AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GOODLAND KS 1042 AM MDT SUN APR 20 2003 WILL BE MAKING MINOR TWEEKS TO THE WIND AND CLOUD COVER. THICKEST CLOUD COVER OVER THE NORTHEAST PORTION OF THE FORECAST AREA AT THIS TIME. LATEST RUC IS CATCHING THIS...AND ALSO THE CLEARING TREND FOR THIS AFTERNOON IN THAT AREA. BREEZY CONDITIONS HAVE WORKED THEIR WAY INTO THE WESTERN PORTIONS OF KIT CARSON AND CHEYENNE COUNTIES OF COLORADO...AND WILL INCREASE TO THAT. RUC IS DOING WELL WITH THE WINDS...AND WILL UPDATE THE GRIDS WITH IT. HIGHEST SPEEDS WILL BE THE EASTERN SECTIONS. LATEST OBSERVATIONS AND MODEL DATA WOULD SUGGEST THAT MAXES WILL BE FINE. HOWEVER...IT LOOKS LIKE THE TEMPERATURES WILL BE AT THE LOW END OF THE FORECAST RANGE. .GLD...NONE. $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 240 PM EDT SUN APR 20 2003 .THE HERE AND NOW... TODAY KIND OF HAS THAT MUGGY THUNDERSTORM TYPE FEEL TO IT, AND SURE ENOUGH, A LINE OF BKN TSRA DEVELOPING OVER SWRN IND ATTM ALONG WITH ANOTHER SCT AREA OVER WRN KY/WRN TN. PARAMETERS COMING TOGETHER AHEAD OF STG 500MB WAVE FOR A BKN AREA OF TS TO AFFECT THE LMK FA LATE THIS AFTERNOON INTO THE EVE HOURS. AXIS OF RELATIVELY HIGH 3KM CAPE AND SFC-6KM SHEAR ASSOCIATED WITH DEVELOPING CONVECTION FROM WRN TN NWD INTO SWRN IND. PER 15Z RUC PW/OMEGA FIELDS, TS SHOULD COALESCE INTO LINEAR ELEMENTS AND TRANSLATE E/SEWD THRU FA OVER NEXT 6-9 HOURS. WITH DECENT AMOUNT OF DRY AIR ABOVE 800MB DAMAGING DOWNDRAFTS CERTAINLY A POSSIBILITY. WILL HAVE TO WATCH FOR ROTATION/SUPERCELL STRUCTURE OUT OF THESE INITIAL STORMS DEVELOPING ON CONVECTIVE ROLLS, COLOCATED WITH LCLS AOB 1KM AND 0-1KM ENVIRONMENTAL SRH AOA 150. .REST OF SHORT TERM... PER 12Z ETA, MID-LEVEL WAVE KICKS DIMINISHING CONVECTIVE SYSTEM OUT OF FA AFTER 5Z/MON, WITH A SOLID INVERSION TRAPPING MOISTURE BELOW 800MB A GOOD PART OF MON, WHERE I'LL GO WITH A 70% SKY COVER. WEAK LIFT ASSOC SECONDARY 500MB TROF AXIS SWINGS THRU FA MON NIGHT, COUPLED WITH A REGIONAL INCR IN PW VALUES AND SOME LOW-LEVEL CAPE (GFS FCSTS 44 J/KG AT 2AM TUE FOR KSDF), COULD YIELD SOME -SHRA OVER NRN PARTS OF LMK FA. HWVR FORCING WOULD HAVE TO PENETRATE RATHER STG INVERSION, LIMITING PCPN POTENTIAL, BUT WILL KEEP LOW CHC -SHRA AS IN CURRENT FCST FOR MON NIGHT. INVERSION HOLDS IN GFS/ETA FCST RAOB DATA HINTING THAT SKIES MAY BE SLOW TO CLEAR, ESP ACROSS NRN KY/SRN IND ON TUE. PER GFS, LOW-LEVELS DRY OUT TUE NIGHT AND WITH SFC HIGH OVER FA, COULD BE A FROSTY START TO WED? FORECASTING SUNSHINE WED AS MID-LEVEL RIDGE MOVES INTO REGION. .EXTENDED PORTION... RIDGING PATTERN ALOFT WILL CONTINUE WEDNESDAY NIGHT AND EARLY THURSDAY KEEPING THINGS QUIET WEATHERWISE. HOWEVER BY LATE THURSDAY STRONG 500 MB LOW PRES EJECTS INTO THE CENTRAL PLAINS WITH STRONG SURFACE LOW DEVELOPING BY THURSDAY NIGHT INTO THE SOUTHERN TN VALLEY. 12Z GFS SUGGESTS INVERTED SURFACE TROUGH INTO CENTRAL KY THU NIGHT WITH WAA PATTERN RAINS SPREADING INTO SRN KY AND TO A LESSER DEGREE NRN KY AND SRN IN. WILL HAVE A LOW CHANCE POP THU AFTN ACROSS THE FAR SOUTH...THEN CHANCE POPS ACROSS THE FA THU NIGHT AND FRIDAY. GIVEN ABUNDANT AVAILABLE GULF MOISTURE SOME GENEROUS RAINFALL AMOUNTS MAY OCCUR ESPECIALLY OVER THE SOUTHERN FA. THE FORECAST PERIOD FROM FRI NIGHT THROUGH SUNDAY WILL BE DRY WITH VERY SEASONABLE AND PLEASANT TEMPS. .LMK...NONE. CCS/JMB ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 1150 AM EDT SUN APR 20 2003 UPDATED ZFP/GRIDS ALREADY SENT. BAND OF T/RW MVG EWD THROUGH LMK FA ATTM ASSOC WITH SMALL-SCALE PIECE OF 500MB VORTICITY ROTATING AROUND MAIN TROF OVER MID-CONUS. PER 12Z RUC PW FIELDS, THIS BAND OF PCPN SHOULD LIFT EWD BY EARLY AFTERNOON, LEAVING MUCH OF FA WITH P/CLOUDY SKIES AND WARM TEMPERATURES. CERTAINLY SOME SCT AFTERNOON TSRA NOT OUT OF THE QUESTION IN THIS RELATIVELY UNCAPPED AIRMASS. QUESTION OF THE HOUR IS TS REDEVELOPMENT AND SVR POTL. RUC PW/OMEGA FIELDS SUGGESTING TS INITIATION OVER SRN IL/SWRN IN AFTER 18Z, RAPIDLY TAKING FORM OF A LINEAR SYSTEM. GIVEN MODEST 0-6KM SHEAR VALUES ASSOC WITH MID-LEVEL SPEED MAX AND 700MB OMEGA ORIENTATION, THIS SEEMS REASONABLE. PER SPC MESOANALYSIS WEBPAGE, ATMOSPHERE ALREADY DESTABILIZING ALONG MS RIVER UP INTO SW IND AHEAD OF FRONTAL BOUNDARY (SEEN NICELY IN VIS SATELLITE PIX OVER SERN MO). 3KM CAPE VALUES NEARING 50-100 J/KG AT THIS EARLY HOUR. OVERALL INGREDIENTS ARE THERE FOR SOME ISO-SCT SVR TS LATE AFTERNOON INTO EARLY EVENING. .LMK...NONE. XXV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 1050 AM CDT SUN APR 20 2003 COLD FRONT EXTENDING NEAR A HOT...TO TXK...TO GGG...TO UTS LINE THIS MORNING. THIN LINE OF SHOWERS CONTINUES TO DEVELOP ALONG THETA E AXIS LOCATED FROM THE TOLEDO BEND COUNTRY...INTO NORTHCENTRAL LOUISIANA. VERY ELEVATED SHOWERS AND ISOLATED THUNDERSTORMS ARE ALSO DEVELOPING BEHIND THE FRONT OVER PORTIONS OF NORTHCENTRAL TEXAS SOUTH OF THE METROPLEX...ASSOCIATED WITH SHORTWAVE SWINGING EAST FROM UPPER LOW OVER NEBRASKA. STRONG STORMS NORTH OF VCT APPEAR ROOTED ALONG FRONT IN AREA OF BEST MOISTURE CONVERGENCE...WITH SHORTWAVE ENERGY NOW PUSHING EAST INTO SE TX...AND INTO S LA THIS AFTERNOON. BOTH RUC AND NEW ETA SHOWING BEST CONVERGENCE STAYING SOUTH OF THE AREA...WITH PASSING SHORTWAVE. HOWEVER...FRONT IS EXPECTED TO SLOW ACROSS SW AR AND NE TX THROUGH THE AFTERNOON... REACHING AN ELD...TO SHV...TO OCH LINE BY 21Z. WILL UPDATE THE ZONES TO LOWER POPS TO SLIGHT CHANCE UP NORTH IN TXK GROUP...BUT WILL MAINTAIN GOING POPS FOR NE TX AND NCNTRL LA. WILL ALSO DROP MENTION OF SEVERE...AS BEST FORCING/CONVERGENCE SHOULD REMAIN TO THE SOUTH...AND LOW OVERCAST WILL INHIBIT HEATING. WILL ALSO HAVE TO LOWER TEMPS A CATEGORY OR SO DUE TO WEAK COLD ADVECTION OCCURRING ACROSS THE NW BEHIND THE FRONT...AND DENSE CLOUD COVER/SHOWERS AHEAD OF IT. UPDATE WILL BE OUT AROUND 1115 AM. 15 .SHV...NONE. $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1055 PM EDT SUN APR 20 2003 THE LATEST SURFACE CHART SHOWS A LOW PRESSURE SYSTEM CURRENTLY LOCATED OVER WESTERN UPPER MICHIGAN. AN ASSOCIATED COLD FRONT IS NOW LOCATED OVER EASTERN ONTARIO...WHICH MOVED OVER THE REGION EARLIER THIS EVENING AND GENERATED SHOWERS AND THUNDERSTORMS OVER MUCH OF LOWER MICHIGAN. THE APX 88D SHOWS GENERALLY DRY CONDITIONS OVER MUCH OF THE FORECAST AREA...WITH REGIONAL RADAR DATA SHOWING SCATTERED SHOWERS OVER WESTERN UPPER MICHIGAN AND PORTIONS OF THE UPPER MIDWEST. THE SHOWERS AND THUNDERSTORMS THAT OCCURRED EARLIER THIS EVENING ...FORMED IN A THTE RIDGE IN ADVANCE OF THE COLD FRONT. 850MB DEW POINTS IN THE THTE RIDGE...WERE BETWEEN 8C AND 10C...WITH THE LATEST RUC SHOWING 850 MB DEW POINTS FALLING TO AROUND 3C OVERNIGHT BEHIND THE FRONT. THE SHOWERS CURRENTLY OVER WESTERN UPPER MICHIGAN...ARE IN RESPONSE TO THE COMBINE EFFORTS OF SURFACE AND UPPER LEVEL FEATURES. SHORT TERM MODEL DATA SHOWS THE SURFACE STORM SYSTEM TO BE LOCATED OVER WESTERN LAKE SUPERIOR OVERNIGHT...WITH A WEAK SURFACE TROUGH MOVING OVER WISCONSIN. ADDITIONALLY...A 500 MB TROUGH AND VORT MAX WILL MOVE OVER THE UPPER MIDWEST OVERNIGHT...MOVING INTO THE WESTERN LAKES REGION BY 12Z MONDAY. CORRESPONDING 700/500 MB QVECTORS SHOWS A CONVERGENT PATTERN DEVELOPING OVER THE WESTERN LAKES REGION OVERNIGHT...IN ADVANCE OF THE 500 MB VORT. MODEL SOUNDINGS AND MOISTURE PROGS SHOW ABUNDANT LOW LEVEL MOISTURE LINGERING OVER THE UPPER LAKES OVERNIGHT...AS 850/700MB RH REMAINS AROUND 90 PERCENT. HOWEVER MID LEVELS WILL BE DRYING WITH 700/500MB RH DIMINISHING TO UNDER 30 PERCENT OVER NORTHEAST LOWER. 700/500MB RH WILL REMAIN AROUND 60 PERCENT OVER EAST UPPER AND NORTHWEST LOWER. THEREFORE WILL KEEP A MENTION OF RAIN SHOWERS OVER EAST UPPER AND NORTHERN WEST LOWER...WHILE KEEPING A MENTION OF DRIZZLE AND FOG OVER NORTHEAST LOWER. .APX...NONE. $$ SWR mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 340 PM EDT SUN APR 20 2003 PCPN TRENDS/PTYPE ARE THE MAIN FCST ISSUES TONIGHT/MON AND THEN CLOUDS/TEMPS THEREAFTER. WV IMAGERY/RUC ANALYSIS SHOW UPPER LOW REDEVELOPING NEWD TOWARD UPPER MI. 2 MAIN SHORTWAVES ARE EVIDENT WITH FIRST TAKING ON NEGATIVE TILT AS IT LIFTS INTO UPPER MI/LK SUPERIOR ON NE SIDE OF REDEVELOPING UPPER LOW. SECOND WAVE WAS ROTATING E THRU IA. AT THE SFC...LOW PRES WAS LOCATED NEAR KCMX WITH OCCLUDED FRONT EXTENDING SE TO NEAR KESC. WIDESPREAD SHRA REDEVELOPED ACROSS FCST AREA THIS MORNING AHEAD OF SHORTWAVE/OCCLUDED FRONT. SHRA ARE NOW DIMINISHING IN AREAL COVERAGE...ESPECIALLY EAST HALF AS DRY SLOT ARRIVES. AGAIN...MODELS ARE IN VERY GOOD AGREEMENT IN THE SHORT TERM WITH NGM/ETA/GFS SHOWING MID-UPPER LOW/TROF ONLY DRIFTING E ACROSS NWRN LAKES TONIGHT/MON. RESULT WILL BE AN UNSETTLED/CHILLY 24HRS AS WEAKENING DEFORMATION ZONE/CCB SLOWLY MOVES ACROSS AREA. PTYPE WILL BECOME AN ISSUE DUE TO COMBINATION OF CAA AND COLUMN COOLING UNDER FALLING HEIGHTS. ETA FCST SOUNDINGS AND 1000-850MB THICKNESS FROM GFS/NGM INDICATE MIX/CHANGEOVER TO SNOW TO OCCUR ROUGHLY AROUND MIDNIGHT W...PROGRESSING INTO CNTRL COUNTIES 09-12Z...AND E MON MORNING...BUT DAYTIME HEATING (THOUGH LIMITED) WILL WORK AGAINST CHANGEOVER E. BASED ON MODEL PCPN AMOUNTS OF GENERALLY 0.15 TO 0.25...(AS HIGH AS 0.35 IN UPSLOPE AREAS ON ETA)...SNOW ACCUMULATIONS SHOULD BE HELD TO 1 TO 2 INCHES. ITS POSSIBLE HIGHEST TERRAIN AREAS FAVORED BY STRONG NRLY UPSLOPE FLOW COULD SEE AS MUCH AS 4 INCHES. SINCE THERE IS UNCERTAINTY IN EXACTLY WHEN CHANGE TO SNOW WILL OCCUR AND SINCE SNOW WILL BE WET (LOW SNOW TO WATER RATIO)...WILL STAY WITH LOW END OF ROUGHLY 1 TO 2 INCHES TOTAL. A PORTION OF THE SNOW WILL FALL DURING DAYLIGHT HRS MON WHICH ALSO ARGUES FOR LOWER TOTALS. HOWEVER...WILL NEED TO KEEP AN EYE ON THIS AS IT APPEARS A WELL-DEFINED DEFORMATION ZONE IS TAKING SHAPE THIS AFTN...SUGGESTING HEAVIER THAN MODEL FCST PCPN AMOUNTS MAY BE IN THE OFFING. WITH BLUSTERY N WINDS ON MON OF 15-30MPH...TEMPS WILL HOLD IN THE 30S NEAR LAKE SUPERIOR...ESPECIALLY NW/NCNTRL WHERE PCPN WILL HAVE GREATEST COVERAGE THRU THE DAY. HIGHEST TEMPS IN THE MID 40S EXPECTED FOR DOWNSLOPE AREAS NEAR LAKE MICHIGAN. UPPER TROF DRIFTS FARTHER E MON NIGHT WITH INFLUX OF MUCH DRIER AIR ARRIVING FROM W AND NW. OTHER THAN SCT EVENING -SHRA/-SHSN E...WILL BRING CLEARING SKIES GRADUALLY FROM W TO E MON NIGHT/TUE MORNING. HOWEVER...ETA RH TIME SECTIONS SUGGEST POTENTIAL OF STRATUS IN UPSLOPE CNTRL AREAS TUE MORNING. NOT GOING TO BUY OFF ON THIS COMPLETELY GIVEN CLR SKIES THIS AFTN IN ONTARIO/MANITOBA TO THE W AND NW OF SYSTEM. FOR NOW...WILL JUST DELAY CLEARING A BIT IN THE UPSLOPE AREAS. DO EXPECT ALL AREAS TO BECOME SUNNY TUE AS LINGERING MOISTURE MIXES OUT INTO VERY DRY AIR ABOVE SFC (850MB DWPT DEPRESSIONS OF 20-30C). WILL BE ANOTHER COOL DAY TUE...ESPECIALLY NCNTRL/E WITH BRISK NRLY FLOW ACROSS LAKE SUPERIOR. EXPECT A COLD NIGHT TUE NIGHT UNDER CLEAR SKIES AND LIGHT/CALM WINDS AS SFC RIDGE AXIS ARRIVES. GFS MOS GUIDANCE LOOK REASONABLE FOR MINS. WED-SUN...GOING DRY FCST LOOKS ON TRACK FOR THIS PERIOD. YESTERDAYS MAIN PCPN ISSUE WAS ON NEXT IN THE RECENT SERIES OF CLOSED LOWS EJECTING E FROM THE SW CONUS MIDWEEK. GFS/CANADIAN/UKMET/ECMWF AGREE THAT THIS SYSTEM WILL HAVE NO IMPACT ON FCST AREA AS IT TRACKS WELL S OF HERE. THIS SRLY TRACK A RESULT OF STRONG HEIGHT RISES BTWN HUDSON BAY AND GREENLAND WHICH FORCES LOWER HEIGHTS/CLOSED LOW TO BECOME LOCKED IN OVER SE CANADA. THIS IN TURN SUGGESTS A MOSTLY DRY PERIOD WITH NEAR TO BLO NORMAL TEMPS AS NWRLY UPPER FLOW DOMINATES THE AREA. ONLY PCPN CONCERN IN THE WED-SUN PERIOD WILL BE POTENTIAL OF DAYTIME INSTABILITY SHRA THU AND/OR FRI AS FCST AREA IS BRUSHED BY COLD POOL ALOFT ASSOCIATED WITH ONE OR MORE SHORTWAVES ROTATING AROUND CLOSED MID/UPPER LOW OVER SE CANADA. FOR NOW...WILL CONTINUE TO MAINTAIN A DRY FCST AS CORE OF COLD AIR AND FORCING REMAINS E OF HERE. NEW TROF IS TO BEGIN HEADING INTO PLAINS EARLY NEXT WEEK... BRINGING A WARMUP HERE AS SWRLY FLOW DEVELOPS. WOULDN'T BE SURPRISED IF THIS IS DELAYED A BIT...BUT 06Z/12Z GFS RUNS ARE INSISTENT ON PROGRESSIVE NATURE. .MQT...GALE WARNING LAKE SUPERIOR. ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1056 AM EDT SUN APR 20 2003 THE MAIN FCST CONCERNS WITH THIS UPDATE FORECAST IS PRECIPITATION TREND AND TEMPERATURES FOR THIS AFTERNOON. RUC/ETA AND WATER VAPOR IMAGERY IS SHOWING A MID LEVEL LOW OVER SOUTHERN MINNESOTA. AS ONE SHORTWAVE WRAPPING AROUND THE BASE OF THIS LOW EXIT THE UPPER GREAT LAKES...ANOTHER DEEPER SHORTWAVE IS ENTERING WISCONSIN AND THE UPPER GREAT LAKES. SURFACE ANALYSIS INDICATE A CLOSED LOW OVER WESTERN UPPER MICHIGAN WITH A WARM FRONT EXTENDING OUT AHEAD OF IT AND IS OVER THE SOUTHERN U.P. THE LOW IS ALSO DRAGGING A COLD FRONT INTO WESTERN LAKE MICHIGAN. THIS LOW IS BEING PROPELLED EAST BY A BROAD RIDGE WHICH BLANKETS THE MID AND NORTHERN HIGH PLAINS. SEVERE WEATHER IS OCCURRING OVER WESTERN LOWER MICHIGAN JUST AHEAD OF THE COLD FRONT. MOISTURE OVER RUNNING OF THE WARM FRONT IS GENERATING SCATTERED SHOWERS AND AREAS OF FOG OVER UPPER MICHIGAN. THE SURFACE LOW WILL REACH THE KEWEENAW BAY BY LATE AFTERNOON DRAGGING THE COLD FRONT INTO CENTRAL U.P. AS THE MID LEVEL LOW REACHES NEAR ONTONAGON. SHORTWAVE ENERGY ROTATING AROUND THE LOW WILL RACE ACROSS UPPER MICHIGAN...WHILE NVA ENTERS SOUTHERN WISCONSIN. MOISTURE WRAPPING AROUND THE LOW WILL FEED THE UNSTABLE AIR OVER THE FORECAST AREA THIS AFTERNOON. ETA/RUC SHOWING THE STRONGEST Q-VECTOR CONVERGENCE WILL BE OVER NORTH OF LAKE SUPERIOR EARLY THIS AFTERNOON. THIS WILL SLIDE JUST INTO LAKE SUPERIOR BY LATE AFTERNOON. ALSO A FAIR AMOUNT OF CONVERGENCE WILL REMAIN OVER THE EASTERN U.P. AND LOWER MICHIGAN LATE THIS MORNING AND EARLY AFTERNOON. 300K ISENTROPIC ANALYSIS SHOWING THE GREATEST ASCENT TO THE OVER LOWER MICHIGAN AND EASTERN U.P. THIS AFTERNOON. IT APPEARS THAT THE HEAVIEST RAINFALL WILL REMAIN OVER THE SOUTHERN AND EASTERN U.P. THIS AFTERNOON. THE SOUTHERN AND EASTERN PART OF THE FORECAST AREA WILL BE UNDER THE NOSE OF THE EXIT REGION OF A 90 KNOT UPPER LEVEL JET. A LOW LEVEL JET AHEAD OF THE SURFACE LOW WILL REMAIN MAINLY OVER THE EASTERN U.P. A 50 KT LOW LEVEL JET WRAPPING AROUND THE BACK OF THE SURFACE LOW IS OVER CENTRAL ONTARIO. SURFACE DEW POINTS TO THE SOUTHWEST OF THE FORECAST AREA REMAIN IN THE 50S. THIS WILL ADVECT INTO THE FORECAST AREA. A SURFACE BASED WILL KEEP FOG IN THE AREAS. AS A COOL EAST WIND CONTINUES TO BLOW ACROSS THE KEWEENAW PENINSULA...THIS SHOULD KEEP THE TEMPERATURES LOW AND CONDUCIVE FOR FOG TO CONTINUE. VISIBLE AND IR SATELLITE IMAGERY SHOWING CLOUDS TO THE SOUTHWEST. PLOTTING THE MOVEMENT SHOULD KEEP CLOUDS OVER THE ENTIRE AREA THIS AFTERNOON...LIMITING ANY SOLAR HEATING. WILL KEEP CLOSE TO GUIDANCE. IR SHOWING SOME THIN SPOTS OVER CENTRAL WISCONSIN...WHICH TRANSLATE TO POSSIBLE BREAKS OVER THE SOUTHERN U.P. LATE THIS AFTERNOON. IF THIS OCCURS IT WILL ALSO WARM THE SURFACE AND WILL MORE LIKELY BREAK A THE CAP AND PRODUCE STRONG THUNDERSTORMS. THUS IT APPEARS THAT THE SHOWERS AND THUNDERSTORMS WILL OCCUR ACROSS THE FORECAST AREA THIS AFTERNOON...WITH THE HEAVIEST REMAINING ALONG THE LAKE MICHIGAN SHORE AND OVER EASTERN COUNTIES. SHOWALTER AND LI'S STILL SUGGEST THAT THESE WOULD NOT DEVELOP INTO SEVERE. AFTER THE LOW PASSES WIND WILL SWITCH TO THE WEST OVER THE WESTERN U.P. .MQT...DENSE FOG ADVISORY THIS THIS AFTERNOON MIZ001-003. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 550 AM CDT SUN APR 20 2003 RAIN IS OVER. GRIDS AND ZFP UPDATED ACCORDINGLY. 233A... CURRENTLY WATCHING DEFORMATION ZONE RAIN SPINNING ACROSS THE NORTHERN CWA. THE EXODUS OF THIS FEATURE...AS WELL AS CLOUDS AND TEMPS ARE THE MINOR CHALLENGES FOR THE SHORT TERM. THE BACK EDGE OF THE RAIN SHIELD IS MAKING DECENT PROGRESS TO THE EAST...AND HAVE ENDED RAIN CHANCES BY MID MORNING. HUGE AREA OF WRAP AROUND CLOUDS PROBABLY WILL HANG TIGHT THROUGH THE NIGHT THOUGH...SO HAVE NOT STARTED ANY CLEARING UNTIL CLOSE TO 12Z ON MONDAY. THIS IS PRETTY MUCH IN LINE WITH THE ETA. DUE TO THICK CLOUDS...HAVE NOT GONE WITH MUCH WARMING TODAY...AND AM SLIGHTLY BELOW GUID IN MOST LOCALES. REST OF FORECAST LOOKS ON TRACK AND HAVE NOT MADE MANY CHANGES. NEXT CHANCE FOR RAIN IS FOR MID WEEK. LATEST MODELS HAVE SPED THIS UP JUST SLIGHTLY...AND HAVE MIRRORED THIS IN THE GRIDS BY BRINGING PCPN INTO WESTERN ZONES BY WED EVENING INSTEAD OF AFTER MIDNIGHT. LVQ 215P.. MAIN CONCERN IS IN THE NEAR TERM WITH THE THREAT OF CONVECTION. ILL DEFINED FRONT HAS STALLED ALONG THE I-35 CORRIDOR WITH THE MORNING CONVECTION HAVING EFFECTIVELY STABILIZED THE AIRMASS ACROSS THE CWA. THE MORNING ETA IS USELESS AS IT DESTABILIZED THE MOST OF THE CWA THIS AFTERNOON WITH THE 15Z RUC LOOKING BETTER...HAVING PICK UP ON THIS MORNINGS CONVECTIVE COMPLEX. MOISTURE IMAGERY INDICATES UPPER LOW/STRONG SHORTWAVE IN THE OKLAHOMA PANHANDLE WHICH WAS PICKED UP WELL ON THE 18Z RUC. SURFACE LOW HAS DEVELOPED IN RESPONSE TO THIS FEATURE IN NORTHWEST OKLAHOMA. STRONG SHORTWAVE IS EXPECTED TO SHEAR ENE TONIGHT AS PER THE RUC. THIS IS IN LINE WITH THE OTHER SHORT RANGE MODELS...WHICH APPEARS REASONABLE GIVEN H3 STRUCTURE OF TROF. THE 18Z RUC IS SIMILIAR TO THE 15Z RUC IN THE HANDLING OF THE SURFACE FEATURES AND IS PREFERRED. BELIEVE SURFACE LOW IN NORTHWEST OKLAHOMA TO MOVE DUE EAST IN AXIS OF BEST INSTABILITY WITH THE FRONT ACROSS OUR CWA TO MOVE SLOWLY EAST THROUGH THE EVENING. DESPITE BEING RATHER STABLE AT THE SURFACE...PROFILERS CONTINUE TO INDICATE BRISK H8 FLOW. THIS SHOULD PROVIDE SUFFICIENT INFLOW FOR SHOWER AND THUNDERSTORM DEVELOPMENT AS FRONT MOVES SLOWLY SOUTHEAST. QG FORCING WITH UPPER TROF/SHORTWAVE TROF WILL ALSO PROVIDE FORCING BEHIND AND IN ADVANCE FRONT FOR RAIN SHOWER DEVELOPMENT. THUNDERSTORMS ARE ALREADY DEVELOPING IN SOUTH CENTRAL KANSAS. EXPECT THIS AREA TO EXPAND NORTHEAST RAPIDLY THIS EVENING. CANT RULE OUT THE POSSIBILITY OF ISOLATED SEVERE...PRIMARILY HAIL. LOCALLY HEAVY RAINFALL ALSO POSSIBLE. THE HEAVIEST RAINFALL SHOULD BE ACROSS THE SOUTHEASTERN HALF OF THE CWA. THIS IS THE PORTION OF THE CWA WHICH HAS SEEN THE LEAST AMOUNT OF RAIN TODAY...AND SHOULD BE ABLE TO HANDLE ANY LOCALLY HEAVY RAINFALL TONIGHT. THE PRECIPITATION SHOULD EXIT THE MUCH OF THE WESTERN CWA BY MIDNIGHT AND MAY LINGER ACROSS THE NORTHEAST CORNER THROUGH THE NIGHT...ALBIET QUITE LIGHT. FOR SUNDAY AND SUNDAY NIGHT...MODELS INDICATE THAT AS THE UPPER TROF MOVES TOWARD THE GREAT LAKES...SERIES OF SHORTWAVES TROFS TO MOVE ACROSS THE CWA. MAY SEE A FEW SPRINKLES ACROSS THE NORTHERN CWA SUNDAY NIGHT BUT WILL NOT MENTION AT THIS TIME. ETA GRIDS SHOW EXTENSIVE LOW CLOUDS THROUGH SUNDAY NIGHT WITH CLEARING SKIES ON MONDAY. WITH THE EXTENSIVE LOW CLOUDS ON SUNDAY...PLAN TO LOWER TEMPERATURES ON SUNDAY. OTHERWISE...PREFER FWC TEMPERATURES THROUGH THE PERIOD. DB MID-LEVEL RIDGE LOOKS TO REMAIN UPSTREAM ACROSS CENTRAL PLAINS THROUGH THE FIRST HALF OF THE WEEK...KEEPING FORECAST AREA DRY AND ALLOWING COOLER AIRMASS TO REMAIN IN PLACE ACROSS MUCH OF FORECAST AREA TUESDAY INTO WEDNESDAY. NEXT SHORTWAVE TROUGH PROGGED TO MOVE THROUGH THE REGION THURSDAY. RETURN FLOW AHEAD OF THIS WAVE MAY ALLOW PRECIPITATION TO SPREAD INTO WESTERN ZONES LATE WEDNESDAY NIGHT...WITH THREAT CONTINUING THROUGH THE DAY THURSDAY...ASSOCIATED WITH PASSAGE OF MID-LEVEL TROUGH. THIS IS REPRESENTED WELL IN GOING FORECAST...THUS HAVE ONLY MADE MINOR CHANGES. MS .EAX... KS...NONE. MO...NONE. mo AREA FORECAST DISCUSSION...MESOSCALE UPDATED NATIONAL WEATHER SERVICE NORTH PLATTE NE 145 PM CDT SUN APR 20 2003 SUSTAINED WINDS OF 30 TO 35 MPH WITH LOCAL GUSTS TO 45 MPH BEING REPORTED BY AREA METARS JUST WEST OF CLOUD SHIELD WHERE MIXING IS STRONGLY EVIDENT. RUC MODEL SHOWING SURFACE WINDS INCREASING SLIGHTLY OVER THE NEXT HOUR...THEN DECREASING AFTER 400 PM CDT. UPDATED ZONE FOR WIND ADVISORY. .LBF...WIND ADVISORY PORTIONS OF NORTH CENTRAL...CENTRAL AND SOUTHWEST NEBRASKA THROUGH 400 PM CDT. 44/DB ...FORECAST CHALLENGES HIGHLIGHTED BY LOW POPS THIS AM WITH EXITING SYSTEM...THEN MIDWEEK SYSTEM... H5 PATTERN TONIGHT REMAINS HIGHLY AMPLIFIED WITH CUTOFF LOW W OF BERMUDA...POS TILTED RIDGE PARALLELING THE APPALACHIANS...MASSIVE TROF ACROSS THE CENTER OF THE U.S. WITH RIDGING ACROSS THE WRN THIRD OF THE CONUS. CLOSER TO HOME...MAJOR FEATURE TONIGHT IS THE CUTOFF LOW OVR CENTRAL SD WITH ANOTHER VERY STRONG SHORTWAVE ACROSS SRN KS AND NRN OK. FOR THE MOST PART...WEATHER SCENARIO ON THE HIGH PLAINS HAS PLAYED OUT AS ADVERTISED WITH LAST NIGHT'S GFS AND ETA RUNS. INITIAL GLANCE OUT TO 60 HRS SHOWS DECENT AGREEMENT WITH GFS AND ETA WITH THE EXCEPTION OF MON NIGHT. AVN STILL TRYING TO GENERATE PCPN MON NIGHT UNDERNEATH THE RIDGE. .TODAY THROUGH MONDAY NIGHT...WEAK VORT ADVECTION CONTINUES ON BACK SIDE OF EXITING LOW TODAY...THIS WILL SUSTAIN CLOUDINESS OVR MOST OF THE FA THROUGH MOST OF THE DAY IN THE ERN ZONES. FARTHER WEST...COULD SEE SOME BREAKS DURING THE AFTN. AM PLANNING TO DROP PRECIP CHANCES IN THE NORTH AND EAST AND GO WITH JUST SPRINKLES. WITH CLEARING IN THE WEST DURING THE AFTN...THE WIND WILL BECOME A FACTOR. HIGH RES ETA ADVERTISING 30 KTS AT H85 THIS AFTN WITH UNIDIRECTIONAL COMPONENT EXTENDING TO THE SFC...THIS SHOULD EQUATE TO AT LEAST 20 TO 30 MPH WINDS. LUCKILY IN THE EAST...A LACK OF CLEARING WILL SUPPRESS THE MIXING POTENTIAL. AFTER TODAY...NEXT 24 TO 36 HRS FAIRLY TRANQUIL WITH RIDGING ALOFT AND HIGH PRESSURE OVHD. WILL LOOK FOR OVRNIGHT LOWS IN THE UPPR 20S FAR WEST TO THE MID 30S EAST...WITH CLEAR SKIES AND LIGHT WRLY WINDS. GFS AND ETA SOLNS DIVERGE ON PRECIP FORMATION MON NIGHT WITH THE AVN DEMONSTRATING ITS USUAL WET BIAS WITH H85 DEW POINTS 2 TO 5 DEG C HIGHER. WILL CONTINUE DRY FCST WITH ONLY HIGH AND MID LVL CLOUDINESS BEGINNING TO ENTER SWRN ZONES LATE. .MIDWEEK...STRONG H85 S SERLY JET STRENGTHENS ON TUESDAY WITH MOIST TAP TO THE GULF OPENING UP. WITH UNIDIRECTIONAL WINDS TO THE SFC...LOOKS TO BE A WINDY ONE ON TUESDAY. LATE IN THE DAY INITIAL SHORTWAVE ENTERS HIGH PLAINS. SHOULD SEE SOME RESULTANT CONVECTION IN THE AFTN/EVE HRS. DYNAMICS FAIRLY WEAK TUES NIGHT AS JET STREAK STILL WELL OFF TO THE SW. PCPN CHANCES...AS WELL AS SVR THREAT MORE SUBSTANTIAL ON WED AS UPPR LOW DIGS INTO THE CENTRAL ROCKIES. JET DYNAMICS AS WELL AS GOOD DIFLUENT FLOW AT H5 SHOULD SUPPORT TSRAS BY LATE AFTN/EVE. CLOSER TO THE SFC...AVN INDICATING WELL ESTABLISHED DRY LINE FROM OGA SOUTH BY AFTN WITH H85 DEW POINTS OF 8+C SURGING AHEAD OF THIS FEATURE. WILL CONTINUE TO HIGHLIGHT SVR POSSIBILITIES IN THE HWO. .THURSDAY AND BEYOND...BROKEN RECORD PATTERN CONTINUES WITH EXITING WRAP AROUND ON THURSDAY...BRIEF REPRIEVE ON FRIDAY THEN ANOTHER MAJOR SYSTEM TAKING AIM ON THE FA SATURDAY...WITH ANOTHER WASHED OUT WEEKEND ON TAP. NO MAJOR CHANGES MADE OTHER THAN TO MENTION THUNDER ON THURSDAY GIVEN DECENT NEG LI'S DEPICTED WITH THE GFS SOLN. CLB ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 912 PM EDT SUN APR 20 2003 PUBLIC: SKIES ARE MOSTLY CLEAR WITH A HINT OF A CLOUD DECK BETWEEN 4500 AND 5000 FT FROM NEAR FLO TO SW OF GSO. RUC AND ETA PROFILE SHOWING BETTER MOISTURE FOR LOW CLOUD DEVELOPMENT AND THIS DECK SHOULD STAY MAINLY OVER WESTERN PORTIONS OF THE AREA. ALSO, WITH CLEAR SKIES ALONG THE COAST WILL INTRODUCE PATCHY FOG ALONG THE COAST. MARINE: EXPECT GENERALLY LIGHT WINDS ACROSS THE WATERS TONIGHT AS HIGH PRES RIDGES DOWN THE COAST. LONG PERIOD SWELLS CONTINUE TO AFFECT THE WATERS...WITH SEAS AT FRYING PAN SHOALS AND EDISTO AT 6 AND 5 FT RESPECTIVELY...BOTH WITH A 13 SECOND PERIOD. WW3 DATA LOOKS ON TRACK AND AS A RESULT WILL CONTINUE THE SMALL CRAFT ADVISORY NORTH OF LITTLE RIVER INLET...BUT WILL GO WITHOUT ANY HEADLINES FARTHER SOUTH (WILL NOT MENTION SCEC DUE TO THE WAVE PERIOD). WILL ALSO ADJUST SWELL DIRECTION TO INDICATE MORE OF AN EASTERLY COMPONENT. OTHERWISE...FORECAST LOOKS GOOD. PRELIMINARY NUMBERS... ILM 49 76 60 75 / 0 20 40 0 LBT 49 78 57 76 / 0 40 40 0 FLO 52 79 59 77 / 0 40 40 0 MYR 52 72 61 75 / 0 40 40 0 .ILM... .NC...SMALL CRAFT ADVISORY AMZ250-252. .SC...NONE. PUBLIC: HAWKINS MARINE: JAQ ------------PREVIOUS DISCUSSION 155 PM SUN APR 20 ----------------- N-NW SFC PRESSURE GRADIENT IN PLACE ACROSS EASTERN CAROLINAS AS STRONG LOW PRES CONTINUES TO SIT AND SPIN NEAR 70 W. MOST OF ILM CWA HAS SEEN A DECENT AMOUNT OF SUNSHINE THIS AFTERNOON...WHILE LOW CLOUDS HOLD ON OVER WESTERN HALF OF SC. LOW PRES TO FINALLY GET ITS ACT TOGETHER AND MOVE OUT OF THE PICTURE TONIGHT AND MON...AS APPROACHING COLD FRONT WILL SHOVE SFC RIDGE AXIS OFFSHORE. SHOULD COOL OFF NICELY TONIGHT...WILL FCST MINS NEAR PERSISTENCE. DECENT WARMUP MON AHEAD OF COLD FRONT. SHOULD ALSO SEE RESPECTABLE MOISTURE...SO WILL BUMP HIGHEST POPS UP TO 40 (MON AFTERNOON AND NIGHT INLAND...JUST MON NIGHT ON THE COAST). GFS PUSHES THE FRONT THRU BETWEEN 06-12Z TUE...WHILE ETA TAKES ITS TIME. IN ANY CASE SHOULD BE DRY TUE...WITH MAX TEMPS CLOSE TO MON NUMBERS. COOL AIR ARRIVES IN EARNEST WED...WITH ETA/GFS THICKNESS VALUES ONLY SUPPORTING 65-70. WILL GO NO WARMER THAN MEX NUMBERS. OFFSHORE FLOW WILL INHIBIT SEA BREEZE DEVELOPMENT TUE-WED. EXTENDED: PATTERN OF MILD DAYS AND COOL NIGHTS CONTINUES INTO FRI. NEXT FRONT TO BRING SLIGHT CHC POPS LATE FRI INTO SAT. TEMPS NEAR CLIMO FOR THE WEEKEND. WILL ONLY MAKE MINOR TWEAKS TO GOING FCST. MARINE: WINDS WILL DECREASE AND SEAS WILL GRADUALLY SUBSIDE TONIGHT AS HIGH PRESSURE MOVES EAST OVER THE COASTAL WATERS. EXPECT TO CONTINUE SMALL CRAFT ADVISORY FOR ALL MARINE ZONES TONIGHT AS LONG PERIOD SWELL FROM WESTLANT SYSTEM WILL CONTINUE TO MOVE INTO THE FCST AREA. RESIDUAL SWELL FROM THIS SYSTEM ON MONDAY WILL KEEP SEAS UP AROUND 4 TO 5 FT. PUBLIC: RAS MARINE: KREITNER nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 945 AM EDT SAT APR 19 2003 .UPDATE...TO LOWER MAX AFTERNOON TEMPS BY 1 CATEGORY ALL BUT SOUTHEAST TIER OF CWA. .DISCUSSION...LEFT OVER FROM THE CAD EVENT...SEE "RESIDUAL COOL POOL" SIGNATURES IN SURFACE ANALYSIS AND GSO RAOBS. BAGGY SURFACE LOCALLY AS PARENT HIGH WELL NORTHEAST CONTINUES TO RETREAT. LOW LEVEL MOISTURE AND EASTERLY LOW LEVEL FLOW (GSO RAOB) WITH HIGH CLOUDS ALOFT. NET EFFECT...WILL LOWER DAYTIME HIGHS 1 CATEGORY FROM CURRENT FORECAST ALL BUT SOUTHEASTERLY TIER OF CWA. EAST OF RAH..LOW LEVEL NORTHERLY FLOW AND ABSENCE OF LOW LEVEL MOISTURE SEEN IN MHX RAOB. RUC SUGGESTS AN EASTERLY COMPONENT TO LOW LEVEL FLOW FROM RAH WEST. LOWERING TEMPS 1 CATEGORY DOES NOT TAKE TEMP GRIDS OUT OF LINE. .RAH...NONE. KK nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 945 AM CDT SUN APR 20 2003 WATER VAPOR IMAGERY SUPPORTING MODEL DATA WITH TWO DISTINCT UPPER LOWS ACROSS REGION THIS MORNING...ONE LIFTING INTO NORTHERN GREAT LAKES WITH ANOTHER ENTERING FAR SOUTHEAST SOUTH DAKOTA. RUC/MESOETA STILL SHOWING SOME MODERATE LOW AND MID LEVEL THETA-E ADVECTION WRAPPING AROUND UPPER LOW IN DEFORMATION ZONE. RUC DATA ALSO SUGGESTING FAIRLY NARROW ZONE OF STRONGER WINDS THIS AFTERNOON IN VICINITY OF STRONG LOW LEVEL HEIGHT GRADIENT AND WHERE BETTER MIXING LIKELY WITH PARTIAL CLEARING THIS AFTERNOON ACROSS WESTERN CWA. CURRENT FORECAST HAS THESE HIGHER WINDS COVERED. UPDATED MAINLY TO ACCOUNT FOR PRECIPITATION. THETA-E RIDGE GRADUALLY SHIFTS EASTWARD THIS AFTERNOON AND UPSTREAM RADAR AT KMVX SHOWING DECENT COVERAGE TO LIGHT RAIN AREA WITH THIS FEATURE. HAVE UPPED POPS TO LIKELY FROM K8D3 TO KATY. UPDATED FORECAST HAS BEEN SENT. .ABR...NONE. MARSILI sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 353 AM EDT MON APR 21 2003 PCPN TRENDS/PTYPE...AND SNOW ACCUMS ARE MAIN FCST CHALLENGES TODAY AND TONIGHT...AND THEN CLOUDS/TEMPS THEREAFTER. SATL IMAGERY/RUC ANALYSIS SHOW VERTICALLY STACKED LOW OFF THE TIP OF THE KEWEENAW PENINSULA WHILE A SHRTWV ROTATES THRU BASE OF UPR TROF INTO ERN IA. OCCLUDED FRONT EXTENDS FM LOW OFF TIP OF KEWEENAW SE TO NEAR KISQ WHILE A COLD FRONT EXTENDS SW THRU IWD TO MSP. RADAR LOOP SHOWS EDGE OF DEFORMATION ZONE PCPN FROM CNTRL LAKE SUPERIOR THRU KEGV TO KRST EXTENDING BACK INTO THE MN ARROWHEAD. RAIN ALREADY MIXING WITH SNOW OVER HIGHER TERRAIN OF WEST AND NCNTRL U.P. TODAY...MODELS STILL IN GOOD AGREEMENT TAKING SHRTWV AND ASSOC 90 KT UPR JET MAX OVR LWR MIDWEST AND MOVG IT THRU LWR MI THIS MORNING THEN INTO QUEBEC THIS EVENING. AS A RESULT...UPR TROF AND LOW WILL LIFT SLOWLY EAST AS COLD FRONT AND WEAKENING DEFORMATION ZONE/CCB SLOWLY MOVES ACROSS AREA. CAA AND FALLING HEIGHTS/THCKNS BEHIND THE LOW WILL RESULT IN PCPN CHANGEOVER FM RAIN TO SNOW EARLY THIS MORNING WEST AND NCNTRL COUNTIES AND LATE MORNING ERY AFT EAST. ETA 1305M 1000-850MB THICKNESS LINE SEEMS TO AGREE BEST WITH WHERE RAIN/ SNOW LINE IS RIGHT NOW LOOKING AT SFC OBS REPORTING SHSN IN PAST HR. THUS WILL USE THIS THCKNS LINE AND ETA SNDGS TO GAUGE TIMING OF PCPN CHANGEOVER FROM WEST TO EAST THIS AFT. LIMITED DAYTIME HEATING MAY DELAY CHANGEOVER FOR CNTRL AND ERN COUNTIES AND IN COMBINATION WITH WARM GROUND COULD LIMIT SNOW ACCUMS. MODEL QPF AMOUNTS GENERALLY .10 TO 0.20 INCH...(AS HIGH AS 0.30 IN OVR UPSLOPE AREAS NCNTRL U.P. ON ETA). BUT AGAIN...GIVEN THAT SNOW WILL BE FALLING MAINLY DURING DAY...MELTING AND WARM GROUND SHOULD LIMIT WET ACCUMS TO 1-2 INCHES...MAINLY OVR HIGH TERRAIN OF MQT-BARAGA COUNTIES. BLUSTERY N WINDS 15-30 MPH WILL HOLD TEMPS IN THE 30S NEAR LAKE SUPERIOR...ESPECIALLY NW/NCNTRL WHERE EARLIER ARRIVAL OF COLD AIR AND GREATER COVERAGE OF PCPN WILL HAVE GREATEST IMPACT ON LOWERING TEMPS. HIGHEST TEMPS IN THE MID 40S ARE EXPECTED FOR DOWNSLOPE AREAS NEAR LAKE MICHIGAN. TONIGHT AND TUESDAY...UPPER TROF DRIFTS FARTHER E AS MODEL SNDGS SHOW INFLUX OF MUCH DRIER AIR ARRIVING FROM NW OF LAKE SUPERIOR. OTHER THAN SCT EVENING -SHRA/-SHSN EAST HALF TONIGHT...WILL KEEP TREND OF CLEARING SKIES GRADUALLY FROM W TO E TONIGHT INTO TUE MORNING. ETA SNDGS AND RH TIME SECTIONS STILL INDICATE LOWER STRATUS DECK HANGING OVER UPSLOPE AREAS OF CNTRL AND ERN COUNTIES TUE MORNING...SO WL KEEP MENTION OF MORE CLDS THERE TUE MORNING. MODEL SNDGS DO SHOW ALL AREAS BREAKING OUT INTO SUNSHINE BY TUE AFT WITH MASSIVE SUBSIDENCE/RDGG FM WEST AS ETA FCST SNDGS SHOW 850MB DWPT DEPRESSIONS OF 20-30C. COOL CONDITIONS WILL LINGER INTO TUE WITH BRISK NLY FLOW OFF LAKE SUPERIOR INTO NCNTRL/ERN PORTIONS AND 850 MB TEMPS OF -2 TO -3C. WILL KEEP TUE MAXES IN LOW 40S ALG LAKE SUPERIOR AND AROUND 50 ALG WI BDR COUNTIES. BRISK NLY WINDS MON NIGHT WILL MODERATE TEMPS MORE ALG GREAT LAKES DESPITE CLRG SKIES WILL KEEP TEMPS IN LOW 30S ALG GRT LAKES AND MID 20S ALG WI BDR COUNTIES. TUESDAY NIGHT AND WEDNESDAY...WINDS DIE OFF AS SFC RDG AXIS FM WRN ONTARIO MOVES OVR AREA. GFS MOS GUIDANCE FCST TEMPS LOOK REASONABLE WITH READINGS FALLING NR DWPNTS OF LOW 20S OVR INLAND AREAS AND UPPER 20S ALG LAKESHORE AREAS. BLDG 850 MB RDG FM WEST WL MODERATE TEMPS SOMEWHAT FOR WED WITH 850 MB TEMPS RISING FM 2C WEST TO -1C EAST. WITH GO WITH RANGE FM UPPER 40S ALG GRT LAKES SHORELINES AS LAKE BREEZES DVLP UNDER SFC RDG TO UPPER 50S INLAND AREAS ALG WI BDR...THIS ALSO IN LINE WITH GFS MOS GUIDANCE. .MQT...GALE WARNING LAKE SUPERIOR. VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1050 AM EDT MON APR 21 2003 PRIMARY CONCERNS ARE AFFECTS OF SFC LOW OVR LAKE SUPERIOR SFC ANALYSIS AND RADAR LOOP DEPICTING SFC LOW OVR SERN LK SUPERIOR (BWTN CARIBOU ISLAND AND UPR MI SHORE). BAND OF PCPN ALONG COLD FRONT IS PRESSING INTO ERN CWA ATTM. ERY/ISQ REPORTING ALL LIQUID WITH THIS WITH T/TD OF 41/39F AT ERY. RADAR BEGINNING TO FILL IN NICELY OVR WRN/CENTRAL UPR MI AS STRONG N WINDS (15 TO 30 MPH) BEGIN TO TRANSPORT COLDER AIR ACROSS LK SUPERIOR. GENERALLY ALL SNOW OVR WRN HALF OF UPR MI ALTHOUGH WEB CAM FM HOUGHTON AND DOWNTOWN MARQUETTE SUGGESTS THAT RAIN IS PREDOMINANT TYPE AS SFC LAYER IS JUST WARM ENOUGH (AROUND 36F). RETURNS POPPING OVER 30DBZ OVR HIGHER TERRAIN AND LOOK OUT OFFICE WINDOW SHOWS DECENT SNOW OCCURRING. HOWEVER...WARM GROUND AND DAYTIME INSOLATION (ALTHOUGH VERY LITTLE DUE TO LOW STRATUS) IS PROHIBITING SIG ACCUM (JUST A COATING). VIS SAT/SFC OBS/RADAR SHOW MOISTURE REACHING AS HIGH AS 11KFT. ETA/RUC RH PROGS GENERALLY 6-9HR SLOW WITH CLEARING COMPARED WITH OBS OVR MN. INTERPOLATION OF MODEL DATA WOULD BRING CLEARING INTO FAR SW AFT 18Z AND OVR MUCH OF WRN HALF OF CWA BY 00Z. ETA DOES HINT AS KEEPING SUB 900MB MOISTURE OVR ALL OF CWA THROUGHOUT DAY AND WITH STEADY N WIND FLOWING OFF LK SUPERIOR AND SUCH LOW DEWPOINT DEPRESSIONS CURRENTLY...THINK THAT WILL BE THE WAY TO PROCEED. CURRENT GRIDS HAVE SITUATION HANDLED WELL. IN UPDATED GRIDS DID BRING P/C SKIES INTO SW LATE TODAY...AND BESIDES EARLY STEADIER PCPN OVR ERN ZONES...WENT SCT RA/SN FOR REST OF DAY. MAX T WILL GENERALLY REMAIN STEADY WITH CURRENT 30S READINGS. HOWEVER...OVR FAR SW WITH ANY SUNSHINE COULD SEE TEMPS RISE INTO 40S LATE THIS AFTN (PER MIXING TO 925MB). .MQT...GALE WARNING LAKE SUPERIOR. JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1000 AM EDT MON APR 21 2003 STRENGTHENING UPPER TROF WILL BE MOVING SLOWLY TOWARD THE NORTHEAST DURING THE NEXT FEW DAYS WITH A VERY UNSETTLED WEATHER PATTERN. FIRST IN A SERIES OF SHORT-WAVES WILL BE MOVING NORTHEAST ACROSS NE PA AND CENTRAL NEW YORK LATER TODAY. THE ATM IS STILL RATHER DRY THIS MORNING...WITH 30S DEW PTS OVER THE EASTERN AND CENTRAL COUNTIES AND 40S ACROSS THE WEST. A 30 KT LOW-LVL JET WILL BEGIN TO MOVE INCREASING AMOUNTS OF LOW-LVL MOISTURE NE TOWARD THE AREA LATER TODAY AND TONIGHT. A WEAKENING COLD FRONT WILL MOVE ACROSS THE AREA LATE TODAY...WITH A STRONGER FRONT EXPECTED ON TUESDAY. LATEST RUC40 FORECASTS SHOW AN AREA OF MODERATELY STRONG LIFT MOVING ACROSS THE AREA AROUND 21Z... SO EXPECT THAT WILL BE THE MOST LIKELY TIME FOR SHOWERS DURING THE NEXT 12 HOURS. RUC LI'S REMAIN ABOVE ZERO ACROSS THE ENTIRE AREA THROUGH TODAY...WITH THE ZERO LINE BARELY GETTING INTO CENTRAL PA. BUFKIT SOUNDINGS CONFIRM THAT INSTABILITY WILL BE LACKING. ETA MID-LEVEL LAPSE RATES APPROACH 7 DEGREES C/KM LATER TODAY SO STILL CAN'T RULE OUT A FEW RUMBLES OF THUNDER ESPECIALLY SOUTHWEST. WIND FIELDS ARE IMPRESSIVE BUT NOT MUCH CONCERN ABOUT SEVERE WEATHER WITH LITTLE INSTABILITY. BASED ON THIS CURRENT FORECAST OF SHOWERS LIKELY WITH THUNDER POSSIBLE STILL SEEMS REASONABLE. WILL BE UPDATING THE ZONES MAINLY TO REMOVE MORNING WORDING. EXPECT NEW ZFP BY AROUND 1030 AM. .BGM...NONE. MSE ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA ISSUED BY NWS PITTSBURGH PA 1115 AM EDT MON APR 21 2003 COLD FRONT CONTINUING TO MOVE SLOWLY THROUGH EASTERN OHIO...AND WILL CROSS INTO THE CENTRAL PENNSYLVANIA MOUNTAINS DURING MID AFTERNOON. LATEST RUC SHOWS INCREASING INSTABILITY...SO THIN LINE OF SHOWERS CURRENTLY ASSOCIATED WITH THE FRONT...CAN RAPIDLY DEVELOP INTO THUNDERSTORMS THIS AFTERNOON OVER WESTERN AND CENTRAL PENNSYLVANIA. SO MENTION OF DAMAGING WINDS WITH THUNDERSTORMS KEPT. ALSO INTRODUCED MENTION OF HAIL PER LOWERED WET BULB ZERO. REST UNCHANGED. ...GIORDANO/REED .CTP... PA...SPS FOR SLGT RISK SVR TODAY WRN ZONES. pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1115 AM EDT MON APR 21 2003 COLD FRONT CONTINUING TO MOVE SLOWLY THROUGH EASTERN OHIO...AND WILL CROSS INTO THE CENTRAL PENNSYLVANIA MOUNTAINS DURING MID AFTERNOON. LATEST RUC SHOWS INCREASING INSTABILITY...SO THIN LINE OF SHOWERS CURRENTLY ASSOCIATED WITH THE FRONT...CAN RAPIDLY DEVELOP INTO THUNDERSTORMS THIS AFTERNOON OVER WESTERN AND CENTRAL PENNSYLVANIA. SO MENTION OF DAMAGING WINDS WITH THUNDERSTORMS KEPT. ALSO INTRODUCED MENTION OF HAIL PER LOWERED WET BULB ZERO. REST UNCHANGED. ...GIORDANO/REED .PBZ... MD...NONE. OH...NONE. PA...NONE. WV...NONE. pa EASTERN WASHINGTON AND NORTH IDAHO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WASHINGTON 900 AM PDT MON APR 21 2003 .SYNOPSIS...A DEEP UPPER LEVEL TROUGH JUST OFF THE PACIFIC COAST WILL SEND WARM AIR UP FROM THE SOUTH INTO EASTERN WASHINGTON TODAY. ALONG WITH THE UNSEASONABLY WARM TEMPERATURES WILL COME THE RISK OF AFTERNOON SHOWERS AND THUNDERSTORMS ESPECIALLY SOUTH AND WEST OF SPOKANE. AS A WEAK COLD FRONT SLIDES ACROSS THE REGION...EXPECT TEMPERATURES TO COOL MODERATELY TUESDAY AND WEDNESDAY WITH A CHANCE OF MAINLY MOUNTAIN SHOWERS. .DISCUSSION...TODAY INTO TONIGHT...SSE FLOW ALOFT IS USHERING MID AND HIGH LEVEL MOISTURE INTO THE REGION. RADAR HAS BEEN PICKING UP WHAT LOOKS LIKE SCT SHOWERS ACROSS THE LOWER BASIN INTO THE CASCADES... ALTHOUGH NO PCPN HAS BEEN REPORTED BUT VIRGA HAS. KOTX SOUNDING SHOWS LAYER OF OF INSTABILITY BELOW A CAP AT 550 MB TO ABOUT 650 MB. THE SOUNDING LOOKS QUITE DRY FROM THIS LEVEL TO THE SURFACE...EVEN DRIER THAN THE 6Z BUFR SOUNDINGS INDICATED. THE DRIER SUB CLOUD LAYER...THE NE SFC FLOW AND THE CURRENT RUC QPF WOULD KEEP ANY MEASURABLE PCPN OUT OF SPOKANE AND AREAS NORTH AND EAST TODAY. WOULD SEE THE BEST CHANCE...ALBEIT VERY LIGHT...TO REMAIN TO THE SOUTH AND WEST...FROM THE LWS AREA...THE BLUES...ACROSS LOWER BASIN INTO CENTRAL CASCADES. WILL CONTINUE THE MENTION OF THUNDER THIS AFTERNOON AND EVENING FOR THIS AREA AS WELL WITH DAYTIME HEATING AND ARRIVAL OF A WEAK WAVE AFTER MIDDAY. WILL SHOWERS GRADUALLY INCREASE OVERNIGHT INTO TUES MORNING WITH THE MAIN TROUGH AXIS SHIFTING THROUGH THE REGION. KOTX 850MB TEMP WAS +13...QUITE A BIT WARMER THAN EXPECTED. SFC TEMPS ARE 5-7 DEGREES HIGHER THAN YESTERDAY ESPECIALLY FOR AREA NORTH AND EAST OF SPOKANE. WILL BUMP UP HIGHS AND PUSH SPOKANE JUST ABOVE THE 70 DEGREE MARK THIS AFTERNOON FOR THE FIRST OF THE SEASON. UPDATES TO THE ZFP AND SFPS ARE FORTHCOMING. -RFOX. ...THE INFORMATION IN THIS PRODUCT CONCERNING WARNINGS AND FORECASTS IS VALID ONLY AT THE TIME OF ISSUANCE. THE LATEST WARNING AND FORECAST INFORMATION WILL BE FOUND IN THE APPROPRIATE PRODUCTS... GEG 071/046/063/042/062 133-1 COE 072/043/064/039/061 133-1 PUW 069/042/062/041/062 233-1 LWS 074/049/066/043/067 23211 CQV 074/041/066/039/065 13322 SPT 072/042/063/039/062 -3322 WWP 069/040/061/040/060 23322 MWH 069/041/066/040/066 432-1 EAT 067/046/067/042/065 432-2 OMK 070/042/066/039/065 232-2 .OTX...NONE. $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 409 PM EDT MON APR 21 2003 MAIN CONCERN WITH THIS FORECAST ARE THE PRECIPITATION POTENTIAL AND WINDS TREND FOR TONIGHT. WATER VAPOR IMAGER/RUC AND ETA SHOWING A CLOSED LOW OVER EASTERN LAKE SUPERIOR. SHORTWAVES ARE ROTATING THROUGH THE BASE OF THIS LOW. ONE IS OVER THE EASTERN U.P. AND ANOTHER IS OVER CENTRAL WISCONSIN. WATER VAPOR AND VISIBLE IMAGERIES DEPICT DRY AIR OVER WESTERN LAKE SUPERIOR FOLLOWING THE LOW AS IT MOVES EAST OF THE UPPER GREAT LAKES. SURFACE ANALYSIS SHOWING A HIGH OVER SOUTHERN HUDSON BAY WITH A RIDGE STRETCHING SOUTH ACROSS THE NORTHERN AND CENTRAL PLAINS...WHILE A TROUGH IS DEVELOPING OVER THE ROCKIES. A SURFACE LOW THAT WAS OVER THE UPPER GREAT LAKES THIS MORNING HAS MOVED INTO SOUTHWEST QUEBEC DRAGGING THE ASSOCIATED COLD FRONT INTO THE LOWER GREAT LAKES. A LOW LEVEL JET WRAPPING AROUND THE BACKSIDE OF THE LOW IS OVER WESTERN LAKE SUPERIOR. WRAP AROUND MOISTURE IS STILL OVER THE CENTRAL AND EASTERN PART OF THE U.P. A STRONG UPPER LEVEL JET MAX IS OVER THE LOWER GREAT LAKES RACING ACROSS QUEBEC. WITH THE DEPART OF THE EASTERN LAKE SUPERIOR LOW...DRIER AIR AND SIGNIFICANT ISENTROPIC DESCENT AND Q-VECTOR DIVERGENCE IS SPREADING INTO THE WESTERN U.P. -RA HAVE ENDED OVER KIWD AND KCMX ALREADY. THE LOW OVER EASTERN LAKE SUPERIOR WILL WEAKEN AS IT ROTATES INTO SOUTHEAST ONTARIO TONIGHT. A WEAK SHORTWAVE WILL SLIDE INTO EASTERN LAKE SUPERIOR AND ONTARIO OVERNIGHT. ANOTHER SHORTWAVE WILL SLIDE DOWN THE LEE OF THE NORTHERN PLAINS RIDGE AND WILL BE OVER WESTERN ONTARIO. THE SURFACE RIDGE WILL PUSH INTO THE UPPER MISSISSIPPI VALLEY ALONG WITH DRIER AIR. THAT SNOW WILL SUBSIDE FROM WEST TO EAST OVER THE FORECAST AREA. THE 30 KNOT LOW LEVEL JET WILL SLIDE OVER THE FORECAST AREA TONIGHT. COOLER AIR ADVECTING IN OVER LAKE SUPERIOR THIS EVENING...WILL PRODUCE ENOUGH LOW LEVEL INSTABILITY TO ALLOW SOME OF THIS JET ENERGY TO MIX TO SURFACE. WITH DRY AIR ADVECTING INTO THE AREA OVERNIGHT...THE SKY SHOULD BE CLEAR FROM THE WEST. WINDS WILL START TO DIMINISH OVER THE WEST TONIGHT AND THE JET WILL SLIDE EAST. THE UPPER LEVEL TROUGH WILL MOVE INTO THE LOWER GREAT LAKES ON TUESDAY. A WEAK SHORTWAVE TRYING TO CATCH UP WITH THE TROUGH WILL SWING OVER THE FORECAST AREA. THE SURFACE RIDGE WILL WILL SHIFT OVER THE UPPER GREAT LAKES ON TUESDAY BRINGING DRY STABLE AIR MASS TO THE AREA. SKIES WILL BECOME MOSTLY SUNNY. AHEAD OF THE HIGH...THE WINDS WILL BE MAINLY OUT OF THE NORTH. THE 30 KNOT LOW LEVEL JET WILL SLIDE TO THE EAST OF THE FORECAST AREA. WINDS WILL GRADUALLY WEAKEN THROUGH THE DAY. WITH THE ABUNDANT SUNSHINE...TEMPERATURES SHOULD CLIMB TO AROUND 50. ANOTHER LOW WILL DEVELOP IN THE TROUGH TUESDAY NIGHT AND WILL BE OVER THE LOWER GREAT LAKES. THE MID LEVEL RIDGE WILL SLIDE OVER THE UPPER MISSISSIPPI VALLEY. MEANWHILE THE SURFACE RIDGE WILL REMAIN OVER THE UPPER GREAT LAKES...EXPANDING INTO THE SOUTHEAST CONUS. THE SURFACE LOW WILL REACH TO THE NORTH ATLANTIC COAST...WHILE WESTERN LOW WILL START TO MOVE OUT OF THE ROCKIES INTO THE HIGH PLAINS. WINDS WILL BECOME LIGHT UNDER THE RIDGE. WITH LIGHT WINDS AND SOME CLEARING THERE SHOULD BE CONSIDERABLE RADIATIONAL COOLING LOWERING THE TEMPERATURES TO AROUND 20 ACROSS THE AREA. THE MID LEVEL LOW WILL MOVE INTO NORTHEAST CONUS ON WEDNESDAY... WHILE THE MID LEVEL RIDGE REMAINS OVER THE UPPER MISSISSIPPI VALLEY. THE SURFACE RIDGE WILL DOMINATE THE UPPER GREAT LAKES ON WEDNESDAY. A SURFACE LOW WILL BECOME MORE ORGANIZED OVER THE CENTRAL HIGH PLAINS ON WEDNESDAY...IN ASSOCIATION WITH THE MID LEVEL LOW. DRY AIR WILL REMAIN OVER THE FORECAST AREA...AND ALLOW MORE SUN OVER THE AREA. TMPERATURES SHOULD CLIMB TO UPPER 50S ON WEDNESDAY. THE MID LEVEL RIDGE WILL MOVE LITTLE BY WEDNESDAY NIGHT AND WILL STILL BE STRETCHED ACROSS THE FORECAST AREA. THE SURFACE RIDGE WILL SHIFT EVER SO SLIGHTLY INTO EASTERN ONTARIO...BUT STILL DOMINATE MUCH OF THE UPPER GREAT LAKES. MEANWHILE TO THE WEST...THE NEARLY VERTICALLY STACKED LOW WILL MOVE INTO WESTERN KANSAS. AS THE SURFACE RIDGE MOVE JUST TO THE EAST OF THE FORECAST AREA...WIND WILL SHIFT TO THE SOUTHWEST AND DRAW WARMER GULF AIR TOWARDS THE FORECAST AREA. THE MODELS ARE IN FAIRLY GOOD AGREEMENT. THE GFS AND GEM ARE IN VERY CLOSE AGREEMENT OUT OF THE 00Z SUN. THE ECMWF POSITIONS ARE VERY CLOSE TO THAT OF THE GFS ONLY WITH SOME MINOR DIFFERENCES IN STRENGTHS OF THE SYSTEMS. ETA MATCHES UP WELL WITH THE GFS/GEM AT 72HRS...EXCEPT FOR THE AND STRENGTH OF THE EAST COAST LOW. ETA IS DEEPER AND FARTHER WEST WITH THIS LOW THAN THE GFS/GEM. ECMWF IS COMPROMISE BETWEEN THE GFS AND ETA. THE ENSEMBLE FORECASTS ALSO FAVOR THE GFS/GEM SOLUTIONS. THE MID LEVEL RIDGE WILL REMAIN OVER THE AREA ON THURSDAY. WINDS WILL BE LIGHT AND OUT OF THE SOUTH. THE MID LEVEL LOW WILL MOVE OVER EASTERN KANSAS BY 00Z FRI. A RIDGE WILL BE OVER ONTARIO AND THE UPPER GREAT LAKES. DRY AIR OVER THE AREA WILL KEEP SKIES FAIR ON THURSDAY. THE RIDGE WILL CAUSE THE LOW TO SLIDE TO THE SOUTH OF THE FORECAST AREA. A WEAK SHORTWAVE WILL SLIDE THROUGH THE FORECAST AREA THURSDAY NIGHT. THE RIDGE WILL KEEP CONDITIONS FAIR THROUGH SUNDAY. MEANWHILE A MID LEVEL LOW IS EXPECTED TO DEVELOP OVER NORTHERN HIGH PLAINS. WEAK SHORTWAVE WILL BE EJECTED OUT AHEAD OF THIS LOW AND WILL TRAVERSE THE FORECAST AREA ON MONDAY. THE SURFACE REFLECTION OF THIS SUPPORTS A LOW DEVELOPING OVER HIGH PLAINS ON SUNDAY AND MOVE TO WESTERN ONTARIO ON MONDAY...DRAGGING A COLD FRONT INTO THE FORECAST AREA LATE SUNDAY NIGHT AND MONDAY. .MQT...GALE WARNING EAST LAKE SUPERIOR. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE EL PASO-SANTA TERESA NM 140 PM MDT MON APR 21 2003 SYNOPSIS... RESIDUAL LOW LEVEL MOISTURE AND INSTABILITY WILL GIVE THE AREA FROM THE RIO GRANDE VALLEY EAST A SLIGHT CHANCE OF THUNDERSTORMS TONIGHT. OTHERWISE DRY AIR AND BREEZY CONDITIONS WILL PERSIST THE REST OF THE WEEK. HIGH TEMPERATURES WILL REMAIN AT AROUND 80 DEGREES ALONG THE LOWLANDS ALL WEEK...EXCEPT FOR A BRIEF COOL DOWN WEDNESDAY WITH A COOL FRONT MOVING THROUGH. DISCUSSION... AREA NOW IN THE PROCESS OF GOING BACK TO DRY SOUTHWEST INFLUENCE. DRYLINE/CONVERGENCE ZONE FORMING OVER THE BOOTHEEL CURRENTLY AND WILL CONTINUE EAST INTO TUESDAY. POSITION OF THIS FEATURE WILL BE CRITICAL AS THERE WILL BE A SLIGHT CHANCE ON THE MOIST SIDE OF THE LINE. MSAS ANALYSIS AND RUC INITIALIZING THE POSITION WELL AND RUC TREND IS TO SLOW DOWN THE DEVELOPING DRY LINE. LATEST RUC STILL SHOWS THE LINE NORTH/SOUTH AROUND DEMING LATE AFTERNOON AND THROUGH EL PASO MID TO LATE EVENING. MODELS STILL SHOWING GOOD INSTABILITY WITH DECENT CAPE VALUES TO THE EAST OF THIS LINE SO WILL KEEP POSSIBILITY OF THUNDERSTORMS IN THE EASTERN ZONES TONIGHT. AREA RETURNS TO MORE TYPICAL SPRING SCENE (WINDS) REMAINDER OF WEEK AS A COUPLE OF LONG WAVE TROUGHS WITH SEVERAL EMBEDDED SHORT WAVES PASS ACROSS THE AREA. WINDS WILL PICK UP INTO BREEZY CATEGORY TUESDAY BUT UPPER TROUGH TIMING NOT VERY GOOD...BEST UPPER SUPPORT MOVES THROUGH TOMORROW NIGHT...AND WILL INHIBIT STRONGER WINDS. FROPA TUESDAY NIGHT WILL COOL TEMPS BRIEFLY. WINDS ON WEDNESDAY A BIT STRONGER WITH GOOD SURFACE PRESSURE PATTERN BUT AGAIN UPPER SUPPORT NOT SHOWING REAL WELL. MUCH THE SAME FOR THURSDAY AND FRIDAY AS DECENT SURFACE PRESSURE GRADIENT CONTINUES BUT UPPER SUPPORT LACKING. PRELIMINARY NUMBERS... EL PASO UU 054/083 052/077 049 10000 ALAMOGORDO UU 050/081 048/075 045 20000 LAS CRUCES UU 050/083 048/077 045 00000 CLOUDCROFT UU 033/061 031/053 030 20000 TRUTH OR CONSEQUENCES UU 047/078 045/072 042 00000 SILVER CITY UU 039/071 037/065 035 00000 DEMING UU 049/082 047/076 044 00000 LORDSBURG UU 046/084 044/078 041 00000 SIERRA BLANCA UU 051/080 049/074 046 20000 .ELP...NONE 17 HEFNER tx