AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 1233 PM MST THU AUG 16 2007 .SYNOPSIS... SHOWERS AND THUNDERSTORMS WILL CONTINUE DRIFTING WESTWARD...THROUGH SOUTHWEST ARIZONA TONIGHT. AREAS OF DENSE BLOWING DUST ARE POSSIBLE WITH SOME OF THESE STORMS. SUFFICIENT MOISTURE WILL SUPPORT A SLIGHT CHANCE FOR LATE AFTERNOON AND EVENING STORMS OVER SOUTH CENTRAL ARIZONA FRIDAY AND SATURDAY. STRONG HIGH PRESSURE ALOFT WILL ESTABLISH RESIDENCE OVER SOUTHERN ARIZONA BY SUNDAY...THEN REMAIN CENTERED OVER OR JUST SOUTH OF OUR AREA THROUGH THE MIDDLE OF NEXT WEEK. EXPECT DRIER AIR TO OVERSPREAD THE REGION...ALONG WITH VERY WARM TO HOT DAYTIME HIGHS...MONDAY AND TUESDAY. A WEATHER DISTURBANCE FROM THE EASTERN PACIFIC WILL BRING A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS TO SOUTH-CENTRAL ARIZONA BY NEXT THURSDAY. && .SHORT TERM... TONIGHT THROUGH SUNDAY... SEVERE TSTM WATCH FOR MARICOPA AND PINAL COUNTIES CANCELLED AT 730 PM MST. BUT...WIDELY SCATTERED THUNDERSTORMS CONTINUED TO FORM AND PROPAGATE WESTWARD THIS EVENING...MAINLY THROUGH REMOTE AREAS OF ZONE 21 AND 26. LATEST YUMA RADAR INDICATED AT LEAST ONE STRONG OUTFLOW BOUNDARY WELL SOUTH OF INTERSTATE 8...CLOSER TO THE MEX BRDR BETWEEN 03Z AND 04Z. PLENTIFUL MOISTURE...WITH DEW POINTS 60 TO 65...ALONG WITH AN OUTFLOW BOUNDARY AND GOOD STEERING FLOWS...SUPPORT BETTER TSTM CHANCES AND POSSIBLE DUST STORM FOR ZONE 25 LATER THIS EVENING. RUC EVEN DRIVES THE WEAK INVERTED TROUGH INTO RIVERSIDE COUNTY BY AROUND 12Z. ACROSS THE REST OF THE CWA...THE EARLIER CONVECTION IN ZONES 24 AND 28 WAS ABOUT OVER. ALTHOUGH MANY AREAS DID NOT RECEIVE ANY PRECIP...IT WAS THE WIND...OVER 40 MPH IN MANY LOCATIONS THAT BROUGHT THE VISIBILITY WAY DOWN. 03Z KPSR SOUNDING STILL HAD SOME POTENTIAL FOR NIGHTTIME SHOWERS OR TSTMS...AND ZONE UPDATES WERE ISSUED BY 9 PM. STEERING FLOW BECOMES SOUTHERLY BY FRIDAY...THEN SOUTHWESTERLY BY SATURDAY...AS STRONG UPPER LOW AND ASSOCIATED TROUGH MOVE INTO THE CENTRAL AND NORTHWEST PACIFIC COAST REGION. LESS FAVORABLE STEERING FLOW...NO APPARENT UPPER LEVEL TRIGGER...AND LESS INSTABILITY SUGGESTS THAT ONLY SLIGHT CHANCE FOR STORMS IS WARRANTED FOR SOUTH CENTRAL AZ FRIDAY AND SATURDAY EVENINGS. DRYING BECOMES MORE NOTICEABLE BY SUNDAY AS STRONG UPPER HIGH BECOMES CENTERED OVER SOUTHEAST ARIZONA...AND DAYTIME HIGHS WILL BEGIN TO CREEP EVEN HIGHER BY THAT TIME. NOTE TO USERS...KIWA 88D RADAR STILL DOWN DUE TO EQUIPMENT FAILURE. && .LONG TERM... SUNDAY NIGHT THROUGH THURSDAY... LOOKS RATHER DRY FOR OUR CWA SUNDAY NIGHT THROUGH TUESDAY NIGHT AS STRONG RIDGE OF HIGH PRESSURE ALOFT LIES ACROSS SOUTHERN CALIFORNIA AND SOUTHERN ARIZONA. MAX TEMPS WILL LIKELY REACH OR EXCEED HEAT ADVISORY THRESHOLD FOR SOUTH-CENTRAL AZ...AND MAYBE FAR SOUTHEAST CALIFORNIA AND SOUTHWEST AZ...MONDAY AND TUESDAY...WITH HOTTEST MAX TEMPS LIKELY TUESDAY AS NOTICEABLY DRIER AIR OVERSPREADS THE REGION. BY LATE WEDNESDAY OR THURSDAY...A WEATHER DISTURBANCE FROM THE EASTERN PACIFIC WILL APPROACH THE AREA. THIS SYSTEM WILL LIKELY TAP INTO ENOUGH LOW-LEVEL MOISTURE TO BRING AT LEAST A SLIGHT CHANCE FOR STORMS TO SOUTH-CENTRAL ARIZONA. EXPECT SOME LOWERING OF MAX TEMPS WEDNESDAY...WITH TEMPS LOWERING TO NEAR CLIMO LEVELS BY THURSDAY. .AVIATION... AUGUST 17 0733 UTC (AUGUST 17 0033 MST) HAVE UPDATED ALL TAFS TO REFLECT CURRENT TRENDS. RADAR /FYI KIWA IS BACK UP/ AND SATELLITE DATA SHOW SHARP DECREASE IN CONVECTION ACROSS THE REGION. OUTFLOW BOUNDARY PUSHED TO THE COLORADO RIVER BUT APPEARS TO HAVE DECOUPLED FROM THE SURFACE...MEANING STRONG SURFACE WINDS ARE NOT MATERIALIZING. CLOUDS WILL CONTINUE TO DECREASE THROUGH THE OVERNIGHT HOURS. FOR THIS AFTERNOON...BROAD TROUGH WILL PUSH NORTH OUT OF MEXICO IN TO THE SW STATES. MUCH OF TODAY/S CONVECTION WILL OCCUR ALONG AND NORTH OF THIS FEATURE. MODELS PLACE THE TROUGH ALONG THE MOGOLLON RIM BY 18Z...WITH WARMER/DRIER AIR FILTERING IN BEHIND IT /ACROSS SRN AZ AND SE CA/. THEREFORE...NOT EXPECTING A LOT OF TSTM ACTIVITY AT ANY OF THE TAF SITES TODAY /SHOULD BE NORTH OF KPHX AND SURROUNDING AIRFIELDS/. KBLH WOULD BE THE MOST LIKELY SITE TO SEE ANY TSTMS. WILL FURTHER ANALYZE DATA THIS MORNING TO HAMMER OUT THE FINER DETAILS. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... AUGUST 16 2250 UTC (AUGUST 16 1550 MST) STRONG HIGH PRESSURE ALOFT WITH HOT AND VERY DRY AIR IS EXPECTED TO BE OVER OUR AREA DURING THIS PERIOD. THE HIGH PRESSURE SYSTEM IS EXPECTED TO BECOME CENTERED OVER THE PACIFIC WEST OF CALIFORNIA NEAR 135 DEGREES WEST LONGITUDE TUESDAY AND WITH VERY DRY FLOW OF AIR FROM THE WEST OVER OUR AREA. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX SHORT TERM...SIPPLE LONG TERM...DG AVIATION...INIGUEZ FIRE WX...ELLIS az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 336 AM MDT FRI AUG 17 2007 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT... MONSOON FLOW BEING INFLUENCED BY SHORTWAVE TROUGHS/EASTERLY WAVES FROM THE SOUTHEAST. ONE OVER AZ IS FEEDING THE SOUTHWEST PORTION OF THE MONSOON PLUME...WHILE ANOTHER WAVE OVER NEW MEXICO IS ROTATING MOISTURE AND OUTFLOW BOUNDARIES INTO SW CO. OTHER SMALL TROUGHS TO NOTE INCLUDE ONE RESOLVED BY RUC OVER CENTRAL CO AND SECOND OVER NORTHER UT. ALL THIS MEANS THUNDERSTORM COVERAGE SHOULD EVEN OUT A BIT TODAY. HAVE INCREASED POPS OVER THE NORTH TO VALUES SIMILAR TO THE SOUTHERN PORTION OF THE CWA. MODELS NOT REALLY SHOWING MUCH CHANGE FOR SATURDAY. A MODERATE MONSOON FLOW SHOULD CONTINUE WITH SHORTWAVE TROUGH LOCATION DETERMINING ANY THUNDERSTORM FOCUS. PERSISTENCE TEMPERATURE CONTINUE TO APPEAR BEST WAY TO GO AS LITTLE IN THE WAY OF WARM OR COLD TEMPERATURE ADVECTION EXPECTED NEXT 2 DAYS. .LONG TERM (SUNDAY THROUGH THURSDAY)... PATTERN CHANGE WILL BE TAKING PLACE DURING THE EXTENDED PERIOD AS THE UPPER LEVEL RIDGE RETREATS DUE TO STRENGTHENING WESTERLIES AND PACIFIC NORTHWEST SHORTWAVE ENERGY. BY SUNDAY WE ALREADY SEE A SHARP DECREASE IN ACTIVITY AS THE MOISTURE PLUM GETS CUT OFF SOUTH OF THE AREA. BY MONDAY WE SHOULD SEE ONLY A SLIGHT CHANCE OF DIURNAL CONVECTION OVER THE MOUNTAINS WITH LITTLE CHANGE FROM DAY TO DAY THEREAFTER. HIGH TEMPS WILL CONTINUE TO RUN A FEW DEGREES ABOVE NORMAL THROUGH THE PERIOD...WITH LOWS COOLING SLIGHTLY FOR NEAR NORMAL READINGS IN THE DRIER AIR. && .AVIATION... ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS MORNING OVER NORTHWEST COLORADO AND NORTHEAST UTAH. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL RE-DEVELOP FRIDAY AFTERNOON AND EVENING OVER THE MOUNTAINS...WITH ISOLATED SHOWERS AND THUNDERSTORMS OVER THE VALLEYS. LOCAL MVFR CIGS ARE EXPECTED. GUSTY OUTFLOW WINDS AND SMALL HAIL WILL ALSO ACCOMPANY SOME OF THE THUNDERSTORMS. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ SHORT TERM...CJC LONG TERM...JDC/EH AVIATION...CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 955 AM EDT FRI AUG 17 2007 ...ISOLATED STRONG TO SEVERE STORMS POSSIBLE THIS AFTERNOON... .SHORT TERM...NO SIGNIFICANT CHANGES TO FCST. BEST CHANCES FOR TSTMS ARE OVER THE NW 1/2 OF THE AREA...WHERE A COMBINATION OF INSTABILITY... JET DYNAMICS...AND LOW-LEVEL FORCING FROM SEABREEZES AND SFC FRONT WILL EXIST. TUTT LOW OVER THE N BAHAMAS SHOULD CONTINUE TO SUPPRESS CONVECTION OVER SE ZONES DUE TO SUBSIDENCE AND DRIER AIR. 12Z RUC APPEARS TO HAVE A GOOD HANDLE ON THE CURRENT CONDITIONS AND EXPECTED POP ORIENTATION...AND THIS MATCHES WELL WITH ONGOING FCST. && .AVIATION...MAY NEED TO BOOST TSTM COVERAGE IN NEXT TAF SET... PARTICULARLY IN SE GA. OTHERWISE...GENERALLY VFR CONDITIONS AT TAF SITES. && .MARINE...LITTLE CHANGE TO FCST. && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ CARROLL/WALKER/BARRON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 724 AM EDT SAT AUG 18 2007 .SYNOPSIS... A FRONTAL BOUNDARY WILL DROP INTO THE AREA THIS MORNING...THEN DISSIPATE BY SUNDAY. ATLANTIC HIGH PRESSURE WILL REGAIN CONTROL ON MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPSTREAM DEWPOINT OBSERVATIONS INDICATE THE FRONTAL BOUNDARY HAS BEEN SLOWLY SLIDING SOUTH...NOW ACROSS NRN S CAROLINA. THE FRONT SHOULD ENCROACH ON OUR NRN COUNTIES SHORTLY. LAPS ANALYSIS SHOWS POOL OF 1000+ J/KG CAPE ALONG COASTAL SC ATTM. AS WINDS VEER AHEAD OF THE BOUNDARY THIS MORNING...ENOUGH LLVL CONVERGENCE ALONG THE COAST IS POSSIBLE TO SQUEEZE OUT A FEW SHOWERS OR ISOLATED STORMS. AFTER DAYBREAK...INCREASING UPPER DIVERGENCE ON NE SIDE OF A TUTT LOW CROSSING FL...WITH STEEPENING LLVL LAPSE RATES AND PRE- FRONTAL MOISTURE POOLING...SHOULD ALLOW FOR ISOLATED SHOWERS AND STORMS TO DEVELOP. BEST CHANCES FOR THE 1ST HALF OF THE DAY WILL BE ACROSS NORTHERN AREAS CLOSEST TO THE FRONT. RELATIVELY WEAK STEERING FLOW SHOULD ALLOW THE SEABREEZE TO FORM THIS AFTERNOON AND PUSH INLAND. BY THE MIDDLE OF THIS AFTERNOON...THE FRONT WILL LIKELY BE QUITE DIFFUSE WHILE THE SEABREEZE TAKES OVER AS THE PRIMARY FORCING MECHANISM. STEEPENING LOW-LEVEL LAPSE RATES WITH AN INLAND PENETRATING SEABREEZE WILL BE THE BEST FORCING FOR CONVECTION IN SE GA...HOWEVER COVERAGE SHOULD BE PRETTY LIMITED GIVEN A 1.5-2.0 DEGREE CAP PROGGED BY THE NAM12. BOUNDARY LAYER WILL STAY PRETTY WELL MIXED ACROSS INLAND AREAS TODAY DUE TO 20-30 KTS OF FLOW AT 850 MB...THUS DEWPOINTS WILL STRUGGLE TO STAY IN THE LOWER 70S DURING THE AFTERNOON. DESPITE HIGH TEMPS FORECAST IN THE UPPER 90S FAR INLAND...PLUMMETING DEWPOINTS SHOULD PRECLUDE ANY HEAT ADVISORY WORRIES. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... BERMUDA HIGH PRESSURE WILL GRADUALLY STRENGTHEN DURING THE SHORT TERM WITH A PREVAILING ONSHORE FLOW ACROSS THE REGION. NO LARGE- SCALE FORCING MECHANISMS WILL BE PRESENT FOR MUCH MORE THAN ISOLATED AFTERNOON CONVECTION ALONG THE SEABREEZE. NO HIGHER THAN SLIGHT CHANCE POPS DEEMED NECESSARY. && .LONG TERM /MONDAY THROUGH FRIDAY/... ATLANTIC SURFACE HIGH WILL REMAIN CENTERED OFF THE SOUTHEAST COAST WITH AN ONSHORE FLOW ALLOWING THE SEABREEZE TO PUSH INLAND DAILY THROUGH AT LEAST TUE. ISOLATED TO SCATTERED DIURNAL CONVECTION IS ANTICIPATED. THE WESTERN PERIPHERY OF THE HIGH IS EXPECTED BUILD WEST OF THE FORECAST AREA DURING THE WEDNESDAY THROUGH FRIDAY TIME FRAME. THIS MAY RESULT IN HIGHER TEMPERATURES AND A SLOWER INLAND PROGRESS OF THE SEA BREEZE. WHAT REMAINS UNCLEAR IS WHETHER THE INCREASED SEA BREEZE CONVERGENCE WILL ENHANCE COVERAGE/INTENSITY OF CONVECTION...OR WHETHER WARM/CAPPED MID LEVELS WILL LIMIT COVERAGE OF AFTERNOON/EVENING THUNDERSTORMS. ONGOING SLIGHT CHANCE POPS FOR DIURNAL THUNDERSTORMS APPEARS REASONABLE FOR THIS PACKAGE. MEANWHILE...HEAT INDICES WILL APPROACH/EXCEED ADVISORY CRITERIA EACH AFTERNOON/EARLY EVENING THROUGH THE LONG TERM PERIOD. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... THE MAIN CONCERN TODAY CONTINUES TO REVOLVE AROUND SHOWER/TSTM DEVELOPMENT. LATEST RUC MODEL SHOWS CONVECTIVE INITIATION POTENTIAL DURING THE EARLY AFTN HOURS ALONG THE SOUTH CAROLINA COAST THEN ISOLATED STORMS WORK SSW INTO SE GEORGIA MID AFTN. CHANCES STILL LOOK TOO LOW TO FORECAST IN EITHER KSAV/KCHS TAF BUT WILL INTRO A CB MENTION ON 12Z CYCLE. SLIGHT CHC OF MVFR IN BR TOWARD DAWN AT EITHER TERM AND SUN MORNING. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL GENERALLY PREVAIL. RADIATIONAL FOG OR ISOLATED TSTMS COULD BRING BRIEF/LOCALIZED PERIODS OF MVFR OR LOWER CONDITIONS. && .MARINE... WIND SPEEDS WERE SLOWLY DECREASING OVER THE WATERS EARLY THIS MORNING WHILE DIRECTIONS NEAR THE COAST GRADUALLY VEERING WITH TIME AS THE SURFACE FRONTAL BOUNDARY SAGS INTO THE MARINE AREA. INITIAL FORECAST CONDITIONS FOR MOST OF OUR WATERS WILL HIGHLIGHT TODAY/S MAX WIND SPEEDS AS THE LOW LEVEL JET PULLS AWAY THEREAFTER. THE FRONTAL LOCATION WILL BECOME MASKED LATER TODAY BY A PURE ONSHORE COMPONENT WITH THE EVOLUTION OF THE SEA BREEZE. SEAS MAINLY 2 TO 4 FT... SUBSIDING TO 3 FT OR LESS. THE ATLC SFC RIDGE WILL DOMINATE MUCH OF THE FORECAST BEYOND TODAY WITH ONSHORE SPEEDS MOSTLY BLO 15 KT. GROUND SWELL FROM HURCN DEAN WILL LIKELY REACH THE SE COAST LATE TONIGHT OR EARLY SUN. SEAS EXPECTED TO INCREASE TO 3 TO 5 FT EARLY NEXT WEEK...HIGHEST 20-60 NM OFF THE GEORGIA COAST. RIP CURRENTS...WILL NEED TO WATCH FOR PSBL ELEVATED RISK ON SUN WITH SWELLS/ONSHORE FLOW LIKELY MAINTAINING AN INCREASED RISK INTO MIDWEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BOISE ID 902 PM MDT FRI AUG 17 2007 .DISCUSSION...INCLUDES FIRE WEATHER. MINOR UPDATES FOR PFM AND ZFP ON WINDS...WHICH WILL STILL COMBINE WITH DRY CONDITIONS LATE SATURDAY. A DRY AREA OVER N CENTRAL CA WILL LIFT NE TO OVER AN AXIS FROM JUST NE OF MCCALL SOUTH SW THROUGH THE TRI-STATE BORDER FOR SATURDAY AFTERNOON. A MID LEVEL SPEED MAX WITH WINDS OF 15-25 KTS AROUND 10-12K FT MSL WILL ALSO BE OVER OUR REGION SATURDAY. RUC DEPICTS MAX WINDS OVER 100 KTS OVER HARNEY COUNTY BY 12Z. RED FLAG FOR WINDS AND LOW RH WITH DRY FUELS SUPPORTED IN CURRENT NCEP RUNS. MINOR UPDATED...PFM/ZFP AND NOAA WEATHER RADIO FORECASTS /162.40 - 162.55 MHZ/ WIND DIRECTIONS CHANGED FOR POPULATED AREAS SAT/SUN AFTERNOON AND EVENINGS. MINOR ADDITION OF EVENING SMOKE ACROSS SE BAKER COUNTY FROM FAR NW MALHEUR COUNTY. && .AVIATION...WILDFIRE SMOKE CONTINUES TO BRING WIDESPREAD IFR CONDITIONS MAINLY NEAR AND EAST OF MCCALL AND NORTH OF DEADWOOD RESERVOIR. LOCALLY VISIBILITY WILL BE REDUCED TO LESS THAN A HALF A MILE THROUGH THESE MOUNTAIN VALLEYS OVERNIGHT INTO THE EARLY MORNING HOURS. THE TOP OF THE SMOKE LAYER IS 15-20K FT MSL. ELSEWHERE... CONDITIONS ARE VFR. ISOLATED THUNDERSTORMS WILL CONTINUE OVER THE CENTRAL ID MOUNTAINS AND EASTERN ID THROUGH 06Z. SURFACE WINDS WILL BE LIGHT OVERNIGHT...INCREASING TOMORROW...WITH MODERATE TO STRONG SW WINDS ALOFT. && .PREV DISCUSSION... SHORT TERM...TONIGHT THROUGH SUNDAY...MONSOON MOISTURE REMAINS ON THE EASTERN PERIPHERY OF THE CWA THIS AFTERNOON...EVIDENCED BY THE LATEST CONVECTIVE DEVELOPMENT IN SOUTHERN TWIN FALLS COUNTY AND NEAR THE CENTRAL IDAHO MOUNTAINS. WILL CONTINUE WITH ISOLATED THUNDERSTORMS THROUGH SATURDAY IN A SMALL AREA BORDERING THE POCATELLO CWA...WHICH INCLUDES THE AFOREMENTIONED AREAS...ALONG WITH THE WESTERN MAGIC VALLEY. ELSEWHERE...AIRMASS REMAINS DRY AND STABLE WITH PW/S LESS THAN A HALF AN INCH. PACIFIC TROUGH WILL CONTINUE TO PUSH ONSHORE...AND BY SATURDAY EVENING THE DRY SLOT THAT HAS COVERED MOST OF THE AREA WILL SHOVE THE MONSOONAL MOISTURE EAST. GUSTY SOUTHWEST WINDS WILL DEVELOP IN THE AFTERNOON...ESPECIALLY OVER THE MOUNTAINS WHERE WIND GUSTS GREATER THAN 30 MPH WILL PREVAIL. COLD FRONT REMAINS TO THE WEST...AND THICKNESSES STAY ABOUT THE SAME SO EXPECT TEMPS ON SATURDAY TO BE SIMILAR TO TODAY. ON SUNDAY...PACIFIC TROUGH MOVES ACROSS THE REGION...WITH DIFFERENCES IN TIMING OF COLD FROPA. GFS IS 6-12 HOURS FASTER THAN THE NAM...RESULTING IN THE MAV MOS GUIDANCE BEING SEVERAL DEGREES COOLER THAN THE ETA MOS. PREFERRED TO GO WITH A COMPROMISE BETWEEN THE TWO AT THIS TIME. MODELS DEPICT A BAND OF SHOWERS DEVELOPING AND MOVING ACROSS THE NORTHERN TIER ON SUNDAY...WITH THE NAM BEING A BIT MORE GENEROUS WITH QPF AMOUNTS AND SOUTHERN EXTENT OF PRECIP. WENT MORE IN LINE WITH THE DRIER GFS. LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY...MODELS STILL SHOWING SOME TIMING AND AMPLITUDE DIFFERENCES IN THE LONG TERM. HAVE CONTINUED TO TREND FORECAST MORE TOWARDS GFS AND ECMWF SOLUTIONS. BEST CHANCE OF PRECIP STILL LOOKS TO BE SUNDAY NIGHT/MONDAY IN THE NORTHERN ZONES AS UPPER LEVEL TROUGH AND PACIFIC MOISTURE...THE BULK OF WHICH REMAINS IN THE NORTHERN PART OF THE CWA...MOVE ACROSS THE REGION. FLOW BECOMES MORE ZONAL BY MONDAY. HEIGHTS AND THICKNESSES DURING THE PERIOD WILL SUPPORT MORE SEASONABLE TEMPERATURES. ZONAL FLOW CONTINUES THROUGH MID WEEK. BOTH GFS/DGEX HINTING AT WEAK SHORTWAVE AND PACIFIC MOISTURE TO AFFECT THE FORECAST AREA THURSDAY...MAINLY ACROSS SOUTHERN ZONES. LONGWAVE RIDGE REDEVELOPS OVER THE INTERMOUNTAIN WEST BY FRIDAY IN RESPONSE TO UPPER LEVEL LOW IN GULF OF ALASKA. HAVE BEGUN A WEAK WARMING TREND BY WEEK/S END WITH TEMPERATURES 2 TO 3 DEGREES ABOVE NORMAL. HAVE HIGHER CONFIDENCE IN LATEST GUIDANCE AS MODEL AGREEMENT HAS IMPROVED AND SOLUTIONS SEEM FAR MORE REASONABLE THAN PREVIOUS RUNS. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...RED FLAG WARNING FROM 12 PM TO 9 PM MDT SATURDAY FOR IDZ400- IDZ401-IDZ402-IDZ403-IDZ404-IDZ419. OR...RED FLAG WARNING FROM 12 PM MDT /11 AM PDT/ TO 9 PM MDT /8 PM PDT/ SATURDAY FOR ORZ636-ORZ637. && $$ WEATHER.GOV/BOISE DISCUSSION...VM AVIATION.....DF PREV SHORT TERM.....BW PREV LONG TERM......SL/MT id AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 121 AM CDT FRI AUG 17 2007 .DISCUSSION... ISSUED 830 PM CDT THU AUG 16 2007 SHORTWAVE AXIS IS CURRENTLY MOVING ACROSS ILLINOIS AND PUSHING THE REMAINING SHOWERS SOUTHEAST OF THE AREA. CONVECTION HAS BEEN FIRING UP ALONG TRAILING SURFACE FRONT WESTWARD FROM SOUTHERN ILLINOIS BACK INTO CENTRAL MISSOURI...BUT THIS ACTIVITY WILL BE STAYING TO OUR SOUTH. ALTHOUGH THE MAIN FRONT WILL WELL TO THE SOUTH...LOW LEVEL MOISTURE REMAINS POOLED TO THE NORTH ACROSS MOST OF CENTRAL ILLINOIS. WITH CLEARING SKIES AND LIGHT WINDS OVERNIGHT...FAVORABLE CONDITIONS FOR FOG WILL SET UP AND THIS IS ALREADY COVERED IN THE CURRENT FORECAST. WILL CONTINUE TO ISSUE PERIODIC UPDATES AS THE SHOWERS CLEAR THE AREA...BUT THE OVERALL SCENERIO FROM THE AFTERNOON FORECAST PACKAGE REMAINS ON TARGET. && .AVIATION... ISSUED 117 AM CDT FRI AUG 17 2007 FOR 06Z TAFS...FOG WITH AREAS OF DENSE FOG HAVE BEEN DEVELOPING AND WILL CONTINUE INTO THE MORNING HOURS. SO ALL TAF SITES WILL HAVE LIFR CONDITIONS DURING THE MORNING HOURS. FOG SHOULD DISSIPATE QUICKLY IN THE MORNING...BY 14Z ANS NORTHEASTERLY WINDS PICK UP TO AROUND 7KTS. REMAINDER OF THE TAF PERIOD WILL BE VFR WITH RIDGING MOVING ACROSS THE AREA. SOME FOG IS POSSIBLE TONIGHT BUT SHOULD NOT BE BELOW MVFR AS DRIER AIR SHOULD ADVECT INTO THE AREA TODAY. AUTEN && .PREV DISCUSSION... ISSUED 256 PM CDT THU AUG 16 2007 MAIN CONCERNS DEAL WITH LINGERING STORMS THIS EVENING...FOG LATER TONIGHT... THEN STORMS ASSOCIATED WITH A WARM FRONT NEAR US FROM SUNDAY THROUGH TUESDAY. AT 19Z...AN INITIAL COLD FRONT WAS EXTENDING ACROSS THE SOUTHERN TIP OF ILLINOIS...WITH A TRAILING COLD FRONT ACROSS NORTHERN ILLINOIS FROM GBG TO LACON TO JOLIET. COOLER AND DRIER HIGH PRESSURE WAS NORTH OF THAT ACROSS THE UPPER MIDWEST AND SW CANADA. FARTHER SOUTH...THE REMNANTS OF ERIN WEST LIFTING NORTH THROUGH TEXAS TOWARD OKLAHOMA. THAT MOISTURE SHOULD EVENTUALLY BE BOTTLED UP SOUTH OF THE COLD FRONTS AND NOT AFFECT ILLINOIS. ALOFT...ZONAL FLOW WAS PRESENT ACROSS THE CANADIAN BORDER...WITH A SPRAWLING RIDGE ACROSS THE SOUTHERN 2/3 RDS OF THE LOWER 48. SHORT TERM...TONIGHT THROUGH SATURDAY. SOME SEVERE STORMS HIT THIS AFTERNOON WERE ASSOCIATED WITH A MESO VORT INDICATED ON RUC AND RADAR LOOPS. THE UNSTABLE AIRMASS BETWEEN THE TWO COLD FRONTS PROVIDED AMPLE SURFACE BASED INSTABILITY FOR DAMAGING WIND GUSTS. PRECIP LOADING WAS MAXIMIZED OVER VERY SHORT PERIODS OF TIME...WITH PRECIP WATER VALUES NEAR 2 INCHES AND MU CAPES OVER 2K J/KG. ANOTHER CURL IS HEADED FOR OUR NORTHERN CWA...ALONG THE SECONDARY COLD FRONT. HOWEVER...ONLY STEADY RAIN AND ISOLATED STORMS SHOULD DEVELOP FROM THAT COMPLEX. HAVE INCLUDED POPS THIS EVENING BACK UP TOWARD PIA AND BMI FOR LINGERING PRECIP. LATER TONIGHT...AS THE TEMPERATURES FALL BEHIND THE SECONDARY COLD FRONT...FOG WILL LIKELY FORM ALL ACROSS CENTRAL ILLINOIS. WENT WITH AREAS OF FOG AFTER MIDNIGHT IN THE GRIDS. WE SHOULD SEE SOME RELIEF IN TEMPERATURES ON FRIDAY...AS DEWPOINTS DROP INTO THE 50S IN MOST OF CENTRAL ILLINOIS. THE RELIEF WILL BE SHORT LIVED...HOWEVER. SOUTHERLY FLOW RETURNS ON SATURDAY AFTERNOON...AS A WARM FRONT DEVELOPS ACROSS THE ILLINOIS WISCONSIN BORDER. STORMS SHOULD REMAIN NORTH OF OUR CWA...ALONG THE FRONT AND H5 SHORT WAVE PATH. LONG TERM...SUNDAY THROUGH THURSDAY. THE WARM FRONT LOOKS LIKE IT WILL BECOME ACTIVE IN CENTRAL ILLINOIS ON SUNDAY AFTERNOON...WITH A STORM COMPLEX IN IOWA DEVELOPING AND MOVING EAST WITH THE MEAN FLOW INTO CENTRAL ILLINOIS. THE WARM FRONT IS EXPECTED TO LIFT NORTH ON MONDAY...BUT REMAIN VERY CLOSE TO OUR NORTHERN CWA...FROM LACON TO HOOPESTON. WILL KEEP THE CHANCES OF STORMS PRIMARILY IN THE NORTHERN HALF OF THE CWA FOR MONDAY THROUGH TUESDAY...TO ACCOUNT FOR THE ACTIVE STREAM OF SHORTWAVES MOVING EAST FROM THE PLAINS ON SEMI ZONAL FLOW. TEMPS WILL LIKELY CLIMB TO AROUND 90 IN MOST AREAS...WITH LOWER 90S SOUTH OF I-70 MOST DAYS NEXT WEEK. DRY CONDITIONS ARE EXPECTED FOR WED...BUT THUR AND THUR NIGHT HAVE A SLIGHT CHC FOR STORMS AS A DEEPER TROUGH DEVELOPS IN THE UPPER FLOW ACROSS THE WESTERN STATES...PROVIDING OUR AREA WITH A MORE ACTIVE SOUTHWEST FLOW. && .ILX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR ILZ027>031- 036>038-040>057-061>063. && $$ il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PADUCAH KY 929 PM CDT FRI AUG 17 2007 .UPDATE... SECONDARY UPDATE FOR SENSIBLE WEATHER TRENDS TONIGHT. && .DISCUSSION... LATE AFTERNOON/EVENING CONVECTION OVER CARTER/WAYNE COUNTIES UNDERGOING A MEASURABLE DOWNWARD TREND AND SHOULD COMPLETELY DISSIPATE BEFORE 06Z. THE 21Z/00Z RUC CONTINUES TO HAVE THE BEST HANDLE ON THE TEMPORAL/SPATIAL COVERAGE OF THE PRECIPITATION ACROSS THE MO OZARK FOOTHILLS AND WAS FOLLOWED FOR SHORT TERM GUIDANCE FOR THE GRID/TABULAR/GRAPHIC/TEXT UPDATE THIS EVENING. LAPS SURFACE BASED DATA STILL SHOWS A MARKED GRADIENT OF POSITIVE CAPE OVER CARTER AND RIPLEY COUNTIES AS OF 02Z...BUT THE OVERALL SURFACE BASED THETA-E CONVERGENCE CONTINUES TO WITHDRAW BACK INTO AR UNDER NELY WIND FLOW. ALTHOUGH SOME ELEVATED INSTABILITY COULD POSSIBLY TRIGGER SOME ISOLATED CONVECTION BEYOND MIDNIGHT /AS HAS BEEN THE CASE THE LAST COUPLE OF NIGHTS/...THERE DOES NOT APPEAR TO BE A STRONG TRIGGER EVIDENT IN THE SHORT TERM GUIDANCE THAT WOULD SUPPORT WIDESPREAD LIFT FOR SCATTERED THUNDERSTORM DEVELOPMENT OVERNIGHT. SO...FOR NOW...I HAVE DECIDED TO KEEP THE CURRENT FORECAST TREND FOR DRY WEATHER IN PLACE FROM THE 06-12Z SATURDAY TIME FRAME. && .PREV DISCUSSION... /ISSUED 237 PM CDT FRI AUG 17 2007/ DISCUSSION... BIGGEST CHALLENGES WITH THIS PACKAGE WILL BE THE TIMING OF MOISTURE RETURN AND CHANCES OF PRECIP FROM SATURDAY THROUGH MONDAY. DIFFUSE FRONT DIFFICULT TO LOCATE BUT APPEARS TO BE ORIENTED NW-SE JUST OUTSIDE OF THE WESTERN EDGE OF OUR CWA. DRIER AIR HAS FILTERED IN FROM THE NORTHEAST ACROSS ALL OF THE CWA EXCEPT SOUTHEAST MISSOURI. ALSO ACROSS SOUTHEAST MISSOURI IS A NW-SE ORIENTED AXIS OF THETA E...CAPE...AND INSTABILITY. ALTHOUGH THERE APPEARS TO BE NO LOW LEVEL FORCING WITH WINDS FROM THE SURFACE THROUGH 850MB HAVING SOME BIT OF A NORTHERLY COMPONENT...WITH RESIDUAL MOISTURE AND HEATING OF THE DAY...MAY SEE AN EVENING RW/TRW OVER OUR FAR WESTERN COUNTIES THIS EVENING. ON SATURDAY THE SOUTHERN END OF THE AFOREMENTIONED FRONT WILL WASH OUT AND AN E-W ORIENTED WARM FRONT WILL ESTABLISH ITSELF TO THE NORTH OF OUR CWA. ALSO ON SATURDAY WITH THE AXIS OF THE RETREATING HIGH PRESSURE AREA EXTENDING SOUTHWEST ACROSS THE CWA...ONLY CHANCE FOR POPS SHOULD BE ACROSS THE FAR WESTERN SECTIONS...WITH CHANCES MIGRATING SLIGHTLY FURTHER EAST SATURDAY NIGHT. BEST CHANCES FOR POPS ARE ON SUNDAY AS DEEPER MOISTURE IS ADVECTED INTO THE REGION AHEAD OF AN H5 TROUGH MOVING EAST. POP CHANCES TAPER OFF SLOWLY EACH PERIOD THROUGH MONDAY AS RIPPLES OF ENERGY CONTINUE TO TAP INTO DECENT MOISTURE AS THEY PASS EASTWARD ACROSS THE AREA. STARTING MONDAY NIGHT THE UPPER LEVEL RIDGE OVER THE SOUTHEAST US BEGINS TO BUILD SLOWLY NORTHWESTWARD. THIS WILL SERVE TO DEFLECT ANY CHANCES OF PRECIP TO THE NORTH AND WEST OF OUR CWA THROUGH THURSDAY NIGHT. BY FRIDAY FLOW AROUND THE SOUTHERN PERIPHERY OF A CANADIAN VORTEX WILL SUPPRESS THE UPPER RIDGE BACK TO THE SOUTH ALLOWING A SURFACE BOUNDARY TO SAG TOWARD THE REGION ALONG WITH SHORT WAVE ENERGY MOVING EASTWARD ACROSS THE REGION. THEREFORE...PUT A SCHC POPS IN FOR DAY SEVEN AND BEYOND. FOR TEMPERATURES...USED A COMPROMISE BETWEEN MAV AND ETA MOS GUIDANCE. AVIATION... FEW-SCT CU AND SCT-BKN250 ACROSS SOUTHERN PORTIONS OF TWB232 AND WESTERN PORTIONS OF TWB236 THROUGH EARLY EVENING. ISOLATED TSTMS POSSIBLE IN SOUTHERN PORTION OF TWB232. REST OF REGION CAN EXPECT SKC-SCT250 OVER THE NEXT 24 HOURS WITH LITTLE TO NO CU DEVELOPMENT. N TO NE WINDS AT 5 TO 12KTS THIS AFTERNOON WILL BECOME LIGHT AFTER 01Z...THEN PICK BACK UP FROM THE SOUTHEAST TO 5 TO 12KTS AFTER 13Z SATURDAY. MAY SEE LIGHT FOG AT KCGI BETWEEN 08Z AND 13Z. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM...SMITH AVIATION...GM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1006 AM CDT SAT AUG 18 2007 .UPDATE...SATELLITE AND RADAR THIS MORNING HAS SHOWN CONVECTION FIRING ALONG THE SE TX/SW LA COAST AND SPREADING INLAND OVER W OF THE LCH AREA. THE SHOWERS AND STORMS WELL ALIGNED WELL WITH THE SURFACE THETA E RIDGE AS DEPICTED BY THE 12Z RUC AND WITH GOES SOUNDER PRECIP WATER. 12Z KLCH AND KCRP SOUNDINGS ARE WELL OVER 2 INCHES IN PRECIP WATER...BUT KLIX SOUNDING WAS RELATIVELY LOW WITH PWATS AROUND 1.70. CURRENT FORECAST LOOKS GOOD FOR NOW...POPS TO REMAIN HIGHEST IN SE TX BUT THINK THINK MAY TWEAK POPS DOWNWARD ESPECIALLY OVER SOUTH CENTRAL LA. && .PREV DISCUSSION... /ISSUED 422 AM CDT SAT AUG 18 2007/ SYNOPSIS... TROPICAL DEPRESSION ERIN...LOCATED NEAR MIDLAND TEXAS...WILL DRIFT NORTH...THAN NORTHEAST...REACHING ALTUS OKLAHOMA ON SUNDAY. A DOME OF HIGH PRESSURE...LOCATED ACROSS WESTERN NORTH CAROLINA ..WILL TRAVEL EAST...MOVING OFF THE NORTH CAROLINA COAST ON MONDAY. AN ASSOCIATED BACKDOOR COLD FRONT EXTENDS ANTICYCLONICALLY THROUGH SOUTHERN MISSOURI TO ACROSS NORTHERN GEORGIA TO SOUTH CAROLINA. AT CIRRUS LEVEL...A TUTT LOW...LOCATED ACROSS SOUTH FLORIDA...WILL TRAVEL WEST ACROSS THE MIDDLE GULF OF MEXICO...REACHING BROWNSVILLE TEXAS BY MONDAY EVENING. UPPER-LEVEL DIFLUENCE WILL BE FOUND DOWNSTREAM (OR WESTWARD) OF THE TUTT LOW. SEE THE LATEST ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON HURRICANE DEAN. DISCUSSION... A WARM CONVEYOR BELT AIRSTREAM...ASSOCIATED WITH ERIN...REMAINS IN PLACE ACROSS THE WESTERN UPPER GULF COAST STATES. THE BACKDOOR FRONT IS DUCTING THE INCOMING...SLANTWISE-ASCENDING GULF AIR THROUGH LOUISIANA AND ACROSS SOUTHEAST TEXAS. SHOWERS AND THUNDERSTORMS ARE EXPECTED ONCE AGAIN...AS THE SLANTWISE ASCENDING AIR RELEASES THE RELATIVELY-CONSTANT POTENTIAL INSTABILITY. THE RAIN CHANCES WILL BE GREATEST ACROSS SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA...WHERE THE RICH GULF AIR ASCENDS CYCLONICALLY. OTHERWISE MOSTLY CLOUDY SKIES WITH SLIGHTLY BELOW-NORMAL TEMPERATURES AND SLIGHTLY ABOVE-NORMAL HUMIDITIES CAN BE EXPECTED. THE RAIN CHANCES WILL BE LEAST ACROSS EAST CENTRAL AND SOUTH CENTRAL LOUISIANA...WHERE THE GULF AIR ASCENDS ANTICYCLONICALLY. YOU CAN EXPECT PARTLY CLOUDY SKIES WITH SLIGHTLY ABOVE-NORMAL TEMPERATURES AND NEAR-NORMAL HUMIDITIES. FOR SUNDAY...RAIN CHANCES INCREASE ACROSS EAST CENTRAL AND SOUTH- CENTRAL LOUISIANA WITH THE APPROACH OF THE TUTT LOW. BOTH THE TEMPERATURES AND HUMIDITIES WILL BE RUNNING ABOUT SEASONABLE THROUGHOUT THE ENTIRE FORECAST AREA. MARINE... SOUTHEASTERLY SWELLS...ASSOCIATED WITH HURRICANE DEAN...ARE EXPECTED TO REACH THE COASTAL WATERS BY WEDNESDAY MORNING. A POSSIBLE TIDAL PILE-UP MAY CAUSE COASTAL FLOODING. AVIATION... THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL BE GREATEST ACROSS SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA. && .PRELIMINARY POINT TEMPS/POPS... KLCH 90 74 90 74 / 40 10 50 10 KBPT 90 76 90 75 / 50 10 50 10 KAEX 94 72 92 71 / 30 10 40 10 KLFT 93 75 89 73 / 30 10 50 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ AP la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 713 PM EDT FRI AUG 17 2007 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION TONIGHT INTO SATURDAY. THIS SYSTEM WILL RESULT IN SCATTERED SHOWERS LATER TONIGHT THROUGH SATURDAY. HIGH PRESSURE WILL THEN START TO BUILD ACROSS THE REGION SATURDAY NIGHT THROUGH EARLY NEXT WEEK WITH UNSEASONABLY COOL WEATHER EXPECTED. && .NEAR TERM /THROUGH SATURDAY/... LATEST RADAR AND LTG DATA INDICATING SOME TSTMS MOVING INTO CNTL MAINE AND PUSHING NEWD. IR SATL IMAGERY SHOWING COOLING TOP AS WELL. THIS ACTIVITY IS MOVING INTO A MORE STABLE ENVIRONMENT ESP ACROSS NRN MAINE. FURTHER S ACROSS DOWNEAST AREAS...ACTIVITY LOOKS LIKE IT WILL HOLD TOGETHER. DECIDED TO ADD MENTION OF THE TSTMS INTO TONIGHT AND EARLY SATURDAY MORNING BASED ON LATEST RUC & NAM SOUNDINGS WHICH APPEAR TO BE IN LINE W/WHAT IS HAPPENING ATTM. ADDED GUSTY WINDS TO CNTL AND DOWNEAST AREAS. SMALL HAIL IS ALSO POSSIBLE GIVEN WBZ DOWN AROUND 7500`. WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL DISTURBANCE CURRENTLY ACROSS ONTARIO AND QUEBEC PROVINCE. THIS FEATURE WILL BE THE WEATHER MAKER ACROSS THE FORECAST AREA LATER TONIGHT AND INTO SATURDAY. EXPECT SCATTERED SHOWERS TO AFFECT THE FORECAST AREA LATER TONIGHT AND INTO SATURDAY AS THIS DISTURBANCE MOVES ACROSS. HAVE GENERALLY USED A BLEND OF THE GFS/NAM12. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... COOL BUT MAINLY DRY WEATHER THROUGH THIS PERIOD. NW FLOW WITH UPPER LEVEL TROF TO PERSIST. STAYED CLOSE TO GFS & GRIDDED MOS SOLUTION. EXPECT P/C SKIES SAT NIGHT AND SUNDAY OVER NRN AREAS WITH DIURNAL INSTABILITY. OVER SRN AREAS DOWN SLOPING SHOULD RESULT IN CLR TO P/C SKIES. RIDGING TO SLOWLY BUILD IN SUNDAY NIGHT AND MONDAY. COOLEST AIRMASS OF THE LATE SUMMER SEASON TO YIELD LOWS IN THE 30S OVER NW AREAS...WILL HAVE TO WATCH FOR THE POSSIBILITY OF SCT FROST MONDAY MORNING. EXPECT AREAS OF VALLEY FOG AND RADIATION FOG SUNDAY NIGHT AS WELL. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER PATTERN FOR MONDAY NIGHT INTO TUESDAY KEEPING THINGS DRY AND COOL ACROSS THE REGION. NEXT GOOD CHANCE FOR PRECIPITATION WILL BE WITH THE ARRIVAL OF A WARM FRONTAL BOUNDARY FROM THE WEST. OPERATIONAL GFS HAS HAD A TENDENCY TO BE FASTER WITH THE PROGRESSION OF THIS SYSTEM IN RELATION TO THE SLOWER ECMWF/GFS ENSEMBLE/CANADIAN RUNS...WITH SUCCESSIVE GFS RUNS TRENDING MORE TOWARDS THIS SLOWER SOLUTION. PREFERRED THEREFORE THIS TIMING OF THE FRONT WHICH BRINGS IT CLOSE TO THE AREA BY LATE WEDNESDAY NIGHT/THURSDAY MORNING. HPC GUIDANCE REFLECTED THIS WELL AND THEREFORE ONLY MADE MINOR CHANGES TO ITS GRIDS. A CHANCE FOR SHOWERS WILL THEN LINGER THROUGH FRIDAY AS COLD FRONT THEN CROSSES THE REGION. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... GENERALLY VFR VSBY/CIGS TONIGHT THROUGH SATURDAY. HOWEVER THERE MAY BE SOME BRIEF PERIODS OF MVFR CIGS/VSBYS IN ANY SCATTERED SHOWERS TONIGHT THROUGH SATURDAY. OTHERWISE MAINLY VFR CONDITIONS ARE EXPECTED SUNDAY THROUGH WEDNESDAY. && .MARINE... NO HEADLINES EXPECT THROUGH THE FORECAST PERIOD. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...DUDA/HEWITT SHORT TERM...LULOFS LONG TERM...WEITLICH AVIATION...DUDA/HEWITT MARINE...DUDA/HEWITT/LULOFS me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1041 PM EDT SAT AUG 18 2007 .UPDATE...AS THE RADAR HAS BEEN SHOWING THIS EVENING, THE RAIN SHOWERS HAVE BEEN MOVING TO THE SOUTH AND EAST. TRIMMED THE RAIN FARTHER SOUTH AND MAY HAVE TO UPDATE AGAIN AS THE RAIN LOOKING UPSTREAM ARE SHOWING WIDELY SCATTERED SHOWERS AND SPRINKLES. OTHERWISE, THE TEMPERATURES LOOKS GOOD WITH THE CLOUD COVER THAT IS OVER THE REGION AND THE HIGH PRESSURE THAT IS KEEPING THE WINDS DOWN TONIGHT. LUTZ && .AVIATION...ISSUED 802 PM RAIN IS MAINLY SOUTH OF M-55 SO FOR THE SHORT TERM, TVC WILL STAY OUT OF THE RAIN, THOUGH SPRINKLES AREN`T OUT OF THE QUESTION. APN AND PLN ARE TOO FAR NORTH AT THIS POINT AS THE RAIN LOOKS TO BE FOLLOWING THE GFS CONFIGURATION TO THE QPF. MBL IS SHOWING 10SM, AND REPORTED 0.01 LAST HOUR SO FOR THE BALANCE OF THE NIGHT THE GOING FORECAST LOOKS GOOD. THIS LOOKS TO BE THINKING IN THE PUBLIC FORECAST AS WELL THROUGH SUNDAY EVENING SO WILL KEEP THE BULK OF THE FORECAST DRY WITH SHOWERS OR SPRINKLES NEAR TVC. THE WIND LOOKS TO REMAIN UNDER 10 KNTS FOR SUNDAY AS WELL. LUTZ && .PREV DISCUSSION...ISSUED 328 PM ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 948 PM EDT SAT AUG 18 2007 .UPDATE... LATEST RADAR LOOP SHOWS BANDS OF SHOWERS STRETCHING FROM CENTRAL/SOUTHERN MN INTO SOUTHERN LOWER MICHIGAN BECOMING SMALLER WIDTH WISE...NOW MOSTLY CONCENTRATED ALONG AND SOUTH OF I-94. HOWEVER...THIS CONCENTRATED ZONE NOW CONSISTS OF HEAVIER SHOWERS AND THUNDERSTORMS...LIKELY DUE TO INCREASING SOUTHWEST WINDS AT 850MB NOTED ON THE BLUE RIVER WISCONSIN PROFILER (NOW 30-35KT) IMPINGING ON THE NEARLY STATIONARY FRONTAL BOUNDARY. PLENTY OF HEAT AND MOISTURE EXISTS SOUTH OF THE FRONTAL BOUNDARY TO SUSTAIN THE CONVECTION...ESPECIALLY WITH THE REMNANTS OF TROPICAL STORM ERIN BEING ADVECTED NORTHWARD WITHIN THE LOW LEVEL JET. CLOSER TO HOME...EXCEPT FOR A FEW OF THE SHOWERS BRUSHING THE MENOMINEE AREA BETWEEN 20-24Z...THE CWA REMAINS DRY WITH MID AND HIGH CLOUDS CROSSING. THESE CLOUDS ARE ALSO ASSOCIATED WITH THE MID-LEVEL FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING AIDING IN THE SHOWERS FARTHER TO THE SW. WITH THE SHOWERS DRYING UP FROM CENTRAL MN INTO EAST-CENTRAL WI...THERE IS CONCERN THAT PCPN MAY BE ENTIRELY DONE NOW MENOMINEE COUNTY (THE ONLY PLACE WITH -SHRA MENTION IN THE CWA). TWO THINGS COULD BE OCCURRING THAT IS CAUSING THE DIMINISHING OF SHOWERS: INCREASED CONVECTIVE ACTIVITY IN SOUTHERN MN AND SOUTHERN WI IS INHIBITING MOISTURE TRANSPORT TOWARDS NORTHERN WI AND/OR THE COMBINATION OF THE MID-LEVEL FRONTOGENETICAL AND UPPER LEVEL JET CIRCULATIONS ARE DRIVING DRIER AIR SOUTHWESTWARD. 20Z TAMDAR SOUNDING FROM CHIPPEWA COUNTY AIRPORT SHOWED A LOT OF DRY AIR IN THE 600-800MB LAYER (DEWPOINT DEPRESSIONS OF 20C OR MORE). GIVEN THAT THE UPPER LEVEL FLOW IS PROGGED TO REMAIN CONFLUENT WITH HEIGHTS RISING INTO SOUTH CENTRAL CANADA...AND TROUGHING IN NEW ENGLAND...THINK IT WILL BE HARD TO GET THE SHOWERS NORTHWARD. THE 18Z GFS CONCURS WITH THIS IDEA...AND THUS HAVE DECIDED TO REMOVE SHOWERS FROM THE FCST. GOING TEMPS SEEM REASONABLE...THOUGH SINCE SKIES REMAIN CLEAR OUT EAST AND LOW PRECIPITABLE WATER THERE...HAVE DECIDED TO DROP TEMPS A FEW MORE DEGREES. PRECIPITABLE WATER VALUES ARE ABOUT 0.25 INCH HIGHER THAN LAST NIGHT...SUGGESTING LOWS SHOULD NOT GET AS COLD. && .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS ARE EXPECTED TO PERSIST DUE TO LOW LEVEL DRY AIR HOLDING ON FROM HIGH PRESSURE JUST TO THE NE OF LAKE SUPERIOR. LOOK FOR A GENERAL EAST WIND...WITH INCREASING SPEED ON SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...JLB LONG TERM...JLL AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 802 PM EDT SAT AUG 18 2007 .AVIATION...RAIN IS MAINLY SOUTH OF M-55 SO FOR THE SHORT TERM, TVC WILL STAY OUT OF THE RAIN, THOUGH SPRINKLES AREN`T OUT OF THE QUESTION. APN AND PLN ARE TOO FAR NORTH AT THIS POINT AS THE RAIN LOOKS TO BE FOLLOWING THE GFS CONFIGURATION TO THE QPF. MBL IS SHOWING 10SM, AND REPORTED 0.01 LAST HOUR SO FOR THE BALANCE OF THE NIGHT THE GOING FORECAST LOOKS GOOD. THIS LOOKS TO BE THINKING IN THE PUBLIC FORECAST AS WELL THROUGH SUNDAY EVENING SO WILL KEEP THE BULK OF THE FORECAST DRY WITH SHOWERS OR SPRINKLES NEAR TVC. THE WIND LOOKS TO REMAIN UNDER 10 KNTS FOR SUNDAY AS WELL. LUTZ && .PREV DISCUSSION...ISSUED 328 PM ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 716 PM EDT SAT AUG 18 2007 UPDATED AVIATION SECTION FOR 00Z TAF ISSUANCE .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS ARE EXPECTED TO PERSIST DUE TO LOW LEVEL DRY AIR HOLDING ON FROM HIGH PRESSURE JUST TO THE NE OF LAKE SUPERIOR. LOOK FOR A GENERAL EAST WIND...WITH INCREASING SPEED ON SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JLB LONG TERM...JLL AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EDT SAT AUG 18 2007 .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... LIGHT WINDS AND VFR CONDITIONS TO PERSIST AS HIGH PRESSURE CONTINUES TO DOMINATE THE REGION. SE TO E WINDS WILL DEVELOP TONIGHT AND INCREASE SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JLB LONG TERM...JLL MARINE/AVIATION...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 328 PM EDT SAT AUG 18 2007 .DISCUSSION...ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 124 AM EDT SAT AUG 18 2007 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A TROUGH OFF THE PAC NW COAST...A RIDGE FROM THE SRN CONUS TO ALBERTA/SASK...AND A TROUGH OVER ERN CANADA RESULTING IN NW FLOW THROUGH THE UPPER GREAT LAKES. AT THE SFC...HIGH PRES FROM MANITOBA AND WRN ONTARIO WAS BUILDING INTO THE UPPER MS VALLEY AND WRN GREAT LAKES BRINGING GUSTY (15-30 MPH) N TO NW WINDS THROUGH LAKE SUPERIOR INTO UPPER MI. VIS LOOP SHOWED CLEARING OVER MOST OF LAKE SUPERIOR BUT ABUNDANT DIURNALLY ENHANCED STRATOCU OVER NRN UPPER MI AND N OF LAKE SUPERIOR AS CAA HAS BROUGHT 850 MB TEMPS TO NEAR 2C. SFC DEWPOINTS OVER THE AREA WERE GENERALLY IN THE UPPER 30S TO LOWER 40S F. && .SHORT TERM (TONIGHT AND SAT)... THE MDLS SUGGEST THAT THE GRADIENT WILL SLACKEN QUICKLY THIS EVENING ALLOWING WINDS TO DECOUPLE AFTER MIDNIGHT. WITH ONLY LIGHT WINDS OFF OF LAKE SUPERIOR AND DECENT SUBSIDENCE OVER THE AREA SKIES SHOULD CLEAR OUT OVER THE AREA...ESPECIALLY WEST. WITH VERY FAVORABLE RADIATIONAL COOLING CONDITIONS...MIN READINGS SHOULD DROP INTO THE MID TO UPPER 30S INLAND CENTRAL AND WEST. SO...SOME PATCHY FROST MAY BE POSSIBLE IN SHELTERED LOW-LYING AREAS. WITH 850 MB TEMPS STILL IN THE 4C-6C RANGE EARLY IN THE DAY...SCT SC WILL AGAIN DEVELOP BY LATE MORNING. SOME INCREASE IN MID/HIGH CLOUDS IS ALSO EXPECTED AS 315K-320K ISENTROPIC LIFT DEVELOPS AHEAD OF A WARM FRONT OVER MN. TEMPS SHOULD REBOUND IN MID 60S N TO AROUND 70 SOUTH AS WEAK WAA PUSHES H8 TEMPS INTO THE 5C-8C RANGE. .LONG TERM (SAT NIGHT THRU FRI)... SAT NIGHT/SUN...WARM FRONT DEVELOPING FROM THE CNTRL PLAINS INTO THE OHIO VALLEY SAT NIGHT/SUN WILL BECOME VERY ACTIVE WITH SHRA/TSRA. NAM IS AT THE NRN EXTREME SHOWING SFC WARM FRONT SETTING UP ACROSS SRN WI. GFS/UKMET/ECMWF CONSENSUS IS FOR FRONT TO RUN FROM SD/NEBRASKA TO INDIANA...LIKELY JUST A BIT TOO FAR S TO SUPPORT SHRA CHANCES IN UPPER MI. THERE HAS BEEN A NOTABLE TREND IN THE LAST 4 GFS RUNS FOR FRONT TO BE FARTHER S...AND THIS MAKES SENSE WITH TROF HANGING ON OVER ERN CANADA WHICH WOULD MAINTAIN MORE OF A NW FLOW INTO THE UPPER LAKES. IT ALSO SUPPORTS MORE PERSISTENT SFC HIGH PRES JUST TO THE NE OF LAKE SUPERIOR TO PROVIDE A FEED OF DRY LOW-LEVEL AIR FROM THE E. GIVEN THE GFS/UKMET/ECMWF CONSENSUS...GFS TREND FARTHER S AND LIKELIHOOD THAT CONVECTIVE COMPLEXES WILL REINFORCE AND MAINTAIN SFC FRONTAL POSITION FARTHER S...PLAN TO CONTINUE WITH A DRY FCST SAT NIGHT THRU SUN NIGHT. WILL NEED TO WATCH THE FAR SRN FCST AREA THOUGH FOR POSSIBLE LATER ADDITION OF POPS GIVEN CLOSE PROXIMITY OF PCPN N OF WARM FRONT. AS FOR TEMPS...WILL STRONGLY LEAN TOWARD THE COOLER GFS GUIDANCE FOR SAT NIGHT WITH THICKER CLOUDS REMAINING SW OF HERE. THE WARMER GFS GUIDANCE LOOKS ACCEPTABLE FOR SUN...AGAIN WITH THICKER CLOUDS REMAINING SW AND S OF HERE. FCST BECOMES MORE UNCERTAIN MON AS MODEL DIFFERENCES ARISE WITH REGARD TO ENERGY EJECTING E FROM TROF MOVING INLAND FROM THE W COAST ON SUN. GFS IS INSISTENT IN PUSHING ENERGY RAPIDLY E ACROSS THE PLAINS INTO THE GREAT LAKES WHICH RESULTS IN WARM FRONT/SFC TROF CROSSING UPPER MI LATE MON NIGHT/EARLY TUE. UKMET SUPPORTS THE ECMWF WITH SHARPER RIDGING BEING MAINTAINED DOWNSTREAM OF TROF MOVING INLAND FROM THE W COAST...BUT 12Z ECMWF IS BEGINNING TO SHOW A TREND TOWARD THE GFS. WILL THUS HALF STEP TOWARD THE GFS AND SIMPLY BUMP UP TIMING OF SHRA/TSRA CHANCES TO MON NIGHT/EARLY TUE. MAY NEED TO BRING POPS INTO THE FCST AREA DURING THE DAY MON IF MODELS MOVE INTO AGREEMENT ON THIS INCREASINGLY FASTER TIMING. TUE-FRI...GFS/CANADIAN/UKMET/ECMWF SHOWED RATHER SIGNIFICANT DIFFERENCES DURING THIS PERIOD REGARDING TIMING OF SYSTEMS ACROSS THE UPPER GREAT LAKES REGION...BUT TODAYS 12Z RUNS HAVE MOVED INTO MUCH BETTER AGREEMENT. SFC WARM FRONT/TROF DISCUSSED IN PREVIOUS PARAGRAPH SHOULD SWEEP ACROSS THE AREA TUE PER CONSENSUS OF MEDIUM RANGE MODELS...AND WILL THUS MAINTAIN CHC POPS FOR TUE. AGREEEMENT HAS IMPROVED WITH TIMING OF COLD FRONT ASSOCIATED WITH MAIN TROF SHIFTING ACROSS SCNTRL CANADA TOWARD HUDSON BAY MIDWEEK. FROPA SHOULD OCCUR DURING THE LATE AFTN/EVENING HRS. WHILE THERE SHOULD BE A BREAK IN SHRA CHANCES TUE NIGHT/EARLY WED...CONFIDENCE IN TIMING FEATURES IS NOT SUFFICIENT TO EXPLICITLY SHOW THAT IN THE GRIDS RIGHT NOW. OPTED TO DRY THINGS OUT FOR THU AND KEPT FCST DRY FOR THE NEW DAY 7 (FRI) EVEN THOUGH RECENT GFS RUNS SUGGEST ANOTHER SHORTWAVE HEADING TOWARD THE GREAT LAKES. SO FOR THIS 7 DAY FCST PERIOD...IF WARM FRONT/TROF IS NOT ACTIVE WHEN IT PASSES TUE... WIDESPREAD/SIGNIFICANT RAINFALL IS NOT LIKELY AS FORCING WITH COLD FROPA WED LOOKS WEAK DUE TO LIMITED HEIGHT FALLS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LIGHT WINDS AND VFR CONDITIONS TO PREVAIL AS HIGH PRESSSURE CONTINUES TO BUILD INTO THE REGION. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... CAA AND A TIGHT GRADIENT HAVE KEPT WINDS IN THE 15-25 KT RANGE OVER THE ERN LAKE WITH GUSTS TO 30 KT AND PUSHED WAVES INTO THE 7 TO 10 FOOT RANGE. WINDS WILL GRADUALLY DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION FROM THE NW. E TO SE WINDS WILL INCREASE FROM SUN INTO MON AS LOW PRES DEVELOPS IN THE PLAINS AND MOVES INTO THE UPPER MISSISSIPPI VALLEY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JLB LONG TERM...ROLFSON MARINE...JLB AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1030 AM EDT FRI AUG 17 2007 .UPDATE...ONGOING FORECAST STILL APPEARS ON TARGET...WITH ONLY MINOR CHANGES ANTICIPATED. MAIN FORECAST CONCERNS INCLUDE LAKE EFFECT RAIN CHANCES...ALONG WITH FIRE WEATHER DANGER. CAA PATTERN CONTINUES...WITH 850 MB TEMPS POISED TO BOTTOM OUT +2-3C ACROSS E UPPER AND AROUND +4C AROUND FAR NRN LOWER EARLY THIS AFTERNOON. COUPLED WITH LAKE TEMPS OF +18-22C...LAKE CLOUDS HAVE DEVELOPED AS EXPECTED -- WITH EVEN A FEW LIGHT LAKE INDUCED RAIN SHOWERS OVER ERN UPPER. SURFACE HIGH WILL BUILD INTO THE WRN GREAT LAKES...AS 500 MB SUPPORT/TROUGH SHIFTS E OF REGION THIS AFTERNOON. THIS WILL CAUSE LOW LEVEL FLOW TO BECOME INCREASINGLY ANTI-CYCLONIC AND FOR 850-700 MB TEMPS TO MODERATE SLIGHTLY AFTER 18Z (WITH STRENGTHENING MID LEVEL INVERSION NOTED ON MODEL SOUNDINGS AFTER 16-18Z). AS A RESULT...EXPECT SHOWER CHANCES ACROSS THE FAR N TO DWINDLE DURING THE AFTERNOON PER CURRENT FORECAST. WITH MIXING OVER LAND LIKELY TO DOMINATE...MAINLY SUNNY SKIES MAY PERSIST ALONG IMMEDIATE LAKE MI SHORELINE S OF LELAND THIS AFTERNOON (IN SPITE OF OVER-WATER INSTABILITY). OTHERWISE...DIURNAL CLOUDS WILL CONTINUE TO DEVELOP DURING THE LATE MORNING WITH GENERALLY PARTLY SUNNY SKIES EXPECTED. MARINE CONCERNS. AS PREVIOUSLY DISCUSSED (IN EARLIER AFD) WATERSPOUT CHANCES NOT GREAT...BUT WILL CONTINUE TO HIGHLIGHT RISK ACROSS E UPPER AND NE LOWER COASTAL WATERS INTO EARLY AFTERNOON. SMALL CRAFT ADVISORIES WILL ALSO CONTINUE. FIRE WEATHER CONCERNS CONTINUE. SURFACE TEMPS HAVE QUICKLY RISEN THIS MORNING...SUGGESTING WE MAY NEED TO NUDGE HIGHS UPWARD SLIGHTLY. HOWEVER...SHALLOWNESS OF SURFACE-BASED INVERSION ON GRB SOUNDING...TOGETHER WITH PROGGED 850 MB TEMPS...SUGGESTS THAT TEMPS WILL LIKELY LEVEL OUT EARLY THIS AFTERNOON WITHOUT GETTING OUT OF HAND -- I.E. HIGHS IN THE 60S FAR N AND LOWER-MID 70S SOUTH. 900-800 MB WINDS AND STRONG VERTICAL MIXING WILL SUPPORT OCCASIONAL GUSTS OF 20-30 MPH. WILL NEED TO KEEP CLOSE EYE ON DEW POINTS. MOISTURE CONTRIBUTION FROM LAKE MAY KEEP RH/S SLIGHTLY MORE ELEVATED...WITH RH/S REMAINING GENERALLY ABOVE 25-30 PCT RANGE. IT/LL BE CLOSE...AND WE/LL CONTINUE TO MONITOR. IN THE MEANTIME...WILL CONTINUE TO HIGHLIGHT ELEVATED FIRE DANGER IN HAZARDOUS WEATHER OUTLOOK. SMITH && .PREV DISCUSSION...ISSUED 508 AM SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING UPPER TROUGH ACROSS THE NE CONUS WITH WELL DEFINED SHORTWAVE TROUGHS EMBEDDED WITHIN. THE MAIN SHORTWAVE AND ASSOCIATED SFC TROUGH/COLDER AIR PUNCH AND DEEPER H8-H7 MOISTURE REMAINS POISED ACROSS SOUTHERN ONTARIO...A BIT SLOWER THAN ORIGINALLY ANTICIPATED. NEVERTHELESS... WE HAVE HAD SOME SCT070-090 CLOUD TRYING TO DEVELOP ACROSS EASTERN LAKE SUPERIOR...WHERE H8 TEMPS HAVE DROPPED INTO THE +7C RANGE. SKIES WERE OTHERWISE CLEAR WITH A WIDE RANGE IN SFC TEMPERATURE. OVER THE WATER...READINGS WERE IN THE LOWER 60S...WHILE INTERIOR LOW LYING AREAS WHERE WINDS HAVE DECOUPLED...WERE IN THE LOWER 40S. FORECAST CONCERNS...SYNOPTIC/LAKE EFFECT RAIN SHOWERS CHANCES TODAY ALONG WITH WATERSPOUT CHANCE AND WINDS WITH A NEARSHORE EMPHASIS. THEN THE FOCUS TURNS TO CHANCES FOR RAIN AGAIN WITH WARM FRONT ARRIVING OVER THE WEEKEND. TODAY...OVERALL...OUTSIDE OF THE GFS...MODELS STILL DO NOT SEEM TO BE HANDLING THE STRENGTH OF THE SHORTWAVE TROUGH IN NC ONTARIO VERY WELL...EVEN THE RUC. THIS WELL DEFINED FEATURE IS STILL EXPECTED TO DROP SE AND THROUGH SE ONTARIO AND INTO NEW YORK STATE TONIGHT. WITH THIS FEATURE...A SFC TROUGH WILL DROP THROUGH EASTERN UPPER BY MIDDAY AND GRAZE THE NE LOWER NEARSHORE AREAS EARLY THIS AFTERNOON. ALONG WITH THIS SFC TROUGH...ARRIVING WILL BE A NARROW BAND OF >70% H8-H7 MOISTURE...AND COLD ADVECTION THROUGH 500MB. H8 TEMPS WILL DROP TO AROUND +2C IN WHITEFISH BAY...TO +5C IN THE FAR SRN CWA. THIS WILL RESULT IN DELTA T`S AROUND 17C-18C.THIS OVER LAKE INSTABILITY IN CONJUNCTION WITH BAND OF DEEPER MOISTURE AND LIFT FROM SFC TROUGH AND CORRIDOR OF WEAK TO MODEST H8-H5 -DIVQ SHOULD BE ABLE TO PROVIDE ISOLATED TO SCATTERED LIGHT RAIN SHOWERS AS FAR SOUTH AS M-68 IN NRN LOWER. THE ADDED LAKE INFLUENCE COULD RESULT IN A BETTER CHANCE IMMEDIATELY DOWNWIND OF WHITEFISH BAY AND PERHAPS LAKE MICHIGAN/NRN LAKE HURON. THROWN IN LCL`S AROUND 3.5KFT WITH AN EXPECTED LOBE OF H8 VORTICITY...AND ALL OF THE ABOVE ATMOSPHERIC PARAMETERS...AND WE HAVE A SLIGHT CHANCE OF WATERSPOUTS TODAY FOR WHITEFISH BAY AND NRN LAKE HURON. THINGS GOING AGAINST WATERSPOUTS ARE THE MARGINAL RH AND THE WARMING SEEN ABOVE 750MB THIS AFTERNOON...PLUS THE RELATIVELY STRONG H8 WIND AT 30KTS. THE LATTER WILL ALSO LEAD TO RATHER GUSTY CONDITIONS EXPECTED TO DEVELOP TODAY OVER THE LAKES. HAVE THROWN EVERYONE INTO A SMALL CRAFT ADVISORY FOR TODAY...WITH A FEW GALE GUSTS POSSIBLE IN COASTAL CONVERGENCE REGIMES INTO THIS EVENING. AFTER COORDINATION WITH SURROUNDING OFFICES AND ENVIRONMENT CANADA...DECIDED AGAINST THE GALES...AND RATHER IN FAVOR OF THE CHANCE FOR WATERSPOUTS. MODELS DO SUGGEST THAT DRIER AIR WILL FILTER IN BEHIND THE SFC TROUGH...WHILE INVERSION HEIGHTS SUBSIDE WITH WARMING ALOFT. IF THE LAKE EFFECT RAIN SHOWERS COULD DEVELOP...WOULD NOT BE SURPRISED TO SEE THEM PERSIST INTO THE AFTERNOON HOURS...EARLY AFTERNOON. TONIGHT...CONTINUED WARMING ALOFT...SUBSIDING INVERSION HEIGHTS AND DRY AIR (< 25%) ARRIVING THROUGH THE EVENING...LEADS TO A GRADUAL CLEARING FOR THE NIGHT. BUT AGAIN...MAYBE CLOUDS COULD HANG ON A BIT LONGER INTO THE EVENING AND DAY CREW WILL NEED TO ASSESS THIS (NOT UNCOMMON FOR LAKE EFFECT TO HOLD OUT LONGER THAN ANTICIPATED). FOR NOW...WILL RIDE CURRENT FORECAST OF MOSTLY CLEAR. WINDS WILL SUBSIDE AS A SFC HIGH DROPS IN RIGHT OVER THE TOP OF NRN MICHIGAN. WILL END MARINE HEADLINES AT 11PM...AND COULD EASILY SEE LOWS DIPPING INTO THE UPPER 30S AND LOWER 40S BY DAYBREAK. SATURDAY...AIR MASS WILL BE QUITE DRY WITH H8-H5 MOISTURE AT 25% OR LESS. SFC HIGH WILL DRIFT EAST LATE IN THE DAY...WHILE MODELS CONTINUE TO INSIST THAT HIGHER LEVEL MOISTURE WILL TRY AND SQUEAK INTO THE GTV BAY REGION BY LATE AFTERNOON...WELL AHEAD OF A WARM FRONT THAT IS EXPECTED TO BE WELL SOUTH OF US...ACROSS IOWA/NRN IL. CAN SEE NO CHANCE FOR PRECIPITATION. SATURDAY NIGHT ONWARD...THE SFC HIGH WILL BE STUBBORN TO LEAVE US...BUT A SLOW DRIFT EASTWARD THROUGH MONDAY IS ANTICIPATED. THE QUESTION IS...HOW LONG WILL IT BE BEFORE...OR WILL THE MOISTURE EVER BECOME DEEP ENOUGH WITH WAA...TO DEVELOP A CHANCE OF RAIN SHOWERS FOR OUR SRN ZONES...SOUTH OF M-72. MID LEVEL HEIGHTS SLOWLY RISE THROUGH THE PERIOD...SO I CAN BELIEVE A SLOW PROGRESSION NORTH THROUGH TIME WITH THE WARM FRONT. HOWEVER...BASED ON THE LOW LEVEL HIGH PRESSURE AXIS OVER THE GULF...AND THE FACT THAT THE MODELS MAY BE RIDDLED WITH CONVECTIVE FEEDBACK...HAVE QUESTIONS ABOUT THE NORTHWARD EXTENT OF MODEL FORECAST PRECIPITATION BEGINNING SATURDAY NIGHT. AGREE WITH PREVIOUS FORECASTER THOUGHTS...AND WILL RIDE CURRENT FORECAST OF CHANCE FOR RAIN SHOWERS THROUGH MONDAY NIGHT SOUTH OF M-72. WOULD NOT BE SURPRISED AT ALL TO SEE THESE CHANCES REMOVED WITH FUTURE FORECAST ISSUANCES. FOR NOW...JUST MADE SOME COSMETIC CHANGES TO BLEND IN WITH SURROUNDING OFFICES. SMD && .AVIATION...ISSUED 730 AM VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. HOWEVER...SFC COOL FRONT WILL SWING ACROSS NRN MICHIGAN TODAY BRINGING A GUSTY NORTHWEST WIND TO ALL TAF SITES. IN ADDITION...COOL AIR ALOFT WILL COMBINE WITH RELATIVELY WARMER WATERS OF THE GREAT LAKES...RESULTING IN ISOLATED LIGHT RAIN SHOWERS FOR PLN/APN BETWEEN 14Z AND 19Z. EXPECT THE DEVELOPMENT OF BKN CUMULUS AROUND MID MORNING WITH CIGS AOA 5KFT. THESE CLOUDS ARE EXPECTED TO DIMINISH BY EARLY THIS EVENING...LEADING TO MAINLY CLEAR SKIES OVERNIGHT. HOWEVER...SCT CU OFF THE LAKES MAY CONTINUE TO PERIODICALLY AFFECT ALL TAF SITES. THE GUSTY WINDS WILL TAPER OFF TO NEAR CALM OVERNIGHT AS SFC HIGH PRESSURE WORKS IN OVER THE TOP OF NRN MICHIGAN. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 730 AM EDT FRI AUG 17 2007 .AVIATION...VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. HOWEVER...SFC COOL FRONT WILL SWING ACROSS NRN MICHIGAN TODAY BRINGING A GUSTY NORTHWEST WIND TO ALL TAF SITES. IN ADDITION...COOL AIR ALOFT WILL COMBINE WITH RELATIVELY WARMER WATERS OF THE GREAT LAKES...RESULTING IN ISOLATED LIGHT RAIN SHOWERS FOR PLN/APN BETWEEN 14Z AND 19Z. EXPECT THE DEVELOPMENT OF BKN CUMULUS AROUND MID MORNING WITH CIGS AOA 5KFT. THESE CLOUDS ARE EXPECTED TO DIMINISH BY EARLY THIS EVENING...LEADING TO MAINLY CLEAR SKIES OVERNIGHT. HOWEVER...SCT CU OFF THE LAKES MAY CONTINUE TO PERIODICALLY AFFECT ALL TAF SITES. THE GUSTY WINDS WILL TAPER OFF TO NEAR CALM OVERNIGHT AS SFC HIGH PRESSURE WORKS IN OVER THE TOP OF NRN MICHIGAN. SMD && .DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING UPPER TROUGH ACROSS THE NE CONUS WITH WELL DEFINED SHORTWAVE TROUGHS EMBEDDED WITHIN. THE MAIN SHORTWAVE AND ASSOCIATED SFC TROUGH/COLDER AIR PUNCH AND DEEPER H8-H7 MOISTURE REMAINS POISED ACROSS SOUTHERN ONTARIO...A BIT SLOWER THAN ORIGINALLY ANTICIPATED. NEVERTHELESS... WE HAVE HAD SOME SCT070-090 CLOUD TRYING TO DEVELOP ACROSS EASTERN LAKE SUPERIOR...WHERE H8 TEMPS HAVE DROPPED INTO THE +7C RANGE. SKIES WERE OTHERWISE CLEAR WITH A WIDE RANGE IN SFC TEMPERATURE. OVER THE WATER...READINGS WERE IN THE LOWER 60S...WHILE INTERIOR LOW LYING AREAS WHERE WINDS HAVE DECOUPLED...WERE IN THE LOWER 40S. FORECAST CONCERNS...SYNOPTIC/LAKE EFFECT RAIN SHOWERS CHANCES TODAY ALONG WITH WATERSPOUT CHANCE AND WINDS WITH A NEARSHORE EMPHASIS. THEN THE FOCUS TURNS TO CHANCES FOR RAIN AGAIN WITH WARM FRONT ARRIVING OVER THE WEEKEND. TODAY...OVERALL...OUTSIDE OF THE GFS...MODELS STILL DO NOT SEEM TO BE HANDLING THE STRENGTH OF THE SHORTWAVE TROUGH IN NC ONTARIO VERY WELL...EVEN THE RUC. THIS WELL DEFINED FEATURE IS STILL EXPECTED TO DROP SE AND THROUGH SE ONTARIO AND INTO NEW YORK STATE TONIGHT. WITH THIS FEATURE...A SFC TROUGH WILL DROP THROUGH EASTERN UPPER BY MIDDAY AND GRAZE THE NE LOWER NEARSHORE AREAS EARLY THIS AFTERNOON. ALONG WITH THIS SFC TROUGH...ARRIVING WILL BE A NARROW BAND OF >70% H8-H7 MOISTURE...AND COLD ADVECTION THROUGH 500MB. H8 TEMPS WILL DROP TO AROUND +2C IN WHITEFISH BAY...TO +5C IN THE FAR SRN CWA. THIS WILL RESULT IN DELTA T`S AROUND 17C-18C.THIS OVER LAKE INSTABILITY IN CONJUNCTION WITH BAND OF DEEPER MOISTURE AND LIFT FROM SFC TROUGH AND CORRIDOR OF WEAK TO MODEST H8-H5 -DIVQ SHOULD BE ABLE TO PROVIDE ISOLATED TO SCATTERED LIGHT RAIN SHOWERS AS FAR SOUTH AS M-68 IN NRN LOWER. THE ADDED LAKE INFLUENCE COULD RESULT IN A BETTER CHANCE IMMEDIATELY DOWNWIND OF WHITEFISH BAY AND PERHAPS LAKE MICHIGAN/NRN LAKE HURON. THROWN IN LCL`S AROUND 3.5KFT WITH AN EXPECTED LOBE OF H8 VORTICITY...AND ALL OF THE ABOVE ATMOSPHERIC PARAMETERS...AND WE HAVE A SLIGHT CHANCE OF WATERSPOUTS TODAY FOR WHITEFISH BAY AND NRN LAKE HURON. THINGS GOING AGAINST WATERSPOUTS ARE THE MARGINAL RH AND THE WARMING SEEN ABOVE 750MB THIS AFTERNOON...PLUS THE RELATIVELY STRONG H8 WIND AT 30KTS. THE LATTER WILL ALSO LEAD TO RATHER GUSTY CONDITIONS EXPECTED TO DEVELOP TODAY OVER THE LAKES. HAVE THROWN EVERYONE INTO A SMALL CRAFT ADVISORY FOR TODAY...WITH A FEW GALE GUSTS POSSIBLE IN COASTAL CONVERGENCE REGIMES INTO THIS EVENING. AFTER COORDINATION WITH SURROUNDING OFFICES AND ENVIRONMENT CANADA...DECIDED AGAINST THE GALES...AND RATHER IN FAVOR OF THE CHANCE FOR WATERSPOUTS. MODELS DO SUGGEST THAT DRIER AIR WILL FILTER IN BEHIND THE SFC TROUGH...WHILE INVERSION HEIGHTS SUBSIDE WITH WARMING ALOFT. IF THE LAKE EFFECT RAIN SHOWERS COULD DEVELOP...WOULD NOT BE SURPRISED TO SEE THEM PERSIST INTO THE AFTERNOON HOURS...EARLY AFTERNOON. TONIGHT...CONTINUED WARMING ALOFT...SUBSIDING INVERSION HEIGHTS AND DRY AIR (< 25%) ARRIVING THROUGH THE EVENING...LEADS TO A GRADUAL CLEARING FOR THE NIGHT. BUT AGAIN...MAYBE CLOUDS COULD HANG ON A BIT LONGER INTO THE EVENING AND DAY CREW WILL NEED TO ASSESS THIS (NOT UNCOMMON FOR LAKE EFFECT TO HOLD OUT LONGER THAN ANTICIPATED). FOR NOW...WILL RIDE CURRENT FORECAST OF MOSTLY CLEAR. WINDS WILL SUBSIDE AS A SFC HIGH DROPS IN RIGHT OVER THE TOP OF NRN MICHIGAN. WILL END MARINE HEADLINES AT 11PM...AND COULD EASILY SEE LOWS DIPPING INTO THE UPPER 30S AND LOWER 40S BY DAYBREAK. SATURDAY...AIR MASS WILL BE QUITE DRY WITH H8-H5 MOISTURE AT 25% OR LESS. SFC HIGH WILL DRIFT EAST LATE IN THE DAY...WHILE MODELS CONTINUE TO INSIST THAT HIGHER LEVEL MOISTURE WILL TRY AND SQUEAK INTO THE GTV BAY REGION BY LATE AFTERNOON...WELL AHEAD OF A WARM FRONT THAT IS EXPECTED TO BE WELL SOUTH OF US...ACROSS IOWA/NRN IL. CAN SEE NO CHANCE FOR PRECIPITATION. SATURDAY NIGHT ONWARD...THE SFC HIGH WILL BE STUBBORN TO LEAVE US...BUT A SLOW DRIFT EASTWARD THROUGH MONDAY IS ANTICIPATED. THE QUESTION IS...HOW LONG WILL IT BE BEFORE...OR WILL THE MOISTURE EVER BECOME DEEP ENOUGH WITH WAA...TO DEVELOP A CHANCE OF RAIN SHOWERS FOR OUR SRN ZONES...SOUTH OF M-72. MID LEVEL HEIGHTS SLOWLY RISE THROUGH THE PERIOD...SO I CAN BELIEVE A SLOW PROGRESSION NORTH THROUGH TIME WITH THE WARM FRONT. HOWEVER...BASED ON THE LOW LEVEL HIGH PRESSURE AXIS OVER THE GULF...AND THE FACT THAT THE MODELS MAY BE RIDDLED WITH CONVECTIVE FEEDBACK...HAVE QUESTIONS ABOUT THE NORTHWARD EXTENT OF MODEL FORECAST PRECIPITATION BEGINNING SATURDAY NIGHT. AGREE WITH PREVIOUS FORECASTER THOUGHTS...AND WILL RIDE CURRENT FORECAST OF CHANCE FOR RAIN SHOWERS THROUGH MONDAY NIGHT SOUTH OF M-72. WOULD NOT BE SURPRISED AT ALL TO SEE THESE CHANCES REMOVED WITH FUTURE FORECAST ISSUANCES. FOR NOW...JUST MADE SOME COSMETIC CHANGES TO BLEND IN WITH SURROUNDING OFFICES. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 508 AM EDT FRI AUG 17 2007 .DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING UPPER TROUGH ACROSS THE NE CONUS WITH WELL DEFINED SHORTWAVE TROUGHS EMBEDDED WITHIN. THE MAIN SHORTWAVE AND ASSOCIATED SFC TROUGH/COLDER AIR PUNCH AND DEEPER H8-H7 MOISTURE REMAINS POISED ACROSS SOUTHERN ONTARIO...A BIT SLOWER THAN ORIGINALLY ANTICIPATED. NEVERTHELESS... WE HAVE HAD SOME SCT070-090 CLOUD TRYING TO DEVELOP ACROSS EASTERN LAKE SUPERIOR...WHERE H8 TEMPS HAVE DROPPED INTO THE +7C RANGE. SKIES WERE OTHERWISE CLEAR WITH A WIDE RANGE IN SFC TEMPERATURE. OVER THE WATER...READINGS WERE IN THE LOWER 60S...WHILE INTERIOR LOW LYING AREAS WHERE WINDS HAVE DECOUPLED...WERE IN THE LOWER 40S. FORECAST CONCERNS...SYNOPTIC/LAKE EFFECT RAIN SHOWERS CHANCES TODAY ALONG WITH WATERSPOUT CHANCE AND WINDS WITH A NEARSHORE EMPHASIS. THEN THE FOCUS TURNS TO CHANCES FOR RAIN AGAIN WITH WARM FRONT ARRIVING OVER THE WEEKEND. TODAY...OVERALL...OUTSIDE OF THE GFS...MODELS STILL DO NOT SEEM TO BE HANDLING THE STRENGTH OF THE SHORTWAVE TROUGH IN NC ONTARIO VERY WELL...EVEN THE RUC. THIS WELL DEFINED FEATURE IS STILL EXPECTED TO DROP SE AND THROUGH SE ONTARIO AND INTO NEW YORK STATE TONIGHT. WITH THIS FEATURE...A SFC TROUGH WILL DROP THROUGH EASTERN UPPER BY MIDDAY AND GRAZE THE NE LOWER NEARSHORE AREAS EARLY THIS AFTERNOON. ALONG WITH THIS SFC TROUGH...ARRIVING WILL BE A NARROW BAND OF >70% H8-H7 MOISTURE...AND COLD ADVECTION THROUGH 500MB. H8 TEMPS WILL DROP TO AROUND +2C IN WHITEFISH BAY...TO +5C IN THE FAR SRN CWA. THIS WILL RESULT IN DELTA T`S AROUND 17C-18C.THIS OVER LAKE INSTABILITY IN CONJUNCTION WITH BAND OF DEEPER MOISTURE AND LIFT FROM SFC TROUGH AND CORRIDOR OF WEAK TO MODEST H8-H5 -DIVQ SHOULD BE ABLE TO PROVIDE ISOLATED TO SCATTERED LIGHT RAIN SHOWERS AS FAR SOUTH AS M-68 IN NRN LOWER. THE ADDED LAKE INFLUENCE COULD RESULT IN A BETTER CHANCE IMMEDIATELY DOWNWIND OF WHITEFISH BAY AND PERHAPS LAKE MICHIGAN/NRN LAKE HURON. THROWN IN LCL`S AROUND 3.5KFT WITH AN EXPECTED LOBE OF H8 VORTICITY...AND ALL OF THE ABOVE ATMOSPHERIC PARAMETERS...AND WE HAVE A SLIGHT CHANCE OF WATERSPOUTS TODAY FOR WHITEFISH BAY AND NRN LAKE HURON. THINGS GOING AGAINST WATERSPOUTS ARE THE MARGINAL RH AND THE WARMING SEEN ABOVE 750MB THIS AFTERNOON...PLUS THE RELATIVELY STRONG H8 WIND AT 30KTS. THE LATTER WILL ALSO LEAD TO RATHER GUSTY CONDITIONS EXPECTED TO DEVELOP TODAY OVER THE LAKES. HAVE THROWN EVERYONE INTO A SMALL CRAFT ADVISORY FOR TODAY...WITH A FEW GALE GUSTS POSSIBLE IN COASTAL CONVERGENCE REGIMES INTO THIS EVENING. AFTER COORDINATION WITH SURROUNDING OFFICES AND ENVIRONMENT CANADA...DECIDED AGAINST THE GALES...AND RATHER IN FAVOR OF THE CHANCE FOR WATERSPOUTS. MODELS DO SUGGEST THAT DRIER AIR WILL FILTER IN BEHIND THE SFC TROUGH...WHILE INVERSION HEIGHTS SUBSIDE WITH WARMING ALOFT. IF THE LAKE EFFECT RAIN SHOWERS COULD DEVELOP...WOULD NOT BE SURPRISED TO SEE THEM PERSIST INTO THE AFTERNOON HOURS...EARLY AFTERNOON. TONIGHT...CONTINUED WARMING ALOFT...SUBSIDING INVERSION HEIGHTS AND DRY AIR (< 25%) ARRIVING THROUGH THE EVENING...LEADS TO A GRADUAL CLEARING FOR THE NIGHT. BUT AGAIN...MAYBE CLOUDS COULD HANG ON A BIT LONGER INTO THE EVENING AND DAY CREW WILL NEED TO ASSESS THIS (NOT UNCOMMON FOR LAKE EFFECT TO HOLD OUT LONGER THAN ANTICIPATED). FOR NOW...WILL RIDE CURRENT FORECAST OF MOSTLY CLEAR. WINDS WILL SUBSIDE AS A SFC HIGH DROPS IN RIGHT OVER THE TOP OF NRN MICHIGAN. WILL END MARINE HEADLINES AT 11PM...AND COULD EASILY SEE LOWS DIPPING INTO THE UPPER 30S AND LOWER 40S BY DAYBREAK. SATURDAY...AIR MASS WILL BE QUITE DRY WITH H8-H5 MOISTURE AT 25% OR LESS. SFC HIGH WILL DRIFT EAST LATE IN THE DAY...WHILE MODELS CONTINUE TO INSIST THAT HIGHER LEVEL MOISTURE WILL TRY AND SQUEAK INTO THE GTV BAY REGION BY LATE AFTERNOON...WELL AHEAD OF A WARM FRONT THAT IS EXPECTED TO BE WELL SOUTH OF US...ACROSS IOWA/NRN IL. CAN SEE NO CHANCE FOR PRECIPITATION. SATURDAY NIGHT ONWARD...THE SFC HIGH WILL BE STUBBORN TO LEAVE US...BUT A SLOW DRIFT EASTWARD THROUGH MONDAY IS ANTICIPATED. THE QUESTION IS...HOW LONG WILL IT BE BEFORE...OR WILL THE MOISTURE EVER BECOME DEEP ENOUGH WITH WAA...TO DEVELOP A CHANCE OF RAIN SHOWERS FOR OUR SRN ZONES...SOUTH OF M-72. MID LEVEL HEIGHTS SLOWLY RISE THROUGH THE PERIOD...SO I CAN BELIEVE A SLOW PROGRESSION NORTH THROUGH TIME WITH THE WARM FRONT. HOWEVER...BASED ON THE LOW LEVEL HIGH PRESSURE AXIS OVER THE GULF...AND THE FACT THAT THE MODELS MAY BE RIDDLED WITH CONVECTIVE FEEDBACK...HAVE QUESTIONS ABOUT THE NORTHWARD EXTENT OF MODEL FORECAST PRECIPITATION BEGINNING SATURDAY NIGHT. AGREE WITH PREVIOUS FORECASTER THOUGHTS...AND WILL RIDE CURRENT FORECAST OF CHANCE FOR RAIN SHOWERS THROUGH MONDAY NIGHT SOUTH OF M-72. WOULD NOT BE SURPRISED AT ALL TO SEE THESE CHANCES REMOVED WITH FUTURE FORECAST ISSUANCES. FOR NOW...JUST MADE SOME COSMETIC CHANGES TO BLEND IN WITH SURROUNDING OFFICES. SMD .AVIATION...HIGH PRESSURE AND VERY DRY AIR ACROSS NRN MICHIGAN WILL PRODUCE VFR CONDITIONS THROUGH THE NIGHT AT PLN/TVC/APN. SFC WINDS WILL REMAIN ON THE LIGHT SIDE THROUGH THE NIGHT BUT BEGIN TO INCREASE AGAIN TOWARD MORNING. ON FRIDAY...MID LEVEL WAVE AND ASSOCIATED POCKET OF COLD AIR ALOFT NOW ACROSS ONTARIO EXPECTED TO DROP DOWN INTO NRN MICHIGAN. THE FAIRLY COLD AIR ALOFT (TEMPS AT 850 MB COOLING TO +5C TO +7C) OVER THE RELATIVE WARM GREAT LAKES... COMBINED WITH DAYTIME HEATING WILL LEAD TO RAPID DEVELOPMENT OF BKN LOWER CLOUD COVER FRIDAY MORNING...BASES 3K-5K FEET. MAY BE ENOUGH LOW LEVEL INSTABILITY TO PRODUCE SOME SHOWER ACTIVITY AT PLN/APN FROM MID MORNING THROUGH MID AFTERNOON...BUT GIVEN LOW PROBABILITIES WILL ONLY CARRY VICINITY SHOWERS AT THESE TAF SITES FOR NOW. IF ENOUGH LOW LEVEL MOISTURE REMAINS ON FRIDAY...DAYTIME HEATING COULD FIRE OFF AN ISOLATED THUNDERSTORM OR TWO (A FEW LIGHTNING STRIKES NOTED OVER CENTRAL ONTARIO LATE THIS AFTERNOON) BRINGING A RISK FOR THUNDER PRIMARILY TO APN. HOWEVER...THIS SCENARIO APPEARS UNLIKELY AT THIS JUNCTURE. ADAM && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 712 PM CDT SAT AUG 18 2007 .UPDATE...ADDED AVIATION DISCUSSION FOR 00Z TAFS BELOW && .DISCUSSION... VOLATILE SITUATION SETTING UP ACROSS FAR SOUTHERN MN AND NORTHERN IA AT MID AFTERNOON. CLOUDS AND RAIN TODAY HAVE HELD TEMPERATURES AND DEW POINTS IN THE UPPER 50S OVER FAR SOUTHERN MN. JUST SOUTH OF THE WARM FRONT IN IA TEMPERATURES ARE IN THE UPPER 80S AND DEW POINTS ARE IN THE MIDDLE 70S. STRONG LOW LEVEL WAA IN FOCUSED ACROSS SOUTH CENTRAL MN THROUGH 19/06Z BEFORE WINDS BEGIN TO VEER. ANOTHER SHORT WAVE IS PROGGED TO PASS ACROSS IA THIS EVENING FROM NEBRASKA. THIS FEATURE IS NOT AS CLEAR AS THE TWO CIRCULATIONS SEEN IN THE MOSAIC RADAR IMAGERY OVER EASTERN SD THIS MORNING. THESE FEATURES ARE NOW APPROACHING EASTERN MN. THE RUC/NAM LOW LEVEL WINDS INCREASE TO NEAR 40 KNOTS DURING THE EVENING OVER NORTHERN IA AND FAR SOUTH CENTRAL MN. THE WIND PROFILE AT KFRM IS STRONGLY VEERED. MAIN CONCERN IS FOR MORE CONVECTIVE DEVELOPMENT ALONG AND NORTH OF INTERSTATE 90. PW`S ARE NEAR 2 INCHES ATTM. RAINFALL TODAY FROM OBSERVERS AND RADAR HAS TOTALED 1.5 TO 3 INCHES. THE RADAR IS SLIGHTLY UNDERESTIMATING ON THE STP WHICH IS NOT SURPRISING GIVEN THE DISTANCE THE RAIN IS AWAY FROM THE RADAR AND THE FACT THAT THIS IS LOW TOP CONVECTION. DECIDED EARLY THIS AFTERNOON TO EXTEND THE FLOOD WATCH THROUGH 4 AM SUNDAY FOR SOUTH CENTRAL MN WITH THE THREAT FOR HEAVY RAIN CONTINUING INTO EARLY SUNDAY MORNING. EXCELLENT COORDINATION FROM THE SURROUNDING OFFICES TODAY. THE ROAD AHEAD LOOKS WET AND STORMY...ESPECIALLY FOR SOUTHERN MN...AS AN UPPER LOW OFF THE PACIFIC NORTHWEST PUSHES INTO SOUTH CENTRAL CANADA BY MID WEEK. WE WILL BE UNDER THE GUN FOR MORE HEAVY RAIN SUNDAY NIGHT OVER SOUTHERN AREAS OF MN AS LOW LEVEL WINDS BACK AND INCREASE AHEAD OF YET ANOTHER SHORT WAVE. SEVERE WEATHER WILL ALSO BE POSSIBLE AS THE WARM FRONT SHOULD BE NEAR THE IA/MN BORDER. ALL FORMS OF SEVERE WEATHER WILL BE POSSIBLE. THE ONE THING TODAY DIFFERENT FROM THAT SEEN ON FRIDAY IS THAT THE WARM FRONT LOOKS LIKE IT WILL HAVE A HARD TIME MOVING TO FAR NORTH AND MAY STAY OVER OUR SOUTHERN FA INTO TUESDAY. THE PICTURE BECOMES A LITTLE MUDDY TUESDAY INTO WEDNESDAY...BUT AS THE UPPER LOW REACHES SOUTH CENTRAL CANADA...THERE WILL BE AN ASSOCIATED COLD FRONT THAT WILL TRY TO PUSH ACROSS THE FA. CHANCES POPS CONTINUED INTO MID WEEK. IT APPEARS A WAVE OF LOW PRESSURE WILL TRY AND RIDE NORTHEAST ALONG THE FRONT THURSDAY AND FRIDAY...PASSING ACROSS SOUTHERN MN. HENCE...CHANCE POPS REMAIN IN THE FORECAST THROUGH FRIDAY. IT APPEARS IT MAY BE NEXT WEEKEND BEFORE WINDS TURN NORTHWEST ALOFT AND THINGS DRY OUT. && .AVIATION.../FOR 00Z TAFS/ MESSY FORECAST CONTINUES THANKS TO AREA STAYING NORTH OF A WARM FRONTAL BOUNDARY STRETCHED ACROSS SOUTHEAST SOUTH DAKOTA AND WESTERN IOWA. TRICKY FORECAST BUT AM FAIRLY CONFIDENT IN IFR CIGS TONIGHT AND LOWER END MVFR/HIGHER IFR CIGS RIGHT THROUGH SUNDAY AFTERNOON. ALSO CONFIDENT IN LOWERING VISIBILITY LATE THIS EVENING AND OVERNIGHT WITH ABUNDANT LOW LEVEL MOISTURE NOT GOING ANYWHERE. EXPECT THAT VIS WILL FALL INTO THE 1-4 MILE RANGE ACROSS THE AREA. THE TRICKY PART WILL BE THE PRECIPITATION CHANCES THROUGH THE PERIOD...AND THUS LOWER CONFIDENCE IN THIS PART OF THE FORECAST. CURRENTLY...BAND OF SHOWERS FROM THE TWIN CITIES SOUTHEASTWARD THROUGH FARIBAULT AND TOWARDS ROCHESTER CONTINUES TO DRIFT EASTWARD. FORCING FOR THIS WILL CONTINUE EASTWARD THROUGH THE EVENING. ADDITIONAL SCATTERED SHOWERS HAVE DEVELOPED TO THE WEST AND SOUTHWEST OF THE TWIN CITIES IN THE LAST HALF HOUR OR SO. ADDITIONAL MOISTURE MOVING IN AND BEING PUSHED UPWARD OVER THE AREA DRIVING THIS DEVELOPMENT. THIS FORCING WILL TURN MORE TO THE EAST AND SHIFT THE SHOWER DEVELOPMENT TO THE SOUTH OF THE TAF SITES THROUGH THE MID TO LATE EVENING. MOST AT RISK FOR SIGNIFICANT SHRA/TSRA THIS EVENING AND TONIGHT IS KRWF. CONVECTION IS EXPECTED TO DEVELOP ACROSS SOUTHEAST SOUTH DAKOTA OVER THE NEXT COUPLE HOURS. THIS WILL MOVE EAST AND SOUTHEAST AND MAY BRUSH KRWF. WILL NEED TO MONITOR FOR POTENTIAL IMPACT THERE. AT KMSP/KRNH/KEAU ...THE BEST CHANCE FOR SHOWERS WILL BE OVER THE NEXT SEVERAL HOURS. VISIBILITY TO LESS THAN 2 MILES WILL BE POSSIBLE IN THE MOST INTENSE SHOWERS BUT DOWNPOURS WILL BE BRIEF. DRIZZLE AND LIGHT RAIN WILL BE POSSIBLE THROUGH THE NIGHT BUT AM THINKING THIS WILL BE SCATTERED AND OF LOW INTENSITY. ..MDB.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...FLASH FLOOD WATCH UNTIL 4 AM CDT SUNDAY FOR BLUE EARTH-BROWN- FARIBAULT-FREEBORN-LE SUEUR-MARTIN-NICOLLET-RICE-STEELE- WASECA-WATONWAN COUNTY(IES). WI...NONE. && $$ RAH/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 337 PM CDT SAT AUG 18 2007 .DISCUSSION... VOLATILE SITUATION SETTING UP ACROSS FAR SOUTHERN MN AND NORTHERN IA AT MID AFTERNOON. CLOUDS AND RAIN TODAY HAVE HELD TEMPERATURES AND DEW POINTS IN THE UPPER 50S OVER FAR SOUTHERN MN. JUST SOUTH OF THE WARM FRONT IN IA TEMPERATURES ARE IN THE UPPER 80S AND DEW POINTS ARE IN THE MIDDLE 70S. STRONG LOW LEVEL WAA IN FOCUSED ACROSS SOUTH CENTRAL MN THROUGH 19/06Z BEFORE WINDS BEGIN TO VEER. ANOTHER SHORT WAVE IS PROGGED TO PASS ACROSS IA THIS EVENING FROM NEBRASKA. THIS FEATURE IS NOT AS CLEAR AS THE TWO CIRCULATIONS SEEN IN THE MOSAIC RADAR IMAGERY OVER EASTERN SD THIS MORNING. THESE FEATURES ARE NOW APPROACHING EASTERN MN. THE RUC/NAM LOW LEVEL WINDS INCREASE TO NEAR 40 KNOTS DURING THE EVENING OVER NORTHERN IA AND FAR SOUTH CENTRAL MN. THE WIND PROFILE AT KFRM IS STRONGLY VEERED. MAIN CONCERN IS FOR MORE CONVECTIVE DEVELOPMENT ALONG AND NORTH OF INTERSTATE 90. PW`S ARE NEAR 2 INCHES ATTM. RAINFALL TODAY FROM OBSERVERS AND RADAR HAS TOTALED 1.5 TO 3 INCHES. THE RADAR IS SLIGHTLY UNDERESTIMATING ON THE STP WHICH IS NOT SURPRISING GIVEN THE DISTANCE THE RAIN IS AWAY FROM THE RADAR AND THE FACT THAT THIS IS LOW TOP CONVECTION. DECIDED EARLY THIS AFTERNOON TO EXTEND THE FLOOD WATCH THROUGH 4 AM SUNDAY FOR SOUTH CENTRAL MN WITH THE THREAT FOR HEAVY RAIN CONTINUING INTO EARLY SUNDAY MORNING. EXCELLENT COORDINATION FROM THE SURROUNDING OFFICES TODAY. THE ROAD AHEAD LOOKS WET AND STORMY...ESPECIALLY FOR SOUTHERN MN...AS AN UPPER LOW OFF THE PACIFIC NORTHWEST PUSHES INTO SOUTH CENTRAL CANADA BY MID WEEK. WE WILL BE UNDER THE GUN FOR MORE HEAVY RAIN SUNDAY NIGHT OVER SOUTHERN AREAS OF MN AS LOW LEVEL WINDS BACK AND INCREASE AHEAD OF YET ANOTHER SHORT WAVE. SEVERE WEATHER WILL ALSO BE POSSIBLE AS THE WARM FRONT SHOULD BE NEAR THE IA/MN BORDER. ALL FORMS OF SEVERE WEATHER WILL BE POSSIBLE. THE ONE THING TODAY DIFFERENT FROM THAT SEEN ON FRIDAY IS THAT THE WARM FRONT LOOKS LIKE IT WILL HAVE A HARD TIME MOVING TO FAR NORTH AND MAY STAY OVER OUR SOUTHERN FA INTO TUESDAY. THE PICTURE BECOMES A LITTLE MUDDY TUESDAY INTO WEDNESDAY...BUT AS THE UPPER LOW REACHES SOUTH CENTRAL CANADA...THERE WILL BE AN ASSOCIATED COLD FRONT THAT WILL TRY TO PUSH ACROSS THE FA. CHANCES POPS CONTINUED INTO MID WEEK. IT APPEARS A WAVE OF LOW PRESSURE WILL TRY AND RIDE NORTHEAST ALONG THE FRONT THURSDAY AND FRIDAY...PASSING ACROSS SOUTHERN MN. HENCE...CHANCE POPS REMAIN IN THE FORECAST THROUGH FRIDAY. IT APPEARS IT MAY BE NEXT WEEKEND BEFORE WINDS TURN NORTHWEST ALOFT AND THINGS DRY OUT. && .PREV DISCUSSION... /ISSUED 108 PM CDT SAT AUG 18 2007/ AVIATION... /18Z TAFS/ CEILINGS WILL CONTINUE TO DROP THROUGH THE TAF PERIOD WITH HIGH CONFIDENCE AS WARM MOIST AIR OVERRIDES A SHALLOW STABLE COOL LAYER AT THE SURFACE. THUNDER WILL BE MORE PREDOMINANT SOUTH OF THE MN RIVER VALLEY...HOWEVER LATE THIS AFTN AND INTO THIS EVE AS LOW LEVEL JET RESURGES THERE IS ENOUGH INCREASE IN INSTABILITY INDICATED BY THE MODELS TO WARRANT A HINT AT T-STORMS. MVFR VISBYS WILL BE COMMONPLACE THROUGH THE TAF PERIOD...WITH IFR FOG LIKELY AT RWF TONIGHT GIVEN THE WET GROUND AND SLACKENING WINDS THERE && .MPX WATCHES/WARNINGS/ADVISORIES... MN...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR BLUE EARTH-BROWN- FARIBAULT-FREEBORN-LE SUEUR-MARTIN-NICOLLET-RICE-STEELE- WASECA-WATONWAN COUNTY(IES). WI...NONE. && $$ RAH/MTF mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1014 AM CDT SAT AUG 18 2007 .UPDATE... LOWERED MAX TEMPS ACROSS SRN HALF OF CWA TODAY CLOSER TO MAV/LAMP GUIDANCE. OVERCAST SKIES ALONG WITH THE RAIN SHOWERS ALONG THE SRN ZONES WILL KEEP TEMPERATURES IN THE 60S TODAY. FURTHER NORTH...MORE SUN AND DRY CONDITIONS WILL RESULT IN TEMPS IN THE LOWER 70S. TWEAKED POPS TO ACCOUNT FOR CURRENT RADAR/SAT TRENDS. NO SIG CHANGES TO FCST...CONTINUE TO EXPECT THE NRN EDGE OF THE RA TO TRACK REACH INTO THE SRN TIER OF COUNTIES IN THE DLH CWA. ONLY ISOLD -SHRA WILL BE FOUND IN THE TWIN PORTS AREA. && .PREV DISCUSSION... /ISSUED 338 AM CDT SAT AUG 18 2007/ DISCUSSION...MAIN FOCUS OVER THE NEXT FEW DAYS WILL BE TO RESOLVE PRECIPITATION POTENTIAL OFFERED A MYRIAD OF DIFFERENT SOLUTIONS. AT PRESENT TIME...CLEAR SKIES AND VERY COOL CONDITIONS WERE FOUND ALONG THE IRON RANGE AND THE ARROWHEAD REGIONS. TEMPERATURES HAD DROPPED INTO THE MIDDLE 30S AT THE GRAND MARAIS AIRPORT. A DEVELOPING AREA OF SHOWERS AND THUNDERSTORMS EXTENDED FROM CENTRAL SOUTH DAKOTA...INTO SW MN AND NORTHERN IOWA. THE ENTIRE AREA WAS GRADUALLY TRYING TO SHIFT TO THE NORTH. QUITE A VARIED FORECAST AMONGST THE 00Z/06Z MODELS...WITH THE 06Z NAM AND THE FULL MEMBER SREF PAINTING PCPN A BIT FARTHER NORTH. IN TERMS OF THE GFS ENSEMBLE FORECAST...THERE WAS A FAIR AMOUNT OF SPREAD AMONGST THE MEMBERS...BUT AGREEMENT ON A SHARP N-S CUTOFF TO THE PRECIPITATION. WILL FOLLOW THE OPERATIONAL GFS FAIRLY CLOSELY FOR THE FORECAST OVER THE NEXT FEW DAYS...ALTHOUGH WILL LEND SOME CREDENCE TO OTHER MODELS...ESPECIALLY THE 06Z RUC...BY EXTENDING A SMALL POP NORTH OF THE EXPECTED MAIN PCPN AREA. HAVE WENT JUST SLIGHTLY NORTH OF THE HPC QPF AREA AS WELL. THE MAIN PCPN THIS WEEKEND IS EXPECTED TO BE IN THE FAR SOUTH. FOR TODAY...THE SHORTWAVE PUSHING EASTWARD OUT OF THE DAKOTAS WILL SPREAD PRECIPITATION ACROSS THE SOUTHERN CWA...WHILE THE NORTH SHOULD SEE PARTLY SUNNY SKIES. TEMPS WILL BE WARMER IN THE NORTH DUE TO INCREASED SUNSHINE IN THAT AREA. WINDS WILL INCREASE FROM THE EAST...WITH GUSTY WINDS NEAR THE LAKE SUPERIOR SHORELINE. FOR TONIGHT INTO SUNDAY...THE FOCUS WILL CONTINUE TO BE IN THE SOUTHERN CWA...ALTHOUGH GFS PAINTING SOME QPF PUSHING NORTHWARD INTO THE IRON RANGE. DRY EASTERLY WINDS FUNNELING OUT OF HIGH PRESSURE IN ONTARIO WILL KEEP THE ARROWHEAD REGION DRY FOR SURE...AND POSSIBLY EVEN INTO NC MN. A LITTLE BETTER CHANCE OF PRECIPITATION CWA-WIDE WILL ARRIVE MONDAY AND CONTINUE INTO TUESDAY...AS A FRONTAL BOUNDARY MOVES EASTWARD ACROSS THE REGION. OVERALL...TEMPERATURES SHOULD MODERATE...BACK INTO THE 70S FOR MOST AREAS BY EARLY TO MID WEEK. AVIATION...VFR CONDITIONS ARE EXPECTED ACROSS THE FORECAST AREA THROUGH THIS MORNING. AREAS OF MVFR CIGS WILL THEN BEGIN TO SPREAD IN FROM THE SOUTH THIS AFTERNOON AND EVENING. BY LATE TONIGHT...AREAS OF MVFR TO IFR CIGS WITH PATCHY FOG IS LIKELY FOR MUCH OF THE NORTHLAND. THERE WILL BE A CHANCE OF THUNDERSTORMS ACROSS CENTRAL MN AND WI TONIGHT...MAINLY AFFECTING KHYR. && POINT TEMPS/POPS... DLH 66 50 69 54 / 20 10 20 20 INL 72 48 74 55 / 10 10 10 10 BRD 67 55 71 60 / 80 20 30 40 HYR 66 53 71 56 / 70 30 30 30 ASX 67 51 70 58 / 20 10 20 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ GRANING/CANNON mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 338 AM CDT SAT AUG 18 2007 .DISCUSSION...MAIN FOCUS OVER THE NEXT FEW DAYS WILL BE TO RESOLVE PRECIPITATION POTENTIAL OFFERED A MYRIAD OF DIFFERENT SOLUTIONS. AT PRESENT TIME...CLEAR SKIES AND VERY COOL CONDITIONS WERE FOUND ALONG THE IRON RANGE AND THE ARROWHEAD REGIONS. TEMPERATURES HAD DROPPED INTO THE MIDDLE 30S AT THE GRAND MARAIS AIRPORT. A DEVELOPING AREA OF SHOWERS AND THUNDERSTORMS EXTENDED FROM CENTRAL SOUTH DAKOTA...INTO SW MN AND NORTHERN IOWA. THE ENTIRE AREA WAS GRADUALLY TRYING TO SHIFT TO THE NORTH. QUITE A VARIED FORECAST AMONGST THE 00Z/06Z MODELS...WITH THE 06Z NAM AND THE FULL MEMBER SREF PAINTING PCPN A BIT FARTHER NORTH. IN TERMS OF THE GFS ENSEMBLE FORECAST...THERE WAS A FAIR AMOUNT OF SPREAD AMONGST THE MEMBERS...BUT AGREEMENT ON A SHARP N-S CUTOFF TO THE PRECIPITATION. WILL FOLLOW THE OPERATIONAL GFS FAIRLY CLOSELY FOR THE FORECAST OVER THE NEXT FEW DAYS...ALTHOUGH WILL LEND SOME CREDENCE TO OTHER MODELS...ESPECIALLY THE 06Z RUC...BY EXTENDING A SMALL POP NORTH OF THE EXPECTED MAIN PCPN AREA. HAVE WENT JUST SLIGHTLY NORTH OF THE HPC QPF AREA AS WELL. THE MAIN PCPN THIS WEEKEND IS EXPECTED TO BE IN THE FAR SOUTH. FOR TODAY...THE SHORTWAVE PUSHING EASTWARD OUT OF THE DAKOTAS WILL SPREAD PRECIPITATION ACROSS THE SOUTHERN CWA...WHILE THE NORTH SHOULD SEE PARTLY SUNNY SKIES. TEMPS WILL BE WARMER IN THE NORTH DUE TO INCREASED SUNSHINE IN THAT AREA. WINDS WILL INCREASE FROM THE EAST...WITH GUSTY WINDS NEAR THE LAKE SUPERIOR SHORELINE. FOR TONIGHT INTO SUNDAY...THE FOCUS WILL CONTINUE TO BE IN THE SOUTHERN CWA...ALTHOUGH GFS PAINTING SOME QPF PUSHING NORTHWARD INTO THE IRON RANGE. DRY EASTERLY WINDS FUNNELING OUT OF HIGH PRESSURE IN ONTARIO WILL KEEP THE ARROWHEAD REGION DRY FOR SURE...AND POSSIBLY EVEN INTO NC MN. A LITTLE BETTER CHANCE OF PRECIPITATION CWA-WIDE WILL ARRIVE MONDAY AND CONTINUE INTO TUESDAY...AS A FRONTAL BOUNDARY MOVES EASTWARD ACROSS THE REGION. OVERALL...TEMPERATURES SHOULD MODERATE...BACK INTO THE 70S FOR MOST AREAS BY EARLY TO MID WEEK. && .AVIATION...VFR CONDITIONS ARE EXPECTED ACROSS THE FORECAST AREA THROUGH THIS MORNING. AREAS OF MVFR CIGS WILL THEN BEGIN TO SPREAD IN FROM THE SOUTH THIS AFTERNOON AND EVENING. BY LATE TONIGHT...AREAS OF MVFR TO IFR CIGS WITH PATCHY FOG IS LIKELY FOR MUCH OF THE NORTHLAND. THERE WILL BE A CHANCE OF THUNDERSTORMS ACROSS CENTRAL MN AND WI TONIGHT...MAINLY AFFECTING KHYR. && POINT TEMPS/POPS... DLH 67 50 69 54 / 20 10 20 20 INL 72 48 74 55 / 10 10 10 10 BRD 70 55 71 60 / 40 20 30 40 HYR 68 53 71 56 / 40 30 30 30 ASX 68 51 70 58 / 20 10 20 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP/BERDES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 332 PM CDT SAT AUG 18 2007 .DISCUSSION... SHORT TERM... MAIN CONCERN IS WITH THE REMNANTS OF ERIN. WRF WANTS TO SPLIT UP THE CIRCULATION WITH ERIN AND HAS A STRONGER SHORT WAVE IN THE NORTHERN STREAM PHASING WITH THE PART OF ERIN IT BRINGS NORTH INTO MISSOURI SUNDAY NIGHT. GFS AND SIMILARLY THE ECMWF HOLD THE REMNANTS MORE AS A SINGLE ENTITY AND ARE SLOWER WITH MOVING IT THROUGH THE FORECAST AREA. PREFER THIS SLOWER SOLUTION SINCE THERE IS NOT A STRONGER WAVE TO KICK THIS FEATURE UNTIL IT BECOMES PHASED WITH THE NORTHERN STREAM MONDAY NIGHT. THUS WILL KEEP SLIGHT CHANCE OR CHANCE POPS IN FORECAST AREA THROUGH MONDAY NIGHT. SHOULD CONTINUE TO SEE PLENTY OF CLOUDINESS BEING PUMPED INTO AREA WITH MOISTURE FROM ERIN STREAMING OVER THE REGION. MAV NUMBERS ON SUNDAY LOOK WAY TOO WARM GIVEN THE CLOUDINESS...AND MET A LITTLE TOO COOL GIVEN THE AIRMASS. THUS WILL GO WITH A COMPROMISE OF GUIDANCE NUMBERS FOR HIGHS ON SUNDAY. WILL ALSO KEEP MONDAY A LITTLE COOLER IN EASTERN AREAS WITH CLOUDS AND RAIN EXPECTED. PC LONG TERM... ONLY SLIGHT ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FORECAST. MODELS REMAIN IN DECENT AGREEMENT FLATTENING THE H5 RIDGE AND SWEEPING LONG WAVE TROUGH ACROSS THE NORTHERN CONUS EARLY IN THE PERIOD. BY TUESDAY...H5 TROUGH WILL SWING A WEAK COLD FRONT THROUGH THE MIDWEST...WITH THE FRONT LIKELY REACHING EXTREME NORTHERN MISSOURI BY TUESDAY NIGHT. AS THE OVERALL FLOW PATTERN BECOMES ZONAL FOR MID-WEEK...FRONT WILL LIKELY REMAIN STALLED FROM WEST TO EAST JUST TO THE NORTH OF THE CWA THROUGH MUCH OF THE WEEK...BECOMING SUSCEPTIBLE TO WEAK IMPULSES RIDING THROUGH THE MID-LVL FLOW. FOR NOW...MADE LITTLE CHANGES TO THE ONGOING POPS SINCE SO MUCH UNCERTAINTY EXISTS AS TO HOW FAR SOUTH THE FRONT WILL BE ABLE TO SINK. ATTM...BEST CHANCE FOR RAINFALL WILL REMAIN ACROSS THE NORTHERN TIER OF COUNTIES...HOWEVER ONLY LOW CHANCE POPS WARRANTED AT THIS TIME. MEDIUM RANGE MODELS TRY TO BRING A SECOND DISTURBANCE THROUGH THE MID-LVL FLOW BY THURSDAY. THIS DISTURBANCE SHOULD BE STRONG ENOUGH TO DISLODGE THE FRONT AND PUSH IT SOUTHWARD THROUGH THE AREA. THE GFS HAS CONTINUED TO SLOW THE FRONTAL PASSAGE DOWN...WITH A SLOWDOWN OF NEARLY 24 HOURS ALREADY NOTED. THE FRONT WILL LIKELY DROP JUST TO THE SOUTH OF THE AREA IN THE FRIDAY/SATURDAY TIMEFRAME...WITH THE RETROGRADING H5 RIDGE OVER THE SE KEEPING THE FRONT FROM DROPPING FURTHER SOUTH. AS FAR AS TEMPERATURES ARE CONCERNED...MUCH OF THE CWA WILL REMAIN IN THE WARM SECTOR THROUGH MID-WEEK. AS A RESULT...BUMPED UP MIN/MAX TEMPERATURES A DEGREE OR TWO IN ORDER TO COMPENSATE FOR THE STRONGER SW LOW-LVL FLOW. BY NEXT WEEKEND...IF THE FRONT IS ABLE TO DROP THROUGH THE AREA...TEMPERATURES WILL LIKELY FALL INTO THE 80S. HOWEVER...INDICATIONS POINT TO A RETURN OF A LONG-WAVE RIDGE AND QUICK RETURN TO WARMER TEMPERATURES. 31 && .AVIATION... FOR THE 18Z TAFS...WARM FRONT HAS LIFTED NORTH OF THE KANSAS CITY TAF SITES...AND WE WILL SEE THE WINDS A BIT STRONGER DURING THE AFTERNOON HOURS TO THE SOUTH OF THIS BOUNDARY. THE FRONT WILL BE LIFTING NORTH OF THE ST JOSEPH TAF SITE SHORTLY...WHICH SHOULD END THE HAZE IN THE REGION. BETTER INSTABILITY AT THIS POINT ACROSS EASTERN KANSAS BUT LOOKING AT RUC MODEL...SHOWING VORT LOBE LIFTING INTO EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI LATE THIS AFTERNOON THAT MAY ALSO SUPPORT THUNDERSTORM DEVELOPMENT IN THOSE AREAS...SO WILL CONTINUE WITH THE TEMPO GROUP TO COVER THIS POTENTIAL. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 120 PM CDT SAT AUG 18 2007 ...UPDATED FOR AVIATION... .DISCUSSION... /210 AM CDT SAT AUG 18 2007/ ATTENTION NOW SHIFTS AWAY FROM THE HIGH HEAT TO THE THREAT OF CONVECTION THIS WEEKEND. LATEST SFC ANALYSIS DEPICTS A POORLY DEFINED STATIONARY FRONT FROM SERN NEB SW TO XTRM SWRN MO. THIS FRONT WILL MOVE QUICKLY NORTH TODAY IN RESPONSE TO A SHORTWAVE TROUGH MOVING THROUGH THE NRN PLAINS. THE FRONT IS XPCTD TO SHIFT NE INTO THE ERN CWA THIS AFTN...AND WITH A VERY WEAK CAP IN PLACE...ALONG WITH MODERATE INSTABILITY...THE FRONT MAY TRIGGER A FEW THUNDERSTORMS. MAIN CONCERN IS THE REMNANTS OF TROPICAL STORM ERIN. LATEST STLT AND RADAR SHOW A NEARLY STATIONARY UPPER LOW JUST NORTH OF MIDLAND TEXAS. DEEP MID-TROPOSPHERIC MOISTURE WAS GRADUALLY BEING ADVECTED NORTH INTO WRN TX EAST TO ARKANSAS. HAVE LITTLE FAITH IN THE MODELS FUTURE DEPICTION OF THE STRUCTURE AND MOVEMENT OF THE UPPER TROUGH. BOTH THE NAM/HIGH RESOLTUION WRF AND GFS...SHEAR A SHORTWAVE NE FROM THE UPPER LOW...BUT STLT AND RADAR SHOW LITTLE INDICATION OF THIS. REGARDLESS...THE OUTER BANDS OF DEEP MOISTURE WILL ADVECT NE INTO THE XTRM SRN CWA LATE THIS MORNING AND INTO WEST CENTRAL MISSOURI DURING THE AFTN...WITH PRECIPITABLE WATER VALUES RISING TO AROUND 2 INCHES. MODEL GRIDS AND FCST SOUNDINGS SHOW A LACK OF A CAP...ESPECIALLY FOR THE SERN TWO THIRDS OF THE CWA. AFTN HEATING ALONE WILL BE SUFFICIENT FOR THE GENERATE SCT THUNDERSTORMS...AS MLCAPES RISE TO NR 2500 J/KG. WK QG FORCING/DEFORMATION ASSOCIATED WITH ANY SHORTWAVE WILL SERVE TO INCREASE THE THREAT. CONVECTION TO DIMINISH DURING THE EVENING WITH THE ONSET OF NIGHTTIME COOLING. HOWEVER...THERE WILL STILL BE SUFFICIENT WEAK UPPER FORCING WITH THE APPROACH OF THE UPPER SHR AXIS TO GENERATE ADDITIONAL SHOWERS OR THUNDERSTORMS. THE NRN PORTION OF THE UPPER TROUGH EVENTUALLY GETS PICK UP BY WEAK WESTERLIES WITH THE UPPER SHEAR AXIS TO SLOWLY PROGRESS EAST THROUGH THE CWA. THE SHEAR AXIS PASSES THROUGH THE XTRM NWRN CWA EARLY SUNDAY....THUS LIMITING THE THREAT OF PRECIPITATION. ACROSS THE REST OF THE CWA...JUST AHEAD OF THE SHEAR AXIS...AFTN HEATING IN COMBINATION WITH WEAK UPPER FORCING SHOULD ALLOW FOR THE DEVELOPMENT OF SCATTERED THUNDERSTORMS IN AN UNCAPPED ENVIRONMENT. THE PRECIPITATION IS EXPECTED TO END IN THE ERN CWA SUNDAY NIGHT WITH THE PASSAGE OF THE SHEAR AXIS. OTHERWISE...TEMPERATURES WILL BE COOLER THIS WEEKEND DUE TO CLOUD COVER AND BEING UNDER THE INFLUENCE OF COOLER S/SSE H8 TRAJECTORIES. DB && .AVIATION... FOR THE 18Z TAFS...WARM FRONT HAS LIFTED NORTH OF THE KANSAS CITY TAF SITES...AND WE WILL SEE THE WINDS A BIT STRONGER DURING THE AFTERNOON HOURS TO THE SOUTH OF THIS BOUNDARY. THE FRONT WILL BE LIFTING NORTH OF THE ST JOSEPH TAF SITE SHORTLY...WHICH SHOULD END THE HAZE IN THE REGION. BETTER INSTABILITY AT THIS POINT ACROSS EASTERN KANSAS BUT LOOKING AT RUC MODEL...SHOWING VORT LOBE LIFTING INTO EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI LATE THIS AFTERNOON THAT MAY ALSO SUPPORT THUNDERSTORM DEVELOPMENT IN THOSE AREAS...SO WILL CONTINUE WITH THE TEMPO GROUP TO COVER THIS POTENTIAL. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 410 PM CDT FRI AUG 17 2007 .DISCUSSION... SHORT RANGE (TONIGHT THROUGH SUNDAY)... CU STARTING TO BUBBLE ALONG INSTABILITY AXIS THAT RUNS FROM SOUTHEAST NEBRASKA INTO THE LAKE REGION OF MISSOURI ALONG OLD STATIONARY BOUNDARY. ISOLD CONVECTION POPPING ACROSS SOUTHEAST NEBRASKA AND IN MISSOURI LAKE DISTRICT WHERE AFTERNOON TEMPERATURES HAVE CLIMBED TO CONVECTIVE TEMPERATURES. BROADBRUSHED HIGHER SLIGHT CHANCE POPS ALONG BOUNDARY FOR THE EVENING HOURS...THEN DIMINSH SLIGHTLY THROUGH THE BULK OF THE OVERNIGHT...AS ANY STORMS THAT DEVELOP WILL BE DIURNALLY DRIVEN. GIVEN BOUNDARY IN THE AREA...EAST TO SOUTHEAST BOUNDARY FLOW...AND BOUNTIFUL BOUNDARY LAYER MOISTURE...IT IS LIKELY THERE WILL BE FOG/HAZE DEVELOPMENT AGAIN TONIGHT. DENSE FOG FORMATION WAS ISOLATED LAST NIGHT...AND SINCE BOUNDARY LAYER FLOW WILL BE A LITTLE STRONGER TONIGHT...WILL HOLD OFF ON ANY TYPE OF ADVISORY FOR TONIGHT. DECIDED TO UP POPS A LITTLE AFTER 09 UTC...AS RUC/NAM12 AND LOCAL WRF ALL DEPICTING DECENT ISENTROPIC FORCING ALNG 308-310K SURFACES IN RESPONSE TO NOCTURNAL 25-30KT LLJ. THE REST OF SATURDAY WILL BE SOMEWHAT OF A TRANSITION DAY AS THE FIRST OF SEVERAL BANDS ASSOCIATED WITH ERIN ENCROACH ON THE FORECAST AREA. GFS IS COMING MORE IN LINE WITH NAM IN TERMS OF TRAJECTORY OF MID-TROPOSPHERIC REMNANTS OF ERIN. BOTH NAM AND GFS EJECT PIECES OF SYSTEM ACROSS THE AREA ON SATURDAY...WHICH LIKELY WILL RESULTS IN PERIODS OF SHOWERS AND POSSIBLE ISOLATED THUNDER. MAIN UPPER CENTER BECOMES CAUGHT UP IN WESTERLIES ON SUNDAY...AND IN TURN WILL ENHANCE BNDRY AND H8 MOISTURE FLUX INTO AREA. INCREASED POPS INTO THE HIGH CHANCE CATEGORY FOR NOW...AND WILL LET LATER SHIFTS DECIDE WHETHER TO BUMP POPS INTO LIKELY CATEGORY. CONVECTIVE DEBRIS SATURDAY MORNING AND INCREASING MID-HIGH CLOUDS SATURDAY AND SUNDAY...WILL LIMIT HEATING ENOUGH TO SHAVE A FEW DEGREES OFF MAX TEMPERATURES. BASED ON TEMPERATURE TRENDS TODAY...ANY SUN WILL ALLOW TEMPERATURES TO RISE QUICKLY AS H8 TEMPERATURES WILL REMAIN AROUND 20C BOTH SATURDAY AND SUNDAY...THUS LEANED TOWARD WARMER MAV AS GUIDE. GIVEN EXPECTED COOLER TEMPERATURES...WILL LET HEAT ADVISORY THAT IS IN EFFECT UNTIL 7 PM TODAY...EXPIRE AS SCHEDULE GIVEN THAT HEAT INDICES TODAY STRUGGLED TO REACH 100 TODAY WITH TEMPERATURES IN THE MID TO UPPER 90S. OVERNIGHT TEMPERATURES WILL BE FAIRLY PERSISTENT...AND DECIDED ONLY TO TWEAK PREVIOUS FORECAST NUMBERS. 24 MEDIUM RANGE (MONDAY THROUGH FRIDAY)... OPERATIONAL 12Z GFS HAS COME IN LINE BETTER WITH THE PREVIOUS GFS ENSEMBLES DEPICTING A MORE DAMPENED AND SLOWER SOLUTION TO A LARGE CHUNK OF WAVE ENERGY...AND ASSOCIATED SFC FRONTAL BOUNDARY PROPAGATING OVER THE CNTRL CONUS RIDGE AXIS BY THE MIDDLE OF NEXT WEEK. THIS LEADS TO SLIGHTLY BETTER CONFIDENCE IN THE OVERALL SYNOPTIC SITUATION...HOWEVER TYPICALLY QUESTIONABLE HANDLING OF TROPICAL AND SUBTROPICAL FEATURES BY GLOBAL MODELS LEAVES MUCH UNCERTAINTY PRESENT IN THIS MEDIUM RANGE PACKAGE. THE AFOREMENTIONED NRN STREAM WAVE WILL PROGRESS ACROSS THE NRN CONUS BEGINNING ON TUESDAY ACCOMPANIED BY A ZONAL 100+KT UPPER JET SEGMENT. GIVEN THE ZONAL FLOW CHARACTERISTICS AND GENERAL LACK OF PRESSURE RISES OVER SRN CANADA...EXPECT ONLY SLOW SWD PROGRESSION OF THE TRUE SFC FRONT...WITH MESOSCALE CONVECTIVE PROCESSES PROVIDING THE BEST FRONTAL MOVEMENT. HAVE TAILORED HIGHEST PRECIP CHANCES ACROSS NRN MISSOURI LATE IN THE WEEK WITH FRONT EXPECTED TO REMAIN IN IOWA FOR MOST OF THE PERIOD. GREATEST UNCERTAINTY STEMS FROM THE TROPICS WHERE THE FINAL REMNANTS OF ERIN LOOK TO BECOME ABSORBED IN THE MEAN WLY FLOW EARLY IN THE WEEK. QUITE A WIDE RANGE OF FORECASTS AVAILABLE...WITH THE NAM-WRF QUICKEST AND DRIEST WITH THE SYSTEM...SEEMINGLY LOSING TOO MUCH DEEP TROPICAL MOISTURE ALONG THE WAY TO THE CNTRL CONUS. GFS SEEMS TO BE GETTING A BETTER HANDLE ON ERIN EJECTING SEVERAL SHORTWAVES AND ASSOCIATED MOISTURE NWD ON THE WRN PERIPHERY OF THE UPPER RIDGE AXIS...WHILE KEEPING THE MAIN CIRCULATION CENTER TRAPPED IN THE SRN HIGH PLAINS. NOT CERTAIN ON HOW MUCH ENERGY WILL NECESSARILY BECOME TRAPPED NEAR THE RIDGING...THOUGH IT APPEARS ERIN WILL AT LEAST CARVE OUT A DISCERNIBLE HEIGHT WEAKNESS OVER THE SRN PLAINS...MUCH LIKE WHAT WAS SEEN DURING THE LATTER HALF OF JUNE AND EARLY JULY. THIS MIDLEVEL WEAKNESS WILL EVEN BE REINFORCED DURING THE MIDWEEK PERIOD BY A SUBTROPICAL LOW RETROGRADING WWD ALONG THE GULF COAST IN ADVANCE OF HURRICANE DEAN. THEREFORE...CANNOT ENVISION MUCH OF AN EML ADVECTING OVER THE AREA NEXT WEEK...THUS LIMITING BOTH HIGH TEMPS TO SLIGHTLY ABOVE AVERAGE...AND CAPPING INVERSION STRENGTH THAT WOULD SUPPRESS DEEP CONVECTION. HOWEVER...AFTER THE EXPECTED DEPARTURE OF ERIN ON MONDAY...LITTLE IN THE WAY OF A WELL DEFINED FOCUSING MECHANISM APPEARS TO EXIST...SO HAVE NOT INCLUDED ANY MENTION OF WIDESPREAD PRECIP...THOUGH GIVEN ONLY WEAK CAPPING AND THE LIKELIHOOD OF SUBTLE DISTURBANCES TRAVERSING NWD FROM THE SUBTROPICAL GULF LOW...CAN ENVISION SOME ISOLATED AFTERNOON CONVECTIVE SHOWERS OR MORNING SHOWERS DERIVED FROM ISENTROPIC LIFT. BETTER PRECIP CHANCES WILL ARRIVE ACROSS THE LOWER MISSOURI RIVER VALLEY BY LATE IN THE WEEK AS MIDLEVEL ENERGY FROM THE SOUTH BECOMES ABSORBED WITH THE FRONTAL BOUNDARY ASSOCIATED WITH A SERIES OF NRN STREAM WAVES. TIMING UNCERTAINTY REMAINS...HOWEVER OVERALL PATTERN WOULD SUPPORT MORE WIDESPREAD SHOWER ACTIVITY AND A RETURN TO MUCH MORE SEASONABLE TEMPERATURES. 21 && .PREV DISCUSSION... /1249 PM CDT FRI AUG 17 2007/ TWEAK TEMPERATURES...DEWPOINTS AND HEAT INDICES FOR TODAY BASED ON LATEST TRENDS. FOG AND LOW CEILINGS TAPERED MORNING HEATING A LITTLE BIT...HOWEVER AS SKIES CLEAR TEMPERATURES CLIMBING RAPIDLY. EXPECT PERIOD OF MOSTLY CLEAR SKIES TO BE SHORT LIVED AS UNCAPPED ATMOSPHERE WILL ALLOW CU/TCU DEVELOPMENT IN THE 19-20 UTC TIMEFRAME. AS A RESULT OF THE DELAYED HEATING AND EXPECTED AFTERNOON CLOUD COVER...SHAVED A DEGREE OR TWO OFF MAX TEMPERATURES. IN ADDITION...INCREASED POPS A LITTLE...THOUGH STILL KEPT THREAT IN SLIGHT CHANCE CATEGORY. NAM AND LOCAL WRF SHOWING ISOLD TO SCTD TSRA ALONG AND EAST OF INSTABILITY AXIS THAT RUNS FROM NEAR FNB...TO MKC...TO DMO. WEAK MID-LEVEL WINDS SHOULD KEEP COVERAGE ISOLD AND MOST ACTIVITY THAT DEVELOPS BELOW SEVERE LIMITS. 24 && .AVIATION... FOR THE 18Z TAFS...WITH LINGERING BOUNDARIES AND DAYTIME HEATING...SOME ISOLATED STORMS ARE POSSIBLE DURING THE AFTERNOON AND EARLY EVENING HOURS. CONFIDENCE IS LOW IN THE INITIATION AND COVERAGE OF ANY CONVECTION...THEREFORE NO THUNDER WILL BE ADDED TO THE TAFS...BUT WILL DENOTE SCATTERED CB DEVELOPMENT. BOUNDARY EXPECTED TO LIFT A LITTLE NORTH AND EAST THIS AFTERNOON AND EVENING...HOWEVER TAF SITES WILL REMAIN UNDER A MOIST...E-SE SURFACE FLOW REGIME. SIMILAR TO LAST NIGHT...EXPECT LIGHT HAZE AND BR TO DEVELOP LATE TONIGHT...WITH A BRIEF PERIOD OF IFR FOG NOT OUT OF THE QUESTION. NAM/LOCAL WRF/RUC DEPICTING WEAK ISENTROPIC FORCING ALONG THE 308-310K SURFACES...WITH A BULLSEYE OF PRESSURE ADVECTION RIGHT OVER THE TOP OF TERMINAL SITES. DECIDED TO INTRODUCED VCSH AROUND 10-11 UTC ALL TERMINAL SITES TO ACCOUNT FOR POTENTIAL ELEVATED DEVELOPMENT. 24 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...HEAT ADVISORY UNTIL 7 PM FRIDAY FOR MOZ028-MOZ029-MOZ037- MOZ038-MOZ039-MOZ040-MOZ043-MOZ044-MOZ045-MOZ046-MOZ053-MOZ054. KS...HEAT ADVISORY UNTIL 7 PM FRIDAY FOR KSZ057-KSZ060-KSZ103- KSZ104-KSZ105. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1249 PM CDT FRI AUG 17 2007 .UPDATE... TWEAK TEMPERATURES...DEWPOINTS AND HEAT INDICES FOR TODAY BASED ON LATEST TRENDS. FOG AND LOW CEILINGS TAPERED MORNING HEATING A LITTLE BIT...HOWEVER AS SKIES CLEAR TEMPERATURES CLIMBING RAPIDLY. EXPECT PERIOD OF MOSTLY CLEAR SKIES TO BE SHORT LIVED AS UNCAPPED ATMOSPHERE WILL ALLOW CU/TCU DEVELOPMENT IN THE 19-20 UTC TIMEFRAME. AS A RESULT OF THE DELAYED HEATING AND EXPECTED AFTERNOON CLOUD COVER...SHAVED A DEGREE OR TWO OFF MAX TEMPERATURES. IN ADDITION...INCREASED POPS A LITTLE...THOUGH STILL KEPT THREAT IN SLIGHT CHANCE CATEGORY. NAM AND LOCAL WRF SHOWING ISOLD TO SCTD TSRA ALONG AND EAST OF INSTABILITY AXIS THAT RUNS FROM NEAR FNB...TO MKC...TO DMO. WEAK MID-LEVEL WINDS SHOULD KEEP COVERAGE ISOLD AND MOST ACTIVITY THAT DEVELOPS BELOW SEVERE LIMITS. 24 && .PREV DISCUSSION... /705 AM CDT FRI AUG 17 2007/ SEVERAL CONCERNS IN THE SHORT TERM WITH THE FIRST BEING THE DEVELOPMENT OF FOG ACROSS NORTHERN MISSOURI. CLEAR SKIES AND LIGHT WINDS HAVE LED TO THE DEVELOPMENT OF AREAS OF FOG WITH SEVERAL LOCATIONS EXPERIENCING DENSE FOG. STLT INDICATES THAT THE FOG IS BECOMING MORE WIDESPREAD...THEREFORE...HAVE ISSUED A DENSE FOG ADVISORY FOR EARLY THIS MORNING. THE FOG WILL RAPIDLY DISSIPATE AFTER SUNRISE. THE NEXT CONCERN IS THE SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE MISSOURI AND KANSAS BORDER...TO THE NW OF KANSAS CITY. THE THUNDERSTORMS ARE DEVELOPING IN AN AREA OF WEAK ISENTROPIC LIFT WITHIN THE 310K LAYER. THE CONVECTION IS ROOTED AT AROUND 770 MB. THE NAM SUGGEST THAT THE ISENTROPIC LIFT WILL GRADUALLY WEAKEN WITH THE THREAT OF ANY CONVECTION ENDING BY LATE MORNING. OTHERWISE...A SERIES OF OUTFLOW BOUNDARIES FROM YESTERDAY EVENING HAS MADE THE FRONTAL LOCATION DIFFICULT. THE OUTFLOW BOUNDARIES HAVE PUSHED INTO SWRN MO WITH THE TRUE FRONT LIKELY CONSIDERABLY FURTHER NORTH NEAR I-70. MODELS SUGGEST THAT WEAK CONVERGENCE ALONG THE OUTFLOW BOUNDARIES WILL BE RESTRICTED TO SWRN MO THIS AFTN...HOWEVER...CANNOT RULE OUT AREAS OF WEAK CONVERGENCE FURTHER NORTH THIS AFTERNOON OVER THE WRN AND SRN CWA. THE CAP WILL CONTINUE TO WEAKEN TODAY WITH AFTN CAPES FROM 1500-2500 J/KG. THE CONVECTION IS EXPECTED TO BE ISOLATED WITH SMALL HAIL AND STRONG WIND GUSTS POSSIBLE. ANY CONVECTION WILL DISSIPATE THIS EVENING...BUT WILL KEEP A SLGT CHC OF CONVECTION FOR EXTREME NERN MO LATE TONIGHT DUE TO WEAK ISENTROPIC LIFT. TEMPERATURES WILL BE A LITTLE COOLER TODAY DUE TO COOLER LOW LVL E/SE H8 TRAJECTORIES. TEMPERATURES WILL STILL BE QUITE WARM FOR AREAS SOUTH OF INTERSTATE 70. THE HEAT IN COMBINATION WITH THE HUMIDITY WILL PUSH HEAT INDICES TO BETWEEN 98 AND 104. ALTHOUGH THE HEAT INDICES WILL NOT REACH ADVISORY CRITERIA...DO NOT PLAN TO DROP THE ADVISORY. THE THREAT OF CONVECTION WILL GRADUALLY INCREASE ACROSS THE SERN CWA SATURDAY WITH THE APPROACH OF THE REMNANTS OF TROPICAL STORM ERIN. AS PER STLT...THE CIRCULATION STILL APPEARS RATHER IMPRESSIVE IN SWRN TX. BELIEVE THE GFS/NAM IS TOO WEAK AND DISORGANIZED WITH THIS FEATURE AND PREFER THE STRONGER UKMET/ECMWF. THE CAP WILL BE RATHER WEAK ACROSS THE SERN CWA SATURDAY AFTN WITH SCATTERED CONVECTIVE DEVELOPMENT LIKELY DURING PEAK AFTN HEATING. WARMER MID LVL TEMPERATURES AND A LITTLE STRONGER CAPPING WILL KEEP THE CONVECTION ISOLATED ACROSS THE REST OF THE CWA. AS THE UPPER SHEAR ZONE DRIFTS NORTH IN KANSAS AND SRN MO SATURDAY NIGHT...THE THREAT OF CONVECTION WILL SPREAD NORTH. COPIOUS MOISTURE IN A WEAKLY CAPPED ENVIRONMENT WILL PROVIDE FOR A THREAT OF OF CONVECTION FOR MOST OF THE CWA ON SUNDAY. DB && .AVIATION... FOR THE 18Z TAFS...WITH LINGERING BOUNDARIES AND DAYTIME HEATING...SOME ISOLATED STORMS ARE POSSIBLE DURING THE AFTERNOON AND EARLY EVENING HOURS. CONFIDENCE IS LOW IN THE INITIATION AND COVERAGE OF ANY CONVECTION...THEREFORE NO THUNDER WILL BE ADDED TO THE TAFS...BUT WILL DENOTE SCATTERED CB DEVELOPMENT. BOUNDARY EXPECTED TO LIFT A LITTLE NORTH AND EAST THIS AFTERNOON AND EVENING...HOWEVER TAF SITES WILL REMAIN UNDER A MOIST...E-SE SURFACE FLOW REGIME. SIMILAR TO LAST NIGHT...EXPECT LIGHT HAZE AND BR TO DEVELOP LATE TONIGHT...WITH A BRIEF PERIOD OF IFR FOG NOT OUT OF THE QUESTION. NAM/LOCAL WRF/RUC DEPICTING WEAK ISENTROPIC FORCING ALONG THE 308-310K SURFACES...WITH A BULLSEYE OF PRESSURE ADVECTION RIGHT OVER THE TOP OF TERMINAL SITES. DECIDED TO INTRODUCED VCSH AROUND 10-11 UTC ALL TERMINAL SITES TO ACCOUNT FOR POTENTIAL ELEVATED DEVELOPMENT. SF && .EAX WATCHES/WARNINGS/ADVISORIES... MO...HEAT ADVISORY UNTIL 7 PM FRIDAY FOR MOZ028-MOZ029-MOZ037- MOZ038-MOZ039-MOZ040-MOZ043-MOZ044-MOZ045-MOZ046-MOZ053-MOZ054. DENSE FOG ADVISORY UNTIL 9 AM FRIDAY FOR MOZ001-MOZ002-MOZ003- MOZ004-MOZ005-MOZ006-MOZ007-MOZ008-MOZ011>017-MOZ023>025. KS...HEAT ADVISORY UNTIL 7 PM FRIDAY FOR KSZ057-KSZ060-KSZ103- KSZ104-KSZ105. $$ mo AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 928 PM MDT THU AUG 16 2007 .UPDATE...LOWERED OR REMOVED POPS FROM THE W AND NC ZONES...AS WELL AS THE FAR SE ZONES FOR LATE TONIGHT. REMAINDER OF FORECAST LOOKS GOOD. 40 && .PREV DISCUSSION...253 PM MDT THU AUG 16 2007 WATER VAPOR LOOP WITH SUPPORT FROM LATEST 400-250MB AIRCRAFT WIND PLOT SHOWS A WEAK UPPER LEVEL DISTURBANCE AROUND 300MB PUSHING SLOWLY NW ACROSS CENTRAL NM. CONVECTION HAS FIRED ACROSS THE NORTHERN AND WESTERN MTNS AHEAD OF THIS DISTURBANCE WITHIN A WEAKLY UNSTABLE ATMOSPHERE PER LATEST SPC MESOANALYSIS. 20Z SFC ANALYSIS SHOWS A 1006MB LOW PRES TROUGH OVER THE WESTERN HALF OF THE STATE STRETCHING NE INTO SE CO AND NE NM. 18Z RUC/12Z NAM/GFS ALONG WITH HPC QPF FIELD INDICATES SHOWERS AND STORMS WILL DEVELOP ALONG THE BNDRY THIS EVE OVER NE NM FROM KRTN EAST TO KCAO. LEFT SLIGHT CHANCE POPS IN THIS AREA WITH BETTER CHANCE POPS FURTHER WEST WHERE ONGOING CONVECTION SHOULD CONTINUE INTO THE EARLY EVE HOURS. SIDED WITH THE 12Z GFS/MM5/ECMWF MODELS FOR THIS FORECAST PACKAGE PER NHC AND HPC COORDINATION REGARDING REMNANTS OF ERIN. COMPLICATED SCENARIO TO DEVELOP OVER THE CWFA AS THE REMNANT LOW FROM ERIN MOVES NW TOWARD W TX/E NM THROUGH FRI/SAT WHILE MID AND UPPER LEVEL HIGH PRES BUILDS OVER AZ. LOW LEVEL MOISTURE WILL SURGE NW INTO THE E PLAINS FRI WITH SHOWERS AND STORMS BREAKING OUT AHEAD OF THE AREA OF LOW PRES. THINK THE BEST CHANCE FOR PRECIP WILL BE OVER THE FAR SE PLAINS AS THE 700MB TRANSPORT REMAINS EASTERLY BEFORE SHUTTING DOWN SAT AS RIDGING BUILDS FARTHER TO THE WEST. LEFT CHANCE POPS FOR SE PLAINS WITH QPF AMOUNTS BTWN 0.25-0.50 OVER E CHAVES...ROOSEVELT...AND CURRY COUNTIES TO REFLECT POSSIBILITY FOR HEAVY RAINFALL IF INDEED SYSTEM PUSHES FARTHER WEST THAN FCST. LOWERED MAX TEMPS/RAISED MIN TEMPS IN THE SE BENEATH CLOUD SHIELD ASSCD WITH CONVECTION. MODELS THEN SHOVE REMNANTS OF ERIN SW INTO NORTHERN MEXICO BENEATH THE RIDGE WITH STRONG DRYING NOTED FROM 700-500MB OVER THE NW CORNER OF STATE. LEFT BEST POPS IN THE HIGHER TERRAIN FOR NEXT WEEK WITH TEMPS REBOUNDING TO SLIGHTLY ABOVE NORMAL IN MANY AREAS. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 63 94 63 95 / 20 20 20 20 GALLUP.......................... 55 89 56 89 / 20 20 20 10 GRANTS.......................... 53 88 54 88 / 10 20 20 10 GLENWOOD........................ 59 89 60 90 / 20 20 10 10 CHAMA........................... 53 82 47 83 / 30 30 30 20 LOS ALAMOS...................... 56 85 55 86 / 20 20 10 10 RED RIVER....................... 42 75 43 75 / 30 30 20 20 TAOS............................ 51 86 52 88 / 20 20 20 20 SANTA FE........................ 61 88 57 89 / 20 20 20 10 SANTA FE AIRPORT................ 60 90 58 91 / 10 10 10 10 ESPANOLA........................ 59 91 58 92 / 10 10 10 10 ALBUQUERQUE HEIGHTS............. 70 92 68 94 / 5 10 10 10 ALBUQUERQUE VALLEY.............. 63 93 64 96 / 5 10 10 10 ALBUQUERQUE FOOTHILLS........... 65 90 65 91 / 10 20 10 10 ALBUQUERQUE WEST MESA........... 64 93 65 93 / 10 10 10 10 SOCORRO......................... 63 93 63 94 / 5 10 10 10 SANDIA PARK/CEDAR CREST......... 57 85 57 86 / 10 20 10 10 MORIARTY/ESTANCIA............... 53 90 55 91 / 5 20 10 10 CARRIZOZO....................... 62 88 62 89 / 5 10 10 10 RUIDOSO......................... 58 79 57 77 / 10 20 20 10 RATON........................... 54 87 54 87 / 20 20 10 10 LAS VEGAS....................... 53 86 52 85 / 10 20 10 10 ROY............................. 61 85 60 84 / 10 10 10 10 CLAYTON......................... 61 89 62 88 / 10 10 10 20 SANTA ROSA...................... 62 91 63 89 / 5 10 10 10 TUCUMCARI....................... 65 91 66 90 / 0 10 20 20 FORT SUMNER..................... 59 87 63 86 / 0 20 20 20 CLOVIS.......................... 63 85 65 85 / 0 20 30 30 PORTALES........................ 63 85 66 84 / 0 20 30 30 ROSWELL......................... 66 88 68 87 / 5 20 20 20 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 150 PM EDT SAT AUG 18 2007 .SYNOPSIS... A HIGH PRESSURE SYSTEM IS SETTLING INTO THE AREA TODAY. WITH THIS SYSTEM A NORTHWEST AIR FLOW WILL BRING IN COOL AND DRY AIR FROM CANADA. THIS WILL BRING PARTLY CLOUDY SKIES UNTIL SUNDAY NIGHT WHEN A WARM FRONT APPROACHING FROM THE WEST WILL BRING IN MORE CLOUDS AND A CHANCE OF SHOWERS TO NORTHEAST PENNSYLVANIA. IN GENERAL...TEMPERATURES WILL START OFF THE WEEKEND BELOW NORMAL WITH SUNDAY MORNING LOWS IN THE 40S...THEN DAYTIME TEMPERATURES WILL WARM INTO THE 70S AGAIN BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE IMAGERY SHOWS STRATOCUMULUS CLOUDS OVER MUCH OF OUR NORTHERN AND EASTERN ZONES AS OF THIS WRITING. AS A COOL NORTHWESTERLY FLOW CONTINUES TO PICK UP MOISTURE OFF LAKE ONTARIO AND FLOW UPSLOPE...CLOUDS SHOULD PREVAIL THIS MORNING. RUC SOUNDING PROFILES SHOW LOW-LEVEL DRYING TAKING HOLD DURING THE EARLY TO MID-AFTERNOON...SO THE CLOUDS SHOULD BREAK UP BY THIS TIME. IN GENERAL...CLOUDY TO PARTLY SUNNY CONDITIONS SHOULD YIELD TO INCREASING SUNSHINE AS THE AFTERNOON PROGRESSES FOR MUCH OF THE FORECAST AREA. OVER THE WESTERN FINGER LAKES REGION AND DOWN INTO THE WYOMING AND LACKAWANNA VALLEYS IN PA...SUNSHINE SHOULD BE THE RULE TODAY. NEAR-TERM SKY COVER GRIDS WERE ADJUSTED OWING TO ABOVE REASONING. WIND...WIND GUST...AND TEMPERATURE GRIDS WERE ALSO TWEAKED SLIGHTLY. OTHERWISE...NO CHANGES FROM CONTINUITY. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... HIGH PRESSURE CRESTS OVERHEAD TONIGHT...AND WITH LIGHT WINDS AND COLD AIRMASS IN GENERAL...OVERNIGHT LOWS WILL BE CONSIDERABLY BELOW NORMAL...POSSIBLY NEAR RECORD. ONE WRINKLE TO THAT COULD BE HIGH CLOUDS FROM ANY UPSTREAM CONVECTION STREAMING IN LATE WHICH IS BEING INDICATED BY GFS/NAM RH PROGS. THE FORECAST GETS A LITTLE MORE INTERESTING TOWARD 00Z MONDAY AND BEYOND THROUGH TUESDAY. GFS/NAM/GEM AND GGEM ALL AGREE THAT A CONFLUENT ZONE WILL SET UP OVER ERN CANADA AND NEW ENGLAND...WITH SFC HIGH PRESSURE REINFORCING ITSELF OFF TO OUR NORTHEAST. MEANWHILE...FLAT RIDING ALOFT WILL BE DEVELOPING OVER THE WESTERN GTLKS BY TUESDAY.IN BETWEEN...A RATHER STRONG BAROCLINIC ZONE IS EXPECTED TO DEVELOP AND NUDGE EASTWARD TO EXTEND FROM MICHIGAN- WRN PA-MARYLAND BY TUESDAY MORNING. THIS FRONTAL ZONE SHOULD BE FAIRLY ACTIVE AS MOISTURE ADVECTING IN FROM TROPICAL REMNANTS IN TEXAS...AND ALSO FROM EASTERLY FLOW AROUND THE NEW ENGLAND HIGH PRESSURE CELL WILL BE FEEDING INTO THE RIGHT ENTRANCE REGION OF STRONG 200 MB JET ABOVE. THE BIGGEST QUESTION IS HOW FAR NORTH WILL THESE PARAMETERS REACH TO CAUSE RAINFALL...AS THE DRY HIGH OVER NEW ENGLAND FILTERS BACK TOWARD THE SOUTHWEST. HAVE NOTED A GENERAL SENSE IN THE MODELS TOWARD A DRYER TREND IN NY...WHILE NEPA MAY SEE MORE CLOUDS AND A LITTLE LIGHT PRECIP FROM TIME TO TIME SUNDAY NIGHT INTO TUESDAY. THE ENSEMBLES WOULD SUGGEST A WETTER SOLUTION AND FURTHER NORTH...BUT WITH THE EXCEPTION OF NORTHEAST PA...I SEE LITTLE INDICATION OF THAT IN OPERATIONAL RUNS OF NAM/GFS/GEM/GGEM. HAVE THUS NUDGED THE FORECAST TOWARD THAT DRIER DIRECTION...WITH MAIN FOCUS FOR ANY PRECIP CONFINED TO THE SRN BORDER COUNTIES IN NY...AND ACROSS NEPA WHERE HIGHEST (BUT STILL CHANCE FOR NOW) RAIN PROBABILITY WILL EXIST. CONVECTIVE INDICES ALL APPEAR TO BE STABLE... SO HAVE REMOVED MENTION OF THUNDER THROUGH TUESDAY. THINGS TO CONSIDER...A WEAKER HIGH IN NEW ENGLAND...OR EVEN SLIGHTLY MORE NEWD PUSH BY THE WARM FRONT WILL MAKE A HUGE DIFFERENCE FOR NEPA/CNY FORECASTS...NOT ONLY IN COVERAGE OF RAINFALL...BUT ALSO INTENSITY AND QPF AMOUNTS FOR MY AREA. CONFIDENCE IN THIS FORECAST...ESPECIALLY SOUTHERN HALF OF THE AREA IS RATHER LOW. GENERALLY ACCEPTED A BLENDED MOS GUIDANCE AS THERMAL FIELDS GRADUALLY WARM UP...BUT WILL BE TEMPERED BY CLOUDS IN THE SOUTH. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... FRONTAL BOUNDARY HANGING TO OUR SOUTHWEST LIFTS TO THE NORTHEAST EARLY IN THE PERIOD. THIS BOUNDARY PROGGED TO HANG OUT JUST NORTH OF THE FORECAST AREA WITH A SERIES OF WAVES RIPPLING ALONG IT THAT WILL KEEP AT LEAST LOW CHC FOR SHRA IN THE FORECAST MUCH OF THE TIME...AS IT IS TOO DIFFICULT TO TIME ANY BEST PRECIP CHC TIMES THIS FAR OUT. OTHERWISE...UPPER RIDGE CENTERED OVER THE SE U.S. WILL KEEP MILD TEMPS ACROSS THE AREA WITH SLOW WARMING TREND BY WEEKS END, BEFORE TROF TRIES TO DIG SWD AND SUPPRESS RIDGE FURTHER SOUTH. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR CONDITIONS THRU THE PERIOD. ANY DIURNAL CU WILL DISSIPATE LATE THIS AFTN...LEAVING MAINLY CLEAR SKIES THIS EVENING WITH INCREASE IN HIGH AND MID CLDS OVERNIGHT...ESP ACROSS ELM, AVP. HAVE LEFT FOG OUT OF ELM AT THIS POINT, GIVEN EXPECTED BKN HIGH CLDS...BUT SHOULD CLDS BE LESS THAN ANTICIPATED, FOG COULD BECOME HIGHER PROBABILITY LATE TONIGHT INTO EARLY SUNDAY. SCT/BKN MID AND HIGH DECK CONTINUES THRU SUNDAY MORNING. JUST SMALL CHC FOR LGT SHRA OR SPRINKLE AT ELM AND AVP. NWLY WINDS AROUND 10 KTS GUSTS TO 20 KTS THIS AFTN WILL BECOME LIGHT THIS EVENING. FOR MONDAY THROUGH THURSDAY... VFR CONDITIONS UNDER HIGH PRESSURE CONTINUE FOR MONDAY, OUTSIDE OF POTENTIAL MORNING FOG AT ELM. A WARM FRONT JUST SOUTHWEST OF THE FA COULD BRING SOME LIGHT SHRA TO THE TAF SITES TUESDAY NIGHT INTO WEDNESDAY. NO WORSE THAN MVFR RESTRICTIONS EXPECTED. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 126 AM EDT SAT AUG 18 2007 .SYNOPSIS... A COLD FRONT WILL PUSH THROUGH THE REGION TONIGHT. THIS SYSTEM WILL BRING SCATTERED SHOWERS TO THE AREA OVERNIGHT...FOLLOWED BY A SHOT OF COOL AND DRIER AIR. THIS INCOMING AIR MASS WILL BRING A PARTLY CLOUDY AND DRY WEEKEND...WITH HIGHS IN THE UPPER 60S AND 70S. AN APPROACHING WARM FRONT WILL BRING THE CHANCE OF SHOWERS OR THUNDERSTORMS BACK INTO THE AREA FROM LATER SUNDAY NIGHT INTO MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... VERY UNUSUAL SEVERE WEATHER EVENT DEVELOPED ACROSS THE AREA THIS EVENING. STRONG UPPER LEVEL SHORT WAVE MOVING ACROSS THE AREA IN NORTHWEST FLOW RESULTED IN A LINE OF THUNDERSTORMS DEVELOPING OVER THE FINGER LAKES AND CENTRAL SOUTHERN TIER OF NEW YORK EARLY THIS EVENING. REFLECTIVITY RETURNS WITH THESE STORMS WERE NOT VERY IMPRESSIVE... ESPECIALLY AS THEY MOVED EAST ACROSS NORTHEAST PA AND THE WESTERN CATSKILLS... HOWEVER A FAVORABLE ENVIRONMENT FOR DOWNBURST WINDS... AS INDICATED BY INVERTED V RUC SOUNDINGS... RESULTED IN NUMEROUS DAMAGING WIND REPORTS. THE PRIMARY LINE OF STORMS HAS NOW MOVED SOUTHEAST OF THE CWA... HOWEVER SCATTERED SHOWERS WITH EVEN SOME EMBEDDED THUNDER CONTINUE TO DEVELOP UPSTREAM ACROSS CENTRAL NEW YORK. LATEST RUC SOUNDING AT SYR SHOWS DEEP LAYER CAPE GONE BY AROUND MIDNIGHT AS VERY DRY AIR ADVECTS INTO THE AREA IN NW FLOW. LOW-LEVEL INVERTED V SIGNATURES ARE ALSO NO LONGER IN PLACE... SO DO NOT EXPECT THESE SHOWERS TO CAUSE THE PROBLEMS THAT OUR EARLIER STORMS DID. ANY SHOWERS SHOULD BE GONE BEFORE SUNRISE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES REGION OVER THE WEEKEND. THIS SYSTEM IS STILL EXPECTED TO BRING RAIN-FREE AND COOL CONDITIONS. HIGHS WILL RANGE FROM THE UPPER 60S TO MID 70S...WITH EARLY MORNING LOWS WELL DOWN INTO THE 40S. A FEW MID TO UPPER 30S ARE EVEN POSSIBLE EARLY SUNDAY IN NORMALLY COLDER SECTIONS. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... FOLLOWED HPC GUIDANCE. UPPER PATTERN BECOMES MORE FLAT RIDGE ACROSS THE EAST NEXT WEEK WITH FASTER ZONAL FLOW IN PLACE OVER NY/PA. LAST COUPLE OF RUNS FROM THE GFS KEEP WAVY FRONTAL BOUNDARY SOUTH OF THE AREA THROUGH ABOUT TUESDAY BEFORE LIFTING THE FRONT NORTH ACROSS THE AREA THAT WILL KEEP CHCS FOR PRECIP THRU THE END OF THE PERIOD. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR EXPECTED THROUGH THE PERIOD. A 4KFT STCU DECK IS EXPECTED TO IMPACT SYR/RME THROUGH THE EARLY MORNING...BEFORE IT SCATTERS OUT BY MID MORNING ON SATURDAY. SCT CU AROUND 5KFT EXPECTED AGAIN TODAY...FALLING APART AFTER SUNSET WITH SOME HIGH CLOUDS LEFTOVER FOR THE OVERNIGHT. WINDS NORTHWESTERLY 5-10KTS OVERNIGHT BEFORE INCREASING TO 12G18KTS BY MID MORNING. NORTHWEST WINDS SLACKENING AFTER SUNSET TO 5KTS OR LESS. FOR SUNDAY THROUGH WEDNESDAY... VFR CONDITIONS UNDER HIGH PRESSURE CONTINUE FOR SUNDAY /OUTSIDE OF POTENTIAL MORNING FOG AT ELM/ WITH AN OUTSIDE SHOT OF A SHRA AT ELM/AVP. FOR MONDAY-WEDNESDAY...A WARM FRONT JUST SOUTHWEST OF OUR CWA COULD BRING SHRA TO ELM/AVP AND POSSIBLY TO ITH/BGM WITH NO WORSE THAN MVFR RESTRICTIONS EXPECTED. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MSE NEAR TERM...MSE SHORT TERM...MLJ LONG TERM...JML AVIATION...JMA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 436 PM EDT FRI AUG 17 2007 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT AND MOVE OFFSHORE EARLY SATURDAY MORNING. HIGH PRES WILL BUILD IN BEHIND THE FRONT AND REMAIN OVER THE AREA THROUGH MIDWEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AIR MASS ACROSS THE AREA HAS NOT DESTABILIZED AS PREVIOUSLY THOUGHT DUE TO EXTENSIVE CLOUD COVER FROM EARLY MORNING CONVECTION UPSTREAM WITH TEMPERATURES ONLY ABLE TO CLIMB INTO THE UPPER 80S AND LOWER 90S ACROSS THE AREA. LATEST WATER VAPOR IMAGERY INDICATES MUCH DRIER AIR FILTERING IN FROM THE NORTHWEST IN ASSOCIATION WITH STRONG SUBSIDENCE. A VERY MOIST AIRMASS REMAINS IN PLACE ACROSS EASTERN NORTH CAROLINA AHEAD OF THE FRONTAL BOUNDARY THAT HAS JUST CROSSED THE MOUNTAINS. MODEL GUIDANCE STILL SHOWS PRECIP DEVELOPING OVER THE AREA THIS EVENING WITH THE BULK OF ACTIVITY ALONG AND EAST OF THE HIGHWAY 17 CORRIDOR. THE RUC IS MOST BULLISH WITH PRECIP WHILE THE GFS IS THE DRIEST. WILL DECREASE POPS TO SLIGHT CHANCE FAR WEST AND OUTER BANKS EARLY THIS EVENING WITH CHANCE ELSEWHERE THEN CHANCE POPS EAST LATE TONIGHT INTO EARLY SATURDAY MORNING AS FRONT MOVES INTO THE AREA. SEVERE THREAT APPEARS TO BE DWINDLING AS TEMPS COOL WITH LOSS OF HEATING HOWEVER A FEW STORMS MAY STILL PRODUCE SOME LOCALLY GUSTY WINDS. SKIES WILL BE PARTLY CLOUDY FOR THE MOST PART THIS EVENING THEN CLEARING FROM WEST TO EAST LATE TONIGHT INTO EARLY SAT. MIN TEMPS WILL RANGE FROM THE LOW AND MID 70S INLAND TO THE UPPER 70S BEACHES AND OUTER BANKS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... CLEARING SKIES ON SATURDAY AS HIGH PRES BUILDS INTO THE AREA. WENT WITH A MOS BLEND FOR TEMPS IN THE SHORT TERM WITH HIGHS IN THE UPPER 80S TO LOWER 90S SATURDAY THEN SLIGHTLY COOLER ON SUN WITH SEASONAL TEMPS IN THE UPPER 80S. LOWS WILL BE IN THE UPPER 60S TO LOWER 70S SUN WITH MONDAY MORNING TEMPS MOSTLY IN THE LOW/MID 70S. && .LONG TERM /MONDAY THROUGH FRIDAY/... MID/UPPER LEVEL RIDGE WILL SET UP OVER THE SOUTHEAST THROUGH THE PERIOD...STILL KEEPING EASTERN NC IN TYPICAL SUMMERTIME REGIME. HIGH TEMPS INLAND THROUGH FRIDAY GENERALLY IN THE LOW 90S AND MID TO UPPER 80S ALONG THE COAST. OVERNIGHT LOWS IN THE LOW TO UPPER 70S. JUST ABOVE CLIMO. BETWEEN SFC TROUGH AND SEA BREEZE DEVELOPMENT...HAVE SLIGHT/ISOLATED CHANCE SHOWERS/TSTORMS IN FORECAST EVERY AFTERNOON. NO SIGNIFICANT RAIN EXPECTED THROUGH FRIDAY. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... GUSTY SWLY FLOW ACROSS RTES THIS AFTERNOON AHEAD OF A FRONTAL BOUNDARY THAT IS ACROSS THE WESTERN PIEDMONT LATE THIS AFTERNOON. CONVECTIVE ACTIVITY RELATIVELY QUIET ACROSS ERN NC AS MID LEVEL CLOUDS LIMITED SFC HEATING TDA BUT SUFFICIENT INGREDIENTS EXSIST FOR AT LEAST ISOLATED CONVECTION TO DEVELOP ACROSS RTES THROUGH THE EVENING AS THE FRONT APPROACHES. WINDS SHOULD KEEP THE AIRMASS MIXED ENOUGH TO PREVENT FOG FROM DEVELOPING THROUGH MUCH OF THE NIGHT HOWEVER GUIDANCE IS SUGGESTING WINDS DROPPING OFF LATE TONIGHT AND A FEW HOURS OF PATCHY FOG BRINGING IFR/MVFR VSBYS AROUND DAYBREAK. THE FRONT WILL BE S OF THE REGION SAT MORNING WITH VFR CONDITIONS AND N-NELY FLOW ACROSS RTES THROUGH THE DAY. MAINLY VFR CONDITIONS THROUGH THE REST OF THE FORECAST PERIOD OUTSIDE OF PATCHY LATE NIGHT FOG EACH NIGHT AND ISOLATED DIURNAL CONVECTION MON THROUGH WED. && .MARINE... MODERATE SWLY FLOW CONTINUES ACROSS THE WATERS THIS EVENING AS A FRONTAL BOUNDARY APPROACHES FROM THE WEST. STRONGEST WINDS/SEAS HAVE BEEN AT DIAMOND BUOY WITH GUSTS UP TO 30 KT AND SEAS TO 8 FT BUT MOST OF THE WATERS HAVE REACHED SCA CONDITIONS THIS AFTERNOON WITH SEAS UP TO 6 FT AND GUSTS TO 25 KT. THE FRONT WILL PUSH INTO THE NORTHERN WATERS LATE TONIGHT AND S OF THE AREA BY MID MORNING SAT WITH N-NELY WINDS DEVELOPING ACROSS THE WATERS. MODELS AGREE WITH POST FRONTAL WINDS AROUND 15-20 KTS THROUGH SAT AS SLOWLY DIMINISHING SAT NIGHT. SEAS ARE EXPECTED TO DROP BELOW 6 FT ACROSS ALL WATERS BY MIDDAY SAT AND HAVE KEPT CURRENT ADVISORIES IN PLACE. HIGH PRES WILL BUILD INTO THE WATERS SAT NIGHT AND SUN...AND MOVE OFFSHORE SUN NIGHT ALLOWING A WARM FRONT TO LIFT N ACROSS THE REGION. WINDS WILL SHIFT TO SLY BEHIND THE FRONT AND ARE EXPECTED TO CONTINUE WITH A MAINLY SLY COMPONENT AS HIGH PRES REMAINS SE OF THE WATERS WITH A THERMAL TROUGH EXISTS ACROSS THE PIEDMONT. DISTANT LONG PERIOD SWELL FROM HURRICANE DEAN HAS STARTED TO SHOW UP AT A FEW BUOYS ALONG THE COAST THIS AFTERNOON. IT IS INITIALLY ONLY AROUND A FOOT AND IS MASKED BY THE BIGGER WIND WAVES TODAY BUT THE SWELL IS EXPECTED TO BUILD THROUGH THE REMAINDER OF THE WEEKEND TO AROUND 4 FT SUNDAY EVENING AND BECOME DOMINANT AS WINDS DIMINISH SAT NIGHT. LONG PERIOD SWELL IS EXPECTED TO PERSIST THROUGH THE FORECAST PERIOD. .RIP CURRENTS...LONG PERIOD SWELL WILL CONTINUE TO SLOWLY BUILD THROUGH THE WEEKEND AND WITH INCREASED WAVE ENERGY COMES A GREATER RISK OF RIP CURRENTLY. HIGH ENERGY SWELLS AROUND A FOOT WITH E-NELY ONSHORE WINDS 15-20 KT WILL BRING A MODERATE RISK OF RIP CURRENTS ALONG THE ENTIRE COAST SAT. SWELLS WILL INCREASE TO 3 TO 4 FT SUN AND CONTINUE INTO MIDWEEK AND A MODERATE TO HIGH RIP CURRENT RISK IS EXPECTED THROUGH THE PERIOD. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SATURDAY FOR AMZ135-158. SMALL CRAFT ADVISORY UNTIL 11 AM EDT SATURDAY FOR AMZ150-152- 154-156. && $$ SYNOPSIS...JW NEAR TERM...JW SHORT TERM...JW LONG TERM...CLQ AVIATION...SK MARINE...SK nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 405 AM EDT FRI AUG 17 2007 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN TODAY AND SATURDAY WITH DRIER AND COOLER WEATHER EXPECTED. A WARM FRONT WILL LIFT NORTH THROUGH THE OHIO VALLEY SUNDAY AND MONDAY...BRINGING A RETURN TO WARMER TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... WHILE MAIN FRNTL BNDRY APPEARS TO HAVE MOVED SOUTH OF THE OHIO RIVER...SECONDARY CONV BNDRY NOTED FROM SE INDIANA NE ALONG I-71 TO NEAR KCMH. A FEW TSTMS HAVE DVLPD WITHIN THE LAST HOUR ALONG THIS BNDRY...BTWN KILN AND KCMH. 03Z RUC INDCG SFC CONV AND INSTABILITY AXIS WILL DIMINISH THRU DAYBREAK AS IT SHIFTS SE ACRS FCST AREA. HAVE LEFT A VERY LOW PRECIP CHANCE FOR ISOLD CONVECTION BTWN NOW AND 12-13Z ALONG AND EAST OF I-71. TEMPS REMAINED IN THE 70S ERLY THIS MRNG WITH DEWPTS HOVERING NEAR OR JUST BLO 70 DEG. LKLY TO SEE SOME PATCHY FOG THRU DAYBREAK...ESPECIALLY IN AREAS THAT SAW RAINFALL THURS AFTN/EVNG. WV SAT SHWNG VERY NICELY DRIER AIRMASS PUNCHING INTO REGION FROM NORTHWEST. THE DRIER AIR BEING DELAYED SOMEWHAT BY AFOREMENTIONED CONV AXIS HELPING TO KICK OFF ISOLD TSTMS THIS MRNG. ONCE CONV AXIS PASSES...BNDRY LYR FLO BECOMES NRLY AND INCREASES THRU MID MRNG. THIS WILL HELP TO PUSH SC DECK SOUTH THRU DAYBREAK AND ALLOW DRIER AIR TO FILTER INTO REGION. DRIER AIR WILL CONTINUE TO FUNNEL INTO FCST AREA THRU THE DAY AS SFC HI PRES BUILDS SOUTH FROM WRN GRT LKS. MID LVL HGTS WILL FALL ACRS REGION AS S/WV PASSES THRU LWR GRT LKS THIS AFTN/EVNG. THIS WILL ENSURE COOLER TEMPERATURES THIS AFTN...AT LEAST IN THE CONTEXT OF TEMPS OVER THE LAST FEW DAYS AND WEEKS. EXPECT FEW/SCT CU LATER THIS MRNG AND AFTN BUT WITH WEAK LO LVL CAA AND PROGRESSIVELY DRIER AIR OVERSPREADING REGION...SHOULD SEE MSTLY SUNNY SKIES. MODEL SOUNDINGS SUPPORT SOME DECENT MIXING THRU BNDRY LYR THIS AFTN..AND EXPECT NRLY WINDS IN THE 10-15 MPH (ESPECIALLY ACRS NRN 1/2 FCST AREA). SFC HI WILL FURTHER SETTLE OVER REGION TONIGHT...SETTING STAGE FOR EXCELLENT RADIATIONAL COOLING WITH CLR SKIES AND LGT WINDS. TEMPS...AS HAS BEEN CUSTOMARY IN RECENT WEEKS...FAVOR THE WARMER END OF GUID TEMPS FOR TODAY. WITH PLENTY OF SUNSHINE LATER TODAY...EXPECT M/U80S FOR AFTN HIGHS. HAVE PENCILED IN AN 88 FOR KCVG TODAY BUT CONSIDERING HOW DRY IT IS AND CONSEQUENTLY HOW EASY A TIME KCVG HAS HAD IN WARMING...NOT OUT OF THE QUESTION THAT KCVG GETS TO 90 THIS AFTN. TEMPS SHOULD DROP NICELY TONIGHT WITH MOST LOCATIONS DROPPING INTO THE 50S. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... ANOTHER SPLENDID DAY ON THE DOCKET FOR SAT AS SFC HI REMAINS ANCHORED ACRS REGION. ALTHOUGH AFOREMENTIONED S/WV WILL SHIFT INTO NEW ENGLAND...MID LVL NW FLO WILL DOMINATE AS UPR RIDGE RETROGRADES BACK INTO CNTRL/HI PLAINS AND ROCKIES. SFC LO ACRS NRN PLAINS WILL SHIFT SLOWLY EAST SAT AFTN/NIGHT AS A WARM FRONT DVLPS AND EXTENDS SE INTO THE REGION. MID LVL FLO PATTERN WILL DEAMPLIFY SAT NIGHT AS BROAD RIDGE BEGINS TO EXPAND BACK EAST TOWARDS REGION. BOTH 00Z NAM/GFS INDCG DVLPG 850 LLJ OVER UPR MIDWEST BY SAT EVNG WITH AN MCS DVLPG AND PROPAGATING E/SE OVER TOP OF RIDGE INTO THE GRT LKS. WITH BROAD SUBSIDENCE AND PREDOMINANT E/SE FLO ACRS REGION SAT NIGHT...HAVE PULLED POPS FROM ALL BUT WEST CNTRL OH. WHILE MAIN FORCING SUPPORTS MCS AFFECTING AREAS NORTH OF FCST AREA...CANNOT RULE OUT FAR NRN FCST AREA BEING CLIPPED TOWARDS DAYBREAK SUN. AT VERY LEAST...EXPECT CI AND EVENTUALLY AC FROM TSTMS TO OVERSPREAD NRN FCST AREA SAT AFTN/NIGHT. WARM FRONT REMAINS DRAPED ACRS REGION SUN. BEST FORCING AND LOCATION OF WARM FRONT SUPPORT GREATER COVERAGE TO PCPN ACRS NRN OH...PROBABLY IN FORM OF REMNANTS OF AFOREMENTIONED MCS. MODEL SOUNDINGS CONTINUE TO SHOW PLENTY OF SUBSIDENCE THRU BNDRY LYR. PRESENCE OF MID LVL CAP ALL DAY SUN AS WELL WITH MID LVL HGTS WARMING AGAIN FROM SW WITH EXPANSION OF RIDGE. AS A RESULT...AM NOT OVERLY IMPRESSED WITH PCPN CHANCES FOR REGION. HAVE DROPPED BACK TO 30 POPS ACRS NRN FCST AREA...WITH ONLY ISOLD CONVECTION EXPECTED FURTHER SOUTH. DO NOT THINK ITS OUT OF THE QUESTION THAT CONDITIONS REMAIN DRY ACRS SRN 1/2 FCST AREA SUN WITH NO APPRECIABLE FORCING...A CAP AND CONSEQUENTLY NO INSTABILITY TO WORK WITH. ANOTHER WEAK WAVE DVLPG SUN NIGHT ALONG FRNTL BNDRY MAY BRING A SLIGHTLY BETTER CHANCE FOR TSTMS...ESPECIALLY ACRS NRN 1/2 FCST AREA AS DEEPER MOISTURE BEGINS TO ADVECT BACK INTO REGION ON SRLY WINDS. VARIOUS MODELS CONTINUING TO STRUGGLE WITH TIMING OF DISTURBANCES SO CONFIDENCE AT GREATER COVERAGE TO PCPN IS RELATIVELY LOW FOR SUN NIGHT ATTM. TEMPS...NICE GRADIENT OF 850 TEMPS AND BNDRY LYR THICKNESSES BISECTING FCST AREA ON SAT. EXPECT COOLER TEMPS AS A RESULT...WITH TEMPS POSSIBLY STAYING IN THE U70S ALONG AND NORTH OF I-70. FURTHER SOUTH L/M80S EXPECTED. AS RIDGE EXPANDS BACK INTO REGION SUN AND LO LVL WAA DVLPS...TEMPS WILL CLIMB BACK INTO M/U80S ACRS SRN FCST AREA. THIS MAY BE SETTING STAGE FOR ANOTHER STRING OF AFTN HIGHS NEAR OR ABV 90 IN THESE AREAS FOR NEXT WEEK. OVERNIGHT LOWS WILL GRADUALLY MODERATE BACK INTO THE 60S MOST LOCATIONS BY MON MRNG. && .LONG TERM /MONDAY THROUGH THURSDAY/... UPPER LEVEL RIDGE OVER THE CENTRAL UNITED STATES WILL GRADUALLY FLATTEN OUT THROUGH THE MIDDLE PART OF NEXT WEEK...ALLOWING FOR FLOW TO BECOME MORE ZONAL ACROSS OUR AREA. IN THE WESTERLY FLOW...A SERIES OF WEAK SHORT WAVES WILL PUSH EAST ACROSS THE REGION. TIMING IS DIFFICULT WITH THESE THOUGH SO THINK THE BEST WAY TO HANDLE IT AT THIS POINT IS TO GO WITH A GENERAL 30 POP FOR A GOOD PART OF THE EXTENDED. RIGHT NOW IT LOOKS LIKE BEST CHANCE FOR ANY PCPN WOULD BE MONDAY AND TUESDAY SO WILL ALLOW FOR CHANCE POPS THEN WITH A 20 POP BEYOND. LOW LEVEL THERMAL FIELDS WILL GRADUALLY INCREASE DURING THE FIRST HALF OF THE WEEK. WILL THEREFORE GO WITH A GRADUAL WARM UP WITH HIGH TEMPS INTO THE UPPER 80S AND LOWER 90S BY MIDWEEK. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOWING MIDDLE TO HIGH CLOUDS WILL BE EAST OF THE TERMINALS BY 07Z. MVFR FOG IS DEVELOPING OVER WESTERN SECTIONS OF OHIO AS MOISTURE FROM EARLIER STORMS OVER INDIANA ADVECTS ACROSS WEST CENTRAL OHIO BEFORE THE DRIER AIR BEHIND COLD FRONT MOVES INTO THE AREA DURING THE DAY ON FRIDAY. CONDITIONS OVER DAY EXPECTED TO LOWER TO IFR SHORTLY FOLLOWED WITHIN ONE OR TWO HOURS BY KILN. MVFR FOG ASSOCIATED WITH THE THUNDERSTORMS THAT MOVED ACROSS SOUTHERN OHIO AND NORTHERN KENTUCKY EARLIER WILL DEVELOP WITHIN THE HOUR KCVG AND KLUK AND FALL RAPIDLY TO IFR CVG AND LIFR KLUK. THIS FOG EXPECTED TO PRODUCE LIFR CEILING KLUK AND BRIEFLY CVG. MVFR FOG EXPECTED CMH AND KLCK A FEW HOURS BEFORE SUNRISE. BRIEF MVFR CEILINGS WILL MOVE ACROSS THE FORECAST AREA FOR THE FIRST TWO HOURS OF THE FORECAST PERIOD FOG WILL DISSIPATE MOST AREAS BY 13Z AND BE FOLLOWED BY ONE TO TWO HOURS OF MVFR HZ KDAY AND KILN SOUTHWARD. VFR EXPECTED ALL AREAS BY 15Z. AS HIGH PRESSURE CONTINUES TO BUILD ACROSS THE AREA FRIDAY DRIER AIR WILL SPREAD ACROSS THE AREA, THUS ONLY EXPECTING A FEW CU LATE AFTERNOON. OUTLOOK...TSTMS POSSIBLE MONDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM...CONIGLIO AVIATION...HAYDU oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 438 PM EDT FRI AUG 17 2007 .SYNOPSIS... A COLD FRONT WILL EXIT THE EASTERN ZONES LATER THIS EVENING WITH SCATTERED SHOWERS AND THUNDERSTORMS COMING TO AN END. MUCH DRIER AND COOLER AIR WILL MOVE INTO THE REGION FOR THE WEEKEND AS CANADIAN HIGH PRESSURE SLIDES SOUTH AND EAST FROM THE UPPER GREAT LAKES. UNSETTLED WEATHER CONDITIONS ARE EXPECTED NEXT WEEK WITH TEMPERATURES AND HUMIDITY ON THE RISE. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... SEVERE THUNDERSTORM WATCH #612 REMAIN IN EFFECT UNTIL 8 PM FOR OUR FAR EASTERN COUNTIES. LATEST SFC ANALYSIS PLACES CLD FNT FM THE ECENT MTNS SWD ALONG THE BLUE RIDGE MTNS WITH WARM FRONT EXTENDING EWD JUST NORTH OF I-80. RATHER MOIST PRE-FRONTAL WARM SECTOR AIRMASS ACROSS THE MIDDLE AND LOWER SUSQ VLY REMAINS THE FOCUS FOR ADDITIONAL ISOLD/SCT STRONG TO SVR CONVECTION THIS EVE WITH RUC SHOWING 1500-2000 J/KG CAPES IN THIS REGION. CONVECTION SHOULD DIE DOWN LATER TONIGHT AS THE FRONT CLEARS THE EASTERN ZONES. CU FIELD TO THE WEST WILL CRUMBLE TOWARD SUNSET WITH MUCH COOLER AND DRIER AIR FILTERING INTO THE REGION FROM THE NW. && .SHORT TERM /8 PM THIS EVENING THROUGH MONDAY NIGHT/... PW VALUES ARE FOREST TO DROP BELOW NORMAL TONIGHT OVER THE ENTIRE STATE SO HAVE GONE AOB THE COOLEST MOS. SREF 2M TEMPS STILL SHOW MANY LOCATIONS IN THE 40S ACROSS NORTHERN AND CENTRAL PA WITH COMFORTABLE 50S IN THE SOUTH/SOUTHEAST. NOTICEABLE CHANGE IN AIRMASS WILL BE FELT SATURDAY WITH BELOW NORMAL PW/S AND 925/850MB TEMPS...A TASTE OF FALL PERHAPS. MOSTLY SUNNY AND LOW HUMIDITY WITH TEMPS MAINLY IN THE 70S. SATURDAY NIGHT SHOULD BE ANOTHER PLEASANT NIGHT. CLOUDS COULD MOVE INTO WESTERN AREAS OVERNIGHT AS A SURGE OF MOISTURE HEADS OUR WAY AHEAD OF A WARM FRONT. CANNOT RULE OUT A SHOWER IN THE WEST BY SUNDAY MORNING. SUNDAY...THE PW VALUES RETURN TO NORMAL AND RISE ABOVE NORMAL IN THE WEST. GEFS SHOWS CHANCE OF SHOWERS/THUNDERSTORMS MAINLY IN THE WEST. MONDAY...A WEAK LOW-LEVEL BOUNDARY SHOULD BE OVER THE STATE. WARM MOIST AIR ON THE SOUTH SIDE AND COOLER DRIER AIR ON THE NORTH. EXPECT HIGH PROBS FOR PCPN GIVEN BETTER OVERALL PW AVAILABILITY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... TUES-THURS...ENSEMBLES CONTINUE TO SHOW PW VALUES TO BE ABOUT 1SD ABOVE NORMAL - SUGGESTING HUMID CONDITIONS AND CHANCES OF SHOWERS. BY TUESDAY OUR 850 HPA TEMPS ARE ABOVE NORMAL SUGGESTING HIGHS AOA CLIMO. LOOKS LIKE A RELATIVELY WARM HUMID PERIOD AND THUS UNSETTLED WITH PDS OF SHOWERS AND THUNDERSTORMS. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... COLD FRONT MOVING SOUTHEAST ACROSS THE STATE THIS AFTERNOON WILL BRING HIGHLY LOCALIZED IFR CIGS AND VSBYS IN STRONG TO SEVERE TSRA EAST OF A KIPT TO KSEG AND KMDT LINE THROUGH 21Z. COOLER AND LESS HUMID AIR WILL BRING WIDESPREAD VFR FLYING CONDITIONS TONIGHT THROUGH SATURDAY NIGHT. GUSTY WEST TO NORTHWEST SFC WINDS WILL CAUSE MECHANICAL TURBULENCE ON TAKEOFF AND FINAL APPROACH THROUGH ABOUT 01Z SATURDAY...BEFORE WINDS DECREASE TO LESS THAN 10 MPH. HIGH PRESSURE WILL BUILD IN FOR SAT WITH VFR FLYING EXPECTED. SUN-TUE LOOKS UNSETTLED WITH SEVERAL DISTURBANCES TAKING AIM ON THE REGION. AS THE MILDER/MOIST AIR MOVES OVER THE COOL AIRMASS OVER PENN...CLOUDS WILL GRADUALLY LOWER AND THICKEN SUNDAY...BUT FLYING CONDITIONS SHOULD BE MVFR AT WORST AS CLOUD BASES STAY AOB 3 KFT AGL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL/GRUMM LONG TERM...STEINBUGL/GRUMM AVIATION...LAMBERT/GARTNER pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 248 PM EDT FRI AUG 17 2007 .SYNOPSIS... A COLD FRONT WAS MOVING SLOWLY SOUTHEAST ACROSS THE REGION THIS AFTERNOON...AND WAS RESPONSIBLE FOR TRIGGERING A FEW SEVERE THUNDERSTORMS ACROSS THE SUSQUEHANNA VALLEY AND POINTS EAST WHERE VERY WAR AND HUMID AIR RESIDED. DRIER AND COOLER AIR WILL MOVE OVER THE REGION THROUGH SATURDAY NIGHT AS HIGH PRESSURE BUILDS SOUTHEAST ACROSS THE GREAT LAKES. MOISTURE AND NORTHWESTERLY FLOW ALOFT SUNDAY INTO MONDAY COULD INCREASE THE CHANCE OF SHOWERS. A WEAK UPPER LEVEL RIDGE SHOULD DOMINATE THE REGION BY MID-WEEK WITH WARM HUMID CONDITIONS. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... UPDATE FOR SVR THUNDERSTORM WATCH #612 EFFECTIVE UNTIL 8 PM FOR OUR FAR EASTERN COUNTIES. STORMS DEVELOPED RAPIDLY OVER NERN SECTIONS...AND PRODUCED LARGE HAIL AND STRONG WINDS IN LYCOMING/LANCASTER COS. SVR THREAT WILL CONTINUE INTO THE LATE AFTN/EARLY EVE INVOF OF WARM FRONT EXTNDG ACROSS ERN PA. UNIDIRECTIONAL DEEP LYR WIND FIELD OVER TOP THE LLVL BNDRY WILL SUPPORT ROTATING UPDRAFTS WITH SPLITTING LEFT MOVING CELLS ENHANCING HAIL POTENTIAL. THE COLD FRONT DRAPED ACROSS NRN PENN AT 1430Z WAS BEING TEMPORARILY DELAYED IN ITS SWD MVMT BY A WEAK WAVE OF LOW PRESSURE NEAR KIPT. NAM/RUC SHOW MIXED LAYER CAPE CLIMBING TO OVER 1000 J/KG ACROSS THE LOWER SUSQ VALLEY THIS AFTERNOON...WHICH IN THE PRESENCE OF WEAK LARGE SCALE FORCING AHEAD OF A SHORT WAVE HEADING SE FROM THE LWR GLAKES...SHOULD YIELD A FEW SHRA/TSRA /MAINLY NEAR AND TO THE SE OF INTERSTATE 81/. COOLER AND LESS HUMID AIR WILL ADVECT SE BEHIND THE FRONT LATE IN THE DAY...SWEEPING ANY CONVECTION SOUTH OF THE MASON/DIXON LINE. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/... HE FRONT SHOULD PUSH TO OUR SOUTH BY MIDDAY. THE COOLER AND DRIER AIR SHOULD PRODUCE A PLEASANT DAY WITH SKIES BECOMING MOSTLY SUNNY. OUR PW VALUES ARE FOREST TO DROP BELOW NORMAL BY EVENING OVER THE ENTIRE STATE. SHOULD BE COMFORTABLE AFTERNOON AND EVENING. VERY DRY AIR OVERNIGHT FRIDAY INTO SATURDAYS SUGGESTS A VERY COOL MORNING SATURDAY. SREF 2M TEMPS SHOW MANY LOCATIONS IN THE 40S ACROSS NORTHERN AND CENTRAL PA. COMFORTABLE 50S IN THE SOUTH/SOUTHEAST. SATURDAY SHOULD BE A MOSTLY SUNNY DAY WITH LOW HUMIDITY AND TEMPS MAINLY IN THE 70S. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... SATURDAY NIGHT SHOULD BE ANOTHER PLEASANT NIGHT. CLOUDS COULD MOVE INTO WESTERN AREAS OVERNIGHT AS A SURGE OF MOISTURE HEADS OUR WAY. CANNOT RULE OUT A SHOWER IN THE WEST BY SUNDAY MORNING. SUNDAY...THE PW VALUES RETURN TO NORMAL AND RISE ABOVE NORMAL IN THE WEST. GEFS SHOWS CHANCE OF SHOWERS/THUNDERSTORMS MAINLY IN THE WEST. MONDAY...A WEAK LOW-LEVEL BOUNDARY SHOULD BE OVER THE STATE. WARM MOIST AIR ON THE SOUTH SIDE AND COOLER DRIER AIR ON THE NORTH. HIGH PROB HAS MOST OF PA WITH ABOVE NORMAL PW AND CHANCE OF SHOWERS. TUES-THURS...OUR PW VALUES ARE FORECAST TO BE ABOUT 1SD ABOVE NORMAL SUGGESTING HUMID CONDITIONS AND CHANCES OF SHOWERS. BY TUESDAY OUR 850 HPA TEMPS ARE ABOVE NORMAL SUGGESTING IT WILL SHOULD BE SLIGHTLY WARMER THAN NORMAL TUE-THURS AS OUR 850 HPA TEMPS REMAIN ABOVE NORMAL. OUR 925 HPA TEMPS SHOULD BE SLIGHTLY ABOVE NORMAL. LOOKS LIKE A RELATIVELY WARM HUMID PERIOD AND THUS THE CHANCE OF SHOWERS AND THUNDERSTORMS. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... COLD FRONT MOVING SOUTHEAST ACROSS THE STATE THIS AFTERNOON WILL BRING HIGHLY LOCALIZED IFR CIGS AND VSBYS IN STRONG TO SEVERE TSRA EAST OF A KIPT TO KSEG AND KMDT LINE THROUGH 21Z. COOLER AND LESS HUMID AIR WILL BRING WIDESPREAD VFR FLYING CONDITIONS TONIGHT THROUGH SATURDAY NIGHT. GUSTY WEST TO NORTHWEST SFC WINDS WILL CAUSE MECHANICAL TURBULENCE ON TAKEOFF AND FINAL APPROACH THROUGH ABOUT 01Z SATURDAY...BEFORE WINDS DECREASE TO LESS THAN 10 MPH. HIGH PRESSURE WILL BUILD IN FOR SAT WITH VFR FLYING EXPECTED. SUN-TUE LOOKS UNSETTLED WITH SEVERAL DISTURBANCES TAKING AIM ON THE REGION. AS THE MILDER/MOIST AIR MOVES OVER THE COOL AIRMASS OVER PENN...CLOUDS WILL GRADUALLY LOWER AND THICKEN SUNDAY...BUT FYING CONDITIONS SHOULD BE MVFR AT WORST AS CLOUD BASES STAY AOB 3 KFT AGL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM/DANGELO/LAMBERT NEAR TERM...GRUMM/LAMBERT/STEINBUGL SHORT TERM...GRUMM LONG TERM...GRUMM AVIATION...LAMBERT/GARTNER pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 147 PM EDT FRI AUG 17 2007 .SYNOPSIS... A COLD FRONT LOCATED NEAR INTERSTATE 80 LATE THIS MORNING WILL PUSH SOUTH ACROSS THE REGION THIS AFTERNOON...TRIGGERING A FEW SHOWERS OR A THUNDERSTORM ACROSS THE SOUTHERN COUNTIES OF PENNSYLVANIA. DRIER AND COOLER AIR WILL MOVE OVER THE REGION THROUGH SATURDAY NIGHT S HIGH PRESSURE BUILDS SOUTHEAST ACROSS THE GREAT LAKES. MOISTURE AND NORTHWESTERLY FLOW ALOFT SUNDAY INTO MONDAY COULD INCREASE THE CHANCE OF SHOWERS. A WEAK UPPER LEVEL RIDGE SHOULD DOMINATE THE REGION BY MID-WEEK WITH WARM HUMID CONDITIONS. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... UPDATE FOR SVR THUNDERSTORM WATCH #612 EFFECTIVE UNTIL 8 PM FOR OUR FAR EASTERN COUNTIES. STORMS DEVELOPED RAPIDLY OVER NERN SECTIONS...AND PRODUCED LARGE HAIL AND STRONG WINDS IN LYCOMING/LANCASTER COS. SVR THREAT WILL CONTINUE INTO THE LATE AFTN/EARLY EVE INVOF OF WARM FRONT EXTNDG ACROSS ERN PA. UNIDIRECTIONAL DEEP LYR WIND FIELD OVER TOP THE LLVL BNDRY WILL SUPPORT ROTATING UPDRAFTS WITH SPLITTING LEFT MOVING CELLS ENHANCING HAIL POTENTIAL. THE COLD FRONT DRAPED ACROSS NRN PENN AT 1430Z WAS BEING TEMPORARILY DELAYED IN ITS SWD MVMT BY A WEAK WAVE OF LOW PRESSURE NEAR KIPT. NAM/RUC SHOW MIXED LAYER CAPE CLIMBING TO OVER 1000 J/KG ACROSS THE LOWER SUSQ VALLEY THIS AFTERNOON...WHICH IN THE PRESENCE OF WEAK LARGE SCALE FORCING AHEAD OF A SHORT WAVE HEADING SE FROM THE LWR GLAKES...SHOULD YIELD A FEW SHRA/TSRA /MAINLY NEAR AND TO THE SE OF INTERSTATE 81/. COOLER AND LESS HUMID AIR WILL ADVECT SE BEHIND THE FRONT LATE IN THE DAY...SWEEPING ANY CONVECTION SOUTH OF THE MASON/DIXON LINE. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/... HE FRONT SHOULD PUSH TO OUR SOUTH BY MIDDAY. THE COOLER AND DRIER AIR SHOULD PRODUCE A PLEASANT DAY WITH SKIES BECOMING MOSTLY SUNNY. OUR PW VALUES ARE FOREST TO DROP BELOW NORMAL BY EVENING OVER THE ENTIRE STATE. SHOULD BE COMFORTABLE AFTERNOON AND EVENING. VERY DRY AIR OVERNIGHT FRIDAY INTO SATURDAYS SUGGESTS A VERY COOL MORNING SATURDAY. SREF 2M TEMPS SHOW MANY LOCATIONS IN THE 40S ACROSS NORTHERN AND CENTRAL PA. COMFORTABLE 50S IN THE SOUTH/SOUTHEAST. SATURDAY SHOULD BE A MOSTLY SUNNY DAY WITH LOW HUMIDITY AND TEMPS MAINLY IN THE 70S. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... SATURDAY NIGHT SHOULD BE ANOTHER PLEASANT NIGHT. CLOUDS COULD MOVE INTO WESTERN AREAS OVERNIGHT AS A SURGE OF MOISTURE HEADS OUR WAY. CANNOT RULE OUT A SHOWER IN THE WEST BY SUNDAY MORNING. SUNDAY...THE PW VALUES RETURN TO NORMAL AND RISE ABOVE NORMAL IN THE WEST. GEFS SHOWS CHANCE OF SHOWERS/THUNDERSTORMS MAINLY IN THE WEST. MONDAY...A WEAK LOW-LEVEL BOUNDARY SHOULD BE OVER THE STATE. WARM MOIST AIR ON THE SOUTH SIDE AND COOLER DRIER AIR ON THE NORTH. HIGH PROB HAS MOST OF PA WITH ABOVE NORMAL PW AND CHANCE OF SHOWERS. TUES-THURS...OUR PW VALUES ARE FORECAST TO BE ABOUT 1SD ABOVE NORMAL SUGGESTING HUMID CONDITIONS AND CHANCES OF SHOWERS. BY TUESDAY OUR 850 HPA TEMPS ARE ABOVE NORMAL SUGGESTING IT WILL SHOULD BE SLIGHTLY WARMER THAN NORMAL TUE-THURS AS OUR 850 HPA TEMPS REMAIN ABOVE NORMAL. OUR 925 HPA TEMPS SHOULD BE SLIGHTLY ABOVE NORMAL. LOOKS LIKE A RELATIVELY WARM HUMID PERIOD AND THUS THE CHANCE OF SHOWERS AND THUNDERSTORMS. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... COLD FRONT MOVING THROUGH THE STATE AT THIS TIME WILL USHER IN MUCH DRIER AIR BY AFTERNOON. AFTER CURRENT HAZE AND FOG DISSIPATES LATER THIS MORNING...BY AROUND 14Z TO 15Z...VFR CONDS ARE EXPECTED. RATHER DEEP MIXING WILL PROMOTE GUSTY SFC WNDS GUSTS LATER THIS AFTN. HIGH PRESSURE WILL BUILD IN FOR SAT WITH VFR FLYING EXPECTED. SUN- TUE LOOKS UNSETTLED WITH SEVERAL DISTURBANCES TAKING AIM ON THE REGION. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM/DANGELO/LAMBERT NEAR TERM...GRUMM/LAMBERT/STEINBUGL SHORT TERM...GRUMM LONG TERM...GRUMM AVIATION...GARTNER pa AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 800 PM CDT FRI AUG 17 2007 .DISCUSSION... TWO AREAS OF CONVECTION ONGOING AT 800 PM CDT. ONE IS MORE OF A COMBINATION OF HEATING OUT AND STRONG LOW LEVEL CONVERGENCE. THIS WAS FOUND ACROSS THE WESTERN HIGH PLAINS WITH MUCH IF NOT ALL OF THIS ACTIVITY BEING FORCED IN THE LOWEST 500 METERS. FARTHER EAST OVER NW IA AND SE SD...AN INCREASING LLJ IN THE 750-1250M LAYER SEEMS TO BE SPARKING THIS ACTIVITY. INITIAL THOUGHTS ARE THAT WESTERN HIGH PLAINS ACTIVITY WILL EITHER WANE QUITE A BIT WITH THE LOSS OF HEATING OR CONGEAL IN THE AN MCS AND TRACK IN TO WESTERN AND CENTRAL NE. CENTRAL AND EASTERN SD SHOULD SEE THE TAIL END OF CURRENT THUNDERSTORM ACTIVITY LIGHT UP AS LLJ STRENGTHENS TO 40-50 KNOTS. CURRENT PROJECTIONS ARE FOR THE STRONGEST FORCING TO TAKE PLACE BETWEEN 3Z-6Z JUST NORTH OF THE MO RIVER PER THE LATEST RUC/NAM. SO...WILL BUMP POPS UP 10-20 PERCENT AS IT APPEARS PER THE LATEST PROFILERS THAT THE LATEST MODEL OUTPUT ON TARGET WITH LLJ STRENGTH AND LOCATION. SEVERE THREAT APPEARS MINIMAL WITH SFC DELTA THETA DIFFERENCE LESS THAN 20 AND MAX ELEVATED CAPE VALUES AROUND 900-850MB ONLY 1000-1500 J/KG. FREEZING LEVEL ALSO AROUND 14-15KFT SO HAIL THREAT LOW. && .AVIATION... MVFR CIGS STILL HANGING ON FM CNTRL NE INTO SWRN CWA THIS AFTN... PSBLY EXPANDING NEWD INTO CWA TNGT. SCT TSTMS EXPCD TO DVLP EWD OVR CWA LATER THIS EVE AND OVERNIGHT...AND EXPAND IN AREAL COVERAGE ESP N OF I90 WITH LCL IFR CIGS AND VSBYS PSBL. && .PREV DISCUSSION... COOL DRY SFC RDG MOVG EWD THRU ERN CWA THIS EVE FLWD BY ESELY FLOW OF GRADUALLY WARMER AND MORE MOIST AIR. LWR CLDS STILL HANGING ON IN FAR SWRN CWA THRU MID AFTN INDICATIVE OF VERY MOIST LOW LVLS. WEAKENING TSTMS HEADING FOR NWRN CWA ATTM...AND WILL KEEP SMALL CHCS THRU EARLY EVE. MAIN TSTMS EXPCD TO DVLP FM SWRN SD TO WRN NE LATE THIS AFTN THRU EARLY TNGT IN UNSTABLE AIR AND SELY INFLOW AHEAD OF GOOD RIDGE RIDER. THIS EXPCD MCS SHOULD DVLP ENEWD OVR MUCH OF CWA LATER THIS EVE THRU LATE TNGT...GRADUALLY TRANSITIONING TO MORE MID LVL DVLPMT MAINLY N OF I90 LATE TNGT. ANY OF THE STORMS WILL HAVE HEAVY RAIN DUE TO GOOD SLY INFLUX OF MOIST ADIABATIC AIR. NAM SEEMS TOO WEAK AND GFS A LIT TOO STG WITH VARIOUS QPF BULLSEYES. STILL A CHC SVR WRN CWA THIS EVE WITH RESIDUAL INSTABILITY ABV SFC...BUT MAIN THREAT WILL BE THE HEAVY RAIN/PSBLY LOCALIZED FLOODING ISSUES LATE TNGT. SETUP FOR TOMORROW ACROSS SOUTHERN MN LOOKS SIMILAR TO HOW THINGS PLAYED OUT TODAY ACROSS NORTH CENTRAL SD...WITH TSRA CONTINUING TO REDEVELOP IN BAND OF PERSISTENT LOW LEVEL THETA-E ADVECTION WHICH MOVES SLOWLY EASTWARD WITH TIME. HAVE EXPANDED HIGH POPS ACROSS THE NORTHEAST CWA WITH THIS IN MIND THROUGH EARLY AFTERNOON...AND ALSO COOLED HIGHS ACROSS ALL BUT THE SOUTHWEST CWA AS EASTERLY OUTFLOW FROM THE SLOW MOVING COMPLEX WILL KEEP MUCH OF THE CWA COOLER. NOT FULLY CONFIDENT IN EVENTUAL PLACEMENT OF THE SHRA/TSRA TO GO QUITE AS COOL AS MAV GUIDANCE...BUT GIVEN TREND OF TEMPERATURES ACROSS NORTHERN HALF OF SD TODAY...MAV NUMBERS MAY NOT BE TOO BAD AND MIDNIGHT SHIFT MAY HAVE TO COOL FURTHER. QUITE A DIFFERENCE IN EVOLUTION BETWEEN NAM AND GFS WITH REGARD TO FRONTAL PLACEMENT BY SATURDAY AFTERNOON...AND GIVEN EXPECTATION FOR OUTFLOW AS MENTIONED ABOVE...PREFER SOUTHERLY FRONTAL LOCATION NEAR MISSOURI RIVER...CLOSER TO GFS BUT NOT QUITE AS FAR SOUTH. STRONG TEMPERATURE GRADIENT ACROSS THE BOUNDARY COULD PROMOTE BETTER CHANCE OF LATE AFTERNOON/EARLY EVENING DEVELOPMENT NEAR THE FRONT...SO HAVE SHIFTED SOME HIGHER CHANCE POPS FARTHER SOUTH IN THE CWA FOR THE EVENING HOURS...BUT STILL LOOKS LIKE PRECIP SHOULD LIFT NORTHEAST OF THE CWA SUNDAY MORNING. FORECAST BECOMES QUITE MUDDLED BY LATER SUNDAY INTO SUNDAY NIGHT... WITH MODELS SHOWING LITTLE AGREEMENT AND POTENTIAL FOR OUTFLOW BOUNDARIES TO BE ANYWHERE IN THE CWA FROM PREVIOUS NIGHTS ACTIVITY. WITH LOW CONFIDENCE IN SURFACE PATTERN...AND BOTH NAM AND GFS HINTING AT WEAK UPPER WAVE MOVING ACROSS LATE IN THE WEEKEND...HAVE EXPANDED SOME LOW CHANCE POPS OVER MUCH OF THE CWA FOR LATE SUNDAY AFTERNOON AND EVENING. UNSETTLED PATTERN PERSISTS OVER THE NORTHERN CONUS FROM MONDAY THROUGH THE LONGER RANGE...WITH SOMEWHAT AMPLIFIED ZONAL FLOW BETWEEN STRONG UPPER LOW SLIDING EAST THROUGH CANADIAN PRAIRIES... AND SEASONAL UPPER RIDGING ACROSS THE SOUTHERN HALF OF THE UNITED STATES. ENSEMBLE OF MODELS CONTINUE TO SHOW QUITE A BIT OF VARIABILITY IN STRENGTH AND TIMING OF WAVES SLIDING THROUGH THE REGION...RESULTING IN LOW CONFIDENCE IN PINPOINTING LOCATION OF BETTER PRECIP CHANCES. HOWEVER IN GENERAL...PATTERN SEEMS MORE FAVORABLE FOR NIGHTTIME ACTIVITY AIDED BY NOCTURNAL LOW LEVEL JET THROUGH MIDWEEK...AND HAVE FOCUSED A LITTLE HIGHER POPS IN THE OVERNIGHT PERIODS THROUGH WEDNESDAY NIGHT. BY THURSDAY...GENERAL MODEL CONSENSUS IS TO TRACK THE MAIN UPPER LOW INTO THE HUDSON BAY BY THURSDAY...WHICH SHOULD ALLOW ASSOCIATED COOL FRONT TO PUSH SOUTH OF THE CWA. HOWEVER SOME QUESTION AS TO HOW FAR SOUTH THE FRONT WILL BE ABLE TO GO WITH DOMINANT UPPER RIDGE OVER THE SOUTHEAST US. LATE IN THE WEEK...00Z OPERATIONAL GFS QUITE AGGRESSIVE IN DEVELOPING STRONG SURFACE LOW AND TRACKING IT QUICKLY NORTHEAST FROM COLORADO THROUGH NORTHWEST IOWA INTO THE FAR WESTERN GREAT LAKES BY FRIDAY EVENING. WOULD BE A GOOD WINTERTIME SETUP FOR A BAND OF HEAVY SNOW ACROSS THE AREA... HOWEVER SEEMS A BIT OVERDONE FOR THIS TIME OF YEAR AND IS QUITE AN OUTLIER COMPARED TO ECMWF AND OTHER 00Z GFS ENSEMBLE MEMBERS. HAVE LEANED MORE TOWARD PREFERRED ENSEMBLE SOLUTION WHICH KEEPS THE FRONT SOUTHEAST OF OUR CWA...WITH SMALL PRECIP CHANCES OVER MAINLY THE SOUTHEAST 1/3 OF THE CWA. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ JH/RSR sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 630 AM CDT SAT AUG 18 2007 .AVIATION... REMNANTS OF ERIN STILL PRODUCING WIDESPREAD MODERATE RAIN ACROSS NORTH CENTRAL TEXAS...AND WILL CONTINUE TO AFFECT ABI AIRPORT THROUGH THE MORNING. EXPECTING MAINLY MVFR CONDITIONS FOR MOST AIRPORTS...BUT COULD SEE SOME TEMPORARY IFR CONDITIONS WITH HEAVIER RAIN SHOWERS IN THE KABI AREA. CEILINGS SHOULD IMPOROVE BY MID MORNING...BUT STILL CONCERNED ABOUT THE POSSIBILITY FOR AFTERNOON THUNDERSTORMS AS THE REMNANTS OF ERIN LINGER ACROSS WEST CENTRAL TEXAS. BEST THUNDER CHANCE WILL LIKELY BE IN THE 22Z TO 01Z TIME FRAME...BUT COULD SEE ADDITIONAL RAIN CONTINUING OVERNIGHT AS WELL. DUE TO UNCERTAINTY IN LOCATION OF REMNANT UPPER LOW...WILL WAIT A LITTLE BEFORE INTRODUCING RAIN OVERNIGHT TONIGHT. && .PREV DISCUSSION... /ISSUED 203 AM CDT SAT AUG 18 2007/ SHORT TERM... UPPER LEVEL LOW WAS ABOUT 30 MILES NORTHEAST OF MIDLAND AT 2 AM...BUT MAIN WEATHER FOCUS IS A LARGE BAND OF CONVECTIVE SHOWERS AND THUNDERSTORMS FROM PANDALE TO SONORA TO SAN ANGELO TO ABILENE. STORMS ARE TRAINING ALONG THIS LINE WITH RAINFALL AMOUNTS OF 1 TO 2 INCHES PER HOUR. ALONG WITH THE FLASH FLOOD THREAT...MAY SEE SOME FLOODING ALONG THE RIVER RISES AND POTENTIAL FLOODING ALONG THE SOUTH CONCHO...ELM CREEK AT BALLINGER...PECAN CREEK NEAR SAN ANGELO. HEAVY RAINFALL NEAR AND SOUTH OF ABILENE MAY ALSO CAUSE CREEKS TO RISE AND POSSIBLY FLOOD THIS MORNING. RUC AND WRF MODELS INDICATE BAND OF SHOWERS AND THUNDERSTORMS EXPECTED TO WEAKEN THROUGH MID MORNING MORNING...MOVING IN TOWARD THE CENTER OF CIRCULATION. THIS GIVES ANOTHER 6-8 HOURS OF HEAVY RAINFALL HOWEVER WHICH WILL CAUSE SIGNIFICANT AND DANGEROUS FLOODING PROBLEMS. AFTER THIS...MOST OF THE SIGNIFICANT RAINFALL THIS AFTERNOON AND EVENING IS CLOSER TO THE UPPER LOW...IN THE BIG BIG COUNTRY. AGAIN HOWEVER CONVECTIVE BANDS OF STORMS POSSIBLE AGAIN IN THE AFTERNOON...WHICH HAVE AT TIME BEEN STRONGER THAN THOSE NEAR THE CENTER OF ERIN. WILL CONTINUE FLASH FLOOD WATCH FOR ALL THE CWA UNTIL 7 PM. LONG TERM... MAIN CONFIDENCE IS IN THE FIRST 12 HOURS OF THE FORECAST. WRF MODEL DRIFTS THE CENTER OF ERIN...EASTWARD ACROSS THE NORTHERN BIG COUNTRY TONIGHT TO NEAR WICHITA FALLS ON SUNDAY. ETA (NAM) WANTS TO DRIFT IT NORTH TOWARD LUBBOCK. NOT A LOT OF CONFIDENCE IN EITHER ONE OF THE FORECASTS...THOUGH LIKE THE NAM A BIT MORE. IN EITHER CASE...RAIN AND FLOOD POTENTIAL WILL BE GREATEST OVER THE BIG COUNTRY TONIGHT/SUNDAY. BOTH NAM/GFS DEVELOP AN WEAK UPPER LOW NEAR ALONG TEXAS GULF COAST MONDAY NIGHT...MOVING IT NORTHWARD INTO WEST CENTRAL TEXAS TUESDAY NIGHT/WEDNESDAY. NOT SURE ABOUT HOW REAL THIS IS...BUT ONLY A FEW ISOLATED SHOWERS TRY TO DEVELOP ALONG IT ANYWAYS. 00Z GFS MODEL TRY TO BRING REMNANTS OF DEAN MORE TOWARD THE BIG BEND FRIDAY...BUT A LOT OF UNCERTAINTY WITH THIS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 81 72 85 72 / 90 80 50 50 SAN ANGELO 84 72 87 73 / 90 70 40 50 JUNCTION 88 72 88 73 / 60 40 30 20 && .SJT WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH THIS EVENING FOR BROWN-CALLAHAN-COKE- COLEMAN-CONCHO-CROCKETT-FISHER-HASKELL-IRION-JONES-KIMBLE-MASON- MCCULLOCH-MENARD-NOLAN-RUNNELS-SAN SABA-SCHLEICHER-SHACKELFORD- STERLING-SUTTON-TAYLOR-THROCKMORTON-TOM GREEN. && $$ 08 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 203 AM CDT SAT AUG 18 2007 .SHORT TERM... UPPER LEVEL LOW WAS ABOUT 30 MILES NORTHEAST OF MIDLAND AT 2 AM...BUT MAIN WEATHER FOCUS IS A LARGE BAND OF CONVECTIVE SHOWERS AND THUNDERSTORMS FROM PANDALE TO SONORA TO SAN ANGELO TO ABILENE. STORMS ARE TRAINING ALONG THIS LINE WITH RAINFALL AMOUNTS OF 1 TO 2 INCHES PER HOUR. ALONG WITH THE FLASH FLOOD THREAT...MAY SEE SOME FLOODING ALONG THE RIVER RISES AND POTENTIAL FLOODING ALONG THE SOUTH CONCHO...ELM CREEK AT BALLINGER...PECAN CREEK NEAR SAN ANGELO. HEAVY RAINFALL NEAR AND SOUTH OF ABILENE MAY ALSO CAUSE CREEKS TO RISE AND POSSIBLY FLOOD THIS MORNING. RUC AND WRF MODELS INDICATE BAND OF SHOWERS AND THUNDERSTORMS EXPECTED TO WEAKEN THROUGH MID MORNING MORNING...MOVING IN TOWARD THE CENTER OF CIRCULATION. THIS GIVES ANOTHER 6-8 HOURS OF HEAVY RAINFALL HOWEVER WHICH WILL CAUSE SIGNIFICANT AND DANGEROUS FLOODING PROBLEMS. AFTER THIS...MOST OF THE SIGNIFICANT RAINFALL THIS AFTERNOON AND EVENING IS CLOSER TO THE UPPER LOW...IN THE BIG BIG COUNTRY. AGAIN HOWEVER CONVECTIVE BANDS OF STORMS POSSIBLE AGAIN IN THE AFTERNOON...WHICH HAVE AT TIME BEEN STRONGER THAN THOSE NEAR THE CENTER OF ERIN. WILL CONTINUE FLASH FLOOD WATCH FOR ALL THE CWA UNTIL 7 PM. .LONG TERM... MAIN CONFIDENCE IS IN THE FIRST 12 HOURS OF THE FORECAST. WRF MODEL DRIFTS THE CENTER OF ERIN...EASTWARD ACROSS THE NORTHERN BIG COUNTRY TONIGHT TO NEAR WICHITA FALLS ON SUNDAY. ETA (NAM) WANTS TO DRIFT IT NORTH TOWARD LUBBOCK. NOT A LOT OF CONFIDENCE IN EITHER ONE OF THE FORECASTS...THOUGH LIKE THE NAM A BIT MORE. IN EITHER CASE...RAIN AND FLOOD POTENTIAL WILL BE GREATEST OVER THE BIG COUNTRY TONIGHT/SUNDAY. BOTH NAM/GFS DEVELOP AN WEAK UPPER LOW NEAR ALONG TEXAS GULF COAST MONDAY NIGHT...MOVING IT NORTHWARD INTO WEST CENTRAL TEXAS TUESDAY NIGHT/WEDNESDAY. NOT SURE ABOUT HOW REAL THIS IS...BUT ONLY A FEW ISOLATED SHOWERS TRY TO DEVELOP ALONG IT ANYWAYS. 00Z GFS MODEL TRY TO BRING REMNANTS OF DEAN MORE TOWARD THE BIG BEND FRIDAY...BUT A LOT OF UNCERTAINTY WITH THIS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 81 72 85 72 / 90 80 50 50 SAN ANGELO 84 72 87 73 / 90 70 40 50 JUNCTION 88 72 88 73 / 60 40 30 20 && .SJT WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH THIS EVENING FOR BROWN-CALLAHAN-COKE- COLEMAN-CONCHO-CROCKETT-FISHER-HASKELL-IRION-JONES-KIMBLE-MASON- MCCULLOCH-MENARD-NOLAN-RUNNELS-SAN SABA-SCHLEICHER-SHACKELFORD- STERLING-SUTTON-TAYLOR-THROCKMORTON-TOM GREEN. && $$ 99/04 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 905 PM CDT SAT AUG 18 2007 .UPDATE... THUNDERSTORMS CONTINUE TO GENERATE NORTH OF THE IOWA WARM FRONT FROM SOUTHWEST WISCONSIN ACROSS SOUTHERN MINNESOTA TO NORTH OF SIOUX FALLS SOUTH DAKOTA. THIS AREA OF RAIN CONTINUES TO MOVE EAST/SOUTHEAST AND IS EXPECTED TO TRAIN OVER THE SAME AREAS OVERNIGHT. WITH THE ACTIVITY OVER SOUTHERN MINNESOTA A LITTLE FARTHER NORTH THAN EARLIER ANTICIPATED WILL EXPAND THE WATCH A LITTLE TO THE NORTH AS WELL. 04 && .PREV DISCUSSION... /ISSUED 245 PM CDT SAT AUG 18 2007/ SHORT TERM...TONIGHT THROUGH TUESDAY FORECAST FOCUS IS ON THE EXPECTED RAIN...ALONG WITH HEAVY RAIN AND THE POSSIBILITY OF FLOODING. THE 12Z GFS AND NAM ARE IN PRETTY GOOD AGREEMENT WITH THE PLACEMENT OF THE WARM FRONT OVER THE NEXT COUPLE DAYS...WHICH WILL BE THE FOCUS FOR WHERE THE PCPN/HEAVY RAIN POTENTIAL WILL LIE. THIS BOUNDARY IS SLATED TO MOVE NORTH TODAY...LAYING UP ROUGHLY FROM NEAR THE IA/MN BORDER INTO NORTHERN ILL TONIGHT...AND THEN SLOWLY SINKS BACK INTO CENTRAL IA/CENTRAL ILL BY MONDAY MORNING. APPRECIABLE FRONTOGENETIC RESPONSE THROUGH THE ATMOSPHERE IS INDICATED NORTH OF THE SFC FRONT...WITH THE CURRENT PCPN LINING UP VERY WELL WITH THE 800:700 MB LAYER. THIS FRONTOGENETIC FORCING DOES SHIFT SOME NORTH/NORTHEAST TONIGHT...MORE FROM EASTCENTRAL MN INTO CENTRAL WI. MEANWHILE...THE STRONGEST ISENTROPIC ADVECTION IN THE 850:700 MB LAYER IS CENTERED MORE ACROSS CENTRAL WI TONIGHT. THE NOSE OF THE 850 MB MOISTURE TRANSPORT ALSO SHIFTS NORTHEAST TONIGHT...MORE FOCUSED ACROSS NORTHCENTRAL WI..INTO THIS HIGHER THETA-E AIR AND FRONTOGENETIC LIFT. THE RUC/NAM/LOCAL WRF PLACE THEIR MAIN QPF WITHIN THIS BETTER FORCING...WHILE THE GFS IS A BIT MORE SOUTH...MOSTLY ACROSS SOUTHEAST MN/SOUTHERN WI. THIS WOULD SEEM TO BE AT ODDS WITH WHERE IT PLACES ITS BEST FORCING. BELIEVE THE MAIN BAND OF RAIN/EMBEDDED THUNDERSTORMS WILL SHIFT A BIT NORTH TONIGHT. SOUTH OF THERE THOUGH...STILL EXPECT SHOWERS/STORMS TO DEVELOP...ALTHOUGH MORE CONVECTIVE IN NATURE THAN TO THE NORTH. GOOD 850:700 MB QG CONVERGENCE...THE VICINITY OF THE SFC FRONT...STRONG LOW LEVEL THERMAL GRADIENT...AND ELEVATED CAPES/S AROUND 750 J/KG JUST NORTH OF THE SFC FRONT SHOULD HELP IN THAT DEVELOPMENT. SFC PW/S ARE STILL IN EXCESS OF 2 INCHES...WHICH KEEPS HEAVY RAIN IN THE PICTURE. HOWEVER...LOCATIONS TO THE NORTH HAVE BEEN MUCH DRIER AND CAN TAKE A CONSIDERABLE AMOUNT OF RAIN...GENERALLY 3 OR MORE INCHES IN 1 TO 3 HOURS. SOUTH THOUGH...VALUES GENERALLY RANGE FROM 1-2 INCHES. ANY CONVECTIVE DOWNPOURS COULD PRODUCE 1 TO 2 INCHES PER HOUR RAIN RATES. SO...WILL EXTEND THE FLASH WATCH THROUGH 4 AM. WILL NOT ADD OR REMOVE ANY COUNTIES FROM THE WATCH FOR NOW. ON SUNDAY...A WEAK RIPPLE ALONG THE 500 MB FLOW WILL TRACK EAST FROM THE CENTRAL PLAINS TO ACROSS IA/ILL. THIS WILL WORK WITH THE PERSISTENT WARM FRONT AND FRONTOGENETIC FORCING TO CONTINUE PRODUCE RAIN AND THUNDERSTORMS...MOSTLY ALONG AND NORTH OF THE SFC FRONT. THIS WILL PERSIST SUNDAY NIGHT. AGAIN...SFC PW/S AROUND 2 INCHES WILL CONTINUE THE THREAT FOR HEAVY RAIN...AND THE THE CURRENT WATCH COULD BE EXTENDED...OR PERHAPS A DIFFERENT WATCH WILL BE NEEDED FOR LATER IN THE DAY SUNDAY...AS A RESULT. FOR MONDAY...THE SUN NIGHT PCPN SHOULD SHIFT EAST...BUT THAT WARM FRONT WILL STILL BE TO THE SOUTH...WITH NOW A COLD FRONT APPROACHING THE UPPER MISSISSIPPI RIVER VALLEY FROM THE NORTHERN PLAINS. THE CHANCE FOR SHOWERS/STORM DEVELOPMENT AROUND THE WARM FRONT WILL CONTINUE. MEANWHILE...THE COLD FRONT LOOKS TO MOVE IN ON TUESDAY...WITH YET MORE SHOWERS AND STORMS PROBABLE. OVERALL...THE WET AND UNSETTLED PATTERN WILL CONTINUE INTO MON/TUES. THE MODELS ARE TRENDING TOWARD SIMILAR SOLUTIONS...BUT STILL HAVE DIFFERENCES IN THEIR QPF. HAVE OPTED TO GO WITH WHERE THE BEST FORCING LIES RATHER THAN WHERE THE MODELS PAINT THEIR QPF. WHILE THE POSITIONING OF THE WARM FRONT IS THE FOCUS FOR THE RAIN...VARIOUS OTHER WEATHER FEATURES //SHORTWAVES...850 MB JET/MOISTURE TRANSPORT...ETC// WILL PLAY THEIR ROLES...AND MUCK UP THE OVERALL PICTURE A BIT. THE HEAVY RAIN POTENTIAL REMAINS HIGH...AND THE FLASH FLOOD WATCH CONTINUES AS A RESULT. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY THE 500 MB FLOW LOOKS TO STAY ZONAL FOR MOST OF NEXT WEEK...AND FAIRLY ACTIVE...AS THE MODELS ZIP VARIOUS PERTURBATIONS THROUGH THE MEAN FLOW. THIS WILL RESULT IN CONTINUED PCPN CHANCES FOR MOST OF NEXT WEEK...ALTHOUGH THE TIMING ON WHEN THE BEST CHANCES WILL BE IS DIFFICULT IN A PATTERN SUCH AS THIS. WILL CONTINUE TO PAINT THE POPS WITH BROAD STROKES...AVOIDING TOO MUCH REFINEMENT UNTIL CONFIDENCE IN THE TIMING/STRENGTH/PLACEMENT OF THE VARIOUS SHORTWAVES AND/OR SFC BOUNDARIES INCREASES. AVIATION... FORECAST CONFIDENCE WAS FAIRLY HIGH THAT PERIODS OF SHOWERS AND THUNDERSTORMS SHOULD CONTINUE TO AFFECT THE AREA THROUGH TONIGHT INTO SUNDAY. THIS WAS BASED ON MOIST SOUTHERLY FLOW IMPINGING ON SURFACE AND 850MB FRONT...ALONG WITH PARADE OF UPPER LEVEL DISTURBANCES INTERACTING WITH THE FRONT. AS A RESULT...IFR AND/OR MVFR ARE EXPECTED TO BE THE PREDOMINANT CONDITIONS AT BOTH LSE AND RST TAF SITES. THOMPSON && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLASH FLOOD WATCH UNTIL 4 AM CDT SUNDAY FOR WIZ032-WIZ033-WIZ041- WIZ053-WIZ054-WIZ055-WIZ061. MN...FLASH FLOOD WATCH UNTIL 4 AM CDT SUNDAY FOR MNZ079-MNZ086-MNZ087- MNZ088-MNZ094-MNZ095-MNZ096. IA...FLASH FLOOD WATCH UNTIL 4 AM CDT SUNDAY FOR IAZ008-IAZ009-IAZ010- IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. && $$ wi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 846 PM CDT SAT AUG 18 2007 .UPDATE...HAVE EXPANDED FLASH FLOOD WATCH TO INCLUDE COLUMBIA AND DODGE COUNTIES. WILL CONTINUE FLASH FLOOD WATCH FOR COUNTIES THAT WAS ISSUED EARLIER. && .SHORT TERM...EXPANDED WATCH AS 1 INCH RAINFALL TOTALS HAVE ALREADY OCCURRED OVER COLUMBIA AND DODGE COUNTIES. IN ADDITION A SLOW EASTWARD PROGRESSION OF COLD CLOUD TOPS SHOWN IN IR SATELLITE ASSOCIATED WITH BAND OF CONVECTION EXPECTED TO BRING ADDITIONAL RAINFALL LATER TONIGHT TO THAT AREA AS WELL AS REMAINDER OF FLASH FLOOD WATCH AREA. TREND OF BACK BUILDING OF CONVECTION NOTED IN RADAR AND SATELLITE LOOPS LAST FEW HOURS WILL INSURE WIDESPREAD PRECIPITATION FOR THE OVERNIGHT HOURS. CURRENT UPPER AIR ANALYSIS SHOWS 30+ LOW LEVEL JET FEEDING FROM IOWA INTO SOUTHERN WISCONSIN WHERE TIGHT BAROCLINIC ZONE REMAINS NEARLY STATIONARY. && .PREV DISCUSSION... /ISSUED 335 PM CDT SAT AUG 18 2007/ DISCUSSION...FCST FOCUS IS ON HEAVY RAIN POTENTIAL TONIGHT INTO SUNDAY AND WET AND UNSETTLED WEATHER INTO MID WEEK. WARM AIR ADVECTION SHOWERS AND A FEW THUNDERSTORMS OVERSPREADING STATE AS EXPECTED ON NOSE OF 30-35KT 850 MB WINDS RUNNING OVER TIGHT BAROCLINIC ZONE...850 TEMPS +8C AT GRB WHILE +16C AT DVN ON 12Z SOUNDINGS...AHEAD OF SHRT WAVE TROUGH LOCATED OVER S CNTRL MN/N CNTRL IA AT 19Z. HEAVIEST PCPN HAS TRACKED WELL WITH STRONGEST 850-700MB FRONTOGENETIC FORCING. NAM CONTINUES TO BE AN OUTLIER WITH PUSH OF SFC AND 850 MB WARM FRONTS FARTHER NORTH THAN CONSENSUS...SO WILL FOLLOW THE GFS FOR DETAILS. RGNL 88-D REFLECTIVITY RETURNS SHOW DISCRETE CONVECTIVE CELLS FORMING CLOSER TO SFC WRM FRONT IN CNTRL IL AND ELEVATED CELLS ..PER RUC SNDG FOR DBQ...FROM SW WI BACK TWDS S CNTRL MN IN RGN OF BETTER ISENTROPIC LIFT NOTED ON 305K SURFACE...AND STRONG 750-800 MB FRONTOGENETIC FORCING. THIS POCKET OF BETTER ISENTROPIC LIFT AND FORCING CROSSES SRN WI BETWEEN 06Z AND 12Z...WITH RGN UNDER THE RIGHT ENTRANCE REGION OF 100-115KT 300 MB JET AIDING LARGE SCALE LIFT. PRECIPITABLE WATER VALUES BETWEEN 2 INCHES AND 2.20 INCHES...AND PRECIP EFFICIENCIES OF 1.70 TO 2.0 ASSURING MAXIMUM POTENTIAL ACCUMULATIONS. STORM TOTAL QPF STILL TARGETS THE MORE SUSCEPTIBLE SRN COUNTIES OF THE CWA SO WILL LEAVE THE GOING FLASH FLOOD WATCH AS IS. IF AXIS OF MAX QPF DOES SHIFT A BIT FARTHER NORTH...NRN COUNTIES HAVE BEEN MUCH DRIER AND 1-3-6 HRLY FLASH FLOOD GUIDANCE MOSAICS INDICATE THE NRN 2 TIERS OF COUNTIES WOULD NEED FAR MORE RAINFALL THAN IS FCST...2.75 TO 3.5 INCHES IN ONE HOUR...TO WARRANT ADDING TO THE WATCH. STILL ALL OF CWA WILL HAVE TO BE MONITORED FOR THE POSSIBILITY OF URBAN/LOWLAND LOCALIZED FLOODING IN ADDITION TO FLASH FLOOD POTENTIAL IN THE SOUTH. UPR JET MAX LINGERS OVER REGION THRU MONDAY...WITH 850 BAROCLINIC ZONE DRAPED OVER CWA WITH PERSISTENT CROSS-ISOTHERM FLOW AND FRONTOGENETIC FORCING...SO WILL LEAVE LIKELY WORDING IN FOR SUNDAY. SFC BNDRY REMAINS ACROSS NRN IL/SRN WI WITH MODELS INDICATING A SERIES OF COMPLEXES MOVING ALONG BNDRY. GENERALLY FOLLOWED MAV GUIDANCE FOR TEMPS...THOUGH TEMPERED TUESDAY MAXES A BIT. EXTENDED...SOME VARIABILITY WITH TIMING AND STRENGTH OF SHRT WAVES IN ZONAL FLOW OVER THE NRN U.S. AND SFC BOUNDARY THAT WILL OSSCILATE OVER THE WRN GREAT LAKES THRU THE PERIOD. APPEARS ENOUGH AGREEMENT AMONG MODELS WITH COLD FRONT SAGGING THRU WI WED AND STALLING NEAR THE NRN IL/WI BORDER WITH WEAK WAVES RUNNING THE BOUNDARY THRU FRI. GFS MAY BE HAVING SOME CONVECTIVE FEEDBACK ISSUES WITH COMPACT VIGOROUS VORTICITY MAXIMAS AND ASSOCIATED QPF AMOUNTS...BUT PATTERN SUGGESTS CWA IS IN REGION DOWNSTREAM FROM NOCTURNAL MCS/S DEVELOPING JUST TO OUR WEST ON PERIPHERY OF 500 MB HIGH OVER THE SE U.S. AND MOVING EWD ALONG BOUNDARY. WITH POTENTIAL FOR THESE COMPLEXES AND EVEN WEAK MCV/S CROSSING CWA WILL HAVE TO KEEP POPS IN FCST EACH DAY...THO NO ALL DAY RAIN OUTS. GENERALLY ACCEPTED HPC/MEXMOS FOR TEMPERATURES THOUGH BACKED OFF ON WED HI/S DUE TO EXPECTED PCPN AND CLOUDS ALONG FRONT WHICH CONSENSUS FCSTS HAVE MOVING THRU CWA BY LATE MORNING/EARLY AFTERNOON. AVIATION...XPCT WDSPRD MVFR CONDS IN -RA/-TSRA/BR THRU 00Z MON. AREAS OF IFR CIGS/VSBYS EXPCTD IN PDS OF HVY RA/TSRA INTO 18Z MON. STNRY FNT ACRS IA AND NRN IL THRU PD WITH MSTR LIFTING OVR FNT INTO SRN WI. MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WIZ056-062-063-067>069. FLASH FLOOD WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR WIZ064>066-070>072. $$ && .MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 6 AM CDT SUNDAY FOR WIZ056-057-062-063- 067>069. FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR WIZ058-064>066- 070>072. && $$ TZ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 335 PM CDT SAT AUG 18 2007 .DISCUSSION...FCST FOCUS IS ON HEAVY RAIN POTENTIAL TONIGHT INTO SUNDAY AND WET AND UNSETTLED WEATHER INTO MID WEEK. WARM AIR ADVECTION SHOWERS AND A FEW THUNDERSTORMS OVERSPREADING STATE AS EXPECTED ON NOSE OF 30-35KT 850 MB WINDS RUNNING OVER TIGHT BAROCLINIC ZONE...850 TEMPS +8C AT GRB WHILE +16C AT DVN ON 12Z SOUNDINGS...AHEAD OF SHRT WAVE TROUGH LOCATED OVER S CNTRL MN/N CNTRL IA AT 19Z. HEAVIEST PCPN HAS TRACKED WELL WITH STRONGEST 850-700MB FRONTOGENETIC FORCING. NAM CONTINUES TO BE AN OUTLIER WITH PUSH OF SFC AND 850 MB WARM FRONTS FARTHER NORTH THAN CONSENSUS...SO WILL FOLLOW THE GFS FOR DETAILS. RGNL 88-D REFLECTIVITY RETURNS SHOW DISCRETE CONVECTIVE CELLS FORMING CLOSER TO SFC WRM FRONT IN CNTRL IL AND ELEVATED CELLS ...PER RUC SNDG FOR DBQ...FROM SW WI BACK TWDS S CNTRL MN IN RGN OF BETTER ISENTROPIC LIFT NOTED ON 305K SURFACE...AND STRONG 750-800 MB FRONTOGENETIC FORCING. THIS POCKET OF BETTER ISENTROPIC LIFT AND FORCING CROSSES SRN WI BETWEEN 06Z AND 12Z...WITH RGN UNDER THE RIGHT ENTRANCE REGION OF 100-115KT 300 MB JET AIDING LARGE SCALE LIFT. PRECIPITABLE WATER VALUES BETWEEN 2 INCHES AND 2.20 INCHES...AND PRECIP EFFICIENCIES OF 1.70 TO 2.0 ASSURING MAXIMUM POTENTIAL ACCUMULATIONS. STORM TOTAL QPF STILL TARGETS THE MORE SUSCEPTIBLE SRN COUNTIES OF THE CWA SO WILL LEAVE THE GOING FLASH FLOOD WATCH AS IS. IF AXIS OF MAX QPF DOES SHIFT A BIT FARTHER NORTH...NRN COUNTIES HAVE BEEN MUCH DRIER AND 1-3-6 HRLY FLASH FLOOD GUIDANCE MOSAICS INDICATE THE NRN 2 TIERS OF COUNTIES WOULD NEED FAR MORE RAINFALL THAN IS FCST...2.75 TO 3.5 INCHES IN ONE HOUR...TO WARRANT ADDING TO THE WATCH. STILL ALL OF CWA WILL HAVE TO BE MONITORED FOR THE POSSIBILITY OF URBAN/LOWLAND LOCALIZED FLOODING IN ADDITION TO FLASH FLOOD POTENTIAL IN THE SOUTH. UPR JET MAX LINGERS OVER REGION THRU MONDAY...WITH 850 BAROCLINIC ZONE DRAPED OVER CWA WITH PERSISTENT CROSS-ISOTHERM FLOW AND FRONTOGENETIC FORCING...SO WILL LEAVE LIKELY WORDING IN FOR SUNDAY. SFC BNDRY REMAINS ACROSS NRN IL/SRN WI WITH MODELS INDICATING A SERIES OF COMPLEXES MOVING ALONG BNDRY. GENERALLY FOLLOWED MAV GUIDANCE FOR TEMPS...THOUGH TEMPERED TUESDAY MAXES A BIT. .EXTENDED...SOME VARIABILITY WITH TIMING AND STRENGTH OF SHRT WAVES IN ZONAL FLOW OVER THE NRN U.S. AND SFC BOUNDARY THAT WILL OSSCILATE OVER THE WRN GREAT LAKES THRU THE PERIOD. APPEARS ENOUGH AGREEMENT AMONG MODELS WITH COLD FRONT SAGGING THRU WI WED AND STALLING NEAR THE NRN IL/WI BORDER WITH WEAK WAVES RUNNING THE BOUNDARY THRU FRI. GFS MAY BE HAVING SOME CONVECTIVE FEEDBACK ISSUES WITH COMPACT VIGOROUS VORTICITY MAXIMAS AND ASSOCIATED QPF AMOUNTS...BUT PATTERN SUGGESTS CWA IS IN REGION DOWNSTREAM FROM NOCTURNAL MCS/S DEVELOPING JUST TO OUR WEST ON PERIPHERY OF 500 MB HIGH OVER THE SE U.S. AND MOVING EWD ALONG BOUNDARY. WITH POTENTIAL FOR THESE COMPLEXES AND EVEN WEAK MCV/S CROSSING CWA WILL HAVE TO KEEP POPS IN FCST EACH DAY...THO NO ALL DAY RAIN OUTS. GENERALLY ACCEPTED HPC/MEXMOS FOR TEMPERATURES THOUGH BACKED OFF ON WED HI/S DUE TO EXPECTED PCPN AND CLOUDS ALONG FRONT WHICH CONSENSUS FCSTS HAVE MOVING THRU CWA BY LATE MORNING/EARLY AFTERNOON. && .AVIATION...XPCT WDSPRD MVFR CONDS IN -RA/-TSRA/BR THRU 00Z MON. AREAS OF IFR CIGS/VSBYS EXPCTD IN PDS OF HVY RA/TSRA INTO 18Z MON. STNRY FNT ACRS IA AND NRN IL THRU PD WITH MSTR LIFTING OVR FNT INTO SRN WI. && .MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WIZ056-062-063-067>069. FLASH FLOOD WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR WIZ064>066-070>072. && $$ 09/09/35 wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 245 PM CDT SAT AUG 18 2007 .SHORT TERM...TONIGHT THROUGH TUESDAY FORECAST FOCUS IS ON THE EXPECTED RAIN...ALONG WITH HEAVY RAIN AND THE POSSIBILITY OF FLOODING. THE 12Z GFS AND NAM ARE IN PRETTY GOOD AGREEMENT WITH THE PLACEMENT OF THE WARM FRONT OVER THE NEXT COUPLE DAYS...WHICH WILL BE THE FOCUS FOR WHERE THE PCPN/HEAVY RAIN POTENTIAL WILL LIE. THIS BOUNDARY IS SLATED TO MOVE NORTH TODAY...LAYING UP ROUGHLY FROM NEAR THE IA/MN BORDER INTO NORTHERN ILL TONIGHT...AND THEN SLOWLY SINKS BACK INTO CENTRAL IA/CENTRAL ILL BY MONDAY MORNING. APPRECIABLE FRONTOGENETIC RESPONSE THROUGH THE ATMOSPHERE IS INDICATED NORTH OF THE SFC FRONT...WITH THE CURRENT PCPN LINING UP VERY WELL WITH THE 800:700 MB LAYER. THIS FRONTOGENETIC FORCING DOES SHIFT SOME NORTH/NORTHEAST TONIGHT...MORE FROM EASTCENTRAL MN INTO CENTRAL WI. MEANWHILE...THE STRONGEST ISENTROPIC ADVECTION IN THE 850:700 MB LAYER IS CENTERED MORE ACROSS CENTRAL WI TONIGHT. THE NOSE OF THE 850 MB MOISTURE TRANSPORT ALSO SHIFTS NORTHEAST TONIGHT...MORE FOCUSED ACROSS NORTHCENTRAL WI..INTO THIS HIGHER THETA-E AIR AND FRONTOGENETIC LIFT. THE RUC/NAM/LOCAL WRF PLACE THEIR MAIN QPF WITHIN THIS BETTER FORCING...WHILE THE GFS IS A BIT MORE SOUTH...MOSTLY ACROSS SOUTHEAST MN/SOUTHERN WI. THIS WOULD SEEM TO BE AT ODDS WITH WHERE IT PLACES ITS BEST FORCING. BELIEVE THE MAIN BAND OF RAIN/EMBEDDED THUNDERSTORMS WILL SHIFT A BIT NORTH TONIGHT. SOUTH OF THERE THOUGH...STILL EXPECT SHOWERS/STORMS TO DEVELOP...ALTHOUGH MORE CONVECTIVE IN NATURE THAN TO THE NORTH. GOOD 850:700 MB QG CONVERGENCE...THE VICINITY OF THE SFC FRONT...STRONG LOW LEVEL THERMAL GRADIENT...AND ELEVATED CAPES/S AROUND 750 J/KG JUST NORTH OF THE SFC FRONT SHOULD HELP IN THAT DEVELOPMENT. SFC PW/S ARE STILL IN EXCESS OF 2 INCHES...WHICH KEEPS HEAVY RAIN IN THE PICTURE. HOWEVER...LOCATIONS TO THE NORTH HAVE BEEN MUCH DRIER AND CAN TAKE A CONSIDERABLE AMOUNT OF RAIN...GENERALLY 3 OR MORE INCHES IN 1 TO 3 HOURS. SOUTH THOUGH...VALUES GENERALLY RANGE FROM 1-2 INCHES. ANY CONVECTIVE DOWNPOURS COULD PRODUCE 1 TO 2 INCHES PER HOUR RAIN RATES. SO...WILL EXTEND THE FLASH WATCH THROUGH 4 AM. WILL NOT ADD OR REMOVE ANY COUNTIES FROM THE WATCH FOR NOW. ON SUNDAY...A WEAK RIPPLE ALONG THE 500 MB FLOW WILL TRACK EAST FROM THE CENTRAL PLAINS TO ACROSS IA/ILL. THIS WILL WORK WITH THE PERSISTENT WARM FRONT AND FRONTOGENETIC FORCING TO CONTINUE PRODUCE RAIN AND THUNDERSTORMS...MOSTLY ALONG AND NORTH OF THE SFC FRONT. THIS WILL PERSIST SUNDAY NIGHT. AGAIN...SFC PW/S AROUND 2 INCHES WILL CONTINUE THE THREAT FOR HEAVY RAIN...AND THE THE CURRENT WATCH COULD BE EXTENDED...OR PERHAPS A DIFFERENT WATCH WILL BE NEEDED FOR LATER IN THE DAY SUNDAY...AS A RESULT. FOR MONDAY...THE SUN NIGHT PCPN SHOULD SHIFT EAST...BUT THAT WARM FRONT WILL STILL BE TO THE SOUTH...WITH NOW A COLD FRONT APPROACHING THE UPPER MISSISSIPPI RIVER VALLEY FROM THE NORTHERN PLAINS. THE CHANCE FOR SHOWERS/STORM DEVELOPMENT AROUND THE WARM FRONT WILL CONTINUE. MEANWHILE...THE COLD FRONT LOOKS TO MOVE IN ON TUESDAY...WITH YET MORE SHOWERS AND STORMS PROBABLE. OVERALL...THE WET AND UNSETTLED PATTERN WILL CONTINUE INTO MON/TUES. THE MODELS ARE TRENDING TOWARD SIMILAR SOLUTIONS...BUT STILL HAVE DIFFERENCES IN THEIR QPF. HAVE OPTED TO GO WITH WHERE THE BEST FORCING LIES RATHER THAN WHERE THE MODELS PAINT THEIR QPF. WHILE THE POSITIONING OF THE WARM FRONT IS THE FOCUS FOR THE RAIN...VARIOUS OTHER WEATHER FEATURES //SHORTWAVES...850 MB JET/MOISTURE TRANSPORT...ETC// WILL PLAY THEIR ROLES...AND MUCK UP THE OVERALL PICTURE A BIT. THE HEAVY RAIN POTENTIAL REMAINS HIGH...AND THE FLASH FLOOD WATCH CONTINUES AS A RESULT. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY THE 500 MB FLOW LOOKS TO STAY ZONAL FOR MOST OF NEXT WEEK...AND FAIRLY ACTIVE...AS THE MODELS ZIP VARIOUS PERTURBATIONS THROUGH THE MEAN FLOW. THIS WILL RESULT IN CONTINUED PCPN CHANCES FOR MOST OF NEXT WEEK...ALTHOUGH THE TIMING ON WHEN THE BEST CHANCES WILL BE IS DIFFICULT IN A PATTERN SUCH AS THIS. WILL CONTINUE TO PAINT THE POPS WITH BROAD STROKES...AVOIDING TOO MUCH REFINEMENT UNTIL CONFIDENCE IN THE TIMING/STRENGTH/PLACEMENT OF THE VARIOUS SHORTWAVES AND/OR SFC BOUNDARIES INCREASES. && .AVIATION... FORECAST CONFIDENCE WAS FAIRLY HIGH THAT PERIODS OF SHOWERS AND THUNDERSTORMS SHOULD CONTINUE TO AFFECT THE AREA THROUGH TONIGHT INTO SUNDAY. THIS WAS BASED ON MOIST SOUTHERLY FLOW IMPINGING ON SURFACE AND 850MB FRONT...ALONG WITH PARADE OF UPPER LEVEL DISTURBANCES INTERACTING WITH THE FRONT. AS A RESULT...IFR AND/OR MVFR ARE EXPECTED TO BE THE PREDOMINANT CONDITIONS AT BOTH LSE AND RST TAF SITES. THOMPSON && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WIZ041-WIZ053-WIZ054- WIZ055-WIZ061. MN...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR MNZ086-MNZ087-MNZ088- MNZ094-MNZ095-MNZ096. IA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR IAZ008-IAZ009-IAZ010- IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. && $$ RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 357 AM MDT SUN AUG 19 2007 .SHORT TERM... (TODAY AND TONIGHT) MAIN SHORT TERM CONCERN IS THE AMOUNT OF CONVECTION ACROSS THE HIGHER TERRAIN. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING GENERALLY WEAK WEST TO SOUTHWEST FLOW ALOFT ACROSS THE REGION WITH FASTER ZONAL FLOW CONTINUING ACROSS THE NORTHERN TIER AS UPPER LEVEL HIGH PRESSURE PERSISTS ACROSS SOUTHERN NEW MEXICO ATTM. WATER VAPOR IMAGERY ALSO INDICATING MINOR SHORT WAVE EMBEDDED IN THE WESTERLY FLOW MOVING INTO WESTERN WYOMING WITH DRIER AIR ALOFT MOVING ACROSS EASTERN UTAH AND INTO WESTERN COLORADO ATTM. CURRENT OBSERVATIONS AND SATELLITE INDICATING IFR STRATUS ACROSS THE WESTERN TEXAS AND OKLAHOMA PANHANDLE INTO WESTERN KANSAS...WITH SOME PATCHY MVFR/IFR CIGS ACROSS EXTREME SE COLORADO ATTM. TODAY AND TONIGHT...NOT MUCH CHANGE IN CURRENT FORECAST THINKING AS MODELS REMAIN CONSISTENT WITH KEEPING DRIER WESTERLY ALOFT ACROSS MUCH OF THE REGION AS WESTERN WYOMING SHORT WAVE CONTINUES TO MOVE ACROSS THE NORTHERN ROCKIES THROUGH TONIGHT. WITH ENOUGH RESIDUAL MOISTURE ALONG WITH DAYTIME HEATING...CANT RULE OUT ISOLATED THUNDERSTORMS DEVELOPING ACROSS THE HIGHER TERRAIN THIS AFTERNOON AND EVENING AND HAVE KEPT THE BEST POPS ACROSS THE CENTRAL MTS WITH PROXIMITY TO PASSING WAVE. MODELS INDICATING SLIGHT WARMING ALOFT WITH H7 TEMPS PROGGED BETWEEN 14-18C...AND WITH LESS CONVECTIVE CLOUD COVER...SHOULD SEE HIGHS IN THE UPPER 80S TO UPPER 90S ACROSS THE PLAINS...WITH 60S TO LOWER 80S ACROSS THE HIGH TERRAIN. CONVECTION TO DIMINISH WITH THE SUN THIS EVENING WITH CLEARING SKIES THROUGH THE OVERNIGHT. MODELS INDICATING WARM AIR ALOFT PERSISTING ACROSS THE REGION...AND HAVE WARMED OVERNIGHT LOWS A TAD MAINLY ACROSS THE HIGHER ELEVATIONS. -MW .LONG TERM... (MONDAY THROUGH NEXT SATURDAY) WESTERLY FLOW INCREASES ACROSS THE AREA ON MONDAY...AS FIRST PIECE OF THE PACIFIC NORTHWEST UPPER TROUGH MOVES THROUGH THE NRN ROCKIES. SHOULD BE WARMER AND DRIER ALL AREAS AS WEST WINDS PUSH MOISTURE AXIS EASTWARD AND DOWNSLOPE FLOW DEVELOPS ON THE PLAINS. LEFT THE LOW POPS IN PLACE OVER THE MOUNTAINS FOR SOME ISOLATED AFTERNOON AND EVENING CONVECTION AS MODELS HAVE BEEN TOO QUICK TO DRY THE AIR MASS OUT THIS SUMMER. MIGHT SEE A WEAK NORTHERLY SURGE OVER THE PLAINS MONDAY AFTERNOON AS UPPER JET PUSHES OUT INTO THE PLAINS...BUT LITTLE IN THE WAY OF MOISTURE OR COOL AIR ASSOCIATED WITH IT. WESTERLY FLOW CONTINUES TUESDAY...WITH MORE SIGNIFICANT BOUNDARY DEVELOPING OVER NORTHEAST COLORADO BY TUESDAY EVENING AS MAIN UPPER JET PUSHES ACROSS THE NORTHERN PLAINS. SHOULD SEE FRONT PUSH THROUGH THE EAST BY MID-MORNING WEDNESDAY WITH A FAIRLY MOIST UPSLOPE SURGE DEVELOPING OVER THE PLAINS DURING THE DAY. EXPECT BEST CHANCE OF PRECIP OVER MUCH OF THE AREA TO BE WEDNESDAY AFTERNOON AND EVENING...WITH PERHAPS ENOUGH MOISTURE LINGERING FOR ANOTHER ROUND OF STORMS THURSDAY. SLIGHTLY COOLER TEMPS BOTH WED/THU BEHIND THE FRONT...THOUGH READINGS WILL ONLY FALL BACK TO NEAR SEASONAL NORMALS AS BULK OF THE COOLING REMAINS NORTH. && .AVIATION...PATCHY MVFR/IFR CIGS ACROSS EXTREME SE COLORADO TO QUICKLY BURN OFF THIS MORNING. LESS CONVECTION IS EXPECTED TODAY AS DRIER AIR ALOFT MOVES INTO THE REGION...THOUGH CANT RULE OUT ISOLATED THUNDERSTORMS ACROSS THE HIGHER TERRAIN...WITH VCTS POSSIBLE FOR KCOS TAF BETWEEN 22-02Z. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/10 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 AM EDT SUN AUG 19 2007 .AVIATION...NOT MUCH HAS CHANGED SINCE THE 00Z TAF ISSUANCE. THE RAIN HAS CONTINUED TO MOVE SOUTH OF THE REGION. EXPECT VFR CONDITIONS TO PREVAIL FOR THE MAJORITY OF THIS TAF CYCLE WITH A MID TO UPPER LEVEL OVERCAST. A WAVE PUSHING ACROSS THE NORTHERN OHIO VALLEY MAY DROP CEILINGS TO MVFR AT KTVC TOMORROW EVENING. HOWEVER...EXPECT ANY RAIN TO REMAIN SOUTH OF THE TAF SITES THROUGH THE PERIOD. LUTZ/MSB && .UPDATE...ISSUED 1041 PM AS THE RADAR HAS BEEN SHOWING THIS EVENING...THE RAIN SHOWERS HAVE BEEN MOVING TO THE SOUTH AND EAST. TRIMMED THE RAIN FARTHER SOUTH AND MAY HAVE TO UPDATE AGAIN AS THE RAIN LOOKING UPSTREAM ARE SHOWING WIDELY SCATTERED SHOWERS AND SPRINKLES. OTHERWISE, THE TEMPERATURES LOOKS GOOD WITH THE CLOUD COVER THAT IS OVER THE REGION AND THE HIGH PRESSURE THAT IS KEEPING THE WINDS DOWN TONIGHT. LUTZ && .PREV DISCUSSION...ISSUED 328 PM ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 114 AM EDT SUN AUG 19 2007 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE .UPDATE...(ISSUED AT 948 PM EDT SAT AUG 18) LATEST RADAR LOOP SHOWS BANDS OF SHOWERS STRETCHING FROM CENTRAL/SOUTHERN MN INTO SOUTHERN LOWER MICHIGAN BECOMING SMALLER WIDTH WISE...NOW MOSTLY CONCENTRATED ALONG AND SOUTH OF I-94. HOWEVER...THIS CONCENTRATED ZONE NOW CONSISTS OF HEAVIER SHOWERS AND THUNDERSTORMS...LIKELY DUE TO INCREASING SOUTHWEST WINDS AT 850MB NOTED ON THE BLUE RIVER WISCONSIN PROFILER (NOW 30-35KT) IMPINGING ON THE NEARLY STATIONARY FRONTAL BOUNDARY. PLENTY OF HEAT AND MOISTURE EXISTS SOUTH OF THE FRONTAL BOUNDARY TO SUSTAIN THE CONVECTION...ESPECIALLY WITH THE REMNANTS OF TROPICAL STORM ERIN BEING ADVECTED NORTHWARD WITHIN THE LOW LEVEL JET. CLOSER TO HOME...EXCEPT FOR A FEW OF THE SHOWERS BRUSHING THE MENOMINEE AREA BETWEEN 20-24Z...THE CWA REMAINS DRY WITH MID AND HIGH CLOUDS CROSSING. THESE CLOUDS ARE ALSO ASSOCIATED WITH THE MID-LEVEL FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING AIDING IN THE SHOWERS FARTHER TO THE SW. WITH THE SHOWERS DRYING UP FROM CENTRAL MN INTO EAST-CENTRAL WI...THERE IS CONCERN THAT PCPN MAY BE ENTIRELY DONE NOW MENOMINEE COUNTY (THE ONLY PLACE WITH -SHRA MENTION IN THE CWA). TWO THINGS COULD BE OCCURRING THAT IS CAUSING THE DIMINISHING OF SHOWERS: INCREASED CONVECTIVE ACTIVITY IN SOUTHERN MN AND SOUTHERN WI IS INHIBITING MOISTURE TRANSPORT TOWARDS NORTHERN WI AND/OR THE COMBINATION OF THE MID-LEVEL FRONTOGENETICAL AND UPPER LEVEL JET CIRCULATIONS ARE DRIVING DRIER AIR SOUTHWESTWARD. 20Z TAMDAR SOUNDING FROM CHIPPEWA COUNTY AIRPORT SHOWED A LOT OF DRY AIR IN THE 600-800MB LAYER (DEWPOINT DEPRESSIONS OF 20C OR MORE). GIVEN THAT THE UPPER LEVEL FLOW IS PROGGED TO REMAIN CONFLUENT WITH HEIGHTS RISING INTO SOUTH CENTRAL CANADA...AND TROUGHING IN NEW ENGLAND...THINK IT WILL BE HARD TO GET THE SHOWERS NORTHWARD. THE 18Z GFS CONCURS WITH THIS IDEA...AND THUS HAVE DECIDED TO REMOVE SHOWERS FROM THE FCST THROUGH 18Z MON. GOING TEMPS SEEM REASONABLE...THOUGH SINCE SKIES REMAIN CLEAR OUT EAST AND LOW PRECIPITABLE WATER THERE...HAVE DECIDED TO DROP TEMPS A FEW MORE DEGREES. PRECIPITABLE WATER VALUES ARE ABOUT 0.25 INCH HIGHER THAN LAST NIGHT...SUGGESTING LOWS SHOULD NOT GET AS COLD. && .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS ARE EXPECTED TO PERSIST DUE TO LOW LEVEL DRY AIR HOLDING ON FROM HIGH PRESSURE JUST TO THE NE OF LAKE SUPERIOR. LOOK FOR A GENERAL EAST WIND...WITH INCREASING SPEED ON SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. WINDS MAY BECOME GUSTY IN THE AFTERNOON AT BOTH TAF SITES AS INLAND WARMING CREATES LAKE BREEZES...ADDING ONTO THE WIND SPEED. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...JLB LONG TERM...JLL AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 312 AM EDT SUN AUG 19 2007 .SYNOPSIS... WHILE HIGH PRESSURE WILL KEEP FAIR AND SEASONABLY COOL CONDITIONS ACROSS THE BULK OF THE FORECAST AREA THROUGH MONDAY...THERE WILL BE A SHARP GRADIENT OVER THE SOUTHERN TIER LEADING TO WIDESPREAD SHOWERS JUST SOUTH OF THE BORDER. TUESDAY WILL THEN SERVE AS A TRANSITION DAY AS WARMER AND MORE HUMID CONDITIONS WILL RETURN FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... SFC HIGH PRESSURE EXTENDING FROM HUDSON BAY TO THE CAROLIANS WILL CONTINUE TO KEEP FAIR BUT COOL WEATHER ACROSS THE BULK OF WESTERN AND NORTH CENTRAL NEW YORK TODAY AND TONIGHT...BUT A RIBBON OF MOISTURE JUST TO OUR SOUTH WILL RESULT IN WIDESPREAD SHOWERS FROM THE PENNSYLVANIA BORDER SOUTHWARDS. THE SHARP GRADIENT ON THE NRN EDGE OF THE PCPN WILL RESULT IN A LOWER FORECAST CONFIDENCE ACROSS THE IAG FRONTIER AND WRN SOUTHERN TIER...WHILE A HIGH CONFIDENCE FORECAST WILL BE FOUND EAST OF LK ONTARIO. AS OF 07Z...A 75 MILE WIDE BAND OF FAIRLY STEADY RAIN EXTENDED FROM THE SOUTHERN HALF OF WISCONSIN AND MICHIGAN TO NORTHEASTERN OHIO AND INTO WESTERN PENNSYLVANIA. THIS AREA OF RAIN COINCIDES WELL WITH THE AREA OF LIFT THAT ONE WOULD EXPECT TO FIND UNDER THE ENTRANCE REGION OF A 130 KT H2 JET THAT IS ALIGNED FROM WESTERN ONTARIO AND THE UPPER GREAT LAKES TO NORTHERN NEW YORK AND COASTAL NEW ENGLAND. JET INDUCED LIFT FROM THE RR QUAD OF THE JET IS COMBINING WITH LOW LEVEL ISENTROPIC LIFT TO PRODUCE THIS SWATH OF RAIN. HOW ARE THE MODELS HANDLING THIS? THUS FAR THE NAM/WRF AND GFS ARE VERY SIMILAR IN THEIR SOLUTIONS ON THE NRN EDGE OF THE RAIN...BUT THE NAM/WRF APPEARS TO BE UNDERDONE AT THIS TIME AND DOES NOT HAVE A GOOD HANDLE ON THE EASTWARD EXTENT OF THE RAIN INTO PA. THE GFS DOES NOT HAVE THIS PROBLEM THROUGH ITS FIRST 6 HRS. THE SHORTER RANGE RUC IS GROSSLY UNDER DONE ON THE AREAL EXTENT OF THE RAIN AND APPEARS TO HAVE BIG PROBLEMS ALL THE WAY OUT THROUGH ITS 12 HR FORECAST. BOIL THIS ALL DOWN AND THE GFS SEEMS TO BE THE MODEL OF CHOICE...AS IT HAS BEEN WITH ITS SOLUTION FOR THE PAST SEVERAL DAYS. THE NAM/WRF IS JUST NOW COMING INTO LINE WITH IT. GIVEN THE IR AND COMPOSITE RADAR TRENDS...WILL CONTINUE TO RELY MORE ON THE GFS GUIDANCE WITH THIS RAIN EVENT. I WILL RAISE POPS EVER SO SLIGHTLY SOUTH OF BUFFALO SO THAT A CHANCE OF SPRINKLES WILL BE MENTIONED IN THE IAG FRONTIER TODAY WITH HIGH CHC POPS FOUND OVER THE SRN TIER. THE HIGH CHC POPS WILL BECOME LIKELY THIS EVENING FOR SITES NEAR THE BORDER. THIS FORECAST WILL BE A BIT MORE PESSIMISTIC THAN OUR SURROUNDING WFO`S...BUT MORE OPTIMISTIC THAN THE HYDROMETEOROLOGICAL PREDICTION CENTER (HPC) IN TERMS OF ACTUAL QPF. FOR TONIGHT...THE SHARP GRADIENT WILL REMAIN IN PLACE OVER NEW YORKS SOUTHERN TIER AND PA`S NRN TIER. HAVE RAISED POPS OVER PARTS OF THE IAG FRONTIER AND FINGER LAKES TO LOW CHC POPS TO ALLOW FOR A PASSING SHOWER...WHILE LIKELY POPS WILL BE FOUND OVER THE SRN TIER. AGAIN...OUR POPS WILL BE A LITTLE LOWER THAN SURROUNDING WFO`S BUT WILL BE MORE PESSIMISTIC IN TERMS OF THE HPC QPF. && .SHORT TERM /MONDAY THROUGH TUESDAY/... THE STRONG H2 JET THAT WILL BE PARTIALLY RESPONSIBLE FOR THE SWATH OF RAIN FROM SUNDAY WILL GRADUALLY PULL TO THE EAST AND SETTLE FURTHER SOUTH AS MONDAY AND MONDAY NIGHT PROGRESSES. THIS WILL HELP TO FURTHER SHUNT THE SWATH OF RAIN TO THE SOUTH...WITH ANY -SHRA OVER THE NEW YORKS SOUTHERN TIER ENDING BY MONDAY EVENING. MEANWHILE STRONG SFC HIGH PRESSURE ALONG THE ONTARIO/QUEBEC BORDER WILL PRODUCE PARTLY SUNNY SKIES ACROSS THE MAJORITY OF OUR FORECAST AREA. TEMPS MONDAY WILL REMAIN A LITTLE BELOW NORMAL WITH H8 TEMPS OF 8 TO 10 DEG C KEEPING MAX TEMPS FROM CLIMBING OUT OF THE 60S (SRN TIER) AND 70S. THE LOWER TEMPS OVER THE SRN TIER WILL BE LARGELY DUE TO THE CLOUDIER SKY CONDITIONS. FOR MONDAY NIGHT AND TUESDAY...THE SFC HIGH WILL DRIFT ACROSS NEW ENGLAND WHILE THE SUPPORTING UPPER RIDGE WILL CROSS THE LOWER GR LAKES. THIS WILL KEEP RAINFREE CONDITIONS ACROSS THE VAST MAJORITY OF THE FORECAST AREA...ALTHOUGH WE WILL CONTINUE TO MENTION LOW CHC POPS FOR A -SHRA OVER CHAUTAUQUA COUNTY WHERE THE RETURN FLOW AROUND THE HIGH COULD HELP TO USHER IN A SHOWER FROM THE SOUTH. THIS WILL ALSO HELP TO MESH BETTER WITH WFO CLE POPS TO OUR WEST. AS MENTIONED IN THE SYNOPSIS...THIS PERIOD WILL ALSO SERVE AS A TRANSITION BETWEEN MORE SUMMERY CONDITIONS THAT WILL BE LURKING JUST TO OUR SOUTH AND WEST. MUCH WARMER AND NOTICEABLY MORE HUMID CONDITIONS FOUND OVER WESTERN PA...OHIO AND MICHIGAN AT THAT TIME WILL BE POISED TO ADVANCE OUR WAY DURING THE REMAINDER OF THE WEEK. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... THE EXTENDED PORTION OF THE FORECAST CONTINUES TO FEATURE A RETURN TO SULTRY SUMMER CONDITIONS...WITH HEAT AND HUMIDITY INCREASING EARLY ON IN THE PERIOD...THEN LIKELY PERSISTING THROUGH THE REMAINDER OF THE WEEK. ON THE SYNOPTIC SCALE...A BROAD...FLAT RIDGE OVER THE EASTERN HALF OF THE NATION EARLY IN IN THE PERIOD WILL GRADUALLY BUILD NORTHWARD THROUGH THE MIDDLE AND LATTER PORTIONS OF THE WEEK...WITH THE GENERAL LARGE-SCALE FLOW SHIFTING FROM WEST TO SOUTHWEST. THIS WILL ACT TO PUMP INCREASINGLY WARMER AIR BACK INTO THE REGION...WITH 850 MB TEMPERATURES RISING FROM THE LOWER TEENS AT THE START OF THE PERIOD TO THE +17C TO +20C DEG C RANGE BY LATER IN THE WEEK. AT THE VERY LEAST...THIS WILL RESULT IN HIGH TEMPERATURES REACHING WELL INTO THE 80S BY WEDNESDAY AND THURSDAY...IF NOT THE LOWER 90S. RIGHT NOW WILL CALL FOR HIGHS REACHING THE MID TO UPPER 80S FOR THE MIDDLE AND LATTER PORTIONS OF THE WORK WEEK...WHICH IS A BIT ABOVE THE LATEST HPC AND MEX GUIDANCE. AS WAS MENTIONED IN THIS SPACE YESTERDAY...THE WARMER WEATHER WILL ALSO BE ACCOMPANIED BY MUCH MORE HUMID CONDITIONS. MREF ENSEMBLE PRECIPITABLE WATER PLUMES CONTINUE TO DEPICT VALUES RISING TO THE 1.75 TO 2 INCH RANGE FOR THE WEDNESDAY THROUGH THURSDAY PERIOD...WITH A NARROW SPREAD BETWEEN THE INDIVIDUAL MEMBERS (REFLECTIVE OF A FAIRLY HIGH CONFIDENCE FORECAST) ALSO CONTINUING THROUGH AT LEAST THURSDAY. SUCH VALUES ARE ROUGHLY 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL FOR LATE AUGUST...SO IF YOU LIKE IT VERY WARM AND HUMID...YOU SHOULD LOVE THE MIDDLE TO LATTER PORTIONS OF THE UPCOMING WEEK. GETTING A LITTLE BIT FURTHER INTO THE FORECAST DETAILS...THE AREA WILL BE ON THE PERIPHERY OF A SUBTROPICAL RIDGE THAT WILL BECOME CENTERED FROM THE SOUTHEASTERN STATES TO THE WESTERN ATLANTIC. A NUMBER OF UPPER WAVES WILL ROTATE AROUND THIS RIDGE AND ACROSS THE AREA DURING THE PERIOD...WITH THE STUBBORN FRONTAL BOUNDARY TO OUR SOUTHWEST LIKELY TO FINALLY LIFT NORTHWARD ACROSS THE REGION AS A WARM FRONT BETWEEN TUESDAY NIGHT AND WEDNESDAY NIGHT...ALONG WITH THE POSSIBILITY OF SEVERAL EPISODES OF MCS DEVELOPMENT. THEREAFTER...A TRAILING COLD FRONT IS EXPECTED TO APPROACH OUR AREA FROM THE UPPER LAKES...BUT STALL OUT JUST TO OUR NORTH AND WEST THE REST OF THE WEEK AS SEVERAL WAVES OF LOW PRESSURE RIPPLE NORTHEAST ALONG IT. WHILE MOST OF THE THURSDAY THROUGH SATURDAY PERIOD IS LIKELY TO BE DRY...HAVE LEFT LOW CHANCE POPS IN PLAY THROUGHOUT DUE TO THE NEARBY PRESENCE OF THE AFOREMENTIONED FRONTAL BOUNDARY...AND THE VERY WARM AND HUMID AIRMASS THAT SHOULD STILL BE IN PLACE. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... A DISTURBANCE PASSING ALONG A STALLED OUT-FRONTAL BOUNDARY OVER OHIO AND WESTERN PENNSYLVANIA WILL BRING INCREASING MID AND UPPER CLOUDS TODAY AND MONDAY...WITH CLOUDS MAINLY THIN EAST OF LAKE ONTARIO. MOST IF NOT ALL PRECIP WILL REMAIN TO THE SOUTH AND WEST OF TAF SITES...THE ONLY EXCEPTION BEING AT KJHW WHERE PERIODS OF LIGHT RAIN FROM A VFR MID DECK OF CLOUDS WILL BE POSSIBLE TODAY AND THIS EVENING...AND AGAIN ON MONDAY. THE STALLED-OUT FRONTAL BOUNDARY IS EXPECTED TO SLOWLY LIFT ACROSS WESTERN NEW YORK SOMETIME BETWEEN TUESDAY NIGHT AND WEDNESDAY NIGHT. WHILE THE EXACT TIMING OF THIS FRONTAL PASSAGE REMAINS IN QUESTION...IT WILL LIKELY BRING A MORE WIDESPREAD RISK OF SHOWERS AND THUNDERSTORMS TO THE AREA WHEN IT PASSES THROUGH...ALONG WITH THE CHANCE OF SOME MVFR-LEVEL RESTRICTIONS. && .MARINE... HIGH PRESSURE OVER NORTHERN ONTARIO WILL SHIFT TO WESTERN QUEBEC BY TONIGHT. A STATIONARY FRONT WILL EXTEND EAST FRO LOW PRESSURE OVER THE MIDWESTERN STATES TO JUST NORTH OF THE OHIO VALLEY AND ACROSS PENNSYLVANIA. THIS WILL INCREASE THE PRESSURE GRADIENT OVER LAKE ONTARIO AND DEVELOP A STRONGER EAST WIND ALONG THE EAST/WEST FETCH OF THE LAKE AND PRODUCE WINDS TO 20 KNOTS TONIGHT THROUGH MONDAY EVENING. WAVES WILL ALSO INCREASE WITH THE STRONGER WINDS...RANGING FROM 3 TO 5 FEET ALONG THE NEARSHORE WATERS FROM THE NIAGARA RIVER TO JUST WEST OF IRONDEQUOIT BAY...THUS A SMALL CRAFT ADVISORY WILL BE IN EFFECT FROM MIDNIGHT TONIGHT TROUGH MIDNIGHT MONDAY NIGHT. THE GRADIENT WILL RELAX A BIT BY TUESDAY MORNING AND RESULT IN LESSER WINDS AND WAVES. TUESDAY NIGHT INTO WEDNESDAY NIGHT...A WARM FRONT IS EXPECTED TO APPROACH AND CROSS THE AREA FROM SOUTHWEST TO NORTHEAST. THIS FEATURE WILL LIKELY BRING A RISK OF SHOWER AND THUNDERSTORM ACTIVITY TO THE AREA DURING THIS TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 11 PM EDT MONDAY FOR LOZ042. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...RSH LONG TERM...JJR AVIATION...WCH MARINE...WCH ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 413 AM EDT SUN AUG 19 2007 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHEAST FROM THE LOWER OHIO VALLEY INTO THE LOWER GREAT LAKES TODAY. THIS FRONT WILL REMAIN ACROSS THE REGION INTO THE FIRST PART OF THE WEEK...ACTING AS A FOCUS FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A WARM FRONT ACRS THE MID MS AND LOWER OHIO RIVER VLY WILL LIFT SLOWLY NE TOWARD THE LOWER GREAT LAKES TODAY. WARM...MOIST ASCENT WAS OCCURRING WELL NORTH OF THIS BOUNDARY INTO THE UPR MIDWEST AND LOWER GREAT LAKES REGION THIS MORNING. MOSAIC RADAR WAS SHOWING A BAND OF PCPN FROM SRN MN SE INTO NRN OHIO. WILL USE A BLEND OF THE OPERATIONAL NAM-WRF AND LATEST RUC40 MODELS FOR THE NEAR TERM FCST AS THEY ARE CAPTURING THE CURRENT PCPN BAND THE BEST. STILL LOOKS LIKE THE MAJORITY OF THE PCPN...ELEVATED IN NATURE...WILL JUST SKIM OUR FAR NORTH THIS MORNING. BY THIS AFTN...WEAK EMBEDDED S/WVS IN THE WNW FLOW ALOFT MAY TRIGGER SOME MORE SHOWERS AND THUNDERSTORMS ACRS THE NORTH. THE REMAINDER OF THE REGION SHOULD REMAIN MAINLY DRY THROUGH LATE AFTN EXCEPT THE SW WHERE A SMALL CHC OF SHOWERS AND THUNDERSTORMS HAVE BEEN PLACED IN THE FCST DUE TO AN APCHING S/WV AND INCREASING INSTABILITY. TEMPERATURES WILL BE CLOUD AND PCPN DEPENDENT...AND WILL REQUIRE SOME SHORT TERM ADJUSTMENTS. FOR NOW...HAVE TAILORED HIGHS FROM THE UPPER 70S NORTH TO THE UPPER 80S SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... A VERY COMPLEX WEATHER PATTERN WILL BE SETTING UP ACRS THE REGION THROUGH TUESDAY. AFOREMENTIONED WARM FRONT WILL STALL OUT AS A STATIONARY BOUNDARY LATE TONIGHT INTO MONDAY NIGHT. EMBEDDED S/WV IMPULSES WILL RIPPLE WITHIN THE WNW FLOW ALOFT ACRS THIS BOUNDARY. TO ADD INSULT TO INJURY...LATEST OPERATIONAL MODELS ARE NOW BRINGING THE REMNANTS OF TROPICAL STORM ERIN INTO THE OHIO VALLEY REGION LATE MONDAY NIGHT INTO TUESDAY. DEEP MOISTURE FROM ERIN IS FCST TO GET DRAWN NE INTO OUR AREA ON MONDAY...AND WILL BE ENTRENCHED ACRS THE REGION MONDAY NIGHT INTO TUESDAY. THE COMBINATION OF DEEP MOISTURE ...EMBEDDED S/WVS...AND LOW LVL CONVERGENCE IN THE VCNTY OF FRONTAL BOUNDARY WILL BRING A HIGH LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS THROUGH THE SHORT TERM PERIOD. THE BEST CHC IS EXPECTED TO OCCUR ACRS THE NRN TWO THIRDS OF THE CWFA ON MONDAY IN CLOSER PROXIMITY TO THE FRONTAL BOUNDARY. HAVE INCREASED POPS TO THE LIKELY CATEGORY FOR THE ENTIRE REGION MONDAY NIGHT AS THE REMNANTS OF ERIN MOVES SLOWLY INTO THE REGION. HAVE INCREASED POPS TO HIGH CHANCE ON TUESDAY AS THE REMNANTS OF ERIN SLOWLY EXIT THE REGION. GIVEN THE PROSPECT OF HEAVY RAIN...HAVE PLACED THIS WORDING IN THE FCST. OUR AREA CONTINUES TO BE UNDER A MODERATE TO SEVERE DROUGHT...SO WILL NOT BE ISSUING ANY HEADLINES IN TERMS OF FLASH FLOOD/FLOOD WATCHES ATTM. HOWEVER...IF WIDESPREAD PCPN MATERIALIZES ON MONDAY...THIS MAY HAVE TO BE RECONSIDERED FOR MONDAY NIGHT INTO TUESDAY AS 1 AND 3 HOUR FLASH FLOOD GUIDANCE VALUES POTENTIALLY DECREASE FROM HEAVY RAIN ON MONDAY. TEMPERATURES WILL BE QUITE DIFFICULT GIVEN THE AMOUNT OF CLOUDS AND PCPN. MAV MOS GUIDANCE CONTINUES TO BE MUCH COOLER THAN THE MET MOS. HAVE LEANED MORE TOWARD THE COOLER MAV MOS. AGAIN...SHORT TERM TEMPERATURE ADJUSTMENTS WILL LIKELY BE NEEDED THROUGH THE PERIOD...PARTICULARLY FOR THE DAYLIGHT HOURS. AS A FINAL NOTE...SPC HAS THE SWRN PART OF OUR FCST AREA IN A SLIGHT RISK FOR SEVERE STORMS ON MONDAY. THIS WILL BE HIGHLY DEPENDENT ON HOW UNSTABLE THE ATMOSPHERE CAN GET AMIDST CLOUD COVER. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... MID/UPPER LEVEL RIDGE OVER THE SOUTHERN UNITED STATES WILL SLOWLY BUILD NORTHWARD THROUGH THE END OF THE WORK WEEK. THIS WILL TEND TO KEEP OUR FA ON THE SOUTHERN FRINGE OF THE MORE ACTIVE WESTERLY FLOW AFFECTING THE GREAT LAKES. AS A RESULT...WILL GENERALLY KEEP POPS IN THE 20 PERCENT RANGE THROUGH FRIDAY...WITH THE BEST CHANCE ACROSS OUR NORTHERN FA. MODELS INDICATING THAT THE RIDGE WILL BEGIN TO BREAK DOWN TOWARD NEXT WEEKEND...BRINGING A BETTER CHANCE OF PCPN BY SATURDAY. AS HIGH BUILDS SLOWLY NORTH ACROSS OUR AREA...WE SHOULD ALSO SEE A GRADUAL WARM UP IN TEMPERATURES THROUGH FRIDAY. 06Z AND 12Z OPERATIONAL GFS ARE STRONGER WITH THE RIDGE AND THUS WARMER THAN THE 00Z GFS ENSEMBLE WEDNESDAY THROUGH FRIDAY. WILL THEREFORE TREND TEMPS A TAD COOLER THAN MOS THROUGH FRIDAY. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... LARGE AREA OF -SHRA/TSRA NORTH OF A WARM FRNTL BNDRY EXTNDG FROM UPR MISSISSIPPI VLY SE INTO CNTRL/LOWER GRT LKS. WITH WELL DEFINED 850 LLJ BACK ACRS IOWA/MINNESOTA HELPING TO INITIATE NEW CONVECTIVE DVLPMNT IN THESE AREAS...CONVECTION WILL CONTINUE TO PROPAGATE SE ALONG WARM FRONT INTO LWR MICHIGAN/NRN INDIANA AND NW OHIO THRU DAYBREAK. ALTHOUGH LO LVL WAA DVLPG JUST WEST OF FCST AREA...MODEL SOUNDINGS STILL SHWNG GOOD DEAL OF SUBSIDENCE THRU BNDRY LYR. HAVE SEEN ISOLD -SHRA/TSRA DVLP OVER LAST HOUR OR SO IN A ZONE ORIENTED SW-NE FROM CNTRL ILLINOIS INVOF MID LVL VORT NE INTO NW OHIO. NOT OUT OF THE QUESTION THAT AN ISOLD -SHRA OR SPRINKLE AFFECTS KDAY/KCMH/KLCK THRU DAYBREAK...BUT COVERAGE REMAINS LOW ENUF TO KEEP MENTION OUT OF TAFS FOR TIME BEING. AT VERY LEAST...EXPECT FAIRLY DENSE AC DECK TO PERSIST WELL INTO THE MRNG ACRS NRN 1/2 FCST AREA. MAIN AREA OF PCPN SHOULD REMAIN FOCUSED NORTH OF THE TERMINALS ACRS NRN OHIO IN CLOSER PROXIMITY TO THE FRNTL BNDRY ALL DAY SUNDAY. MODEL SOUNDINGS CONTINUE TO SHOW DRIER AIR WITHIN THE BNDRY LYR HANGING INTO THE AFTN HOURS. WHILE THERE WILL BE SOME SUNSHINE...ESPECIALLY AT KCVG AND KLUK...EXPECT MSTLY CLDY SKIES FOR MUCH OF THE DAY WITH PREDOMINANT AC DECK BTWN 10-15KFT. AS DEEPER MOISTURE BEINGS TO SLOWLY ADVECT INTO THE REGION FROM THE SOUTHWEST DURING THE AFTN/EVNG HOURS EXPECT WDLY SCT -SHRA/TSRA WILL DVLP. PCPN WILL INCREASE IN COVERAGE AFT 00Z...PARTICULARLY NORTH OF I-70. HAVE BROUGHT SOME SCT SC/CU INTO THE TERMINALS DURING THE EVNG HOURS...BUT WILL KEEP ANY PCPN MENTION OUT OF THE NRN TERMINALS (KDAY/KCMH/KLCK) AS MAJORITY OF THE PCPN SHOULD REMAIN FOCUSED NORTH OF THESE AREAS. PCPN CHANCES WILL INCREASE BEYOND 06Z MON MRNG AND THRU THE DAY MON AS FRNTL BNDRY SAGS INTO FCST AREA. OUTLOOK...TSTMS POSSIBLE MONDAY AND TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...LOTT AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 330 AM PDT SUN AUG 19 2007 .SYNOPSIS...AN UPPER LEVEL TROUGH WILL SWING THROUGH THE AREA TODAY WITH SHOWERS PERSISTING THROUGH THE EVENING HOURS THEN DIMINISHING AFTER MIDNIGHT. ANOTHER ROUND OF SHOWERS ARE EXPECTED ON MONDAY AS ANOTHER UPPER LEVEL SYSTEM PASSES THROUGH THE STATE. DRY WEATHER WITH WARMER TEMPERATURES ARE EXPECTED FROM TUESDAY ON THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE DEVELOPS OVER THE PACIFIC AND WESTERN U.S. && .SHORT TERM...WATER VAPOR IMAGERY AND RUC ANALYSIS THIS MORNING SHOWS THE UPPER LEVEL TROUGH AXIS JUST OFF THE WA/OR COAST WITH WESTERN WASHINGTON UNDER THE DIFFLUENT ZONE. RADAR SHOWING LIGHT BUT STEADY PRECIP ACROSS THE AREA WITH MOST LOCALES REPORTING A FEW HUNDREDTHS OF AN INCH PER HOUR. LIGHT RAIN WILL SWITCH OVER TO SHOWERS THIS AFTERNOON AS THE TROUGH PASSES THROUGH THE AREA. MODELS SHOW THE AXIS SHIFTING EAST AND RIGHT OVER THE CASCADES BY 18Z. MM5 GFS ALSO HINTING AT WEAK CONVERGENCE AROUND NORTHERN KING AND SNOHOMISH COUNTIES. THIS SYSTEM HAS HAD A HISTORY OF PRODUCING A FEW ISOLATED THUNDERSTORMS NEAR THE COLD CORE...BUT MODEL SOUNDINGS APPEAR TOO STABLE FOR ANY ACTIVITY TODAY. TEMPERATURES TODAY WILL BE FAIRLY MILD WITH ONLY MID TO UPPER 60S EXPECTED. A MODEST 66 AT SEATAC IS 10 DEGREES BELOW AVERAGE FOR THIS TIME OF YEAR. THE TROUGH WILL MOVE INTO E WA AND IDAHO THIS EVENING WITH SHOWERS TAPERING OFF AND LIMITED TO MOSTLY THE CASCADES. SHOWERS WILL RETURN THE THE COAST EARLY MONDAY WITH PRECIP SPREADING INLAND THROUGH THE MORNING AND AFTERNOON AS ANOTHER POTENT AND FAST MOVING SHORTWAVE TROUGH PASSES THROUGH. BY TUESDAY...WEAK UPPER LEVEL RIDGING AND NW FLOW ALOFT WILL RESULT IN DRIER AND SLIGHTLY WARMER TEMPERATURES ACROSS THE AREA. .LONG TERM...IT LOOKS LIKE THE REMAINDER OF THE WORK WEEK WILL BE DRY AS THE BROAD UPPER LEVEL RIDGE BUILDS ACROSS THE CENTRAL PACIFIC...WITH HEIGHTS RISING ACROSS THE PACNW. TEMPERATURES WILL SLOWLY WARM EACH DAY WITH POSSIBLE 80S RETURNING TO THE INTERIOR BY FRIDAY AND SATURDAY AS H5 582 HEIGHTS REACH UP INTO THE AREA. A PLEASANT RETURN TO SUMMER INDEED. FOR THE WEEKEND...MODELS TRYING TO BRING CLOSED LOW DOWN FROM GULF OF AK WITH A FRONT SLIDING DOWN THE BC COAST TOWARD WA. TOO FAR OUT TO EVEN WORRY ABOUT IT YET SO NO BIG CHANGES MADE. 33 && .AVIATION...MOISTURE CONTINUES TO STREAM IN FROM THE SOUTHWEST AS UPPER TROF APPROACHES COAST. EXPECT CONDITIONS TO CONTINUE TO DETERIORATE THRU 15Z AS PRECIP CONTINUES TO FALL INTO MOIST BOUNDARY LAYER. ONCE TROF AXIS PASSES INLAND IN THE NEXT FEW HOURS FLOW WILL VEER AROUND TO BECOME MORE WESTERLY. MESO MODELS INDICATE THIS WILL GENERATE A PERIOD OF CONVERGENCE WITH CONTINUED LOW CONDITIONS NORTH SOUND BUT WITH IMPROVING CONDITIONS ELSEWHERE. GENERALLY MVFR...BUT WITH SOME LOCAL IFR...WILL CONTINUE THROUGH AT LEAST 15Z. KSEA WINDS WILL REMAIN LIGHT AND SLY. COLMAN && .SEW WATCHES/WARNINGS/ADVISORIES...NONE. $$ WEATHER.GOV/SEATTLE wa AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1123 AM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE COAST TODAY. A WARM FRONT WILL DEVELOP OVER THE AREA THIS AFTERNOON AND STALL ACROSS NORTHERN VIRGINIA THROUGH TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL SLIDE EAST ALONG THE FRONT KEEPING THE AREA UNSETTLED THROUGH MUCH OF THE WEEK. A WARMER AND MORE HUMID AIRMASS WILL RETURN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL NOON TODAY/... STATIONARY FRONT BISECTING CWA LATE THIS MORNING WITH CLOUDY SKIES AND LIGHT SHRAS TO THE NORTH AND SUNNY SKIES TO THE SOUTH. GFS/RUC MODELS SHOW WEAK ISENTROPIC LIFT CONTINUING THRU THE AFTERNOON. NOT MUCH MOVEMENT TO THE FRONT EXPECTED IN THE NEXT 18 HRS. MAYBE AN ISOLD TSRA IN THE SW AS INSTABILITY BUILDS BUT NOT MUCH IN THE WAY OF FORCING && .SHORT TERM /NOON TODAY THROUGH 6 PM MONDAY/... OVERRUNNING PRECIP...NORTH OF BOUNDARY...WILL MOVE ACROSS NORTHERN ZONES TONIGHT. TRENDED FROM HIGH LIKELY TO LOW CHC POPS NORTH TO SOUTH. A SFC LOW APPEARS TO SLIDE EAST ALONG THE BOUNDARY MONDAY AFTN. I WILL ASSUME THE BOUNDARY WILL BE STATIONED ACROSS SOUTHERN ZONES. AS A RESULT CONTINUED THE WET WX BUT WILL ALSO KEEP A MENTION OF THUNDER GIVEN ADDITIONAL FORCING FROM SFC LOW. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... MONDAY NIGHT THROUGH WEDNESDAY A WAVY FRONT WILL REMAIN ACROSS THE MID ATLANTIC THROUGH TUESDAY NIGHT. SEVERAL WEAK WAVES APPEAR TO TRACK ALONG THE FRONT...BRINGING THE BEST RAINFALL CHANCES THE REGION HAS SEEN FOR QUITE SOME TIME. PRECIPITABLE WATER VALUES RISE TO NEAR 2 INCHES...WELL ABOVE THE NORMAL OF 1.1 INCHES. PRECIPITATION CHANCES WILL COME WITH HARD-TO-TIME WEAK WAVES MOVING ALONG THE FRONTAL BOUNDARY. GUIDANCE STILL SHOWS THAT THE NORTHERN HALF OF THE FORECAST AREA HAS THE BEST CHANCE OF SEEING NOTICEABLE PRECIPITATION WHILE THE SOUTHERN HALF OF THE FORECAST AREA COULD BE LEFT HIGH AND DRY. OVERALL...INCOMING CLOUD COVER ASSOCIATED WITH THE FRONT WILL SPREAD NORTH AND SOUTH RATHER FAR...AND THIS SHOULD HELP TO KEEP TEMPERATURES WELL BELOW NORMAL. THURSDAY THROUGH SATURDAY... HIGH PRESSURE WILL BUILD ONCE THE FRONT HAS EXITED THE REGION...BRINGING A RETURN TO A MORE TYPICAL WARM AND HUMID AIRMASS. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS THRU 00Z MON. SHOULD SEE CEILINGS GRADUALLY LOWER DURING THE DAY. EXPECT MVFR CEILINGS AND VISIBILITIES DUE TO CLOUDS AND LIGHT PRECIP STARTING THIS EVENING. TSTMS POSSIBLE MON. THE NEARLY STATIONARY FRONTAL BOUNDARY WILL LINGER THROUGH LATE TUESDAY INTO EARLY WEDNESDAY...MAINTAINING CHANCES OF MVFR AND EVEN TEMPORARY IFR CEILINGS AND VISIBILITIES WITH SHOWERS AND THUNDERSTORMS POSSIBLE THROUGHOUT. HIGHEST CHANCES FOR PROLONGER MVFR OR IFR CONDITIONS WILL BE FOR THE WASHINGTON...BALTIMORE...AND MARTINSBURG TERMINALS. && .MARINE... WARM FRONT DEVELOPING ACROSS THE NORTHERN BAY TODAY. SOUTH OF THE FRONT...SOUTHERLY CHANNELING WINDS INCREASE TO A LOW END SCA SO HAVE ISSUED SCA FOR THIS AFTERNOON AND EVENING FOR THE LOWER BAY. WRF-ARW INDICATES A BNDRY ACROSS THE NORTHERN BAY WHICH DRIFTS SOUTH THIS EVENING. LIGHT...10 KNOTS OR LESS...AND VARIABLE WIND DIRECTIONS EXPECTED OVER THE WATERS WITH A NEARLY STATIONARY...WAVY FRONTAL BOUNDARY OVER THE REGION. CONSISTENT CHANCES OF SHOWERS AND THUNDERSTORMS REMAIN THROUGH TUESDAY WITH THE BOUNDARY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...ROSA LONG TERM...SAR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1101 AM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFF THE COAST TODAY...AS A WARM FRONT MOVES BACK NORTH INTO THE AREA THIS AFTERNOON. THE FRONT WILL STALL OVER THE NORTHERN MID ATLANTIC REGION MONDAY AND TUESDAY. THIS WILL PROVIDE ANOTHER CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS. WEAK HIGH PRESSURE WILL THEN TAKE CONTROL THROUGH THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATEST SATL SHOWING ZONE OF ISENTROPIC LIFT/LOW CLOUD BANK ACRS THE PIEDMNT. RUC DEPICTS THIS WELL IN 300-305K LEVEL...AND TRACKS THIS FARTHER TO THE NE BY MID AFTN. IN ADDITION...CAN SEE CU POPPING ACRS CSTL CAROLINAS. HAVE ADDED 30% POP TO THE FCST FOR MD ZONES...AND 20% MUCH OF INTERIOR AREAS. MAY STAY CLDY ALL DAY FAR NORTHEAST. FOR TEMP FCST TRENDED HIGHS DOWN ANOTHER DEGREE OR TWO ACRS NRN ZONES WHERE MORE CLOUDS WILL STAY ARND ALL DAY. BEST RAIN CHANCE EASILY COMES TNGT. ISENTROPIC UPGLIDE DEPICTED BY BOTH MODELS ALONG AND NORTH OF FRONT...RESULTING IN HIGH CHC TO LKLY POPS OVER NORTHERN TIER OF CWA (LKU TO WAL AND NORTH)...WITH SILENT POPS OVER SOUTHERN THIRD OF CWA. RAIN DOES APPEAR AS IF IT WL BE A (VERY MUCH WELCOME) LGT AND STRATIFORM RAINFALL...SO CHOSE TO STICK WITH SHRA VICE TSRA. USED A MAV/FWC BLEND FOR LOWS THIS EVENING...RESULTING IN LOWS IN THE U60S/ARND 70. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... DETERMINING FRONTAL POSITION HAS PROVED TO BE THE BIGGEST FORECAST CHALLENGE THROUGH MONDAY EVENING. MODELS SEEM TO POINT TWDS FRONT REMAINING NEARLY STATIONARY/WAVERING SLIGHTLY THROUGH MON NGT...WITH INCREASINGLY MOIST AIR MASS CARRING OVER TO BEGIN THE WORK WEEK. GENERAL TREND OF INCREASING CLDS MONDAY HAS BEEN KEPT IN TACT. GIVEN THIS THICKER CLOUD COVER...ESPECIALLY OVER THE NORTH...TEMPERED MOS VALUES SLIGHTLY FOR MAX T MONDAY. THIS YIELDED QUITE A THERMAL GRADIENT. U80S/NR 90 OVER THE NW...WITH L/M90S ELSEWHERE INLAND. MEANWHILE...TEMPS ONLY IN UPPER 70S/L80S IN MD. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LATEST RUNS OF GFS/ECMWF CONTINUE TO SHOW THE PERSISTENT MID LEVEL RIDGE ACRS GULF COAST STATES...WHICH WILL KEEP HURRICANE DEAN WELL TO OUR SOUTH (SEE LATEST OFFICIAL FCST FROM NHC/TPC FOR DETAILS). TUE AND WED...MID ATLC REMAINS IN BETWEEN SFC HIGH PRESSURE ACRS NEW ENGLAND...AND WEAK HIGH PRESSURE ACRS SC/GA. GFS/ECMWF MEAN POSITION OF SFC TROUGH/STATIONARY FRONT IS ACRS NRN PORTION OF THE CWA BOTH DAYS. HAVE CHC POPS NORTH...SCHC SOUTH BOTH DAYS. TEMPS AGAIN MUCH COOLER ACRS NE ZONES. FRONT LOOKS TO LIFT FARTHER NORTH LATE WED...AND FOR PERIOD THU THROUGH SAT HAVE GONE WITH JUST 20% DIURNAL TSTMS (OR LESS) AND HIGHER TEMPS MAINLY BACK INTO THE 90S CWA WIDE. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... SC CLOUD DECK AND ASSCTD -RA MOVG SE FROM DC AREA THIS AM...ALTHOUGH ECHOES HAVE BEEN WEAKENING. DESPITE THIS...DECIDED TO ADD A 2 HR TEMPO PRD FOR -RA THIS AM AT SBY. GAVE RIC MORE CLOUDS NXT FEW HRS AS WELL. MODELS CONT THE WETTER TREND AT SBY TONITE...SO TRENDED THE SBY TAF MORE PESSIMISTIC WRT CLOUD COVER/VSBY IN -RA AT SBY (MVFR RANGE). RIC MAY SEE BKN SC DECK...BUT LTL IN WAY OF PCPN. && .MARINE... WNDS SLOWLY INCRG PAST HR OR SO. WILL HAVE TO BE WATCHED FOR PSBL SCA ACROSS CURRITUCK SND THIS AFTRN. OTW...VRY CHALLENGING FCST THIS AM AS INCRG WNDS AND SEAS WILL RESULT IN SCA CONDITIONS AS VARIOUS TIMES ACROSS MARINE AREA FOR THE NXT SVRL DAYS. ALL MODELS NOW INCRS S-SE FLOW (BTWN 15-20 KTS) OVR CHES BAY THIS AFTRN. SO..IN COORD WITH LWX...HAVE HOISTED SCA`S FOR CHES BAY THRU ERLY EVE. GRDNT SLOWER TO INCRS ACROSS CURRITUCK SND... SO HELD BACK ON SCA THERE UNTIL AFTR MIDNITE...BUT CONT IT THRU MOST OF MON. BUFKIT SHOWNG GUST PTNTL UP TO 25 KTS ACROSS NRN CSTL WTRS AFTR MIDNITE TONITE AS WELL AS INCRG SEAS TO 5 FT. SO...IN COORD WITH PHL...HAVE HOISTED SCA FOR MD CSTL WTRS LATE TONITE THRU MON. ENDED FLAGS MON AFTRN AS FIRST EVENT ENDS. NXT EVENT WILL BE NRLY SURGE BEHIND FRNT LATE MON AFTRN. WILL NOT HEADLINE FOR THIS EVENT ATTM (AS IT WILL PRBLY LEAD TO SOME CONFUSION AS TO JUST WHEN SCA`S END AND BEGIN). WILL LET LATER SHIFTS DECIDE THIS. SUFFICE IT TO SAY THAT ANTHR 4-6 HR NRLY SURGE XPCTD DOWN CHES BAY LATER MON...BUT CONFIDENCE RTHR LOW ATTM AS TO THE EXACT HRS THIS OCCURS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 AM TO 6 PM EDT MONDAY FOR ANZ650. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR ANZ630>632. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EDT MONDAY FOR ANZ633. && $$ SYNOPSIS...BROWN NEAR TERM...BROWN SHORT TERM...MAM LONG TERM...BROWN/MAM AVIATION...MPR MARINE...MPR/KCS md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1220 PM EDT SUN AUG 19 2007 .SYNOPSIS... A WEAK FRONT ACROSS SOUTH CAROLINA WILL DISSIPATE THIS MORNING. HIGH PRESSURE OFFSHORE WILL EXTEND WESTWARD ACROSS THE CAROLINAS THROUGH TUESDAY. WARM...HAZY AND HUMID CONDITIONS ARE EXPECTED MUCH OF THE WEEK. A WEAK COLD FRONT WILL ATTEMPT TO MOVE SOUTH FROM VIRGINIA INTO THE CAROLINAS BY THURSDAY...POSSIBLY PROVIDING TEMPORARY RELIEF. && .NEAR TERM /THROUGH TODAY/... EXTENSIVE CUMULUS FIELD NOW COVERING ALL MOST OF THE CWA WITH THE EXCEPTION OF THE FAR SOUTHERN COUNTIES. LATEST RUC AND GFS FOR THAT MATTER SHOW A LITTLE SEA BREEZE ACTIVITY THIS AFTERNOON. LATEST RADAR LOOPS DO SHOW A FEW RETURNS TRYING TO DEVELOP BUT VERY DRY MID LEVELS EVIDENT ON MORNING SOUNDINGS AND WATER VAPOR IMAGERY ARE INHIBITING ACTIVITY. OTHER THAN A TWEAK TO CLOUD COVER GRIDS...NO OTHER CHANGES. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... VERTICALLY STACKED HIGH PRESSURE FROM 700 MB UP THROUGH AT LEAST 200 MB WILL SIT OVER SOUTH CAROLINA THROUGH TUESDAY. THE HIGH WILL THEN SLOWLY RETROGRADE WEST WEDNESDAY. LARGE SCALE SUBSIDENCE AND SUBSEQUENT WARM DRY AIR ALOFT WILL ALSO KEEP CLOUDS AND PRECIPITATION AT A MINIMUM TONIGHT THROUGH TUESDAY. BELOW 850 MB...HIGH PRESSURE IS CENTERED OFFSHORE AND WILL KEEP A VERY CLIMATOLOGICAL SOUTH-SOUTHWESTERLY FLOW ACROSS THE CAROLINAS. AFTERNOON SEABREEZES WILL TRANSFER MOMENTUM INTO LOW LEVEL JETS EACH OF THE NEXT SEVERAL NIGHTS. THE ONLY EFFECT FROM THESE 20-30 KT LOW LEVEL JETS WILL BE WARM NIGHTS WITH 5-10 MPH SURFACE WINDS. BY WEDNESDAY...THE RETROGRESSION OF THE UPPER RIDGE WILL OPEN UP THE EASTERN CAROLINAS TO THE POSSIBILITY OF SLIGHT COOLING OF THE MID LEVELS WITH ANY UPPER LEVEL ENERGY ABLE TO DIVE SOUTH AROUND THE PERIPHERY OF THE RIDGE. WILL ONLY INTRODUCE 20 POPS AT THIS TIME ACROSS SOUTHEAST NC. THERE ARE SOME SUBTLE BUT SIGNIFICANT DIFFERENCES BETWEEN THE GFS AND NAM MODELS DEVELOPING LATE TUESDAY INTO WEDNESDAY. THE GFS IS MORE BULLISH PUSHING A RATHER STRONG VORT ACROSS NORTHERN NC WHICH DRIVES A SURFACE COLD FRONT INTO THE STATE. THE NAM IS MUCH WEAKER WITH THE VORT AND FARTHER NORTH WITH THE FRONT. AFTER COLLABORATION WITH WFO MHX...WE WILL FOLLOW THE NAM SOLUTION WHICH KEEPS THE FRONT TO THE NORTH. && .LONG TERM /THURSDAY THROUGH SATURDAY/... 595 DAM H5 RIDGE CENTERED NEAR SAV TO START THE PD. THIS FEATURE WILL SLOWLY RETROGRADE THROUGH THURSDAY AND THEN EXPAND SLIGHTLY BACK TO THE EAST WHILE REMAINING CENTERED OVER AL BY FRIDAY. THIS WILL MEAN A CONTINUATION OF ABV CLIMO TEMPS FOR MOST OF THE TIME. OPERATIONAL GFS BUILDS THE RIDGE MORE SHARPLY THAN MOST ENSEMBLE RUNS SO MEX STRINGS HAVE BEEN SLIGHTLY UNDERCUT. PRECIP CHANCES WILL BE MOST AFFECTED BY LOW LEVEL FEATURES GIVEN THE FAIRLY MINIMAL CHANGES IN THE UPPER PATTERN. PIEDMONT TROUGHINESS DEVELOPING SLOWLY ON WEDNESDAY WILL ACT TO IMPORT SOME LL AND MIDLVL MOISTURE BUT NOT ENOUGH TO WARRANT POPS EXCEPT FOR AT NIGHT. SLGT CHANCE POPS THEN SEEM TO BE PLAUSIBLE FOR THE REST OF THE WORK WEEK AS PW VALUES ARE AT OR SLIGHTLY ABV CLIMO BUT FORCING REMAINS QUITE WEAK. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SOUTHEAST FLOW WILL PREVAIL LATER TODAY...WITH VAD WIND PROFILE AND SKEW-T SHOWING MAINLY SOUTHEAST TO EAST FLOW AT MOST LEVELS BELOW 500 MPH. SOME ISOLATED SEA BREEZE ACTIVITY POSSIBLE AFTER 18Z...BUT NO TEMPO OR MENTION AT THIS TIME. MVFR OR POSSIBLE IFR FOG/STRATUS AGAIN TOWARD THE END OF THE FORECAST PERIOD. ISOLATED THUNDERSTORMS ON TUESDAY...SCATTERED WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TODAY/... BUOY OBS SHOW ESE WINDS STILL A SOLID 15 KT...AS KLTX VWP INDICATES JETTING AROUND 20 KT AT 1000 FEET. SEAS RUNNING AROUND 3 FT...WITH A 17 SEC ESE SWELL STARTING TO SHOW UP. NOCTURNAL JETTING WILL WEAKEN AFTER DAYBREAK...ALLOWING WINDS TO VEER TO SE AS THE PATTERN BECOMES MORE SEABREEZE-DOMINATED. WILL KEEP CONDITIONS BELOW THRESHOLDS...CAPPING SPEEDS AT 15 KT AND SEAS AT 4 FT. SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY CLIMATOLOGICAL SOUTH TO SOUTHWESTERLY WIND DIRECTION THROUGH THE PERIOD. WIND SPEEDS WILL INCREASE TO A SOLID 15 KNOTS EACH OF THE NEXT SEVERAL AFTERNOONS AND EVENINGS IN ASSOCIATION WITH THE SEABREEZE. STRONGEST WINDS ARE LIKELY TO BE LOCATED NEAR THE BEACHES BETWEEN THE HOURS OF 3 PM AND 9 PM. THE BIGGEST WEATHER IMPACT TO MARINERS OVER THE NEXT SEVERAL DAYS IS LIKELY TO BE SWELL FROM HURRICANE DEAN. THE WAVEWATCH MODEL WAS NEARLY PERFECT IN SHOWING THE 17-18 SECOND FORERUNNER SWELLS DEVELOPING YESTERDAY EVENING. IT NOW FORECASTS THE SWELL HEIGHT TO INCREASE TO 3-4 FT EVERY 10-12 SECONDS BY TUESDAY AND WEDNESDAY. THESE LONG PERIOD SWELLS WILL CARRY A LOT OF ENERGY AND WILL MAKE BAR AND INLET CONDITIONS QUITE ROUGH...PARTICULARLY AROUND LOW TIDE. SURFERS WILL ENJOY THE NICE SURF EXPECTED TUESDAY AND WEDNESDAY MORNINGS BEFORE THE SEABREEZE ADDS A WIND CHOP TO THE OCEAN. LONG TERM /THURSDAY THROUGH FRIDAY/... PRESSURE PATTERN QUITE TYPICAL OF AUGUST WITH HIGHEST VALUES IN THE WRN ATLANTIC AND A SWRLY FLOW LOCALLY. SERLY DEAN SWELL IS PROGGED TO BE ALL BUT GONE JUST BY THE START OF THE PD. GUIDANCE SHOWS A SECONDARY SWELL FRONT ARRIVE FROM THE EAST ON THURSDAY BUT THE GFS SEEMS TOO STRONG AND TOO FAR N WITH THE SFC WAVE/LOW AT THIS POINT. REGARDLESS...MOST OF THE PD WILL BE CHARACTERIZED BY SWRLY FLOW CAPPED AT 15 KT AND SEAS 2 TO 4 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...SHK SHORT TERM...TRA LONG TERM...BACON AVIATION...HDL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 938 AM CDT SUN AUG 19 2007 .DISCUSSION... QUIET MORNING ACROSS THE FORECAST AREA WITH MOSTLY SUNNY SKIES AND TEMPERATURES MAINLY IN THE 80S. REMNANTS OF TROPICAL STORM ERIN SEEM TO BE MOVING MORE DUE EAST AT THE MOMENT. LATEST RUC MODEL CONTINUES SHOWING THE REMNANTS MOVING NORTHEAST. WILL KEEP AN EYE ON THE MOVEMENT AND MAY UPDATE POPS LATER IF CONDITIONS WARRANT. WILL SEND AN UPDATE TO REMOVE MORNING WORDING BUT AT THIS POINT NO OTHER CHANGES ARE NEEDED. && .PREV DISCUSSION... /ISSUED 305 AM CDT SUN AUG 19 2007/ DISCUSSION... SKIES WERE MOSTLY CLEAR THIS MORNING WITH SOME STATIONS REPORTING SOME LIGHT FOG/HAZE...MAINLY WHERE IT RAINED YESTERDAY. TEMPERATURES RANGED FROM THE LOWER 70S TO NEAR 80S DEGREES AND DEW POINTS RANGED FROM THE UPPER 60S TO MID 70S. VERY LITTLE CHANGE EXPECTED TODAY...WITH DEADLY HEAT STILL THE MAIN FOCUS. MAX TEMPERATURES TODAY WILL REACH NEAR 100 DEGREES WITH HEAT INDICES AROUND 105 OR GREATER. PERHAPS WHERE IT RAINED...TEMPS MAY BE HARD PRESSED TO REACH 100 BUT HUMIDITY LEVELS WILL COUNTERACT THAT AND MAKE IT FEEL MUCH WARMER THAN THE AMBIENT TEMPERATURE. EXPECT A FEW THUNDERSTORMS AGAIN THIS AFTERNOON NEAR PEAK HEATING. SOME OF THESE STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS IN EXCESS OF 50 MPH AND SMALL HAIL. THE LARGE COMPLEX OF THUNDERSTORMS THAT EXPLODED OVER WEST/CENTRAL OKLAHOMA YESTERDAY EVENING WILL TRANSLATE ALONG THE W/NW FRINGE OF THE UPPER HIGH AND CLIP A SMALL PORTION OF THE NORTHWEST FORECAST AREA MONDAY. THUS THE ASSOCIATED CLOUD COVER WILL INHIBIT DAYTIME TEMPERATURES FROM MAKING IT INTO THE TRIPLE DIGITS. GUIDANCE NUMBERS ARE MUCH COOLER FOR MONDAY...AND BASED ON PERSISTENCE HAVE OPTED TO FORECAST ABOUT FOUR DEGREES WARMER THAN GUIDANCE. THIS HINGES ON A COUPLE OF GIVENS...SUCH AS NO RAINFALL AND MINIMAL CLOUD COVER. SOMETHING TO MONITOR FOR THE NEXT FORECAST. SOME AREAS ACROSS THE FORECAST AREA WILL REACH HEAT ADVISORY CRITERIA ON MONDAY. ANTICIPATE THE UPPER HIGH TO BUILD WEST OVER THE MID SOUTH TUESDAY BRINGING TRIPLE DIGIT TEMPERATURES BACK INTO THE FORECAST AND A HEAT ADVISORY TUESDAY THROUGH THURSDAY. THE UPPER HIGH BREAKS DOWN AND WEAKENS A LITTLE BY NEXT WEEKEND WHICH SHOULD DROP TEMPERATURES INTO THE MID 90S. && .PRELIMINARY POINT TEMPS/POPS... MEM 100 77 97 77 / 20 20 20 20 MKL 99 73 98 72 / 20 20 20 20 JBR 98 74 94 73 / 20 20 20 20 TUP 98 74 97 72 / 10 20 20 20 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLAY-CRAIGHEAD- CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI- PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DUNKLIN-PEMISCOT. MS...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ALCORN-BENTON MS- CALHOUN-CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS- MARSHALL-MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN- TALLAHATCHIE-TATE-TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA. TN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CHESTER-CROCKETT- DECATUR-DYER-FAYETTE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON- LAUDERDALE-MADISON-MCNAIRY-SHELBY-TIPTON. HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS EVENING FOR CARROLL-GIBSON-HENRY-LAKE-OBION-WEAKLEY. && $$ tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 215 PM EDT SUN AUG 19 2007 .SHORT TERM...MSAS ANALYSIS SHOWS HIGH PRESSURE HAS SETTLED IN OFF THE CAROLINA COAST PROVIDING AN EASTERLY FLOW REGIME FOR THE AREA. OVER THE SOUTHERN SECTIONS OF THE FORECAST AREA...THERE ARE SUBTLE INDICATIONS OF A COASTAL TROUGH WHICH HAS RESULTED IN MOSTLY SPRINKLES WITH ISOLATED SHOWERS OVER COASTAL WATERS. FOR THE REMAINDER OF THIS AFTERNOON...THE MOST SIGNIFICANT OF THE SHORTWAVE ENERGY HAS LIFTED NORTH OF THE AREA AND RUC DIFFERENTIAL PVA ANALYSIS SHOWS A LARGE ARE OF SUBSIDENCE OVER THE ENTIRE FORECAST AREA. IN ADDITION...DRIER AIR NOTED ON THE WATER VAPOR STREAMING IN OFF THE ATLANTIC SHOULD HELP CURB CONVECTIVE DEVELOPMENT AND CURRENT 20 POPS LOOK SUFFICIENT. FOR MONDAY...500 MB HIGH STRENGTHENS FURTHER TO 596 DAM AND SETTLES DIRECTLY OVER NORTHEAST FLORIDA. THIS WILL CONTINUE TO KEEP POPS AT A MINIMUM WITH THE OCCASIONAL EARLY MORNING SOUTHERN COASTAL SHOWER ALWAYS A POSSIBILITY. THE REAL STORY WILL BE THE CONTINUED HOT TEMPS WITH MID 90S IN STORE FOR INLAND LOCATIONS. ALTHOUGH DEWPOINTS LOOK A LITTLE LOWER THAN PREVIOUS EVENT...WILL NEED TO MONITOR CLOSELY FOR POSSIBLE HEAT ADVISORIES THROUGHOUT THE WEEK. TUESDAY AND WEDNESDAY...AS DEAN PASSES WELL TO THE SOUTH OF FLORIDA...STACKED HIGH CONFIGURATION WILL BE A MAINSTAY OVER OUR AREA WITH NIL TO SLIGHT CHANCE POPS EACH DAY. .LONG TERM...MID AND UPPER LEVEL HIGH RETROGRADES WEST BY THE END OF THE WEEK AND SURFACE HIGH BREAKS DOWN WITH A TROUGH DIPPING DOWN FROM THE MID-ATLANTIC. ALL THIS POINTS TO SOME SLIGHT RELIEF FROM THE EXTREME HEAT AND POPS INCREASING...ESPECIALLY OVER THE NORTHERN SECTIONS. THERE ARE A COUPLE OF WEAK WAVES INDICATED BY THE GFS FOR THE WEEKEND WITH THE FIRST LOOKING TO IMPACT SOUTH FLORIDA EARLY SATURDAY AND GRADUALLY EXTEND NORTHWARD THROUGH SUNDAY. WAY TO FAR OUT TO GET INTO MANY DETAILS AND CURRENT SCT POPS IN THE GRIDS LOOK SUFFICIENT FOR NOW. && .AVIATION...VIS IMAGERY SHOWS SCT-BKN CU FIELD BUT CLOUDS ARE ABOVE 3000 FT. TONIGHT...BRIEF MVFR VIS POSSIBLE TOWARD MONDAY MORNING DUE TO INCREASED SUBSIDENCE ALOFT AND LIGHT BOUNDARY LAYER WINDS EXCEPT FOR SSI WHERE MIXING WILL BE MORE PREVALENT. && .MARINE...NO HEADLINES FOR NOW. IT HAS BEEN NOTED FOR THE PAST 12-18 HRS THAT SEAS HAVE INCREASED A BIT MAINLY DUE TO E TO SE SWELLS INCREASING BY 1-2 FT. HAVE ADJUSTED WNA WAVE GUIDANCE A BIT FOR NEXT 48 HRS AND STILL LOOKS LIKE A SMALL AREA OF 5-6 FT SEAS POSSIBLE OVER THE SE OFFSHORE WATERS FROM LATE MON INTO EARLY TUE. OTHERWISE...WINDS LOOK TO REMAIN AT OR BELOW 15 KT FOR THE PERIOD AT THIS TIME AND SEAS AT OR BELOW 5 FT. RIP CURRENT RISK TO REMAIN ELEVATED IN THE MODERATE CATEGORY AT LEAST THROUGH MID WEEK DUE TO ONSHORE FLOW AND ESE SWELLS. && .PRELIMINARY POINT TEMPS/POPS... AMG 71 96 72 96 / 20 10 10 0 SSI 79 90 78 89 / 10 10 10 0 JAX 74 93 74 93 / 20 10 10 10 SGJ 76 90 76 89 / 20 10 10 0 GNV 72 95 71 94 / 20 20 10 20 OCF 73 94 72 94 / 20 20 10 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ DEESE/SHASHY/WALKER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 335 PM CDT SUN AUG 19 2007 .SYNOPSIS... NEARLY STATIONARY FRONT WOBBLING NORTH ACROSS THE STATE LATE THIS AFTERNOON WITH TROPICAL MOISTURE FEED WELL IN PLACE ONCE AGAIN. THUNDERSTORMS CONTINUE TO DEVELOP NORTH OF BOUNDARY ACROSS SOUTHERN MN AND ARE HEADING EAST ALONG H850 FRONTAL ZONE. OVER SOUTHERN SECTIONS OF THE FORECAST AREA...CONTINUE TO SEE INFLUX OF OLD ERIN MOISTURE WITH AREAS OF THUNDERSTORMS INCREASING. MAINTAINING FLASH FLOOD WATCH TONIGHT ACROSS THE NORTH WHERE ADDITIONAL RAINFALL EXPECTED. SOUTHERN PORTIONS CAN TAKE A FEW INCHES WITH LESS IMPACT EXPECTED THERE. .SHORT TERM...TONIGHT... DEEP TROPICAL MOISTURE PLUME CONTINUES TO STREAM NORTH INTO THE STATE TNT. THOUGH THE GREATEST LIFT INITIALLY APPEARS TO BE ALONG AND NORTH OF THE IA-MN BORDER...RUC MODEL HAS COME AROUND TO SHOW INCREASING LIFT WITH STRONGER AND MORE NORTHERLY MOISTURE TRANSPORT OVER THE ENTIRE FORECAST AREA THIS EVENING AND GRADUALLY SHIFTING THE GREATER MOISTURE TRANSPORT MORE EAST NORTHEAST BY 03Z LATER THIS EVENING. H700 WAVE OVER THE DAKOTAS SHOULD HELP KEEP PATTERN PROGRESSIVE OVER THE NORTH THOUGH SOME STORMS EXPECTED TO FIRE INTO THE WARM SECTOR THIS EVENING ALONG THE FRONTAL BOUNDARY AS IT DRIFTS SOUTHEAST WITH TIME. THIS MAY MITIGATE SOME HYDRO ISSUES OVER THE NORTH BUT WILL HOLD ONTO FLASH FLOOD WATCH DUE TO FACT THAT LITTLE IF ANY ADDITIONAL RAINFALL TNT WILL CAUSE PROBLEMS. OLD ERIN STILL A PROBLEM...AS MOISTURE TRANSPORT AND PLUME WILL CROSS THE SOUTHEAST THIRD OF FORECAST AREA THROUGH 06Z...WITH SOME HEAVY RAINFALL POSSIBLE THERE. GFS/NAM MUCH FARTHER EAST WITH TRACK THIS EVENING...AND AM FOLLOWING RUC MORE CLOSELY. FFG RUNNING HIGHER SOUTHEAST COUNTIES WITH VALUES GENERALLY IN THE 2.5 TO 3.5 RAINFALL SO WILL NOT EXTEND WATCH ANY FARTHER SOUTH ATTM THOUGH SOME TOTALS MAY COME IN ABOVE TWO INCHES IN SOME CASES. H700 WAVE NORTH WILL LIFT EAST AFTER 06Z AND RAINFALL SHOULD DIMINISH AT THAT TIME. ACROSS THE SOUTH EXPECT THE RAIN TO DIMINISH BETWEEN THE 04 AND 08Z TIMEFRAME AS OLD ERIN SPINS EAST BY MORNING. FOLLOWING THAT...FOG MAY BECOME AN ISSUE IN THE WAKE OF THE THESE SYSTEMS AS WINDS REMAIN LIGHT BY MORNING. WITH GO WITH AREAS OF FOG FOR NOW. .LONG TERM...MONDAY THROUGH SUNDAY ACTIVE WEATHER PATTERN TO CONTINUE FOR THE WORK WEEK AS THE SURFACE BOUNDARY IS NEVER FORECAST TO LEAVE IOWA UNTIL FRIDAY NIGHT. SEVERAL ROUNDS OF CONVECTIVE WEATHER ARE LIKELY TO OCCUR...WITH HIGHEST PROBABILITES OVER NORTHERN IOWA WHERE SOME HEAVY RAINS HAVE ALREADY FALLEN...MAKING LOCAL FLOODING THE BIGGEST THREAT FOR THE WEEK. WESTERLY FLOW ALOFT WILL PROVIDE ENOUGH SHEAR AT TIMES FOR ISOLATED SEVERE WEATHER. CONDITIONS SOUTH OF THE FRONT WILL REMAIN TROPICAL WITH HIGHS CLOSE TO 90 AND DEWPOINTS WELL INTO THE 70S. TEMPERATURES A BIT MORE PROBLAMATIC NORTH SINCE THERE IS A SLIM POSSIBILITY THAT COOLER AND DRIER AIR COULD SLIP IN FOR A SHORT SPELL. SPECIFICALLY...AFTER TONIGHT HEAVY RAIN CHANCES APPEAR TO BE MOST LIKELY WITH CONVECTIVE COMPLEXES THAT ARE EXPECTED TO DEVELOP MONDAY EVENING AND MOVING ACROSS NORTHERN IOWA...WITH REPEAT ACTION POSSIBLE ACROSS THE SAME AREA TUESDAY NIGHT. RETURN FLOW OF COPIOUS MOISTURE AND THETA-E ADVECTION IS RAPID ACROSS THIS AREA AS A SERIES OF SHORT WAVES COMES OUT IN THE WLY FLOW ALOFT. DIFFICULT TO SEE ENOUGH OF A BREAK IN THIS PATTERN THROUGH THURSDAY NIGHT...SO CHANCES FOR THUNDERSTORMS REMAIN IN THE FORECAST THROUGH FRIDAY. LONGER RANGE MODELS AGREE THAT A RIDGE WILL BUILD SOMEWHAT TO THE WEST PUSHING A SURFACE HIGH INTO IOWA AND THE UPPER MIDWEST FOR FRIDAY AND SATURDAY...WHICH SHOULD END THE PERSISTENT RAIN CHANCES AND DROP TEMPERATURES AND DEWPOINTS BACK TO COMFORTABLE LEVELS. ALL OF THESE RAIN CHANCES LEAVE THE POSSIBILITY OF ADDITIONAL FLASH FLOOD WATCHES AND POSSIBLE RIVER FLOODING EVENTUALLY FOR THE NORTHERN HALF OF THE STATE. CEDAR RIVER IS NOW EXPECTED TO REACH BANK FULL...AND COULD GO HIGHER IF RAINS TARGET THE SAME AREAS FOR A COUPLE OF DAYS IN A ROW. .AVIATION...19/18Z FNTL BNDRY REMAINS DRAPED OVER THE AREA ATTM. THUNDER BREAKING OUT SOUTHEAST RTES/APTS WHERE MOISTURE TRANSPORT INCREASING. FEEL THUNDER NORTH WILL INCREASE DURING LATE AFT/EVENING FCST WITH LOWERING CIGS/VSBYS TOWARD 08-12Z MOST AREAS DUE TO RECENT RAINFALL AND LIGHT WINDS./REV && .DMX WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH THROUGH 4 AM MONDAY IAZ004>007-IA015>017-IA023>028-IA035>039-IA049>050- && $$ SHORT TERM/AVIATION...REV LONG TERM...JUNGBLUTH ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1131 AM CDT SUN AUG 19 2007 .UPDATE... MAIN CONCERN WILL CONTINUE TO BE MOVEMENT OF TROPICAL DEPRESSION ERIN AND TSRA CHANCES ASSOCIATED WITH IT FOR AREAS ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS. CURRENT SATELLITE ANALYSIS AND RADAR TRENDS SUGGEST THAT TD ERIN IS MAKING A GENERAL EASTWARD MOVEMENT. CURRENT 12Z MODELS NOT HANDLING THIS VERY WELL...WITH THE LATEST SHORT TERM RUC HAVING THE BEST HANDLE ON ITS MOVEMENT WHICH TAKES IT MORE EAST-NORTHEAST RATHER THAN NORTH. THIS MORE EASTWARD MOVEMENT WILL HAVE A BIG IMPACT ON POPS AND POSSIBLE SEVERE CHANCES FOR SOUTHEAST KANSAS. CURRENT THINKING IS THAT MOST OF THE CONVECTION WILL STAY SOUTH OR EAST OF THE AREA...BUT CIRRUS SHIELD WITH THIS SYSTEM IS THINNING SOME...WHICH WILL ALLOW MORE HEATING IN SOUTHEAST KS. LOTS OF LOW LEVEL MOISTURE AROUND...SO ANY INCREASED HEATING WILL INCREASE INSTABILITY ACROSS THIS AREA FOR A SCATTERED SEVERE CHANCE. SO WILL CONTINUE WITH SEVERE MENTION IN THIS AREA FOR NOW...AS HIGHER INSTABILITY AND CURRENT DIRECTIONAL SHEAR LOOKS FAVORABLE FOR A SEVERE WEATHER CHANCE. LOW LCL VALUES COULD LEAD TO AN ISOLATED TORNADO THREAT...BUT MAIN CONCERN WILL BE WET MICROBURST POTENTIAL. SEVERE THREAT LOOKS TO DROP OFF TONIGHT AS DIRECTIONAL SHEAR WANES SOME AS SYSTEM MOVE EAST. WILL ALSO MAKE SOME ADJUSTMENTS TO POPS FOR CEN KS AS A MORE EASTWARD MOVEMENT KEEPS PRECIP CHANCES TO THE EAST OF THIS AREA. .AVIATION... FOR 18Z TAF SUITE. MAIN CONCERN WILL BE FOR THE KCNU TAF SITE AS SOME SEVERE CONVECTION IS STILL POSSIBLE IF HEATING CAN MATERIALIZE. SO WILL CONTINUE THIS MENTION IN KCNU. WILL ALSO KEEP A VCTS IN KICT AND KHUT AS SOME ISOLATED TSRA COULD ROTATE NORTH INTO THIS AREA FOR THE AFTERNOON AREAS. LOTS OF LOW LEVEL MOISTURE AROUND...SO STILL COULD SEE SOME MVFR CEILINGS FOR THE KICT/KCNU AND KHUT SITES UNTIL SUNSET. KETCHAM && .PREV DISCUSSION... /ISSUED 619 AM CDT SUN AUG 19 2007/ UPDATE... AVIATION...12Z TAFS [RSL/SLN/HUT/ICT/CNU] IFR/MVFR STRATUS WILL CONTINUE TO AFFECT CENTRAL KS SITES UNTIL MID-LATE MORNING WHEN HEATING/MIXING SHOULD ALLOW IT TO DISSIPATE. T.D. ERIN OVER CENTRAL OK EARLY THIS AM...PROGGED TO MOVE NEWD ACROSS FAR SOUTHEASTERN KS LATER THIS PM/TONIGHT ALTHOUGH IT APPEARS TO BE MOVING DUE EAST AT THIS TIME. THIS TRACK WILL BRING HIGH SHOWER/T-STORM PROBABILITY TO CNU SITE MAINLY AFTER 23Z...WITH CONVECTION MORE ISOLD AT HUT/ICT TODAY. STRONG WIND GUSTS POSSIBLE WITH TS PARTICULARY AT CNU THIS EVE. JMC PREV DISCUSSION... /ISSUED 313 AM CDT SUN AUG 19 2007/ DISCUSSION... SYNOPSIS... TSRA POTENTIAL TO INCREASE TODAY & TONIGHT OVER ESPECIALLY SE KS AS REMNANTS OF "ERIN" CONTINUE NE MIGRATION FROM OK ACROSS SC & SE KS. WITH MID-UPR LOW ASSOCIATED WITH "ERIN" MOVING NE ACROSS CENTRAL OK DEEP-LAYER DIRECTIONAL SHEAR WILL INCREASE MARKEDLY OVER ESPECIALLY SE KS. THEREFORE AN INCREASED POTENTIAL FOR SEVERE THUNDERSTORMS TO EXIST OVER AREAS ALONG & SE OF THE TURNPIKE. WITH TROPICAL AIRMASS INCREASING GRIP ON THE REGION AS EVIDENCED BY SFC DEWPOINTS OF ~75F MIGRATING DUE NORTH ACROSS ERN OK AS WELL AS PRECIPITABLE WATERS OF ~2.5 INCHES...+RA A CERTAINTY IN SE KS BOTH TODAY & TONIGHT. TODAY & TONIGHT: PER "SYNOPSIS" HAVE INCREASED POPS CONSIDERABLY OVER SE KS TO ~70% TSRA WITH "POSSIBLY SEVERE" DESCRIPTOR APPLIED. MULTIPLE THREATS EXIST: DAMAGING WINDS...VERY HEAVY RAINS AND EVEN A COUPLE TORNADOES. (IN FACT TORNADO WATCH #616 JUST WENT INTO EFFECT FOR CENTRAL OK TIL 8 AM CDT.) SOAKED AIRMASS DICTATES LOWERING MAXES A FEW DEGREES ALL AREAS...ESPECIALLY SC & SE KS. AS REMNANTS OF ERIN CONTINUE NE TREK ACROSS SE KS SHRA/TSRA POTENTIAL TO GRADUALLY IN WEST-EAST MANNER IN CENTRAL & SC KS WITH NUMEROUS SHRA/EMBEDDED TSRA CONTINUING OVER SE KS MOST OF THE NIGHT. MON: AS PREVIOUSLY MENTIONED TROPICAL SYSTEM VACATES SE KS PREMISES SHRA TO LINGER INTO THE MORNING WITH LITTLE ADDITIONAL RAINFALL RESULTING. TUE-FRI: FORECAST FOCUS SHIFTS TOWARD FAST WLY MID-UPR DECK FLOW ACROSS NRN PLAINS WITH EMBEDDED SHORTWAVES EJECTING E. BEHAVIOR & TRACKS OF THE FEATURES BEARS WATCHING AS ATTENDANT COLD FRONT WILL KNOCK ON DOORS IN CENTRAL KS FROM TUE NIGHT THROUGH WED NIGHT. SE THRUST OF MID-LVL SHORTWAVES APPEARS LACKING. AS SUCH APPEARS FRONT MAY STALL & PERHAPS RETREAT NWD AS WARM FRONT WED NIGHT. UNTIL BEHAVIOR OF THE FRONT COMES INTO BETTER FOCUS...HAVE FELT IT PRUDENT TO ASSIGN 20-30% POPS TO CENTRAL KS BOTH TUE & WED NIGHTS. AVIATION... 06Z TAF UPDATE...SHOWERS AND A FEW THUNDERSTORMS COULD AFFECT SOUTHERN KANSAS DURING THE EARLY MORNING HOURS. THE ACTIVITY IS EXPECTED TO BECOME MORE WIDESPREAD DURING THE LATE MORNING AND AFTERNOON HOURS. OTHERWISE...LOW CLOUDS WITH POSSIBLE IFR CEILINGS ARE EXPECTED TO FILL IN ACROSS CENTRAL AND SOUTH CENTRAL KANSAS AROUND SUNRISE. THE CEILINGS SHOULD GRADUALLY IMPROVE BY LATE MORNING OVER THE AREA BUT THE RAIN AND THUNDERSTORMS WILL REMAIN OVER THE REGION. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 87 73 94 75 / 50 20 0 0 HUTCHINSON 88 72 96 74 / 30 20 0 10 NEWTON 87 73 95 74 / 40 20 10 10 ELDORADO 86 73 94 74 / 60 40 10 0 WINFIELD-KWLD 87 74 94 75 / 60 40 10 0 RUSSELL 92 70 96 74 / 20 10 0 10 GREAT BEND 92 70 96 74 / 20 10 0 10 SALINA 90 72 97 74 / 30 10 0 10 MCPHERSON 88 72 96 74 / 30 10 0 10 COFFEYVILLE 88 73 89 74 / 80 60 30 0 CHANUTE 88 73 90 73 / 80 60 30 0 IOLA 88 73 91 73 / 70 70 30 10 PARSONS-KPPF 88 73 89 73 / 80 60 30 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 PM EDT SUN AUG 19 2007 .SHORT TERM DISCUSSION (TNGT THRU MON)... LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW RIDGING OVER THE CENTRAL CONUS EXTENDING UP INTO SOUTH CENTRAL CANADA. THIS RIDGE IS BRACKETED BY UPPER LOWS/TROUGHING ALONG THE NORTHWEST COAST AND OVER EASTERN QUEBEC. A SHARPLY DEFINED SHORTWAVE TROUGH CAN BE SEEN ROTATING THROUGH WASHINGTON AND OREGON...AND THIS IS THE NEXT SIGNIFICANT SHORTWAVE FEATURE EXPECTED TO AFFECT THE AREA...ALTHOUGH IT WILL LOSE SOME OF ITS LUSTER AS IT WORKS EASTWARD THROUGH THE UPPER RIDGE. RADAR IMAGERY CONTINUES TO SHOW A WNW-ESE ORIENTED AREA OF PCPN WITH EMBEDDED CONVECTION FROM SOUTHERN MINNESOTA THROUGH NORTHERN INDIANA AND NORTHWEST OHIO. THIS ACTIVITY CORRELATES WELL WITH AN AREA OF 850-700MB FRONTOGENESIS AND CONVECTIVE INSTABILITY SHOWN BY THE 12Z NAM AND GFS. SOME LIGHTER SHOWERS ARE JUST SOUTH OF THE CWFA OVER NORTHEAST WISCONSIN...AND THERE IS A SLIGHT CHANCE THEY COULD CLIP MENOMINEE COUNTY LATE THIS AFTERNOON OR THIS EVENING...BUT CURRENT OBSERVED TRENDS WOULD KEEP THEM OUT OF THE AREA. MAIN SHORT TERM FORECAST CONCERN IS THE POSSIBILITY OF PCPN AS WELL AS ASSOCIATED TEMPERATURE AND CLOUD COVER ISSUES AS THE WARM FRONTAL BOUNDARY CONTINUES TO LURK TO OUR SOUTH. UTILIZED A COMBINATION OF THE NAM AND GFS...WHICH ARE REASONABLY SIMILAR THROUGH TOMORROW. THE WARM FRONTAL BOUNDARY IS NOT EXPECTED TO MAKE MUCH IF ANY NORTHWARD PROGRESS THROUGH MONDAY. THE NAM AND GFS DO MANAGE TO NUDGE IT SLIGHTLY NORTH LATE TONIGHT AND EARLY MONDAY...WHICH COULD BRING THE SHARP GRADIENT IN CLOUD COVER A BIT FARTHER NORTH...SO ALLOWED FOR SOME INCREASE IN CLOUD COVER DURING THAT TIME FRAME. AS FAR AS PCPN GOES...CONTINUED TO LEAVE IT OUT OF THE FORECAST THROUGH MONDAY. THE FRONTAL BOUNDARY WILL REMAIN ACTIVE THROUGH MONDAY...WITH A PERSIST AREA OF GOOD 850-700MB FRONTOGENESIS INTERACTING WITH AN AREA OF NEGATIVE 850-500MB DIFFERENTIAL THETA-E AND GOOD LOW LEVEL MOISTURE. HOWEVER...THIS AXIS OF CONVERGENCE...FRONTOGENESIS...MOISTURE...AND CONVECTIVE INSTABILITY WILL REMAIN SOUTH OF OUR AREA. IF ANYTHING...THE PERSISTENT PCPN NORTH OF THE BOUNDARY SHOULD REINFORCE THE BOUNDARY AND HELP KEEP IT TIED UP TO THE SOUTH THROUGH MONDAY. IN ADDITION...THE DRY EASTERLY FLOW FROM THE SURFACE HIGH ANCHORED TO OUR NORTH AND EAST SHOULD HELP KEEP ANY RENEGADE SHOWERS AT THE NORTHERN EDGE OF THE ELEVATED FRONTAL BOUNDARY FROM PEELING OFF INTO OUR AREA. WILL HAVE HIGHER POPS NEAR THE WISCONSIN BORDER...BUT WILL KEEP THEM BELOW THE THRESHOLD OF MENTIONING ANY ACTUAL PCPN. IF RADAR TRENDS CHANGE...THEN THERE MAY BE THE NEED TO MENTION AN ISOLATED SHOWER IN SOUTHERN MENOMINEE COUNTY...BUT WILL LEAVE THAT OUT FOR NOW. .LONG DISCUSSION (MON NGT THRU SUN)... QUESTION FOR MON NGT IS WHETHER UPR LO OVER THE PAC NW DRIFTING ACRS SRN CAN CAN GENERATE ANY PCPN OVER THE CWA. CONSIDERING THE PERSISTENT NW FLOW ACRS ERN CAN THAT WL TEND TO HOLD DRY CNDN HI/ ANTECEDENT AIRMASS IN PLACE ACRS THE UPR GRT LKS AND THE PRESENCE OF PERSISTENT/ANNOYING BNDRY TO THE S THAT WL INTERCEPT MSTR RETURN IN ADVANCE OF SLUGGISH UPR LO MOVING ONLY INTO CNTRL CAN AT 12Z TUE... HAVE TENDED TO FOLLOW A SLOWER/DRIER NAM SCENARIO AND RESTRICT POPS TO THE FAR WRN CWA THRU 12Z TUE TO THE W OF MODEST H85 LLJ AXIS (ONLY UP TO 30 KTS) AS SHOWN BY THE BIT MORE PROGRESSIVE GFS. OTRW...RETURN OF HIER PWAT WL TRANSLATE INTO INCRSG MID/HI CLDS ABV LINGERING LLVL DRY AIR. EXPECT LOWEST MIN TEMPS OVER THE INTERIOR E CLOSER TO PERSISTENT HI CENTER/DRIER AIR. ON TUE...GUIDANCE SHOWS COMMA TAIL FEATURE ASSOCIATED WITH SLOW MOVING LO ACRS SCNTRL CAN SWINGING W-E ACRS THE CWA. OPTED TO LOWER GOING 40 POPS TO 30 EXCEPT OVER THE NW SINCE NAM/GFS/UKMET SHOW SHARPER DPVA/H85-3 QVECTOR CNVGC SHIFTING TO THE N OVER ONTARIO... CWA PROGGED TO FALL INTO UNFVRBL RIGHT EXIT OF H3 JET MAX MOVING THRU NRN MN IN SUPPORT OF CYC IN SCNTRL CAN... AND FCST SDNGS HINT AT DRY AIR TRYING TO HOLD IN WITH ABSENCE OF SGNFT HGT FALLS. LOWERED FCST MAX TEMPS CLOSER TO MUCH COOLER MOS GUIDANCE WITH EXPECTATION OF AT LEAST CONSIDERABLE CLD COVER AND LLVL SE FLOW. BEST CHC FOR WARMER TEMPS WL BE OVER THE W...WHERE CLDS MAY THIN LATE IN THE DAY FOLLOWING PASSAGE OF DEEPER COMMA TAIL MSTR TO THE E. ON TUE NGT/WED...12Z UKMET IS FASTER/DEEPER THAN GFS WITH SFC WAVE FCST TO RIDE ENEWD IN WSW FLOW ALF BTWN SLOW MOVING VORTEX ACRS SCNTRL CAN AND UPR RDG OVER THE SE STATES. CUT POPS BACK TO 20 OVER THE ENTIRE FA ON TUE EVNG BEFORE INCRSG POPS TO 30 AFT MIDNGT OVER THE SCNTRL AND E TO ACCOUNT FOR POTENTIAL LO PRES WAVE THAT WOULD RIDE NEWD. MAINTAINED THE LOWER POPS OVER THE NW TO ACCOUNT FOR HIER PROBABILITY WAVE WL TRACK ALG PERSISTENT BNDRY FARTHER S. IN THE MEDIUM/EXTENDED PD FOLLOWING PCPN CHCS ON WED...HI PRES RDG LOOKS TO BE BLDG TOWARD THE FA ON THU. HOWEVER...CONSIDERING SFC FNT HANGS UP JUST TO THE SE OF THE FA...WARY ABOUT A DRY FCST... ESPECIALLY OVER THE SCNTRL AND E. IN FACT...12Z GFS SHOWS A SERIES OF WAVES RIDING ENEWD ON THIS BNDRY AND DUMPING QUITE A PIT OF PCPN ON AREAS SE OF CRYSTAL FALLS TO MQT. THEN QUESTIONS AS TO EXTENT OF SFC DVLPMNT/TRACK OF LO PRES IN THE CNTRL PLAINS FOR THE FRI-SAT TIME. 00Z ECWMF/GFS/UKMET/12Z CNDN SHOW A DEEPER UPR TROF DVLPG IN THE PLAINS WITH THE RESULT A SOMEWHAT DEEPER WAVE TRACKING FARTHER N TOWARD NRN LWR MI FRI NGT WITH DEEPER RH/CYC NE FLOW OVER THE CWA. 00Z CNDN/06Z GFS ON THE OTHER HAND ARE A BIT FLATTER WITH THE TROF/SFC WAVE AND SHOW DEEPER RH/MAIN BODY OF PCPN STAYING TO THE S. 12Z GFS HAS COMPLETELY SHIFTED GEARS AND SHOWS DRY HI PRES BLDG INTO THE AREA ON SAT FOLLOWING PASSAGE OF LAST WAVE ON THE FNT THU NGT. ALTHOUGH 00Z GFS REFCST GUIDANCE APPEARS TO SUPPORT THE 00Z CNDN/06Z GFS SCENARIO...NCEP MANUAL GUIDANCE INDICATES A PREFERENCE FOR THE DEEPER 00Z GFS/ECMWF/UKMET/12Z CNDN FCST. SO FOLLOWED THIS FCST SCENARIO...WITH EXPECTED TEMPS BLO NORMAL ESPECIALLY ON SAT WITH STEADY NE FLOW. THEN COOL/DRIER ON SUN WITH NW FLOW BTWN DEPARTING LO AND CNDN HI PRES BLDG TOWARD THE UPR MS VALLEY. COORDINATED WITH APX/GRB/LOT/DLH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... THERE WILL CONTINUE TO BE A VERY SHARP GRADIENT IN CLOUD COVER AS YOU HEAD SOUTH OF UPPER MICHIGAN. WITH THE EXCEPTION OF SOME DIURNAL CU AND HIGH CIRRUS...LOOK FOR VERY LITTLE IN THE WAY OF CLOUD COVER AT KCMX AND KSAW THROUGH THE DAY. THE CLOUDS TO THE SOUTH WILL TRY TO CREEP A BIT NORTH LATE TONIGHT AND EARLY MONDAY...BUT CEILINGS SHOULD REMAIN VFR...ALTHOUGH SOME MARGINAL MVFR CONDITIONS COULD SNEAK INTO KSAW TOWARD DAYBREAK. THE BETTER MOISTURE AND FORCING WITH THE WARM FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE AREA...SO NO PCPN IS EXPECTED. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... HIGH PRESSURE CENTERED TO THE NORTH AND EAST OF THE AREA WILL GRUDGINGLY SLIDE EAST OVER THE NEXT SEVERAL DAYS AS A WARM FRONT TO THE SOUTH TRIES TO LIFT NORTH. ALTHOUGH THE WARM FRONT WILL PROBABLY NOT MAKE IT NORTH INTO UPPER MICHIGAN...WE WILL EVENTUALLY SEE A COLD FRONTAL BOUNDARY SLIDE THROUGH BY LATE THURSDAY. WITH A HIGH TO THE EAST AND LOWER PRESSURE TO THE WEST...WE WILL GENERALLY SEE EASTERLY FLOW TONIGHT AND MONDAY GIVE WAY TO SOUTHERLY FLOW BY TUESDAY THROUGH THURSDAY. THE PRESSURE GRADIENT WILL BE TIGHTEST OVER THE NEXT 24 TO 36 HOURS WITH 15 TO 25 KT WINDS OVER MUCH OF THE LAKE DURING THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM DISCUSSION...TRH LONG TERM DISCUSSION...KC AVIATION/MARINE...TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 245 PM CDT SUN AUG 19 2007 .DISCUSSION... FORECAST CHALLENGE WITH THIS PACKAGE INCLUDES HEAVY RAIN AND SEVERE WEATHER POTENTIAL AS THE REMAINS OF TROPICAL STORM ERIN MOVE THROUGH SOUTHEAST KANSAS AND SOUTHERN MISSOURI TONIGHT. MODELS NOT HANDLING THE REMNANTS WELL AT ALL. CURRENTLY...LOW CENTERED OVER NORTH CENTRAL OKLAHOMA IN THE VICINITY OF PONCA CITY THIS AFTERNOON. MOISTURE FROM SATELLITE IMAGERY SHOWING AN EASTWARD MOVEMENT WHILE THE SURFACE LOW ITSELF SHOWING A MORE NORTHEAST MOVEMENT. THUNDERSTORMS MOVING THROUGH THE CENTRAL CWA THIS AFTERNOON ARE VERY EFFICIENT RAIN PRODUCERS. WE HAD ALMOST 6/10THS OF AN INCH OF RAINFALL IN TEN MINUTES FROM ONE OF THESE CELLS AS IT PASSED OVER THE OFFICE. RUC CAPES THIS AFTERNOON GENERALLY AROUND 1000 J/KG BASICALLY WHERE THE THUNDERSTORMS ARE FIRING UP. SHEAR VALUES REMAIN HIGH AS 850MB PROFILER WINDS SHOWING 25 TO 30 KNOTS OVER SOUTHWEST MISSOURI AND SOUTHEAST KANSAS. CLOUD COVERAGE KEEPING AFTERNOON TEMPERATURES DOWN. STARTING TO GET SOME SEVERE REPORTS WITH THESE THUNDERSTORMS AND WOULD EXPECT SEVERE THREAT TO CONTINUE THROUGH THE AFTERNOON. TONIGHT INTO MONDAY...SINCE BOTH MODELS HAVING A DIFFICULT TIME WITH REMNANTS OF ERIN...DECIDED TO FOLLOW HPC GUIDANCE. THIS BRINGS THE SURFACE LOW INTO SOUTHWEST MISSOURI SHORTLY AFTER 00Z AND TRACKS THE LOW INTO NORTHEASTERN MISSOURI OVERNIGHT. LOTS OF MOISTURE WITH THE LOW AS IT TRACKS THROUGH WITH 6 HOURLY QPF VALUES OVER AN INCH OVER WESTERN AND CENTRAL MISSOURI. PWATS REMAIN OVER 2 INCHES ON MODEL SOUNDINGS OVERNIGHT. WE HAVE BEEN DRY HERE FOR A LONG TIME AND THE RAIN IS A WELCOMED RELIEF...BUT GIVEN THE RAIN EFFICIENCY OF THESE STORMS...DECIDED TO ISSUE A FLASH FLOOD WATCH FOR THIS EVENING AND OVERNIGHT. WE KEEP A GOOD LOW LEVEL JET FROM THE SOUTHWEST AT 40KTS AROUND MIDNIGHT TONIGHT...SO SEVERE THREAT TO CONTINUE OVERNIGHT. LOW PUSHES OFF TO THE NORTHEAST BY LATE MORNING AND PRECIPITATION SHOULD BE ENDING FROM WEST TO EAST THROUGH THE DAY. TUESDAY ON...RIDGE OF HIGH PRESSURE TO BUILD BACK INTO THE CENTRAL U.S. TUESDAY INTO THE WEEK. GET SOME DISTURBANCES MOVING ALONG THE PERIPHERY OF THE RIDGE THAT MAY SET OFF SOME CONVECTION THROUGH THE WEEK. TEMPERATURES ARE EXPECTED TO CLIMB BACK INTO THE MID 90S THROUGH THE WEEK...THAT WILL GET OUR HEAT INDICES BACK UP TO AROUND OR SLIGHTLY ABOVE 100 DEGREES. GCC && .AVIATION... AT 1715Z...SCATTERED SHOWERS WERE DEVELOPING AROUND THE SPRINGFIELD AIRPORT. KSGF WILL LIKELY EXPERIENCE A COUPLE BRIEF PERIODS OF MODERATE RAIN BEFORE THE AFTERNOON IS OVER. WILL ALSO MONITOR CONVECTION OVER OKLAHOMA AS IT SHIFTS INTO THE OZARKS THIS EVENING. THIS FEATURE IS THE REMNANT CIRCULATION OF TROPICAL STORM ERIN...AND COULD PRODUCE SOME VERY HEAVY RAINFALL ACROSS THE REGION. LOWERING CEILINGS AND VISIBILITIES WOULD BE EXPECTED IF THIS CIRCULATION TRACKS TOWARD THE SPRINGFIELD AIRPORT. THE JOPLIN SITE WILL ALSO NEED TO WATCH THIS AREA OF RAIN CLOSELY...HOWEVER...THIS CONVECTION COULD SHIFT SOUTH OF JOPLIN WITH TIME. PILOTS CAN ALSO EXPECT WIND SPEEDS TO INCREASE WITH TIME THIS EVENING. 15-20 KNOTS WITH HIGHER GUSTS IS NOT OUT OF THE QUESTION. CRAMER && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH FOR AREAS WEST OF A LINE FROM BRANSON TO OSAGE BEACH FROM 9 PM THROUGH 10 AM MONDAY. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 308 PM CDT SUN AUG 19 2007 .DISCUSSION... MAIN CONCERN FOR THE NEXT SEVERAL DAYS IS TIMING OF AND LOCATION OF CONVECTION. UPPER AIR CHARTS FROM THIS MORNING STILL SHOWED A GOOD AMOUNT OF MOISTURE IN THE LOWER AND MID LEVELS OF THE ATMOSPHERE FROM PART OF THE SWRN U.S. AND WEST TX UP INTO ERN NE...WRN IA... SD AND MN. SURFACE ANALYSIS EARLY THIS AFTN SHOWED A FRONT LOCATED FROM NERN IA NWWD BACK TO LOW PRESSURE OVER SWRN MN/NWRN IA THEN SEWD INTO NRN NE...THEN BACK NWWD INTO ERN MT. DEWPOINTS LOCALLY WERE IN THE UPPER 60S TO MID 70S AT MOST LOCATIONS. WATER VAPOR LOOP SHOWED MAIN CONVECTION ASSOCIATED WITH REMNANTS OF ERN ACROSS OK...A WEAK MID LEVEL LOW OVER NWRN MO MOVING NEWD AND A SHORTWAVE TROUGH RESPONSIBLE FOR STORMS OVER SWRN MN/NWRN IA/SERN SD/NERN NE MOVING EWD ACROSS SD AND NE. A MOIST PLUME WAS ALSO INCREASING IN COVERAGE AHEAD OF STRONG SYSTEM OVER THE PACIFIC NW PUSHING INTO THE ROCKIES. 20Z VISIBLE SATELLITE IMAGERY SHOWED SOME ENHANCEMENT TO CLOUDS ALONG FRONT OVER NERN NE. LITTLE OR NO CAP WAS INDICATED BY LATEST RUC MEAN LAYER CONVECTIVE INHIBITION. TONIGHT...EXPECT THAT MOST OF THE CONVECTION THIS AFTERNOON WILL PROBABLY DIE OUT THIS EVENING. WILL KEEP A SMALL CHANCE OF TSTMS GOING AFTER 06Z ACROSS WRN IA FOR CONTINUITY SAKE WITH BORDERING OFFICES. WILL HAVE TO KEEP AN EYE OUT FOR DEVELOPMENT OF LOW CLOUDS AND FOG...WHICH SEEM TO HAVE BEEN RELATIVELY COMMON THE PAST FEW WEEKS. EXPECT LOW TEMPS TO BE MAINLY IN THE LOWER 70S WITH SOME UPPER 60S NORTH. FOR NOW...WILL NOT MENTION A CHANCE OF PCPN LATE TONIGHT IN FAR WESTERN ZONES WITH DISTURBANCE NOW OUT OVER THE ROCKIES...BUT IT IS MOVING QUICKLY. MONDAY...IMPRESSIVE WAVE OVER THE WRN U.S. WILL TRACK NEWD TOWARD SRN ALTA BY 00Z TUESDAY...WITH MAIN PUNCH OF ENERGY MOVING ACROSS THE DKTS. THIS WILL HELP DRIVE A COLD FRONT EASTWARD. 12Z GFS SHOWED VERY WARM 700 MB TEMPS OVER OUR AREA DURING THE DAY (MAINLY 12C TO 15C) BUT ALSO A LOT OF 700 MB MOISTURE (WITH DEWPOINTS UP TO 12 BY LATE AFTN) SO SPC DAY 2 OUTLOOK SEEMED REASONABLE. BULK SHEAR IN THE 0-6 KM LAYER INCREASES TO 30-45 KTS...AND SURFACE BASED CAPE GET UP TO OVER 3000 J/KG. INCREASED POPS A LITTLE FOR THE DAYTIME PERIOD AND INTO THE EVENING. EXPECT HIGHS ABOUT 90 TO 95 CENTRAL AND SOUTH...BUT ONLY UPPER 80S FAR NORTH. CLOUD COVER WILL BE A BIG PLAYER AS TO HOW WARM IT GETS ON MONDAY. UNSETTLED PATTERN WILL CONTINUE MUCH OF THE WEEK WITH FAIRLY FAST FLOW ACROSS THE NRN U.S. AND A FRONTAL BOUNDARY OSCILLATING NORTH AND SOUTH THROUGH THE REGION. KEPT POPS IN THE SLIGHT CHANCE TO CHANCE RANGE. MIGHT BE ABLE TO FINE TUNE THINGS BETTER IN FUTURE FORECAST AS WE GET CLOSER. TIMING IS GOING TO BE PROBLEMATIC... BUT THE TUESDAY EVENING PERIOD AND WEDNESDAY NIGHT INTO THURSDAY NIGHT SEEM POTENTIALLY BUSY WITH HEAVY RAIN POTENTIAL. TUESDAYS HIGHS SHOULD BE 90 TO 95...WEDNESDAYS HIGHS IN THE MID 80S TO LOWER 90S AND THEN EXPECT MAINLY 80S THURSDAY THROUGH SATURDAY. LEFT NEXT WEEKEND DRY FOR NOW. && .AVIATION... FOR THE FOLLOWING TAF SITES...KOFK/KOMA/KLNK CONTINUED INTRUSION OF LOW AND MID LEVEL MOISTURE INTO THE CWA FROM LEFT OVER REMNANTS OF ERIN...WILL CONTINUE TO CAUSE WIDESPREAD CU FIELD ACROSS MUCH OF EASTERN NEBRASKA AND SOUTHWEST IOWA THROUGH THE AFTERNOON HOURS. FURTHER NORTH ALONG NE/SD BORDER... FAIRLY STATIONARY BOUNDARY IS THE FOCUS FOR THUNDERSTORM ACTIVITY... ESPECIALLY NORTH OF THE BOUNDARY INTO MN. VFR CONDITIONS SHOULD PREVAIL FOR MOST OF THE PERIOD UNTIL AROUND THE 09-12Z TIMEFRAME WHEN THE POTENTIAL FOR FOG FORMATION APPEARS TO BE LIKELY DUE TO LOW DEWPOINT DEPRESSIONS AND DECREASED WIND SPEEDS...WHICH COULD LOWER CEILINGS/ VISIBILITIES TO LIFR/LFR CONDITIONS FOR ALL TAF SITES. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DISCUSSION...MILLER AVIATINO...REESE ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 223 PM CDT SUN AUG 19 2007 .SHORT TERM...NOW THROUGH MONDAY NIGHT. BIGGEST CHALLENGE WILL BE CHANCES OF PRECIPITATION. SURFACE BOUNDARY NEAR THE NORTHERN CWA BORDER COULD BE THE FOCUS OF A FEW SHOWERS OR THUNDERSHOWERS IN NORTHERN CWA AND MAY SAG JUST SOUTH INTO THE EXTREME NORTHERN CWA. INCLUDED A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH EARLY EVENING. THIS BOUNDARY SHOULD EVENTUALLY MOVE NORTH TONIGHT AS A WARM FRONT. THE RUC DOES NOT SEEM TO BE DOING A VERY GOOD JOB IN THE FIRST 12 HOURS...WITH THE NAM BEING A BIT CLOSER TO REALITY AS FAR AS PRECIPITATION IS CONCERNED...BUT WITH SOME TIMING ISSUES. AFTER 12 HOURS HOWEVER...THE NAM LOSES MUCH OF ITS CREDIBILITY AND THE GFS LOOKS LIKE IT GENERALLY DOES A BETTER JOB. A QUICKLY MOVING SHORTWAVE TROUGH IS MOVING THROUGH THE NORTHWEST UNITED STATES TODAY AND THE EXTREME SOUTHERN FRINGE OF THIS TROUGH MAY AFFECT THE EXTREME NORTHERN PART OF THE CWA. MODELS GENERALLY SHOW THAT THIS ENERGY SHOULD BE TOO FAR NORTH TO SIGNIFICANTLY AFFECT US. ONE MINOR WORRY IS THAT THE FAR NORTH MAY BE IN THE VICINITY OF THE LEFT FRONT QUADRANT OF A MODEST AND WANING UPPER LEVEL JET. BUT WORKING AGAINST RAINFALL WILL ALSO BE A RELATIVELY DRY LAYER NEAR 850 MB WITH THE LOW LEVEL JET NOT PARTICULARLY STRONG IN THIS REGION. I WILL ULTIMATELY GO DRY FOR LATE TONIGHT AND MONDAY MORNING. THE LATEST RUN OF THE NAM PUTS QPF OVER THE CWA DURING THIS TIME PERIOD...BUT LOOKS STRANGE AS IF THERE ARE SOME CONVECTIVE FEEDBACK ISSUES. FOR MONDAY AFTERNOON AND EVENING THERE IS A CONCERN THAT STORMS MAY DEVELOP IN THE NORTHERN PLAINS IN ASSOCIATION WITH ANOTHER SHORTWAVE MOVING IN AND EVENTUALLY SPREAD SOUTH INTO OUR AREA AS A LOW LEVEL JET DEVELOPS DURING THE EVENING. THE CENTRAL/NORTHERN PART OF THE CWA LOOKS LIKE IT WILL MAINLY STAND THE BEST CHANCE FOR BEING NEAR THE NOSE OF THE LOW LEVEL JET. SEVERE WEATHER IS A POSSIBILITY WITH THIS AND WILL HAVE TO KEEP AN EYE ON IT. I WILL LEAN TOWARD KEEPING THE SLIGHT CHANCE OF PRECIPITATION THAT WE HAVE IN FOR THIS PERIOD ALREADY...BUT MAY BUMP UP CHANCES OF PRECIPITATION IN THE FAR EAST...CLOSER TO WHERE AN MCS IS MORE LIKELY TO DEVELOP. .LONG TERM...TUESDAY THROUGH SUNDAY. FORECAST CONCERN DURING THIS TIME FRAME WILL CONTINUE TO BE CHANCE OF THUNDERSTORMS. OVERALL SCENARIO HAS NOT CHANGED MUCH AS WE END UP ON THE SOUTHERN END OF THE WESTERLIES WITH SURFACE BOUNDARY DROPPING SOUTH INTO OUR AREA AND THEN STALLING OUT...AS EAST/WEST FRONT LIES PARALLEL TO UPPER FLOW. ATTEMPTING TO PIN DOWN TIMING OF THE RAINS WILL CONTINUE TO BE DIFFICULT AS SURFACE FRONT LOCATION NOT COMPLETELY CLEAR CUT AND MAY BE INFLUENCED BY ANY CONVECTION THAT OCCURS THE PREVIOUS DAY. ALSO TOUGH TO TELL WHEN ANY EMBEDDED SHORT WAVE TROUGH WILL TRAVERSE THE PLAINS. DOES APPEAR THAT GFS SUFFERS FROM CONVECTIVE FEEDBACK ISSUES A COUPLE OF TIMES. PRECIPITABLE WATER VALUES AGAIN PRETTY HIGH BY MID WEEK SO HEAVY RAINS POSSIBLE ALONG THE FRONT. BY NEXT WEEKEND THE FRONT MAY PUSH FAR ENOUGH TO THE SOUTH...AS RIDGE TO THE WEST AMPLIFIES...TO KEEP IT DRY HERE AND WILL GO ALONG WITH SCENARIO FOR THE TIME BEING. && .PREV DISCUSSION... /ISSUED 124 PM CDT SUN AUG 19 2007/ AVIATION...18Z TAF. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE FORECAST. ANY THUNDERSTORMS SHOULD BE TO THE NORTH ASSOCIATED WITH A BOUNDARY WHICH LIES WELL TO THE NORTH IN NORTH CENTRAL NEBRASKA. POSSIBLE MID-LEVEL BROKEN LAYER COMING IN OVERNIGHT. THE NAM SUGGESTS A DECREASE IN VISIBLITY...BUT DO NOT SEE A WHOLE LOT TO SUPPORT THIS AND THE NAM HAS RECENTLY BEEN OVERFORECASTING REDUCTION OF VISIBILITIES. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ HEINLEIN/EWALD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 125 PM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE OFFSHORE WILL EXTEND WESTWARD ACROSS THE CAROLINAS THROUGH TUESDAY. WARM...HAZY AND HUMID CONDITIONS ARE EXPECTED MUCH OF THE WEEK. A WEAK COLD FRONT WILL ATTEMPT TO MOVE SOUTH FROM VIRGINIA INTO THE CAROLINAS BY THURSDAY...POSSIBLY PROVIDING TEMPORARY RELIEF. && .NEAR TERM /THROUGH TODAY/... EXTENSIVE CUMULUS FIELD NOW COVERING ALL MOST OF THE CWA WITH THE EXCEPTION OF THE FAR SOUTHERN COUNTIES. LATEST RUC AND GFS FOR THAT MATTER SHOW A LITTLE SEA BREEZE ACTIVITY THIS AFTERNOON. LATEST RADAR LOOPS DO SHOW A FEW RETURNS TRYING TO DEVELOP BUT VERY DRY MID LEVELS EVIDENT ON MORNING SOUNDINGS AND WATER VAPOR IMAGERY ARE INHIBITING ACTIVITY. OTHER THAN A TWEAK TO CLOUD COVER GRIDS...NO OTHER CHANGES. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... VERTICALLY STACKED HIGH PRESSURE FROM 700 MB UP THROUGH AT LEAST 200 MB WILL SIT OVER SOUTH CAROLINA THROUGH TUESDAY. THE HIGH WILL THEN SLOWLY RETROGRADE WEST WEDNESDAY. LARGE SCALE SUBSIDENCE AND SUBSEQUENT WARM DRY AIR ALOFT WILL ALSO KEEP CLOUDS AND PRECIPITATION AT A MINIMUM TONIGHT THROUGH TUESDAY. BELOW 850 MB...HIGH PRESSURE IS CENTERED OFFSHORE AND WILL KEEP A VERY CLIMATOLOGICAL SOUTH-SOUTHWESTERLY FLOW ACROSS THE CAROLINAS. AFTERNOON SEABREEZES WILL TRANSFER MOMENTUM INTO LOW LEVEL JETS EACH OF THE NEXT SEVERAL NIGHTS. THE ONLY EFFECT FROM THESE 20-30 KT LOW LEVEL JETS WILL BE WARM NIGHTS WITH 5-10 MPH SURFACE WINDS. BY WEDNESDAY...THE RETROGRESSION OF THE UPPER RIDGE WILL OPEN UP THE EASTERN CAROLINAS TO THE POSSIBILITY OF SLIGHT COOLING OF THE MID LEVELS WITH ANY UPPER LEVEL ENERGY ABLE TO DIVE SOUTH AROUND THE PERIPHERY OF THE RIDGE. WILL ONLY INTRODUCE 20 POPS AT THIS TIME ACROSS SOUTHEAST NC. THERE ARE SOME SUBTLE BUT SIGNIFICANT DIFFERENCES BETWEEN THE GFS AND NAM MODELS DEVELOPING LATE TUESDAY INTO WEDNESDAY. THE GFS IS MORE BULLISH PUSHING A RATHER STRONG VORT ACROSS NORTHERN NC WHICH DRIVES A SURFACE COLD FRONT INTO THE STATE. THE NAM IS MUCH WEAKER WITH THE VORT AND FARTHER NORTH WITH THE FRONT. AFTER COLLABORATION WITH WFO MHX...WE WILL FOLLOW THE NAM SOLUTION WHICH KEEPS THE FRONT TO THE NORTH. && .LONG TERM /THURSDAY THROUGH SATURDAY/... 595 DAM H5 RIDGE CENTERED NEAR SAV TO START THE PD. THIS FEATURE WILL SLOWLY RETROGRADE THROUGH THURSDAY AND THEN EXPAND SLIGHTLY BACK TO THE EAST WHILE REMAINING CENTERED OVER AL BY FRIDAY. THIS WILL MEAN A CONTINUATION OF ABV CLIMO TEMPS FOR MOST OF THE TIME. OPERATIONAL GFS BUILDS THE RIDGE MORE SHARPLY THAN MOST ENSEMBLE RUNS SO MEX STRINGS HAVE BEEN SLIGHTLY UNDERCUT. PRECIP CHANCES WILL BE MOST AFFECTED BY LOW LEVEL FEATURES GIVEN THE FAIRLY MINIMAL CHANGES IN THE UPPER PATTERN. PIEDMONT TROUGHINESS DEVELOPING SLOWLY ON WEDNESDAY WILL ACT TO IMPORT SOME LL AND MIDLVL MOISTURE BUT NOT ENOUGH TO WARRANT POPS EXCEPT FOR AT NIGHT. SLGT CHANCE POPS THEN SEEM TO BE PLAUSIBLE FOR THE REST OF THE WORK WEEK AS PW VALUES ARE AT OR SLIGHTLY ABV CLIMO BUT FORCING REMAINS QUITE WEAK. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SOUTHEAST FLOW THIS AFTERNOON. CONVECTION TRYING TO FIRE WITH CUMULUS CONGESTUS FORMING AROUND THE AREA. THINK THUNDERSTORMS WILL BE ISOLATED ENOUGH TO LEAVE OUT OF THE TERMINALS FOR NOW. GOOD RADIATION AGAIN TONIGHT WILL BRING MVFR/IFR FOG AFTER 09Z. SEVERITY OF FOG WILL BE LEFT UP TO LATER TAFS. COULD ALSO SEE LIFR STRATUS AGAIN WITH THE WEAK ISENTROPIC LIFT. SOUTHWEST FLOW MONDAY MORNING...WITH A MVFR CEILING ALONG THE COAST POSSIBLE WITH GOOD LOW LEVEL MOISTURE. CONVECTION POSSIBLE TOWARD THE END OF THE FORECAST PERIOD. ISOLATED THUNDERSTORMS ON TUESDAY...SCATTERED WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TODAY/... BUOY OBS SHOW ESE WINDS STILL A SOLID 15 KT...AS KLTX VWP INDICATES JETTING AROUND 20 KT AT 1000 FEET. SEAS RUNNING AROUND 3 FT...WITH A 17 SEC ESE SWELL STARTING TO SHOW UP. NOCTURNAL JETTING WILL WEAKEN AFTER DAYBREAK...ALLOWING WINDS TO VEER TO SE AS THE PATTERN BECOMES MORE SEABREEZE-DOMINATED. WILL KEEP CONDITIONS BELOW THRESHOLDS...CAPPING SPEEDS AT 15 KT AND SEAS AT 4 FT. SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY CLIMATOLOGICAL SOUTH TO SOUTHWESTERLY WIND DIRECTION THROUGH THE PERIOD. WIND SPEEDS WILL INCREASE TO A SOLID 15 KNOTS EACH OF THE NEXT SEVERAL AFTERNOONS AND EVENINGS IN ASSOCIATION WITH THE SEABREEZE. STRONGEST WINDS ARE LIKELY TO BE LOCATED NEAR THE BEACHES BETWEEN THE HOURS OF 3 PM AND 9 PM. THE BIGGEST WEATHER IMPACT TO MARINERS OVER THE NEXT SEVERAL DAYS IS LIKELY TO BE SWELL FROM HURRICANE DEAN. THE WAVEWATCH MODEL WAS NEARLY PERFECT IN SHOWING THE 17-18 SECOND FORERUNNER SWELLS DEVELOPING YESTERDAY EVENING. IT NOW FORECASTS THE SWELL HEIGHT TO INCREASE TO 3-4 FT EVERY 10-12 SECONDS BY TUESDAY AND WEDNESDAY. THESE LONG PERIOD SWELLS WILL CARRY A LOT OF ENERGY AND WILL MAKE BAR AND INLET CONDITIONS QUITE ROUGH...PARTICULARLY AROUND LOW TIDE. SURFERS WILL ENJOY THE NICE SURF EXPECTED TUESDAY AND WEDNESDAY MORNINGS BEFORE THE SEABREEZE ADDS A WIND CHOP TO THE OCEAN. LONG TERM /THURSDAY THROUGH FRIDAY/... PRESSURE PATTERN QUITE TYPICAL OF AUGUST WITH HIGHEST VALUES IN THE WRN ATLANTIC AND A SWRLY FLOW LOCALLY. SERLY DEAN SWELL IS PROGGED TO BE ALL BUT GONE JUST BY THE START OF THE PD. GUIDANCE SHOWS A SECONDARY SWELL FRONT ARRIVE FROM THE EAST ON THURSDAY BUT THE GFS SEEMS TOO STRONG AND TOO FAR N WITH THE SFC WAVE/LOW AT THIS POINT. REGARDLESS...MOST OF THE PD WILL BE CHARACTERIZED BY SWRLY FLOW CAPPED AT 15 KT AND SEAS 2 TO 4 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...SHK SHORT TERM...TRA LONG TERM...BACON AVIATION...HDL nc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD...CORRECTED 430 PM CDT SUN AUG 19 2007 .DISCUSSION... MORE HEAVY RAIN FOR THE NORTHEAST PORTION OF THE FSD CWA TODAY... WITH RADAR ESTIMATES THE HIGHEST ACROSS NORTHERN COTTONWOOD AND NORTHERN MURRAY COUNTIES. MUCH OF SW MINNESOTA AND NW IOWA NOW SATURATED FROM RECENT RAINS...SO ISSUED A FLASH FLOOD WATCH EARLIER TODAY FOR THIS AREA...AND WILL CONTINUE THE WATCH THRU MID EVENING...AS CONVECTION CONTINUES THAT AREA. THIS CONVECTION SHOULD WIND DOWN BY MID/LATE EVENING AS THE UPPER SUPPORT SHIFTS EAST. NORTHWEST IOWA AND ADJOINING COUNTIES OF SOUTHWEST MINNESOTA... SOUTHEAST SOUTH DAKOTA AND EXTREME NORTHEAST NEBRASKA HAS HEATED OUT TODAY...AND IS THE MOST UNSTABLE WITH VERY JUICY LOW LEVEL SOUTH TO SOUTHWEST FLOW. THIS AREA HAS THE HIGHEST RISK OF LATE AFTERNOON AND EVENING SEVERE WEATHER...ESPECIALLY IF THE BOUNDARY LAYER WINDS VEER TO MORE SOUTHERLY OR SOUTHEASTLY PER THE LATEST RUC. SOME RISK OF AN ISOLATED TORNADO THRU EARLY EVENING...ESPECIALLY NEAR THE NORTHWEST IOWA AND SOUTHWEST MINNESOTA BORDER COUNTIES...WHERE THE SHEER WILL BE THE BEST. THE REST OF THE FA WILL BE RAIN FREE MOST OF THE NIGHT...AFTER A FEW ISOLATED EARLY EVENING SHOWERS...BUT FOG... REDUCING VSBYS TO LESS THAN A MILE IN SOME AREAS..WILL BE COMMON LATE TONIGHT THROUGH EARLY MONDAY MORNING. THE CHANCE FOR THUNDERSTORMS WILL INCREASE AGAIN ACROSS THE WEST TOWARD MORNING AS THE NEXT UPPER LEVEL DISTURBANCE APPROACHES...WITH MORE HEAVY RAIN BECOMING LIKELY ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE FA DURING THE DAY MONDAY. TEMPERATURES TONIGHT WILL BE COOLEST ACROSS THE NORTH WHERE LITTLE HEATING OCCURRED TODAY. QUITE THE ADVENTUROUS FCST THIS WEEK WITH CONTINUED STREAM OF SHORT WAVES INTERACTING WITH E/W BOUNDARIES AND SLY LOW LVL INFLOW OF GULF MOISTURE. MODELS AGREE FAIRLY WELL THAT MAIN WAVES AND ASSCD TSTMS WILL DVLP ESEWD OVR AREA FM LATE MON MRNG THRU THE AFTN...AGAIN TUE AFTN AND EVE...AND ENEWD OVR AREA LATE WED INTO THU. ANY ONE OF THESE WAVES WILL HAVE GREAT POTENTIAL FOR HEAVY RAIN WITH LESSER CHCS OF SVR DUE TO LACK OF GREAT INSTABILITY. FNTL BOUNDARY WAVERING OVER AREA WILL CONTINUE TO CAUSE ISSUES WITH TEMP FCSTG WITH POTENTIALLY GREAT CONTRAST FM NORTH TO SOUTH IN CWA...BUT TREND IS FOR MODERATION OF AIR MASS TO THE NORTH...SO HOPEFULLY NO MORE 30 DEGREE TEMP VARIATIONS FM N TO S IN CWA. MAIN ISSUE WILL BE RAIN COOLED AIR. KEPT OUT CHCS PRECIP FOR FRI NGT INTO NEXT WEEKEND FOR NOW AS DYNAMICS WEAKEN QUITE A BIT. && .AVIATION... IFR CONDITIONS WILL CONTINUE THRU MID MORNING MONDAY ACROSS MOST OF SOUTHEAST SD AND MUCH OF SW MINNESOTA. VFR CIGS ACROSS NW IOWA THIS EVENING...BUT A RISK OF SEVERE THUNDERSTORMS THRU MID EVENING...THEN EXPECT KSUX TO GO DOWN IN IFR FOG AFTER 20/05Z...THRU MID MORNING MONDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...FLASH FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR IAZ003-014. MN...FLASH FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR MNZ081-090. NE...NONE. SD...NONE. && $$ RYRHOLM/HARMON sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 329 PM EDT SUN AUG 19 2007 .SYNOPSIS... HOT AND HUMID WEATHER WILL PREVAIL NEXT FEW DAYS AS FRONTAL BOUNDARY TO OUR NORTH WILL PUSH SLOWLY INTO THE AREA AND STALL DURING THE DAY MONDAY BUT BRING ONLY A SLIGHT INCREASE IN RAINFALL CHANCES. && .NEAR TERM /THROUGH MONDAY/... SOUTHWEST FLOW INTO THE REGION HAS INCREASED DEWPOINTS DRAMATICALLY OVER YESTERDAY AT THIS TIME. A SFC BOUNDARY/DEVELOPING WARM FRONT REMAINS JUST NORTH OF THE CWA. RADAR SHOWS ISOLD SHOWERS/STORMS DEVELOPING ACROSS THE GREENBRIER VALLEY AREA IN THE AREA OF BEST LOW LEVEL CONVERGENCE. THESE STORMS SHOULD MOVE EASTWARD INTO THE VA MTNS/SHEN VALLEY AND POSSIBLY PIEDMONT THIS EVENING. UNTIL SUNSET...OTHER ISOLD STORMS MAY STILL DEVELOP IN THE MTNS AS WELL. I HAVE KEPT THE SLIGHT CHC TSTMS THRU 800 PM ALL MTNS AND FOOTHILLS... AND THEN HAVE JUST A SLIGHT CHC IN THE WEST CEN VA FOOTHILLS PIEDMONT. LATE TONIGHT...WEAKENING CONVECTION THAT DEVELOPS IN THE OHIO VALLEY MAY BE MOVING INTO WESTERN SLOPES AREAS OF SE WV...SO I KEPT THE LOW CHC POPS OUT THAT WAY. STAYED AT OR ABOVE MOS FOR LOWS TONIGHT- SHOULD BE A WARM AND MUGGY NIGHT WITH THE INCREASED DEWPOINTS. KEY TO MONDAY FORECAST IS POSITION OF THE BOUNDARY/WARM FRONT. IS ANY ORGANIZED CONVECTION FROM THE OHIO VALLEY MOVES ALONG IT OVERNIGHT...IT MAY GET PUSHED SOUTHWARD INTO THE CWA. BOTH THE NAM AND GFS BRING IT NEAR NORTHERN SECTIONS. FOR NOW...I FELT THE BEST COURSE WAS TO RAISE THE POPS AROUND 10 PCT TO THE NORTH...AND KEEP THE SLIGHT CHC OR LESS ACROSS SOUTHERN SECTIONS OF THE CWA. SOUTHERN SECTIONS WILL BE HOT AND HUMID MONDAY...BUT WILL HAVE HEAT INDICES OF AROUND 100 WHICH IS BELOW ADVISORY LEVELS OF 105. LOOKS LIKE RECORD HIGH TEMPS FOR MONDAY WIL BE OUT OF REACH AS WELL. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... MAIN QUESTION IS THE POSSIBLE EFFECTS FROM THE REMAINS OF TD ERIN AND IT DOES NOT LOOK ESPECIALLY PROMISING AT THIS POINT. 12Z RUNS OF GFS/NAM HAVE NOW BACKED OFF SOMEWHAT ON THE PRECIP COVERAGE ACROSS THE CWA AND KEEP BULK THE ENERGY ASSOCIATED WITH ERIN TO THE NORTH. PWATS INCREASE TO AROUND 2 INCHES BY EARLY WED. BUT MAIN FORCING REMAINS NORTH OF THE MASON-DIXON LINE. SCATTERED SHOWERS STILL POSSIBLE WHICH COULD PRODUCE LOCALLY HEAVY RAINFALL BUT WIDESPREAD SOAKING POSSIBILITY REMAINS SLIM. 12Z CANADIAN MODEL ALSO CAME IN WITH QPF BULLSEYE CONSIDERABLY FURTHER NORTH THAN ITS 00Z RUN...MAINLY ACROSS MD AND SOUTHERN PA LATE TUESDAY INTO WEDNESDAY. TEMPERATURES WILL CONTINUE TO RUN 4 TO 6 ABOVE CLIMO DURING THE PERIOD. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 596 DM RIDGE OVER THE SOUTHEASTERN US VERY HARD TO DISLODGE DURING THE EXTENDED PERIOD. THE SURFACE BOUNDARY ACROSS THE EASTERN CWA WILL WASH OUT BY LATE THURSDAY LEAVING WEAK HIGH PRESSURE ACROSS THE MID-ATLANTIC AND VERY WARM TEMPERATURES FOR THE LATE WEEK AND INTO THE WEEKEND. POPS IN THE 20/30 RANGE OFFER LITTLE LIKELIHOOD OF DROUGHT RELIEF. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... LAPS AND MSAS SHOWING THE AREA BECOMING UNSTABLE THIS AFTERNOON WITH THE SOUTHWEST FLOW BRINGING HIGHER SFC DEWPOINTS. THERE IS LITTLE IN THE WAY OF FORCING FOR CONVECTION LATE THIS AFTERNOON OTHER THAN DIFF HEATING AND WEAK CONVERGENCE IN THE MTNS WEST OF THE BLUE RIDGE. RUC MODEL SHOWS PRECIP IN THE NEW RIVER AND ROA VALLEYS 21 TO 00Z...AND THEN MOVING EAST INTO THE PIEDMONT. 12Z NAM INITIATES A LITTLE FURTHER EAST...BUT HINTS AT THE SAME. FOR THIS REASON...I HAVE KEPT IN THE VICINITY TSTM THAT WE ALREADY HAD GOING FOR ROA...LYH AND DAN. I REMOVED IT FROM BLF AND LWB. I ALSO NARROWED THE WINDOW OF VICINITY TSTMS DOWN TO 3 HOUR PERIODS. OTHER THAN A CHANCE FOR IFR OR MVFR WITH A PASSING TSTM...I LOOK FOR MAINLY VFR CONDITIONS THRU THE NEXT 24 HOURS. LYH MAY HAVE A PERIOD OF MVFR FOG TOWARD MORNING. I KEPT IN THE LIGHT SHOWERS FOR LWB AS MODELS STILL SHOW SOME WEAKENING CONVECTION MAKING IT INTO SE WV OVERNIGHT. SOUTHWEST TO WEST WINDS WILL PICK UP AGAIN ON MONDAY TO AROUND 10 KNOTS ALL TAF SITES. MONDAY AFTERNOON THROUGH WEDNESDAY...WILL SEE AN INCREASE IN THUNDERSTORM ACTIVITY AS WAVES TRACK ALONG A STATIONARY BOUNDARY IN THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. GREATEST CHANCE FOR ACTIVITY WILL BE IN THE GREENBRIER VALLEY (LWB) AND LESS CHANCE TOWARD SOUTHSIDE VA (DAN). && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PC NEAR TERM...JJ SHORT TERM...PC LONG TERM...PC AVIATION...JJ va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 142 PM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL SLIDE OFF THE MID ATLANTIC COAST TODAY. PRECIPITATION CHANCES WILL START TO INCREASE HEADING INTO NEXT WEEK AS THE FRONT MOVES NORTH AGAIN AS A WARM FRONT INTO THE OHIO VALLEY. TEMPERATURES WILL ONCE AGAIN BE ABOVE NORMAL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WITH A SOLID OVERCAST OF STRATO-CUMULUS OVER THE PIEDMONTS OF NW NC AND WEST CENTRAL VA...I HAVE UPDATED THE GRIDS FOR MORE SKY COVER THIS MORNING. WITH HEATING...THIS OVC SHOULD SCATTER OUT AROUND NOON OR SHORTLY AFTER. BECAUSE OF THE SKY COVER...I LOWERED HIGH TEMPS A DEGREE OR TWO IN THE PIEDMONT. I RAISED THE HIGH TEMPS A DEGREE OR TWO IN THE WEST WITH PLENTY OF SUN...A WARM START AND WEAK WARM ADVECTION THIS AFTERNOON. BLF MAY HIT 90 DEGREES...WHICH IS THEIR RECORD FOR TODAY- 90 DEGREES SET IN 1988. NO OTHER RECORD HIGHS SHOULD BE THREATENED. OTHER CHANGE TO THE FCST WAS TO RAISE THE DEWPOINTS IN THE PIEDMONT WITH UPPER 60S TO 70 DEGREE DEWPOINTS SURGING NORTHEAST ACROSS NC. FINALLY...I RAISED POPS IN THE MTNS ENOUGH TO HAVE ISOLD TSTMS ALL AREAS. LOOKS LIKE PIEDMONT AREAS WILL BE THE MOST UNSTABLE WITH THOSE HIGH DEWPOINTS...BUT NO BOUNDARY OR UPPER LEVEL FORCING TO GENERATE STORMS...SO WOULD PROBABLY NEED STORMS TO DEVELOP IN THE MTNS AND THEN MOVE EASTWARD INTO THE FOOTHILLS AND PIEDMONT. BETTER CHC FOR STORMS WOULD THEN BE EARLY EVENING IN THE PIEDMONT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... MODELS HAVE BE SHOWING STATIONARY BOUNDARY DEVELOPING FROM THE GREAT LAKES THROUGH THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. 07Z SUN SATELLITE DATA IS VERIFYING THIS BOUNDARY. THE FORECAST THROUGH TUESDAY DEPENDS ON THE LOCATION OF THIS BOUNDARY AND WAVES DEVELOPING ON IT AND RIDING AROUND UPPER LEVEL RIDGE IN SOUTHEASTERN US. WAVES THAT MAKE IT INTO THE OHIO VALLEY WILL ALLOW THIS BOUNDARY TO SINK TO THE SOUTH. WITH MOISTURE IN THE AREA AND ENERGY FROM THESE WAVES WILL BRING A GOOD CHANCE OF STORMS TO NORTHERN CWA. WITH MORE INFLUENCE OF THE UPPER LEVEL RIDGE TO THE SOUTH...ISOLATED DIURNAL CONVECTION IS POSSIBLE BUT THE FOCUS WILL BE ACROSS THE GREENBRIER VALLEY AND THE VA HIGHLANDS. ONCE ONE WAVE EXITS THE OHIO VALLEY...ANOTHER ONE WILL DEVELOP UPSTREAM ALLOWING THE BOUNDARY TO DRIFT BACK TO THE NORTH. CONVECTION MAY LINGER DEEPER INTO MONDAY NIGHT AS A LEE TROF BECOMES A LITTLE STRONGER. TUESDAY LOOKS LIKE A REPEAT OF MONDAY BUT 00Z GFS BRINGS ONE OF THE WAVES/MCS INTO CENTRAL WV-VA. THIS WILL BRING A BETTER CHANCE FOR STORMS NORTH OF 460. AREA WILL REMAIN ON THE WARM SIDE OF THE FRONT AND WITH UPPER LEVEL RIDGE TO THE SOUTH...TEMPERATURES WILL RUN ABOVE NORMAL INTO TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... THIS TIME PERIOD WILL BE CHARACTERIZED BY A TRANSITION BACK TO A MORE DIURNAL POTENTIAL FOR SHOWERS AND STORMS MAINLY IN WESTERN PARTS OF THE AREA. WHILE ADDITIONAL SHOWERS/STORMS WILL BE POSSIBLE MAINLY IN THE NORTH WITH THE AFOREMENTIONED FRONT STILL IN THE PROXIMITY OF THE AREA TUESDAY NIGHT INTO WEDNESDAY...AN APPROACHING TROUGH IN THE CENTRAL PART OF THE U.S. WILL HELP LIFT THIS FRONT NORTH INTO NEW ENGLAND. AS THIS HAPPENS...THE UPPER RIDGE WILL BUILD BACK NORTH OVER OUR AREA. THIS WILL PLACE US IN A REGIME WITH LIMITED...IF ANY...DYNAMICS ALOFT...BUT WE STILL WILL HAVE PLENTY OF LOW LEVEL MOISTURE AND AFTERNOON INSTABILITY FOR ISOLATED TO SCATTERED SHOWERS AND STORMS MAINLY IN THE MOUNTAINS. THE RIDGE AGAIN WILL GET SHUNTED SOUTH HEADING INTO THE WEEKEND AS ANOTHER COLD FRONT TRIES TO PUSH INTO THE AREA. A BETTER CHANCE OF ORGANIZED PRECIPITATION WILL RETURN TO THE AREA BECAUSE OF THIS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... LAPS AND MSAS SHOWING THE AREA BECOMING UNSTABLE THIS AFTERNOON WITH THE SOUTHWEST FLOW BRINGING HIGHER SFC DEWPOINTS. THERE IS LITTLE IN THE WAY OF FORCING FOR CONVECTION LATE THIS AFTERNOON OTHER THAN DIFF HEATING AND WEAK CONVERGENCE IN THE MTNS WEST OF THE BLUE RIDGE. RUC MODEL SHOWS PRECIP IN THE NEW RIVER AND ROA VALLEYS 21 TO 00Z...AND THEN MOVING EAST INTO THE PIEDMONT. 12Z NAM INITIATES A LITTLE FURTHER EAST...BUT HINTS AT THE SAME. FOR THIS REASON...I HAVE KEPT IN THE VICINITY TSTM THAT WE ALREADY HAD GOING FOR ROA...LYH AND DAN. I REMOVED IT FROM BLF AND LWB. I ALSO NARROWED THE WINDOW OF VICINITY TSTMS DOWN TO 3 HOUR PERIODS. OTHER THAN A CHANCE FOR IFR OR MVFR WITH A PASSING TSTM...I LOOK FOR MAINLY VFR CONDITIONS THRU THE NEXT 24 HOURS. LYH MAY HAVE A PERIOD OF MVFR FOG TOWARD MORNING. I KEPT IN THE LIGHT SHOWERS FOR LWB AS MODELS STILL SHOW SOME WEAKENING CONVECTION MAKING IT INTO SE WV OVERNIGHT. SOUTHWEST TO WEST WINDS WILL PICK UP AGAIN ON MONDAY TO AROUND 10 KNOTS ALL TAF SITES. MONDAY AFTERNOON THROUGH WEDNESDAY...WILL SEE AN INCREASE IN THUNDERSTORM ACTIVITY AS WAVES TRACK ALONG A STATIONARY BOUNDARY IN THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. GREATEST CHANCE FOR ACTIVITY WILL BE IN THE GREENBRIER VALLEY (LWB) AND LESS CHANCE TOWARD SOUTHSIDE VA (DAN). && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...JJ SHORT TERM...RCS LONG TERM...DS AVIATION...JJ/RCS va