AREA FORECAST DISCUSSION. NATIONAL WEATHER SERVICE GOODLAND KS 203 PM MST FRI JAN 21 2000 ...FORECAST CONCERNS ARE TEMPERATURES AND CHANCES OF PRECIP... LATEST GUIDANCE INDICATING A GOOD VORT MAX IN THE ZONAL FLOW ALOFT WILL PASS THROUGH THE AREA AROUND 00Z THIS EVENING. THIS VORT MAX WILL INTERACT WITH A SURFACE LOW OVER SOUTHEAST COLORADO. MID LEVEL MOISTURE INCREASES AT THE SAME TIME WITH 850-700 MB LAPSE RATES INCREASING. THE AREA WILL ALSO BE IN THE LFQ OF THE 250 MB JET. NOT REALLY EXCITED ABOUT THE CHANCE OF ANY PRECIP...ESPECIALLY WITH A LACK OF AN UPSLOPE COMPONENT. AFTER LOOKING AT THE CANADIAN/LATEST RUC AND 18Z ETA...I DECIDED TO REMOVE THE MENTION OF PRECIP. THERES A BRIEF (3 HOUR) PERIOD OF UPWARD MOTION BUT IT QUICKLY DECREASES AFT 4Z. MOISTURE X-SECTIONS SHOW SUBSTANTIAL CLOUDCOVER EARLY TONIGHT BEFORE SUBSIDENCE ERODES MUCH OF THE CLOUDS. WILL GO NEAR GUIDANCE BUT FEEL IT MAY BE TO LOW. WILL AWAIT THE 18Z ETA. THE SURFACE LOW MOVES AWAY SATURDAY AS A WEAK SURFACE HIGH MOVES INTO THE NORTHEAST CWA. 850 COOL A FEW DEGREES SUGGESTING TEMPS NEAR 45. FWC GUIDANCE ALSO IN LINE WITH MY THINKING. WE'LL BE IN BETWEEN SYSTEMS SO SOME SUN SHOULD BE SEEN WITH SUBSIDENCE OVER THE AREA. NEXT WEEK SYSTEM FORECAST TO MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY MORNING. FORECAST CONTINUES TO INDICATE AN OVERNIGHT EVENT AND I SEE NO REASON TO DEVIATE...ESPECIALLY NOW THAT THE FWC HAS RAISED POPS TOWARD 30 PERCENT. AS FAR AS TEMPS...NOT VERY CONFIDENT THAT WE'LL DROP INTO THE TEENS WITH SOME PRECIP FALLING AND ABUNDANT CLOUDCOVER. DEWPOINTS ARE IN THE MIDDLE TEENS. WILL GO NEAR 20/LOWER 20S. SUNDAY WILL ALSO BE TRICKY AS COLD FRONT IS FORECAST TO BACK INTO THE AREA WITH THE NGM THE BOLDEST AND ETA/AVN A LITTLE MORE CONSERVATIVE. AVN MOISTURE AND COOLER AIR MAKES IT INTO THE EASTERN CWA WHERE I'LL KEEP A CHANCE OF SNOW AND COOLER TEMPS. AS YOU GO EAST TEMPS WILL BE SLIGHTLY WARMER WITH A LITTLE MORE SUN. NGM APPEARS TO BE RUSHING THINGS ABIT AS FAR AS TEMPS SO I'LL GO A BIT ABOVE OVER THE EAST AND MORE OVER THE CENTRAL AND WESTERN ZONES. IN THE EXTENDED...WILL AGAIN GO WITH THE MRF/NOGAPS SOLUTION. FORECAST AREA TO REMAIN IN NORTHWEST FLOW ALOFT WITH EMBEDDED VORT MAXIMA UNTIL WEDNESDAY WHEN SOME RIDGING AND WARMER 850 TEMPS ARE FORECAST. UNTIL THEN COLDER AIR WILL BACK INTO THE AREA WITH COLDEST TEMPS EAST AND WARMER TEMPS WEST. NOT A LOT OF SIGNIFICANT MOISTURE TO WORK WITH SO DRY LOOKS OK. .GLD...NONE THEDE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1025 PM EST FRI JAN 21 2000 LES CONTINUES TO LINGER ON THIS EVENING...ALTHOUGH SURFACE OBS AND A CALL TO EASTERN UPPER DON'T INDICATE ANYTHING REAL SIGNIFICANT OCCURRING. HIGH CLOUDS RACING ACROSS WI ATTM HAVE BEEN THINNING A BIT AS THEY APPROACH NORTHERN LOWER...WITH SOME THICKER MID CLOUD SPREADING ACROSS MN AND INTO WESTERN/CENTRAL WI. ISENTROPIC TRAJECTORIES SUGGEST THAT THESE CLOUDS SHOULD TEND MORE SOUTHEAST WITH TIME AND REMAIN OUT OF THE AREA UNTIL SATURDAY MORNING. MEANWHILE...IR LOOPS SHOW BANDS OVER NORTHERN LAKE SUPERIOR VEERING A BIT MORE TO THE NORTH. LATEST RUC A BIT SLOWER TO TURN LOW LEVEL WINDS WESTERLY OVERNIGHT THAN EARLIER MODEL RUNS...AND CURRENT TRENDS SEEM TO SUPPORT THIS. INVERSION HEIGHTS CONTINUE TO COME DOWN OVERNIGHT...FROM THE CURRENT 6K FEET DOWN TOWARD 4K FEET...BUT WITH A CONTINUED TRAJECTORY OFF OF LAKE SUPERIOR WILL CONTINUE TO MENTION SNOW SHOWERS INTO EASTERN UPPER... ENDING LATE AS LOW LEVEL WIND FLOW TENDS TOWARD THE WEST. SIMILAR STORY FOR NORTHWEST LOWER...WILL ALLOW FOR SNOW SHOWERS TO TAPER OFF LATE AS WINDS TURN MORE TOWARD THE WEST AND FETCH SHORTENS UP ALONG WITH INCREASED DRYING BELOW INVERSION...CLOUD GENESIS AREA OVER NORTHERN LAKE MICHIGAN HAS SHOWN A NOTICEABLE SHIFT CLOSER TO SHORE DURING THE EVENING HOURS. BACKING LOW LEVEL WINDS MAY PUSH SOME LAKE CLOUDS INTO STRAITS AREA COUNTIES LATE. NO ACCUMULATIONS MENTIONED ANYWHERE OVERNIGHT...SHOULD NOT BE SIGNIFICANT. EARLIER UPDATE TO LOWER TEMPERATURES NOT LOOKING TOO BAD WITH OSC/HTL ALREADY AT -8...SOME PATCHY SC FLOATING ACROSS NORTHEAST LOWER MAY KEEP READINGS FROM GETTING TOO OUT OF HAND BUT TEENS BELOW ZERO LOOK TO BE A GOOD BET. UPDATED ARBZFPAPX WILL BE OUT AT 0330Z. .APX...NONE. JPB mi NORTHERN GREAT BASIN FORECAST DISCUSSION NATIONAL WEATHER SERVICE ELKO NV 200 PM PST FRI JAN 21 2000 SYNOPSIS...LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST WILL MOVE INLAND TODAY. A MOIST WEST FLOW OVER THE GREAT BASIN TODAY WILL TURN NORTHWEST THIS WEEKEND. THIS WILL ALLOW COLDER AIR TO FILTER INTO NORTHERN NEVADA AND LOWER SNOW LEVELS. SHORT TERM...NEW RUC MODEL SHOWS WELL SHORTWAVE ENHANCING INTO NORTHERN CALIFORNIA THIS AFTERNOON WITH SATELLITE PIX SHOWING SOME RAPID CONVECTIVE DEVELOPMENT. VIS PIX ALSO SHOW CONVECTIVE CLOUDS ALONG THE NORTHERN NEVADA/IDAHO BORDER IN BEST DIVERGENT AREA. SECOND AND MAIN SHORTWAVE ENERGY BEHIND 1ST VORT FEATURE WILL SHEAR ACROSS NORTHERN NEVADA BETWEEN 12Z-18Z WITH BEST 500MB DIFFERENTIAL VORTICITY ADVECTION. DEEPER LAYERED MOISTURE AND -12C 700MB COLD POOL SHOULD KEEP SNOW SHOWERS ACROSS THE NORTH INTO SUNDAY MORNING BEFORE MAIN RIDGING BEGINS. EVEN CONDITIONAL INSTABILITY SHOWING UP ALONG THE DROPPING BOUNDARY WILL AID SOME CONVECTION ON SATURDAY. WILL INCREASE POPS ALONG THE NORTHERN AND WESTERN ZONES FOR TONIGHT AND TIME INTO THE EAST OVERNIGHT. TEMPS LOOK TO REMAIN IN 30S SO SNOW LEVELS NO PROBLEM THROUGH SUNDAY. LONG TERM...MRF AND NOGAPS DO AGREE WITH EUROPEAN MODELS ON MEAN RIDGING WITH MRF AND NOGAPS MORE ROBUST ON THE RIDGE. TIMING DOES DIFFER INTO TUESDAY/WEDNESDAY WITH NEXT TROUGH SO WILL KEEP SOME SLIGHT CHANCE THROUGH THE PERIOD. SLA .EKO...NONE. nv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 916 PM CST FRI JAN 21 2000 THE RACE IS ON. TEMPS HAVE FALLEN INTO THE UPPER 20S ALONG PARTS OF THE TN RIVER WHERE THE WIND WAS CALM. ELSEWHERE TEMPS WERE IN THE LOW AND MID 30S. CLOUDS STREAMING ACROSS THE REGION ALONG WITH AN INCREASING SE SFC WIND WL KEEP TEMPS FROM FALLING MUCH FURTHER. A TREMENDOUS AMOUNT OF WAA/ISENTROPIC LIFT DEVELOPING ACROSS THE MID SOUTH BELOW 700MB BETWEEN 09Z-12Z. LOW LEVELS STILL VERY DRY SO EXPECT EVAPORATION TO DELAY ONSET SOME. CURRENT FORECAST IDEA OF LIGHT PRECIP ONSET AFT 10Z ACRS WRN SXNS LOOKS ON TRACK. 00Z RUC SHOWS NO REAL SURPRISES. AT FIRST GLANCE...THE 00Z ETA LOOKS VERY SIMILAR TO THE PREVIOUS RUN. WL MAKE MINOR COSMETIC CHANGES TO WORDING OF THE FIRST PERIOD AND ADJUST TEMPS ALONG THE TN RIVER A LITTLE DOWNWARD. .MEM...NONE. SJM tn AREA FORECAST DISCUSSION...CORRECTED FOR EXTRA WORDS NATIONAL WEATHER SERVICE NASHVILLE TN 838 PM CST FRI JAN 21 2000 WELL...WINTER WEATHER FORECASTING QUANDARY. LATEST SURFACE ANALYSIS HAS SURFACE HIGH STRETCHED FROM LEX-HSV-ANB. SURFACE TEMPS ARE IN THE LOW 30S IN WRN TN...MID 20S IN MIDDLE TN...AND IN THE 15 TO 20 DEGREE RANGE ON THE PLATEAU. OBVIOUSLY THE ARCTIC AIR IS STILL ENTRENCHED. LARGE CI/CS SHIELD ENCROACHING ON WRN CWA...AND WILL BE STABILIZING TEMPS FROM WEST TO EAST...WITH THE PLATEAU NOT GETTING THE SHIELD TO AROUND 06Z. THUS THERE TEMPS WILL LIKELY BOTTOM OUT IN THE MID TEENS. BNA SOUNDING WAS BONE DRY AND COLD AT 00Z...BUT BOTH BHM AND JAN HAVE THE NOSE OF WARM LAYER OFF THE SURFACE WITH JAN MORE IMPRESSIVE... EVEN THOUGH THEY WERE ABOVE ZERO ON THE SFC. BHM STILL HAS N-NE WINDS ON THE SFC WITH SW FLOW AROUND H8 AT JAN. FREEZING RAIN ON MY MIND...AND OLD HPC 94S STILL LOOKS REASONABLE FOR ICE FOR AREA N AND E OF BNA. WAITING FOR THE NEW ETA RUN...LATEST RUC...NEW 94S AND 9 PM OBS...TO MAKE A DECISION. WITH THE SURFACE LOW OVER THE OK PANHANDLE... PRECIP WILL TAKE SOME TIME TO GET HERE...BUT WITH ARCTIC AIR ENTRENCHED IN THE ENE AREAS...AND A NOSE OF STRONG H8 MOISTURE CONVERGENCE...WSFO STL SCHROEDER RULE IN AFFECT SATURDAY...BELIEVE EVAPORATIVE COOLING WILL HAVE NO PROBLEM SQUEEZING OUT MORE THAN THE 0.25 INCHES OF QPF ADVERTISED BY OLD ETA. NEW PRECIPITABLE WATER PLOT HAS .42 INCHES AT JAN WITH ONLY .20 INCHES AT BNA. AM LEANING TOWARDS UPGRADING 2ND PERIOD ADVISORY TO A 2ND PERIOD WINTER STORM WATCH (MAINLY BECAUSE OF ICE CONCERNS) FOR AREAS FROM DAVIDSON COUNTY TO CUMBERLAND COUNTY AND THEN UP TO PICKETT COUNTY. WILL MAKE THE DECISION BY 930 PM. A 05Z BNA RAWINSONDE WILL BE SENT UP...SO THE MID SHIFT SHOULD HAVE IT AROUND 1215-1230 AM. .BNA...WINTER WEATHER ADVISORY FOR NORTHERN MIDDLE TENNESSEE AND THE NORTHERN CUMBERLAND PLATEAU TOMORROW. JDG tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 339 AM EST SAT JAN 22 2000 LATEST SATELLITE IMAGE SHOWS HIGH CLOUDS QUICKLY SHIFTING EAST THROUGH THE OHIO VALLEY. FOLLOWING BEHIND THIS AREA OF HIGH CLOUDS SLEET AND FREEZING DRIZZLE HAS FORMED OVER CENTRAL MO. THIS AREA OF PRECIPITATION WILL QUICKLY SLIDE EAST TO THE CWFA DURING THE MORNING. IT APPEARS THIS AIR MASS IS SATURATING UP FAIRLY QUICKLY WITH CIGS ALREADY AT 8KFT AT PAH. UPPER LEVEL SHORTWAVE ASSOCIATED WITH THESE CLOUDS WILL CONTINUE TO SHEAR OUT AS IT HEADS EAST. RUC DEPICTS A STRAIGHT JET STREAK PATTERN IN OK WITH THE PRECIPITATION TRYING TO GET GOING ON THE LEFT EXIT REGION IN MO. MEANWHILE...THERE IS A SECONDARY ANTICYCLONICALLY CURVED JET IN OH WITH THE RIGHT ENTRANCE REGION PRODUCING SOME DIVERGENCE OVER THE OHIO VALLEY AT THE PRESENT TIME. THIS JET STREAK IN ADDITION TO THE ONE STREAKING THROUGH THE OK WILL HELP ENHANCE THE ISENTROPIC LIFT OVER THE REGION THIS AFTERNOON. RUC IS ALREADY PICKING UP ON A 50KT LLJ IN OK WHICH IS HELPING PRODUCE GOOD ISENTROPIC LIFT IN AR AND OK WHICH IS DEPICTED WELL ON THE IR SATELLITE LOOP. FOR TODAY ALL THREE MODELS ON THE 295K LEVEL SHOW THIS AREA OF ISENTROPIC LIFT SHIFTING EAST TO THE LOWER OHIO AND TENNESSEE VALLEYS. MODEL SOUNDING AND ACARS DATA SHOW THAT THE AIR MASS WILL INITIALLY START OUT AS SNOW ESPECIALLY AS THINGS START SATURATING UP. WOULD EXPECT MOST OF SNOW TO OCCUR IN NORTHERN KY AND SOUTHERN INDIANA DUE TO A COLDER AIR MASS IN PLACE AT THE LOW LEVELS. FURTHER SOUTH THE AIR IS NOT QUITE AS COLD...THUS THEY COULD HAVE A THREAT OF MIXED PRECIPITATION DURING THE AFTERNOON. WE ALSO FOLLOWED FAIRLY CLOSE TO THE ETA SOLUTION IN WARMING THE 800-900MB LAYER THIS AFTERNOON. THIS COULD CAUSE A MIXTURE OF PRECIP TO DEVELOP OVER SOUTHERN KY LATE THIS AFTERNOON. ALTHOUGH THIS MIXTURE SHOULD GRADUALLY TURN TO ALL RAIN BEFORE ENDING EARLY THIS EVENING. MODEL QPF'S SHOW ABOUT A QUARTER TO ONE HALF INCH OVER THE CWA WITH THE HIGHEST AMOUNTS FURTHERN SOUTH. FOR NOW WE WILL MENTION 1 TO 3 INCH SNOW AMOUNTS IN SOUTHERN KY DUE TO A MIXTURE DEVELOPING LATE IN THE DAY TO AROUND 3 INCES OF SNOW NORTH. WE UNDERCUT FWC A COUPLE OF DEGREES TODAY DUE TO CURRENT TREND AND THE AMOUNT OF ADIABATIC COOLING THAT WILL BE TAKING PLACE. TONIGHT THIS PRECIPITATION SHOULD END FAIRLY QUICKLY AS THE COLD FRONT ALOFT PASSES THROUGH BEFORE SURFACE TROF. THUS...TEMPERATURES WILL NOT FALL TO MUCH TONIGHT DUE TO WEAK WARM AIR ADVECTION IN PLACE. THERE COULD BE SOME DRIZZLE MIXED IN WITH THE FLURRIES AS MOISTURE COLUMN GRADUALLY BEGINS TO DRY OUT. WE FOLLOWED FAIRLY CLOSE TO FWC NUMBERS FOR THIS TREND. SUNDAY WE WILL SEE CLOUDS BEGINNING TO DECREASE SOME FROM WEST TO EAST AS THE DRY WEST FLOW KICKS IN AND SURFACE HIGH BUILDS IN FROM THE CENTRAL PLAINS. .SDF...WINTER WEATHER ADVISORY SOUTH CENTRAL KENTUCKY...SNOW ADVISORY NORTHERN KENTUCKY AND SOUTHERN INDIANA. COX ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 137 AM CST SAT JAN 22 2000 06Z SFC MAP SHOWED WK SRLY FLOW ACROSS THE FA...WITH A LOW OVER WRN OK. DEW POINTS WERE STILL IN THE TEENS. LAPS SOUNDINGS STILL SHOW VERY DRY AIR BELOW 750MB...AND NO PRECIP YET. NOT TOO FAR AWAY THOUGH...AS KPAH 88D SHOWS RETURNS ARE BEGINNING TO INCREASE JUST WEST AND SOUTHWEST OF SE MO. REGIONAL MOSAIC SHOWS BROAD AREA OF PRECIP DVLPG ON NOSE OF 50KT 850MB JET PUNCHING OUT OF OKLAHOMA...AND AIDED BY S/WV MOVG OUT OF THE CENTRAL PLAINS. MAIN FCST ISSUE IS OBVIOUSLY WINTRY PRECIP EVENT FCST FOR THE AREA. FAVOR THE NGM/AVN MODELS OVERALL. SPEED OF SYSTEM MAY BE MORE SIMILAR TO THE ETA...BUT THE ETA MODEL SEEMS TOO COOL WITH ITS THERMAL FCST FIELDS. EXPECT DIABATIC PROCESSES THIS MORNING TO RESULT IN LIGHT SNOW OR SLEET PRECIP TYPE DVLPG ACROSS SE MO...AND SPREADING EAST OVER SRN IL AND WRN KY...REACHING SW IN BY MID MORNING. SFC/925MB WET BULB TEMPS STILL BELOW ZERO PER LATEST LAPS/RUC DATA. AS THE LOW-LVL JET SHIFTS EAST...EXPECT WAA TO TAKE OVER THE DIABATIC PROCESS AND CHANGE THE PRECIP TO RAIN IN SRN SECTIONS OF THE FA. MEANWHILE...COLD AIR SHOULD HOLD IN SE IL...SW IN AND ADJACENT WRN KY COUNTIES TODAY...WITH PRIMARILY SNOW EXPECTED. SNOWFALL FORECAST TECHNIQUES SUGGEST 1 TO AT MOST 3 INCHES IN THIS AREA. SHOULDN'T BE ANYMORE THAN THAT DUE TO FAST NATURE OF THE SYSTEM...LACK OF A WELL DEFINED SFC LOW...OPEN WAVE AT 850MB AND WK MID-LVL FORCING. REST OF THE FA...WILL WORD ACCUMULATION LESS THAN 1 INCH...AS PRECIP INITIALLY SHOULD BE LIGHT...THEN CHANGE OVER TO LIQUID. WILL COMPROMISE ON GUIDANCE NOS FOR TODAY. SYSTEM DEPARTS RAPIDLY THIS EVENING...WITH LARGE SCALE DRYING TAKING PLACE FROM WEST TO EAST. SO OTHER THAN AN EARLY EVENING WORDING FOR MAINLY EAST SECTIONS...WILL GO DRY FOR REST OF THE NIGHT. CLOUDS MAY DECREASE WRN SECTIONS AND NORTHERN SECTIONS LATE AND MAY REFLECT IN ZFP. NEXT UPPER TROF ROTATES ACROSS THE GREAT LAKES AND UPPER MIDWEST ON SUNDAY. MID-HIGH LVL MSTR STILL FAIRLY PROMINENT...SO WILL NOT DEVIATE FROM CURRENT ZFP CONSIDERABLE CLOUD FORECAST. WILL CONTINUE TO FOLLOW GUIDANCE NOS...AND THEY ARE IN LINE WITH GOING ZFP. .PAH...WINTER WEATHER ADVISORY TODAY NORTH OF A LINE FROM MOUNT VERNON ILLINOIS TO CALHOUN KENTUCKY. NOLES/ YORK ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 230 AM CST SAT JAN 22 2000 FORECAST FOCUS IS SNOW CHANCES. MERGING PATTERN OVER THE CENTRAL U.S. STRONG W-E JET WITH ANOTHER BRANCH DROPPING SE FROM THE CENTRAL PROVINCES AND THEN TURNS E ALG THE CANADIAN BORDER. A COUPLE OF VORT CENTERS WILL BE THE KEY TO THIS FCST CYCLE. THE FIRST IS MOVING ESE ACROSS THE NRN QTR OF MN. THE DLH 88D IMAGERY HAS GRADUALLY FILLED IN AS LOWER DRY LAYER IS OVERCOME BY THE PCPN. THE VORT WEAKENS AS IT MOVES THRU NRN MN DUE TO THE SHEAR OF THE CNTRL U.S. JET. ALSO, FGF 88D SEEMS TO INDICATE THAT PCPN SHUTS OFF CLOSE TO THE VORT CENTER/AXIS AS IT APCHS MN. THE JET SPEEDS E AND THE SECOND JET AND VORT MAX IN SRN CATCHES UP BY MIDDAY. SNOW IS GENLY LIGHT WITH 2-5 MI VSBYS REPORTED. CURRENT FCST FOR MRNG SNOW OF ABOUT AN INCH SHOULD DO IT. A LITTLE MORE SHOULD FALL NR THE CANADIAN BORDER WHERE PVA PERSISTS. BUT WEAKENING PVA SHOULD NOT BE CAUSE FOR CONCERN. RUC HAS A GOOD INITIAL HANDLE ON SPEED AND PSN OF SYSTEMS, AND THE ETA MATCHES THAT GOOD PERFORMANCE IN MOST FIELDS. SO WE FEEL CONFIDENT WITH IT AS THE MAIN GUIDE FOR OUR THOUGHTS. THE DIFFERENCES THAT DO APPEAR ARE IN THE ISENTROPIC FIELDS. ETA IS MORE MOIST WITH LOW CONDENSATION PRESSURE DEFICITS AND A BROADER PCPN FIELD. 1-2 INCHES ALG THE CANADIAN BORDER LOOKS GOOD WITH ARND AN INCH IN SRN MN CWA. NRN WI WILL GET A GLANCING BLOW AS THE MAIN PVA GOES OVR LK SUPR AND SOUTH WINDS PREVAIL. THAT SCENARIO DOES CAUSE US TO FOCUS ON THE MN ARROWHEAD HIER TERRAIN WHICH COULD PRODUCE A COUPLE OF INCHES THERE FOR TDA. LATER TDA AND TNGT...COLD AIR AND SINKING FILL IN BEHIND THE PASSING SFC LOW AND THAT SETS UP ISENTROPIC DOWNGLIDE OVER SRN PTNS OF THE CWA BUT PERSISTENCE FLURRIES ACROSS THE NRN MN PTNS AS THE SECOND VORT MAX MOVES THROUGH. THIS SECOND VORT MAX IS PRETTY TOOTHLESS BRINGING IN PERHAPS SOME INSTABILITY BUT NO REAL WAA AHEAD OF IT. .DLH...NONE. CS mn SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 830 PM MST FRI JAN 21 2000 ...UPDATES PLANNED FOR ZONES AND STATE... WILL UPDATE A LITTLE EARLY TONIGHT AS CHANGES NEAR CANADIAN BORDER AND FARTHER UPSTREAM SUGGEST CURRENT FORECAST NEEDS SOME AMENDING. WIND SHIFT TO THE N OCCURRED ABOUT 01Z AT CTB. STRONGER PRESSURE RISES AND COLDER AIR WERE MOVING S THROUGH CENTRAL ALTA AT 02Z. LIGHT SNOW STARTED AT CTB SHORTLY AFTER 02Z. 12Z MODEL RUNS WERE TOO SLOW WITH WIND SHIFT 18Z MESOETA AND 00Z RUC TEND TO BE BETTER BUT ARE STILL TOO SLOW WITH WIND SHIFT. SATELLITE IMAGERY AND OBSERVATIONS INDICATE A BAND OF SNOW WAS MOVING THROUGH SRN ALTA AT 02Z AND SHOULD REACH GTF/LWT AREA BEFORE 12Z. WILL BE RAISING POPS OVER THE PLAINS. CURRENT POPS MAY BE OK FOR MEASURABLE SNOW BUT NOT ENTIRELY CONFIDENT OF THIS. WILL ALSO ADD SOME SNOW ACCUMULATIONS. SINCE SYSTEM APPEARS RATHER WEAK DO NOT FORESEE AMOUNTS REACHING SNOW ADVISORY CRITERIA. TEMPERATURES BELOW 15 DEGREES WERE LIMITED TO NRN ALTA AND ALSO SASK EXCEPT FOR FAR SW. BASED ON THICKNESS TRENDS COLD AIR SHOULD MAY MAKE IT INTO N CENTRAL MT BY 12Z. SO WILL RAISE FORECAST LOWS AT CTB/LWT/GTF. LOW AT HVR MIGHT NEED LOWERING BUT WITH EXPECTED CLOUD COVER WILL LEAVE IT AS IS. SW FORECAST LOOKS IN GOOD SHAPE SO NO UPDATE EXPECTED THERE. BLANK GTF 5611 HLN 2521 HVR 6311 mt AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 950 PM CST FRI JAN 21 2000 UPDATED ZONE FORECASTS WERE SENT A BIT EARLIER. RADAR AND MTR OBSERVATIONS SHOW LIGHT RAIN TO THE WEST...MOVING EAST. 00Z OAX SOUNDING WAS INTERESTING WITH A WARM LAYER ALOFT. TEMPERATURES AT THE SFC HAVE NOT DROPPED TOO MUCH ACROSS ECNTRL AND SERN NE... INTO SWRN IA. DECENT SHORTWAVE IS MOVING THROUGH...AND OUTPUT FROM 00Z ETA DOES GENERATE MEASURABLE PCPN OVERNIGHT. PCPN TYPE SOMEWHAT OF A QUESTION...AND SINCE PCPN LOOKS RATHER CONVECTIVE ...HAVE GONE WITH RAIN OR SNOW SHOWERS. TO THE NORTH...PCPN MAY BE MAINLY FLURRIES...BUT THE AREA FROM ABOUT OFK EAST COULD HAVE A BRIEF PERIOD OF FREEZING RAIN IF SFC TEMPS ARE LOW ENOUGH. ALSO...BASED ON THE LATEST OUTPUT FROM THE RUC MODEL...WENT AHEAD AND RAISED LOW TEMPS FOR MOST AREAS OVERNIGHT. .OMA...NONE MILLER ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 938 AM EST SAT JAN 22 2000 VSBL STLT INDICATES VARYING AMOUNTS OF MID/HIGH CLOUDS STREAMING E OVER THE CWFA THIS MORNING WITH THICKER ALTOCUMULUS MOVING RAPIDLY INTO CENTRAL GEORGIA. INCREASING CLOUDS/MOSTLY CLOUDY ON TARGET FOR THIS AFTN WITH COOL TEMPERATURES LIKELY TO ONLY REACH THE MID OR UPPER 40S MANY AREAS. SHORT RANGE MODELS INDICATE GRADUAL DEVELOPMENT OF COASTAL TROF/WARM FRONT COMBO LATER TDA...BUT WITH STRONG SFC WEDGE IN PLACE...PLAN TO LOWER MAXIMUM TEMPS (ESECIALLY INLAND) A CATEGORY TO COMPENSATE. 12Z REGIONAL RAOBS INDICATE VERY DRY AIR BLO H7 EVEN BACK TO KFFC...EXPECTING PRECIP TO REMAIN ALF THIS AFTN. CWF...WINDS CURRENTLY RATHER LIGHT AND VARIABLE AT THE BUOYS. PILOT BOAT REPORT OF NE 12 TO 15 KT AND 2 FT SEAS AT 9AM. EXPECT COASTAL TROF OFF OF FL TO DEVELOP FRTHR N THIS AFTN WHICH SHOULD KEEP WINDS ON THE SC WATERS NE THIS AFTN. WILL GO WITH N WINDS BECOMING VARIABLE OVER THE GA WATERS DUE TO UNCERTAINTY IN FINAL LOCATION OF COASTAL TROF PARTICULARLY IF RUC AND MESOETA ARE TOO QUICK TO DEVELOP THIS FEATURE. SEAS EXPECTED TO CHANGE LITTLE THIS AFTN. .CHS... SC...NONE. GA...NONE. RVT/SLF sc AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 955 AM CST SAT JAN 22 2000 MAIN CONCERNS FOR TODAY WITH CLOUDS AND WINDS. SAT LOOPS SHOW CLOUDS GENERALLY SPREADING SOUTH AND EAST ACROSS CWA. UPDATED ZONES TO MAKE SLIGHT ADJUSTMENTS UPWARD ON WINDS AND SLIGHTLY DOWNWARD ON TEMPS. 15Z SFC ANALYSIS SHOWS LOW ALONG CAN/MN BORDER AND ASSOCIATED TROUGH/CD FNT EXTENDING SW INTO N CNTL AND NW SD. WINDS BEHIND FRONT PICKING UP PRETTY GOOD OVER ND...WITH W/GUSTS UP TO 36 KTS NOTED AT GARRISON ND...IN AREA OF BEST CAA. AFTER LOOKING AT RUC TEMP AND WIND PROGS...LATEST FLP...AND LAST NIGHT'S MOS GUIDANCE...DROPPED TEMPS A BIT MOST AREAS WITH CD FNT DROPPING SOUTH. SW COUNTIES WILL LIKELY SEE LEAST EFFECTS OF CD FNT. ALSO HAVE SEEN OCCASIONAL REPORTS OF -SN UPSTREAM...AND ABR 88D NOW SHOWING SOME LIGHT RETURNS MOVING S ACROSS ND/SD BORDER...SO HAVE CONTINUED MENTION OF FLURRIES WITH CLOUDS MOVING IN...MAINLY N AND E COUNTIES. .ABR...NONE. LORENS sd COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 322 AM CST SAT JAN 22 2000 CDFNT/PREFNTL TROF WILL DRAW CLOSER THRU SUN. ETA X-SCTNS RATHER DRY WITH LLVL POS OMEGA/MSTR CONVG SUN AFTN. NGM X-SCTNS RETAIN LLVL MSTR E CWA TDY THEN DRY WITH WEAKER LLVL MSTR CONVG SUN. AVN X-SCTNS ALSO DRY WITH LLVL MSTR CONVG SUN. 07Z RUC X-SCTNS SHOW LLVL MSTR E CWA THRU 18Z TDY. ETA/NGM PWATS SLOWLY INCREASING WITH 85H THETAE RIDGE SUN AFTN. ETA ALSO SHOWS 85H CONVG SUN. UNFAVORABLE RFQ OF 25H/50H JETMAX APPROACHES SUN. CI FROM THESE FEATURES WILL NOT MAKE A SERIOUS IMPACT TO CLOUD COVER. THEREFORE WILL GO PC DAY MCLR NGT EAST AND MSUNNY DAY MCLR NGT WEST. ETA SOUNDINGS INDICATE STRONG RADIATION INVERSION THIS MORNING AND ESPECIALLY SUN MORNING WITH VERY SHALLOW MSTR OVERLAIN WITH DRY AIR. THIS WILL SUPPORT FOG. WND SPEEDS OF 15-20 MPH AND GUSTY E CWA TDY DUE TO DEPARTING LLVL JET AND STRENGTH OF SEABREEZE DUE TO STRONG THERMAL HEATING. WITH 85H TEMPS SVRL DEGREES WARMER AND 1000-850MB THICKNESSES MUCH HIGHER INLAND TEMPS SHUD BE IN THE 80S. SUN WILL BE EVEN WARMER THAN TDY AS MIXING LYR WILL BE DEEPER(NRLY 800MB) AND W HALF OF CWA WILL HAVE A DOWNSLOPING W WND BEHIND PREFNTL TROF. WILL GO ABV GUIDANCE IN MOST INSTANCES FOR MAX TEMPS. WITH RATHER DRY COLUMN WILL FAVOR NGM MOS MINS. WEAKENING PGRAD SHUD ALLOW FOR CSTL SEABREEZES SAT/SUN. MARINE...WILL LOWER WINDS A TAD TONIGHT AS SURFACE TROF APPROACHES. STILL EXPECT SCA FOR SEAS OFFSHORE AT LEAST FOR THE MORNING. ETA INDICATES SOME INSTABILITY IN THE GULF...BUT WITH LIMITED MOISTURE AND LOTS OF CIN DO NOT EXPECT ANY RAINFALL. EXTENDED: MODEL SOLUTIONS ARE SIMILAR TO PREVIOUS RUNS. SO WILL TINKER VERY LITTLE WITH OUR CURRENTLY ADVERTISED FCST. PRELIMINARY NUMBERS: CRP BB 083/058 085/058 070 -0- VCT BB 080/055 082/055 066 -0- LRD AA 084/056 087/056 072 000 .CRP...SCA OFFSHORE WATERS THIS MORNING FOR SEAS. (SYN)...85/BB (MESO)...86/GW tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 244 PM EST SAT JAN 22 2000 CURRENTLY...LATEST SURFACE ANALYSIS SHOWS RIDGE ACROSS THE EASTERN PART OF THE COUNTRY BEGINNING TO PUSH OFFSHORE WITH GENERALLY LIGHT SELY FLOW ACROSS THE AREA. SURFACE WARM FRONT...PER ISOBAR... ISOTERM...AND WIND FIELD ANALYSIS...IS ALSO EVIDENT FROM NORTHERN TX AND INTO SOUTHERN AK...N CNTRL MS...N AL...N CNTRL GA...AND OFF THE SC COAST. AT THE UPR LVLS...MOSTLY ZONAL FLOW DOMINATES MUCH OF THE COUNTRY WITH OUTSTANDING FEATURE BEING UPR LVL JET ASSOCIATED WITH SUBTROPICAL JET ACROSS THE SOUTHERN SECTION OF THE US. 12Z UPR AIR DATA AND RUC ANALYSIS SHOWED THE AXIS ACROSS THE CAROLINAS... TN..AND S AK. ANOTHER JET STREAK IS ALSO EVIDENT TO BE MOVG INTO THE SW ATTM. MODELS...IN GENERAL...I THINK ETA INITIALIZED BETTER ESPECIALLY THE SURFACE FEATURES. IN TERMS OF THE EVOLUTION IN THE ATMOSPHERIC FLOW...ALL SHOW A SIMILAR PICTURE. SO ALTHOUGH I WILL LEAN MORE TOWARD THE ETA I WILL STILL USE AN ENSEMBLE OF ALL THEM. AND THAT IS S/W DROPPING FROM CANADA ACROSS THE PLAINS WITH TROUGH AMPLIFYING ACROSS THE EASTERN PART OF THE COUNTRY TOMORROW AFTERNOON AND NIGHT. ALONG WITH THAT...SFC LOW CURRENTLY ACROSS NORTHERN TX MOVES EAST ALONG WARM FRONT WITH TRAILING COLD FRONT ACROSS SOUTHERN AL AND MS AND OFF THE TX COAST BY TOMORROW AFTN. BUT PERHAPS MORE SIGNIFICANT IS THAT AT THE UPR LVLS WE WILL HAVE CURRENT JET ACROSS THE SE SHIFTING TOWARD THE NE AHEAD OF AMPLIFYING TROUGH WITH SECONDARY JET MAX DIGGING SE INTO TX AND NW GULF. IN RESPONSE TO THIS UPR LVL FORCING...SFC LOW DEVELOPS OFF THE MID ATLANTIC STATES COAST TOMORROW AFTN AND THEN LIFTS NE SUNDAY NIGHT WITH TRAILING COLD FRONT MOVG ACROSS THE AREA FROM TOMORROW NIGHT INTO MONDAY MORNING. ISENTROPIC ANALYSIS SHOWS GOOD FOCUS OF MSTR FLUX CONVERGENCE ALONG THE FRONT WITH DECENT UPR LVL SUPPORT ASSOCIATED WITH SECONDARY JET SUNDAY NIGHT AND MONDAY MORNING. FORECAST...ALL THE ABOVE SAID... THIS IS PROBABLY THE BEST CHC OF RAIN WE HAVE HAD IN QUITE A WHILE. I WILL PUT POPS IN THE CHC CATEGORY IN SE GA AND EXTREME NE FL WITH SLIGHT CHC ELSEWHERE ON SUNDAY. THEM I WILL INCREASE POPS TO LIKELY RANGE SUNDAY NIGHT AND MONDAY MORNING DECREASING LATE ON MONDAY. TEMP WISE...I WILL LEAN MORE TOWARD THE AVN/FMR FOR THIS PACKAGE. WITH CLOUDY CONDITIONS FROM TOMORROW NIGHT TO MONDAY AND FRONT MOVG THROUGH...I FIND IT HARD TO BELIEVE TEMPS WILL GET INTO THE 60S AS ADVERTISED BY FWC ON MONDAY. CWF...GIVEN THE SCENARIO ABOVE...I WILL MAINTAIN TREND IN CURRENT MARINE PACKAGE WITH AT LEAST SCEC CONDITIONS FOR SUNDAY INCREASING TO SCA CONDITIONS BY THE AFTN. MEDIUM RANGE...TUESDAY THROUGH THURSDAY...DRY WITH ANOTHER STRONG S/W TROUGH MOVG TROUGH AT THE UPR LVLS AND THUS IT WILL BE MUCH COLDER THAN NORMAL THROUGH THE PD. THICKNESSES BELOW 5400 M BEHIND TROUGH. ANOTHER STRONG LOW DEVELOPS OFFSHORE THE MID ATLANTIC STATES ON WEDNESDAY AHEAD OF UPR LVL TROUGH BUT LOOK LIKES ANY WRAP AROUND MSTR WILL BE FAR ENOUGH NORTH TO BRING ANY PCPN INTO THE FCST. PRELIM AMG 43/65/47/54 0474 SSI 45/64/49/56 0474 JAX 44/70/53/55 0365 GNV 39/74/54/56 0255 18 .JAX... GA...RED FLAG WARNING ALL AREAS THIS AFTN. FL...RED FLAG WARNING ALL AREAS THIS AFTN. SANTOS fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 945 AM EST SAT JAN 22 2000 CURRENTLY...COLD START TO THE DAY AS SOME INTERIOR AG SITES BOTTOMED OUT IN TH U20S-L30S..WITH MOST AIRPORT STATIONS M-U30S EVEN AS FAR SOUTH AS FPR. SATELLITE ANIMATION SHOWS A FEW CI STREAMERS BRUSHING NORTH FL ATTM WITH THICKER AC/AS/CS STAYING WELL TO THE NW. MARINE STRATO-CU CONFINED TO THE GULF STREAM...AND NOT ALL THAT EXTENSIVE ATTM. LOOKING AT 12Z RAOBS...EXTRAPOLATED H85 TEMP AT XMR SUPPORTS A FULL SUN MAX OF 68-70F TODAY...SO ADDING/SUBTRACTING A FEW DEGREES TO ACCOUNT FOR TEMPS TO THE SOUTH/NORTH PUTS IT RIGHT IN LINE WITH THE CURRENT PUBLIC FORECAST. NIL FLOW TODAY WILL BECOME LIGHT SE... ON THE ORDER OF ABOUT 5-7KTS. THERE MAY BE A FEW SHREDS OF STRATO-CU AT BEST THIS AFTERNOON AS TEMPS APPROACH MAXES AND SHALLOW MOISTURE GETS DRAWN NORTHWARD ACROSS THE STATE. HIGHER CLOUDS SHOULD STAY NORTH OF OUR CWA. FORECAST LOOKS FINE AND ASIDE FROM A HALF CAT TEMP TWEAK...SEE NO NEED FOR CHANGES. MARINE...WINDS AOB 5KT WILL COME AROUND TO SE TODAY. WILL TWEAK DIRECTION ON FORECAST...AND MAY TACK ON A FOOT TO COMBINED SEAS IN ORDER TO ACCOUNT FOR SMALL SWELL. FIRE WX...DRIER AIR ALOFT WILL MIX DOWN TO THE SURFACE BY NOON. WEAK ONSHORE FLOW IS DEVELOPING BUT MOISTURE RETURN WILL BE VERY SLOW... ESPECIALLY NORTHERN SECTIONS. 12Z RUC SHOWS VERY LOW RH VALUES (15-20%) SPREADING DOWN THE INTERIOR/WESTERN PENINSULA DURING THE DAY. WHILE THE MAGNITUDE IS LIKELY OVERDONE...LIKE THE TREND AND PLACEMENT. WILL WATCH OBS BUT AM THINKING RED FLAG WARNING WILL BE NECESSARY THIS AFTERNOON OVER NORTHERN INTERIOR SECTIONS FOR LOW RH DURATIONS. .MLB...FIRE WEATHER WATCH THIS AFTERNOON FOR LAKE...SEMINOLE... ORANGE AND INTERIOR VOLUSIA COUNTIES. CRISTALDI fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 230 PM EST SAT JAN 22 2000 ...A SLGHT CHNC OF FREEZING RAIN IN FAR NW CWA POSSIBLE TONIGHT...OTHERWISE RAIN ELSEWHERE ACRS THE CWA THRU SUN NIGHT... MODELS SIMILAR THRU 30 HRS WITH ETA FASTER TO FINISH. ETA STILL MODEL OF CHOICE AS NGM/AVN HAVING SOME DIFFICULT WITH SFC FEATURES. ALL MODELS BRING PCPN THRU SUN NIGHT WITH DEVELOPMENT OF NOREASTER OF THE CAPE. UPPER S/W EARLY NEXT WEEK SHOULD KEEP A PROGRESSIVE AND WET FORECAST GOING. FOR TONIGHT...STILL OPTIMISTIC THAT SFC TEMPS/WETBULB0 WILL REMAIN ABOVE 32F FOR ALMOST ALL CFWA. EXCEPTION BEING THE FAR NW COUNTIES.. SPECIFICALLY DARLINGTON...MARLBORO...DILLON...ROBESON AND BLADEN COUNTIES. ETA IS ONLY MODEL TO LOWER SFC TEMPS LOW ENOUGH TO ALLOW RAIN TO FREEZE. HOWEVER...THE LAYER IS SO PATHETICALLY THIN THAT ANY RAIN FALLING THRU THE 40 TO 45 DEGREE H95-H90 LAYER SHOULD ALLOW LITTLE IF ANY RAIN TO FREEZE. NGM A BIT COOLER IN THIS LAYER...BUT WARMER AT SFC. THIS WOULD RESULT IN A FEW FLAKES OF SNOW MIXED IN WITH THE RAIN. BUT ETA HAS BEST HANDLE ON SFC TEMPS ATTM. INVERTED SOUNDING WITH DRY LAYER BLW H70. CURRENTLY VERY DRY AT SFC WITH AREA DWPTS IN THE SINGLE DIGITS. LAYER SHOULD BECOME MORE SATURATED AFTER MIDNIGHT. WILL ISSUE SPS FOR POSSIBLE WINTRY MIX IN AFOREMENTIONED COUNTIES...WITH FREEZING RAIN THE MAIN THREAT. WAA ON SUNDAY WILL KEEP PCPN IN FORM OF RAIN THRU SUNDAY NIGHT. WILL GO WITH LIKELY POPS OVERNIGHT...OCCASIONAL RAIN ON SUNDAY...AND LIKELY SUNDAY NIGHT FOR COASTAL COUNTIES...50% INLAND. WET AND COOL TREND TO CONTINUE AS INTO FIRST HALF ON NEXT WEEK. GENERALLY WILL FOLLOW COOLER FAN GUID THRU PACKAGE. CWF: DIFFICULT TO DETERMINE INITIAL WND DIR AS IMSAS SHOWING DEVLPG LOW OFF SC COAST. WNDS AT EDISTO BUOY SE ARD 10 KT WHILE FRYING PAN IS NE AT 15 KT. RUC INITIALLY REPRESENTS WNDS FIELD THRU 06Z. AFTER WILL BLEND ETA AND NGM WND FIELDS WITH SCA CONDITIONS DEVLP ON SUN. ILM RC 037/050 042/049 026 35687 FLO RC 034/048 038/046 025 35685 MYR RC 036/051 041/047 026 35487 .ILM...NONE. JFP nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1035 AM CST SAT JAN 22 2000 15Z SURFACE ANALYSIS AND CURRENT MESONET DATA SHOWS COLD FRONT... ASSOCIATED WITH WEAK LOW PRESSURE OVER SOUTHEAST OKLAHOMA...HAS PUSHED THROUGH ALL BUT THE SOUTHEAST COUNTIES OF THE CWA. PESKY LOW CLOUDS HAVE BEEN HANGING AROUND ALL MORNING OVER FAR EASTERN COUNTIES. RUC RH FIELDS SUGGEST THAT LOWER CLOUDS WILL CONTINUE A SOUTHWARD DRIFT AFFECTING SOUTHCENTRAL AND SOUTHEAST ZONES MAINLY EAST OF I-35. CLOUDS SHOULD ERODE AROUND 18-19Z IN ARDMORE AREA BUT MAY NOT CLEAR TO AFTER 21Z ACROSS DURANT AND ATOKA LOCATIONS. LOWERED TEMPS SOME...AS COLD FRONT SHOULD KEEP TEMPERATURES FROM GETTING ABOVE HIGHS YESTERDAY IN MOST AREAS...AS MORNING ANALYSIS INDICATED FAIR AMOUNT OF LOW LEVEL CAA. .OUN... OK...NONE. TX...NONE. 6 ok