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 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 AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 930 PM EST WED FEB 16 2000 THE LATEST SURFACE OBSERVATIONS FROM EAST UPPER MICHIGAN SHOW LINGERING LAKE EFFECT SNOW SHOWERS CONTINUING WITH VISIBILITIES OCCASIONALLY DOWN TO AROUND 1 MILE IN NEW BERRY AND SAULT STE MARIE. REPORTS FROM NORTHERN LOWER SHOWS BROKEN CLOUD COVER OVER NORTHWEST LOWER WITH MOSTLY CLEAR/PARTLY CLOUDY SKIES FOR THE REST OF THE FORECAST AREA. IR STLT LOOP AND MQT 88D SHOWING LAKE EFFECT CLOUDS STILL BANDING OVER A GOOD PORTION OF LAKE SUPERIOR...GENERALLY FROM MARQUETTE TO WHITEFISH BAY. THE LATEST RUC SHOWS SURFACE RIDGING BUILDING INTO THE WESTERN GREAT LAKES CURRENTLY WITH UPPER LEVEL RIDGING OVER WISCONSIN. THE RUC PUSHES THE SURFACE AND UPPER LEVEL RIDGE OVER THE UPPER GREAT LAKES BY 12Z THURSDAY...WITH MOISTURE IN THE 1000/850 MB LAYER DRYING TO UNDER 50 PERCENT. HOWEVER THROUGH 09Z...SURFACE THROUGH 850 MB WINDS WILL BE NORTHWEST WITH 850 TEMPERATURES TO -20C OVER EAST UPPER AND -16C OVER NORTHWEST LOWER OVERNIGHT. THROUGH 09Z LOW LEVEL MOISTURE WILL BE AROUND 60 TO 70 PERCENT....MAINLY OVER EAST UPPER. AFTER 09Z UPPER LEVEL AND SURFACE ANTI-CYCLONIC FLOW AND DRYING IN LOW LEVELS WILL HELP TO DIMINISH ANY LINGERING LAKE EFFECT SNOW TO FLURRIES WITHIN THE LAKE SUPERIOR AND LAKE MICHIGAN SNOWBELTS. WILL KEEP PERIODS OF LIGHT SNOW FOR EAST UPPER MICHIGAN OVERNIGHT BECOMING FLURRIES LATE...WITH JUST FLURRIES FOR NORTHWEST LOWER. WITH FRESH SNOW COVER OVER MUCH OF NORTHERN LOWER MICHIGAN AND THE CLEARING SKIES AND CALMING WINDS... WILL LOWER OVERNIGHT LOWS FOR NORTHEAST AND NORTH CENTRAL LOWER MICHIGAN TO NEAR 10 BELOW IN SOME LOCATIONS. WILL KEEP TEMPERATURES A LITTLE WARMER IN THE TYPICAL LAKE MICHIGAN SNOWBELT REGIONS DUE TO THE LINGERING LAKE EFFECT CLOUDS. .APX...NONE. SWR mi AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 815 PM MST WED FEB 16 2000 ...NO MAJOR CHANGES TO THE GOING FORECAST... A NARROW BAND OF LIGHT SNOW HAS DEVELOPED OVER FAR SWRN SD. THIS WAS BEING FORCED BY LOW-LEVEL WARM-AIR ADVECTION AND FRONTOGENESIS. THE 00Z RUC SUGGESTS THIS WILL PERSIST TONIGHT...AND GIVES ABOUT AN INCH OF SNOW ALONG THE SD/NEB BORDER BY 12Z. OTHERWISE...CLOUDY SKIES WILL PREVAIL ELSEWHERE...AND A FEW SNOW SHOWERS MAY PUSH AS FAR NORTH AS I-90 LATE TONIGHT. WILL NOT MAKE ANY CHANGES TO THE WATCH AT THIS TIME. IT WILL BE A CLOSE CALL GIVEN THE DISAGREEMENT BETWEEN THE MODELS. MOST OF THE DIFFERENCE BETWEEN THE ETA AND THE NGM/AVN CAN BE TRACED TO THE LOW-LEVEL TEMPERATURE FIELD. THE ETA PUSHES THE COLDER AIR FARTHER TO THE SOUTH...WHILE THE NGM/AVN HOLD THE WARMER AIR FARTHER TO THE NORTH. SINCE THE NGM/AVN MODELS USE THE SHUELL METHOD TO CALCULATE MEAN SEA-LEVEL PRESSURE (WHICH USES THE MODEL SURFACE TEMPERATURE TO CALCULATE THE REDUCTION)...THEY ARE FARTHER NORTH WITH THE SURFACE LOW. BASED ON THE ADVECTION FIELDS OF THE MODELS...THERE IS NOT MUCH SUPPORT FOR THE MORE NORTHERN POSITION OF THE WARMER AIR...AND THUS THE ETA QPF MAY BE MORE CORRECT. WE WILL SEE... .UNR...WINT STM WATCH THURSDAY FAR SWRN SD. WINT STM WATCH THURSDAY AND THURSDAY NIGHT SCNTRL SD. BUNKERS sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND TX 1046 PM CST WED FEB 16 2000 WATER VAPOR IMAGERY CONTINUES TO SHOW AN APPROACHING STORM SYSTEM OVER SOUTHERN CALIFORNIA AND EXTREME SOUTHERN NEVADA THIS EVENING. ADDITIONAL SHORTWAVE ENERGY COMING ACROSS NORTHERN MEXICO ALONG WITH INCREASING MID AND HIGH LVL MSTR HAVE RESULTED IN THE DEVELOPMENT OF ELEVATED CONVECTION FROM NEAR EL PASO INTO SOUTH CENTRAL NEW MEXICO. OVERNIGHT...AS MID AND HIGH LVL MOISTURE STREAMS INTO SOUTHWEST TX AND SOUTHEAST NM...THESE SHOWERS AND THUNDERSTORMS ARE EXPECTED TO PROGRESS SLOWLY EAST INTO OUR FORECAST AREA. BECAUSE OF THIS... SLIGHT CHANCE POPS HAVE BEEN INCLUDED FOR SOUTHWEST TEXAS AND SOUTHEAST NEW MEXICO FOR THE OVERNIGHT PERIOD. 00Z RUC INTERACTIVE SOUNDINGS PROG ELEVATED CAPES FROM 06Z-12Z OF AROUND 500 J/KG OVER THE PERMIAN BASIN AND ROLLING PLAINS...BUT WITH DECENT AMOUNTS OF NEGATIVE INHIBITION. SATELLITE IMAGERY SEEMS TO SUGGEST THAT THE RUC MAY BE UNDERESTIMATING THE AMOUNT OF MID LVL MOISTURE ASSOCIATED WITH THIS APPROACHING SYSTEM...THUS FEEL THAT ACTUAL NEGATIVE INHIBITION MAY BE LESS THAN PROGGED WITH ELEVATED SHOWER AND THUNDERSTORM DEVELOPMENT POSSIBLE FARTHER WEST THAN PREVIOUSLY FORECAST. A FRONTAL BOUNDARY PRESENTLY DRAPED ACROSS THE LOW TRANS PECOS REGION IS PROGGED TO MOVE NORTH AS A WARM FRONT OVERNIGHT. ABUNDANT LOW LVL MSTR RIDING UP OVER THIS FRONT...ALONG WITH IMPRESSIVE ISENTROPIC LIFT AND CAPES OF 500-1000 J/KG OVER THE NORTHEAST PORTIONS OF THE FORECAST AREA SEEM TO SUPPORT THE POTENTIAL FOR A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THESE AREAS THROUGH 12Z TOMORROW MORNING...AS NOTED IN THE MOST RECENT DAY 1 OUTLOOK FROM SPC. .MAF... TX...NONE. NM...NONE. PV tx TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1015 PM CST WED FEB 16 2000 SENT OUT AN SPS REGARDING POTENTIAL FOR SVR AFTER MIDNIGHT ACROSS EXTRM SERN TX PNHDL. LATEST SFC ANALYSIS SHOWS LOW LVL MOISTURE RIDING UP THE RIO GRANDE WITH HIGH BASED TSTMS OCCURRING OVER FAR W TX WELL AHEAD OF UPPER LOW...WHICH IS NOW MOVING ONSHORE OF SRN CA. STORMS DVLPG OVER FAR W TX A RESULT OF STEEP MID LVL LAPSE RATES SEEN ON 00Z SOUNDINGS FROM THE SW US. WAA PROGGED LATER TNGT COUPLED WITH AN INCREASINGLY UNSTABLE ATMOSPHERE SUPPORTS MENTION OF TSTMS AT LEAST IN SRN TX PNHDL...WITH RISK FOR SVR IN EXTRM SERN ZNS. MAIN THREAT SHOULD BE HAIL DUE TO FABORABLE WET BULB ZERO HEIGHTS AND COLD TEMPS ALOFT. IF STORMS DVLP...THEY SHOULD BE MAINLY ELEVATED IN NATURE. LOTS OF TSTMS OVER SRN NV AND NRN AZ THIS EVENING DUE DIRECTLY TO UPPER LOW AND AIDED BY STRONGER THAN PROGGED 80+ KNOT JET DIGGING THRU EXTRM SRN CA AS SEEN ON 00Z UA ANALYSIS. SATELLITE IMAGERY SUGGESTS SYSTEM IS WELL DEVELOPED...WITH LATEST RUC HINTING AT A STRONGER...SLIGHTLY SLOWER AND SLIGHTLY FURTHER S PROGGED PATH OF THIS LOW COMPARED TO EARLIER 12Z SHORT RANGE MODEL RUNS. THE STRENGTH IS CLOSEST TO NGM/AVN BUT ETAS OVERALL FURTHER S TRACK MAY NOT BE ALL THAT BAD. EVEN SO...STILL APPEARS BEST THREAT FOR ANY PRECIP WILL BE LATE TNGT INTO EARLY AFTN THU...WITH HIGHEST POPS ERN ZNS. PLAN ON MAKING MINOR ADJUSTMENTS TO FIRST PERIOD TO ACCOUNT FOR CURRENT TRENDS. UPDATED ZONES OUT SOON. .AMA... TX...NONE. OK...NONE. ANDRADE tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 905 PM MST WED FEB 16 2000 SNOW BAND ALONG LOW LEVEL CONVERGENCE ZONE FROM JUST SOUTH OF CASPER TO SOUTH PASS WITH INCREASING UPSLOPE FLOW NORTH OF CONVERGENCE BOUNDARY. WEST OF CONT DIVIDE AREAS OF SNOW CONTINUE IN AREA OF BETTER UPPER LEVEL DIVERGENCE AND ISENTROPIC LIFT. WEAKER ISENTROPIC LIFT ALSO OVER LOW LEVEL CONVERGENCE BOUNDARY. RUC AND ETA HANDLING THIS AREA OF PRECIP WELL IN SHORT TERM WITH 00Z ETA CONTINUING TO KEEP THIS AS THE MAIN PRECIP AREA IN CWFA THROUGH THU. OVERALL CAN NOT SEE SWEETWATER COUNTY GETTING ANY MORE SNOW THAN SURROUNDING AREAS AND WIND SHOULD NOT BE A FACTOR FOR SIGNIFICANT BLOWING SNOW SO WILL CHANGE WINTER STORM WATCH TO SNOW ADVISORY AND KEEP OTHER AREAS IN SNOW ADVISORY THROUGH THU. .RIW... ...SNOW ADVISORY REST OF TONIGHT AND THURSDAY ZONES 11>20..22>25. C.BAKER wy AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 930 PM CST WED FEB 16 2000 FORECAST HAS BEEN UPDATED TO REFLECT MORE SNOW IN CENTRAL PORTIONS TONIGHT. WARM ADVECTION/ISENTROPIC LIFT ON LATEST RUC MODEL INDICATES GREATER POTENTIAL FOR LIFT TO SATURATION. PROBLEM ALSO WITH TEMPERATURES...EVENTUALLY CLOUDS AND WARM ADVECTION WILL HALT TEMPERATURE DROP...BUT SOME UPDATES WILL BE NEEDED TO REFLECT TONIGHTS LOWS. .MSP...NONE. SCOTT mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1005 PM EST WED FEB 16 2000 NO SIG CHGS TO MAKE TO TON FCST. FNT SLOWLY WORKING INTO UPSTATE. SAT INDICATES SOME DISSIPATION OF CI. CURRENT TEMPS IN THE MID 50S ACRS CWA. LTST LAMP BRINGS MINS INTO M40S. LTST RUC/MESOETA STILL INSIST FROPA FOR MST CWA 09Z-12Z. LIGHTER WINDS NEAR FNTL ZONE WITH MSTLY CLR SKIES...PLUS ANY CAA TAKING PLACE LATE...SHOULD ALLOW TEMP FALL CLOSE TO FCST MINS OF 40 TO 45...ESPECIALLY N/CENT. MAY TWEAK SW CWA UP TO M40S. .CAE...NONE. sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 941 AM EST THU FEB 17 2000 FOG CONTINUING TO REDUCE VISIBILITIES WEST AND SOUTH CWA. WILL UPDATE FORECAST PACKAGE TO REMOVE MENTION OF MORNING FOG AFTER DISSIPATION IN THOSE AREAS. WEAK FRONT NOTED OVER CENTRAL GEORGIA THIS MORNING AS HIGH PRESSURE REMAINS SOUTH. NORTHEAST TO EAST WINDS TODAY WITH PARTLY CLOUDY SKIES. CLOUDS ADVERTISED ON THE INCREASE TODAY FOR NORTH CWA BY PREVIOUS MODELS...BUT THIS MORNINGS' RUC NOT INITIALIZING WELL AND WILL PUT IN PARTLY CLOUDY THERE INSTEAD. WILL BUMP UP TEMPS AS LITTLE AS A RESULT. WILL CONTINUE TREND IN MARINE. SCEC CONDITIONS EXPECTED OFFSHORE AND AN INCREASE BUT BELOW CRITERIA NEAR SHORE. 11 .JAX... GA...NONE. FL...NONE. fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 930 AM EST THU FEB 17 2000 THIS AFTERNOON...TAMPA SOUNDING SHOWED LESS DRY AIR IN THE LOW LEVELS COMPARED TO THE LAST FEW DAYS...BUT CANAVERAL SOUNDING CONTINUED WITH SHALLOW MOISTURE AND EXTENSIVE DRYING ABOVE. MODELS INDICATE THAT MOISTURE OVER THE EASTERN GULF WILL ADVECT WESTWARD WITH DEEP DRY AIR OVER CENTRAL FLORIDA. THEREFORE WILL GO WITH MOSTLY SUNNY SKIES. OTHERWISE WILL JUST CHANGE TEMPS TO SHOW A BEACHES/INLAND CONTRAST. FIRE WX...ONSHORE FLOW WILL KEEP RH VALUES WELL ABOVE CRITICAL LEVELS IN THE COASTAL COUNTIES. HOWEVER...DRY AIR JUST ABOVE THE SURFACE WILL MIX DOWN OVER INTERIOR SECTIONS...ALLOWING MINIMUM RH VALUES TO REACH 35 PERCENT FOR A BRIEF PERIOD THIS AFTERNOON. MARINE...HIGH PRESSURE RIDGE WEAKENING OVER THE WATERS PROVIDING VARIABLE AND LIGHT WINDS. THEY SHOULD BECOME ONSHORE AT NO MORE THAN 10 KNOTS THIS AFTERNOON AS PER RUC AND MESO ETA MODELS. STALLING FRONT OVER NORTHEAST FLORIDA SHOULD BOTTLE UP THE GRADIENT INCREASE TO THE NORTH OF OUR WATERS. .MLB...NONE. KELLY/LASCODY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 305 AM CST THU FEB 17 2000 SCT SHRA AND FEW LIGHTNING STRIKES ACROSS NRN AR/SRN MO AT THIS TIME...WITH THE ACTIVITY PUSHING EAST. ALTHOUGH THE 00Z MODELS DID NOT DO WELL FORECASTING THIS AREA OF PCPN...IT APPARENTLY IS THE RESULT OF LOW LEVEL THETA-E ADVECTION AND ISENTROPIC UPGLIDE (SEEN CLEARLY ON THE 300K SFC OFF OF THE 06Z RUC). MODELS HAVE BEEN COMING TO MORE OF A CONSENSUS FROM THE PAST FEW RUNS...BUT STILL DIFFERENCES IN THE SPEED AND STRENGTH OF FEATURES. AGREE WITH THE NCEP MODEL DIAGNOSTIC DISCUSSION THAT THE NGM IS MUCH TOO STRONG IN CUTTING OFF THE H5 LOW OVER CO. THIS THEREFORE LEADS THE NGM TO LAG BOTH THE ETA/AVN. ALTHOUGH THE ETA MAY BE TOO FAST WITH THE SFC LOW...WILL TAKE AN ETA/AVN BLENDED SOLUTION WITH A SLIGHT TILT TO THE MORE COMPROMISE AVN. FOR TODAY...ISENTROPIC UPGLIDE WILL CONTINUE TO INCREASE AND SPREAD ACROSS THE MUCH OF THE FA BY 00Z. ALTHOUGH THE ATMOSPHERE IS INITIALLY QUITE DRY AND WILL NEED TO SATURATE...WILL PUT CHANCE POPS IN EVERYWHERE (HIGHEST WEST) TO ACCOUNT FOR WAA PCPN. AS LOW PRESSURE DEVELOPS LATER TODAY AND TRACKS ACROSS THE CENTRAL PLAINS TONIGHT...A WARM FRONT WILL SET UP NORTH OF THE FA ACROSS CENTRAL IL/IN. WITH PLENTY OF LOW LEVEL MOISTURE ADVECTION HELPED ALONG BY A 60+ KT H8 JET AND GOOD UPPER LEVEL DIVERGENCE...CATEGORICAL POPS APPEAR WARRANTED ACROSS ENTIRE FA OVERNIGHT. ELEVATED TSRA ARE ALSO LIKELY GIVEN MID LEVEL LAPSE RATES BETWEEN 7 AND 8 DEGC. ALTHOUGH SOME LOCALLY HEAVY RAIN WILL BE POSSIBLE OVERNIGHT...THE BEST FORCING AND HEAVIEST PCPN MAY BE FOCUSED NORTH OF THE FA CLOSER TO THE WARM FRONT. WITH STRONG WAA OVERNIGHT...TEMPS WILL SLOWLY RISE INTO THE 50S IN MOST LOCALES. ON FRIDAY...THE SFC LOW WILL TRACK BETWEEN KCGI AND KLSX EARLY IN THE DAY AND THEN SLIDE EASTWARD INTO THE LWR OHIO VLY. THIS WILL BRING A COLD FRONT ACROSS THE FA DURING THE 1ST HALF OF THE DAY. WITH DWPTS AOA 60 DEGF ACROSS SRN PARTS OF THE AREA AND SFC LIFTED INDICES BETWEEN 0 AND -2...THUNDERSTORMS WILL BE LIKELY WITH THE FROPA. THIS MAY BE THE BEST CHANCE OF SVR WEATHER ACROSS THE FA. SHRA/TSRA SHOULD DIMINISH RAPIDLY BY AFTN WITH MUCH COOLER AND DRIER AIR MOVING INTO THE AREA. WILL WORD ZONES WITH A MORNING HIGH AND THEN FALLING AFTN TEMPERATURES. WITH THE SLOWER MOVEMENT OF THE NGM...WILL TREND WITH THE GUIDANCE NOS FROM THE MORE PROGRESSIVE AVN. .PAH...NONE. KEYSOR ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 942 AM EST THU FEB 17 2000 SYNOPSIS: LOW PRESSURE WILL LIFT TOWARD NEWFOUNDLAND THIS AFTERNOON WHILE HIGH PRESSURE BUILDS TOWARD NEW ENGLAND FROM THE GREAT LAKES. THE HIGH WILL MOVE EAST OF THE REGION OVERNIGHT. A DEVELOPING WINTER STORM WILL MOVE TO THE OHIO RIVER VALLEY BY FRIDAY EVENING. TECHNICAL DISCUSSION: CONCERN THIS AFTN WILL BE WIND CHILL ADV/TEMPS. WILL DISCUSS WKEND EVENT IN AFTN AFD. WRKZFP SENT. AS MNTND BY MID-SHIFT...TEMPS FELL SHARPLY BEFORE DAYBREAK DUE TO STG VORT MAX/CAA. CAA & NW WINDS AVGG 15-25 MPH W/GUST TO 30 CAUSING WIND CHILLS TO BE AOB CRITERIA. WINDS SHOULD SLOWLY SUBSIDE LATE THIS AFTN AS HIGH PRES RIDGES OVER THE CWFA. LATEST RUC2/MESO-ETA INDICATE WINDS TO STAY UP & CAA TO CONT THRU 21Z. WILL HOLD ONTO WIND CHILL ADV THIS AFTN ESP NRN ZNS. MGT NEED TO ADJUST AFTN TEMPS DOWN A NOTCH. 12Z RAOB/RUC SNDG GIVES MAKE 10-15 FOR NRN ZNS. WILL MAKE FINAL DECISION AFT 10Z OBS. HIGH SUN ANGLE SHOULD HELP WARM BLYR SOME. COASTAL WATERS: GALE CONDS OUT THERE ON THE WTRS ATTM. RUC2 SHOWS WINDS HOLDING @ 30 KTS THRU 21Z W/THAT CAA COMING OVER THE WTRS. PER DISC W/MARINE GUY WILL KEEP GLW FOR EARLY THIS AFTN & BRING WINDS DOWN LATE. .CAR...WIND CHILL ADVISORY THIS MORNING FOR ZONES 001>006-010-011 GLW FOR COASTAL WATERS. JOE me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1040 AM EST THU FEB 17 2000 ONLY BIG CHANGE FOR THIS AFTERNOON WILL BE TO ADD FLURRIES TO THE NORTH. AT 15Z...HIGH OVER SOUTHERN ONTARIO. LOW PRESSURE IN SOUTHERN ROCKIES WITH MAIN WARM FRONT MOVING ACROSS KS...BUT SEEMS TO BE SECONDARY WARM FRONT ACROSS NORTHERN PLAINS FROM SD TO NRN IL. ISENTROPIC LIFT/WAA LIGHT SNOW FALLING NORTH OF THIS BOUNDARY IN MN AND NORTHERN WISCONSIN. AREA OF ISENT LIFT MOVES OVER NORTHERN HALF OF CWA THIS AFTERNOON WHILE LOW LEVELS MOISTEN UP SOME. 12Z RUC SHOWS CONDENSATION PRESSURE DEFICITS BELOW 40MB THIS AFTERNOON ACROSS NORTHERN NORTHERN LOWER AND EASTERN UPPER. TEMPERATURES LOOK GOOD BASED ON CURRENT READINGS VS. MOS 15Z FCST. WINDS WILL REMAIN LIGHT UNTIL GRADIENT PICKS UP LATER THIS AFTERNOON AS HIGH PRESSURE MOVES AWAY. SYNOPTIC SNOW TO MOVE IN THIS EVENING...BUT OHIO VALLEY CONVECTION WILL NEED TO BE WATCHED. MAIN AREA OF FORCING WILL BE WELL SOUTH OF REGION AND EVEN BEST ISENT LIFT WILL BE ACROSS CENTRAL AND SOUTHERN MICHIGAN. IF MOISTURE HAS A HARD TIME MOVING UP FROM THE SOUTH...MIGHT TURN OUT TO BE PRETTY LIGHT SNOW. .APX...NONE. FARINA mi SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 307 AM CST THU FEB 17 2000 WINTER STORM SCENARIO REMAINS A THREAT THIS MORNING WITH FALLING HTS OVR NV IN ADVN OF MAIN SYS...MID LVL MSTR STREAMING OVR THE CNTRL PLNS...35 TO 40 KT ON THE 850 MB WRN KS PROFILERS...AND SFC LOW OVR SERN CO. DRY SLOT ALSO EVIDENT OVR NM AP PER SATELLITE IMAGERY. ETA/AVN/NGM CONT TO PAINT AN UGLY...PRETTY?...PICTURE FOR CWA OVR THE NXT 24 HRS. UPR DVRGNC AND RESULTANT OMEGA FIELDS INCRS THRU THE DAY AND MAX OUT ARND 00Z FOR NRN CWA...LINGERING OVR SRN CNTIES AS DEFORMATION ZONE SHIFTS TO THE S. THESE MDLS AGREE ON ELEVATED UNSTABLE LAYER BY LATE AFTN ALONG WITH HEALTHY DRAW ON SRN PLNS MSTR. ETA/AVN/NMG TEMP/WET BULB PROFILES FAVOR SN FOR NRN CWA...SN TO MIX FOR BRDR CNTIES...AND EARLY FREEZING RAIN CHANGING TO RA OVR KS COUNTIES. CONCERN IS OF DRY AIR IN THE LLVLS FOR THOSE AREAS... EVAPORATIVE COOLING COULD OFFSET PROGGED STRONG WARM ADVCTN. MAGIC CHART...COOK AND GARCIA METHODS WITH THESE MDLS GIVING 8 TO 10 INCHES OF ACCUMULATION. LIMITING FACTORS INCLUDE RUC AND MESOETA VERSIONS OF 850 TEMPS IN SRN NEB BY 18Z...ALONG WITH 700 MB DRY SLOT...IN ADDITION TO SPEED OF SYS. WL BE FOLLOWING RUC/MESOETA SOLUTIONS OF LATE DEVELOPING PCPN AND DROP HEADLINES FOR TDA. WL LEAVE WATCH FOR NEB CWA TNGT...BUT KP KS OUT AS TEMP PROFILE LKS FAVORABLE FOR A LATER CHANGEOVER COMBINED WITH RAPID EXIT OF SYS. 2 TO 4 LKS OK FOR NOW. WL TAPER SN OFF LATE TNGT/FRI MRNG AS MID LVL TROF AXIS CLEARS THE AREA...PERSIST WITH SUB-GUIDANCE 3RD PD TEMPS WITH EXPECTED SN COVER. .GID...WINTER STORM WATCH FOR NEB CWA TONIGHT. 9/6 ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 102 PM CST THU FEB 17 2000 FORECAST CHALLENGE REMAINS SNOW AMOUNTS THROUGH FRIDAY MORNING. LOW DEGREE OF CONFIDENCE IN ANY OF THE MODEL DATA FORECAST DUE TO POOR VERIFICATION OF THIS MORNING/S DRY SLOT SCENARIO. NGM SNOW ACCUMULATOR LOOKS TO BE THE ONLY ONE CLOSE TO REALITY AS OF 18Z THURSDAY...BUT IT ALSO MISSED MORNING SNOW OVER NORTHEAST ZONES. NGM IS TRENDING MORE TOWARDS YESTERDAY/S ETA SOLUTION TAKING SURFACE LOW FARTHER SOUTH TO TEXAS PANHANDLE BY 00Z FRI. ALL MODELS AGREE ON BEST SNOW AT MIDNIGHT TONIGHT FOR CENTRAL PART OF CWA. MODELS HAVE CONSISTENTLY SLOWED DOWN SECOND WAVE FOR EACH RUN OVER THE PAST COUPLE DAYS. THIS SECOND SYSTEM IS BECOMING MOISTURE STARVED PER THE ETA OVER OUR AREA AS WELL. HEAVY SNOW DISCUSSION MENTIONS CENTRAL COLORADO. SAT PIX SHOWS UPPER LEVEL VORT MAX IN SC CO PROGGED TO HEAD EAST SOUTHEAST. RUC HAS NOT BEEN ON TARGET THIS MORNING WITH PRECIP FIELDS EITHER. AM LEANING TOWARDS THE ETA SOLUTION FOR EARLIER PERIODS...BLENDING ALL TOWARDS LATTER HALF OF FORECAST. TONIGHT...ISENTROPIC DOWN GLIDE AGREED UPON BY ALL MODELS AT 295K SURFACE OVERNIGHT...AT LEAST OVER NORTHWEST HALF OF STATE. BEST LIFT (OMEGA...QG FORCING...AND WAA) STAYS IN KANSAS TOWARDS TOPEKA WITH NEUTRAL OR NEGATIVE OMEGA OVER US AT 06Z. LOOKS LIKE WE WILL GET INTO SOME WRAP AROUND WHICH COULD PRODUCE A FEW INCHES. THINK IT MAY BE PRUDENT TO KEEP ADVISORY GOING FOR SOUTHERN AND EASTERN ZONES IN CASE THERE ARE SOME ISOLATED 4 INCH AMOUNTS OVERNIGHT. WILL WORD AS 3 TO 5 INCHES. SURFACE HIGH BUILDS INTO WESTERN ZONES BY 12Z WITH NORTH WIND AND CAA...SO THIS IS EXPECTED TO SHUT OFF THE SNOW THERE. FRIDAY/NIGHT...SNOW ENDING BY MID MORNING OVER ALL OF CWA AS SYSTEM QUICKLY MOVES EAST. NGM LAPSE RATES MUCH STEEPER THAN ETA/S AS FAR AS POSSIBLE COLD AIR STRATO CU DEVELOPMENT DURING THE AFTERNOON. PLENTY COLD WITH 850 TEMPS AVERAGING -8 TO -5 C THROUGH FRIDAY AFTERNOON. WILL TAKE OUT MORNING FLURRIES FOR ALL ZONES MOST LIKELY. REST OF THE DAY SHOULD BE MOSTLY SUNNY UNLESS STRATO CU DEVELOPS PER THE NGM. WILL HAVE TO WATCH FOR ISOLD SNOW SHOWERS. SATURDAY...LOOKS MOSTLY SUNNY. RH FIELDS THROUGHOUT ATMOSPHERE LESS THAN 50% FOR ENTIRE ARE ALL DAY AS WEAK RIDGING TAKES PLACE OVER HIGH PLAINS. RIDGING SEEMS TO BE IN RESPONSE TO CUT OFF LOW OFF CALIFORNIA COAST DIGGING INTO SOUTHERN CA BY 12Z SUNDAY. WEAK DISTURBANCES DO ZIP THROUGH DURING THE DAY OVER AREA...BUT ARE SINCE WE ARE ON THE EAST SIDE OF THE RIDGE AXIS...WE WILL BE LACKING ADEQUATE MOISTURE TO PRODUCE ANYTHING. EXTENDED...SUNDAY THROUGH TUESDAY THE RIDGE BEGINS TO BREAK DOWN SOME AS SYSTEM TRIES TO MOVE ASHORE. APPEARS TO REMAIN NEARLY STATIONARY BEFORE FINALLY COMING ASHORE IN MEXICO TUESDAY MORNING. WITH CUT OFF LOWS...HAVE SEEN USUAL TENDENCY FOR MODELS TO TRY TO BRING THEM ASHORE TOO QUICKLY AND EXPECT THIS IS NO EXCEPTION. LOOKS DRY THROUGH PERIOD WITH A BIT OF A WARM UP. .LBF...SNOW ADVISORY TONIGHT SW TO NE... ZONES 007-010-026>029-037-038-056>059-069>071... SLM ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 315 AM CST THU FEB 17 2000 FORECAST QUANDARIES...SEVERE WEATHER POSSIBILITIES AFTER 00Z FRI. CURRENT ASOS/AWOS OBSERVATIONS...REGIONAL SATELLITE IMAGERY...AND LAPS/SURFACE ANALYSES SHOWING MID AND UPPER LEVEL MOISTURE ADVECTION ACROSS CWA/S CENTRAL AND WESTERN PORTIONS...SPREADING EASTWARD. 07Z LAPS SOUNDINGS SHOWING LOW LEVEL AIRMASS CONTINUING TO REMAIN DRY. AREAL SURFACE WIND FIELDS ARE REMAINING NELY UNDER RIDGING INFLUENCES. 07Z RUC/UPPER AIR CHART ANALYSES ILLUSTRATING MAINLY ZONAL FLOW WITH MINOR PERTIBATIONS...AND BUILDING WESTERN RIDGING INFLUENCES...ESPECIALLY BELOW 700MB. 00Z THU ETA/AVN REGIONAL MODEL INITIALIZATIONS AND FORECASTS THROUGH 00Z SAT GENERALLY SIMILAR...EXCEPT FOR THE NGM SURFACE LOW POSITIONED FARTHER NORTH OVER LAKE ERIE BY PERIOD/S END. EXPECTED EVOLUTION OF UPPER LEVEL FEATURES BETWEEN THE MODELS MOST CONSISTENT WITH MAX AMPLITUDE OF RIDGING OCCURRING AROUND 00Z FRI WITH DIGGING TROF OVER NE CO...MOVING NORTHEAST INTO THE LAKE MICHIGAN AREA BY 00Z SUN...WITH TROF AXIS CENTERED OVER WESTERN TN. AGREE WITH AFTERNOON FORECASTERS DISCUSSION AND CURRENT NCEP MODEL DIAGNOSTIC DISCUSSION THAT THE NGM SFC LOW IS CLEARLY TOO FAR NORTH AND TOO STRONG BY 00Z SAT. WILL LEAN TOWARD AN ETA/AVN SOLUTION FOR UPCOMING FORECAST PERIOD. TODAY...00Z THU ETA/AVN SOLUTIONS SHOWING PCPN POTENTIAL FOR THIS AFTERNOON MAINLY CONFINED OVER WESTERN TN. WILL CONTINUE WITH CHANCE POPS WESTERN ZONES AND WILL LOWER POPS OVER CENTRAL CWA TO WIDELY SCATTERED. MODELS ALSO INDICATING LITTLE CONVECTIVE POTENTIAL OVER REGION..EXCEPT SW. WILL MENTION POSSIBLE THUNDERSTORM POTENTIAL OVER SW LATE AFTERNOON. WILL CONTINUE MOSTLY CLOUDY SKY CONDITION WORDING THROUGH 00Z FRI AS MODEL RH PROGS STILL SUPPORTIVE. TONIGHT...LOOK FOR ENHANCED SHOWER AND THUNDERSTORM ACTIVITY AFTER 00Z FRI WEST...SPREADING ACROSS ENTIRE REGION BY 12Z FRI...LIKELY POPS ALL AREAS BY 12Z. WILL TRANSITION INTO LIKELY POPS AFTER 06Z EASTERN AREAS. SEVERE TS POTENTIAL BEST OVER SW AFTER 06Z FRI... WITH ETA/AVN MODEL SWEAT INDICIES ABOVE 350. WILL CONTINUE WORDING ACCORDINGLY. FRIDAY...WITH MAX SWEAT VALUES PROGGED AROUND 18Z FRI..STILL ABOVE 350...K INDICIES IN THE LOWER 30S...AND AVN 12Z-18Z SRH 0-3 KM LAYER HELICITIES APPROACHING 400(ETA VALUES WAY TOO HIGH STILL)...TS ACTIVITY WILL PREDOMINATE THROUGH 00Z SAT...WITH THE POTENTIAL OF SOME STORMS TO BECOME STRONG. TEMPERATURES...WILL LEAN A FEW DEGREES ABOVE AVN FAN HIGHS FOR REGION TODAY AND FRIDAY...AND MORE IN LINE WITH IN HOUSE ETA BOUNDRY LAYER TEMPERATURE SCHEME VALUES. WITH CLOUDY SKIES AND SOUTHERLY FLOW...LITTLE DIURNAL VARIATIONS IN TEMPERATURES EXPECTED. WILL GO WITH AVN/ETA COMPROMISE ON THURSDAY NIGHT LOWS. PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY... BNA 055/051/064/044 2785 CSV 051/047/062/043 1686 .BNA...NONE. $$ 14 JBW tn TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 1143 AM CST THU FEB 17 2000 15Z SFC ANALYS SHOWED LOW DEVELOPING ACROSS SE CO WITH PAC FNT INTO CNTRL NM. WMFNT FM N MAF TO ALONG RED RIVER BEGINNING TO MOVE N IN RESPONSE TO APPROACHING UPPER LEVEL STORM MOVING THROUGH FOUR CORNERS. EXPECT SFC LOW TO DEEPEN AND MOVE E ACROSS MAINLY OK PNHDL THIS AFTN AND EXIT FA AFT 00Z. STRONG RETURN OF LLVL MOISTURE NOTED ACROSS CENTRAL TX WITH DPS ABV 60 ALREADY INTO N TX ALONG WMFNT. EXPECT AIRMASS ACROSS ERN 1/3 TX PANHANDLE TO CONTINUE TO DESTABILIZE THIS AFTN AS CLEARING SEEN ON VIS IMAGERY OVER SE CORNER FA WORKS N. INITIALLY ELEVATED BKN LINE OF CONVECTION SHOULD FORM ALONG/AHEAD OF WMFNT THIS AFTN ACROSS ERN ZNS AND MOVE RAPIDLY E AS ADVERTISED IN EARLIER PACKAGE. LTG DATA INDICATES STRIKES ALONG NM/CO BORDER ASSCD WITH LIFT AHEAD OF UPPER STORM. THIS SHOULD WORK E AND NE THIS AFTN SO WILL KEEP SOME SLIGHT MENTION OF THUNDER IN FAR NRN ZNS WITH SLIGHT CHC S CENTRAL NEAR INITIATION. OTHER MAJOR CONCERN IS WITH WIND. 12Z RUC INDICATES STRONG H7 GRADIENT MOVING OUT OF ERN NM THIS AFTN. WHITE SANDS PROFILER SUPPORTS THIS WITH 50KT WINDS JUST ABV H8. SFC WINDS ACROSS ERN SLOPES NM ALREADY IN ADVISORY BEHIND PACFNT SO EXPECT THIS TO CONTINUE MIGRATING EWRD THIS AFTN. WILL ISSUE WIND ADVSY FOR WRN 2/3 TX/OK PNHDLS THIS AFTN. ALSO RAISED TEMPS A NOTCH WITH CURRENT OBS/NEW FWC GUIDANCE SUPPORTING A BIT WARMER TEMPS BEHIND FNT THIS AFTN. .AMA... TX...WIND ADVISORY THIS AFTN ZNS 001>003-006>008-011>013-016>018. OK...WIND ADVISORY THIS AFTN ZNS 001-002. COBB tx