE FRONT. CONDITIONS CONTINUE TO LOOK FAVORABLE FOR SEVERE WEATHER DEVELOPMENT. .LONG TERM... THE 500MB LOW IS FIGURED TO TRACK TO CENTRAL ONTARIO BY 12Z WEDNESDAY...AND NEAR THE ONTARIO AND QUEBEC BORDER AROUND 12Z THURSDAY. AT THAT TIME...THE LARGE RIDGE OVER THE SOUTHWEST WILL SURGE INTO THE UPPER GREAT LAKES...WITH THE RIDGE AXIS BEING OVERHEAD FROM ROUGHLY 18Z THURSDAY THROUGH EARLY SATURDAY. AFTER THAT TIME A MORE ZONAL PATTERN OR BROAD SCALE TROUGH IS FIGURED THROUGH THE WEEKEND. ON SATURDAY...SPC IS HIGHLIGHTING THE POTENTIAL FOR...AS STATED IN THE DAY 4-8 CONVECTIVE OUTLOOK...A VERY SIGNIFICANT/DERECHO TYPE MESOSCALE CONVECTIVE SYSTEM EXISTS. WITH MODELS COMING INTO BETTER AGREEMENT IN THE MIDDLE TO LONG RANGE OF THE FORECAST PERIOD...THIS MAY BE A VIABLE SOLUTION. HAVE HIGHLIGHTED ONLY THUNDERSTORMS THUS FAR IN THE HWO...BUT WILL NEED TO CONTINUE TO MONITOR THE EVOLUTION OF THIS WEEKEND SYSTEM. MODEL WISE...THE NAM CAME IN SLOWER ONCE AGAIN...BUT WILL STILL PREFERRED OVER THE GFS AS IT WAS MORE IN LINE WITH OTHER MODELS IN THE NEAR TERM. BELIEVE THAT THE NAM MAY BE TOO SLOW HOWEVER ONCE WE GET BEYOND THURSDAY AFTERNOON. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH A COLD FRONT MOVING IN...THERE SHOULD BE MORE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS...BUT LOCATION IS HIGHLY UNCERTAIN. THEREFORE TEMPO GROUPS CONTINUE AT BOTH TAF SITES...LONGEST AT SAW WHERE THE COLD FRONT DOES NOT PASS UNTIL LATE IN THE EVENING. NO MENTION OF TS GIVEN UNCERTAIN LOCATION OF DEVELOPMENT...BUT CB GROUPS ARE WARRANTED. VFR CONDITIONS EXPECTED IN THE WAKE OF THE COLD FRONT. COOLER TEMPERATURES SHOULD SUPPORT MIXING A LITTLE WIND TO SURFACE BY LATE MORNING SO WILL BE LOOKING FOR SOME GUSTY CONDITIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS WILL MOVE ACROSS LAKE SUPERIOR TONIGHT. AHEAD OF THE FRONT...EXPECT SOUTHERLY WINDS TO INCREASE...ESPECIALLY ACROSS THE EAST HALF OF LAKE SUPERIOR WHERE SPEEDS MAY REACH 25 KT. WIND SPEEDS WILL DIMINISH SLIGHTLY BEHIND THE FRONT AS THE DIRECTION SHIFTS TO THE WEST. FURTHER DIMINISHING OF WINDS IS EXPECTED WED NIGHT THROUGH THU NIGHT AS HIGH PRESSURE DROPS DOWN OUT OF CANADA ACROSS LAKE SUPERIOR. LOOK FOR WINDS TO GRADUALLY PICK FRI AFTERNOON INTO SAT AS ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE PLAINS. SPEEDS SHOULD REMAIN UNDER 25 KNOTS...THOUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...DG LONG TERM...KF AVIATION...DG MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 133 AM EDT TUE JUL 29 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER WEST CENTRAL QUEBEC...A RIDGE OVER WESTERN ONTARIO...AND ANOTHER LOW OVER NORTHERN SASKATCHEWAN. WEAK SHORTWAVES MOVING THROUGH THE BASE OF THE SASKATCHEWAN LOW ARE MOVING THROUGH THE APEX OF THE RIDGE. SURFACE ANALYSIS DEPICTS A LARGE RIDGE OVER ONTARIO AND THE UPPER GREAT LAKES. A LOW IS OVER THE MIDDLE AND HIGH PLAINS...WITH A WARM FRONT EXTENDING OUT AHEAD OF THE LOW INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. && .SHORT TERM (TODAY AND TONIGHT)... MAIN FORECAST CONCERN IS THUNDERSTORM DEVELOPMENT FOR TONIGHT AND TUESDAY. UPPER RIDGE OVER THE WESTERN PART OF OUR CWA WILL CONTINUE TO SLIDE EASTWARD THROUGH TONIGHT...WHILE THE SHORTWAVE OVER SOUTHWEST ALBERTA MOVES TO SOUTHEAST MANITOBA BY SUNRISE TUESDAY. THESE MID LEVEL FEATURES SUGGEST THAT THE UPPER GREAT LAKES REGION WILL BE UNDER WARM ADVECTION. WITH THE APPROACHING SHORTWAVE...MOST MODELS SHOW A SURFACE LOW OVER CENTRAL MANITOBA BY 12Z...MEANING THAT THE WARM ADVECTION WILL LIKELY BE ACCOMPANIED BY A FAIRLY STRONG LOW LEVEL JET. NAM PROGGED 850MB WINDS ARE AROUND 30 KT OUT OF THE SOUTHWEST ACROSS MINNESOTA. 850MB THETA-E ADVECTION VALUES INCREASE ACROSS NORTHERN MINNESOTA INTO THE WESTERN CWA...SUGGESTING PRETTY GOOD MOISTURE RETURNING WITH THE LOW LEVEL JET. ANOTHER ZONE OF STRONG ADVECTION VALUES EXIST IN SOUTHERN MINNESOTA AND NORTHERN IOWA. WESTERN ZONES ARE LIKELY AREAS FOR THUNDERSTORMS LATE TONIGHT...MAINLY AFTER 06Z. SOME CONCERN EXISTS FOR HAIL GIVEN MUCAPES AROUND 1000 J/KG AND EFFECTIVE SHEAR VALUES OF 25-30 KT. THE FREEZING LEVEL HEIGHTS ARE AROUND 14000 FT. GIVEN INCREASING CLOUD COVER FROM THE WARM ADVECTION...INCREASING SOUTHERLY WINDS AND HIGHER DEWPOINTS MOVING IN...LOW TEMPERATURES SHOULD GENERALLY BE IN THE 50S TO LOW 60S. COOLEST READINGS EXPECTED IN THE EAST WHERE MOSTLY CLEAR SKIES AND LIGHT WINDS IN THE EVENING ALLOW FOR GREATER RADIATIONAL COOLING. THE MANITOBA UPPER LEVEL TROUGH WILL SHIFTS INTO NORTHWEST ONTARIO ON TUESDAY. A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW WILL SWEEP ACROSS THE FORECAST AREA. MEANWHILE...A COLD FRONT WILL APPROACH WESTERN LAKE SUPERIOR AND IWD BY LATE AFTERNOON. CONVECTIVE FEEDBACK IN THE MODELS FROM CONVECTION TONIGHT OVER NORTHERN MINNESOTA RESULTS IN SOME ISSUES WITH THE FORECAST...HOWEVER...THERE IS A GENERAL CONSENSUS THAT THE ECMWF/NAM BLEND LOOKS BEST. NAM FOR WHATEVER MCS THAT DEVELOPS OVER NRN MINNESOTA/WESTERN LAKE SUPERIOR WILL SLIDE AND WEAKEN AS IT CROSSES THE CWA THROUGH THE DAY. THEREFORE PRECIPITATION CHANCES WILL BE REDUCED IN THE FORECAST AS MUCH OF THE CONVECTION IS ASSUMED TO BE ELEVATED AND NOT SURFACE BASED. ALL SURFACE BASED CONVECTION SHOULD OCCUR TO THE SOUTH OF THE CWA DUE TO OUTFLOW BOUNDARIES FROM THIS MCS. IF OUR LOCAL WRF-ARW RUN IS CORRECT AND KEEPING MUCH OF THE MCS ACTIVITY ACROSS LAKE SUPERIOR AND THE NORTHERN U.P....THEN THERE WOULD BE AN OPPORTUNITY FOR THE SOUTHERN U.P. TO HEAT UP AND THUS RESULT IN SOME SURFACE BASED CONVECTION. REGARDING SEVERE CHANCES...SIMILAR CONDITIONS EXIST TO TONIGHT WITH MUCAPES BETWEEN 1000-1500 J/KG... EFFECTIVE SHEAR VALUES OF 25-30 KT AND FREEZING LEVELS NEAR 14000 FT...WITH INSTABILITY DIMINISHING TO THE EAST. THEREFORE SOME HAIL IS NOT OUT OF THE QUESTION...BEST CHANCES IN THE WESTERN U.P WHERE HIGHER INSTABILITY IS PRESENT. HIGH TEMPERATURES ARE TRICKY...WITH CONCERN OF LOCATION OF MCS AND 850MB TEMPS OF 15-19C AT LEAST. WILL STAY ON THE CONSERVATIVE END OF GUIDANCE...WITH WARMEST READINGS IN THE SOUTH CENTRAL U.P.. .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... TUE NIGHT...ALTHOUGH FEEDBACK PROBLEMS WITH THE GFS WERE NOT AS SEVERE AS PREVIOUS RUNS AND THE MDL WAS NOT AS MUCH OF AN OUTLIER COMPARED TO THE OTHER MODELS...THE SLOWER NAM SCENARIO...SUPPORTED BY THE UKMET/ECMWF AND CANADIAN REGIONAL GEM...WAS STILL PREFERRED. SO...WITH THE FRONT/TROUGH JUST MOVING INTO W UPPER MI AROUND 00Z...EXPECT CONTINUING POTENTIAL FOR SCT SHRA/TSRA ACROSS THE CNTRL AND EAST CWA BTWN 00Z-06Z SUPPORTED BY LOW LEVEL CONV AND QVECTOR CONV AHEAD OF THE LOW AND MID LEVEL TROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS WILL LINGER WITH MLCAPE VALUES AROUND 1000-1500 J/KG AND 0-6KM SHEAR VALUES INCREASING INTO THE 35-40 KT RANGE...ESPECIALLY NEAR THE WI BORDER WHERE THE INSTABILITY WILL BE GREATEST. WITH THE LOSS OF DIURNAL HEATING AND THE EXITING 950-850 MB CONV...EXPECT REMAINING SHRA/TSRA TO WEAKEN OR EXIT THE CWA BY 03Z-06Z. WED...LOW LEVEL DRY ADVECTION BEHIND THE TROUGH AND MID LEVEL SUBSIDENCE DRYING WITH THE DRY SLOT AND AREA OF QVECTOR DIV WILL HAMPER DEEP CONVECTION OVER MOST OF THE CWA. HOWEVER...ENOUGH LOW LEVEL MOISTURE WILL LINGER OVER THE ERN CWA SO THAT LOW LEVEL CONV ALONG LAKE IN PREVAILING WRLY MAY TRIGGER SCT OR ISOLD SHRA/TSRA. WED NIGHT INTO THU...MDLS WERE IN AGREEMENT WITH A DRY AIRMASS AND HIGH PRES SETTLING INTO THE AREA WITH NO PCPN EXPECTED. THU NIGHT...MDLS DIFFER WITH DEGREE OF RETURN WAA/MOISTURE. THE FCST LEANED MORE TOWARD THE LESS PROGRESSIVE ECMWF WHICH KEPT BEST LOW LEVEL THETA-E ADVECTION FARTHER TO THE WEST. FRI-MON...THE FCST...IN LINE WITH THE HPC PREFERRED 00Z GFS AND ENS 00Z GFS ENS MEAN...BRINGS IN POTENTIAL FOR SHRA/TSRA SAT INTO SUN WITH THE UPPER LAKES AFFECTED BY WAA AND SHORTWAVES ON THE PERIPHERY OF THE RIDGE. FOR NOW...NOT PCPN WAS MENTIONED FOR FRI...BUT SHRA/TSRA CHANCES MAY NEED TO BE ADDED...PER ECMWF...IF BETTER MDLS CONSENSUS EMERGES WITH DETAILS OF MOISTURE AND THE WAA PATTERN. MDLS WERE IN GENERAL AGREEMENT...THROUGH WITH TIMING DIFFERENCES...IN TRANSITION TOWARD MORE ZONAL PATTERN WITH A PROGRESSIVE TROUGH THROUGH SRN CANADA EVENTUALLY BRINGING A FRONT THROUGH THE AREA SAT NIGHT OR SUN WITH ADDITIONAL SHRA/TSRA CHANCES. TEMPS AOA SEASONAL AVERAGES ARE EXPECTED SAT AND POSSIBLY SUN BUT RETURN TO MORE NORMAL CONDITIONS BY MON. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS SHOULD REMAIN THROUGH THE PERIOD EVEN WITH SHOWERS ARRIVING BY LATE MORNING TO EARLY AFTERNOON FOR BOTH PLACES. SHOWERS WILL END IN THE EVENING WITH CONDITIONS STAYING LOW VFR FOR CIGS AT BOTH PLACES. COULD BE SOME THUNDER AT BOTH PLACES...BUT CONFIDENCE IS NOT HIGH ENOUGH TO FORECAST THUNDERSTORMS AT THIS TIME. HEDGED WITH CB GROUP FOR CLOUD COVER INSTEAD UNTIL IT BECOMES MORE APPARENT THAT THUNDERSTORMS WILL AFFECT BOTH SITES. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE HIGH DIRECTLY OVERHEAD KEEP WINDS LIGHT TONIGHT. THE LIGHT WINDS WILL BE SHORT LIVED AS A LOW PRESSURE TROUGH MOVES IN FROM THE HIGH PLAINS ON TUESDAY. WINDS WILL BECOMING SOUTHERLY AND STRENGTHEN THROUGH TUESDAY AFTERNOON. WINDS WILL BE STRONG ONCE AGAIN FROM THE WEST WEDNESDAY AFTERNOON...AS THE LOW SLOWLY MOVES EASTWARD TO THE NEW ENGLAND STATES BY THURSDAY MORNING. HIGH PRESSURE WILL THEN MOVE OVER LAKE SUPERIOR FOR ONCE AGAIN FOR THURSDAY AND FRIDAY...WITH WINDS GENERALLY LESS THAN 15 KTS. WIND WILL AGAIN INCREASE FOLLOWING ANOTHER COLD FRONT ON SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...GM MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 720 PM EDT MON JUL 28 2008 MAIN FORECAST CONCERN IS THUNDERSTORM DEVELOPMENT FOR TONIGHT AND TUESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER WEST CENTRAL QUEBEC...A RIDGE OVER WESTERN ONTARIO...AND ANOTHER LOW OVER NORTHERN SASKATCHEWAN. WEAK SHORTWAVES MOVING THROUGH THE BASE OF THE SASKATCHEWAN LOW ARE MOVING THROUGH THE APEX OF THE RIDGE. SURFACE ANALYSIS DEPICTS A LARGE RIDGE OVER ONTARIO AND THE UPPER GREAT LAKES. A LOW IS OVER THE MIDDLE AND HIGH PLAINS...WITH A WARM FRONT EXTENDING OUT AHEAD OF THE LOW INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. .SHORT TERM...TODAY AND TONIGHT. UPPER RIDGE OVER THE WESTERN PART OF OUR CWA WILL CONTINUE TO SLIDE EASTWARD THROUGH TONIGHT...WHILE THE SHORTWAVE OVER SOUTHWEST ALBERTA MOVES TO SOUTHEAST MANITOBA BY SUNRISE TUESDAY. THESE MID LEVEL FEATURES SUGGEST THAT THE UPPER GREAT LAKES REGION WILL BE UNDER WARM ADVECTION. WITH THE APPROACHING SHORTWAVE...MOST MODELS SHOW A SURFACE LOW OVER CENTRAL MANITOBA BY 12Z...MEANING THAT THE WARM ADVECTION WILL LIKELY BE ACCOMPANIED BY A FAIRLY STRONG LOW LEVEL JET. NAM PROGGED 850MB WINDS ARE AROUND 30 KT OUT OF THE SOUTHWEST ACROSS MINNESOTA. 850MB THETA-E ADVECTION VALUES INCREASE ACROSS NORTHERN MINNESOTA INTO THE WESTERN CWA...SUGGESTING PRETTY GOOD MOISTURE RETURNING WITH THE LOW LEVEL JET. ANOTHER ZONE OF STRONG ADVECTION VALUES EXIST IN SOUTHERN MINNESOTA AND NORTHERN IOWA. WESTERN ZONES ARE LIKELY AREAS FOR THUNDERSTORMS LATE TONIGHT...MAINLY AFTER 06Z. SOME CONCERN EXISTS FOR HAIL GIVEN MUCAPES AROUND 1000 J/KG AND EFFECTIVE SHEAR VALUES OF 25-30 KT. THE FREEZING LEVEL HEIGHTS ARE AROUND 14000 FT. GIVEN INCREASING CLOUD COVER FROM THE WARM ADVECTION...INCREASING SOUTHERLY WINDS AND HIGHER DEWPOINTS MOVING IN...LOW TEMPERATURES SHOULD GENERALLY BE IN THE 50S TO LOW 60S. COOLEST READINGS EXPECTED IN THE EAST WHERE MOSTLY CLEAR SKIES AND LIGHT WINDS IN THE EVENING ALLOW FOR GREATER RADIATIONAL COOLING. THE MANITOBA UPPER LEVEL TROUGH WILL SHIFTS INTO NORTHWEST ONTARIO ON TUESDAY. A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW WILL SWEEP ACROSS THE FORECAST AREA. MEANWHILE...A COLD FRONT WILL APPROACH WESTERN LAKE SUPERIOR AND IWD BY LATE AFTERNOON. CONVECTIVE FEEDBACK IN THE MODELS FROM CONVECTION TONIGHT OVER NORTHERN MINNESOTA RESULTS IN SOME ISSUES WITH THE FORECAST...HOWEVER...THERE IS A GENERAL CONSENSUS THAT THE ECMWF/NAM BLEND LOOKS BEST. NAM FOR WHATEVER MCS THAT DEVELOPS OVER NRN MINNESOTA/WESTERN LAKE SUPERIOR WILL SLIDE AND WEAKEN AS IT CROSSES THE CWA THROUGH THE DAY. THEREFORE PRECIPITATION CHANCES WILL BE REDUCED IN THE FORECAST AS MUCH OF THE CONVECTION IS ASSUMED TO BE ELEVATED AND NOT SURFACE BASED. ALL SURFACE BASED CONVECTION SHOULD OCCUR TO THE SOUTH OF THE CWA DUE TO OUTFLOW BOUNDARIES FROM THIS MCS. IF OUR LOCAL WRF-ARW RUN IS CORRECT AND KEEPING MUCH OF THE MCS ACTIVITY ACROSS LAKE SUPERIOR AND THE NORTHERN U.P....THEN THERE WOULD BE AN OPPORTUNITY FOR THE SOUTHERN U.P. TO HEAT UP AND THUS RESULT IN SOME SURFACE BASED CONVECTION. REGARDING SEVERE CHANCES...SIMILAR CONDITIONS EXIST TO TONIGHT WITH MUCAPES BETWEEN 1000-1500 J/KG... EFFECTIVE SHEAR VALUES OF 25-30 KT AND FREEZING LEVELS NEAR 14000 FT...WITH INSTABILITY DIMINISHING TO THE EAST. THEREFORE SOME HAIL IS NOT OUT OF THE QUESTION...BEST CHANCES IN THE WESTERN U.P WHERE HIGHER INSTABILITY IS PRESENT. HIGH TEMPERATURES ARE TRICKY...WITH CONCERN OF LOCATION OF MCS AND 850MB TEMPS OF 15-19C AT LEAST. WILL STAY ON THE CONSERVATIVE END OF GUIDANCE...WITH WARMEST READINGS IN THE SOUTH CENTRAL U.P.. && .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) TUE NIGHT...ALTHOUGH FEEDBACK PROBLEMS WITH THE GFS WERE NOT AS SEVERE AS PREVIOUS RUNS AND THE MDL WAS NOT AS MUCH OF AN OUTLIER COMPARED TO THE OTHER MODELS...THE SLOWER NAM SCENARIO...SUPPORTED BY THE UKMET/ECMWF AND CANADIAN REGIONAL GEM...WAS STILL PREFERRED. SO...WITH THE FRONT/TROUGH JUST MOVING INTO W UPPER MI AROUND 00Z...EXPECT CONTINUING POTENTIAL FOR SCT SHRA/TSRA ACROSS THE CNTRL AND EAST CWA BTWN 00Z-06Z SUPPORTED BY LOW LEVEL CONV AND QVECTOR CONV AHEAD OF THE LOW AND MID LEVEL TROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS WILL LINGER WITH MLCAPE VALUES AROUND 1000-1500 J/KG AND 0-6KM SHEAR VALUES INCREASING INTO THE 35-40 KT RANGE...ESPECIALLY NEAR THE WI BORDER WHERE THE INSTABILITY WILL BE GREATEST. WITH THE LOSS OF DIURNAL HEATING AND THE EXITING 950-850 MB CONV...EXPECT REMAINING SHRA/TSRA TO WEAKEN OR EXIT THE CWA BY 03Z-06Z. WED...LOW LEVEL DRY ADVECTION BEHIND THE TROUGH AND MID LEVEL SUBSIDENCE DRYING WITH THE DRY SLOT AND AREA OF QVECTOR DIV WILL HAMPER DEEP CONVECTION OVER MOST OF THE CWA. HOWEVER...ENOUGH LOW LEVEL MOISTURE WILL LINGER OVER THE ERN CWA SO THAT LOW LEVEL CONV ALONG LAKE IN PREVAILING WRLY MAY TRIGGER SCT OR ISOLD SHRA/TSRA. WED NIGHT INTO THU...MDLS WERE IN AGREEMENT WITH A DRY AIRMASS AND HIGH PRES SETTLING INTO THE AREA WITH NO PCPN EXPECTED. THU NIGHT...MDLS DIFFER WITH DEGREE OF RETURN WAA/MOISTURE. THE FCST LEANED MORE TOWARD THE LESS PROGRESSIVE ECMWF WHICH KEPT BEST LOW LEVEL THETA-E ADVECTION FARTHER TO THE WEST. FRI-MON...THE FCST...IN LINE WITH THE HPC PREFERRED 00Z GFS AND ENS 00Z GFS ENS MEAN...BRINGS IN POTENTIAL FOR SHRA/TSRA SAT INTO SUN WITH THE UPPER LAKES AFFECTED BY WAA AND SHORTWAVES ON THE PERIPHERY OF THE RIDGE. FOR NOW...NOT PCPN WAS MENTIONED FOR FRI...BUT SHRA/TSRA CHANCES MAY NEED TO BE ADDED...PER ECMWF...IF BETTER MDLS CONSENSUS EMERGES WITH DETAILS OF MOISTURE AND THE WAA PATTERN. MDLS WERE IN GENERAL AGREEMENT...THROUGH WITH TIMING DIFFERENCES...IN TRANSITION TOWARD MORE ZONAL PATTERN WITH A PROGRESSIVE TROUGH THROUGH SRN CANADA EVENTUALLY BRINGING A FRONT THROUGH THE AREA SAT NIGHT OR SUN WITH ADDITIONAL SHRA/TSRA CHANCES. TEMPS AOA SEASONAL AVERAGES ARE EXPECTED SAT AND POSSIBLY SUN BUT RETURN TO MORE NORMAL CONDITIONS BY MON. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS SHOULD REMAIN...WITH MAINLY JUST HIGH CLOUDS AND DRY WEATHER FOR BOTH PLACES. ONLY EXCEPTION WILL BE LATER IN THE DAY AT KCMX WITH SHOWERS MOVING THROUGH AND GIVING MVFR CIGS TO KCMX BY LATE IN THE AFTERNOON. KSAW WILL HAVE SHOWERS LATE...BUT CONDITIONS SHOULD REMAIN VFR THROUGH THE PERIOD. WILL GET GUSTIER AT KSAW IN THE AFTERNOON WITH WINDS MIXING DOWN TO THE SFC. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE HIGH DIRECTLY OVERHEAD KEEP WINDS LIGHT TONIGHT. THE LIGHT WINDS WILL BE SHORT LIVED AS A LOW PRESSURE TROUGH MOVES IN FROM THE HIGH PLAINS ON TUESDAY. WINDS WILL BECOMING SOUTHERLY AND STRENGTHEN THROUGH TUESDAY AFTERNOON. WINDS WILL BE STRONG ONCE AGAIN FROM THE WEST WEDNESDAY AFTERNOON...AS THE LOW SLOWLY MOVES EASTWARD TO THE NEW ENGLAND STATES BY THURSDAY MORNING. HIGH PRESSURE WILL THEN MOVE OVER LAKE SUPERIOR FOR ONCE AGAIN FOR THURSDAY AND FRIDAY...WITH WINDS GENERALLY LESS THAN 15 KTS. WIND WILL AGAIN INCREASE FOLLOWING ANOTHER COLD FRONT ON SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...GM MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1228 PM EDT MON JUL 28 2008 LATEST UPDATE...AVIATION .SYNOPSIS...(338 AM EDT MON JUL 28 2008) WEAK HIGH PRESSURE OVER THE GREAT LAKES WILL GRADUALLY DRIFT EAST TODAY ALLOWING A WARM FRONT TO DEVELOP AND MOVE NORTH INTO THE REGION TUESDAY. THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL INCREASE TUESDAY THROUGH EARLY WEDNESDAY AS THE WARM FRONT MOVES THROUGH AND THEN THE COLD FRONT. HIGH TEMPERATURES WILL BE MAINLY IN THE MID 80S FOR THE NEXT FEW DAYS. && .SHORT TERM...(338 AM EDT MON JUL 28 2008) (TODAY THROUGH WEDNESDAY) FORECAST CONCERNS TODAY DEAL WITH CONVECTIVE POTENTIAL TUESDAY THROUGH WEDNESDAY. A WEAK COLD FRONT WILL DRIFT SOUTH THROUGH THE CWA TODAY BEFORE HEADING BACK NORTH AS A WARM FRONT TUESDAY. CURRENTLY THERE IS REALLY NO WEATHER WITH THE FRONT AS SKIES ARE CLEAR. MODELS REALLY DON/T PAINT MUCH EITHER EXCEPT FOR THE 4KM WRF WHICH DEVELOPS A FEW SHOWERS ALONG IT LATER THIS AFTERNOON. RUC SOUNDINGS ARE PRETTY DRY THROUGHOUT THE PROFILE SO WE/RE GOING TO LEAVE THE GRIDS DRY TODAY. THE NWD MOVING WARM FRONT IS PROGD TO MOVE THROUGH THE CWA TUESDAY MORNING. INSTABILITY WILL INCREASE THROUGHOUT THE DAY WITH LI/S IN THE -4 TO -6C RANGE ON THE NAM. GFS IS MUCH MORE UNSTABLE LIKELY DUE TO THE VERY HIGH SFC DEWPOINTS IT CREATES. I HAVE A HARD TIME BELIEVING WE/LL SEE SFC DEWPOINTS NEAR 77F TUESDAY AFTERNOON. THE NAM/S DEWPOINTS AROUND 70 ARE MORE BELIEVABLE. LLJ SUPPORT IS WEST OF THE LAKE. IF STORMS FIRE ON THE WARM FRONT I SUSPECT MOST OF THEM WILL BE WEST OF THE CWA. WE/LL KEEP LOW CHC POPS IN TO COVER THE FRONT. A HIGHER CHANCE OF RAIN WILL COME WITH THE TRAILING COLD FRONT TUESDAY NIGHT INTO WEDNESDAY. LLJ INCREASES TO AROUND 30KTS TUESDAY NIGHT BUT THAT WILL BE WHEN INSTABILITY IS WEAKEST. SO WE/RE LIKELY TO SEE MORE STORMS...BUT PERHAPS A BIT WEAKER. NO REAL IMPRESSED WITH THE SVR THREAT AS 0-6KM BULK SHEAR REMAINS AOB 40 KTS THROUGH THE PERIOD. && .LONG TERM...(338 AM EDT MON JUL 28 2008) (WEDNESDAY NIGHT THROUGH SUNDAY) AS I DID YESTERDAY...SO I WILL DO EARLY THIS MORNING. THAT IS... I MADE NO SIGNIFICANT CHANGES TO THE MEDIUM RANGE PART OF THE GOING FORECAST. MODEL CONTINUITY ON BOTH THE GFS AND ECMWF BEYOND WEDNESDAY POOR AT BEST. GIVEN THE SIGNIFICANT UNCERTAINTIES IT WOULD SEEM UNREASONABLE TO MAKE SIGNIFICANT CHANGES TO OUR FORECAST AT THIS POINT. HAVING SAID THAT...THE LONGWAVE PATTERN SEEMS LOCKED IN PLACE WITH TROUGHS NEAR BOTH COASTS AND A FLAT RIDGE OVER WESTERN PLAINS. EVERY TIME A PACIFIC SHORTWAVE TOPS THE RIDGE THE PATTERN BECOMES FLATTER. WHEN THAT WAVE REACHES THE DOWNSTREAM TROUGH... THE PATTERN BECOMES MORE AMPLIFIED. THE GRR CWA IS ON THE DOWNSTREAM SIDE UPPER RIDGE... NEAR THE INFLECTION POINT IN THE FLOW. THAT IS KEEPING MOST OF THE PRECIPITATION NORTH AND SOUTH OF HERE. THAT IS DUE TO THE NORTHERN STREAM JET BEING TO OUR NORTH AND THE SUBTROPICAL JET STAYING TO OUR SOUTH. I SEE NO BIG CHANGES TO THIS PATTERN FOR SOME TIME TO COME. ANY SYSTEMS THAT DO COME THROUGH WILL FOR THE MOST PART BE WEAK IN TERMS OF LARGE SCALE PRECIPITATION POTENTIAL. TEMPERATURES WILL FOR THE MOST PART BE ON THE WARM SIDE OF NORMAL. I DO NOT BUY INTO THE STRONG COLD FRONT THE GFS BRINGS SOUTH ON THURSDAY ANY MORE THAN I BELIEVE THE 12Z ECMWF COLD FRONT FRIDAY INTO THE WEEKEND. BOTH FEATURES ARE LARGE CHANGES FROM THE PREVIOUS RUNS OR THE RUNS BEFORE THAT. THUS DUE TO LOW CONFIDENCE... I HAVE ALLOWED THE CURRENT VERSION OF OUR FORECAST FOR WEDNESDAY NIGHT THROUGH SATURDAY TO CONTINUE AS IS. && .MARINE...(1145 AM EDT MON JUL 28 2008) LIGHT WINDS WILL RESULT IN WAVES LESS THAN 2 FEET THROUGH TUESDAY. SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE TUESDAY INTO TUESDAY NIGHT. WINDS AND WAVES COULD BE HIGHER NEAR ANY OF THE THUNDERSTORMS. SMALL CRAFT ADVISORIES MAY BE NEEDED TUESDAY NIGHT OR WEDNESDAY. && .AVIATION...(1228 PM EDT MON JUL 28 2008) CUMULUS CLOUDS WITH BASES 3500 TO 4000 FT AGL ARE FORMING ATTM ALONG WEAK SURFACE CONVERGENCE ASSOCIATED WITH STALLED FRONT FROM MKG TO LAN. EXPECT SOME WIDELY SCATTERED SHOWERS OR AN ISOLATED THUNDERSTORM THIS AFTERNOON...BUT CHANCES ARE LOW ENOUGH NOT TO BE INCLUDED IN THE FORECAST. CLOUDS SHOULD DIMINISH BY SUNSET WITH SOME LOWER VISIBILITIES OVERNIGHT IN LIGHT FOG...SIMILAR TO LAST NIGHT EXCEPT A LITTLE MORE MOISTURE SHOULD MEAN A LITTLE LOWER THAN LAST NIGHT. CHANCE OF THUNDER BY 18Z TOMORROW...BUT TIMING AND COVERAGE UNCERTAIN. && .HYDROLOGY...(338 AM EDT MON JUL 28 2008) FEW HYDRO CONCERNS TODAY DUE TO THE DRY WX REGIME. SHOWERS AND THUNDERSTORMS ARE POSSIBLE TUESDAY AND WEDNESDAY. LOCALLY HEAVY RAINFALL IS POSSIBLE WITH PWATS AROUND 2 INCHES. WIDESPREAD FLOODING IS NOT ANTICIPATED THOUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: 93 SHORT TERM: 93 LONG TERM: WDM MARINE: MJS AVIATION: OSTUNO HYDROLOGY: 93 mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 126 PM EDT MON JUL 28 2008 .SHORT TERM...TODAY. MAIN FORECAST CONCERN IS THUNDERSTORM DEVELOPMENT FOR TONIGHT/TUE. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER WEST CENTRAL QUEBEC...A RIDGE OVER ONTARIO...AND ANOTHER LOW OVER NORTHERN SASKATCHEWAN. WEAK SHORTWAVES MOVING THROUGH THE BASE OF THE SASKATCHEWAN LOW ARE APPROACHING THE RIDGE. SURFACE ANALYSIS DEPICTS A LARGE RIDGE OVER THE ONTARIO AND THE UPPER GREAT LAKES. A LOW IS OVER THE MIDDLE AND HIGH PLAINS...WITH A WARM FRONT EXTENDING OUT AHEAD OF THE LOW INTO THE UPPER MISSISSIPPI RIVER VALLEY. UPPER LEVEL RIDGE OVER CENTRAL CANADA WILL SLIDE INTO WESTERN ONTARIO THIS AFTERNOON AS THE TROUGH OVER SASKATCHEWAN DEEPENS. HIGH PRESSURE SHOULD STILL REMAIN AT THE SURFACE DUE TO THE AREA BASICALLY REMAINING TO THE EAST OF THE RIDGE AXIS...AND THE COOL WATER EFFECT FROM LAKES SUPERIOR AND MICHIGAN. THEREFORE...A LAKE BREEZE DAY IS LIKELY SO LAKESHORE LOCATIONS SHOULD SEE SOME COOLING THIS AFTERNOON. AIRMASS REMAINS DRY UNDER THIS RIDGE...WITH PRECIPITABLE WATER VALUES PROGGED TO STAY BETWEEN 0.50 INCH AND 1 INCH. WITH MID LEVEL SUBSIDENCE IN PLACE AND THE DRY AIR...NO PRECIPITATION IS EXPECTED. SOME MID/HIGH CLOUDS ARE LIKELY TO SPREAD ACROSS THE CWA AS EVIDENCED UP TO THE NW...ALONG WITH SOME SMOKE UP IN THE UPPER LEVELS. SOME AFTERNOON CUMULUS AROUND 5K FEET WILL LIKELY FORM... ESPECIALLY IN THE WESTERN U.P. WHERE RETURN FLOW HELPS RAISE DEWPOINTS INTO THE MID/UPPER 50S. THE COMBINATION OF THE CLOUDS/SMOKE SHOULD PREVENT MIXING SOME...BUT READINGS ARE STILL PLANNED TO REACH INTO THE 70S TO LOW 80S WITH WITH 850MB TEMPS OF 12-15C. WARMEST READINGS EXPECTED ALONG THE WI BORDER. NO CHANGES TO THE CURRENT FORECAST NEEDED AT THIS TIME. .LONG TERM... TONIGHT...UPPER RIDGE OVER THE WRN PORTION OF THE CWA AT 00Z WILL CONTINUE TO SLIDE EASTWARD THROUGH THE NIGHT...WHILE THE POTENT LOOKING SHRTWV OVER SW ALBERTA MOVES TO SE MANITOBA BY 12Z TUE. THE MOVEMENT OF THESE MID LEVEL FEATURES MEANS THAT THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES REGION WILL BE UNDER WARM ADVECTION. GIVEN THE APPROACH OF THE SHRTWV...MOST MODELS SHOW A FAIRLY STRONG SURFACE LOW (AROUND 1000MB) OVER CENTRAL MANITOBA BY 12Z...MEANING THAT THE WARM ADVECTION WILL LIKELY BE ACCOMPANIED BY A FAIRLY STRONG LOW LEVEL JET. NAM PROGGED 850MB WINDS ARE AROUND 30 KT OUT OF THE SW ACROSS MUCH OF MN AFTER 06Z...WHICH THEN VEER TO POINT TOWARDS UPPER MI. 850MB THETA-E ADVECTION VALUES INCREASE ACROSS NRN MN INTO THE CWA...ESPECIALLY IN THE WESTERN U.P....SUGGESTING PRETTY GOOD MOISTURE RETURN WITH THE LOW LEVEL JET. HOWEVER...ANOTHER ZONE OF STRONG ADVECTION VALUES EXIST IN SRN MN AND NRN IA. EACH ZONE ARE LIKELY AREAS FOR TSTM INITIATION...AND THEREFORE CHANCE POPS ARE IN THE FORECAST FOR THE WESTERN CWA...MAINLY AFTER 06Z. SOME CONCERN EXISTS FOR HAIL GIVEN MUCAPES AROUND 1000 J/KG AND EFFECTIVE SHEAR VALUES OF 25-30 KT. HOWEVER...FREEZING LVL HEIGHTS ARE A BIT HIGH...AROUND 14000 FT. SPC DAY 1 OUTLOOK OF 5 PCT SEEMS REASONABLE. THE EASTERN CWA LOOKS TO BE TOO CAPPED TO ALLOW FOR PCPN. GIVEN INCREASING CLOUD COVER FROM THE WARM ADVECTION...INCREASING SOUTHERLY WINDS AND HIGHER DEWPOINTS MOVING IN...LOW TEMPS SHOULD GENERALLY BE IN THE 50S TO LOW 60S. COOLEST READINGS EXPECTED IN THE EAST WHERE MOSTLY CLEAR SKIES AND LIGHT WINDS IN THE EVENING ALLOW FOR GREATER RADIATIONAL COOLING. TUESDAY...UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA SHIFTS INTO NRN ONTARIO DURING THE DAY...ALLOWING A SURFACE COLD FRONT TO APPROACH THE WRN LAKE SUPERIOR AND IWD BY 00Z. CONVECTIVE FEEDBACK IN THE MODELS FROM CONVECTION TONIGHT OVER NRN MN RESULTS IN SOME ISSUES WITH THE FORECAST...HOWEVER...THERE IS A GENERAL CONSENSUS FROM THE 00Z/18Z GFS...THE 00Z ECMWF...UKMET...REGIONAL CANADIAN AND NAM FOR WHATEVER MCS THAT DEVELOPS OVER NRN MN/WRN LAKE SUPERIOR TO SLIDE AND WEAKEN AS IT CROSSES THE CWA THROUGH THE DAY. THEREFORE PCPN CHANCES REMAIN IN THE FORECAST...BUT MUCH OF THE CONVECTION IS ASSUMED TO BE ELEVATED AND NOT SURFACE BASED. ALL SURFACE BASED CONVECTION SHOULD OCCUR TO THE SOUTH OF THE CWA DUE TO OUTFLOW BOUNDARIES FROM THIS MCS. IF OUR LOCAL WRF-ARW RUN IS CORRECT AND KEEPING MUCH OF THE MCS ACTIVITY ACROSS LAKE SUPERIOR AND THE NRN U.P....THEN THERE WOULD BE AN OPPORTUNITY FOR THE SOUTHERN U.P. TO HEAT UP AND THUS RESULT IN SOME SURFACE BASED CONVECTION. FUTURE FCST SHIFTS WILL NEED TO MONITOR. REGARDING SEVERE CHANCES...SIMILAR CONDITIONS EXIST TO TONIGHT WITH MUCAPES BETWEEN 1000-1500 J/KG... EFFECTIVE SHEAR VALUES OF 25-30 KT AND FREEZING LEVELS NEAR 14000 FT...WITH INSTABILITY DIMINISHING TO THE EAST. THEREFORE SOME HAIL IS NOT OUT OF THE QUESTION...BEST CHANCES IN THE WESTERN U.P WHERE HIGHER INSTABILITY IS PRESENT. HIGH TEMPERATURES ARE TRICKY...WITH CONCERN OF LOCATION OF MCS AND 850MB TEMPS OF 15-19C AT LEAST. WILL STAY ON THE CONSERVATIVE END OF GUIDANCE...WITH WARMEST READINGS IN THE SOUTH CENTRAL U.P.. TUE NIGHT AND WED...UPPER TROUGH IS PROGGED TO CONTINUE MARCHING ACROSS NRN ONTARIO DURING THIS PERIOD...WITH MODELS ACTUALLY SUGGESTING THE UPPER LEVEL PATTERN BY 00Z THU LOOKING VERY SIMILAR TO WHAT IS OCCURRING NOW...THOUGH WITH SLIGHTLY LESS AMPLIFICATION. HAVE DISCOUNTED THE GFS WITH THE HANDLING OF THE UPPER TROUGH... PRIMARILY DUE TO ITS CONVECTIVE FEEDBACK PROBLEMS IT HAS BACK WITH TONIGHTS ACTIVITY...WHICH MERGES WITH THE UPPER TROUGH. FOLLOWED CLOSER TO THE NAM/UKMET/ECMWF. ANY LINGERING CONVECTION FROM TUE... BE IT ELEVATED OR POSSIBLY SURFACE BASED...SHOULD EXIT MUCH IF NOT ALL OF THE CWA TUE EVENING. MOSTLY DRY CONDITIONS WITH DECREASING CLOUDS ARE EXPECTED FOR AFTER MIDNIGHT TUE NIGHT INTO WED...WHICH SHOULD ALLOW FOR SLIGHTLY COOLER TEMPS TUE NIGHT COMPARED TO MON NIGHT. FOR WED AFTERNOON...A SURFACE TROUGH ASSOCIATED WITH THE UPPER LEVEL TROUGH IS INDICATED TO DROP DOWN INTO THE CWA. LAKE BREEZE CONVERGENCE INTO THIS TROUGH...COMBINED WITH LINGERING LOW LEVEL MOISTURE (DEWPOINTS PROGGED AROUND 60) SHOULD RESULT IN SOME SCATTERED SHOWERS AND THUNDERSTORMS OVER THE EAST HALF OF THE CWA AWAY FROM LAKE SUPERIOR. GOING HIGH TEMPS LOOK REASONABLE...WITH COOLEST READINGS NEAR LAKE SUPERIOR WITH EXPECTED ONSHORE FLOW. WED NIGHT AND THU...UPPER LEVEL TROUGH SHIFTS OFF TO THE EAST...ALLOWING HIGH PRESSURE TO BUILD DOWN FROM CANADA AT THE SURFACE. THIS WILL ALLOW DRIER AIR TO FILTER SOUTH...THOUGH THERE STILL MAY BE SOME LOW TO MID LEVEL STRATUS FOR WED NIGHT. LOWERED LOW TEMPS SOME FOR WED NIGHT GIVEN MEX GUIDANCE READINGS IN THE UPPER 40S FOR THE WESTERN U.P.. HOWEVER...IF THERE IS LESS CLOUD COVER THAN FORECAST...COULD SEE A NEED TO LOWER LOW TEMPS MORE FOR WED NIGHT SINCE A DRY AIRMASS IS MOVING IN. THIS HIGH PRESSURE RIDGE MOVES OVER THE CWA ON THU...SO EXPECT ANOTHER LAKE BREEZE DAY WITH CONDITIONS VERY SIMILAR TO TODAY...BOTH CLOUD COVER AND TEMPERATURE WISE. ONLY PCPN FORECAST FOR THE PERIOD IS IN THE SE CWA EARLY WED EVENING WITH ANY LINGERING CONVECTION. NO CHANGES MADE BEYOND THU. HOWEVER...CHANCE POPS MAY BE NEEDED FOR THU NIGHT AND FRI...MAINLY IN THE SOUTHERN U.P....WITH THE 00Z ECMWF/GFS SUGGESTING WARM ADVECTION PCPN ACROSS THE SOUTHERN U.P. AND NRN WI. WILL LET DAY SHIFT LOOK AT THIS CLOSER. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CONDITIONS SHOULD REMAIN...WITH MAINLY JUST HIGH CLOUDS AND DRY WEATHER. TAMDAR SHOWING A DECK OF CUMULUS SHOULD DEVELOP AROUND 3K FEET AT KSAW AND FORECAST SOUNDINGS SHOWING A CUMULUS LAYER DEVELOPING AT KCMX AROUND 5K FEET. DUE TO WNW FLOW ALOFT BRINGING IN AN ELEVATED SMOKE LAYER FROM WILDFIRES IN NRN CALIFORNIA AND NORTH CENTRAL CANADA...HAZY HIGH CLOUDINESS WILL REMAIN. BUFKIT SUGGEST SHOWING A CHANCE OF SHOWERS AND THUNDERSTORMS WILL SHIFT ACROSS THE WEST HALF OF FORECAST AREA TUESDAY MORNING SO WILL PUT IN A CHANCE OF SHOWERS OVER KCMX TUESDAY MORNING. FORECAST SOUNDING A LITTLE LATER FOR KSAW SO WILL HOLD OFF A TIL AFTER 18Z TUESDAY THERE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SFC HIGH DIRECTLY OVERHEAD SHOULD RESULT IN LIGHT WINDS. THE LIGHT WINDS WILL BE SHORT LIVED AS A LOW PRESSURE TROUGH MOVES IN FROM THE HIGH PLAINS ON TUESDAY. WINDS WILL BECOME SOUTHERLY OVERNIGHT INTO TUESDAY MORNING AND STRENGTHEN THROUGH THE AFTERNOON HOURS. WINDS WILL BE STRONG ONCE AGAIN FROM THE WEST WEDNESDAY AFTERNOON...AS THE LOW SLOWLY MOVES EASTWARD TO THE NEW ENGLAND STATES BY THURSDAY MORNING. HIGH PRESSURE WILL THEN MOVE OVER LAKE SUPERIOR FOR ONCE AGAIN FOR THURSDAY AND FRIDAY...WITH WINDS GENERALLY LESS THAN 15 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...DLG LONG TERM...AJ AVIATION...DLG MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 111 PM EDT MON JUL 28 2008 .AVIATION... AFTERNOON VISIBLE SATELLITE IMAGERY IS SHOWING AN ENHANCED CU FIELD...BASED BETWEEN 4 AND 5K FT AGL...EXTENDING ALONG A SURFACE TROUGH FROM NEAR MTC TO MKG. CONVERGENCE ALONG THIS BOUNDARY ALONG WITH ADDITIONAL CONVERGENCE OFF THE ST CLAIR LAKE BREEZE MAY TOUCH OFF SOME ISOLATED THUNDERSTORMS LATE THIS AFTERNOON. CHANCES OF THIS CONVECTION IMPACTING THE DETROIT TAFS REMAINS FAR TO LOW TO INCLUDE IN THE FORECAST AT THIS POINT. OTHERWISE...VFR CONDITIONS WILL PREVAIL THROUGH THE EVENING. THE SURFACE BOUNDARY IS EXPECTED TO LINGER OVER SOUTHERN MI THROUGH THE NIGHT. MOISTURE POOLING ALONG THIS BOUNDARY WILL WARRANT SOME MVFR VISIBILITIES IN FOG/HAZE LATE TONIGHT INTO EARLY TUES MORNING. && .PREV DISCUSSION...ISSUED 1132 AM EDT MON JUL 28 2008 UPDATE... A WEAK MID LEVEL RIDGE ACROSS NORTHERN INDIANA HAS BEEN PROVIDING ENOUGH SUBSIDENCE TO PRODUCE SUNNY SKIES ACROSS THE FORECAST AREA THIS MORNING. AS A RESULT...HAVE ISSUED AN UPDATE TO DIMINISH CLOUD COVER SLIGHTLY IN THE GRIDS AND RAISE MAX TEMPS BY A DEGREE OR TWO. THE 15Z SURFACE ANALYSIS SHOWS AN ILL DEFINED TROUGH EXTENDING FROM ROUGHLY LAKE ST CLAIR THROUGH THE GRAND RAPIDS AREA. DO NOT FORESEE THIS BOUNDARY SINKING TOO FAR SOUTH THIS AFTERNOON WITH STRONG AFTERNOON INSULATION. THE 12Z NAM AND RUC DO PRODUCE A LITTLE LATE AFTERNOON QPF IN THE VICINITY OF THIS BOUNDARY AND THE LAKE ST CLAIR LAKE BREEZE. STILL ONLY EXPECTING MODEST AFTERNOON INSTABILITY...SB CAPE NEAR 1500 J/KG. THIS ALONG WITH OVERALL LACK OF LARGE SCALE FORCING SUGGEST ANY COVERAGE OF LATE AFTERNOON CONVECTION WILL REMAIN ISOLATED. HOWEVER...GIVEN THE LATEST GUIDANCE...HAVE EXPANDED THE AREAL COVERAGE OF ISOLATED CONVECTION TO ENCOMPASS THE M 59 CORRIDOR AND LAKE ST CLAIR VICINITY. PREV DISCUSSION...ISSUED 421 AM EDT MON JUL 28 2008 SHORT TERM...TODAY A TYPICAL LATE JULY DAY IS IN STORE FOR SE MICHIGAN TODAY IN TERMS OF TEMPERATURE AND RAIN CHANCES. THE PRESENCE OF A WEAK SURFACE TROUGH WILL MAKE AN ISOLATED THUNDERSTORM POSSIBLE LATE THIS AFTERNOON IN THE DETROIT AREA DOWN TO THE OHIO BORDER BUT IT WILL BE DRY ELSEWHERE. HIGHS WILL RANGE FROM THE UPPER 70S NEAR THE LAKE HURON SHORELINE TO THE MID 80S NEAR THE OHIO BORDER. DECIDED TO INCLUDE AN ISOLATED THUNDERSTORM POSSIBILITY IN THE FORECAST FOR THE SOUTH FOUR COUNTIES LATE THIS AFTERNOON BASED ON REASONABLE NAM12 AND 4KM WRF MODEL OUTPUT, IN ADDITION TO SOME HINTS OF QPF FROM THE GFS. EXPECT SURFACE DEWPOINT IN THE LOWER HALF OF THE 60S TO POOL AHEAD OF THE TROUGH DURING THE DAY DUE TO LIGHT SW WINDS. THE MOST LIKELY SURFACE PARCEL OF 85/63 THEN YIELDS CAPE AROUND 1500 J/KG WITH JUST ENOUGH SURFACE CONVERGENCE TO TOUCH OFF A STORM DURING PEAK HEATING. SEVERE WEATHER PARAMETERS ARE NOT FAVORABLE WITH HIGH FREEZING LEVEL AND SLOW STORM MOTION JUST LEADING TO BRIEF HEAVY DOWNPOURS AND PERHAPS A DOWNBURST WIND GUST IN THE NEIGHBORHOOD OF 30 MPH. FARTHER NORTH, THE MAIN STORY WILL BE COOLER FLOW OFF OF LAKE HURON INTO THE THUMB AS NORTHERLY FLOW BEHIND THE TROUGH COMBINES WITH A LAKE BREEZE COMPONENT. CONDITIONS WILL NOT BE AS COOL FARTHER INLAND TOWARD THE TRI CITIES BUT SURFACE DEWPOINT IN THE 50S WILL KEEP CONDITIONS LESS HUMID HEADING INTO THIS EVENING. LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY. BEHIND THE WEAK FRONT TODAY...HIGH PRESSURE WILL BUILD TOWARDS THE EASTERN GREAT LAKES TONIGHT ALLOWING LIGHT WINDS TO VEER AROUND TO THE SOUTHEAST. THIS WILL SET THE STAGE FOR TUESDAY WITH A WEAK CONVERGENT BOUNDARY IN PLACE OVER SOUTHEAST MICHIGAN...SLOWLY LIFTING BACK NORTH AS A WARM FRONT IN ADVANCE OF A BROAD AREA OF LOW PRESSURE TAKING SHAPE ACROSS WESTERN ONTARIO AND THE UPPER MIDWEST. THE ASSOCIATED UPPER LEVEL LOW IS EXPECTED TO GRADUALLY DEEPEN AS IT TRACKS ACROSS ONTARIO THROUGH WEDNESDAY BRINGING A CHANCE OF THUNDERSTORMS TO THE REGION. THE GFS CONTINUES TO STRUGGLE WITH HANDLING OF THIS SYSTEM AND IS ALONE IN SHOWING THE SURFACE LOW DEVELOPING SOUTH OF LAKE SUPERIOR ON TUESDAY. INSTEAD WILL LEAN THE FORECAST IN THE DIRECTION OF A NAM/ECMWF BLEND. BOTH OF THESE MODELS INDICATE A MCS WILL DEVELOP OVER SOUTHERN MINNESOTA/NE IOWA MONDAY NIGHT WITH SOME QUESTION AS TO WHERE THE REMNANTS OF THIS FEATURE WILL TRACK ON TUESDAY. THE ECMWF TRACKS THE DISSIPATING MCS SOUTHWEST OF THE AREA WHILE THE NAM SHOWS AN MCV DEVELOPING AND HELPING TO TRIGGER CONVECTION FOR SOUTHEAST MICHIGAN LATE TUESDAY AFTERNOON. SOUTHERLY WINDS SOUTH OF THE WARM FRONT WILL WORK TO ADVECT A MOIST LOW LEVEL AIRMASS INTO SOUTHERN LOWER MICHIGAN WITH DEWPOINTS REACHING THE MID TO UPPER 60S ACROSS THE SOUTH. THIS SHOULD YIELD MODERATE INSTABILITY OVER THE AREA WITH MODELS SOUNDINGS SHOWING OVER 2500 J/KG OF SURFACE BASED CAPE. QUITE A BIT OF UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE UPSTREAM MCS WHICH WILL AFFECT BOTH THE DEGREE OF CLOUD COVER AND THE POTENTIAL FORCING MECHANISM FOR CONVECTION. MID LEVELS WILL BE RATHER WARM...BUT GIVEN THE INSTABILITY AND WEAK BOUNDARY IN PLACE...WILL NEED TO MONITOR STORMS WITH A SLIGHT CHANCE OF SEVERE WEATHER. THE CHANCE OF THUNDERSTORMS CONTINUES THROUGH WEDNESDAY AS THE ASSOCIATED SURFACE TROUGH MOVES ACROSS THE AREA. A WEAK COLD FRONT WILL DROP SOUTH INTO OUR NORTHERN COUNTIES WEDNESDAY NIGHT BRINGING A COMFORTABLE DAY FOR THURSDAY WITH NEAR NORMAL TEMPERATURES AND LOWER HUMIDITY. RIDGING WILL BUILD OVERHEAD TOWARDS THE END OF THE WEEK WITH THE NEXT CHANCE OF THUNDERSTORMS COMING AS SHORTWAVE ENERGY WORKS TO FLATTEN THE RIDGE AND TRANSITION TO A NEAR ZONAL FLOW ACROSS THE NORTHERN TIER OF STATES. MODELS ARE NOT IN GOOD AGREEMENT ON ANY ONE PARTICULAR PERIOD TO ADD A CHANCE OF SHOWERS/THUNDERSTORMS ALTHOUGH A LOW CHANCE MAY EVENTUALLY NEED TO BE ADDED IN THE FRIDAY THROUGH SUNDAY PERIOD. MARINE... MARINE WEATHER CONCERNS ARE MINIMAL OUTSIDE OF AN ISOLATED THUNDERSTORM POSSIBILITY OVER LAKE ST CLAIR AND WESTERN LAKE ERIE. A WEAK SURFACE TROUGH OF LOW PRESSURE WILL SETTLE FROM CENTRAL LAKE HURON INTO WESTERN LAKE ERIE BY TONIGHT. LIGHT NORTH WINDS WILL QUICKLY BECOME VARIABLE TONIGHT AS HIGH PRESSURE SETTLES INTO THE REGION. THIS WILL GIVE WAY TO INCREASING SOUTHERLY WINDS ON TUESDAY AS THE NEXT LOW PRESSURE SYSTEM TAKES SHAPE IN THE UPPER MIDWEST. SIGNIFICANT THUNDERSTORM POTENTIAL TUESDAY NIGHT INTO WEDNESDAY WILL BE THE MAIN WEATHER CONCERN DURING THAT TIME PERIOD. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...BT LONG TERM....KEC MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1145 AM EDT MON JUL 28 2008 LATEST UPDATE...MARINE .SYNOPSIS...(338 AM EDT MON JUL 28 2008) WEAK HIGH PRESSURE OVER THE GREAT LAKES WILL GRADUALLY DRIFT EAST TODAY ALLOWING A WARM FRONT TO DEVELOP AND MOVE NORTH INTO THE REGION TUESDAY. THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL INCREASE TUESDAY THROUGH EARLY WEDNESDAY AS THE WARM FRONT MOVES THROUGH AND THEN THE COLD FRONT. HIGH TEMPERATURES WILL BE MAINLY IN THE MID 80S FOR THE NEXT FEW DAYS. && .SHORT TERM...(338 AM EDT MON JUL 28 2008) (TODAY THROUGH WEDNESDAY) FORECAST CONCERNS TODAY DEAL WITH CONVECTIVE POTENTIAL TUESDAY THROUGH WEDNESDAY. A WEAK COLD FRONT WILL DRIFT SOUTH THROUGH THE CWA TODAY BEFORE HEADING BACK NORTH AS A WARM FRONT TUESDAY. CURRENTLY THERE IS REALLY NO WEATHER WITH THE FRONT AS SKIES ARE CLEAR. MODELS REALLY DON/T PAINT MUCH EITHER EXCEPT FOR THE 4KM WRF WHICH DEVELOPS A FEW SHOWERS ALONG IT LATER THIS AFTERNOON. RUC SOUNDINGS ARE PRETTY DRY THROUGHOUT THE PROFILE SO WE/RE GOING TO LEAVE THE GRIDS DRY TODAY. THE NWD MOVING WARM FRONT IS PROGD TO MOVE THROUGH THE CWA TUESDAY MORNING. INSTABILITY WILL INCREASE THROUGHOUT THE DAY WITH LI/S IN THE -4 TO -6C RANGE ON THE NAM. GFS IS MUCH MORE UNSTABLE LIKELY DUE TO THE VERY HIGH SFC DEWPOINTS IT CREATES. I HAVE A HARD TIME BELIEVING WE/LL SEE SFC DEWPOINTS NEAR 77F TUESDAY AFTERNOON. THE NAM/S DEWPOINTS AROUND 70 ARE MORE BELIEVABLE. LLJ SUPPORT IS WEST OF THE LAKE. IF STORMS FIRE ON THE WARM FRONT I SUSPECT MOST OF THEM WILL BE WEST OF THE CWA. WE/LL KEEP LOW CHC POPS IN TO COVER THE FRONT. A HIGHER CHANCE OF RAIN WILL COME WITH THE TRAILING COLD FRONT TUESDAY NIGHT INTO WEDNESDAY. LLJ INCREASES TO AROUND 30KTS TUESDAY NIGHT BUT THAT WILL BE WHEN INSTABILITY IS WEAKEST. SO WE/RE LIKELY TO SEE MORE STORMS...BUT PERHAPS A BIT WEAKER. NO REAL IMPRESSED WITH THE SVR THREAT AS 0-6KM BULK SHEAR REMAINS AOB 40 KTS THROUGH THE PERIOD. && .LONG TERM...(338 AM EDT MON JUL 28 2008) (WEDNESDAY NIGHT THROUGH SUNDAY) AS I DID YESTERDAY...SO I WILL DO EARLY THIS MORNING. THAT IS... I MADE NO SIGNIFICANT CHANGES TO THE MEDIUM RANGE PART OF THE GOING FORECAST. MODEL CONTINUITY ON BOTH THE GFS AND ECMWF BEYOND WEDNESDAY POOR AT BEST. GIVEN THE SIGNIFICANT UNCERTAINTIES IT WOULD SEEM UNREASONABLE TO MAKE SIGNIFICANT CHANGES TO OUR FORECAST AT THIS POINT. HAVING SAID THAT...THE LONGWAVE PATTERN SEEMS LOCKED IN PLACE WITH TROUGHS NEAR BOTH COASTS AND A FLAT RIDGE OVER WESTERN PLAINS. EVERY TIME A PACIFIC SHORTWAVE TOPS THE RIDGE THE PATTERN BECOMES FLATTER. WHEN THAT WAVE REACHES THE DOWNSTREAM TROUGH... THE PATTERN BECOMES MORE AMPLIFIED. THE GRR CWA IS ON THE DOWNSTREAM SIDE UPPER RIDGE... NEAR THE INFLECTION POINT IN THE FLOW. THAT IS KEEPING MOST OF THE PRECIPITATION NORTH AND SOUTH OF HERE. THAT IS DUE TO THE NORTHERN STREAM JET BEING TO OUR NORTH AND THE SUBTROPICAL JET STAYING TO OUR SOUTH. I SEE NO BIG CHANGES TO THIS PATTERN FOR SOME TIME TO COME. ANY SYSTEMS THAT DO COME THROUGH WILL FOR THE MOST PART BE WEAK IN TERMS OF LARGE SCALE PRECIPITATION POTENTIAL. TEMPERATURES WILL FOR THE MOST PART BE ON THE WARM SIDE OF NORMAL. I DO NOT BUY INTO THE STRONG COLD FRONT THE GFS BRINGS SOUTH ON THURSDAY ANY MORE THAN I BELIEVE THE 12Z ECMWF COLD FRONT FRIDAY INTO THE WEEKEND. BOTH FEATURES ARE LARGE CHANGES FROM THE PREVIOUS RUNS OR THE RUNS BEFORE THAT. THUS DUE TO LOW CONFIDENCE... I HAVE ALLOWED THE CURRENT VERSION OF OUR FORECAST FOR WEDNESDAY NIGHT THROUGH SATURDAY TO CONTINUE AS IS. && .MARINE...(1145 AM EDT MON JUL 28 2008) LIGHT WINDS WILL RESULT IN WAVES LESS THAN 2 FEET THROUGH TUESDAY. SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE TUESDAY INTO TUESDAY NIGHT. WINDS AND WAVES COULD BE HIGHER NEAR ANY OF THE THUNDERSTORMS. SMALL CRAFT ADVISORIES MAY BE NEEDED TUESDAY NIGHT OR WEDNESDAY. && .AVIATION...(707 AM EDT MON JUL 28 2008) FOG WILL BURN OFF BY 10 AM ACROSS THE AREA. A WEAK FRONTAL BOUNDARY WILL STALL NEAR I-94 THIS AFTERNOON AND ACT AS AN AREA OF SURFACE CONVERGENCE. THIS AREA OF SURFACE CONVERGENCE WILL ACT AS A CATALYST FOR ISOLATED THUNDERSTORMS THIS AFTERNOON BUT THOSE STORMS WILL ONLY EFFECT THE I-94 TAF SITES. ONCE THE SUN SETS SKIES WILL CLEAR BUT LIKE THIS MORNING... LIGHT WINDS AN INCREASING SURFACE DEW POINTS WILL BRING SOME FOG BACK TO THE AREA AFTER MIDNIGHT. && .HYDROLOGY...(338 AM EDT MON JUL 28 2008) FEW HYDRO CONCERNS TODAY DUE TO THE DRY WX REGIME. SHOWERS AND THUNDERSTORMS ARE POSSIBLE TUESDAY AND WEDNESDAY. LOCALLY HEAVY RAINFALL IS POSSIBLE WITH PWATS AROUND 2 INCHES. WIDESPREAD FLOODING IS NOT ANTICIPATED THOUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: 93 SHORT TERM: 93 LONG TERM: WDM MARINE: MJS AVIATION: WDM HYDROLOGY: 93 mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1132 AM EDT MON JUL 28 2008 .UPDATE... A WEAK MID LEVEL RIDGE ACROSS NORTHERN INDIANA HAS BEEN PROVIDING ENOUGH SUBSIDENCE TO PRODUCE SUNNY SKIES ACROSS THE FORECAST AREA THIS MORNING. AS A RESULT...HAVE ISSUED AN UPDATE TO DIMINISH CLOUD COVER SLIGHTLY IN THE GRIDS AND RAISE MAX TEMPS BY A DEGREE OR TWO. THE 15Z SURFACE ANALYSIS SHOWS AN ILL DEFINED TROUGH EXTENDING FROM ROUGHLY LAKE ST CLAIR THROUGH THE GRAND RAPIDS AREA. DO NOT FORESEE THIS BOUNDARY SINKING TOO FAR SOUTH THIS AFTERNOON WITH STRONG AFTERNOON INSULATION. THE 12Z NAM AND RUC DO PRODUCE A LITTLE LATE AFTERNOON QPF IN THE VICINITY OF THIS BOUNDARY AND THE LAKE ST CLAIR LAKE BREEZE. STILL ONLY EXPECTING MODEST AFTERNOON INSTABILITY...SB CAPE NEAR 1500 J/KG. THIS ALONG WITH OVERALL LACK OF LARGE SCALE FORCING SUGGEST ANY COVERAGE OF LATE AFTERNOON CONVECTION WILL REMAIN ISOLATED. HOWEVER...GIVEN THE LATEST GUIDANCE...HAVE EXPANDED THE AREAL COVERAGE OF ISOLATED CONVECTION TO ENCOMPASS THE M 59 CORRIDOR AND LAKE ST CLAIR VICINITY. && .PREV DISCUSSION...ISSUED 703 AM EDT MON JUL 28 2008 AVIATION... A WEAK SURFACE TROUGH WILL SETTLE FROM CENTRAL LOWER MICHIGAN TO THE OHIO BORDER BY TONIGHT. ABOUT THE ONLY AVIATION CONCERN WITH THIS FEATURE WILL BE THE POSSIBILITY OF AN ISOLATED THUNDERSTORM NEAR DETROIT LATE THIS AFTERNOON. OTHERWISE, LIGHT SOUTHWEST WINDS WILL GRADUALLY TURN THROUGH THE NORTH TODAY AND TOWARD THE EAST LATER TONIGHT AS THE TROUGH WASHES OUT IN FAVOR OF WEAK HIGH PRESSURE. PREV DISCUSSION...ISSUED 421 AM EDT MON JUL 28 2008 SHORT TERM...TODAY A TYPICAL LATE JULY DAY IS IN STORE FOR SE MICHIGAN TODAY IN TERMS OF TEMPERATURE AND RAIN CHANCES. THE PRESENCE OF A WEAK SURFACE TROUGH WILL MAKE AN ISOLATED THUNDERSTORM POSSIBLE LATE THIS AFTERNOON IN THE DETROIT AREA DOWN TO THE OHIO BORDER BUT IT WILL BE DRY ELSEWHERE. HIGHS WILL RANGE FROM THE UPPER 70S NEAR THE LAKE HURON SHORELINE TO THE MID 80S NEAR THE OHIO BORDER. DECIDED TO INCLUDE AN ISOLATED THUNDERSTORM POSSIBILITY IN THE FORECAST FOR THE SOUTH FOUR COUNTIES LATE THIS AFTERNOON BASED ON REASONABLE NAM12 AND 4KM WRF MODEL OUTPUT, IN ADDITION TO SOME HINTS OF QPF FROM THE GFS. EXPECT SURFACE DEWPOINT IN THE LOWER HALF OF THE 60S TO POOL AHEAD OF THE TROUGH DURING THE DAY DUE TO LIGHT SW WINDS. THE MOST LIKELY SURFACE PARCEL OF 85/63 THEN YIELDS CAPE AROUND 1500 J/KG WITH JUST ENOUGH SURFACE CONVERGENCE TO TOUCH OFF A STORM DURING PEAK HEATING. SEVERE WEATHER PARAMETERS ARE NOT FAVORABLE WITH HIGH FREEZING LEVEL AND SLOW STORM MOTION JUST LEADING TO BRIEF HEAVY DOWNPOURS AND PERHAPS A DOWNBURST WIND GUST IN THE NEIGHBORHOOD OF 30 MPH. FARTHER NORTH, THE MAIN STORY WILL BE COOLER FLOW OFF OF LAKE HURON INTO THE THUMB AS NORTHERLY FLOW BEHIND THE TROUGH COMBINES WITH A LAKE BREEZE COMPONENT. CONDITIONS WILL NOT BE AS COOL FARTHER INLAND TOWARD THE TRI CITIES BUT SURFACE DEWPOINT IN THE 50S WILL KEEP CONDITIONS LESS HUMID HEADING INTO THIS EVENING. LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY. BEHIND THE WEAK FRONT TODAY...HIGH PRESSURE WILL BUILD TOWARDS THE EASTERN GREAT LAKES TONIGHT ALLOWING LIGHT WINDS TO VEER AROUND TO THE SOUTHEAST. THIS WILL SET THE STAGE FOR TUESDAY WITH A WEAK CONVERGENT BOUNDARY IN PLACE OVER SOUTHEAST MICHIGAN...SLOWLY LIFTING BACK NORTH AS A WARM FRONT IN ADVANCE OF A BROAD AREA OF LOW PRESSURE TAKING SHAPE ACROSS WESTERN ONTARIO AND THE UPPER MIDWEST. THE ASSOCIATED UPPER LEVEL LOW IS EXPECTED TO GRADUALLY DEEPEN AS IT TRACKS ACROSS ONTARIO THROUGH WEDNESDAY BRINGING A CHANCE OF THUNDERSTORMS TO THE REGION. THE GFS CONTINUES TO STRUGGLE WITH HANDLING OF THIS SYSTEM AND IS ALONE IN SHOWING THE SURFACE LOW DEVELOPING SOUTH OF LAKE SUPERIOR ON TUESDAY. INSTEAD WILL LEAN THE FORECAST IN THE DIRECTION OF A NAM/ECMWF BLEND. BOTH OF THESE MODELS INDICATE A MCS WILL DEVELOP OVER SOUTHERN MINNESOTA/NE IOWA MONDAY NIGHT WITH SOME QUESTION AS TO WHERE THE REMNANTS OF THIS FEATURE WILL TRACK ON TUESDAY. THE ECMWF TRACKS THE DISSIPATING MCS SOUTHWEST OF THE AREA WHILE THE NAM SHOWS AN MCV DEVELOPING AND HELPING TO TRIGGER CONVECTION FOR SOUTHEAST MICHIGAN LATE TUESDAY AFTERNOON. SOUTHERLY WINDS SOUTH OF THE WARM FRONT WILL WORK TO ADVECT A MOIST LOW LEVEL AIRMASS INTO SOUTHERN LOWER MICHIGAN WITH DEWPOINTS REACHING THE MID TO UPPER 60S ACROSS THE SOUTH. THIS SHOULD YIELD MODERATE INSTABILITY OVER THE AREA WITH MODELS SOUNDINGS SHOWING OVER 2500 J/KG OF SURFACE BASED CAPE. QUITE A BIT OF UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE UPSTREAM MCS WHICH WILL AFFECT BOTH THE DEGREE OF CLOUD COVER AND THE POTENTIAL FORCING MECHANISM FOR CONVECTION. MID LEVELS WILL BE RATHER WARM...BUT GIVEN THE INSTABILITY AND WEAK BOUNDARY IN PLACE...WILL NEED TO MONITOR STORMS WITH A SLIGHT CHANCE OF SEVERE WEATHER. THE CHANCE OF THUNDERSTORMS CONTINUES THROUGH WEDNESDAY AS THE ASSOCIATED SURFACE TROUGH MOVES ACROSS THE AREA. A WEAK COLD FRONT WILL DROP SOUTH INTO OUR NORTHERN COUNTIES WEDNESDAY NIGHT BRINGING A COMFORTABLE DAY FOR THURSDAY WITH NEAR NORMAL TEMPERATURES AND LOWER HUMIDITY. RIDGING WILL BUILD OVERHEAD TOWARDS THE END OF THE WEEK WITH THE NEXT CHANCE OF THUNDERSTORMS COMING AS SHORTWAVE ENERGY WORKS TO FLATTEN THE RIDGE AND TRANSITION TO A NEAR ZONAL FLOW ACROSS THE NORTHERN TIER OF STATES. MODELS ARE NOT IN GOOD AGREEMENT ON ANY ONE PARTICULAR PERIOD TO ADD A CHANCE OF SHOWERS/THUNDERSTORMS ALTHOUGH A LOW CHANCE MAY EVENTUALLY NEED TO BE ADDED IN THE FRIDAY THROUGH SUNDAY PERIOD. MARINE... MARINE WEATHER CONCERNS ARE MINIMAL OUTSIDE OF AN ISOLATED THUNDERSTORM POSSIBILITY OVER LAKE ST CLAIR AND WESTERN LAKE ERIE. A WEAK SURFACE TROUGH OF LOW PRESSURE WILL SETTLE FROM CENTRAL LAKE HURON INTO WESTERN LAKE ERIE BY TONIGHT. LIGHT NORTH WINDS WILL QUICKLY BECOME VARIABLE TONIGHT AS HIGH PRESSURE SETTLES INTO THE REGION. THIS WILL GIVE WAY TO INCREASING SOUTHERLY WINDS ON TUESDAY AS THE NEXT LOW PRESSURE SYSTEM TAKES SHAPE IN THE UPPER MIDWEST. SIGNIFICANT THUNDERSTORM POTENTIAL TUESDAY NIGHT INTO WEDNESDAY WILL BE THE MAIN WEATHER CONCERN DURING THAT TIME PERIOD. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......SC AVIATION.....BT SHORT TERM...BT LONG TERM....KEC MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 713 AM EDT MON JUL 28 2008 UPDATED FOR THE 12Z TAF ISSUANCE .SYNOPSIS (ISSUED AT 347 AM EDT)... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING EXTENDING FROM THE FOUR CORNERS INTO SOUTH CENTRAL CANADA...A TROUGH FROM SE CANADA INTO THE EASTERN GREAT LAKES AND A TROUGH IN SW CANADA. WITH UPPER MI IN BETWEEN THE CENTRAL RIDGE AND EASTERN TROUGH...SUBSIDENCE IS OCCURRING ALOFT WHILE HIGH PRESSURE COVERS THE AREA AT THE SURFACE. THIS HIGH PRESSURE RIDGE EXTENDS FROM NE MANITOBA SOUTHWARD INTO MI. DRY AIR ASSOCIATED WITH THE RIDGE (PRECIPITABLE WATER OF 0.68 INCHES AT INL AND 0.82 INCHES AT GRB PER 00Z SOUNDINGS) IS PREVENTING PCPN. HOWEVER...SOME LOW TO MID LEVEL STRATUS CONTINUES TO WRAP AROUND THE EASTERN PORTION OF THE CWA AROUND THE WEST SIDE OF THE SE CANADA TROUGH. OTHER MID AND HIGH CLOUDS CAN BE SEEN OVER NRN MN...NW ONTARIO AND INTO MANITOBA WHICH ARE MOVING THROUGH THE UPPER RIDGE. THESE ARE BEING CREATED THROUGH WEAK SHRTWVS MOVING ACROSS...MID TO UPPER LEVEL MOISTURE FROM THE EAST PACIFIC...AND WARM ADVECTION NOTED BY 850MB TEMPS OF 20C AT BIS AND 22C AT GGW...COMPARED TO 15C AT INL AND 14C AT CYQD. FARTHER WEST...A POTENT LOOKING SHRTWV IS PRESENT IN SW ALBERTA...WITH QUITE A FEW THUNDERSTORMS ON ITS SOUTHERN SIDE. LIKELY COOL MID LEVEL TEMPS ARE PRESENT THERE...WHICH 00Z RAOBS AT CWEG AND CYLW DO INDICATE WITH READINGS AROUND -15C. UPPER LEVEL SMOKE FIELD HARD TO TRACK AT NIGHT...BUT LAST NESDIS SMOKE ANALYSIS AT 02Z INDICATED SMOKE FROM NRN CALIFORNIA...INTO SOUTH CENTRAL CANADA AND SE INTO UPPER MI. SMOKE FROM NORTH CENTRAL CANADA FIRES STAYING TO THE NORTH DUE TO THE UPPER TROUGH MOVING IN THERE. && .DISCUSSION... MAIN FORECAST CONCERN IS THUNDERSTORM DEVELOPMENT FOR TONIGHT/TUE. TODAY...UPPER LEVEL RIDGE OVER SOUTH CENTRAL CANADA IS PROGGED TO DROP DOWN INTO THE WESTERN PORTION OF THE CWA BY 00Z TUE IN RESPONSE TO THE UPPER TROUGH OVER SW CANADA PUSHING EAST. HIGH PRESSURE SHOULD STILL REMAIN AT THE SURFACE DUE TO THE AREA BASICALLY REMAINING TO THE EAST OF THE RIDGE AXIS...AND THE COOL WATER EFFECT FROM LAKES SUPERIOR AND MICHIGAN. THEREFORE...A LAKE BREEZE DAY IS PLANNED SO LAKESHORE LOCATIONS SHOULD SEE SOME COOLING THIS AFTERNOON. AIRMASS REMAINS DRY UNDER THIS RIDGE...WITH PRECIPITABLE WATER VALUES PROGGED TO STAY BETWEEN 0.50 INCH AND 1 INCH. WITH MID LEVEL SUBSIDENCE IN PLACE AND THE DRY AIR...NO PCPN IS EXPECTED. SOME MID/HIGH CLOUDS ARE LIKELY TO SPREAD ACROSS THE CWA AS EVIDENCED UP TO THE NW...ALONG WITH SOME SMOKE UP IN THE UPPER LEVELS. IN ADDITION...DAYTIME CUMULUS WILL LIKELY FORM...ESPECIALLY IN THE WRN U.P. WHERE RETURN FLOW HELPS RAISE DEWPOINTS INTO THE MID/UPPER 50S. THE COMBINATION OF THE CLOUDS/SMOKE SHOULD PREVENT MIXING SOME...BUT READINGS ARE STILL PLANNED TO REACH INTO THE 70S TO LOW 80S WITH WITH 850MB TEMPS OF 12-15C. WARMEST READINGS EXPECTED ALONG THE WI BORDER. TONIGHT...UPPER RIDGE OVER THE WRN PORTION OF THE CWA AT 00Z WILL CONTINUE TO SLIDE EASTWARD THROUGH THE NIGHT...WHILE THE POTENT LOOKING SHRTWV OVER SW ALBERTA MOVES TO SE MANITOBA BY 12Z TUE. THE MOVEMENT OF THESE MID LEVEL FEATURES MEANS THAT THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES REGION WILL BE UNDER WARM ADVECTION. GIVEN THE APPROACH OF THE SHRTWV...MOST MODELS SHOW A FAIRLY STRONG SURFACE LOW (AROUND 1000MB) OVER CENTRAL MANITOBA BY 12Z...MEANING THAT THE WARM ADVECTION WILL LIKELY BE ACCOMPANIED BY A FAIRLY STRONG LOW LEVEL JET. NAM PROGGED 850MB WINDS ARE AROUND 30 KT OUT OF THE SW ACROSS MUCH OF MN AFTER 06Z...WHICH THEN VEER TO POINT TOWARDS UPPER MI. 850MB THETA-E ADVECTION VALUES INCREASE ACROSS NRN MN INTO THE CWA...ESPECIALLY IN THE WESTERN U.P....SUGGESTING PRETTY GOOD MOISTURE RETURN WITH THE LOW LEVEL JET. HOWEVER...ANOTHER ZONE OF STRONG ADVECTION VALUES EXIST IN SRN MN AND NRN IA. EACH ZONE ARE LIKELY AREAS FOR TSTM INITIATION...AND THEREFORE CHANCE POPS ARE IN THE FORECAST FOR THE WESTERN CWA...MAINLY AFTER 06Z. SOME CONCERN EXISTS FOR HAIL GIVEN MUCAPES AROUND 1000 J/KG AND EFFECTIVE SHEAR VALUES OF 25-30 KT. HOWEVER...FREEZING LVL HEIGHTS ARE A BIT HIGH...AROUND 14000 FT. SPC DAY 1 OUTLOOK OF 5 PCT SEEMS REASONABLE. THE EASTERN CWA LOOKS TO BE TOO CAPPED TO ALLOW FOR PCPN. GIVEN INCREASING CLOUD COVER FROM THE WARM ADVECTION...INCREASING SOUTHERLY WINDS AND HIGHER DEWPOINTS MOVING IN...LOW TEMPS SHOULD GENERALLY BE IN THE 50S TO LOW 60S. COOLEST READINGS EXPECTED IN THE EAST WHERE MOSTLY CLEAR SKIES AND LIGHT WINDS IN THE EVENING ALLOW FOR GREATER RADIATIONAL COOLING. TUESDAY...UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA SHIFTS INTO NRN ONTARIO DURING THE DAY...ALLOWING A SURFACE COLD FRONT TO APPROACH THE WRN LAKE SUPERIOR AND IWD BY 00Z. CONVECTIVE FEEDBACK IN THE MODELS FROM CONVECTION TONIGHT OVER NRN MN RESULTS IN SOME ISSUES WITH THE FORECAST...HOWEVER...THERE IS A GENERAL CONSENSUS FROM THE 00Z/18Z GFS...THE 00Z ECMWF...UKMET...REGIONAL CANADIAN AND NAM FOR WHATEVER MCS THAT DEVELOPS OVER NRN MN/WRN LAKE SUPERIOR TO SLIDE AND WEAKEN AS IT CROSSES THE CWA THROUGH THE DAY. THEREFORE PCPN CHANCES REMAIN IN THE FORECAST...BUT MUCH OF THE CONVECTION IS ASSUMED TO BE ELEVATED AND NOT SURFACE BASED. ALL SURFACE BASED CONVECTION SHOULD OCCUR TO THE SOUTH OF THE CWA DUE TO OUTFLOW BOUNDARIES FROM THIS MCS. IF OUR LOCAL WRF-ARW RUN IS CORRECT AND KEEPING MUCH OF THE MCS ACTIVITY ACROSS LAKE SUPERIOR AND THE NRN U.P....THEN THERE WOULD BE AN OPPORTUNITY FOR THE SOUTHERN U.P. TO HEAT UP AND THUS RESULT IN SOME SURFACE BASED CONVECTION. FUTURE FCST SHIFTS WILL NEED TO MONITOR. REGARDING SEVERE CHANCES...SIMILAR CONDITIONS EXIST TO TONIGHT WITH MUCAPES BETWEEN 1000-1500 J/KG... EFFECTIVE SHEAR VALUES OF 25-30 KT AND FREEZING LEVELS NEAR 14000 FT...WITH INSTABILITY DIMINISHING TO THE EAST. THEREFORE SOME HAIL IS NOT OUT OF THE QUESTION...BEST CHANCES IN THE WESTERN U.P WHERE HIGHER INSTABILITY IS PRESENT. HIGH TEMPERATURES ARE TRICKY...WITH CONCERN OF LOCATION OF MCS AND 850MB TEMPS OF 15-19C AT LEAST. WILL STAY ON THE CONSERVATIVE END OF GUIDANCE...WITH WARMEST READINGS IN THE SOUTH CENTRAL U.P.. TUE NIGHT AND WED...UPPER TROUGH IS PROGGED TO CONTINUE MARCHING ACROSS NRN ONTARIO DURING THIS PERIOD...WITH MODELS ACTUALLY SUGGESTING THE UPPER LEVEL PATTERN BY 00Z THU LOOKING VERY SIMILAR TO WHAT IS OCCURRING NOW...THOUGH WITH SLIGHTLY LESS AMPLIFICATION. HAVE DISCOUNTED THE GFS WITH THE HANDLING OF THE UPPER TROUGH... PRIMARILY DUE TO ITS CONVECTIVE FEEDBACK PROBLEMS IT HAS BACK WITH TONIGHTS ACTIVITY...WHICH MERGES WITH THE UPPER TROUGH. FOLLOWED CLOSER TO THE NAM/UKMET/ECMWF. ANY LINGERING CONVECTION FROM TUE... BE IT ELEVATED OR POSSIBLY SURFACE BASED...SHOULD EXIT MUCH IF NOT ALL OF THE CWA TUE EVENING. MOSTLY DRY CONDITIONS WITH DECREASING CLOUDS ARE EXPECTED FOR AFTER MIDNIGHT TUE NIGHT INTO WED...WHICH SHOULD ALLOW FOR SLIGHTLY COOLER TEMPS TUE NIGHT COMPARED TO MON NIGHT. FOR WED AFTERNOON...A SURFACE TROUGH ASSOCIATED WITH THE UPPER LEVEL TROUGH IS INDICATED TO DROP DOWN INTO THE CWA. LAKE BREEZE CONVERGENCE INTO THIS TROUGH...COMBINED WITH LINGERING LOW LEVEL MOISTURE (DEWPOINTS PROGGED AROUND 60) SHOULD RESULT IN SOME SCATTERED SHOWERS AND THUNDERSTORMS OVER THE EAST HALF OF THE CWA AWAY FROM LAKE SUPERIOR. GOING HIGH TEMPS LOOK REASONABLE...WITH COOLEST READINGS NEAR LAKE SUPERIOR WITH EXPECTED ONSHORE FLOW. WED NIGHT AND THU...UPPER LEVEL TROUGH SHIFTS OFF TO THE EAST...ALLOWING HIGH PRESSURE TO BUILD DOWN FROM CANADA AT THE SURFACE. THIS WILL ALLOW DRIER AIR TO FILTER SOUTH...THOUGH THERE STILL MAY BE SOME LOW TO MID LEVEL STRATUS FOR WED NIGHT. LOWERED LOW TEMPS SOME FOR WED NIGHT GIVEN MEX GUIDANCE READINGS IN THE UPPER 40S FOR THE WESTERN U.P.. HOWEVER...IF THERE IS LESS CLOUD COVER THAN FORECAST...COULD SEE A NEED TO LOWER LOW TEMPS MORE FOR WED NIGHT SINCE A DRY AIRMASS IS MOVING IN. THIS HIGH PRESSURE RIDGE MOVES OVER THE CWA ON THU...SO EXPECT ANOTHER LAKE BREEZE DAY WITH CONDITIONS VERY SIMILAR TO TODAY...BOTH CLOUD COVER AND TEMPERATURE WISE. ONLY PCPN FORECAST FOR THE PERIOD IS IN THE SE CWA EARLY WED EVENING WITH ANY LINGERING CONVECTION. NO CHANGES MADE BEYOND THU. HOWEVER...CHANCE POPS MAY BE NEEDED FOR THU NIGHT AND FRI...MAINLY IN THE SOUTHERN U.P....WITH THE 00Z ECMWF/GFS SUGGESTING WARM ADVECTION PCPN ACROSS THE SOUTHERN U.P. AND NRN WI. WILL LET DAY SHIFT LOOK AT THIS CLOSER. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CONDITIONS SHOULD REMAIN...WITH MAINLY JUST HIGH CLOUDS AND DRY WEATHER. HIGH RANGE MVFR CIGS REMAIN OVER EASTERN LAKE SUPERIOR...AND HAVE MOVED ACROSS EASTERN UPPER MICHIGAN AS WELL. THEY SHOULD STILL REMAIN JUST EAST OF SAW. DUE TO WNW FLOW ALOFT BRINGING IN AN ELEVATED SMOKE LAYER FROM WILDFIRES IN NRN CALIFORNIA AND NORTH CENTRAL CANADA...HAZY HIGH CLOUDINESS WILL REMAIN. WITH ONLY 20 PERCENT CHANCE OF RECEIVING -RA OR -TSRA BETWEEN 09Z AND 12Z IN OUR REGULAR FORECAST...HAVE OPTED TO KEEP THE MENTION OF PRECIPITATION OUT OF THIS ISSUANCE AND SLOWLY LOWER CIG HEIGHS INSTEAD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SFC HIGH DIRECTLY OVERHEAD SHOULD RESULT IN LIGHT WINDS. THE LIGHT WINDS WILL BE SHORT LIVED AS A LOW PRESSURE TROUGH MOVES IN FROM THE HIGH PLAINS ON TUESDAY. WINDS WILL BECOME SOUTHERLY OVERNIGHT INTO TUESDAY MORNING AND STRENGTHEN THROUGH THE AFTERNOON HOURS. WINDS WILL BE STRONG ONCE AGAIN FROM THE WEST WEDNESDAY AFTERNOON...AS THE LOW SLOWLY MOVES EASTWARD TO THE NEW ENGLAND STATES BY THURSDAY MORNING. HIGH PRESSURE WILL THEN MOVE OVER LAKE SUPERIOR FOR ONCE AGAIN FOR THURSDAY AND FRIDAY...WITH WINDS GENERALLY LESS THAN 15 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 347 AM EDT MON JUL 28 2008 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING EXTENDING FROM THE FOUR CORNERS INTO SOUTH CENTRAL CANADA...A TROUGH FROM SE CANADA INTO THE EASTERN GREAT LAKES AND A TROUGH IN SW CANADA. WITH UPPER MI IN BETWEEN THE CENTRAL RIDGE AND EASTERN TROUGH...SUBSIDENCE IS OCCURRING ALOFT WHILE HIGH PRESSURE COVERS THE AREA AT THE SURFACE. THIS HIGH PRESSURE RIDGE EXTENDS FROM NE MANITOBA SOUTHWARD INTO MI. DRY AIR ASSOCIATED WITH THE RIDGE (PRECIPITABLE WATER OF 0.68 INCHES AT INL AND 0.82 INCHES AT GRB PER 00Z SOUNDINGS) IS PREVENTING PCPN. HOWEVER...SOME LOW TO MID LEVEL STRATUS CONTINUES TO WRAP AROUND THE EASTERN PORTION OF THE CWA AROUND THE WEST SIDE OF THE SE CANADA TROUGH. OTHER MID AND HIGH CLOUDS CAN BE SEEN OVER NRN MN...NW ONTARIO AND INTO MANITOBA WHICH ARE MOVING THROUGH THE UPPER RIDGE. THESE ARE BEING CREATED THROUGH WEAK SHRTWVS MOVING ACROSS...MID TO UPPER LEVEL MOISTURE FROM THE EAST PACIFIC...AND WARM ADVECTION NOTED BY 850MB TEMPS OF 20C AT BIS AND 22C AT GGW...COMPARED TO 15C AT INL AND 14C AT CYQD. FARTHER WEST...A POTENT LOOKING SHRTWV IS PRESENT IN SW ALBERTA...WITH QUITE A FEW THUNDERSTORMS ON ITS SOUTHERN SIDE. LIKELY COOL MID LEVEL TEMPS ARE PRESENT THERE...WHICH 00Z RAOBS AT CWEG AND CYLW DO INDICATE WITH READINGS AROUND -15C. UPPER LEVEL SMOKE FIELD HARD TO TRACK AT NIGHT...BUT LAST NESDIS SMOKE ANALYSIS AT 02Z INDICATED SMOKE FROM NRN CALIFORNIA...INTO SOUTH CENTRAL CANADA AND SE INTO UPPER MI. SMOKE FROM NORTH CENTRAL CANADA FIRES STAYING TO THE NORTH DUE TO THE UPPER TROUGH MOVING IN THERE. && .DISCUSSION... MAIN FORECAST CONCERN IS THUNDERSTORM DEVELOPMENT FOR TONIGHT/TUE. TODAY...UPPER LEVEL RIDGE OVER SOUTH CENTRAL CANADA IS PROGGED TO DROP DOWN INTO THE WESTERN PORTION OF THE CWA BY 00Z TUE IN RESPONSE TO THE UPPER TROUGH OVER SW CANADA PUSHING EAST. HIGH PRESSURE SHOULD STILL REMAIN AT THE SURFACE DUE TO THE AREA BASICALLY REMAINING TO THE EAST OF THE RIDGE AXIS...AND THE COOL WATER EFFECT FROM LAKES SUPERIOR AND MICHIGAN. THEREFORE...A LAKE BREEZE DAY IS PLANNED SO LAKESHORE LOCATIONS SHOULD SEE SOME COOLING THIS AFTERNOON. AIRMASS REMAINS DRY UNDER THIS RIDGE...WITH PRECIPITABLE WATER VALUES PROGGED TO STAY BETWEEN 0.50 INCH AND 1 INCH. WITH MID LEVEL SUBSIDENCE IN PLACE AND THE DRY AIR...NO PCPN IS EXPECTED. SOME MID/HIGH CLOUDS ARE LIKELY TO SPREAD ACROSS THE CWA AS EVIDENCED UP TO THE NW...ALONG WITH SOME SMOKE UP IN THE UPPER LEVELS. IN ADDITION...DAYTIME CUMULUS WILL LIKELY FORM...ESPECIALLY IN THE WRN U.P. WHERE RETURN FLOW HELPS RAISE DEWPOINTS INTO THE MID/UPPER 50S. THE COMBINATION OF THE CLOUDS/SMOKE SHOULD PREVENT MIXING SOME...BUT READINGS ARE STILL PLANNED TO REACH INTO THE 70S TO LOW 80S WITH WITH 850MB TEMPS OF 12-15C. WARMEST READINGS EXPECTED ALONG THE WI BORDER. TONIGHT...UPPER RIDGE OVER THE WRN PORTION OF THE CWA AT 00Z WILL CONTINUE TO SLIDE EASTWARD THROUGH THE NIGHT...WHILE THE POTENT LOOKING SHRTWV OVER SW ALBERTA MOVES TO SE MANITOBA BY 12Z TUE. THE MOVEMENT OF THESE MID LEVEL FEATURES MEANS THAT THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES REGION WILL BE UNDER WARM ADVECTION. GIVEN THE APPROACH OF THE SHRTWV...MOST MODELS SHOW A FAIRLY STRONG SURFACE LOW (AROUND 1000MB) OVER CENTRAL MANITOBA BY 12Z...MEANING THAT THE WARM ADVECTION WILL LIKELY BE ACCOMPANIED BY A FAIRLY STRONG LOW LEVEL JET. NAM PROGGED 850MB WINDS ARE AROUND 30 KT OUT OF THE SW ACROSS MUCH OF MN AFTER 06Z...WHICH THEN VEER TO POINT TOWARDS UPPER MI. 850MB THETA-E ADVECTION VALUES INCREASE ACROSS NRN MN INTO THE CWA...ESPECIALLY IN THE WESTERN U.P....SUGGESTING PRETTY GOOD MOISTURE RETURN WITH THE LOW LEVEL JET. HOWEVER...ANOTHER ZONE OF STRONG ADVECTION VALUES EXIST IN SRN MN AND NRN IA. EACH ZONE ARE LIKELY AREAS FOR TSTM INITIATION...AND THEREFORE CHANCE POPS ARE IN THE FORECAST FOR THE WESTERN CWA...MAINLY AFTER 06Z. SOME CONCERN EXISTS FOR HAIL GIVEN MUCAPES AROUND 1000 J/KG AND EFFECTIVE SHEAR VALUES OF 25-30 KT. HOWEVER...FREEZING LVL HEIGHTS ARE A BIT HIGH...AROUND 14000 FT. SPC DAY 1 OUTLOOK OF 5 PCT SEEMS REASONABLE. THE EASTERN CWA LOOKS TO BE TOO CAPPED TO ALLOW FOR PCPN. GIVEN INCREASING CLOUD COVER FROM THE WARM ADVECTION...INCREASING SOUTHERLY WINDS AND HIGHER DEWPOINTS MOVING IN...LOW TEMPS SHOULD GENERALLY BE IN THE 50S TO LOW 60S. COOLEST READINGS EXPECTED IN THE EAST WHERE MOSTLY CLEAR SKIES AND LIGHT WINDS IN THE EVENING ALLOW FOR GREATER RADIATIONAL COOLING. TUESDAY...UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA SHIFTS INTO NRN ONTARIO DURING THE DAY...ALLOWING A SURFACE COLD FRONT TO APPROACH THE WRN LAKE SUPERIOR AND IWD BY 00Z. CONVECTIVE FEEDBACK IN THE MODELS FROM CONVECTION TONIGHT OVER NRN MN RESULTS IN SOME ISSUES WITH THE FORECAST...HOWEVER...THERE IS A GENERAL CONSENSUS FROM THE 00Z/18Z GFS...THE 00Z ECMWF...UKMET...REGIONAL CANADIAN AND NAM FOR WHATEVER MCS THAT DEVELOPS OVER NRN MN/WRN LAKE SUPERIOR TO SLIDE AND WEAKEN AS IT CROSSES THE CWA THROUGH THE DAY. THEREFORE PCPN CHANCES REMAIN IN THE FORECAST...BUT MUCH OF THE CONVECTION IS ASSUMED TO BE ELEVATED AND NOT SURFACE BASED. ALL SURFACE BASED CONVECTION SHOULD OCCUR TO THE SOUTH OF THE CWA DUE TO OUTFLOW BOUNDARIES FROM THIS MCS. IF OUR LOCAL WRF-ARW RUN IS CORRECT AND KEEPING MUCH OF THE MCS ACTIVITY ACROSS LAKE SUPERIOR AND THE NRN U.P....THEN THERE WOULD BE AN OPPORTUNITY FOR THE SOUTHERN U.P. TO HEAT UP AND THUS RESULT IN SOME SURFACE BASED CONVECTION. FUTURE FCST SHIFTS WILL NEED TO MONITOR. REGARDING SEVERE CHANCES...SIMILAR CONDITIONS EXIST TO TONIGHT WITH MUCAPES BETWEEN 1000-1500 J/KG... EFFECTIVE SHEAR VALUES OF 25-30 KT AND FREEZING LEVELS NEAR 14000 FT...WITH INSTABILITY DIMINISHING TO THE EAST. THEREFORE SOME HAIL IS NOT OUT OF THE QUESTION...BEST CHANCES IN THE WESTERN U.P WHERE HIGHER INSTABILITY IS PRESENT. HIGH TEMPERATURES ARE TRICKY...WITH CONCERN OF LOCATION OF MCS AND 850MB TEMPS OF 15-19C AT LEAST. WILL STAY ON THE CONSERVATIVE END OF GUIDANCE...WITH WARMEST READINGS IN THE SOUTH CENTRAL U.P.. TUE NIGHT AND WED...UPPER TROUGH IS PROGGED TO CONTINUE MARCHING ACROSS NRN ONTARIO DURING THIS PERIOD...WITH MODELS ACTUALLY SUGGESTING THE UPPER LEVEL PATTERN BY 00Z THU LOOKING VERY SIMILAR TO WHAT IS OCCURRING NOW...THOUGH WITH SLIGHTLY LESS AMPLIFICATION. HAVE DISCOUNTED THE GFS WITH THE HANDLING OF THE UPPER TROUGH... PRIMARILY DUE TO ITS CONVECTIVE FEEDBACK PROBLEMS IT HAS BACK WITH TONIGHTS ACTIVITY...WHICH MERGES WITH THE UPPER TROUGH. FOLLOWED CLOSER TO THE NAM/UKMET/ECMWF. ANY LINGERING CONVECTION FROM TUE... BE IT ELEVATED OR POSSIBLY SURFACE BASED...SHOULD EXIT MUCH IF NOT ALL OF THE CWA TUE EVENING. MOSTLY DRY CONDITIONS WITH DECREASING CLOUDS ARE EXPECTED FOR AFTER MIDNIGHT TUE NIGHT INTO WED...WHICH SHOULD ALLOW FOR SLIGHTLY COOLER TEMPS TUE NIGHT COMPARED TO MON NIGHT. FOR WED AFTERNOON...A SURFACE TROUGH ASSOCIATED WITH THE UPPER LEVEL TROUGH IS INDICATED TO DROP DOWN INTO THE CWA. LAKE BREEZE CONVERGENCE INTO THIS TROUGH...COMBINED WITH LINGERING LOW LEVEL MOISTURE (DEWPOINTS PROGGED AROUND 60) SHOULD RESULT IN SOME SCATTERED SHOWERS AND THUNDERSTORMS OVER THE EAST HALF OF THE CWA AWAY FROM LAKE SUPERIOR. GOING HIGH TEMPS LOOK REASONABLE...WITH COOLEST READINGS NEAR LAKE SUPERIOR WITH EXPECTED ONSHORE FLOW. WED NIGHT AND THU...UPPER LEVEL TROUGH SHIFTS OFF TO THE EAST...ALLOWING HIGH PRESSURE TO BUILD DOWN FROM CANADA AT THE SURFACE. THIS WILL ALLOW DRIER AIR TO FILTER SOUTH...THOUGH THERE STILL MAY BE SOME LOW TO MID LEVEL STRATUS FOR WED NIGHT. LOWERED LOW TEMPS SOME FOR WED NIGHT GIVEN MEX GUIDANCE READINGS IN THE UPPER 40S FOR THE WESTERN U.P.. HOWEVER...IF THERE IS LESS CLOUD COVER THAN FORECAST...COULD SEE A NEED TO LOWER LOW TEMPS MORE FOR WED NIGHT SINCE A DRY AIRMASS IS MOVING IN. THIS HIGH PRESSURE RIDGE MOVES OVER THE CWA ON THU...SO EXPECT ANOTHER LAKE BREEZE DAY WITH CONDITIONS VERY SIMILAR TO TODAY...BOTH CLOUD COVER AND TEMPERATURE WISE. ONLY PCPN FORECAST FOR THE PERIOD IS IN THE SE CWA EARLY WED EVENING WITH ANY LINGERING CONVECTION. NO CHANGES MADE BEYOND THU. HOWEVER...CHANCE POPS MAY BE NEEDED FOR THU NIGHT AND FRI...MAINLY IN THE SOUTHERN U.P....WITH THE 00Z ECMWF/GFS SUGGESTING WARM ADVECTION PCPN ACROSS THE SOUTHERN U.P. AND NRN WI. WILL LET DAY SHIFT LOOK AT THIS CLOSER. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS SHOULD REMAIN...WITH MAINLY JUST HIGH CLOUDS AND DRY WEATHER. STILL LOOKS LIKE MVFR CIGS REMAIN OVER NE LAKE SUPERIOR. THEY SHOULD REMAIN OUT OF THE TAF SITES...WITH A SMALL CHANCE THAT SOME COULD FILTER INTO SAW EARLY THIS MORNING. HAZY HIGH CLOUD SHOULD CONTINUE DUE TO WNW FLOW ALOFT BRINGING IN AN ELEVATED SMOKE LAYER FROM WILDFIRES IN NRN CALIFORNIA AND NORTH CENTRAL CANADA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SFC HIGH DIRECTLY OVERHEAD SHOULD RESULT IN LIGHT WINDS. THE LIGHT WINDS WILL BE SHORT LIVED AS A LOW PRESSURE TROUGH MOVES IN FROM THE HIGH PLAINS ON TUESDAY. WINDS WILL BECOME SOUTHERLY OVERNIGHT INTO TUESDAY MORNING AND STRENGTHEN THROUGH THE AFTERNOON HOURS. WINDS WILL BE STRONG ONCE AGAIN FROM THE WEST WEDNESDAY AFTERNOON...AS THE LOW SLOWLY MOVES EASTWARD TO THE NEW ENGLAND STATES BY THURSDAY MORNING. HIGH PRESSURE WILL THEN MOVE OVER LAKE SUPERIOR FOR ONCE AGAIN FOR THURSDAY AND FRIDAY...WITH WINDS GENERALLY LESS THAN 15 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 338 AM EDT MON JUL 28 2008 LATEST UPDATE...ALL BUT AVIATION .SYNOPSIS...(338 AM EDT MON JUL 28 2008) WEAK HIGH PRESSURE OVER THE GREAT LAKES WILL GRADUALLY DRIFT EAST TODAY ALLOWING A WARM FRONT TO DEVELOP AND MOVE NORTH INTO THE REGION TUESDAY. THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL INCREASE TUESDAY THROUGH EARLY WEDNESDAY AS THE WARM FRONT MOVES THROUGH AND THEN THE COLD FRONT. HIGH TEMPERATURES WILL BE MAINLY IN THE MID 80S FOR THE NEXT FEW DAYS. && .SHORT TERM...(338 AM EDT MON JUL 28 2008) (TODAY THROUGH WEDNESDAY) FORECAST CONCERNS TODAY DEAL WITH CONVECTIVE POTENTIAL TUESDAY THROUGH WEDNESDAY. A WEAK COLD FRONT WILL DRIFT SOUTH THROUGH THE CWA TODAY BEFORE HEADING BACK NORTH AS A WARM FRONT TUESDAY. CURRENTLY THERE IS REALLY NO WEATHER WITH THE FRONT AS SKIES ARE CLEAR. MODELS REALLY DON/T PAINT MUCH EITHER EXCEPT FOR THE 4KM WRF WHICH DEVELOPS A FEW SHOWERS ALONG IT LATER THIS AFTERNOON. RUC SOUNDINGS ARE PRETTY DRY THROUGHOUT THE PROFILE SO WE/RE GOING TO LEAVE THE GRIDS DRY TODAY. THE NWD MOVING WARM FRONT IS PROGD TO MOVE THROGH THE CWA TUESDAY MORNING. INSTABILITY WILL INCREASE THROUGHOUT THE DAY WITH LI/S IN THE -4 TO -6C RANGE ON THE NAM. GFS IS MUCH MORE UNSTABLE LIKELY DUE TO THE VERY HIGH SFC DEWPOINTS IT CREATES. I HAVE A HARD TIME BELIEVING WE/LL SEE SFC DEWPOINTS NEAR 77F TUESDAY AFTERNOON. THE NAM/S DEWPOINTS AROUND 70 ARE MORE BELIEVABLE. LLJ SUPPORT IS WEST OF THE LAKE. IF STORMS FIRE ON THE WARM FRONT I SUSPECT MOST OF THEM WILL BE WEST OF THE CWA. WE/LL KEEP LOW CHC POPS IN TO COVER THE FRONT. A HIGHER CHANCE OF RAIN WILL COME WITH THE TRAILING COLD FRONT TUESDAY NIGHT INTO WEDNESDAY. LLJ INCREASES TO AROUND 30KTS TUESDAY NIGHT BUT THAT WILL BE WHEN INSTABILITY IS WEAKEST. SO WE/RE LIKELY TO SEE MORE STORMS...BUT PERHAPS A BIT WEAKER. NO REAL IMPRESSED WITH THE SVR THREAT AS 0-6KM BULK SHEAR REMAINS AOB 40 KTS THROUGH THE PERIOD. && .LONG TERM...(338 AM EDT MON JUL 28 2008) (WEDNESDAY NIGHT THROUGH SUNDAY) AS I DID YESTERDAY...SO I WILL DO EARLY THIS MORNING. THAT IS... I MADE NO SIGNIFICANT CHANGES TO THE MEDIUM RANGE PART OF THE GOING FORECAST. MODEL CONTINUITY ON BOTH THE GFS AND ECMWF BEYOND WEDNESDAY POOR AT BEST. GIVEN THE SIGNIFICANT UNCERTAINTIES IT WOULD SEEM UNREASONABLE TO MAKE SIGNIFICANT CHANGES TO OUR FORECAST AT THIS POINT. HAVING SAID THAT...THE LONGWAVE PATTERN SEEMS LOCKED IN PLACE WITH TROUGHS NEAR BOTH COASTS AND A FLAT RIDGE OVER WESTERN PLAINS. EVERY TIME A PACIFIC SHORTWAVE TOPS THE RIDGE THE PATTERN BECOMES FLATTER. WHEN THAT WAVE REACHES THE DOWNSTREAM TROUGH... THE PATTERN BECOMES MORE AMPLIFIED. THE GRR CWA IS ON THE DOWNSTREAM SIDE UPPER RIDGE... NEAR THE INFLECTION POINT IN THE FLOW. THAT IS KEEPING MOST OF THE PRECIPITATION NORTH AND SOUTH OF HERE. THAT IS DUE TO THE NORTHERN STREAM JET BEING TO OUR NORTH AND THE SUBTROPICAL JET STAYING TO OUR SOUTH. I SEE NO BIG CHANGES TO THIS PATTERN FOR SOME TIME TO COME. ANY SYSTEMS THAT DO COME THROUGH WILL FOR THE MOST PART BE WEAK IN TERMS OF LARGE SCALE PRECIPITATION POTENTIAL. TEMPERATURES WILL FOR THE MOST PART BE ON THE WARM SIDE OF NORMAL. I DO NOT BUY INTO THE STRONG COLD FRONT THE GFS BRINGS SOUTH ON THURSDAY ANY MORE THAN I BELIEVE THE 12Z ECMWF COLD FRONT FRIDAY INTO THE WEEKEND. BOTH FEATURES ARE LARGE CHANGES FROM THE PREVIOUS RUNS OR THE RUNS BEFORE THAT. THUS DUE TO LOW CONFIDENCE... I HAVE ALLOWED THE CURRENT VERSION OF OUR FORECAST FOR WEDNESDAY NIGHT THROUGH SATURDAY TO CONTINUE AS IS. && .MARINE...(338 AM EDT MON JUL 28 2008) LIGHT WINDS WILL RESULT IN WAVES LESS THAN 2 FEET THROUGH TUESDAY. && .AVIATION...(1152 PM EDT SUN JUL 27 2008) VFR CONDITIONS WILL PREVAIL OVER THE NEXT 24 HOURS. CLOUD BASES TONIGHT WILL BE AOA 8000 FEET AND THE DIURNAL CUMULUS DECK ON MONDAY WILL BE AOA 3500 FEET. AZO HAS BEEN EXPERIENCING SOME MVFR HAZE THIS AFTERNOON AND EVENING... AND WILL CARRY THAT OVERNIGHT... BUT IT IS LOCALIZED (PER SURROUNDING OBS) AND CONFIDENCE IS LOW ON HOW MUCH LONGER IT WILL LINGER. WIND SPEEDS WILL BE LIGHT AND VARIABLE NEXT 24 HOURS... ALTHOUGH A 10 KNOT ONSHORE FLOW SHOULD DEVELOP MONDAY AFTERNOON ALONG THE LAKE MICHIGAN SHORELINE. && .HYDROLOGY...(338 AM EDT MON JUL 28 2008) FEW HYDRO CONCERNS TODAY DUE TO THE DRY WX REGIME. SHOWERS AND THUNDERSTORMS ARE POSSIBLE TUESDAY AND WEDNESDAY. LOCALLY HEAVY RAINFALL IS POSSIBLE WITH PWATS AROUND 2 INCHES. WIDESPREAD FLOODING IS NOT ANTICIPATED THOUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: 93 SHORT TERM: 93 LONG TERM: WDM MARINE: 93 AVIATION: MEADE HYDROLOGY: 93 mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1227 AM CDT MON JUL 28 2008 .UPDATE... LOCAL RADAR REMAINS ECHO FREE THIS EVENING WITH MOST ACTION OVER NORTHEAST MISSOURI. CELLS OVER NORTHEAST MISSOURI MAY CLIP OUR NORTHEASTERN COUNTIES HERE LATER THIS EVENING LOOKING AT TRAJECTORY OF MOVEMENT. WENT AHEAD AND INCREASED POPS AROUND VICHY AND OSAGE BEACH TO COVER THIS TENDENCY. OTHERWISE...LOWERED POPS ELSEWHERE FOR THIS EVENING. GCC && .DISCUSSION... MAIN FORECAST CHALLENGES REMAIN THE CHANCES OF PRECIPITATION AND HEAT THROUGH THE UPCOMING WEEK. AFTERNOON CONVECTION THIS EVENING AND THEN THE REMNANTS OF DOLLY MUDDLE THE MESS MORE. FOR THIS EVENING...THUNDERSTORMS NOW DEVELOPING IN NW MISSOURI WILL LIKELY RIDE SOUTH ALONG THE INSTABILITY AXIS FROM NE KANSAS TO NE ARKANSAS. WEAK ISENTROPIC LIFT AND LITTLE CIN SHOULD ALLOW SOME ISOLATED STORMS TO MOVE THROUGH PORTIONS OF THE OZARKS THIS EVENING WITH CORFIDI VECTORS INDICATING A SOUTHWARD STORM MOTION INTO SW MISSOURI. GFS BUFR SOUNDING SHOWS A PRETTY DRY LAYER THAT WOULD WORK AGAINST STORM DEVELOPMENT...HOWEVER...RUC/NAM AND THE 12Z KSGF SOUNDING ARE NOT INDICATING SUCH A DRAMATIC DRY LAYER. GOING WITH THE RUC/NAM SOUNDING YIELD PWATS IN THE 1.50 TO 1.70 RANGE. THIS IS SUFFICIENT FOR STRONG PULSE THUNDERSTORM DEVELOPMENT WILL LIKELY SEE STORMS DEVELOP OVER THE NE THIRD OF THE CWA LATE THIS AFTERNOON. NOTED THIS IN THE HWO BUT WILL NEED TO MONITOR DEVELOPMENT AND TRAJECTORY OF STORMS THIS EVENING. SOME OF THE HOTTEST TEMPERATURES WILL BE FELT ON MONDAY AS THE HIGH OVER THE PLAINS EXPANDS EAST A TOUCH IN TO THE REGION. THIS WILL PRODUCE HEAT INDICES IN THE 99 TO 103 RANGE ACROSS THE AREA AND MAKE FOR AN UNPLEASANT OUTDOOR DAY. WHILE TEMPERATURES WILL BE HOT...SUBSIDENCE FROM THE HIGH PRESSURE WILL KEEP NEARLY ANY STORM THAT TRIES TO DEVELOP IN CHECK SO HAVE KEPT PRECIPITATION CHANCES OUT OF THE FORECAST FOR MONDAY. HELD OFF ON ANY HEAT ADVISORY AS WELL AS HEAT INDEX VALUES REMAIN BELOW THE 105 DEGREE THRESHOLD THOUGH THIS WILL NEED TO BE WATCHED CLOSELY. FOR MID WEEK...BOTH THE GFS AND ECMWF REMAIN IN AGREEMENT WITH THE TRACK AND TIMING OF THE REMNANTS OF DOLLY AS COMPARED TO YESTERDAYS RUNS. THIS 24 HOUR CONSISTENCY INCREASES CONFIDENCE THAT THE OZARKS WILL SEE RAINFALL LATE TUESDAY INTO WEDNESDAY AS DOLLY IS ENTRAINED IN THE UPPER LEVEL PATTERN AND SWINGS ACROSS THE REGION. BECAUSE OF THIS HAVE LOWERED HIGH TEMPERATURES FOR WEDNESDAY NEARER THE MEX GUIDANCE NUMBERS IN THE UPPER 80 TO AROUND 90. THE AREA SHOULD BE UNDER AN OVERCAST SKY TUESDAY NIGHT THROUGH WEDNESDAY AS DOLLY TRAVERSES THE AREA. DID INCREASE RAIN CHANCES TO CHANCE FOR MOST OF THE OZARKS. ONCE DOLLY MAKE ITS WAY EAST OF THE REGION THE UPPER LEVEL RIDGE BEGINS TO BUILD EASTWARD AND THE REGION BEGINS TO HEAT UP AGAIN. SO THE TEMPERATURE REPRIEVE AFFORDED BY DOLLY WILL BE SHORT LIVED. TEMPERATURES WILL CLIMB BACK INTO THE LOW TO MID 90S FOR THE REMAINDER OF THE WEEK INTO THE WEEKEND WITH CHANCES OF AFTERNOON SHOWERS AND THUNDERSTORMS A CONTINUING POSSIBILITY. A FEW SHORT WAVE COULD MOVE OVER THE PERIPHERY OF THE RIDGE AN PRODUCE A STORM COMPLEX OF TWO BUT WILL HAVE TO PLAY WAIT AND SEE ON THESE BEFORE GOING MUCH MORE THEN A SLIGHT CHANCE OF PRECIPITATION. HATCH && .AVIATION... FOR THE 06Z TAF PACKAGE...VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24 HOURS...WITH STORM ACTIVITY DEVELOPING IN THE EDGE OF MID LEVEL CAPPING INVERSION OVER CENTRAL AND NORTHEAST MO. CLEAR SKIES AND DECREASING WINDS MAY ALLOW ENOUGH RADIATIONAL COOLING TO GET PATCHY MORNING FOG GOING. WILL MONITOR AND AMEND AS NEEDED IF FOG DEVELOPS. TERRY && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 259 PM MDT MON JUL 28 2008 .DISCUSSION... STORMS SLOW TO GET GOING TODAY ACROSS THE SOUTHERN TIER...MOST LIKELY DUE TO THE LOWER ATMOSPHERE GETTING WORKED OVER THE PREVIOUS DAY AND LEFT OVER CLOUD COVER THIS MORNING. REGARDLESS...LOOK FOR THUNDERSTORMS TO FILL IN OVER THE HIGHER TERRAIN AS THE AFTERNOON PROGRESSES. OF PARTICULAR CONCERN WILL BE THE RUIDOSO AREA AS PW/S REMAIN HIGH DOWN THAT WAY. ANY TYPE OF SUBSTANTIAL RAIN WILL EXASPERATE ALREADY WET CONDITIONS BUT TO THE RANDOM NATURE TO CELL FORMATION...DONT WANT TO ISSUE A FLASH FLOOD WATCH FOR LINCOLN COUNTY. THE MAIN FOCUS AREA FOR THE REST OF TODAY INTO THE OVERNIGHT WILL BE ACROSS THE NORTH. IR OVERLAID WITH RUC VORTICITY SHOWS A VORTICITY MAXIMA OVER THE FOUR CORNERS AREA AND WESTERN COLORADO. MODELS ARE IN FAIR AGREEMENT WITH TRANSLATING THIS FEATURE EAST/SOUTHEAST ACROSS CWFA. BEST CONCENTRATION OF STORMS WILL DEVELOP OUT AHEAD OF THIS FEATURE AND FAVOR NORTHERN AND EASTERN AREAS. INHERITED POPS REFLECTED THIS BUT ADJUSTED THEM SLIGHTLY BASED ON CURRENT FORECASTS AND ANTICIPATIONS. SEVERE WX POTENTIAL WILL BE ISOLATED DUE TO THE ENHANCED SHEAR FROM THE UPPER WAVE. OVERALL THEME THROUGH THE WORK WEEK WILL BE LESSENING COVERAGE ACROSS THE EAST AND TRANSFERRING TO THE WEST AS THE UPPER HIGH SETS UP OVER PORTIONS OF THE STATE. MODELS ARE IN FAIR AGREEMENT WITH THIS ASSESSMENT ALTHOUGH GFS LESS BULLISH ON OVERALL THUNDERSTORM COVERAGE THAN NAM. REALLY DEPENDS ON THE DRIER AIR INTRUSION FOLLOWING THE TRANSLATING WAVE TONIGHT AND TUESDAY. WE WILL NEED ANOTHER SIGNIFICANT MOISTURE INFLUX FROM EASTERN THE PLAINS...GULF OR BAJA/SONORA MEXICO BEFORE WE CAN GET BACK INTO WHAT WE HAVE HAD THE PAST 2 TO 3 WEEKS. IN THE MEANTIME WE WILL RECYCLE MOISTURE THAT WILL BE CAUGHT UNDERNEATH THE UPPER HIGH. ONE WILDCARD CONCERNS A BACK DOOR FRONT THAT IS DEPICTED TO FOCUS SOME ADDITIONAL THUNDERSTORMS ACROSS THE EAST ON TUESDAY AND TUESDAY NIGHT. WILDCARD WILL BE HOW MUCH MOISTURE CAN TRANSFER WESTWARD UNDER A GAP WIND SCENARIO ALONG THE CENTRAL MOUNTAINS. IF ENOUGH LOW LEVEL MOISTURE GETS PUSHED WESTWARD...THEN MAY DELAY HOW MUCH DRYING OUT OCCURS UNDERNEATH THE UPPER HIGH. ADJUSTED POPS A BIT DUE TO STEERING FLOW CONSIDERATIONS AND EXPECTATIONS UNDERNEATH THE UPPER HIGH. OVERALL THOUGH...INHERITED GRIDS LOOKED GOOD. WONT TOTALLY BUY OFF ON SIGNIFICANT DRYING IN HOPES THAT THERE WILL BE ENOUGH MOISTURE TRAPPED UNDERNEATH THE HIGH. && .AVIATION... EXPECTING VFR CONDITIONS ACROSS N AND CENTRAL NM NEXT 24 HOURS WITH THE EXCEPTION OF ISOLATED TO WIDELY SCATTERED BRIEF INSTANCES OF THUNDERSTORM CREATED MVFR AND IFR CONDITIONS DUE TO CIGS AND POSSIBLY RAIN REDUCED VISIBILITY. THUNDERSTORMS SHOULD DIMINISH IN THE WEST BY MIDNIGHT...BUT AN UPPER TROUGH CROSSING THE EAST SHOULD CAUSE ISOLATED SHOWERS AND THUNDERSTORMS TO PERSIST AFTER MIDNIGHT. EVEN FEWER TSRA EXPECTED MOST AREAS ON TUESDAY. CB IN TAFS WITHOUT TS OR VCTS INDICATES LOW PROBABILITY OF THUNDERSTORMS AND UNCERTAINTY ABOUT WHEN THEY MAY DEVELOP. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z. && .FIRE WEATHER... NORTH AND EAST SECTIONS OF FORECAST AREA FAVORED FOR SCATTERED TO ISOLATED THUNDERSTORMS INTO TONIGHT. THROUGH MID WEEK HIGH PRESSURE CENTER ALOFT SHOULD WOBBLE AROUND SW NM/SE AZ...WHICH WILL ALLOW DRIER AIR INTO THE STATE. LOWER MIN RH DAYTIME AND SLIGHTLY POORER RECOVERIES AT NIGHT. THUNDERSTORM WILL BECOME MUCH MORE ISOLATED TUESDAY ONWARD INTO THU OR FRI...THEN MAY INCREASE BY OR JUST AFTER THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 62 95 62 98 / 10 10 10 10 GALLUP.......................... 55 90 56 92 / 10 10 10 10 GRANTS.......................... 58 89 55 91 / 10 10 10 10 GLENWOOD........................ 62 94 60 97 / 10 10 10 10 CHAMA........................... 46 82 47 83 / 30 20 10 20 LOS ALAMOS...................... 56 87 57 88 / 20 20 20 20 RED RIVER....................... 47 77 43 79 / 30 20 20 20 TAOS............................ 53 89 51 89 / 30 20 20 20 SANTA FE........................ 57 90 60 89 / 20 20 20 20 SANTA FE AIRPORT................ 60 91 60 92 / 20 10 20 10 ESPANOLA........................ 59 96 58 95 / 20 20 20 20 ALBUQUERQUE HEIGHTS............. 67 93 68 94 / 10 10 10 10 ALBUQUERQUE VALLEY.............. 65 92 66 93 / 10 10 10 10 ALBUQUERQUE FOOTHILLS........... 63 92 63 93 / 10 10 10 10 ALBUQUERQUE WEST MESA........... 64 97 67 97 / 10 10 10 10 SOCORRO......................... 64 93 62 93 / 10 10 10 10 SANDIA PARK/CEDAR CREST......... 54 83 53 86 / 10 10 10 10 MORIARTY/ESTANCIA............... 57 89 55 89 / 20 20 20 30 CARRIZOZO....................... 61 93 60 93 / 10 10 20 20 RUIDOSO......................... 56 83 54 84 / 20 20 20 20 RATON........................... 57 88 54 90 / 40 40 10 30 LAS VEGAS....................... 58 85 56 88 / 30 40 20 40 ROY............................. 63 87 62 90 / 30 30 10 20 CLAYTON......................... 64 92 64 95 / 40 30 10 20 SANTA ROSA...................... 63 92 61 95 / 30 30 30 20 TUCUMCARI....................... 68 97 67 99 / 30 30 20 20 FORT SUMNER..................... 66 94 66 94 / 20 20 40 20 CLOVIS.......................... 67 96 67 96 / 20 20 40 20 PORTALES........................ 68 96 68 98 / 20 20 40 20 ROSWELL......................... 69 98 70 98 / 20 20 40 20 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 50/43 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 138 AM EDT MON JUL 28 2008 .SYNOPSIS... A WEAK COLD FRONT IS FORECAST TO MOVE EAST ACROSS THE AREA TONIGHT AND MONDAY MORNING WITH SCATTERED SHOWERS OR AN ISOLATED THUNDERSTORM. THE FRONT WILL BE FOLLOWED BY HIGH PRESSURE MONDAY NIGHT AND TUESDAY. ANOTHER BROAD AREA OF LOW PRESSURE IS FORECAST TO MOVE EAST FROM THE CENTRAL LAKES LATE TUESDAY NIGHT AND BRING MORE UNSETTLED WEATHER TO THE REGION FOR WEDNESDAY AND EARLY THURSDAY. ANOTHER HIGH IS FORECAST TO BUILD EAST ACROSS THE AREA ON FRIDAY AND SATURDAY. && .NEAR TERM /THROUGH TODAY/... MOISTURE CHANNEL IMAGERY SHOWING A SHORTWAVE STRETCHING FROM THE OTTAWA VALLEY TO CENTRAL LAKE ONTARIO AT 0130Z...EMBEDDED WITHIN A MORE BROAD MID LEVEL TROUGH WHICH WILL GRADUALLY DIG FROM THE CENTRAL GREAT LAKES THIS EVENING THROUGH THE SAINT LAWRENCE VALLEY ON MONDAY. SEVERAL MORE WEAK SHORTWAVES ARE FORECAST BY MODEL GUIDANCE TO ROTATE ACROSS NORTHERN SECTIONS OF THE REGION THROUGH MONDAY. WIDELY SCATTERED CONVECTION CONTINUES TO SLOWLY INCREASE FROM LAKE ONTARIO THROUGH THE SAINT LAWRENCE VALLEY WITHIN THE REGION OF LARGE SCALE FORCING FOR ASCENT AND LOW/MID LEVEL CONVERGENCE ASSOCIATED WITH THE SHORTWAVE AND ATTENDANT 40+KNOT 700MB SPEED MAX. A FEW OF THESE STORMS...INCLUDING ONE IN NORTHERN CAYUGA/SW OSWEGO COUNTIES AND THE STORM OVER LAKE ONTARIO OFFSHORE OF ROCHESTER HAVE COME VERY CLOSE TO BECOMING SEVERE. SPC OBJECTIVE RUC ANALYSIS SUGGESTING A RATHER MARGINAL THERMODYNAMIC ENVIRONMENT IN PLACE WITH SBCAPE OF 500-1000J/KG. WITH NOCTURNAL COOLING NOW UNDERWAY THE BOUNDARY LAYER WILL CONTINUE TO STABILIZE AND EXPECT UPDRAFT INTENSITY TO BEGIN TO WEAKEN SOMEWHAT OVER THE NEXT HOUR OR TWO...AND EFFECTIVE STORM INFLOW PARCELS ARE LIKELY TO BECOME ELEVATED OFF THE SURFACE AS BOUNDARY LAYER CONTINUES TO STABILIZE THIS EVENING. 0-6KM SHEAR IS ALSO RATHER WEAK WITH THE STRONGER WESTERLIES DISPLACED NORTH OF THE US/CANADIAN BORDER. THIS SHOULD PREVENT ANY ORGANIZED SEVERE WEATHER...ALTHOUGH CURRENT STRONG STORMS WILL BE MONITORED CLOSELY. 00Z SURFACE ANALYSIS SHOWING A WEAK SECONDARY COLD FRONT EXTENDING FROM EASTERN GEORGIAN BAY TO NEAR WINDSOR ONTARIO. SHORT TERM MODEL GUIDANCE SHOWS THIS FEATURE PUSHING EAST ACROSS THE LOWER GREAT LAKES LATE TONIGHT THROUGH MONDAY MORNING. AS THIS FRONT AND THE AFOREMENTIONED MID LEVEL TROUGH CROSS THE REGION...EXPECT MORE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP. HAVE CONTINUED WITH SAME BASIC IDEA IN THE GRIDS/ZFP...WITH THE GREATEST CHANCES ACROSS NORTHERN SECTIONS FROM THE SOUTH SHORE OF LAKE ONTARIO INTO THE SAINT LAWRENCE VALLEY CLOSER TO THE STRONGER MID LEVEL HEIGHT FALLS. THE LOWEST CHANCE OF RAIN WILL BE FOUND ALONG THE NY/PA STATE LINE. && .SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/... HIGH PRESSURE WILL FOLLOW THE PASSAGE OF THE FRONT WITH DRY AND CLEAR SKIES LATE MONDAY NIGHT AND FOR MUCH OF TUESDAY. MONDAY NIGHT WILL BE RATHER COOL AS DRIER AIR SPREADS ACROSS THE REGION...THE LOWS WILL FALL TO THE 50S WITH LOW 50S OVER THE SOUTHERN TIER AND THE VALLEYS NEAR THE FINGER LAKES. TUESDAY WILL HAVE ABUNDANT SUNSHINE AND HIGH TEMPS WILL REBOUND TO THE LOW 80S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... AN AREA OF LOW PRESSURE MOVES EAST FROM THE CENTRAL LAKES AND BRINGS A CHANCE OF SHOWERS AND THUNDERSTORMS LATE TUESDAY NIGHT THROUGH WEDNESDAY. I WENT WITH THE PLACEMENT AND TIMING OF THE PRECIP BASED MORE ON MEX AND SREF THAN USING THE GMOS POPS AND QPF...IT LOOKED MORE REALISTIC TO HAVE MORE QPF DURING WED AFTERNOON WHEN IT INTERCEPTS MORE WARMTH DURING THE DAY. A SECOND WAVE MOVES ALONG THE WEST TO EAST EXTENSION OF THE FRONT ON THURSDAY MORNING WHICH WILL KEEP CHANCE POPS OVER THE SOUTHERN TIER TO THE EASTERN LAKE ONTARIO REGION...THEN RIDGING ALOFT DEVELOPS BY FRIDAY MORNING. FRIDAY THROUGH SATURDAY, DRIER AIR SPREADS INTO THE REGION. MAX AND MIN TEMPS THROUGH THIS PERIOD WILL BE VERY CLOSE TO SEASONAL AVERAGES WITH HIGHS IN THE UPPER 70S TO LOW 80S AND LOWS FROM THE MID 50S TO LOW TO MIDDLE 60S. GFS DEVELOPS A DEEPENING UPPER LOW OVER THE CENTRAL GREAT LAKES ON SATURDAY AFTERNOON AND NIGHT WITH A SURFACE LOW LIFTING FROM SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA. THE GFS QPF IS WAY OVERDONE AT 06Z TO 12Z SUNDAY MORNING AND MAKES THIS 12Z GFS RUN A LITTLE SUSPECT...BUT WILL STILL GO WITH AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS ON SUNDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... ONCE AGAIN FOR THIS TAF CYCLE VFR CONDITIONS WILL PREVAIL BUT A MID LEVEL TROUGH WILL CONTINUE TO DIG FROM THE GREAT LAKES TO THE SAINT LAWRENCE VALLEY THROUGH TODAY WITH A COUPLE OF EMBEDDED SHORTWAVES TRAVERSING THE AREA. A WEAK SURFACE COLD FRONT WILL CONTINUE TO PUSH SLOWLY EAST ACROSS THE LOWER GREAT LAKES THROUGH THE FIRST HALF OF TODAY. THIS WEAK SURFACE FRONT COMBINED WITH THE MID LEVEL SHORTWAVES WILL PROVIDE ENOUGH CONVERGENCE AND FORCING FOR ASCENT TO PRODUCE A FEW SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE AREA...ESPECIALLY DURING THE BEST DIURNAL HEATING PERIOD. THE THREAT WILL CONTINUE THROUGH LATE TODAY. THE MID LEVEL TROUGH WILL TRANSLATE FURTHER EAST TONIGHT WITH A GRADUAL CLEARING TREND EXPECTED. CLEARING SKIES AND LIGHT WINDS WILL LIKELY EVENTUALLY LEAD TO FOG...ESPECIALLY ACROSS THE SOUTHERN TIER AFTER THIS TAF PERIOD. GIVEN THE HIGH DEGREE OF UNCERTAINTY WITH RESPECT TO TIMING AND PLACEMENT OF CONVECTION...WILL JUST USE VCSH QUALIFIERS FOR NOW WITH LITTLE IN THE WAY OF CONFIDENCE TO INCLUDE A CIG/VSBY RESTRICTION. WILL CONTINUE TO MONITOR RADAR/OBSERVATIONAL TRENDS AND AMEND AS NECESSARY. OUTLOOK... TUESDAY...VFR. WEDNESDAY...VFR/MVFR SCATTERED SHWRS/TSRA. THURSDAY...VFR. FRIDAY...VFR. && .MARINE... CHANNELLING OF SOUTHWEST WINDS UP LAKE ERIE HAVE DEVELOPED 3 TO 5 WAVES...SO WILL MAINTAIN SMALL CRAFT ADVISORY THROUGH THIS EVENING...THEN EXPECT WINDS AND WAVES TO SETTLE DOWN OVERNIGHT. ON LAKE ONTARIO WINDS AND WAVES ARE EXPECTED TO STAY BELOW SMALL CRAFT CRITERIA THROUGH MONDAY NIGHT. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...WCH NEAR TERM...HITCHCOCK SHORT TERM...WCH LONG TERM...WCH AVIATION...SAGE/HITCHCOCK MARINE...WCH ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 247 AM EDT MON JUL 28 2008 .SYNOPSIS... A LOW PRESSURE TROUGH WILL LINGER OVER CENTRAL NORTH CAROLINA THROUGH MIDWEEK. THIS TROUGH...COMBINED WITH PASSING UPPER LEVEL DISTURBANCES WILL CAUSE A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK. A STRONGER UPPER LEVEL SYSTEM...AND A WEAK COLD FRONT...ARE EXPECTED TO ENTER THE AREA ON THURSDAY...BRINGING WIDESPREAD SHOWERS AND STORMS TO THE AREA. && .NEAR TERM /THROUGH TUESDAY/... AS OF 925 PM MONDAY... CONVECTION OFF TO THE SOUTHWEST HAS BEEN TRYING TO PROPAGATE VIA SUCCESSIVE OUTFLOW BOUNDARIES NORTHWARD BUT HAS NOW BUCKED UP AGAINST THE STABLE TROF IN THE FOOTHILLS AND DO NOT EXPECT THIS ACTIVITY TO MAKE IT INTO THE SOUTHWEST CWFA. MEANWHILE...THE CONVECTION THAT CROSSED THE NORTHERN MOUNTAINS HAS EFFECTIVELY FIZZLED AS IT MADE IT TO THE FAR NORTHWEST PIEDMONT AS WELL. HAVE SEEN SOME RECOVERY IN THE AIRMASS IN THE WEST AS PROGGED BY RUC SOUNDINGS...AND EXPECT SOME MODEST INSTABILITY OVERNIGHT... ESPECIALLY IN THE EAST. WITH THE UPPER SHORT WAVE/VORT MAXIMA CONTINUING TO SAG SOUTHEAST OVERNIGHT...FEEL IT PRUDENT TO HAVE A SLIGHT CHANCE POP ACROSS THE AREA AFTER MIDNIGHT. WILL NOT INCLUDE THUNDER AT THIS TIME...BUT AN ISOLATED STORM IS POSSIBLE ACROSS THE SOUTHERN TIER AS WE WILL HAVE A RESIDUAL SEA BREEZE BOUNDARY IN THE SOUTHEAST AND PROBABLY SOME OUTFLOW INTERACTION FROM THE ONGOING CONVECTION IN THE FAR SOUTHWEST. FOR TUESDAY...MID LEVEL TROUGH DRIFTS EAST ACROSS FORECAST AREA. AGAIN, MODEL GUIDANCE ONLY DEPICTING WEAK CONFLUENCE ALONG FEATURE. HOWEVER WITH PRECIP WATER VALUES AROUND 1.8 INCHES...SURFACE LIFTED INDICES NEAR MINUS 3...COULD BE ENOUGH TO TRIGGER SCATTERED CONVECTION. FOR NOW WILL GO WITH A 30% POP. TEMP GUIDANCE VARIES ABOUT 10 DEGREES WITH THE DRIER MAV MUCH WARMER THAN WETTER ETA MOS. WENT WITH THICKNESS/TEMP SCHEME WHICH YIELD TEMPS IN THE LOW/MID 90S WITH FULL TO PARTIAL SUN. IF CLOUDS MORE EXTENSIVE (PER NAM)...THEN MAX TEMPS MAY NEED UP BEING ABOUT 5 DEGREES COOLER. -MLM && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 145 AM TUESDAY... WEDNESDAY AND WEDNESDAY NIGHT: SHORTWAVE RIDGING ALOFT WILL PASS OVER THE AREA WED MORNING...WITH FLOW ALOFT BECOMING UNIDIRECTIONAL BY AFTERNOON. THERE APPEARS TO BE NO APPRECIABLE WARMING FCST IN THE MID-LEVELS IN ASSOC/W THE SHORTWAVE RIDGE. SFC TROUGHING IS EXPECTED TO DEEPEN OVER THE AREA DURING THE DAY WED...IN ASSOC/W A SFC AND UPPER LEVEL LOW MOVING EAST ALONG THE UPPER GREAT LAKES. THE 00Z NAM IS MUCH WEAKER WITH THE TROUGHING OVER NC THAN THE GFS...THOUGH. EITHER WAY...BOTH THE NAM/GFS FCST SOUNDINGS ARE SHOWING PWAT VALUES IN THE 1.75-2.00" RANGE AND UP TO 2000 J/KG OF SFC BASED CAPE WITH SFC DEWPOINTS IN THE UPPER 60S TO LOWER 70S AND AFTERNOON TEMPS IN THE 90S. LOOKING AT THE GFS/NAM UPPER LEVEL PATTERN WED AFTERNOON...ANY SHORTWAVE DISTURBANCES ARE EXPECTED TO REMAIN NORTH IN THE OHIO VALLEY...SO UPPER LEVEL HELP LOOKS MINIMAL. WILL SHOW LOW CHANCE POPS (30%) ON WED AFTERNOON SINCE THIS IS CLOSE TO CLIMATOLOGY AND THE AIRMASS LOOKS REASONABLY UNSTABLE WITH LOW LEVEL CONVERGENCE IN ASSOC/W THE SFC TROUGH AS A FOCUS. HIGH TEMPS SHOULD BE SLIGHTLY ABOVE NORMAL... IN THE LOWER/MID 90S...BASED ON THICKNESSES. CANNOT RULE OUT A SLIGHT CHANCE OF SHOWERS/STORMS WED NIGHT WITH A VERY MOIST AIRMASS AND SFC TROUGHING STILL ACROSS THE AREA. IN FACT...A LARGE AREA OF CONVECTION SHOULD BE UPSTREAM OF THE AREA OVER THE TN VALLEY IN ASSOC/W OUR NEXT APPROACHING SHORTWAVE BY 12Z THU MORNING. LOW TEMPS IN THE UPPER 60S TO LOWER 70S. THURSDAY THROUGH FRIDAY: THE UPPER LEVEL PATTERN BECOMES MORE MERIDIONAL OVER THE MID-ATLANTIC AND CAROLINAS THURSDAY...AND A SOMEWHAT SHEARED OUT SHORTWAVE IS FCST TO CROSS THE AREA FROM THE NORTHWEST DURING THE AFT/EVE. ADDITIONALLY...WE SHOULD HAVE A SHARP SFC TROUGH ACROSS THE AREA IN ASSOC/W LOW PRESSURE IN NEW ENGLAND...IN ADDITION TO PWAT VALUES AROUND 2" AND SFC BASED CAPE VALUES IN THE 1500-2500 J/KG RANGE...DEPENDING ON CLOUD COVER AND TEMPS. AS SUCH...HAVE DECIDED TO KEEP A HIGH CHANCE (50%) OF SHOWERS/STORMS ACROSS THE ENTIRE AREA THROUGH MIDNIGHT FRIDAY MORNING. PRECIP CHANCES SHOULD BEGIN TO DECREASE FROM WNW TO ESE AFTER MIDNIGHT THROUGH SUNRISE FRIDAY MORNING AS DEEP UPPER LEVEL RIDGING OVER THE MIDWEST/ROCKIES BEGINS TO NOSE EAST TOWARD THE CAROLINAS...AND THE SFC TROUGH SHIFTS TOWARD THE COAST. THE NAM DELAYS THE RIDGE BUILDING INTO THE AREA A BIT COMPARED TO THE GFS...AND SHOWS ANOTHER SHORTWAVE DROPPING THROUGH THROUGH CENTRAL NC IN THE 06-15Z TIME FRAME FRIDAY MORNING...AND THIS WOULD ARGUE FOR KEEPING A LOW CHANCE OF POPS IN THE EAST THROUGH ABOUT NOON FRIDAY. HAVE DECIDED TO KEEP A SLIGHT CHANCE OF SHOWERS/STORMS IN THE SE COASTAL PLAIN UNTIL NOON FRIDAY TO ACCOUNT FOR THIS. OTHERWISE...WE SHOULD SEE A CLEARING TREND DURING THE DAY FRIDAY AS DEEP UPPER LEVEL RIDGING CONTINUES TO BUILD INTO THE AREA FROM THE WEST...WITH MID-LEVEL TEMPS WARMING CONSIDERABLY. ANY PRECIP CHANCES FRIDAY AFT/EVE SHOULD BE CONFINED TO THE IMMEDIATE COASTAL AREAS AND OFFSHORE. HIGH TEMPS ON THURSDAY SHOULD BE SHUNTED SOMEWHAT BY CLOUD COVER AND PRECIP...AND UPPER 80S TO LOWER 90S LOOK REASONABLE. LOW TEMPS THU NIGHT AROUND CLIMO IN THE UPPER 60S TO LOWER 70S. HIGH TEMPS ON FRIDAY WARMER IN THE LOWER/MID 90S WITH INCREASING THICKNESSES. -VINCENT && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AS OF 245 AM TUESDAY... THE CHANCE FOR WELL ABOVE-NORMAL TEMPERATURES IS INCREASING BY THE END OF THE WEEKEND INTO EARLY NEXT WEEK AS BOTH THE GFS/ECMWF ARE SHOWING THE DEEP UPPER LEVEL RIDGE OVER THE MIDWEST BUILDING OVER THE MID-ATLANTIC AND CAROLINAS ON SATURDAY...FURTHER STRENGTHENING OVER THE AREA ON SUN/MON. THE LATEST 00Z MEXMOS GUIDANCE IS SHOWING HIGH TEMPS IN THE MID TO UPPER 90S ON SAT/SUN/MON...WHICH SAYS SOMETHING SINCE THIS MOS GUIDANCE PRODUCT IS HEAVILY SKEWED TOWARDS CLIMATOLOGY AT THAT TIME RANGE...AND AVERAGE HIGHS THIS TIME OF YEAR ARE AROUND 89F. AT THIS TIME...WILL SHOW HIGH TEMPS INCREASING INTO THE MID 90S BY SUN/MON (94-97F RANGE). THERE IS STILL A GOOD DEAL OF UNCERTAINTY AT THIS TIME RANGE W/REGARDS TO THE EXACT POSITION AND STRENGTH OF THE UPPER LEVEL RIDGE...WHICH WILL ULTIMATELY DETERMINE HOW HOT WE GET. HOWEVER...BOTH THE GFS/ECMWF ARE SHOWING A VERY SIMILAR PATTERN... AND CONFIDENCE IS HIGH ENOUGH TO SHOW HIGH TEMPS AT LEAST IN THE ABOVE-NORMAL RANGE...IN THE MID 90S. WITH STRONG SUBSIDENCE ALOFT AND VERY WARM/DRY MID-LEVELS...EXPECT MOSTLY CLEAR/SUNNY SKIES ON SAT/SUN/MON WITH VERY LITTLE OR NO CHANCE OF ANY DIURNAL CONVECTION. -VINCENT && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 130 AM TUESDAY... AN AREA OF SHOWERS AND THUNDERSTORMS MOVED INTO THE WESTERN PIEDMONT OVER THE PAST FEW HOURS...RESULTING FROM PROPAGATING OUTFLOW BOUNDARIES AND A WEAK UPPER LEVEL SHORTWAVE. LATEST RADAR TRENDS INDICATE THIS ACTIVITY IS DIMINISHING AS THE BOUNDARY LAYER CONTINUES TO STABILIZE. THEREFORE...NOTHING MORE THAN LIGHT RAIN IS ANTICIPATED AT GSO/RDU THROUGH 08Z AND THIS ACTIVITY SHOULD NOT LOWER CONDITIONS BELOW VFR. OTHERWISE...MAINLY BROKEN MID LEVEL CONVECTIVE DEBRIS CLOUDS WILL AFFECT THE REGION THROUGH SUNRISE. THIS WILL LIKELY REDUCE THE FOG POTENTIAL AT THE TYPICALLY FOG PRONE SITES OF RWI/FAY... SO WILL ONLY GO WITH A BRIEF PERIOD OF LIGHT MVFR FOG AROUND SUNRISE. CONVECTIVE POTENTIAL DURING THE DAY TODAY REMAINS UNCERTAIN. DEEP LAYER MOISTURE WILL BE BETTER TODAY AS COMPARED TO YESTERDAY...THUS INSTABILITY PARAMETERS WILL BE HIGHER. OVERALL...FORCING IS VERY WEAK IN THE LOW LEVELS WITH ONLY A WEAK MID LEVEL TROUGH PRESENT ALOFT. THEREFORE...COVERAGE IS NOT ANTICIPATED TO BE HIGH ENOUGH TO INCLUDE A MENTION IN THE TERMINALS AT THIS TIME. OUTSIDE OF CONVECTION...VFR CONDITIONS WILL PERSIST THROUGH TONIGHT WITH PERHAPS SOME SUNRISE FOG AT RDU/RWI/FAY WEDNESDAY MORNING. DIURNAL CONVECTIVE POTENTIAL INCREASES SLIGHTLY ON WEDNESDAY AS DEEP LAYER MOISTURE CONTINUES TO RISE. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS APPEARS TO BE ON THURSDAY AS A STRONG MID LEVEL TROUGH AND SFC BOUNDARY APPROACH THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...MLM SHORT TERM...VINCENT LONG TERM...VINCENT AVIATION...JFB nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 935 PM EDT MON JUL 28 2008 .SYNOPSIS... A LOW PRESSURE TROUGH WILL HOLD STATIONARY OVER COASTAL NORTH CAROLINA THROUGH TODAY... THEN SHIFT BACK WESTWARD THROUGH THE PIEDMONT TONIGHT... WHERE IT WILL REMAIN THROUGH TUESDAY. THIS WILL KEEP A WARM AND HUMID AIR MASS OVER THE REGION INTO MIDWEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 925 PM MONDAY... CONVECTION OFF TO THE SOUTHWEST HAS BEEN TRYING TO PROPAGATE VIA SUCESSIVE OUTFLOW BOUNDARIES NORTHWARD BUT HAS NOW BUCKED UP AGAINST THE STABLE TROF IN THE FOOTHILLS AND DO NOT EXPECT THIS ACTIVITY TO MAKE IT INTO THE SOUTHWEST CWFA. MEANWHILE...THE CONVECTION THAT CROSSED THE NORTHERN MOUNTAINS HAS EFFECTIVELY FIZZLED AS IT MADE IT TO THE FAR NORTHWEST PIEDMONT AS WELL. HAVE SEEN SOME RECOVERY IN THE AIRMASS IN THE WEST AS PROGGED BY RUC SOUNDINGS...AND EXPECT SOME MODEST INSTABILITY OVERNIGHT... ESPECIALLY IN THE EAST. WITH THE UPPER SHORT WAVE/VORT MAXIMA CONTINUING TO SAG SOUTHEAST OVERNIGHT...FEEL IT PRUDENT TO HAVE A SLIGHT CHANCE POP ACROSS THE AREA AFTER MIDNIGHT. WILL NOT INCLUDE THUNDER AT THIS TIME...BUT AN ISOLATED STORM IS POSSIBLE ACROSS THE SOUTHERN TIER AS WE WILL HAVE A RESIDUAL SEA BREEZE BOUNDARY IN THE SOUTHEAST AND PROBABLY SOME OUTFLOW INTERACTION FROM THE ONGOING CONVECTION IN THE FAR SOUTHWEST. FOR TUESDAY...MID LEVEL TROUGH DRIFTS EAST ACROSS FORECAST AREA. AGAIN, MODEL GUIDANCE ONLY DEPICTING WEAK CONFLUENCE ALONG FEATURE. HOWEVER WITH PRECIP WATER VALUES AROUND 1.8 INCHES...SURFACE LIFTED INDICES NEAR MINUS 3...COULD BE ENOUGH TO TRIGGER SCATTERED CONVECTION. FOR NOW WILL GO WITH A 30% POP. TEMP GUIDANCE VARIES ABOUT 10 DEGREES WITH THE DRIER MAV MUCH WARMER THAN WETTER ETA MOS. WENT WITH THICKNESS/TEMP SCHEME WHICH YIELD TEMPS IN THE LOW/MID 90S WITH FULL TO PARTIAL SUN. IF CLOUDS MORE EXTENSIVE (PER NAM)...THEN MAX TEMPS MAY NEED UP BEING ABOUT 5 DEGREES COOLER. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 215 PM MONDAY... FOR TUESDAY NIGHT: THE MID LEVEL VORTICITY AXIS IS EXPECTED TO DROP JUST SOUTHEAST OF CENTRAL NC BY TUESDAY EVENING... AND THE HIGHER POPS SHOULD ACCOMPANY THE POSITIVE VORTICITY ADVECTION HEADING OUT OF THE CWA... WITH MID LEVEL RIDGING NOSING IN FROM THE SOUTHWEST. FORECAST SOUNDINGS OVER THE NORTHWEST HALF OF THE CWA SHOW A SUBSIDENCE LAYER ALOFT. HOWEVER... WITH THE PERSISTENCE OF THE SURFACE-850 MB TROUGH THROUGH THE WESTERN PIEDMONT AND THE POTENTIAL HIGH MODEL TIMING ERRORS WITHIN THIS VERY WEAK FLOW REGIME... WILL HOLD ONTO ISOLATED POPS THROUGH TUESDAY NIGHT... ON THE HIGHER END OVER THE SOUTHEAST CWA WHERE PROJECTED PRECIPITABLE WATER APPROACHES 150% OF NORMAL. LOWS 68-74 LOOK REASONABLE WITH PARTLY CLOUDY SKIES. FOR WEDNESDAY: IN THE WAKE OF THE MID LEVEL TROUGH AXIS WEAKENING AND SHIFTING OFFSHORE... VAGUELY ZONAL OR SLIGHTLY CYCLONIC MID LEVEL FLOW ACROSS THE OHIO VALLEY AND MIDATLANTIC REGION AND ITS SUBTLE PERTURBATIONS MAKE FOR AN INCREASINGLY DIFFICULT FORECAST. IT APPEARS LIKELY THAT THE LEESIDE SURFACE TROUGHING WILL HOLD NEARLY STATIONARY THROUGH THE WESTERN CWA THROUGH WEDNESDAY WITH THE SYNOPTIC FRONT HOLDING TO OUR NW THROUGH VA INTO NE TN AND BACK THROUGH WRN KY. HOWEVER THE MODELS DO NOT AGREE ON THE AMOUNT OF MOISTURE AVAILABLE. THE GFS BUILDS A PRECIPITABLE WATER NEARLY 2.25 INCHES THROUGH THE CWA... WHEREAS THE NAM SHUNTS THIS HIGHER MOISTURE TO THE SOUTHEAST CORNER OF THE CWA WITH PW VALUES ONLY NEAR AN INCH IN WESTERN NC. BOTH MODELS CONFINE THE MEASURABLE PRECIP TO THE SOUTHEAST COUNTIES WHERE INSTABILITY IS BEST WITH A LIFTED INDEX NEAR -4. WHILE THIS IS THE MOST PROBABLE SPOT TO SEE CONVECTION CLIMATOLOGICALLY-SPEAKING... WITH THE UNCERTAINTY IN THE FORCED ASCENT CONTRIBUTIONS FROM THESE PERTURBATIONS ALOFT... WILL KEEP A SMALL PRECIP CHANCE IN THE FORECAST ELSEWHERE TOO. CLOUDS SHOULD BE A MIX OF MID AND HIGH CONVECTIVE DEBRIS CLOUDS WITH INCREASING CONVECTIVE CLOUDS DURING THE AFTERNOON. LOW LEVEL THICKNESSES INDICATE HIGHS IN THE MID TO UPPER 90S WHICH IS CLOSE TO GFS MOS GUIDANCE... HOWEVER WITH AT LEAST SOME CLOUD COVER THROUGH THE DAY AND FACTORING IN THE TENDENCY IN RECENT WEEKS FOR THE GFS MOS GUIDANCE TO BE TOO HIGH ON THESE ANOMALOUSLY WARM DAYS... HAVE TRENDED DOWN A BIT FROM THESE NUMBERS... TO 92-96. FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: A MID LEVEL VORTEX OVER CENTRAL ONTARIO WOBBLES SOUTHEASTWARD THROUGH SOUTHERN QUEBEC... RECARVING A MEAN TROUGH TO THE SSW DOWN THE WEST SLOPES OF THE APPALACHIANS. THE REMNANT MOISTURE AND VORTICITY FROM DOLLY IS EXPECTED TO SWING THROUGH THE BASE OF THIS TROUGH... REACHING VA/NC DURING THE DAY THURSDAY. OF COURSE THERE IS SOME UNCERTAINTY REGARDING SPECIFIC TIMING... AND THIS UNCERTAINTY IS AMPLIFIED BY CONVECTIVE FEEDBACK ON THE GFS... BUT IT APPEARS THAT THE BEST CHANCE FOR RAIN DURING THIS FORECAST WILL BE THURSDAY INTO THURSDAY EVENING AS THE MID LEVEL TROUGH AXIS SWINGS THROUGH WITH MID LEVEL LAPSE RATES STEEPENING TO OVER 6 C/KM... NAM-INDICATED SURFACE CAPE RISING TO 2000+ J/KG... AND PRECIPITABLE WATER NEARING 170% OF NORMAL. THIS SCENARIO TIMING IS PRETTY WELL AGREED UPON BY THE LATEST NAM/ECMWF/CANADIAN. HAVE RAISED POPS A BIT TO THE 42-50% RANGE INTO THURSDAY EVENING. EXPECT PARTLY CLOUDY SKIES WEDNESDAY NIGHT... BECOMING MOSTLY CLOUDY THURSDAY INTO THURSDAY NIGHT... WHICH SHOULD NARROW THE DIURNAL TEMPERATURE DIFFERENCE AND PRODUCE MILD LOWS OF 69-74 WEDNESDAY NIGHT. THICKNESSES ARE HIGHLY VARIED AMONG THE MODELS FOR THURSDAY BUT LEAN SLIGHTLY ABOVE NORMAL... SO WILL KEEP HIGHS FAIRLY CLOSE TO NORMAL... 88-93... GIVEN THE WARM AIR ADVECTION AND CLOUD COVER. THE MID LEVEL TROUGH AXIS DROPS TO OUR SOUTHEAST THURSDAY NIGHT AND WE SHOULD SEE A TAPERING OFF OF RAIN CHANCES NW TO SE OVERNIGHT WITH PARTIAL CLEARING CLOSE ON ITS HEELS. LOWS 67-73. -GIH && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 255 PM MONDAY... FOR FRIDAY: THE MID LEVEL TROUGH AND ACCOMPANYING SURFACE FRONT WILL PUSH INTO SOUTHEAST NC BY FRIDAY MORNING... BRINGING AN END TO RAIN CHANCES OVER ALL BUT THE SOUTHEAST COUNTIES... WHERE A LOW CHANCE POP WILL BE RETAINED NEAR THE FRONT. WILL HAVE A DECREASE IN CLOUDS OVER NORTHERN AND WESTERN SECTIONS WITH HIGH PRESSURE CENTERED IN THE OHIO VALLEY BEGINNING TO BUILD IN. HIGHS 89-93. FOR FRIDAY NIGHT THROUGH MONDAY: THE GENERAL TREND THROUGH THE WEEKEND IS FOR A STRONG HOT RIDGE TO BUILD OVER THE MID SECTION OF THE COUNTRY... WITH A BAGGY TROUGH FROM SOUTHEAST CANADA THROUGH COASTAL NC INTO THE INTERIOR SOUTHEAST. FORECAST SOUNDINGS INDICATE MID LEVEL SUBSIDENCE AND VERY DRY AIR IN PLACE SATURDAY THROUGH SUNDAY... WITH ONLY MARGINAL INSTABILITY AT MOST INDICATED BOTH AFTERNOONS. EXPECT ABOVE-NORMAL HIGHS BOTH DAYS... AROUND 90-95. THE GFS SHOWS THE RIDGE SLIDING IN THE OHIO VALLEY AND EXPANDING IN A WEST-TO-EAST FASHION... WHICH SHOULD ENSURE THE CONTINUED DRY AND WARM WEATHER INTO NC. HIGHS SHOULD CONTINUE ABOVE NORMAL... 90-95. -GIH && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 830 PM... BAND OF SHOWERS WEAKENING AS IT ADVANCES TOWARD THE WESTERN PIEDMONT AND DRIER MORE STABLE AIR. NOT YET COMPLETELY CONVINCED THERE WILL BE MUCH MORE THAN VFR CEILINGS AND ISOLATED VERY LIGHT SHOWERS BY THE TIME THIS BAND REACHES HIGHWAY ONE. A WEAK MID LEVEL TROUGH HELPING TO SUPPORT RAIN CHANCES FLATTENS AND WEAKENS AFTER SUNRISE TUESDAY TO BE NO MORE THAN ABOUT THIRTY PERCENT FROM MIDNIGHT THROUGH THE REMAINDER OF THE DAYLIGHT HOURS TUESDAY. VFR CEILINGS AND VISIBILITIES OUTSIDE SHOWERS WITH THE EXCEPTION OF ROCKY MOUNT AND FAYETTEVILLE WHERE MVFR FOG OR HAZE IS POSSIBLE UNTIL MID MORNING. FOR WEDNESDAY AND THURSDAY...EXPECT A PERIOD OF UNSETTLED WEATHER WITH EXTENDED PERIODS OF MVFR DUE TO CEILINGS. WILL SEE OCCASIONS WHEN SHOWERS AND STORMS COVERAGE WILL BE 50 PERCENT. APPEARS THAT CHANCES FOR CONVECTION WILL DECREASE FRIDAY INTO SATURDAY AS HIGH PRESSURE WILL BUILD EAST INTO THE REGION FROM THE OHIO VALLEY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...MLM SHORT TERM...HARTFIELD LONG TERM...HARTFIELD nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 739 PM EDT MON JUL 28 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO COVER THE REGION THIS WEEK. THE FOCUS OF SHOWER AND THUNDERSTORM ACTIVITY WILL BE ALONG THE SEA BREEZE AND A TROUGH OF LOW PRESSURE OVER THE PIEDMONT EACH AFTERNOON. A COLD FRONT WILL APPROACH THE REGION THIS WEEKEND BEFORE STALLING NEAR THE AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...CU DEVELOPMENT HAS BEEN CONCENTRATED ALONG THE SEA BREEZE AND SOUTHEAST OF A TROUGH WHICH MOVED INTO OUR LOCAL AREA THIS MORNING. ISOLATED SHOWERS/TSTMS DEVELOPING ALONG AND EAST OF SEA BREEZE AND TROUGH BOUNDARY. DRIER AIR HAS MIXED DOWN ACROSS INLAND AREAS WITH SHARP GRADIENT EXISTING BETWEEN INLAND DEWPOINT TEMPS WHICH DROPPED DOWN TO THE LOWER TO MID 60S AND COASTAL AREAS WHERE DEWPOINTS HAVE MAINTAINED THEMSELVES IN THE LOWER TO MID 70S. RUC SHOWING BEST INSTABILITY OVER GEORGETOWN AND WILLIAMSBURG COUNTIES WHICH LINES UP NICELY WITH CONVECTIVE DEVELOPMENT THIS AFTERNOON. MODEL SOUNDINGS STILL SHOWING MORE STABLE CONDITIONS FOR LATER THIS AFTERNOON WITH K INDEX VALUES DECREASING TO THE TEENS AND CAPE AND LI VALUES TRENDING TOWARD LESS CONVECTIVE POTENTIAL THROUGH THIS AFTERNOON. ALSO OVERALL MOISTURE DOWN TO AROUND 1.5 INCHES OR LESS THIS AFTERNOON ACROSS MOST OF THE AREA. THEREFORE EXPECT CONVECTION TO DIE DOWN FAIRLY RAPIDLY THIS AS FOR TONIGHT SURFACE TROUGH SHOULD MOVE BACK INLAND WITH RETURN OF HIGHER DEWPOINT AIR INLAND. PUSHED TEMPS UP SLIGHTLY INTO THE MID 70S MOST PLACES. EXPECT TO SEE SOME PATCHY FOG..ESPECIALLY IN AREAS WHERE PCP OCCURRED THIS AFTERNOON. SHORTWAVE WILL TRAVERSE THE AREA...BUT WILL REMAIN MAINLY NORTH...THEREFORE WENT MORE WITH DIURNAL TREND OF BEST CHC OF SHOWERS/TSTMS OFF SHORE IN THE COASTAL WATERS. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...FAIRLY TYPICAL JULY WEATHER TO CONTINUE WITH THE PIEDMONT TROUGH MAINTAINING ITSELF INLAND WITH BERMUDA HIGH PRESSURE RIDGING INTO THE AREA FROM THE EAST. MODELS DIFFER ON UPPER LEVEL SUPPORT IN TERMS OF TIMING AND INTENSITY OF SHORT WAVES BUT THERE SHOULD BE SUFFICIENT MOISTURE AND LIFT AROUND FOR ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS EACH DAY. INITIATION IS EXPECTED TO OCCUR ON THE SEA BREEZE AND PIEDMONT TROUGH. MAX TEMPERATURES EACH DAY WILL BE IN THE LOW TO MID 90S AWAY FROM THE BEACHES WITH MINS EACH NIGHT IN THE LOW TO MID 70S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...5H TROFFING OVER THE E COAST AT THE BEGINNING OF THE PERIOD WILL EVENTUALLY PUSH A COLD FRONT/SFC TROF OFF THE COAST. BEST GUESS ON TIMING AT THIS POINT IS LATE FRI/EARLY SAT. AHEAD OF THE FRONT ENVIRONMENT REMAINS VERY MOIST WITH SEA BREEZE AND PIEDMONT TROF BOTH EXPECTED TO GENERATE CONVECTION. HOLDING ONTO LOW CHANCE POPS UNTIL AFOREMENTIONED FRONT PUSHES OFF THE COAST. FRONT WILL NOT GET VERY FAR OFF THE COAST BEFORE STALLING OUT SAT INTO SUN. GFS DEVELOPS 3 SEPARATE WAVES/LOWS ALONG THE BOUNDARY...BUT THIS SEEMS UNREALISTIC. THINK THE 00Z ECMWF IDEA OF ONE LOW DEVELOPING OVER THE NRN GOMEX IS THE RIGHT SOLUTION. THE LOW MOVES WNW AS 5H RIDGE OVER THE CENTRAL PLAINS BUILDS W. 7H RIDGE ALSO BUILDING IN FROM THE CENTRAL PLAINS WILL KEEP THE FRONT OFFSHORE WITH DRIER AIRMASS AND MID LEVEL CAPPING. DROPPED POPS TO SLIGHT CHANCE SAT AND BEYOND. TEMPS NEAR TO SLIGHTLY ABOVE CLIMO THROUGH THE PERIOD. && .AVIATION /0Z TUESDAY THROUGH SATURDAY/... SOME MID AND HIGH CLOUDS POSSIBLE EARLY TONIGHT FROM THUNDERSTORMS THAT FORMED EARLIER TODAY. BY 06Z MORE MID AND HIGH LEVEL CLOUDS WILL SPREAD EAST AHEAD OF A CLUSTER OF STORMS ACROSS TN AND WESTERN NC. SOME MVFR VISIBILITY RESTRICTIONS POSSIBLE AFTER 09Z...WITH THE BEST BET COMING AT THE INLAND TERMINALS. WINDS WILL BE LIGHT TONIGHT OUT OF THE SOUTHWEST...TO NEAR CALM INLAND. ON TUESDAY OUR CHANCES FOR PRECIPITATION INCREASE...ESPECIALLY INLAND. THE 18Z NAM SEEMS TO HAVE AN EXCELLENT HANDLE ON A H5 SHORTWAVE CURRENTLY ACROSS CENTRAL TN/KY. THIS SHORTWAVE WILL BRING SOME PVA TO THE INLAND TERMINALS AFTER 17Z TUESDAY...INCREASING THE CHANCES FOR SHOWERS/THUNDERSTORMS. IT APPEARS THE BEST MOISTURE AND LIFT WILL BE BETWEEN 21Z AND 03Z. SOME IFR CONDITIONS ARE POSSIBLE DUE TO HEAVY RAIN. CLOSER TO THE COAST ASIDE FROM SOME CU ALONG THE RESULTANT SEA BREEZE WE SHOULD REMAIN DRY. THE H5 TROF MENTIONED ABOVE APPROACHES BY AFTERNOON. THE LIMITING FACTOR WILL BE THE LACK OF MOISTURE AS NAM 1000-500 MB MOISTURE PROFILES SHOW AN AXIS OF DRY AIR RIGHT ALONG THE COAST. AS FAR AS WINDS GO TUESDAY THEY SHOULD BE OUT OF THE SOUTHWEST AT LESS THAN 10 KNOTS. AT THE COASTAL TERMINALS SOUTHWEST WINDS WILL SHIFT INTO THE SOUTH BETWEEN 17Z AND 18Z AND BECOME GUSTY AS THE RESULTANT SEA BREEZE MOVES INLAND. OUTLOOK THROUGH SATURDAY...THE PIEDMONT TROF ALONG WITH THE DAILY SEA BREEZE WILL BE THE FOCUS OF ISOLATED TO SCATTERED CONVECTION EACH AFTERNOON. BY THE END OF THE WEEK A COLD FRONT WILL SETTLE ACROSS THE AREA...PROVIDING MORE CHANCES FOR CONVECTION. IFR CONDITIONS ARE POSSIBLE DUE TO HEAVY RAIN...BUT THE CONDITIONS WILL BE BRIEF IN DURATION. VISIBILITY CONCERNS POSSIBLE PRIOR TO DAWN IN AREAS THAT SEE RAIN THE DAY BEFORE. MOST OF THIS PERIOD OUTSIDE OF THE AFTERNOON/EARLY MORNING WILL BE VFR. $$ .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...HIGH PRESSURE OFFSHORE AND LINGERING TROUGH OVER COASTAL CAROLINAS WHICH PUSHES BACK INLAND AND MAINLY REMAINS AS PERSISTENT TROUGHINESS OVER THE PIEDMONT AREA OF THE CAROLINAS. COMBINATION OF THESE TWO FEATURES WILL KEEP UP A SWLY FLOW OVER THE COASTAL WATERS. GUIDANCE PINCHES GRADIENT A BIT THIS EVENING...BUT WINDS WILL STAY IN THE 10 TO 15 KT RANGE. SEAS 2 TO 3 FT THROUGH TONIGHT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...THE TROUGH INLAND AND HIGH PRESSURE OFFSHORE WILL MAINTAIN S TO SW FLOW THROUGH THE PERIOD WITH SPEEDS RUNNING 15 KT OR LESS. SEAS ARE EXPECTED TO BE 4 FT OR LESS. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 PM MONDAY...SRLY FLOW CONTINUES THROUGH THE PERIOD...THOUGH WEAK COLD FRONT/SFC TROF MAY CROSS THE WATERS SAT. FRONT/TROF IS WEAK...SO IMPACT ON GRADIENT WILL BE LIMITED WITH SPEEDS INCREASING BY ONLY A FEW KTS. POST FRONT WINDS WOULD BECOME NRLY BUT TIMING OF FRONT REMAINS QUESTIONABLE. SEAS WILL RUN 2 TO 4 FT THROUGH THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...31 NEAR TERM...RGZ SHORT TERM...31 LONG TERM...III AVIATION...HEDEN nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 933 PM CDT TUE JUL 29 2008 .UPDATE... THINGS STILL LOOK ON TRACK FOR CURRENT FCST. NOT ENTIRELY SOLD ON THE SLGHT CHC TSRA WE HAVE GOING FOR THE WRN CWA AFT 06Z...BUT LATEST RUC13/NAM12 WANTS TO DEVELOP SOME LIGHT QPF IN THE KPIR AREA BY 12Z WITH THE WAA REGIME SETTING UP OUT WEST. GIVEN THAT BOTH ARE SHOWING FAIRLY HEALTHY 7H THETA-E RIDGES MOVING INTO THE MO RIVER COUNTIES...CAN`T REALLY ARGUE AGAINST IT. CURRENT TEMPS ALSO LOOK GOOD...WITH HOURLY TEMP ADJUSTING ONLY NEEDED. ALSO TWEAKED CLOUD COVER TO REFLECT CLEAR SKIES ACROSS THE EAST...AND PLANNED WAA MID-CLOUD DEVELOPMENT ACROSS THE WEST. NO PLANNED UPDATE TO WORDED ZONE FCST ATTM. UPDATED AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT PCPN CHANCES AND TEMPERATURES ARE THE MAIN QUANDARY THROUGH THE MEDIUM RANGE. FOR TNT SFC HIGH WILL DRIFT OFF TO THE EAST WITH RETURN FLOW SETTING UP OVER THE WESTERN DAKOTAS. SOME ENERGY DOES COME OUT OF THE ROCKIES AND MODELS HINT AT SOME ACCAS THUNDER OVER WESTERN OR FAR SOUTHWESTERN CWA AS ELEVATED INSTABILITY ADVECTS BACK NORTH INTO THE WESTERN CWA VIA LLJ. WILL KEEP SLIGHT CHANCE POPS GOING OVER THESE REGIONS. THEN FOR WED THROUGH THURSDAY SFC LOW FORMS OVER CENTRAL PART OF STATE WITH WARM FRONTAL BOUNDARY DEVELOPING EAST FROM THIS LOW INTO MINNESOTA. ANYTIME A WARM FRONT IS HANGING AROUND IT IS HARD TO IGNORE POTENTIAL PCPN CHANCES. HOWEVER...A BIG PROBLEM COULD BE THE ELEVATED MIXED LAYER THAT GRADUALLY ADVECTS EASTWARD ACROSS CWA...THUS PROVIDING SOME CAPPING. NONETHELESS FEEL IT IS STILL A GOOD IDEA TO KEEP POPS IN THE FORECAST...ESPECIALLY THE NORTHEAST CWA WHERE CONVECTIVE INHIBITION BOTH LATE WED AND LATE THUR WILL BE THE WEAKEST. MODELS ALSO HINT AT A COUPLE CONVECTIVE COMPLEXES POSSIBLY DROPPING THROUGH OR INTO THAT AREA. AS FOR TEMPERATURES...AFOREMENTIONED WARM FRONT WILL PLAY A ROLE IN TEMPERATURES. WITH IT HANGING OUT TO THE SOUTH OF THE NORTHERN CWA SHOULD BE THE COOLEST WITH AN EASTERLY SFC FLOW AND MORE MOISTURE IN THE BOUNDARY LAYER. H85 TEMPS HEADED WELL INTO THE 20+ C RANGE BEG FOR SOME NEAR 100 DEGREE READINGS AT KPIR. HOWEVER RECENT RAINS HAVE GREENED UP THE REGION IN THE LAST COUPLE WEEKS WHICH IS HELPING HOLD DOWN BOUNDARY LAYER MIXING. SO...BECAUSE OF THIS WILL KEEP TEMPS A TAD UNDER VERY WARM MAV PROGNOSTICATIONS. .LONG TERM...FRIDAY THROUGH TUESDAY MAIN FORECAST CHALLENGE WILL BE THE TEMPERATURE TRENDS AS UPPER FLOW DOMINATED BY FOUR CORNERS HIGH TRANSITIONS EAST. DESPITE THE TRANSITION...UPPER FLOW REMAINS ZONAL WITH SERIES OF WAVES...THE MOST POTENT IS EXPECTED TO TRAVERSE NORTHER TIER CONUS SATURDAY. H7 TEMPERATURES ARE FAIRLY STABILIZING...WITH LOW TEENS TO START PERIOD...AND INTO UPPER TEENS SATURDAY. THE RESULT...AN UNEVENTFUL SURFACE TROUGH PASSAGE MARKED BY MERE CHANGE IN HUMIDITY/WIND DIRECTION. MAIN EFFECT IS FORECAST MAX TEMPS FRIDAY/SATURDAY...WITH MEX GUIDANCE EXCEEDING CENTURY MARK IN WESTERN COUNTIES FRIDAY/SATURDAY. WITH RECENT RAINFALL AND CONTINUED GREEN CONDITIONS...AS WELL AS A CLIMATOLOGICALLY UNFAVORABLE WIND DIRECTION...WILL GO BELOW GUIDANCE THOSE DAYS. SLIGHTLY COOLER H7 TEMPERATURES ARE LESS INHIBITING SUNDAY INTO START OF NEXT WEEK. PREVIOUSLY MENTIONED SURFACE FRONT NOW EXPECTED TO HANG UP ACROSS SOUTH DAKOTA SUNDAY INTO THE START OF NEXT WEEK...SO HAVE INCREASED POPS DAYS 5 THRU 7 TO SLIGHT/CHANCE. && .AVIATION... VFR CONDS EXPECTED ACROSS ALL TERMINAL SITES THROUGH 00Z THURSDAY. SOME FEW-SCT120 CONDS MAY DEVELOP AFT 10Z THROUGH 15Z. P6SM VSBYS ALSO EXPECTED THROUGH DURATION OF VALID TAFS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...HINTZ SHORT TERM...TDK LONG TERM...CONNELLY AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LUBBOCK TX 1024 AM CDT TUE JUL 29 2008 .UPDATE... TRAILING LINE OF OVERNIGHT MCS IS SLOWLY EXITING THE FA...EXPECT IT TO BE EAST OF STONEWALL COUNTY BY AROUND 1100 AM. HAVE LOWERED/REMOVED POPS FROM THE REMAINDER OF THE FA THROUGH 18Z/1 PM. FAIRLY THICK CLOUD SHIELD SHOULD BE SLOW TO DISSIPATE ACROSS THE ROLLING PLAINS...AND HAVE CONSERVATIVELY LOWERED HIGH TEMPS ABOUT 3-5 DEGREES FOR THAT AREA THIS AFTERNOON...BACKING OFF FROM THE 101-105 RANGE DOWN TO ABOUT 98-101. SFC OBS SHOW ANOTHER FRONT/OUTFLOW SURGE MOVING SOUTH THROUGH THE OKLAHOMA AND NRN TX PANHANDLE AT 10 AM. HAVE UPDATED THE WIND GRIDS WITH LATEST RUC/NAM GUIDANCE THAT SHOW THIS NORTHERLY WIND SHIFT PROGRESSING THROUGH THE FA TODAY /LEADING SURGE HAS ALREADY GONE THROUGH THE WESTERN SPLNS/. THE RUC REDEVELOPS CONVECTION ALONG THE BOUNDARY THIS AFTERNOON ACROSS OUR NORTH-CENTRAL ZONES WHEREAS THE LATEST WRF/NAM INDICATES DEVELOPMENT A LITTLE BIT LATER AND A BIT FARTHER TO THE SOUTH AND EAST. FINALLY...THE VIS SAT LOOP SHOWS LOW CLOUD COVER INCREASING FROM THE EASTERN PANHANDLE INTO THE NRN SPLNS AND ROLLING PLAINS. CLOUD COVER SHOULD PLAY A KEY ROLE IN DESTABILIZATION THIS AFTN...CREATING SOME UNCERTAINTY IN CONVECTIVE POTENTIAL. WITH THIS IN MIND WILL RETAIN CURRENT POP CONFIGURATION AND WILL WATCH FOR REDEVELOPMENT LATER THIS AFTERNOON IN AREAS WITH BEST HEATING CO-LOCATED WITH LIFT FROM APPROACHING BOUNDARIES PLUS ANY RESIDUAL OUTFLOW BOUNDARIES LEFT FROM OUR EARLIER STORMS. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 93 66 94 66 95 / 20 30 20 10 0 TULIA 93 67 92 67 94 / 30 30 20 10 0 PLAINVIEW 95 68 93 68 93 / 30 30 20 10 0 LEVELLAND 98 69 95 70 96 / 20 30 20 10 0 LUBBOCK 98 71 95 71 95 / 30 30 20 20 0 DENVER CITY 97 71 98 71 96 / 20 30 30 20 0 BROWNFIELD 97 70 96 71 95 / 20 30 30 20 0 CHILDRESS 99 73 95 72 98 / 30 30 20 20 0 SPUR 98 70 96 73 96 / 20 30 30 20 10 ASPERMONT 101 72 97 74 98 / 30 30 30 20 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 33 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1122 PM CDT MON JUL 28 2008 .DISCUSSION... SEE THE DISCUSSION FOR THE UPCOMING 06Z TAF FORECAST BELOW. && .AVIATION... VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24 HOURS. WINDS WILL BE SOUTH AT AROUND 10 KNOTS...INCREASING TO 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS AFTER 29/15Z. ISOLD SHWRS AND TSTMS ARE POSSIBLE ACROSS THE BIG COUNTRY. 21 && .PREV DISCUSSION... /ISSUED 1012 PM CDT MON JUL 28 2008/ UPDATE... POPS WERE INCREASED INTO THE LOW CHC CATEGORY (30%) MAINLY NORTH OF INTERSTATE 20 ACROSS THE BIG COUNTRY. DISCUSSION... SCATTERED SHOWERS AND THUNDERSTORMS...WHICH MAY BE SLIGHTLY ELEVATED BASED ON THE LATEST SFC CAPE ANALYSIS FROM LAPS/RUC MODELS...ARE MAINLY AFFECTING AREAS NORTH OF INTERSTATE 20 OVER THE WESTERN BIG COUNTRY. THE ACTIVITY IS SHIFTING MORE EAST THAN NORTH AND SO THE POP ORIENTATION HAD TO BE CHANGED SLIGHTLY. IN ADDITION...WITH A BIT BETTER COVERAGE THAN EARLIER ANTICIPATED...POPS WERE INCREASED TO 30 PERCENT NORTH OF I-20. SEVERE WEATHER IS NOT EXPECTED DUE TO WEAK INSTABILITY AND LOW SHEAR. PREV DISCUSSION... /ISSUED 905 PM CDT MON JUL 28 2008/ UPDATE... A FEW TWEAKS TO THE HOURLY T/TD/RH/HI WERE NEEDED. DISCUSSION... CURRENT FORECAST IS STILL ON TRACK. A FEW SHOWERS HAVE DEVELOPED NEAR AND TO THE NORTH OF SWEETWATER...AND THE CURRENT SLGT CHC POPS IN THE GRIDS CORRECTLY MATCH THE LOCATION OF THE SHOWERS. THEREFORE...NO CHANGES WERE NEEDED. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 73 103 76 100 76 / 10 0 10 10 10 SAN ANGELO 73 103 75 101 75 / 10 0 10 10 10 JUNCTION 74 101 73 100 72 / 0 0 10 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1012 PM CDT MON JUL 28 2008 .UPDATE... POPS WERE INCREASED INTO THE LOW CHC CATEGORY (30%) MAINLY NORTH OF INTERSTATE 20 ACROSS THE BIG COUNTRY. && .DISCUSSION... SCATTERED SHOWERS AND THUNDERSTORMS...WHICH MAY BE SLIGHTLY ELEVATED BASED ON THE LATEST SFC CAPE ANALYSIS FROM LAPS/RUC MODELS...ARE MAINLY AFFECTING AREAS NORTH OF INTERSTATE 20 OVER THE WESTERN BIG COUNTRY. THE ACTIVITY IS SHIFTING MORE EAST THAN NORTH AND SO THE POP ORIENTATION HAD TO BE CHANGED SLIGHTLY. IN ADDITION...WITH A BIT BETTER COVERAGE THAN EARLIER ANTICIPATED...POPS WERE INCREASED TO 30 PERCENT NORTH OF I-20. SEVERE WEATHER IS NOT EXPECTED DUE TO WEAK INSTABILITY AND LOW SHEAR. && .PREV DISCUSSION... /ISSUED 905 PM CDT MON JUL 28 2008/ UPDATE... A FEW TWEAKS TO THE HOURLY T/TD/RH/HI WERE NEEDED. DISCUSSION... CURRENT FORECAST IS STILL ON TRACK. A FEW SHOWERS HAVE DEVELOPED NEAR AND TO THE NORTH OF SWEETWATER...AND THE CURRENT SLGT CHC POPS IN THE GRIDS CORRECTLY MATCH THE LOCATION OF THE SHOWERS. THEREFORE...NO CHANGES WERE NEEDED. PREV DISCUSSION... /ISSUED 610 PM CDT MON JUL 28 2008/ DISCUSSION... SEE THE DISCUSSION FOR THE UPCOMING 00Z TAF FORECAST BELOW. AVIATION... VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24 HOURS. WINDS WILL BE SOUTH AT AROUND 10 KNOTS...INCREASING TO 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS AFTER 29/15Z. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 73 103 76 100 76 / 10 0 10 10 10 SAN ANGELO 73 103 75 101 75 / 10 0 10 10 10 JUNCTION 74 101 73 100 72 / 0 0 10 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ LACY tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UT 840 PM MDT TUE JUL 29 2008 .SYNOPSIS...A WEAK PACIFIC SYSTEM WILL CROSS NORTHERN UTAH OVERNIGHT. A DRIER BUT VERY WARM SOUTHWESTERLY FLOW FOR WEDNESDAY THROUGH FRIDAY. MOISTURE IS EXPECTED TO INCREASE IN THE SOUTH BY LATE FRIDAY AND THEN SPREAD NORTHWARD FOR THE WEEKEND. && .DISCUSSION...UPPER LEVEL TROUGH NOW ENTERING NORTHWEST UTAH WITH A 70 KNOT 200 MB JET STREAK. INITIAL HIGH BASED CONVECTION DURING THE LATE AFTERNOON AND EARLY EVENING PRODUCED A LARGE OUTFLOW THAT SPREAD ACROSS THE DESERTS AND INTO THE WASATCH FRONT. GUSTS TO 50 MPH WERE COMMON IN THE DESERTS WITH ISOLATED SEVERE GUSTS AROUND 60 MPH BETWEEN ROSEBUD IN THEN NW CORNER AND I-80. HAVE HANDLED THIS WITH A HIGH WIND WARNING UP TO NOW. GUSTS OF 30 MPH AND UP TO NEAR 40 MPH REACHED INTO THE WASATCH FRONT AS THE ASSOCIATED EXTENSIVE OUTFLOW SPREAD INTO THIS REGION EARLY THIS EVENING. TO THE SOUTH...WIDELY SCATTERED THUNDERSTORMS HAVE LINGERED OVER THE SEVIER PLATEAU TO LOA AND CIRCLEVILLE AND ONE CELL PRODUCED A 57 MPH GUST IN RICHFIELD. MOST AREAS OF UTAH DRIED SIGNIFICANTLY SINCE LAST NIGHT AS DRY AIR ALOFT MIXED DOWN INTO THE BOUNDARY LAYER AND DROPPED DEWPOINTS INTO THE 20S AND 30S. ISSUE FOR THE REST OF THE EVENING IS SYNOPTIC LIFT ASSOCIATED WITH THE WAVE MOVING ACROSS CENTRAL AND NORTHERN UTAH WHILE MOISTURE ADVECTION SPREADS INTO THE WASATCH FRONT. WHETHER ENOUGH DESTABILIZATION OCCURS IN A DEEP LAYER TO KEEP THE CURRENT LIGHTNING THAT IS ONGOING BETWEEN DUGWAY AND DELTA. THIS LIGHTNING APPEARS TO BE ON THE OUTFLOW FROM EARLIER WEAK CONVECTION. 00Z NAM CONTINUES ITS TREND OF WEAKENING THE WEST CENTRAL UTAH CONVECTION...WHILE THE LATEST RUC AND 18Z ARW HOLD IT TOGETHER BETTER UNTIL IT REACHES THE WASATCH FRONT AND THEN WEAKENS. EITHER WAY BOTH THE NAM AND GFS TRACK THE 500 MB OMEGA AND HIGHEST HUMIDITY RIGHT ACROSS NORTHERN UTAH THROUGH MIDNIGHT AND THEN THE FAR NORTHEAST CORNER JUST AFTER MIDNIGHT. WITH LOW HUMIDITY IN THE BOUNDARY LAYER AND WIDESPREAD HIGH BASED CONVECTION THE THREAT FOR STRONG WINDS WILL REMAIN IN THE DESERTS AND INTO PARTS OF THE WASATCH FRONT THROUGH MIDNIGHT OR JUST AFTER. BOTH GFS AND RUC HAVE UP TO 25 KNOTS AT 700 MB CROSSING THE FAR NORTH LATE THIS EVENING. EXTENSIVE AREA OF COOLER CLOUD TOPS ARE DEPICTED ACROSS ALL OF NORTHERN UTAH THIS EVENING WITH THE BROAD AREA OF LIFT OCCURRING IN THIS REGION. AFTER TONIGHT LIMITED MOISTURE LINGERS ACROSS UTAH AND THE AIR MASS WARMS...BRINGING 18C 700 MB TEMPS UP TO I-80 BY THURSDAY AND PERSISTING THROUGH SUNDAY. STEEP LAPSE RATES WILL ALLOW FOR ISOLATED CONVECTION ON FAVORED SLOPES OF EASTERN UTAH. POSITION OF THE UPPER HIGH LATE IN THE WEEK WILL LIKELY ALLOW MOISTURE TO SPILL BACK INTO SOUTHERN UTAH BY FRIDAY AND THIS GETS DRAW INTO STRONGER SOUTHWEST FLOW ACROSS FAR NORTHWEST UTAH. THIS SHOULD ALLOW MOISTURE LEVELS TO INCREASE FROM SOUTH TO NORTH AND INCREASE THUNDERSTORM ACTIVITY INTO THE WEEKEND AND LAST INTO EARLY NEXT WEEK. && .AVIATION...OLD OUTFLOW WILL CONTINUE TO WEAKEN BUT APPROACHING HIGH BASED SHOWERS AND ISOLATED THUNDERSTORMS FROM THE SOUTHWEST COULD BRING GUSTY SOUTHWEST WIND TO 35-40 MPH BETWEEN 9 PM AND MIDNIGHT. MAINLY VFR CONDITIONS WITH A 10 PERCENT CHANCE OF LIGHTNING LATE EVENING. && .FIRE WEATHER...WIDESPREAD HUMIDITIES BELOW 15 PERCENT AND WIND GUSTS OF 40 TO 60 MPH ACROSS NORTHWEST UTAH LATE THIS AFTERNOON AND EARLY EVENING BROUGHT CRITICAL FIRE CONDITIONS. GUSTY WINDS CONTINUE IN THIS REGION BUT HAVE WEAKENED AND HUMIDITIES HAVE RISEN TO 15 TO 20 PERCENT. HOWEVER A WEAK WEATHER DISTURBANCE IS TRACKING THROUGH THE NORTHERN HALF OF UTAH AND BRINGING WIDESPREAD HIGH BASED SHOWERS AND ISOLATED THUNDERSTORMS. LIGHTNING HAS BEEN MORE NUMEROUS IN ZONE 434 OF WEST CENTRAL UTAH. ADDITIONAL OUTFLOW AND RATHER LOW HUMIDITY HAS PROMPTED A RED FLAG WARNING FOR NORTHWEST AREAS WHERE CONDITIONS WILL BE NEAR CRITICAL THROUGH THE EVENING AND THE POTENTIAL FOR CLOUD TO GROUND LIGHTNING STRIKES EXIST. IN THE SOUTH ISOLATED THUNDERSTORMS WILL CONTINUE WITH SLIGHTLY MORE MOISTURE IN PLACE ACROSS SOUTH CENTRAL UTAH THIS EVENING. HOWEVER THIS REGION HAS ALSO EXPERIENCED CONSIDERABLE DRYING IN THE LOW LEVELS. A DRIER AND MORE STABLE AIRMASS IS EXPECTED TO SPREAD ACROSS THE REGION FOR THE MIDDLE TO LATTER PORTION OF THE WEEK. ISOLATED THUNDERSTORMS FOR FAVORED EASTERN AND SOUTHERN AREAS WILL INCREASE THURSDAY AND FRIDAY. HOT TEMPERATURES AND LOW HUMIDITY FOR MUCH OF THE REGION. 10 TO 15 KNOTS AT 700 MB AND VERY LOW HUMIDITY WILL BRING LOCAL NEAR CRITICAL CONDITIONS TO WESTERN AND SOUTHWEST AREAS THURSDAY AND FRIDAY. DEEPER MOISTURE WILL SPREAD INTO THE REGION STARTING SATURDAY. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...HIGH WIND WARNING AND RED FLAG WARNING FOR UTZ005-015 UNTIL MIDNIGHT TO 2 AM. RED FLAG WARNING FOR UTZ002>004 UNTIL 2 AM FOR GUSTY WINDS AND LIGHTNING. WY...NONE. && $$ TARDY FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE) ut AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 444 AM CDT TUE JUL 29 2008 .SHORT TERM...TODAY THROUGH WEDNESDAY... FORECAST CONCERNS THIS PERIOD ON CONVECTIVE CHANCES TODAY INTO THE EVENING. STRONG SHORT WAVE MOVING THROUGH THE NORTHERN PLAINS WITH SFC COLD FRONT EXTENDING SOUTH THROUGH WESTERN MN. 40-50KT MID LEVEL JET TO MOVE INTO STATE THIS AFTERNOON...INCREASING SHEAR OVER AREA. WEAK TO MODERATE SOUTHERLY FLOW AHEAD OF FRONT TO BRING SFC DEW POINTS UP TO MID 60S...AROUND 70...MAKING FOR MORE HUMID DAY...WITH SBCAPES RISING INTO THE 1 TO 2K RANGE. MODELS SHOWING SOME DIFFERENCES WITH GFS BRINGING IN HIGHER DEW POINTS AND MORE INSTABILITY IN MID LEVELS. CURRENT CONVECTION OVER EASTERN MN...HANDLED FAIRLY GOOD BY RUC...THOUGH A BIT SLOW...BRINGING REMNANTS INTO NORTH CENTRAL WI EARLY THIS MORNING. QUESTION IS REDEVELOPMENT THIS AFTERNOON AHEAD OF FRONT AND TEMPERATURES GIVEN CLOUDINESS ASSOCIATED WITH ONGOING CONVECTION. LOWERED TEMPERATURES A BIT FOR TODAY...THOUGH INCREASING HUMIDITY WILL MAKE FOR WARM AND MUGGY DAY. FRONT TO PASS THROUGH CWA TONIGHT PERIOD WITH HIGH BUILDING IN FOR WED. .LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY WEAK HIGH PRESSURE WILL NOSE INTO NORTHEAST WISCONSIN WEDNESDAY NIGHT AND THEN GRADUALLY SHIFT EAST ON THURSDAY. DIFFERENCES NOTED BEGINNING THURSDAY NIGHT AS MODELS DIFFER ON LOCATION AND TIMING OF RETURN FLOW. WILL CONTINUE WITH DRY FORECAST FOR NOW UNTIL MODELS COME INTO AGREEMENT WITH PRECIPITATION THURSDAY NIGHT. FOR FRIDAY INTO THE WEEKEND...NEW GFS GUIDANCE VERY WARM COMPARED TO THE CURRENT FORECAST. HAVE NUDGED UP TEMPERATURES A FEW DEGREES...BUT DID NOT GO AS HIGH AS THE MEX GUIDANCE. WEAK BOUNDARY LURING ACROSS THE AREA FRIDAY INTO SATURDAY...ALONG WITH THE POTENTIAL FOR CONVECTION COULD KEEP TEMPERATURES DOWN A FEW DEGREES. WILL CONTINUE TO FOLLOW THE TRENDS THE NEXT FEW NIGHTS AND MAKE ADJUSTMENTS UPWARD IF THIS TREND CONTINUES. WITH BOUNDARY LURKING AROUND...A SMALL CHANCE OF THUNDERSTORMS IS WARRANTED THIS WEEKEND. && .AVIATION... LOW VFR CIGS THIS AM TO LIFT NORTH...WHILE SHOWERS/TSTM AND SCT MVFR CIGS EXPECTED TO MOVE BY THIS AFTERNOON...EVENING AHEAD OF COLD FRONT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ TE/ECKBERG wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 250 AM CDT TUE JUL 29 2008 .SHORT TERM...TODAY THROUGH THURSDAY FORECAST CONCERNS FOCUS ON THE PCPN TRENDS TODAY. MCS ONGOING ACROSS THE EASTERN DAKOTAS/WESTERN MN...TRACKING MOSTLY EAST...MATCHING THE CORFIDI VECTORS. THE ACTIVITY WAS SPARKING AHEAD OF A SFC BOUNDARY/500 MB SHORTWAVE TROUGH/AND IN THE NOSE OF THE 850 MB LOW LEVEL JET/MOISTURE TRANSPORT. THE RUC WOULD CONTINUE TO PUSH THE BULK OF THE MCS ACROSS NORTHERN WI THIS MORNING...WITH ONLY SCATTERED ACTIVITY TO THE SOUTH. RADAR TRENDS SUPPORT THIS...AS DOES THE LATEST VWP/PROFILER 850 MB WINDS. THE FRONT WILL CONTINUE TO TRACK EAST TODAY...AS THE 500 MB SHORTWAVE TROUGH ITS ASSOCIATED WITH MOVES ACROSS LAKE SUPERIOR. THE NAM AND GFS BUILD 2500+ J/KG OF SBCAPE FOR THE AFTERNOON AHEAD OF THE BOUNDARY...WITH ABOUT 25-30 KTS OF 0-3 KM SHEAR. CLOUD SHIELD WITH THE CURRENT STORMS ARE A CONCERN...AS THEY COULD INHIBIT THE INSTABILITY. HOWEVER...ITS MORE EXTENSIVE AND THICK TO THE NORTH...WITH THE CONVECTION. EVEN SO...MLCAPES OF 1000-2000 J/KG ARE INDICATED AHEAD OF THE FRONT CURRENTLY. SO...STILL EXPECT A DECENT AMOUNT OF INSTABILITY FOR THE SYSTEM TO TAP INTO. OVERALL FOR TODAY...FEEL THE PCPN THREAT IS LOW FOR THE SOUTHERN 2/3RDS OF THE FORECAST AREA THIS MORNING. THIS IS SUPPORTED BY THE RADAR TRENDS...ALONG WITH THE 29.03Z RUCWRF...WHICH IS DOING A GOOD JOB WITH THE CURRENT CONVECTION. THIS AFTERNOON...CHANCES SHOULD INCREASE LOCALLY AS THERE SHOULD BE MORE DESTABILIZATION...ALONG WITH THE SFC FRONT TRACKING IN. EXPECT THE BETTER STORM THREAT TO BE EAST OF THE AREA...WHERE LESS CLOUDS/MORE CAPE/AND A GREATER INFLUENCE OF THE LOW LEVEL JET/MOISTURE TRANSPORT WILL TAKE PLACE. CONSIDERING ALL THIS...FEEL THE SEVERE THREAT WILL BE LOW LOCALLY...WITH THE BETTER CHANCES LIKELY LATER THIS AFTERNOON...AND FOR THE FAR EASTERN PARTS OF THE FORECAST AREA. A WEAK SFC HIGH STARTS TO BUILD ACROSS THE REGION LATE TONIGHT...AND LOOKS TO LINGER ACROSS THE GREAT LAKE STATES INTO SATURDAY. THIS WILL NOT RULE OUT PCPN CHANCES...ALTHOUGH THE TRENDS WOULD BE FOR DRY WEATHER INTO THE WEEKEND. ONE FEATURE OF NOTE IS A POTENTIAL MCS OVER NORTH DAKOTA WED NIGHT...WITH BOTH THE GFS AND NAM HAVING THIS FEATURE. A GOOD MOISTURE FEED VIA THE 850 MB MOISTURE TRANSPORT VECTORS...ALONG WITH A 40 KT LOW LEVEL JET...WOULD BE THE MAIN INITIATORS. CORFIDI VECTORS WOULD SUGGEST THAT THE POTENTIAL MCS WOULD TRACK SOUTH/SOUTHEAST...INTO IOWA...STAYING TO THE SOUTHWEST OF THE LOCAL AREA. THU NIGHT THE 29.00Z NAM SUGGESTS ANOTHER POTENTIAL MCS TO DEVELOP OVER CENTRAL MN...THANKS AGAIN TO THE INFLUENCE OF THE LOW LEVEL JET AND MOISTURE TRANSPORT. THIS MAY BE AN ENHANCEMENT OF ONGOING PCPN THAT SPARK AS A 500 MB SHORTWAVE TRACKS ACROSS THE CANADIAN/US BORDER THU AFTERNOON. CORFIDI VECTORS WOULD TAKE THIS MCS ACROSS THE FORECAST AREA. HOWEVER...THE 29.00Z GFS IS WELL NORTH WITH THIS FEATURE...AS IT SURGES ITS LOW LEVEL JET INTO NORTHERN MN. THE 29.00Z EC WOULD FAVOR THE NAM...WITH THE 03Z SREF A BLEND BETWEEN THE NAM/GFS. FOR NOW...WILL KEEP THE BETTER CHANCE POPS ACROSS THE NORTHERN PORTION OF THE FORECAST AREA. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY MEDIUM RANGE MODELS TAKE A 500 MB SHORTWAVE TROUGH ACROSS SOUTHERN CANADA...TRACKING NORTH OF THE REGION FRI/SAT. WHILE THE BULK OF THE ENERGY WITH THIS SYSTEM WILL BE TO THE NORTH...BOTH THE GFS AND ECMWF SLIDE A SFC FRONT ACROSS THE REGION. THIS FRONT THEN BECOMES WEST TO EAST ORIENTATED...LINGERING ACROSS THE UPPER MISSISSIPPI RIVER VALLEY FOR SUNDAY THROUGH THE EARLY PART OF NEXT WEEK. GOOD LOW LEVEL MOISTURE RETURN INTO THIS FRONT SHOULD RESULT IN SOME SHOWER/STORM DEVELOP AROUND THE BOUNDARY...AND COULD HAVE THE POTENTIAL FOR SOME HEAVY...TRAINING TYPE RAINS. && .AVIATION... CONVECTIVE CLUSTER TO THE NORTHWEST EARLY THIS MORNING LOOKS LIKE IT WILL REMAIN NORTH OF THE TAF SITES. COULD BE SOME DEVELOPMENT SOUTHWARD...BUT BULK OF ACTIVITY TIED MORE TO THE SHORT WAVE TROUGH WHICH IS CROSSING NORTHERN MN. RELATIVELY WEAK SURFACE FLOW AND AMPLE BOUNDARY LAYER MOISTURE RESULTING IN PATCHY BR...AND THIS WILL CONTINUE FOR KRST INTO DAYLIGHT. CONVECTION TO WEAKEN...AND ATTENTION THEN SHIFTS TO APPROACH OF COLD FRONT WHICH IS CURRENTLY ACROSS EASTERN ND/CENTRAL SD. EXPECT REDEVELOPMENT ALONG THE FRONT LATER TODAY...LINGERING INTO THE EVENING. STRONGEST ACTIVITY LOOKS LIKE IT WILL OCCUR EAST OF THE TAF LOCATIONS...BUT WILL HAVE TO ADDRESS THE CHANCES IN THE NEXT TAF ISSUANCE. SKIES SHOULD CLEAR OUT BEHIND THE FRONT AS HIGH PRESSURE MOVES IN. MW && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 333 AM MDT WED JUL 30 2008 .SHORT TERM...SATELLITE AND GPS PRECIPITABLE WATER VALUES SHOW A SLIGHT INCREASE IN MOISTURE UPSTREAM AT THIS HOUR. SOUNDINGS FROM 00Z AND CLOUD OBSERVATIONS HOWEVER SHOW THAT THE MOISTURE IS MOSTLY IN THE MID AND HIGH LEVELS. RUC ANALYSES FOR THE LAST SEVERAL HOURS SHOW SOME QUASIGEOSTROPHIC ASCENT OVER SOUTHEAST IDAHO AND NORTHERN UTAH WHICH THE MODELS WANT TO WASH OUT AS THE DAY WEARS ON. NOT SURE WHAT TO MAKE OF THESE PROGNOSES AS THE ANALYSES CONTINUE TO HOLD ONTO THIS FEATURE. IN ANY EVENT...THE MOISTURE AND POSSIBLE LIFT SHOULD BE SUFFICIENT TO KEEP A VERY SMALL THREAT OF HIGH BASED CONVECTION OVER MUCH OF THE AREA BY LATE MORNING AND INTO THE EVENING. GUSTY WINDS BUT LITTLE RAIN WOULD BE THE MAIN ISSUE WITH ANYTHING THAT DEVELOPS. IT WILL BE HOT AGAIN...WE ARE GETTING CLOSE TO SETTING THE ALL TIME /SINCE 1872/ LONGEST STREAK OF CONSECUTIVE 90+ MAXIMUM TEMPERATURES...YUCK. .LONG TERM...MODELS KEEP THE UPPER RIDGE CENTERED RIGHT OVER THE FORECAST AREA FROM THURSDAY THROUGH FRIDAY NIGHT. THE FLOW ALOFT IS LIGHT WEST-NORTHWESTERLY. THE QG VERTICAL VELOCITY FIELDS SHOW NOTHING CONCERNING SYNOPTIC SCALE ENERGY THROUGH THE PERIODS. THE BOUNDARY LAYER SHOULD NOT DEVIATE SIGNIFICANTLY FORM THE NORMAL DIURNAL TRENDS. MODELS SHOW MOISTURE TO BE PRETTY SPARSE THROUGH FRIDAY NIGHT...MAINLY SOME IN THE MID AND UPPER LEVELS. PRECIPITABLE WATER VALUES ARE IN THE 0.50 TO 0.80 INCH RANGE THURSDAY THROUGH FRIDAY NIGHT. BOUNDARY LAYER DEW POINTS ARE IN THE 30 TO 45 F RANGE OVER THE PLAINS AND FOOTHILLS LATE DAY THURSDAY AND LATE DAY FRIDAY. THERE IS LIMITED CAPE OVER THE NORTHEAST CORNER AND HIGH MOUNTAINS FOR LATE DAY THURSDAY. ON FRIDAY THERE IS A BIT MOVE OVER THE MOUNTAINS...FOOTHILLS...AND ADJACENT PLAINS. THE THETA-E AXIS IS WELL EAST OF THE FORECAST AREA THROUGH THE PERIODS. LAPSE RATES ON THE CROSS SECTIONS STILL SHOW A CAP IN THE MID LEVELS... BOTH THURSDAY AND FRIDAY AFTERNOONS. WILL GO WITH 10-20%S POPS IN THE MOUNTAINS ONLY LATE THURSDAY...SAME FOR LATE DAY FRIDAY WITH THE ADDITION OF 10%S OVER THE PLAINS. FOR TEMPERATURES...THURSDAY`S HIGHS LOOK QUITE SIMILAR TO TODAY`S. FRIDAY`S READINGS WARM-UP 0.5-1.5 C FROM THURSDAY`S. WILL LEAVE THE LATER DAYS...SATURDAY THROUGH TUESDAY AS IS. && .AVIATION...VFR CONDITIONS ARE EXPECTED TODAY AND TONIGHT. THERE SHOULD BE A BIT OF HIGH BASED CONVECTION AROUND DURING THE HEAT OF THE DAY WHICH COULD PRODUCE GUSTY OUTFLOW WINDS/MICROBURST ACTIVITY. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ET/RJK co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 137 AM EDT WED JUL 30 2008 .AVIATION... WEAKENING CDFNT EXTENDING FM NW LWR MI SWWD INTO ERN IA IN RESPONSE TO FILLING CYCLONE OVR SW ONTARIO WILL DROP INTO THE AREA THIS MORNING AND WASH OUT. MID LVL MSTR PLUME FM DOLLY REMNANTS WILL BE SLOW TO CLEAR HWVR W/WK FLW ALOFT AS VFR CONDS CONT THROUGH THE PD. OTHERWISE AFTN CONVECTIVE POTENTIAL STILL APPEARS TOO LOW TO WARRANT A MENTION. && .PREV DISCUSSION... .UPDATE... TSTMS WHICH DEVELOPED ALONG PREFRONTAL TROF OVER ERN IA THIS AFTN PROPAGATING EWD AT 35-40KT ACROSS IL THIS EVE. EXPECT STORMS TO WEAKEN WITH DIURNAL COOLING AND AS THEY MOVE INTO LESS UNSTABLE AIRMASS OVER OUR AREA...HWVR...3-6KM LAPSE RATES AROUND 6C/KM FM DTX EVE SOUNDING SUGGESTS POTENTIAL FOR SUFFICIENT ELEVATED INSTABILITY TO ALLOW STORMS TO PERSIST IN WEAKENED STATE AS THEY MOVE THROUGH OUR AREA TONIGHT. UPDATED TO INCREASE POPS TO HIGH LIKELY OVER SWRN PORTION OF CWA...GOING CHC POPS ACROSS REMAINDER OF THE AREA STILL A REASONABLE ESTIMATE OF POTENTIAL. && .SHORT TERM... TONIGHT THROUGH WEDNESDAY NIGHT 19Z ANALYSIS REVEALS TWO DISTINCT MID LEVEL VORTICIES NEARING THE REGION...A POTENT SW TROUGH ENTERING THE UPPER GREAT LAKES AND A THE REMNANTS OF DOLLY HEADING INTO THE MID MISSISSIPPI VALLEY. BOTH OF THESE FEATURES WILL INTERACT TO HELP INCREASE PRECIP CHANCES TONIGHT INTO TOMORROW. HAVE UTILIZED THE NAM 12 AND AND RUC13 FOR FORECAST DETAILS MAINLY IN TRYING TO TIME THESE FEATURES AND THERE RESULTANT IMPACTS ON THE LOCAL SYNOPTIC/MESOSCALE PATTERN. MOISTURE CONTINUES TO STRUGGLE TO RETURN TO THE REGION PER WEAK MOMENTUM FIELDS GIVEN LIGHT TO CALM WINDS BEING PREDOMINATE OVER THE FA. HIGHEST MOISTURE AXIS CONTINUES TO RESIDE OVER IL/IA/MO AND WILL BEGIN TO SLOWLY PUSH EAST AS LL WINDS RESPOND TO SFC PRESSURE FALLS IN RESPONSE TO THE ADVANCING UPPER TROUGH. WITH INCREASED LL MOISTURE...MID COOLING WILL COMMENCE TONIGHT IN REPONSE TO THE SKIRTING UPPER IMPULSE...INCREASING THE INSTABILITY ACROSS THE REGION. THE INCREASED INSTABILITY IS EVIDENT IN SHOWALTER INDICES PROGS FALLING TO AROUND -3. THIS INCREASED INSTABILITY COUPLED WITH THE ADVANCEMENT OF A SFC BOUNDARY WILL SUPPORT AN INCREASED CHANCE FOR PRECIP TONIGHT. LACK OF DEEP LAYER SHEAR/STRONG UPPER LEVEL FORCING/AND WEAK LL WIND FIELDS WILL BE DETRIMENTAL TO WELL ORGANIZED CONVECTION...ALLOWING THE ADVANCING BOUNDARY AND ANY RESIDUAL OUTFLOW BOUNDARIES TO BE THE SOLE MECHANISM FOR PRODUCTION OF PRECIP. NIGHTTIME FRONTAL ARRIVAL WILL ALSO BE DETRIMENTAL TO PRECIP CHANCES. HENCE...HAVE TRIMMED BACK 50 POPS TO THE WEST WHERE BEST INGREDIENTS WILL BE IN PLACE. FARTHER EAST...HAVE LOWERED TO 40...WHICH MAY EVEN BE TOO HIGH AT THIS POINT...THINKING MAV GUIDANCE MAY BE THE MOST REALISTIC IN THE POP DEPARTMENT. WEDNESDAY...FRONTAL BOUNDARY WILL SAG INTO THE REGION AND STALL IN RESPONSE TO THE ADVANCEMENT OF THE REMNANTS OF DOLLY. THE TRACK OF THIS IMPULSE VARIES IN MODEL SOLUTIONS AND WILL LIKELY CHANGE FROM RUN TO RUN GIVEN FORECAST MODEL POOR HANDLING OF TROPICAL REMNANTS/SLOW MOVING UPPER IMPULSES. CURRENT EXPECTATION IS THAT THIS SYSTEM WILL PHASE WITH THE DEEP NORTHERN STREAM WAVE AND PROGRESS EAST. THUS WITH ADDED LIFT FROM THE UPPER IMPULSE AND INCREASED LL CONVERGENCE FROM THE BOUNDARY IN PLACE...HAVE LET POPS RIDE THROUGH THE DAY WITH HIGHER NUMBERS IN THE SOUTH WHERE BETTER DYNAMICS LOOK TO BE FAVORED. VEERING WINDS IN THE H925 TO H85 LAYER OVERNIGHT WILL BRING AN ADDED SMALL CHANCE OF PRECIP SHIFTING SOUTH OVERNIGHT. HAVE RETAINED LOW POPS FOR THIS. OTHERWISE...TEMPS WILL REMAIN RATHER WARM THROUGH THE PERIOD WITH SLIGHTLY DRIER AIR WORKING INTO THE NORTH WED NIGHT PER NORTHERLY FLOW...ALLOWING COOLER TEMPS THERE. LONG TERM... WARM AND MUGGY WITH LITTLE CHANCE FOR PRECIPITATION IS THE THEME FOR THE EXTENDED PERIOD. MODELS CONTINUE TO ADVERTISE STRONG UPR LEVEL RIDGE BUILDING EASTWARD THOUGH THE WEEKEND WITH H5 HIGH OVER OHIO VALLEY BY SUNDAY NIGHT. GFS BRINGS A WEAK SW THROUGH FRIDAY NIGHT BUT MODEL SOUNDINGS ALREADY CAPPED BY THIS TIME. HEAT BUILDS IN EARNEST BEGINNING SATURDAY WITH H850 TEMPS OVER 20C SAT THROUGH TUESDAY. GUIDANCE...ALREADY BEING UNDERCUT...WARMED EVEN MORE. BUMPED HIGHS INTO LOWER 90S MOST AREAS SAT-SUN WHICH IS STILL BELOW GUIDANCE. WITH ONGOING DRY CONDITIONS THE DOOR IS STILL OPEN TO EVEN WARMER TEMPS THAN CURRENTLY FCST. RIDGE FLATTENS EARLY NEXT WEEK WITH GFS ENSEMBLE MEAN FASTER TO DROP NW FLOW OVER REGION THAN THE OP RUN...WITH BNDRY SAGGING NEAR NORTHERN CWA BY END OF FCST PD. BUT ONCE ESTABLISHED WOULD NOT BE SURPRISED TO SEE RIDGING HOLD LONGER THAN CURRENTLY DEPICTED. EITHER WAY...TEMPS REMAIN ABOVE NORMAL THROUGH THE EXTENDED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LUDINGTON UPDATE...JT AVIATION...HOLSTEN in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT WED JUL 30 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE. .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A LOW OVER WESTERN ONTARIO WITH A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THIS LOW MOVING THROUGH WESTERN LAKE SUPERIOR AND THE WESTERN U.P. A COLD FRONT EXTENDS FROM A LOW OVER WESTERN ONTARIO THROUGH DULUTH AND THE UPPER MISSISSIPPI RIVER VALLEY. NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS ARE FIRING OVER EASTERN U.P. AND LAKE SUPERIOR. NEW SHOWERS AND THUNDERSTORMS ARE DEVELOPING OVER WESTERN U.P. IN AN AREA OF INSTABILITY AHEAD OF THE FRONTAL BOUNDARY. THESE ARE MOVING EAST AT 35 TO 40 MPH PRODUCING BRIEF HEAVY RAINS. && .SHORT TERM... (TONIGHT AND WEDNESDAY) THE MID LEVEL LOW WILL MOVE INTO CENTRAL ONTARIO...WHILE WEAK SHORTWAVES SWEEP THROUGH THE NORTHERN PART OF THE FORECAST AREA TONIGHT. THE COLD FRONT WILL ADVANCE ACROSS THE U.P. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL GENERATE MORE SHOWERS AND THUNDERSTORMS. AN UPPER LEVEL JET MAX IS OVER NORTHERN MINNESOTA AND WILL CROSS UPPER MICHIGAN PLACING THE STRONGEST UPPER LEVEL DIVERGENCE OVER THE CENTRAL AND EASTERN U.P. WARM AIR ADVECTION AT 850MB AHEAD OF THE FRONT WILL CONTRIBUTE TO DESTABILIZING THE ATMOSPHERE PRODUCING SOME MUCAPE VALUES GREATER THAN 2000J/KG AND A PRONOUNCED THETA-E RIDGE AHEAD OF THE FRONT. CONDITIONS CONTINUE TO LOOK FAVORABLE FOR SEVERE WEATHER DEVELOPMENT. WEAK SHORTWAVE ENERGY PASSING OVER THE EASTERN U.P. WILL PRODUCE JUST A CHANCE OF THUNDERSTORMS OVER THE EASTERN U.P. ON WEDNESDAY. DRY AIR FOLLOWING THE FRONT WILL LIMIT THE SHOWERS AND THUNDERSTORMS. .LONG TERM... (WED NIGHT THRU TUE) WED NIGHT INTO THU...SHORTWAVE RIDGING AND ASSOCIATED SFC HIGH PRES WILL BE MOVING INTO THE UPPER GREAT LAKES ALONG WITH A DRY AIRMASS. SO...TRANQUIL/SEASONABLE WEATHER IS EXPECTED. LAKE BREEZES WILL BE THE RULE NEAR LAKE SUPERIOR THU AS HIGH PRES DRIFTS SE TO LAKE SUPERIOR. IT MAY NOT BE UNTIL LATE IN THE DAY THAT THE LAKE BREEZE DEVELOPS NEAR LAKE MICHIGAN. FRI THRU TUE...MODELS ARE IN REASONABLE AGREEMENT THAT THE RIDGE OVER THE SW CONUS WILL EXPAND EWD LATE WEEK THRU THE WEEKEND SO THAT BY EARLY NEXT WEEK THE RIDGE DOMINATES THE SRN HALF OF THE CONUS. AT THE SAME TIME...A MIDLEVEL LOW WILL TRACK E ACROSS SRN CANADA TOWARD JAMES BAY BY MON PER ECMWF/GFS AND GFS ENSEMBLES. RESULT WILL BE AN EWD EXPANSION OF HEAT ACROSS THE CONUS WITH THE UPPER GREAT LAKES BECOMING FAVORED FOR POTENTIAL OF PERIODIC CONVECTION ON THE EDGE OF THE HEAT AND UNDER THE UPPER JET. PATTERN SUPPORTS THE POSSIBILITY OF AN EPISODE OF STRONG OR SVR STORMS. THU NIGHT/FRI OFFERS THE FIRST OPPORTUNITY OF SHRA/TSRA AS APPROACHING SUBTLE SHORTWAVE INCREASES LOW-LEVEL JET. HOWEVER...LOCATION OF THE NOSE OF LOW-LEVEL JET/STRONGEST THETA-E ADVECTION SUGGESTS A SE MOVING CLUSTER OF SHRA/TSRA SHOULD PASS TO THE SW AND S OF THE FCST AREA. THERE MAY BE ADDITIONAL SCT CONVECTION FARTHER N ALONG APPROACHING 850MB TROF... BUT CONFIDENCE IN PCPN OCCURRING IS TOO LOW TO INCLUDE POPS ACROSS THE AREA WITH THIS FEATURE LATE THU NIGHT/FRI. THERE IS LITTLE CONFIDENCE IN TIMING PCPN CHANCES BEYOND FRI...BUT RIGHT NOW IT APPEARS THAT THERE WILL BE AT LEAST ONE OPPORTUNITY FOR SHRA/TSRA SAT/SUN AS COLD FRONT APPROACHES. WILL OPT FOR DRY WEATHER MON/TUE IN THE WAKE OF THE COLD FRONT ASSOCIATED WITH EWD MOVING CLOSED LOW ACROSS SRN CANADA. TEMPS WILL BE ABOVE SEASONAL NORMALS THRU THE WEEKEND...THEN RETURN CLOSER TO NORMAL MON/TUE. IT WILL PROBABLY BE UNCOMFORTABLY HOT/HUMID AT LEAST ONE OF THE DAYS (MOST LIKELY SAT) PRIOR TO FROPA LATE IN THE WEEKEND. IN ADDITION...DEPENDING ON PCPN OCCURRENCE...WOULD NOT BE SURPRISED IF MIN TEMPS SAT NIGHT DON`T FALL BELOW 70F IN SOME AREAS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WITH MID LVL DRYING OVER SOME LLVL MSTR FOLLOWING RECENT RA...EXPECT OFF AND ON PTCHY MVFR FOG AT SAW EARLY THIS MRNG IN PRESENCE OF NOCTURNAL COOLING/STABILIZATION THAT WL LIMIT NEAR SFC DRY ADVCTN. DID NOT GO ANY LOWER THAN MVFR GIVEN SOME BREEZE. SOME LLVL DRY HAS ALREADY ARRIVED ON THE MORE EXPOSED KEWEENAW PENINSULA...SO NO FOG EXPECTED THERE. OTRW...VFR CONDITIONS WL PREDOMINATE TDAY/THIS EVNG. HOWEVER...GUSTY W WIND IS LIKELY AT CMX WITH DAYTIME HTG/LK BREEZE FLOW ACCENTUATING FAIRLY TIGHT WLY GRADIENT FLOW ON THE SRN FLANK OF LO MOVING ACRS ONTARIO. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS COLD FRONT MOVES ACROSS LAKE SUPERIOR TONIGHT...WINDS AHEAD OF THE FRONT WILL BE SOUTHERLY AND MAY INCREASE TO 25 KT. WIND SPEEDS WILL DIMINISH SLIGHTLY BEHIND THE FRONT AS THE DIRECTION SHIFTS TO THE WEST. FURTHER DIMINISHING OF WINDS IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS HIGH PRESSURE DROPS OUT OF CANADA ACROSS LAKE SUPERIOR. LOOK FOR WINDS TO GRADUALLY PICK UP FRIDAY AFTERNOON INTO SAT AS ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE PLAINS. SPEEDS SHOULD REMAIN UNDER 25 KNOTS THROUGH THE REST OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...ROLFSON AVIATION...KC/AJ MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 336 AM CDT WED JUL 30 2008 .DISCUSSION... CIRCULATION CENTER ASSCD WITH THE REMNANTS OF DOLLY HAS SHIFTED INTO SERN KS WITH AN ELONGATED SHEAR AXIS EXTENDING NE INTO CENTRAL/NORTH CENTRAL MISSOURI. LATEST GFS/RUC APPEAR TO HAVE A MUCH BETTER HANDLE ON THE SITUATION AS THE NAM QPF HAS BEEN MUCH TOO FAR NORTH OVERNIGHT. A RATHER SHARP H7/H5 DEFORMATION ZONE HAS LIMITED THE NWD EXTENT OF THE HEAVY PRECIP SHIELD...FM KC AREA ENE TO NR MACON. THIS IS WELL HANDLE BY THE GFS WITH THE GFS TO SHIFT THIS AXIS SLOWLY SE THROUGH THE DAY. A VERY IMPRESSIVE H8/H7 THETAE RIDGE WAS POSITION NR THE DEFORMATION ZONE WITH COPIOUS AMOUNT OF TROPICAL MOISTURE...2-2.5 PRECIPITABLE WATER...RESULTING IN VERY HEAVY RAINFALL AMOUNTS. CLOUD TOPS HAVE WARMED THE LAST FEW HOURS AS THE LLJ HAS VEERED. HOWEVER...EXCESSIVE RAINFALL AMOUNTS ARE STILL LIKELY THIS MORNING BEFORE SYSTEM BEGINS TO WEAKEN AND BEGIN ITS DIURNAL DECREASE IN THE AFTN. SINCE RADAR TRENDS VERIFY THE LATEST GFS...HAVE REMOVED THE XTRM NRN EXTENT OF THE FFA. OTHERWISE...HAVE CONCERN ABOUT LOW CLOUDS AND FOG TNGT. MORE CONFIDENT IN AREAS OF FOG AFTER MIDNIGHT IN AREAS WHICH HAVE RECEIVED THE HEAVY RAIN TODAY. UPPER RIDGE OF HIGH PRESSURE TO BUILD INTO THE REGION THURSDAY AND FRIDAY WITH VERY WARM TEMPERATURES RETURNING. DB && .AVIATION... PRECIPITATION HAS EXPANDED IN COVERAGE THIS EVENING AND WILL CONTINUE THROUGH THE OVERNIGHT...AS IS TYPICAL OF TROPICAL INFLUENCED SYSTEMS. BAND OF VERY HEAVY RAIN...WITH LIFR CIGS/VSBYS...IS SETTING UP GENERALLY ALONG INTERSTATE 35 FROM EMPORIA TO KC AREA. THIS BAND WILL PERSIST THROUGH AT LEAST THE NEXT SEVERAL HOURS...GRADUALLY MOVING NORTH AND EAST. HAVE THEREFORE HAD TO CONTINUE THUNDER FOR THE KC SITES THROUGH THE NIGHT. HAVE TAPERED BACK TO SHOWERS AND MVFR CIGS DURING THE DAY WEDNESDAY. THE ENTIRE SYSTEM IS PROGGED TO MOVE SOUTH OF THE TAF SITES BY WEDNESDAY EVENING. NRR && .EAX WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL 1 PM WEDNESDAY FOR MOZ017-MOZ021-MOZ022- MOZ023-MOZ024-MOZ025-MOZ028-MOZ029-MOZ030-MOZ031-MOZ032- MOZ033-MOZ037-MOZ038-MOZ039-MOZ040-MOZ043-MOZ044-MOZ045- MOZ046-MOZ053-MOZ054. KS...FLASH FLOOD WATCH UNTIL 1 PM WEDNESDAY FOR KSZ057-KSZ060-KSZ103- KSZ104-KSZ105. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 403 AM CDT WED JUL 30 2008 .SHORT TERM...TODAY THROUGH FRIDAY CURRENT WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS UPPER LEVEL RIDGE AXIS CENTERED OVER THE NORTHERN HIGH PLAINS WITH A WEAK RIPPLE AT 700 MB MOVING ACROSS THE AREA. VORT MAX ALSO MOVING ACROSS NORTH DAKOTA AND NORTH CENTRAL SOUTH DAKOTA...WITH LLJ IN PLACE ACROSS SOUTH CENTRAL AND SOUTHWEST SOUTH DAKOTA. ALL THIS IS INTERACTING WITH JUST ENOUGH ELEVATED INSTABILITY TO PRODUCE ACCAS AND ISO SHOWERS/THUNDERSHOWERS ACROSS PORTIONS OF CENTRAL AND SOUTHEASTERN SOUTH DAKOTA EARLY THIS MORNING. RUC/NAM PICKING UP ON THIS FAIRLY WELL AND SHOWS THIS ACTIVITY LINGERING INTO THE MORNING HOURS. HAVE THEREFORE EXPANDED SLIGHT CHANCE POPS A BIT FURTHER EAST INTO THE MORNING HOURS. WARM FRONT POSITION BECOMING A LITTLE BETTER DEFINED ON SFC OBS THIS MORNING WITH PIR/HON/BKX SHOWING SOUTHEAST WINDS AND OBS TO THE NORTH WITH EITHER LIGHT EASTERLY WINDS OR LIGHT/VARIABLE WINDS. MODELS SHOW THE WARM FRONT TO BASICALLY REMAIN IN THIS POSITION ALL DAY. WILL KEEP SLIGHT CHANCE POPS GOING INTO THE AFTERNOON HOURS EVEN THOUGH A LARGE PORTION OF THE CWA SHOULD REMAIN CAPPED. SVR PARAMETERS DO SUPPORT STRONG TO SEVERE THIS AFTERNOON/EVENING WITH ANY STORMS THAT CAN GET GOING. ATTENTION THEN TURNS TO THURSDAY WHEN ANOTHER FRONTAL BOUNDARY LOOKS TO TRACK EASTWARD ACROSS THE AREA. 700 MB TEMPS BEGIN TO INCREASE EVEN MORE ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...APPROACHING 15 DEGREES C. MUCH OF THE AREA SHOULD REMAIN CAPPED...EXCEPT FOR PERHAPS THE FAR NORTHERN/NORTHEASTERN CWA AND HAVE INCLUDED SLIGHT CHANCE POPS FOR THESE AREAS LATE WEDNESDAY NIGHT AND INTO THURSDAY. MODELS HAVE BEEN FAIRLY CONSISTENT IN BRINGING SOME SORT OF CONVECTIVE COMPLEX ACROSS NORTH DAKOTA AND POSSIBLY EXTREME NORTHERN SOUTH DAKOTA LATE WEDNESDAY NIGHT AND THURSDAY. THIS FRONTAL BOUNDARY IS FORECAST TO MOVE OUT OF THE AREA BY THURSDAY EVENING...LEAVING DRY CONDITIONS UNDER WEAK HIGH PRESSURE. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY A FAIRLY STRONG UPPER RIDGE WILL BE THE DOMINANT FEATURE OVER THE PLAINS STATES THROUGHOUT THE EXTENDED PERIOD. THE RIDGE WILL DAMPEN SOME ON MONDAY AS A SHORTWAVE TROUGH SLIDES ACROSS CANADA...BUT THEN BUILDS RIGHT BACK UP ON TUESDAY. A SURFACE FRONT WILL EXTEND FROM EASTERN MONTANA TO CENTRAL NEBRASKA TO THE GREAT LAKES FRIDAY NIGHT. HIGH PRESSURE WILL DROP SOUTH OVER MINNESOTA AND WISCONSIN ON SATURDAY AS LOW PRESSURE STRENGTHENS OVER THE WESTERN DAKOTAS. A WARM FRONT ASSOCIATED WITH THIS LOW PUSHES TO NORTHERN SOUTH DAKOTA ON SUNDAY...THEN FURTHER NORTHWARD AS THE LOW CENTER TRACKS TO THE CENTRAL DAKOTAS SUNDAY NIGHT. THE COLD FRONT TRACKS ACROSS THE CWA MONDAY AND EAST OF THE REGION MONDAY NIGHT...WITH HIGH PRESSURE SLIDING OVER THE NORTHERN PLAINS BEHIND THE EXITING FRONT ON TUESDAY. NOT REAL CONFIDENT IN PRECIPITATION CHANCES WITH EITHER OF THE FRONTAL PASSAGES AS H7 TEMPS WILL BE IN THE +12 TO +18 DEGREE RANGE FROM FRIDAY NIGHT THROUGH MONDAY NIGHT. WILL KEEP SMALL POPS IN ALONG AND NORTH OF THE WARM FRONT SATURDAY NIGHT...AND ALONG THE COLD FRONT SUNDAY NIGHT INTO MONDAY...BUT AGAIN...CONFIDENCE IS NOT HIGH ON PRECIPITATION BEING ABLE TO DEVELOP UNDER THE STRONG CAP. THE WARM TEMPERATURES ALOFT WILL TRANSLATE TO THE SURFACE AS WELL...WITH H85 TEMPS IN THE 20S TO LOWER 30S EVERY DAY EXCEPT TUESDAY. MEX GUIDANCE INDICATING HIGH TEMPERATURES OF 100+ DEGREES ACROSS THE WESTERN CWA SATURDAY THROUGH MONDAY...BUT DUE TO ABUNDANT RAIN AND GREENNESS ACROSS THE AREA...WILL STICK WITH TEMPS IN THE 90S FOR NOW. WILL SEE A TOUCH OF A COOL DOWN ON TUESDAY AS COOLER DRIER AIR MOVES IN IN ASSOCIATION WITH THE SURFACE HIGH. && .AVIATION... SCT -TSRA WILL OCCUR OVER PORTIONS OF THE WESTERN AND SOUTHERN CWA THIS MORNING. OTHERWISE...VFR CONDITIONS UNDER JUST SOME SCT MID LEVEL CLOUDS AOA 8K FEET ARE EXPECTED. THERE IS A CHANCE FOR MORE THUNDERSTORM ACTIVITY THIS EVENING AND OVERNIGHT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...PARKIN AVIATION...PARKIN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 245 AM CDT WED JUL 30 2008 .DISCUSSION... SCATTERED SHOWERS AND STORMS CONTINUE ALONG A MID LEVEL SHEAR AXIS /AS REPRESENTED IN RUC 500MB AND 700MB VORTICITY ANALYSIS/ EXTENDING FROM NORTH CENTRAL OKLAHOMA TO OUR WESTERN CWA AND INTO THE BIG BEND REGION. AS THIS SHEAR ZONE TRANSLATES ACROSS NORTH TEXAS TODAY EXPECT SCATTERED STORMS TO DEVELOP. THERE WILL BE A SLIGHT CHANCE OF STORMS THIS MORNING...WITH BETTER CHANCES THIS AFTERNOON OVER OUR EASTERN AND NORTHEASTERN ZONES. HOWEVER...HIGH TEMPERATURES WILL STILL MANAGE TO BE QUITE HOT THIS AFTERNOON WITH UPPER 90S COMMON AREA WIDE. SCATTERED STORM CHANCES WILL LINGER OVER OUR EASTERN CWA THROUGH TOMORROW EVENING. WHILE SOME OF THE MODELS SUGGEST PRECIP CHANCES WILL CONTINUE THROUGH FRIDAY...WILL MAINTAIN SILENT 10 POPS AT THIS TIME DUE TO UNCERTAINTY. OTHERWISE...CENTER OF THE MID LEVEL RIDGE WILL ANCHOR ITSELF OVER THE OZARKS EARLY NEXT WEEK...ALLOWING FOR TRIPLE DIGIT HEAT TO SETTLE OVER NORTH TEXAS ONCE AGAIN. SCHULTZ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 99 79 99 80 99 / 30 20 20 10 10 WACO, TX 99 79 99 79 99 / 20 20 20 10 10 PARIS, TX 96 73 97 75 96 / 30 20 20 10 10 DENTON, TX 98 75 98 77 98 / 30 20 10 10 10 MCKINNEY, TX 98 73 98 75 98 / 30 20 20 10 10 DALLAS, TX 98 79 99 80 98 / 30 20 20 10 10 TERRELL, TX 99 77 98 77 97 / 30 20 20 10 10 CORSICANA, TX 98 76 96 76 97 / 30 20 20 10 10 TEMPLE, TX 98 76 98 76 96 / 20 20 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 1018 AM MDT WED JUL 30 2008 .UPDATE... UPDATED MORNING FORECAST TO REFLECT TRENDS. && .PREV DISCUSSION... /ISSUED 405 AM MDT WED JUL 30 2008/ SHORT TERM... (TODAY AND TONIGHT) FORECAST CONCERNS FOR TODAY AGAIN REVOLVE AROUND POPS. ANOTHER SHORTWAVE...EVIDENT IN WV PICS AND RUC H2-H3 PV FIELDS...IS LOCATED OVER THE GREAT BASIN MOVING INTO WRN CO. ONCE AGAIN MODELS DRAG THIS FEATURE ACROSS THE AREA DURING THE AFTERNOON HOURS. WARMER/DRIER AIR MASS WILL BE ADVECTING INTO THE AREA FROM THE WEST WITH H7 TEMPS APPROACHING +18 TO +20C OUT WEST...AND +15 TO +18C FOR THE EASTERN PLAINS. THIS WILL MEAN A MODEST WARM UP FOR THE MOUNTAINS (BY A COUPLE DEGREES OR SO) TO SEVERAL DEGREES WARMER ACROSS THE PLAINS AND ADJACENT I-25 CORRIDOR. MODELS DRY OUT THE SFC DEW POINTS DROPPING THEM INTO THE 20S AND 30S FOR THE MTS AND WEST...WITH SOME 40S NEAR THE CO KS BORDER. C51ENGE WILL BE HOW FAR EAST THE LOW LVL MOISTURE MIXES OUT. ONCE AGAIN DISCREPANCIES EXIST BETWEEN THE GFS/NAM QPF FIELDS WITH NAM BREAKING OUT SOME LIGHT QPF ACROSS THE MTS/ADJACENT I-25 CORRIDOR...AND ACROSS SOUTHERN SLOPES OF THE PALMER DIVIDE DURING THE AFTN...WHILE GFS AND UKMET KEEPS IT DRY. ECMWF PRINTS OUT SOME VERY LIGHT QPF ACROSS THE CEN MTS. GIVEN THE PRESENCE OF A SHORTWAVE AND THE FACT THAT MODELS WERE TOO QUICK TO DRY OUT THE LOW LEVELS ACROSS THE PLAINS YESTERDAY ALLOWING THUNDERSTORMS TO FORM AND SPREAD ACROSS THE PLAINS DURING THE EVENING...ITS DIFFICULT TO GO WITH 0 POPS FOR THE PLAINS JUST YET. THUS HAVE SPREAD SOME LOW GRADE ISOLATED POPS FOR JUST ABOUT EVERYWHERE TODAY. EARLIER TIMING OF SHORTWAVE WOULD SUGGEST THUNDERSTORMS MAY DEVELOP MORE QUICKLY TODAY THAN YESTERDAY. MAIN THREAT WITH THUNDERSTORMS WILL BE GUSTY WINDS AND LIGHTNING...WITH LIGHT TO MODERATE RAINFALL POSSIBLE IN SPOTTY AREAS. THUNDERSTORMS SHOULD DIMINISH DURING THE EVENING...WITH LOSS OF HEATING AND AS SHORTWAVE EXITS EASTERN CO. MIN TEMPS SHOULD BE ON THE COOL SIDE ONCE AGAIN FOR MOUNTAIN VALLEY LOCATIONS GIVEN DRIER AIR MASS AND CLEAR SKIES ALLOWING FOR EFFICIENT RADIATIONAL COOLING. -KT LONG TERM... (THURSDAY THROUGH TUESDAY) UPR RIDGE WL BE CENTERED OVR THE AREA THU THRU SAT WITH H7 TEMPS RANGING FROM AROUND 16-22C. HIGH TEMPS OVR THE SERN PLAINS THU THRU SAT WL BE IN THE 90S TO LOWER 100S...WITH 80S GENERALLY OVR THE HIGH VALLEYS. A COUPLE RECORD TEMPS MAY BE BROKEN OR TIED ON FRI. IT WL BE FAIRLY DRY OVR THE AREA...BUT WE WL PROBABLY STILL SEE SOME ISOLD SHOWERS/TSTMS DEVELOP OVR THE MTS EACH DAY. THE UPR RIDGE SHIFTS EWRD FOR SUN THRU TUE...AND THE S TO SW FLOW OVR WRN PORTIONS OF THE FORECAST AREA LOOKS LIKE IT WL DRAW MONSOON MSTR BACK OVR THESE AREAS...ESPECIALLY FOR MON AND TUE...WHICH WL LEAD TO BETTER CHANCES FOR PCPN OVR THE MTS AND HIGH VALLEYS...WHILE OVR THE FAR SE PLAINS THE WEA STILL LOOK AS THOUGH IT WL BE DRY. TEMPS SHOULD BE ONLY A LITTLE COOLER MON AND TUE. AVIATION... ISOLATED THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS AFTER 18Z...AND SPREAD ACROSS THE PLAINS AFTER 20Z. VFR CIGS...ERRATIC GUSTY WINDS UP TO 45 MPH AND LIGHTNING WILL BE THE PRIMARY THREATS. THUNDERSTORMS WILL END DURING THE EVENING HOURS WITH CLEARING SKIES AND LIGHT DIURNALLY DRIVEN WINDS EXPECTED OVERNIGHT. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 14/34 co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1132 AM EDT WED JUL 30 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW SPINNING JUST NORTH OF LAKE SUPERIOR OVER CENTRAL ONTARIO. CONSIDERABLE DRY AIR INTRUSION CAN BE SEEN MOVING INTO THE DRY SLOT AND OVER THE FORECAST AREA THIS MORNING. A WEAK SHORTWAVE IS SWEEPING ACROSS THE FORECAST AREA WHILE ROTATING THROUGH THE BASE OF THE LOW. A RIDGE IS BUILDING OVER MANITOBA. A SURFACE LOW IS OVER EAST CENTRAL ONTARIO WITH A FRONTAL BOUNDARY EXTENDING SOUTH INTO CENTRAL LOW MICHIGAN THEN WEST INTO THE NORTHERN PLAINS. A SURACE RIDGE IS ALSO BUILDING OVER MANITOBA STETCHING INTO THE FORECAST AREA. PROVIDING SOME SUN ACROSS THE AREA. .SHORT TERM... AS THESE FEATURES SHIFT EAST TODAY...MORE DRIER AIR AND SUN WILL PREVAIL OVER THE AREA WHICH WILL CONTRIBUTE TO LAKE BREEZES DEVELOPMENT. THE HI RES SHORT TERM MODELS SHOW THE STRONGEST LAKE ALONG LAKE SUPERIOR EAST OF MARQUETTE TO GRAND MARAIS THIS AFTERNOON. THUS STONGEST LAKE BREEZE CONVERGENCE WILL BE FROM MANISTIQUE EASTWARD...WITH WEAKER CONVERGENCE ZONE NEAR MARQUETTE...AND ALONG THE LAKE MICHIGAN SHORE FROM MENOMINEE TO MANISTIQUE. THESE HAVE THE POTENTIAL OF PRODUCING SOME ISOLATED SHOWERS AND POSSIBLE A THUNDERSTORM OR TWO. THIS IS CONVEYED ALREADY IN THE GRIDS. CURRENT TEMPERATURE GRIDS ARE VERIFYING FAILY CLOSE AT THIS TIME. CONSIDERING THE TRAJECTORY FORECASTS TEMPERATURES SHOULD REACH TO AROUND 80 OVER MOST OF THE INTERIOR OF THE U.P. AND LAKE BREEZES WILL LIMIT HEATING NEAR THE LAKE SHORE. THE CONVERGENCE ZONE WILL ALSO PRODUCE MORE CLOUDS AND SLOW HEATING. CURRENT ZONE FORECAST LOOKS REASONABLE. NO UPDATES NEEDED AT THIS TIME. .LONG TERM... WITH A HIGH AMPLITUDE RIDGE SETTING UP OVER THE SOUTHWESTERN UNITED STATES THROUGH MINNESOTA BY 06Z THURSDAY...A MAJORITY OF THE CLOUDS WILL BE SHUNNED TO THE EAST. OVERNIGHT TEMPERATURES WEDNESDAY NIGHT INTO THURSDAY SHOULD BE ROUGHLY 5 DEGREES COOLER THAN WHAT IS BEING EXPERIENCED THIS MORNING. 850MB TEMPERATURES WILL NOT FALL TOO DRAMATICALLY FROM 12Z WEDNESDAY TO 12Z THURSDAY...GENERALLY FROM 12-13C TO 10-11C. HAVE OPTED TO GO A LITTLE MORE OPTIMISTIC WITH REGARDS TO SKY COVER...LESSENING THE PERCENTAGE MORE THAN MODEL GUIDANCE. WOULD NOT BE SURPRISED IF TEMPERATURES DROP A COUPLE MORE DEGREES OVER THE SOUTHWEST INTERIOR CWA. AS FOR MODEL GUIDANCE...PROBLEMS CONTINUE WITH A VARIETY OF SOLUTIONS TO SELECT FROM. LATEST GFS SCENARIO WOULD RESULT IN MORE NW FLOW...WITH COOLER TEMPERATURES FIGURED THAT OUR ONGOING FORECAST. THIS MAY INHIBIT SOME OF THE STRONGER THUNDERSTORMS WITH OUR PREVIOUS THINKING. HOWEVER...THE GFS WAS NOT BACKED BY THE NAM OR ECMWF. THE ECMWF WAS GENERALLY THE PREFERRED MODEL. AS A RESULT...HAVE ADDED IN SLIGHT CHANCE SHOWERS AND THUNDERSTORMS FOR MUCH OF THE CWA FRIDAY AFTERNOON. THIS WAS NOT A PART OF THE GFS...AS THE GFS DOES A TYPICAL DIVIDE OF PRECIPITATION JUST TO OUR WEST...WITH MUCH OF THE SHOWERS REMAINING TO OUR SOUTH. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... WINDS DROPPED OFF LIGHTER THAN EXPECTED AT SAW...AND AS A RESULT VLIFR VIS AND LIFR CIG DEVELOPED THERE AROUND 08Z. HOWEVER...DRIER AIR WORKING IN FROM THE WEST DISSIPATED THE FOG AND BR BY 11Z. EXPECT SOME DAYTIME CUMULUS CLOUDS TO DEVELOP AT BOTH TAF SITES THIS MORNING. CMX MAY ALSO GET INTO SOME MVFR CIG CLOUDS ROTATING AROUND LOW PRESSURE OVER NORTHERN ONTARIO THIS MORNING...BUT OTHERWISE VFR CONDITIONS ARE PLANNED INTO THIS EVENING. GUSTY WINDS ARE ALSO EXPECTED TODAY AT BOTH SITES...AND ESPECIALLY AT CMX WHERE LAKE BREEZE ENHANCEMENT OCCURS. AFTER MIDNIGHT...ANOTHER COLD FRONT OVER NORTHERN ONTARIO IS EXPECTED TO DROP SOUTH THROUGH THE TAF SITES. LOW CLOUDS...WITH MVFR TO LIFR CIGS...CURRENTLY EXIST AROUND THE FRONT. SOME OF THESE CLOUDS MAY MIX OUT TODAY WITH HEATING...BUT AM WORRIED THAT THEY WILL REFORM TONIGHT WITH COOLING. RIGHT NOW HAVE INCLUDED MVFR CIGS AT BOTH TAF SITES UNDER THE EXPECTATION OF REFORMING...BUT LOWER CIGS MAY OCCUR. FUTURE FORECASTS WILL NEED TO MONITOR. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A BREEZY WSW WIND IS EXPECTED TODAY ON WESTERN LAKE SUPERIOR...WITH SPEEDS UP TO 25 KT...IN THE WAKE OF THE COLD FRONT THAT PASSED ACROSS LAKE SUPERIOR DURING THE NIGHT. WINDS WILL DIMINISH ACROSS LAKE SUPERIOR TONIGHT AS HIGH PRESSURE BUILDS IN...WITH SPEEDS LIKELY BELOW 15 KT FOR THU NIGHT. WIND FORECAST A LITLE MORE COMPLICATED BEYOND THU NIGHT WITH MANY MODEL DIFFERENCES. GENERAL CONSENSUS SUGGESTS A COLD FRONT OR TROUGH DROPPING SOUTH ACROSS LAKE SUPERIOR LATE FRI...WITH HIGH PRESSURE BUILDING OVER LAKE SUPERIOR BY SAT MORNING. THIS HIGH THEN SLOWLY HEADS OFF TO THE EAST FOR SAT NIGHT INTO SUN AS A COLD FRONT APPROACHES FROM THE NORTHERN PLAINS. NO MATTER WHAT HAPPENS TO THE MOVEMENT OF THESE FEATURES...WIND SPEEDS SHOULD STILL END UP AT OR BELOW 20 KT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...KF AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 540 AM CDT WED JUL 30 2008 .DISCUSSION... IN THE SHORT TERM...MUCH DRIER AIRMASS HAS PUSHED ACROSS AREA WITH 00Z MPX RAOB SHOWING PWATS DOWN TO .60 VS. THE 1.7 INCHES AT 12Z. HOWEVER...ISOL SHOWERS AND TSTMS HAVE BEEN DEVELOPING IN SODAK TOWARD EXTREME SW MN LAST HOUR OR TWO. 00Z GFS PICKED UP ON POCKET OF ELEVATED INSTABILITY IN AREA OF SHOWER DEVELOPMENT. WV IMAGERY ALSO SHOWS A WEAK CONVECTIVELY INDUCED DISTURBACE WHICH CAME OUT OF COLORADO WHICH HAS HELPED CONVECTION ALONG. INTRODUCED SOME ISOL MORNING TSTMS IN EXTREME SW PORTIONS AND RETAINED THE SLIGHT CHANCE POPS IN THAT AREA FOR THE AFTERNOON. IN THE BIGGER PICTURE A SERIES OF RATHER STRONG TROFS MOVE ACROSS CANADA DURING THE PERIOD AS UPPER RIDGE BUILDS INTO THE CENTRAL U.S. DURING THE WEEKEND. THIS WILL MAINTAIN A FAIRLY TIGHT BAROCLINC ZONE ACROSS THE AREA. FRONT WHICH MOVED THROUGH THE AREA YESTERDAY WILL BEGIN TO MOVE BACK NORTH AGAIN TONIGHT/THURSDAY AHEAD OF TROF NOW PUSHING ACROSS THE NORTHERN ROCKIES. SHUD SEE SCT TSTMS LATE TONIGHT SW 1/2 CWA AS LLJ POKES ACROSS NEBRASKA TOWARD SW MN. MID LEVEL INSTABILITY INCREASES ACROSS SW INTO CENTRAL MN IN AREA OF DIFLUENT 850MB TO 300MB THICKNESS. MID LEVELS GET PRETTY WARM IN SW MN BY 18Z THURSDAY WITH 700 MB TEMPS AS WARM AS 15C...BUT QUITE A BIT OF COOLING BY 00Z FRIDAY AS UPPER TROF MOVES INTO AREA. SPREAD POPS EAST THURSDAY AFTERNOON AND THURSDAY NIGHT AS LLJ TRANSLATES EAST AHEAD OF TROF. 850MB TEMPERATURES BEGIN TO WARM A BIT OVER THE WEEKEND AS UPPER RIDGE BUILDS...BUT EASTERLY TRAJECTORIES OUT OF SURFACE HIGH PRESSURE SHOULD KEEP DEWPOINTS FROM GETTING OUT OF HAND. KEPT IN THE SLIGHT CHANCE POPS FOR THE WEEKEND...BUT WITH UPPER RIDGE BUILDING INTO AREA MAY NEED TO CUT THEM BACK. && .AVIATION.../12Z TAF ISSUANCE/ SHOULD BE QUIET WEATHER DURING TAF PERIOD. WEAK SHORT WAVE DROPPING ACROSS SOUTHEAST SOUTH DAKOTA THIS MORNING WILL AFFECT THE SOUTHWEST CORNER OF MN DURING THE EARLY PERIOD. RUC IS ADAMANT IN KEEPING CONVECTION GOING INTO THE AFTERNOON. KRWF WOULD BE THE ONLY AFFECTED AREA. WILL KEEP TAF DRY FOR NOW...AS APPEARS BOTH NAM/GFS DROP ACTIVITY OFF TO THE SOUTH OF THE AREA. THEN SOME HIGH CLOUDS ALONG WITH SPOTTY CUMULUS EXPECTED ACROSS MUCH OF AREA TODAY...WITH WIND GENERALLY NWLY IN DIRECTION AND 10 KTS OR LESS. SURFACE BOUNDARY OVER SOUTHERN MN WILL LIKELY LIFT SLOWLY NORTH LATER TONIGHT AND THURSDAY...INCREASING CHANCES FOR PCPN...MAINLY OVER THE SOUTHWEST CWA AGAIN. HAVE OPTED TO KEEP KRWF DRY FOR NOW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ BAP/DWE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 547 AM CDT WED JUL 30 2008 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... CIRCULATION CENTER ASSCD WITH THE REMNANTS OF DOLLY HAS SHIFTED INTO SERN KS WITH AN ELONGATED SHEAR AXIS EXTENDING NE INTO CENTRAL/NORTH CENTRAL MISSOURI. LATEST GFS/RUC APPEAR TO HAVE A MUCH BETTER HANDLE ON THE SITUATION AS THE NAM QPF HAS BEEN MUCH TOO FAR NORTH OVERNIGHT. A RATHER SHARP H7/H5 DEFORMATION ZONE HAS LIMITED THE NWD EXTENT OF THE HEAVY PRECIP SHIELD...FM KC AREA ENE TO NR MACON. THIS IS WELL HANDLE BY THE GFS WITH THE GFS TO SHIFT THIS AXIS SLOWLY SE THROUGH THE DAY. A VERY IMPRESSIVE H8/H7 THETAE RIDGE WAS POSITION NR THE DEFORMATION ZONE WITH COPIOUS AMOUNT OF TROPICAL MOISTURE...2-2.5 PRECIPITABLE WATER...RESULTING IN VERY HEAVY RAINFALL AMOUNTS. CLOUD TOPS HAVE WARMED THE LAST FEW HOURS AS THE LLJ HAS VEERED. HOWEVER...EXCESSIVE RAINFALL AMOUNTS ARE STILL LIKELY THIS MORNING BEFORE SYSTEM BEGINS TO WEAKEN AND BEGIN ITS DIURNAL DECREASE IN THE AFTN. SINCE RADAR TRENDS VERIFY THE LATEST GFS...HAVE REMOVED THE XTRM NRN EXTENT OF THE FFA. OTHERWISE...HAVE CONCERN ABOUT LOW CLOUDS AND FOG TNGT. MORE CONFIDENT IN AREAS OF FOG AFTER MIDNIGHT IN AREAS WHICH HAVE RECEIVED THE HEAVY RAIN TODAY. UPPER RIDGE OF HIGH PRESSURE TO BUILD INTO THE REGION THURSDAY AND FRIDAY WITH VERY WARM TEMPERATURES RETURNING. DB && .AVIATION... INTERMITTENT MVFR/IFR CONDITIONS ARE EXPECTED THIS MORNING ASSOCIATED WITH THE PRECIPITATION SHIELD. THE PRECIPITATION SHIELD WILL GRADUALLY SHIFT SOUTHEAST WITH THE LOW CLOUD DECK TO RISE TO THE VFR CATEGORY BY EARLY TO MID AFTERNOON. NEXT CONCERN IS LATE TONIGHT. SKIES WILL CLEAR TONIGHT...AND WITH LIGHT WINDS...A MOIST AIR MASS AND WET GROUND...MVFR AND IFR CONDITIONS IN FOG ARE LIKELY. DB && .EAX WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL 1 PM WEDNESDAY FOR MOZ017-MOZ021-MOZ022- MOZ023-MOZ024-MOZ025-MOZ028-MOZ029-MOZ030-MOZ031-MOZ032- MOZ033-MOZ037-MOZ038-MOZ039-MOZ040-MOZ043-MOZ044-MOZ045- MOZ046-MOZ053-MOZ054. KS...FLASH FLOOD WATCH UNTIL 1 PM WEDNESDAY FOR KSZ057-KSZ060-KSZ103- KSZ104-KSZ105. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1039 AM EDT WED JUL 30 2008 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL CROSS THE AREA LATE THIS AFTERNOON AND EVENING BRINGING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. A COLD FRONT WILL SWING THROUGH THE REGION ON THURSDAY, CONTINUING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. FRIDAY WILL BE PARTLY SUNNY AND SEASONAL FOLLOWED BY COOLER AND UNSETTLED WEATHER FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CURRENT FORECAST ON TRACK WITH JUST MINOR CLOUD/TEMP GRID TWEAKS. CONVECTION OVER SOUTHERN ONTARIO CONTINUES TO WEAKEN AS IT APPROACHES WESTERN NEW YORK. BOTH LATEST NAM/RUC INDICATE BEST SHORT WAVE LIFT OCCURS LATE THIS AFTERNOON THROUGH EARLY EVENING. BUF 12Z RAOB SHOWS DECENT CAP AROUND 700 MB WHICH IS ALSO DEPICTED ON 06Z NAM MODEL SOUNDINGS. THIS FEATURE ALONG WITH DRY LOW LEVELS WILL SUPPRESS CONVECTION UNTIL SHORT WAVE ERODES CAP AND DEW POINTS RISE INTO THE MID 60S LATER TODAY. DUE TO WEAK BULK SHEAR VALUES, WEAK MID LEVEL WIND FIELDS AND CAPES AROUND 600-900 J/KG, SEVERE POTENTIAL LOOKS LOW. ALTHOUGH, COMBINATION OF COLD POOL ALOFT WITH MID LEVEL DRY AIR A FEW STRONGER CELLS COULD PRODUCE SMALL HAIL. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... SEVERE POTENTIAL LOOKS LOW AGAIN THURSDAY. NAM CAPES ARE REASONABLE WITH FORECAST VALUES AROUND 600-900 J/KG. GFS APPEARS FAR TOO UNSTABLE AGAIN, WITH DEW POINTS IN EXCESS OF 70F MOST LOCALES. THE MORE CONSERVATIVE NAM, COMBINED WITH A WEAK WIND FIELD, DOES NOT INDICATE MUCH POTENTIAL FOR WIDESPREAD SEVERE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... UPR RDG OVER THE CNTRL US WITH THE FCST AREA IN THE NW FLOW EAST OF THE RDG THRU THE PD. WITH THE AXIS OF THE TROF WELL EAST OF THE AREA...SLGT CHANCE POPS SEEM TO BE ABOUT THE HIGHEST WE CAN XPCT AS THE RDG TRIES TO NOSE IN. PRVS FCST TEMPS WERE WELL ABV NRML...AND ABV SURROUNDING WFO/S SO HAVE ADJUSTED TEMPS DOWN A FEW DEGREES IN BETTER COLLABORATION AND CLSR TO NRML GIVEN THE TROF AND RDG PSN. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... OUTSIDE OF VLIFR EARLY MORNING FG AT ELM...ALL SITES VFR ATTM AND LIKELY TO REMAIN THAT WAY THROUGH THE MORNING AND INTO THE EARLY AFTERNOON. HAVE INCLUDED CB GROUPS THIS AFTERNOON FOR CONVECTIVE POTENTIAL. WIDESPREAD CONVECTION DOES NOT LOOK LIKELY AT THIS TIME...BUT SOME BRIEF MVFR/IFR CONDITIONS ARE POSSIBLE AS SHRA/TSRA DEVELOP LATE THIS AFTERNOON. TONIGHT...COULD BE A FEW LINGERING SHRA...BUT GENERALLY VFR CONDITIONS WITH THINNER /MVFR/ FOG POSSIBLE AT ELM AGAIN TOWARDS DAYBREAK. SOUTHERLY WINDS 5-10KTS TODAY WILL BECOME SOUTHWESTERLY AROUND 5KTS TONIGHT. OUTLOOK... THURSDAY THROUGH THURSDAY NIGHT...CHC FOR SHRA/TSRA WITH RESTRICTIONS. FRIDAY...VFR WITH POTENTIAL IFR/MVFR FOG AT ELM IN THE MORNING. SATURDAY...MORNING MVFR/IFR FOG POSSIBLE AT ELM. CHC AFTERNOON MVFR/IFR SHRA/TSRA. SUNDAY...VFR WITH POTENTIAL IFR/MVFR FOG AT ELM IN THE MORNING. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...RRM NEAR TERM...RRM SHORT TERM...DJP LONG TERM...DGM AVIATION...JMA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1115 AM EDT WED JUL 30 2008 .SYNOPSIS... WEAK PRESSURE GRADIENT REMAINS ACROSS THE AREA THROUGH EARLY WEDNESDAY. A COLD FRONT WILL MOVE THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY. HIGH PRESSURE WILL BUILD IN THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE AND RADAR DATA SUPPORT THE 12Z NAM AND RUC FOR THIS AFTERNOON AND EVENING. ONE VORT ACROSS NORTH-CENTRAL OHIO WILL CLIP OUR NORTHERN COUNTIES AS IT MOVES EAST...WHILE ANOTHER VORT OVER WESTERN KENTUCKY WILL MOVE EASTWARD ACROSS OUR CENTRAL AND SOUTHERN AREAS. THE PROBLEM IS...WITH THE WEAK DYNAMICS AND FLOW WITH THESE VORTS...HEATING AND MOISTURE WILL BE THE MAIN PLAYERS FOR CONVECTION. MID TO HIGH CLOUDS ARE INVADING FROM THE WEST FROM DIURNALLY DYING CONVECTION FROM THE KENTUCKY VORT...AND IS SUPPORTED BY PW`S NEAR 2 INCHES...SO WILL LIKELY HOLD TOGETHER AS IT OVERSPREADS THE WESTERN HALF OF THE AREA THIS AFTERNOON. THIS WILL ACT TO LIMIT THE HEATING POTENTIAL AND CONVECTIVE REDEVELOPMENT OVER WESTERN HALF OF OUR AREA. ON THE OTHER HAND...WILL NOT TAKE MUCH HEATING IN THE MOIST ADIABATIC ATMOSPHERE THIS AFTERNOON TO GENERATE SCATTERED CONVECTION. SO...BEST POPS WILL ACTUALLY BE IN THE EAST AND SOUTH WHERE BEST HEATING WILL INTERACT WITH THE VORTS. WILL GO LIKELY THERE AND CHANCE ELSEWHERE. OTHERWISE...LOWERED TEMPS A FEW DEGREES IN THE WEST WITH ALL THE CLOUDS. PREVIOUS DISCUSSION BELOW... UPPER AND MID LEVEL CLOUDS ASSOCIATED WITH DYING MCS ACROSS THE OH VALLEY WILL CONTINUE TO MOVE ACROSS THE AREA TODAY. THESE CLOUDS WILL KEEP TEMPERATURES INTO THE MID 80S LOWLANDS...RANGING TO THE MID 70S HIGHEST ELEVATIONS. BREAKS IN THE CLOUDS COULD PRODUCE SOME DIFFERENTIAL HEATING BOUNDARIES THAT COULD SERVE AS FOCUS MECHANISM FOR AFTERNOON SHOWERS AND THUNDERSTORMS UNDER A MARGINALLY UNSTABLE ATMOSPHERE WITH CAPE VALUES AROUND 1800 J/KG. IN ADDITION...BOTH GFS AND NAM BRING A SHORT WAVE EVIDENT AS H5 VORT MAXES MOVING FROM NORTHWEST TO SOUTHEAST THIS AFTERNOON AND EVENING. KEPT CHANCE POPS ACROSS THE ENTIRE AREA AS IT IS DIFFICULT TO PINPOINT THE LOCATIONS OF WHERE DIFFERENTIAL HEATING BOUNDARIES WILL OCCUR. WITH THE AMOUNT OF CLOUDS EXPECTED...WENT COOLER THAN MET AND MAV...ACTUALLY CLOSER TO THE LAV GUIDANCE FOR HIGHS THIS AFTERNOON. TONIGHT LOWS WERE A BLEND OF MET AND MAV NUMBERS. ANY PREDAWN FOG AND LOW CLOUDS WILL BURN OFF SHORTLY AFTER SUNRISE. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... UPPER LEVEL TROUGH AXIS ORIENTED ALONG THE OHIO RIVER WILL SWING SOUTHEASTERLY THROUGH THE AREA THURSDAY...AS WILL THE POTENT SURFACE TROUGH. STILL LOOKING AT A SCENARIO WITH HIGH PRECIPITABLE WATER VALUES IN THE NEIGHBORHOOD OF 2.0 INCHES...AND A SLOW PROGRESSION OF THE INSTABILITY. WILL HAVE TO CLOSELY MONITOR AREAS THAT GET MULTIPLE THUNDERSTORMS AND THEIR HIGH PRECIPITATION RATES...AS ANY SORT OF TRAINING COULD EASILY RESULT IN WATER ISSUES FOR URBAN AREAS AND SMALL STREAMS. BEYOND THURSDAY...UPSTREAM 596HPA RIDGE WILL PROGRESS EASTWARD FROM THE CENTRAL PLAINS TOWARDS THE MISSISSIPPI RIVER VALLEY...AND THE HEAT WILL BE ON. BY THE BEGINNING OF THE WEEKEND...LOW 90S WILL NOT BE OUT OF THE QUESTION. ECMWF AND GFS DIVERGE IN THEIR SOLUTIONS REGARDING THE LOCATION OF AN UPPER LEVEL TROUGH TO THE NORTHEAST. EUROPEAN PUTS THIS FEATURE FURTHER NORTHEAST IN THE MARITIMES OF CANADA...WHILE THE GFS IS FURTHER SOUTHWEST. THIS WILL BE CRUCIAL IN DETERMINING THE EXTENT OF THE HEAT BUILDING IN FOR THE WEEKEND. TEMPERATURES ARE KEPT WITHIN GUIDANCE BLENDS FOR THE SHORT TERM FORECAST. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... FOLLOWED HPC THINKING IN THE EXTENDED RANGE. DRY WEATHER PATTERN CONTINUES INTO THE WEEKEND AND EARLY NEXT WEEK AS RIDGE AT SURFACE AND ALOFT BUILD OVER CWA. BY SUNDAY AND MONDAY...HOT AND HUMID PATTERN ENVELOPS REGION AS H8 TEMPS RISE TO 22-24C RESULTING IN DAYTIME MAX/S IN THE MID-UPPER 90S. TEMPS BACK DOWN A COUPLE DEGREES ON TUESDAY AS CREST OF RIDGE ALOFT DRIFTS SOUTHWARD. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... 15Z WEDNESDAY THRU 12Z THURSDAY... VERY MOIST AND UNSTABLE ATMOSPHERE WILL BRING THREAT OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS...MAINLY THIS AFTERNOON AND EARLY TONIGHT. BEST CHANCES ARE IN THE EAST AND SOUTH WHERE CLOUDS WILL BE LEAST AND ALLOW FOR HEATING. EXPECT LOTS OF MID TO HIGH CLOUDS WEST OF A PKB TO CRW LINE THIS AFTERNOON AND TONIGHT TO LIMIT CONVECTION. THUS...MENTIONED ONLY CB AT PKB...HTS AND CRW WITH NO TEMP PERIOD FRO THUNDER. INCLUDED TEMP PERIOD 19Z-23Z OF THUNDER AT EKN...BKW...AND CKB. OTHERWISE...GENERALLY VFR OUTSIDE THE CONVECTION THIS AFTERNOON AND EVENING. OVERNIGHT...VERY DIFFICULT...AS CONVECTION WILL LIKLEY DIMINISH GREATLY WITH LOSS OF HEATING...BUT FOG MAY BE AN ISSUE WHERE IT RAINS THIS AFTERNOON. THUS...WITH GREAT UNCERTAINTY...DECIDED NOT TO ADDRESS FOG OVERNIGHT. AVIATION OUTLOOK /AFTER 12Z THU/...STRONG THUNDERSTORMS WITH IFR CONDITIONS AND STRONG GUSTY WINDS POSSIBLE THUR EVENING INTO FRI ACROSS MAINLY ACROSS THE NORTHERN SITES...PKB AND CKB. NO SIGNIFICANT WEATHER FORECAST FRI AFTERNOON THRU SUN. && .CLIMATE... THE ENTIRE CLI FOR EKN IS MISSING AGAIN. && .EQUIPMENT... NO CHANGE IN THE STATUS AT EKN UNTIL WED AT THE EARLIEST THUS NIL AMD CONTINUES IN THE EKN TAF. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...26/ARJ NEAR TERM...JMV SHORT TERM...26 LONG TERM...JKF AVIATION...JMV CLIMATE... EQUIPMENT... oh AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1028 AM CDT WED JUL 30 2008 .UPDATE... LINE OF SHOWERS AND THUNDERSTORMS THAT MOVED OVER PARTS OF THE NORTHWESTERN HALF OF THE CWA THIS MORNING CONTINUE TO DIMINISH AT THIS HOUR. A FEW SMALL SHOWERS CONTINUE TO DEVELOP WEST OF THE I-35 CORRIDOR AND NORTH OF I-20 BUT MUCH OF THE AFTERNOON LOOKS TO BE DRY. CHANCE CONTINUES FOR THE REST OF THE DAY THAT ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP AND WILL CONTINUE WITH 20 POPS FOR MUCH OF THE AFTERNOON OVER ALL THE AREA. BY LATER THIS AFTERNOON/EARLY EVENING...MODELS ARE INDICATING ANOTHER REFIRING OF SHOWERS AND STORMS ACROSS THE WESTERN HALF OF THE CWA. HAVE INCREASED POPS TO 30 PERCENT AFTER 22Z AND MAY HAVE TO ADJUST HIGHER FOR TONIGHT. OTHERWISE CURRENT FORECAST IS ON TRACK AND ADJUSTED BASED ON CURRENT TRENDS. DID MAKE A FEW MINOR TWEAKS TO TEMPERATURES...TO INCREASE A DEGREE OR TWO IN THE WEST AND DECREASE A DEGREE IN THE NORTHEAST. 82/JLD && .AVIATION... A SHEAR AXIS WILL REMAIN OVER NORTH TEXAS THROUGH THURSDAY. WEAK LARGE SCALE LIFT COUPLED WITH MID LEVEL MOISTURE WILL BRING SCATTERED SHOWERS/STORMS TO THE METROPLEX TAF SITES THIS MORNING. A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS AFTERNOON/EVENING AND SHOULD PROVIDE A FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS. THE MAIN FORECAST CHALLENGE WILL BE TIMING OF THE STORMS AT THE TAF SITES. WILL SEE A FEW STORMS AT TAF ISSUANCE NEAR FTW/DFW/AND AFW AND SHORTLY AFTER AT DAL. WILL BRING THUNDERSTORM CHANCES BACK TO ALL TAF SITES LATE THIS AFTERNOON WHEN THE COLD FRONT GETS A BIT CLOSER. OTHERWISE...EXPECT VFR CONDITIONS WITH MAINLY SCATTERED TO BROKEN MID LEVEL CLOUDS AND A SOUTH WIND BETWEEN 8 AND 14 KNOTS. .79... && .PREV UPDATE... QUICK UPDATE TO INCREASE POPS OVER OUR NORTH CENTRAL/NORTHEAST ZONES THROUGH 18Z GIVEN CURRENT RADAR TRENDS AND EXPECTED PRECIP EVOLUTION. UPDATES AVAILABLE SHORTLY. SCHULTZ && .PREV DISCUSSION... /ISSUED 245 AM CDT WED JUL 30 2008/ SCATTERED SHOWERS AND STORMS CONTINUE ALONG A MID LEVEL SHEAR AXIS /AS REPRESENTED IN RUC 500MB AND 700MB VORTICITY ANALYSIS/ EXTENDING FROM NORTH CENTRAL OKLAHOMA TO OUR WESTERN CWA AND INTO THE BIG BEND REGION. AS THIS SHEAR ZONE TRANSLATES ACROSS NORTH TEXAS TODAY EXPECT SCATTERED STORMS TO DEVELOP. THERE WILL BE A SLIGHT CHANCE OF STORMS THIS MORNING...WITH BETTER CHANCES THIS AFTERNOON OVER OUR EASTERN AND NORTHEASTERN ZONES. HOWEVER...HIGH TEMPERATURES WILL STILL MANAGE TO BE QUITE HOT THIS AFTERNOON WITH UPPER 90S COMMON AREA WIDE. SCATTERED STORM CHANCES WILL LINGER OVER OUR EASTERN CWA THROUGH TOMORROW EVENING. WHILE SOME OF THE MODELS SUGGEST PRECIP CHANCES WILL CONTINUE THROUGH FRIDAY...WILL MAINTAIN SILENT 10 POPS AT THIS TIME DUE TO UNCERTAINTY. OTHERWISE...CENTER OF THE MID LEVEL RIDGE WILL ANCHOR ITSELF OVER THE OZARKS EARLY NEXT WEEK...ALLOWING FOR TRIPLE DIGIT HEAT TO SETTLE OVER NORTH TEXAS ONCE AGAIN. SCHULTZ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 99 79 99 80 99 / 30 30 20 10 10 WACO, TX 99 79 99 79 99 / 30 30 20 10 10 PARIS, TX 95 73 97 75 96 / 20 30 20 10 10 DENTON, TX 98 75 98 77 98 / 30 30 10 10 10 MCKINNEY, TX 98 73 98 75 98 / 30 30 20 10 10 DALLAS, TX 98 79 99 80 98 / 30 30 20 10 10 TERRELL, TX 99 77 98 77 97 / 30 30 20 10 10 CORSICANA, TX 98 76 96 76 97 / 20 30 20 10 10 TEMPLE, TX 98 76 98 76 96 / 20 30 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/82 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 705 AM CDT WED JUL 30 2008 .UPDATE... QUICK UPDATE TO INCREASE POPS OVER OUR NORTH CENTRAL/NORTHEAST ZONES THROUGH 18Z GIVEN CURRENT RADAR TRENDS AND EXPECTED PRECIP EVOLUTION. UPDATES AVAILABLE SHORTLY. SCHULTZ && .AVIATION... A SHEAR AXIS WILL REMAIN OVER NORTH TEXAS THROUGH THURSDAY. WEAK LARGE SCALE LIFT COUPLED WITH MID LEVEL MOISTURE WILL BRING SCATTERED SHOWERS/STORMS TO THE METROPLEX TAF SITES THIS MORNING. A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS AFTERNOON/EVENING AND SHOULD PROVIDE A FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS. THE MAIN FORECAST CHALLENGE WILL BE TIMING OF THE STORMS AT THE TAF SITES. WILL SEE A FEW STORMS AT TAF ISSUANCE NEAR FTW/DFW/AND AFW AND SHORTLY AFTER AT DAL. WILL BRING THUNDERSTORM CHANCES BACK TO ALL TAF SITES LATE THIS AFTERNOON WHEN THE COLD FRONT GETS A BIT CLOSER. OTHERWISE...EXPECT VFR CONDITIONS WITH MAINLY SCATTERED TO BROKEN MID LEVEL CLOUDS AND A SOUTH WIND BETWEEN 8 AND 14 KNOTS. .79... && .PREV DISCUSSION... /ISSUED 245 AM CDT WED JUL 30 2008/ SCATTERED SHOWERS AND STORMS CONTINUE ALONG A MID LEVEL SHEAR AXIS /AS REPRESENTED IN RUC 500MB AND 700MB VORTICITY ANALYSIS/ EXTENDING FROM NORTH CENTRAL OKLAHOMA TO OUR WESTERN CWA AND INTO THE BIG BEND REGION. AS THIS SHEAR ZONE TRANSLATES ACROSS NORTH TEXAS TODAY EXPECT SCATTERED STORMS TO DEVELOP. THERE WILL BE A SLIGHT CHANCE OF STORMS THIS MORNING...WITH BETTER CHANCES THIS AFTERNOON OVER OUR EASTERN AND NORTHEASTERN ZONES. HOWEVER...HIGH TEMPERATURES WILL STILL MANAGE TO BE QUITE HOT THIS AFTERNOON WITH UPPER 90S COMMON AREA WIDE. SCATTERED STORM CHANCES WILL LINGER OVER OUR EASTERN CWA THROUGH TOMORROW EVENING. WHILE SOME OF THE MODELS SUGGEST PRECIP CHANCES WILL CONTINUE THROUGH FRIDAY...WILL MAINTAIN SILENT 10 POPS AT THIS TIME DUE TO UNCERTAINTY. OTHERWISE...CENTER OF THE MID LEVEL RIDGE WILL ANCHOR ITSELF OVER THE OZARKS EARLY NEXT WEEK...ALLOWING FOR TRIPLE DIGIT HEAT TO SETTLE OVER NORTH TEXAS ONCE AGAIN. SCHULTZ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 99 79 99 80 99 / 40 20 20 10 10 WACO, TX 99 79 99 79 99 / 30 20 20 10 10 PARIS, TX 96 73 97 75 96 / 40 20 20 10 10 DENTON, TX 98 75 98 77 98 / 30 20 10 10 10 MCKINNEY, TX 98 73 98 75 98 / 40 20 20 10 10 DALLAS, TX 98 79 99 80 98 / 40 20 20 10 10 TERRELL, TX 99 77 98 77 97 / 40 20 20 10 10 CORSICANA, TX 98 76 96 76 97 / 30 20 20 10 10 TEMPLE, TX 98 76 98 76 96 / 30 20 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 600 AM CDT WED JUL 30 2008 .AVIATION... A SHEAR AXIS WILL REMAIN OVER NORTH TEXAS THROUGH THURSDAY. WEAK LARGE SCALE LIFT COUPLED WITH MID LEVEL MOISTURE WILL BRING SCATTERED SHOWERS/STORMS TO THE METROPLEX TAF SITES THIS MORNING. A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS AFTERNOON/EVENING AND SHOULD PROVIDE A FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS. THE MAIN FORECAST CHALLENGE WILL BE TIMING OF THE STORMS AT THE TAF SITES. WILL SEE A FEW STORMS AT TAF ISSUANCE NEAR FTW/DFW/AND AFW AND SHORTLY AFTER AT DAL. WILL BRING THUNDERSTORM CHANCES BACK TO ALL TAF SITES LATE THIS AFTERNOON WHEN THE COLD FRONT GETS A BIT CLOSER. OTHERWISE...EXPECT VFR CONDITIONS WITH MAINLY SCATTERED TO BROKEN MID LEVEL CLOUDS AND A SOUTH WIND BETWEEN 8 AND 14 KNOTS. .79... && .DISCUSSION... 245 AM SCATTERED SHOWERS AND STORMS CONTINUE ALONG A MID LEVEL SHEAR AXIS /AS REPRESENTED IN RUC 500MB AND 700MB VORTICITY ANALYSIS/ EXTENDING FROM NORTH CENTRAL OKLAHOMA TO OUR WESTERN CWA AND INTO THE BIG BEND REGION. AS THIS SHEAR ZONE TRANSLATES ACROSS NORTH TEXAS TODAY EXPECT SCATTERED STORMS TO DEVELOP. THERE WILL BE A SLIGHT CHANCE OF STORMS THIS MORNING...WITH BETTER CHANCES THIS AFTERNOON OVER OUR EASTERN AND NORTHEASTERN ZONES. HOWEVER...HIGH TEMPERATURES WILL STILL MANAGE TO BE QUITE HOT THIS AFTERNOON WITH UPPER 90S COMMON AREA WIDE. SCATTERED STORM CHANCES WILL LINGER OVER OUR EASTERN CWA THROUGH TOMORROW EVENING. WHILE SOME OF THE MODELS SUGGEST PRECIP CHANCES WILL CONTINUE THROUGH FRIDAY...WILL MAINTAIN SILENT 10 POPS AT THIS TIME DUE TO UNCERTAINTY. OTHERWISE...CENTER OF THE MID LEVEL RIDGE WILL ANCHOR ITSELF OVER THE OZARKS EARLY NEXT WEEK...ALLOWING FOR TRIPLE DIGIT HEAT TO SETTLE OVER NORTH TEXAS ONCE AGAIN. SCHULTZ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 99 79 99 80 99 / 30 20 20 10 10 WACO, TX 99 79 99 79 99 / 20 20 20 10 10 PARIS, TX 96 73 97 75 96 / 30 20 20 10 10 DENTON, TX 98 75 98 77 98 / 30 20 10 10 10 MCKINNEY, TX 98 73 98 75 98 / 30 20 20 10 10 DALLAS, TX 98 79 99 80 98 / 30 20 20 10 10 TERRELL, TX 99 77 98 77 97 / 30 20 20 10 10 CORSICANA, TX 98 76 96 76 97 / 30 20 20 10 10 TEMPLE, TX 98 76 98 76 96 / 20 20 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 223 PM MST WED JUL 30 2008 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA FORECAST DISCUSSION .UPDATE...UPDATED FOR AVIATION AND FIRE WX DISCUSSIONS. && .SYNOPSIS... DRY AND INCREASINGLY WARM WEATHER CAN BE EXPECTED THROUGH FRIDAY ACROSS THE REGION AS HIGH PRESSURE STRENGTHENS OVERHEAD. BY SATURDAY TEMPERATURES WILL BEGIN TO DECREASE AND MOISTURE LEVELS WILL INCREASE MEANING THE THREAT FOR PRIMARILY AFTERNOON SHOWERS AND THUNDERSTORMS WILL RETURN TO THE AREA. THE THUNDERSTORMS MAY BECOME MORE WIDESPREAD SUNDAY THROUGH TUESDAY AS THE MOISTURE DEEPENS. && .DISCUSSION... THIS EVENING...SOME CU HAS MANAGED TO DEVELOP ALONG THE RIM. HOWEVER...STRONG CONVECTIVE INHIBITION WILL LIMIT THE COVERAGE/INTENSITY OF ANY STORMS THAT DEVELOP. UNFAVORABLE STEERING FLOW WILL ALSO CONFINE MUCH OF THE ACTIVITY TO THE MOGOLLON PLATEAU AND NEAR THE WHITE MOUNTAINS. LATEST RUC PLACES THE CENTER OF THE UPPER LEVEL ANTICYCLONE ATOP THE PHOENIX AREA. THIS WILL ENSURE MAINLY CLEAR SKIES AND WARM TEMPERATURES THROUGH THE SHORT TERM. MAVS CONTINUE TO TREND WARMER FOR THU AND WILL BE ISSUING AN EXCESSIVE HEAT WARNING FOR THE GREATER PHOENIX AREA. CONFIDENCE IS INCREASING FOR THIS WEEKEND`S HEAT AND THE EXCESSIVE HEAT WATCH FOR FRI-SAT WILL ALSO BE UPGRADED TO A WARNING. WITH THE DEEPER MOISTURE IN PLACE ACROSS THE SOUTHWEST DESERTS (RELATIVE TO THE PHOENIX AREA)...HEAT INDICES WILL BE ELEVATED...THOUGH EXCESSIVE HEAT CRITERIA WILL LIKELY NOT BE REACHED IN YUMA. PREVIOUS DISCUSSION... TWO PRIMARY MODES OF WEATHER EXPECTED OVER THE NEXT WEEK...HOT AND DRY THROUGH FRIDAY THEN COOLER AND WET BEGINNING SATURDAY. 00Z NAM AND GFS MODELS APPEARED TO HAVE INITIALIZED VERY WELL AND BOTH PORTRAY SIMILAR FORECASTS THROUGH FRIDAY. AS HAS BEEN THE CASE FOR MUCH OF THE SUMMER...THE ECMWF IS THE WET-FOOT. FORECAST CONFIDENCE THROUGH FRIDAY IS HIGH. CONFIDENCE BEGINS TO DECREASE SATURDAY AND IS LOW BY TUESDAY. MODELS IN EXCELLENT AGREEMENT THAT MOISTURE WILL GENERALLY REMAIN AT BAY THROUGH FRIDAY AS TEMPERATURES QUICKLY ESCALATE. H5 PATTERN SIMILAR IN ALL MODELS WITH RIDGE INTENSIFYING AS IT DRIFTS TOWARD THE FOUR CORNERS. INHERITED FORECAST LOOKED PRETTY GOOD...BUT OPTED TO INCREASE MAXIMUM TEMPERATURES SLIGHTLY AS JUSTIFIED BY H85 TEMPS AND VERY DRY BOUNDARY LAYER. SATURDAY...MODELS INDICATING A QUICK TRANSITION FROM HOT-DRY TO /RELATIVELY/ COOL-WET. THE EXPECTED WEATHER PATTERN FRIDAY INTO SATURDAY CONCEPTUALLY POINTS TO MCS ACTIVITY OVER NORTHERN MEXICO...CONDUCIVE TO GENERATING A GULF SURGE FOR OUR LOWER DESERTS. HOWEVER...BEING MANY DAYS OUT IT IS ALMOST FOOLISH TO PEG THE FORECAST TO MESOSCALE WEATHER FEATURES. OVERALL THE SYNOPTIC PATTERN OF INCREASING S/SE FLOW WOULD CAUSE MOISTURE TO BEGIN MOVING BACK INTO OUR AREA AND THEREFORE INCREASING CHANCES FOR PRECIPITATION. PREVIOUS GRIDS ALREADY INDICATED INCREASING POPS FOR THE FORECAST AREA BEGINNING SATURDAY...AND KEPT WITH THAT THINKING. GFS/ECMWF INDICATING A TROPICAL WAVE WILL MOVE TOWARD THE AREA AROUND MONDAY. THIS IS ABOUT THE ONLY SUBSTANTIVE WEATHER FEATURE IN THE EXTENDED FORECAST PERIOD TO GRAB ON TO...THEREFORE CONTINUED UPWARD TREND IN POPS THROUGH MONDAY...WITH A SLIGHT DECREASE AFTERWARD. AS SAID...OVERALL CONFIDENCE IN THE EXTENDED FORECAST IS LOW. THE PROBABILITY THAT DEEP /MONSOON/ MOISTURE WILL MOVE BACK INTO OUR FORECAST AREA THIS WEEKEND LOOKS FAIRLY HIGH. BUT AS IS OFTEN THE CASE...OUR WEATHER TENDS TO BE DOMINATED BY MESOSCALE FEATURES THAT ARE BEYOND FORECASTING CAPABILITIES THIS FAR IN ADVANCE. && .AVIATION... NO AVIATION CONCERNS EXPECTED THROUGH AT LEAST 00 UTC FRIDAY. MOSTLY CLEAR SKIES WITH LIGHT WINDS CAN BE EXPECTED ACROSS SOUTHEAST CALIFORNIA...SOUTHWEST AND SOUTH-CENTRAL ARIZONA THROUGH AT LEAST 00 UTC FRIDAY. THE ATMOSPHERE WILL REMAIN QUITE DRY FOR THIS TIME OF YEAR...WITH ONLY A VERY SLIGHT (LESS THAN 10%) CHANCE OF THUNDERSTORMS OVER THE WHITE MTS...WELL TO THE EAST OF THE VALLEY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... AN INCREASE IN MOISTURE IS EXPECTED OVER THE WEEKEND...FOR AN INCREASING THREAT OF MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. THE MAIN THREATS WITH ANY STORMS THAT DEVELOP WILL BE FREQUENT LIGHTNING WITH LITTLE RAINFALL...AS WELL AS STRONG GUSTY ERRATIC WINDS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...EXCESSIVE HEAT WARNING FROM 10 AM THURSDAY TO 8 PM MST SATURDAY FOR AZZ022-023-027-028. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH/INIGUEZ AVIATION...WANEK FIRE WEATHER...WANEK az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 325 PM CDT WED JUL 30 2008 .DISCUSSION... 324 PM CDT MAIN FORECAST TRENDS ARE WARM AND UNSETTLED WEATHER FOR THE REMAINDER OF THE WEEK FOLLOWED BY A DRY AND MILDER SATURDAY THAN ORIGINALLY THOUGHT. HEAT AND HUMIDITY BUILD INTO THE AREA AGAIN SUNDAY AND MONDAY. THE FIRST ISSUE IS CONTINUED DEVELOPMENT OF ISOLATED TSRA THIS EVENING ALONG THE STALLED SURFACE BOUNDARY ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. LOCALIZED VERY HEAVY RAIN HAS BEEN REPORTED WITH THESE STORMS. WILL PLAN TO CONTINUE MENTION OF ISOLATED ACTIVITY THROUGH THE EVENING...MAINLY ALONG THE SURFACE BOUNDARY. GFS AND NAM BOTH SHOW A SURFACE TROUGH STATIONED OVER THE AREA TOMORROW BETWEEN HIGH PRESSURE CENTERS TO OUR NORTH AND SOUTH. BOTH MODELS SHOW LIGHT PRECIP DEVELOPING ALONG THIS BOUNDARY DURING THE AFTERNOON. COULD BE MUCH LIKE TODAY WITH VERY ISOLATED SHOWERS. ANOTHER SURFACE TROUGH APPROACHES THE AREA ON FRIDAY. NAM AND GFS DISAGREE ON POSITION OF SURFACE WAVE FRIDAY AFTERNOON...WITH GFS PUTTING IT OVER THE AREA AND NAM KEEPING IT FARTHER WEST OVER IOWA. SPC ALSO DISCUSSES FORECAST UNCERTAINTY BUT HAS THE NORTHERN HALF OF ILLINOIS AND PART OF NORTHWEST INDIANA IN THE DAY 3 SLIGHT RISK. WILL FOLLOW THIS THINKING AND EXPAND SLIGHT CHANCE TSRA AND MENTION CHANCE OF HEAVY THUNDERSTORMS FOR PART OF THE PERIOD. HEAT BUILDS INTO THE REGION BY THE WEEKEND AND EARLY NEXT WEEK. ORIGINAL THOUGHT WAS FOR POSSIBLE HEAT HEADLINES SATURDAY AND SUNDAY. LATEST MODELS NOW SUGGEST MAX TEMPERATURE AND DEWPOINT COMBINATIONS WILL ARRIVE A LITTLE LATER...LIKE SUNDAY AND MONDAY. ON SATURDAY THE GFS ENSEMBLES SHOW THE SURFACE RIDGE MOVING OVERHEAD...PUTTING US IN NORTHERLY FLOW AND DRIER AIR FOR AT LEAST PART OF THE DAY. BY SUNDAY AND MONDAY THE UPPER RIDGE INTENSIFIES OVER THE AREA AND THE SURFACE RIDGE AXIS HAS MOVED JUST TO OUR EAST. THIS PUTS US IN SOUTH TO SOUTHWEST FLOW WITH WARM ADVECTION AND HIGHER DEWPOINTS. WILL NEED TO CONTINUE MONITORING THIS SITUATION FOR POSSIBLE DANGEROUS HEAT INDICIES. EXTENDED GUIDANCE HAS HEAT PERSISTING INTO TUESDAY WITH POSSIBLE MODERATION NEXT WEDNESDAY. GFS ENSEMBLE MEAN ALSO INDICATES INCREASINGLY UNSETTLED WEATHER FOR THE FIRST PART OF NEXT WEEK...BUT WILL NOT MAKE MAJOR CHANGES TO THIS PERIOD AT THIS TIME. LENNING && .AVIATION... 120 PM CDT FOR 18Z TAFS...WINDS MAIN FOCUS THROUGH NEXT 24 HOURS...THOUGH SMALL BUT NON ZERO PROBABILITY FOR CONVECTION EXISTS IN VICINITY OF STALLED FRONTAL BOUNDARY. WEAK COLD FRONT HAS SETTLED ACROSS FORECAST AREA THIS MORNING...AND HAS BECOME NEARLY STATIONARY ROUGHLY ALONG KCWI...KSQI...KGYY LINE AT 17Z. GENERALY WESTERLY LOW LEVEL FLOW ACROSS AREA WITH SPEEDS GENERALY BELOW 10 KNOTS...THOUGH DIRECTION HAS BEEN SOMEWHAT VARIABLE FROM SOUTHWEST TO NORTHWEST AT TIMES. KORD/KMDW TDWR REFLECTIVITY DEPICT WEAK LAKE BREEZE HAS DEVELOPED...PUSHING INLAND TO A FEW MILES EAST OF KMDW AT THIS TIME. SHORT TERM MODEL GUIDANCE INDICATES THERE SHOULD BE ENOUGH WESTERLY BOUNDARY LAYER FLOW TO PREVENT LAKE BOUNDARY FROM MOVING INTO KORD/KMDW...THOUGH THIS WILL HAVE TO BE WATCHED NEXT FEW HOURS ESPECIALLY FOR KMDW BASED ON CURRENT TRENDS. OTHERWISE...LIGHT SYNOPTIC WESTERLY FLOW EXPECTED UNTIL THURSDAY MORNING...WHEN SECONDARY SURFACE TROUGH SAGS THROUGH FORECAST AREA. SURFACE HIGH PRESSURE BUILDING SOUTHEAST ACROSS WI/LAKE MICHIGAN SHOULD HELP TO VEER WINDS NORTHERLY DURING THE MORNING AND THEN EAST/NORTHEAST JUST BEYOND 18Z END OF TAF PERIOD. WITH RESPECT TO CONVECTION POTENTIAL...LOWER 70S SURFACE DEW POINTS POOLING ALONG/AND ON WARM SIDE OF STALLED FRONT PER SURFACE OBS EARLY THIS AFTERNOON. RUC/NAM FORECAST SOUNDINGS FROM FRONTAL ZONE THIS AFTERNOON DEVELOP SBCAPES OF 2500-3500 J/KG...WITH LITTLE/NO CIN. LOW LEVEL FORCING IS QUITE WEAK...GIVEN LIGHT FLOW AND LITTLE DIRECTIONAL CONVERGENCE ACROSS FRONT. HOWEVER...RELATIVELY POTENT MID LEVEL SHORT WAVE NOTED IN VAPOR IMAGERY THIS MORNING TRANSLATING SOUTHEAST FROM THE DAKOTAS...AND EXTRAPOLATION FROM GOES VAPOR LOOP SUGGESTS THIS WAVE WILL MOVE INTO NORTHEAST IA BY LATE THIS AFTERNOON. ALONG WITH POTENTIAL ENHANCEMENT THROUGH WEAK SYNOPTIC SCALE LIFT/MID LEVEL COOLING...RUC FORECASTS INDICATE REGION WILL COME BENEATH DIVERGENT RIGHT ENTRANCE REGION OF 70 KNOT UPPER JET STREAK OVER NORTHERN LAKES. THUS WHILE POTENTIAL COVERAGE APPEARS TO BE MINIMAL...ISOLATED THUNDERSTORMS CANT BE RULED OUT NEAR TERMINALS LATE THIS AFTERNOON/EARLY THIS EVENING...WITH KMDW/KGYY LIKELY HAVING THE GREATER THREAT THOUGH STILL SMALL PROBABILITY. AT THIS TIME WILL REMAIN DRY IN TERMINALS AS CAN/T USE A LOW CHANCE PROB GROUP IN FIRST 9 HOURS...THOUGH WILL MONITOR RADAR TRENDS CLOSELY FOR THE NEED TO AMEND. RATZER && .MARINE... 303 PM CDT LOW PRESSURE OF OVER EASTERN ONTARIO WILL CONTINUE TO TRACK OFF TO THE EAST TONIGHT...MOVING ACROSS SOUTHERN QUEBEC ON THURSDAY. WEAK HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES BY THURSDAY AFTERNOON...BEFORE A WEAK AREA OF LOW PRESSURE DEVELOPS ACROSS THE CENTRAL PLAINS AND MOVES ACROSS LAKE MICHIGAN ON FRIDAY. ANOTHER WEAK AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES LATE SATURDAY AND SATURDAY NIGHT...AS LOW PRESSURE DEVELOPS OVER THE PLAINS. A WEAKER AREA OF LOW PRESSURE WILL MOVE INTO THE WESTERN LAKES MONDAY. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 304 PM CDT WED JUL 30 2008 .DISCUSSION... 1154 AM CDT HAVE BEEN LOOKING INTO ADDING A SLIGHT CHANCE OF TSRA IN THE WESTERN PART OF THE I-80 TO I-88 CORRIDOR FOR LATE THIS AFTERNOON AND EVENING. WIDESPREAD SUPPORT APPEARS TO BE LIMITED BUT SEVERAL FACTORS SUGGEST THE POSSIBILITY FOR ISOLATED CONVECTION. A WEAK COLD FRONT STALLED ACROSS NORTHERN ILLINOIS THIS MORNING IS INDICATED BY A LINE OF DEVELOPING CUMULUS IN THE VISIBLE SATELLITE IMAGERY. NORTH OF THIS BOUNDARY DEWPOINTS APPEAR TO BE DROPPING BUT THE 14Z-15Z SURFACE ANALYSIS INDICATES POOLING NEAR THE BOUNDARY ITSELF. MODEL SOUNDINGS NORTH OF THE BOUNDARY INDICATE SOME MID- LEVEL WARMING AND DRYING DUE TO SUBSIDENCE WHICH ALSO WOULD TEND TO INHIBIT CONVECTION...BUT THESE EFFECTS ARE LESS PRONOUNCED FARTHER SOUTH. THE ADDITION OF ANOTHER SURFACE TROUGH MOVING SOUTH THROUGH WISCONSIN...PLUS INDICATIONS OF SHORTWAVE ENERGY IN THE UPPER- LEVEL FLOW...ALSO WOULD PROVIDE SUPPORT FOR SURFACE CONVERGENCE AND UPPER-LEVEL DIVERGENCE. SEVERAL FACTORS WOULD HAVE TO COME TOGETHER FOR CONVECTION TO FORM...BUT THINK THIS POSSIBILITY IS AT LEAST WORTH MENTIONING. UPDATED FORECAST PACKAGE WILL BE COMING IN A FEW MINUTES. LENNING && .AVIATION... 120 PM CDT FOR 18Z TAFS...WINDS MAIN FOCUS THROUGH NEXT 24 HOURS...THOUGH SMALL BUT NON ZERO PROBABILITY FOR CONVECTION EXISTS IN VICINITY OF STALLED FRONTAL BOUNDARY. WEAK COLD FRONT HAS SETTLED ACROSS FORECAST AREA THIS MORNING...AND HAS BECOME NEARLY STATIONARY ROUGHLY ALONG KCWI...KSQI...KGYY LINE AT 17Z. GENERALY WESTERLY LOW LEVEL FLOW ACROSS AREA WITH SPEEDS GENERALY BELOW 10 KNOTS...THOUGH DIRECTION HAS BEEN SOMEWHAT VARIABLE FROM SOUTHWEST TO NORTHWEST AT TIMES. KORD/KMDW TDWR REFLECTIVITY DEPICT WEAK LAKE BREEZE HAS DEVELOPED...PUSHING INLAND TO A FEW MILES EAST OF KMDW AT THIS TIME. SHORT TERM MODEL GUIDANCE INDICATES THERE SHOULD BE ENOUGH WESTERLY BOUNDARY LAYER FLOW TO PREVENT LAKE BOUNDARY FROM MOVING INTO KORD/KMDW...THOUGH THIS WILL HAVE TO BE WATCHED NEXT FEW HOURS ESPECIALLY FOR KMDW BASED ON CURRENT TRENDS. OTHERWISE...LIGHT SYNOPTIC WESTERLY FLOW EXPECTED UNTIL THURSDAY MORNING...WHEN SECONDARY SURFACE TROUGH SAGS THROUGH FORECAST AREA. SURFACE HIGH PRESSURE BUILDING SOUTHEAST ACROSS WI/LAKE MICHIGAN SHOULD HELP TO VEER WINDS NORTHERLY DURING THE MORNING AND THEN EAST/NORTHEAST JUST BEYOND 18Z END OF TAF PERIOD. WITH RESPECT TO CONVECTION POTENTIAL...LOWER 70S SURFACE DEW POINTS POOLING ALONG/AND ON WARM SIDE OF STALLED FRONT PER SURFACE OBS EARLY THIS AFTERNOON. RUC/NAM FORECAST SOUNDINGS FROM FRONTAL ZONE THIS AFTERNOON DEVELOP SBCAPES OF 2500-3500 J/KG...WITH LITTLE/NO CIN. LOW LEVEL FORCING IS QUITE WEAK...GIVEN LIGHT FLOW AND LITTLE DIRECTIONAL CONVERGENCE ACROSS FRONT. HOWEVER...RELATIVELY POTENT MID LEVEL SHORT WAVE NOTED IN VAPOR IMAGERY THIS MORNING TRANSLATING SOUTHEAST FROM THE DAKOTAS...AND EXTRAPOLATION FROM GOES VAPOR LOOP SUGGESTS THIS WAVE WILL MOVE INTO NORTHEAST IA BY LATE THIS AFTERNOON. ALONG WITH POTENTIAL ENHANCEMENT THROUGH WEAK SYNOPTIC SCALE LIFT/MID LEVEL COOLING...RUC FORECASTS INDICATE REGION WILL COME BENEATH DIVERGENT RIGHT ENTRANCE REGION OF 70 KNOT UPPER JET STREAK OVER NORTHERN LAKES. THUS WHILE POTENTIAL COVERAGE APPEARS TO BE MINIMAL...ISOLATED THUNDERSTORMS CANT BE RULED OUT NEAR TERMINALS LATE THIS AFTERNOON/EARLY THIS EVENING...WITH KMDW/KGYY LIKELY HAVING THE GREATER THREAT THOUGH STILL SMALL PROBABILITY. AT THIS TIME WILL REMAIN DRY IN TERMINALS AS CAN/T USE A LOW CHANCE PROB GROUP IN FIRST 9 HOURS...THOUGH WILL MONITOR RADAR TRENDS CLOSELY FOR THE NEED TO AMEND. RATZER && .MARINE... 303 PM CDT LOW PRESSURE OF OVER EASTERN ONTARIO WILL CONTINUE TO TRACK OFF TO THE EAST TONIGHT...MOVING ACROSS SOUTHERN QUEBEC ON THURSDAY. WEAK HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES BY THURSDAY AFTERNOON...BEFORE A WEAK AREA OF LOW PRESSURE DEVELOPS ACROSS THE CENTRAL PLAINS AND MOVES ACROSS LAKE MICHIGAN ON FRIDAY. ANOTHER WEAK AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES LATE SATURDAY AND SATURDAY NIGHT...AS LOW PRESSURE DEVELOPS OVER THE PLAINS. A WEAKER AREA OF LOW PRESSURE WILL MOVE INTO THE WESTERN LAKES MONDAY. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 332 PM EDT WED JUL 30 2008 .SHORT TERM... TONIGHT THROUGH THURSDAY NIGHT WEAK SFC BOUNDARY IS LAID OUT ACROSS THE REGION AS OF 1830Z...EXTENDING FROM MCI TO SOUTH OF SBN TO OEB. NORTHERN PORTION THIS BOUNDARY HAS CONTINUED TO MARCH THROUGH MI WHILE THE SOUTHERN END HAS PRETTY MUCH STALLED OUT OVER IN. ADDED CONVERGENCE ALONG THE LK MI LAKE BREEZE COUPLED WITH SFC CONVERGENCE AND DAYTIME HEATING HAS ALLOWED A SCT SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE REGION. SB CAPES OF NEARLY 2000 J/KG PER RUC13 PROGS INDICATED THAT THIS ACTIVITY WILL LIKELY CONTINUE ALONG AND SOUTH OF THE AFOREMENTIONED BOUNDARY GIVEN ADDED LARGE SCALE ASCENT PRESENT PER THE REMNANTS OF DOLLY. HAVE ALLOWED SCT TS/SH MENTION TO CONTINUE THROUGH THE AFTERNOON/EVENING WITH ACTIVITY LIKELY DIMINISHING AFTER SUNSET...ONLY BEING SUPPORTED BY OUTFLOW BOUNDARIES. THIS IS IN LINE WITH NAM12/RUC13/AND GFS PROGS. GIVEN AMPLE DRY AIR IN PLACE PER GRB/DVN 12Z RAOB AND PROGGED RUC SOUNDINGS...THE POTENTIAL WILL EXIST FOR STRONG DOWNBURST WINDS WITH THE MORE INTENSE CORES...ESPECIALLY GIVEN HIGH PW. WINDEX VALUES OF 58 KNOTS CONFIRM THIS. HAVE ADDED GUSTY WINDS IN WX MENTION. EVERYTHING SHOULD SHIFT SOUTH THROUGH THE EVENING. FARTHER UPSTREAM...A WEAKENING SW TROUGH IS ENTERING NW IA AND COULD SUPPORT ANOTHER ROUND OF CONVECTION ALONG THE OLD SFC BOUNDARY. THERE IS AN OUTSIDE CHANCE THAT THIS WAVE COULD HOLD TOGETHER AS IT APPROACHES THE REGION LATE TONIGHT AS INDICATED BY NAM12 SI AND H85 THETA-E PROGS. HOWEVER...ALL OTHER GUIDANCE SUGGEST OTHERWISE. FORECAST RAOBS INDICATE THAT MID LEVEL WARMING WOULD PRECLUDE ANY ELEVATED CONVECTION. HAVE OPTED FOR DRY FORECAST UNTIL BETTER CONFIDENCE IS REACHED. EXPECTING DRY CONDITIONS TOMORROW AT THIS TIME. THERE IS AN OUTSIDE CHANCE FOR AN ISOLATED SH/TS IN THE FAR SOUTH ALONG THIS RESIDUAL BOUNDARY...BUT GIVEN LACK OF STRONG FORCING AND UPPER LEVEL SUPPORT...DRY OPTION IS BEST FOR NOW. ANOTHER MCS IS EXPECTED TO DEVELOP IN THE NORTHERN PLAINS AND TRACK SE DOWN TOWARD THE UPPER MIDWEST. THERE IS AN OUTSIDE CHANCE THAT THIS SYSTEM MAY MAKE IT INTO THE CWA LATE OVERNIGHT THUR. BUT...WILL LEAVE FORECAST DRY AT THIS TIME DUE TO QUESTIONS ON INSTABILITY AND TRACK. OTHERWISE...THE REMAINDER OF THE FORECAST IS IN GOOD SHAPE. && .LONG TERM... FOCUS OF THE LONG TERM CONTINUES TO BE DEVELOPING RIDGE AND QUESTIONS PERTAINING TO ITS POSITION AND INFLUENCE OVER THE FORECAST AREA. AFTER A DRASTIC FLOP IN THE GFS LAST NIGHT THE 12Z RUN IS FAIRLY CONSISTENT WITH ITS 00Z/06Z PREDECESSORS DIGGING A TROF OVER THE EASTERN US AND HOLDING THE RIDGE FURTHER WEST. THIS KEEPS CWA ON PERIPHERY OF RIDGE UNDER NW FLOW ALOFT THROUGH THE WEEKEND BEFORE FINALLY BUILDING INTO THE OHIO VALLEY EARLY IN THE WEEK. THE 00Z EC HAS SHOWN BETTER RUN TO RUN CONSISTENCY AND EVOLVES SIMILARLY BUT BUILDS THE RIDGE SOMEWHAT FASTER TO THE EAST WITH A WARMER WEEKEND. GIVEN THE RECENT GFS CONCERNS HAVE SIDED MORE WITH THE EC SOLUTION FOR THIS PACKAGE WHILE NOTING BOTH MODELS CONTINUE THE TREND OF DELAYING THE EASTWARD PROGRESSION OF THE RIDGE IN FAVOR OF EASTERN TROF WHICH WE HAVE SEEN SO OFTEN THIS SEASON. WOULD NOT BE SURPRISED TO SEE THIS TREND CONTINUE IN SUBSEQUENT RUNS. MODEL CONSENSUS DEVELOPS CONVECTION ALONG BNDRY THAT PUSHES THROUGH FRI NITE/SAT BEFORE THE RIDGE BUILDS IN EARNEST OVER THE AREA INTO THE NEW WEEK. DESPITE PERSISTENT DRY PATTERN ITS DIFFICULT TO COMPLETELY IGNORE THIS FEATURE WITH IT SHOWING UP ACROSS VARIOUS MODEL SOLNS SO HAVE ADDED CHC POPS FRI AFTERNOON AREA WIDE CARRYING OVER IN EASTERN PORTIONS FRI NITE. SIDE EFFECT OF SLOWER TIMING WITH RIDGE IS PERSISTENCE OF HEAT LONGER INTO THE WEEK...WITH TEMPS NOW PROGGED NEAR 90 THROUGH THE END OF THE EXTENDED AND THE INFLUENCE OF BNDRY POISED JUST TO THE N OF CWA PUSHED BACK TO WEDNESDAY. TEMPS ALREADY IN THIS RANGE FOR THE FCST WITH ONLY MINOR TWEAKS. WILL ALSO LEAVE TAIL END OF EXTENDED DRY FOR NOW AS CONFIDENCE IN THE EVOLUTION OF RIDING AND THE ASSOC BNDRY TO THE NORTH IS LOW. && .AVIATION.../18Z TAFS/ WEAK FRONTAL BOUNDARY CONTINUES TO DRIFT SOUTH ACROSS THE FA. THIS BOUNDARY CAN BE SEEN ON VIS SAT AND SFC OBS...EXTENDING SE FROM GYY TO NEAR GSH AND EAST. ADDED CONVERGENCE ON THE SOUTH END OF LK MI FROM THE LK BREEZE IS ALLOWING SOME ENHANCED CU TO DEVELOP. GIVEN SB CAPES OF AROUND 1500 J/KG...AND CONTINUED HEATING EXPECTING A FEW TS TO DEVELOP BY MID/LATE AFTERNOON WHICH WILL PROPAGATE SE. HAVE ADDED VCTS AND CB MENTION AT SBN...BUT NOT EXPECTING ANY RESTRICTIONS AT THE TERMINAL. HAVE DONE THE SAME FOR FWA...WHERE RESTRICTIONS ARE POSSIBLE. BUT GIVEN LOW CONFIDENCE IN DEVELOPMENT...HAVE OPTED OUT OF A TEMPO FOR NOW. THIS BOUNDARY WILL CONTINUE TO SAG SOUTH THROUGH THE NIGHT WITH CONVECTION CHANCES DIMINISHING AFTER SUNSET. HAVE ADDED BR MENTION AT FWA WHERE BETTER MOISTURE WILL BE IN PLACE...LEAVING SBN VFR UNTIL BETTER INDICATIONS ARE PRESENT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LUDINGTON AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 353 PM EDT WED JUL 30 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW SPINNING JUST NORTHEAST OF LAKE SUPERIOR OVER NORTHEAST ONTARIO. A WEAK SHORTWAVE IS SWEEPING ACROSS EASTERN LAKE SUPERIOR WHILE ROTATING THROUGH THE BASE OF THE LOW. A RIDGE IS BUILDING OVER MANITOBA AS A SURFACE LOW IS OVER EAST CENTRAL ONTARIO WITH A FRONTAL BOUNDARY EXTENDING SOUTH INTO SOUTHERN LOWER MICHIGAN THEN WEST INTO THE DAKOTAS. A SURFACE RIDGE IS ALSO BUILDING OVER MANITOBA STRETCHING INTO THE FORECAST AREA PROVIDING SOME SUN ACROSS THE AREA. && .SHORT TERM... (TONIGHT AND THU) THE VERTICALLY STACKED LOW WILL SHIFT INTO SOUTHWEST QUEBEC BY THURSDAY MORNING WHILE THE RIDGE SHIFTS INTO WESTERN ONTARIO. DRIER AIR WILL CONTINUE TO FEED INTO THE AREA. THE LOW CLOUDS SHOULD BURN OFF AS THE SUN GOES DOWN. SWILL BE LIGHT UNDER THE INFLUENCE OF THE RIDGE. SOME LOW LEVEL MOISTURE WILL BE TRAPPED UNDER RADIATIONAL COOLING INDUCED WEAK INVERSION WHICH SHOULD LEAD TO SOME FOG REDUCING VISIBILITY ONLY TO 2 MILES IN PLACES. DENSE FOG IS NOT ANTICIPATED AT THIS TIME SO WILL NOT INCLUDE IN THE GRIDS. THE QUEBEC LOW WILL EDGE EASTWARD A LITTLE...DRAWING THE SHORTWAVE EAST INTO EASTERN ONTARIO. THE RIDGE WILL SETTLE OVER THE FORECAST AREA. DRY AIR IN PLACE WILL KEEP CONDITIONS DRY THROUGH THURSDAY. WINDS WILL BE LIGHT IN THE MORNING AND WILL INCREASE TO 5 TO 10 MPH IN THE AFTERNOON. FORECAST SOUNDINGS STILL SUGGESTING THAT THERE WILL BE SOME CONVECTION AROUND 850MB...HOWEVER...A SIGNIFICANT CAP WILL PREVENT ANY SHOWERS OR THUNDERSTORMS. .LONG TERM... (THU NIGHT THRU WED) THU NIGHT/FRI...ATTENTION TURNS TO SEVERAL SHORTWAVES DROPPING ESE INTO THE MIDWEST/GREAT LAKES REGION. SUBTLE SHORTWAVE TRACKING ACROSS MN/IA SHOULD BE THE FOCUS OF THE MORE SIGNIFICANT CONVECTION. WITH THIS SHORTWAVE...THE LOCATION OF THE NOSE OF LOW-LEVEL JET/STRONGEST THETA-E ADVECTION/GREATEST INSTABILITY SUPPORTS A SE MOVING CLUSTER OF SHRA/TSRA THAT SHOULD PASS TO S OF THE FCST AREA THU NIGHT/FRI MORNING. FARTHER N...POTENTIAL EXISTS FOR ADDITIONAL ISOLD/SCT CONVECTION ALONG APPROACHING COLD FRONT/850MB TROF ASSOCIATED WITH STRONGER SHORTWAVES HEADING FOR THE UPPER LAKES. WITH MODEST 12HR 500MB HEIGHT FALLS OF 40-60M AND ELEVATED INSTABILITY (ABOVE SFC BASED INVERSION...GFS INDICATES MUCAPE VALUES OF 200-600J/KG WHILE THE NAM IS AS HIGH AS AROUND 1000J/KG)... PROBABLY CAN`T RULE OUT A FEW SHRA/TSRA. WILL ONLY INCLUDE SLIGHT CHC POPS OVER THE W HALF LATE THU NIGHT/FRI MORNING...AND INCREASE POPS TO CHC CATEGORY OVER THE E FRI AFTN AS MLCAPE BUILDS TO AROUND 1000J/KG PRIOR TO FROPA. SAT THRU WED...OVERALL PATTERN EVOLUTION DURING THIS TIME FRAME IS SIMILAR TO WHAT WAS INDICATED YESTERDAY...AND THAT IS FOR THE RIDGE OVER THE SW STATES TO EXPAND EWD OVER THE WEEKEND SO THAT FOR THE FIRST HALF OF NEXT WEEK THE RIDGE DOMINATES THE SRN HALF OF THE CONUS. END RESULT WILL BE AN EWD EXPANSION OF HEAT ACROSS MUCH OF THE CONUS WITH THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION BECOMING FAVORED FOR POTENTIAL PERIODIC CONVECTION UNDER THE UPPER JET ON THE NRN EDGE OF THE HEAT TO THE S. ALTHOUGH THE OVERALL PATTERN IS FAIRLY SIMILAR...TODAYS MEDIUM RANGE MODEL RUNS HAVE ADDED A BIT MORE UNCERTAINTY DURING THIS PERIOD FOR THE UPPER GREAT LAKES REGION. FIRST UP...SHORTWAVE THAT WILL BE HEADING THRU THE UPPER GREAT LAKES FRI WILL NOW SET UP A MORE AMPLIFIED NE CONUS TROF THIS WEEKEND. GFS IS STRONGER AND MORE WRLY INITIALLY WITH THIS TROF THAN THE ECWMF. FOR SENSIBLE WEATHER...END RESULT IS THE SAME FOR UPPER MI AS SFC HIGH PRES WILL BE SETTLING OVER THE UPPER LAKES IN THE WAKE OF THE TROF. SO...SAT WILL NOT BE NEARLY AS WARM/HUMID AS PREVIOUSLY EXPECTED. IN ADDITION...WILL REMOVE MENTION OF PCPN. PER HPC PREFERENCE...FROM SUN ONWARD...WILL LEAN FCST TOWARD THE ECMWF WHICH HAS SHOWN BETTER RUN TO RUN CONSISTENCY THAN THE GFS. THAT SAID...THERE IS STILL LITTLE OR NO CONFIDENCE IN TIMING SHORTWAVES AND ASSOCIATED CONVECTIVE COMPLEXES THAT WILL BE TRACKING ACROSS THE NRN STATES ON THE EDGE OF THE HOT DOME TO THE S. SINCE INHERITED FCST HAD POPS MENTIONED FOR SUN AND DRY WEATHER MON...WILL MAINTAIN CONTINUITY AS THERE IS STILL SOME SUPPORT FOR THAT SCENARIO. WITH VERY LOW CONFIDENCE...WILL ADD POPS TUE AND GO WITH A DRY DAY FOR THE NEW DAY 7 (WED). AS FOR TEMPS...DURING THE EARLY PART OF NEXT WEEK...THERE IS THE POTENTIAL FOR ONE OR MORE HOT/HUMID DAYS DEPENDING ON SHORTWAVE TIMING AND HOW FAR N THE RIDGE OVER THE SRN CONUS EXTENDS. ALTHOUGH TEMPS WILL BE ABOVE NORMAL...FOR NOW...WILL TAKE A CONSERVATIVE APPROACH TO TEMPS UNTIL RIDGE STRENGTH/SHORTWAVE TIMING BECOME MORE CERTAIN. TEMPS SHOULD BE CLOSER TO NORMAL WED AS RIDGE IS SUPPRESSED SOUTHWARD. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SOME DAYTIME CUMULUS CLOUDS HAVE DEVELOPED AT BOTH TAF SITES THIS MORNING. CMX ALSO WILL CONTINUE TO HAVE SOME MVFR CIG CLOUDS ROTATING AROUND LOW PRESSURE OVER NORTHERN ONTARIO...BUT OTHERWISE VFR CONDITIONS SHOULD PERSIST INTO THIS EVENING. GUSTY WINDS WILL CONTINUE THROUGH EARLY AFTERNOON AT BOTH SITES...AND ESPECIALLY AT CMX WHERE LAKE BREEZE ENHANCEMENT OCCURS. AFTER MIDNIGHT...AS ANOTHER COLD FRONT OVER NORTHERN ONTARIO DROP SOUTH THROUGH THE AREA...SOME OF LOW CLOUDS WITH THE FRONT WILL REFORM WITH THE COOLING. HAVE INCLUDED MVFR CIGS AT BOTH TAF SITES UNDER THE EXPECTATION OF REFORMING...BUT LOWER CIGS MAY OCCUR. RADIATIONAL COOLING OVERNIGHT WILL CONTRIBUTE TO MVFR VISIBILITIES AROUND SUNRISE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS WILL DIMINISH ACROSS LAKE SUPERIOR TONIGHT AS HIGH PRESSURE BUILDS IN...WITH SPEEDS LIKELY BELOW 15 KT THROUGH THURSDAY NIGHT. WINDS ARE FORECAST A LITTLE MORE COMPLICATED BEYOND THURSDAY NIGHT WITH MANY MODEL DIFFERENCES. GENERAL CONSENSUS SUGGESTS A ECMWF/GEM/NAM BLEND. THIS GIVES US A COLD FRONT DROPPING SOUTH ACROSS LAKE SUPERIOR LATE FRIDAY...WITH HIGH PRESSURE BUILDING OVER LAKE SUPERIOR BY SATURDAY MORNING. THIS HIGH THEN SLOWLY HEADS EAST SATURDAY NIGHT INTO SUNDAY AS A COLD FRONT APPROACHES FROM THE NORTHERN PLAINS. WIND SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...ROLFSON AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1215 PM CDT WED JUL 30 2008 .UPDATE... AXIS OF HEAVIER PRECIPITATION HAS MOVED INTO CENTRAL PART OF FORECAST AREA...THUS ADJUSTED AFTERNOON POPS AND WEATHER TO ACCOUNT FOR TREND. EXTENSIVE AREA OF STRATUS AND SCATTERED SHOWERS LINGER ACROSS EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI...THUS EXPECT ONLY LIMITED WARMING THROUGH THE REST OF THE AFTERNOON AND ADJUSTED MAXIMUM TEMPERATURES DOWNWARD. BREAKS IN STRATUS EVIDENT ACROSS NORTHWEST MISSOURI AND NORTHEAST KANSAS...SO EXPECT TEMPERATURES TO REBOUND A LITTLE IN THESE AREAS...THOUGH DECIDED TO LOWER MAXIMUM TEMPERATURES A FEW DEGREES LOWER THAN EARLY FORECAST. SF && .DISCUSSION... WILL ALLOW THE FLASH FLOOD WATCH TO EXPIRE AT 18Z. ADDITIONAL RAIN FALLING IN CENTRAL MISSOURI WILL NOT BE ENOUGH TO CAUSE FLASH FLOODING THIS AFTERNOON. PC && .PREV DISCUSSION... /547 AM CDT WED JUL 30 2008/ CIRCULATION CENTER ASSCD WITH THE REMNANTS OF DOLLY HAS SHIFTED INTO SERN KS WITH AN ELONGATED SHEAR AXIS EXTENDING NE INTO CENTRAL/NORTH CENTRAL MISSOURI. LATEST GFS/RUC APPEAR TO HAVE A MUCH BETTER HANDLE ON THE SITUATION AS THE NAM QPF HAS BEEN MUCH TOO FAR NORTH OVERNIGHT. A RATHER SHARP H7/H5 DEFORMATION ZONE HAS LIMITED THE NWD EXTENT OF THE HEAVY PRECIP SHIELD...FM KC AREA ENE TO NR MACON. THIS IS WELL HANDLE BY THE GFS WITH THE GFS TO SHIFT THIS AXIS SLOWLY SE THROUGH THE DAY. A VERY IMPRESSIVE H8/H7 THETAE RIDGE WAS POSITION NR THE DEFORMATION ZONE WITH COPIOUS AMOUNT OF TROPICAL MOISTURE...2-2.5 PRECIPITABLE WATER...RESULTING IN VERY HEAVY RAINFALL AMOUNTS. CLOUD TOPS HAVE WARMED THE LAST FEW HOURS AS THE LLJ HAS VEERED. HOWEVER...EXCESSIVE RAINFALL AMOUNTS ARE STILL LIKELY THIS MORNING BEFORE SYSTEM BEGINS TO WEAKEN AND BEGIN ITS DIURNAL DECREASE IN THE AFTN. SINCE RADAR TRENDS VERIFY THE LATEST GFS...HAVE REMOVED THE XTRM NRN EXTENT OF THE FFA. OTHERWISE...HAVE CONCERN ABOUT LOW CLOUDS AND FOG TNGT. MORE CONFIDENT IN AREAS OF FOG AFTER MIDNIGHT IN AREAS WHICH HAVE RECEIVED THE HEAVY RAIN TODAY. UPPER RIDGE OF HIGH PRESSURE TO BUILD INTO THE REGION THURSDAY AND FRIDAY WITH VERY WARM TEMPERATURES RETURNING. DB && .AVIATION... THREAT OF PERSISTENT PRECIPITATION HAS ENDED AT ALL THREE TERMINAL SITES...THUS THE MAIN FORECAST CONCERN THROUGH 00Z WILL BE CEILING AND VISIBILITY TRENDS. EXPECT MVFR CIGS TO CONTINUE THROUGH MID-AFTERNOON AT KSTJ...WITH BRIEF PERIOD OF LOW VFR CEILING BECOMING SCATTERED BEFORE 00Z. IFR CONDITIONS AT KMCI AND KMKC EXPECTED TO IMPROVE TO MVFR CATEGORY BY MID-AFTERNOON...WITH LOW VFR CEILING PERSISTING UNTIL 00-01Z BEFORE BECOMING SCATTERED. SKIES WILL CLEAR TONIGHT...AND WITH LIGHT WINDS...A MOIST AIR MASS AND WET GROUND...MVFR AND IFR FOG IS EXPECTED TO DEVELOP AT ALL THREE TERMINAL SITES BETWEEN 08Z AND 10Z. SF && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1202 PM CDT WED JUL 30 2008 .DISCUSSION... WILL ALLOW THE FLASH FLOOD WATCH TO EXPIRE AT 18Z. ADDITIONAL RAIN FALLING IN CENTRAL MISSOURI WILL NOT BE ENOUGH TO CAUSE FLASH FLOODING THIS AFTERNOON. PC && .PREV DISCUSSION... /547 AM CDT WED JUL 30 2008/ CIRCULATION CENTER ASSCD WITH THE REMNANTS OF DOLLY HAS SHIFTED INTO SERN KS WITH AN ELONGATED SHEAR AXIS EXTENDING NE INTO CENTRAL/NORTH CENTRAL MISSOURI. LATEST GFS/RUC APPEAR TO HAVE A MUCH BETTER HANDLE ON THE SITUATION AS THE NAM QPF HAS BEEN MUCH TOO FAR NORTH OVERNIGHT. A RATHER SHARP H7/H5 DEFORMATION ZONE HAS LIMITED THE NWD EXTENT OF THE HEAVY PRECIP SHIELD...FM KC AREA ENE TO NR MACON. THIS IS WELL HANDLE BY THE GFS WITH THE GFS TO SHIFT THIS AXIS SLOWLY SE THROUGH THE DAY. A VERY IMPRESSIVE H8/H7 THETAE RIDGE WAS POSITION NR THE DEFORMATION ZONE WITH COPIOUS AMOUNT OF TROPICAL MOISTURE...2-2.5 PRECIPITABLE WATER...RESULTING IN VERY HEAVY RAINFALL AMOUNTS. CLOUD TOPS HAVE WARMED THE LAST FEW HOURS AS THE LLJ HAS VEERED. HOWEVER...EXCESSIVE RAINFALL AMOUNTS ARE STILL LIKELY THIS MORNING BEFORE SYSTEM BEGINS TO WEAKEN AND BEGIN ITS DIURNAL DECREASE IN THE AFTN. SINCE RADAR TRENDS VERIFY THE LATEST GFS...HAVE REMOVED THE XTRM NRN EXTENT OF THE FFA. OTHERWISE...HAVE CONCERN ABOUT LOW CLOUDS AND FOG TNGT. MORE CONFIDENT IN AREAS OF FOG AFTER MIDNIGHT IN AREAS WHICH HAVE RECEIVED THE HEAVY RAIN TODAY. UPPER RIDGE OF HIGH PRESSURE TO BUILD INTO THE REGION THURSDAY AND FRIDAY WITH VERY WARM TEMPERATURES RETURNING. DB && .AVIATION... INTERMITTENT MVFR/IFR CONDITIONS ARE EXPECTED THIS MORNING ASSOCIATED WITH THE PRECIPITATION SHIELD. THE PRECIPITATION SHIELD WILL GRADUALLY SHIFT SOUTHEAST WITH THE LOW CLOUD DECK TO RISE TO THE VFR CATEGORY BY EARLY TO MID AFTERNOON. NEXT CONCERN IS LATE TONIGHT. SKIES WILL CLEAR TONIGHT...AND WITH LIGHT WINDS...A MOIST AIR MASS AND WET GROUND...MVFR AND IFR CONDITIONS IN FOG ARE LIKELY. DB && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 335 PM CDT WED JUL 30 2008 .DISCUSSION... ...MAIN CHALLENGES ARE LOW POPS...AS WELL AS HIGHS THROUGH 7 DAYS... THE OVERALL THERMODYNAMIC CHARACTERISTICS OF THE AIRMASS IN THE FORECAST AREA HAS NOT CHANGED SIGNIFICANTLY IN THE PAST SEVERAL DAYS. 12Z OAX SOUNDING CONTINUES TO SHOW A WARM AND CAPPED BOUNDARY LAYER. THE PRECIPITATION FORECAST APPEARS TO BE LARGELY A FUNCTION OF HOW THIS AIRMASS MIGHT CHANGE...AND WHAT FORCING MECHANISMS COULD PUSH PARCELS TO THE LFC. OR...IF EXISTING UPSTREAM CONVECTION COULD BE SUSTAINED IN THIS AIRMASS. IN THE NEAR TERM OF TONIGHT...A SMALL AND DECAYING CLUSTER OF STORMS MOVING THROUGH NORTHWEST IOWA HAS PUSHED A WELL DEFINED OUTFLOW BOUNDARY INTO THE OMAHA-COUNCIL BLUFFS METRO AREA PER VISIBLE SATELLITE IMAGERY AND 20Z SUBJECTIVE SURFACE ANALYSIS. HOWEVER...LFC HEIGHT AS ESTIMATED FROM RUC SOUNDINGS AND 12Z OAX SOUNDING APPEARS TO BE AROUND 8000 FEET AGL...WHICH IS HIGHER THAN THE OUTFLOW CAN LIFT. OUTFLOW ALSO APPEARS SOMEWHAT DIFFUSE AND IS DECELERATING. KEPT JUST A SLIGHT CHANCE IN FAR NORTHERN COUNTIES TONIGHT TO ACCOUNT FOR ANY ACTIVITY EITHER ASSOCIATED WITH THIS BOUNDARY OR ANY POTENTIAL CONVECTION THAT MIGHT MOVE SOUTHEAST FROM SOUTH DAKOTA. WEAK FRONTAL BOUNDARY STILL EXISTS IN CENTRAL SOUTH DAKOTA SO CONVECTION THERE IS POSSIBLE WHICH COULD FOLLOW SOUTHEAST ORIENTED CORFIDI VECTORS OVERNIGHT. FOR THURSDAY...THE MODELS ARE IN AGREEMENT WITH BRINGING A VERY LOW AMPLITUDE SHORTWAVE INTO THE PLAINS AND DRAGGING A FRONT INTO FORECAST AREA THURSDAY AFTERNOON AND EVENING. MEANWHILE...MID TROPOSPHERIC TEMPERATURES ACTUALLY WARM SLIGHTLY DUE TO THE BUILDING UPPER RIDGE. THEREFORE AS THE FRONT MOVES THROUGH...THE CAPPING INVERSION STRENGTHENS. FORECAST SOUNDINGS ALONG AND JUST AHEAD OF THE FRONT DURING PEAK HEATING THURSDAY AFTERNOON SHOW FROM 150 J/KG TO 350 J/KG OF CONVECTIVE INHIBITION. THIS FRONT LOOKS TOO WEAK TO PUSH THROUGH THAT STRONG OF A CAP. ONLY POSSIBILITY MIGHT AGAIN BE IN THE FAR NORTHERN COUNTIES WHERE CAP WILL BE WEAKEST. KEPT SLIGHT CHANCE POPS FAR NORTH FOR THURSDAY EVENING AND OVERNIGHT. BY MID DAY SATURDAY THE UPPER RIDGE AXIS IS OVER THE CENTRAL PLAINS...THE H5 HEIGHTS SHOULD BE AT OR ABOVE 5910 METERS...AND A HOT AND CAPPED AIRMASS WILL HAVE A STRONG HOLD ON THE FORECAST AREA. HIGH TEMPERATURES WILL CLIMB THROUGH THE 90S...AND CONVECTION SHOULD BE FULLY SUPPRESSED. FOR NEXT WEEK...THE ECMWF MODEL WAS FAVORED OVER THE GFS BY HPC DUE TO BETTER CONTINUITY...AND THE ECMWF HELD ONTO THE STRONG RIDGING PATTERN THROUGH WEDNESDAY. SOMEWHAT SURPRISINGLY...IT STILL SHOWED SOME AGREEMENT WITH THE GFS IN BRINGING A WEAK FRONT INTO THE REGION TUESDAY. AGAIN WE FEEL THAT THE AIRMASS WILL REMAIN TOO WARM AND CAPPED FOR CONVECTION...BUT KEPT SMALL POPS TUESDAY NIGHT ONLY TO ACCOUNT FOR THE FRONT AND POTENTIAL FOR UPSTREAM CONVECTION. STILL FEEL THE GFS MOS HIGH TEMPERATURES ARE SHOWING A BIAS OF BEING TOO WARM PER RECENT VERIFICATION...THUS KEPT FORECAST A FEW DEGREES BELOW GFS MOS. DESPITE THIS...THE HEAT INDEX VALUES WILL HIT THE 100-105 RANGE STARTING SATURDAY. WILL CONTINUE TO MENTION HEAT IN THE HWO. && .AVIATION... FOR TAF SITES KOMA/KLNK/KOFK THRU 31/18Z. TWO SHORTWAVE TROUGHS WILL PUSH MAINLY NORTH OF THE TAF SITES DURING THE FCST PD...THUS A FEW SCT CLDS TODAY AND SOME MID CLOUDS POSSIBLE ESPECIALLY AT KOFK/KOMA LATER TONIGHT AND THU MORNING. DID INCLUDE MENTION OF MVFR VSBYS WITH FOG POSSIBLE AT KOMA AND KLNK EARLY THURSDAY MORNING. SFC WINDS EXPECTED TO INCREASE TO 10 TO 20 KTS FROM THE SW AFTER 15Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DISCUSSION...NIETFELD/KURTZ AVIATION...ZAPOTOCNY ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 338 PM EDT WED JUL 30 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO COVER THE REGION INTO THURSDAY. A COLD FRONT TO OUR NORTH WILL WEAKEN AND DISSIPATE ON THURSDAY. A PIEDMONT TROF WILL DEVELOP ON THURSDAY AND MOVE TO THE COAST BY FRIDAY AND STALL. HOT WEATHER WILL RETURN TO THE AREA OVER THE WEEKEND AHEAD OF THE NEXT ADVANCING COLD FRONT THAT WILL REACH THE COAST BY SUNDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 3 PM WEDNESDAY...MAIN FOCUS OF CONVECTION THIS AFTERNOON ALONG SEA BREEZE BOUNDARY...MAINLY SOUTH OF BRUNSWICK COUNTY WHERE BEST MOISTURE AND INSTABILITY LIES. SREF/RUC STILL POINTING AT BEST CHC OF CONVECTION ALONG SEA BREEZE AND INLAND ALONG THE PIEDMONT TROUGH THOUGH THIS EVENING. MEAN STORM MOTION WILL BRING ANY DEVELOPMENT EASTWARD. THEREFORE LEFT ISOLATED TO SCT SHOWERS ACROSS CWA THROUGH THIS EVENING. WITHOUT ANY UPPER LEVEL SUPPORT EXPECT SHOWER ACTIVITY TO END LATER THIS EVENING AS DIURNAL HEATING CUTS OFF...LEAVING ANOTHER QUIET BUT MUGGY OVERNIGHT PERIOD WITH TEMPS REMAINING IN THE LOWER TO MID 70S...A FEW DEGREES ABOVE CLIMO...AND DEWPOINTS HOLDING IN THE 70S. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 3 PM WEDNESDAY...MAIN CONCERN FOR THIS PERIOD IS THE DEVELOPMENT OF THE PIEDMONT TROF THAT WILL SLOWLY MAKE ITS WAY TO THE COAST BY FRIDAY. TEMPERATURES LOOK TO BE ABOVE CLIMO FOR THIS PERIOD EVEN NEAR THE COAST AS WEAK SEA BREEZE DOES LITTLE TO BRING RELIEF. HAVE ABOUT 40 POPS OVER THE INLAND AREAS FOR THURSDAY AFTERNOON IN RESPONSE TO THE TROF WITH JUST ABOUT 30 POPS NEAR THE COAST. HAVE KEPT THE POPS AROUND 30 PCT FOR FRIDAY AS UPPER LEVELS A BIT WARM TO SEE ANY WIDESPREAD PCPN ACROSS THE COAST AS TROF MOVES NEAR BUT CANNOT RULE OUT A FEW TSTMS OR SHOWERS ESPECIALLY WITH THE INTERACTION WITH THE WEAK SEA BREEZE. HAVE TAKEN A BLEND OF THE MET AND GFS MOS DATA FOR THE TEMPS WHICH WILL BE ABOVE CLIMO FOR THE NEXT TWO DAYS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 3 PM...WILL BEGIN THE PERIOD WITH AN EAST COAST UPPER TROF AND A DISSIPATING FRONTAL BOUNDARY OVER THE EASTERN CAROLINAS. THIS COULD KEEP THINGS A BIT UNSETTLED THRU THE WEEKEND...BUT A WESTERLY COMPONENT THRU A VERY DEEP LAYER WILL LIMIT POPS TO SLIGHT CHANCE. BY MONDAY OR TUESDAY A STRONG UPPER RIDGE WILL BUILD FROM THE PLAINS ALL THE WAY TO THE COAST...RESULTING IN WARMER THAN CLIMO TEMPS AND LITTLE OR NO CHANCE OF PRECIP FOR THE REST OF THE EXTENDED. FORECAST MAX TEMPS IN THE MID 90S INLAND AND LOWER 90S ALONG THE COAST...AND WITH DEWPOINTS NOT MIXING ANY LOWER THAN THE UPPER 60S EXPECT SEVERAL DAYS WITH AFTERNOON HEAT INDICES APPROACHING THE ADVISORY THRESHOLD OF 105. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... LATEST VISIBLE PICS SHOWING AN EXPANSIVE CU FIELD DEVELOPING ACROSS EASTERN SC SPREADING NORTHEAST. IN ADDITION SOME CU IS FORMING ALONG THE SEA BREEZE BOUNDARY WHICH WILL CONTINUE TO PUSH INLAND. NO CHANGES TO THE PREVIOUS SET OF TAFS WITH CONVECTION POSSIBLE THIS AFTERNOON ALONG THE SEA BREEZE AND FARTHER INLAND NEAR THE PIEDMONT TROF. SOME BRIEF IFR CONDITIONS POSSIBLE DUE TO HEAVY RAIN BUT THE DURATION IS TOO SHORT TO PUT THEM IN THE PREVAILING GROUPS. BEST TIMING FOR STORMS WILL BE BETWEEN 18Z AND 01Z. SOUTHWESTERLY WINDS WILL BECOME GUSTY AT THE COAST AS THE RESULTANT SEA BREEZE MOVES FARTHER INLAND. CONVECTION DIES DOWN SHORTLY AFTER SUNSET TONIGHT WITH SOME DEBRIS CLOUDS POSSIBLE THROUGH 04Z. VFR CONDITIONS EXPECTED FOR MOST OF THE TERMINALS WITH IFR CEILINGS DUE TO STRATUS AT THE INLAND TERMINALS AFTER 10Z. THE NAM BUFKIT SOUNDINGS WHICH DID A GREAT JOB WITH THE STRATUS THIS MORNING ARE NOT AS BULLISH TONIGHT WITH THE STRATUS. WITH THAT SAID LITTLE HAS CHANGED IN THE LOWER PART OF THE ATMOSPHERE AND THE PROSPECTS OF SOME RAIN TODAY MAY MAKE US EVEN MORE MOIST TONIGHT. GIVEN THIS I PUT IN IFR CEILINGS IN THE TAFS FOR NOW WITH PLENTY OF TIME TO ADJUST AS WE GET CLOSER TO 06Z. WITH A SOUTHWEST TO WEST-SOUTHWEST WIND FROM THE SURFACE UP THROUGH 8K...IF THIS STRATUS DECK DEVELOPS WE WILL HAVE TO WATCH FOR IT ADVANCING INTO THE MYRTLES TOWARD DAYBREAK. OUTLOOK THROUGH SUNDAY...A COLD FRONT WILL APPROACH THE AREA THURSDAY AND MOVE THROUGH FRIDAY. THIS WILL BE ENOUGH TO KEEP THE CHANCE FOR MAINLY AFTERNOON/EVENING CONVECTION IN THE FORECAST. OVER THE WEEKEND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST AND KEEPS THE AREA DRY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM WEDNESDAY...HIGH PRESSURE OFFSHORE AND TROUGH OVER INLAND WILL COMBINE TO KEEP UP A SWLY FLOW OVER THE COASTAL WATERS. ONCE AGAIN A PINCHED GRADIENT INTO TONIGHT WILL KEEP WINDS AROUND 15 KTS OR SO AND SEAS 3 TO 4 FT IN THE OFF SHORE WATERS OVERNIGHT. && SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 PM WEDNESDAY...SW FLOW CONTINUES ACROSS THE COASTAL WATERS ON THURSDAY WITH A SLIGHT TIGHTENING OF THE GRADIENT DURING THE AFTERNOON WHICH WILL KEEP THE SEAS UP TO 4 TO 5 FT WITH 2 TO 4 FEET CLOSER TO SHORE...MAY EVEN SEE UP TO 6 FEET OUT TOWARDS FRYING PAN. A WEAK TROF MOVES FROM THE PIEDMONT REGION TO THE COAST ON FRIDAY BUT WILL REMAIN OVER LAND WHICH WILL RESULT IN OUR WINDS STILL REMAINING FROM THE SW AROUND 10 KTS WITH SEAS RUNNING ABOUT 2 TO 3 FT. WITH TROF NEARING THE COAST BY THURSDAY AND REMAINING IN THE AREA FOR FRIDAY WILL HAVE JUST CHANCE POPS OVER THE WATERS FOR THE PERIOD. && LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 PM...WILL MAINTAIN A GENERAL SW WIND DIRECTION THROUGH THE PERIOD...WITH THE SEABREEZE DRIVING AN OSCILLATION TO S/SSW EACH AFTERNOON...AND PERHAPS EVEN WESTERLY IN THE LATE NIGHT/EARLY MORNING HRS. SPEEDS WILL BE LIMITED TO AROUND 15 KT...THO A STRONGER THAN EXPECTED PIEDMONT TROF COULD GIVE US 15-20 KT AT SOME POINT. SEAS GENERALLY AROUND 3 FT...NOT DEVIATING MUCH FROM WW3 GUIDANCE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS.../MAC NEAR TERM...RGZ SHORT TERM...MAC LONG TERM...RAS AVIATION...EH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 330 PM EDT WED JUL 30 2008 .SYNOPSIS... A COLD FRONT OVER THE LOWER GREAT LAKES WILL MOVE SLOWLY SOUTH INTO THE OHIO VALLEY DURING THURSDAY. THE FRONT WILL WEAKEN AS IT MOVES TO ALONG THE OHIO RIVER ON FRIDAY AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... WEAK COLD FRONT/TROUGH OVER CENTRAL GREAT LAKES WILL TAKE ITS TIME GETTING THROUGH THE AREA. RUC MODEL SHOWS ANOTHER PREFRONTAL TROUGH FORMING ACROSS SE LOWER MI AND SW ONTARIO THIS AFTERNOON AND PUSHING SOUTHEAST ACROSS THE AREA EARLY TONIGHT. WILL HAVE TO LEAVE A CHANCE/SLIGHT CHANCE OF A SHOWER/TSTORM JUST ABOUT ANYWHERE EARLY TONIGHT ALTHOUGH COVERAGE MAY NOT BE THAT EXTENSIVE UNLESS A LINE FORMS...WHICH I DOUBT SINCE IT IS REALLY NOT THAT UNSTABLE OUT THERE. DEWPOINTS WILL REMAIN HIGH THROUGH THE NIGHT. PREFER WARMER TEMP GUIDANCE WITH SW FLOW AHEAD OF TROUGH EXCEPT EXTREME NE OH/NW PA WHERE THERE WAS ENOUGH RAIN TODAY THAT THE ATMOSPHERE WAS COOLED. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... MODEL POP GUIDANCE IS TOO LOW FOR THURSDAY. TROUGH WILL NOT BE SOUTH OF THE AREA UNTIL LATE AFTERNOON/EARLY EVENING AND BELIEVE WE WILL SEE AT LEAST A SCATTERING OF TSTORMS DEVELOP...MAINLY OVER INLAND NE OH/NW PA. SHOULD DRY OUT ACROSS NW OHIO AND ALONG THE LAKESHORE DURING THE DAY AND DEWPOINTS WILL MIX OUT AND DROP TO THE LOWER 60S...NOT EXACTLY CRISP AND COMFORTABLE BUT AN IMPROVEMENT WHICH SHOULD BE NOTICEABLE BY LATE AFTERNOON OR EVENING. MAX TEMP GUIDANCE MAY BE A DEGREE OR TWO TOO WARM. WILL FORECAST HIGHS FROM THE LOWER 80S NW PA TO THE UPPER 80S NW OH. MODELS RELATIVELY CONSISTENT AND SIMILAR GOING INTO THE WEEKEND. FRIDAY SHOULD BE A DRY DAY WITH TEMPS NEAR NORMAL. ALL MODELS HAVE SETTLED IN ON A SLIGHTLY SLOWER ONSET OF THE HEAT... CLOSER TO THE ECMWF SOLUTION. THE DELAY IS PARTLY DUE TO A WEAK SHORT WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES FRIDAY NIGHT. THE ASSOCIATED WEAK COLD FRONT/TROUGH WILL LIKELY SET OFF SHOWERS/TSTORMS OVER THE GREAT LAKES WHICH SHOULD MOVE SSE TOWARD THE FCST AREA (NW OHIO) BY FRIDAY EVENING. NOT SURE AT THAT POINT WHERE THE STORMS WOULD TRACK OR HOW LONG THEY WOULD LAST. FRIDAY WILL NOT BE THE MOST UNSTABLE DAY SO IT IS UNLIKELY THAT A DERECHO OR HUGE TSTORM COMPLEX WOULD ROAR ACROSS THE AREA BUT CERTAINLY THERE COULD BE A CHANCE OF SHOWERS/TSTORMS FOR A WHILE FRIDAY NIGHT JUST ABOUT ANYWHERE AS THE WEAK FRONT/TROUGH PUSHES INTO THE AREA. WITH NW FLOW ALOFT AND TIMING OF ANY PARTICULAR FEATURE UNCERTAIN... CANNOT RULE OUT A TSTORM OR TWO AROUND ON SATURDAY...ESPECIALLY IF THE WEAK FRONT/TROUGH FROM FRIDAY NIGHT HAS NOT CLEARED THE AREA. THINK MOST OF THE AREA WILL BE RAINFREE THOUGH AND WILL USE SLIGHT CHANCE POP (15-24 PERCENT). TEMPS SATURDAY MAYBE A CATEGORY WARMER THAN FRIDAY BUT DEWPOINTS WILL BE CREEPING BACK UP. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MODELS COMING INTO BETTER AGREEMENT MOVING HIGH ACROSS AREA SUNDAY...THEN STALLING HIGH JUST EAST OF THE AREA...ALLOWING WARM UP FOR THE EARLY PART OF NEXT WEEK. MODELS SHOW FRONT STALLING ACROSS CENTRAL LAKES BY MID WEEK...ALLOWING FOR CHC OF TSRA TUES AND WEDNESDAY. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... SHOWERS/TSRA NE OHIO MOVING EAST AT 25 KNOTS AND SHOULD BE EAST OF THE FORECAST AREA TOWARD 20Z. CLEARING SKIES BETWEEN SANDUSKY AND LORAIN WILL SPREAD OVER AREA BY 21Z. THIS WILL ALLOW ISOLATED TSRA TO DEVELOP OVER AREA. TSRA WILL DIMINISH AFTER SUNSET. EXPECT AREAS OF MVFR BR TO DEVELOP TOWARD DAYBREAK...BUT BURN OFF BY MID MORNING THURSDAY. COLD FRONT NOW ACROSS LAKE HURON WILL PUSH SOUTH ACROSS THE AREA TOMORROW AFTERNOON...SO EXPECT SOME TSRA TO DEVELOP TOMORROW AFTERNOON...MAINLY SOUTH OF CLE. OUTLOOK...HIGH PRESSURE WILL BUILD IN THURSDAY NIGHT INTO FRIDAY WITH VFR CONDITIONS EXPECTED. WEAK TROUGH MOVES THROUGH SATURDAY PROVIDING FOR A SLIGHT CHANCE OF SOME SHOWERS OR THUNDERSTORMS WITH LOCAL NON VFR WEATHER. VFR AGAIN ON SUNDAY WITH HIGH PRESSURE MOVING BACK IN. && .MARINE... LAKE BREEZE TO RELAX THIS EVENING AND THEN FLOW ON LAKE TO BE MORE CLOSELY CONNECTED TO SYNOPTIC FLOW AS COLD FRONT APPROACHES FROM THE MIDWEST/CENTRAL GREAT LAKES. SOME SHOWER/THUNDERSTORM ACTIVITY POSSIBLE PRECEDING THE FRONT WEDNESDAY WITH THE FRONT PASSING WEDNESDAY EVENING. LITTLE CHANGE IN WIND DIRECTION OR SPEED WITH THE ACTUAL FRONT...BUT MORE SO WITH TROUGH THAT FOLLOWS THURSDAY. THIS IS WHEN WINDS WILL COME AROUND TO THE NORTHWEST WITH HIGH PRESSURE FOR FRIDAY THROUGH SUNDAY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...THOMPSON NEAR TERM...KOSARIK SHORT TERM...KOSARIK LONG TERM...DJB AVIATION...DJB MARINE...OUDEMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 214 PM EDT WED JUL 30 2008 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY...WITH ANOTHER ONE EXPECTED ON SATURDAY. HIGH PRESSURE WILL BUILD IN FOR SUNDAY THROUGH MONDAY NIGHT. && .NEAR TERM /THROUGH THURSDAY/... SATELLITE AND RADAR DATA SUPPORT THE 12Z NAM AND RUC FOR THIS AFTERNOON AND EVENING. ONE VORT ACROSS NORTH-CENTRAL OHIO WILL CLIP OUR NORTHERN COUNTIES AS IT MOVES EAST...WHILE ANOTHER VORT OVER WESTERN KENTUCKY WILL MOVE EASTWARD ACROSS OUR CENTRAL AND SOUTHERN AREAS. THE PROBLEM IS...WITH THE WEAK DYNAMICS AND FLOW WITH THESE VORTS...HEATING AND MOISTURE WILL BE THE MAIN PLAYERS FOR CONVECTION. MID TO HIGH CLOUDS ARE INVADING FROM THE WEST FROM DIURNALLY DYING CONVECTION FROM THE KENTUCKY VORT...AND IS SUPPORTED BY PW`S NEAR 2 INCHES...SO WILL LIKELY HOLD TOGETHER AS IT OVERSPREADS THE WESTERN HALF OF THE AREA THIS AFTERNOON. THIS WILL ACT TO LIMIT THE HEATING POTENTIAL AND CONVECTIVE REDEVELOPMENT OVER WESTERN HALF OF OUR AREA. ON THE OTHER HAND...WILL NOT TAKE MUCH HEATING IN THE MOIST ADIABATIC ATMOSPHERE THIS AFTERNOON TO GENERATE SCATTERED CONVECTION. SO...BEST POPS WILL ACTUALLY BE IN THE EAST AND SOUTH WHERE BEST HEATING WILL INTERACT WITH THE VORTS. WILL GO LIKELY THERE AND CHANCE ELSEWHERE. OTHERWISE...LOWERED TEMPS A FEW DEGREES IN THE WEST WITH ALL THE CLOUDS. PREVIOUS DISCUSSION BELOW... UPPER AND MID LEVEL CLOUDS ASSOCIATED WITH DYING MCS ACROSS THE OH VALLEY WILL CONTINUE TO MOVE ACROSS THE AREA TODAY. THESE CLOUDS WILL KEEP TEMPERATURES INTO THE MID 80S LOWLANDS...RANGING TO THE MID 70S HIGHEST ELEVATIONS. BREAKS IN THE CLOUDS COULD PRODUCE SOME DIFFERENTIAL HEATING BOUNDARIES THAT COULD SERVE AS FOCUS MECHANISM FOR AFTERNOON SHOWERS AND THUNDERSTORMS UNDER A MARGINALLY UNSTABLE ATMOSPHERE WITH CAPE VALUES AROUND 1800 J/KG. IN ADDITION...BOTH GFS AND NAM BRING A SHORT WAVE EVIDENT AS H5 VORT MAXES MOVING FROM NORTHWEST TO SOUTHEAST THIS AFTERNOON AND EVENING. KEPT CHANCE POPS ACROSS THE ENTIRE AREA AS IT IS DIFFICULT TO PINPOINT THE LOCATIONS OF WHERE DIFFERENTIAL HEATING BOUNDARIES WILL OCCUR. WITH THE AMOUNT OF CLOUDS EXPECTED...WENT COOLER THAN MET AND MAV...ACTUALLY CLOSER TO THE LAV GUIDANCE FOR HIGHS THIS AFTERNOON. TONIGHT LOWS WERE A BLEND OF MET AND MAV NUMBERS. ANY PREDAWN FOG AND LOW CLOUDS WILL BURN OFF SHORTLY AFTER SUNRISE. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... MODELS SUGGEST MID-LEVEL SHORTWAVE TROF WILL BE LOCATED SOUTHEAST OF THE REGION AT THE BEGINNING OF THE PERIOD. BECAUSE OF THIS AND THE LOSS OF DAYTIME HEATING...EXPECT SMALL THUNDERSTORM CHANCES EARLY THURSDAY NIGHT WILL QUICKLY DECREASE WITH DRY CONDITIONS EXPECTED BY MIDNIGHT. WEAK HIGH PRESSURE SHOULD BE IN CONTROL ON FRIDAY...WITH HOT AND DRY WEATHER ANTICIPATED. A WEAK COLD FRONT IS EXPECTED TO IMPACT THE WEATHER ACROSS THE REGION FROM LATE FRIDAY NIGHT INTO SATURDAY NIGHT. HOWEVER... MODELS DIFFER ON THE SPEED OF THE FRONT. HAVE CHOSEN TO GO BETWEEN THE SPEED OF THE NAM...TOO SLOW...AND GFS...TOO FAST. BECAUSE OF UNCERTAINTY...HAVE ALSO CHOSEN TO INTRODUCE ONLY LOW CHANCE POPS FOR SATURDAY. THE FRONT SHOULD BE EAST OF THE REGION...WITH DRY WEATHER ANTICIPATED REGION-WIDE EARLY SATURDAY NIGHT. MIN T GRIDS FOR WEDNESDAY/THURSDAY NIGHTS AND MAX T GRIDS FOR THURSDAY APPEAR REASONABLE...SO HAVE NOT MADE ANY MAJOR CHANGES. LATEST MEX NUMBERS FOR SATURDAY AND SATURDAY NIGHT APPEAR TOO COOL...BUT HAVE TWEEKED THE HIGHS ON SATURDAY A DEGREE OR TWO TO REFLECT THE COOLER GUIDANCE. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GENERALLY FOLLOWED HPC THINKING DURING THIS PERIOD. UPPER LEVEL TROUGH IS PROGGED ALONG EAST COAST AT BEGINNING OF PERIOD. THIS FEATURE MOVES EAST BY MONDAY...ALLOWING UPPER LEVEL RIDGE AND HOT DAYTIME TEMPERATURES TO BUILD INTO THE AREA. LATEST THINKING IS THAT AXIS OF UPPER RIDGE WILL REMAIN TO THE SOUTH OF REGION...RESULTING IN WESTERLY/NORTHWESTERLY UPPER FLOW ACROSS AREA. LONG RANGE MODELS SUGGEST A WARM FRONT WILL LIFT NORTHEAST ON TUESDAY AS AN AREA OF SURFACE LOW PRESSURE APPROACHES FROM THE WEST. BECAUSE OF THIS...HAVE INTRODUCED LOW THUNDERSTORM CHANCES FOR TUESDAY MORNING THROUGH WEDNESDAY. && .AVIATION /15Z WEDNESDAY THROUGH MONDAY/... 15Z WEDNESDAY THRU 12Z THURSDAY... VERY MOIST AND UNSTABLE ATMOSPHERE WILL BRING THREAT OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS...MAINLY THIS AFTERNOON AND EARLY TONIGHT. BEST CHANCES ARE IN THE EAST AND SOUTH WHERE CLOUDS WILL BE LEAST AND ALLOW FOR HEATING. EXPECT LOTS OF MID TO HIGH CLOUDS WEST OF A PKB TO CRW LINE THIS AFTERNOON AND TONIGHT TO LIMIT CONVECTION. THUS...MENTIONED ONLY CB AT PKB...HTS AND CRW WITH NO TEMP PERIOD FRO THUNDER. INCLUDED TEMP PERIOD 19Z-23Z OF THUNDER AT EKN...BKW...AND CKB. OTHERWISE...GENERALLY VFR OUTSIDE THE CONVECTION THIS AFTERNOON AND EVENING. OVERNIGHT...VERY DIFFICULT...AS CONVECTION WILL LIKLEY DIMINISH GREATLY WITH LOSS OF HEATING...BUT FOG MAY BE AN ISSUE WHERE IT RAINS THIS AFTERNOON. THUS...WITH GREAT UNCERTAINTY...DECIDED NOT TO ADDRESS FOG OVERNIGHT. AVIATION OUTLOOK /AFTER 12Z THU/...STRONG THUNDERSTORMS WITH IFR CONDITIONS AND STRONG GUSTY WINDS POSSIBLE THUR EVENING INTO FRI ACROSS MAINLY ACROSS THE NORTHERN SITES...PKB AND CKB. NO SIGNIFICANT WEATHER FORECAST FRI AFTERNOON THRU SUN. && .CLIMATE... THE ENTIRE CLI FOR EKN IS MISSING AGAIN. && .EQUIPMENT... NO CHANGE IN THE ASOS STATUS AT EKN. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JSH NEAR TERM...JMV SHORT TERM...JSH LONG TERM...JSH AVIATION...JMV CLIMATE... EQUIPMENT... oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1153 AM CDT WED JUL 30 2008 .UPDATE... EARLY MORNING CONVECTION HAS MOVED SOUTH AND NOW THE REGION IS NEARLY CLOUD FREE...WITH TEMPERATURES WELL ON TRACK TO MEET FORECASTED HIGHS. MAIN CONCERN FOR THE SHORT TERM IS THE CHANCE FOR THUNDERSTORM DEVELOPMENT ALONG FRONTAL BOUNDARY POSITION ACROSS CENTRAL SD AND OUTFLOWS FROM EARLIER CONVECTION. THE WHOLE FORECAST HINGES ON TWO THINGS...MID LEVEL CAP TEMPERATURES AND DEWPOINTS. MODEL H7 TEMPERATURE SPREAD IS NEARLY 1C...AND DETERMINES THE DIFFERENCE BETWEEN CAPED AND UNCAPPED. IN THE SAME RESPECT...SURFACE DEWPOINTS...OF WHICH THE MODEL SUITE IS DOING FAIRLY WELL WHEN COMPARED TO MSAS OBSERVATIONS...ARE THE SECOND LINCHPIN OF THE FORECAST. MORNING SOUNDINGS INDICATE DRIER AIR ABOVE THE MORNING BOUNDARY LAYER. AM UNSURE HOW EFFECTIVELY DRIER AIR WILL COUNTERACT LOW LEVEL MOISTURE ADVECTION AND EVAPOTRANSPIRATION...AND GUIDANCE CONSERVATION IN BL MOISTURE THROUGH THE DAY IS FEASIBLE. ANY STORMS THAT DO FORM WILL BE OCCURRING IN A HIGH CAPE ENVIRONMENT OF 2-3000J/KG AND CURVED HODOGRAPHS. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY CURRENT WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS UPPER LEVEL RIDGE AXIS CENTERED OVER THE NORTHERN HIGH PLAINS WITH A WEAK RIPPLE AT 700 MB MOVING ACROSS THE AREA. VORT MAX ALSO MOVING ACROSS NORTH DAKOTA AND NORTH CENTRAL SOUTH DAKOTA...WITH LLJ IN PLACE ACROSS SOUTH CENTRAL AND SOUTHWEST SOUTH DAKOTA. ALL THIS IS INTERACTING WITH JUST ENOUGH ELEVATED INSTABILITY TO PRODUCE ACCAS AND ISO SHOWERS/THUNDERSHOWERS ACROSS PORTIONS OF CENTRAL AND SOUTHEASTERN SOUTH DAKOTA EARLY THIS MORNING. RUC/NAM PICKING UP ON THIS FAIRLY WELL AND SHOWS THIS ACTIVITY LINGERING INTO THE MORNING HOURS. HAVE THEREFORE EXPANDED SLIGHT CHANCE POPS A BIT FURTHER EAST INTO THE MORNING HOURS. WARM FRONT POSITION BECOMING A LITTLE BETTER DEFINED ON SFC OBS THIS MORNING WITH PIR/HON/BKX SHOWING SOUTHEAST WINDS AND OBS TO THE NORTH WITH EITHER LIGHT EASTERLY WINDS OR LIGHT/VARIABLE WINDS. MODELS SHOW THE WARM FRONT TO BASICALLY REMAIN IN THIS POSITION ALL DAY. WILL KEEP SLIGHT CHANCE POPS GOING INTO THE AFTERNOON HOURS EVEN THOUGH A LARGE PORTION OF THE CWA SHOULD REMAIN CAPPED. SVR PARAMETERS DO SUPPORT STRONG TO SEVERE THIS AFTERNOON/EVENING WITH ANY STORMS THAT CAN GET GOING. ATTENTION THEN TURNS TO THURSDAY WHEN ANOTHER FRONTAL BOUNDARY LOOKS TO TRACK EASTWARD ACROSS THE AREA. 700 MB TEMPS BEGIN TO INCREASE EVEN MORE ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...APPROACHING 15 DEGREES C. MUCH OF THE AREA SHOULD REMAIN CAPPED...EXCEPT FOR PERHAPS THE FAR NORTHERN/NORTHEASTERN CWA AND HAVE INCLUDED SLIGHT CHANCE POPS FOR THESE AREAS LATE WEDNESDAY NIGHT AND INTO THURSDAY. MODELS HAVE BEEN FAIRLY CONSISTENT IN BRINGING SOME SORT OF CONVECTIVE COMPLEX ACROSS NORTH DAKOTA AND POSSIBLY EXTREME NORTHERN SOUTH DAKOTA LATE WEDNESDAY NIGHT AND THURSDAY. THIS FRONTAL BOUNDARY IS FORECAST TO MOVE OUT OF THE AREA BY THURSDAY EVENING...LEAVING DRY CONDITIONS UNDER WEAK HIGH PRESSURE. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY A FAIRLY STRONG UPPER RIDGE WILL BE THE DOMINANT FEATURE OVER THE PLAINS STATES THROUGHOUT THE EXTENDED PERIOD. THE RIDGE WILL DAMPEN SOME ON MONDAY AS A SHORTWAVE TROUGH SLIDES ACROSS CANADA...BUT THEN BUILDS RIGHT BACK UP ON TUESDAY. A SURFACE FRONT WILL EXTEND FROM EASTERN MONTANA TO CENTRAL NEBRASKA TO THE GREAT LAKES FRIDAY NIGHT. HIGH PRESSURE WILL DROP SOUTH OVER MINNESOTA AND WISCONSIN ON SATURDAY AS LOW PRESSURE STRENGTHENS OVER THE WESTERN DAKOTAS. A WARM FRONT ASSOCIATED WITH THIS LOW PUSHES TO NORTHERN SOUTH DAKOTA ON SUNDAY...THEN FURTHER NORTHWARD AS THE LOW CENTER TRACKS TO THE CENTRAL DAKOTAS SUNDAY NIGHT. THE COLD FRONT TRACKS ACROSS THE CWA MONDAY AND EAST OF THE REGION MONDAY NIGHT...WITH HIGH PRESSURE SLIDING OVER THE NORTHERN PLAINS BEHIND THE EXITING FRONT ON TUESDAY. NOT REAL CONFIDENT IN PRECIPITATION CHANCES WITH EITHER OF THE FRONTAL PASSAGES AS H7 TEMPS WILL BE IN THE +12 TO +18 DEGREE RANGE FROM FRIDAY NIGHT THROUGH MONDAY NIGHT. WILL KEEP SMALL POPS IN ALONG AND NORTH OF THE WARM FRONT SATURDAY NIGHT...AND ALONG THE COLD FRONT SUNDAY NIGHT INTO MONDAY...BUT AGAIN...CONFIDENCE IS NOT HIGH ON PRECIPITATION BEING ABLE TO DEVELOP UNDER THE STRONG CAP. THE WARM TEMPERATURES ALOFT WILL TRANSLATE TO THE SURFACE AS WELL...WITH H85 TEMPS IN THE 20S TO LOWER 30S EVERY DAY EXCEPT TUESDAY. MEX GUIDANCE INDICATING HIGH TEMPERATURES OF 100+ DEGREES ACROSS THE WESTERN CWA SATURDAY THROUGH MONDAY...BUT DUE TO ABUNDANT RAIN AND GREENNESS ACROSS THE AREA...WILL STICK WITH TEMPS IN THE 90S FOR NOW. WILL SEE A TOUCH OF A COOL DOWN ON TUESDAY AS COOLER DRIER AIR MOVES IN IN ASSOCIATION WITH THE SURFACE HIGH. && .AVIATION... SOME ISOLD SHOWER AND THUNDERSTORM ACTIVITY REMAINS IN THE EXTREME SOUTHERN PORTION OF THE AREA. OUTSIDE OF THE FEW REMAINING CELLS EXPECT VFR CONDITIONS FOR MOST OF THE DAY WITH SCT MID AND HIGH CLOUDS AOA 10K FEET. LATER THIS AFTERNOON INTO THE EVENING...SCT CUMULUS WILL DEVELOP...ALONG WITH A SLIGHT CHANCE OF A THUNDERSTORM THROUGH THE EVENING AND OVERNIGHT HOURS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...CONNELLY SHORT TERM...TMT LONG TERM...PARKIN AVIATION...GIONTA WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 251 PM CDT WED JUL 30 2008 .DISCUSSION... BASE OF UPPER LEVEL TROUGH IS NOW WELL INTO NORTH TEXAS WITH THE AXIS ORIENTED FROM SW KANSAS TO CENTRAL TEXAS. UPPER LEVEL RIDGE IS ALSO WELL DEFINED IN THE RUC 500 MB ANALYSIS AND SATELLITE IMAGES OVER SOUTHERN ARIZONA. TONIGHT...THE TROUGH WILL SLIDE SOUTH AS THE RIDGE PUSHES EAST. ENERGY FROM THE REMNANTS OF THE TROUGH WILL REMAIN OVER NORTH TEXAS FOR THE NEXT FEW DAYS BUT RAIN CHANCES REMAIN SMALL AND DWINDLE BY THURSDAY AFTERNOON. AN ISOLATED CHANCE FOR SHOWERS OR STORMS EXISTS ON FRIDAY BUT ATTM THE CHANCE IS TOO SMALL TO MENTION AND KEPT 10 POPS. BY SUNDAY...THE UPPER LEVEL RIDGE WILL BE CENTERED IN THE CENTRAL PLAINS AND WILL THEN SETTLE OVER THE MISSISSIPPI RIVER VALLEY EARLY NEXT WEEK. THE INFLUENCE OF THE RIDGE ACROSS NORTH TEXAS WILL BE STRONG AND A RETURN TO TRIPLE DIGITS IS EXPECTED THIS WEEKEND...BUT TEMPERATURES SHOULD REMAIN JUST BELOW RECORD LEVELS. A WEAK FRONT IS WORKING ITS WAY INTO THE FAR NORTHWESTERN PORTIONS OF NORTH TEXAS. THIS FRONT IS NOT EXPECTED TO PUSH ANY FARTHER INTO NORTH TEXAS THAN A LINE FROM GAINESVILLE TO EASTLAND. ISOLATED SHOWERS AND THUNDERSTORMS ARE ALREADY STARTING TO REDEVELOP THIS AFTERNOON ALONG AND AHEAD OF THE FRONT. EXPECT SCATTERED RAIN ACTIVITY LATE THIS AFTERNOON TO REMAIN ACROSS THE WESTERN HALF OF THE CWA. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL THEN SHIFT OVER THE ENTIRE REGION LATER TONIGHT AS THE TROUGH AXIS CONTINUES TO MOVE SOUTH ACROSS NORTH TEXAS. MODELS AND MODEL SOUNDINGS INDICATE SOME INSTABILITY WILL BE PRESENT TONIGHT...SUPPORTIVE OF THUNDERSTORMS WITH CLOUD TO GROUND LIGHTNING AND POSSIBLY SOME GUSTY WINDS. WILL KEEP 30 POPS TONIGHT. RAIN WILL END FROM WEST TO EAST TOMORROW AND THEN THE FORECAST LOOKS DRY AFTER THAT. TEMPERATURE FORECAST FOR THIS PACKAGE CONTINUES TO BE ABOVE MOS GUIDANCE FOR THE MOST PART AND IS A FEW DEGREES WARMER THAN PREVIOUS FORECAST. BASED ON THIS FORECAST...A HEAT ADVISORY WILL LIKELY BE NEEDED FOR PARTS OF NORTH TEXAS THIS WEEKEND. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 79 99 78 100 81 / 30 20 10 10 10 WACO, TX 78 100 78 100 79 / 30 20 10 10 10 PARIS, TX 74 97 74 99 77 / 30 30 10 10 10 DENTON, TX 76 99 77 100 78 / 30 10 10 10 10 MCKINNEY, TX 75 98 76 101 77 / 30 20 10 10 10 DALLAS, TX 80 98 80 101 82 / 30 20 10 10 10 TERRELL, TX 77 98 76 100 77 / 30 30 10 10 10 CORSICANA, TX 77 97 76 98 77 / 30 20 10 10 10 TEMPLE, TX 76 98 75 99 75 / 30 20 10 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/82 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1210 PM CDT WED JUL 30 2008 .AVIATION... WILL STAY WITH THE THEME THAT WK FNTL BNDY NOW DRAPED FROM NEAR KTSA... KADM...KRPH...KABI...LINE WILL CONT TO SLOWLY MOVE ESE TOWARD D/FW METRO BY 00Z/AFTR. SHOULD SEE SCT SHRA/TSRA DEVELOPMENT ALONG BNDY BY 21Z TWD KXBP/KLUD/KMWL/KMKN/KBKD AREAS IN THE WRN N TX...THEN PUSH EWD. MAY TREND A LITTLE LATER THAN CWSU WITH VCTS AND EITHER TEMPO/PROB30 FOR KDFW/KDAL BY 02Z-03Z AND THRU 12Z. MAY KEEP THESE CONVECTIVE GROUPS VFR FOR NOW...THOUGH MVFR IS PSBL CONSIDERING WHAT WAS SEEN WITH HEAVIER RAIN THIS PREV MRNG. SSW WND ARND 10 KTS SHD BE SELY 8-12 KTS AFTR 00Z...THEN GO S/SWLY ARND 10 KTS AGAIN BY 12Z THURS/AFTR. AFTR 12Z...MAY JUST MAINTAIN VCTS /VCSH WORDING AS OUTFLOW DRIVING CONVECTION SHD BE PUSHING SE AWAY FROM D/FW TAFS/AIRPORTS...HOWEVER SHD BE AFFECTING KACT BY THEN...ALONG WITH SOME STRATUS. /05 && .UPDATE... LINE OF SHOWERS AND THUNDERSTORMS THAT MOVED OVER PARTS OF THE NORTHWESTERN HALF OF THE CWA THIS MORNING CONTINUE TO DIMINISH AT THIS HOUR. A FEW SMALL SHOWERS CONTINUE TO DEVELOP WEST OF THE I-35 CORRIDOR AND NORTH OF I-20 BUT MUCH OF THE AFTERNOON LOOKS TO BE DRY. CHANCE CONTINUES FOR THE REST OF THE DAY THAT ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP AND WILL CONTINUE WITH 20 POPS FOR MUCH OF THE AFTERNOON OVER ALL THE AREA. BY LATER THIS AFTERNOON/EARLY EVENING...MODELS ARE INDICATING ANOTHER REFIRING OF SHOWERS AND STORMS ACROSS THE WESTERN HALF OF THE CWA. HAVE INCREASED POPS TO 30 PERCENT AFTER 22Z AND MAY HAVE TO ADJUST HIGHER FOR TONIGHT. OTHERWISE CURRENT FORECAST IS ON TRACK AND ADJUSTED BASED ON CURRENT TRENDS. DID MAKE A FEW MINOR TWEAKS TO TEMPERATURES...TO INCREASE A DEGREE OR TWO IN THE WEST AND DECREASE A DEGREE IN THE NORTHEAST. 82/JLD && .PREV DISCUSSION... /ISSUED 245 AM CDT WED JUL 30 2008/ SCATTERED SHOWERS AND STORMS CONTINUE ALONG A MID LEVEL SHEAR AXIS /AS REPRESENTED IN RUC 500MB AND 700MB VORTICITY ANALYSIS/ EXTENDING FROM NORTH CENTRAL OKLAHOMA TO OUR WESTERN CWA AND INTO THE BIG BEND REGION. AS THIS SHEAR ZONE TRANSLATES ACROSS NORTH TEXAS TODAY EXPECT SCATTERED STORMS TO DEVELOP. THERE WILL BE A SLIGHT CHANCE OF STORMS THIS MORNING...WITH BETTER CHANCES THIS AFTERNOON OVER OUR EASTERN AND NORTHEASTERN ZONES. HOWEVER...HIGH TEMPERATURES WILL STILL MANAGE TO BE QUITE HOT THIS AFTERNOON WITH UPPER 90S COMMON AREA WIDE. SCATTERED STORM CHANCES WILL LINGER OVER OUR EASTERN CWA THROUGH TOMORROW EVENING. WHILE SOME OF THE MODELS SUGGEST PRECIP CHANCES WILL CONTINUE THROUGH FRIDAY...WILL MAINTAIN SILENT 10 POPS AT THIS TIME DUE TO UNCERTAINTY. OTHERWISE...CENTER OF THE MID LEVEL RIDGE WILL ANCHOR ITSELF OVER THE OZARKS EARLY NEXT WEEK...ALLOWING FOR TRIPLE DIGIT HEAT TO SETTLE OVER NORTH TEXAS ONCE AGAIN. SCHULTZ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 99 79 99 80 99 / 20 30 20 10 10 WACO, TX 99 79 99 79 99 / 20 30 20 10 10 PARIS, TX 95 73 97 75 96 / 20 30 20 10 10 DENTON, TX 98 75 98 77 98 / 20 30 10 10 10 MCKINNEY, TX 98 73 98 75 98 / 20 30 20 10 10 DALLAS, TX 98 79 99 80 98 / 20 30 20 10 10 TERRELL, TX 99 77 98 77 97 / 20 30 20 10 10 CORSICANA, TX 98 76 96 76 97 / 20 30 20 10 10 TEMPLE, TX 98 76 98 76 96 / 20 30 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/82 tx