NORTHERN ARIZONA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 900 PM MST FRI DEC 31 1999 .SYNOPSIS...A WEAK COLD FRONT WILL MOVE INTO ARIZONA TONIGHT. THIS WILL PRODUCE LIGHT SNOW SHOWERS ACROSS THE MOGOLLOM RIM COUNTRY AND THE WHITE MOUNTAINS. BY SATURDAY AFTERNOON...LIGHT SNOW WILL BE LIMITED TO THE EASTERN MOUNTAINS AS THE FRONT MOVES INTO NEW MEXICO. MUCH COOLER AIR WILL COVER THE REGION SUNDAY. A NORTHWEST FLOW WILL BRING BREEZY CONDITIONS...MOSTLY CLOUDY SKIES...AND SLIGHTLY WARMER TEMPERATURES MONDAY THROUGH WEDNESDAY. DISCUSSION...LATEST RUC MODEL HAS GOOD HANDLE ON EAST PACIFIC TROF AND ASSOCIATED VORT MAX THAT IS APPROACHING SOUTHERN CALIF/NORTHERN BAJA. SOUTHERLY FLOW AHEAD OF TROF IS PUSHING MOISTURE INTO SOUTHEAST AZ ATTM. RADAR AND SFC OBS INDICATE LIGHT PRECIP OVER THE WHITES AND ALONG THE NM BORDER. UPPER LOW WEAKENS AS IT MOVES ACROSS AZ AND MAIN ENERGY WITH THIS SYSTEM TRAVELS ACROSS SOUTHERN AZ TONIGHT AND SATURDAY. BEST DYNAMICS...OMEGA/PVA...AND RH TARGET THE WHITES AND EASTERN SECTIONS OF THE CWA FOR OVERNIGHT AND SATURDAY. CURRENT FCST WITH HIGHEST POPS FOR THE SOUTHEAST ON TRACK. FOR THE WEST SHOWERS POSSIBLE WITH LITTLE ACCUMULATION EXPECTED. 00Z ETA INDICATING ANOTHER WEAK S/WV CAUGHT IN THE NW FLOW FOR SUNDAY. WHILE ETA DOES NOT INDICATE MUCH IN THE WAY OF RH OR PRECIP POTENTIAL THIS FEATURE DOES BEAR WATCHING. WILL LET MID SHIFT DECIDE WHETHER OR NOT TO INCLUDE POPS FOR NORTHERN CWA ON SUNDAY. NO UPDATE. DF .FGZ...NONE. az SOUTHEAST ARIZONA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 815 AM MST FRI DEC 31 1999 SYNOPSIS...A WEAK PACIFIC STORM WILL BRING A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW SHOWERS TO SOUTHEAST ARIZONA THROUGH EARLY NEW YEARS DAY. PRECIPITATION AMOUNTS ARE EXPECTED TO BE LIGHT AND IT WILL BE MUCH COOLER THIS WEEKEND. A RETURN TO DRY AND WARMER WEATHER IS FORECAST FOR EARLY NEXT WEEK. DISCUSSION...MID AND SOME LOWER LEVEL MOISTURE WERE ON THE INCREASE AHEAD OF THE MAIN SYSTEM. TUS MORNING SOUNDING SHOWED THAT THE MOISTURE WAS BETWEEN 850MB AND 650 MB. LATEST RUC MODEL HAD A GOOD HANDLE ON THIS MOISTURE WITH SOME WEAK UPWARD VERTICAL MOTION PROGGED OVER THE ARE TODAY. THUS...HAVE UPDATED THE FORECAST TO MENTION SOME LGT SHWRS OR SPRINKLES THIS MORNING FOR MAINLY THE HIGHER ELEVATIONS SINCE VALLEY DEW POINTS WERE STILL FAIRLY LOW. AT ANY RATE...WILL LIKELY SEE SOME BREAKS IN THE CLOUDS BY LATE AFTERNOON IN THE WESTERN AND CENTRAL ZONES. ETA MODEL SHOWED THAT MOST OF THE MOISTURE WILL SHIFT EAST OF THE AREA BY 10Z TOMORROW. SO WILL ADJUST THE TIMING OF PRECIP UP SEVERAL HOURS. JD .TWC...NONE. az EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 330 AM PST FRI DEC 31 1999 THE MARINE LAYER IS DEEPENING AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES TOWARD SOUTHERN CALIFORNIA TODAY. LITTLE IF ANY CLEARING WILL OCCUR WEST OF THE MOUNTAINS TODAY AND TEMPERATURES WILL BE COOLER ACROSS SOUTHWEST CALIFORNIA. DRIZZLE IS EXPECTED TONIGHT AND INTO NEW YEARS DAY...WITH GRADUAL CLEARING DURING THE AFTERNOON. FIRST DAY BACK SO NO REAL FEEL FOR HOW SHORT RANGE MODELS HAVE BEEN PERFORMING SINCE MONDAY NIGHT. NCEP AND OTHERS CONSENSUS IS THE AVN MODEL HAS BEEN MOST CONSISTENT. MAIN CHANGE TO CURRENT FORECASTS WAS TO PROLONG CLOUDINESS OVER ZONES WEST OF MOUNTAINS TODAY AND LOWER TEMPERATURES MOST ZONES. MARINE LAYER CONTINUING TO DEEPEN AS EVIDENCED BY LIFTING OF CEILINGS AND INCREASING VISIBILITIES MOST LOCATIONS. SATELLITE AND RADAR IMAGERY SHOWING INCREASING LOW/MID CLOUDS OVER SOUTHERN CALIFORNIA BIGHT AND AVN/RUC MODELS SHOWING -24 CELSIUS CORE AT 500 MB IN THE UPPER LOW. SO ANY CLEARING WILL BE SHORT LIVED AS PLENTY OF CLOUDS/MOISTURE TO ADVECT IN AND INCREASING LIFTING ON THE WAY. HELD OFF ON MENTION OF PRECIPITATION TONIGHT EXCEPT FOR SANTA ANA MOUNTAINS...DAY SHIFT MAY WANT TO EVALUATE FURTHER AND/OR CHANGE DRIZZLE TO LIGHT RAIN. LEFT EXTENDED ALONE...ALTHOUGH BREEZY/WINDY CONDITIONS ADVERTISED FOR DAY 5 LOOK LIKE THEY MAY BE CONFINED TO HIGHER TERRAIN UNTIL THURSDAY WHEN OFFSHORE GRADIENT HAS STRENGTHENED. SAN 022 .SAN...NONE. BALFOUR ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 155 PM EST FRI DEC 31 1999 STG ZONAL FLOW AND ASSOCD WK SFC RIDGE IN PLACE THIS PM KEEPING WX ACRS FA TRANQUIL FOR THE TIME BEING. FCST CONCERNS THIS FCST PD WL BE PRECIP SUN THRU EXTENDED AND TEMPS. WK TROF NOTED ON 17Z SFC MAP HELPING TO GENERATE LOTS OF LOW LVL CLDS ACRS NE QUARTER OF FA THIS PM. RUC MODEL HANDLED THIS PRETTY WL FOR THE MOST PART BUT NOT AGGRESSIVE ENOUGH WITH CLRG BEHIND THIS FTR. AT ANY RATE XPC ALL AREAS TO CLR OUT INTO THIS EVENING WITH GUIDANCE FCST MINS ON TRACK OVERNIGHT. AS WE START OUT THE NEW YEAR... WAA BEGINS IN EARNEST AS OLD CUTOFF LOW ALG CA COAST GETS KICKED E FINALLY IN RESPONSE TO AMPLIFYING N STREAM SW DIGGING INTO PAC NW. PREFER SOMEWHAT MORE PROGRESSIVE ETA/NGM SOLUTIONS FROM 12Z ALTHOUGH NGM MUCH LIKE YDA 12Z AVN OVERDEVELOP SFC WAVE VCNTY E IA BY 48H. BEST LOW LVL FORCING TO PASS N ACRS MI/WI BUT FVRBL JET POSITIONING AND INCREASING PVA AHD OF SW TROF PROMISE WIDESPREAD MAINLY LIGHT RAIN EVENT ACRS FA FOR SUN/SUN NIGHT AS MODEL QPF/S NOT VERY IMPRESSIVE ACRS FA. FROPA TO OCCUR LATE SUN INTO MON AM AS N STREAM SW FOLLOWS ON HEELS OF CA WAVE. ENOUGH CAA AND WRAP AROUND MOIST TO WARRANT CHC POPS FOR SHSN MON WITH BEST BET NR LK MI WITH NARROW WINDOW OF FVRBL TRAJ/DELTA T OFF THE LK. AFT THAT... MUCH MORE IMPRESSIVE ARCTIC STREAM SW DROPS DOWN OUT OF GULF OF AK EARLY NEXT WEEK AND HOLDS MUCH MORE PROMISE FOR SIG SNOW TUESDAY. GUIDANCE TEMPS LOOK GOOD EARLY BUT APPEAR TOO WARM SUN GIVEN XPCD PRECIP AND CLDS. .IWX...NONE. TEH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 0200 PM CST FRI DEC 31 1999 THE FIRST FORECAST CHALLENGE FOR TODAY...THE LAST REGULAR JACKSON NWS FORECAST DISCUSSION OF THE 1900S...IS WHEN TO BREAK UP THE CLOUDINESS ACROSS THE FORECAST AREA. SATELLITE IMAGERY SHOWS SOME BREAKS IN THE CLOUDS IN SOUTHEASTERN SECTIONS OF THE FA AND CLEAR SKIES WEST AND NORTH OF THE FA. A FEW SURPRISE SHOWERS...PROBABLY CAUSED BY PVA ASSOCIATED WITH A WEAK 500 MB TROUGH MOVING ACROSS THE FA...HAVE DEVELOPED IN CENTRAL MISSISSIPPI. IN GENERAL...LOW LEVEL CLOUDINESS IS HANGING TOUGH ACROSS THE FA TODAY. LATEST RUC FORECAST SOUNDING FOR JAN SHOWS LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH AT LEAST 03Z...LEADING TO CONTINUED LOW CLOUDS TONIGHT WITH POSSIBLE FOG BY SUNRISE. THE ETA FORECAST SOUNDINGS ALSO SHOW LINGERING LOW LEVEL MOISTURE TONIGHT WITH GRADUAL CLEARING FROM WEST TO EAST DURING THE NIGHT. WITH RECENT DEVELOPMENT OF ISOLATED SHOWERS...WILL HAVE TO PUT IN CHANCE OF EARLY EVENING SHOWERS IN FORECAST FOR EASTERN SECTIONS OF FA FOR TONIGHT. ON NEW YEAR'S DAY...THE LARGE...MOSTLY CLOUD FREE AREA NOW LOCATED TO OUR NORTH AND WEST WILL BE IN PLACE OVER THE FORECAST AREA BRINGING BEAUTIFUL WEATHER TO THE REGION. LIGHT SOUTHERLY LOW LEVEL FLOW WITH DRY AIR ABOVE WILL ENSURE A SUNNY DAY ACROSS THE FA AFTER THE LAST FEW LINGERING LOW CLOUDS DISSIPATE IN THE MORNING. ON SATURDAY NIGHT...MOISTURE RETURNS AGAIN TO THE FA AS THE SOUTHERLY FLOW FROM THE GULF INCREASES. SUNDAY WILL BE A CLOUDY AND WINDY DAY WITH MILD TEMPERATURES. LIGHT RAIN IS POSSIBLE...BUT AVN/NGM/ETA MODEL QPF DOES NOT SHOW ANY MEASURABLE RAIN THROUGH SUNDAY DESPITE UP TO 40 PERCENT POPS ON NGM MOS DATA. BELIEVE THAT ANY RAIN FALLING ON SUNDAY WILL BE LIGHT. BY SUNDAY NIGHT AS SURFACE FRONT APPROACHES THE FA...MEASURABLE RAIN IS MORE LIKELY...BUT WILL PROBABLY STILL BE LIGHT WITH MODELS SHOWING BEST MOISTURE AND LIFT WELL NORTH OF THE FA. FOR TEMPS...BELIEVE AVN GUIDANCE IS MORE ON TARGET WITH WARMER LOWS TONIGHT AND TOMORROW NIGHT AND WARMER HIGHS FOR NEW YEAR'S DAY. IN FACT...WITH AFTERNOON DEWPOINTS ACROSS THE FA TODAY GENERALLY IN THE UPPER 50S...WILL FORECAST LOWS ABOVE AVN GUIDANCE AS WELL. FOR SUNDAY...BELIEVE AVN GUIDANCE OF RECORD HIGH TEMPS IS OVERDONE SINCE MODELS INDICATE SIGNIFICANT MID TO HIGH CLOUDINESS ON SUNDAY. THEREFORE...WILL STAY CLOSER TO NGM'S LOWER HIGH TEMPS FOR SUNDAY. FOR POPS...BELIEVE CHANCE OF MEASURABLE RAIN IS VERY LOW TILL SUNDAY NIGHT. WILL MENTION SLIGHT CHANCE OF MAINLY LIGHT RAIN FOR SUNDAY AND CHANCE FOR SUNDAY NIGHT. DON'T SEE MUCH DIFFERENCE IN RAIN FROM ONE SIDE OF THE FA TO THE OTHER. QPF DISCUSSION...NONE EXPECTED. IN THE EXTENDED...IF MRF'S SPEED OF UPPER TROUGH IS CORRECT...SOME LINGERING LIGHT RAIN COULD OCCUR WEST OF THE SURFACE FRONT INTO MONDAY MORNING. ANOTHER UPPER TROUGH PUSHES A SURFACE FRONT ACROSS THE FA ON TUESDAY...BUT LACK OF LOW LEVEL MOISTURE WILL ENSURE THE SYSTEM WILL BE DRY ON TUESDAY ACROSS THE FA. SURFACE HIGH PRESSURE MOVES ACROSS THE AREA ON WEDNESDAY BRINGING AT LEAST ONE GENERALLY SUNNY DAY TO THE REGION BETWEEN THE RAPIDLY MOVING WEATHER SYSTEMS. BEYOND THE FIVE DAY FORECAST PERIOD...THE MRF HAS BEEN CONSISTENT THE PAST TWO DAYS IN BRINGING ARCTIC AIR WELL INTO THE DEEP SOUTH BY FRIDAY NIGHT. THE MODEL DATA SHOWS PLENTIFUL MOISTURE WITH THIS SYSTEM...EVEN IN THE COLD LOW LEVEL AIR WEST OF THE SURFACE FRONT AS THE 500 MB TROUGH MOVES ACROSS THE FA. THIS SYSTEM COULD CAUSE SOME TYPE OF FROZEN PRECIPITATION ACROSS PORTIONS OF THE DEEP SOUTH BY THE END OF THE WEEK. OF COURSE...TIMING OF THE COLD AIR WILL BE CRITICAL AS TO WHETHER THERE WILL BE ENOUGH LINGERING MOISTURE FOR PRECIPITATION BY THE TIME THE SURFACE TEMPERATURES DROP TO FREEZING FRIDAY NIGHT. ALSO...IF LATER MODEL RUNS MODIFY THE LOW LEVEL TEMPERATURES AS THE SYSTEM REACHES MISSISSIPPI...THE FA WILL JUST EXPERIENCE A COLD RAIN. THIS POSSIBLE STORM SYSTEM BEARS WATCHING AT THE END OF THE WEEK. HOWEVER...AFTER ALL THIS HAS BEEN SAID ABOUT THE MRF PROGS...THE CANADIAN ENSEMBLE MODEL DOES NOT BRING NEARLY AS DEEP OF A 500 MB TROUGH INTO THE CENTRAL UNITED STATES. IF THE 500 MB TROUGH IS NOT AS DEEP...THE COLD AIR WILL NOT PENETRATE AS FAR SOUTH. SO...WE WILL LOOK AT THIS SITUATION MORE CAREFULLY AS FUTURE FORECAST MODELS ARE PRODUCED IN THE YEAR 2000. PRELIM NUMBERS... JAN 052/076 056/074 -00- MEI 053/076 056/075 200- .JAN... MS...NONE. AR...NONE. LA...NONE. 15 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 949 AM EST FRI DEC 31 1999 SUBS INVERSION YET AGAIN TRAPPED CLDS ACRS A GOOD PORTION OF CWFA INTO THIS MORNING AS THE CNY CLOUD FEST CONTINUES. FAST ZONAL FLOW WL TAKE WK LOPRES NOW OVER ERN PA AWAY FROM AREA AND BRING ANOTHER CLIPPER TO NRN NY BY LATE PM. VIS SAT PIX SHOW SUBS BEHIND PA S/WV DVLPG SUCKER HOLES IN SHLW LOW CLD DECK OVR WRN PA WITH DECENT CLR AREA IN OH. MORE WARMFRONTAL CLDS ASSOC WITH UPSTRM CLIPPER MOVG INTO MI/ONTARIO. 00Z/06Z ETA AND CURRENT RUC DEPICT CLD TRENDS WELL WITH GOOD DRYING IN H85 RH FIELDS AROUND 18Z...THEN MOISTENING AGAIN BY 00Z. SHUD SEE SUNNY BREAKS AMONG THE CLDS TAFTN...BUT WITH NEXT CLD SHIELD APCHG AND SOMEWHAT UNSTBL BNDRY LYR...BLV ADDL STRATOCU WL FORM. WL OPT FOR THE MIX OF CLDS AND SOME SUN WORDING OVER CRNT P/S. NORTH COUNTRY STARTED OFF RATHER CHILLY UNDER MAINLY CLR SKIES...SO WL HV TROUBLE REBOUNDING AND WL TWEEK LOWER...ESPLY NRN ONEIDA WHERE 10 IN SNOWCOVER RMNS. HV TWEEKED TONITE PD AS WELL FOR MORE CLDS THIS EVENING ASSOC WITH WMFNT...THEN CLRG AS WE GET INTO WARM SECTOR BY DAYBREAK. .BGM...NONE. BREWSTER ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 920 PM EST FRI DEC 31 1999 THE 18Z ETA AND 00Z RUC SHOW MOISTURE GRADUALLY INCREASING OVERNITE BELOW 700 MB. INCREASING CLOUDS LOOKS LIKE A GOOD TREND JUDGING BY SATELLITE IMAGERY...WHICH SHOWS AN AREA OF CLOUDINESS EXPANDING OVER N GA AND MOVING IN OUR DIRECTION. IF THERE IS A PROBLEM WITH THE FORECAST...IT IS WITH THE LOW TEMPS TONITE. AM LEANING TOWARD DROPPING SOME OF THE LOW TEMPS A FEW DEGREES E OF THE MOUNTAINS... WHICH WILL HAVE THE BENEFIT OF COMING MORE INTO LINE WITH OUR NEIGHBORS TO THE EAST. ROCK HILL IS ALREADY AT 43 DEGREES F. WILL PROBABLY SPLIT OFF CLT AREA ZONES TO GO WITH MORE OF A LOWER RANGE...BUT WILL KEEP GSP AREA/UPSTATE SC/NE GA GROUP WITH MID 40S. .GSP...NONE. MOORE sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 210 PM EST FRI DEC 31 1999 MAINLY ZONAL FLOW TO CONTINUE AT LEAST THRU SAT WITH XCPTN OF RIPPLE APPROACHING AREA FM THE W LATER TONITE. MODELS HAVING SOME MINOR DIFFERENCES BUT IN GENL AGREE THAT AVBL MSTR IS LIMITED AND WL GET FEW SPRINKLES AT BEST ON SAT. LATEST VSBL SAT LOOP AND RUC HINTING THAT MID-HIGH LVL CLDS SHD THIN OUT LATER TDA. HOWEVER ETA/AVN SUGGESTING THAT LOW-LVL MSTR WL MOV INTO AREA SAT AM AS S/W GETS CLOSER. AFTER S/W MOVS E OF AREA LATE SAT...RIDGING SHD OCCUR UNTIL NXT UPR TROF APPROACHES BY LATE MON. WL PRBLY MENTION ISOLD SHWR BY LATE SUN IN ADVANCE OF NXT FRNT. IN THE EXTENDED...SERIES OF S/WS WL CROSS THE AREA MON THRU WED AS BROAD UPR TROF SWINGS THRU. BEST CHC FOR PRECIP APPEARS TO BE MON. CONSENSUS OF GUIDANCE TEMPS AND POPS LUKS GD ATTM. PRELIM CCFS CAE EE 44/68/47/69/52 220-0 AGS EE 43/68/45/69/51 220-0 .CAE...NONE. BC sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1015 AM EST FRI DEC 31 1999 LATEST RUC AND 12Z ETA BOTH SHOW HIGH LEVEL MOISTURE DECREASING FOR THE AFTERNOON. HOWEVER, SATELLITE STILL SHOWING PLENTY OF CLOUDS TO OUR WEST MOVING EAST. WILL GO WITH PARTLY SUNNY FOR THE AFTERNOON. TEMPS IN THE MID-UPPER 60S RANGE IN ORDER. .CAE...NONE. LM sc AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 1015 AM CST FRI DEC 31 1999 ANLYS CONTS TO SHOW SFC LOW MOVING EAST ALONG ND/CANADA BORDER WITH WARM FRONT DRAPED NORTH/SOUTH ACROSS THE CENTRAL DAKOTAS. WINDS BEHIND THE FRONT ARE SWINGING TO THE WEST WHILE SOUTHEAST TO SOUTH WINDS ARE FOUND AHEAD OF THE FRONT. LATEST RUC SHOWS 1000-700MB LAYER DRYING OUT DURING DAY. CONCERN IS HOW FAR SOUTH ND CLOUDS WILL MAKE IT. THEY CURRENTLY APPEAR TO BE PUSHING ALMOST STRAIGHT EAST. ALSO CONCERNED ABOUT TEMPS. TEMPS ARE RUNNING AOA FORECAST HIGHS MOST PLACES. WITH WARM FRONT PUSHING THROUGH AND DECENT MIXING WINDS...WILL HAVE TO UP TEMPS MOST PLACES. WILL TWEAK CLOUD COVER AND GO PCLOUDY ALONG NORTHERN TIER COUNTIES...WHILE KPIR WILL REMAIN MOSTLY SUNNY. WILL PLAY WITH WINDS AS WELL. UPDATES OUT SHORTLY. .ABR...NONE. HINTZ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 835 PM CST FRI DEC 31 1999 WEAK LOW PRESSURE CENTER CONTINUES OVER THE SOUTHERN MISSISSIPPI VALLEY IN SW MISSISSIPPI. A WEAK STATIONARY FRONT EXTENDS NORTHWARD FROM THE LOW TO NORTHERN MISSISSIPPI AND THEN CURLS TOWARD THE ENE THROUGH SOUTHERN MIDDLE TENNESSEE EASTWARD INTO THE CAROLINAS. THE SYSTEM HAS BEEN ATTEMPTING TO PUSH LOW AND MID CLOUDS NORTHWARD INTO THE FORECAST AREA(FA). A WEAK SURFACE RIDGE IS SEEN ACROSS THE OHIO VALLEY PULLING SLOWLY EASTWARD. THE NEXT MAJOR SYSTEM IS THE LOW PRESSURE IN THE LEE OF THE ROCKIES ASSOCIATED WITH AN H5 SHORTWAVE OVER SOUTHERN CALIFORNIA. IN THE SHORT TERM...LATEST MESO-ETA AND RUC BRING IN A GOODLY AMOUNT OF MOISTURE MAINLY BELOW 800MB WITH LITTLE IF ANY LIFT. CURRENT FORECAST FOR INCREASING CLOUDINESS AND A SLIGHT CHANCE OF RAIN (IN THE SOUTH AND EAST) SEEMS TO BE HITTING THE RIGHT NOTE. TEMPERATURE TRENDS EXPECTED BY THE FWC SEEM TO BE ON TRACK FOR A LOW IN THE MID 40S. WILL MAKE NO CHANGES FOR THIS MILLENIUM. .BNA...NONE. 18 JLM tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 910 PM EST FRI DEC 31 1999 SC DECK SEEN TRYING TO FORM AS BL/SFC WINDS BEGIN TO TURN TO THE SOUTHEAST IN WRN NC. H8 WINDS STILL MOSTLY WEST AND DOWNSLOPING SOME. THIS HAS HAD AN ERODING EFFECT EVEN AS SC FORM. RUC KEEPS WINDS ADVECTING LOW LEVEL MOISTURE VERY LIGHT THROUGH THE NEXT SEVERAL HOURS...WHILE MESO-ETA IN THE LATER HOURS CONTINUES NORTHWARD PROGRESS OF RH ALONG BOTH SIDES OF THE APPALACHIANS...WITH WITH VERY LIGHT WINDS. WITH CLEAR SKIES TEMPS IN VALLEYS DIPPING QUICKLY...WITH LWB AT 30 AT RNK 28. WILL BE A BIT MORE OPTIMISTIC WITH CLOUD COVER OVERNIGHT GREENBRIER VALLEY AND NRV. WILL LOWER MINS IN THESE REGIONS WITH LIGHT WINDS AND CLEAR SKIES FOR AT LEAST AN ADDITIONAL 4 TO 6 HOURS. THATS IT. A HAPPY NEW YEAR TO ALL! .RNK VA...NONE. WV...NONE. NC...NONE. NOGUEIRA va EASTERN WASHINGTON AND NORTH IDAHO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WASHINGTON 900 AM PST FRI DEC 31 1999 SOME CLEARING EVIDENT BEHIND FRONTAL BAND PRECIPITATION NOW MAINLY SE PART OF CWFA. LIGHT/MODERATE SNOW CONTINUING IDAHO ZONES 4 AND PULLMAN SOUTHWARD. VERY FAINT VORT MAX ON SATELLITE NOW OVER COLUMBIA RIVER MOUTH. RUC MODEL HAS THIS NICELY AND TRACKS IT INTO NE OREGON THIS AFTERNOON. EXPECT THIS TO ENHANCE AND CONTINUE PRECIPITATION SE CORNER OF CWFA ESPECIALLY OVER IDZ027. HENCE SNOW ADVISORY WILL CONTINUE INTO THE AFTERNOON HOURS FOR THIS REGION. REMAINDER OF CWFA WILL BE IN AND OUT OF MID LEVEL CLOUD DECK WITH LOW CLOUDS HANGING STILL IN BASIN. ONLY SCATTERED SNOW SHOWERS EXPECTED REMAINDER OF TODAY REST OF CWFA. UPSTREAM HAVE STG JET INTENSIFYING NWLY FLOW AND SENDING PERIODIC WAVES OF PRECIP BUT MAINLY TO THE ID PANHANDLE MOUNTAINS AND SOME TO THE NORTHERN ZONES. WILL UPDATE ZONES MAINLY FOR LACK OF CLOUDS OVER NRN PORTION OF CWFA. ALSO COLDER THAN ANTICIPATED SO WILL ADJUST TEMPS DOWN. TC ...THE INFORMATION IN THIS PRODUCT CONCERNING WARNINGS AND FORECASTS IS VALID ONLY AT THE TIME OF ISSUANCE. THE LATEST WARNING AND FORECAST INFORMATION WILL BE FOUND IN THE APPROPRIATE PRODUCTS... GEG 028/023/030 245 CQV 029/023/030 346 S86 028/024/029 366 COE 028/023/031 245 WWP 024/020/025 866 LWS 034/031/033 734 MOS 029/025/030 EAT 032/025/032 113 .GEG...SNOW ADVISORIES TODAY FOR ID ZONE 4 3 27 AND WA ZONE 33. wa AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 829 PM MST FRI DEC 31 1999 CURRENT SFC ANAL SHOWS LIGHT AND VARIABLE WINDS ACROSS THE ENTIRE CWA. THIS IS A RESULT OF ONE SFC TROF MOVG THRU ERN CWA...AND LEE TROF AND SFC LOW REDEVLPG/STRENGTHENING TO THE WEST. THIS SCENARIO OFTEN DVLPS WHEN HAVE MULTIPLE S/WS MOVG THRU OR APRCHG THE AREA. AS NRN PLAINS S/W MOVES AWAY...AND AS S/W APRCHES CWA OVERNIGHT AND UPR LOV MOVES INTO SWRN CONUS...LOOKS LIKE THE ERN MOST TROF WL WASHOUT/MOVE AWAY AND LEE TROF/SFC LOW TO WEST WL CONT TO DEEPEN. HWVR UNTIL SFC RDG PASSES THRU THE AREA TONIGHT AND LEE TROF GETS MORE ESTABILISHED...WINDS SHOULD REMAIN ON THE LIGHT SIDE. THE RUC AND MESOETA SEEM TO CATCH THIS SCENARIO THE BEST AND WL PUT LIGHT WINDS INTO FCST. ALSO BASED ON CURRENT SATL...WL CHANGE CLD COVER TO PCLDY. HAVE ALREADY DROPPED FAIRLY RAPIDLY ON TEMPS...AND SOME LOCATIONS ARE ONLY 5 TO 10 DEGREES ABV FCST MINS. BASED ON DPS AND LIGHT WINDS...WL LWR MINS IN NW HALF OF CWA DOWN TO NR 20 EVEN WITH THE CLD COVER. DPS IN S AND SE PTN OF CWA SUPPORT KEEPG CURRENT MINS THERE. .GLD...NONE. BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1056 AM MST FRI DEC 31 1999 WARM CONTINUES AHEAD OF EXPECTED PACE WITH LATEST RUC2 AND 12Z ETA SUGGESTING MAXES 60 TO 67 FROM WEST TO EAST. WINDS ALSO STAYING UP A LITTLE LONGER THAN EXPECTED OVER THE WESTERN THIRD OF THE CWFA. ZONE UPDATE FORTHCOMING. .GLD...NONE. ENTWISTLE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1030 PM EST FRI DEC 31 1999 CONCERNS CENTER ON WEAK LOW CROSSING SUPERIOR REGION OVERNIGHT. ZONAL 500MB FLOW IS ESCORTING YET ANOTHER WEAK CYCLONE ACROSS THE U.P. 00Z SURFACE ANALYSIS SHOWS THE LOW IN WESTERN MINNESOTA...WITH THE ETA VERIFYING BEST AMONG THE 12Z MODELS REGARDING DEPTH OF THE LOW. IR SATELLITE IMAGERY SHOWS ENHANCED CLOUDS OVER NORTHERN U.P. AND LAKE SUPERIOR. FORECAST AREA IS NOW UNDER GOOD 700-300MB QVECTOR CONVERGENCE DOWNSTREAM OF THE SURFACE LOW...BUT BEST 1000-500MB LAYER RH IS MAINLY OVER LAKE SUPERIOR AND ONTARIO. BROAD AREA OF 88D REFLECTIVITIES AS HIGH AS 20 DBZ COVERS MUCH OF THE NORTHERN FORECAST AREA... BUT U.P. METARS HAVE SHOWN NO PRECIPITATION THUS FAR. FURTHER UPSTREAM IN MINNESOTA THERE WAS ALMOST NO SNOW EARLIER TODAY WHEN THE QVECTOR CONVERGENCE AND ENHANCED IR CLOUD TOPS WERE THERE. HIGHER 88D REFLECTIVITIES HAVE EXITED MINNESOTA AND NORTHWEST WISCONSIN. FOR THE REMAINDER OF TONIGHT... CHANCE OF SNOW LOOKS MINIMAL. ENTIRE FORECAST AREA WILL COME UNDER ADVANCING 700-300MB QVECTOR DIVERGENCE FROM 06Z TO 12Z. LATEST RUC QPF IS BONE DRY OVER THE FORECAST AREA...AND THIS LOOKS GOOD...ESPECIALLY GIVEN DRY HISTORY OF THIS SYSTEM. WITH LOW CENTER PROGGED TO CROSS FROM NEAR IWD TO FAR EASTERN LAKE SUPERIOR FROM 06Z TO 12Z...FORECAST AREA WILL BE UNDER A RELATIVELY WEAK PRESSURE GRADIENT NEAR THE LOW CENTER. WILL FORECAST WINDS SOMEWHAT LIGHTER THAN CONTINUITY OVER INLAND COUNTIE ...AS PER LATEST FLP GUIDANCE AND RECENT METARS IN CENTRAL MINNESOTA NEAR LOW CENTER. .MQT...NONE. ES mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 344 AM CST SAT JAN 01 2000 SURFACE COLD FRONT MAKING IT'S WAY THROUGH SE MN AT THIS TIME. WEAK RIDGE OF HIGH PRESSURE TO MOVE ACROSS THE STATE THIS MORNING. FOG PRODUCT SHOWING BAND OF LOW CLOUDINESS IN THE WAKE OF THE FRONT COVERING MUCH OF NORTHERN MN. NEITHER THE RUC OR THE MESO-ETA GOOD AT SHOWING THE LOW LEVEL MOISTURE. IN FACT...LOW LEVEL RH ACTUALLY DECREASES THIS MORNING WITH THE RIDGING MOVING OVERHEAD. WITH SHORTWAVE APPROACHING FROM THE WEST...MID/HIGH LEVEL CLOUDINESS WILL BE ON THE INCREASE SO WILL USE INCREASING CLOUDINESS FOR TODAY. SOME RECOVERY EXPECTED IN THE TEMPERATURES TODAY WITH FAN/NGM MOS LOOKING GOOD. MODELS IN FAIR AGREEMENT ON WHAT TO EXPECT TONIGHT. ONE NICE THING IS THAT THE APPROACHING LOW PRESSURE SYSTEM DOES NOT REALLY GET IT'S ACT TOGETHER UNTIL IT IS EAST OF HERE SUNDAY MORNING. ETA SEEMS TO FAST WITH THE NGM/AVN IN BETTER AGREEMENT. BUT THEN THE NGM IS THE WARMEST IN THE LOW LEVELS WHILE THE ETA/AVN AGREE BETTER WITH THE LOW LEVEL THERMAL FIELDS. HAVE DECIDED TO MODEL THE FORECAST AFTER THE AVN RUN. SOUNDING DATA INDICATES DEEP LAYER SATURATION DOES NOT OCCUR ACROSS MUCH OF THE MN CWA AND ONLY EARLY SUNDAY MORNING ACROSS THE WI CWA. THIS POSES SEVERAL PROBLEMS. SOUNDING DATA INDICATES MAINLY LOW LEVEL SATURATION TONIGHT ALONG WITH HIGH LEVEL SATURATION LEAVING A DRY SLOT BETWEEN 800 AND 600 MB. LOW LEVEL TEMPERATURES RUN BETWEEN 0 AND -5C INDICATING SOME FREEZING DRIZZLE/RAIN IS POSSIBLE. BEST CHANCE FOR SNOW THEN COMES TOWARD DAYBREAK SUNDAY IN EASTERN MN WHEN SOME MID LEVEL SATURATION IS INDICATED FOR A FEW HOURS. DEEP LAYER SATURATION THEN BLOSSOMS ACROSS WI EARLY SUNDAY WITH OUR WI CWA HAVING THE BEST CHANCE FOR SOME SNOW ACCUMULATION. EPV/Q-VECTOR PRODUCT FROM THE AVN SHOWS LITTLE FORCING AT 700 MB WHILE THE ETA HAS THE "GREENIES" PASSING ACROSS IA AND SOUTHERN WI. WITH AN OPEN WAVE AT 700 MB...WEAK CLOSED LOW AT 850 MB AND NET VERTICAL DISPLACEMENT INCREASING FROM 20 TO 80 MB ACROSS WI BETWEEN 00 AND 12Z SUNDAY WILL CONTINUE WITH UP TO 4 INCHES OF SNOW FOR THE NORTHERN WI CWA. MIXING RATIO BETWEEN 700 AND 750 MB IS AROUND 2 G/KG. SNOW WILL DIMINISH TO FLURRIES SUNDAY AFTERNOON IN THE WI CWA WITH MAINLY CLOUDY SKIES ACROSS THE MN CWA. WILL BE ISSUING AN SPS FOR THE POSSIBILITY OF A WINTRY MIX LATE TONIGHT AND EARLY SUNDAY. .MSP...NONE. HILTBRAND mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 908 AM MST SAT JAN 1 2000 ZONE UPDATES ISSUED TO ACCOUNT FOR WINDS CONTINUING NORTHWEST THROUGH THE AFTERNOON IN THE WESTERN AND CENTRAL PORTIONS OF THE CWFA PER RUC2...QUICK LOOK AT NEW RUNS...AND CURRENT OBS. VARIABLE WINDS EXPECTED IN EASTERN GROUP. MAX TEMPS IN THE EAST AND SOUTH SHOULD APPROACH 60F BASED ON 12Z SOUNDINGS AND THE AFOREMENTIONED MODELS. TEMPS IN THE LOWER TO MIDDLE 50S LOOK GOOD ELSEWHERE. .GLD...NONE. ENTWISTLE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1110 AM EST SAT JAN 01 2000 ON GOING FORECAST LOOKS FINE. UPDATED WORDING TO DROP MENTION OF MORNING FROM ZONES. LARGE AREA OF CI/CS DEVELOPING NICELY OVER A LARGE AREA TO OUR WEST AND SOUTHWEST AHEAD OF THE DEVELOPING SYSTEM IN THE SOUTHERN PLAINS. THESE CLOUDS HAVE ALREADY STARTED TO OVERSPREAD THE GRR AREA AND WILL CONTINUE TO INVADE THE REST OF THE CWA DURING THE AFTERNOON. HIGHS IN THE MID 40S LOOK FINE... IT IS ALREADY NEAR 40 IN MANY LOCATIONS... SNOW COVER OR NOT. RATHER SHALLOW INVERSION ON RUC/ETA SOUNDINGS NEAR 950 MB THIS AFTERNOON WHICH IS SIMILAR TO DTX 12Z SOUNDING. VERY DRY TH ROUGH 500 MB THROUGH 00Z. SO EXPECT HIGHS MOSTLY BETWEEN 43 AND 47F. QUICK LOOK AT LATEST MODELS INDICATES NO IMPORTANT CHANGE TO GOING FORECAST TONIGHT/SUNDAY AT THIS POINT. COULD BE CHANCES FOR MONDAY THOUGH AS LATEST MODELS (12Z ETA/NGM/AVN/CANADIAN) HAVE TRAILING LOW MUCH FARTHER WEST THAN PREVIOUS RUNS AND BASED ON LOCATION OF LONGWAVE TROF... IT WOULD MAKE SENSE TO HAVE A SUFACE LOW CLOSER TO UPPER TROF. COULD MEAN MORE RAIN MONDAY. .GRR...NONE. WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1100 AM EST SAT JAN 1 2000 FCST CONCERNS FOR THE AFTN ARE TEMPS AND POSSIBLE LAKE EFFECT -SHSN. WV IMAGERY SHOWS SHORTWAVE APPROACHING 4 CORNERS AREA OF SW U.S. ANOTHER SHORTWAVE WAS MOVING E ACROSS FAR S SASKATCHEWAN. HIGH CLOUDS EXPANDING ACROSS CNTRL U.S. IN ADVANCE OF BOTH SYSTEMS. CLOSER TO HOME AND AT THE SFC...HIGH PRESSURE WAS JUST E OF LAKE WINNIPEG. CAA AHEAD OF SFC HIGH BEGINNING TO PRODUCE LAKE EFFECT CLOUDS OVER LK SUPERIOR...ESPECIALLY CNTRL/E. 12Z RAOB AT KINL SHOWS 850MB TEMP AT -12C WITH 30KT NW WIND. 12Z RUC INITIALIZED 850MB TEMPS WELL...AND IT SHOWS TEMPS FALLING TO ABOUT -10C ACROSS LK SUPERIOR THIS AFTN. GIVEN DEVELOPING LAKE CLOUDS ALREADY...LIKELY TO SEE SOME -SHSN DEVELOP THIS AFTN AS DELTA-T REACHES 13C. HOWEVER...LOW-LEVEL WINDS SHIFT THROUGH THE AFTN FROM NW TO NE BY EVENING. WIND FLOW ALSO BECOMES NOTABLY ANTICYCLONIC AS SFC HIGH MOVES TO JUST N OF LK SUPERIOR BY 00Z. THIS WILL PREVENT ANY ORGANIZED -SHSN FROM DEVELOPING...AND WITH MARGINAL DELTA-T OF 13C...CURRENT FCST OF FLURRIES IS ON TARGET. SHALLOW COLD AIRMASS WILL CONTINUE TO FILTER INTO FA THIS AFTN. WITH MOSTLY CLOUDY SKIES...TEMPS SHOULD REMAIN FAIRLY STEADY OR EVEN FALL A FEW DEGREES N FA. 12Z ETA SUPPORTS GOING WINTER STORM WATCH FOR SE FA LATE TONIGHT/SUN MORNING. IN DEPTH LOOK AT ALL MODELS THIS AFTN WILL NEED TO BE DONE BEFORE DECIDING FATE OF WATCH. .MQT...WINTER STORM WATCH LATE TNGT/SUN MRNG MIZ012>014. ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1032 AM EST SAT JAN 1 2000 SFC LOW IS MAKING SLOW PROGRESS SE THROUGH ERN LAKE SUPERIOR. TRAILING COLD FRONT EXTENDS FROM THE LOW THROUGH GREEN BAY TO S CENTRAL WI. LOW LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM IS FAIRLY SHALLOW PER 12Z APX SOUNDING AND LATEST RUC PROGS...AND REMAINS SHALLOW THROUGH THE AFTERNOON. HOWEVER...MID/UPPER LEVEL MOISTURE WILL BE ON THE INCREASE FROM SW TO NE AHEAD OF THE DEVELOPING PLAINS SYSTEM. THUS...THOSE AREAS THAT ARE STILL RECEIVING SOME SUN (I.E. SRN TIER OF COUNTIES) WILL SEE INCREASING CLOUDS THROUGHOUT THE AFTERNOON. WILL UPDATE ALL ZONES MAINLY TO FRESHEN WORDING OF THE FORECAST. OVERALL TRENDS LOOK IN LINE. .APX...WINTER STORM WATCH...SUNDAY...MIZ008-015. EME mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 937 AM EST SAT JAN 1 2000 THE GREAT START TO THE NEW YEAR FOR NON WINTER ENTHUSIASTS WILL CONTINUE THRU THE WEEKEND. CLIPPER RACING ACROSS CNTRL ONTARIO THIS AM WITH MID CLOUDS SCOOTING THRU NRN SXNS OF CWFA. THESE SHOULD MOVE OUT EARLY THIS AFTN PER SATL TRENDS AND 12Z RUC RH FCSTS...THEN JUST SOME INCIDENTAL THIN CI. LOW CLDS MOVG NWD THRU WV/VA LOOK TO BE HELD AT BAY TIL EVENING AND FOG IN WY VLY LIFTING OUT AS WELL. XPCT ALL AREAS WL BASK IN WINTER SUN AND MILD SWLY FLOW FOR RMNDR AFTN. SOUNDINGS AND LAMP FCSTS GET MAX T'S INTO 40S ACROSS THE BOARD. CURRENTS VERIFYING WITH GUIDANCE TRENDS THUS FAR AS INVERSION BREAKS SO ONLY MINIMAL TWEEKS TO SKY CONDITS ARE EXPECTED THIS UPDATE. WL HOPE FOR MORE STABLE BUFR DATA TODAY TO EVALUATE FZDZ SITN TONITE AS POLAR HIPRES BEHIND CLIPPER SAGS FRONT INTO AREA AND MOIST SWLY FLOW RIDES OVER COLD DOME. WRKZONES OUT AS ADMBGM...FINALS ABOUT 10 AM. .BGM...NONE. BREWSTER ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1000 AM EST SAT JAN 1 2000 IT IS APPARENT THE CRNT FCST WILL HAVE TO UNDERGO SOME MINOR SURGERY THIS AM WITH LOW CLD DECK AND LIGHT RAIN ACRS CENT SC MOVING NE TOWARD CWFA. THIS IS RESULTING FROM A WEAK H50 S/W - H70 DIFF THAT RUC CARRIES OVR OUR REGION THIS AFTN. SFC RIDGE AXIS CRNTLY ALLOWING CLDS TO ERODE A BIT ATTM...BUT RUC WEAKENS THIS FEATURE OVER TIME AND CLDS/SPRINKLES SHOULD EDGE TOWARD THE COAST BY LATE AFTN. MOSTLY CLOUDY SW ZONE GROUPS/BECOMING (PC/MC?) NE ZONES. LIGHT WINDS BECOMING EAST. TEMPS WILL BE LOWERED A CAT MOST AREAS AND PERHAPS TWO CAT FURTHER INLAND. CWF...WILL GO WITH N WIND 10 KT OR LESS TO START OUT WITH AND SWING ARND TO THE E. SEAS 2 FT OR LESS. .ILM...NONE. JFP nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CHARLESTON SC 633 AM EST SAT JAN 1 2000 AFTER WATCHING CROSS SXNS OF 88-D FOR PAST HOUR OR SO...AND PCPN SHAFTS CONT TO CREEP CLOSER TO THE GROUND. CONSIDERING THAT PCPN IS MOVING INTO A COOLR...AND THEREFORE EASIER TO SATURATE LO LVL ATMOS...HV TO BELIVE THAT ENUF OF THIS PCPN ALOFT WL MAKE IT DOWN TO THE GROUND TO BE NOTICEABLE. LATEST RUC/MESOETA DATA STILL SUGGEST THAT BEST ISENT LIFT WL REMAIN W OF OUR AREA AND ONCE APPCHNG VORT MOVS OFFSHORE THS AFTN...STL BELIVE THERE WL BE ENUF DRYING TO JSTFY P CLDY. THEREFORE WILL UPDATE ENTIRE PKG TO PUT IN PATCHY LGT RA BUT KP BECMNG P CLDY WORDNG. UPDATE WL BE OUT SHRTLY. .CHS... SC...NONE. GA...NONE. WOODWORTH sc SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 930 AM CST SAT JAN 1 2000 SUNNY WITH PATCHY FOG GENERALLY NORTH OF I-10 AND CLOUDY SOUTH OF I-10 AT MID-MORNING. THE PRIMARY UPDATE ISSUE IS THE STRONG WARM/MOIST SURGE OVER A COOL BOUNDARY LAYER. THE RESULT IS A LOW BKN/OVC DECK SOUTH OF I-10...ALONG WITH VERY LOW VISIBILITY TO THE S/W OF SERN TX. THE 00Z NCEP MODELS/LATEST RUC DON'T DO THE BEST JOB OF PORTRAYING THE LOW-LEVEL MOIST SURGE...BUT WELL ENOUGH TO SUPPORT FURTHER NORTHWARD LIFT ON THE 290K ISENTROPIC SURFACE. DIURNAL MIXING SHOULD RAISE CEILINGS SLOWLY AND PRODUCE MORE BKN THAN OVC WITH TIME. TEMPS WILL BE AFFECTED BY THE CLOUDCOVER AND A COLD START...BUT LAMP GUIDANCE SEEMS TO HAVE PICKED UP THE TREND. THE FORECAST UPDATE WILL HAVE SIGNIFICANT CHANGES...NAMELY FROM A SUNNY/PARTLY CLOUDY SKY TO MOSTLY CLOUDY...AND A CATEGORY TO CATEGORY AND A HALF LOWER TEMPS FOR ALL ZONES. .HGX...NONE. 31/36 UPDATED PRELIMS... CLL EE 070/061 075/060 070 0022 IAH EE 068/060 076/060 071 0022 GLS EE 067/063 071/063 070 0022 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 223 PM CST SAT JAN 01 2000 ONCE AGAIN TODAY...TOUGH FORECAST FOR NO HEADLINES WITH ALL FORECAST ELEMENTS IN QUESTION. YESTERDAY'S FORECAST ACTUALLY WORKING OUT WELL FOR THE CURRENT TIME PERIOD WITH S/W CONUS SYSTEM AROUND 4 CORNERS. WARM ADVECTION CLOUDS AND A FEW SPRINKLES INVADING IA FROM THE SW. ITS THIS FEATURE AND PTYPE IT BRINGS THAT MAY PROVIDE THE MOST DIFFICULT FORECAST CHALLENGE. ELSEWHERE AT UPPER LEVELS SYSTEM COMING ASHORE IN PAC NW TO EFFECT IA ON MONDAY NOT TUESDAY. AT THE SFC...DOUBLE LOW STRUCTURE OVER WRN KS TO NE CO WITH STRNY FRONT FROM KGLD TO KCID. THIS LIKELY TO MOVE BACK NORTH AS A WARM FRONT THIS EVENING AS ANOTHER NORTHWARD MOVING WARM FRONT FROM KCNK TO KCOU CATCHES UP WITH IT. ARCTIC AIR WELL NORTH INTO ND AND NRN MN NOT TO EFFECT NEAR TIME PERIODS. AS OFTEN HAPPENS WITH SYSTEMS COMING ASHORE...WHETHER IN THE NW OR SW...BEGIN TO BE HANDLED BY ETA. THIS IS AGAIN HAPPENING THOUGH AVN SHOWS VERY SIMILAR SOLN TOO. WILL GO THAT WAY. PRIMARY CHALLENGE TONIGHT IS ONSET OF PRECIP...THATS ALREADY BEGINNING TO OCCUR WITH A FEW SPRINKLES LIKELY HITTING GROUND FROM DNS AND WEST. WILL GO WITH THAT LINE OF THINKING MOST AREAS TONIGHT. FROM POCAHONATAS COUNTY TO MCW AND POINTS NORTH THOUGH...A LITTLE VERY LIGHT...INTERMITTENT FZRA COULD OCCUR LATE THIS EVENING AS PARTIAL THICKNESSES BEGIN TO FALL. ALSO DUE TO DRY LOW LEVELS...WILL GET SOME COOLING TO DUE EVAP. MOST PLACES THO WON'T SEE TEMPS FALLING ENOUGH FOR THAT. 18Z RUC ALSO LEANING AWAY FROM FZRA POTENIAL IN NORTH AS THICKNESSES AND TEMPS JUST AREN'T COOL ENOUGH. SUNDAY...AS THICKNESSES SLOWLY FALL...MAY SEE SOME MORNING FLURRIES NRN HALF CWA WITH SPRINKLES SOUTH AS 4 CORNERS SYSTEM MOVES THROUGH PLAINS AND MISSOURI VALLEY. GUID TEMPS REASONABLE AND IN AGREEMENT. COULD BE A LITTLE SUN SHOW UP IN WRN CWA LATE...BUT WITH NEXT BATCH OF HIGH CLOUDINESS ONCOMING...WILL NOT BE TOO MUCH. SUNDAY NIGHT TO REMAIN QUITE AS WE'RE STILL BARELY BETWEEN SYSTEMS. GUID TEMPS BEGIN TO DIVERGE. WILL SIDE TO COOLER NUMBERS WITH CAA PERHAPS OVERCOMING CLOUDY SKIES. FOR MONDAY...YESTERDAYS TUES SYSTEM HAS SPED UP AND WOULDN'T BE SURPRISED TO SEE THIS HAPPEN WITH VERY FAST JET OFF NW PAC COAST. TEMPS NEAR THE FREEZING MARK IN THE SOUTH WITH LITTLE RISE ANYWHERE. 50 POP SOUTH FOR R/S LESSER POPS FARTHER NORTH FOR ALL S. EXTENDED...REMAINS PRETTY TOUGH WITH DIFFERING SOLNS ESP BY DAY 5. AVN KEEPS CYCLONIC FLO AND PLENTY OF RH OVER IA...WITH COLD TEMPS WILL RUN WITH FLURRIES. WED TO BE DRY EXCEPT FOR CAN/US BORDER LOW AND TRAILING COLD FRONT PER MRF/CAN/ECMWF SO NRN IA MAY SEE SOME LIGHT SNOW. BY THU...MANY DIFF SOLNS AND WILL SIDE WITH DRY...UNLIKE VERY PESSIMISTIC MRF. .DSM...NONE SEARCY ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 230 PM EST SAT JAN 1 2000 NEW YEAR STARTS OUT ON A MILD NOTE. SFC HI PRES CNTRD OFF NC CST HELPING TO KEEP WARM AMS IN PLACE OVR SERN STATES. PTCHY FOG JUST RECENTLY BURNING OFF WITH SKIES BECMG PTCLDY AS WK S/W EXITS STATE AS SHOWN BY LATEST RUC. MODELS IN DECENT AGREEMENT DEPICTING SW FLOW ALF WHICH WL CONTINUE THRU PD. SERIES OF S/WS CARVE OUT NXT TROF AS IT APPROACHES MID-SECTION OF NATION BY MON AM. MODELS A BIT SLOWER NOW WITH THIS FEATURE...ESPECIALLY AVN. WK S/W WL MOV THRU STATE SUN BUT XPCT NO PRECIP ATTM...ALTHO WITH GD LOW-LVL MSTR AVBL...MAY SEE MORE PTCHY FOG LINGERING INTO THE LATE AM HRS SUN WITH LGT S WNDS. PTCLDY-MCLDY SKIES WL PERSIST THRU PD AS LWR LAYERS OF AMS BECOME MORE MOIST INTO SUN. MAY SEE SLGT CHC OF RAIN LATE MON AS TROF GETS CLOSER. IN THE EXTENDED...UPR TROF SWINGS OFSHR WED. RDG BLDS THRU MUCH OF REMAINDER OF WK WITH NR SEASONABLE TEMPS. CONSENSUS OF GUIDANCE NUMBERS FOR TEMPS LUKS REASONABLE. PRELIM CCFS CAE BE 47/75/53/75/54 22000 AGS BE 46/75/52/74/52 22000 .CAE...NONE. BC sc