NORTHERN ARIZONA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 245 PM MST FRI DEC 14 2001 .SYNOPSIS...A STRONG PACIFIC STORM SYSTEM WILL BRING WIDESPREAD SNOW TO MUCH OF THE REGION TONIGHT AND SATURDAY. SNOW LEVELS WILL FALL TO AROUND 3000 FEET BY SATURDAY WITH THIS STORM. GUSTY SOUTHWEST WINDS WILL CONTINUE OVERNIGHT...BEFORE SWITCHING TO THE NORTH SATURDAY. VERY COLD AIR WILL ACCOMPANY THIS STORM SATURDAY...WITH WIND CHILLS IN THE SINGLE DIGITS. HIGH PRESSURE WILL REBUILD SUNDAY...WITH WARMER TEMPERATURES AND PARTLY CLOUDY SKIES EXPECTED MUCH OF THE COMING WEEK. .DISCUSSION...DEEP AND COLD TROUGH WITH ABUNDANT DYNAMICS AND LIMITED MOISTURE WILL MAKE ITS WAY ACROSS ARIZONA TONIGHT AND SATURDAY. CURRENT OBS AND RUC DATA INDICATE A SYSTEM A BIT DEEPER AND SLOWER THAN THE 12Z AVN...AND THIS SOLUTION IS PREFERRED. WILL EXTEND SNOW ADVISORIES INTO SATURDAY...AND WILL ADD A FEW MORE ZONES TO THE COVERAGE. WILL KEEP THE AMOUNTS THE SAME...AS MOISTURE LEVELS NOT VERY IMPRESSIVE WITH THIS STORM. SNOW LEVELS WILL PLUNGE TO 3500 FEET OVERNIGHT...PERHAPS EVEN LOWER. SNOW LEVELS WILL CONTINUE TO FALL TO 3000 FEET ON SATURDAY. WINDS WILL STAY OUT OF THE SOUTHWEST TONIGHT...AND WILL APPROACH 30 MPH AT TIMES. WINDS WILL SWITCH TO THE NORTH SATURDAY...WITH A SECONDARY FRONT AND VORTICITY MAXIMA MOVING OUT OF THE NORTH. THIS WILL LIKELY CONTINUE SNOW SHOWERS OVER MUCH OF AREA UNTIL LATE IN THE DAY. GUSTY NORTH TO NORTHEAST WINDS WILL PERSIST INTO SUNDAY...BUT STRONG SUBSIDENCE WILL DRY OUT THE AIRMASS AS A RIDGE BUILDS INTO THE SOUTHWEST. THIS RIDGE TO LAST INTO THE EXTENDED PERIOD...WITH A FEW WEAKER SYSTEMS PASSING TO THE NORTH. WILL STICK WITH FAIR SKIES...AND NORMAL TO ABOVE NORMAL TEMPERATURES FOR MUCH OF NEXT WEEK. PETERSON. .FGZ...SNOW ADVISORY TONIGHT ZONES 4/5/6/7/8/37/38 SNOW ADVISORY TONIGHT THROUGH NOON SATURDAY ZONES 15/16/18 SNOW ADVISORY MIDNIGHT TONIGHT THROUGH NOON SATURDAY ZONES 10/11/17/39. .CODED TEMPERATURES/POPS FOR SELECTED CITIES IN NORTHERN ARIZONA CITY TEMPERATURES LO/HI PROBABILITY OF PRECIP TON SAT SUN MON TON SAT SUN MON FLAGSTAFF 021/027 015/034 002/043 100 080 020 000 000 000 WINSLOW 027/038 019/040 014/049 050 050 020 000 000 000 PRESCOTT 026/036 018/045 015/054 090 050 000 000 000 000 PAGE 030/036 024/038 021/047 080 040 000 000 000 000 WINDOW ROCK 018/027 005/032 004/041 090 080 030 000 000 000 --------------------------------------------------------------------- TEMPERATURES LO/HI TON SAT SUN MON CANYON DE CHELLY 024/026 011/031 010/040 COTTONWOOD 031/043 023/052 020/061 GRAND CANYON 023/031 017/038 004/047 GREER 021/028 015/035 002/044 HEBER 022/033 016/040 003/049 JACOB LAKE 022/024 016/031 003/040 NAVAJO N.M. 024/022 011/027 010/036 PAYSON 025/039 017/048 014/057 SEDONA 033/041 025/050 022/059 SELIGMAN 020/037 012/046 009/055 SHOW LOW 027/030 021/037 008/046 ST. JOHNS 025/039 017/041 012/050 WUPATKI N.M. 031/039 023/041 018/050 az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 925 AM PST FRI DEC 14 2001 UPDATED MORNING ZONES TO FRESHEN WORDING. LATEST RUC SHOWING DECREASING PRECIP OVER THE SIERRA NEVADA AS SYSTEM CONTINUES TO TRACK EAST SO HAVE ALLOWED WARNING TO EXPIRE. INCREASING SUBSIDENCE AND NW TO N FLOW OVER CWA TODAY AS SURFACE HIGH BUILDS INTO NORCAL. UPSTREAM BAROCLINIC CIRRUS APPROACHING WEST COAST AND PROGGED TO BEGIN INVADING THE CWA LATER TODAY. MODELS SPREAD SOME PRECIP NEAR THE NORTHERN BORDER TONIGHT WITH ASSOCIATED WARM FRONT AND POSSIBLY ACROSS NORTHERN PORTIONS OF CWA OVER THE WEEKEND. ANY PRECIP THAT OCCURS WILL BE LIGHT AS UPPER RIDGE...CURRENTLY NEAR 150W... PROGRESSES INLAND OVER THE WEST. CYCLOGENESIS ON SUNDAY BETWEEN 40N- 50N AND 130W-140W AS LONG WAVE CURRENTLY NEAR THE DATELINE PROGRESSES TO AROUND 145W. SURFACE LOW TRACKS INTO B.C. DRAGGING FRONT ACROSS NORCAL FOR EARLY NEXT WEEK. .STO...NONE. PCH ca INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 330 AM PST FRI DEC 14 2001 THIS MORNINGS WATER VAPOR AND RUC ANALYSIS HAS THE UPPER TROF AXIS OVER THE NORTH BAY AREA. CURRENT DOPPLER RADAR IMAGES SHOWS THE LEADING EDGE OF RAIN FROM SOUTH OF PASO ROBLES NORTHEAST TO MADERA WITH POSSIBLE LIGHT PRECIP EXTENDING TO FRESNO. SURFACE ANALYSIS SHOWS THE COLD FRONT CURRENTLY APPROACHING SFO AND TIMED TO HIT THE CWFA NEAR 5 AM. WITH THIS FAST MOVING SYSTEM...WILL CONTINUE TO EXPECT MORNING RAIN SPREADING SOUTH TO BAKERSFIELD AND DIMINISHING BY THE AFTERNOON HOURS. AS STATED ABOVE...THIS IS A FAST MOVING SYSTEM WITH THE COLD FRONT TIMED TO REACH THE KERN COUNTY MOUNTAINS BY 10 AM AND SPREAD INTO SOUTHERN CALIFORNIA BY 4 PM THIS LATE AFTERNOON. CURRENT RUC ANALYSIS HAS A +150KT JET DRIVING DOWN ON THE BACK SIDE OF THE TROF. THIS JET IS PROVIDING THE SUPPORT NEEDED TO PUSH THIS TROF ALONG AND IS TIMED TO DROP INTO CENTRAL CALIFORNIA BY MIDDAY TODAY. BEST DYNAMICS OVER THE SIERRA NEVADA THIS MORNING AND DIMINISHING TROUGH OUT THE DAY. WILL THEREFORE MAINTAIN THE CURRENT WINTER STORM WARNING ABOVE 5000 FEET WITH SNOW LEVELS AS LOW AS 3000 FEET. AFTER 10 AM...THE TROF AXIS WILL BE OVER THE SOUTHERN END OF THE CWFA WITH MUCH OF THE DISTRICT COMING INTO THE AREA OF NVA. AT THAT TIME...UPPER LEVEL FLOW WITH BE MORE ALIGN WITH THE KERN COUNTY MOUNTAINS. WILL NOT EXPECT WARNING CRITERIA SNOW AMOUNTS FOR THE KERN COUNTY MOUNTAINS BUT...WITH STRONG UP SLOPE FLOW...ISOLATED 2 TO 5 INCHES ARE POSSIBLE. SNOW LEVELS FOR THE KERN COUNTY MOUNTAINS WILL ALSO BE NEAR 4000 FEET TODAY. WILL ISSUE A WINTER WEATHER ADVISORY AS LIGHT SNOW AND WINDS WILL BE A FACTOR TODAY FOR TRAVEL OVER HWY 58 AND INTERSTATE 5. WITH THE TIMING THE JET MAX AND COLD FRONT TO REACH THE KERN AREA BY MIDDAY...WILL UPGRADE THE HIGH WIND WATCH TO A WARNING. CONDITIONS WILL LINE UP TO FOR VERY STRONG GRADIENT WINDS LATER TODAY AND EARLY EVENING BELOW THE PASSES OF THE KERN COUNTY DESERTS. THE FAST MOVING SYSTEM WILL ALLOW THE WINDS TO DIMINISH BY THIS EVENING AS THE BETTER SUPPORT FOR STRONG WINDS WILL MOVE EASTWARD AFTER SUNSET. BY SATURDAY MORNING...CLEARING WILL ALLOW THE COLD AIR THAT FILTERED INTO THE DISTRICT TODAY TO FORM FROST AROUND DAYBREAK. THESE CONDITIONS WILL PERSIST INTO THE LATER PERIODS OF SUNDAY AND MONDAY. LONGER RANGE MODELS INDICATE POSSIBLE UNSETTLED CONDITIONS BY TUESDAY AND CONTINUING THROUGH THURSDAY. MOLINA .HNX...WINTER STORM WARNING TODAY FOR THE SOUTHERN SIERRA NEVADA...FROM YOSEMITE TO THE KERN COUNTY LINE. ...WINTER WEATHER ADVISORY TODAY FOR THE KERN COUNTY MOUNTAINS. ...HIGH WIND WARNING TODAY FOR THE KERN COUNTY DESERTS. ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 850 PM EST FRI DEC 14 2001 PUBLIC FORECAST UPDATE: AT 00Z, THE FRONT EXTENDED FROM JUST W OF ABY SW TO JUST E OF PFN. THE BOUNDARY IS MAKING VERY SLOW EWD PROGRESS. SLOW ENOUGH IN FACT THAT WE MAY NEED TO WORRY ABOUT FOG ACROSS SOME OF OUR ERN ZONES FOR A PERIOD OF TIME TONIGHT. THE LATEST RUC KEEPS THE 65 DEG ISODROTHOTHERM W OF TLH THROUGH 12Z. THE 18Z ETA IS JUST A BIT FASTER. LOW CEILINGS HAVE ALREADY SET IN HERE AT TLH. WILL LIKELY RAISE MIN TEMP ACROSS OUR SE ZONES AS WELL. ISOLATED SHOWERS CONTINUE TO POP UP ALONG THE BOUNDARY IN SW GA. HOPEFULLY, WILL BE ABLE TO REMOVE ALL POPS AFTER 02Z. MARINE: NO MAJOR CHANGES PLANNED OTHER THAN REMOVAL OF SHOWERS. .TLH... .AL...NONE. .GA...NONE. .FL...NONE. WOOL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 930 PM EDT FRI DEC 14 2001 QUIET WEATHER PATTERN OVERNIGHT WITH HIGH PRES RIDGE OVERHEAD. MAIN FORECAST CONCERN FOR THE OVERNIGHT WILL BE THE EXTENT OF LOW CLDS AND TEMPERATURES. 00Z GRB SOUNDING SHOWS INVERSION AROUND 900MB...WITH PROFILE UNDER INVERSION SOMEWHAT MOIST. THIS ALONG WITH GENERALLY LIGHT WINDS CAUSING LOW CLDS TO DEVELOP ACROSS THE EAST AND NRN FA. WESTERN FA STAYING CLEAR DUE TO SLIGHTLY STRONGER WINDS ALOFT AND SOME POSSIBLE MIXING. RUC II SHOWS RH > 80 PERCENT AT 950>850MB OVER THE EASTERN AND NRN FA WHICH CORRESPOND WELL TO WHERE LOW CLDS ARE CURRENTLY. RUC REALLY DOES NOT MOVE OUT MUCH MOISTURE UNTIL LATE WHEN EASTERN AREA SEES STRONGER S-SWLY WINDS ON BACK SIDE OF THE HIGH. WILL THEREFORE GO MOSTLY CLOUDY WORDING FROM FROM L'ANSE AND EAST...AND KEEP WESTERN FA PTLY CLDY TO MOSTLY CLEAR. WILL ALSO BUMP UP MINS SEVERAL DEGREES FOR AREAS WITH CLDS. OTHERWISE...REMAINDER OF FCST LOOKS FINE SO NO OTHER CHANGES PLANNED. .MQT...NONE. MRD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT FRI DEC 14 2001 MAIN FCST CONCERNS SHIFT FROM CLOUDS/TEMPS TONIGHT/SAT TO PCPN TIMING/COVERAGE SAT NIGHT THROUGH SUNDAY. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE WRN CONUS AND RDGING TOWARD THE PLAINS WITH STRONGEST UPR LVL JET AND SHRTWV ENERGY WAS PROPAGATING TOWARD THE SRN CA/AZ. FARTHER EAST...A POTENT SHRTWV OVER NRN OHIO...PRODUCING SWATH OF SNOW OVER SRN LWR MI... WAS RIDING ENE ATOP PERSISTENT SE CONUS RDG. A MOISTURE STARVED SHRTWV UPSTREAM OVER NE MO WAS SUPPORTING ONLY A BAND OF CLOUDS. AT THE SFC...A WEAK RDG EXTENDED TOWARD UPR MI FROM HI PRES OVER ONTARIO. IR LOOP SHOWED EDGE OF ENHANCED CLD BAND FROM LWR MI STORM JUST BRUSHING SE PORTION OF CWA. VIS LOOP INDICATED PERSISTENT PATCH OF SC OVER CNTRL UPR MI AS LLVL MOISTURE REMAINED TRAPPED BLO 900 MB INVERSION. CLOUDS WERE THIN ENOUGH SO THAT CONTINUED SUBSIDENCE AND AFTERNOON MIXING HAS BROUGHT MORE SUNNY BREAKS. TONIGHT...AS THE RDG SLIDES TO THE EAST...EXPECT LLVL WAA ADVECTION AND LLVL ISENTROPIC LIFT TO INCREASE AFTER 06Z WITH POSSIBILITY OF SOME LO CLD FORMATION LATE. HOWEVER WITH UPSTREAM DEWPOINTS OVER WI ONLY IN THE LOWER TO MID 20S F...WIDESPREAD OVC NOT EXPECTED. LOW TEMPS AT OR SLIGHTLY ABV GUIDANCE LOOK REASONABLE WITH DECENT RADIATIONAL COOLING EXPECTED. SATURDAY...WHILE ETA SHOWS THIN MOIST LYR PERSISTING BLO 925 MB INVERSION...WL STILL MAINTAIN MORE OPTIMISTIC PTSUNNY WORDING...GIVEN VERY THIN NATURE OF ANY CLOUDS. INCREASED MIXING AND SOME DOWNSLOPE WITH INCREASING SOUTH WINDS MAY ALSO HELP SUPPRESS LO CLDS. ACCORDINGLY...KEPT TEMPS NEAR HIGHER MAV VALUES. SATURDAY NIGHT...LLVL MOISTURE SHOULD THICKEN WITH 45 KT LLVL JET DEVELOPING...PER ETA. ETA/AVN BOTH SHOW RELATIVELY DRY LYR ABV MOIST LLVL SO THAT ANY PCPN WOULD FALL AS -DZ OR -FZDZ. SINCE MDL TREND HAS BEEN TO SLOW PROGRESSION OF THE TROF FROM THE PLAINS...AND 18Z ETA HAS BACKED OFF A BIT ON THE MOISTENING...WL KEEP DRY FCST GOING. WAA SHOULD KEEP MOST TEMPS ABV FREEZING WITH SLOWLY RISING TEMPS AFTER DROP OFF DURING THE EVENING. SUNDAY INTO SUNDAY NIGHT...PLENTIFUL MOISTURE ADVECTION ALONG WITH MODERATE 700-300 QVECTOR CONVERGENCE WL BE ENOUGH TO KEEP LIKELY PCPN CHANCES. FCST SNDGS SHOW RELATIVELY DEEP WRM BNDRY LYR WITH 1000-850 THICKNESS REMAINING WELL ABV 1305M. WL NOT ADD TIMING FOR NOW GIVEN MDL INCONSISTENCY...BUT EXPECT RAIN MAY BE DELAYED TIL MAINLY AFTERNOON GIVEN SLOWING TREND. WHILE ETA/AVN SHOW LIFT AND 850-500 MOISTURE QUICKLY DEPARTING BY AROUND 21Z WEST AND 00Z CENTRAL...WL ALSO KEEP CHANCES INTO THE EVENING AND KEEP LIKELY WORDING FOR THE ERN CWA. MONDAY...LITTLE MOISTURE LEFTOVER ON MONDAY AS UKMET/AVN SUGGEST NRN STREAM TROF WILL BE EAST OF THE AREA AND SRN STREAM SYSTEM WL ALSO SLIDE EAST. BOTH...HOWEVER...SHOW A WEAK SHEARED SHRTWV THAT WOULD SLIDE INTO THE WRN LAKES FROM THE NW AND MAY PRODUCE A FEW FLURRIES. DAYS 4-7...WHILE RUN TO RUN CONSISTENCY WITH MDLS HAS BEEN POOR...UKMET/MRF/AVN HAVE CONVERGED A BIT IN SUGGESTING SHRTWV RDGING TUESDAY AHEAD OF NEXT SHRTWV AND SHOT OF COLDER AIR ARRIVING MID-WEEK. UKMET IS MUCH DEEPER WITH SHRTWV INTO THE WRN LAKES BY WED WHILE MRF/AVN ADVERTISES A MORE ZONAL PATTERN WITH ONLY A QUICK INTRUSION OF SHALLOW COLD AIR WITH MORE LIMITED SNOW OR LES POTENTIAL. MRF/UKMET/ECMWF ALSO SUGGEST MID LVL RDGING AGAIN BY LATE WEEK. WITH UPPER LVL PATTERN IN TRANSITION PHASE...HAVE PLENTY OF UNCERTAINTY IS ASSOCIATED TIMING/STRENGTH DIFFERENCES WITH ANY SHRTWVS AFFECTING UPR MI BY WED/FRI. SO...HAVE MADE LITTLE CHANGE TO GOING FCST. .MQT...NONE. JLB mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 340 PM EST FRI DEC 14 2001 12Z RAOBS/WATER VAPOR LOOP SHOW UPPER SHORTWAVE OVER THE WESTERN GREAT LAKES WITH POTENT VORT MAX OVER INDIANA/OHIO. UPSTREAM RIDGE OVER THE PLAINS WITH TROUGH OVER THE WEST COAST. TWO DISTINCT PIECES OF ENERGY NOTED...ONE OVER WASHINGTON/BRITISH COLUMBIA AND ONE OVER CALIFORNIA/NEVADA. SURFACE ANALYSIS SHOWS OVER OHIO...WITH RIDGE ALONG THE MISSISSIPPI FROM HIGH OVER ONTARIO. REGIONAL RADARS/METARS SHOW A MIX OF RAIN AND SNOW OVER THE AREA...MAINLY RAIN OVER THE EASTERN CWA AND SNOW OVER WESTERN CWA. OF FIRST CONCERN IS PRECIP WITH THE DEPARTING SYSTEM. BACK EDGE OVER NORTHERN INDIANA AND LAKE MICHIGAN...WHERE RUC/ETA DEPICT 295/300K ISENTROPIC DECENT AND DRYING. LIFT CONTINUES VERY EARLY THIS EVENING WITH 2-3G/KG SPECIFIC HUMIDITY. WILL WAIT TO SEE LATEST RADAR TRENDS BEFORE ZONE ISSUANCE...BUT EXPECT PRECIP TO END THIS EVENING...SNOW NORTH/MIXED RAIN AND SNOW SOUTH. WITH CONTINUED ACCUMULATING SNOW... WILL CONTINUE WINTER WEATHER ADVISORY INTO THE EVENING. DEEP MOISTURE DECREASES TONIGHT WITH DRYING AT 500/700MB NOTED ON PROFILES AND PLAN FIELDS. A FEW BREAKS IN THE CLOUDS UPSTREAM...BUT NOT SURE HOW MANY WILL CONTINUE ONCE THE SUN SETS. DESPITE SUBSIDENCE/MID-LEVEL DRYING...LOW-LEVEL MOISTURE AROUND 925/850MB LINGERS AS IT HAS THE PAST FEW NIGHTS. EXPECT CLOUDS TO STICK AROUND TONIGHT BEFORE MIXING OUT TOMORROW. SURFACE RIDGE MOVES EAST IN THE MORNING...WITH RETURN FLOW DEVELOPING BY AFTERNOON WITH 850MB TEMPERATURES CLIMBING TO 2C ACROSS THE SOUTHERN CWA AT 00Z. CONTINUED SUBSIDENCE/DRYING IN ADDITION TO MIXING FROM INSOLATION WILL LEAD TO INCREASING SUNSHINE...SIMILAR TO WHAT HAPPENED TODAY OVER WESTERN WISCONSIN/IOWA. HIGH CLOUDS AHEAD OF NEXT SYSTEM LOOK TO HOLD OFF UNTIL SATURDAY NIGHT...AND WILL CONTINUE WORDING OF BECOMING MOSTLY SUNNY. WESTERN TROUGH SHIFTS EASTWARD...WITH BROAD SURFACE LOW/TROUGH ACROSS THE PLAINS SATURDAY NIGHT. SOUTHERN STREAM SHORTWAVE BECOMES DOMINATE WITH SURFACE WAVE DEVELOPING OVER THE LOWER MISSISSIPPI ON SUNDAY. WEAKER PVA/DEVELOPING ISENTROPIC LIFT OVER THE GREAT LAKES AHEAD OF THE NORTHERN SHORTWAVE/SURFACE TROUGH. AVN HAS SLOWED THE EASTWARD PROGRESS OF THE SYSTEM OVER THE PAST TWO RUNS. FORECAST SOUNDINGS SHOW VERY DRY AIR BELOW 600MB 12Z SUNDAY...WITH PROFILES SATURATING BY 00Z THAT EVENING. WILL BUMP BACK TIMING FOR PRECIPITATION TO THE AFTERNOON SUNDAY AND CONTINUE IT THROUGH SUNDAY NIGHT. EVEN WITH TREND MENTIONED IN THE NEXT PARAGRAPH...WILL CARRY CHANCE POPS ACROSS MAINLY THE SOUTHEAST CWA INTO MONDAY WITH SOME LINGERING MOISTURE AND WEAK QVECTOR CONVERGENCE AHEAD OF SECONDARY SHORTWAVE SWINGING THROUGH LOWER MICHIGAN. 00Z AND 12Z AVN RUNS AS WELL AS THE MRF/ETA-XX HAVE TRENDED AWAY FROM THE CUTOFF LOW OVER THE GREAT LAKES MONDAY/TUESDAY. THESE MODELS KEEP THE NORTHERN AND SOUTHERN STREAMS OUT OF PHASE AND EMPHASIZE THE SOUTHERN STREAM ENERGY. MAJORITY OF MRF ENSEMBLE MEMBERS SUPPORT THIS MORE PROGRESSIVE SOLUTION...BUT 12Z/13 ECMWF AND 00Z/14 CANADIAN STICK WITH THE PREVIOUS IDEA OF A STRONGER PHASED LOW THAT CUTS OFF OVER THE EASTERN GREAT LAKES. WILL TEND TOWARD THE OPEN SOLUTION GIVEN THE LOOK OF THE 12Z ETA. ENSEMBLE MEMBERS ARE IN GENERAL AGREEMENT DROPPING ANOTHER TROUGH ON THURSDAY...WITH RIDGING BUILDING IN FOR FRIDAY. THANKS TO GRR AND APX FOR COORDINATION. .DTX...WINTER WX ADVISORY...THIS EVENING...MIZ047>049-053>055-060>062. JHB mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1135 AM EST FRI DEC 14 2001 WILL CONTINUE ADVISORY AS IS. WILL TWEAK WORDING FOR A LITTLE STRONGER MIX IN SOUTHERN COUNTIES. THIS SUPPORTED BY LATEST OBSERVATION TRENDS...RUC 1000 TO 850 MB THICKNESSES WHERE 1305 M STILL CRUDELY LINES UP WITH RAIN VERSUS SNOW...AND IS PROGGED TO SUPPRESS SOUTH THIS AFTERNOON INTO FAR SOUTHERN COUNTIES. DYNAMIC COOLING AND SOME RESIDUAL EVAPORATIVE COOLING PLAYING A PART IN CHANGE OF RAIN TO SNOW OR MIX...IS VERY DIFFICULT TO QUANTIFY. .DTX...WINTER WEATHER ADVISORY...THIS AFTERNOON AND EVENING FOR DWD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1112 AM EST FRI DEC 14 2001 KGRR-88D SHOWS A BROAD AREA OF PCPN MOVING NORTH ACROSS THE CWA. AS EXPECTED THERE IS A SHARP NRN EDGE TO THE PCPN EXTENDING FROM BIV TO JUST SOUTH OF BIG RAPIDS. THIS LINES UP VERY NICELY WITH CONDENSATION PRESSURE DEFICIT FORECASTS. MOST AREAS HAVE ALREADY TURNED OVER TO SNOW AS THE STRONGEST REFLECTIVITIES MOVE NORTH FROM INDIANA INTO THE CWA. AZO HAS ALREADY PICKED UP AN INCH. CURRENT ADVISORY AREA LOOKS GOOD ATTM AND WILL BE CONTINUED. WILL BOOST ACCUMS A TAD DUE TO THE QUICKER TURNOVER TO SNOW AND ADD CALHOUN TO THE ADVISORY AREA AS THE NW CORNER OF THE COUNTY IS CURRENTLY UNDER THE HEAVIER SNOW AREA. LATEST RUC CONTINUES TO SHOW THE 1000-850 1300M THICKNESS LINE SINKING SOUTH THRU THE AFTERNOON. IR LOOP SHOWS THE SOUTHWEST EDGE OF THE CLOUD SHIELD MAKING STEADY PROGRESS TO THE NORTH WHICH SUGGESTS THAT THIS WILL NOT BE A LONG-LIVED EVENT. WILL LOWER TEMPS A TAD TO REFLECT CURRENT TRENDS. 93 .GRR...SNOW ADVISORY MIZ051-052-057>059-064>066-071>073 THIS AFTERNOON THROUGH THIS EVENING. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 205 PM CST FRI DEC 14 2001 LOW STATUS DECK SLOWLY ERODING FROM WEST TO EAST ACROSS EASTERN KANSAS...NORTHEAST OKLAHOMA THIS AFTERNOON. SOME BREAKS HAVE ALREADY DEVELOPED ALONG THE PLATEAU DUE TO SOUTHWEST FLOW OVER HIGHER TERRAIN OF NORTHWEST ARKANSAS. SHORT TERM CONCERNS: WHEN LOW CLOUD DECK DEPARTS OVERNIGHT. LONGER TERM CONCERNS: PRECIPITATION CHANCES SATURDAY AFTERNOON THROUGH MONDAY MORNING. LATEST 20/40 RUC AND MESOETA SHOWING 90/92H RH FIELDS SLOWLY DRYING OUT DURING THE EVENING AS A STRONGER S/SW FLOW DEVELOPS. WILL MAKE LAST MINUTE ADJUSTMENTS IN THE WESTERN ZONES DUE TO AMOUNT OF CLOUD COVER LEFT...BUT WILL WORD THE REST OF THE AREA WITH "BECOMING CLEAR LATE IN THE EVENING. RETURN FLOW DEVELOPS AFTER MIDNIGHT WITH 15 TO 20 MPH SOUTH/SOUTHEASTERLY WINDS LIKELY AHEAD OF NEXT SYSTEM MOVING ACROSS CALIFORNIA THIS AFTERNOON. MODEL ARE IN GOOD AGREEMENT WITH LARGE SCALE FEATURES AS THE MAIN UPPER SYSTEM MOVES OUT INTO THE SOUTHERN PLAINS SATURDAY AFTERNOON. INITIAL WARM AIR/THETA-E ADVECTION DEVELOPS SATURDAY AFTERNOON...WITH LIGHT RAIN MOST LIKELY BY SUNSET ACROSS THE SOUTHERN ZONES. MODEST THETA-E ADVECTION WILL GENERATE LIGHT RAIN OVER MOST OF THE CWA SATURDAY NIGHT/SUNDAY MORNING...ONLY AREA OF CONCERN IN THE FAR NW AS MAIN DYNAMICS HOLDS OUT UNTIL THE MAIN UPPER LOW MOVES THROUGH THE AREA SUNDAY AFTERNOON/SUNDAY NIGHT. BELIEVE TOO WAVES OF PRECIPITATION WILL DEVELOP...LIKE THE PREVIOUS SYSTEM. HIGH PRECIPITABLE WATER VALUES IN EXCESS OF ONE INCH WILL LIKELY GENERATE COPIOUS AMOUNTS OF RAINFALL...ESPECIALLY IN THE FAR SE ZONES. NCEP DISCUSSION (DAY 2) IS EXPECTING NEARLY 3-4 INCHES IN CENTRAL/EASTERN ARKANSAS. THIS AREA HAS HAD THE BULK OF THE HEAVIEST RAINFALL THE LAST FEW DAYS...THEREFORE NOT ANTICIPATING ANY FLOODING FROM THIS EVENT...HOWEVER IT BEARS WATCHING (ESPECIALLY FAR SE ZONES)!!! SECOND WAVE/UPPER LOW WILL SLOWLY MOVE OUT SUNDAY NIGHT...SO CONTINUED A SMALL CHANCE OF RAIN IN THE FAR SE ZONES. ALSO THICKNESS VALUES AND SURFACE TEMPERATURES ARE NOT CONDUCIVE FOR FREEZING OR FROZEN PRECIPITATION...EVEN AS THE EVENT WINDS DOWN. ISC GRIDS ALREADY SENT. FCSTID = 25/JLT SGF 35 55 40 47 / 0 20 70 50 JLN 36 55 42 48 / 0 20 60 50 UNO 36 54 41 48 / 0 20 70 70 VIH 35 55 40 47 / 0 20 70 50 .SGF... MO...NONE. KS...NONE. JLT mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 400 AM CST FRI DEC 14 2001 DEFORMATION/TROWAL TYPE RAIN/SNOW SHOULD BE PULLING OUT OF THE CWA LTR THIS MRNG AS VORT CNTR OVR N CNTRL AR MOVS INTO SRN IN BY 18Z FRI AND SFC LOW OVR WRN KY TN MOVS INTO WRN OH. 10Z RUC HAS 700-600 MB THETA E RDG EXTDG FM ERN KY W THRU SRN IN SRN IL AND INTO SERN MO. LGT SNOW BEING REPORTED IN UIN WITH PERIODS OF LIGHT TO MODERATE SNOW JUST N AND NE OF STL WITH LWR FREEZING LVLS. WL MENTION UP TO ONE INCH OF ACCUMULATION N OF STL...SHOULD BE MAINLY ON GRASSY AREAS AND ON ELEVATED SFCS WITH WRM GROUND TEMPS...ALTHOUGH ROADS COULD BE SLICK WITH SLUSHY ACCUMULATION THIS MRNG BFR SNOW ENDS AND TEMPS RISE INTO THE LWR 40S. ANY LEFTOVR PCPN LT THIS MRNG IN THE FORM OF DRIZZLE AS MOISTURE BCMS MORE SHALLLOW WITH DECREASING CLOUDINESS FM W TO E THIS AFTN. PCPN SHOULD RETURN ON SAT NGT INTO SUN AS ETA DEPICTS STG 850 MB THETA E ADVCTN AND MOISTURE CNVG OVR CNTRL AND SRN MO ON NOSE OF STG SWLY LLJ AHD OF NEXT TROF. WITH 1000-700 MB THICKNESS FCST BY ETA/AVN WELL ABV 2840 M OVR ENTR CWA LOOKS TO BE AN ALL RAIN EVENT...WITH ONLY A BRIEF PERIOD OF CAA SUN NGT JUST AFTR PCPN MOVES OUT OF AREA. .STL...NONE GKS mo FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 950 AM CST FRI DEC 14 2001 FORECAST CHALLENGE FOR UPDATE CONCERNS MAINLY CLOUD TRENDS AND TEMPERATURES. IFR CIGS WHICH HAVE SPREAD INTO RRV IN MOIST LOW LEVEL SSE FLOW DEPICTED FARLY WELL BY 925MB RH FIELDS FROM RUC. LAYER ONLY GRADUALLY DRIES THIS AFTERNOON AND WITH SSE FLOW CONTINUING ALONG WITH STEEPENING INVERSION WILL LIKELY BE TOUGH TO CLEAR OUT. WILL LIKELY TRIM BACK ON OPTIMISM OF CLEARING TRENDS...ESPECIALLY EAST RIVER. FARTHER WEST MID/UPPER LEVEL CLOUD COVER IN ZONE OF WARM ADVECTION WILL HAVE A TOUGH TIME SPREADING TOO FAR EAST AS COLUMN REMAINS FAIRLY DRY SO SHOULD SEE FAIR AMOUNT OF SOLAR IN THIS AREA. WIDE RANGE OF TEMPS WITH SINGLE DIGITS OVR FAR NE ND WHICH REMAINED IN THE CLEAR TO GENERALLY 20S ELSEWHERE. WILL MAKE SOME MINOR ADJUSTMENT OVER FAR NORTH AND ALLOW FOR ONLY MINOR RECOVERY IN CLOUD COVERED AREAS. .FGF...NONE. VOELKER nd AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN NATIONAL WEATHER SERVICE ABERDEEN SD 345 PM CST FRI DEC 14 2001 A FEW CONCERNS IN THE FORECAST INCLUDE LOW CLOUD COVERAGE AND FOG DEVELOPMENT EARLY TOMORROW MORNING AND PRECIPITATION CHANCES FOR SATURDAY NIGHT WITH NEXT PACIFIC COAST SHORT WAVE TROUGH. 20Z SURFACE OBSERVATIONS SHOW TONGUE OF RELATIVELY HIGHER DEW POINTS EXTENDING FROM CENTRAL MISSOURI NORTHWARD INTO EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA. SURFACE WINDS HAVE STARTED TO TURN TO THE SOUTH OVER MUCH OF EASTERN SOUTH DAKOTA. HOWEVER...IN THE EXTREME NORTHEASTERN PART OF CWA EASTERLY WIND COMPONENT WILL LIKELY REMAIN IN PLACE KEEPING DEW POINTS RELATIVELY HIGH. 18Z RUC ALSO SHOWS EASTERLY COMPONENT REMAINING FOR MUCH OF THE NIGHT IN THIS AREA. WILL MENTION LOW CLOUDS/FOG FOR THESE COUNTIES THROUGH THE NIGHT. THE NEXT CONCERN WILL THEN SHIFT TO NEXT SHORT WAVE TOMORROW. SIGNIFICANT CHANGE IN THE MODELS FROM YESTERDAY. MODELS NOW IN GENERAL AGREEMENT IN SHOWING SPLIT FLOW SOLUTION WITH MORE AGGRESSIVE DEVELOPMENT OF SOUTHERN STREAM WAVE. HOWEVER...MODELS SEEM TO BE CONVERGING ON A MORE PROGRESSIVE POSITIVELY-TILTED SOLUTION TO THE WAVE EVOLUTION. AVN..ETA..AND CANADIAN MODELS SIMILAR ON TIMING OF WAVE WITH 500 HPA TROUGH AXIS PASSING THROUGH CWA SUNDAY MORNING. UKMET AND AVN HAVE SLIGHTLY SHARPER 500 HPA WAVE WITH SMALLER WAVELENGTH...BUT THIS SEEMS TO HAVE LITTLE AFFECT ON UPPER DIVERGENCE AND VERTICAL MOTION PATTERNS BETWEEN THE MODELS. STRONGEST LOW LEVEL THERMAL RIDGING REMAINS SOUTH OF CWA SATURDAY MORNING. HOWEVER AVN AND ETA BOTH INDICATE 850 HPA TEMPERATURES RISING INTO THE 4-7 DEG CELSIUS RANGE. 12Z ETA FORECAST SOUNDINGS SHOW RELATIVELY DRY LAYER FROM 800-650 HPA FOR TOMORROW AFTERNOON. DESPITE ISENTROPIC LIFT WITH WARM FRONTAL PASSAGE SATURDAY MORNING...MODELS REMAIN SHOW NO QPF DURING THE DAY TOMORROW WITH SIGNIFICANT BOUNDARY LAYER MOISTURE REMAINING VERY SHALLOW. ETA BRINGING IN SMALL QPF AMOUNTS LATE SATURDAY NIGHT AND QPF SIGNATURE IS LARGELY A REFLECTION OF MID AND UPPER LEVEL PVA. PRECIPITATION TYPE SHOULD NOT BE A CONCERN WITH THIS EVENT AS ANY PRECIPITATION THAT FALLS SHOULD BE AFTER PASSAGE OF LOW LEVEL BAROCLINIC ZONE SATURDAY AFTERNOON. AVN SLIGHTLY MORE AGGRESSIVE WITH QPF AMOUNTS BUT CONSIDERING TREND FOR AVN OVERDOING PRECIPITATION WILL TREND TOWARD THE ETA SOLUTION. MODELS INDICATE STRONG MID LEVEL DEFORMATION ACTING TO STRETCH 500 HPA PV TOMORROW NIGHT INTO SUNDAY MORNING...REDUCING THE POTENTCY OF MID LEVEL PVA FORCING. WILL DROP POPS TO 30 PERCENT FOR OVERNIGHT SATURDAY. LACK OF SUFFICIENT DEEP BOUNDARY LAYER MOISTURE COMBINED WITH MINIMAL DURATION IN THE UPPER FORCING SHOULD KEEP ACCUMULATION AMOUNTS LIGHT...GENERALLY LESS THAN AN INCH. WITH SUCH AN ANTICYCLONICALLY SHEARED OUT MID LEVEL WAVE...SHOULD CLEAR RAPIDLY ON SUNDAY MORNING AS MODELS INDICATE TIGHT PV GRADIENT AS TROUGH MOVES EAST OF REGION. LARGE SCALE...LOW AMPLITUDE UPPER RIDGE BUILDS INTO CWA FOR MONDAY...BUILDING 1000-500 HPA THICKNESS RIDGE. THIS WILL KEEP REMAINDER OF SHORT TERM FORECAST DRY AND WITH MUCH ABOVE NORMAL TEMPERATURES. .EXTENDED DISCUSSION... EXTENDED MODELS COMING INTO BETTER AGREEMENT THAN DAYS PAST ALTHOUGH THERE ARE STILL SOME DIFFERENCES. THE MRF STARTS THE EXTENDED PERIOD WITH A UPPER RIDGE IN PLACE OVER THE MIDWEST AND AGREES WELL WITH THE CURRENT AVIATION. NOGAPS AGREES FAIRLY WELL THOUGH IS MUCH WEAKER WITH THE UPPER WAVE WEDNESDAY AND BUILDS TOO STRONG A SURFACE HIGH OVER THE UPPER MIDWEST. ECMWF DIGS A FAIRLY STRONG PACIFIC LOW OFF THE OREGON COAST THURSDAY WHERE MRF SOLUTION OF TROUGH DIGGING TO SOUTHERN CALIFORNIA BEFORE MOVING INLAND AND CLOSING OFF LOOKS BEST. WILL LEAN TOWARD MRF SOLUTION WHICH HAS H5 RIDGE DEVELOPED OVER THE AREA TUESDAY WITH AN OPEN WAVE APPROACHING THROUGH WYOMING/MONTANA. MOISTURE IS A LITTLE SPARSE MRF BRINGS A GOOD SURFACE LOW THROUGH WITH THIS WILL CARRY A CHANCE OF SNOW WITH THIS BASED ON THICKNESS VALUES THAT ARE WELL BELOW 540 BY WEDNESDAY AFTERNOON. RIDGE REFORMS THURSDAY AND FRIDAY AS PACIFIC TROUGH DIGS IN THE WEST TURNING UPPER FLOW TO THE SOUTHWEST. UPPER LOW CLOSES OFF FRIDAY IN THE FOUR CORNERS AREA AND WE LEAVE THIS EXTENDED PERIOD WITH AN UPPER FLOW THAT LOOKS CAPABLE OF PRODUCING THE NEXT WINTER STORM. .ABR...NONE. KEEFE/MARSILI sd COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 919 PM CST FRI DEC 14 2001 REVIEW OF THE FIRST 12 HRS OF THE 00Z MODEL CYCLE SHOWS BOUNDARY LAYER MOISTURE WILL BE 2KFT LESS AND ISENTROPIC UPGLIDE WILL BE WEAKER. BOUNDARY LAYER MOISTURE IS EXPECTED TO INCREASE RAPIDLY OVERNIGHT(3KFT) AS A STRONG(40 KNOTS) LOW-LEVEL JET DEVELOPS. MODERATE ISENTROPIC UPGLIDE(I285/I290) ALSO DEVELOPS BUT CONDENSATION PRESSURE DEFICITS ARE MARGINAL AT BEST TO SUPPORT RAIN(MOSTLY THE RIO GRANDE PLAINS). WITH THE 500HPA TROUGH DIGGING OVER BAJA CALIFORNIA...FEEL THE VORTICITY MAXIMUM OVER THE SIERRA MADRE WILL BE PULLED WEST OF THE CWA...AS THE ETA/MESOETA/NGM/RUC INDICATE. THEREFORE...ANY DYNAMICAL FORCING IN ASSOCIATION WITH THIS FEATURE WILL LIKELY JUST SCRAPE THE FAR WESTERN RIO GRANDE PLAINS. BOUNDARY LAYER FORCING DOES INCREASE SOME OVERNIGHT...BUT GIVEN THE ASSESSMENT ABOVE...WILL RETAIN THE CURRENT POP DISTRIBUTION. A STRONG CAPPING INVERSION WILL RESULT IN JUST STRATIFORM PRECIPITATION. ALSO EXPECT THE WINDS TO BACK TO THE EAST AS THE WARM FRONT SLOWLY APPROACHES SOUTH TEXAS. WITH LOW-LEVEL WARM THERMAL ADVECTION OCCURRING...WILL REFLECT STEADY OR SLOWLY RISING TEMPERATURES OVERNIGHT. MESOETA/RUC FOG DIAGNOSTICS SUGGEST PATCHY FOG WILL DEVELOP LATE...MAINLY THE EASTERN COUNTIES. MARINE...LLJ EXPECTED TO INCREASE OVERNIGHT AS LOW PRESS UP NORTH DEEPENS. THIS WILL INCREASE MAINLY THE WINDS OVER THE COASTAL WATERS. MESOETA INDICATES A WEAK TROF DEVELOPING ALONG THE COAST TONIGHT...WHICH SEEMS REASONABLE WITH WAA ANTICIPATED AND AN UPPER LEVEL VORT MAX EXPECTED TO SWING ACROSS THE REGION. CURRENTLY WINDS ARE ELY ACROSS THE BAYS AND ALTHOUGH WINDS ARE EXPECTED TO VEER MORE TO THE SE OVER THE NEXT FEW HOURS...THEY WILL BACK AGAIN TO THE E WITH THE WAA. WILL LOWER BAY WINDS BY ABOUT 5 KNOTS AND MAINTAIN AN ELY DIRECTION. .CRP...NONE. 85/BB/PUBLIC 81/TE/MARINE-AVIATION tx SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 245 AM MST SAT DEC 15 2001 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL MOVE THROUGH NORTHERN ARIZONA AND CONTINUE TO WEAKEN TODAY. THE THREAT FOR SHOWERS AND MOUNTAIN SNOW WILL ALSO DECREASE BY THIS AFTERNOON. HIGH PRESSURE WILL BUILD ACROSS CALIFORNIA...AND WESTERN ARIZONA ON SUNDAY. THUS...CLOUDY SKIES TODAY WILL GIVE WAY TO SUNSHINE TOMORROW. BREEZES WILL ALSO KICK UP IN ALL AREAS TODAY AS A WEAK COLD FRONT MOVES INTO EASTERN ARIZONA. DRY AND WARMER CONDITIONS WILL DOMINATE OUR WEATHER INTO THE MIDDLE PART OF THE WEEK...ALTHOUGH HIGH CLOUDS WILL FILTER OUT SOME OF THE SUNSHINE. .DISCUSSION... WATER VAPOR LOOP INDICATED THE UPPER LEVEL TROUGH HAS BEGUN TO WEAKEN AS OF 06Z. BEST ENHANCEMENT APPEARS EAST OF PHX WITH COLDEST 500MB TEMPS...-28C...NEAR KINGMAN. HEIGHTS ALSO HAVE BEGUN RISING WITH THIS SYSTEM...PER RUC/ETA...ALTHOUGH COLD ADVECTION LIKELY TO RESULT IN BANDS OF INSTABILITY SHOWERS MAINLY IN OUR EASTERN ZONES TODAY. AVN HAS ALSO SLOWED SOMEWHAT FROM ITS PREVIOUS RUNS...ALTHOUGH PRECIP AMOUNTS QUITE LIGHT. SFC DEW POINTS RAMPING UP SLOWLY FROM THE WEST...AND 88D REFL LOOPS SHOW LIGHT PRECIP GENERALLY EAST OF YUMA-QUARTZSITE LINE AT 08Z. COLD FRONT DUE INTO PHX AROUND 12Z...CLOSE TO EARLIER PROJECTIONS. 850MB TEMPS TO DROP TO NEAR FREEZING BY 18Z...AVN BEING MUCH COLDER THAN ETA. THUS WE WILL MODIFY SNOW ADV SLIGHTLY AS PRECIP BAND IS DVLPG. WILL ALSO TWEAK FCSTS SLIGHTLY FOR WINDS AND POPS...OTHERWISE TRENDS GOOD FROM PREVIOUS PACKAGE. STG UPPER JET TO DIVE SOUTH ... BUT WILL KEEP WINDS BELOW ADVSRY LVLS AT IMPERIAL/BLYTHE. MODELS AGREE ON BUILDING THE UPPER RIDGE OVER SERN CALIF BY LATE SUNDAY. HIGH LEVEL MOISTURE STILL EXPECTED TO SPREAD INTO ARIZONA DURING MIDWEEK...AS ANOTHER IN A SERIES OF PACIFIC TROFS APPROACHES. MRF SHOWS MORE OF A PROGRESSIVE PATTERN NOW...AND BRINGS NEXT SYSTEM INTO THE CALIF COAST A BIT EARLIER. LOOK FOR NICE TEMPERATURE RECOVERY BY TUESDAY. MAX TEMPS MAY BE A BIT ABOVE AVERAGE SPCLY TUESDAY. SIPPLE .PSR...SNOW ADVISORY SOUTHERN GILA AND FAR NORTHEAST MARICOPA COUNTY ABOVE 4000 FEET UNTIL 3 PM MST. az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 345 AM CST SAT DEC 15 2001 FCST CONCERNS CONT TO BE CLOUDS...PRECIP CHANCES WITH TROF TNGHT/SUN AND TEMPS SUN. MDLS STILL DOING OK JOB ON SYNOPTIC SCALE BUT STILL HAVING SIG DIFFS WITH LL THERMAL GRADIENTS AND VERY HIGH LL RH. SIDING WITH ETA FOR MOST PART THIS CYCLE...BUT STILL SPLIT FLO GIVING MDLS FITS FROM RUN TO RUN. SC/ST BROKE OUT IN FORCE THIS MRNG AND SEE NO REASON WHY THIS WILL BREAK THRU DAY. STRONG SRLY FLOW /40-50KTS AT H85/ COUPLED WITH STRONG MOISTURE TRANSPORT TO CONT THRU DAY. WITH SUCH STRONG WAA OVER STILL UNDERFCST COOL PBL...ST/SC BLOSSOMING. RUC/META ISENTROPIC LIFT ENOUGH TO SATURATE OUT IN LOW LEVELS...DESPITE SOME VERY DRY AIR ATOP THE VERY SHALLOW INVERSION. A BIT WORRIED SOME GOOD MIXING MIGHT POKE SOME HOLES IN SC DECK...BUT THESE SHOULD FILL WITH CONTINUED LL WAA/LIFT. WITH CEILING SO LOW...COULD NOT RULE OUT A PATCH OR TWO OF DRIZZLE GIVEN HIGH LL MOISTURE. FOLLOWING ETA/META H9-H8 TEMPS TO BASE HIGHS ON...WHICH CAME OUT A BIT ABV GUIDANCE. TROF TONIGHT SLOWING A BIT AS ONE WOULD GUESS GIVEN STRENGTH OF JET...BUT JET CONFIGURATION AND SPLIT FLOW MAKING THIS SYSTEM LOOK WEAKER BY THE MOMENT. STILL A FULL LATITUDE TROF...BUT OPEN AND PROGRESSIVE. NO CHANCE TO REALLY WRAP SOME GOOD MOISTURE/CONVERGENCE INTO IT. IMPRESSIVE DRY LAYER /SEEN IN 00Z RAOBS AT KTOP/KOAX/KLBF/ WILL KEEP ANY PRECIP TONIGHT IN WEST SHORT IN DURATION AND LIGHT. LOW/MID LEVEL UVV'S NOT EVEN THAT IMPRESSIVE...WITH SPLIT IN FLOW TAKING BEST FORCING BOTH SOUTH AND NORTH OF MPX CWA. STILL SEEING SIGNS THAT SOME BETTER/DEEPER MOISTURE ON 285/290K THETA SFCS COULD INTERACT WITH TROF OVER FAR ERN CWA ON SUNDAY AND BREAK OUT A LITTLE BETTER AREA OF -RA. SLIGHTLY HIGHER POPS HERE...BUT STILL NOTHING TO GET EXCITED ABOUT. STEADY TEMPS IN WEST TMR UNDER MOD CAA...BUT EAST COULD POP CLOSE TO 40 AGAIN JUST AHEAD OF SLOWING FRONT. CAA TO ONLY LAST 6-12 HOURS AS FLOW RAPIDLY BCMS WRLY AGAIN...AS STRONG CANADIAN SYSTEMS FLATTEN OUT MID LAT FLOW. RESULT IS FAST ZONAL FLOW...WITH WEAK WAVES AND CONT MUCH ABOVE NORMAL TEMPS WITH PACIFIC FLOW. SHOULD BE MORE FOG...EPISODES OF LOW SC/ST...AND LIGHT PCPN AMTS/DURATION THRU NEXT WEEK. ONLY PERIODIC WEAK COOL DOWNS...ONE ON WED...AND NEXT WEEKEND. WHITE CHRISTMAS IN MN LOOKING BLEAKER AND BLEAKER. .MSP...NONE. BINAU mn SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 200 AM CST SAT DEC 15 2001 WATER VAPOR PICS SHOW WELL DEFINED TROF XG THE WRN CONUS THIS MRNG WITH ARND 200 M HT FALLS OVR THE GREAT BASIN. VORTEX XG AZ/NM TDA IS EXPECTED TO WEAKEN AS IT SLIDES ACRS THE PLNS TNGT...WHILE TRAILING SHRTWV IS PROGGED FOR THE SRN PLNS. SFC LOW OVR ERN CO/WY HAS PULLED LLVL MSTR IN THE AREA WITH ST SPREADING OVR THE ERN ZONES AS OF 08Z. DURATION/WWD EXTENT OF THESE CLDS IS A PROBLEM WITH RUC/MESOETA COND PRES DEF PROGS CLRG THE AREA BY AFTN. MSTR LYR IS SHALLOW SO WL MIX IT OUT TO PC WITH TEMPS SOMEWHERE ARND HIGHER MAV NMBRS. WINDS IN THE BREEZY CATEGORY LK OK. CDFNT STILL TIMED FOR LTR TNGT AND PCPN CHCS RMN QNABLE. SFC LOW PROGGED TO WIND UP NR THE NCNTRL KS CNTIES BY MIDNGT WITH LLVL MSTR AXIS SHUNTED EWD. ISENTROPIC LIFT WITH THE ADVN OF THE MID LVL TROF IS UNIMPRESSIVE THIS RUN...EVEN FOR THE USUALLY STRNGR AVN. LK AT MDL SNDINGS SHOWS THE SUB 700 MB LYR MOISTENS UP BRIEFLY TWD 12Z...WITH COLD AIR SWEEPING OVR THE CWA BY THAT TIME. CANNOT RULE OUT LGT PCPN TIL THE TROF AXIS PASSES ON SUN MRNG. WL MAINTAIN CHC/SLGT CHC POPS FOR -RA/SN FOR LATE SAT NGT/EARLY SUN. REST OF THE PACKAGE LKS OK WITH RIDGING/WARM ADVCTN SLATED FOR MON. .GID...NONE. 09 ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 600 AM EDT SAT DEC 15 2001 MAIN FOCUS THIS PKG DEALS WITH -RA CHCS SUN INTO SUN NIGHT...OTHERWISE THE USUAL CLD/TEMP FCST AGONIES. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF OVER THE WRN CONUS AND RDGG TOWARD THE PLAINS AND MIDWEST. WELL-DEFINED SHRTWV AND 100 KT 3H JET MAX ROUNDING BASE OF UPR TROF OVR SW STATES WHILE MORE SHEARED OUT SHRTWV EVIDENT OVR THE NRN ROCKIES. AT SFC...HIGH PRES RDG OVR THE CNTRL GRT LAKES WHILE LOW PRES IN LEE OF CO RCKYS. SOMEWHAT MOIST SSE FLOW BTWN THESE FEATURES RESULTING IN AREAS OF UPSLOPE STRATUS OVR NCNTRL AND ERN ZONES OF U.P. TODAY...WITH CONTINUED SSE FLOW EXPECT STRATUS CLDS TO HOLD IN OVER ERN ZONES PER 06Z ETA FCST SNDGS. NCNTRL ZONES COULD SEE SOME EROSION OF STRATUS LATE THIS MORNING/ERY AFT WITH DIURNAL MIXING AND A SLIGHT VEERING OF WNDS TO S AHD OF APPROACHING SHEARED OUT CDFNT OVR NRN PLAINS. WRN FA SHOULD STAY FREE OF STRATUS BUT WILL CONTINUE TO SEE WAA CLDS SPILLING OVR RDG AXIS. DRY ADIABATIC MIXING TO 925 MB SEEMS REASONABLE DESPITE HIGH CLDS. THIS WOULD YIELD TEMPS NEAR HIGHER MAV VALUES OF 35 TO 40. SATURDAY NIGHT...STRENGTHENING SLY LLVL JET TO 40 KTS SHOULD BRING IN LLVL MSTR THIS EVENING...SO WENT INCREASING CLOUDS ACROSS FA. DESPITE WK LIFT/Q-VECT CONV AHD OF APPROACHING TROF...MSTR TOO SHALLOW FOR PCPN SO LEFT FCST DRY. STGR WINDS AND MIXING SHOULD KEEP MOST TEMPS ABV FREEZING AGAIN MORE IN LINE WITH AVN GUIDANCE. SUNDAY INTO SUNDAY NIGHT...CONTINUED MOISTURE ADVECTION ALONG WITH MODERATE 700-300 QVECTOR CONVERGENCE AND INCRG 295-300K ISENTROPIC ASCENT AHD OF SHRTWV AND ASSOC SFC CDFNT...WL BE ENOUGH TO KEEP LIKELY PCPN CHANCES FOR CNTRL AND ERN ZONES. TRIMMMED BACK WRN ZONES TO CHC POPS AS ISENTROPIC LIFT NOT AS IMPRESSIVE THERE. ALSO GIVEN MODELS TRENDING SLOWER WITH SHRTWV...BACKED OFF ON TIMING OF -RA THIS AFT SUN. ASSOC SFC CDFNT TENDS TO STALL OUT OR SLOW DOWN SUN NIGHT AS SHRTWV FIGHTS INTO UPR RDG...PER AVN MODEL. DESPITE LOSS OF BEST ISENTROPIC ASCENT...LEFT IN GOING CHC POPS FOR WEST AND CNTRL ZONES AND LIKELY FOR EAST GIVEN FAIRLY DEEP MSTR TO 7KFT AND PROMIXITY OF SFC CDFNT. MONDAY...DESPITE GENL LOSS OF Q-VECT CONV...LINGERING MOISTURE ON MONDAY PER AVN SNDGS AND PRESENCE OF SFC-850 MB OVR AREA...LEFT IN CLDS AND FLURRIES. SUSPECT FLURRIES SHOULD END IN AFT AS SFC-850 MB FLOW BCMS MORE ANTICYCLONIC WITH RDG BLDG IN FM WEST. .MQT...NONE. VOSS mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SPRINGFIELD MO 945 AM CST SAT DEC 15 2001 CLOUD COVER MORE EXTENSIVE THIS MORNING THAN PREVIOUSLY THOUGHT. THIS IS REFLECTED IN THE TEMPERATURE FIELD WITH READINGS STILL IN THE LOW 40S...WITH A FEW MID 40S IN SOUTH CENTRAL MISSOURI. WITH THE INCREASING LOW LEVEL MOISTURE THIS AFTERNOON AND HARDLY ANY BREAKS IN THE OVERCAST...BELIEVE TEMPERATURES WILL BE 45 TO 50 DEGREES AT BEST...WITH THE HIGHEST READINGS OVER SOUTHEAST KANSAS...WHERE THE DEPTH OF THE CLOUD COVER IS LESS. LATEST 20KM RUC STILL INDICATES STRONG THETA-E ADVECTION AND QPF VALUES INCREASING BETWEEN 21-00Z THIS AFTERNOON. ALSO ADJUSTED OVERNIGHT LOWS TO REFLECT DEW POINTS RISING THROUGH THE NIGHT AND ABUNDANT RAINFALL ACROSS THE AREA. NO OTHER CHANGES MADE TO FORECAST. UPDATED ISC GRIDS ALREADY SENT. .SGF... MO...NONE. KS...NONE. JLT mo DEEP SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 925 AM CST SAT DEC 15 2001 DATA FROM MORNING RADIOSONDE LAUNCH SHOWS SIG WARMING BLO 600MB...ABT 11 DEG C AT 925MB...OVR PAST 24 HRS. LI NOW BLO ZERO AT -2.1 AS AIR HAS BECOME VERY MOIST BLO 5K FT... WITH CI DECK ARND 25K FT. WINDS BTWN 2 AND 5K FT ARE 25-40KTS WITH VAD WIND PROFILE VERY SIMILAR. WV/IR SATELLITE LOOP HAS MID/UPR LVL MOISTURE STREAMING ACRS MEXICO TOWARD THE MID MISSISSIPPI VALLEY IN FLOW DOWNSTREAM OF THE L/WV TROF CROSSING THE ROCKIES. BRO RADAR IN REFLECTIVITY MODE DETECTING SHOWERS AND LIGHT RAIN OVER THE CWA...INCLUDING THE COASTAL WATERS. SEE NO NEED TO CHANGE MORNING PACKAGE FOR NOW. MARINE...RUC DATA SHOWS THE MODERATE PGF PERSISTING OVER THE GULF WATERS THROUGH THE REST OF TODAY WITH DECENT 7H LIFT AND MOISTURE EVIDENT THROUGH 00Z THIS EVENING. ACCORDINGLY...WILL MAINTAIN A MENTION OF ISOLD SHOWERS THROUGHOUT THE DAY. BUOY020 CURRENTLY IS REPORTING WINDS NEAR 15 KT WITH GUSTS TO 19 AND SWELLS NEAR 4 FT. HAVE AMENDED THE CURRENT CWF TO INCREASE SURFACE WINDS AND SWELLS A BIT OFFSHORE. OTHERWISE...NO OTHER CHANGES REQUIRED ATTM. SYNOPTIC-PUBLIC...59 MARINE-AVIATION...60/62 MESO...DW INTERNET ADDRESS...WWW.SRH.NOAA.GOV/BRO .BRO...NONE. tx AREA FORECAST DISCUSSION...CORRECTED THE DATE NATIONAL WEATHER SERVICE MARQUETTE MI 1140 AM EST SAT DEC 15 2001 MAIN CONCERN THIS FCST PACKAGE IS THE TEMPS TDA...AND INCR CLD CVR TNGT. WV IMAGERY AND RUC DEPICTING RDG OVR W GRTLKS...TRAPPED BTWN A CUTOFF LOW OVR N UT...AND A SHRTWV OVR ERN GRTLKS. MRNG SOUNDINGS SHOWING A SPLIT JET FLOW. ONE MOVING FM NM N ACRS THE HI PLAINS INTO CAN PRARIES...THEN E ACRS ONT. THE OTHER UPR LVL JET RUN ACRS SRN PLAINS THEN E THRU THE S OH VALLEY. A SFC LOW CONT TO DVLP OVR NE CO THIS AM...ALONG WITH A CDFNT WHICH STRETCHES ACRS SRN HI PLAINS. A LOW LVL 40KT JET STRETCHES FM CNTRL TX...N THRU CNTRL PLAINS TO MN THIS AM...AND WAS DRAWING WRM MOIST GULF AIR INTO UPR MS VALLEY. ALREADY SFC DWPNTS ARE INTO LOW 30S ACRS MN. A WEAK SHRTW WILL BE EXPELLED FM THE TROF OVR SW CONUS INTO W GRTLKS TDA. THE MEAN SFC-500MB RH WILL REMAIN LESS THAN 50 PCT OVR THE REGION THRU 00Z SUN. RUC 290K ISENTROPIC ANLYS SHOWING WEAK LIFT OVR THE FCST AREA THIS AFTN. HOWEVER...850-500MB Q-VEC ANLYS SHOWING NEUTRAL LIFT. VIS IMAGERY DEPICTING AN EXTENSIVE LYR OF CLDS ACRS WI EDGING OVR THE U.P. SFC ANLYS AND IR INDCT THESE CLDS TO BE A SHALLOW LOW CLDS. RAOB INDICT THAT THESE CLDS WOULD BE BLO THE INVRN ARND 950MB. SOUNDING DATA SHOWING THE LYR SHOULD DRY OUT ENOUGH FOR THE CLDS TO DISSIPATE BY EARLY AFTN. HOWEVER...SHORTLY AFT THAT...CI/AC WILL FLOW BACK OVR THE U.P. ALREADY THESE CLDS ARE SHOWING UP OVR IA...IL AND SW WI. THEREFORE...THERE SHOULD BE MIX OF SUN AND CLDS THIS AFTN...WHICH WILL LIMIT SFC HEATING. TEMPS ARE A LTL COOLER THAN MDLS SHOW. WILL BUMP TEMPS DOWN A BIT. CDFNT WILL SLIDE INTO MN...AND CONT TO DRAW WARM GULF MSTR INTO THE UPR GRTLKS....WHICH WILL SATURATE OUT THE LOW LVLS. Q-VEC CVNGNC WILL INCR ACRS THE FCST AREA OVRNGT. 290K ISENTROPIC ANLYS SHOWING ASENT IN THE LOW LVLS ACRS U.P. TNGT. THUS SOUNDING DATA INDICATES THAT THE MID LVL CLDS WILL THICKEN OVRNGT. THE CLDS SHOULD KEEP THE TEMPS UP OVRNGT. WINDS WILL REMAIN OUT OF THE S...AND INCR OVRNGT. .MQT...NONE. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 248 PM CST SAT DEC 15 2001 FORECAST CHALLENGES -- PRECIPITATION CHANCES TONIGHT SYNOPSIS -- 20Z SURFACE ANALYSIS HAD A LOW OVER NERN CO WITH AN ATTENDANT COLD FRONT STRETCHED FROM CNTRL ND TO ERN NM. PRESSURE FALLS TO THE E OF THIS FEATURE WERE RESULTING IN STRONG, S WINDS ACROSS THE ERN PLAINS STATES. ALOFT, MORNING UPPER-AIR ANALYSIS AND AFTERNOON MOISTURE CHANNEL IMAGERY INDICATED A DIGGING TROUGH OVER THE ROCKIES, WITH A BRANCHED DOWNSTREAM JET STRUCTURE: ONE AXIS FROM WRN NM TO ERN MT, AND THE OTHER FROM CHIHUAHUA MEXICO, ACROSS TX TO THE CAROLINAS. FORECAST -- ETA DIAGNOSTICS SUGGEST THE UPPER-LEVEL TROUGH TO OUR W WILL WEAKEN OVERNIGHT AS IT SLOWLY TRANSLATES ACROSS THE PLAINS. ALTHOUGH RUCII DATA INDICATES STEEPENING MID-LEVEL LAPSE RATES APPROACHING FROM THE SW (~7.0 TO 7.5 DEG C/KM), ONLY WEAK LARGE-SCALE ASCENT IS FORECAST (AS SEEN IN THE Q-VECTOR FIELDS) WITH SHALLOW SATURATION IN THE LOW- AND UPPER-LEVELS OF THE ETA FORECAST SOUNDINGS. THUS, WE WILL CARRY A SLIGHT CHANCE POPS ACROSS ALL BUT FAR SERN ZONES, WHERE WE WILL KEEP 30 PERCENT GOING. OTHERWISE, INCREASING CLOUDS SHOULD KEEP TEMPERATURES UP TO NEAR GUIDANCE VALUES. ON SUNDAY, WE MAY SEE SOME LINGERING LIGHT RAIN OR SNOW IN THE MORNING ACROSS THE ERN ZONES WITH THE PASSAGE OF THE SURFACE FRONT. THE AIRMASS BEHIND THIS FRONT ISN'T ALL THAT COLD, AND WITH INSOLATION INCREASING BY AFTERNOON, WE HAVE OPTED TO GO CLOSER TO THE WARMER MAV VALUES. THE MID-LEVEL FLOW BEGINS TO FLATTEN ON MONDAY AND TUESDAY WITH DOWNSLOPING, LOW-LEVEL TRAJECTORIES SUPPORTING A WARMUP. WE WILL SEE THE PASSAGE OF A WEAK FRONT TUESDAY NIGHT AND WEDNESDAY, WITH A SLIGHT COOL DOWN, THEN RIDGING THROUGH THE END OF THE WEEK, AHEAD OF THE NEXT SYSTEM MOVING ONTO THE W COAST. WE WILL CONTINUE WITH A DRY FORECAST THROUGH THE EXTENDED WITH TEMPERATURES CLOSE TO MEX VALUES. THANKS TO LBF FOR COORDINATION! .OMA...NONE. MEAD ne SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 213 PM CST SAT DEC 15 2001 ATTENTION IN THE SHORT TERM IS POPS TONIGHT. PRETTY STRONG UPPER LEVEL TROUGH MOVING OUT OF THE INTERMOUNTAIN WEST. EARLY THIS EVENING...STRONG GRADIENT WILL HOLD WINDS IN THE BREEZY/WINDY CATEGORY EASTERN ZONES. ALSO...SURGE OF 40 DEGREE DEWPOINTS COMING RIGHT UP THE I-135 CORRIDOR AND TAKING DEAD AIM ON EASTERN HALF OF CWFA. M-ETA AND RUC SUGGEST RAPID INFILTRATION OR FORMATION OF CLOUDS AS MOISTURE INCREASING AND WARM ADVECTION SETS UP FOR A TIME THIS EVENING. THIS WILL AFFECT LOWS TONIGHT...AND HAVE HELD THEM UP A BIT IN THE EAST...AND ANTICIPATE THE TEMPERATURES TO DROP JUST BEFORE SUNRISE AS FROPA OCCURS THERE. THE RISK OF MEASURABLE PRECIPITATION LOOKS VERY SMALL TONIGHT. AGEOSTROPHIC ENHANCEMENT NOT FAVORABLE BY LATE EVENING...ISENTROPIC LIFT IS SHORT LIVED...AND MOISTURE IS PRETTY LIMITED. WHAT/S THERE IS VERY SHALLOW. SPLIT TYPE TROUGH FOCUSES ENERGY TO OUR NORTH AND SOUTH...AND LEAVES US IN BETWEEN. HAVE DROPPED ZFP POP WORDING AND WENT PROVERBIAL SPRINKLES/FLURRIES WORDING. AVN HANGS ON TO CLOUDS TOMORROW LONGER THAN THE ETA. DECIDED TO DELAY CLEARING WORDING JUST A BIT. CLOUDS AND COLD ADVECTION WILL DEFINITELY TAKE TEMPERATURES LOWER. THROUGH THE FIRST 15 DAYS OF DECEMBER...WE ARE AVERAGING ABOUT 13 DEGREES ABOVE. THIS GENERAL IDEA WILL CONTINUE THROUGH MOST OF DAYS 2 THROUGH 7...WITH MONDAY/S WEST WINDS AND SUNSHINE EXPECTED TO PUSH TEMPERATURES IN THE 50S MANY AREAS. COOLER AIR AND CLOUDS TUESDAY WILL HOLD TEMPERATURES DOWN SOME...BUT STILL ABOVE NORMALS. COOLEST DAY IS WEDNESDAY BUT SUNSHINE LOOKS LIKELY. RIDGING AHEAD OF DIGGING WEST COAST TROUGH SUGGESTS WARMER WEATHER THURSDAY AND FRIDAY...AND CURRENT 40S IN THE FORECAST MAY NOT DUE. MRF EJECTS WAVE SATURDAY AND AND WARM ADVECTION ASSERTS ITSELF. THE RESULT IS PRECIPITATION CENTERED JUST TO OUR SOUTHEAST. UNCERTAINTY AT THIS TIME...ALONG WITH APPROACHING TRAVEL HOLIDAY...LEAD ME TO HOLD OFF ON PRECIPITATION... AND WAIT FOR SOME MORE CONTINUITY TO DEVELOP. AFTER DAY 7...THE DEVELOPMENT OF STRONG RIDGE NEAR WEST COAST WILL BE A KEY PLAYER IN DETERMINING HOW THINGS WILL SHAKE OUT OVER HOLIDAYS. .GID...NONE. MORITZ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 305 PM CST SAT DEC 15 2001 WL MAKE SOME CHANGES TO EARLY PTN FCST AS SLOWER MVMT OF TROF CURRENTLY INTO CNTRL ND HAS RESULTED IN SOME TIMING PROBLEMS AND INCG MOISTURE WL RESULT IN SOME PCPN OVER WRN AND CNTRL ND THROUGH EARLY SUNDAY. THERE ARE SOME MDL DIFFERENCES BUT HAVE SETTLED ON 18Z MESOETA FOR DETAILS. THIS IS PRETTY SIMILAR IN PLACEMENT OF 70H TROF COMPARED TO LATEST RUC...BUT NOT QUITE AS DEEP...AND IS ALSO WEAKER THAN 12Z RUNS OF ETA/AVN. IN THE WEST THIS EVENG CONCERN IS THAT MID LVLS OF ATMS HAVE NOT COOLED OFF ENOUGH THAT ENTIRE COLUMN IS BELOW FREEZING. THUS AS SFC TEMPS DROP BELOW FREEZING EARLY THIS EVENING ANY HYDROMETEORS REACHING THE GROUND MAY BE IN THE FORM OF FREEZING RAIN. ATTIM NO REPORTS TO CONFIRM/DENY THOUGHT BUT MAY MENTION SOME FREEZING SPRINKLES WRN ZONES THIS EVNG. HOPEFULLY COLUMN SHLD HAVE COOLED ENOUGH THAT BY TIME PCPN REACHES CNTRL ND PCPN WL BE ALL SNOW. AMOUNTS WL BE LGT AND WL GO CAT POPS ONLY FOR NERN ZONES...FM MOT EWD...AND MENTION AMTS LESS THAN AN INCH. WL STICK WITH POPS ELSEWHERE ACROSS CNTRL ZONES FOR NOW...AND ONLY FLURRIES/PSBL FREEZING SPRINKLES WEST. WL ALSO MENTION SOME LINGERING FLURRIES FAR ERN ZONES SUN MRNG. ANOTHER PROBLEM MAY BE AREAS OF FOG SO WL MENTION FOG FOR AREAS ALONG AND EAST OF CURRENT TROF POSN. LOW CLOUDS WL KEEP TEMPS WARMER THAN PREV FCST OVER CNTRL AND ERN ZONES SO RAISED OVER NIGHT LOWS THESE AREAS. BEYOND FIRST AND EARLY SECOND PDS LTTL OR NO CHANGES TO GOING FCST. MILD WORDING ON MONDAY LOOKS GOOD AS UPR RDG BUILDS OVER RGN WITH GOOD WLY FLOW AS SFC LOW REMAINS WELL NORTH OF AREA. IN THE EXTENDED...GENERALLY ZONAL FLOW WITH SERIES OF WK IMPULSES THROUGH PD. PERHAPS A LTL MORE SIG TROF IND BY MRF FOR FRI-SAT PD BUT WITH UNCERTAINTY IN FAST ZONAL FLOW WILL KEEP A DRY FCST THROUGH EXTENDED PD. .BIS...NONE. TWH nd AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1015 AM MST SAT DEC 15 2001 CDFNT SLOWLY SLIDING THROUGH SRN HALF OF CWFA ATTM. THE UPPER TROF AND POST FRONTAL PCPN STILL W OF CWFA...AND THE TENDENCY HAS BEEN TO SLOW ITS EWD MOVEMENT. 12Z ETA/15Z RUC NOT IMPRESSIVE WITH EITHER OMEGA OR RH FIELDS ACRS CWFA...REALLY NOT MUCH TO GET EXCITED ABOUT. THUS HAVE LOWERED POPS AND PUSHED BACK PCPN TIMING TO EXTEND INTO 'TONIGHT' PD. LOW FROUDE NUMBERS AND LACK OF RH SHOULD KEEP UPSLOPE SNOW OVER THE NRN HILLS TO A MINIMUM. WITH SLOWER PROGRESSION OF TROF...STRONGER WINDS WILL CONTINUE INTO THIS EVENING ACRS SD ZONES. HOWEVER...MAX 850MB WINDS OF 35-40KTS SHOULD KEEP WINDS BELOW ADVISORY CRITERIA. .UNR...NONE. JOHNSON sd