AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1010 PM EST FRI JAN 7 2000 SPIRIT OF FCST REMAINS UNCHANGED. UPDATE WAS TO INDICATE RISING TEMPS OVERNIGHT AS SW FLOW STRENGTHENS...ESPECIALLY WRN SECTIONS. THIS IS ALREADY HAPPENING PER LATEST MKG SFC OB. USED LATEST RUC AND MESOETA SFC TEMP PROGS AND 02Z LAMP FCSTS FOR OVERNIGHT TEMP GUIDANCE. IR SATL LOOP SHOWS MID/HI CLDS WITH NRN WAVE CLIPPING NRN SECTIONS OF THE FCST AREA WHILE THE SOUTH REMAINS CLR. .GRR...NONE. MEADE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 840 PM CST FRI JAN 7 2000 ONLY MINOR FORECAST PROBLEMS TONIGHT. LATEST RUC MODEL SHOWED THE 850 MB TROUGH EXITING EASTERN MN. CLOUDS HAVE CLEARED OVER MUCH OF CWA EXCEPT OVER EXTREME EASTERN SECTION OF WISCONSIN ZONES. HOWEVER...ANOTHER BATCH OF MIDDLE/HIGH LEVEL CLOUDS WERE ADVANCING OVER THE EASTERN DAKOTAS...AHEAD OF THE NEXT SHORTWAVE/VORT MAX. THESE CLOUDS SHOULD SPREAD OVER OUR NORTHERN CWA OVERNIGHT. THE LATEST SURFACE ANALYSIS ALSO DEPICTED A WARM FRONT...APRROACHING WESTERN MN...THIS FRONT EXPECTED TO TREK EAST THROUGH OUR CWA OVERNIGHT. TEMPS EXPECTED TO HOLD EITHER STEADY OR SLOWLY RISE INTO THROUGH THE 20S AND 30S. PREVIOUS FORECAST HAS A GOOD HANDLE ON CURRENT WEATHER TREND. ONLY MINOR REVISIONS NEEDED TO THE CURRENT FORECAST. .MSP...NONE JVM mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 825 PM EST FRI JAN 7 2000 LOWER ATMOSPHERIC TEMP ADVECTION HAS BECOME NEARLY NEUTRAL THIS EVENING WITH BOUNDARY LAYER STABILITY INCREASING. THIS HAS ALLOWED SKIES TO BECOME MOSTLY CLEAR SOUTH OF A PIT-UNV-AVP LINE. TO THE NORTH...LATEST GOES IR LOOP AND RUC CROSS SECTION OF EQUIV POT TEMP AND RELATIVE HUMIDITY SHOWS BOUNDARY LAYER MOISTURE AND INSTABILITY SLOWER TO DECREASE. BKN-OVC020-040 CONDITIONS PERSIST FROM MANSFIELD OHIO TO JUST WEST OF WILLIAMSPORT AND AREAS NORTHWARD. SUBSIDENCE DOES NOT APPEAR STRONG ENOUGH ON ITS OWN TO CLEAR THE CURRENT LOW LEVEL CLOUD DECK OUT OF THESE AREAS...RATHER DRIER AIR CURRENTLY RESIDING OVER WESTERN OHIO WILL HAVE TO ARRIVE TO PRODUCE A DRAMATIC CLEARING TREND. VARIABLY OR MOSTLY CLOUDY WORDING THEREFORE LOOKS GOOD FOR THE OVERNIGHT HOURS...AND CURRENT FORECAST HAS THIS HANDLED. FLURRIES HAVE ENDED OVER THE CTP FORECAST AREA AS WELL AS SURFACE RIDGE BECOMES MORE DOMINANT AND WINDS ALOFT TURN MORE TO THE WEST AND SOUTHWEST. REMOVING THE EVENING SNOW SHOWER/FLURRY MENTIONS FROM ZONES WL BE THE ONLY OTHER CHANGE AS ALL OTHER FORECAST DETAILS WORKING OUT NICELY FOR THE OVERNIGHT PERIOD. WORK ZONES TO BE SENT BY 845 PM AS PHLADMCTP. .CTP...NONE. DEVOIR pa SOUTH CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 800 PM CST FRI JAN 7 2000 MADE QUICK UPDATE TO ZONES TO ADD SOME THUNDER OVER THE EAST HALF. AREA OF CONVECTIVE PCPN INCREASED THIS PAST OVER THE SERN CWA INVOF INVERTED SFC TROF WHICH SEPARATES WARMER/DEEPER MOISTURE IN THE EAST FROM COOLER/SHALLOW MOISTURE IN THE WESTERN SECTIONS. MSAS SHOWING STG MOISTURE CONVERGENCE OVER MIDDLE COASTAL PLAINS INTO THE SE CWA WHICH ALSO HAPPENS TO BE IN THE RRQ OF UPR JET CURRENTLY OVER N TX. EXPECTED INFLUENCE OF UPR JET TO LESSEN...WHILE LATEST RUC SHOWS SFC TROF TO VERY SLOWLY SHIFT EAST AFTER 06Z. OTHERWISE CURRENT FORECAST LOOKS GOOD AND ONLY A FEW MINOR CHANGES TO WINDS WHICH ARE MORE NORTHERLY IN THE WEST AND NUDGED A FEW MIN TEMPS DOWN SOME. .EWX...NONE 01/10 tx DEEP SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 735 PM CST FRI JAN 7 2000 BAROCLINIC ZONE ENTRENCHED ACROSS THE RIO GRANDE VALLEY NOW WITH SFC LOW OVER SPI AND TROF EXTENDING NORTHEAST. LOW SURFACE PRESSURE CONTINUES OVR MMTC IN NORTHEASTERN MEXICO. HVY SHRAS IDENTIFIED BY KBRO FM 60 TO 100 NM ENE OF POR. THIS AREA OF THE GULF HAS RECEIVED 1.5-2.5 INCHES OF RAFL DURING THE PAST 10 HRS...WHICH IS VERY GOOD FOR THE SHRIMP BUSINESS. IN THE RIO GRANDE VALLEY...0.20 TO 0.50 INCH SWATHS ARE IDENTIFIED BY KBRO STM TOTALS IN ERN HIDALGO AND CAMERON COUNTIES FROM TODAY'S SHRA ACTIVITY. MFE REPORTED 0.13...HRL RECEIVED 0.03 AND BRO 0.02. CURRENT IR STLT PICS SHOW BREAK IN CLOUD SHIELD OVER VLY WITH SUM CI STREAMING OVR THE WRN VLY. RUC AND ETA ELUDE TO THE END OF SHRAS HERE IN VLY BUT CONTINUED THETA-E RIDGING REMAINS IN PLACE OVR DEEP S TX THRU MIDDAY SATURDAY AND AN H3 JET STREAK TRANSLATES THRU DEEP S TX BEGINNING SATURDAY...PLACING RR QUAD OF 110 KT OVR WRN VLY SUN AT 6 AM. NO BASIS TO CHANGE CURRENT FCST AS THERE EXISTS TOO MANY VARIABLES ATTM TO RULE OUT RA OR CLDS BY MRNG. MDLS ALL REMAIN WET-BIASED SATURDAY WITH ISOLATED CHCS SUNDAY. ANOTHER RUN WILL BETTER DEFINE RA CHCS AND MVMT OF BAROCLINIC ZN. NO CHANGES. SYN...PHILO 58/HMT...CAMPBELL BRO EB 062/075 058/077 059 30/30/20/10 MFE EB 064/076 060/078 059 20/20/10/10 RGC EB 063/076 056/079 057 20/20/10/10 SPI EB 067/074 063/075 064 30/30/20/10 .BRO...SCA FOR GMZ150-155-170-175. tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 300 AM CST SAT JAN 8 2000 MODELS SIMILAR IN MOST FEATURES AGAIN THIS PAST RUN WITH MID LEVEL VORT/SHORT WAVE OVER SOUTH OKLAHOMA INTO NORTH TEXAS SLIGHTLY MORE NORTH THAN THE MODELS PREVIOUSLY PREDICTED. RUC MODEL ALSO SHOWING FEATURE MORE SOUTH THAN AVN/ETA/NGM. WATER VAPOR LOOP SHOWING MORE DRY AIR BEING DRAWN INTO TEXAS AROUND SYSTEM WHICH WOULD LEAD ME TO THINK THAT THE CURRENT ONGOING RAIN MAY CUT OFF FASTER THAN PREVIOUSLY THOUGHT BASED ON EARLIER MODEL RUNS. LOOKING DOWNSTREAM AT HGX DOPPLER RADAR RAIN ASSOCIATED WITH SURFACE LOW ALONG THE LOWER TEXAS COAST CONTINUES WITH BOUNDARY LAYER MOISTURE REMAINING HIGH (>80 %) INTO SUNDAY/3RD PERIOD AS LOW MOVING UP INTO THE EAST TEXAS LAKES COUNTRY OF NORTHEAST TEXAS LATE THIS AFTERNOON AND THE ACROSS CENTRAL LA TONIGHT BEFORE WEAKENING AND WASHING OUT. HOWEVER MID AND UPPER LEVEL MOISTURE DROPS OFF DURING THE DAY TODAY WITH MEAN RELATIVE HUMIDITIES IN THE 1000-500 MB LEVEL DROPPING OFF TO LESS THAN 70 % OVER THE WESTERN HALF BY EARLY AFTERNOON AND THEN AREA WIDE BY LATE AFTERNOON AND EARLY EVENING. WITH VERTICAL MOTION FIELDS ALSO DECREASING DURING SAME TIME PERIOD...AS VORT MAX LIFTS INTO NORTH AR AND SOUTHERN MISSOURI POSSIBLY FARTHER NORTH THAN FORECAST BY MODELS...RAINFALL ENDING SUPPORTED. WILL WORD FORECAST WITH RAIN ENDING EARLY THIS MORNING OVER THE WESTERN SECTIONS AND THEN REMAINING AREAS DURING THE AFTERNOON. MAY LEAVE SOME CHANCE OF RAIN INTO THE EVENING FOR SURFACE FEATURE MOVING UP THE TEXAS COAST AND INTO CENTRAL LOUISIANA. NEXT UPSTREAM VORT/SHORT WAVE SYSTEM WILL BE SUNDAY AFTERNOON/EVENING BUT WITH LIMITED MOISTURE SHOULD BE NO RAIN BUT WILL HAVE CLOUDS MENTIONED. WILL GO ABOVE GUIDANCE NUMBERS FOR FIRST TWO PERIODS AND THEN REMAIN NEAR AVN/NGM FOR 3RD PERIOD AND MORE TOWARD NGM NUMBERS FOR 4TH PERIOD. 06 PRELIMS... SHV 61/50/66/54 5201 MLU 63/49/66/54 5202 TXK 58/50/65/56 5200 TYR 62/53/67/53 4200 LFK 65/50/68/56 5302 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 904 PM EST FRI JAN 7 2000 SYNOPSIS: A COLD FRONT WILL MOVE ACROSS THE REGION OVERNIGHT. A WEAK AREA OF LOW PRESSURE ACROSS THE CANADIAN MARITIMES WILL MOVE EAST OF OVERNIGHT. HIGH PRESSURE WILL RIDGE BACK ACROSS THE REGION ON SATURDAY. ANOTHER AREA OF LOW PRESSURE WILL PASS TO OUR NORTH LATE SATURDAY NIGHT AND SUNDAY BRINGING THE NEXT THREAT FOR LIGHT SNOW TO NORTHERN AREAS. TECHNICAL DISCUSSION: LONGER LOOP OF WATER VAPOR IMAGERY SHOWS UPPER LEVEL TROF MOVING EAST ACROSS THE CWA ATTM. 00Z SFC CHART SHOWED LOW PRESSURE EAST OF NB. THIS SYSTEM WILL CONTINUE TO PULL AWAY FROM NRN ME OVERNIGHT. KCBW 88D SHOWING THAT THE STEADIER PRECIP ASSOCIATED WITH THIS DEPARTING SYSTEM HAS JUST ABOUT MOVED EAST OF THE ME/NB BORDER ATTM. COLD FRONT STILL JUST TO THE WEST ACROSS QUEBEC PROV. LATEST IR SAT LOOP SHOWS BREAKS IN THE CLOUDS ACROSS THE CWA ATTM BUT MORE CLOUDS SHOWING UP TO OUR NW ACROSS QUEBEC PROV ATTM. ALTHOUGH MDLS SHOW GOOD DOWNGLIDE DEVELOPING ACROSS THE AREA OVERNIGHT WILL NOT BE TOO QUICK TO CLEAR THINGS OUT UP NORTH WITH COLD FRONT YET TO COME THROUGH. WILL CONT TO MENTION SCT SNOW SHOWERS NRN ZONES OVERNIGHT IN THE H85 CAA PTRN. FOR CENTRAL/DOWNEAST AREAS DOWNSLOPE FLOW SHOULD HELP TO CONT CLEARING TREND AND WILL BE MORE OPTIMISTIC THESE AREAS. AS FAR AS TEMPS GO OVERNIGHT CURRENT FORECAST MINS LOOK REASONABLE BASED ON UPSTREAM TEMPS ACROSS QUEBEC BUT WILL LOOK AT LATEST OBS BEFORE RELEASE TIME. COASTAL WATERS: MDRM1 SHOWS WINDS SUSTAINED 23 KT LAST HOUR. THINK WINDS WILL INCREASE A BIT LATER TNGT WITH CONT CAA PTRN ACROSS THE WATERS OVERNIGHT. THIS ALSO INDICATED IN RUC 925 MB WIND FCST AS WELL AND WILL MAINTAIN SMALL CRAFT ADVISORY. .CAR...SCA. DUDA me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 1000 AM MST FRI JAN 7 2000 WILL MAKE A FEW ADJUSTMENTS TO FIRST PERIOD OF THE ZONES. LATEST RUC INDICATES LOW LEVEL MOISTURE WILL CONTINUE NORTHWEST TRACK INTO SE NM TODAY AS UPPER LOW TRACKS ALONG SOUTHERN NM BORDER. KMAF RADAR ALREADY SHOWING PRECIP MOVING INTO THE SE CORNER OF NM. WILL UP THE POPS A LITTLE OVER THE SOUTHCENTRAL MOUNTAINS AND SE ZONES. HIGH AND MID LEVEL CLOUDS AHEAD OF SYSTEM OVER NV/UT ALREADY MAKING IT TO THE NORTHWEST FOUR CORNERS AND WILL ADJUST THE CLOUD COVER OVER THE NORTHWEST ZONES FOR SOME CLOUDS THIS AFTERNOON. LEE TROF SETTING UP AND CAO IS ALREADY SUSTAINED AT 21 MPH AND WILL BUMP THE WINDS UP OVER THE NORTHEAST. NO OTHER CHANGES AT THIS TIME. JH .ABQ...NONE. nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 300 PM EST FRI JAN 7 2000 QUITE A CHANGEABLE AFTN ACRS NRN OHIO. DESPITE STG NVA...DOWNWARD MOTION AND CONDITIONAL INSTBY WITH RESPECT TO THE LAKE...LES SNOW DVLPD AND DROPPED UP TO 2 INCHES EAST OF KCLE. NGM/ETA AND RUC SHOW COLDEST AIR AT 850 ACRS FA ATTM WITH WARM ADVN TO BGN QUICKLY THIS EVG AND CONT OVRNGT WHICH SHOULD BRING AN END TO LES. WL CONT SNOW INTO EVG AND MNTN TOTAL ACCUM OF 1 TO LOCALLY 3 INCHES. OTRW CLDS ACRS FA CONVECTIVE AND SHOULD DSIPT THRU THE EVG AND ERY TNGT AS DRY AIR AND HIGH PRES NOSE IN FM THE SOUTH. DRY AIR TO RMN ACRS FA INTO SATURDAY HWVR MSTR RETURNS QUICKLY SAT NGT AND SUNDAY IN ADVANCE OF VORT MOVING OUT OF THE SRN PLAINS. NGM ISOTHERMS REMAIN PACKED IN THE LOWER TN VLY SAT NGT INTO SUNDAY WHLIE THE ETA HAD PACKING FURTHER NORTH ACRS THE SRN OH VLY. EITHER WAY BEST LIFT SHOULD BE TO OUR SOUTH BUT AVN SHOWS VORT SWINGING ACRS FA WHICH WL LKLY DRAG PCPN FURTHER NORTH DURG THE DAY. WL CARRY SMALL CHC THRU SAT NIGHT AND BOOST TO HIGH CHC ON SUNDAY. CLE...NONE. TK oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KEY WEST FL 845 PM EST FRI JAN 7 2000 MOSTLY CLEAR AND UNSEASONABLY WARM ACROSS THE AREA THIS EVENING...WITH TEMPS IN THE LOWER TO MID 70S AND DEWPOINTS 70 DEGREES OR HIGHER. WATER VAPOR SHOWS CONSIDERABLE MID AND UPPER LEVEL SUBSIDENCE OVER THE AREA BUT THERE IS SOME LOW LEVEL MOISTURE TO CONTEND WITH. 00Z KBYX SOUNDING HAS 1.16 INCHES OF PRECIPITABLE WATER CONFINED BELOW 700 MBS. EASTERLY FLOW IS NOT AS DEEP AS LAST NIGHT AS IT EXTENDS ONLY TO 800 MBS. THERE IS AN ISOTHERMAL INVERSION AROUND 700 MBS...WITH A WEAK TEMPERATURE INVERSION AROUND 650 MBS. IT IS ALSO MORE STABLE THIS EVENING THAN 24 HOURS AGO WITH SLIGHTLY WARMER 500 MB TEMPS AND SLIGHTLY COOLER 850 TEMPS. MOST NOTABLE FEATURE THIS EVENING IS PATCH OF FOG OVER THE SOUTHEAST GULF...JUST OFFSHORE THE SOUTHWEST COAST OF THE PENINSULA. THIS PATCH IS MOVING SOUTH AND EARLIER REDUCED THE VISIBILITY AT APF AS IT MOVED ONSHORE TO 1 MILE. IT IS CURRENTLY MOVING INTO GULF WATERS OF THE NORTHERN PART OF THE EAST CAPE SABLE TO CHOKOLOSKEE AREA. ALTHOUGH THIS AREA OF FOG WILL START MOVING ACROSS SOME WARMER WATERS AS IT MOVES SOUTH...AND SHOULD TEND TO BREAK UP SOME...I WILL ADD IT INTO THAT GROUPING IN THE CWF. THANKS FOR COORDINATION IN THIS REGARD MIA. CURRENT THINKING IS THAT IT WOULD DISSIPATE BEFORE GETTING INTO KEYS WATERS...BUT COULD SEE SOME LOWER STRATO-FRACTUS MOVE IN INSTEAD AFTER MIDNIGHT. NORTHEAST TO EAST WIND AT 10 TO 15 KNOTS ALL EVENING AT C-MAN SITES VERIFYING THE BEST ON THE ETA AND RUC. THEY SHOW SIMILAR WIND TO CONTINUE DURING TONIGHT. DID HAVE A SHIP REPORT...THE SEA-LAND HONDURAS FROM DENMARK SOUTH OF THE LOWER KEYS AT 00Z...WITH 16 KNOTS AND 3 TO 4 FOOT SEAS. MLRF1 AT 01Z DOWN TO JUST 8 KNOTS...AND BOUNDARY LAYER WIND ON 00Z SOUNDING IS NORTHEAST TO EAST AT 10 KNOTS. WILL KEEP 10 TO 15 KNOTS FOR ALL NIGHT IN CWF AND JUST KEEP 10 TO 15 KNOTS IN FOR SATURDAY FORECAST. IN PUBLIC FORECAST...LOW LEVEL EASTERLIES CERTAINLY COULD CAUSE A FEW LATE NIGHT SHOWERS...BUT NO MORE THAN ISOLATED AS NOW IN FORECAST. WILL NEED TO WATCH WHAT HAPPENS TO THE FOG AS IT MOVES FURTHER SOUTH FOR ANY POSSIBLE IMPACT ON THE LOWER KEYS. TEMPS AND WIND LOOK FINE. .EYW...NONE MOHLIN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 248 PM CST SAT JAN 8 2000 THE MAIN FORECAST CHALLENGE IS THE HANDLING OF A SERIES OF FAST MOVING SHORT WAVES DROPPING INTO THE MEAN UPPER TROUGH OVER THE CENTRAL U.S. ASIDE FROM THE TYPICAL CONCERN OF TEMPS AND CLOUD COVER...A CONVECTIVE PCPN EVENT IS A DISTINCT POSSIBLITY SUNDAY AFTN. IN THE SHORT TERM...LOW CLOUDS FROM THE SOUTH WILL LIKELY AFFECT RICHARDSON AND PERHAPS PAWNEE COUNTIES IN FAR SOUTHEAST NEB...BASED ON SATELLITE TRENDS AND RUC LOW LEVEL RH PROGS. MID CLOUDS AROUND A WEAK CIRCULATION EJECTING OUT OF CO ARE MORE EXTENSIVE AND SHOULD CROSS THE SOUTHEAST HALF OF THE CWA TONIGHT. BOTH FEATURES WILL HELP TO KEEP TEMPS IN A MILD RANGE COMPATIBLE WITH PREV FCST IN THE SOUTH...EXCEPT THAT FNB WILL REMAIN IN THE 30S WITH HIGHER DWPTS. THE NORTH HAS LOW DEW POINTS AND LIGHT WIND...AND SHOULD RADIATE INTO THE LOWER 20S. THE MODELS ARE FAIRLY SIMILAR THROUGH 24 HRS. HOWEVER...NONE OF THEM WAS DEEP ENOUGH WITH THE 5H HEIGHT FALL CENTER ARRIVING IN THE PAC NW THIS MORNING. A FAIRLY LARGE AREA OF 100-150 METER FALLS WILL PROBABLY REMAIN STRONGER THAN THE MODELS GIVE IT CREDIT FOR AS IT CROSSES THE AREA ON SUNDAY. EVEN SO...AVN AND ESPECIALLY NGM GENERATE AN AREA OF CLDS AT AND BELOW 700 MB DURING THE AFTN...AS WELL AS INCREASING THE LAPSE RATE AS COLDER AIR ADVECTS IN ALOFT WITH THE UPPER TROUGH. NGM EVEN SUGGESTS POTENTIAL INSTABILITY AT OFK DURING THE AFTN. I AM EXPECTING A SCENARIO SIMILAR TO THU WHEN DEEP MIXING FOR THIS TIME OF YEAR AND A PASSING TROUGH ALLOWED SOME RAIN/SNOW SHOWERS TO DEVELOP IN THE AFTN. SFC TEMPS WILL BE SOMEWHAT COOLER THAN THE LAST CASE...BUT TROUGH ALOFT IS STRONGER AND WILL COMPENSATE. UPPER DIFL FROM A JET MAX EMERGING FROM THE BASE OF THE TROUGH AND CROSSING MO ON BOTH NGM AND AVN COULD END UP ENHANCING VERTICAL MOTION...BUT THE NGM ALSO USES IT TO SLOW DOWN DAYTIME HEATING BY GENERATING HIGHER CLOUDS. I WILL ASSUME GOOD MIXING AND DECENT SUNSHINE BEFORE THE TROUGH TAKES OVER...AND LEAVE MAX TEMPS NEAR PREVIOUS FORECAST AND ALSO MOS. MODELS BEGIN TO DIFFER ON THE EXTENT OF LOW LEVEL COOLING SUNDAY NIGHT...WITH ETA RUNNING ABOUT 4C WARMER THAN AVN AT 850 MB BY MON MORNING AND NGM A LITTLE CLOSER TO ETA THAN AVN. ALL MODELS DEPICT LOW LEVEL WINDS BACKING INTO W/SW BY MON MORNING IN ADVANCE OF YET ANOTHER IMPULSE DIGGING INTO NRN PLAINS. THIS SHOULD CUT SHORT THE INITIAL COLD ADVN. WINDS SHOULD ALSO REMAIN UP SOMEWHAT...SO PREFER MID TO UPPER 20S OVER THE NGM MOS LOWER 20S FOR LOWS. AVN KEEPS THE LAXT IMPULSE MAINLY NORTHEAST OF THE AREA ON MONDAY...BUT WE DO GET CLIPPED WITH COLDER TEMPS. BREEZY CONDITIONS IN SW QUAD OF THE DIGGING SYSTEM SHOULD ALLOW DECENT MIXING AND ALLOW RELATIVE WARM MAX TEMPS FOR THE SITUATION. ONLY CONCERN IS THAT CI COVER COULD BE SUBSTANTIAL AS PACIFIC FIREHOSE JET PENETRATES INTO CENTRAL U.S. IN THE EXTENTED...ZONAL FLOW TAKES OVER ON TUESDAY WITH WARM ADVN SETTING UP DURING THE DAY IN ADVANCE OF WEAK LEESIDE TROUGH. LOW STRENGTHENS AND EJECTS EWD ON WED...GENERATING MILD TEMPS AT 850 ON BOTH MRF AND ECMWF...FOLLOWED BY A BACKDOOR INCURSION OF COOLER AIR ON THU. BARE GROUND HAS ALLOWED VERY MILD TEMPS FOR THIS TIME OF YEAR RECENTLY...AND WILL GO WITH RECENT TRENDS RELATING SFC TO 850 TEMPS. WHILE OVERNIGHT LOWS SHOULD NOT NEED MUCH MODIFICATION...I WILL TAKE HIGHS ABOUT 5F WARMER THAN NCEP GUID ON TUE...10F ON WED... AND 3F ON THURSDAY. DRY FORECAST LOOKS GOOD. .OMA...NONE POLLACK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1000 AM EST SAT JAN 8 2000 LOWER CLOUDS CAME INTO COASTAL SECTIONS EARLIER THIS MORNING. ALTHOUGH THEY ARE SOMEWHAT OBSCURED BY HIGHER CLOUDS ON THE VISIBLE SATELLITE IMAGERY IT APPEARS THAT LOWER DECK IS BREAKING UP. SO WILL STAY THE COURSE WITH PARTLY CLOUDY FORECAST. OTHERWISE TROUGH OFF THE COAST DOES NOT LOOK TOO STRONG AT THIS TIME BUT IT SHOULD BE ENOUGH TO KEEP WINDS NORTHEAST TO EAST THROUGH THE DAY. SOUNDINGS SUPPORT CURRENT TEMPERATURE FORECAST. SO OVERALL NOT MANY CHANGES TO PUBLIC FORECAST. CWF...PG CONT TO INCR OVR CSTL WTRS. CONDS AT SCA CRITERIA AT 40 MI BUOY. MESO/RUC INDICATING AS TROF DEEPENS ALONG CST...HIGH PRES TO THE NORTH MOVES OFF THE COAST. PG WL RELAX AND WINDS WL DECR AS PER CURRENT PACKAGE. SUBSEQUENTLY DO NOT SEE ANY MAJOR CHGS FOR UPDATE. .CHS... SC...NONE. GA...NONE. /JCI sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 245 PM CST SAT JAN 8 2000 FORECAST QUANDARIES: PCPN PROBABILITIES/TEMPERATURES. CURRENT AWOS/ASOS OBSERVATIONS...SATELLITE IMAGERY...AND MOSIAC RADAR DATA ILLUSTRATING REGIONAL CLOUDINESS AND LIGHT RAINFALL ACROSS CWA/S WESTERN PORTIONS. LATEST SURFACE ANALYSIS/LAPS DATA DEPICTING LIGHT SOUTHERLY WIND FIELD WITH DEWPOINTS SPANNING MID 20S TO MID 30S. UPPER LEVEL CHART ANALYSIS/RUC SHOWING DEVELOPING SW FLOW WITH EMBEDDED VORT MAXES. 100KT+ 250MB SWLY JET OVER WESTERN TN. 12Z SAT MODEL RUN/S SURFACE AND UPPER LEVEL REGIONAL INITIALIZATION AND PROGGED EVOLUTION SIMILAR THROUGH 00Z TUE. SURFACE FEATURES EXPECTED TO PROGRESS FROM WEAKENING RIDGING INFLUENCES AREA CENTERED AS OF 18Z SAT OVER NE NC. MOVING EASTWARD. CURRENT REGIONAL AIRMASS PROGGED TO BE REPLACED BY A "MOISTURE RICH ONE" AHEAD OF AN APPROACHING COLD FRONT MOVING EASTWARD OUT OF THE CENTRAL U.S.. COLD FRONT EXPECTED TO BEGIN MOVING THROUGH WESTERN PORTIONS OF AREA AFTER 06Z MON. "RAPID" EASTWARD MOVEMENT ANTICIPATED ACROSS CWA AS FRONT MOVES INTO EASTERN TN BY 12Z MON. A SLIGHT PERTIBATIONS IN UPPER LEVEL FLOW ASSUMED TO MOVE ACROSS REGION BY 18Z SUN WITH MAIN UPPER LEVEL TROUGH PASSING OVER REGION DURING AN 12Z MON TO 00Z TUE TIME SPAN. IN AGREEMENT WITH LATEST MODEL DIAGNOSTIC DISCUSSION LEANING TOWARD AN AVN SOLUTION AFTER 00Z MON WITH "FAST" UPPER LEVEL FLOW MAKING SUCH A SOLUTION MOST LIKELY. AS FOR SKY CONDITIONS...MODELS PRESENTLY UNDERESTIMATING ATMOSPHERIC MOISTURE CONTENT...ESPECIALLY IN THE LOWER LEVELS. BELIEVE ENOUGH LOW LEVEL MOISTURE WILL BE PRESENT THROUGHOUT PERIOD TO SUPPORT MOSTLY CLOUDY SKIES. MAXIMUM AIRMASS MOISTURE POTENTIAL WILL BE ACHIEVED BEFORE 12Z SUN....CLOUDY SKIES AREA WIDE TONIGHT. AS FOR PCPN PROBABILITIES...AVN SHOWING LIKELY POPS THROUGH 12Z SUN WITH TOTAL RAINFALL AMOUNTS EXPECTED TO AVERAGE LESS THAN 0.25 INCH. NGM MOS SOLUTION POPS MAY BE "TOO LOW" THROUGH 00Z MON. WITH CURRENT MEASURABLE PRECIPITATION TRENDS AND SOME CONTINUED DRYNESS IN THE LOWER LEVELS..BELIEVE SOME RAINFALL WILL EVAPORATE BEFORE REACHING THE GROUND. WILL GO WITH CHANCE POPS REGIONWIDE ON SUNDAY WITH HIGHEST POPS WEST. WILL CONTINUE WITH CHANCE POP FORECAST THROUGH REMAINDER OF PERIOD. "QUICK" COLD FRONT PASSAGE BETWEEN 06Z-12Z MON WILL AID AS A FOCUSING MECHANISM FOR RAIN/SHOWER DEVELOPMENT...WITH LITTLE INDICATION OF INSTABILITY ASSOCIATED WITH TS DEVELOPMENT. WITH UPPER LEVEL TROF PASSAGE EXPECTED AFTER 12Z MON...NGM MOS VALUES COULD BE IN THIS CASE "TOO HIGH". WILL LEAN TOWARD HIGHER CHANCE POPS SUNDAY NIGHT AND CHANCE POPS CONTINUING THROUGH MONDAY AS LOW LEVEL MOISTURE PREVALENT ENOUGH FOR SCT PCPN POTENTIAL. AS FOR TEMPERATURES...WITH CLOUDY SKIES EXPECTED TONIGHT...AREA SHOULD SEE ONLY SLIGHT DIURNAL VARIATION IN HIGHS FROM THIS AFTERNOON TO SUNDAY MORNING LOWS. WITH HIGHS THIS AFTERNOON ONLY IN THE MID 40S TO AROUND 50 SOUTH...CLOSE TO AVN FAN EXPECTED LOW VALUES...WILL LEAN TOWARD NGM MOS LOWS. WITH PREFERRED AVN SOLUTION...WILL GO CLOSER TO FAN AVN HIGHS/ETA IN HOUSE BOUNDRY TEMPERATURE SCHEME VALUES FOR SUNDAY HIGHS. FAN AVN/NGM MOS LOWS "ON LINE" FOR SUNDAY NIGHT. WILL LEAN TOWARD WARMER AVN FAN VALUES FOR HIGHS ON MONDAY. PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY... BNA 038/057/047/060 4333 CSV 035/053/045/056 3433 .BNA...NONE. $$ 14 JBW tn SOUTH CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 300 AM CST SAT JAN 8 2000 EASTERN CWA RECEIVED GOOD RAINS FROM THIS SYSTEM WHILE WESTERN AREAS HAVE COME UP SHORT TO VERY SHORT. SOME DECENT SHOWERS ONGOING IN EXTREME EAST WHILE DRIER AIR HAS STARTING TO INVADE WEST. RUC AND ETA SHUT OFF RAIN FOR CWA SHORTLY AFTER SUNUP. AVN KEEPS IT GOING A LITTLE LONGER. WILL TEND TOWARD QUICKER END. EXPECT SOME FOG WEST THIS MORNING WITH RESIDUAL MOISTURE AND CLEARING SKIES. CLOUDS TO PERSIST EAST TODAY THEN PARTIAL CLEARING AND FOG CENTRAL AND EAST SECTIONS TONIGHT. TEMPS UNDER GUIDANCE EAST TODAY WITH CLOUDS PERSISTING. WARMER DAYS AHEAD SUNDAY AND MONDAY. NEW MRF SUGGESTS NO FURTHER RAIN CHANCES THROUGH NEXT WEEK. PRELIMS AUS 055/049 068/043 3000 DRT 063/042 072/041 0000 SAT 058/050 068/045 2000 .EWX...NONE 03/18 tx