WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL 937 AM EDT FRI APR 16 2004 .CURRENTLY...SURFACE HIGH PRESSURE OVER THE SOUTHEASTERN STATES AND PENINSULA IS PROVIDING CLEAR SKIES ACROSS THE ENTIRE FORECAST AREA EARLY THIS MORNING. TEMPERATURES ARE NOT AS COOL AS YESTERDAY MORNING AT THIS TIME WITH READINGS NOW IN THE UPPER 50S NORTH...AND LOWER 60S CENTRAL AND SOUTH. .REST OF TODAY...DELIGHTFUL WEATHER WILL PREVAIL ACROSS THE REGION. ABUNDANT MID APRIL SUNSHINE WILL ALLOW TEMPERATURES TO CLIMB INTO THE UPPER 70S TO ~80 IN MOST LOCATIONS AS THE AIR MASS CONTINUES TO SLOWLY MODIFY. ONGOING ZONES COVER THIS...SO NO UPDATES NEEDED. && .MARINE...LIGHT WINDS AND SLIGHT SEAS BEING OBSERVED OVER THE COASTAL WATERS EARLY THIS MORNING. THESE CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON...WITH A WEAK PRESSURE PATTERN SUPPORTING AN ONSHORE SEA BREEZE COMPONENT DEVELOPING ALONG COASTAL LOCATIONS. MAY LOWER SEAS SLIGHTLY FOR THE AFTERNOON BASED ON CURRENT TRENDS...OTHERWISE NO OTHER CHANGES EXPECTED IN THE 1030 AM UPDATE. && .FIRE WEATHER...A DRY AIR MASS AND MODERATING TEMPERATURES WILL AGAIN SUPPORT LOW RH DURATIONS OVER MOST OF THE FORECAST AREA DURING THIS AFTERNOON...WHICH IS SUPPORTED BY LATEST RUC DATA. THE EXCEPTION TO THIS WILL BE RIGHT ALONG THE IMMEDIATE COAST WHERE THE ONSET OF THE AFTERNOON SEA BREEZE SHOULD KEEP VALUES ABOVE CRITICAL VALUES. RED FLAG WARNING WILL REMAIN IN EFFECT FOR ALL COUNTIES EXCEPT PINELLAS. && .TBW WATCHES/WARNINGS/ADVISORIES... ...RED FLAG WARNING ALL COUNTIES EXCEPT PINELLAS AND IMMEDIATE COAST TODAY FOR LOW RH DURATIONS. ...FIRE WEATHER WATCH ALL AREAS SATURDAY FOR MARGINALLY LOW RH DURATIONS... $$ SHORT TERM...MCMICHAEL LONG TERM....SHARP fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 637 PM CDT FRI APR 16 2004 .DISCUSSION... WARM FRONT WILL LIE FROM CENTRAL NEBRASKA TO CENTRAL WISCONSIN DURING THE EARLY EVENING. AN INCREASE IN HIGH CLOUDS SEEN ON THE SATELLITE LOOPS OVER CENTRAL IOWA ALONG THE ARM FRONT SHOWS THE VORTICITY ADVECTION ALOFT. DEWPOINTS ARE INCREASING AT THE SURFACE AND ARE IN THE 50S AS 19 UTC. THE RUC SOUNDINGS IN THE SOUTHWEST PART OF THE FORECAST AREA OF NORTHEAST ILLINOIS SHOWS A DRY LOW LEVEL ATMOSPHERE. SO THE LIFT MAY BE AROUND BUT NOT ENOUGH DEEP MOISTURE. HOWEVER USING A SURFACE PARCEL AND LIFTING IT ON THE SOUNDING GIVES 1554 J/KG WITH THE CURRENT DEWPOINT. WITH THIS INSTABILITY AROUND AND SLOWLY INCREASING MOISTURE BY SATURDAY MORNING. THIS IS SEEN ON THE MESOETA SOUNDING FORECAST AND THE WORKSTATION ETA FORECASTS. WILL ADD A CHANCE OF THUNDERSTORMS AFTER 06 UTC TONIGHT. THIS WILL GIVE THE ATMOSPHERE A CHANCE TO BECOME MORE MOIST. THE FRONT WILL BE AROUND SOUTHERN WISCONSIN AND NORTHERN ILLINOIS THROUGH SATURDAY AND SUNDAY. THERE ARE HIGH FORECAST CONVECTIVE AVAILABLE SO A CHANCE OF THUNDERSTORMS WILL BE IN THE FORECASTS. IT WILL BE DIFFICULT TO DETERMINE WHEN THE THUNDERSTORMS OCCUR WITH THE FRONT AROUND...VORTICITY MAXIMUM MOVING THROUGH AND OLD THUNDERSTORM BOUNDARIES AROUND THE AREA. WILL FORECASTS LOW POPS FOR NOW. USED THE AVN MODEL AS GUIDANCE ESPECIALLY LOW LEVEL EQUIVALENT POTENTIAL TEMPERATURE FIELDS AND 700 500 MB VORTICITY FIELDS. ANOTHER LOW IS FORECAST TO MOVE INTO CENTRAL ILLINOIS ON WEDNESDAY. WILL ADD A CHANCE OF THUNDERSTORMS IN THE SOUTHERN QUARTER OF THE FORECAST AREA. ON THURSDAY AND FRIDAY THE GFS FORECAST ANOTHER LOW IN IOWA AND THE CANADIAN GLOBAL MODEL SHOWS POSITIVE VORTICITY ADVECTION INTO THE REGION AT 500 MB. WILL ADD A CHANCE OF THUNDERSTORMS FOR FRIDAY. WHW && .AVIATION... FOR 00Z TAFS...CONVECTION STARTING TO FIRE ACROSS WESTERN IA AND ACTIVITY IS EXPECTED TO MOVE ENE ALONG A FRONTAL BOUNDARY TONIGHT. MODELS SHOW MOST OF THE PRECIP ALONG AND NORTH OF THE WI/IL BORDER. HOWEVER...EXPECT A FEW SHOWERS AND THUNDERSTORMS ACROSS NORTHERN IL AND WILL LEAVE PROB30 AROUND SUNRISE GOING THIS CYCLE. SW WINDS 10-15KTS TURN SOUTHERLY OVERNIGHT THEN BACK WESTERLY AFTER SUNRISE SAT. COULD BE A FEW SHOWERS AND THUNDERSTORMS SAT AFTERNOON BUT ANY PRECIP SHOULD BE SOUTH OF THE FRONTAL BOUNDARY WHICH MOVES THROUGH TERMINALS 16Z-18Z SATURDAY...SHIFTING WINDS TO THE NORTHEAST. FOR NOW HAVE LEFT SPEEDS AT 12KTS BUT SOME GUSTS TO 20KTS POSSIBLE ESPECIALLY AS FRONT PUSHES THROUGH LATE SAT MORNING. && .LOT...WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LK MI...NONE. $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 340 PM CDT FRI APR 16 2004 .DISCUSSION WARM FRONT WILL LIE FROM CENTRAL NEBRASKA TO CENTRAL WISCONSIN DURING THE EARLY EVENING. AN INCREASE IN HIGH CLOUDS SEEN ON THE SATELLITE LOOPS OVER CENTRAL IOWA ALONG THE ARM FRONT SHOWS THE VORTICITY ADVECTION ALOFT. DEWPOINTS ARE INCREASING AT THE SURFACE AND ARE IN THE 50S AS 19 UTC. THE RUC SOUNDINGS IN THE SOUTHWEST PART OF THE FORECAST AREA OF NORTHEAST ILLINOIS SHOWS A DRY LOW LEVEL ATMOSPHERE. SO THE LIFT MAY BE AROUND BUT NOT ENOUGH DEEP MOISTURE. HOWEVER USING A SURFACE PARCEL AND LIFTING IT ON THE SOUNDING GIVES 1554 J/KG WITH THE CURRENT DEWPOINT. WITH THIS INSTABILITY AROUND AND SLOWLY INCREASING MOISTURE BY SATURDAY MORNING. THIS IS SEEN ON THE MESOETA SOUNDING FORECAST AND THE WORKSTATION ETA FORECASTS. WILL ADD A CHANCE OF THUNDERSTORMS AFTER 06 UTC TONIGHT. THIS WILL GIVE THE ATMOSPHERE A CHANCE TO BECOME MORE MOIST. THE FRONT WILL BE AROUND SOUTHERN WISCONSIN AND NORTHERN ILLINOIS THROUGH SATURDAY AND SUNDAY. THERE ARE HIGH FORECAST CONVECTIVE AVAILABLE SO A CHANCE OF THUNDERSTORMS WILL BE IN THE FORECASTS. IT WILL BE DIFFICULT TO DETERMINE WHEN THE THUNDERSTORMS OCCUR WITH THE FRONT AROUND...VORTICITY MAXIMUM MOVING THROUGH AND OLD THUNDERSTORM BOUNDARIES AROUND THE AREA. WILL FORECASTS LOW POPS FOR NOW. USED THE AVN MODEL AS GUIDANCE ESPECIALLY LOW LEVEL EQUIVALENT POTENTIAL TEMPERATURE FIELDS AND 700 500 MB VORTICITY FIELDS. ANOTHER LOW IS FORECAST TO MOVE INTO CENTRAL ILLINOIS ON WEDNESDAY. WILL ADD A CHANCE OF THUNDERSTORMS IN THE SOUTHERN QUARTER OF THE FORECAST AREA. ON THURSDAY AND FRIDAY THE GFS FORECAST ANOTHER LOW IN IOWA AND THE CANADIAN GLOBAL MODEL SHOWS POSITIVE VORTICITY ADVECTION INTO THE REGION AT 500 MB. WILL ADD A CHANCE OF THUNDERSTORMS FOR FRIDAY. WHW && .AVIATION DISCUSSION FOR 18Z TAFS... SOUTHWEST LOW LEVEL WINDS CONTINUE TO DIMINISH PER WIND PROFILERS AND WINDS SHOULD REMAIN IN THE 5 TO 15 KNOT RANGE THROUGH THE REMAINDER OF THE AFTERNOON. WEAK SHEAR VORT NOW EXITING CWA ASSOCIATED WITH MID LEVEL WAVE PASSING THROUGH OVERNIGHT...AND MODEL TIME SECTIONS INDICATE WEAK SUBSIDENCE THROUGHOUT THE COLUMN THIS AFTERNOON. THIS SHOULD LIMIT EXTENT OF ANY AFTERNOON CU THAT DO FORM. CURRENT SATELLITE IMAGERY SHOWING NO EVIDENCE OF ANY CU FORMATION AND ANY LOW CLOUDS THAT DO FORM WOULD BE VFR SO DOES NOT APPEAR WORTH A MENTION. QUESTION FOR TONIGHT WILL BE CHANCES AND TIMING OF CONVECTION. SHOULD SEE DIURNAL LLJ DEVELOP ONCE AGAIN...BUT MOST FAVORED AREA FOR MCS DEVELOPMENT APPEARS TO BE NORTH OF CWA TONIGHT IN CLOSER VICINITY TO LOW LEVEL BAROCLINIC ZONE. WILL KEEP -TSRA MENTION IN FOR 09Z-13Z TIME PERIOD WITH SOUTHERN EXTENT OF ANY OVERNIGHT CONVECTION POSSIBLY CLIPPING NRN IL/NW IN. OTHER QUESTION DEALS WITH SOUTHWARD EXTENT OF LOW LEVEL BAROCLINIC ZONE TOMORROW. SYNOPTIC FORCING WITH THIS BOUNDARY APPEARS WEAK ENOUGH TO DELAY LAKE FRONT PASSAGE UNTIL AFTER THE FORECAST PERIOD...SO WILL KEEP SOUTHWEST WINDS THROUGHOUT THE PERIOD. NDM && .LOT...WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LK MI...NONE. $$ il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GOODLAND KS 819 PM MDT FRI APR 16 2004 .DISCUSSION...WILL BE UPDATING ALL ZONES FOR ALL PARAMETERS. SHALLOW COOL FRONT HAS SAGGED ACROSS THE FORECAST AREA...AND IS OVER THE EXTREME SOUTHERN PORTION OF OUR COUNTIES. NGM/ETA/GFS NOT DOING WELL AT ALL WITH WINDS AND BOUNDARY POSITION. RUC IS DOING VERY WELL... AND WILL UPDATE THE WIND FORECAST WITH IT. MODELS NOT HANDLING DEWPOINTS WELL. THE ETA IS THE CLOSEST. HIGHER DEWPOINTS STAY OVER NORTH AND NORTHEAST SECTIONS. WINDS WILL GET LIGHT AND VARIABLE VERY CLOSE TO 12Z. WILL BE LOWERING MINS...ESPECIALLY IN THE WEST WHERE THE LOWER DEWPOINTS RESIDE. LOOKS LIKE WILL KEEP A DECENT AMOUNT OF HIGH CLOUD COVER... AND WILL CHANGE FORECAST TO PARTLY CLOUDY. RED FLAG WATCH STILL LOOKS ON TRACK. HOWEVER...DEPENDING HOW FAST BOUNDARY RETREATS... WINDS MIGHT NOT MEET CRITERIA UNTIL VERY LATE IN THE AFTERNOON. $$ .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...FIRE WEATHER WATCH EAST CENTRAL COLORADO COUNTIES FROM 1 PM MDT TIL 9 PM MDT SATURDAY. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1048 PM EDT FRI APR 16 2004 .UPDATE... WILL INCREASE POPS ACROSS THE CWA AS AN MCS WAS TAKING SHAPE OVER CENTRAL IA. THIS COMPLEX OF STORMS WILL CONTINUE TO MOVE EAST NORTHEAST OVERNIGHT...TAKING AIM ON LOWER MI DURING THE 08-12Z TIME FRAME. ONE CONCERN IS THE DRIER THAT WAS OVER SOUTHERN WI/NORTHERN IL AS OF 02Z WHICH COULD WEAKEN THE STORMS BEFORE REACHING MI. DEW POINTS IN THIS REGION WERE ONLY AROUND 40. BUT THE RUC INDICATES STRONG MOISTURE ADVECTION INTO THIS REGION AS THE MCS APPROACHES... AND INDEED DEW POINTS ARE IN THE 50 TO 55 DEGREE RANGE OVER CENTRAL IL. THE COMPLEX WILL MAINTAIN FAVORABLE JET DYNAMICS OVERNIGHT WHICH WILL SUSTAIN THE CONVECTIVE ACTIVITY. A 35KT LOW LEVEL JET WILL NOSE INTO THE CENTRAL LAKES...WHILE VERY STRONG UPPER DIVERGENCE MOVES FROM IA TO CENTRAL LOWER MI BY 12Z. WILL USE CATEGORICAL POPS ACROSS THE NORTH...AND LIKELY POPS SOUTH. WILL ALSO LOWER TEMPS A BIT GIVEN CURRENT TRENDS. && .GRR...WATCHES/WARNINGS/ADVISORIES...NONE. && JK mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 245 PM EDT FRI APR 16 2004 .DISCUSSION... DIFFICULT FORECAST FOR THE WEEKEND AS A FRONTAL BOUNDARY WILL BE MEANDERING OVER LOWER MICHIGAN. THIS PRESENTS PROBLEMS...AS THERE IS THE POTENTIAL OF SEVERE WEATHER ALONG AND IN THE VICINITY OF THE FRONT. ONE OF THE BIGGEST ISSUES IS THE AMOUNT OF AVAILABLE MOISTURE AND CORRESPONDING INSTABILITY. EXACT POSITION OF THE FRONTAL BOUNDARY WILL HAVE BIG IMPACT ON TEMPERATURES AS WELL...WITH A BUST POTENTIAL OF 10 DEGREES POSSIBLE. TIGHT BAROCLINIC ZONE WILL SET UP OVER LOWER MICHIGAN. ALSO...WILL THE COOL WATER TEMPERATURES OF LAKE HURON/ST CLAIR/ERIE HAVE A SIGNIFICANT IMPACT ON THE ULTIMATE POSITION OF THE FRONTAL BOUNDARY? ONE OF THE KEY SYNOPTIC PLAYERS FOR THE WEEKEND IS THE DIGGING TROUGH CURRENTLY OFF THE CALIFORNIA COAST. THIS HIGHLY AMPLIFIED LONGWAVE TROUGH WILL CAUSE THE UPPER LEVEL RIDGE OVER THE PLAINS ON SATURDAY TO BUILD. CONFLUENT FLOW OVER THE NORTHERN LAKES WILL ALLOW A SURFACE HIGH TO BUILD INTO THE REGION...PUSHING THE FRONTAL BOUNDARY SOUTH THROUGH LOWER MICHIGAN. HOW FAR SOUTH IS THE BIG QUESTION? WILL IT REACH THE OHIO BORDER BY SATURDAY EVENING? IT LOOKS LIKE ENOUGH PACIFIC ENERGY/SHORTWAVES WILL RIDE OVER THE TOP OF THE RIDGE TO INITIATE ACTIVITY ALONG THE FRONTAL BOUNDARY SATURDAY/SATURDAY NIGHT. THE THREAT FOR SEVERE WEATHER IS DEPENDENT ON THE LOW LEVEL MOISTURE AND EXACT FRONTAL POSITION. 12Z MESOETA CONTINUES TO SHOW SOME CONCERNING CONVECTIVE PARAMETERS. SPECIFICALLY...THE MOST CONCERNING BEING THE LOW LEVEL HELICITY/WIND SHEAR ALONG AND JUST NORTH OF THE FRONTAL BOUNDARY...WITH SUFFICIENT INSTABILITY. HOWEVER...A MAJOR PROBLEM OF THE MESOETA APPEARS TO BE THE AMOUNT OF LOW LEVEL MOISTURE IT IS DEPICTING. THE FORECASTED SURFACE DEWPOINTS ON SATURDAY (LOW TO MID 60S ACROSS LOWER MICHIGAN) APPEAR TO BE EXCESSIVELY HIGH. QUICK GLANCE AT TODAY'S SURFACE DEW POINTS INDICATES VALUES BELOW WHAT THE MESOETA IS FORECASTING. AS OF EARLY AFTERNOON...SURFACE DEW POINTS IN THE LOWER 60S WERE CONFINED TO THE SOUTHERN PLAINS. NOT ANTICIPATING THESE TYPE OF DEW POINTS ADVECTING INTO THE AREA BY SATURDAY. SO...WOULD LIKE TO TAPER DOWN THE BULLISH FORECAST BY THE MESOETA. NONE-THE-LESS...STILL ENOUGH INGREDIENTS IN PLACE TO CONTINUE THE MENTION OF SLIGHT CHANCE OF SEVERE THUNDERSTORMS THROUGH THE WEEKEND. AS FAR AS THE TIMING OF SHOWERS/THUNDERSTORMS GOES...12Z ETAXX/MESOETA/10KM TAQ RUC SOLUTIONS ALL APPEAR TO BE IN THE SAME BALLPARK. IN TERMS OF THE FRONTAL BOUNDARY (PREFERENCE WITH THE 12Z ETAXX/10 KM TAQ RUC)..EXPECTING THE FRONT TO REACH THE MICHIGAN/OHIO BORDER BY SATURDAY EVENING...WITH A GOOD CHANCE THE FRONT WILL SAG SOUTH OF THE LOWER MICHIGAN BORDER DURING THE EVENING HOURS...ESPECIALLY WITH ANY HELP FROM THUNDERSTORM OUTFLOW BOUNDARIES AND THE COOL LAKE ERIE WATER TEMPERATURES. ANY SOUTHWARD MOVEMENT OF THE FRONT WILL COME TO AN END TOWARD MIDNIGHT...WITH THE FRONT QUICKLY RETURNING NORTH AS A WARM FRONT (OR BECOMING REDEFINED FARTHER NORTH) TOWARD SUNDAY MORNING. THIS IS IN RESPONSE TO THE TROUGH AXIS SHIFTING EAST INTO THE ROCKIES...AND A LEAD WAVE MOVING THROUGH THE MIDWEST. THE QUESTION FOR SUNDAY IS WHETHER OR NOT THE FRONT WILL TRULY CLEAR THE TRI-CITIES AND THUMB REGION BY DAY'S END. BANKING ON THE SOUTHERN THIRD OF THE CWA PUNCHING INTO THE WARM SECTOR...WITH TEMPS AROUND 80 DEGREES A PRETTY GOOD BET (FYI...RECORD MAX FOR DTW IS 84 DEGREES SET IN 2002). FARTHER NORTH...ALL BETS ARE OFF...AS THE FAR NORTHERN PART OF THE CWA COULD STRUGGLE TO CLIMB INTO THE 60S. WITH THE SOUTHERN HALF OF THE CWA EXPECTED TO GET INTO THE WARM SECTOR...DON'T REALLY SEE A TRIGGER FOR THUNDERSTORMS. HOWEVER...WITH THE LACK OF CIN...WILL LEAVE A CHANCE IN THE FORECAST. BUT OVERALL...SUNDAY LOOKS LIKE A FINE DAY ACROSS THE DETROIT METRO AREA. COLD FRONT STILL ON TRACK TO PUSH THROUGH ON MONDAY (ANOTHER WARM DAY)...WITH THE LOW SEVERE THREAT CONTINUING...AS VERY STRONG WIND FIELD WILL BE OVER THE CENTRAL GREAT LAKES REGION (LOW LEVEL JET OF 55+ KNOTS). TIMING OF THE COLD FRONT AND AMOUNT OF SUNSHINE WILL GO A LONG WAY IN ANY CONVECTION WE SEE. INSTABILITY LOOKS LIMITED...AS MOST OF THE DYNAMICS TRACK NORTH OF LOWER MICHIGAN. REGARDLESS...EXPECT A WINDY DAY WITH GOOD COLD ADVECTION BEHIND THE FRONT. DRY AND COOLER FOR TUESDAY AS HIGH PRESSURE BUILDS IN. .EXTENDED... WILL BE CARRYING CHANCE POPS WEDNESDAY THROUGH FRIDAY. FAST ZONAL FLOW EXPECTED TO DEVELOP OVER THE CONUS...MAKING IT VERY DIFFICULT TO TIME SHORTWAVES. MEDIUM RANGE MODELS SEEM TO BE IN PRETTY GOOD AGREEMENT WITH LIFTING A WARM FRONT INTO LOWER MICHIGAN ON WEDNESDAY. BEYOND THAT...SIGNIFICANT DIFFERENCES EMERGE. LEANING TOWARD THE 00Z CANADIAN AND 00Z ETAXX FOR THURSDAY AND FRIDAY. NOT BUYING INTO THE 00Z GFS SOLUTION WHICH INDICATES A STRONG CUTOFF DEVELOPING OVER THE PLAINS BY THURSDAY. THIS SOLUTION SEEMS TO BE AN OUTLIER COMPARED TO THE OTHER MEDIUM RANGE MODELS/ENSEMBLE MEMBERS. WILL NOT DEVIATE TOO FAR FROM NORMAL FOR THURSDAY AND FRIDAY'S TEMPERATURES. NORMAL FOR MID TO LATE APRIL IS NEAR 60 DEGREES FOR HIGHS AND AROUND 40 DEGREES FOR THE LOW. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SF EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1135 AM EDT FRI APR 16 2004 .UPDATE... I WILL PUT OUT A QUICK UPDATE TO FRESHEN THE WORDING OF THE ZONE FORECAST. OVERALL THE GOING FORECAST FOR THIS AFTERNOON LOOKS FINE...PARTLY CLOUDY WITH HIGHS BETWEEN 75 AND 80 INLAND AND NEAR 70 NEAR LAKE MICHIGAN. WITH THE WARM FRONT MOVING EAST OF THE CWA...SO TO GOES THE 1000/850MB THTE CONVERGENCE...DECENT ISENTROPIC LIFT...700 TO 300MB QVECT CONVERGENCE AND ASSOCIATED SFC WIND CONVERGENCE. THE SHOWERS ARE (15Z) MOVING EAST OUT OF THE CWA AS I WRITE THIS. SKIES ARE MOSTLY CLEAR OVER LAKE MICHIGAN AND WISCONSIN. AS FOR CONVECTION THIS AFTERNOON...ONCE AGAIN THE RUC SEEMS TO BE DOING BETTER WITH THE LOW LEVEL MOISTURE PROFILE THEN THE ETA. EITHER WAY THROUGH...BOTH SOUNDINGS SHOW A SIGNIFICANT AMOUNT OF NEGATIVE AREA BELOW 15000 FT THIS AFTERNOON. AT 19Z THE RUC SHOWS GRR WITH 79F TEMP AND A 46F DEW POINT. THE CIN IS 62 G/KG. SO CU SHOULD HAVE A HARD TIME FORMING SO SAY NOTHING OF DEEP CONVECTION. SOUNDINGS AND THE 1000/925 THICKNESS TOOL FROM THE ETA SUGGEST THE RUC IS CORRECT WITH HIGHS IN THE 75 TO 80 RANGE TODAY. THUS I WILL GO WITH PARTLY CLOUDY BECOMING MOSTLY SUNNY AFTERNOON WITH HIGHS BETWEEN 75 AND 80...COOLER NEAR LAKE MICHIGAN. && .GRR...WATCHES/WARNINGS/ADVISORIES...NONE. && WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1125 AM EDT FRI APR 16 2004 .DISCUSSION... CONCERN FOR THIS AFTN/EVENING IS CONVECTION INITIATION AND JUST HOW HIGH TEMPS WILL GO. SATELLITE AND RADAR SHOWS BACK EDGE OF RAIN SHOWERS IS PRESSING OUT OF E UPR MI WITH RAIN JUST ENDING AT ANJ. SKIES HAVE CLEARED NICELY ACROSS REST OF UPR MI DESPITE SFC TROUGH LINGERING OVR THE AREA AS PRIMARY LOW PRES LIFTS TOWARD JAMES BAY. EXPECT SFC TROUGH TO MOVE VERY LITTLE VIA SYNOPTIC PROCESSES AS H5 STEERING FLOW NOW IS PARALLEL TO THE TROUGH. ONLY WAY FRONT WILL EDGE SWD IS AS MESOHIGH BUILDS OVR LK SUPERIOR THIS AFTN AND PUSHES LK BREEZE INLAND. STILL...H85-H8 TEMPS OF +8C TO +10C ARE ALLOWING MANY AREAS TO WARM QUICKLY THIS MORNING INTO THE LWR 60S. MIXING TO HEIGHTS NEAR 800MB WILL YIELD TEMPS WELL INTO THE 70S ALONG WI BORDER. DEVELOPING LK BREEZE WILL QUICKLY COOL LK SUPERIOR SHORELINE AREAS IN THE 60S/LWR 70S TO AROUND 50F THIS AFTN (ALREADY HAPPENED AT COPPER HARBOR WHERE TEMP FELL FM 67F AT 10 AM TO 54F AT 11 AM). MOISTURE FM UPR MI BACK INTO S HALF OF MN IS LIMITED WITH PWATS LESS THAN A HALF INCH ATTM. DID CONSIDER REMOVING AFTN POPS ALONG WI BORDER BUT ALTHOUGH MOISTURE IS LIMITED IT IS NOT DRY ENOUGH TO PULL POPS ALTOGETHER WITH H8-H6 LAPSE RATES RISING UP TO NEAR 9.0C/KM BY 21Z AND H85 BAROCLINIC ZONE OVERHEAD/SWRLY H85 JET AROUND 30KT NOSING INTO SW UPR MI AND HINT OF WEAK SHORTWAVE APPROACHING FM W MN. BLYR CONVERGENCE ALONG WEAK BOUNDARY MAY SPIKE UP LATE AFTN TOO AND COULD ACT AS TRIGGER FOR CONVECTION THANKS TO SOME SFC BASED INSTABILITY (MODIFYING 12Z MPX SOUNDING WITH SFC TEMP/TD OF 74F/40F GIVES CAPES NEAR 300J/KG WITH NEG AREA AROUND 50J/KG). MPX SOUNDING DID SHOW WARM CAPPING LAYER AROUND 800MB BUT RUC INDICATES TEMPS IN THAT LAYER DIPPING A BIT AS WEAK SHORTWAVE APPROACHES FM W WHICH COULD HELP TO ERASE CAP PARTIALLY. BETTER LOW LEVEL JET ORGANIZES THIS EVENING INTO NE WI AND ETA ADVERTISING CONVECTIVE COMPLEX WILL FORM ON NOSE OF THIS FEATURE LATER THIS EVENING. BEST POPS ATTM APPEAR TO OCCUR FM DICKINSON INTO MEMOMINEE COUNTIES AND MAY PUSH THEM TO LIKELY WITH AFTN PACKAGE. NO CHANGES BEYOND THIS AFTN FOR NOW. PUBLISHED GRIDS ALREADY OUT...TEXT ZFPMQT OUT SHORTLY. JLA && .PREV DISCUSSION... TONIGHT...850MB THETA-E RIDGE BULGES BACK INTO THE AREA WITH SOME INCREASE IN SWRLY FLOW...THOUGH MORE PRONOUNCED RIDGING AND STRONGER FLOW/CONVERGENCE IS FARTHER S. ETA/GFS BLOW UP CONVECTION (FOR GFS IT IS SOMEWHAT A CONTINUATION OF ITS AFTN CONVECTION) ACROSS WI WHICH APPEARS TO BE TIED TO A HARD TO TRACK SHORTWAVE TRACKING THRU PLAINS THIS AFTN. BOTH ETA/GFS HAVE SIMILAR 850MB CONVERGENCE AREA ACROSS WI AND WILL FAVOR THE ETA PLACEMENT OF THE RESULTING CONVECTION. WILL STAY WITH CHC POPS WHICH WILL BE STRATIFIED FROM N TO S WITH EXPECTATION OF MAIN ACTION STAYING TO THE S. SFC RIDGING STRENGHTENS INTO THE AREA ON SAT AS A RESULT OF TIGHTENING CONFLUENT FLOW ACROSS ONTARIO. DRIER LOW-LEVEL NERLY FLOW LOCKS IN ACROSS UPPER MI WHICH WILL ONLY BE AIDED FURTHER BY LAKE BREEZE COMPONENT TO SYNOPTIC FLOW. SFC FRONT WILL ALSO BE PUSHED FARTHER S INTO THE LWR LAKES...AND THIS WILL PLAY A ROLE IN PCPN POTENTIAL SAT NIGHT/SUN. SAT WILL BE A COOLER DAY...ESPECIALLY NEAR LAKE SUPERIOR WHERE TEMPS WILL RISE NO BETTER THAN THE 40S. NEAR LAKE MICHIGAN...MENOMINEE COUNTY WILL BE AFFECTED BY AN INCREASING COMPONENT OFF THE BAY. COOLER ETA MOS PREFERRED THERE. SAT NIGHT/SUN...TROF ALONG W COAST SHIFTS OUT INTO THE PLAINS WITH STRONG SFC CYCLONGENESIS OVER SD/NEBRASKA. SFC BOUNDARY THAT SHIFTED TO SRN LAKES SAT WILL START TO HEAD BACK N IN RESPONSE TO STRENGTHENING WAA PATTERN ACROSS THE PLAINS. SAT NIGHT...GFS LOOKS MUCH TOO FAST SPREADING HEAVY PCPN WELL N OF WARM FRONT WHICH WILL STILL BE ACROSS SRN WI BY 12Z SUN. PREFER DRIER ETA SOLUTION WHICH IS IN LINE WITH CANADIAN/UKMET. LIKE THE IDEA OF HOLDING ONTO HIGHER SFC PRES N OF THE WARM FRONT OVER THE COLD LAKES WHICH WOULD MAINTAIN DRIER E/ENE FEED OF DRY AIR AT LOW-LEVELS. WILL GRADUALLY SPREAD CHC POPS N INTO FCST AREA AFTER MIDNIGHT SAT NIGHT...BUT WILL LEAVE KEWEENAW AND FAR E DRY UNTIL SUN. SUN VERY UNCERTAIN WITH PROGRESS OF WARM FRONT AND TRACK OF SFC LOW VERY IMPORTANT TO HEAVY RAIN POTENTIAL AND/OR SVR TSTM POTENTIAL. CANADIAN/UKMET/GFS BLOW WARM FRONT THRU UPPER MI SUN OR SUN EVENING. SEEMS A BIT AMBITIOUS GIVEN COLD GREAT LAKES WHICH SHOULD HOLD UP NWD PROGRESS OF SFC WARM FRONT. HARD TO IGNORE THE AGREEMENT OF THOSE 3 MODELS. HOWEVER... BELIEVE ETA PROBABLY HAS A BETTER HANDLE ON SFC PATTERN AS IT ONLY BRINGS FRONT N INTO UPPER MI BY MON MORNING. SFC LOW ALSO TRACKS FARTHER S ACROSS ACROSS WI TOWARD ERN UPPER MI AS OPPOSED TO ACROSS LAKE SUPERIOR. ETA SUPPORTS MORE OF A HEAVY RAIN EVENT AS OPPOSED TO SVR TSTM THREAT. OBVIOUSLY CONFIDENCE IS LOW ON THIS SCENARIO...AND HEAVY RAIN THREAT WILL NEED TO BE MONITORED IN LATER MODEL RUNS. IN ANY CASE...GOING LIKELY POPS FOR SUN/SUN NIGHT ARE ON TRACK AT THIS POINT. ROLFSON && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 825 PM EDT FRI APR 16 2004 WILL MAKE A QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR THE LIGHT SHOWERS DEVELOPING AHEAD OF THE WARM FRONT THAT STRETCHES FROM THE NIAGARA PENINSULA TO CENTRAL NEW YORK STATE. ADDED LIFT FROM THE WEAK MID LEVEL SHORT WAVE...LOCATED JUST NORTH OF LAKE ONTARIO...WILL HELP TO KEEP THE SCATTERED SHOWERS INTACT THROUGH EARLY TONIGHT. THE RUC TRACKS THE SHORT WAVE EAST OF LAKE ONTARIO BY 06Z. THEREFORE...MOST OF THE SCATTERED SHOWERS SHOULD BE OVER AROUND MIDNIGHT. THE REST OF THE PREVIOUS AFD FOLLOWS. GFS/ETA IN AGREEMENT THAT SURFACE COLD FRONT WILL DROP DOWN ACROSS THE LOWER GREAT LAKES SATURDAY AFTERNOON...EVENTUALLY CROSSING THE AREA FROM NORTH TO SOUTH BETWEEN 22Z SATURDAY AFTERNOON AND 06Z SATURDAY NIGHT. AHEAD OF COLD FRONT...AIR MASS WILL DESTABILIZE SIGNIFICANTLY BY 20Z. LIFTED INDEX VALUES WILL LIKELY BE IN THE -5 RANGE AND SURFACE BASED CAPES FROM 1500-2000 J/KG. THE COMBINATION OF GOOD LOW LEVEL MOISTURE TRANSPORT WITH SURFACE DEWPOINTS IN THE MID 50S ADVECTING INTO THE AREA DURING THE AFTERNOON AND STEEPENING MID LEVEL LAPSE RATES (800 MB-650 MB LAPSE RATES NEAR 8 C/KM) WILL ALSO CONTRIBUTE TO THE DESTABILIZATION OF THE ATMOSPHERE. SHOULD SEE SCATTERED THUNDERSTORMS DEVELOP LATE IN THE DAY SATURDAY AND INTO EARLY SATURDAY NIGHT...BUT FEEL SEVERE THREAT IS LIMITED. WOULD LIKE TO SEE SLIGHTLY HIGHER DEWPOINTS ADVECTING NORTHWARD AND VERTICAL SHEAR PROFILES NOT QUITE SUFFICIENT ENOUGH FOR DAMAGING THUNDERSTORM WINDS. IN ADDITION...STRENGTHENING SOUTHWEST FLOW OFF THE COLD GREAT LAKES WILL HELP TO STABILIZE THE ATMOSPHERE DOWNWIND OF THE LAKES. CONVECTION WILL DIMINISH ACROSS THE AREA BEHIND THE FRONT SATURDAY NIGHT AS ATMOSPHERE STABILIZES AND DRIER AIR WORKS INTO THE AREA. CONVECTION WILL REGENERATE ALONG THE FRONT AS IT RETURNS AS A WARM FRONT SUNDAY. MODELS SUGGESTING MAIN ISENTROPIC LIFT WILL BE NORTH AND WEST OF THE AREA SUNDAY...HOWEVER BOTH GFS AND ETA SUGGESTING FRONT WILL BE SLOW TO WORK NORTH ACROSS THE NORTH COUNTRY. UPSTREAM CONVECTION COULD SLIDE DOWN THE FRONT ACROSS LAKE ONTARIO INTO AREAS EAST OF LAKE ONTARIO SUNDAY AFTERNOON. GFS SHOWING THIS POTENTIAL MUCH MORE THAN THE ETA...BUT MAY BE OVERDONE DUE TO SOME CONVECTIVE FEEDBACK PROBLEMS. AVIATION...VFR CONDITIONS EXPECTED AT ALL SITES FOR THE NEXT 24 HOURS. .BUF...NONE. $$ TJP/TMA/PO ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BUFFALO NY 939 AM EDT FRI APR 16 2004 WEAK SHORT WAVE CROSSING THE WESTERN GREAT LAKES AT THIS TIME IS PRODUCING AN AREA OF MID LEVEL CLOUDINESS OVER MICHIGAN...INDIANA AND WESTERN OHIO. THICKEST CLOUD COVER SEEN OVER MICHIGAN...WITH CLOUDS DISSIPATING SOMEWHAT OVER INDIANA AND WESTERN OHIO. RUC SEEMS TO HAVE A GOOD HANDLE ON THIS SYSTEM. RUC SHOWS THIS SHORT WAVE MOVING INTO THE CENTRAL GREAT LAKES BY 21Z AND BRINGING HIGHER 700 MB-500 MB MEAN RELATIVE HUMIDITY (ABOVE 50 PERCENT) INTO FAR WESTERN SECTIONS AT THE SAME TIME. SATELLITE TREND WOULD SUGGEST THAT LEADING EDGE OF MID CLOUDS SHOULD REACH WESTERN SECTIONS BETWEEN 19Z AND 21Z. WITH THIS IN MIND...WILL HAVE SUNSHINE GIVING WAY TO INCREASING CLOUDS AFTER 2 PM OR 3 PM IN THE WEST...AREAS FROM ROCHESTER EAST WILL HAVE ENOUGH SUNSHINE THIS AFTERNOON TO KEEP FORECAST AS MOSTLY SUNNY. 12Z KBUF SOUNDING SUGGESTING AFTERNOON HIGHS IN THE UPPER 60S WITH FULL SUNSHINE. PROBABLY WILL NOT MIX SOUNDING COMPLETELY WITH LOWER SUNS ANGLE THIS TIME OF YEAR. NEUTRAL TEMPERATURE ADVECTION PATTERN SHOULD KEEP AFTERNOON TEMPERATURES IN THE LOWER HALF OF THE 60S... BUT A FEW UPPER 60S OR EVEN A 70F READING POSSIBLE OVER INTERIOR SECTIONS. COULD EVEN SEE THIS HAPPEN IN FAVORED DOWNSLOPE AREAS (SOUTHEAST LOW LEVEL FLOW) ALONG THE LAKE ERIE SHORE (DUNKIRK) AND SOUTH OF LAKE ONTARIO. HOWEVER...COULD ALSO SEE AN ONSHORE FLOW DEVELOP THIS AFTERNOON COOLING THESE AREAS SLIGHTLY. ...PREVIOUS DISCUSSION... A STRONGER SHORT WAVE APPROACHES SATURDAY, AND WITH THE SURFACE TROUGH TO THE WEST, THE SOUTHWEST FLOW WILL BRING INCREASING TEMPERATURES AND DEW POINTS. THE GFS SHOWS THE PRECIPITATION MOVING THROUGH IN THE EARLY AFTERNOON, WHILE THE ETA HOLDS IT BACK UNTIL THE PASSAGE OF THE FRONT IN THE EVENING. THE EXAGGERATED WAVE IN THE ETA LOOKS LIKE AN ABERRATION, BUT WITH THE UNCERTAINTY BETWEEN THE MODELS, WE WILL NOT TRY TO TIME THE RAIN CLOSELY. THUS WE WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON, AND KEEP THEM LINGERING INTO THE EVENING. THE FRONT PUSHES BACK NORTH ON SUNDAY, BUT WESTERN NEW YORK IS IN THE COL BETWEEN THE LOW TO THE WEST AND OFF THE ATLANTIC COAST, GIVING SUN BUT LITTLE ENERGY FOR PRECIPITATION. TEMPERATURES ARE A PROBLEM BECAUSE THERE WILL BE BIG DIFFERENCES DEPENDING ON HOW FAR NORTH THE FRONT GETS DURING DIURNAL HEATING. IT SHOULD REMAIN IN THE 60S NORTH OF SYRACUSE, WHILE LOW 70S ARE LIKELY FURTHER WEST. ONLY MINOR CHANGES HAVE BEEN MADE TO THE EXTENDED PERIOD. AVIATION...VFR CONDITIONS EXPECTED AT ALL SITES FOR THE NEXT 24 HOURS. .BUF...NONE. $$ TMA/APB ny AREA FORECAST DISCUSSION...UPDATED 939 AM EDT FRI APR 16 2004 WEAK SHORT WAVE CROSSING THE WESTERN GREAT LAKES AT THIS TIME IS PRODUCING AN AREA OF MID LEVEL CLOUDINESS OVER MICHIGAN...INDIANA AND WESTERN OHIO. THICKEST CLOUD COVER SEEN OVER MICHIGAN...WITH CLOUDS DISSIPATING SOMEWHAT OVER INDIANA AND WESTERN OHIO. RUC SEEMS TO HAVE A GOOD HANDLE ON THIS SYSTEM. RUC SHOWS THIS SHORT WAVE MOVING INTO THE CENTRAL GREAT LAKES BY 21Z AND BRINGING HIGHER 700 MB-500 MB MEAN RELATIVE HUMIDITY (ABOVE 50 PERCENT) INTO FAR WESTERN SECTIONS AT THE SAME TIME. SATELLITE TREND WOULD SUGGEST THAT LEADING EDGE OF MID CLOUDS SHOULD REACH WESTERN SECTIONS BETWEEN 19Z AND 21Z. WITH THIS IN MIND...WILL HAVE SUNSHINE GIVING WAY TO INCREASING CLOUDS AFTER 2 PM OR 3 PM IN THE WEST...AREAS FROM ROCHESTER EAST WILL HAVE ENOUGH SUNSHINE THIS AFTERNOON TO KEEP FORECAST AS MOSTLY SUNNY. 12Z KBUF SOUNDING SUGGESTING AFTERNOON HIGHS IN THE UPPER 60S WITH FULL SUNSHINE. PROBABLY WILL NOT MIX SOUNDING COMPLETELY WITH LOWER SUNS ANGLE THIS TIME OF YEAR. NEUTRAL TEMPERATURE ADVECTION PATTERN SHOULD KEEP AFTERNOON TEMPERATURES IN THE LOWER HALF OF THE 60S... BUT A FEW UPPER 60S OR EVEN A 70F READING POSSIBLE OVER INTERIOR SECTIONS. COULD EVEN SEE THIS HAPPEN IN FAVORED DOWNSLOPE AREAS (SOUTHEAST LOW LEVEL FLOW) ALONG THE LAKE ERIE SHORE (DUNKIRK) AND SOUTH OF LAKE ONTARIO. HOWEVER...COULD ALSO SEE AN ONSHORE FLOW DEVELOP THIS AFTERNOON COOLING THESE AREAS SLIGHTLY. ...PREVIOUS DISCUSSION... A STRONGER SHORT WAVE APPROACHES SATURDAY, AND WITH THE SURFACE TROUGH TO THE WEST, THE SOUTHWEST FLOW WILL BRING INCREASING TEMPERATURES AND DEW POINTS. THE GFS SHOWS THE PRECIPITATION MOVING THROUGH IN THE EARLY AFTERNOON, WHILE THE ETA HOLDS IT BACK UNTIL THE PASSAGE OF THE FRONT IN THE EVENING. THE EXAGGERATED WAVE IN THE ETA LOOKS LIKE AN ABERRATION, BUT WITH THE UNCERTAINTY BETWEEN THE MODELS, WE WILL NOT TRY TO TIME THE RAIN CLOSELY. THUS WE WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON, AND KEEP THEM LINGERING INTO THE EVENING. THE FRONT PUSHES BACK NORTH ON SUNDAY, BUT WESTERN NEW YORK IS IN THE COL BETWEEN THE LOW TO THE WEST AND OFF THE ATLANTIC COAST, GIVING SUN BUT LITTLE ENERGY FOR PRECIPITATION. TEMPERATURES ARE A PROBLEM BECAUSE THERE WILL BE BIG DIFFERENCES DEPENDING ON HOW FAR NORTH THE FRONT GETS DURING DIURNAL HEATING. IT SHOULD REMAIN IN THE 60S NORTH OF SYRACUSE, WHILE LOW 70S ARE LIKELY FURTHER WEST. ONLY MINOR CHANGES HAVE BEEN MADE TO THE EXTENDED PERIOD. AVIATION...VFR CONDITIONS EXPECTED AT ALL SITES FOR THE NEXT 24 HOURS. .BUF...NONE. $$ TMA/APB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 830 PM CDT FRI APR 16 2004 .DISCUSSION...MSAS SURFACE ANALYSIS INDICATES SURFACE RIDGE ACROSS SOUTHEAST UNITED STATES THIS EVENING WITH A SURFACE DRYLINE ACROSS WEST TEXAS. WATER VAPOR SATELLITE IMAGES AND 500MB RUC HEIGHT ANALYSIS INDICATES SUBTROPICAL RIDGE OVER NORTHERN MEXICO EXTENDING INTO THE SOUTHERN PLAINS. NORTHWEST FLOW ALOFT CONTINUES TO PROVIDE SUBSIDENCE ACROSS THE LOWER RIO GRANDE VALLEY WITH MOISTURE CONFINED TO NEAR 850MB AS PER LATEST KBRO SOUNDING. SKIES APPEAR TO BE CLEARING FROM EAST TO WEST TONIGHT WITH A FEW HIGH CLOUDS OVER NORTHERN MEXICO MOVING TOWARDS DEEP SOUTH TX. WILL UPDATE ZONES/GRIDS TO REFLECT CLOUD COVER. && .MARINE...SCA FOR GMZ130...AS COOL SURF FM RECENT FROPA WELCOMES MIXING. NRN GULF OF MEX NEARLY FLAT...AS HIGH PRESSURE BLANKETED THE REGION FOR SEVERAL DAYS AND WIND FIELD FEEL TO NADA. THE LWR TX COASTAL WATERS NOW AT 5 FOOTERS IN 15 TO 19 KTS OF SE WND. GWW KEEPS WAVE HEIGHTS BELOW 6 FT THRU 12Z WED...WITH SE WNDS APPROACHING 20 KTS. GENERALLY...NOT A VERY GREAT DETERMENT TO ANY MARINE ACTIVITY. ALTHOUGH SCA FLAGS ARE POSSIBLE FOR SAT...NOT A MAJOR PLAYER...AS WINDS/SEAS WILL GRADUALLY SUBSIDE TUE AND WED. && .AVIATION...WND SPEEDS ON SAT LOOK EVEN STRONGER THAN TDYS ...WITH A WIND ADVISORY POSSIBLE. CIGS MVFR OVRNGT...TO VFR BY LATE MRNG AS CLGS WILL MIX OUT/UPWARD WITH DAYTIME HEATING. STRONGER AND GUSTIER SURFACE WINDS THE NEXT COUPLE OF DAYS WILL HELP PRODUCE SOME LIGHT LOW LEVEL TURBULENCE DURING LANDING AND TAKEOFFS AT LOCAL AIRPORTS. STRONG SE WNDS CONTINUE FOR SUN PM. && .PREVIOUS DISCUSSION...A QUIET AND PRETTY BENIGN WX PATTERN WILL PERSIST OVER DEEP SOUTH TX THROUGHOUT THE WEEKEND. 5H TROFFING WILL DEEP SOUTH ALONG THE WEST COAST WHILE A 5H CLOSED LOW SHEARS OFF OF THE 5H TROFFING DIGGING OFFSHORE OF THE NE U.S. THIS WILL IN TURN TEND TO BUILD A 5H RIDGE OVER THE CENTRAL PORTION OF THE COUNTRY WITH THE RIDGE EVENTUALLY ELONGATED FROM THE SW TO THE NE OVER THE GULF COAST. A SIGNIFICANT 5H SHORT WAVE WILL DIG EAST ACROSS THE UPPER MIDWEST AND THIS WILL MAINTAIN A STRONG PGF OVER THE CENTRAL PLAINS STATES THROUGHOUT SUN. SO THIS CONFIGURATION WILL MAINTAIN BREEZY/WINDY CONDITIONS DURING THE DAYLIGHT HOURS ACROSS THE BRO CWA. THE MODERATE/STRONG SE SURFACE FLOW WILL KEEP THE DEWPOINT AND WARM TEMPERATURE ADVECTION IN PLACE IN THE SHORT TERM. DIURNAL HEATING WILL HELP GENERATE AFTERNOON AND EARLY EVENING SC/CU FIELDS OVER THE NEXT SEVERAL DAYS. MAV AND MET TEMP GUIDANCE OVER THE NEXT SEVERAL DAYS IS IN REASONABLE AGREEMENT...HOWEVER...THE MODEL TEMP GUIDANCE APPEARS TO BE TOO FAST IN THE EXPECTED WARM UP. SO WILL GO A LITTLE BELOW MET HIGH TEMPS FOR THE PERIOD. && .BRO WATCHES/WARNINGS/ADVISORIES...SCA FOR GMZ130. && $$ SYNOPTIC...CASTILLO AVIATION/MARINE...PHILO MESO...ABBOTT THIS PRODUCT IS ALSO AVAILABLE ON OUR INTERNET WEB PAGE AT: HTTP://WWW.SRH.NOAA.GOV/BRO tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 306 AM MDT SAT APR 17 2004 .SHORT TERM... (TODAY AND TONIGHT) ...POTENTIAL RED FLAG FIRE WEATHER CONDS THIS AFTN/EVE SERN CO... CURRENTLY...WATER VAPOR AND RUC UPPER AIR ANALYSES SHOWS SWLY FLOW ACROSS THE CNTRL ROCKIES INTO THE DESERT SW. 100-120KT ULJ JUST ABOUT TO MOVE INTO SWRN US. UPPER LEVEL WIND SPEEDS STARTING INCREASE ACROSS SWRN CO. FIRST WAVE OF HIGH CLOUDS IS ABOUT TO EXIT ERN CO EARLY THIS MORNING. THE NEXT BATCH OF HIGH LEVEL MOISTURE WAS DOWN AROUND THE BAJA OF CA AND OLD MEXICO. SOUTHWEST WINDS HAVE BEEN BLOWING ALL NIGHT OVER THE HIGH TERRAIN PER DOT AWOS SENSORS WITH GUST REPORTS OF 25-35KTS. OCCASIONALLY...SW WIND 10-15KTS HAS BEEN REPORTED AT KCOS AND KTAD(ENHANCED DRAINAGE WIND). SFC DEW POINTS STILL IN THE SINGLE DIGITS TO TEENS GENERALLY AOA 6K OR 7K FT MSL AND ESPECIALLY AT HIGHER ELEVATIONS. 30S/40S/LOWER 50S SFC DEW POINTS ARE SPREAD ACROSS SERN NM AND THE TX PANHANDLE. TEMPS ACROSS THE SERN CO PLAINS ARE PRETTY MILD WITH READINGS IN THE 50S/LOWER 60S THANKS TO THE CLOUD COVER AND SOME WIND. TDA AND TNGT...QUITE A CHALLENGING FIRE WEATHER FORECAST THIS AFTN AND TNGT. MODELS STILL APPEAR TO BE ON TRACK WITH THE OVERALL TROP WINDS INCREASING DURING THE DAY AND ESPECIALLY TONIGHT IN RESPONSE TO THE 100-120KT MOVING INTO CO. THERE IS NOW HINTS OF SOME H5 MOISTURE MOVING INTO SRN CO TDA AND TNGT ALONG WITH SOME LOW LEVEL MOISTURE ADVECTION. WITH THIS POTENTIAL MOISTURE...THERE COULD BE SOME HIGH CLOUD BASE VIRGA THIS AFTERNOON...WHICH WOULD SUPPORT WIND GUSTS OF 30-40KTS. NOW...IF THE CLOUD COVER IS MORE WIDESPREAD AND THICKER...THEN THE POTENTIAL HEATING AND MIXING MIGHT NOT BE REALIZED...THUS NOT AS STRONG WINDS AND LOWER SFC DEW POINTS. MODEL MOS GUIDANCE HAS BEEN VERY CONSISTENT WITH THE 15-30KT SUSTAINED WIND SPEEDS IN SERN CO...SO HARD TO GO AGAINST SUCH CONSISTENCY. FUEL MOISTURE REPORTS ARE DRY CONDITIONS IN SERN CO AND YESTERDAY'S 10HR FUEL MOISTURE IS REPORTED/CALCULATED TO BE 1%-3% IN SERN CO. HIGH TEMPERATURES TODAY CERTAINLY LOOK TO BE MUCH ABOVE MID APR AVE READINGS. WILL GO AHEAD AND ISSUE A RED FLAG WARNING FOR FIRE WEATHER ZONES 226>237(I-25 CORRIDOR TO EXTREME SERN CO). FOR TNGT...WILL PLAY THE LOW LEVEL MOISTURE SURGE INTO SERN CO WITH DEW POINTS IN THE 30S/40S/LOWER 50S. WINDS WILL POTENTIALLY STAY UP... BUT THE HUMIDITY LEVELS WILL INCREASE...SO WILL END THE RED FLAG WARNING AT 9PM. VERY CHALLENGING MIN TEMPS TNGT. WITH SFC/PBL STAYING UP...OR INCREASING...TURBULENT MIXING COULD KEEP TEMPS MILD OVERNIGHT. MODELS ARE STILL CONSISTENT WITH KEEPING QPF IN THE SWRN CO MTS THANKS TO MOISTURE AND UPSLOPE FLOW MUCH OF THE NGT. THERE COULD BE SOME HIGH TERRAIN 1-3 INCH SNOW AMOUNTS BY SUN AM. WILL INCREASE POPS TO 50% IN THE ERN SAN JUAN MTS. ANY "SIGNIFICANT" WIND WILL LIKELY REMAIN AROUND MT TOP LEVELS...HOWEVER...WOULD BE SURPRISED TO SEE SOME WINDS POTENTIAL "SPILL" DOWN THE LEE SIDE OF THE NRN SANGRE DE CRISTO MTS OR BE CHANNELED AROUND LA VETA PASS/WALSENBURG. [METZE] .LONG TERM... (SUNDAY THROUGH FRIDAY) ...STRONG WINDS EXPECTED ON SUNDAY... AS THE UPPER DISTURBANCE MOVES ACROSS THE NORTHERN PORTION OF THE STATE AND EXITS SUNDAY...110-120 KT CORE OF THE UPPER JET SWEEPS ACROSS COLORADO. COUPLED WITH GOOD DOWNWARD FORCING...THIS WILL PRODUCE STRONG AND GUSTY WINDS ACROSS THE CWA ON SUNDAY. MAX TEMPS ARE EXPECTED TO BE A BIT COOLER...3-4 DEGS C COOLER AS PER 850 AND 700 MB TEMP CHARTS...SO CORRESPONDING HIGHER RHS SHOULD PREVENT ANY FIRE WEATHER HIGHLIGHT ISSUANCE. HOWEVER...WINDS WILL BE STRONG... AND PRESCRIBED BURNING IS NOT ADVISED. ADJUSTED MAX T GRIDS SLIGHTLY...BUT NUMERICAL GUIDANCE IS ALL OVER THE PLACE AND OF LITTLE HELP. AS PREVIOUS FORECASTER NOTED...THE UPPER PATTERN BECOMES MORE W-NW THROUGH THE PERIOD WITH A NUMBER OF UPPER DISTURBANCES MOVING ACROSS THE ROCKY MT REGION. KEPT ISOLATED POPS GOING IN MOST AREAS... ESPECIALLY ACROSS THE HIGHER TERRAIN...BUT THE AREA MOST AFFECTED THROUGH THE EXTENDED LOOKS TO BE THE CENT MTS. LESSENED THE SKY COVER FOR THE PLAINS ON MON...OTHERWISE PARTLY CLOUDY SKIES LOOKS GOOD FOR NOW DUE TO MODEL UNCERTAINTY. IF CURRENT TRENDS CONTINUE... PRECIP CHANCES MIGHT HAVE TO BE LOWERED FURTHER SINCE THE DOWNSLOPE FLOW WOULD KEEP MAJORITY OF THE AREA DRY. \\MOORE// && .PUB WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING FROM 1PM TO 9PM SATURDAY FOR FIRE WEATHER ZONES 226 TO 237. (EASTERN PLAINS AND INTERSTATE 25 CORRIDOR FIRE ZONES). && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT SAT APR 17 2004 .DISCUSSION... MAIN FCST CONCERNS ARE TIMING PCPN ARRIVAL TONIGHT...COVERAGE OF PCPN SUN/SUN NIGHT AND POTENTIAL OF HVY RAIN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW VORTEX CENTERED OVER NCNTRL CANADA...BROAD RIDGE OVER SCNTRL CONUS AND A TROF ALONG THE W COAST. WEAK SHORTWAVE AND LOW-LEVEL JET AROUND 30KTS PER PROFILERS RESULTED IN AREA OF SHRA/ISOLD TSRA THAT PASSED OVER ABOUT THE SE HALF OF FCST AREA DURING THE NIGHT. TIGHTENING CONFLUENT FLOW BTWN SRN RIDGE AND NRN CANADA VORTEX RESULTING IN BUILDING SFC PRES FROM ALBERTA EWD INTO ONTARIO. THIS WILL BE THE STORY FOR TODAYS WEATHER. COLD FRONT THAT DROPPED INTO UPPER MI YESTERDAY IS STARTING TO BECOME BETTER DEFINED ACROSS IA/WI/LWR MI AS IT CONTINUES TO DRIFT S IN RESPONSE TO RISING SFC PRES TO THE N. DRY DAY ON TAP TODAY AS SFC HIGH BUILDS ACROSS SCNTRL CANADA WITH CENTER MOVING TO ONTARIO BY 00Z. N TO NERLY FLOW AHEAD OF SFC HIGH WILL BRING COOLER/DRIER AIR INTO UPPER MI TODAY. ADDITIVE LAKE BREEZE COMPONENT OFF LAKE SUPERIOR WILL ONLY AID THE COOLING/DRYING AND WILL ENSURE A FAIRLY CHILLY DAY NEAR THE LAKE...ESPECIALLY AFTER YESTERDAYS WARMTH. EXPECT HIGH TEMPS NO BETTER THAN MID 40S LAKESIDE...RISING TO NEAR 60 OVER THE SRN INTERIOR. ONLY COOLING NEAR LAKE MICHIGAN WILL BE IN MENOMINEE COUNTY AS ERLY COMPONENT TO THE FLOW WILL SPREAD MARINE LAYER INLAND THERE. FAIR AMOUNT OF SUNSHINE EXPECTED...BUT THERE WILL BE AN INCREASE IN HIGHER CLOUDS IN THE AFTN AS STRENGTHENING ISENTROPIC ASCENT WITH RAPIDLY LOWERING CONDENSATION PRES DEFICITS DEVELOPS JUST UPSTREAM (PER ETA 305K SFC...AROUND 600MB) WITH CLOUDS THEN STREAKING E. CLOUDS WILL CONTINUE TO THICKEN TONIGHT AS LOW-LEVEL JET/ISENTROPIC ASCENT/MOISTURE ADVECTION STRENGTHEN ACROSS PLAINS IN RESPONSE TO TROF/HEIGHT FALLS MOVING THRU ROCKIES. SFC FRONT SHOULD BE LOCATED NRN IA/NRN IL/NRN IN/SRN LWR MI THIS EVENING AND WILL BEGIN TO DRIFT BACK N IN THE FACE OF WAA PATTERN. UPPER JET IN CONFLUENT FLOW ACROSS ONTARIO WILL PLACE WRN LAKES REGION IN FAVORABLE BROAD RIGHT ENTRANCE REGION UPPER DIFFLUENCE OVERNIGHT...AIDING STRENGTHENING OF THE LOW-LEVEL JET. DEVELOPING 50KT LOW-LEVEL JET AIMING TOWARD UPPER MI SHOULD SUPPORT RAPID NEWD PCPN DEVELOPMENT INTO THE AREA. PLENTY OF MOISTURE WILL SURGE N WITH PRECIPITABLE WATER INCREASING TO ABOUT AN INCH BY 12Z SUN. GOING FCST HAS HIGH LIKELY POPS AFTER MIDNIGHT ACROSS THE SRN FCST AREA TRENDING TO HIGH CHC ACROSS THE N. WILL UP POPS A CATEGORY GIVEN INCREASING MODEL AGREEMENT AND QUITE FAVORABLE FORCING. STILL QUITE A BIT OF UNCERTAINTY IN HOW PCPN WILL PLAY OUT ON SUN AS SFC WARM FRONT STRUGGLES N TOWARD UPPER MI. GFS HAS SOME FEEDBACK PROBLEMS WITH A NICE BULLSEYE OF 1 TO 1.65 INCHES ACROSS A GOOD PORTION OF UPPER MI SUN...PCPN AMOUNTS MIGHT NOT BE UNREASONABLE THOUGH GIVEN MOISTURE ADVECTION. ETA GRADUALLY PUSHES BULK OF WAA PCPN BAND N OF THE AREA AS 850MB WARM FRONT MOVES N TO LAKE SUPERIOR BY 00Z MON. ETA PCPN IS 0.15 TO 0.75 INCHES. WHERE EXACTLY HEAVIEST PCPN FALLS ON SUN DURING THE DAY WILL BE TOUGH TO PIN DOWN...BUT IT IS PROBABLY SAFE TO SAY A GENERAL 0.5 INCH RAINFALL WILL OCCUR WITH DEFINITE POTENTIAL FOR MORE IN SOME AREAS. GOING FCST FOR SUN IS IN GREAT SHAPE WITH CATEGORICAL POPS. DEEP LAYER SHEAR WELL IN EXCESS OF 40KTS SUPPORTS SVR POTENTIAL...BUT WOULD EXPECT ANY SVR TO BE CONFINED TO HAIL WITH CHILLY BNDRY LAYER N OF SFC WARM FRONT PREVENTING ANY WIND THREAT. ETA/GFS ARE SURPRISINGLY IN QUITE GOOD AGREEMENT NOW ON TAKING SFC LOW ACROSS CNTRL UPPER MI TOWARD VCNTY OF WHITEFISH BAY SUN NIGHT... WHICH SHOULD LEAD TO NEARLY STEADY OR EVEN RISING TEMPS OVER THE ERN FCST AREA DURING THE NIGHT. AT THE SAME TIME...MIDLEVEL TROF TAKES ON A POSITIVE TILT AS IT SHEARS ENE INTO CONFLUENT FLOW. PCPN PLACEMENT WILL CONTINUE TO BE A PROBLEM. ETA FOCUSES RELATIVELY NARROW HEAVY PCPN (1-2 INCHES) SUN NIGHT FROM NW WI ACROSS WRN LAKE SUPERIOR (JUST BRUSHING WRN UPPER MI) TO THE W OF SFC LOW TRACK WITH LITTLE/NO PCPN OVER ABOUT SE HALF OF UPPER MI. LOOKS A LITTLE UNREALISTIC GIVEN SYSTEM BEGINNING TO SHEAR OUT/WEAKEN...BUT ITS COUPLED UPPER JET STRUCTURE CERTAINLY SUPPORTS ITS PCPN LOCATION AND POTENTIAL SIGNIFICANT AMOUNTS. GFS IS BROADER IN COVERAGE AND LIGHTER IN AMOUNTS (0.5-0.8 INCHES) GENERALLY ALONG AND N OF SFC LOW TRACK. UKMET/CANADIAN ARE HINTING AT A SIMILAR PCPN PATTERN TO THAT OF THE ETA...BUT NOT AS HEAVY. WILL LEAN IN THE DIRECTION OF THE ETA FOR SUN NIGHT AND RANGE POPS FROM CATEGORICAL NW TO LIKELY SE...THOUGH POPS MAY NEED TO BE LOWERED MORE SE. CONFIDENCE IN ENTIRE EVENT PCPN TOTALS AND LOCATION OF HEAVIEST AMOUNTS IS STILL TOO UNCERTAIN TO WARRANT FLOOD WATCH ATTM. WOULD APPEAR NWRN AND NCNTRL AREAS WILL NEED TO BE WATCHED MOST CLOSELY AS THE EVENT NEARS AS THAT AREA STILL HAS SNOW IN THE WOODS AND THAT AREA MAY BE TARGETED BY BOTH LEAD WAA PCPN AND BY PCPN ASSOCIATED WITH MAIN SHORTWAVE. RIVERS IN THAT AREA ARE ALSO ON THE RISE AGAIN WITH RECENT SNOWMELT. PCPN WINDS DOWN MON...AND THERE IS STILL SOME POTENTIAL FOR SOME SNOW TO MIX IN FOR A TIME OVER THE HIGHER TERRAIN OF WRN UPPER MI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 357 AM EDT SAT APR 17 2004 .DISCUSSION... A LONG WAVE TROUGH OVER THE PACIFIC NORTHWEST AND RETURN FLOW AROUND SURFACE HIGH PRESSURE OFF THE SOUTHEAST COAST OF THE US HAS DEVELOPED A STRONG WARM AIR ADVECTION REGIME ACROSS THE CENTRAL PORTIONS OF THE COUNTRY. MEANWHILE...A TROUGH OVER HUDSON BAY HAS AN ASSOCIATED SURFACE FRONT EXTENDING ACROSS CENTRAL LAKE HURON AND INTO EXTREME SOUTHERN WISCONSIN AND CENTRAL IOWA. LOW LEVEL MASS CONVERGENCE ALONG AND NORTH OF THIS SURFACE FRONT...COUPLED WITH STEEP MID LEVEL LAPSE RATES HAS LED TO TO QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY NORTH OF THE FRONTAL BOUNDARY OVERNIGHT. THE MORE WIDESPREAD ACTIVITY IS NOW WORKING ACROSS SOUTHERN WISCONSIN/NORTHERN ILLINOIS AND IS THE REMNANTS OF A MESO SCALE CONVECTIVE SYSTEM (MCS) WHICH FORMED OVER IOWA LAST EVENING. SEVERE THUNDERSTORM POTENTIAL AND TEMPERATURES CONTINUE TO BE THE MAIN FORECAST CONCERNS THE NEXT THREE DAYS WITH THIS VERY SUMMER-LIKE AIRMASS OVER THE REGION. THE 00Z MODEL SUITE ARE IN RATHER GOOD AGREEMENT IN BRINGING THE SURFACE COLD FRONT SOUTH ACROSS THE FORECAST AREA TODAY AS HIGH PRESSURE BUILDING INTO NORTHERN ONTARIO WILL COMBINE WITH THE COLD STABLE MARINE LAYER OFF THE LAKE TO DRIVE THE FRONT SOUTH. THE CURRENT MESO ETA AND RUC INDICATE THAT THE FRONT WILL SETTLE INTO THE SAGINAW VALLEY THIS MORNING...THEN GRADUALLY PULL SOUTH ACROSS THE FORECAST AREA...REACHING THE STATE LINE BY THIS EVENING. A MESO SCALE CONVECTIVE VORTICITY MAX...REMNANTS OF THE IOWA MCS...WILL TRACK ACROSS SOUTHERN LOWER MICHIGAN THIS MORNING. LIFT AHEAD OF THIS WAVE WILL COMBINE WITH LOW LEVEL FRONTOGENETICAL FORCING TO PROVIDE A FAIRLY GOOD SHOT AT SOME SHOWERS AND THUNDERSTORMS THIS MORNING. LIFT SHOULD WEAKEN AS THIS SYSTEM HEADS EAST...SO WILL CARRY HIGHEST POPS ACROSS THE WESTERN PORTIONS OF THE AREA THIS MORNING. SURFACE BASED INSTABILITY WILL BE VERY WEAK THIS MORNING. WITH JUST MODEST ELEVATED INSTABILITY...NOT EXPECTING ANY SEVERE WEATHER THIS MORNING. ALTHOUGH SOME OF THE STORMS THIS MORNING MAY PRODUCE SMALL HAIL AND GUSTY WINDS. SOME SUBSIDENCE WILL BUILD IN IN THE WAKE OF THE MID LEVEL WAVE EARLY THIS AFTERNOON...WHICH MAY LEAD TO A BREAK IN THE CONVECTION. LIFT ALONG THE COLD FRONT...COMBINED WITH INCREASING DIURNAL INSTABILITY...SHOULD TOUCH OFF MORE CONVECTION BY THE MIDDLE OF THE AFTERNOON ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. GIVEN THE TEMPS UPSTREAM YESTERDAY...WILL GO ABOVE GUIDANCE A COUPLE DEGREES ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. MUCH COOLER CONDITIONS WILL EXIST NORTH OF THE FRONT...ESPECIALLY ACROSS HURON COUNTY WITH THE FLOW OFF THE LAKE...WHERE AFTERNOON TEMPS MAY STRUGGLE TO BREAK 60. SOME OF THE THUNDERSTORMS ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THIS AFTERNOON MAY BE SEVERE WITH SOUNDINGS INDICATING 0-6KM SHEAR AROUND 40M/S ALONG WITH VERY STEEP MID LEVEL LAPSE RATES. MODIFIED ETA FORECAST 18Z SOUNDING OVER DTW FOR 79/58 YIELDS SURFACED BASE CAPE OF 1900 J/KG. THERE IS ALSO A POTENTIAL FOR SUPERCELLULAR STORM TYPES AS THE FRONTAL BOUNDARY AND LAKE BREEZE BOUNDARY SHOULD YIELD HIGH STORM RELATIVE HELICITY. WILL THUS AGAIN HIGHLIGHT SEVERE STORM POTENTIAL IN THE HWO. THE UPPER TROUGH WILL MOVE INTO THE DESERT SW TONIGHT AS LEE SIDE CYCLOGENESIS WILL OCCUR ACROSS THE CENTRAL PLAINS. A 50-60KT LOW LEVEL JET WILL DEVELOP AHEAD OF THE SURFACE LOW...WITH MAXIMUM LIFT EXPECTED ACROSS WISCONSIN. THIS WILL ALLOW THE FRONTAL BOUNDARY TO LIFT BACK NORTH ACROSS THE AREA AS A WARM FRONT. DESPITE THE BEST LIFT BEING FOCUSED WEST OF THE AREA...WEAK LOW LEVEL FRONTAL CIRCULATIONS COUPLED WITH A LOW LEVEL THETA E RICH AIRMASS SHOULD LEAD TO QUITE A BIT OF CONVECTION ACROSS LOWER MI. THE BOUNDARY LAYER SHOULD BE FAIRLY STABLE...ESPECIALLY FARTHER NORTH INTO THE FORECAST AREA. HOWEVER...ETA SOUNDINGS OVERNIGHT INDICATE 500-800 J/KG OF CAPE CALCULATED ABOVE THE STABLE LAYER. WITH WET BULB ZERO HEIGHTS AROUND 9K FT...LARGE/SEVERE HAIL MAY BE POSSIBLE WITH SOME OF THE STORMS TONIGHT. STRONG/SEVERE WIND GUSTS WILL BE MORE LIKELY OVER THE FAR SOUTHERN PORTIONS OF THE FORECAST AREA...CLOSER TO THE SURFACE WARM FRONT. GIVEN THE COLD LAKES...EXPECT IT WILL TAKE SOME TIME FOR THE WARM FRONT TO LIFT NORTH. IT LIKELY WILL NOT CLEAR THE SAGINAW VALLEY UNTIL LATE SUNDAY MORNING AS STRONG 925-850MB WINDS DEVELOP OVER SE LOWER MI. THE UPPER TROUGH WILL LIFT INTO THE CENTRAL PLAINS ON SUNDAY...WEAKENING SLIGHTLY. WITH THE WARM FRONT LIFTING NORTH OF THE AREA...SE MICHIGAN WILL BE WELL WITHIN THE WARM SECTOR. WILL CARRY A CHANCE OF THUNDERSTORMS MAINLY DURING THE MORNING ACROSS THE NORTH GIVEN THE CLOSE PROXIMITY TO THE WARM FRONT. OTHERWISE...SHOULD BE ANOTHER SUMMER-LIKE DAY ACROSS THE AREA. BASED ON RECENT TEMPS IN THIS AIRMASS...WILL INCREASE HIGHS ON SUNDAY FROM GUIDANCE. EXPECT THERE WILL BE QUITE A FEW LOCALS TO BREAK THE 80 DEGREE MARK. THE UPPER TROUGH WILL PASS ACROSS THE GREAT LAKES REGION ON MONDAY. THE ASSOCIATED SURFACE LOW WILL PASS ACROSS THE NORTHERN LAKES REGION...WHILE THE SURFACE COLD FRONT STILL LOOKS TO PASS ACROSS THE AREA LATE MONDAY AFTERNOON/EARLY EVENING. VERY STRONG AND DEEP LAYER SHEAR WILL ACCOMPANY THE FRONT. MODELS STILL HOWEVER ARE RATHER WEAK WITH THE INSTABILITY...LIKELY DUE TO THE FACT THAT THEY ARE SHOWING THE LOW LEVEL THETA E RIDGE PASSING THROUGH THE AREA MONDAY MORNING...WELL IN ADVANCE OF THE SURFACE COLD FRONT. WILL HOWEVER CONTINUE TO MAINTAIN A MENTION OF SEVERE STORMS AHEAD OF THE FRONT GIVEN THE DEGREE OF WIND SHEER AND VERY STEEP MID LEVEL LAPSE RATES. COOLER AND DRYER WEATHER STILL LOOKS ON TARGET IN THE WAKE OF THIS SYSTEM ON TUESDAY. NO UPDATES HAVE BEEN MADE TO THE GRIDS BEYOND MONDAY. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ CONSIDINE EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL 947 AM EDT SAT APR 17 2004 .CURRENTLY...SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS THE FORECAST AREA EARLY THIS MORNING. TEMPERATURES ARE MUCH MILDER THAN PREVIOUS MORNINGS WITH READINGS ~60 TO THE LOWER 60S NORTH...AND MID 60S CENTRAL AND SOUTH. .REST OF TODAY...12Z RAOB DATA SHOWS A SUBSIDENCE INVERSION ~900MB WITH A BIT MORE MOISTURE NOTED BELOW IT...SO WILL LIKELY SEE A FEW MORE CLOUDS TODAY COMPARED TO THE LAST FEW DAYS...BUT STILL A VERY PLEASANT DAY EXPECTED. ONGOING ZONES LOOK ON TRACK...SO NO MORNING UPDATES EXPECTED. && .MARINE...TRANQUIL BOATING CONDITIONS WILL CONTINUE THE REMAINDER OF THE TODAY WITH EAST WINDS ~10 KNOTS AND A LATE DAY SEA BREEZE POSSIBLE FROM SARASOTA NORTH. NO CHANGES EXPECTED IN THE 1030 AM UPDATE. && .FIRE WEATHER...TRICKY FORECAST FOR THE AFTERNOON. RUC DATA SHOW SUB 35 PERCENT RH'S ACROSS A GOOD PORTION OF MY CWA FROM 17Z ON WHILE THE ETA/MESO-ETA AND GFS KEEP RH'S ABOVE CRITICAL VALUES. SEEING THAT WE STRUGGLED TO GET FLAG CONDITIONS YESTERDAY...FEEL THE ETA MESO-ETA AND GFS SOLUTIONS ARE MORE REALISTIC IN DEPICTING PERHAPS AN HOUR OR TWO OF MARGINALLY LOW RH'S...BUT GIVEN THE UNCERTAINTY WILL LEAVE RED FLAG WARNING IN PLACE FOR LEVY COUNTY. ELSEWHERE NO OTHER HIGHLIGHTS EXPECTED AT THIS TIME. && .TBW WATCHES/WARNINGS/ADVISORIES... ...RED FLAG WARNING THIS AFTERNOON FOR LEVY COUNTY FOR LOW RH DURATIONS. $$ MCMICHAEL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1126 AM EDT SAT APR 17 2004 .UPDATED... SQUALL LINE HAS EXITED THE CWA AND THE CONVECTIVE SHORTWAVE (BASED ON THE WATER VAPOR IMAGE LOOPS) IS EXITING THE CWA AS OF 15Z. THERE IS RATHER DECENT SUBSIDENCE BEHIND THIS SHORTWAVE AND THAT SHOULD SUPPRESS ANY CONVECTION THIS AFTERNOON OVER THE CWA. THIS SUBSIDENCE CAN BE SEEN ON THE RUC SOUNDING LOOPS AS THE SOUNDING SHOW DRYING FROM 500MB DOWN THE TO THE SURFACE WITH THE MOST DRYING BETWEEN 750 AND 500MB. THE PROBLEM THOUGH IS WINDS HAVE NOT BECOME NORTHWEST OR WEST YET OVER ANY OF THE CWA AS OF 15Z. I DO BELIEVE AS HEATING CONTINUES DUE TO MOSTLY CLEAR SKIES WEST OF THE CONVECTIVE CLOUD SYSTEM MOVING OUT OF OUR CWA WE WILL MIXED DOWN THE 270/20KT OUR VAD SHOWS AT 1000 FT. ONCE THAT HAPPENS...ANY CHANCE OF SFC CONVERGENCE WILL BE GONE. THE WILL BE SOME CAPE THIS AFTERNOON...NEAR 1000 J/KG IF THE TEMPERATURES GET INTO THE MID 70S AS I THINK THEY WILL BUT THAT WILL BE CAPED. EVEN SO...I KEEP A 30 PCT CHANCE ALONG THE I-94 AREA CLOSER TO THE FRONT... BUT I DO NOT THINK ANYTHING WILL REALLY HAPPEN THERE. IF WE DID GET CONVECTION TO FIRE THIS AFTERNOON...HAIL WOULD BE OUR BIGGEST THREAT WITH WB ZERO HEIGHTS NEAR 10000 FT. WIND PROFILES DO NOT SHOW MUCH POTENTIAL...THERE IS SOME MID LEVEL DRY AIR TO HELP THAT CAUSE THOUGH. EVEN SO...I REALLY DO NOT BELIEVE THERE IS MUCH OF A SEVERE THREAT IN SOUTHWEST MICHIGAN UNTIL AFTER MIDNIGHT WHEN THAT MCS FROM MN/WI ROLLS IN. WITH A FAIR AMOUNT OF SUN...HIGHS SHOULD MAKE THE MID 70S OVER MOST OF THE CWA THIS AFTERNOON. DUE TO WEST WINDS HIGHS WILL BE IN THE 40S AT THE BEACHES...MID 50S JUST INLAND (LESS THAN A MILE)OF THE BEACHES AND NEAR 70 ABOUT 5 MILES INLAND OF THE BEACHES. I PULLED THE THUNDERSTORMS FROM EARLY TONIGHT OUT OF THE FORECAST. WE WILL HAVE TO WAIT FOR THE CONVECTION THAT FIRES ON THE NOSE OF THE LOW LEVEL JET NORTH OF THE WARM FRONT TO ROLL INTO LOWER MICHIGAN. I CAN NOT SEE THAT HAPPENING UNTIL AFTER 04Z AT THE EARLIEST. && .GRR...WATCHES/WARNINGS/ADVISORIES...NONE. && WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1025 AM EDT SAT APR 17 2004 .UPDATE... MCS CONTINUES TO WEAKEN AND PULL EAST OF SOUTHEAST MICHIGAN. WILL BE ISSUING AN UPDATED ZONE FORECAST TO ACCOUNT FOR DRY CONDITIONS EARLY THIS AFTERNOON. CLEARING ALREADY WORKING INTO WESTERN LOWER MICHIGAN AT THIS HOUR. WILL STILL GIVE THE MAX TEMPERATURE FORECAST A CHANCE TO WORK TODAY (JUST LOWERED TEMPS BY A DEGREE). OUTFLOW BOUNDARIES HAVE MADE THE FRONT TOUGH TO LOCATE. BEST GUESS RIGHT NOW WOULD BE NEAR THE M 59 CORRIDOR. STILL EXPECTING THE FRONTAL BOUNDARY TO GRADUALLY SINK SOUTH...MOVING JUST SOUTH OF THE LOWER MICHIGAN BORDER. NORTHERN THIRD/HALF OF THE CWA SHOULD BE SHOWER AND THUNDERSTORM FREE AS NORTHEAST WINDS OFF OF LAKE HURON HELP TO STABILIZE THINGS. THE CHANCE FOR THUNDERSTORMS LATE THIS AFTERNOON WILL INCREASE TOWARD THE OHIO BORDER...WHERE THE FRONTAL BOUNDARY WILL BE LOCATED...ALONG WITH ANY LINGERING OUTFLOW BOUNDARIES. WITH THIS AREA BEING WEAKLY CAPPED AND TEMPS CLIMBING INTO THE UPPER 70S...CONVECTION WOULD LIKELY FIRE...WITH HAIL BEING THE MAIN THREAT...AS LOW LEVEL WINDS REMAIN FAIRLY LIGHT. WILL WATCH THE FRONTAL BOUNDARY PROGRESS CLOSELY...AS IT IS STILL POSSIBLE THE FRONT WILL SAG FAR ENOUGH SOUTH TO KEEP ALL OF SOUTHEAST MICHIGAN DRY THIS AFTERNOON...AS EASTERLY WINDS OFF OF LAKE ERIE HELPS STABILIZE THE DETROIT METRO AREA. OF COURSE...WITH EASTERLY WINDS...MAXES WILL NOT LIKELY REACH THE UPPER 70S. WILL CONTINUE WITH JUST CHANCE POPS LATE TODAY FOR THE SOUTHERN HALF OF THE CWA. NO CHANGES TO FORECAST TONIGHT...AS ACTIVITY SHOULD FIRE UP ALONG THE RETURNING WARM FRONT. ANOTHER MCS EXPECTED TO FIRE UP ALONG THE WARM FRONT UPSTREAM ACROSS THE UPPER MISSISSIPPI VALLEY/WESTERN GREAT LAKES. UNLIKE THIS MORNING'S MCS...THIS ONE HAS A SHOT TO MAINTAIN IT'S SELF AS IT MOVES INTO THE CENTRAL GREAT LAKES. && SF .DISCUSSION ISSUED AT 357 AM... A LONG WAVE TROUGH OVER THE PACIFIC NORTHWEST AND RETURN FLOW AROUND SURFACE HIGH PRESSURE OFF THE SOUTHEAST COAST OF THE US HAS DEVELOPED A STRONG WARM AIR ADVECTION REGIME ACROSS THE CENTRAL PORTIONS OF THE COUNTRY. MEANWHILE...A TROUGH OVER HUDSON BAY HAS AN ASSOCIATED SURFACE FRONT EXTENDING ACROSS CENTRAL LAKE HURON AND INTO EXTREME SOUTHERN WISCONSIN AND CENTRAL IOWA. LOW LEVEL MASS CONVERGENCE ALONG AND NORTH OF THIS SURFACE FRONT...COUPLED WITH STEEP MID LEVEL LAPSE RATES HAS LED TO TO QUITE A BIT OF SHOWER AND THUNDERSTORM ACTIVITY NORTH OF THE FRONTAL BOUNDARY OVERNIGHT. THE MORE WIDESPREAD ACTIVITY IS NOW WORKING ACROSS SOUTHERN WISCONSIN/NORTHERN ILLINOIS AND IS THE REMNANTS OF A MESO SCALE CONVECTIVE SYSTEM (MCS) WHICH FORMED OVER IOWA LAST EVENING. SEVERE THUNDERSTORM POTENTIAL AND TEMPERATURES CONTINUE TO BE THE MAIN FORECAST CONCERNS THE NEXT THREE DAYS WITH THIS VERY SUMMER-LIKE AIRMASS OVER THE REGION. THE 00Z MODEL SUITE ARE IN RATHER GOOD AGREEMENT IN BRINGING THE SURFACE COLD FRONT SOUTH ACROSS THE FORECAST AREA TODAY AS HIGH PRESSURE BUILDING INTO NORTHERN ONTARIO WILL COMBINE WITH THE COLD STABLE MARINE LAYER OFF THE LAKE TO DRIVE THE FRONT SOUTH. THE CURRENT MESO ETA AND RUC INDICATE THAT THE FRONT WILL SETTLE INTO THE SAGINAW VALLEY THIS MORNING...THEN GRADUALLY PULL SOUTH ACROSS THE FORECAST AREA...REACHING THE STATE LINE BY THIS EVENING. A MESO SCALE CONVECTIVE VORTICITY MAX...REMNANTS OF THE IOWA MCS...WILL TRACK ACROSS SOUTHERN LOWER MICHIGAN THIS MORNING. LIFT AHEAD OF THIS WAVE WILL COMBINE WITH LOW LEVEL FRONTOGENETICAL FORCING TO PROVIDE A FAIRLY GOOD SHOT AT SOME SHOWERS AND THUNDERSTORMS THIS MORNING. LIFT SHOULD WEAKEN AS THIS SYSTEM HEADS EAST...SO WILL CARRY HIGHEST POPS ACROSS THE WESTERN PORTIONS OF THE AREA THIS MORNING. SURFACE BASED INSTABILITY WILL BE VERY WEAK THIS MORNING. WITH JUST MODEST ELEVATED INSTABILITY...NOT EXPECTING ANY SEVERE WEATHER THIS MORNING. ALTHOUGH SOME OF THE STORMS THIS MORNING MAY PRODUCE SMALL HAIL AND GUSTY WINDS. SOME SUBSIDENCE WILL BUILD IN IN THE WAKE OF THE MID LEVEL WAVE EARLY THIS AFTERNOON...WHICH MAY LEAD TO A BREAK IN THE CONVECTION. LIFT ALONG THE COLD FRONT...COMBINED WITH INCREASING DIURNAL INSTABILITY...SHOULD TOUCH OFF MORE CONVECTION BY THE MIDDLE OF THE AFTERNOON ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. GIVEN THE TEMPS UPSTREAM YESTERDAY...WILL GO ABOVE GUIDANCE A COUPLE DEGREES ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. MUCH COOLER CONDITIONS WILL EXIST NORTH OF THE FRONT...ESPECIALLY ACROSS HURON COUNTY WITH THE FLOW OFF THE LAKE...WHERE AFTERNOON TEMPS MAY STRUGGLE TO BREAK 60. SOME OF THE THUNDERSTORMS ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THIS AFTERNOON MAY BE SEVERE WITH SOUNDINGS INDICATING 0-6KM SHEAR AROUND 40M/S ALONG WITH VERY STEEP MID LEVEL LAPSE RATES. MODIFIED ETA FORECAST 18Z SOUNDING OVER DTW FOR 79/58 YIELDS SURFACED BASE CAPE OF 1900 J/KG. THERE IS ALSO A POTENTIAL FOR SUPERCELLULAR STORM TYPES AS THE FRONTAL BOUNDARY AND LAKE BREEZE BOUNDARY SHOULD YIELD HIGH STORM RELATIVE HELICITY. WILL THUS AGAIN HIGHLIGHT SEVERE STORM POTENTIAL IN THE HWO. THE UPPER TROUGH WILL MOVE INTO THE DESERT SW TONIGHT AS LEE SIDE CYCLOGENESIS WILL OCCUR ACROSS THE CENTRAL PLAINS. A 50-60KT LOW LEVEL JET WILL DEVELOP AHEAD OF THE SURFACE LOW...WITH MAXIMUM LIFT EXPECTED ACROSS WISCONSIN. THIS WILL ALLOW THE FRONTAL BOUNDARY TO LIFT BACK NORTH ACROSS THE AREA AS A WARM FRONT. DESPITE THE BEST LIFT BEING FOCUSED WEST OF THE AREA...WEAK LOW LEVEL FRONTAL CIRCULATIONS COUPLED WITH A LOW LEVEL THETA E RICH AIRMASS SHOULD LEAD TO QUITE A BIT OF CONVECTION ACROSS LOWER MI. THE BOUNDARY LAYER SHOULD BE FAIRLY STABLE...ESPECIALLY FARTHER NORTH INTO THE FORECAST AREA. HOWEVER...ETA SOUNDINGS OVERNIGHT INDICATE 500-800 J/KG OF CAPE CALCULATED ABOVE THE STABLE LAYER. WITH WET BULB ZERO HEIGHTS AROUND 9K FT...LARGE/SEVERE HAIL MAY BE POSSIBLE WITH SOME OF THE STORMS TONIGHT. STRONG/SEVERE WIND GUSTS WILL BE MORE LIKELY OVER THE FAR SOUTHERN PORTIONS OF THE FORECAST AREA...CLOSER TO THE SURFACE WARM FRONT. GIVEN THE COLD LAKES...EXPECT IT WILL TAKE SOME TIME FOR THE WARM FRONT TO LIFT NORTH. IT LIKELY WILL NOT CLEAR THE SAGINAW VALLEY UNTIL LATE SUNDAY MORNING AS STRONG 925-850MB WINDS DEVELOP OVER SE LOWER MI. THE UPPER TROUGH WILL LIFT INTO THE CENTRAL PLAINS ON SUNDAY...WEAKENING SLIGHTLY. WITH THE WARM FRONT LIFTING NORTH OF THE AREA...SE MICHIGAN WILL BE WELL WITHIN THE WARM SECTOR. WILL CARRY A CHANCE OF THUNDERSTORMS MAINLY DURING THE MORNING ACROSS THE NORTH GIVEN THE CLOSE PROXIMITY TO THE WARM FRONT. OTHERWISE...SHOULD BE ANOTHER SUMMER-LIKE DAY ACROSS THE AREA. BASED ON RECENT TEMPS IN THIS AIRMASS...WILL INCREASE HIGHS ON SUNDAY FROM GUIDANCE. EXPECT THERE WILL BE QUITE A FEW LOCALS TO BREAK THE 80 DEGREE MARK. THE UPPER TROUGH WILL PASS ACROSS THE GREAT LAKES REGION ON MONDAY. THE ASSOCIATED SURFACE LOW WILL PASS ACROSS THE NORTHERN LAKES REGION...WHILE THE SURFACE COLD FRONT STILL LOOKS TO PASS ACROSS THE AREA LATE MONDAY AFTERNOON/EARLY EVENING. VERY STRONG AND DEEP LAYER SHEAR WILL ACCOMPANY THE FRONT. MODELS STILL HOWEVER ARE RATHER WEAK WITH THE INSTABILITY...LIKELY DUE TO THE FACT THAT THEY ARE SHOWING THE LOW LEVEL THETA E RIDGE PASSING THROUGH THE AREA MONDAY MORNING...WELL IN ADVANCE OF THE SURFACE COLD FRONT. WILL HOWEVER CONTINUE TO MAINTAIN A MENTION OF SEVERE STORMS AHEAD OF THE FRONT GIVEN THE DEGREE OF WIND SHEER AND VERY STEEP MID LEVEL LAPSE RATES. COOLER AND DRYER WEATHER STILL LOOKS ON TARGET IN THE WAKE OF THIS SYSTEM ON TUESDAY. NO UPDATES HAVE BEEN MADE TO THE GRIDS BEYOND MONDAY. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ CONSIDINE EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1145 AM EDT SAT APR 17 2004 .UPDATE... LATEST RUN OF THE ETA MODEL APPEARS TO HAVE DECREASED THE FORECAST INSTABILITY A BIT OVER CENTRAL NY... WITH FORECAST CAPE VALUES IN THE SYR AREA NOW DOWN BELOW 1000 J/KG... AND CAPE VALUES ON THE RUC BELOW 300 J/KG. BASED ON CURRENT SAT LOOPS THIS LOOKS REASONABLE AS A LARGE AREA OF MID AND HI CLOUDS ARE MOVING SOUTHEAST TOWARD THE AREA. BASED ON THIS WILL LOWER FORECAST HIGH TEMPS A FEW DEGREES. FORECAST TIMING FOR CHC THUNDERSTORMS STILL LOOKS REASONABLE AS A COLD FRONT APPROACHES THE AREA. STORMS SHOULD BE CONFINED TO CENTRAL NY THIS AFTERNOON... THEN COULD DRIFT AS FAR SOUTHEAST AS NORTHEAST PA THIS EVENING. LIMITED INSTABILITY SHD KEEP STORMS FROM BECOMING SEVERE DESPITE PRETTY DECENT SHEAR PROFILES. .DISCUSSION... ANOTHER WARM DAY ON TAP, WITH THE POTNL FOR SOME CONVECTION LATER THIS AFTN AND EVNG AS A CDFNT APRCHS THE AREA. THE CDFNT WILL PUSH THRU TNGT, AND THEN RETURN NEWD TMRW AS A WMFNT. MDLS STILL FCST A 1031 HIGH N OF THE FNT, WHICH WILL GIVE IT A PRETTY DECENT PUSH. BEST GUESS IS A PSN FROM SW NY SEWD TO NEAR ABE/PHL BY 12Z SUNDAY. THE WMFNT LOOKS LIKE IT WILL TAKE ON MORE OF A N-S ORIENTATION AS IT HEADS BACK TO THE NE ON SUNDAY. BASED ON UPSTREAM MAXES AND EXPECTATION OF A GOOD DEAL OF SUNSHINE THRU AT LEAST MIDDAY, XPCT MAY AREAS TO GET INTO THE U70S TDA. MDLS ARE IN PRETTY GOOD AGREEMENT WITH TIMING OF CONVECTIVE POTNL FOR TDA AND TNGT, AND AGREE WITH THE CRNT FCST. MDLS SHOW LI'S ARND -2 WITH CAPES GNRLY 500-900, HIGHEST OVER UPSTATE. 0-3 KM BULK SHEAR IS GREATEST OVER THE NRN FINGER LAKES AND WRN MOHAWK VLY THIS AFTN, WITH VALUES OF 25-30 KTS, SUGGESTING POTNL FOR SOME WIND PRODUCERS IF ANYTHING WERE TO GET ORGANIZED, BUT WITH MARGINAL INSTABILITY THIS LOOKS UNLIKELY. BEST GUESS AT THIS POINT IS THAT WE COULD SEE SOME NON-SEVERE GUSTY WINDS WITH A FEW TSTMS THIS AFTN ACRS THE CNTRL SRN TIER AND FINGER LAKES. PLAN ON LEAVING THE CHC POPS AS IS FOR THIS AFTN AND EVNG. LINGERING ACTIVITY SHUD PUSH SEWD THIS EVENG, PRBLY WEAKENING TO JUST SHOWERS AS IT DOES SO, BUT WILL LEAVE IN THE CHC FOR TSTMS INTO THE EVNG HRS AS ACTIVITY HEADS INTO NE PA. PER SUGGESTION FROM CTP, SOME FOG LIKELY TO DVLP LATE (SPCLY IF WE GET THE PCPN) AND WILL ADD TO WX GRIDS. ON SUNDAY, THE WMFNT RETURNS NWD. BOTH THE ETA AND GFS ARE NOW SHOWING A WEAK S/WV TRACKING EWD ACRS THE AREA TMRW AFTN AS THIS OCCURS, AND THEY ALSO SHOW INSTABILITY DVLPNG IN THE WARM SECTOR TMRW AFTN. MESOETA EVEN HINTS AT SOME POOLING OF TD'S JUST WEST OF THE WMFNT. GIVEN THE POTNL TRIGGERS FOR CONVECTION (SFC BNDRY, S/WV ALOFT, INSTABILITY), THINK IT'S PRUDENT TO INTRODUCE A LOW CHC POP FOR A SHRA/TSRA LATE TMRW AFTN/ERLY EVNG ACRS MOST OF THE FCST AREA. THE REAL CHALLENGE WILL BE THE MAX TEMP FCST. THERE ARE SUBTLE DIFFS IN THE MDLS W/RESPECT TO THIS, WITH THE GFS SLOWER BRINGING THE FNT THRU. ACTUALLY, THE MAV GUIDANCE GIVES UPSTATE NY MAXES IN THE M/U60S, WITH 70S RESTRICTED TO PA. GIVEN THE SHALLOW NATURE OF THE COOL AIR, WILL LEAN TWDS THE FASTER ETA BUT STILL INDICATE THE COOLEST MAXES ACRS NRN ZONES TMRW. OTHER THAN TWEEKING UP SUNDAY NGT MINS A TAD, NO CHGS TO LATTER PDS. BRADY. .LONG RANGE (SUN NITE-FRI) WARM FRONT NORTH OF THE REGION...AND WARM SWLY FLOW ALOFT EARLY IN THE PD WILL BE REPLACED BY MORE SEASONABLE CONDITIONS AS COOLER CANADIAN HIGH PRESSURE MOVES ACROSS ERN CANADA BEHIND A COLD FRONT MON NITE-TUES. MON SHOULD SEE ANOTHER DAY INTO THE 70S. MDLS SHOW WEDGE OF UNSTABLE AIR AHEAD OF FRONT...SO FEW SHRA/TSRA PSBL MON AFTN-EVE. LATEST RUNS OF MED RANGE MDLS ARE IN GOOD AGREEMENT INTO WEDS BEFORE DIVERGING ON LOW OVER CNTRL PLAINS AND RETURNING WARM FRONT LIFTING AT OUR REGION. OPNL GFS MUCH DEEPER WITH SYS THAN OTHER MDLS...SO WL IGNORE THAT OUTLIER FOR NOW AND FOLLOW MORE OPEN WAVE SOLUTIONS WHICH INCLUDE GFS ENSEMBLES. RESULT WILL BE HEALTHY ISENTROPIC LIFT OVER THE WARM FRONT THURS-FRI BRINGING CLOUDS AND PDS OF RAIN. && .AVIATION... VFR CONDITIONS EXPECTED THROUGH THE PERIOD WITH SCT-BKN MID/HI CLDS TONIGHT AND SFC BASED CU BY SAT AFTRN. MID CLDS WILL BE MOSTLY BKN SYR-UCA AND SCT-BKN ITH/BGM/ELM AND MAINLY SCT AVP OVRNGT AND EARLY SAT. LIGHT WINDS BCM SWLY 10 KTS AFTER 12Z. CU CUD BECOME BKN IN SYR/UCA/ITH/ELM AND BGM LATER IN THE DAY SAT AS MOISTURE ADVTN INCREASES DURG DAY. CHC SHRA/TSTMS LATE IN THE DAY FOR MOST OF UPSTATE NY WITH MVFR CIGS. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. $$ ny SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 935 AM CDT SAT APR 17 2004 .UPDATE...SENT UPDATES TO THE COASTAL AND PUBLIC FORECAST. HAVE GONE MOSTLY CLOUDY IN MOST LOCATIONS TODAY AS CU FIELD IS EXPECTED TO DEVELOP IN CLEAR AREAS SIMILAR TO YESTERDAY AND CREATE MAINLY M/C SKIES. REMOVED MORNING FOG FROM FORECAST AND ALSO TWEAKED WINDS AND WORDING. FOR THE MARINE FORECAST HAVE DROPPED THE SCA FOR THE OFFSHORE WATERS AND LOWERED SEAS A COUPLE FEET AS WELL. LATEST MARINE MOS GUIDANCE AND ETA/RUC FORECASTS HOLD WINDS BELOW SCA CONDITIONS OVER MUCH OF THE GULF. WILL CARRY SCA OVER THE BAYS AND NEARSHORE WATERS AS BETTER MIXING WILL TAKE PLACE NEAR LAND AND 20KT WINDS ARE EXPECTED OVER THESE WATERS THIS AFTERNOON. MADE ADDITIONAL CHANGES TO THE OFFSHORE WATERS FORECAST TO HOLD THEM BELOW SCA LEVELS UNTIL SUN NIGHT WHEN IT APPEARS A TYPICAL SUMMERTIME NOCTURNAL ENHANCEMENT OF WIND SPEEDS OVER THE GULF WILL OCCUR AND CAUSE THEM TO INCREASE TO SCA LEVELS. .CRP WATCHES/WARNINGS/ADVISORIES...SCA FOR BAY AND NEARSHORE WATERS. $$ 92/TR tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 1040 AM EDT SAT APR 17 2004 WILL OPT TO UPDATE THE GOING FCST FOR SOME MINOR FIRST PERIOD CHANGES. CF TO MOVE DOWN ACRS SRN CANADA TODAY. 06Z TAQ RUC/12Z 40KM RUC SHOW TEMPS TO GET UP INTO THE U40S-M50S TODAY WITH S-SW SFC WINDS AT 5-15G20 KTS. T1MAX TEMPS ARE IN THE U60S-M70S TODAY AND LOOK WAY BETTER THAN RUC TEMPS BASED ON LATEST MESONET OBS. FEW TWEAKS TO FIRST PERIOD TEMPS/WINDS BASED ON THIS DATA. LOW-LVL MSTR TO INCREASE ACRS THE FA BY LATER TODAY (WITH SOME H85 FGEN AS WELL). SOME MID-LVL MSTR TO AFFECT THE NRN TIER ZONES BY LATE TODAY. CAPES TO BE AOB 500 J/KG ACRS THE FA TODAY. PW VALUES ACRS THE FA LOOK TO BE AOB 1.1". RUC SHOWS MOCLDY SKIES ACRS THE FA TODAY WITH SCT PCPN ACRS THE NRN TIER ZONES THIS AFTERNOON. QPF TO BE AOB 0.25" ACRS THE FA INTO THIS EVENING. SAT PIX SHOW PLENTY OF CLDS SPREADING ACRS THE FA FROM THE WEST ATTM. BUFCAN/88D MOSAIC/LTG DATA SHOWS SOME CONVECTION MOVING DOWN ACRS SRN CANADA ATTM. ATMOSPHERE APPEARS TO BE MODERATELY TO STRONGLY SHEARED ACRS THE FA WITH NOT MUCH IN THE WAY OF REAL INSTABILITY THOUGH...SO ANY CONVECTION EXPECTED TO BE NON-SVR TODAY. LEAST CHC FOR ANY PCPN TODAY STILL APPEARS TO BE ACRS SRN VT...WITH THE BEST CHC BEING ACRS MUCH OF NY STATE. GOING FCST OF SOME PCPN LINGERING INTO EARLY TONITE LOOKS OK FOR NOW. REST OF CHANGES TO GOING FCST FOR TODAY AND TONITE ARE COSMETIC...AND NO CHANGES TO THE GOING FCST BEYOND TONITE FOR NOW. WRK ZONES OUT UNDER ALBWRKCWF. FINAL ZFP/GRIDS BY AROUND 11 AM. MURRAY .PREV DISCUSSION...FROM 251 AM EDT... FCST CONCERNS ARE TEMPS AND CHCS FOR PRECIP THRU TONIGHT. WATER VAPOR SHOWS BUILDING MID/UPPER LVL RIDGE ACRS NE CONUS WITH S/W ENERGY OVER THE CENTRAL PLAINS ATTM. THIS WAVE COMBINED WITH FAVORABLE JET DYNAMICS AND SFC CONVERGENCE IS ENHANCING TS ACTIVITY OVER IOWA AND MN THIS MORNING. THIS WL PROVIDE OUR CWA WITH A CHC FOR PCPN OVER THE WEEKEND. OTHERWISE...BASED ON VAPOR TRENDS AND RAOB DATA MODELS INITIALIZED WELL WITH S/W ENERGY AND BUILDING RIDGE ACRS NE CONUS. ALL MODELS ARE HANDLING LLVL WAA OVER OHIO VALLEY AND WESTERN NY THIS MORNING BASED ON 85H RAOB DATA. 85H TEMPS NEAR 12C ACRS MI YESTERDAY SUPPORTED HIGHS WELL INTO THE 70S...EXPECT THESE TEMPS ACRS OUR FA TODAY. IR SAT PIC SHOWS SOME MID/HIGH LVL CLOUDS SPILLING OVER RIDGE INTO OUR WESTERN CWA THIS MORNING WITH MSS TEMP AT 44F. MEANWHILE...CPV AND POINTS EAST TEMPS HAVE FALLEN INTO THE U20S/L30S WITH MAINLY CLR SKIES. TODAY-TONIGHT...MID/UPPER LVL RIDGE MVS THRU CWA TODAY AS S/W ENERGY AND ASSOCIATED JET DYNAMICS APPROACHES OUR FA THIS AFTN/EVENING. WITH 925MB TEMPS NEAR 16C AND PROGGED 85H TEMPS NEAR 10C AND SW SFC FLOW WL MENTION TEMPS 3 TO 5 DEGREES ABOVE GUIDANCE. THIS COMBINED WITH UPSTREAM TEMPS IN THE 70S/L80S WL MENTION TEMPS WELL INTO THE 70S MOSTLY LOCATIONS TODAY. NEXT QUESTION IS PRECIP AND CHC FOR TS THIS AFTN/EVENING. MODELS TAKE S/W RESPONSIBLE FOR CONVECTION ACRS IOWA THIS EVENING AND RACE IT TOWARD OUR CWA THIS AFTN...ALONG WITH A WEAK SFC FRNT. WL INCREASE POPS TO LIKELY THIS AFTN...ESPECIALLY WESTERN CWA BASED ON LATEST GUIDANCE AND UPSTREAM RADARS. WL KEEP CHC POPS ACRS CPV...FEELING STRONG LLVL DOWNSLOPING FLOW WL LIMIT PRECIP CHCS. ALSO...WESTERN CWA WITH BE UNDER FAVORABLE ULVL DIVERGENCE WITH DUAL JET STRUCTURE OVER NE AND STRONG PVA WITH 5H VORT MOVING THRU OUR FA. CONVECTIVE PARAMETERS LOOK MARGINAL FOR TS...BUT GIVEN SW'S AROUND -1...SFC BASED CAPES NEAR 300 J/KG...AND TTS IN THE M50S WL CONT TO MENTION CHC FOR TS. FEEL GFS CONTS TO HAVE CONVECTIVE FEEDBACK PROBLEMS WITH QPF FCST AND ENHANCEMENT OF 5H VORTS...THEREFORE WL LEAN TOWARD MESO-ETA QPF FIELDS. TONIGHT...RW/TRW WEAKEN ACRS OUR FA AS BEST ULVL DYNAMICS AND MOISTURE LIFTS INTO CANADA. WL CONT TO MENTION CHC POPS THIS EVENING WITH SOME CLRING LATE AS NVA/SUBSIDENCE BUILDS INTO FA. SUNDAY-MONDAY...WEAK SFC FRNT STALLS ALONG THE PA/NY BORDER...THEN SLOWLY LIFTS BACK TOWARD FA LATE SUNDAY INTO MONDAY. BEST LIFT/MOISTURE ASSOCIATED WITH STRONG WAA STAYS WEST AND NORTH OF CWA...THEREFORE WL KEEP MOST OF FCST AREA DRY ON SUNDAY. MEANWHILE... GFS IS MUCH MORE AGGRESSIVE WITH 5H VORT AND ASSOCIATED LIFT/MOISTURE ACRS OUR WESTERN FA SUNDAY AFTN. WL MENTION CHC POPS WESTERN CWA/NNY ATTM ASSOCIATED WITH SFC WARM FRNT AND PROGGED MOISTURE/LIFT. PROGGED 85H TEMPS AROUND 5C AND NORTH SFC WINDS SUPPORT HIGHS BACK INTO THE 50S/L60S. MONDAY...CWA IS EXPECTED TO BE IN WARM SECTOR AGAIN AS SFC WARM FRNT LIFTS INTO SOUTHERN CANADA. STRONG LLVL WAA PUSHES 85H TEMPS TO 12C WITH 925MB TEMPS NEAR 15C ON MONDAY. THIS COMBINED WITH SW DOWNSLOPING FLOW...WL MENTION TEMPS BACK INTO THE 70S FOR MONDAY. NEXT S/W AND ASSOCIATED MOISTURE/LIFT APPROACHES WESTERN FA LATE MONDAY AFTN...THEREFORE WL MENTION CHC POPS WESTERN CWA. THE SFC COLD FRNT PUSHES THRU CWA MONDAY NITE INTO TUESDAY AND WL CONT TO MENTION CHC POPS ATTM. TUESDAY...STRONG LLVL CAA CONTS BEHIND SFC COLD FRNT AS HIGH PRES BUILDS INTO CWA FROM CANADA. THE COMBINATION OF WEAK 5H VORT AND LEFTOVER MOISTURE WL CONT TO MENTION MORNING RW...OTHERWISE DECREASING MOISTURE SHOULD ALLOW FA TO SEE SOME SUN BY AFTN. PROGGED 85H TEMPS NEAR 2C SUPPORT HIGHS ONLY INTO THE 50S ATTM. EXTENDED...HIGH PRES WL CONT ACRS FA ON WEDS AS SFC FRNT STALLS ACRS THE MID ATLANTIC STATES. THIS FRNT WL TRY TO PUSH BACK TOWARD FA LATE WEDS INTO THURS WL ANOTHER CHC FOR RW. OTHERWISE...TEMPS WL BE NORMAL WITH DRY CONDITIONS EXPECTED ON WEDS. CRNT FCST HAS THIS COVERED WELL...THEREFORE NO CHANGES ARE EXPECTED ATTM. TABER .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ vt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 100 PM CDT SAT APR 17 2004 .UPDATE... JUST A FEW CHANGES MADE TO GOING FORECAST THIS MORNING WITH LOW LEVEL BOUNDARY SLOW TO SAG THROUGH THE AREA THIS MORNING. MAIN TWEAK WAS TO INCREASE TEMPS SLIGHTLY BASED ON OBSERVATIONAL TRENDS AND TO SLOW NORTHEAST WIND SHIFT A BIT. SPC RUC-BASED ANALYSIS PAGE SHOWING INCREASING SURFACE BASED INSTABILITY ACROSS NORTHWEST INDIANA JUST TO SOUTH AND EAST OF MAIN SYNOPTIC BOUNDARY WITH SFC DEW POINTS UP INTO THE UPPER 50S AND LOWER 60S. DEEP LAYER SHEAR ACROSS THIS AREA IS RATHER MARGINAL ON ORDER OF 20-30 KNOTS BUT WILL KEEP AFTERNOON CHANCE POPS GOING ACROSS THIS AREA. UPDATED GRIDS AND ZONES HAVE BEEN SENT. .DISCUSSION REGARDING 400 AM ZONES/GRIDS: AFD DLAD DUE TO BADLY TIMED SVR WX. ANYWAY...GETTING CAUGHT UP NOW. ZFP IS OUT AND HAVE MADE DETAILED ADJUSTMENTS TO TEMP FCST OVR NXT 24 HRS. TEMPS WILL LIKELY BE A REAL PAIN TDY AS CONVECTIVE DEBRIS ERLY THIS MRNG WILL RETARD HEATING THIS MORNING...THEN AS THIS CLEARS OFF...CDFNT IN SRN WI WILL BE SAGGING SWD ACROSS FA...AIDED BY LK MI. LATEST SFC OBS SHOW THAT THIS FRONT HAS PROGRESSED FASTER THAT 00Z GUIDANCE HAD SUGGESTSD AND WILL LIKELY BE THROUGH MUCH OF NRN IL AND NWRN IN BY NOON. WILL WORD ZFP TO ACCENTUATE THIS TEMP DROP. FNT EXPECTED TO BCM STNRY OVR SRN PORTIONS OF FA BY THIS EVENING...THEN LIFT NWD AS A FAIRLY POTENT WARM FRONT BEGINNING THIS EVENING IN RESPONSE TO BACKING MID LVL FLOW AS MAIN S/W ENERGY LIFTS OUT OF SWRN U.S. THIS WILL RESULT IN RATHER SIG CYCLOGENESIS SUN-SUN NGT. SO...LO TEMPS TNGT WILL OCCUR THIS EVENING WITH TEMPS RISING MOST AREAS AS COOL MARINE LYR AIR OFF LK MI IS REPLACED BY INLUX OF TRPCL WARM SECTOR AIR. WILL HAVE LO CHC POPS IN FOR TNGT DUE TO PROXIMITY OF FNT...BUT BEST THETA E ADVECTION NOW APPREARS FOCUSED TO N OF RGN SO TSTMS MORE LIKELY OVR UPR MIDWEST TNGT. SUNDAY SHOULD BE DRY AND 20+ DEG ABV NORMAL. ETA FCST SHOWS H85 TEMPS ARND 18 C SUN AFTN IN ZONE OF STG FORCING AHD OF APCHG FRONT. DON'T SEE MUCH TO FOCUS ON FOR TSTM TRIGGER ON SUN AND LOW LEVELS OF FCST SOUNDINGS STRT TO DRY OUT SO...ALTHOUGH QUITE WARM...DEGREE OF INSTABILITY COMES INTO QUESTION. WILL HAVE CHC POPS IN FOR THUNDER AHD OF FNT SUN NGT BUT PROSPECTS FOR ANYTHING WIDESPREAD APPEAR WEAK ATTM. NDM && .AVIATION... THE INVERSION THIS MORNING WILL SLOWLY ERODE AWAY SOUTH OF THE FRONT OVER NORTHEAST ILLINOIS. CONVECTIVE AVAILABLE POTENTIAL ENERGY VALUES AROUND ORD USING TEMPERATURES SOUTH OF THE FRONT ARE AROUND 1956 J/KG. VISIBLE SATELLITE SHOWS SOME CUMULUS FORMING IN NORTHWEST INDIANA AND SOUTH OF CHICAGO. THIS IS ALONG A LAKE BREEZE BOUNDARY AS WELL. WILL NOT MENTION THUNDERSTORMS IN THE AFTERNOON TAFS BECAUSE MOST OF THE AIRPORTS FORECAST ARE THE COOL AIR SIDE OF THE FRONT. THERE IS STABILITY THERE. A LOW LEVEL WIND SHEAR HAS BEEN DROPPED FOR MDW BECAUSE THE WINDS AROUND 200 FEET HAVE DECREASED IN SPEED SINCE THE MORNING. USING THE AIRPORT AND OUR WSR88D DOPPLER RADARS AND PROFILER AND ACARS SOUNDINGS. USED THE MESO ETA AND WORKSTATION ETA FOR TONIGHTS FORECASTS. AFTER 06 UTC THE FRONT WILL MOVE NORTH AND SOUTH WINDS WILL PREVAIL. A VORTICITY MAXIMUM WILL MOVE ACROSS TO THE NORTH OF OUR FORECAST AREA. SOME POSITIVE VORTICITY ADVECTION MAY REACH NORTH CENTRAL ILLINOIS AFTER 03 UTC. WILL ADD THUNDERSTORMS VICINITY FOR RFD AFTER 03 UTC. WHW && .LOT...WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LK MI...NONE. $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 205 PM MDT SAT APR 17 2004 .SHORT TERM...(TONIGHT THROUGH MONDAY) SLIM POSSIBILITY OF CONVECTION THIS EVENING AND WIND TONIGHT AND SUNDAY ARE THE FORECAST CHALLENGES. CONVECTION...COPIOUS MID AND UPPER LEVEL MOISTURE APPROACHING THE HIGH PLAINS FROM THE SOUTHWEST TODAY. MODELS HINT AT AN ILL DEFINED SHORTWAVE EMBEDDED IN THE FLOW TO PASS OVER THE AREA THIS EVENING. PROFILER DATA ACROSS EASTERN NEW MEXICO THIS AFTERNOON SHOWS 500 MB WINDS BACKING. 18Z MESOETA RUN NO LONGER BREAKING OUT CONVECTION ALONG THE DRY LINE THIS EVENING. RUC FORECAST SOUNDING FOR HILL CITY SHOWS ANY STORMS THAT CAN INITIATE WILL BE VERY HIGH BASED...AT AROUND 600 MB...AND THUS THE CHANCE OF MEASURABLE PRECIPITATION ACTUALLY REACHING THE GROUND SEEMS REMOTE. STILL...GUSTY WINDS AND LIGHTNING WILL ACCOMPANY ANY OF THESE DRY THUNDERSTORMS IF THEY DEVELOP. SUNDAY...ALTHOUGH INSTABILITY WILL BE PRESENT EAST OF THE DRY LINE BETWEEN 15Z AND 18Z...THERE IS NO FOCUSING MECHANISM FOR CONVECTION AT THAT TIME OTHER THAN SURFACE HEATING AND THE DRY LINE ITSELF. AFTER 18Z THE DRY LINE SURGES EAST OF THE FORECAST AREA AND THE ATMOSPHERE STABILIZES. WILL NOT MENTION ANY THUNDER FOR SUNDAY. WIND...THERE WILL BE TWO WINDOWS WHERE WIND COULD POTENTIALLY MEET HIGH WIND WARNING CRITERIA BASED ON ETA BUFKIT MIXING HEIGHTS. THE FIRST WILL BE TONIGHT AS 850 MB WINDS INCREASE TO 40 TO 60 KTS ACROSS THE FORECAST AREA. IN WESTERN ZONES...TIME HEIGHT CROSS SECTIONS SHOW DOWNWARD MOTION INCREASING AFTER 03Z AND CONTINUING THROUGH THE NIGHT...WHILE IN THE EAST STRONG DOWNWARD MOTION INDICATED THROUGH 06Z...BUT THEN ETA ACTUALLY HAS LIFT AFTER 06Z. NORMALLY RELIABLE HIGH RESOLUTION RUC20 HAS SUSTAINED WINDS AT 20-30KT CENTERED AROUND 03Z. WILL MONITOR LATEST RUC FORECAST TRENDS...BUT FEEL AREA WILL STAY JUST BELOW ADVISORY CRITERIA TONIGHT. SUNDAY...15Z-21Z APPEARS TO BE THE CRITICAL TIME PERIOD WHERE MOMENTUM TRANSFER POTENTIAL WILL BE FROM 50-55 KTS ACROSS THE ENTIRE AREA. MOS GUIDANCE...OF WHICH THE GFS IS THE STRONGEST...HAS SUSTAINED WINDS OF 35-40 KTS AT ALL MOS SITES EXCEPT HLC (32 KTS). THUS...SUSTAINED AND GUST CRITERIA FOR A HIGH WIND WATCH/WARNING ARE MET. AFTER MUCH DEBATE AND COORDINATION...HAVE DECIDED UPGRADING TO A HIGH WIND WARNING WILL BETTER COMMUNICATE TO THE PUBLIC THE POTENTIAL FOR STRONG WINDS THAN REPLACING THE CURRENT ADVISORY WITH A WATCH. && .LONG TERM...(TUESDAY THROUGH SATURDAY) MODELS IN FAIRLY GOOD AGREEMENT ON TIMING OF SHORTWAVE FOR MONDAY NIGHT AND TUESDAY MORNING. BEST COMBINATION OF MOISTURE/INSTABILITY AND LIFT WILL BE OVER EASTERN ZONES WHERE CHANCE POPS WILL RESIDE. EXPECT CONVECTION TO END BY 12Z IN WESTERN ZONES AS SUBSIDENCE QUICKLY DEVELOPS BEHIND THE UPPER TROUGH AXIS AND WEST WINDS BEHIND SURFACE TROUGH DRY THE LOWER LEVELS. CAPE AND SHEAR FORECASTS FROM THE ETA SUGGEST STORMS WILL STAY BELOW SEVERE LIMITS. ETA 850 MB TEMPERATURES SUPPORT HIGHS IN THE MIDDLE 60S NORTH TO LOWER 70S SOUTH. SHORTWAVE RIDGE WILL TRAVERSE THE CENTRAL PLAINS TUESDAY NIGHT THROUGH WEDNESDAY WITH NO PRECIPITATION EXPECTED. LEE TROUGH WILL DEVELOP OVER EASTERN COLORADO AND SURFACE HIGH NEAR KANSAS CITY. SOUTHEAST SURFACE WINDS WILL BEGIN TO ADVECT MOISTURE INTO THE FORECAST AREA. REAL EXTENDED FORECAST PROBLEM LIES IN THE EVOLUTION OF THE NEXT SYSTEM WEDNESDAY NIGHT THROUGH FRIDAY. THE OPERATIONAL GFS HAS PUT TOGETHER AT LEAST 2 RUNS WITH A CUT OFF 500 MB LOW FORMING OVER CENTRAL COLORADO AND SLOWLY MIGRATING EASTWARD. HOWEVER...THERE IS VERY LITTLE AGREEMENT AMONG GFS ENSEMBLE MEMBERS AND OTHER MEDIUM RANGE MODELS SUCH AS THE ECMWF AND THE GLOBAL CANADIAN. SINCE CONFIDENCE IN ANY PARTICULAR SOLUTION IS QUITE LOW AT THIS TIME...PREFER TO STAY THE COURSE WITH CONSERVATIVE POPS AND NOT MAKE ANY MAJOR CHANGES TO THE INHERITED FORECAST. $$ .GLD WATCHES/WARNINGS/ADVISORIES... KS...HIGH WIND WARNING SUNDAY. NE...HIGH WIND WARNING SUNDAY. CO...RED FLAG WARNING FOR KIT CARSON AND CHEYENNE COUNTIES THROUGH 9PM TONIGHT. FIRE WEATHER WATCH AND HIGH WIND WARNING FOR EAST CENTRAL COLORADO SUNDAY. && $$ JDK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 PM EDT SAT APR 17 2004 .DISCUSSION... 12Z RAOBS/LATEST WV LOOP AND RUC ANALYSIS SHOW SPLIT FLOW ACRS NAMERICA WITH FA NR THE SHARP CONFLUENCE ZN BTWN THE BRANCHES...ON TOP OF SRN BRANCH RDG AND BELOW NRN BRANCH TROF CENTERED OVER HUDSON BAY. CWA DOMINATED BY DRY NW FLOW IN ADVANCE OF 1027MB SFC HI PRES NR LK WINNIPEG. VERY COLD AIR NOTED IN CAN (H5 TEMP -42C AT CHURCHILL) WITH PLENTY OF INSTABILITY CU IN ONTARIO...BUT MORE WNW FLOW AT H85/ZONAL FLOW ALF TENDING TO KEEP THE MAJORITY OF THIS AIR TO THE N. TEMPS QUITE A BIT WARMER TO THE S...H85 TEMPS AOA 20C OVER THE SCNTRL PLAINS. 110KT H3 JET MAX EMBEDDED WITHIN CONFLUENCE ZN/ABV SHARP LARGE SCALE THERMAL GRADIENT NOTED OVER INL AT 12Z... AND AN AREA OF MID/HI CLD NOTED OVER THE NRN PLAINS IN RRQ OF THIS FEATURE IS SPREADING EWD TOWARD THE FA. BUT VERY DRY AIR NOTED OVER THE PLAINS (H85-7 DWPT DEPRESSIONS AS HI AS 20-30C FM TX INTO SD AND MOST PWAT WELL BLO ONE INCH) LIMITING PCPN AND EVEN CLD COVER TO THE N OF SFC-H85 WARM FNT IN THE CNTRL PLAINS. HOWEVER...SOME SFC DWPTS IN THE 60-65 RANGE NOTED OVER ERN KS/MO TO THE S OF THE WARM FNT. THE SFC-H85 WARM FRONTOGENESIS IS IN RESPONSE TO PRES FALLS IN THE LEE OF THE CENTRAL ROCKIES ASSOCIATED WITH DEEP SRN BRANCH TROF OVER THE SW CONUS. 110KT H3 JET MAX NOW LIFTING OUT OF THE TROF...WITH 12HR H3 HGT FALLS NEAR 150M AT LAS VEGAS. NMRS FCST CONCERNS THIS PACKAGE FOR TNGT INTO MON AS SW TROF FCST TO LIFT OUT TOWARD THE GRT LKS. CONCERNS INCLUDE TIMING/EXTENT/AND AMOUNT OF PCPN...PSBL FLOODING...AND EVEN SVR WX THREAT. FOR TNGT...MODELS SHOW SFC HI SLIDING E ACRS ONTARIO. AS ISENTROPIC LIFT OVER LINGERING COOL DRY AIR INCREASES TNGT AS SHOWN ON ETA FCST 295-305K SFCS...DEEPER RH FCST TO EXPAND OVER THE FA...AND BOTH ETA/GFS PAINT QPF AFTER MIDNGT. MOISTENING WL BE ENHANCED AS RRQ OF H3 JET MAX IN UPR CONFLUENCE ZN/ENHANCED UPR DVGC SHIFTS OVHD. H85 FRONTOGENESIS DEPICTED OVER WI IN CONFLUENCE AT NOSE OF DVLPG 50KT H85 JET. ALTHOUGH VERY CONCERNED THAT MODELS HAVE BEEN TRYING TO MOISTEN UP ATMOSPHERE TOO QUICKLY RECENTLY (CONSIDERING VERY DRY AIR OVERALL TO THE SW)...HAVE OPTED TO RETAIN LIKELY POPS OVER THE N AND CATEGORICAL OVER THE S (CLOSER TO BETTER FRONTOGENESIS) AFTER MIDNGT DUE TO IMPRESSIVE DYNAMICS AND POTENTIAL FOR 60-65 SFC DWPTS OBSVD IN ERN KS/MO TO LIFT AND SPREAD NE. BUT RESTRICTED MENTION OF TSRA TO ONLY THE SRN TIER ZNS WHERE ETA SHOWS SSI APRCHG 0 TOWARD 12Z... AS BETTER UVV ALONG FRONTOGENESIS TO THE S SHOULD INTERCEPT LIMITED MSTR. BOTH GFS/ETA SHOW HIER QPF APRCHG 0.50 INCH REMAINING OVER WI CLOSER TO BETTER FRONTAL FORCING/MSTR INTERCEPT. BOTH ETA/GFS SHOW UPR TROF LIFTING NE FM THE SW TMRW WITH SFC LO FM THE PLAINS RIDING NE...BOTH ETA/GFS NOW IN GOOD AGREEMENT SHOWING SFC LO OVER SCNTRL MN AT 00Z MON. CONTD ISENTROPIC LIFT AHEAD OF APRCHG SFC-85 WARM FNT WL KEEP -SHRA ARND ALL DAY...BUT APPEARS THE BEST UPR DVGC IN JET COUPLING BTWN APRCHG 120KT JET/DEPARTING 140KT H3 JET MAX NEAR JAMES BAY WL REMAIN W OF FA DURG THE DAY. IN FACT...BOTH ETA/GFS HINT AT DRY SLOTTING DURING THE AFTN FOLLOWING PASSAGE OF H85 WARM FNT. SVR THREAT TMRW APPEARS WL BE ELEVATED IN NATURE BECAUSE ETA SHOWS SFC WARM FNT JUST APRCHG MNM AT 00Z AND FUELED BY ARRIVAL OF HIER H85 TEMPS/STEEPENING LAPSE RATES FM THE SW. NGM BLOWS SFC WARM FNT THRU FA EARLY IN THE DAY...BUT SINCE THIS MODEL IS IGNORANT OF LKS (AND COLDER LK WATER/MODIFIED AIRMASS)... FAVOR THE ETAS SLOWER NWD PROGRESSION OF THE SFC BNDRY/COOLER NR SFC TEMPS EVEN THOUGH THE H85 WARM FNT WL PUSH MORE RPDLY ACRS THE FA WITH 50KT SW FLOW FCST AT THAT LVL. ETA F36 SDNG FOR IWD (00Z MON) SHOWS NR 2000 J/KG CAPE LIFTING FM H85 NEAR BACK EDGE OF DEPARTING MSTR...TO THE S OF H85 WARM FNT. ALTHOUGH ETA FCST H85 DWPT NEAR 15C MAY BE A BIT ON THE HI SIDE CONSIDERING UPSTREAM DRY AIR...DYNAMICS AND EVEN LESS INSTABILITY THAN FCST EXPLICITLY BY MODEL MORE THAN ENUF TO GENERATE TSRA. CONVECTIVE UPDRAFTS WL BE ENHANCED BY CLASSIC CLOCKWISE TURNING HODOGRAPH IN STRG WAD PATTERN JUST N OF WARM FNT...SO LARGE HAIL DEFINITELY A THREAT FM ELEVATED TSRA. SPC FCSTG ENTIRE FA IN SLGT RISK FOR SVR TSRA ON SUN. PREFER SOMEWHAT LOWER ETA QPF OVER GFS FCST DUE TO APRNT CONVECTIVE FEEDBACK IN GFS AND LACK OF BETTER JET FORCING. MODELS SHOW UPR JETS COMING INTO BETTER POSITION TO INCRS JET COUPLING/UPR DVGC/FRONTOGENESIS IN DEFORMATION ZN OVER THE WRN ZNS AS SFC/H85 LOW PUSH NE INTO CNTRL LK SUP AFTER MIDNGT. ALTHOUGH THE STORM SYS APPEARS WL BE MOVING QUICKLY THEN AS SHRTWV PICKING UP NEWD SPEED ON NW FLANK OF SERN RDG...ETA FCST QPF APRCHG 2 INCHES AT IWD AND VIGOROUS DYNAMICS OVER DEFORMATION ZN CNVGC HINTS AT POTENTIAL FOR HVY RA. ALTHOUGH MODEL QPF MAY BE BIASED UPWARD BY OVERESTIMATE OF MSTR...1-3 INCHES OF SWE REMAINS IN THE SN PACK OVER THE HIER TERRAIN FM ONTONAGON COUNTY-NEWD INTO KEWEENAW COUNTY AND OVER THE HURON MOUNTAINS. HAVE OPTED TO ISSUE FLOOD WATCH FOR SUN NGT-MON FM MQT-KEWEENAW-IWD GIVEN BETTER POTENTIAL FOR HEAVY RA AND/OR RAPID MELT OF LINGERING SN PACK AS SFC TEMPS/DWPTS RISE SUN EVNG WITH APRCH OR PASSAGE OF SFC WARM FNT. COORDINATION WITH RFC FOR QPF ARND 1.25" AND SN MELT INDICATES MOST RIVERS IN THIS AREA WL REACH AOA FLOOD STAGE. QUICK RESPONDING RIVERS OVER THE KEWEENAW WOULD BE MOST LIKELY TO SEE RAPID RISES IN RIVER LEVEL. FARTHER SE UNDER DRY SLOT AND IN THE WARM SECTOR...SCT SHRA/TSRA WL REMAIN A THREAT. VIGOROUS DRYING IN WARM SECTOR MAY MINIMIZE SVR TSRA THREAT. ALTHOUGH POPS WL INCRS OVERNGT INTO MON AS WHOLE LO AND COLD FNT PUSH EWD...THREAT FOR HVY RA WL DIMINISH WITH COLLAPSE OF COUPLED JET AND FASTER SPEED OF LO/COLD FNT. GFS/ETA SHOW SHRTWV/SFC LO TRENDING TO DEPART FA FASTER ON MON...WITH UPR DYNAMIC SUPPORT EXITING EVEN ERY BY 18Z. ALTHOUGH THERE MAY BE SOME LINGERING -SHRA IN CYC FLOW ESPECIALLY OVER THE HIER TERRAIN...ADDITIONAL PCPN ON MON SHUD BE NEGLIGIBLE. GFS/ETA FCST H85 TEMPS/H100-85 THKNS SUG POTENTIAL FOR CHG TO SN IS SMALL ESPECIALLY CONSIDERING COLDER AIR PUSHING IN DURING DIURNAL MAX AND WITH DECAYING DYNAMICS. THEN CLRG LATE IN DAY ON MON/MON NGT WITH ARRIVAL OF SFC RDG/DRIER AIR. EXPECT DRY DAY ON TUE AS SHRTWV RDG/SFC HI IN RATHER FAST ZONAL FLOW BEHIND DEPARTING SHRTWV DOMINATES. GIVEN TREND TOWARD MORE ZONAL FLOW AND FASTER MODERATION OF COLD AIR RETURNING BEHIND MON SHRTWV...WL FOLLOW ECMWF GUIDANCE HIER H85 TEMPS REACHING 3C LATE IN THE DAY...WHICH SUPPORTS TMAX CLOSE TO 60 OVER THE INTERIOR WEST AWAY FM LK MODERATION. BUT CLDS WL INCRS LATER IN THE DAY AS SHRTWV NOW IN THE ERN PACIFIC AND EMBEDDED IN THE QUICK WLY FLOW FOLLOWS RIGHT BEHIND THE RDG. PREVIOUS FCST HAD SHRA HOLDING OFF UNTIL WED NGT...BUT WL ACCELERATE ARRIVAL OF SHRA CHCS TO LATE TUE NGT/WED. CONSIDERING TREND TOWARD A MORE ZONAL FLOW...THIS FCST SEEMS RSNBL PER NCEP GUIDANCE. 00Z EXTENDED MODELS SHOWING SGNFT CHGS FM YDAYS RUNS WITH CUTOFF UPR LO IN THE SRN BRANCH FLOW FORMING IN THE SRN PLAINS LATE THIS WEEK AND UPR GRT LKS UNDER THE INFLUENCE OF THE MORE PROGRESSIVE NRN BRANCH FLOW. PER NCEP GUIDANCE WL LEAN TOWARD THE 06Z GFS FCST FOR EXTENDED FCST DETAILS. 00Z GFS ENSEMBLE MEAN IN SUPPORT OF NEW TRENDS...SO HAVE MADE MAJOR CHGS TO PREVIOUS EXTENDED FCST. BLDG HI PRES RDG IN SRN CAN ON THE SRN EDGE OF THE MORE ZONAL FLOW ACRS CAN AND N OF FALLING HGTS IN THE SRN PLAINS BRINGS DRY WX FOR THU THRU SAT. ALTHOUGH 06Z GFS INDICATES A CHC OF SHRA ON SAT WITH SOME PHASING BTWN NRN AND SRN BRANCH TROFS AND SFC LO LIFTING NEWD INTO THE GRT LKS... WL GO WITH FARTHER S POSITION DEPICTED ON 00Z GFS ENSEMBLE MEAN/NCEP HAND DRAWN PROGS AND CALL SAT DRY. COORDINATED WITH APX/GRB/DLH/NCRFC. && .MQT WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH MIZ001>005-009-084 && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 305 PM EDT SAT APR 17 2004 .SHORT TERM... ONCE AGAIN THE QUESTION BECOMES WHERE THE CONVECTION WILL DEVELOP...THEN ONCE THAT HAPPENS...WHERE DOES IT GO? THE BEST SHOT GRR HAS FOR CONVECTION WOULD BE LATER TONIGHT AS THE WARM FRONT PUSHES NORTH THROUGH THE CWA. WHAT THIS QUESTION REALLY IS RELATED TO IS DOES CONVECTION DEVELOP OVER NRN IL/IN AND MOVE NE INTO LOWER MICHIGAN THIS EVENING AS THE FRONT TURNS BACK NORTH OR DO WE HAVE TO WAIT FOR THE CONVECTION FORM MN/WI TO ROLL INTO LOWER MICHIGAN AFTER 06Z OR SO? THE NEXT ISSUE IS HOW WARM IT GETS SUNDAY...WITH ENOUGH SUNSHINE...LOWER 80S ARE MORE THAN REACHABLE OVER A GOOD PART OF THE SOUTHERN AND CNTL CWA. SUNDAY NIGHT THERE IS A 75KT 850MB JET OVER SW LWR MI. WILL THERE BE CONVECTION WITH THAT? FINALLY THERE IS THE ISSUE OF CONVECTION ON THE COLD FRONT MONDAY. LITTLE QUESTION ABOUT CLEARING LATER MONDAY NIGHT AS THE CANADIAN POLAR HIGH MOVES IN BEHIND THE FRONT AFTER 06Z. FOR TONIGHT...MY SPIN ON THIS IS THE CONVECTION WILL FIRE WHERE THE LOW LEVEL JET INTERSECTS THE WARM FRONT OVER NRN IA/SRN MN/WRN WI EARLY THIS EVENING. FROM THERE IT WILL TRACK ESE ALONG THE WARM FRONT...WHICH WILL BE MOVING NORTHWARD. THERE IS A NARROW RIBBON OF 10 TO 12C 850MB DEWPOINTS THIS WILL SUPPLY THAT COMPLEX WITH PLENTY OF MOISTURE TO FEED ON. THE WATER VAPOR LOOPS SHOW A NICE PLUME OF MOISTURE HEADING NORTHEAST FROM MEXICO AND LOWER CALIFORNIA AT 18Z. THAT TOO IS HEADED FOR THE WARM FRONT WHICH WILL THEN INTERACT WITH THE ENTRANCE REGION TO A 120 KNOT JET SEGMENT OVER WESTERN ONTARIO/EASTERN MANITOBA THIS EVENING. AS FOR THE POTENTIAL FOR CONVECTION TO DEVELOP ON THE WARM FRONT SOUTH OF MICHIGAN THIS EVENING...LIKE BETWEEN CHI AND SBN... I AM THINKING NO. LAPS SOUNDING AND RUC SOUNDINGS SHOW A DECENT CAP IN PLACE AND THE ETA SOUNDING SUGGEST IT WILL REMAIN IN PLACE THIS EVENING. SO OUR ONLY REAL SHOT IS FOR THE CONVECTION FROM THE UPPER MID WEST TO ROLL IN ALONG THE WARM FRONT. AS FOR SEVER POTENTIAL FROM THAT...GIVEN THE SURFACE INVERSION FORECAST BY THE MODELS...SEEMS IT WOULD HAVE TO BE ELEVATED. THERE WILL BE A LOT OF ENERGY FOR THESE STORMS THOUGH SINCE THE CAPE IS NEAR 2000 J/KG AND 850MB LI VALUES ARE NEAR -6C. LARGE HAIL WOULD BE THE MOST LIKELY SINCE WINDS ARE NOT THAT STRONG THROUGH 10000 FT (NO WIND OVER 40 KNOTS). THERE IS SOME MID LEVEL DRY AIR THOUGH AND GIVEN THE ELEVATED CAPE...I CAN NOT BE RULED OUT. BOTTOM LINE TO THIS IS WHAT CONVECTION THERE WILL BE WILL MOSTLY BE NORTH OF MKG TONIGHT. IT WILL LIFT NORTH SUNDAY AND THAT WILL BRING A LOT OF VERY DRY AIR NORTH DURING THE DAY. BY LATE AFTERNOON OR EVENING THE 850MB LI RISES TO +8C! THE 850MB DEW POINTS PLUNGE BELOW 0C! THERE IS A VERY STRONG CAP TOO. SO WITH THE WARM FRONT TO THE NORTH OF THE GRR CWA AND THAT VERY WARM DRY 850MB AIR COMING UP FROM THE SOUTH...I SEE SUNDAY AS BECOMING MOSTLY SUNNY BY MID AFTERNOON WITH TEMPERATURES RISING INTO THE LOWER 80S. THAT IS BASED ON THE 1000/850MB THICKNESS AND THE 1000/925MB THICKNESS OFF THE ETA. SUNDAY NIGHT WE COULD SEE SOME ISOLATED STORMS LATE AS THE 300MB TROUGH MOVES INTO LOWER MICHIGAN AFTER 06Z LOWERING HEIGHTS AND COOLING OFF THE MID LEVELS. STILL SW MICHIGAN IS VERY STRONGLY CAPED. GOOD THING TOO...THERE IS 75KT OF WIND AT 850MB AND 50KNOTS AT 925MB. IF ANY CONVECTION DID GET GOING...THERE WOULD SURELY BE DAMAGING WINDS. WE WILL NEED TO MONITOR THIS. MONDAY THE FRONT COMES THROUGH THE WESTERN CWA IN THE MORNING AND EASTERN CWA EARLY IN THE AFTERNOON. MOISTURE IS LIMITED BY THEN BUT IT IS A STRONG FRONT AND THERE IS SFC BASED LI'S BELOW ZERO. SO I WILL CARRY CHANCE POP INTO THE EVENING FOR THAT BUT MORE THAN LIKELY IF THERE IS ANYTHING AT ALL...IT WILL BE EAST OF GRR IN THE LATE MORNING OR EARLY AFTERNOON. MUCH COOLER AIR MOVES IN MONDAY NIGHT. THAT WILL LIKELY HAVE A PERIOD OF LOW CLOUDS WITH IT AS THE COLD AIR MIXES WITH THE WARMER AND MORE MOIST AIR AHEAD OF IT WITH CYCLONIC CURVED FLOW BEFORE 06Z. AFTER THAT SKIES WILL CLEAR AS THE POLAR HIGH MOVES IN. THAT WILL ALLOW TEMPERATURES TO FALL INTO THE 30S BY MORNING. TUESDAY SHOULD BE MOSTLY SUNNY AND PEASANT. .LONG TERM... THE LONG TERM PORTION OF THE FORECAST WILL FEATURE A RELATIVELY PROGRESSIVE PATTERN ACROSS THE GREAT LAKES. EARLY TUE NIGHT...THE WEATHER WILL START OUT QUIET ACROSS THE CWFA. A WAVE OUT TO OUR SW WILL MAKE A RUN AT THE GREAT LAKES LATE TUE NIGHT. WAA OUT AHEAD OF THE WAVE WILL PRODUCE A THREAT OF SOME SHOWERS AND THUNDERSTORMS... ESPECIALLY OVER SOUTHERN AREAS. THIS WAVE WILL TRACK ACROSS THE REGION DURING THE DAY ON WED...BRINGING A SFC LOW RIGHT OVERHEAD AND CONTINUING THE CHC OF SHOWERS AND THUNDERSTORMS. THIS SYSTEM WILL PASS EAST OF THE AREA ON WED NIGHT AND ANY PCPN THAT IS LEFT OVER WILL DIMINISH. BEHIND THE WED SYSTEM...WEAK UPPER RIDGING AND A SFC HIGH WILL BUILD OVER THE STATE ON THU. THIS WILL BRING DRY WEATHER BACK TO THE AREA TEMPORARILY. THE WEATHER FOR NEXT FRI AND SAT IS STILL QUITE UNCERTAIN AS THE MEDIUM RANGE MODELS HAVE SOME DIFFERENT SOLUTIONS FOR THE END OF THE WEEK. A HIGH AMPLITUDE UPPER TROUGH/CLOSED UPPER LOW IS EXPECTED TO DIG OVER THE SW U.S. BY THU. THIS FEATURE IS THEN EXPECTED TO EJECT NE. THE TREND OF THE MAJORITY OF THE MODELS IS TO ALLOW THIS FEATURE TO BE A LITTLE MORE PROGRESSIVE MOVING ENE. WE WOULD THEN BE ON THE NRN EDGE OF THIS SYSTEM IN THE WAA REGION. PER COLLABORATION WITH SURROUNDING OFFICES...WE WILL KEEP PCPN MENTIONED FOR FRI FOR NOW AND GO DRY SAT. IF THIS SYSTEM STAYS FAR ENOUGH SOUTH...WE COULD MISS OUT ON IT TOTALLY AND REMAIN DRY. && .GRR...WATCHES/WARNINGS/ADVISORIES...NONE. && WDM NJJ mi SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 321 PM CDT SAT APR 17 2004 .SHORT TERM...THROUGH 12Z TUE. MANY CONCERNS THIS CYCLE RELEGATED TO STRONG INCOMING UPR TROF OVR CA. AT THE SFC...LEE SIDE CYCLOGENESIS UNDERWAY OVR ERN CO WITH DVLPG WARM FRONT ALG KS/NE BORDER AND LIFTING NWD. WARM SECTOR CONTS TO MOISTEN BUT AGAIN QUITE SHALLOW AND APPEARS INSUFFICIENT TO SPRT CONVN ALG WARM FRONT LTR THIS AFTN OR EVENING AS IT MIXES N INTO SD. OTHERWISE WAITING TO SEE HOW DRYLINE OVR WRN KS AND SW NE DEVELOPS. DIFFUSE LEAD SW EMBEDDED WITHIN MID LVL MSTR PLUME ALG SRN EDGE OF INTENSIFYING UPR JET MAY LEAD TO ISOLD DVLPMNT YET LT THIS AFTN BUT GIVEN ELIMINATION OF POPS THAT AREA...WILL NOT REINTRODUCE AT THIS POINT UNLESS SOMETHING MORE DEFINITIVE ARISES BEFORE ZONE ISSUANCE. ATTENTION THEN TURNS TO A PROBLEMATIC SUNDAY. BIGGEST DILEMMA IS HOW BEST TO HANDLE EJECTING SFC/UPR SYSTEM AND STRONG WINDS BEHIND SURGING DRYLINE IN THE AFTN. ALIGNMENT OF WELL MIXED DEEP BNDRY LYR FLOW POST DRYLINE SPRTS SEVERAL HOURS OF SUSTAINED 35-40KT WINDS W/PROBABLE GUSTS TO 50KTS GIVEN 20KM FSL DEV RUC OUTPUT. GIVEN SIGNAL FOR HIGH WIND EVENT AND CLOSE ANALOG TO APRIL 16 2002 EVENT AND AFTER COORDINATION CALLS W/LBF AND GLD...FEEL ITS PRUDENT TO UPGRADE TO A WARNING AT THIS POINT. OTHERWISE CONVN STILL LOOKS POSSIBLE...ESP ERN THIRD AS DRYLINE COLLAPSES DOWN THERE TWD 3 PM W/BLOW TORCH WEST OF THERE GIVEN LL THERMAL RIDGE IN PLACE AND DEEP MIXED LYR WEDGE UNDERNEATH UPR TROF. GUIDANCE TEMPS UNREALISTIC SAVE MAV NUMBERS AND LARGELY IGNORED. AFT THAT...CAA SURGE TAKES PLACE SUN NIGHT BEHIND DEPARTING SYS AND MAKES FOR QUITE MON IN THE INTERIM. HWVR SHRT LIVED AS NXT UPSTREAM TROF STEAMING SE THROUGH NEPAC AND PROGGED TO MAKE LANDFALL MON AM. TRACK OF MID LVL TROF AND ASSOCD HGT FALLS W/DVLPG RTN FLW STILL LOOKS PROMISING FOR AN APPRECIABLE RAIN EVENT HERE AS EARLY AS LT MON NIGHT BUT MORE LIKELY ON TUE AND SORELY NEEDED ACRS THIS PARCHED CWA. .LONG TERM...12Z TUESDAY THROUGH SATURDAY...A SHORT WAVE MOVES THROUGH THE PLAINS TUESDAY FOLLOWED BY YET ANOTHER ON THURSDAY. MODELS VARY ON THE WAY THIS SECOND SYSTEM IS HANDLED. GFSLR CLOSES IT OFF OVER THE CENTRAL/SOUTHERN PLAINS...WHILE THE ECMWF AND CANADIAN KEEP IT AS A MORE OPEN WAVE PROGRESSING ACROSS THE PLAINS. THE UKMET ALSO CLOSES OFF THIS SYS BUT KEEPS IT FARTHER NORTH IN THE PLAINS. HOWEVER HAVE STAYED CLOSER TO THE ECMWF/CANADIAN SOLUTION FOR THIS PERIOD. MAIN FORECAST ISSUES WILL BE PRECIPITATION...BOTH FOR TUESDAY AND LATE IN THE WEEK. FOR TUESDAY THE MODELS ARE FAIRLY SIMILAR WITH THE SHORT WAVE MOVING INTO THE PLAINS...AND THE SURFACE LOW PRESSURE SYSTEM MOVES ACROSS KANSAS. THUNDERSTORMS WILL BE AHEAD OF THE UPPER LEVEL SHORT WAVE WHEN THE GREATEST RETURN FLOW IS STRONGEST. THE GFS CLOSES OFF THE SYSTEM MOVING INTO THE PLAINS ON THURSDAY. THERE ARE SEVERAL WAVES ACROSS THE PACIFIC THAT ARE CONTINUING TO PROGRESS EASTWARD AND SPRING IS NOT A COMMON TIME TO HAVE A CLOSED OFF LOW...THEREFORE HAVE STAYED CLOSER TO THE ECMWF/CANADIAN WHERE THE SHORT WAVE IS MORE OPEN AND CONTINUES TO MOVE THROUGH THE PLAINS. THERE SHOULD BE A BRIEF BREAK BETWEEN SYSTEMS AS A WEAK HIGH PRESSURE SYSTEM MOVES THROUGH ON WEDNESDAY. BUT BY WEDNESDAY NIGHT ANOTHER SHORT WAVE MOVES INTO THE PLAINS ALONG WITH ANOTHER CHANCE OF THUNDERSTORMS. THE GFS IS STRONGER AND SLOWER THAN THE ECMWF AND CANADIAN BUT AGAIN STAYING CLOSER TO THE ECMWF SOLUTION AND WILL THEN THEREFORE END THUNDERSTORMS FRIDAY NIGHT AND KEEP SATURDAY DRY. COOLER AIR WILL SETTLE INTO THE CENTRAL PLAINS EARLY IN THE WEEK. TEMPERATURES WILL BE QUITE A BIT COOLER THAN THIS PAST WEEKEND... BUT STILL AROUND NORMAL FOR THIS TIME OF YEAR. && .GID WATCHES/WARNINGS/ADVISORIES... .NE...NONE. .KS...NONE. && $$ T/JCB ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 230 PM CDT SAT APR 17 2004 .DISCUSSION... SEVERAL THINGS TO CONSIDER...WIND...TEMPERATURES AND THUNDERSTORMS IN THE SHORT TERM AS STRONG SYSTEM DEVELOPS AND COMES ACROSS THE REGION TONIGHT INTO SUNDAY. WARM FRONT HAD LIFTED NORTH FROM JUST SOUTH OF THE NEBRASKA BORDER THIS MORNING TO ACROSS SOUTHERN IOWA INTO SOUTHEAST AND SOUTH CENTRAL NEBRASKA AT 18Z. PLENTY OF INSTABILITY AROUND WITH 60 DEW POINTS SOUTH OF THE FRONT. EXPECT FRONT TO CONTINUE TO LIFT NORTH THIS AFTERNOON WITH 15Z RUC PLACING IT ACROSS NORTHEAST NEBRASKA INTO NORTHERN IOWA BY 00Z. THIS BOUNDRY STILL EXPECTED TO BE PRIMARY FOCUS FOR THUNDERSTORM DEVELOPMENT ESPECIALLY THIS EVENING AS LOW LEVEL JET PICKS UP. HAVE CONTINUED WITH POPS ACROSS NORTHERN PARTS OF THE AREA THROUGH 06Z WITH SLIGHT CHANCE ALONG NORTHERN BORDER AFTER THAT TIME AS FRONT LIFTS A BIT FURTHER NORTH IN ADVANCE OF DEVELOPING SURFACE LOW. WIND ADVISORY APPEARS LIKELY ON SUNDAY ACROSS THE AREA AS SURFACE GRADIENT TIGHTENS. MOMENTUM TRANSFER ON FORECAST SOUNDINGS INDICATE GUSTS OF 40 TO 50 MPH WITH DRY ADIABATIC LAYER UP TO 700 MB AT OFK. SINCE NORTHERN PARTS OF THE AREA MAY BE SLOWER WITH INCREASING WINDS WILL HOLD OFF ON ANY ADVISORY AT THIS TIME. MORE STORMS POSSIBLE ACROSS THE AREA SUNDAY AFTERNOON AS FRONT/TROF MOVES THROUGH AND WITH SUCH STRONG SURFACE WINDS IN PLACE SEVERE STORMS POSSIBLE AS PER DAY 2 OUTLOOK FROM SPC. EXTENDED PERIOD ALSO STAYS ACTIVE AFTER MONDAY AS NEXT WAVE COMES ACROSS ON TUESDAY AND ANOTHER THURSDAY INTO FRIDAY. LITTLE CHANGE TO THE EXTENDED PERIOD WITH DAY 7 TREND TOWARD HPC GUIDANCE AND IDEA OF FASTER MOVEMENT OF SYSTEM FOR SATURDAY. && WATCHES/WARNINGS/ADVISORIES... .NE...NONE. .IA...NONE. && $$ FOBERT ne