AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 925 PM CST TUE FEB 15 2000 LATEST SURFACE ANALYSIS...HAS COLD FRONT IN NORTHERN OK...WITH A PRE-FRONTAL TROF EXTENDING FROM A LOW NORTH OF ABI TO SOUTH OF SPS TO BETWEEN PRX AND ADM...WITH DRY LINE FROM EAST OF ABI TO WEST OF SJT. LATEST RUC MOVES DRY LINE A LITTLE WEST DURING THE NIGHT... WHILE FRONT CONTINUES TO MOVE SOUTH...AND SHOULD EXTEND FROM NORTH MS INTO SOUTHERN AR THEN WEST ALONG THE LA/AR BORDER INTO NORTHEAST TX A LITTLE SOUTH OF THE RED RIVER BY 16/12Z...THIS IS A LITTLE SLOWER THAN MORNING PROGS SHOWED AND LOOKS REASONABLE. RUC INDICATES ENOUGH ISENTROPIC LIFT (295K) FOR POSSIBLE TSTMS NORTH OF BOUNDARY LATE TONIGHT PER SPC UPDATE. WILL UPDATE TO ADD THUNDER TO AREAS EXPECTED TO BE NORTH OF FRONT LATE TONIGHT...WILL ALSO NEED TO ADJUST TEMPS JUST A TAD HERE AND THERE. WITH SLOWER MOVEMENT OF FRONT AND UPPER 50S AND LOWER 60S DEW POINTS A LITTLE FARTHER WEST AND NORTH THAN PREVIOUSLY THOUGHT...WILL NEED TO ADD LOW CLOUDS INTO THE TYR/GGG AREA. DON'T THINK FOG WILL BE MUCH OF A PROBLEM EXCEPT SOUTHERN PORTIONS OF CWA...SINCE A 50 KNOT LOW LEVEL JET HAS DEVELOPED ACROSS THE CENTRAL AND NORTHERN SECTIONS. .SHV...NONE. IV la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1110 PM EST TUE FEB 15 2000 APX AND MQT 88D'S SHOWING AN AREA OF SNOW STILL LINGERING OVER CENTRAL AND EAST UPPER MICHIGAN AND THE STRAITS AREA. APX 88D SHOWING WEAKER RETURNS OVER THE REST OF THE FORECAST AREA WITH SPOTTER REPORTS FROM TRAVERSE CITY AND CADILLAC SHOWING LIGHT FREEZING RAIN AND DRIZZLE WITH SOME COATING OF GLAZE TAKING PLACE. THE LATEST SNOWFALL REPORTS FROM EAST UPPER SHOWS SNOWFALL AMOUNTS SINCE THIS AFTERNOON NEAR 6 INCHES. ACROSS NORTHERN LOWER SNOWFALL AMOUNTS HAVE BEEN AROUND 4 TO 5 INCHES ACROSS THE STRAITS SINCE EARLIER THIS AFTERNOON AND AROUND 2 TO 4 INCHES FOR LOCATIONS BETWEEN M-32 AND M-72. THE MAIN BATCH OF SNOW THAT AFFECTED THE AREA THIS AFTERNOON AND EVENING WAS INFLUENCED HIGHLY BY UPPER JET DYNAMICS...500 MB TROUGH AND THE SURFACE LOW ALL CONVERGING OVER EAST UPPER AND EXTREME NORTHERN LOWER. HOWEVER FOR THE OVERNIGHT HOURS...THE LEFT EXIT REGION OF THE UPPER JET MOVES EAST OF THE FORECAST AREA WHILE THE 500 MB VORT MAX/TROUGH AND SURFACE LOW MOVES OVER THE UPPER GREAT LAKES. THE SOUTHERN PORTIONS OF THE FORECAST AREA WILL BE CAUGHT IN BETWEEN THE SURFACE LOW MOVING OVERHEAD EARLY IN THE OVERNIGHT PERIOD AND THE APPROACHING UPPER LOW. IR STLT LOOP SHOWS THE MID AND UPPER LEVEL CLOUD COVER HAS DIMINISHED OVER EASTERN WISCONSIN AND THE WESTERN GREAT LAKES. THEREFORE THE SOUTHWEST PORTIONS OF THE FORECAST AREA CONTINUES TO BE AFFECTED BY FREEZING RAIN/DRIZZLE. RUC AND MESO ETA MODEL SOUNDINGS SHOW THE ENTIRE SOUNDING BELOW FREEZING OVERNIGHT FOR TVC AND CAD AREAS WITH MID AND UPPER LEVEL MOISTURE ABSENT UNTIL AFTER 09Z. THE CLOUD LAYER TEMPERATURES WILL BE -10C OR WARMER WITH WEAK WIND SHEAR NOTED AT THE TOP OF THE CLOUD LAYER. THIS ALL SUPPORTS THE FREEZING RAIN/DRIZZLE CURRENTLY BEING REPORTED OVER THE WESTERN GREAT LAKES. WINDS TURN NORTHWEST OVERNIGHT WITH LAKE EFFECT SNOW EXPECTED BY DAWN IN THE LAKE MICHIGAN SNOWBELTS WITH LIMITED ADDITIONAL ACCUMULATIONS EXPECTED. WILL PUT THE SOUTHWEST PORTIONS OF THE FORECAST AREA IN A WINTER WEATHER ADVISORY FOR THE FREEZING RAIN EARLY AND LIGHT SNOW LATE. WILL KEEP THE SNOW ADVISORY FOR EAST UPPER AND STRAITS AREA FOR THE ADDITIONAL 1 TO 3 INCHES OVERNIGHT. .APX...SNOW ADVISORY...OVERNIGHT...MIZ008-015-016>019. WINTER WEATHER ADVISORY...OVERNIGHT...MIZ020>022-025>028-031>033. SWR mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EST TUE FEB 15 2000 MAIN FCST CONCERNS PACKAGE SHIFT FROM ONGOING HEAVY SNOW EVENT THIS EVENING TO LAKE EFFECT SNOW POTENTIAL LATE TONIGHT INTO WEDNESDAY NIGHT. WV/IR IMAGERY SHOWED STRONG VORT TO NE MN WITH IMPRESSIVE SHIELD OF COLD CLOUD TOPS ACRS UPR MI AND LK SUPERIOR. AT THE SFC...LO PRES WAS NEAR RST AT 20Z WITH GREATEST PRESSURE FALLS FROM NRN IL INTO SE WI. COMPOSITE RADAR AND SFC OBS INDICATED HEAVIEST SNOW IN FAVORED POSITION NEAR SRN PORTION OF COLDER TOPS WITH VSBYS AOB 1/2SM AND SNOWFALL RATES AOA 1 INCH/HR. SNOWFALL REPORTS INDICATED 5-7 INCH AMOUNTS ALREADY OVER NRN WI AND WRN UPR MI WITH 2 TO 4 INCH AMOUNTS MQT TO IMT-ESC AND CRYSTAL FALLS. HEAVY SNOWFALL SUPPORTED BY STRONG UPR LVL DIV...850-500 QVECTOR CONVERGENCE AND 290K-300K ISENTROPIC ASCENT AHEAD OF POTENT SHRTWV. IN THE SHORT TERM...MDLS IN REASONABLE AGREEMENT IN HANDLING SYSTEM AS IT PASSES THROUGH THE AREA. HOWEVER...TREND WITH THE VORT HAS BEEN TOWARD A TRACK A BIT FARTHER TO THE NORTH...PER WV LOOP...RADAR AND 18Z RUC. EXPECT SNOW TO LINGER TIL BACK EDGE OF FORCING ASSOCIATED WITH SHRTWV MOVES THROUGH THE AREA BTWN 00Z-06Z. SOME LAKE ENHANCEMENT COULD ADD TO THE ALREADY IMPRESSIVE SYNOPTIC TOTALS. AS LLVL WINDS VEER FROM THE EAST TO THE NORTHEAST AND NORTH OVERNIGHT WITH LK-H85 DLT/T AROUND 12C...ADDED MOISTURE AND UPSLOPE FLOW SHOULD BOOST SNOWFALL...PARTICULARLY FOR HIGHER TERRAIN NEAR IWD AND MQT. HRLY BUFKIT WINDS SHOW DEPTH OF NE FLOW INCREASING FROM 00Z-06Z DURING SAME PERIOD BEST LIFT IS DEPARTING. THIS WOULD LEAVE BEST WINDOW FOR ENHANCEMENT FROM 02Z-05Z. PROCESS ALREADY UNDERWAY NEAR IWD...PER KDLH VWP. SO...WILL ADD ANOTHER 1-3 INCHES ONTO SYNOPTIC AMOUNTS. SNOW WILL TRANSITION TO PURE LES BTWN 06Z-12Z AS DLT/T LOWERS TO 18C...SUBSIDENCE INCREASES AND INVERSION HGTS LOWER TO 3-4K FT AS WINDS VEER TOWARD 340. WEDNESDAY...WINDS AROUND 340 FCST TO GRADUALLY BACK TOWARD 300. ONT-P59 AND AREAS EAST OF MARQUETTE WILL BE FAVORED FOR LES AS DLT/T DROPS TO AROUND 20C. WL GO WITH LIGHTER AMOUNTS THAN SUGGESTED BY DECISION TREE GIVEN CONTINUED LOW INVERSION HGTS NEAR 3K FEET WITH STRONG SUBSIDENCE AND 850-700 DRYING. LONGER FETCH INTO ERN UPR MI SHOULD BRING POTENTIAL FOR SLIGHTLY GREATER AMOUNTS THAN WRN UPR MI. WEDNESDAY NIGHT INTO THURSDAY NIGHT...ANY LINGERING LES WINDS DOWN EARLY WED NIGHT WITH BACKING WINDS AND WAA SETTING IN. ADDED MENTION OF CHANCE POPS FOR LATE THUR WEST AND ACRS AREA THURSDAY NIGHT AHEAD OF NEXT WEAK SHRTWV MOVING TOWARD AREA...PER ETA AND 48-72 HR AVN. EXTENDED...MDLS IN REASONABLE AGREEMENT WITH KEEPING UPR MI IN A GENERALLY DRY PATTERN ONLY AFFECTED BY WEAK NRN STREAM SHRTWVS. ENOUGH COLD AIR FOR WEAK LES MAINLY FRIDAY. .MQT...WINTER STORM WARNING TONIGHT MIZ002-005-009 ...WINTER STORM WARNING TONIGHT INTO WEDNESDAY MIZ006 ...SNOW ADVISORY EARLY TONIGHT MIZ004-007-010>014 JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1210 PM EST TUE FEB 15 2000 ...SN ENTERING UPR MI... 88D RETURNS AND METARS NOW SHOWING BROAD AREA OF SN W/ VSBY BLO 1SM BEGINNING TO ENTER THE SOUTHWEST FA ATTM. SFC OBS AND SPOTTER REPORTS SUBSTANTIATE THIS AS SN NOW REPORTED AT ASX...IWD...IRON RIVER...AND IMT. TIGHTLY WOUND VORT MAX OVR NRN MN CONTINUES TO PUSH EAST AS DIPICTED BY WV AND IMPRESSIVE BAROCLINIC LEAF ON IR SAT. VORT IS REFLECTED BY TIGHTLY PACKED STORM W/ CENTRAL PRESSURE OF 1000MB OVER SOUTHWESTERN MN ATTM. SFC ANALYSIS THIS MORNING REVEAL STORM HAS MOVED ABOUT 200 MILES SINCE 12Z THIS MORNING FM SCENTRAL ND. LOW IS MOVING EAST OR SLIGHTLY NORTHEAST TOWARDS BEST 3HR PRES FALLS OF 4MB OVR W CENTRAL WI PER MSAS ANALYSIS. SN WL SPREAD FM WEST TO EAST THIS AFTERNOON AND WL HAVE LITTLE DIFFICULTY GETTING GOING WITH RELATIVELY MOIST BLYR IN PLACE. NEW MODEL QPFS ARE SIMILAR TO PREVIOUS RUNS AND SHRT TERM MODELS (MESOETA AND RUC) STILL POINT TO NARROW STRIPE OF HEAVIEST SNOWFALL ACROSS S CENTRAL UPPER MI FM IWD TO IMT TO ESC...WHERE 3 TO 5 INCHES SHOULD FALL BY EVENING. ACROSS NW BELIEVE AMOUNTS WL BE MORE IN LINE W/ 2-4 INCHES IN ONT AND THE KEWEENAW. SINCE MAJORITY OF SN HAS JUST BEGUN ACROSS WESTERN UPR PENINSULA SN AMOUNTS WL GO RELATIVELY UNCHANGED FM PREVIOUS ZONE PKG...WITH ONLY EXCEPTION OUT EAST IN SCHOOLCRAFT COUNTY WHERE AMOUNTS WERE TRIMMED SLGTLY THIS AFTN AND BUMPED UP SLGTLY TONIGHT. .MQT...WINTER STORM WARNING THIS AFTERNOON AND TONIGHT MIZ005 ...WINTER STORM WARNING THIS AFTERNOON THROUGH WEDNESDAY MIZ006 ...SNOW ADVISORY MIZ002-004-007-009>014 JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI ISSUED BY NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1130 AM EST TUE FEB 15 2000 WAA/ISENTROPIC LIFT SNOW ENTERING WRN MI ATTM AND HAS A NEWD DRIFT. LATEST RUC AND NEW 12Z ETA SUPPORTS GOING IDEA OF BEST PCPN CHCS IN THE EXTREME NRN PORTION OF SE LWR THIS AFTERNOON. WILL CONTINUE THE GOING FCST OF SNOW DEVELOPING ACROSS BAY/HURON/MIDLAND COUNTIES AND HOLD OFF ON ANY MENTION OF ACCUMULATIONS UNTIL TONIGHT. PCPN CHCS LOWER CONSIDERABLY FARTHER SOUTH THIS AFTERNOON ACROSS SE LWR MI WHERE RUC PROGS HIGHER CONDENSATION PRESSURE DEFICITS. 12Z DTX SOUNDING ALSO VERY DRY BELOW 500 MB. WILL MAINTAIN CHANCE POPS IN FNT AREA BUT KEEP THE SRN AREAS DRY...ALTHOUGH A SPRINKLE OR FLURRY SEEMS POSSIBLE AS TAIL END OF WAA PCPN DRIFTS ACROSS. RUC SHOWS SIGNIFICANT WARMING SURGING IN AT 850 MB THIS AFTERNOON SUGGESTING MORE OF A MIXY PCPN SCENERIO COULD SET UP BY EVENING. HOWEVER HOURLY FCST SOUNDINGS SHOW WET BULB PROFILES REMAINING BELOW ZERO SO WILL KEEP PCPN TYPE ALL SNOW. 3.9 MICRON AND VISIBLE SATELLITE IMAGERY SHOWS A LARGE HOLE IN THE LOW CLOUDS OPENING UP OVER SE LWR MI AND NW OH. WILL HAVE TO ACCOUNT FOR THIS EARLY ON...AND IT MAY IMPACT HIGH TEMPS AS WELL. PCPN CHANCES LOOK MUCH BETTER FOR ALL OF SE LWR TONIGHT AS SHORT WAVE TROUGH COMES THROUGH. .DTX...NONE. MEADE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 830 PM CST TUE FEB 15 2000 FORECAST HAS BEEN UPDATED FOR DRYING TREND. 700 MB TROUGH IS INTO WI WITH CONSIDERABLE CLEARING OVER MINNESOTA. MORE CLOUDINESS IS EXPECTED TO MOVE OVER THE STATE LATER...ASSOCIATED WITH SHORT WAVE TROUGH IN NW WY. SURFACE LOW IS IN SOUTHEAST WISCONSIN WITH MAXIMUM ISALLOBARIC GRADIENT OVER WRN WI. WIND SHOULD CONTINUE TO DECREASE. LATEST RUC MODEL SUPPORTS GOING TEMPERATURE FORECAST. .MSP...NONE SCOTT mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 315 PM CST TUE FEB 15 2000 THE SNOW CONTINUES TO PILE UP...WITH LAKE SUPERIOR BECOMING INVOLVED NOW. AMOUNTS WILL HAVE TO BE ADJUSTED UPWARD AGAIN. ANOTHER BAND OF HEAVY SNOW JUST FORMED WEST OF THE TWIN PORTS. WILL KEEP THE WARNING GOING FOR THE TWIN PORTS INTO THE EVENING. WILL ALSO KEEP THE WARNING GOING FROM BAYFIELD INTO IRON COUNTIES...AS CONDITIONS BECOME MORE FAVORABLE FOR LAKE EFFECT/LAKE ENHANCEMENT. MODELS WERE FAIRLY CLOSE ON THE VORT PLACEMENT. WILL CONTINUE TO GO WITH THE RUC...WHICH DID A BEAUTIFUL JOB ON THE QPF FIELDS TODAY. BEYOND THAT...WILL STICK WITH AVN DUE TO LIMITED FORECAST TIME. VORT NOW MOVING THROUGH CENTRAL MINNESOTA. THE MAIN EFFECTS OF THE VORT SHOULD MOVE OUT OF THE MINNESOTA SIDE BY 7 PM...AND NORTHWEST WISCONSIN BY MIDNIGHT. STILL SOME CONCERN ABOUT THE SOUTH SHORE ZONES. WILL UP THE SNOWFALL AMOUNTS IN THE NORTHERN COUNTIES OF WISCONSIN...WITH 10 INCH AMOUNTS JUST RECEIVED FROM HURLEY AND UPSON. WILL BE PESSIMISTIC IN BRINGING CLEARING TO THE SOUTHERN HALF OF THE CWA TONIGHT...ESSENTIALLY DUE TO THE SHORTWAVE MOVING THROUGH THE DAKOTAS. THE NORTHERN ZONES SHOULD SEE SOME PARTIAL CLEARING WITH STRONG NVA. MAY STILL SEE SOME PARTIAL CLEARING IN THE SOUTH...BUT FOR NOW WILL GO WITH MORE CLOUDS. FAN/FWC TEMPS FAIRLY CLOSE AND HAVE NOT STRAYED TOO FAR. NEXT PROBLEM IS CHANCE OF SNOW LATE WEDNESDAY NIGHT AND THURSDAY. WILL GO WITH MID RANGE POPS TO START THE BALL ROLLING IN THE SOUTH. THE SYSTEMS OF LATE HAVE BEEN EFFICIENT SNOW PRODUCERS...OBVIOUSLY. SO WILL BUMP UP FAN/FWC POPS A BIT. .DLH...HEAVY SNOW WARNING THIS EVENING MNZ037-WIZ001. HEAVY SNOW WARNING TONIGHT WIZ002>004. DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1215 PM CST TUE FEB 15 2000 SNOW CONTINUED TO PILE UP ACROSS CENTRAL MINNESOTA AND NORTHWEST WISCONSIN THIS MORNING. RUC WAS DOING A TERRIFIC JOB WITH THE PLACEMENT OF THE QPF FIELDS...BUT ONLY HINTED AT THE VORT MOVING THROUGH AITKIN COUNTY. SNOWFALL RATES HAVE BEEN ON THE ORDER OF 2 INCHES AN HOUR IN DULUTH WITH 35 TO 40 DBZ RETURNS ON DLH RADAR AT TIMES. HAVE UPGRADED CARLTON AND SOUTHERN SAINT LOUIS...AS WELL AS THE FOUR NORTHERN MOST COUNTIES IN WISCONSIN TO A HEAVY SNOW WARNING. .DLH...HEAVY SNOW WARNING MNZ037-038-WIZ001>004-006>009. SNOW ADVISORY MNZ025-033>036. DAP mn FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 820 PM CST TUE FEB 15 2000 FCST CHALLENGE TONIGHT...CLOUD TREND AND TEMPS. SFC LOW MOVING QUICKLY EAST...NOW IN ERN WI. WATER VAPOR SHOW NRN STREAM SHORT WAVE DROPPING SOUTH THRU MB/NW ONTARIO WITH CLEARING SKIES BEHIND IT. 12Z MODELS/RUC AND 18Z MESO ETA ALL SHOW THIS DRIER AIR AND SUB ZERO DEW PTS MOVING MORE SOUTHEAST TONIGHT TOWARD FAR NRN MN. O/W WATER VAPOR AND IR SHOW ANOTHER VORT MAX WITH SPIN IN THE CLOUDS JUST SOUTHWEST OF BIS. KBIS 88D AND OBS SHOWING SOME VERY LIGHT SNOW WITH THIS FROM ISN TO BIS. 00Z RUC PICKS UP ON THIS SHORT WAVE AND SHOWS IT DROPPING ESE INTO ERN SD OVERNIGHT. THIS WAVE MAY PRODUCE A VERY FLURRIES IN SW ZONES. WILL BREAK OUT LIBSON/VALLEY CITY AREA FOR A FEW FLURRIES TONIGHT. O/W DRY. THAT LEAVES...LOTS OF CI/AC OVER THE MAJORITY OF THE CWFA TONIGHT. ANY THIN SPOTS WILL ALLOW QUICK TEMP DROP...SPCLY OVER FRESH SNOW COVER IN SRN CWFA (AS SHOWN BY 1F TEMP AT 02Z AT PKD). WILL TREND UPDATE TOWARD SKIES BECMG PTLY CLDY FAR NE ND AND FAR NW MN ZONES AND KEEP MUCH OF THE REST OF THE CWFA MSTLY CLDY. WILL LOOK OVER TEMPS...BUT DONT EXPECT BIG CHANGES FROM WHAT IS IN ZONES. UPDATE OUT BY 9 PM. FINAL SNOWFALL TALLY AROUND CWFA SHOW 6-8 INCHES FERGUS FALLS/WADENA WITH WIDESPREAD 3 TO 5 INCH BAND ALONG AND SOUTH OF A VALLEY CITY TO FARGO TO DETROIT LAKES LINE. NONE TO ONLY A TRACE REPORTED DVL-GFK-BJI NORTH. .FGF...NONE. RIDDLE nd AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 1020 AM CST TUE FEB 15 2000 WRAPAROUND -SN FROM FIRST S/W AND THE INFLUENCES FROM A WEAKER S/W ROTATING THRU THIS AFTN WILL CONTINUE TO BRING -SN TO NC AND NE SD AND WC MN. ADDITIONAL ACCUMULATIONS OF 1 TO 2 INCHES ARE POSSIBLE. THE RUC...ETA AND NGM ALSO SHOW A THIRD S/W MOVING ACROSS THE CWA THIS EVENING. THEREFORE...-SN WILL CONTINUE INTO THIS EVENING ACROSS THE NORTH WITH A CHC ACROSS THE REST OF THE CWA. WITH LOW CLOUDS AND CAA...TEMPS WILL SLOWLY FALL THROUGH THE AFTN. NE WINDS AT 15 TO 30 MPH WILL GENERATE SOME BLOWING SNOW...ESPECIALLY IN NE SD AND WC MN. UPDATED FORECAST TO MAKE MANY CHANGES. .ABR...NONE MOHR sd SOUTH CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 935 PM CST TUE FEB 15 2000 LOW CLOUD FORMATION WILL BE DELAYED FOR ANOTHER FEW HOURS SO WILL TRIM BACK CLOUD WORDING OVER THE DRIER WESTERN SECTIONS. LATEST RUC MODEL STILL SUGGESTS A POTENTIAL FOR DRIZZLE ALONG AND EAST OF THE ESCARPMENT. THUS THE REST OF THE FORECAST IS IN GREAT SHAPE. .EWX...NONE. 18/2 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 245 PM CST TUE FEB 15 2000 MAIN FORECAST PROBLEMS IN THE SHORT TERM ARE SNOW CHANCES TONIGHT AND THEN SNOW CHANCES AGAIN ON THURSDAY. 19Z SURFACE ANALYSIS PLACED LOW PRESSURE ACROSS SOUTH CENTRAL MINNESOTA/NORTH CENTRAL IOWA WITH A WARM FRONT EXTENDING OUT OF THE LOW INTO NORTHERN WISCONSIN WHILE A COLD FRONT WAS LOCATED ACROSS WESTERN IOWA. MOSAIC OF SURROUNDING WSR-88DS INDICATES THAT THE HEAVIEST SNOW CONTINUES TO FALL WELL NORTH OF THE ARX FORECAST AREA. LOCALLY...THE KARX WSR-88D SHOWS SOME SNOW ACROSS CLARK/TAYLOR COUNTIES OF NORTH CENTRAL WISCONSIN. 12Z NGM/ETA DID NOT DO A GOOD JOB OF HANDLING THE TWO VORTICITY CENTERS ACROSS THE DAKOTAS. THE RUC AND 12Z AVN HAVE DONE A BETTER JOB WITH THESE FEATURES BUT I PREFER THE ETA/NGM HANDLING OF THE SURFACE FEATURES WITH THE AVN LOOKING TOO SLOW. WILL GO WITH A BLEND OF THE MODELS IN THE SHORT TERM AND GO CLOSER TO THE AVN IN THE LATER PERIODS. THE SURFACE LOW IS FORECAST TO MOVE RAPIDLY TO LOWER MICHIGAN BY MIDNIGHT. THE STRONGEST QG-FORCING AT VARIOUS LAYERS ALONG WITH THE VERTICAL VELOCITES ALSO MOVE RAPIDLY EAST THIS EVENING. MODEL GENERATED QPF IS FAIRLY LIGHT TONIGHT ACROSS THE ARX FORECAST AREA AND AGREE THAT THIS SHOULD BE THE CASE. WILL END THE SNOW THIS EVENING IN ANY AREAS THAT IT IS LINGERING AT FORECAST TIME WITH LITTLE ADDTIONAL ACCUMULATION EXPECTED. ONCE THE LOW PASSES...COLD AIR ADVECTION WILL SPREAD ACROSS THE AREA. THE PRESSURE GRADIENT WILL BE STRONG AND WOULD EXPECT NORTHWEST WINDS TO PICK UP QUITE A BIT. HIGH PRESSURE IS THEN FORECAST TO INFLUENCE THE AREA FOR WEDNESDAY WITH TIME CROSS SECTIONS FROM ACROSS THE AREA SHOWING A DECREASE IN MOISTURE. WILL KEEP THE AREA MOSTLY CLOUDY TONIGHT...BUT GO WITH PARTLY CLOUDY WORDING FOR WEDNESDAY. THERE IS SOME CONCERN ABOUT A WAVE THAT IS FORECAST TO MOVE ACROSS THE AREA FOR WEDNESDAY...BUT MOISTURE LOOKS TO BE TOO LIMITED AND THE FORCING TOO WEAK TO CAUSE MUCH TROUBLE...SO AGAIN PARLTY CLOUDY SEEMS REASONABLE. WARM AIR ADVECTION BEGINS AGAIN ON WEDNESDAY NIGHT INTO THURSDAY. LOW LEVEL MOISTURE IS FORECAST TO INCRASE WEDNESDAY NIGHT SO SKIES SHOULD AGAIN BECOME CLOUDY...BUT IT APPEARS THAT THE DEEPEST MOISTURE DOES NOT ARRIVE UNTIL THURSDAY. VERTICAL VELOCITIES ARE ALSO FORECAST TO INCREASE DURING THE DAY THURSDAY ALONG WITH THE ISENTROPIC LIFT. WILL PUT IN A CHANCE OF SNOW FOR NOW...BUT WE WILL HAVE TO WATCH LATER MODEL RUNS TO SEE HOW THIS COMES TOGETHER SINCE RIGHT NOW IT LOOKS LIKE ACCUMULATIONS ARE A GOOD POSSIBILITY. LOW PRESSURE IS THEN FORECAST TO MOVE FROM THE CENTRAL PLAINS INTO THE OHIO VALLEY THURSDAY NIGHT INTO FRIDAY. NOGAPS AND THE MRF STILL INDICATE THE POSSIBLITY OF SOME LINGERING SNOW ON FRIDAY SO WILL NOT ADJUST THAT PORTION OF THE FORECAST...BUT IT DOES APPEAR THE BEST CHANCES WOULD BE EARLY IN THE DAY. THE WEEKEND LOOKS DRY AS HIGH PRESSURE AGAIN TAKES OVER THE AREAS WEATHER. LOOKING AT TEMPERATURES NGM/AVN GUIDANCE VALUES ARE IN RELATIVE AGREEMENT THROUGH THE PERIOD AND WILL GENERALLY FOLLOW. THANKS TO GRB/MPX/DVN/MKX FOR COORDINATION. .LSE...NONE.. KING wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 922 AM CST TUE FEB 15 2000 14Z SURFACE OBSERVATIONS AND SATELLITE IMAGERY SHOWING MAIN ENERGY ACROSS THE DAKOTAS. SNOW ASSOCIATED WITH THERMODYNAMIC FORCING HAS MOVED EAST OF THE FORECAST AREA. THUS...ONLY REMAINING CHANCE OF SNOW WILL BE FROM THE DAKOTA DISTURBANCE. 12Z RUC HAS GOOD HANDLE ON SNOW ASSOCIATED WITH THE SYSTEMS DYNAMIC FORCING. AT THE PRESENT TIME...LOOKS AS THOUGH THE HEAVIEST SNOW WILL REMAIN NORTH OF THE FORECAST AREA. NEVER THE LESS...WILL HOLD ON TO CURRENT HEADLINES AS POSTED UNTIL THE STORM PASSES. WILL INDICATE A LESSER EVENT THAN CURRENTLY ADVERTISED FOR AREAS NEAR AND SOUTH OF ROCHESTER AND LA CROSSE. .LSE...WINTER STORM WARNING...TODAY...NORTH CENTRAL WI...WIZ017. WINTER WEATHER ADVISORY TODAY...CENTRAL WI...WIZ029. KRC wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 337 AM CST WED FEB 16 2000 SURFACE HIGH PRESSURE BUILDING ACROSS THE FORECAST AREA TODAY WHILE SOMEWHAT CYCLONIC NORTHWEST FLOW CONTINUES ALOFT. 06Z RUC AND ETA BOTH SHOWING 700 MB RELATIVE HUMIDITY IN EXCESS OF 60 PERCENT ACROSS THE CWA TODAY ALONG WITH SOME POSITIVE MID LEVEL THETA-E ADVECTION. ENHANCED IR LOOP INDICATING PATCHES OF AC HERE AND THERE AND WILL INDICATE PARTLY CLOUDY IN THE ZONES. GUIDANCE HIGH TEMPERATURES LOOK PRETTY GOOD WITH HIGH TEENS IN THE NORTH AND LOWER 20S IN THE SOUTH. NEXT POSSIBLE SNOW MAKER IS ASSOCIATED WITH UPPER LOW APPROACHING CALIFORNIA THIS MORNING. MODELS INITIALIZED FAIRLY WELL WITH THIS FEATURE BUT AS TIMES PROGRESSES THE ETA WEAKENS THE SHORT WAVE MUCH MORE THAN THE AVN/NGM BEYOND 24 HOURS. RECENT HISTORY SHOWS THE ETA HAS BEEN HAVING PROBLEMS WITH INTENSITY OF THE SHORT WAVES IN THIS SPLIT FLOW. AVN/NGM BEYOND 24 HOURS ARE ALMOST IDENTICAL AND INDICATE THE POSSIBILITY OF HEAVY SNOW ACROSS FAR SOUTHERN MN THURSDAY AFTERNOON/NIGHT. DPROG/DT ON THE AVN AT 48 HOURS SHOWS A 999MB LOW MOVING A LITTLE NORTH WITH TIME WITH A CLOSED 700 MB LOW ALONG THE NE/SD BORDER. FAVORED THE AVN/NGM RUNS WITH EVEN THE CANADIAN MODEL SHOWING A 999 MN LOW IN THE PANHANDLE OF OK AT 48 HOURS. AFTER COORDINATION WITH FSD AND LSE WILL ISSUE AN SPS THIS MORNING TALKING ABOUT THE SNOW POTENTIAL ON THURSDAY. IF THE AVN COULD MAINTAIN COURSE AND SPEED...HEAVY SNOW WOULD OCCUR ACROSS FAR SOUTHERN MN AND NORTHERN IA. JUST ABOUT EVERY PARAMETER FOR HEAVY SNOW IS MAXIMIZED ACROSS NORTHERN IA THURSDAY AFTERNOON AND EVENING. COOK TECHNIQUE INDICATES ABOUT 12 DEG OF WAA AT 200. CONVERGENCE/DIVERGENCE COUPLET IS IN PLACE. OMEGA IS MAXIMIZED NEAR 500 MB WHILE 600 MB TEMPERATURES ARE BETWEEN -14 AND -16 DEG C. 12 HR NET VERTICAL DISPLACEMENT IS +60 WHILE MIXING RATIO VALUES APPROACH 3 G/KG BETWEEN 700 AND 750 MB. WILL INTRODUCE SOME SNOW ACROSS THE FAR SOUTH LATE TONIGHT AS WARM ADVECTION GETS UNDERWAY. WILL USE CATEGORICAL POPS ACROSS THE FAR SOUTH ON THURSDAY DECREASING TO CHANCE POPS ACROSS THE FAR NORTHERN MN CWA. MADE ADJUSTMENTS TO THE EXTENDED TO ADD A THURSDAY NIGHT PERIOD AND DRY THINGS OUT ON FRIDAY OVER THE NORTH AND WEST. .MSP...NONE. HILTBRAND mn AREA FORECAST DISCUSSION...CORRECTED FOR POPS NATIONAL WEATHER SERVICE NASHVILLE TN 250 AM CST WED FEB 16 2000 FORECAST QUANDARIES...CLOUD COVER AMOUNTS...PCPN CHANCES AFTER 18Z THU...AND TEMPERATURES. CURRENT AWOS/ASOS OBSERVATIONS...REGIONAL SATELLITE IMAGERY...AND SURFACE/LAPS ANALYSES SHOWING LOW AND MID LEVEL MOISTURE ADVECTION ACROSS CWA. MOISTURE ADVECTION ASSOCIATED WITH A SURFACE COLD FRONT ...PRESENTLY POSITIONED ACROSS THE MISSOURI BOOTHEEL. SOUTHERLY WIND FIELD NOTED AHEAD OF COLD FRONT...ACROSS OUR CWA. 07Z RUC/UPPER AIR CHART ANALYSES DEPICTING WEAK SHORTWAVE APPROACHING WESTERN TN IN PREDOMINATE PROGRESSIVE ZONAL FLOW. 00Z WED REGIONAL MODEL INITIALIZATIONS AND PROGGED EVOLUTION THROUGH 00Z FRI GENERALLY SIMILAR...ESPECIALLY UPPER LEVEL PATTERNS. SURFACE COLD FRONT EXPECTED TO MOVE EAST OF REGION AROUND 12Z WED WITH MIDWEST SURFACE HIGH PRESSURE SYSTEM/S RIDGING INFLUENCING BECOMING MOST DOMINANT AROUND 06Z THU...WITH 4-CORNERS LOW PRESSURE SYSTEM MOVING INTO THE HIGH PLAINS BY 00Z FRI. UPPER LEVEL PATTERN DEPICTS ZONAL FLOW THROUGH 00Z THU WITH "SLIGHT" RIDGING IN FLOW AFTERWARD...WITH MAIN "DIGGING" TROF OVER THE ROCKIES. TODAY...MODEL RH PROGS SHOWING DECREASING CLOUDINESS AFFECTING ENTIRE REGION AFTER 18Z WED. WILL GO CLOSE TO YESTERDAY AFTERNOON/S ZONE SKY CONDITION WORDING FOR TODAY/S ZONES. TONIGHT...WITH SURFACE RIDGING INFLUENCES BECOMING ENTRENCHED BY AROUND 06Z THU...WOULD TEND TO GO WITH MOSTLY CLEAR SKIES. HOWEVER...WITH PROGRESSIVE UPPER LEVEL FLOW PATTERN LATELY...WOULD NOT BE "SHOCKED" TO SEE CWA EXPERIENCE SOME HIGH LEVEL MOISTURE ADVECTION THROUGH 12Z THU...AS MODEL RH PROGS "HINT AT". THURSDAY...MODEL PCPN PROGS INTRODUCING WIDELY SCATTERED/LOW CHANCE POPS CENTRAL AND WEST AFTER 18Z THU IN RESPONSE TO HIGH PLAINS LOW PRESSURE SYSTEM. MODEL INSTABILITY PARAMETERS SHOWING LITTLE IF ANY INDICATION OF TS DEVELOPMENT WITH UPCOMING SYSTEM. HOWEVER...WITH SE WIND SURFACE AND ALOFT...BRINGING IN A WARMER AIRMASS...CAN NOT RULE OUT POSSIBILITY OF TS ACTIVITY ALTOGETHER. DO BELIEVE PCPN CHANCES OVER EASTERN ZONES WILL BE NEGLIGIBLE. MODEL RH PROGS STILL SUPPORT MOSTLY CLOUDY SKY FORECAST FOR ENTIRE REGION. TEMPERATURES...DESPITE NGM MOS UNDERESTIMATING YESTERDAY/S HIGHS...BELIEVE THAT HIGH VALUES ARE MORE IN LINE WITH EXPECTED CONDITIONS THAN AVN FAN FOR TODAY . WILL COMPROMISE ON LOWS FOR WED NIGHT. WITH SE FLOW...AVN FAN "TOO COOL" ON THURSDAY/S HIGHS. WILL TREND TOWARD NGM MOS ACCORDINGLY. PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY... BNA 060/033/057/045 0034 CSV 054/028/053/040 0013 .BNA...NONE. $$ 14 JBW tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KEY WEST FL 1000 AM EST WED FEB 16 2000 QUIET RADAR THIS MORNING AND GENERALLY SUNNY SKIES OVER THE KEYS AS WE ENJOY THE EFFECTS OF THE DRIER AIRMASS IN PLACE OVER THE AREA. SATELLITE SHOWS SCATTERED SMALL CU OR SC OVER ATLANTIC AND STRAITS WATERS...MAINLY OVER THE GULF STREAM. A FEW OF THE CLOUDS ARE DRIFTING ACROSS THE KEYS IN THE NE-E LOW LEVEL FLOW. KEYS TEMPERATURES ARE IN THE MID 70S. C-MAN WINDS ARE NE-E AROUND 10 KT WHILE MTRS REPORT NE-E 5 TO 10 MPH. WILL CONTINUE TO SEE A FEW CU DRIFTING OVER THE KEYS AND DEVELOPING ALONG THE KEYS THIS AFTERNOON...BUT SHOULD BE ENOUGH SUN TO KEEP MOSTLY SUNNY SKIES IN THE FORECAST. ZFP LOOKS ON TRACK AND NO CHANGES ARE NEEDED AT THIS TIME. WILL HOLD OFF ON EXPECTED SLIGHT INCREASE IN MARINE WINDS UNTIL TONIGHT...KEEP NE-E AROUND 10 KT FOR TODAY AS PER MOST RECENT RUC AND MESOETA. .EYW...NONE. JEB fl AREA FORECAST DISCUSSION...RETRANSMISSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 300 AM CST WED FEB 16 2000 LATEST ANALYSIS OF UPPER AIR AND SFC ALONG WITH SATELLITE SHOWS A SETUP FOR A POTENTIALLY VERY SIGNIFICANT SNOWSTORM THU/FRI. ARCTIC HIGH NOW LOCATED IN DAKOTAS IS OVERSPREADING ALL OF THE MIDWEST WWITH COLD AIR. FAST ZONAL JET ACROSS US SHOWS STRONG ENERGY AND BAROCLINICITY TO TAP AND FINALLY A LARGE VIGOROUS UPPER LOW IS NOW APPROACHING CALIFORNIA. THESE FEATURES SETTING REGION UP FOR CYCLOGENESIS WITH OPEN GULF AND WIDESPRAED HEAVY PRECIPITATION FOR CENTRAL UNITED STATES. STRONG PRESSURE RISES AT SURFACE OVER MIDWEST HERALD STRONG CAA ACROSS AREA TODAY WITH ALL AREA NOW BELOW FREEZING AND FREEZING LINE TO PUSH MUCH FIRTHER SOUTH TODAY AS RIDGE AXIS STILL BACK IN HIGH PLAINS DUE TO STIFF NORTH TO NORTHWEST WINDS. SATELLITE SHOWS LARGE CANOPY OF HIGH LEVEL CLOUDS NOW OVER MOST OF WESTERN US AHEAD OF UPPER LOW OFF CALIFORNIA. BOTTOM LINE IS LITTLE QUESTION AS TO SNOW...JUST HOW MUCH AND TIMING AND HEAVY SNOW AXIS ISSUES. ...APPROACHING STORM BIGGEST CHALLENGE THIS FORECAST PERIOD... MODELS INITIALIZE OK AND VERIFY BEST ON UPPER AIR FEATURES WITH SOME PHASING DISCREPANCIES WITH DUMBELL VORT MAX PATTERN OFF CALIFORNIA... BUT OVERALL JET FLOW LOOKS GOOD. STILL 24 HOURS BEFORE MOVES ONSHORE SO INTENSITY AND PHASING LIKLEY NOT RESOLVED TIL TONIGHT. AT SFC...AVN/NGM VERIFY BEST ON GREAT LAKES SFC LOW WHICH USE FIRST 12 HOURS. THEN UPSTREAM ETA FEATURES SEEM MORE REASONABLE FOR SECOND PERIOD AND BEYOND. MODELS BEGIN TO DIVERGE BASED ON THERE NATURAL BIASES ON SFC LOW BY 48 HOURS AND ASSOCIATED PRECIP PATTERNS. SOLUTION USED IS ETA/AVN BLEND WHICH SUGGESTS WIDESPREAD AREAS OF MODERATE TO STRONG ISENTROPIC UPGLIDE AND HEAVY PRECIP OVER MO AND MOVING INTO FORECAST AREA BY LATE THURSDAY. SINCE MODELS TEND TO MOVE SYSTEM ONSHORE TOO QUICKLY AND LATEST RUN ALREADY SHOWS SYSTEM SLOWED DOWN SEVERAL HOURS FROM 24 HOURS AGO. THIS SUGGEST MOST HEAVY PRECIP THU NIGHT AND FRIDAY. CONCERN IS LENGTH OF PRECIP WITH THIS SYSTEM. ETA SHOWS VERY STRONG WAA WITH PRECIPITAION. IF SYSTEM SLOWS DOWN AND STAYS CLOSED LONGER THAN MODELS AS SUGGESTED BY AVN AND NORMAL MODLE BIAS. EXTENDED PERIODS OF SIGNIFICANT SNOWS VIABLE FOR SOUTHERN 1/2 TO 2/3 OF FORECAST AREA. ETA SOUNDINGS SUGGESTS LITTLE CHANCE FOR FREEZING RAIN OR SLEET WITH RAIN/SNOW LINE LIKELY ALONG OR JUST SOUTH OF SOUTH END OF FORECAST AREA BASED ON BL THRESHOLD TEMPS. SINCE HEAVY PRECIP BEYOND PERIOD 3 WILL NOT GO WITH WATCH BUT HIT HARD IN NEW SPECIAL WEATHER STATEMENT. FOR ZONES...WILL EMPHSIZE SIGNIFICANT ACCUMULATIONS POSSIBLE FOR THU NIGHT IN THESE AREAS AND ALSO FRIDAY. IN HAZERDOUS WEATEHR OUTLOOK STATEMENT...WILL MENTION LARGE AREA OF SIGNFICANT SNOW EXPECTED WITH 4 PLUS INCHES POSSIBLE BEFORE ENDING AND ALSO POTENTIAL FOR SIGNIFICANT AREAS OF 8 INCHES OR MORE WITH PROPER CAVEATS OF NEED TO MONITOR TRACK...DEVELOPMENT AND INTENSITY ISSUES. DAY SHIFT SHOULD BE IN BETTER POSITION TO ASSESS WATCH ISSUANCE. NEAR TERM...USE NOWCAST TOOLS TO TIME CLEARING OF LOW CLOUDS ALONG WITH RUC WHICH ALL SUGGEST BECOMING MOSTLY SUNNY. TEMPS TODAY WILL USE FWC GUIDANCE VERSUS FAN WHICH APPEARS TOO COOL AS SNOW COVER NOW BASICALLY ALL GONE EXCEPT NEAR KDBQ. NEAR IDEAL MEX COOLING TONIGHT WITH LIGHT WINDS SUGGEST FWC LOOKS REASONABLE. THEN SLIGHTLY ABOVE FWC THU AHEAD OF MAIN SNOW WITH LIKELY POPS WESTERN PORTIONS AREA BY PM. ...EXTENDED... FOR FRIDAY...ALL MODELS SUPPORT SNOW...POSSIBLY HEAVY WORDING. THEN DRY AND SEASONABLY COOL DAY 4/5 AS HIGH PRESURE MOVES IN. COORDINATED WITH DSM...ILX...LOT AND STL...THX. .DVN...NONE. NICHOLS il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 910 PM EST TUE FEB 15 2000 LOW PRES OVER SRN WI WILL CONTINUE TO TRACK EWD TNGT. RDR ECHOES LOOK FAIRLY WDPSRD ACRS SRN MI BUT ITS MAINLY AC WITH ONLY DTX REPORTING -SN LAST HR (VSBY 9SM). BEST ISEN LIFT AND LOW LVL MSTR WILL REMAIN NORTH OF THE LOW TRACK AND ITS ACRS NRN LOWER MI AND UPR MI WHERE THE SIG PCPN IS OCCURRING. RUC AND MAPS DATA HAVE A GOOD HANDLE ON THE SITN AND INDICATE THIS PCPN WILL TRACK EWD STAYING NORTH OF THE CWA. ITS APPEARING MORE LIKELY THAT CNTRL NY WILL ONLY SEE SOME FLURRIES OR PSBLY A BRIEF PD OF -SN OVERNIGHT WITH LTL OR NO ACCUMULATION...BEST CHC FOR SNOW AND NOMINAL ACCUMS WOULD BE FAR NRN ONEIDA CNTY. MESOETA INDICATES ABOUT 0.10 AT SYR BY 12Z AND IS FURTHER S AND MORE WDPSRD WITH THE PCPN LATER TNGT. WILL CONTINUE TO MONITOR TRENDS BUT INCLINATION AT THIS POINT WILL BE TO LOWER POPS FROM CAT TO LIKELY UP NORTH AND LOWER ACCUMS TO ARND AN INCH. WILL PRBLY LOWER POPS INTO CHC CAT ACRS THE SRN TIER AND NRN PA. LOOKS LIKE CTP IS ALSO LEANING IN THAT DIRECTION BASED ON THEIR AFD. .BGM...NONE. BRADY ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 1010 AM EST WED FEB 16 2000 THE CURRENT ZONE FORECASTS FOR TODAY LOOK FINE. I WILL ADJUST THE WORDING TO SHOW PARTLY CLOUDY SKIES NORTH AND CENTRAL THIS AFTERNOON. THIS IS SUPPORTED BY A DIMINISHING MOISTURE FIELD SEEN IN THE LATEST RUC MODEL RUN. SOME WIND DIRECTION ADJUSTMENTS ARE NEEDED OVER THE NORTH...SINCE THE COLD FRONT HAS ONLY MADE IT TO NORTH-CENTRAL ALABAMA AS OF 10 AM. SATELLITE IMAGERY SHOWS A GREAT DISPLAY OF CONTRAILS OVER SE GA. .ATL...NONE. SCHAUB ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 229 PM CST WED FEB 16 2000 ...SHORT TERM... WATER VAPOR AND PROFILER DATA HAVE A NICE SHORTWAVE MOVING EAST THROUGH ILLINOIS AND INDIANA WITH AN 850 MB RIDGE MOVING ACROSS NEBRASKA AND KANSAS. 500 MB JET STREAK OF 90 KNOTS OVER THE AREA IS MOVING EAST WHILE 110+ KNOTS ARE AT 300 MB. MAIN INTEREST IS FOCUSED ON THE POWERFUL SYSTEM STARTING TO MOVE ON SHORE IN CALIFORNIA. SATELLITE IMAGERY SHOWS MAINLY CI/CS ACROSS THE FORECAST AREA WITH THE LOWER SC HAVING JUST EXITED THE FORECAST AREA. A NARROW BAND OF AC WAS NOTED ACROSS THE DAKOTAS INTO MINNESOTA WITH A FINGER IN FAR NORTHERN IOWA. 18Z SURFACE ANALYSIS HAS THE HIGH OVER WESTERN MINNESOTA WITH THE RIDGE AXIS RUNNING SOUTH-SOUTHWEST INTO WEST TEXAS. MOISTURE ANALYSIS SHOWS DEW POINTS IN THE TEENS ACROSS THE FORECAST AREA WITH 20S AS NEAR BY AS I70 IN MISSOURI. MORE IMPORTANTLY ARE THE 50 AND 60 DEW POINTS THAT ARE ALONG THE RED RIVER VALLEY AND INTO SOUTHERN ARKANSAS. PROBLEM THIS PACKAGE CENTERS AROUND THE INCOMING STORM SYSTEM AND THEN CLOUDS/TEMPERATURES. WINTER STORM WATCH TO BE ISSUED WITH THIS PACKAGE. 12Z ETA/NGM DID NOT INITIALIZE WELL AT ALL. AVN DID BETTER BUT WAS STILL A TAD WEAK WITH THE MAIN FEATURES. NONE OF THE MODELS CAUGHT THE 60 DEW POINTS INTO FAR SOUTHERN ARKANSAS. 15Z/18Z RUC APPEARS TO BE CATCHING THE FEATURES THE BEST IN THE VERY SHORT TERM AND WILL FOLLOW IT AND THEN BLEND IT INTO AN AVN/ETA COMPROMISE FOR POSITION OF THE MAIN FEATURES. WILL USE BETTER ETA DETAIL TO TRY AND REFINE THE OVERALL SNOW THREAT. AVN/ETA PUSH SURFACE RIDGE EASTWARD ACROSS THE GREAT LAKES TONIGHT THROUGH THURSDAY WHILE THE CALIFORNIA SYSTEM MOVES INTO THE INTER-MOUNTAIN REGION. LEE CYCLOGENESIS BEGINS IN ERNEST IN SOUTHEAST COLORADO THURSDAY MORNING AS THE LLJ STRENGTHENS IN THE PLAINS. TREMENDOUS ISENTROPIC LIFT BEGINS ACROSS WESTERN IOWA AS THE LLJ INCREASES TO 45-55 KNOTS WITH 120 MB OF LIFT. THIS SHIFTS EASTWARD WITH TIME AS THE LOW MOVES EAST ALONG THE KANSAS/OKLAHOMA BORDER. QG FORCING COMBINED WITH ISENTROPIC LIFT QUICKLY LOWERS CONDENSATION PRESSURE DEFICITS THURSDAY BUT DRY AIR HOLDS TOUGH ACROSS THE AREA UNTIL THURSDAY AFTERNOON WHEN SATURATION OF THE LOWER LEVELS IS ACHIEVED. FORECAST SOUNDING SHOW THIS VERY WELL WITH RAPID SATURATION THURSDAY AFTERNOON. AVN/ETA TAKES THE SURFACE LOW UP I44 IN MISSOURI WITH AVN/ETA INDICATING THE FIRST LOW OCCLUDING OFF ACROSS MISSOURI WITH ANOTHER DEVELOPING NORTHWEST OF KEVV. EITHER WAY STRONG ISENTROPIC LIFT TO PROVIDE A STRONG SHOT OF WAA SNOW BEFORE DEFORMATION ZONE SETS UP OVER THE AREA. INFLUX OF WARM AIR MAY BE STRONG ENOUGH TO ALLOW A MIXTURE ACROSS THE FAR SOUTH PART OF THE FORECAST AREA. 700-500 MB LAPSE RATES FALL OVER THEMSELVES WITH 7.5-8C/KM THURSDAY NIGHT. THIS MAKES THE THREAT OF CONVECTIVE SNOW A VERY REAL POSSIBILITY. IF THIS WOULD OCCUR SNOW AMOUNTS WOULD END UP BEING MUCH HIGHER. SYSTEM MOVES UP THE OHIO VALLEY ON FRIDAY WITH SNOW GRADUALLY TAPERING OFF. HOWEVER PRESSURE GRADIENT DOESN/T RELAX UNTIL FRIDAY NIGHT SO THE THREAT OF BLOWING SNOW TO REMAIN AFTER SNOW TAPERS OFF ON FRIDAY. ...EXTENDED... WEEKEND TO BE QUIET AS HIGH PRESSURE BUILDS INTO THE AREA. CURRENT TEMPERATURES BEING FORECAST BY MEDIUM RANGE MODELS LOOK TOO WARM GIVEN A DEEP LAYER OF NEW SNOW AND WILL ADJUST DOWNWARD. STRONG RETURN FLOW TO SET UP AS HIGH MOVES EAST OF THE AREA MONDAY AND WEAK IMPULSE PASSING THROUGH MAY BE ENOUGH TO BREAK OUT SOME LIGHT SNOW. COORDINATED WITH DSM...LSE...MKE...CHI...ILX...AND STL. .DVN...WINTER STORM WATCH LATE THURSDAY AFTERNOON THROUGH FRIDAY MORNING. IAZ040>042-051>054-063>068-076>078-087>089-098-099 ILZ001-002-007-009-015>018-024>026-034-035 MOZ009-010 NC il