AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 855 PM PDT WED APR 18 2001 CURRENT FORECAST IN GOOD SHAPE BUT WILL UPDATE TO FRESHEN UP AND MAY AID WSW...SEE BELOW. FRONTAL PRECIP MOVED INTO THE COASTAL RANGE THIS MORNING...THEN SHOWERS AND THUNDERSTORMS QUICKLY DEVELOPED IN THE CENTRAL VALLEY BY EARLY AFTERNOON...THEN MOVED INTO THE SIERNEV/SOUTHERN CASCADES BY LATE AFTERNOON. LEADING VORT SEEN IN NEVADA NOW WITH TROF AXIS IN THE BAY AREA. THUNDERSTORMS DEVELOPED IN AN UNSTABLE AIRMASS WITH RUC SOUNDING SHOWING OBSERVED CAPES OF 1500 J/KG IN BUTTE COUNTY...LAPS SHOWED 800 J/KG OVER MYV. UNSTABLE AIR MASS WAS EVIDENT WITH LOTS OF ACCAS DURING THE MORNING AND MODELS DID UNDERESTIMATE THIS. AIR MASS FURTHER DESTABILIZED DUE TO STRONG SURFACE HEATING AND GOOD H7-5 QVEC CONVERGENCE. H2 JET OF 130KT OVERHEAD HELPED STORMS BUT WAS SURPRISED WE DID NOT GET ANY WIND DAMAGE WITH CELLS MOVING AT 30-35KTS. PROBABLY DUE TO THE H85-7 WINDS NOT BEING OVER 30KTS AND STORM TOPS OF ONLY 25KFT. GOOD TILT IN A STORM SEEN NEAR BLUE CANYON AND HIGH REFL IN STORMS IN EASTERN BUTTE COUNTY. BREEZY VALLEY WIND HAS WEAKENED AS THE SFO-RNO GRADIENT IS DOWN TO 6-MB FROM 9-MB. APPEARS THERE MAY BE A SURFACE BOUNDARY LYING BETWEEN CHICO AND RED BLUFF. ETA MODEL HANDLED THINGS WELL...ESPECIALLY CONSIDERING CONVECTIVE NATURE. YESTERDAYS AVN QPF WAS TOO FAR NORTH BUT HAD THE DYNAMICS IN THE RIGHT PLACE. RADAR SHOWS BEST REFLECTIVITY CONFINED TO THE WEST SLOPES WITH SOME SHOWERS STILL IN THE VALLEY AND ANOTHER BATCH WITH TROF AXIS IN THE BAY AREA. SNOW LEVELS ARE LOWERING AS WATER VAPOR SHOWS INTENSE SHORT WAVE MOVING THRU THE CWA. STILL RAIN AT BLUE CANYON. AUTOMATED SNOW GAUGES SHOWING UP TO 5 INCHES NEW ALREADY ALONG I-80. SEVERAL RAIN GAUGES SHOWING .50 TO .80 INCHES IN THE SIERNEV. TROF AXIS LIFTS THRU BY 09Z WHICH SHOULD TAPER PRECIP OFF ALL ZONES. STRONG DOWNSLOPE AND SYNOPTIC SUBSIDENCE SHOWS UP IN CLEARING OVER WEST SIDE OF CENTRAL VALLEY NOW. NEXT CONCERN WILL BE SHORT WAVE ON H20 VAPOR NEAR 35N/130W STARTING TO TURN THE CORNER AND TAKE AIM ON CENTRAL CAL FOR THURSDAY AFTERNOON. SSM/I SHOWS 1-IN PW'S SIMILAR TO CURRENT SYSTEMS SOURCE. BEST H7-5 QVEC CONVERGENCE HITS THE SRN CWA...BUT WITH TROF AXIS MOVING THRU THIS WILL HELP DESTABILIZE MOIST ATMOS OVER THE ENTIRE CWA GIVING CHANCE OF SHOWERS AND THUNDERSTORMS. COLDER AIR ALOFT SHOULD INCREASE HAIL THREAT. ETA CAPE VALUES NOT HIGH BUT MAY BE UNDERDONE. MAY NEED ANOTHER SNOW ADVISORY FOR THE SIERNEV. STRONG GOA SHORT WAVE WILL BRING ROUND 3 ON FRIDAY. 00Z ETA SHOWS A 35 UNIT VORT MOVING OVER THE COASTAL RANGE DRIVEN BY 130KT H2 NORTHERLY JET. BY 18Z LEFT FRONT QUAD OF GET GIVES GOOD UPPER DIV OVER NORCAL. TIMING OF HEAVIEST PRECIP WITH ETA TIMING OF DYNAMICS WOULD BE AFTERNOON AND FRIDAY EVENING AS .70-IN PW'S GET SQUEEZED OUT. 00Z/19 ETA SIMILAR TO THE 18Z/18 AVN. WILL TAKE A LOOK AT 00Z/19 AVN BEFORE UPDATES. 12Z/18 UKMET AND NOGAPS ARE SLIGHTLY FASTER AND A TAD FURTHER SOUTH WITH VORT MAX. WAA PRECIP AHEAD OF THE VORT MAY LEAVE LITTLE BREAK IN THE SIERNEV FROM THURSDAY EVENING PRECIP. CONSIDERING ISSUING A WATCH FOR ABOVE REASONS AND TO COORD BETTER WITH HANFORD OFFICE...PLUS THE NORMAL FRIDAY TAHOE/RENO TRAFFIC HEADS UP. TOTAL SNOWFALL AMOUNTS WILL BE SIGNIFICANT AND IF YOU INCLUDE THIS EVENINGS...THURSDAY AFTERNOON/EVE...AMOUNTS COULD REACH 3 FEET. WHAT A WAY TO END TO SEASON FOR MANY SKI RESORTS. H7 TEMPS DROP TO -10C WHICH WILL LOWER SNOW LEVEL TO NEAR 2500 FEET FRIDAY NIGHT. GOOD H85 MOISTURE CONVERGENCE PROGGED BY THE ETA SUGGESTS GOOD RAINS FOR THE CENTRAL VALLEY. ANY BRIEF CLEARING FRIDAY AFTN WITH STRONG APRIL SUN COULD LEAD TO STRONG THUNDERSTORMS IN THE VALLEY. 23 M/S LLVL SHEAR SEEN ON ETA VALLEY SOUNDINGS AND UP TO 100 M2/S2 HELICITY. WRAP AROUND PRECIP AND PROXIMITY OF UPPER LOW SHOULD HAVE LINGER SHOWERS AROUND SATURDAY. EXTENDED MODELS SHOW GOOD RIDGING SUNDAY AND MONDAY WHICH CONTINUES TO AT LEAST TUESDAY FOR A GOOD WARMING TREND. POSSIBLE HEIGHT FALLS BY WEDNESDAY ON THE NORTH COAST. .STO...SNOW ADVISORY TONIGHT CA ZONE 69...WEST SLOPE SIERRA NEVADA ...WINTER STORM WATCH FRIDAY FOR WESTERN PLUMAS COUNTY AND WEST SLOPE SIERRA NEVADA... TARDY ca EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 900 PM EDT WED APR 18 2001 TEMPERATURES BEGINNING TO FALL OFF NOW AS SFC RIDGE BUILDS TO THE N AND WINDS...AT LEAST OVER NORTHERN SECTIONS BEGIN TO DROP OFF. RIGHT ALONG THE COAST THERE HAS BEEN SOME MODIFICATION OF THE LOW LEVEL AIRMASS AS WINDS HAVE BEEN ONSHORE SINCE THE EARLY AFTERNOON. 00Z SOUNDINGS SHOW JUST HOW DRY IT IS OVERALL WITH AROUND ONE QUARTER INCH OF PCP WATER AT TBW AND XMR. MESO-ETA AND RUC SHOW SFC HIGH CENTER TO MOVE OVER GA OVERNIGHT WITH WIND FIELD WEAKENING. CURRENT NE FLOW SHOULD GRADUALLY BACK TO MORE OF A LAND BREEZE. FARTHER TO THE S IN TIGHTER GRADIENT THIS WILL TAKE PLACE MUCH LATER. SO FAR GUIDANCE IS ACTUALLY A LITTLE LOWER WITH SFC DEW PTS COMPARED TO CURRENT READINGS. HOWEVER WITH LOWER 30 DEW PTS IN MANY AREAS OF THE N PREFER THE SLIGHTLY COOLER MAV GUIDANCE TEMPS. THIS WILL MEAN RECORD LOWS MAY BE ACHIEVED AT DAB (RECORD 43) AND MCO (RECORD 46). WITH N LAKE AND INTERIOR VOLUSIA ALREADY IN SEPERATE ZONE GROUP AND FAWN SITES ALREADY REPORTING TEMPS IN LOWER 50S IN THIS AREA WILL LOWER MINS INTO THE 30S WITH ISOLATED FROST FOR THIS GROUP. THIS WILL ALIGN BETTER WILL SURROUNDING FL ZONES AS WELL. MARINE...WIND AND SEAS WILL BE SLOW TO DROP OVER THE S WATERS WITH STILL 15 TO 20KTS JUST ABV THE SFC. WILL DROP HEADLINE TO THE N AS BUOY 9 DOWN TO 14 KTS AND SEAS OF 5 FEET. .MLB...SMALL CRAFT ADVISORY COCOA BEACH TO JUPITER INLET. ...RED FLAG WARNING THURSDAY AFTERNOON FOR SEMINOLE LAKE...ORANGE...OKEECHOBEE...OSCEOLA AND INLAND VOLUSIA COUNTIES. ...FIRE WEATHER WATCH THURSDAY AFTERNOON FOR BREVARD AND COASTAL VOLUSIA. PUBLIC/MARINE...BLOTTMAN AVIATION/FIRE WEATHER...PENDERGRAST fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 850 PM EDT WED APR 18 2001 CLEAR SKIES ACROSS THE CWA WITH TEMPS MAINLY IN THE 50S MOST PLACES. DEWPOINTS HAVE RISEN INTO THE LOWER AND MID 30S WITH WINDS 3 TO 5 KNOTS AT THIS TIME. SFC HIGH AT 1026 MB IN THE LOWER MS VALLEY WITH THE RIDGE AXIS ACROSS NRN FL AND INTO THE WRN ATLC. RUC AND 18Z MESO-ETA MODELS SHIFTS THE HIGH CENTER INTO NRN GA BY 09Z-12Z THU...ALLOWING WINDS TO BECOMING NEAR CALM OVER MOST OF THE CWA. COMPARING LATEST READINGS TO GUIDANCE SHOWS DEWPOINTS ARE AT OR A LITTLE ABOVE GUIDANCE. THE CLEAR SKIES AND LIGHTENING WINDS WILL PROMOTE A GOOD RADIATIONAL COOLING NIGHT. CURRENT ZONE PACKAGE SEEMS ON TARGET FOR MID 30S WITH SOME LOWER 30S OVER OVER MUCH OF THE INLAND ZONES. PATCHY FROST ALSO A POSSIBILITY WITH WINDS BECOMING CALM LATER TONIGHT. PROBABLY WILL NOT CHANGE ONGOING FORECAST...BUT WILL MONITOR TRENDS DURING THE NEXT FEW HOURS. MARINE...WINDS DOWN TO NEAR 10 KNOTS OVER THE WATERS AND SEAS HAVE DROPPED OFF TO 2-3 FT. WILL UPDATE TO REMOVE SCEC HEADLINE. THANKS TLH FOR HELP SENDING TAFJAX. .JAX... .GA...NONE. .FL...NONE. ARS fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 950 AM EDT WED APR 18 2001 12Z TALLAHASSEE SOUNDING BONE DRY WITH 0.17" PRECIPITABLE WATER. RED FLAG WARNING CRITERIA FOR FL ZONES SHOULD EASILY BE REALIZED TODAY. SURFACE HIGH PRESSURE CENTERED OVER ARKANSAS WITH STRONG OFFSHORE FLOW EASILY MEETING SMALL CRAFT ADVISORY CRITERIA OVER THE COASTAL WATERS. 12Z 850 MB RAOB PLOT SHOWED NOTABLE COLD ADVECTION... PARTICULARLY OVER THE GULF. 11Z RUC ADVERTISES WIND OVER WATERS TO STAY STRONG AS COLD ADVECTION OVER RELATIVELY WARM WATERS ENSURES CONTINUED DOWNWARD WIND MOMENTUM TRANSPORT. WINDS OVER LAND NEAR THE COAST ARE ALSO PRETTY STRONG PER LATEST METARS...SO MAY ADJUST THESE AREAS IN ZONES. MAXIMUM TEMPERATURES TODAY STILL LOOK ON TRACK. .TLH... AL...NONE. GA...NONE. FL...RED FLAG WARNING ALL ZONES UNTIL SUNSET. FIRE WEATHER WATCH THURSDAY AFTERNOON ALL ZONES. SMALL CRAFT ADVISORY GMZ750-755-770-775. TJT fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 930 AM EDT WED APR 18 2001 CURRENTLY/THIS AFTERNOON...WIND CHILLS IN THE 30S ACROSS THE NORTH HALF OF THE AREA. HIGH CLOUDS ASSOCIATED WITH UPPER TROUGH WILL BE OUT OF HERE QUICKLY SO WILL SEE FULL SUN. LOW LEVEL COLD ADVECTION OCCURRING AND MODELS FORECAST 850 MB TEMPS TO DROP A FEW MORE DEGREES WITH GUSTY LOW LEVEL NORTHERLY WINDS. WITH RATHER HIGH APRIL SUN ANGLE...MAX TEMPS SHOULD REACH THE UPPER 60S IN THE NORTH TO LOWER 70S IN THE SOUTH...CLOSE TO RECORD COOL HIGH TEMPS. DO NOT SEE ANYTHING IN THE CURRENT FORECAST THAT NEEDS UPDATING. TONIGHT...MODELS SHOW HIGH CENTER MOVING EAST ACROSS GEORGIA AND BEGINNING TO ELONGATE EAST/WEST SOMEWHAT. THIS WILL LIKELY DEVELOP BOUNDARY LAYER ONSHORE FLOW IN THE SOUTH. EXPECT QUICK DROP IN TEMPS EARLY TONIGHT THERE SO IT WILL STILL BE QUITE COOL. TEMPERATURES SHOULD BE AROUND 15 DEGREES BELOW CLIMO VALUES FOR THIS TIME OF THE YEAR...RECORD LOWS POSSIBLE AT MCO AND DAB. RECORDS: MCO 46 (1999) DAB 43 (1997) MLB 41 (1997) FIRE WEATHER...FEW SPOTS ALREADY 35 PERCENT OR BELOW DUE TO VERY LOW DEW POINTS (MID 20S TO LOW 30S). WITH WINDS 15 MPH AND GUSTY...RED FLAG WARNING ALREADY VERIFYING...IN FACT VERIFIED OVERNIGHT IN MANY LOCATIONS! SUCH A PROFOUNDLY DRY AIR MASS WILL LEAD TO RED FLAG CONDITIONS AGAIN TOMORROW OVER THE INTERIOR AND EVEN THE COAST SHOULD SEE A PERIOD OF RH BELOW 35 PERCENT. MARINE...ADVISORY CONDITIONS PRESENTLY OCCURRING. LATEST RUC AND MESO ETA KEEP GRADIENT UP MOST OF THE AFTERNOON. PLAN TO ADJUST WIND TREND SLIGHTLY. REGARDLESS...WAVE WATCH MODEL KEEPS SEAS 7 FEET OR HIGHER ALL DAY. .MLB...SMALL CRAFT ADVISORY FLAGLER BEACH TO JUPITER INLET. ...RED FLAG WARNING UNTIL SUNSET TODAY FOR ALL OF EAST CENTRAL FLORIDA. ...RED FLAG WARNING THURSDAY AFTERNOON VOLUSIA...LAKE... ORANGE...SEMINOLE AND OSCEOLA COUNTIES. ...FIRE WEATHER WATCH THURSDAY AFTERNOON BREVARD...INDIAN RIVER...ST LUCIE...MARTIN AND OKEECHOBEE COUNTIES. PUBLIC/MARINE...LASCODY AVIATION/FIRE WEATHER...VOLKMER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1010 PM EDT WED APR 18 2001 TEMPS FALLING NICELY ERN FORECAST AREA (FA) THIS EVNG. WITH LGT WNDS...DWPTS IN THE 20S AND NEARLY CLEAR SKIES WE SHOULD CONTINUE TO RADIATE QUITE WELL. 00Z RUC SHOWING TEMPS IN THE LOWER OR MID 30S...BY THU MRNG CNTRL KY - AND WITH LOCAL AWOS'S ALREADY IN THE LWR OR MID 40S...THIS SEEMS REASONABLE. WE WIL ISSUE FROST ADVISORY ERN FA. RMNDR OF FCST ON TARGET. .SDF...FROST ADVISORY CENTRAL KENTUCKY OVERNIGHT. ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1155 AM EDT WED APR 18 2001 .UPDATED... REMOVED THE MORNING WORDING FROM THE FIRST PERIOD. SNOWFALL APPEARS TO BE WITHIN FORECAST...SO NO CHANGES IN ACCUMULATIONS...WILL MAINTAIN CURRENT ADVISORIES. TEMPS LOOK WITHIN FORECAST RANGE. .SYNOPSIS... A DEVELOPING LOW PRESSURE SYSTEM SOUTH OF CAPE COD WILL CONTINUE TO MOVE NORTHEAST ACROSS THE SOUTHERN GULF OF MAINE THIS AFTERNOON...AND THEN TRACK INTO THE CANADIAN MARITIMES. THIS SYSTEM WILL BRING WET SNOW TO DOWNEAST MAINE...WITH LESSER AMOUNTS ACROSS WESTERN AND NORTHERN AREAS. DISCUSSION... MODELS VERY SIMILAR TO 12Z RUN...WITH A SLIGHTLY FURTHER EAST TRACK FROM YESTERDAYS 00Z RUN. FOR THE SHORT TERM WILL LEAN ON THE ETA...WHICH HAS SEEMED TO HAVE A GOOD HANDLE ON THIS STORM. THE ETA STILL ADVERTISES .75 INCHES OF PRECIP AT EPO...WITH LESSER AMOUNTS TO THE NORTH AND EAST. AVN/GEM ARE IN GOOD AGREEMENT WITH THE ETA...WITH SIMILAR QPFS. ALOFT...A VORT MAX OVER THE MID ATLANTIC CLOSES OFF AND TRACKS JUST TO THE EAST OF MAINE. THIS BRINGS IN VORTICITY ADVECTION AND SOME UPPER LEVEL DIVERGENCE TO EXTREME EASTERN MAINE...THUS CAUSING THE GREATEST LIFT AND ACCOUNTING FOR HIGHER QPFS. 850 MB LOW WILL TRACK NEAR EASTPORT... BRINGING SOME WAA AT 850. SINCE THIS IS LIMITED...SOUNDING REMAIN COLD ENOUGH FOR SNOW. BOUNDARY LAYER TEMPS MAY CAUSE SOME AREAS...MAINLY ALONG THE COAST AND AT THE START OF THE EVENT...TO MIX WITH RAIN. FOR NOW CURRENT PACKAGE SEEMS REASONABLE...AND WILL ONLY MAKE MINOR ADJUSTMENTS. HOWEVER...THIS STORM BEARS WATCHING...AS ONLY A SMALL ERROR IN TRACK WILL RESULT IN DRASTICALLY HIGHER...OR LOWER...PRECIPITATION AMOUNTS. KEEPING CLOSE EYE ON RUC/CURRENT RADAR. OTHERWISE...CLEARING TREND ON THURSDAY. STUCK CLOSE TO MAV NUMBERS FOR OVERNIGHT LOWS ON WEDNESDAY AND THURSDAY NIGHTS. FWC/MAV COMPROMISE FOR HIGHS TODAY AND TOMORROW. EXTENDED...LOW PRESSURE WILL TRACK TO OUR WEST SUNDAY...WHICH SHOULD PULL A WARM FRONT THROUGH OUR ENTIRE CWA. THIS COULD BE THE FIRST REAL TASTE OF SPRING FOR MANY IN NORTHERN MAINE. THE AND AVN/GEM ARE SLOWER BRINING IN RAIN FROM THIS SYSTEM...SO CHANGED EXTENDED TO HAVE RAIN START LATE SATURDAY. NO OTHER CHANGES MADE. COASTAL WATERS...STILL GOING WITH A STRONG GALE...HAVING A FEW GUSTS TO 50 KTS. EXPECT WINDS TO PEAK TODAY...AND THEN GRADUALLY DROP DOWN TO SCA WINDS LATE TONIGHT. .CAR...GALE WARNING WINTER WEATHER ADVISORY TODAY ZONES 16/17/29/30. BT/TM me SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 937 PM EDT WED APR 18 2001 LAKE INDUCED BOUNDARY IS DIVIDING THE CWA FROM NORTHWEST TO SOUTHEAST. BOUNDARY CONTINUES TO BE RESPONSIBLE FOR STRATOCU DECK WITH WEAK SURFACE CONVERGENCE AS NOTED ON THE LATEST LAPS DATA. AS RIDGING CONTINUES TO UNFOLD ACROSS THE REGION...EXPECT THE CURRENT BOUNDARY TO DISSIPATE AS WELL AS THE CLOUDS. SOME CI MAY SPILL OVER THE RIDGE BUT NOT ENOUGH TO CHANGE THE MOCLR FORECAST. AS WINDS BECOME LIGHT...TURNING SLIGHTLY SOUTH...THIS SHOULD BRING TEMPS DOWN BELOW FREEZING ONCE AGAIN FOR MOST AREAS OVERNIGHT. FIND IT HARD TO FOLLOW THE LAMP GUIDANCE WHICH KEEPS TEMPS ABOVE 32 CWA WIDE. FOLLOWING TRAJECTORY FORECASTS AND THE LATEST RUC40...WE DO EXPECT MOSTLY 20S IN THE ZONES. SO UPDATE ZONES WILL INCLUDE A CLEAN UP OF EVENING WORDING... SLIGHTLY LOWER TEMPS AND ADJUST WINDS. .DTX...NONE. BGM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 900 PM EDT WED APR 18 2001 A QUIET BUT COOL NIGHT EXPECTED. SURFACE RIDGE WAS LOCATED OVER THE WESTERN GREAT LAKES EARLY THIS EVENING. CORRESPONDING AIRMASS REMAINS VERY DRY...WITH DEW POINTS GENERALLY IN THE TEENS TO AROUND 20. RECENT OBSERVATIONS SHOW WINDS GRADUALLY WEAKENING...IN RESPONSE TO BOUNDARY LAYER DECOUPLING AND APPROACHING SURFACE RIDGE. VISIBLE AND IR SATELLITE LOOPS SHOW SCATTERED DIURNAL CLOUDS DISSIPATING...WITH ONLY PATCHY CI MOVING INTO THE WESTERN LAKES REGION DOWNSTREAM FROM 500 MB MEAN RIDGE POSITIONED OVER THE PLAINS STATES. CURRENT DEW POINTS...TOGETHER WITH FORECAST DEW POINTS FROM THE RUC STILL AROUND 20F BY 09Z SUPPORT SOME LOCALES FALLING TO NEAR 20F OVERNIGHT -- PER GOING FORECAST. QUITE COOL...CONSIDERING NORMAL LOWS NOW RANGE FROM 30 TO 33 ACROSS THE FORECAST AREA. RUC ALSO SHOWS SURFACE WINDS COMING AROUND TO THE SOUTH AFTER 06Z ACROSS WESTERN PARTS OF FORECAST AREA AS SURFACE RIDGING SLIPS TO THE EAST. WILL INCORPORATE THIS MINOR CHANGE INTO FORECAST. NO OTHER CHANGES ANTICIPATED. .APX...NONE. SMITH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 941 PM EDT WED APR 18 2001 THANX TO WFOS ALY AND GYX FOR PROVIDING SERVICE BACKUP FOR US TODAY. WILL OPT TO UPDATE ZFP TO MAKE A FEW MINOR CHANGES TO GOING FORECAST. HI PRESS RIDGE TO BUILD EAST ACRS THE GREAT LKS REGION TONITE...AS A STORM SYS TRACKS UP INTO THE CANADIAN MARITIMES. THIS HI PRESS RIDGE TO BUILD ACRS THE FA FROM THE WEST ON THU. TROP FOLD/SHORT WAVE (AS SEEN IN H2O VAP IMAGERY) TO DIVE TO THE SOUTH OF THE FA TONITE. UPR TROF TO MOVE ACRS THE FA TONITE AND THEN TO THE EAST OF THE FA ON THU. GOOD SFC PRESS GRADIENT TO LINGER ACRS THE FA TONITE AS WELL. N- NW FLOW ALOFT TO PERSIST ACRS THE FA OVRNITE TONITE. 21Z 40KM RUC SHOWS TEMPS TO GET DOWN INTO THE M-U20S TONITE WITH W-NW SFC WINDS BECOMING 5-10 KTS. T1MIN TEMPS ARE MOSTLY IN THE TEENS TONITE. WIDENED UP A FEW OF THE LOW TEMP RANGES FOR THE OVRNITE PERIOD BASED ON CURRENT OBS TRENDS AND RUC DATA. FEW TWEAKS TO FIRST PERIOD WINDS AS WELL BASED ON OBS TRENDS AND RUC DATA. SOME AMT OF LOW-LVL MOISTURE TO DROP DOWN ACRS THE NRN TIER OF THE FA TONITE. RUC SHOWS JUST SOME MID AND UPR LVL CLDS TO AFFECT THE ERN PART OF THE FA TONITE. IR SAT PIX SHOW SOME LWR CLDS MOVING SOUTH FROM SRN QUE AND SOME HIR CLDS MOVING NORTH ACRS VT ATTM. FEW TWEAKS TO FIRST PERIOD CLD COVER FORECAST BASED ON THESE TRENDS. WK H85 CAA TO TAKE PLACE ACRS THE FA TONITE...THEN WK WAA ON THU. LOW-LVLS TO DRY OUT ON THU ACRS THE FA. MID-LVLS TO REMAIN DRY ACRS THE FA ON THU. LOW-LVL LAPSE RATES TO CONT TO BE HI ACRS THE FA INTO THU. 12Z ETA CRANKING OUT SOME PCPN ACRS THE FA TONITE AND EARLY ON THU...BUT WILL DISCOUNT THIS AS NO PCPN EXPECTED ACRS THE FA OVER THE NEXT 24 HRS. REST OF CHANGES TO GOING ZFP COSMETIC IN NATURE. WORK ZONES OUT UNDER ALBWRKCWF. FINAL ZFP BY 10 PM AFTER A QUICK LOOK AT THE LATEST OBS. HYDRO-WISE...SRN PART OF LK CHAMP FLIRTING WITH FS ATTM AS A RESULT OF CONTINUED NORTHERLY FLOW ACRS THE LK. REST OF THE WIDER PORTION OF THE LK STILL HAS A WAYS TO GO BEFORE FS THOUGH. STAY TUNED... .BTV...NONE. MURRAY vt SOUTHEAST IDAHO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE POCATELLO/IDAHO FALLS ID 250 PM MDT THU APR 19 2001 CURRENT RADAR LOOP SHOWING WIDELY SCATTERED SHOWERS TRACKING NE ACROSS FCST/A THIS MORNING. THIS ACTIVITY ASSOCIATED WITH SFC TROF AND THE INTERACTION OF LF QUAD OF 3H JET. ADDITIONAL SHOWERS/ISOL TSTMS ACROSS WESTERN ID ASSOCIATED WITH UPPER S/WV. ACTIVITY ACROSS WESTERN ID SHOULD TRACK ACROSS FCST/A LATE THIS MORNING/EARLY AFTN (PER RUC MODEL) AND THEN SOME CLEARING SHOULD MOVE INTO THE AREA BY LATE AFTN. THIS WILL BE SHORT LIVED AS NEXT MORE POTENT WAVE WILL EJECT EAST FROM COASTAL LOW AND SLIDE INTO SE ID BY FRIDAY MORNING. MODEL TRENDS HAVE BEEN PLACING THIS FEATURE A BIT FURTHER SOUTH AND EAST WITH EACH NEW RUN SO DOWN PLAYED POPS OVER CENTRAL MTNS. AS THIS WAVE SLIDES ACROSS AREA FRIDAY...DECENT COOLING ALOFT (2-4C AT 5H) SHOULD HELP DESTABLIZE ATMOSPHERE DURING THE AFTN FOR SOME TSTMS. EXTENDED...NO CHANGES PLANNED. UPPER LOW WILL SLIDE BY WELL TO OUR SOUTH FOR SAT/SUN BUT LOBE OF INSTABILITY EXTENDING NORTH SHOULD KEEP A FEW SHOWERS AROUND. MON-WED LOOKS DRY AS UPPER RIDGE BUILDS INTO AREA. 579 5H HEIGHTS SUGGESTS THAT WE COULD REACH NEAR 80 DEG BY NEXT WED. DAY SHIFT MAY WANT TO MAKE THE WARMER ADJUSTMENT. BYI 62/39/53 356 .KSFX WSR-88D...OPERATIONAL...VCP 21. .PIH...NONE. PIH EW 060/038 053/036 055 06456 id AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 400 AM CDT THU APR 19 2001 MDLS PRETTY CLOSE WITH THE WEATHER FEATURES AFFECTING THE ABR CWA THROUGH FRI NIGHT. FOR TODAY...THEY SHOW A S/W MOVG QUICKLY THROUGH THE AREA THROUGH THIS MRNG. WITH LITTLE MEAN RH...THIS S/W WILL BRING ONLY MID AND HIGH CLOUDS WITH A FEW SPRINKLES EARLY THIS MRNG ACROSS NC SD. FOR THE REST OF THE DAY AND THIS EVENING...THE MDLS SHOW A MUCH STRONGER 50H S/W AND ASSOCIATED SFC LOW PRES MOVING E AND NE ACROSS THE CWA. ACCORDING TO THE MSAS ANALYSIS...THE MDLS ARE TOO HIGH ON THE SFC LOW PRESSURES EARLY THIS MRNG AND THE LATEST RUC SHOWS SFC LOW PRESSURES LOWER THAN ALL 3 MDLS EARLY THIS MRNG AND CLOSER TO THE MSAS ANALYSIS. THEREFORE...THE SFC LOW PRES MOVING ACROSS THE CWA WILL BE LOWER THAN THE MDLS AND THUSLY THE SFC SE WINDS WILL BE STRONGER. WILL GO WITH BREEZY TO WINDY CONDITIONS ACROSS MUCH OF THE CWA TODAY AS A RESULT. GOOD PVA...WAA AND MID LEVEL INSTABILITY WITH THIS 50H S/W MOVING ACROSS THE CWA THROUGH THIS EVENING. THE ONLY THING LACKING IS MOISTURE. THE ETA OVERDOES THE SFC DWPTS THROUGH THE EVENING...FORECASTING DWPTS IN THE 50S. NO 50 DEGREE DWPTS ARE SEEN AS FAR AS S OKLAHOMA. THEREFORE...THE RUC...NGM AND AVN SFC DWPTS LOOK MUCH BETTER IN THE 40S. WITH THE GOOD LIFT AND INSTABILITY...SKIES OVER THE CWA SHOULD BE MOSTLY CLOUDY THROUGH THE DAY WITH A SLIGHT CHANCE OF -SHRAS THIS AFTN AND EVENING. 85H TEMPS WILL BE VERY WARM TODAY. DESPITE THE CLOUD COVER...WITH TEMPS STARTING OUT IN THE 40S AND LOWER 50S EARLY THIS MRNG AND WITH GOOD MIXING...TEMPS SHOULD RISE TO NEAR YSTRDYS HIGHS. FOR TONIGHT...THE 50H S/W AND SFC LOW PRES MOVE OFF TO THE NE TAKING THE MID LEVEL CLOUDS AND SCT -SHRAS WITH IT BY LATE EVENING. WITH GOOD SUBSIDENCE IN BEHIND...SFC HIGH PRES BUILDING IN ALONG WITH CAA...WINDS WILL BECOME NW ACROSS THE CWA. TSCTS SHOW LL RH INCREASING. THEREFORE...LOW CLOUDS SHOULD MOVE IN ACROSS THE NORTHERN PART OF THE CWA THROUGH THE NIGHT. TEMPS SHOULD FALL INTO THE 40S ACROSS THE CWA BY FRI MRNG. ON FRIDAY...SFC HIGH PRES WILL BE OVER THE AREA ALONG WITH LOWER 85H TEMPS AND GOOD LL RH. THEREFORE...MIXING SC SHOULD BRING P/C SKIES OVER THE AREA WITH HIGH TEMPS ABOUT 5 TO 10 DEGREES COOLER THAN TODAY. NW WINDS AT 10 TO 20 MPH WILL SLOWLY TURN TO THE NE AS WE BEGIN TO RECEIVE THE INFLUENCES FROM THE NEXT MUCH MORE POTENT 50H S/W. FOR FRI NIGHT...AS THE NEXT MUCH STRONGER S/W MOVES IN ALONG WITH GOOD MEAN RH....SCT SHRAS AND TSRAS SHOULD DEVEVLOP ACROSS THE ABR CWA THROUGH THE NIGHT. WILL CONTINUE WITH THE CURRENT 50% POPS FOR FRI NIGHT. THE ETA AND AVN BOTH BRING GOOD QPF TO THE CWA BY SAT MRNG. TEMPS SHOULD ONLY FALL INTO THE 40 TO 50 DEGREE RANGE BY SAT MRNG. .ABR...NONE MOHR sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1115 AM EDT THU APR 19 2001 MAIN CONCERN WITH THIS FCST PACKAGE IS THE HI TEMP FOR TDA AND ON SET OF SHRA TNGT. WV IMAGERY AND RUC DATA SHOWING A RIDGE OVR NRN PLAINS THIS AM. A NUMBER OF WEAK SHRTWV WERE MOVG THRU THIS RIDGE DVLPG MID AND HI CLDS. A DRY SLOT IS ALSO XTNDG FM SRN CA NE INTO NE WY. A WEAK LOW IS OVR WRN SD THIS AM AND IS TRACK SLOWLY EWRD. A WRM FRNT STRETCHES E FM THIS LOW INTO IA. THE 1ST OF THE WEAK SHRTWV WILL SWEEP THRU FA THIS AFTN. MEAN SFC TO H50 RH ARND 50 PCT. PROFILE DATA SHOW CLD LYR ARND 12K FT. OTHERWISE...QUITE DRY. ACCORDING TO VIS...MID LVL CLDS ARE SLIDING OVR THE RIDGE. THUS XPCT PT SUNNY COND TDA. NGM MOS/AVN MOS ARE IN GOOD AGREEMENT. BOTH ARE RUNNING A LTL LESS THAN ACTUAL TEMPS AT A FEW LOCATIONS...SO WILL ADJUST THEM UP A BIT. ELSEWHERE TEMPS LOOK ALRIGHT. WINDS WILL REMAIN OUT OF THE S. XPCT WITH THE SFC HEATING MORE OF THE BLYR WILL MIX TO SFC...THUS WINDS SHOULD INCREASE TO 10 TO 20 MPH ACRS FA THIS AFTN. LOOKING FOR THE SD LOW TO TRACK NE INTO CNTRL MN BY 12Z FRI PULLING THE WRMFNT INTO CNTRL WI. CYC FLOW AHEAD OF FNT WILL DRAW GULF MSTR INTO THE FA LATE TNGT AND AND FRI. MEAN SFC-H50 RH WILL RISE TO 80-90 PCT ACRS REGION LATE TNGT. 300K ISENTROPIC ANLYS SHOWING STRONG LIFT ACRS FA AHEAD OF WRMFNT AND OVR FA. THIS LINES UP WELL WITH THE SHRTWV MOV OVR LATE TNGT AND FRI. MEAN RH WILL INCREASE TO 90 PCT ACRS FA ON FRI. SHRTWV AND ISENTROPIC LIFT WILL INCREASE OVR FA ON FRI. CHC OF SHRA LOOK LIKELY ON FRI. DWPNT DEPRESSION WILL APPROACH ZERO ACRS FA TNGT...SO XPCT TO SEE SOME FOG. TEMPS SHOULD FALL OFF TO ARND 40 OVRNGT. .MQT...NONE. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 PM EDT THU APR 19 2001 12Z RAOBS/LATEST WV LOOP AND RUC ANAL SHOW BLDG RDG IN CNTRL CONUS BTWN TROFS ALG W CST AND E CST. W TROF DEEPENING WHILE E CST TROF TENDING TO LIFT NE. A SHRTWV MOVG NE THE WRN PLAINS HAS RESULTED IN LO PRES DVLPMNT OVR WRN SD. 12Z RAOBS SHOWING LO/MID LVL MSTR LACKING...BUT INCRSG SLY FLOW AHD OF LO PRES TENDING TO ADVCT HIER H85 DWPTS OVR SRN PLAINS NWD. SFC DWPT HAS RISEN INTO THE 50S AS FAR N AS MKC. A FEW LTG STRIKES ALSO EVIDENT OVR SW MN...WHERE AVN F6 SHOWING H7-5 LAPSE RATE NR 8C/KM. SKIES OVR CWA MCLR...WITH CLD AREAS OVR NRN LK SUP/SCNTRL ONTARIO MOVG SLOWLY SE AND DRYING AND OVR CNTRL MN-NCNTRL WI TENDING TO MOVE ESE AHD OF WEAK AND SHEARING SHRTWV IN NCNTRL MN. FOR TNGT...XCPT MCLR SKIES THIS EVNG GIVING WAY TO INCRSG CLDS LATE AS AVN FCST 300K ISENTROPIC SFC PROGS SHOW INCRSG LIFT/MOISTENING OVRNGT. AS VORT AND UPR DVGC LOBE/AXIS OF HIER PW ARRIVES LATE TNGT OVR SW ZNS...HAVE INTRODUCED CHCY POPS THERE. ALSO MAINTAINED LO CHC POPS TOWARD DAWN FOR ZNS JUST TO NE. KEPT E TOTALLY DRY WITH JUST INCRSG CLDS LATE. MOS FCST TEMPS LOOK RSNBL WITH INCRSG GRADIENT WND OFFSETTING FAIRLY LO DWPTS. FOR FRI...MODELS IN GENERAL AGREEMENT ON SHOWING INCRSGLY SHEARED SHRTWV NOW IN NW PLAINS MOVG NE INTO MEAN RDG POSITION/UPR CONFLUENCE AND SLOWLY WEAKENING WITH AXIS OF H85-5 QVECTOR CNVGC AND H4-2 DVGC SLOWLY PROGRESSING SW-NE ACRS CWA AS SFC LO MOVES INTO WRN ONTARIO. THINK ETA OVRDVLPD ON SFC FEATURE CONSIDERING SHRTWV MOVG INTO MEAN RDG POSITION...PREFER WEAKER AVN/NGM/CANADIAN. BUT ALL THESE MODELS GENERATE AT LEAST SOME PCPN. SO GENERALLY WENT HIER THAN FWC...BUT LWR THAN HIER FAN GUIDANCE...FOR POPS BECAUSE SYS CURRENTLY LACKS A LOT OF MSTR...LACKS JET DYNAMICS AND BCMS INCRSGLY DISORGANIZED LOOKING HEADING INTO MEAN RDG POSITION. MODELS INDICATE DRYING ALF DURG AFTN MOVES OUT AHD OF SFC WARM FNT...WHICH APPEARS TO GET STUCK OVR NE WI DURG DAY. SO WORDED FCST FOR SHRA MAINLY IN THE MRNG ALG THE WI BORDER. THINK SELY FLOW N OF WARM FNT ADVERTISED BY AVN WL KEEP LO CLDS IN DURG DAY...SO TRENDED MAX TEMPS CLOSER TO LWR AVN GUIDANCE. BEST CHC FOR SOME CLRG IN THE AFTN NR IWD. SINCE AVN FCSTS LI DOWN CLOSE TO ZERO THERE LATE IN THE DAY...THINK THERE COULD BE A -SHRA/-TSRA DVLP. BUT SUBSIDENCE/ QVECTOR DVGC WL KEEP ANY ACTIVITY LIMITED IN COVG AND INTENSITY. FORCG/MSTR ASSOCIATED WITH FRI SHRTWV EXITS ERN ZNS EARLY FRI NGT... THEN COMES BACK LATE AHD OF NXT VIGOROUS SHRTWV LIFTING NEWD OUT OF SW TROF PER FVRD FASTER AVN IN FAST/CONFLUENT FLOW ALF. SO REINTRODUCED POPS LATE ACRS SW ZNS. OTRW...LOTS OF CLDS WITH LINGERING LLVL MSTR/FOG. ON SAT...VIGOROUS SHRTWV PROGGED TO PASS OVR OVR CWA...AVN FCSTS SFC LO TO TRACK OVR WRN LK SUP...ETA AND CANADIAN ACRS CNTRL CWA. WENT WITH COMPROMISE PER PMDHMD. THESE MODELS SHOW BAND OF SHRA LIFTING NE AHD OF LO DURG MRNG/EARLY AFTN...THEN DRY SLOTTING DURG THE AFTN ACRS ESPECIALLY THE ERN HALF OF CWA...WHERE MOS SHOWING TEMPS RISING WELL INTO THE 60S. ETA FCSTS CAPES UP TO 3000 J/KG AT IMT...BUT WITH A SFC DWPT OF 66. ETA BIAS HAS BEEN TO FCST DWPTS TOO HI...SO REJECTED THIS FCST. MORE RSNBL AVN ON THE OTHR HAND SHOWS DWPTS RISING NR 55 BEFORE CONSIDERABLE MID TO UPR LVL DRYING...WITH MODIFIED IMT SDNG SHOWING CAPE OF 1100 J/KG FOR TD OF 55. BEST CHC FOR THESE INSTABILITY TSRA WL BE OVR SE ZNS...AND HAVE WORDED ACCORDINGLY. PRIMARY THREAT FM SVR TSRA WOULD BE STRG WNDS...WITH 50KT H85 WNDS AND UNIDIRECTINAL FLOW IN LO-MID TROP. LOCALLY HVY SHRA PSBL OVR WRN ZNS JUST TO W OF LO TRACK WITH AVN SHOWING PW RISING TO NR 1.50". DRIER NWLY FLOW WL ENVELOP CWA SAT NGT. DURG THE XTNDED PD...MODELS INDICATE CONTD SPLIT FLOW ACRS THE CONUS WITH WRN TROF/ERN RDG CONTG IN SRN BRANCH ON SUN BLO NRN BRANCH TROF ACRS CNTRL CAN. RESULT FOR NW GRT LKS IS CONFLUENT WLY FLOW ALF WITH BIG SFC HI PRES OVR ONTARIO. IF FNTL ZN IN WAKE OF SAT SYS STALLS NOT TOO FAR TO S...COULDN'T RULE OUT SOME DZ/-RA ESPECIALLY ACRS THE S IN LLVL ENELY FLOW/SHALLOW COOL AIRMASS. BUT LATEST AVN GUIDANCE SHOWS MORE AGGRESSIVE DRYING/ACYC FLOW PER A NUMBER OF CANADIAN ENSEMBLE MEMBERS. SO HAVE KEPT FCST DRY AND INTRODUCED AT LEAST SOME SUN. OPERATIONAL MODELS/MRF ENSEMBLE MEMBERS IN GOOD AGREEMENT ON LIFTING OUT BIG WRN TROF ON MON WITH HEALTHY SFC LO PRES RIDING NEWD TOWARD GRT LKS. 12Z AVN HAS TRENDED WEAKER WITH SYS AND A BIT FARTHER S. ALTHOUGH SYS WL BE RIDING INTO UPR CONFLUENCE BTWN SRN BRANCH RDG AND NRN BRANCH TROF...SUPPORT DEEPER SCENARIO AS WHOLE TROF LIFTING OUT...NOT JUST A PIECE. XPCT WAD RA IN RRQ OF UPR JET IN ERN CAN AND WITH FNTL BNDRY LIFTING N TOWARD CWA. NRN AND SRN BRANCH TROFS PHASE A BIT MORE OVR THE E FOLLOWING PASSAGE OF THIS STORM ON TUE...SO WOULDN'T BE SURPRISED TO SEE PCPN MIX WITH OR CHG TO SN BEFORE ENDING ON TUE. COOLER AND DRIER AIR WL OVRSPRD NW GRT LKS WITH SFC HI PRES MOVG INTO THE E LATER ON TUE. ANOTHER SHRTWV MAY APRCH FM THE NW NXT LATE WED/THU...BUT SYS SHUD BE WEAK AND CUTOFF FM SGNFT MSTR AS IT WL BE MOVG THRU DRY RDG. COORDINATED WITH APX. .MQT...NONE. KC mi