EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 845 PM EST SUN FEB 20 2000 FRONT CONTINUES TO PUSH DOWN THE PENINSULA...WITH DEWPOINTS NOW FALLING THROUGH THE 40S NORTH AND 50S SOUTH. SURFACE WINDS HAVE TEMPORARILY VEERED TO NE COMPONENT OVER N HALF OF THE CWA...BUT EXPECT WINDS TO BACK TO N/NNW LATER TONIGHT. CURRENT ZFP IN GOOD SHAPE...BUT WILL OPT TO REFRESH WORDING BY 10 PM. MARINE...CURRENT BUOYS AND LATEST RUC FORECAST CONTINUE TO SUPPORT SCEC CONDITIONS OVERNIGHT. DO NOT EXPECT ANY CHANGES TO CWF. .MLB...FIRE WEATHER WATCH...LAKE SEMINOLE ORANGE OSCEOLA INTERIOR VOLUSIA MONDAY AFTERNOON FOR LOW RH WITH WIND. BRAGAW/SPRATT fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SHREVEPORT LA 930 AM CST SUN FEB 20 2000 HIGH PRESSURE CENTERED OVER SE AR THIS MORNING WITH MOSTLY CLEAR SKIES ACROSS MY ENTIRE AREA. VIS SAT IMAGERY SHOWING VAST EXPANSE OF AC ACROSS NORTH CENTRAL TEXAS MOVING SOUTH AND EAST INTO THE PINEY WOODS AND LAKE COUNTRY OF EASTERN TEXAS. CLOUDS DISSIPATING SOMEWHAT ALONG THEIR EASTERN EDGE AS THEY ENCOUNTER DRIER AIR IN ASSOCIATION WITH 7H RIDGE AXIS ACROSS DEEP SOUTH TEXAS. ISENTROPIC SURFACES AT THE 8K LEVEL ON THE LATEST RUC MODEL SHOWS 60-70% RH ALONG THE TX/LA BORDER BY 00Z TNGT. CURRENT FCST HAS PC ACROSS EAST TEXAS SO THIS SHOULD HOLD WITH MOSTLY CLOUDY CONDITIONS NOT FCST UNTIL TNGT. DUE TO THE LATE ARRIVAL OF THESE CLOUDS AND THE FACT THAT THEY SHOULD NOT BE TOO THICK...DO NOT ANTICIPATE THEM HAVING MUCH INFLUENCE ON AFTERNOON HEATING. REST OF FCST ON TRACK SO NO UPDATE NEEDED. 13 .SHV...NONE. la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1155 AM EST SUN FEB 20 2000 AREA SURFACE REPORTS AND 88D DATA CONTINUING TO SHOW LIGHT SNOW SHOWERS AND FLURRIES REMAINING OVER NORTHERN LOWER AND EAST UPPER MICHIGAN. THE LATEST SURFACE CHART SHOWS A COLD FRONT MOVING OVER CENTRAL LOWER MICHIGAN WITH THE LATEST RUC RUN STILL SHOWING 700/500 MB DPVA AFFECTING NORTHERN LOWER THROUGH THE AFTERNOON. LAKE ENHANCEMENTS WILL ALSO CONTINUE THROUGH THE AFTERNOON WITH 850 MB TEMPERATURES AROUND -12C TO -13C. 1000/850 MB AVERAGE WIND DIRECTION WILL BE 280/290 DEGREES WITH 1000/850 MB MOISTURE DRYING FROM 70 PERCENT EARLY THIS AFTERNOON TO 40 PERCENT BY THIS EVENING. THEREFORE WILL KEEP MENTION OF SNOW SHOWERS IN THE LAKE MICHIGAN SNOW BELT THIS AFTERNOON BUT MENTION DIMINISHING. FOR NORTHEAST LOWER WILL CONTINUE SCATTERED SNOW SHOWERS OR FLURRIES THROUGH THE AFTERNOON AS THE COLD FRONT AND 500 MB VORT MAX MOVES OVER THE NORTHERN GREAT LAKES. FOR EAST UPPER WILL MENTION DIMINISHING SNOW SHOWERS THIS AFTERNOON. .APX...NONE. SWR mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 545 AM EST SUN FEB 20 2000 WILL BE UPDATING MY SOUTHWEST COUNTIES TO INCLUDE SOME MINOR ACCUMULATIONS. LATEST RADAR TRENDS SHOW A LARGE AREA OF LIGHT SNOW AND FLURRIES COVERING MY SOUTHWEST COUNTIES. WEST WIND WILL SHIFT TO THE WEST NORTHWEST BY 8 AM AND THEN NORTHWEST LATE THIS MORNING. THUS...SNOW BANDS SHOULD PREVAIL OVER ALLEGAN...VAN BUREN AND KALAMAZOO COUNTIES. RUC MODEL IS DRY...BUT SHOWS PERSISTANT SURFACE DIVERGENCE ACROSS THESE COUNTIES THIS MORNING. MESO ETA IS SIMILAR. INVERSION HEIGHT REMAIN AROUND 4500 FT...SO AM EXPECTING ONLY LIGHT ACCUMULATIONS. ALLEGAN HAD A DUSTING AS OF 540 AM. THUS WILL BE ADDING SNOW SHOWERS LIKELY WITH LOCALLY AND INCH OF ACCUMULATION...THROUGH THIS MORNING. .GRR...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1025 AM EST SUN FEB 20 2000 LK PLUME AS FAR E AS ABT 10SW KDDH PER KENX RADAR. 14Z SFC ANLYS INDICATES WK CDFNT APCHG CYSB AND SE LK SUPERIOR. 12Z SOUNDING AT KALY SHOWS ABT 2 THSD FT DP MOIST LYR TO SUPPORT BKN SC/CU. UPSTREAM SOUNDINGS CONT WITH ADDITIONAL LOW LVL MSTR. LATEST RUC NOTES NVA BLDG INTO SE NY OVER NEXT FEW HRS...WL LEAN LTL MORE TWD SUNSHINE THERE...OTHER ONLY MINOR VARIATIONS ON ERYR PACKAGE. MCKINLEY/HWJIV .ALY...NY ERN/VT EXTRM SRN/MA EXTRM WRN/CT NW...NONE. ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 831 PM EST SUN FEB 20 2000 HI PRES OVER THE AREA THIS EVE. CLR SKIES/LGT WINDS. DEWPTS HOVERING AROUND FREEZING. FCST LO TEMPS LOOK TO BE ON TRACK WITH AROUND 30 INLAND TO NR 40 CST. MAY TWEAK ONE OR TWO ZONES. WL CUT WINDS BACK TO LGT INLAND AND 5 MPH CST BASED ON LTST OBS. CWF...SFC PRES GRADIENT IS RATHER WEAK ACROSS THE MARINE FA EARLY THIS EVENING. MESOETA/RUC BOTH INDICATE THE WEAK SFC WAVE WELL OFFSHORE WILL CHANGE LITTLE OVERNIGHT...BUT SOME NOCTURNAL SURGING IS LIKELY AS GRADIENT TIGHTENS CLOSER TO THE COAST BY 12Z. FCST LOOKS REAL GOOD AND THE ONLY SIGNIFICANT CHANGE WILL BE TO REPLACE SCA FOR OFFSHORE GEORGIA WATERS WITH SCEC. MAY ALSO REMOVE SCEC FOR GEORGIA WATERS WITHIN 20 NM. .CHS... SC...NONE. GA...NONE. TJR/RVT sc SOUTH CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 855 PM CST SUN FEB 20 2000 HIGH PRESSURE KEEPING LOW LEVEL JET FLOWING UP THE RIO GRANDE. RUC SHOWS MINIMAL ISENTROPIC LIFT IN THE BOUNDARY LAYER WITH THIS JET. SOME ALTOCU CASTELLANOUS PICKED UP BY KDFX RADAR AND SHORT WAVE IR IMAGES MOVING TOWARD VAL VERDE COUNTY. EVENTHO CLOUD TOP WARMING HAS SHRUNK THE AREAL COVERAGE OF THIS ALTOCU AS IT APPROACHES THE RIDGE, SOME DROPS COULD REACH THE GROUND BEFORE IT FIZZLES OUT. WILL NOT PUT POPS IN VAL VERDE COUNTY AND LET SHORT TERM FORECASTS HANDLE THIS. DRIER EASTERLY SURFACE WINDS CONTINUE OVER EASTERN MOST COUNTIES. ONLY MINOR CHANGES TO ONGOING FORECAST. .EWX...NONE. 06/08/PM tx COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 945 AM CST FRI FEB 20 2000 CLOUDS THINNING WITH SOME VERY LARGE BREAK NOWS STARTING TO OCCUR...ESPECIALLY SOUTH CENTRAL CWFA. KCRP SOUNDING AND LATEST RUC ISENT DATA INDICATING THAT THE LOW LEVELS ARE DRYING OUT SOMEWHAT. EXPECT THIS TREND TO CONTINUE INTO THIS AFTERNOON. LOOKS LIKE THERE MIGHT BE AN AREA OF SEA FOG OFF COAST AROUND CRP BAY AND THIS WILL HAVE TO BE WATCHED ESPECIALLY LATE IN THE DAY FOR A RUN INLAND. TEMPS WILL BE A PROBLEM WITH THE VARIABLE CLOUDS AROUND. SOME READINGS WILL RISE INTO THE LOW TO MID 70S IF THEY GET 1 OR 2 HOURS OF GOOD SUNSHINE. MARINE...NO FLAGS AS THINGS SMOOTH OUT BY THE END OF DAY. .CRP...NONE. 78 tx WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 120 PM MST SUN FEB 20 2000 PROGRESSIVE FLOW PUTS THE SOUTHWEST AND GREAT BASIN UNDER THE GUN FOR THE NEXT SEVERAL DAYS. THE MOIST AND DEEPER AVN IS THE MODEL OF CHOICE BASED ON RECENT PERFORMANCE AND GOES SOUNDER CONFIRMATION. THANKS FOR INPUT FROM ABQ/PUB/SLC/. SYSTEM 1...THAT WAS WOUND UP TIGHT AND BEAUTIFUL IN THE CENTRAL PACIFIC LAST WEDNESDAY...CONTINUES TO OPEN AND WEAKEN AS IT COMES ON SHORE. 17Z RUC PRODUCES NO PRECIP WEST OF NEVADA THRU 03Z. 18Z GOES SOUNDER SHOWS UNSTABLE AIR (-21C 500TEMPS/<0 LI) HAVE SPREAD INTO 4- CORNERS ALONG WITH AN 80KT JET. WEAK FRONT TO BRUSH THE SOUTHERN ZONES BEFORE MIDNIGHT AND MAY PRODUCE SOME CONVECTIVE PRECIP...LESS THAN ADVISORY AMOUNTS. AN ISOLATED THUNDERSTORM IS NOT OUT OF THE QUESTION. SNOW ACCUMULATION LEVEL AROUND 8000FT. FOR NORTHERN ZONES WILL DROP POPS...BUT KEEP A SLIGHT CHANCE IN AS FAR NORTH AS THE FLAT TOPS (COZ13) WHERE OROGRAPHICS COULD WRING OUT SOME LIGHT ACCUMULATIONS. OTHERWISE THIS WEAK FIRST SYSTEM SERVES TO ADVECT MOISTURE AHEAD OF SYSTEM 2. SYSTEM 2 SPLITS AS IT APPROACHES MONDAY AFTERNOON WITH THE MAJORITY OF ENERGY INTO NM. THE SOUTHERN MOUNTAINS TO INITIALLY GET THE MOST PRECIP IN SW FLOW AND NOSE OF 90KT JET. ASSOCIATED COLD FRONT PASSES TUESDAY MORNING WITH GOOD INSTABILITY SHOWERS THRU THE AFTERNOON. TROF PASSAGE BY AFTERNOON WITH ALL WINDS VEERING TO THE NW. STRONG CYCLONIC FLOW AND AN IMPULSE DROPPING INTO THE LOW FROM THE NORTH WOULD TURN ON THE SNOW MACHINE FOR THE NORTHERN AND CENTRAL MTNS. NORTH-CENTRAL MTN SHOWERS TO END EARLY WEDNESDAY AS SHORTWAVE RIDGE AXIS APPROACHES. SNOW LEVEL STARTING AT 8000 AND LOWERING TO AROUND 7000FT. EVEN WITH SOME UNCERTAINTY...MTN SNOW ADVISORY CRITERIA LIKELY TO BE MET AND POSSIBLY APPROACHING WARNING CRITERIA. WILL ISSUE A STATEMENT AND LET THE NEXT FEW SHIFTS CONSIDER A WATCH. EXTENDED: PROGRESSION CONTINUES WITH NEXT SYSTEM ADVERTISED FOR THURSDAY (CANADIAN) OR FRIDAY (MRF...NOGAPS...EC). SPLITTING FLOW IS AGAIN ADVERTISED WITH MOST OF THE ENERGY AGAIN SOUTH. BUT WITH PLENTY OF UNCERTAINTY ABOUT TIMING AND INTENSITY...WILL DO A BAROCLINIC BROADBRUSH PERHAPS WITH A SLIGHT EMPHASIS SOUTH. 99/RAMEY .GJT...NONE. co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 313 AM CST MON FEB 21 2000 ...CHANCES FOR PCPN ON TUESDAY STILL MAIN CONCERN... MODELS CONTINUE TO MOVE WRN SYSTEM INTO THE PLAINS BY TUESDAY. DIFFERENCES BECOME MORE APPARENT THROUGH TIME HOWEVER. EARLY ON...APPEARS AVM HAS BETTER HANDLE ON UPPER AIR SYSTEM OFF CA. COAST. SPLIT IN CIRCULATION APPEARS TO BE UNDER WAY AS NOTED ON LAST FEW HOURS OF SAT PIX AND HIGH DENSITY WATER VAPOR WINDS. IN ANY CASE...NOT WITHSTANDING HPC DISCUSSION OF NRN BIAS OF AVM...FEEL MOISTURE WILL BE DEEP ENOUGH...AND LIFT WITH APPCHG WAVE SUFFICIENT TO INCREASE ONGOING POPS SLIGHTLY FOR TUESDAY AFTN. H3 JET STRUCTURE IN ADVANCE OF WRN SYSTEM WOULD BE SUPPORTIVE OF SGFNT CONVECTION. LOW LVL MOISTURE SHOULD BE INCREASING RAPIDLY BY TONIGHT SETTING STAGE FOR CONVECTIVE OUTBREAK CENTRAL KS TUESDAY AFTERNOON. TIMING OF PCPN OVER ERN PTN OF CWA A LITTLE TRICKY. INITIAL DVLPMT/PUSH OF PCPN SHOULD BE MORE TO THE NORTH THAN NORTHEAST. THUS PCPN MAY NOT MAKE IT INTO ERN CWA UNTIL LATE AFTN OR ERY EVENING. PREFER UPPER JET STRUCTURE OF NGM/AVM WITH RIGHT REAR QUAD OF JET OVER CNTRL KS LATE TUESDAY AFTN. HOWEVER...MAY BE A CLOSE CALL IN KEEPING STG STORMS OUT OF WRN CWA LATE TUESDAY. JET DYNAMICS MAY BE STG ENOUGH TO KEEP THE ACTIVE STORMS GOING THROUGH A GOOD PTN OF TUESDAY EVENING. FOR SHORTER TERM...WILL UP FCST WINDS TO 20 TO 30 MPH BASED ON CURRENT LOW LVL WIND PROFILE...AND EXPECTED FURTHER INCREASE IN GRADIENT...ESP OVER ERN CWA. LOWER CLOUDS INITIALLY VERY THIN AND LIKELY TO SHIFT EAST EARLY IN FCST. LIKEWISE...REMNANTS OF UPPER AIR SYSTEM OFF BAJA YDA MVG OVER AREA ATTM. WEAK SHORT WAVE...OR REMNANTS OF UPPER SYSTEM...SHEARING OUT OVER AREA THIS MORNING PER LATEST RUC. THUS PC BY THIS AFTN. WITH SOME SUNSHINE...LIKELY TO SEE TEMPERATURES MORE IN LINE WITH FAN TODAY. BY TMRW...MUCH DEEPER MOISTURE AND THICK HIGH CLOUDS SHOULD KEEP READINGS BLO MOS LVLS. .TOP...NONE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 445 AM CST MON FEB 21 2000 COMBINATION OF WEAK SHORT WAVE TROUGH AND LOW LEVEL THERMAL ADVECTION RESPONSIBLE FOR CONVECTION ACROSS NORTH CENTRAL TEXAS ZONES EARLY TODAY. NONE OF THE MODELS INCLUDING THE RUC INDICATE THIS IN PRECIP FIELDS. TRENDS AND MOVEMENT PAST 3-4 HOURS POINT TO THIS AREA OF PRECIP MOVING ENE AND REMAINING WEAK. WILL NOT INCLUDE MENTION OF PRECIP IN SOUTHEAST ZONES FOR THE TIME BEING UNLESS FURTHER DEVELOPMENT OCCURS. 5-7K DECK OF CLOUDS OVER N TX AND SOUTHERN OK WILL CONTINUE ACROSS THESE REGIONS THROUGH THE MORNING WITH DECREASING CLOUD TREND THIS AFTERNOON AS HINTED BY ETA RH FIELDS. AREAS FURTHER NORTH AND WEST WILL SEE MOSTLY HIGH CLOUDS UNTIL WEAK SHORT WAVE PASSES DURING THE DAY. ALL SHORT RANGE MODELS IN AGREEMENT THAT THE VIGOROUS TROUGH IN THE WEST WILL MOVE INTO SOUTHERN PLAINS TUESDAY WITH SIGNIFICANT ROUND OF RW/TRW. PROBABLY TWO ROUNDS OF PRECIP WITH THIS SYSTEM BEGINNING AS LATE TONIGHT IN WESTERN OKLAHOMA WITH ELEVATED INSTABILITY PROGGED AND AT LEAST ONE WEAK TROUGH LIFTING OUT AHEAD OF MAIN TROUGH. RIGHT REAR QUAD OF POLAR JET EXITING THROUGH CENTRAL PLAINS WILL HELP ELEVATED CONVECTION CONTINUE DURING THE DAY TUESDAY AHEAD OF THE MAIN TROUGH TUES EVE/NIGHT. WILL NEED TO TEMPER SEVERE THREAT TUES EVENING WITH THE FACT THAT SIGNIFICANT CLOUD COVER AND DAYTIME PRECIP WILL LIKELY ALTER QUALITY OF AIRMASS. AGREE WITH SPC ASSESSMENT OF CONVECTION IN SWODY2. CONVECTION WILL END WEST TO EAST TUESDAY NIGHT. WITH CURRENT TIMING IT LOOKS LIKE ENDING BEFORE MIDNIGHT WEST AND AFTER MIDNIGHT EAST. DOES NOT APPEAR TO BE ANY PUSH OF COLD AIR BEHIND SYSTEM AND ALL MEDIUM RANGE MODELS SHOW SEVERAL MORE IMPULSES COMING OUT OF THE WEST WED-FRI. TIMING AND INTENSITY OF THESE FEATURES DIFFERS WITH MODELS. INSTEAD OF WAFFLING ON THIS WILL LEAVE EXTENDED GO FOR NOW. FCSTID = 33 OKC 66 54 63 46 / 0 10 70 70 HBR 70 52 63 43 / 0 30 70 70 SPS 70 55 68 48 / 0 30 70 70 GAG 70 48 63 40 / 0 30 70 70 PNC 68 52 63 46 / 0 10 70 70 DUA 66 55 65 48 / 10 10 70 70 .OUN... OK...NONE. TX...NONE. ok DEEP SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 225 AM CST MON FEB 21 2000 WM FNT SLOSHES EAST WITH GOOD ISENTROPIC UPGLIDE ON 300K SUN...GAVE MFE 0.05 INCH OF RAFL. KBRO STM TOTAL PCPN SHOWS 1/2 TO 1 INCH TOTALS NEAR WESLACO IN EASTERN HIDALGO COUNTY. CURRENT KBRO REF IDENTIFIES A LINE OF LIGHT TO MODERATE SHRAS FM THE GULF WATERS OF WILLACY COUNTY...EXTENDING INTO WILLACY COUNTY AND SOUTHERN KENEDY AND NORTHERN BROOKS COUNTIES. BRO RECORDED 0.01 INCH DURING THE EVENING. TEMP RANGED VERY LITTLE ACROSS THE VLY SUN...WITH MFE RECORDING A HIGH OF 76...HRL 75 AND BRO 77. MRNG LOWS NEAR 62 DEG F. STLT PICS SHOW MID LVL SHIELD SHUD CONTINUE TO ADVECT OVR VLY THIS MRNG AS IT MVS N...EXITING THE VLY BY SUNRISE. MESOETA SHOWS MSTR DECREASE IN THE LOWER LVLS THRU 6 PM TNGT WITH LLVL FLOW VEERING SOUTH SOUTHEAST AND DECREASING TO 20 KT BY 6 AM TDY. SFC WINDS WILL STAY SOUTHEAST AT AROUND 10 MPH UNTIL LATE MRNG...NOT INCREASING TO THE 15 TO 20 MPH RANGE UNTIL LATE THIS AFTERNOON...AS PGF GOES HIGH OVR GULF/LOW OVR ZAPATA LATE. RUC HOLDS CLDS IN UNTIL WINDS PICK UP...AND XPCT MOSTLY CLOUDY MRNG...BECMG PARTLY CLOUDY AND BREEZY BY MID AFTERNOON. WILL WORD ZFPBRO ACCORDINGLY. TEMPS WILL BE SIMILAR TDY AS YESTERDAY...WITH LITTLE AREAL VARIATION. MOS LOOKS GOOD FOR TEMPS AND WINDS. BY EARLY TUE MRNG...LOW LVL MSTR WILL BE EJECTED NORTHWARD FM DEEP S TX...UNDER THE UPPER RIDGE. AS UPSTREAM S/W MVS TO ELP NOON TUE...XPCT LOW LVL THERMAL AND MSTR CONVERGING IN NRN TX...UNDER A DIVERGENT UPPER FLOW FIELD...TO INDUCE SHRAS/TSRAS OVR THE TX PANHANDLE AND OK TUESDAY. DYNAMICS AND LIFT WL REMAIN TOO FAR N OF THE VLY TO GIVE US A CHC FOR RAFL...AND DEEP S TX WL REMAIN IN A MODERATE TO STRONG SE SFC FLOW LATE TDY...INCREASING TUE TO 25 TO 30 KT. WINDS WILL REMAIN BRISK THRU THE EXTENDED AS AN EVEN MORE VIGOROUS W COAST UPPER TROF DIVES INTO WRN TX. NEXT CHC FOR MUCH-NEEDED RAFL MAY BE SUNDAY...AS VIGOROUS UPPER CLOSED LOW AND ABUNDANT ENERGY WALTZES ACROSS TX SUN AND MON. MARINE...BOY020 NOW 11017KT AND WILL CONTINUE TO VEER SE. XPCT SPEEDS TO MAINTAIN OR DECREASE UNTIL MID TO LATE AFTERNOON...THEN BEGIN THEIR CLIMB TO SCA CRITERIA BY TUE. LATEST 2 AM DATA AT BOY020 FM INTERNET SHOWS WAVE HEIGHTS DOWN FM 4.9 TO 4.6 FEET WITH WINDS DOWN FM 11017G21KT TO 11017G19KT. WL NOT INTRODUCE SCEC UNTIL 2ND PD...WITH "SCA EXPECTED TOMORROW" IN HEADLINES. .SYN...PHILO 58 .MESO...FLATT 55 .HMT...CAMPBELL BRO BN 078/065 081/064 084 05/05/05/05 MFE BN 078/064 082/063 085 05/05/05/05 RGC BN 077/062 083/062 086 05/05/05/05 SPI BN 077/066 078/066 080 05/05/05/05 .BRO...NONE. tx SOUTH CENTRAL TEXAS FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 1120 PM CST SUN FEB 20 2000 TIGHT GRADIENT ALONG THE RIO GRANDE AND PASSING IMPULSES HAS KEPT WINDS MUCH STRONGER THAN FORECAST. SO WILL UP THE WIND SPEEDS THIS REGION FOR THE REST OF THE NIGHT. ............................................................... HIGH PRESSURE KEEPING LOW LEVEL JET FLOWING UP THE RIO GRANDE. RUC SHOWS MINIMAL ISENTROPIC LIFT IN THE BOUNDARY LAYER WITH THIS JET. SOME ALTOCU CASTELLANOUS PICKED UP BY KDFX RADAR AND SHORT WAVE IR IMAGES MOVING TOWARD VAL VERDE COUNTY. EVENTHO CLOUD TOP WARMING HAS SHRUNK THE AREAL COVERAGE OF THIS ALTOCU AS IT APPROACHES THE RIDGE, SOME DROPS COULD REACH THE GROUND BEFORE IT FIZZLES OUT. WILL NOT PUT POPS IN VAL VERDE COUNTY AND LET SHORT TERM FORECASTS HANDLE THIS. DRIER EASTERLY SURFACE WINDS CONTINUE OVER EASTERN MOST COUNTIES. ONLY MINOR CHANGES TO ONGOING FORECAST. .EWX...NONE. 06/08/PM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 230 PM MST SUN FEB 20 2000 CRNT WX...SCT-BKN HI/MID CLDS STREAMING NE INTO CWA AHEAD OF SWRN US SHRT WV AND MAIN UPR TROF OFF MAIN TROF OFF CAL CST. WV AND RUC SHOW AXIS OF UPR RIDGE CROSSING THRU CWA ATTM. WARMEST TEMPS NORTH AND NORTHEAST WHERE MAX SOLAR INSLTN AND DOWNSLOPING OCCURRED...TEMPS MID 40S TO MID 50S. COLDER SOUTH AND WEST WHERE EARLIER CLOUD COVER OCCURRED WITH SOME LOCALS NOT MIXING OUT AT ALL. KJAC STILL 18F AT 21Z. SHRT WAVE TO MOVE THRU AREA LATE TNT. ETA PLACES 1.5 INCH BULLSEYE OVER TETONS WITH LESSER AMOUNTS OTHER WESTERN MTNS. E OF DVD WILL BE IN DOWNSLOPE AND PC. FCSTG 1 TO 2 INCHES LCL ACCUMS WERN MTN. MAINLY TETONS AND WERN SLOPES WIND RIVERS NRML TO SW FLO. SCT -SHSN WERN VALLEYS. PAC MSTR TO CONT SCT -SHSN WEST TOMORROW WITH LIGHT SNOWS FCST WEST TMRW NT WITH APPRCH OF UPR TROF. AM CONTG PREVS MENTN PSBL THUNDER SW TMRW PM AS ATMOS MARGINALLY UNSTBL. AM TAKING OUT MENTION OF PCPN TUES NT AS AVN PROGS SHOW BOTH SFC AND UPR RIDGE OVR AREA. SUSPECT THIS MAY CARRY OVER INTO WED IF AVN/MRF TREND TO SLOW DOWN WITH APPROACH TO VALID TIME CONTINUES. HOWEVER...WILL LEAVE WED/THURS XNTD AS IS FOR NOW. IMPROVE WX OF FRIDAY AS 3 XNTD MDLS BUILD SFC RDG OVER REGION. .RIW...NONE. DZ wy WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 335 AM MST MON FEB 21 2000 EACH NEW LOOK AT APPROACHING PACIFIC SYSTEM SHOWS IT WEAKENING. MODELS IN FAIR AGREEMENT ON GENERAL CHARACTERISTIC. EACH SHOWS MAIN VORT MAX DIGGING SOUTH ALONG U.S./MEX BORDER AS SYSTEM MOVES ONSHORE. THIS IS SUPPORTED IN LATEST RUC. CURRENT SATELLITE SHOWS CIRCULATION CENTER ELONGATES TO ON N/S AXIS WITH MINOR STRENGTHENING OF TROP UNDULATION SOUTH OF LOW CENTER. AREAS UP UPLIFT AND SCTD PCPN AHEAD OF TROUGH MOVING THRU WRN/CNTRL AZ AND SWRN UT THIS MORNING SHOULD ADVECT INTO SWRN CO. WILL SCALE BACK PCPN AT BIT IN FIRST PERIOD FROM CURRENT FCST WITH LOWER POPS IN VALLEYS. WILL KEEP HIGH POPS IN MTNS BUT HOLD BACK TIMING A BIT. WITH TIME IN MODELS AND FROM LATEST TENDANCIES IN SATELLITE IMAGERY...PERIOD OF GOOD UVV ERN UT AND WRN CO SHORTENS TO LESS THAN 12HRS. 700 MB WINDS WEAKEN IN 00Z MODELS TO 20 KTS AND SHIFT EARLIER TO W AND NW. AVN IS ONLY MODEL WITH SGNFCNT MOISTURE DEPTH AND THAT IS VERY SHORT LIVE FROM ABOUT 06Z TO 12Z TONIGHT. ALL POINTS TO HIGH PCPN PROBABILITIES...BUT BLO HEAVY SNOW CRITERIA. ALSO RELATIVELY WARM 700 MB TEMPS OR ABOUT -4 C MEAN WET SNOW. WILL GO WITH LOW ACCUMULATIONS AND LET DAY SHIFT DETERMINE IF AN ADVY IS NECESSARY FOR TONIGHT. SERIES OF PROGRESSIVE TROUGH SHOULD CONTINUED THRU THE REST OF THE WEAK...SHORT HARD TO TIME BREAKS IN BETWEEN. WILL CONTINUE CURRENT TREND OF CHC PCPN THRUOUT THE PD. CUOCO WESTERN COLORADO AND EASTERN UTAH EMERGENCY MANAGERS SHOULD MAINTAIN A NORMAL LEVEL OF WEATHER AWARENESS TODAY. .GJT...NONE. co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1053 AM EST MON FEB 21 2000 ...TEMPS AND CLOUDS ON TRACK... UPR MI UNDERGOING WAA WITH BROAD SFC HI OVER THE OHIO VALLEY AND UPR RIDGE OVER HI PLAINS. MESOETA/RUC DEPICT UPSTREAM H4 SHORTWV APPROACHING FROM SW ONTARIO CONTRIBUTING TO INCREASING H7-H3 QVECTOR CONV THIS AFTERNOON. CURRENT IR/VIS IMAGERY AND A GLANCE OUT THE WINDOW REVEALS CIRRUS SHIELD ASSOC W/ THIS FEATURE ALREADY STREAMING ACROSS UPR MI W/ KMQT 88D VAD RETURNS AT 25KFT. ANOTHER SHIELD OF CI APPROACHING FROM SW MAY OVERSPREAD SE COUNTIES GIVEN THIS SHORWV FEATURE OVR NW IOWA IS FURTHER NORTH THAN MODELS SUGGEST. NGM PARCEL TRAJECTORIES AND ANALYGOUS 1000-500MB THICKNESS ANALYSIS INDICATE UPSTREAM SOURCE REGION IS S CENTRAL MN. MOS PERFORMED WELL THERE YESTERDAY...AND ONLY DIFFERENCE IS LESS SOLAR INSOLATION WITH CI SHIELD HERE TODAY. MIXING THE 12Z GRB RAOB OUT BLO 950MB YIELDS 37-40F. CURRENT FCST OF MAX TEMPS NR 40F LOOK ONTRACK..SO WILL NOT UPDATE. .MQT...NONE. WOLF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 AM EST MON FEB 21 2000 MAIN FCST CONCERNS ARE TEMPS..POTL FOR FOG/DRZL TNT AND TMRW AND RAIN IN THE MID WEEK. NOW...BROAD HIGH PRES AREA ACS THE SERN U.S. AND RATHER DISORGANIZED SFC PTN ACRS THE ROCKIES. WATER VAP SHOWS SOME WEAK...HIGH CLDS PRODUCING...S/WVS EJECTING FM THE ROCKIES WHILE DEEP TROF BANGS INTO CNTRL CA. ACRS MQT CWA...SOME HIGH CLDS SEE DROPPING INTO E CST TROF... BUT LTL ELSE IN THE WAY OF CLDS. TEMPS HAVE RMND RELATIVELY MILD ACRS MUCH OF THE FA W/ LWR ATM NOT COMPLETLY DECOUPLED. LOCALLY...NOTABLY AT ESC AND SAW...TEMPS SVRL DEGS COLDER. TDY...HIGH MSTR ACRS THE PLAINS ON THE WRN SIDE OF THE MID LVL RDG. RUC ANALYSIS AT 400MB DEPICTS THE VORT MAXES W/ THESE CLDS OVR UT/CO...AND THE NGM/AVN BOTH PICK UP THESE WAVES. MDLS LIFT THIS ENERGY UP THE UP THE RDG TDY EVEN AS THE WHOLE PTN TRANSLATES EWD. THIS MAKES CRNT SUN THRU HIGH CLD FCST CONT TO LOOK GOOD. WHERE THERE WAS SNOW CVR ACRS WI/IA/SRN MN TEMPS ALL TOPPED OUT IN THE LOW TO MID 30S. H1000/H85 TKNS FCST POINTS TO THESE TEMPS AND NGM SFC TRAJECTORY FCST SHOWS AIR ACRS SRN YOOP ORIGINATING IN IA. WL CUT TEMPS BACK A BIT MOST ZONES...PARTICULARLY THE W. TNT...WL REMOVE DRZL FM ERN ZONES. GNRL SLOWING OF MDLS IN DVLPG/ MOVG THE SW SYS HAS RESULTED IN A SLOWING OF HIER DWPT ADVCTN AS WELL. DPROG/DT ANALYSIS OF DWPTS FM BOTH THE NGM/ETA VALID AT 12Z TUES SHOW DWPTS FCST TO BE ABT 5 DEGS DRIER THAN THE 20/12Z RUN. ALSO...FCST SOUNDINGS AT 12Z HAVE LOWERED SATURATION LVL 25 TO 50MB. W/ SHALLOWER MSTR AND DWPTS FCST TO RMN WELL BLO 32 WL RMV DRZL FM ERN CNTYS AND HAVE JUST PTCHY FOG DVLPG. ELSEWHERE WL LEAVE PTLY CLDY AS HIGH CLDS CONTS TO SPILL ACRS UPR RDG AXIS WHICH WL BE ACRS THE UPR MIDWEST BY MORG. TUES...LOW LVL MSTR CONTS TO STREAM TWD FA ON BROAD SW FLOW. HIGH OVR E COAST FINALLY MOVES TO A POSN WHERE GULF MSTR MAY START TO BE TAPPED...THO DWPTS WL STL BE RELATIVELY MODEST UP HERE. DWPTS ARE FCST TO COME UP ABV FRZG AND THIS MSTR SHD BE TRAPPED BLO INCRSG INVERSION. MDL SNDGS RMN DRY FM 900 TO 500MB WHICH WL PRECLUDE ANY MEANINGFUL PCPN. WL LEAVE DRZL IN E WHERE SATURATION IS DEEPEST. WL FCST INCREASING CLOUDS RMDR OF FA. DESPITE 00Z WED 925MB TEMPS FCSTS OF 6 AND H85 TEMPS OF 10...WL CUT BACK HIGH TEMPS AGN...SNOW CVR AND CLDS SHD RETARD MIXING AND THUS A BIT OF THE PUNCH OF THE POTL WRMG. TUE NGT/WED...00Z AVN LIFTS STG S/WV TWD MQT FA DURG THIS PD. TUES NGT THERE WL BE A NRN BRANCH SYS CROSSING NEAR HUDSON BAY. THE RESULT...ACCORDING TO THE AVN...IS THE DVLPMNT OF A 100 PLUS KNOT JET OVR ONTARIO AT H300...AND THE YOOP IS FCST TO BE UNDER AREA OF IMPRESSIVE UPR LVL DVRGC ASSOCIATED W/ RIGHT ENTRANCE RGN. THIS IS IN GOOD AGREEMENT W/ THE PVS AVN RUN. HOWEVER...THE SFC LOW POSN IS NOT...NEW RUN MUCH FARTHER N AND FARTHER N THAN THE ECMWF AND NEW CANADIAN AS WELL. WL LEAVE PCPN AS IT IS IN THE SOUTH...THO DAY SHIFT MIGHT HAVE TO MAKE AN ADJUSTMENT. PER AVN...DEEP MSTR...APRCH SFC LOW... ISENT LIFT...QVEC CNVRGNC IN THE H7/H3 LYR...H85/H3 DIFF DIVERGENCE POINT TO RAIN ON WED. CANADIAN MDL ALSO AGREES. WL STRENGTHEN WORDING OF PCPN WRN GROUPS CLOSER TO BEST DYNAMICS AND LEAVE FURTHER TUNING TO DAY FCSTR. .MQT...NONE. DESROSIERS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1030 AM CST MON FEB 21 2000 16Z VIS IMGS/SFC OBS SHOW FOG SLOWLY BURNING OFF ACROSS MAINLY THE SRN PTN OF THE KDLH CWA. EXPECT THIS TO CONTINUE THROUGH LATE MORNING. MEANWHILE...RUC AND MESO ETA SEEM TO BE ON TRACK WITH S/W MOVING EAST ACROSS THE ERN DAKOTAS. MORNING SOUNDINGS SHOW MSTR MAINLY IN THE HIGH LEVELS...ALTHOUGH SOME SCATTERED AC BEING NOTED ACROSS CENTRAL AND SRN MN. THIS MSTR IS PROGGED TO SHIFT E DURING THE DAY...WHICH LINES UP WELL WITH TODAYS FCST OF PTSUNNY. THUS...PLAN TO MAKE ONLY MINOR ADJUSTMENTS TO SKY AND WIND FCST. EXPECT COOLEST TEMPS TO ACTUALLY BE ACROSS SRN CWA...WHERE RESIDUAL FOG AND HIGH CLOUDS WILL SLOW THE EFFECTS OF THE SUN. ACROSS THE NORTH...WILL ADD MENTION NR RECORD HIGHS FOR INL ZONES AS 45 DEGREES DEFINATELY IN REACH WITH LIMITED SNOWFALL. TOMALAK .DLH...NONE. mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1000 AM CST MON FEB 21 2000 RUC SEEMS TO BE HANDLING SHORT WAVE CROSSING SE SD INTO IOWA FAIRLY WELL THIS MORNING. MAINLY HIGH CLOUDS WITH THIS BUT SOME HIGH BASED AC LOOKING A BIT UNSTABLE ON VIS. IN FACT...RUC SHOWING SOME 850-500 LAPSES RATES GREATER THAN 7C SLIDING ACROSS IOWA TODAY. CLOUDS MAY THIN OUT SW MN DURING AFTERNOON BUT PT SUNNY LOOKS GOOD ELSEWHERE. TEMPS A LITTLE TRICKY WITH CLOUDS BUT WELL INTO 40S AND MAYBE A 50 A GOOD BET AT LEAST SW ZONES. .MSP...NONE RICHARDSON mn DEEP SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 940 AM CST MON FEB 21 2000 WILL GO AHEAD AND REMOVE WORDING OF MORNING FOG OUT WEST IN THE ZONES. MORNING SOUNDING SHOWS FAIRLY SIGNIFICANT DEPTH OF SURFACE MOISTURE...UP TO AROUND 750 MB. CU FIELD ALREADY FORMING GIVING SCT TO BKN SKIES ACROSS SOUTH TEXAS. WILL WATCH FOR POSSIBLE UPDATING OF THE CLOUDCOVER LATER TODAY. PARTLY CLOUDY CURRENTLY IN THE FORECAST BUT WITH DEEP LAYER OF MOISTURE...MAY SEE OFF AND ON BKN SKIES. LATEST RUC DOES HOWEVER SHOW MUCH OF THE MOISTURE MOVING NORTH INTO CENTRAL TEXAS WHILE PW VALUES ACTUALLY LOWER DURING THE DAY. MAY ACTUALLY GET A FEW SPRINKLES OR LIGHT SHOWERS FROM THE CU AS THE BOTTOMS LOOK FAIRLY DARK. WRAPPED UP STORM SYSTEM ON THE WEST COAST WILL WEAKEN AS IT MOVES INLAND AND INCREASE OUR SOUTH WINDS BY LATE TONIGHT. TUESDAY LOOKS WINDY AS VORT MOVES EAST THROUGH THE 4 CORNERS. DYNAMICS SHOULD REMAIN WELL TO THE NORTH SO CHANCES OF SIGNIFICANT RAIN WILL BE BLEAK. 69 .BRO...NONE. tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 245 PM CST MON FEB 21 2000 LATEST SFC AND MSAS ANALYSIS INDICATE INCREASING LOW LEVEL SOUTHERLY FLOW HAVING IT/S WARMING EFFECT WITH AMBIENT TEMPS REACHING WELL INTO THE 40S...EVEN OVER DENSER SNOWPACK EXCEPT OVER FAR NORTH WHERE THERE/S TOO MUCH SFC FETCH OVER SNOW FIELDS TO THE SOUTH. 40+ F SFC DPTS HAVE NOSED ACROSS SOUTHWEST IA...WITH 60+ AMBIENT TEMPS ACRS MUCH OF THE CENTRAL PLAINS AND PORTIONS OF MO. VIS LOOP SHOWING STRATOCU DECK TRYING TO PUNCH NORTHWARD OUT OF THE SOUTHEAST PLAINS AND INTO NORTH-CENTRAL MO. REGIONAL 88D LOOP ALSO SHOWING SCATTERED SHOWERS ASSOCIATED WITH WEAK DISTURBANCE AND LOW LEVEL WARM SURGE/MOISTURE CONVERGENCE...PUSHING ACRS NORTHEAST MO. MODELS...NOT EVEN RUC...ARN/T PICKING UP ON THESE AND WILL WATCH TREND THROUGH ISSUANCE TIME TO SEE IF NEEDED TO ADD TO FAR SOUTHERN CWA FOR THIS EVENING. MAIN CONCERNS THIS PACKAGE CONTINUE TO BE TEMPS...SKY COVER... FOG/DRIZZLE POTENTIAL...AND EVENTUAL RAIN CHANCES. WARMING TREND WILL CONTINUE ACRS AREA AS H85 WARM POOL ACRS PLAINS WILL CONTINUE TO BE TAPPED INTO WITH SOUTHWESTERLY H85 FLOW. SHORT RANGE MODELS ADVECT EAST PLAINS H85 HIGHER LEVEL RH/S NORTHEAST ACRS MOST OF CWA TONIGHT. CONTINUING SOUTHWEST H85 FLOW MAY CONTINUE TO DEFLECT THIS SOUTH OF NORTHERN HALF OF CWA...BUT STILL WILL LEAVE MOSTLY CLOUDY/CLOUDY FOR CWA LATER TONIGHT...WITH PARTLY CLOUDY THIS EVENING. INTERESTING...MODELS THEN SHUNT BETTER H85 MOISTURE POOL EAST OF CWA AFTER 06Z TUE...BUT HIGHER LEVEL 1000-H85 LMRH/S CONTINUE TO HOLD FIRM THROUGH TUE SUPPORTING ONGOING MOSTLY CLOUDY WORDING. STILL NOT RULING OUT A FEW BREAKS THOUGH DURING DAY ON TUE. INITIAL WEAK VORT PIECES SHEAR OUT OF DVLPNG WEST COAST TROUGH THROUGH TUE...BUT GET DAMPENED AS THEY TRY AND TOP UPPER RIDGE. MORE SUBSTANTIAL VORT PIECE DOES MAKE IT ACRS AREA TUE NIGHT SUPPORTING PRECIP CHANCES THOUGH. INSHORTER TERM... CONCERNED THERE MAY NOT BE MUCH SUPPORT FOR DRIZZLE TONIGHT...BUT INCREASING LOW TO MID LEVEL RH/S DUE TO ADVECTIVE PROCESSES...SNOW MELT JUICING UP THE LOWER BOUNDARY LAYER...AND INCREASING SFC DPTS OVER DWINDLING SNOW FIELDS ON NOSE OF SOUTHERLY BREEZE SHOULD SUPPORT ADVECTION FOG TONIGHT OVER AREAS WITH STILL SOME DECENT SNOW PACK. MAY REMOVE FROM SOUTHERN ZONES WHERE SNOW HAS ERODED. NOT OUT OF QUESTION WITH ALL THESE PROCESSES FOR DRIZZLE AS WELL...SO WILL LEAVE IN MENTION WHERE FOG IS MENTIONED. MAY REMOVE FOR DAYTIME TUE HOWEVER. ETA AND NGM GENERALLY DRY THROUGH TONIGHT AND LATER TUE...ALTHOUGH AVN HINTS AT A HUNDREDTH/.01/ OVERNIGHT TONIGHT. SHORT RANGE MODELS HAVE THEIR DIFFERENCES IN HANDLING AND DVLPNG NEXT MAIN WX MAKER... BUT GENERAL SOLUTION BLEND ORGANIZES SFC LOW OVER WEST CENTRAL PLAINS/WEST KS AND WEST NE/ TUE AFTERNOON...THEN EVENTUALLY EVOLVING TOWARD SOUTHWEST IA/NORTHWEST MO THROUGH 12Z WED. AS INITIAL WARM FRONTAL BOUNDARY FROM DEVELOPING PLAINS LOW SWEEPS NORTHWARD ACRS THE SOUTHERN CWA BY LATE TUE AFTERNOON...NGM AND ETA INITIATE SHOWER CHANCE AT LEAST ACRS FAR SOUTHWEST. AS SFC LOW PULLS TOWARD SOUTHWEST IA THROUGH 12Z WED...MODELS BREAK OUT CONVECTION AHEAD OF IT FROM EAST OK...ACRS WEST MO...AND INTO CENTRAL AND EASTERN IA...ESPECIALLY AFTER 06Z WED. AVN SLOWER AND KEEPS BULK OF PRECIP WEST OF CWA THROUGH 12Z WED...AND MAY BE MORE CORRECT IN THIS DVLPNG SYNOPTIC SCENARIO. HOWEVER WITH INCRESING RH/S AND VORT TUE NIGHT...MAY TAKE COMPROMISE FOR NOW AND UP POPS ACRS THE WEST FOR LATE TUE NIGHT. BOTH NGM AND ETA WAVER RATHER UNSTABLE H85- H5 LAYER-MEAN LAPSE RATES ACRS WEST CWA BETWEEN 00Z-06Z WED. AND AS THTA-E GRADIENT COUPLED WITH NICE SFC-H85 MOISTURE CONVERGENT/UVV AXIS ON NOSE OF STRENGTHENING SOUTHERLY LLJ BUILDING ACRS SOUTHWEST 2/3'S OF CWA TUE NIGHT...MAY INTRODUCE THUNDER WORDING. AVN CONTINUES WITH PERIODS OF SHOWERS AND T-STORMS ON WED...BUT NOW INDICATES BEST H85-H7 UVV'S/POS OMEGAS...LL MOISTURE CONVERGENCE...AND INSTABILITY FOR MORE SIGNIFICANT STORMS PUSHES SOUTH ACRS MO WED AFTERNOON...AND ACRS CENTRAL IL WED NIGHT. THESE PARAMETERS DO CLIP FAR SOUTH- SOUTHEAST CWA THOUGH...MAINLY FROM 00Z-06Z THU. MAY REMOVE WED NIGHT THUNDER WORDING ACRS NORTH. FWC AND FAN GUIDANCE MAY ACTUALLY NOT BE SO BAD IN LIGHT OF TODAY/S WARM UP AND SNOW MELT. STILL LOOK TO BE AT LEAST A CATEGORY HIGH THOUGH AND WILL UNDERCUT HIGHS. LOWS MAY ONLY BE A TAD HIGH LOOKING AT INFILTRATING SFC DPTS AND ADDITION DUE TO SNOW MELT. ...EXTENDED...THU-FRI-SAT... LOOKS LIKE MILD WX TO CONTINUE FROM END OF THE WEEK INTO THE FIRST PART OF THE WEEKEND.MRF AND CANADIAN NOW A BIT WEAKER WITH NEGATIVELY TILTED BUT OPEN UPPER WAVE DEPARTING DVN CWA REGION ON THU...WHILE THE EUROPEAN THIS RUN SOMEWHAT FURTHER SOUTH BUT STILL MAINTAINS INITIALLY CLOSED UPPER LOW RIGHT OVER THE CWA EARLY ON THU. IN ANY CASE AS LOWER AND UPPER LEVEL SYSTEMS DEPART...WRAP AROUND/BACKLASH PRECIP STILL LOOKS GOOD...ESPECIALLY FOR FIRST HALF OF DAY. SOUTHEAST PORTIONS OF CWA MAY STILL HAVE SOME LINGERING CONVECTION EARLY...BUT WILL MAINTAIN STRAIGHT RAIN WORDING FOR NOW. FRIDAY LOOKS INTERESTING. MRF...CANADIAN...AND EURO ALL INDICATE ANOTHER...BUT MUCH DEEPER SPRING-LIKE NEGATIVELY TILTED L/W TROUGH AMPLIFYING ACRS THE WESTERN PLAINS. CANADIAN THE LEAST IMPRESSIVE OF THE BUNCH AND MORE PROGRESSIVE...WHILE THE MRF AND EURO ARE DEEPER AND THUS SLOWER WITH SFC AND UPPER LEVEL LOWS. EURO JUST INITIATES FURTHER SOUTH THAN THE MRF. THIS DYNAMIC...NEG TILTED SYSTEM REALLY WRAPS UP AS IT PULLS NORTHWARD TO A GENERAL INL LOCATION BY 12Z SAT. IF THIS SCENARIO PANS OUT...ALL THE DYNAMICS ARE THERE COMBINED WITH LOW TO MID LEVEL THTA-E ADVECTION STRAIGHT FROM THE GULF AND INSTABILITY FOR STRONG CONVECTION/THUNDERSTORMS FRI AFTERNOON AND NIGHT. SYSTEM OF THIS MAGNITUDE MAY BE INITIALLY BEING HANDLED TOO QUICKLY BY LONG RANGE MODELS AND ACTIVITY MAY BE MORE OF FRI NIGHT INTO SAT MORNING/LESS IDEAL T-STORM TIME OF DAY/ ...BUT MAY INTRODUCE THUNDER POTENTIAL ANYWAY. WARMEST TEMPS OF THE WEEK A GOOD POSSIBILITY FRI AS STEEPLY AMPLIFIED SOUTHERLY FLOW SHOOTS UP ENTIRE MS RVR VALLEY OUT AHEAD OF SYSTEM. BOUNDARY LAYER TO H85 TEMPS EVEN ON COOLEST MODEL...STILL SUPPORT CHANCE OF A 60 DEGREE READING IF SNOW IS GONE. AS OF NOW... EAST IA/NORTHWEST IL LOOKS TO GET DRY-SLOTTED ON SAT BY BOTH MRF AND EURO AND MAY GO PRECIP-FREE. TEMPS DO LOOK TO COOL HOWEVER AS COLDER H85 TEMPS GET ENTRAINED ACROSS THE AREA FROM THE NORTHWEST. .DVN... IA...NONE. IL...NONE. MO...NONE. JDH il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 230 PM CST MON FEB 21 2000 FOG POSSIBILITIES AND PRECIP THREAT ARE THE MAIN ISSUES TODAY. IN THE VERY SHORT TERM BAND OF WEAK CONVECTION OVER NORTHERN MO ASSOCIATED WITH 850 MB CONVERGENCE AND SOME INSTABILITY ABOVE THAT LEVEL. THIS IS FORCING IS FORECAST BY RUC TO WORKS ITS WAY EAST OR EAST-NORTHEAST TONIGHT. SUPPOSE SOME SPRINKLES COULD COME OF THIS LATER TONIGHT SOUTHERN CWA, BUT WILL LET EVENING SHIFT PLAY THAT BY EAR. AS PER PMDHMD MODELS HAVE SOME INITIAL ANALYSIS PROBLEMS OFF THE CALIFORNIA COAST AND FURTHER, WITH THE EDGE TO THE NGM/AVN ON PLACEMENT AND INTENSITY OF A COUPLE SURFACE AND UPPER SYSTEMS. 500 MB SOLUTIONS OF NGM AND AVN FASTER, YET DEEPER WITH CENTRAL PLAINS TROUGH AND PREFERRED. EVEN WITHIN SIMILAR LOW LEVEL WIND FIELD, AVN HOLD BEST LOW LEVEL MOISTURE/PRECIPITABLE WATER FIELDS FARTHER WEST THROUGH 48 HOURS THEN NGM. HOWEVER PRESENCE OF 850 MB JET UPSTREAM FROM CWFA AND A WEAK VORTICITY LOBE SWINGING THROUGH SUGGEST A MODERATE POP FOR TUESDAY NIGHT...HIGHEST WESTERN SECTIONS. LIKELY POPS FOR WEDNESDAY PER BOTH SETS OF MOS. STRATUS/FOG/DRIZZLE FORMATION STILL AN ISSUE AS TO TIMING AND LOCATION. HIGH DEWPOINTS PUSHING NORTHWARD A BIT SLOWER THAN EARLIER EXPECTED, MEANING AFFECTED AREA FOR FOGGY CONDITIONS LIKELY SHRINKING NORTHWARD AS SNOW COVER ERODES FROM THE SOUTH. BEST LOW LEVEL DEWPOINT SURGE PRIMARILY TO THE WEST OF OUR AREA AT THIS TIME AND AGAIN, AVN/NGM SEEM TO HAVE THE EDGE HERE IN TREND. MAIN FOG THREAT WOULD SEEM TO BE IN NORTH CENTRAL SECTIONS LATE TONIGHT AND POSSIBLY SPREADING INTO NORTHEAST IL ON TUESDAY AS HIGHER DEWPOINT EDGE EASTWARD. AFFECTED AREA SHOULD BE NORTH OF I-80 OR EVEN I-08. EVEN SO, ENOUGH WIND TO PROBABLY KEEP MOST AREAS VISIBILITIES ABOVE THRESHOLD FOR ANY ADVISORIES. SOUTHERN SECTIONS TO HAVE LESS FOG, BUT STRATUS/STRATOCU AND SOME DRIZZLE STILL POSSIBLE WITH INVASION OF 50 DEGREE DEWPOINT AND CONTINUED INVERSION ON WEDNESDAY. MOS TEMPS FOR TUESDAY HIGHS STILL TOO HIGH AT RFD...WELL INTO THE SNOW COVER AND NGM MOS STILL ABOUT 5 DEGREES HIGH AT ORD. .CHI...NONE KAPLAN il