AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1022 AM CDT FRI MAY 2 2003 NO SURPRISE THAT THE MODELS STRUGGLE WITH THE LOW-LEVEL MOISTURE FIELDS. DRIER AIR TRYING TO MAKE WAY SOUTHWARD INTO NRN CWA. GALESBURG NOW CLEAR...WHILE PEORIA IS ON THE NORTHERN EDGE OF THE EXTENSIVE CLOUD SHIELD. RUC RH/WIND FIELDS JUST ABOVE THE SURFACE SUGGEST THAT THIS DRIER TRENDS WILL CONTINUE IN THE WEST...WITH FLOW FROM THE N-NE. HAVE MADE MINOR ADJUSTMENTS TO THE TEMPS THIS AFT...UNIFORM IN THE LOWER 60S WEST...ADJUSTED COOLER IN THE EAST WITH THE PERSISTANT CLOUDS. .ILX...NONE. $$ PLAHMER il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 955 PM CDT FRI MAY 2 2003 MAIN QUESTIONS TNGT PCPN TRENDS...TEMPS...AND PATCHY FOG. BNDRY LYR COOLING EVIDENT AS AP EXPANDS ACRS FA...BUT SHWRS STILL HOLDING ON ALG AND N OF HIGHWAY 20. KINEMATIC FORCING LOOKS TO BE SUSTAINING PCPN AND SUBTLE SHRT WV IS NOTED IN WV IMAGERY MOVG THRU CNTRL IA. RUC QG FORCING ASSOCD WITH THIS FEATURE SLOWLY MOVG EWD SO HAVE ENDED SCT SHWR WORDING TWRD MIDNIGHT. HAVE SEEN A FEW LTG STRIKES...BUT NOT ENOUGH TO MENTION. ELEVATED INSTABILITY IS GRDLLY DCRG. RAISED TEMPS A CATEGORY GENERALLY ACRS NERN HALF OF FA. AFTN/EVE SHWRS HAVE ADDED SOME LOW LVL MSTR WITH AFTN CLDS ALSO KEEPING SUN FM DRYING BNDRY LYR MUCH. THIS ALSO LED ME INTRODUCE PATCHY FOG WRN AND NRN PTNS WHERE SFC RH IS ALREADY 75+ PERCENT. SHOULD SEE DECENT RADIATIONAL COOLING OVNGT AS CLDS SLOWLY DCR. .DSM...NONE $$ SMALL ia SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 815 PM EDT FRI MAY 2 2003 WILL UPDATE TO REFRESH THE CLOUD WORDING...AS CLOUDS HAVE TENDED TO THIN A BIT FASTER THAN EARLIER THOUGHT MOST AREAS BEHIND MAIN VORTICITY AS PER RUC AT 500 MB. STILL LOOKING FOR SOME SEMBLANCE OF CLOUDS OVERNIGHT CENTRAL AND SOUTH...ESPECIALLY SOUTH BEING IN PROXIMITY OF SHEAR LOBE THEN IA VORTICITY CENTER APPROACHING LATE TONIGHT. DWD THE FULL AFTERNOON DISCUSSION FOLLOWS... THE LATEST RADAR TRENDS INDICATE THAT WE CAN GO WITH A DRY FORECAST FOR TONIGHT. THE WAVE OVER THE SOUTHERN GREAT LAKES WILL MOVE EAST BY THIS EVENING AND FINALLY RENDER CONDITIONS LESS FAVORABLE FOR SHOWER DEVELOPMENT. THE SHORT WAVE RIDGE WILL GENERATE MID LEVEL SUBSIDENCE AND VEER THE FLOW ENOUGH TO HELP DRIVE DEEPER MOISTURE TO OUR SOUTH. CLOUD COVER AND TEMPS WILL BE THE MAIN CONCERN TONIGHT. NOTICED VERY DRY BOUNDARY LAYER AIR YIELDED LOW TEMPS IN THE MID 30S OVER MOST OF NORTHERN LOWER THIS MORNING WITH A WEAK GRADIENT WIND. IT LOOKS LIKE WE HAVE SIMILAR POTENTIAL FOR LOW TEMPS AND WIND TONIGHT OVER OUR AREA. THE COMPLICATING FACTOR WILL BE LESS MID AND HIGH CLOUDS TONIGHT COMPARED TO LAST NIGHT, ESPECIALLY IN THE SAGINAW VALLEY AND THUMB. MOSTLY CLEAR SKIES WILL ALLOW ENOUGH SURFACE WIND DECOUPLING TO PERMIT ABOUT A 3 HOUR PERIOD OF NEAR FREEZING TEMPS AND POSSIBLY SOME FROST CONSIDERING WET GROUND CONDITIONS KEEPING SURFACE DEWPOINTS ELEVATED FOR A WHILE. WILL COVER THIS WITH A FROST ADVISORY FOR TONIGHT FOR TRI CITIES, FLINT AND THUMB REGION. CLOUDS WILL DIMINISH BRIEFLY THEN RETURN NEAR THE OHIO BORDER OVERNIGHT AS THE SHORT WAVE RIDGE GIVES WAY TO THE NEXT IMPULSE IN THE UPPER JET TRACKING FROM THE PLAINS TO THE OHIO VALLEY. THIS SAME WEAK UPPER WAVE IS REGENERATING SOME MOISTURE IN THE 12Z MODELS, ESPECIALLY THE ETA, TOWARD SUNRISE. EXPECT DEEPER NE FLOW AND THE DRY BOUNDARY LAYER TO PREVENT ANY RAIN FROM MAKING IT TO THE SURFACE. THE 12Z MODELS SHOW THAT CLOUDS WILL LINGER AROUND THE SOUTH HALF OF OUR AREA INTO SATURDAY AFTERNOON AND THEN GIVE WAY COMPLETELY AS HIGH PRESSURE BUILDS INTO THE AREA. HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH SUNDAY AND THEN MOVE EAST AS THE NEXT SYSTEM APPROACHES FROM THE PLAINS. EXPECT WARM ADVECTION PRECIP TO MOVE INTO THE AREA LATER SUNDAY NIGHT BUT AMOUNTS WILL BE LIGHT AS DRY AIR CONTINUES TO CUT IN FROM THE EAST. CONSIDERING THE SLOWER TIMING EXPECTED WITH THE HIGH AMPLITUDE UPPER FLOW, AND THE DRY AIR IN THE LOW LEVELS, THE ETA LOOKS OVERDONE ON ITS QPF BY 12Z MONDAY. CHANCE POPS LOOK GOOD FOR SUNDAY NIGHT. THE GFS HAS BEEN LEADING THE WAY ON THIS SYSTEM WITH A FAIRLY CONSISTENT SOLUTION WITH THE OTHER MEDIUM RANGE MODELS TRENDING TOWARD IT. OVERALL, THERE IS STILL GOOD MODEL AGREEMENT AND STABILITY IF ONLY JUST A SLIGHTLY SLOWER AND FARTHER NW TRACK TO THE UPPER LOW THAT WILL CUT UNDER THE RIDGE OVER CENTRAL CANADA. THIS LENDS SOME CONFIDENCE FOR HIGHER POPS DURING THE MONDAY TUESDAY PERIOD. DRY AIR MAY CUT INTO THE WARM ADVECTION PRECIP SUNDAY NIGHT BUT THE NEXT SURGE WILL DO THE JOB MONDAY NIGHT FOLLOWED BY THE COLD FRONT ON TUESDAY. PLAN TO GO WITH SHOWERS AND THUNDERSTORMS LIKELY DURING THIS PERIOD. JUDGING BY THE DEPTH OF SURFACE LOW AND THE FAST FLOW ALOFT, THERE COULD EVEN BE A ROUND OF SEVERE WEATHER. A NUMBER OF CHOICES REMAIN IN THE SOLUTIONS FOR TIMING THE EXIT OF THIS SYSTEM ON WEDNESDAY, ALL OF WHICH ARE STILL DRY FOR SE MICHIGAN. SOLUTIONS RANGE FROM A CONTINUED PROGRESSIVE UPPER TROF IN THE EURO MODELS TO A SLOWER BUT FARTHER NORTH BLOCKING PATTERN OVER CENTRAL CANADA IN THE GFS. THE NCEP ENSEMBLE MEAN SUPPORTS A SOLUTION MORE LIKE THE UKMET WITH AN UPPER RIDGE SETTING UP TO OUR WEST BUT MAYBE NOT AS AMPLIFIED. FOR NOW, IT STILL SEEMS SAFE TO KEEP WEDNESDAY AND THURSDAY DRY AND BRING IN ANOTHER CHANCE OF SHOWERS ON FRIDAY. THE GFS SHOWS THE NEXT SYSTEM MOVING IN ON THURSDAY BUT THIS IS A VERY LOW CONFIDENCE FEATURE. IT LOOKS TOO FAST OR TOO FAR EAST CONSIDERING THE TROF DEVELOPING ALONG THE WEST COAST IN THE ENSEMBLE. OUR FORECAST WILL FOLLOW A SOLUTION MORE LIKE THE UKMET AND THAT REFERRED TO BY NCEP'S EPD. THIS ALSO MEANS MILD TEMPS THROUGH MID WEEK THEN COOLER THAN GFS GUIDANCE NUMBERS FOR WEDNESDAY THROUGH FRIDAY AS HIGH PRESSURE WILL BE MORE IN CONTROL. THE GOOD NEWS IS THAT COOLING WILL BE MODEST WITH NO BIG SURGES OF COLD AIR FROM CANADA. .DTX...FROST ADVISORY...TONIGHT...MIZ047>049-053-054-060-061. $$ EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) BT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1157 AM EDT FRI MAY 2 2003 HIGH PRESSURE BUILDING OVER UPPER MICHIGAN BRINGING ANOTHER SUNNY AND VERY DRY DAY (W/ RHS BOTTOMING IN TEENS). CURRENT FORECAST IS ON TRACK. WILL ADJUST TEMPS DOWN SLIGHTLY INLAND THOUGH FROM NEAR 60F TO MID 50S...BASED ON MESOETA/RUC SOUNDINGS...SHOWING 925MB TEMPS FROM 3-6C AND MIXING TO NEAR 880MB. CURRENT TRENDS WOULD SUPPORT THIS. SOLID NE FLOW (950MB WINDS 10-15KT TIL LATE IN DAY) WILL OFFSET ANY SIGNIFICANT LAKE MICHIGAN BREEZE...THOUGH TEMPS WILL BE COOLER ALONG THE IMMEDIATE BAY AS WINDS HAVE ELY COMPONENT. MINOR UPDATE COMING SHORTLY. .MQT...NONE. JKL mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1050 AM CDT FRI MAY 2 2003 UPDATED SHORT TERM GRIDS TO REFLCT CURRENT TRENDS...BUMPED UP TEMPS A BIT...AND DECREASED CLOUDS A BIT 'CEPT FOR THE FAR SOUTH. MORNING 12Z RAOBS FROM AROUND THE AREA CONT TO SHOW VRY DRY AIRMASS IN PLACE. SFC DEWPTS REFLECTING THIS AS MOST READINGS IN TEENS/20S AND EVEN A FEW SUSPECT SINGLE DIGITS. LOW LVL RIDGE AXIS FM SFC TO H85 KEEPING CLOUDS AWAY AND WIND FIELDS LIGHT. STEEP LL LAPSE RATES IN DRY AIR SUGGEST MIXING ALL THE WAY TO H7 TDY...SO A FEW GUSTS AS CONVECTIVE OVERTURNING STRENGTHENS WITH DIURNAL TEMP RISE. SHEARING H7 WAVE OVR WI...AND UPR DISTURBANCE IN SD ALONG SHEAR ZONE WITH 60 KT H3 JET WL ROTATE THRU SRN MN TODAY...KEEPING MID LVL AC FOCUS UNDER RUC PROGGED H5-H3 CONV-Q WHICH SCOOTS ALONG IA/MN BORDER. ISC GRIDS OF EXTENDED VARIETY ARE OUT...AS WELL AS ALL SHORT TERM GRIDS. .MSP...NONE. $$ BINAU mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 1030 AM EDT FRI MAY 2 2003 KBUF RADAR AT 14Z SHOWING BACK EDGE OF RAIN SHIELD GENERALLY FROM ROCHESTER TO WELLSVILLE. EXTRAPOLATION OF BACK EDGE WOULD END PRECIPITATION OVER THE ENTIRE AREA BY 16Z. VISIBLE IMAGE SHOWING LEADING EDGE OF CLEARING LINE ACROSS SOUTHERN ONTARIO. RUC SEEMS TO HAVE GOOD HANDLE ON CLEARING TREND. LEADING EDGE WILL WORK TO NEAR A WATERTOWN TO BUFFALO LINE AROUND 21Z. WILL LEAVE MOSTLY CLOUDY SKIES ALONG AND SOUTH OF THE LINE WITH PARTIAL CLEARING ALONG AND NORTH. LOW LEVEL COLD AIR ADVECTION SHOULD KEEP AFTERNOON TEMPERATURES FROM RISING MUCH...ESPECIALLY UNDER CLOUD COVER. INCREASING SUNSHINE FOR NORTHERN SECTIONS COULD GET TEMPERATURES INTO THE LOWER HALF OF THE 50S. REMAINDER OF FORECAST UNCHANGED. .BUF...NONE. $$ TMA ny AREA FORECAST DISCUSSION. NATIONAL WEATHER SERVICE RALEIGH NC 952 AM EDT FRI MAY 2 2003 INSTABILITY WILL BE IMPRESSIVE IN THE WEST LATE TODAY PER COPIOUS SUN. RUC SPITS OUT AN OVERESTIMATED -10 LI AND A 2800 CAPE AT 21Z...EVEN SO...STILL IN GOOD TIMING WITH THE UPPER VORT MAX CROSSING THE MOUNTAINS. A FAIRLY STRONG CAP EXISTS AT 600 MB ON THE MORNING SOUNDING WHICH SHOULD LIMIT EARLY CONVECTION...BUT WILL INCREASE THE WESTERN POPS INTO THE CHANCE CATEGORY...THOUGH THE EVENING/EARLY TONIGHT PERIOD SHOULD BE MORE ACTIVE. ONLY COSMETIC CHANGES IN THE CENTRAL AND EAST. .RAH...NONE. MLM nc COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 330 PM CDT FRI MAY 2 2003 SHORT-TERM (TONIGHT THRU 12Z SUN)...WATER VAPOR IMAGERY SHOWS UPPER LEVEL SPEED MAX MOVING ACROSS BIG BEND REGION. THE RUC MODEL PICKS UP ON THIS MID-UPPER LEVEL SHORT WAVE TROUGH AND MOVES IT TO NORTH OF VICTORIA BY 06Z SATURDAY. ISOLATED CONVECTION HAS DEVELOPED ON THE HIGHER TERRAIN WEST OF DEL RIO WHERE INSOLATION HAS PROVIDED A VERY UNSTABLE AIRMASS ON THE WEST EDGE OF MOIST AXIS. THICK STRATOCUMULUS PERSISTING OVER THE RIO GRANDE PLAINS HAS PREVENTED FURTHER DESTABILIZATION OF AIRMASS OVER THIS REGION. STORMS OVER MEXICO SHOULD SOUTHEAST...WILL PUT SLIGHT CHANCE POPS FOR THE LAREDO/COTULLA AREAS FOR THIS EVENING. FARTHER NORTH...STORMS ARE FIRING NEAR THE INTERSECTION OF THE DRYLINE AND COLD FRONT NEAR SAN ANGELO. STORMS ARE EXPECTED TO FORM INTO A MESOSCALE CONVECTIVE SYSTEM TONIGHT MOVING EAST-SOUTHEAST. THIS ACTIVITY WILL BE CLOSE ENOUGH TO THE NORTHEAST PART OF THE FORECAST AREA TO WARRANT MENTIONING POPS LATER TONIGHT. MODELS ARE CONSISTENT FORECASTING DRIER AIR AT 85H MOVING INTO THE COASTAL PLAINS TONIGHT...SO WILL NOT MENTION LIGHT PRECIP AFTER MIDNIGHT. SURFACE PRESSURES WILL BE FALLING OVER THE PLAINS AS SHORT WAVE TROUGH MOVES INTO THE SOUTHERN ROCKIES. BREEZY CONDITIONS EXPECTED OVER THE AREA SATURDAY. WITH LOW LEVEL MOISTURE HANGING IN OVER THE AREA...KEPT MAX TEMPS SATURDAY DOWN FROM PREVIOUS FORECAST. WILL MAINTAIN DRY FORECAST FOR SATURDAY AS FLAT UPPER RIDGE MOVES OVER THE AREA. THE WINDS HAVE FAILED TO RESPOND OVER THE WATERS...WILL TAPER THE WINDS BACK IN THE MARINE FOR TONIGHT. THE WINDS SHOULD FINALLY PICK UP SATURDAY AFTERNOON. LONG-TERM (SUN THRU FRI)...LARGE SFC LOW PRESSURE OVER THE CEN PLAINS WILL LIFT NE TOWARDS THE GREAT LAKES TROUGH THE EARLY PART OF NEXT WEEK...W/ THE ASSOC SFC TROF MVG INTO THE WRN CWA ON MONDAY. THIS WILL PRODUCE BREEZY/WINDY CONDITIONS SUN AND MON...EXCEPT FOR IN AREAS NEAR THE TROF ON MON (WRN ZONES). SW FLOW AT H85 WILL PRODUCE WARM TEMPS AND A LARGE CAPPING INVERSION...KEEPING PROSPECTS FOR CONVECTION LOW AND WILL NOT MENTION POPS THROUGH TUE. GFS HAS NOT RETAINED ANY RUN TO RUN CONSISTENCY FOR THE PERIODS IN THE MIDDLE OF THE WEEK. LATEST PROGS SHOW A DEEP UPR TROF MVG ACROSS NRN TX ON WED...W/ SFC LOW PRESSURE DEEPENING ACROSS THE TX PANHANDLE. PROSPECTS FOR POPS WED REMAIN LOW AS THE DYNAMICS REMAIN WELL TO THE NORTH OF THE REGION AND H85 FLOW BECOMES SSW. IF THIS VERIFIES WILL SRLY WINDS CRANK UP ON WED AS A 40-50KT LLJ SETS UP ACROSS THE COASTAL BEND. AS THE LOW LIFTS NE...GFS SHOWS A TRAILING SFC FRONT MVG TO THE COAST ON THU...POSSIBLY PRODUCING SLIGHTLY HIGHER RAIN PROSPECTS. THE CURRENT FORECAST SHOWS JUST SLIGHT CHC POPS EACH DAY AND GIVEN THE SERIOUS LACK OF RUN TO RUN CONSISTENCIES IN THE MED RANGE MODELS...I AM NOT INCLINED TO MAKE MANY CHANGES TO THE CURRENT EXT PERIODS. PRELIMS... CRP BB 073/088 075/088 076 1-0 VCT BE 072/089 073/089 073 100 LRD BB 076/098 077/099 076 -00 .CRP...NONE. 89/TMT...SHORT TERM 88/MJG...LONG TERM tx SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO 310 AM MDT SAT MAY 3 2003 SHORT TERM DISCUSSION...(TODAY AND TONIGHT). ...WINDY AND DRY CONDITIONS LATER THIS AFTERNOON AND TONIGHT... CURRENTLY: LATEST WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED NEXT ULJ MOVING OUT OF THE DESERT SW INTO SWRN CO. BKN-OVC CS CLOUD SHIELD IS ASSOCIATED WITH THIS ULJ. THIS HAS HELD SFC TEMPS UP DURING THE NGT. ALSO...WINDS AROUND MTN TOP LEVEL HAVE INCREASED TO 20-25KTS WITH GUSTS AROUND 30KTS. SELY WINDS ACROSS SERN CO PLAINS ARE IN RESPONSE TO NOCTURNAL LLJ AROUND CO/KS BORDER. KALS HAS BEEN AROUND 10-12KTS ALL NIGHT WHICH IS ATYPICAL FOR THIS TIME OF DAY. BIG HORN RAWS(SW SIDE OF SAN LUIS VALLEY@ 8K FT MSL) IS ALREADY SW@19 MPH GUSTS TO 30 MPH. LOW LEVEL MOISTURE... 30S/40S DEW POINTS...IS ONCE AGAIN BANKED UP AGAINST THE ERN SLOPES OF THE SERN CO MTNS. "LEADING EDGE" OF THE MOISTURE IS SOMEWHERE AROUND 8K-9K FT MSL...BUT IS STARTING TO ERODE AT HIGHER ELEVATIONS. WILLIS CREEK RAWS(9396 FT MSL) HAS DEW POINTS ALREADY AROUND 10F WITH CUCHARA(8313 FT MSL) AROUND 25F. ACROSS THE ERN SAN JUANS AND COLLEGIATE PEAKS DEW POINTS RANGED FROM 4F-19F. TDA: CURRENT FCST APPEARS TO BE ON TRACK. 100-130KT ULJ SHOULD CONTINUE TO SPREAD INTO SRN CO TDA. LOW/MID LEVEL WINDS SHOULD RESPOND DURING THE DAY. STILL LOOKS LIKE 15-30 MPH SUSTAINED WINDS WITH GUST POTENTIAL OF 35-45 MPH THIS AFTN/EVE WITH DEEP BOUNDARY LAYER MIXING. THE BIGGEST CHALLENGE IS THE DEW POINTS AND DRYLINE FORECAST IN SERN CO. SHOULD SEE THE DRYLINE SLOWLY MIGRATE TOWARDS THE CO/KS BORDER LATE THIS AM/EARLY AFTN. BY THE TIME THE DRYLINE MAKES IT TO THE CO/KS BORDER...THE LOW LEVEL CAP(LID) SHOULD BE WEAK. LOW LEVEL CONVERGENCE ZONE APPEARS TO BE FAIRLY WEAK AND MAY NOT BE ENOUGH TO OVERCOME WEAK LOW LEVEL CAP(LID). THIS TOUGH SCENARIO WILL LIKELY BE JUST TO OUR E...SO WILL LEAVE POPS OUT OF THE FCST FOR NOW. WITH THE POTENTIAL FOR DEEP BOUNDARY LAYER MIXING TDA...CURRENT FCST OF LOWER 80S AOB 5K FT MSL STILL LOOKS ON TARGET. THE ONLY CLOUD COVER SHOULD BE BKN-OVC CS AND DEPENDING ON THE OPAQUENESS IT COULD EITHER BE PARTLY CLOUDY OR MOSTLY CLOUDY. TNGT: 100-130KT ULJ WILL CONTINUE OVER SRN CO WITH SFC CYCLOGENESIS OCCURRING IN NERN CO/NWRN KS LATER THIS EVE AND OVERNIGHT. LOW/MID LEVEL TROP WLY WINDS ACTUALLY INCREASE DURING THE NGT WHICH COULD KEEP THE AIR MASS TURBULENTLY MIXED. MESO-ETA CONTINUES TO KEEP RELATIVELY LOW DEW POINTS(SINGLE DIGITS) ACROSS THE AREA...BUT DIDN'T GO AS LOW. SFC TEMPS MAY ALSO BE SLOW TO COOL DURING THE NGT. HAVE TWEAKED THE POPS TO ONLY AROUND THE CONTDVD AND 20% FOR TNGT. FIRE WEATHER CONCERNS: WITH THE POTENTIAL OF S-SW WINDS 15-30 MPH AND GUSTS OF 35 MPH(LOWER ELEV.) TO 45 MPH(HIGHER ELEV)...AFTN MIN RH VALUES OF 8-15% CWA-WIDE(EXCEPT AT THE VERY HIGHER TERRAIN LOCATIONS)...HAINES 5-6...EXTREME DROUGHT...AND PUEBLO DISPATCH STILL CONCERNED ABOUT THE RELATIVE DRYNESS OF FUELS BELOW 9K FT MSL...WILL GO AHEAD AND UPGRADE THE FIRE WEATHER WATCH TO A RED FLAG WARNING. I WILL EXPAND IT TO INCLUDE 220 AND 223(THIS MAKES IT FOR ALL FIRE WEATHER ZONES)...AS IT APPEARS THE MID LEVEL MOISTURE WILL HOLD OFF UNTIL LATER TONIGHT AND AFTN RH VALUES(BLO 9K FT MSL) SHOULD BE AROUND 10%. ALSO...THIS WILL BLEND IN WITH GJT'S FIRE WEATHER HEADLINE ISSUED YDA EVENING. -- METZE LONG TERM DISCUSSION...(SUNDAY THROUGH FRIDAY). SUNDAY...TROF PASSES OVER CWA 12-18Z...WITH WINDS SHIFTING FROM SOUTHWEST TO WEST NORTHWEST. SUBSIDENCE SETS IN BEHIND...AND WITH 500 MB WINDS 40-50KTS WOULDN'T BE SURPRISED TO GET 40KT GUSTS OVER HIGHER TERRAIN...30KTS LOWER ELEVATIONS. INCREASED SFC SUSTAINED WINDS A BIT. JET SCOOTS SOUTH BY 18Z...HOWEVER NEXT STREAK MOVES IN THROUGH NORTHWEST FLOW...SO ANTICIPATE WINDS TO STAY UP SUNDAY NIGHT AS WELL. ADDED GENERALLY 1-3 INCH SNOW GRID FOR OVERNIGHT SNOW SHOWERS WEST AND CNTRL MTNS. SURFACE GRADIENT STICKS AROUND AS SURFACE HIGH BUILDS WEST WHILE LOW PRESSURE BUILDS IN THE PLAINS. MONDAY KEPT CNTRL AND WESTERN MTN POPS...BUT WITH ENERGY SHIFTING NORTH AND EAST THINK ISOLATED COVERAGE IS BEST. BRIEF REPRIEVE MONDAY AS WESTERLY FLOW MAY RECOVER TEMPS BRIEFLY IN THE AFTERNOON...BUT NEXT SFC HI AND MID LEVEL CAA RETURN LATE IN THE DAY. TUESDAY...NEXT TROF APPROACHES WESTERN BORDER BY MIDNIGHT...AND FLOW SHIFTS NORTHEAST ON THE PLAINS. LOW LEVEL JET LOOKS TO ADVECT MOISTURE INTO EAST PLAINS AS TROF ENTERS THE STATE 12Z TUESDAY. WOULD ANTICIPATE A COOL...CLOUDY DAY. BY NOON...AVN HAS LARGE AREA OF LIGHT TO MODERATE PRECIP OVER MOST EAST PLAINS AND EAST MTNS... CONSIDERING UPSLOPE...INCOMING LIFT FROM WEST TROF...THETA E ADVECTION. AVN IS FASTER AND STRONGER WITH THIS WAVE...ETA THROUGH 84 HRS HINTING AT A SLOWER WEAKER SOLUTION...SO WILL LEAVE AS ISOLATED COVERAGE ACROSS ALL CWA AS THINK TROF WILL PASS BUT TIMING AND EXTENT OF PRECIP YET TO BE DETERMINED. WEDNESDAY THROUGH FRIDAY...GFS SETS UP EARLY AM MCS OVER NE CO/NW KS...AND IS USHERED EASTWARD WITH S/W TROF. INCOMING JET BEHIND COULD ACT TO SCOUR OUT SOME OF THIS MOISTURE...TIME WILL TELL. A BIT OF TEMP RECOVERY MAY BEGIN THIS DAY. NEXT LONGER WAVE TROF STILL PRESENTING SOME LIFT OVER THE AREA WEDNESDAY SO WILL LEAVE CURRENT POPS AS IS. THURSDAY AND FRIDAY LOOK TO BE A WARMING DRYING TREND AS SOUTHWEST FLOW ALOFT SETS UP OVER THE AREA. NO CHANGES. .PUB...RED FLAG WARNING 12PM TO 12AM FOR ALL S CNTRL/SERN ZONES... BELOW 9500 FEET...FIRE WX ZONES 220>237. co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 359 AM EDT SAT MAY 3 2003 LARGE STRIPE OF LOW CLOUDS SPREADING SLOWLY INTO NRN PARTS OF THE LMK FA ATTM WITHIN LIGHT FLOW REGIME ASSOCIATED WITH INCOMING SURFACE HIGH. LOW CIGS/VISIB RESTRICTIONS A GOOD BET EARLY THIS MORNING, AS LOWEST FEW HUNDRED METERS AGL REMAINS MOIST PER 0Z ETA AND OBSERVED KSDF ACARS RAOBS, MODULATED TO MORE OF A LOW CIG REGIME ALONG/N OF I-64 BY ZONE OF NELY 15-20KT WINDS ~1KFT AGL PER 3Z RUC. CLOUD BEARING LAYER FLOW ALMOST NIL THRU TODAY, AND WITH LOW-LEVEL THERMAL TROF PASSING OVERHEAD, THINK CLOUDS WILL PERSIST FOR A WHILE. THEN INTO THE MID/LATE AFTERNOON, AMPLIFYING 500MB WAVE NOW OVER IA TRANSLATES EWD INTO UPPER OH RIVER VALLEY WITH A BAND OF FAIRLY IMPRESSIVE 700MB SUBSIDENCE SPREADING INTO LMK FA. THIS SHOULD PROMPT AN ERADICATION OF THE CLOUD COVER BY EARLY EVENING. RAW ETA AND ETA-MOS SPIT OUT SOME VERY LIGHT QPF FROM SDF-LEX THIS AFTERNOON IN ZONE OF WEAK PBL LIFT AHEAD OF THAT WAVE. WITH ELY LOW LEVEL FLOW, MOIST NEAR SURFACE LAYER LOOKS FAIRLY SHALLOW BY 12Z/SUN ACROSS MOST OF THE FA, PER ETA FCST RAOBS. THINK ANY BR/FG SHOULD BE RESTRICTED TO FAVORED LOCATIONS IN SRN KY. STG JET STREAK EJECTS OUT OF THE SRN ROCKIES ON SUN, WITH ASSOC CYCLOGENESIS TAKING PLACE OVER CEN PLAINS, MAKING THINGS INTERESTING OVER THE FA. EVERYTHING COMING TOGETHER FOR A GOOD PCPN EVENT SUN NIGHT, AS INGREDIENTS COALESCE OVER FA WITH THE PASSAGE OF SFC WARM FRONT. HIGH FREEZING LEVELS, STG LOW LEVEL JET IMPORTING A BUBBLE OF ELEVATED CAPE, PWS NEARING 250% OF NORMAL, AND SWATH OF UPPER LEVEL DIVERGENCE ALL COME TOGETHER. NWP TRENDS HAVE BEEN FOR SLIGHTLY FURTHER NORTH 500MB WAVE TRACK, AND THUS PER 21Z/02 ETA-ENSEMBLES THREAT FOR HEAVIEST RAINS AT THIS POINT IS OVER THE NRN 1/2 OF LMK FA WHERE 1-2" TOTALS WOULD OCCUR SHOULD THIS SCENARIO MATERIALIZE. VERY STRONG SFC-1KM WIND FIELD ASSOCIATED WITH SFC WARM FRONTAL PASSAGE LATE SUN NIGHT ARGUES FOR A CHANCE OF SEVERE CONVECTION. WITHIN "WARM SECTOR" AIRMASS MONDAY, SCT TSRA AGAIN POSSIBLE. GFS SUGGESTS CAPPING ~750MB WHICH MAY INHIBIT THINGS FOR A WHILE MON, BUT AS 500MB JET STREAK ROUNDS TROF, THINK CONVECTION WILL REDEVELOP OVER UNSTABLE FA WITH SVR TS CERTAINLY POSSIBLE BASED ON 0-6KM SHEAR. RELYING ON GFS, TUE LOOKS FOR THE MOST PART DRY AS AREA OF SUBSIDENCE OVERSPREADS THE FA BEHIND DEPARTING 500MB WAVE. ACTIVE WEATHER QUICKLY RETURNS WED-THU, AS ANOTHER WAVE IN MID-LEVEL FLOW EJECTS OUT OF SRN ROCKIES THIS TIME TAKING A MORE SLY TRACK. FRONTAL BOUNDARY IN VICINITY OF FA DURING THIS PERIOD, SO LOW CHC TSRA LOOKS FINE FOR NOW GIVEN UNCERTAINTIES THIS FAR OUT. .LMK...NONE. XXV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 446 AM CDT SAT MAY 3 2003 FAST MOVING...HIGH AMPLITUDE SYSTEMS CONTINUE TO AFFECT MUCH OF THE COUNTRY. THUS...UNCERTAINTY IS HIGHER THAN NORMAL...AND THIS FORECASTER WILL ATTEST TO THAT! THE STATIONARY FRONT HAS BEEN BEHIND THE MODELS' SCHEDULE FOR LIFTING OUT TO THE NORTH. THAT TREND WILL CONTINUE...AND SOME VESTIGE OF THE WARM FRONT MAY WELL BE ACROSS NORTHERN SECTIONS OF NORTH TEXAS THIS AFTERNOON. THE NEW RUC AND SEVERAL OTHER MODELS SUGGEST THAT THIS IS THE MOST LIKELY SOLUTION. THE RUC SUGGESTS THAT A RATHER WEAK SHORT WAVE TROUGH WILL HELP TO ELIMINATE THE CAP AND RESULT IN THUNDERSTORMS ACROSS THE NORTHERN ZONES (NEAR THE FRONT) THIS AFTERNOON. WE WILL SEE IF THAT ACTUALLY HAPPENS. WE HAVE FASHIONED SLIGHT CHANCE AND CHANCE POPS IN MOST AREAS...BUT I CURRENTLY THINK THAT THE WARM FRONT OFFERS THE BEST BOUNDARY FOR THUNDER TO FORM...THUS WE HAVE KEPT CHANCE POPS IN THAT AREA. BECAUSE OF THE LACK OF A PRONOUNCED SHORT WAVE TROUGH NEAR THE DRY LINE...WE THINK THAT CONVECTION WILL BE IN THE SLIGHT CHANCE (20 PERCENT) CATEGORY IN MOST AREAS. NEVERTHELESS...WHERE CONVECTION DOES FIRE OFF...SHEAR/INSTABILITY SUGGEST A GOOD CHANCE OF MULTICELL OR SUPERCELL SEVERE STORMS. THE DRY LINE WILL STILL NOT CLEAR THE AREA SUNDAY...THUS ANOTHER ROUND OF SCATTERED THUNDERSTORMS SEEMS IN ORDER. ASSUMING THAT THE MRF HAS A FAIR AMOUNT OF ACCURACY TO IT (SEE THE FIRST PARAGRAPH ABOVE!) THERE MAY BE BETTER CHANCES FOR THUNDERSTORMS LATER IN THE WEEK...WHEN ANOTHER STATIONARY FRONT SETS UP ACROSS NORTH TEXAS. WE HAVE RAISED POPS AND DEW POINTS BECAUSE OF THIS PATTERN...WHICH OFFERS MORE EASTERLY FLOW THAN WESTERLY WINDS...AS WAS THE CASE YESTERDAY. THIS SHOULD KEEP MORE MOISTURE IN THE AREA. WE HAVE FOLLOWED SPC'S CUE IN PUTTING "A FEW SEVERE" IN THE FORECAST FOR BOTH TODAY AND SUNDAY. FCSTID = 26 DFW 87 70 88 66 / 30 30 20 0 ACT 89 72 89 66 / 20 20 20 10 PRX 85 68 85 64 / 30 20 30 20 DTO 86 69 88 63 / 30 20 20 0 TKI 86 69 87 64 / 30 20 20 0 DAL 88 70 88 66 / 30 20 20 0 TRL 87 70 87 65 / 20 20 30 20 CRS 88 71 87 66 / 20 20 20 10 TPL 90 70 91 66 / 20 20 10 10 .FWD... TX...NONE. $$ tx EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 940 AM EDT SAT MAY 3 2003 QUESTION FOR TODAY IS COVERAGE AND INTENSITY OF CONVECTION. NOTE SPC SLIGHT RISK RIGHT OF A LINE FROM MLB TO PIE. BOTH MESO ETA AND RUC INDICATED SEA BREEZE DEVELOPMENT FROM ALONG THE COAST AT DAYTONA BEACH PUSING INLAND TO AROUND LAKE OKEECHOBEE IN THE SOUTH BY 18 TO 21 UTC. STRONGER WEST TO NORTHWEST STEERING FLOW SHOULD KEEP THE SEA BREEZE CLOSE TO THE COAST FROM CAPE CANAVERAL NORTHWARD. REMNANT OF OVERNIGHT OUTFLOW BOUNDARY IS MOST EVIDENT IN THE SURFACE DEWPOINT FIELD OVER CENTRAL FLORIDA WHERE A AXIS OF 68 PLUS DEWPOINTS EXTENDS FROM AROUND CAPE CANAVERAL TO NORTH OF TAMPA. THIS BOUNDARY KEPT FAIRLY STRONG NORTH WINDS AT BUOY 009 UNTIL 7AM WHEN THEY STARTED TO WEAKEN SIGNIFICANTLY AND RECOVER TO A MORE EASTERLY DIRECTION. BEST LIFTED INDICES SHOULD BE IN THE -8 TO -10 RANGE OVER THE SEA BREEZE BY 21Z WITH WEST TO NORTHWEST FLOW AT STEERING LEVELS AND 25O MB WINDS OF AROUND 50 KTS. PRECIP WATER MAY BE SOMEWHAT LIMITED DUE TO DRY AIR IN MIDLEVELS BUT THIS WILL BE FAVORABLE FOR ISOLATED SEVERE STORMS ESPECIALLY OVER VOLUSIA AND NORTHERN BREVARD COUNTIES LATE THIS AFTERNOON. .MLB...NONE. PUBLIC/MARINE...HAGEMEYER AVIATION/FIRE...CRISTALDI $$ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 935 AM CDT SAT MAY 3 2003 FRESHENED GRIDS AND WORDS A BIT TO REFLECT LATEST TRENDS. GOING FCST IS IN FINE SHAPE AND LITTLE CHANGES MADE TO THE SENSIBLE WX OVR CWA TODAY AND THIS EVE. 12Z RUC AND 06Z META SHOWING NICE LEAD H7 S/W EJECTING OUT AHEAD OF MAIN UPR SYSTEM THIS AFTN INTO CNTL SD. LLJ AT H85 INCREASING IN RESPONSE...ADVECTING ELEVATED MOISTURE/THETA-E FROM CNTL PLAINS INTO ERN SD/WRN MN THIS AFTN. RESPONSE TO THIS ALREADY BEING IN SEEN IN SRN SD AS BAND OF ELEVATED -SHRA/-TSRA LIFTING NE TWRD WRN MN...DUE IN LATE AFTN. WHILE SHOWALTERS/ELEVATED INSTABILITY IS MARGINAL...DID KEEP THUNDER THREAT IN WCNTL BASED ON CURRENT LIGHTNING STRIKES AND STEEPISH LAPSE RATES APPROACHING 7 C/KM. BUMPED TEMPS UP A TAD BASED ON FCST SOUNDINGS/12Z RAOBS...BUT JUST A FEW DEGREES. MAINLY CNTL CWA WHERE MIXING WINDS/SUNSHINE MAXIMIZED. 06Z META HAS SFC LOW DOWN TO 984MB NOW SUN EVE...MORE ON THIS IN AFTN DISC. .MSP...NONE. BINAU mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1049 AM EDT SAT MAY 3 2003 COLD FRONT STALLED N OF AREA. VIS SATELITE IMAGERY AND 300 MB ANALYSIS SHOW UPPER LEVEL JET MOVING INTO AREA. MODEL CAPES RATEHR HIGH AT MID DAY OVER UPSTATE SC...THEN RAPIDLY SHIFT S AND E AS THEY DIMINSH. WET BULB ZERO 8500 - 9500 FT. WORKING AGAINST SEVERE WEATHER IS CIRRUS COVER...AND MORE IMPORTANTLY A WEAK MID LEVEL CAP IN AREA SOUNDINGS. COOLER MID LEVEL TEMPERATURES APPROACHING FROM UPSTREAM. WHETHER THEY GET HERE IN TIME IS QUESTIONABLE. AT THIS TIME WILL MOVE FOCUS FOR BEST CHANCE OF CONVECTION FROM NC INTO SC/GA PIEDMONT...THOUGH CHANCE POPS EVERYWHERE. TEMPERATURES RUNNING A DEGREE OR TWO BELOW 06Z MAV GUIDANCE...WHICH IS ABOUT THREE DEGREES BELWO FORECAST. LOWERED MAXIMUM TEMPERATURES TWO DEGREES. MODEL DEW POINT AGRESSIVELY MOISTEN AREA TODAY...AND HAVE REDUCED THIS TREND GREATLY. RUC WINDS BRING FLOW AROUND TO NE ALONG I-40 LATE AS FRONT SETTLES S. FCSTID = 7 GSP 77 54 73 53 / 50 50 10 20 AND 78 54 74 54 / 50 50 10 20 CLT 77 52 73 52 / 40 50 10 20 HKY 73 49 71 51 / 30 50 10 20 AVL 72 47 69 49 / 50 50 10 20 .GSP... GA...NONE. NC...NONE. SC...NONE. $$ O7 sc AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE FORT WORTH TX 1115 AM CDT SAT MAY 3 2003 LATE MORNING PUBLIC DISCUSSION UPDATE... NO MAJOR WHOLESALE CHANGES EXPECTED...EXCEPT SOME TWEAKS ON POPS... CLOUDS AND WINDS. LOOKING AT SOUNDING DATA AROUND THE REGION...LOW CLOUD SOUTH OF WARM FRONT NOW BETWEEN WACO AND D/FW...LOOK TO BE ~2000 FT DEEP AND MAY NOT MIX FULLY OUT (SIMILAR TO YESTERDAY). THUS TEMPS AND WINDS WILL NEED TO BE DROPPED SOME AS DRYLINE REMAINS HELD ALONG TX/NM BORDER NEAR BETTER HEIGHT FALLS. AS FOR POPS...FEEL BEST CHANCES WILL BE ALONG/N OF THE WARM FRONT (I-20/NWD) WHERE BETTER LOW LVL FORCING/MSTR CONVERGENCE...ALONG WITH BETTER VERTICAL MOTIONS WILL BE REALIZED. MID LVL RIDGE AXIS BUILDING OVER RIO GRANDE VALLEY AS OF 16Z AND THIS MAY CAP S/SW ZONES ENOUGH...ALONG WITH FORCING MECHANISMS REMAINING FARTHER NORTH TO BREAK IT. WILL TREND FROM ZERO POPS FAR S/SW...TO SLIGHT CHANCE IMMEDIATELY ALONG/SOUTH OF EXPECTED WARM FRONT POSITION NEAR I-20...TO CHANCE THOUGHT FARTHER NORTH TO THE RED RIVER. PER LATEST SWODY1 (READ FOR DETAILS) AND DISCUSSION WITH SPC EARLIER THIS MORNING...MODERATE RISK JUST N/NE OF METROPLEX VERY REASONABLE. DAMAGING WIND/LARGE HAIL A GOOD BET. THOUGH LOW LVL WIND FIELDS ARE RELATIVELY WEAK...FEEL STORM-SCALE INTERACTIONS ALONG WITH SURFACES WINDS BACKING TO THE EAST NORTH OF THE WARM FRONT...AND DECENT DEW PTS NWD INTO OK...DO SUGGEST THAT A BRIEF TORNADO OR TWO CAN/T BE RULE OUT...AND HAVE ALREADY UPDATE HWO TO REFLECT THIS. *WILL DO AN 18Z SOUNDING AS WELL TO INVESTIGATE POTENTIAL.* UPDATES OUT BY NOON. FCSTID = 05/ AVIATION DISCUSSION 610 AM CDT... IFR STRATUS DECK...BKN004-008 AND VIS 4-6SM BR/HZ...ALONG A KJCT-KOCH LN AT 11Z...MOVING NORTH 15 KTS WILL ARRIVE IN KACT TRACON AROUND 1230Z AND LINGER UNTIL 15Z. KDFW TRACON WILL HAVE BRIEF MVFR VIS OF 4-6SM BR 12Z-15Z THIS MORNING. A WEAK FRONT ALONG A KABI-KSEP-KCRS-KSHV LN WILL BE THE FOCI FOR TSRA DEVELOPMENT ALONG AND NORTH OF THE FRONT THIS AFTERNOON. DEEPENING LOW PRESSURE TO THE NORTH WILL VEER MORNING EASTERLY WINDS AND INCREASE SOUTHERLY WINDS LATER THIS AFTERNOON. EXPECT 15G25KT OVERNIGHT...ESPECIALLY AFTER 06Z AS LLJ STRENGTHENS. THESE WINDS MAY RESULT IN ANOTHER STRATUS DECK ADVECTING INTO THE KACT AREA BY 12Z. 75 EARLY MORNING PUBLIC DISCUSSION 446 AM CDT... FAST MOVING...HIGH AMPLITUDE SYSTEMS CONTINUE TO AFFECT MUCH OF THE COUNTRY. THUS...UNCERTAINTY IS HIGHER THAN NORMAL...AND THIS FORECASTER WILL ATTEST TO THAT! THE STATIONARY FRONT HAS BEEN BEHIND THE MODELS' SCHEDULE FOR LIFTING OUT TO THE NORTH. THAT TREND WILL CONTINUE...AND SOME VESTIGE OF THE WARM FRONT MAY WELL BE ACROSS NORTHERN SECTIONS OF NORTH TEXAS THIS AFTERNOON. THE NEW RUC AND SEVERAL OTHER MODELS SUGGEST THAT THIS IS THE MOST LIKELY SOLUTION. THE RUC SUGGESTS THAT A RATHER WEAK SHORT WAVE TROUGH WILL HELP TO ELIMINATE THE CAP AND RESULT IN THUNDERSTORMS ACROSS THE NORTHERN ZONES (NEAR THE FRONT) THIS AFTERNOON. WE WILL SEE IF THAT ACTUALLY HAPPENS. WE HAVE FASHIONED SLIGHT CHANCE AND CHANCE POPS IN MOST AREAS...BUT I CURRENTLY THINK THAT THE WARM FRONT OFFERS THE BEST BOUNDARY FOR THUNDER TO FORM...THUS WE HAVE KEPT CHANCE POPS IN THAT AREA. BECAUSE OF THE LACK OF A PRONOUNCED SHORT WAVE TROUGH NEAR THE DRY LINE...WE THINK THAT CONVECTION WILL BE IN THE SLIGHT CHANCE (20 PERCENT) CATEGORY IN MOST AREAS. NEVERTHELESS...WHERE CONVECTION DOES FIRE OFF...SHEAR/INSTABILITY SUGGEST A GOOD CHANCE OF MULTICELL OR SUPERCELL SEVERE STORMS. THE DRY LINE WILL STILL NOT CLEAR THE AREA SUNDAY...THUS ANOTHER ROUND OF SCATTERED THUNDERSTORMS SEEMS IN ORDER. ASSUMING THAT THE MRF HAS A FAIR AMOUNT OF ACCURACY TO IT (SEE THE FIRST PARAGRAPH ABOVE!) THERE MAY BE BETTER CHANCES FOR THUNDERSTORMS LATER IN THE WEEK...WHEN ANOTHER STATIONARY FRONT SETS UP ACROSS NORTH TEXAS. WE HAVE RAISED POPS AND DEW POINTS BECAUSE OF THIS PATTERN...WHICH OFFERS MORE EASTERLY FLOW THAN WESTERLY WINDS...AS WAS THE CASE YESTERDAY. THIS SHOULD KEEP MORE MOISTURE IN THE AREA. WE HAVE FOLLOWED SPC'S CUE IN PUTTING "A FEW SEVERE" IN THE FORECAST FOR BOTH TODAY AND SUNDAY. FCSTID = 26 DFW 87 70 88 66 / 30 30 20 0 ACT 89 72 89 66 / 20 20 20 10 PRX 85 68 85 64 / 30 20 30 20 DTO 86 69 88 63 / 30 20 20 0 TKI 86 69 87 64 / 30 20 20 0 DAL 88 70 88 66 / 30 20 20 0 TRL 87 70 87 65 / 20 20 30 20 CRS 88 71 87 66 / 20 20 20 10 TPL 90 70 91 66 / 20 20 10 10 .FWD... TX...NONE. $$ tx AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE FORT WORTH TX 610 AM CDT SAT MAY 3 2003 AVIATION DISCUSSION... IFR STRATUS DECK...BKN004-008 AND VIS 4-6SM BR/HZ...ALONG A KJCT-KOCH LN AT 11Z...MOVING NORTH 15 KTS WILL ARRIVE IN KACT TRACON AROUND 1230Z AND LINGER UNTIL 15Z. KDFW TRACON WILL HAVE BRIEF MVFR VIS OF 4-6SM BR 12Z-15Z THIS MORNING. A WEAK FRONT ALONG A KABI-KSEP-KCRS-KSHV LN WILL BE THE FOCI FOR TSRA DEVELOPMENT ALONG AND NORTH OF THE FRONT THIS AFTERNOON. DEEPENING LOW PRESSURE TO THE NORTH WILL VEER MORNING EASTERLY WINDS AND INCREASE SOUTHERLY WINDS LATER THIS AFTERNOON. EXPECT 15G25KT OVERNIGHT...ESPECIALLY AFTER 06Z AS LLJ STRENGTHENS. THESE WINDS MAY RESULT IN ANOTHER STRATUS DECK ADVECTING INTO THE KACT AREA BY 12Z. 75 XXXXXXXXXXXXXX 446 AM CDT SAT MAY 3 2003 FAST MOVING...HIGH AMPLITUDE SYSTEMS CONTINUE TO AFFECT MUCH OF THE COUNTRY. THUS...UNCERTAINTY IS HIGHER THAN NORMAL...AND THIS FORECASTER WILL ATTEST TO THAT! THE STATIONARY FRONT HAS BEEN BEHIND THE MODELS' SCHEDULE FOR LIFTING OUT TO THE NORTH. THAT TREND WILL CONTINUE...AND SOME VESTIGE OF THE WARM FRONT MAY WELL BE ACROSS NORTHERN SECTIONS OF NORTH TEXAS THIS AFTERNOON. THE NEW RUC AND SEVERAL OTHER MODELS SUGGEST THAT THIS IS THE MOST LIKELY SOLUTION. THE RUC SUGGESTS THAT A RATHER WEAK SHORT WAVE TROUGH WILL HELP TO ELIMINATE THE CAP AND RESULT IN THUNDERSTORMS ACROSS THE NORTHERN ZONES (NEAR THE FRONT) THIS AFTERNOON. WE WILL SEE IF THAT ACTUALLY HAPPENS. WE HAVE FASHIONED SLIGHT CHANCE AND CHANCE POPS IN MOST AREAS...BUT I CURRENTLY THINK THAT THE WARM FRONT OFFERS THE BEST BOUNDARY FOR THUNDER TO FORM...THUS WE HAVE KEPT CHANCE POPS IN THAT AREA. BECAUSE OF THE LACK OF A PRONOUNCED SHORT WAVE TROUGH NEAR THE DRY LINE...WE THINK THAT CONVECTION WILL BE IN THE SLIGHT CHANCE (20 PERCENT) CATEGORY IN MOST AREAS. NEVERTHELESS...WHERE CONVECTION DOES FIRE OFF...SHEAR/INSTABILITY SUGGEST A GOOD CHANCE OF MULTICELL OR SUPERCELL SEVERE STORMS. THE DRY LINE WILL STILL NOT CLEAR THE AREA SUNDAY...THUS ANOTHER ROUND OF SCATTERED THUNDERSTORMS SEEMS IN ORDER. ASSUMING THAT THE MRF HAS A FAIR AMOUNT OF ACCURACY TO IT (SEE THE FIRST PARAGRAPH ABOVE!) THERE MAY BE BETTER CHANCES FOR THUNDERSTORMS LATER IN THE WEEK...WHEN ANOTHER STATIONARY FRONT SETS UP ACROSS NORTH TEXAS. WE HAVE RAISED POPS AND DEW POINTS BECAUSE OF THIS PATTERN...WHICH OFFERS MORE EASTERLY FLOW THAN WESTERLY WINDS...AS WAS THE CASE YESTERDAY. THIS SHOULD KEEP MORE MOISTURE IN THE AREA. WE HAVE FOLLOWED SPC'S CUE IN PUTTING "A FEW SEVERE" IN THE FORECAST FOR BOTH TODAY AND SUNDAY. FCSTID = 26 DFW 87 70 88 66 / 30 30 20 0 ACT 89 72 89 66 / 20 20 20 10 PRX 85 68 85 64 / 30 20 30 20 DTO 86 69 88 63 / 30 20 20 0 TKI 86 69 87 64 / 30 20 20 0 DAL 88 70 88 66 / 30 20 20 0 TRL 87 70 87 65 / 20 20 30 20 CRS 88 71 87 66 / 20 20 20 10 TPL 90 70 91 66 / 20 20 10 10 .FWD... TX...NONE. $$ tx NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 230 PM MDT SAT MAY 03 2003 SHORT TERM DISCUSSION...ATTENTION STILL FOCUSED ON FAR NORTHEAST COUNTIES ALONG TIGHT BNDRY LYR MOISTURE AND TEMPERATURE GRADIENT. ON THE WEST SIDE OF THIS TIGHT GRADIENT IN WESTERN HIGH PLAINS CTYS WHERE ERLY AFTN DEW POINTS IN THE UPR 20S AND 30S...WHILE EAST OF THIS DISCONTINUITY ZONE READINGS IN THE 50S. UNFORTUNATELY WIDESPREAD CLOUD COVER UNTIL RECENTLY HAS KEPT SFC TEMPS DOWN AND BNDRY LYR CIN VALUES HIGH. WILL NEED TO CLIMB TO AT LEAST THE MID 60S BEFORE STG CAP BREAKS OUT NEAR THE NERN CORNER. THEREFORE BELIEVE ITS JUST ALONG THE PSUEDO DRY-LINE STRETCHING ACROSS LOGAN AND WASHINGTON CTYS WHERE T-STORMS ARE LIKELY TO POP FIRST. CAPES PROGD BY RUC TO BE IN THE 600-900 J/KG RANGE IN THIS AREA BY 21Z. WHEREAS ETA A BIT FARTHER EAST WITH THESE VALUES. APRS STG TURNING THRU DEEP LAYER SHOULD FURTHER AID IN THE FORMATION OF SINGLE CELL STORMS ALONG AND JUST WEST OF THIS ZONE WHERE STEEP LAPSE RATES EXIST THRU AT LEAST MID-EVENING. NEXT...SHORTWAVE LIFTING NEWRD OUT OF THE FOUR CORNERS AREA PASSES OVER THE CWFA BTWN 06Z-15Z/SUN. DO NOT SEE MUCH IN THE WAY OF PCPN EAST OF MTNS AFT 06Z WITH DRYING ASSOCIATED WITH STG DOWNSLOPING. WHEREAS IN THE MTNS...SHOULD SEE WIDESPREAD SNOWSHOWERS DVLPG AOA 05Z AND CONTINUING THRU MIDDAY SUNDAY. ETA SNOW ACCUMULATION GRIDS AND OROGRAPHIC SNOW MODEL CAME UP WITH 3-7 INCH SNOW TOTALS IN MTN ZNS 33 AND 34...AND UPWARDS OF 10 INCHES IN MTN ZN 30 WHERE CAA AND STG NWLY FLOW ALOFT WILL FAVOR MOST. SUNDAY LOOKS DRY AND WINDY ON THE PLAINS...ALTHOUGH INCREASING MID-LVL LAPSE RATES IN THE AFTERNOON COULD RESULT IN ISOLD SHOWERS AND T-STORMS ON NERN PLAINS. ALSO SEE NWLY WNDS GUSTING 25-35KT PLAINS AND FTHLS FOR MUCH OF THE DAY WITH GUSTS ABV 50 KTS CAUSING BLOWING SNOW NEAR AND ABV TIMBERLINE. BAKER LONG TERM DISCUSSION...MODELS ARE A BIT DRIER WITH EXITING SYSTEM SUN NIGHT AND MON WITH LESS WRAPAROUND MOISTURE. STILL PLENTY OF WIND THOUGH. I WILL TRIM POPS A BIT THROUGH THIS PERIOD. A SECOND SHORT WAVE STILL DROP OVER CO ON MON BUT LOOKS TO BE OVER DRY AIR SO THE MAIN EFFECT MAY BE TO BRING DOWN A SURGE OF COOLER AIR. THERE IS LESS MODEL AGREEMENT FOR SHORTWAVES SHOOTING ACROSS DURING THE MIDDLE OF THE WEEK IN MODEST WESTERLY FLOW. TREND HAS BEEN TO HAVE THE WEATHER NORTH AND SOUTH OF US...I WILL STICK WITH THE LOW POPS WE HAVE. THERE SHOULD BE DRYING AND WARMING THEREAFTER. NEXT SYSTEM MAY COME OVER THE ROCKIES DURING THE WEEKEND. OPERATIONAL GFS SEEMS TO BE FASTER AND FARTHER SOUTH THAN MOST...BUT IF WE DO NOT SEE THE EFFECTS OF THAT SYSTEM WE MAY HAVE ENOUGH WARMING AND MOISTURE RETURN ANYWAY...SO I WILL PUT IN LOW POPS FOR FRI/SAT. GIMMESTAD .DEN...WINTER WEATHER ADVISORY TONIGHT AND SUNDAY MORNING NRN CO MTNS ZONES 31...33 AND 34. co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 215 PM MDT SUN MAY 4 2003 GFS INITIALIZED SOUTHERN CALIFORNIA SUBTROPICAL JET CORE BEST THIS MORNING WITH THE ETA WIND SPEEDS OVERDONE AND TOO FAR NORTH. FORECAST AREA COMES UNDER NOSE/LEFT EXIT REGION TONIGHT. BEST DIVERGENCE AND LIFT WILL BE OVER THE NORTHERN PORTIONS OF THE FORECAST AREA. THIS JET CORE WILL BE PUSHED SOUTH ON SUNDAY BY THE BACKSIDE POLAR JET WRAPPING INTO THE UPPER CIRCULATION. THE FORECAST AREA WILL BE UNDER MAINLY DIVERGENCE/SUBSIDENCE DURING THIS TIME. 500 MB HEIGHT FALLS ON THE ORDER OF 5 TO 10 DAM OVERSPREAD THE FORECAST AREA THIS EVENING WITH APPROACHING TROUGH AXIS. CYCLONIC VORTICITY ADVECTION BY THE THERMAL WIND WILL BE IN PLACE OVER THE ENTIRE AREA DURING THE EVENING HOURS...BUT THEN SHIFTS TO PRIMARILY THE NEBRASKA COUNTIES AFTER MIDNIGHT AS THE THERMAL WIND FIELD BACKS TO SOUTH/SOUTHWEST. BY 12Z ONLY THE EXTREME EASTERN PORTIONS OF THE AREA ARE UNDER ANY QUASI GEOSTROPHIC LIFT. THE ETA THEN ROTATES A VORTICITY LOBE OVER THE NORTHERN ZONES SUNDAY AFTERNOON AROUND THE MAIN UPPER LOW LOCATED OVER SOUTH DAKOTA. GFS LIMITS THIS ENERGY TO NORTHERN FRINGES (NEBRASKA) WHILE THE NGM IS DOMINATED BY SUBSIDENCE ON SUNDAY. ANALYSIS OF CONVECTIVE PARAMETERS FOR TONIGHT SHOWS MARGINAL INSTABILITY IN PLACE IN THE NORTHWEST CORNER AT 00Z WITH K-INDEX IN THE UPPER 20S AND TOTAL TOTALS IN THE UPPER 50S (GFS). HOWEVER...700 MB DRY PUNCH IS EVIDENT AND BY 06Z 700 MB DEWPOINTS DROP BELOW -10C FOR ALL BUT THE FAR EASTERN ZONES...MAKING CONVECTION EXTREMELY UNLIKELY ELSEWHERE. BY 12Z 700 MB DEWPOINTS ARE IN THE LOWER TO MIDDLE TEENS EVERYWHERE AND CONVECTION SHOULD BE WELL EAST. GFS SHOWS SOME RECOVERY OF MOISTURE DURING THE DAY ON SUNDAY...BUT WET BIAS MAY BE PRESENT AS ETA SHOWS ONLY MODEST RECOVERY WITH 700 MB DEWPOINTS AT AROUND -10C. BASED ON THE ABOVE HAVE KEPT SCATTERED THUNDER IN NORTHERN AND EASTERN ZONES TONIGHT...DRY ELSEWHERE. FOR SUNDAY...HAVE REMOVED PRECIPITATION EXCEPT IN NORTHERN ZONES WHERE RETAINED SLIGHT CHANCE OF SHOWERS/THUNDER ASSOCIATED WITH WEAK VORT LOBE/COLD POOL ALOFT. OTHER CONCERN ON SUNDAY WILL BE WIND. DEVELOPMENTAL RUC SHOWS NORTHWEST WINDS SUSTAINED AT 30 MPH OVERSPREADING MUCH OF THE FORECAST AREA BY 21Z. DO NOT SEE A HIGH WIND EVENT...THOUGH AN ADVISORY WILL LIKELY BE REQUIRED. WINDS DROP DRAMATICALLY AFTER 03Z AS SURFACE LOW PULLS AWAY TO THE NORTHEAST. FOLLOWED MAV FOR LOW TEMPERATURES AND A BLEND OF MET/MAV FOR HIGHS. MONDAY...WEAK JET DYNAMICS RESULT IN CONVERGENCE/SUBSIDENCE ALOFT REINFORCED BY COLD ADVECTION IN LOWER LEVELS. 850 TEMPERATURES COOL SLIGHTLY AS DOES SHORT TERM MOS GUIDANCE. TUESDAY...GFS BRINGS A SHORTWAVE ACROSS THE FORECAST AREA DURING THE AFTERNOON. INSTABILITY PARAMETERS/MOISTURE AXIS FORECAST TO INCREASE OVER EASTERN COLORADO. WILL THEREFORE INTRODUCE SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS IN COLORADO COUNTIES DURING THE AFTERNOON AND EVENING HOURS. 850 TEMPERATURES ARE COOLEST OF THE PERIOD WITH A MOIST UPSLOPE FLOW INDICATED IN LOW LEVELS. EXTENDED...LOW CONFIDENCE FOR WEDNESDAY AND THURSDAY WITH GFS CONTINUING TO BRING PERIODIC SHORTWAVES ACROSS THE AREA IN SOUTHWEST FLOW ALOFT. SOME JET DYNAMICS FROM LEFT EXIT REGION...ESPECIALLY ON WEDNESDAY. MOISTURE WOULD APPEAR TO BE BEST IN THE WEST ON WEDNESDAY AND THE EAST ON THURSDAY. HOWEVER...LARGE AREA OF CONVECTION MAY BE IN PROGRESS WITHIN MOISTURE TRAJECTORY TO THE SOUTHEAST OF THE AREA BOTH DAYS. WARMED UP TEMPERATURES TO COME MORE IN LINE WITH CURRENT GFS GUIDANCE AND SURROUNDING OFFICES. MORE SIGNIFICANT SYSTEM APPROACHES FOR THE END OF THE WEEK. GFS WANTS TO DRY SLOT THE AREA ON SATURDAY...BUT EXPECTATION IS THAT THE MODEL IS TOO FAST WITH UPPER LOW...AND MOISTURE AXIS WILL BE FURTHER WEST. .GLD...NONE. $$ JDK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 406 PM EDT SAT MAY 3 2003 SHORT TERM...TONIGHT AND SUN WV IMAGERY AND RUC ANALYSIS INDICATED MID/UPR LVL LO OVER NE CANADA AND POTENT SHRTWV AND 140 KT H25 JET INTO SRN CA/NV WHILE RDGING PREVAILED OVER THE SRN/CNTRL PLAINS AND FROM THE UPR MS VALLEY INTO CNTRL CANADA. AT THE SFC...HI PRES WAS ENTRENCHED OVER THE NRN LAKES. INCREASING SRLY FLOW AND H8 THETA-E ADVECTION INTO THE NRN PLAINS AND UPR MS VALLEY AHEAD OF SFC TROF INTO THE HIGH PLAINS SUPPORTED SOME TSRA OVER NRN SD AND EN ND. SUNSHINE WITH MIXING INTO VERY DRY AIRMASS HAS AGAIN PUSHED DEWPOINTS TO AROUND 10-15F INLAND OVER UPR MI. WITH SFC AND MID LVL RDG CONTINUING TO DOMINATE...MAIN FCST CONCERN WILL CONTINUE TO BE TEMPS. TONIGHT...INCREASING SRLY LOW LVL FLOW WILL KEEP TEMPS FROM FALLING OFF AS MUCH AS PREVIOUS NIGHTS DESPITE MAINLY CLEAR SKIES AND LINGERING DRY AIR OVER THE AREA. SO...HAVE GONE WITH MIN TEMPS NEAR GUIDANCE AROUND 30 F. SUN...WITH INCREASING SE WINDS AHEAD OF THE DEVELOPING LOW...COLDEST AIR FROM LK MI SHOULD SPREAD INLAND. OTHERWISE...MIXING TOWARD H8 TEMPS AROUND 4C SUPPORT TEMPS INTO THE MID 60S F INLAND. ETA RH PROG SUGGESTS THICKER CLOUDS WILL HOLD OFF UNTIL LATE IN THE AFTERNOON OR EVENING OVER THE SW. JLB LONGER TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)... FORECAST CONCERN IS WET PATTERN THAT APPEARS TO BE SETTING UP EARLY NEXT WEEK. THIS IS GREAT NEWS FOR FIRE WEATHER CONCERNS THAT HAVE BECOME SUBSTANTIAL OF LATE. ISENTROPIC LIFT (305-315K) INCREASES SUNDAY NIGHT AS SFC/UPR LOW TAKE FORM IN PLAINS...INITIALLY WORKING ON VERY DRY LOWER AMS...BUT BY OVERNIGHT HOURS SHOULD SEE PCPN BEGIN FROM THE SW MOVING NE. ETA SOUNDINGS CONTINUE TO SHOW RAPID MOISTENING OF ENTIRE PROFILE...BUT THIS MAY NOT BE TOO FAR-FETCHED CONSIDERING MOISTURE ADVECTION OCCURRING IN PLAINS CURRENTLY (SFC DEWPTS ALREADY ABOVE 50F IN SD... AND PWATS THERE TO AN INCH BY THIS EVENING). SO...SHOULD SEE A PRETTY GOOD PCPN GRADIENT WHEN THINGS KICK IN...ESPECIALLY WITH DRY EAST WIND AT SFC. HAVE OPTED TO REMOVE MENTION OF THUNDER SUN NIGHT THOUGH...BASED ON VERY UNIMPRESSIVE MID LEVEL LAPSE RATES OF AROUND 5C/KM (700-500MB). MIGHT NOT EVEN SEE PCPN IN EASTERN COUNTIES UNTIL DAYTIME. NEARLY STACKED SFC/UPR LOW MOVE INTO UPPER MISSISSIPPI VALLEY MONDAY AND MONDAY NIGHT. WITH THE U P BEING UNDER REGION OF DIVERGENCE ALOFT (UNLIKE PAST FEW TROUGHS)...AND CONSIDERING AMOUNT OF MOISTURE THAT LOOKS TO GET WRAPPED INTO THIS SLOW-MOVING SYSTEM...SHOULD SEE WET PERIOD DEVELOP THAT MAY LAST THROUGH MUCH OF TUESDAY. WITH BLOCKING RIDGE IN SASKATCHEWAN/MANITOBA...ETA AND GFS NOW AGREE (TO A GREATER EXTENT THAN BEFORE) TO THIS SLOW SOLUTION OVERALL...WITH SFC LOW IN SE MN LATE MON...AND LOWER MI LATE TUE. SO HAVE OPTED TO RAISE POPS TO CATEGORICAL ACROSS THE BOARD FOR PERIODS 4/5...AND KEEP LIKELY SHRA GOING TUE UNDER UPR LOW. SFC WARM FRONT DURING THIS TIME MAKES IT NO FURTHER NORTH THAN ROUGHLY A MKE-APX LINE...SO ANY CONVECTION WILL REMAIN ELEVATED. MID LEVEL LAPSE RATES STEEPEN AT HEAD OF H8 THETA-E TONGUE TO OUR SOUTH BY MONDAY AFTN AND NIGHT... THOUGH WITH NOT MUCH ELEVATED CAPE (100J/KG OR LESS PER THE ETA AT KMNM). WILL MENTION CHC TS IN S/SE ZONES ONLY...WITH BEST BET BEING LATE MON/MON NIGHT. FURTHER NORTH...WILL BE TOO ENTRENCHED IN COOLER AIR...THOUGH MAY SEE SOME CONVECTIVE ELEMENTS AND PERIODS OF HEAVIER RAIN. E/NE FLOW OFF OF LAKE SUPERIOR WILL MEAN A COLD RAIN AT THAT FOR THE NORTH...WHERE TEMPS WILL PROBABLY NOT GET OUT OF THE 40S MON AND TUE. WINDS WILL ALSO BE A CONCERN MONDAY...ESPECIALLY OVER THE LAKE WHERE HAVE KEPT MENTION OF GALES. IN THE EXTENDED...12Z GFS RUN SHOWS LINGERING SFC TROF WED AND THU...THOUGH HAVE NOT BOUGHT OFF ON THAT YET AND HAVE SIDED WITH ECMWF/UKMET/CANADIAN AND 00Z GFS IN BUILDING SFC RIDGE AND DRY WX DURING THIS TIME. BOTH GFS RUNS THEN BRING WEAK SHORTWAVE THROUGH TO OUR WEST BY FRI...THOUGH HAVE OPTED TO KEEP THIS DAY DRY AS WELL WITH THE THINKING THAT IT IS BRINGING IT IN TOO QUICKLY AS IT HAS SO OFTEN THIS SPRING. EMERGENCE OF STRONGER TROF AND DEVELOPING PLAINS LOW (PER ENSEMBLES AS WELL) WILL BRING NEXT CHANCE OF SHRA BY SATURDAY. DAYS 4-7 ARE A LITTLE TRICKY RIGHT NOW...AND WILL HINGE ON WHETHER SFC HIGH DOES INDEED BUILD OVER THE UPPER LAKES BY MID WEEK. COORDINATED WITH APX AND GRB...THANKS. JKL .MQT...NONE. mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 350 PM EDT SAT MAY 3 2003 12Z RAOBS/WATER VAPOR LOOP SHOW UPPER LOW JUST SOUTH OF LOWER MICHIGAN...WITH RIDGE ACROSS THE CENTRAL CONUS. SPLIT ENERGY MOVING ONSHORE ACROSS THE NORTHWEST AND SOUTHWEST COASTS. SURFACE ANALYSIS SHOWS HIGH OVER THE NORTHERN GREAT LAKES WITH HIGH ORGANIZING OVER THE HIGH PLAINS. PERSISTENT BATCH OF CLOUDS HOLDING ACROSS THE SOUTHERN CWA...OTHERWISE SKIES ARE CLEAR UPSTREAM. WEAK ECHOES APPARENT SOUTH OF THE STATE UNDER THE UPPER LOW...BUT NOT PRECIP ACROSS THE CWA. MAIN CONCERN IS WITH SEVERE THREAT ON MONDAY. TO BEGIN WITH THE CONCERN IS WITH FROST/FREEZE POTENTIAL TONIGHT. SURFACE HIGH SLIDES EAST OVERNIGHT...WITH GRADIENT WEAKENING A BIT OVER SOUTHEAST MICHIGAN. ETA/GFS INDICATE CLOUDS ACROSS THE SOUTH SCOURING OUT...LEAVING CLEAR SKIES ACROSS THE STATE. LOOKING AT 15Z RUC WILL HOLD ON TO CLOUDS A BIT LONGING INTO THE EVENING...AND EVENTUALLY BECOMING MOSTLY CLEAR ACROSS THE SOUTHERN COUNTIES. COMPARED TO LAST NIGHT...ATMOSPHERE IS DRIER AND GRADIENT IS A BIT WEAKER...POINT TOWARDS ANOTHER NIGHT DECOUPLING AND DROPPING TOWARD FREEZING. HOWEVER WITH MORE OF A EAST/NORTHEAST WIND DIRECTION OFF LAKES HURON/ERIE...SURFACE DEWPOINTS AT MANY STATIONS ARE HOVERING IN THE LOW-MID 40S. FNT INLAND IS LOWEST IN OUR CWA WITH A 32F DEWPOINT...AND JUST WEST IN THE STATE STATIONS ARE IN THE UPPER 20S. SHOULD SEE TEMPERATURES DROPPING CLOSE TO FREEZING...ALTHOUGH DO NOT SEE MANY SITES DROPPING BELOW 30 AS NEEDED FOR A FREEZE WARNING. AFTER COORDINATION WILL GO WITH A FROST ADVISORY FOR MOST OF THE CWA...LEAVING OUT WAYNE AND MONROE COUNTIES WITH LOWS IN THE UPPER 30S. QUIET DAY ON SUNDAY WITH HIGH SHIFTING EAST AND A LIGHT EAST/SOUTHEAST GRADIENT. DECENT SUNSHINE AND WEAK WARMING SHOULD ALLOW TEMPERATURES TO CLIMB ABOUT 5-10F WARMER THAN TODAY...GENERALLY INTO THE MID 60S. FLOW OFF THE LAKES WILL KEEP TEMPERATURES COOLER ALONG THE SHORE AND A BIT INLAND. ENERGY MOVING ONSHORE ACROSS THE WEST BEGINS TO CUT OFF OVER THE CENTRAL PLAINS. SURFACE LOW SHIFTS INTO NEBRASKA AND DEEPENS. AT THIS POINT DO NOT SEE MORE THAN INCREASING HIGH CLOUDS LATE IN THE DAY THIS FAR EAST. SYSTEM TRACKS TO FAR SOUTHERN MINNESOTA SUNDAY NIGHT...BRINGING A WARM FRONT INTO THE OHIO VALLEY. MOISTURE SLOWLY INCREASES WITH EASTERLY FLOW HELPING TO KEEP THE LOW LEVELS DRY THROUGH THE EVENING. LOOKS AS THROUGH A DECENT SHOT OF PRECIP WILL MOVE THROUGH WITH GOOD LIFT/MOISTURE RETURN WITH STRONG THETA-E ADVECTION. WILL BUMP POPS UP A CATEGORY...TO LIKELY ACROSS MUCH OF THE CWA AND ADD A CHANCE ACROSS THE THUMB. LOOKS AS THOUGH MOST SHOULD SEE A SHOT OF PRECIP BUT WITH TIMING STRADDLING THE PERIODS SUNDAY NIGHT/MONDAY. WITH THAT THINKING WOULD CARRY LIKELY POPS INTO MONDAY MORNING AS WELL. IF THE 12Z RUNS OF THE GFS AND ESPECIALLY THE ETA PAN OUT...WE COULD HAVE A VERY BUSY DAY ON MONDAY /WHICH WOULD BE AN UNDERSTATEMENT/. DESPITE THE SYSTEM WORKING OVER THE AIRMASS IN THE MORNING...STRONG WARM ADVECTION AS THE WARM FRONT LIFTS INTO THE STATE WILL RETURN US TO VERY UNSTABLE CONDITIONS. FORECAST SOUNDINGS/PLAN VIEWS INDICATE CAPE UP TO 3000J/KG AND LIFTED INDEX DROPPING BELOW -10C. LAPSE RATES STEEPEN SIGNIFICANTLY...OVER 8C/KM THROUGH MUCH OF THE PROFILE. IN ADDITION ALONG THE WARM FRONT HELICITY VALUES CLIMB NEAR 300M2/S2. MUCH DEPENDS AND THE LOCATION OF THE WARM FRONT...AND EVEN IF IT STALLS SOUTH /WHICH ETA-AVN MOS GUIDANCE WOULD INDICATE/ THERE WOULD STILL BE PLENTY OF ELEVATED INSTABILITY. STAY TUNED AS THIS SITUATION EVOLVES. WITH EVENTS IN THE MORNING AND AGAIN TOWARD AFTERNOON...WILL CALL IT SHOWERS AND THUNDERSTORMS LIKELY FOR THE DAY ON MONDAY. ALSO WILL CARRY LIKELY POPS OVER INTO MONDAY NIGHT. MAIN LIFT/MOISTURE CLEARS THROUGH FOLLOWING MONDAY NIGHT...AND WILL CUT POPS BACK FOR TUESDAY/TUESDAY NIGHT. WE ALSO STABILIZE MORE...ENOUGH TO PULL MENTION OF THUNDERSTORMS...LEAVING A CHANCE OF RAIN /MAINLY FOR TUESDAY/. FOR THE EXTENDED...UPPER LOW OVER THE WESTERN GREAT LAKES WEAKENS AND PULLS EAST...AS UPPER TROUGH REDEVELOPS BACK ALONG THE WEST COAST. SURFACE HIGH BUILDS ACROSS NORTHERN ONTARIO...LEADING TO A DRY FORECAST. PREVIOUS GFS/ETA-XX BROUGHT A SERIES OF WAVES UP FROM THE GULF...TRACKING FARTHER WEST EVENTUALLY ACROSS THE GREAT LAKES. HOWEVER THE CURRENT GFS/ETA-XX HAVE BACKED OFF THIS PATTERN...HAVING RETURNED TO PREVIOUS PATTERN FROM SIMILAR TO TWO DAYS AGO. BOUNDARY ACROSS THE OHIO/TENNESSEE VALLEYS WILL CONTINUE TO SAG SOUTH. IF WE DO SEE PRECIP WITH A WAVE RIPPLING ALONG THIS FRONT IT WOULD BE MORE WEDNESDAY/WEDNESDAY NIGHT. HOWEVER WILL KEEP IT DRY FOR NOW THROUGH SATURDAY. NEXT SHOT FOR WIDESPREAD PRECIP LOOKS TO BE SUNDAY...POSSIBLY WORKING IN LATE SATURDAY BUT WITH TIMING ISSUES WILL LEAVE IT OUT OF THE FORECAST. .DTX...FROST ADVISORY...TONIGHT.... MIZ047>049-053>055-060>063-068>070-075-082 /ALL EXCEPT MIZ076-MIZ083/. $$ BRAVENDER EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi WEST CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 215 PM CDT SAT MAY 3 2003 PRIMARY FORECASTS CONCERNS ARE THUNDERSTORM CHANCES THIS EVENING AND SUNDAY AFTERNOON OVER THE EAST. 18Z SURFACE MAP SHOWS A DRYLINE EXTENDING FROM THE NW TIP OF CROCKETT COUNTY...NORTHWARD INTO THE SOUTH PLAINS...SW OF LUBBOCK. 19Z GOES VISIBLE IMAGERY SHOWS DEVELOPING CU NEAR THE EXPECTED DRYLINE POSITION...EAST OF KFST. 15Z RUC PROGS THE DRYLINE TO MAKE LITTLE EASTWARD PROGRESS THIS AFTERNOON...ALTHOUGH SOME DRIER MID LEVEL AIR IS PROGGED TO MIX TO THE SURFACE OVER THE WESTERN CONCHO VALLEY AND WESTERN BIG COUNTRY. 12Z MESOETA BOUNDARY LAYER CAPE/CINH PROG IS IN LINE WITH THE 06Z RUN IN DEVELOPING 3000+ J/KG BOUNDARY LAYER CAPE WITH NO CAP BY 21Z OVER THE HEARTLAND AND EASTERN BIG COUNTRY. UNLIKE FRIDAY...12Z MAF SOUNDING HAD MOISTURE IN THE LOWER LEVELS...WITH 17C DEWPOINTS UP TO 840MB. AS IT IS PRONE TO DO...THE MESOETA MAY BE MIXING THE DRYLINE TOO FAR EAST THIS AFTERNOON. FOLLOWING RUC SOLUTION...AN ISOLATED THUNDERSTORM OR TWO COULD DEVELOP AS FAR WEST AS THE SAN ANGELO AREA LATER THIS AFTERNOON. 18Z FWD SOUNDING SHOWS WEAK CAPPING...WITH EASILY REACHED CONVECTIVE TEMP INFERRED FOR OUR EASTERN BIG COUNTRY COUNTIES. ENTRANCE REGION OF LOW LEVEL JET WILL SET UP OVER WC TX TONIGHT... WITH NO LARGE AREAS OF ORGANIZED MOISTURE CONVERGENCE EXPECTED. IN RESPONSE TO A SHORTWAVE TROF PASSAGE SUNDAY AFTERNOON...THE MESOETA BRINGS THE DRYLINE THROUGH MOST OF WC TX. AVN MAV GUIDANCE IN AGREEMENT...WITH MID UPPER 40S DEWPOINTS AT KABI/KSJT AND MID 60S DEWPOINTS AT KSJT. CURRENT ISC GRIDS INDICATE NO CHANCE OF THUNDERSTORMS OVER THE HEARTLAND/NW HILL COUNTRY FOR SUNDAY...BUT WE HAVE RESERVATIONS CONCERNING UNDERESTIMATED MESOETA BOUNDARY LATER CAPE IN THE PRESENCE OF STRONG LOW LEVEL CONVERGENCE OVER EASTERN PORTIONS OF THE FORECAST AREA. WILL LIKELY ADJUST GRIDS AND MAINTAIN SLIGHT CHANCE POPS FROM THE PREVIOUS FORECAST OVER THE HEARTLAND/NW HILL COUNTRY. SHORTWAVE RIDGING ALOFT SHOULD KEEP A LID ON THUNDERSTORM DEVELOPMENT MONDAY...BUT APPROACHING SHORTWAVE TROF SHOULD COOL MID LEVEL TEMPS SUFFICIENTLY TO HELP STORMS FIRE OVER THE EAST ON TUESDAY. PERSISTENCE APPEARS TO BE BEST FORECAST THROUGH LATE NEXT WEEK... UNDER WEAK CONVECTIVE CAP. ABI 071/093/063/088/061 22101 SJT 072/095/065/091/063 11101 JCT 070/090/064/092/062 22111 .SJT...NONE. 14 tx AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1154 AM CDT SAT MAY 3 2003 LOW LEVEL MSTR MUCH FARTHER W THAN 24HRS AGO PER 48 DEWPOINT AT MRF AND 52 AT CNM AT 10 AM. 15Z RUC II MUCH SLOWER IN BRINGING MSTR E AND HOLDS CONVERGENT AXIS W ACRS PB. FARTHER W AND LITTLE HIGHER UP MSTR DROPS OFF RAPIDLY...WITH RIDGE TOP WINDS ACRS GDP MTNS 28016G37MPH AND MIXING ACRS WRN PB EXPECT DRYLINE WILL MOVE/JUMP TO CENTRAL PB BY 19Z AND THEN HOLD AS 85H WINDS TEND TO STAY S THRU 21Z EWD INTO WRN LOW ROLLING PLAINS. BEST LOW LEVEL CONVERGENCE FCST TO BE ACRS PB N INTO S PLAINS WITH BEST 3H DIVERGENCE W NEAR COINCIDENT. CERTAINLY AGREE ON HIGH CONDITIONAL PROBABILITIES IN REGARD TO SEVERE STORMS (HIGH CAPES AND 55KT VWS)...INITITATION IS THE CHALLENGE. BASED ON LOOK AT VISIBLE SATELLITE IT SEEMS THAT AT LEAST EARLY ON BEST FOCUS/ESTABLISHED MSTR AXIS FOR PREFERED INITITIATION IS JUST NE-E OF CWFA...BUT WITH DRYLINE HOLDING FARTHER W WILL HAVE UPDATE ZFP/HWO TO REFLECT POPS IN PB WITH MENTION OF SEVERE E. HAVE ALSO UPDATED WWA SECTION. COORD WITH LBB. .MAF... TX...RED FLAG WARNING THROUGH EVENING TXZ057-074-0258. ...HIGH WIND WATCH GUADALUPE MOUNTAINS FOR SUNDAY. ...FIRE WEATHER WATCH FOR SUNDAY ALL AREAS EXPECT PRESIDIO VALLEY AND TERRELL COUNTY. NM...RED FLAG WARNING THROUGH EVENING NMZ112. ...HIGH WIND WATCH GUADALUPE MOUNTAINS FOR SUNDAY. ...FIRE WEATHER WATCH FOR SUNDAY NMZ112. $$ tx