AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1200 PM CST TUE FEB 14 2006 .DISCUSSION... FORECAST ON TRACK AND ONLY MINOR UPDATE TO THE FORECAST THIS AFTERNOON. BUMPED UP TEMPS AND SSW WINDS A BIT. AMPLE SUNSHINE THIS AFTERNOON AND BREEZY SSW WINDS 10 TO 20 MPH WITH GUSTS IN THE 20S. HIGHS IN THE 50S WITH WARMEST TEMPERATURES WEST OF A GALESBURG TO SPRINGFIELD LINE AND COOLEST OVER EAST CENTRAL IL. MIDDAY SURFACE MAP SHOWS 1031 MB HIGH PRESSURE OVER FL AND 999 MB LOW PRESSURE OVER LAKE SUPERIOR WITH A FRONTAL BOUNDARY ALONG THE US/CANADIAN BORDER. ANOTHER FRONT EXTENDED SW FROM THE LOW ACROSS FAR NW IOWA INTO CENTRAL NEBRASKA. NICE PRESSURE GRADIENT ACROSS IL WITH SUNNY SKIES HELPING MIX HIGHER WINDS ALOFT TOWARD THE SURFACE. SSW WINDS 10 TO 20 MPH WITH A FEW GUSTS OF 20 TO 25 MPH. NOON TEMPS IN THE UPPER 40S AND LOWER 50S. THIN CIRRUS CLOUDS RACING ESE ACROSS NORTHERN IL NORTH OF I-80. RUC AND NAM TAKE FRONTAL BOUNDARY SE TOWARD THE IA/IL BORDER BY MIDNIGHT. MILD SW BREEZES AHEAD OF IT OVER CENTRAL/SE IL. HIGHS IN THE 50S STILL LOOKS GOOD...WITH LOWER 50S EAST CENTRAL IL AND UPPER 50S SW AREAS AS 850 MB TEMPS ARE GOING UP TO 6 TO 8C THIS AFTERNOON. BUMPED UP HIGHS A BIT...BUT MAY EVEN GET WARMER IN A FEW AREAS. THIN CIRRUS TO GRADUALLY WORK SE INTO CENTRAL IL LATER TODAY...BUT OVERALL A SUNNY AND NICE VALENTINES DAY. && .PREV DISCUSSION... LATEST FORECAST TRENDS CONTINUE TO SUPPORT A MORE WARM/WET FORECAST VERSUS COLD/WET IN THE SHORT TERM. PRIMARY SNOW BAND SHOULD REMAIN NORTH OF THE AREA... WITH FAR NORTHWEST CWA HAVING THE BEST SHOT AT LIGHT SNOW ACCUMULATIONS POST-FROPA THURSDAY EVENING. WILL NEED TO KEEP AN EYE ON POSSIBLE SVR WX ESPECIALLY EAST AND SOUTHEAST THURSDAY AFTERNOON. HYDRO CONCERNS MAY NEED MONITORING DEPENDING ON QPF. POTENTIAL DRY SLOTTING EARLY THURS MAY MITIGATE THIS SOMEWHAT. VERY QUICK TRANSITION TO VERY COLD AIR THURSDAY NIGHT INTO FRIDAY... WITH COLD AIR POSSIBLY RIVALING COLDEST OF THE SEASON SO FAR. SHORT TERM...TODAY THROUGH FRIDAY... WEAK SFC LOW AND ATTENDANT COLD FRONT WILL MOVE ACROSS LAKE SUPERIOR TODAY... COLD FRONT WILL EVENTUALLY STALL OUT ACROSS NW ILLINOIS TONIGHT... WITH BAROCLINIC ZONE SHARPENING UP INTO WEDNESDAY AS POLAR VORT OVER HUDSONS BAY RETROGRADES INTO THE CANADIAN PRAIRIES... ALLOWING ARCTIC AIR TO BEGIN FILTERING INTO THE UPPER MIDWEST. FOR TODAY... JUST A FEW HIGH AND MID CLOUDS TO SCRAPE BY THE FAR NORTHERN CWA. SUBTLE MID-LEVEL SPEED MAX PASSING THROUGH THE FOUR CORNERS REGION INTO THE PLAINS WILL RESULT IN WEAK LEE CYCLOGENESIS OVER THE TX PANHANDLE... WHILE MORE SIGNIFICANT TROUGH MOVES INTO THE PACIFIC NORTHWEST. WEAK INITIAL CYCLOGENESIS OVER THE PLAINS... ALONG WITH HIGH PRESSURE SHIFTING EAST OFF FLORIDA... WILL ALLOW FOR LOW LEVEL FLOW TO BACK AND DEEPEN THIS AFTERNOON. STRONG WAA WILL RESULT. DESPITE STRONG INVERSION WITH MIXING ONLY TO ABOUT 950-925 MB... SHOULD STILL SEE TEMPS REACH THE LOW TO MID 50S ACROSS MUCH OF THE AREA... POSSIBLY STAYING IN THE UPPER 40S IN THE FAR NORTHEAST. DEEPENING SOUTHERLY FLOW WILL BE EVIDENCED BY 925MB WINDS CRANKING UP TO 40 KTS BY THE AFTERNOON... HOWEVER STRONG INVERSION SHOULD LIMIT DOWNWARD MOMENTUM XFER... SO SHOULD ONLY SEE RELATIVELY MODEST GUSTS IN THE 20-25 MPH RANGE THIS AFTERNOON. WED/THU SYSTEM. SOME MODEL DIFFERENCES CONTINUING WITH THE 00Z/14 SUITE. ETA BEGINNING TO COME MORE IN LINE WITH STRENGTH OF UPPER SHORTWAVE... HOWEVER THE OVERALL UPPER PATTERN BEYOND ABOUT 48 HOURS REMAINS UNDER-AMPLIFIED. ETA KEEPS POLAR VORT OVER MB... WITH NO RIDGING OVER THE NORTHEASTERN STATES THURSDAY. THIS LEADS TO A SFC LOW TRACK FARTHER SOUTH AND EAST. IN ADDITION... ETA NOT QUITE AS SHARP WITH UPPER SHORTWAVE GOING INTO THURSDAY... RESULTING IN WEAKER SFC LOW. THE TREND HOWEVER... HAS BEEN TO AMPLIFY OVERALL PATTERN IN TIME... RESULTING IN A SFC LOW TRACK SHIFTING FARTHER NORTH AND WEST WITH TIME. AS SAID BEFORE... THIS PROBLEM HAS BEEN NOTED ALL WINTER WITH THE ETA/NAM... AND EXPECT THAT IT WILL CONTINUE TO COME IN LINE AS SYSTEM GETS IN TO THE 24-36 HOUR TIME FRAME. GFS HAS BEEN TRENDING TOWARDS A MORE NORTH AND WEST TRACK... WITH A HIGHLY AMPLIFIED UPPER PATTERN BY THURSDAY. POLAR VORT CENTERED OVER SK... AND BROAD MID-LEVEL RIDGING ACROSS THE NORTHEAST. AS UPPER SHORTWAVE PIVOTS AROUND THE FARTHER-WEST POLAR VORT... IT BECOMES NEGATIVELY TILTED. GFS IS ALSO MUCH STRONGER WITH JET STREAM PUSHING ACROSS GREAT PLAINS ON THU... WITH COUPLED JET SETUP FAVORING STRONGER CYCLOGENESIS OVER THE MIDWEST ON THURSDAY. ECMWF/UKMET NOT QUITE AS FAR NW AS GFS. 00Z RUN OF THE ENVIRONMENT CANADA GLOBAL MODEL MORE IN LINE WITH ETA... BUT IS RATHER INCONSISTENT WITH PREVIOUS RUNS. PERHAPS MOST NOTABLE IS THAT GFS ENSEMBLES FAVOR THE OP GFS RUN... WITH ABOUT 1/3 OF THE MEMBERS MORE ALONG THE LINES OF ECMWF/ETA SFC LOW TRACK. CONSIDERING THE TRENDS... WILL TEND TO SIDE WITH OP/ENSEMBLE MEAN GFS FOR THIS PACKAGE. THIS RESULTS IN VERY FEW CHANGES TO PRECIP TYPE FORECAST. STILL LOOKS LIKE WEDNESDAY NIGHT WILL SEE RAIN SHOWERS BREAKING OUT WITH PLENTY OF ISENTROPIC LIFT INITIALLY FOCUSED ACROSS THE SOUTHEAST... THEN EXPANDING NORTHWARD AS LLJ CRANKS UP AND BEGINS TO INTERSECT THE STALLED OUT FRONT ACROSS FAR NW ILLINOIS. DEPENDING ON HOW QUICKLY THE SYSTEM MATURES... COULD SEE SOME DRY SLOTTING ISSUES IN THE FAR SE LATE WEDNESDAY NIGHT. PRECIP COULD BE SOMEWHAT EPISODIC IN NATURE ESPECIALLY THURSDAY... AS DRY SLOTTING MAY SHUT OFF PRECIP SOUTHEAST OF A CMI-DEC-SPI LINE. THEN COLD FRONT MOVES THROUGH. OUT AHEAD OF IT... LLJ WINDS UP TO 55-60KT AGAIN... H5 WINDS INCREASE TO 70-80 KT AHEAD OF APPROACHING SHORTWAVE TROUGH. GFS SUGGESTS 0-6KM BULK SHEAR INCREASING TO 65-70 KT THURSDAY AFTERNOON. STRONG LARGE-SCALE ASCENT ALONG COLD FRONT SHOULD COMPENSATE FOR MODEST INSTABILITY. COLD AIR MOVES IN RAPIDLY BEHIND STRONG COLD FRONT. NICE SNOW BAND SHOULD SET UP... BUT SHOULD BE DISPLACED TO OUR NORTH OVER THE UPPER MIDWEST. SOUTHERN EDGES OF DEFORMATION SNOW REGION MAY SCRAPE BY OUT FAR NORTHWEST CWA... BUT THIS CONTINUES TO LOOK LESS LIKELY IN TIME. ALL LOCATIONS WILL HAVE THE CHANCE OF SEEING SOME SNOW IN CYCLONIC FLOW AND COLD ADVECTION THURSDAY NIGHT INTO FRIDAY... BUT ACCUMULATIONS NOT EXPECTED TO BE SIGNIFICANT AT THIS TIME... BUT MAIN RISK CONTINUES TO BE NORTHWESTERN CWA... WILL GO WITH UP TO 1/2 INCH IN THE SNOW GRIDS FAR NORTHWEST FOR NOW. AS FOR PRECIP FORECAST... STILL HEDGING WITH RAIN OR SNOW WORDING LATE THU AFTERNOON IN THE FAR NORTHWEST... SYSTEM IS STILL A FEW DAYS OUT... AND WE ARE DEALING WITH A VERY SHARP BAROCLINIC ZONE HERE... WITH COLD AIR AMASSED JUST BARELY TO OUR WEST ON THURSDAY AFTERNOON. SO IT IS IMPORTANT TO STRESS THAT CHANGES COULD STILL BE MADE... BUT CONFIDENCE IN THE GOING FORECAST IS INCREASING. WILL GO WITH LIGHT SNOW WORDING MARCHING WEST TO EAST THURSDAY NIGHT. LIGHT SNOW SHOWERS OR FLURRIES COULD LINGER INTO FRIDAY. WILL MENTION THUNDER LIKELY IN THE EAST THURSDAY AFTERNOON. TRIED NOT TO GET TOO CUTE WITH POPS... BUT STARTED A TREND WHICH REFLECTS POSSIBILITY OF DRY SLOTTING SHUTTING PRECIP OFF FOR A TIME IN THE EAST AND SOUTHEAST FOR THE FIRST PART OF THURSDAY. LONG TERM...SATURDAY THROUGH MONDAY... STRONG CAA WILL HIGHLIGHT THE WEEKEND...WITH NEARLY THE COLDEST AIR OF THE SEASON SETTLING ACROSS CENTRAL IL. H85 TEMPS WILL DROP INTO THE -18 TO -21C RANGE BY NOON SATURDAY. WIND CHILL READINGS WILL NOT BE TOO BAD AS WINDS WEAKEN UNDER THE SURFACE RIDGE AXIS...WHICH IS EXPECTED TO PUSH ALMOST DIRECTLY OVER OUR CWA. CLEARING SKIES ON SATURDAY WILL ALLOW FOR CRISP CLEAR SKIES...BUT WITH LOW SUN ANGLES...NOT MUCH WARMING IS EXPECTED. CLEAR SKIES SUNDAY MORNING WILL ALLOW TEMPS TO DIP BETWEEN 0 AND 5 ABOVE IN OUR NW ZONES. SOME OF THE TYPICAL COLD SPOTS MAY EVEN SEE READINGS BELOW ZERO...BUT HELD OFF ON GOING BELOW GUIDANCE AT THIS POINT. IN COLLABORATION... HAVE KEPT TEMPS AOA MEX GUID FOR NOW. LITTLE TO NO SNOW COVER WILL ALSO WORK TO KEEP TEMPS FROM PLUMMETING TOO FAR AS WELL. WILL WAIT TO SEE HOW MUCH THE AIRMASS MODIFIES IN FUTURE MODEL RUNS BEFORE GOING THAT COLD. THE GFS AND ECMWF ARE HINTING AT THE NEXT PRECIP CHANCES COMING SUNDAY NIGHT THROUGH MONDAY NIGHT... AS A LOW PRESSURE SYSTEM IN THE SOUTHERN STREAM LIFTS FAR ENOUGH NORTH TO AFFECT CENTRAL ILLINOIS. WILL GO LIGHTLY INTO THIS SCENARIO...SEEING HOW MUCH THE EXTENDED MODELS ALTERED SATURDAYS FCST FROM A SNOW STORM WHEN IT WAS DAY 7...SO PARTLY CLOUDY AS DAY 5. THUS...JUST 20 POPS FOR SNOW AT THIS POINT. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HUETTL/HARDIMAN LONG TERM...SHIMON il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 655 PM EST TUE FEB 14 2006 .AVIATION... FIRST CONCERN LIES WITH POTENTIAL FOR LLWS EARLY IN PERIOD. A FEW TAMDAR/ACARS SOUNDINGS AS WELL AS PROFILERS NOT QUITE AS STRONG WITH 925MB LEVEL SW WINDS AS RUC/NAM12 SUGGESTS SO WILL FORGO MENTION FOR NOW BUT CONTINUE TO MONITOR FOR NEED FOR POSSIBLE UPDATE. TOWARD DAYBREAK AS FRONT MOVES INTO KSBN BEGIN TO REALIZE SUBSTANTIAL COOLING 1KFT-3KFT LAYER LEADING TO SATURATION/MVFR SC FORMATION. SOME POTENTIAL FOR LOWERING TO IFR DURING THE AFTERNOON AS INVERSION HEIGHTS LOWER...HOWEVER BEING SO FAR INTO FORECAST PERIOD WILL DEFER AN IFR FORECAST TO NEXT MODEL RUN/ISSUANCE. && .SHORT TERM... TONIGHT AND WEDNESDAY WARMER AIR ALOFT TODAY APPEARS TO BE HINDERING MIXING OF STRONGER WINDS TO THE SFC, SO HAVE THUS HAVE BACKED DOWN ON WIND GUSTS THIS EVE. CDFNT OVER IA THIS AFTN WILL MOVE EAST INTO NWRN PORTION OF CWA BY 12Z WED. LITTLE MOISTURE AVLBL FOR THIS FRONT AND ONLY WK FORCING, SO IT WILL MOVE INTO THE AREA DRY WITH ONLY INCRSG CLOUDS FM NW-SE OVERNIGHT. SW WINDS WILL GRDLY DIMINISH OVERNIGHT AS GRADIENT WEAKENS, BUT SOME MIXING WILL CONTINUE SE OF THE FRONT SO GENERALLY WENT A LITTLE ABOVE MOS TEMPS IN THAT AREA. ON WED THE FRONT WILL MOVE SLOWLY SE ACROSS THE CWA AS IT BECOMES PARALLEL TO THE MID LEVEL FLOW. H85 WINDS WILL BACK AND STRENGTHEN TO THE SOUTH OF THE FRONT IN RESPONSE TO DEEPENING LOW PRESSURE SYSTEM OVER THE SRN ROCKIES. THIS MAY LEAD TO SOME OVERRUNNING -RW ACROSS SRN PORTION OF THE CWA TOWARD EVE. WITH FRONT IN THE AREA, MORE CLOUDINESS, AND LESS MIXING, HIGH TEMPS OVER MOST OF THE CWA SHOULD BE CONSIDERABLY LOWER THAN TODAY RANGING FROM THE U30S NW TO THE M40S SE. && .LONG TERM... WEDNESDAY NIGHT THROUGH TUESDAY A VERY BUSY LONG TERM TODAY WITH A LITTLE OF EVERYTHING COMING IN THE NEXT 5 DAYS. CONCERNS REVOLVE AROUND FZRA POTENTIAL WED NGT AND THEN SEVERE WEATHER POTENTIAL THURSDAY EVENING FOLLOWED BY THE COLDEST AIR OF THE WINTER SEASON FOR FRI INTO THE WEEKEND. NORTHERN HEMISPHERIC WATER VAPOR IMAGERY TODAY SHOWING FLOW UPSTREAM OVER THE NORTHERN PACIFIC BECOMING HIGHLY AMPLIFIED AS A RIDGE DEVELOPS ALL THE WAY ACROSS ALASKA AND INTO THE HIGH ARCTIC. IN FACT THIS RIDGE IS BRIDGING ACROSS THE POLAR REGIONS TO ANOTHER POSITIVE ANOMALY OVER THE CENTRAL ASIAN CONTINENT. THIS HAS SET THE STAGE FOR TRUE CROSS POLAR FLOW WHICH WILL AID IN DELIVERING THE COLDEST AIR OF THE 2005/2006 WINTER THUS FAR TO THE REGION THIS WEEKEND. BEFORE THAT LOTS OF CONCERNS TO DEAL WITH HOWEVER. FIRST CONCERN REVOLVES AROUND THE FIRST OF TWO SIGNIFICANT WAVES OF ENERGY TO RIPPLE ALONG THE EVER TIGHTENING BAROCLINIC ZONE WHICH WILL DEVELOP IN THE SHORT TERM ACROSS THE REGION. NAM/GFS COMING INTO GOOD AGREEMENT IN SPREADING A SIGNIFICANT WAVE OF ISENTROPIC UPGLIDE OVER THE SHARPENING BOUNDARY WED NGT IN RESPONSE TO DIGGING UPSTREAM TROUGH AND BACKING OF MID LEVEL FLOW ATOP THE LOW LEVEL BOUNDARY. AMPLE MOISTURE BEING ADVECTED ACROSS THE FRONTAL ZONE BY A BURGEONING LOW LEVEL JET WITHIN THE DEVELOPING WARM SECTOR. EXPECT PRECIP TO BREAK OUT AND SPREAD ACROSS THE REGION WED EVENING. MOST OF THE CWA WILL REMAIN WARM ENOUGH FOR ALL RAIN...BUT PRECIP TYPE A CONCERN ACROSS THE FAR NORTHERN COUNTIES WHERE LOW LEVEL NE FLOW WILL STRENGTHEN TO THE NORTH OF THE SHARPENING BAROCLINIC ZONE. NAM 2 METER TEMPS ARE MARGINAL WITH AROUND 32F ACROSS THE NORTHERN 1-2 TIERS OF COUNTIES. BETTER ZR POTENTIAL WILL LIE FARTHER NORTH INTO MICHIGAN WHERE LOW LEVEL TEMPS WILL BE SEVERAL DEGREES BELOW FREEZING. STILL FEEL POTENTIAL JUSTIFIES MENTION IN THE FORECAST. ON THURSDAY EXPECT TEMPS TO RISE WELL ABOVE FREEZING EVEN ACROSS THE NORTH...ENDING ANY ZR CHANCE. ON THURSDAY SCREAMING WAA IN THE LOW LEVELS WILL HELP TO PUSH THE SURFACE FRONT SLOWLY NORTH ACROSS THE CWA. THERE WILL LIKELY BE A PHENOMENAL TEMPERATURE GRADIENT ACROSS THE CWA WITH HIGHS REACHING INTO AT LEAST THE MID 50S ACROSS THE SOUTHEAST COUNTIES...WHILE THE FAR NORTH MAY END UP STUCK IN LOW LEVEL NE FLOW ALL DAY WITH TEMPS STRUGGLING TO REACH 40. OF LARGER CONCERN IS THURSDAY EVENING. BOTH NAM/GFS DEVELOP A PLUME OF ELEVATED INSTABILITY WITHIN THE WARM SECTOR UPSTREAM ON THURSDAY AFTERNOON. WITH SURFACE TEMPS RISING WELL INTO THE 50S WITHIN THE WARM SECTOR MAIN QUESTION WILL BECOME HOW MUCH LOW LEVEL MOISTURE RETURN DEVELOPS WITHIN THE WARM SECTOR. SPC NOTED THAT THE GULF IS DOMINATED BY CONTINENTAL AIR THIS AFTERNOON...WHICH MAY DELAY GULF RETURN. FLOW IS EXTREMELY STRONG WITH 100+KTS AT 500MB PUNCHING IN JUST BEHIND THE COLD FRONT. DYNAMICS AND FLOW WOULD SUGGEST POTENTIAL OF A FORCED LOW TOPPED SQUALL LINE EVENT ALONG THE COLD FRONT. IF ANY INSTABILITY IS ABLE TO DEVELOP IN THE WARM SECTOR...STRONG DAMAGING WINDS WOULD BE LIKELY WITH THIS FORCED LINE. AT THIS TIME MOST LIKELY PORTION OF THE CWA TO EXPERIENCE THIS WOULD BE THE AREA BREAKING INTO THE WARM SECTOR ON THURS...THE SOUTH AND ESPECIALLY SOUTHEAST. THIS IS STILL A FEW DAYS AWAY HOWEVER AND EXACT DETAILS ARE STILL HARD TO PIN DOWN. PLEASE REFER BACK TO OUR HWO AND SPC SEVERE WEATHER OUTLOOKS IN THE COMING DAYS ON THIS. FOLLOWING THE INTENSE COLD FRONT THURS NIGHT THE COLDEST AIR OF THE WINTER WILL BLAST INTO THE REGION WITH TEMPS FREE FALLING DOWN INTO AT LEAST THE LOW TO MID 20S BY 12Z FRI. THIS MAY DEVELOP A FLASH FREEZE SCENARIO WITH ANY WATER REMAINING ON THE SURFACE QUICKLY FREEZING. SNOW LOOKS LIMITED IN THE WRAP AROUND MOISTURE FIELD WITH THE BULK OF FORCING WITHIN THE WARM AIR. COULD SEE UP TO AN INCH OR SO OF SNOW...BUT NOT MUCH MORE. SYNOPTIC SCALE WINDS WILL BECOME VERY STRONG FOLLOWING FROPA ESPECIALLY IN LIGHT OF MODEL DEPICTION OF MID LEVEL DRY SLOT DEVELOPING ATOP STRONG LOW LEVEL CAA. COULD EASILY SEE AT LEAST ADVISORY CRITERIA WINDS LATE THURS NGT INTO FRIDAY AND GALES ON THE LAKE. INTO THE WEEKEND HIGHS ON SAT ONLY EXPECTED TO BE IN THE TEENS AS THE HEART OF THE COLD CORE CROSSES THE REGION. LAKE EFFECT POTENTIAL LOOKS LIMITED DESPITE COLD AIR DUE TO VERY DRY NATURE OF THE AIRMASS AND SURFACE RIDGE QUICKLY BUILDING IN. INTO EARLY NEXT WEEK A SLOW MODERATING TREND BUT STILL BELOW NORMAL TEMPS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...JT LONG TERM...HITCHCOCK AVIATION...MURPHY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 218 PM MST TUE FEB 14 2006 .DISCUSSION... 17Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED ZONAL FLOW AS TROUGH WAS DROPPING SOUTH ACROSS THE PAC NORTHWEST. AT THE SFC...COLD FRONT WAS SLOWLY WORKING ITS WAY ACROSS NEBRASKA AND WAS DRAPED ACROSS CENTRAL NEBRASKA AT 17Z. BOTH THE NAM AND GFS APPEARED TO HAVE INTIALIAZED THE 100+KT H3 JET STREAK TO FAR WEST THIS MORNING WHEN COMPARED TO SALEM RAOB. GFS DID MUCH BETTER AT H5 ALTHOUGH THERE WERE SMALLER ERRORS ACROSS THE PAC NORTHWEST. NAM SEEMED TO HAVE LOTS OF PROBLEMS PLACING THE PAC NW H5 SHORTWAVE AND WAS TO FAR NORTH AND WEST WITH THE FEATURE. ALTHOUGH MAGNITUDE OF THE ERRORS IS RATHER SMALL...CONFIDENCE IS A BIT LOWERED IN THE LATTER PERIODS OF THE SHORT TERM DUE TO THE INIT PROBLEMS. SHORT RANGE MODELS ALL BEGINNING TO TREND FURTHER NORTH WITH WEDNESDAY NIGHT SYSTEM AND WILL MAINLY LEAN TOWARDS THE GFS WITH THIS SYSTEM. TONIGHT/TOMORROW...MAIN CONCERN TONIGHT WILL BE FOG -FZDZ POTENTIAL OVERNIGHT AS COLD FRONT SLIDES ACROSS THE AREA OVERNIGHT. UPSTREAM DEWPOINTS IN THE UPPER 20S/LOW 30S INDICATE LOTS OF LOW LEVEL MOISTURE BEHIND THE FRONT BUT MIDLEVELS ARE VERY DRY. WITH LOTS OF TRAPPED MOISTURE...UPSLOPE FLOW AND INCREASING H85-H7 WAA AFTER 09Z THINK THE POTENTIAL FOR -FZDZ IS PRETTY GOOD. QUESTION WILL BE HOW MUCH COVERAGE/INTENSITY OF DRIZZLE. BEST FORCING WILL BE ACROSS THE NORTH WHERE ISENTROPIC LIFT IS MAXIMIZED...BUT THIS IS ALSO GETTING CLOSE TO AREA WHERE SNOW DEVELOPMENT IS POSSIBLE. CONSIDERED A WINTER WX ADVISORY FOR NORTHEAST CWA FOR -FZDZ...BUT STILL NOT SURE OF HOW WIDESPREAD THIS WILL BE AND WILL HOLD OFF FOR NOW. LINGERING FOG/DZ WILL HANG AROUND THROUGH THE MORNING BEFORE DISSIPATING IN THE AFTERNOON. H7 FRONT SHIFTS WELL TO THE NORTH OF THE CWA DURING THE AFTERNOON WED NIGHT-THURSDAY...MAIN CHALLENGE WILL BE PRECIP TYPE AND POPS THROUGH THE EVENING. AS MENTIONED BEFORE...ACTIVE MID LEVEL FRONT SHOULD REMAIN WELL TO THE NORTH OF THE AREA OVERNIGHT BEFORE BEGINNING TO MOVE SOUTH LATE. INITIAL CONCERN WILL BE FOR FREEZING PRECIP OVERNIGHT. MIDLEVELS WARM AND VERY DRY THROUGH 09Z WITH A RELATIVELY DEEP SUPERCOOLED LAYER. STRONG H85 AND H7 WAA COUPLED WITH APROACHING JET STREAK SHOULD PROVIDE PLENTY OF LIFT FOR LIGHT PRECIP. NOT EXPECTING ANY SIGNIFICANT AMOUNTS...BUT WITH THE DEGREE OF LIFT DECIDED TO CHANGE PRECIP TO -FZRA INSTEAD OF DRIZZLE AND BUMP UP POPS SOME. PRECIP SHOULD CHANGE OVER TO SNOW LATE AS SYSTEM BEGINS TO EJECT EAST. WILL SEE A BRIEF WINDOW OF STRONG MID LEVEL FRONTOGENESIS THURSDAY MORNING. STABILITY PROFILES ABOVE THE FRONTAL SURFACE SHOW WEAK STATIC STABILITY AND SOME POTENTIAL SYMMETRIC INSTABILITY. THINK THAT NORTH/NORTHEAST CORNER MAY SEE A BRIEF WINDOW OF MODERATE TO HEAVY SNOW AS THE FRONT MOVES EAST. UPPED POPS AND QPF AMOUNTS IN THIS AREA TO ACCOUNT FOR THIS. FRIDAY...WEAK UPSLOPE IN THE MORNING SHOULD YIELD SOME MORNING FOG IN THE WEST...WHILE AREA OF H7 WAA WILL PROVIDE ENOUGH LIFT FOR A FEW FLURRIES IN THE AFTERNOON. CURRENT FORECAST HANDLES THIS WELL AND DIDNT MAKE ANY CHANGES. IN THE EXTENDED...TEMPS AND PRECIP CHANCES CONTINUE TO BE THE PRIMARY CHALLENGE THROUGHOUT THE EXTENDED. BOTH THE 06Z GFS/ECMWF VERY SIMILAR THROUGH SUNDAY AND HAVE DECENT ENSEMBLE SUPPORT. LARGE DIFFERENCES BEGIN TO APPEAR FROM MONDAY ON...AND ENSEMBLE MEMBERS ALL OVER THE PLACE WITH PLACEMENT OF WEST COAST TROUGH THAT CONFIDENCE IS VERY LOW. ONLY THING MODELS SEEM TO AGREE ON IS THAT COLD AIR SHOULD STAY IN PLACE THROUGHOUT THE PERIOD AND WILL KEEP TEMPS WELL BELOW NORMAL. WITH MODELS TENDING TO HAVE COLD AIR MORE FIRMLY IN PLACE OVER CWA HAD TO MAKE SOME MINOR CHANGES TO GOING FORECAST. FIRST WITH SURFACE FRONT WELL TO OUR SOUTH...LARGE SCALE OVERRUNNING/WAA WILL BE IN PLACE ON SATURDAY. HARD TO REALLY FINE TUNE ONE PARTICULAR SPOT FOR PRECIP SO WILL COVER AREA WITH LOW CHANCE POPS FOR NOW. ON SUNDAY...EVEN MORE INTENSE LOW LEVEL WAA GETS GOING BUT MID-LEVELS BEGIN TO DRY OUT. GFS SOUNDINGS POINT TO -FZDZ BEING THE MAIN PRECIP TYPE AND WILL GO AHEAD AND INCLUDE IN THE SUNDAY FORECAST. WITH SIMILAR FLOW THROUGH THE BEGINNING OF THE WEEK...COULD REALLY INCLUDE POPS EVERY DAY. HOWEVER DUE TO THE UNCERTAINTY AM GOING TO KEEP MON-TUESDAY DRY FOR NOW. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JRM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1014 PM EST TUE FEB 14 2006 .UPDATE...SFC ANALYSIS REVEALING LOW PRESSURE OVER EASTERN LAKE SUPERIOR/SOUTHERN ONTARIO AND COLD FRONT EXTENDING INTO NW WISCONSIN. TIGHT THERMAL GRADIENT ASSOCIATED WITH THE FRONT WITH TEMPS IN THE SINGLE DIGITS IN ONTARIO AND THE NRN PLAINS...40S AND 50S JUST OFF TO OUR SOUTH. STRONG BAROCLINIC ZONE AND RESULTING FRONTOGENESIS/DEFORMATION PROCESSES THE MECHANISM THIS EVENING FOR OUR NARROW PRIVATE LITTLE SNOW STORM LATE THIS AFTERNOON AND THIS EVENING. 18Z AND 00Z MODEL SOLUTIONS AS WELL AS SUBSEQUENT RUC80 RUNS ACTUALLY PINNED THIS EVENT FAIRLY WELL...DEPICTING STRONG FRONTOGENESIS DEVELOPING OVER THE REGION AND A RESPONSE FOCUSED IN A NARROW CORRIDOR AROUND GRAND TRAVERSE BAY UP INTO NW AND NORTH CENTRAL LOWER MICHIGAN (AROUND CHARLEVOIX/ANTRIM/OTSEGO COUNTIES). KAPX/KGRB RADARS SHOWING THE RESULTS WITH A COUPLE OF FOCUSED BANDS OF HEAVY PRECIP EXTENDING FROM AROUND GREEN BAY UP INTO NRN LOWER MICHIGAN. SNOWFALL RATES WITHIN THESE BANDS VERY IMPRESSIVE...RUNNING 1-2 INCHES PER HOUR. IN FACT...LAKE ANN IN LEELANAU COUNTY (WHERE SNOWFALL HAS BEEN MOST PERSISTENT) REPORTED 8 INCHES IN THE LAST 8 HOURS...4 INCHES SINCE 7 PM. ONE CAVEAT HOWEVER...BOUNDARY LAYER JUST WARM ENOUGH NEAR THE LAKE MICHIGAN COAST TO GET A CHANGEOVER TO RAIN AT FRANKFORT AND MANISTEE THIS EVENING...WHILE JUST ABOUT EVERYONE ELSE REPORTING SNOW. FOR THE REST OF TONIGHT...00Z NAM AND RUC80 SOLUTIONS SHOWING THE FOCUSED RESPONSE WEAKENING RAPIDLY AFTER THE MIDNIGHT HOUR OR SO...AND THUS EXPECT THE VERY HEAVY BANDS OF SNOW TO QUICKLY DWINDLE IN THE NEXT 2-4 HOURS. COLD FRONT AND COLDER/DRIER AIR WILL THEN BEGIN TO SPREAD INTO THE CWA LATE OVERNIGHT AND WEDNESDAY WITH SOME LINGERING LAKE EFFECT SNOW SHOWERS THROUGH WEDNESDAY. ALL IN ALL...CURRENT HEAVY SNOW WARNING/SNOW ADVISORY WORKING OUT FINE. AS MENTIONED...WARNING CRITERIA SNOWFALL ALREADY REPORTED FROM LEELANAU COUNTY AND STILL A FEW MORE HOURS OF HEAVY SNOW TO GO. SO WILL UP THE TOTAL NIGHTTIME SNOW AMOUNTS ACROSS THIS AREA TO THE 6 TO 12 INCH RANGE. NOT NEARLY AS MUCH SNOW ACROSS BENZIE/GD TRAVERSE COUNTIES THUS FAR (2-5 INCHES REPORTED). BUT AGAIN RECENT RADAR TRENDS SHOWING HEAVIER SNOWFALL FILLING BACK IN ACROSS THESE COUNTIES AND STILL A FEW MORE HOURS OF DECENT SNOW TO GO. FURTHER INLAND...PICKED UP 2-3 INCHES AROUND THE GAYLORD AREA THROUGH 10 PM WITH A COUPLE MORE INCHES TO GO. DID CONSIDER ADDING EMMET/ CHEBOYGAN/PRESQUE ISLE COUNTIES INTO THE SNOW ADVISORY WITH SOME OF THE HEAVIER STUFF GETTING INTO THE SOUTHERN PORTIONS OF THESE COUNTIES. BUT GIVEN THAT IT REALLY DID NOT START SNOWING GOOD THERE UNTIL MID EVENING...BELIEVE 1-3 INCHES SHOULD HANDLE IT THERE. CURRENT WARNING/ADVISORY HEADLINES RUN THROUGH 6AM...ALTHOUGH HEAVIEST SNOW WILL NOT LAST THAT LONG. MIDNIGHT SHIFT SHOULD BE ABLE TO CANCEL/EXPIRE THESE HEADLINES WITH NEXT FORECAST ISSUANCE. ADAM && .UPDATE...CAN NOW EXPOUND A BIT ON RATIONALE FOR THE HEADLINES. TIGHT BAROCLINIC ZONE EMERGING FROM THE NORTHERN GREAT LAKES BACK INTO THE NORTHERN PLAINS WITH SFC TEMPS IN THE SINGLE DIGITS ACROSS ONTARIO AND THE NRN PLAINS...40S AND 50S JUST OFF TO THE SOUTH. ALONG THIS TIGHT THERMAL GRADIENT...INTERESTING NARROW SYNOPTIC SNOW BAND BEGAN TO UNFOLD LATE THIS AFTERNOON FROM NRN LOWER MICHIGAN BACK THROUGH WISCONSIN...COURTESY OF STRONG FRONTOGENETIC/ DEFORMATION PROCESSES. IN FACT...CLASSIC LOOK TO IR SATELLITE DATA THIS EVENING WITH A BAND OF COOLING CLOUD TOPS EXTENDING ALL THE WAY BACK INTO MINNESOTA AND NARROW BAND OF MOD-HEAVY PRECIP OCCURRING ALONG THE SOUTHERN FRINGE OF THE COOLING CLOUD TOPS. 18Z NAM/GFS80 AS WELL AS LATEST RUC80 DATE SUGGEST STRONG RESPONSE WILL REMAIN FOCUSED WITHIN THIS NARROW BAND ACROSS NRN LOWER MICHIGAN THROUGH THE EVENING HOURS BEFORE WEAKENING OVERNIGHT. BASED ON REPORTS OF 3 TO 4 INCHES ALREADY RECEIVED AROUND THE GRAND TRAVERSE BAY AREA (SEE ARBPNSAPX ISSUED AT 7 PM)...ANOTHER 3 INCHES A GOOD BET THIS EVENING PUSHING THIS AREA TOWARD WARNING CRITERIA. FURTHER INLAND AND TO THE NORTH...HAVE SEEN SOME HIGHER RETURNS ON RADAR OVER THE LAST FEW HOURS PROBABLY HELPED OUT BY TERRAIN. HEAVIEST SNOWFALL ALSO APPEARS TO BE SLOWLY PUSHING NORTHWARD JUST A BIT BECOMING FOCUSED BETWEEN M-72 AND M-68. SO BASED ON THESE TRENDS...ISSUED SNOW ADVISORY FOR INLAND COUNTIES NORTH OF M-72. WILL OF COURSE WATCH HOW THIS ALL PLAYS OUT OVER THE NEXT COUPLE OF HOURS FOR POSSIBLE HEADLINE ADDITIONS/UPGRADES...ETC. ADAM && .UPDATE...WILL BE ISSUING FORECAST UPDATE TO ADD HEAVY SNOW WARNING/ADVISORIES TO PORTIONS OF NORTHERN LOWER MICHIGAN THROUGH TONIGHT. ALREADY RECEIVED REPORTS OF OVER 3 INCHES IN LEELANAU AND GD TRAVERSE COUNTY...AND ANOTHER 3 OR SO INCHES ACROSS PORTIONS OF NRN LOWER MICHIGAN A GOOD BET FOR THIS EVENING. ADAM && .PREV DISCUSSION...ISSUED AT 400 PM EST TUE FEB 14 2006 DISCUSSION...SURFACE LOW HAS REACHED CENTRAL LAKE SUPERIOR LATE THIS AFTERNOON. FIRST AREA OF SNOW CONTINUES TO SLOW SPREAD EAST INTO NRN LOWER MICHIGAN...DRIVEN BY WEAK ISENTROPIC ASCENT (I290) AND DPVA FROM THE FIRST OF TWO SHORT WAVES SCHEDULED TO IMPACT THE REGION OVER THE NEXT 12 HOURS. LOWEST VSBY SEEN SO FAR IN REGION OBS HAS BEEN A HALF OF A MILE...BUT VSBYS AT LOCATIONS RECEIVING SNOW HAVE BEEN A MILE OR GREATER MOST OF THE AFTERNOON. RADAR REFLECTIVITIES SUPPORT VSBYS REPORTED BY REGIONAL OBS...ONLY SHOWING A FEW SPECKS OF 28+ DBZ EMBEDDED WITHIN LIGHT TO OCCASIONALLY MODERATE SNOW. AREA OF SNOW DRIVEN BY THE SECOND SHORT WAVE IS GEARING UP OVER CENTRAL WISCONSIN ATTM. MAIN FORECAST ISSUES WILL CONTINUE TO BE POPS AND SNOWFALL POTENTIAL AS THESE TWO SHORT WAVES MOVE THRU THE REGION TONIGHT. WEDNESDAY BRINGS THE CALM BEFORE THE NEXT BIG STORM SLATED TO HIT THE REGION LATE WEDNESDAY NIGHT THRU FRIDAY. TONIGHT...INITIAL SHORT WAVE AND RESULTING AREA OF SNOW WILL CONTINUE TO IMPACT NRN LOWER MICHIGAN ZONES THRU EARLY EVENING... EXITING THE REGION BY MIDNIGHT. ISENTROPIC ASCENT WILL CONTINUE TO LEND SOME SUPPORT TO SNOWFALL PRODUCTION...BUT LIFT WILL BE WEAK AND FLEETING...WITH ONLY AROUND A 30 DEGREE ANGLE BETWEEN THE WINDS AND THE PRESSURE SURFACES AND ONLY DURING A 3 TO 4 HOUR WINDOW FROM AROUND 00Z TO 03Z. MIXING RATIOS DURING THIS TIME WILL BE AROUND 2 G/KG...SUGGESTING UNDER AN INCH OF SNOW POSSIBLE FROM ISENTROPIC CONTRIBUTION ALONE. SECOND SHORT WAVE AND RESULTING AREA OF SNOW WILL TAKE A SIMILAR TRACK THRU NRN LOWER MICHIGAN OVERNIGHT...WITH NO ISENTROPIC ASCENT AVAILABLE FOR ADDITIONAL SUPPORT. TEMP PROFILE WILL BE TOO WARM FOR ANY LAKE CONTRIBUTION (I.E. 850 MB TEMPS OF AROUND -4 C). BOTTOM LINE IS THAT SNOWFALL IS ANTICIPATED TO REMAIN BELOW ADVISORY CRITERIA... BUT LOCATIONS ALONG AND 25 MILES EITHER SIDE OF A LINE FROM MBL TO HIGGINS LAKE TO HARRISVILLE SHOULD SEE AROUND 2 INCHES OF NEW SNOW THROUGHOUT THE NIGHT. THE REST OF THE CWA WILL SEE AROUND AN INCH OF NEW SNOW. LIFT AND MOISTURE ASSOCIATED WITH THIS FEATURE SHOULD EXIT THE REGION JUST BEFORE DAYBREAK...BRINGING AN END TO ACCUMULATING SNOWFALL. TEMPS WILL BE ABOVE NORMAL OVERNIGHT...WITH LOW TEMPS ONLY DROPPING INTO THE LOWER TO MID 20S. WEDNESDAY...A RELATIVELY QUIET WEATHER DAY IS ON TAP (BEFORE BIG SNOW DEVELOPS DURING THE LAST HALF OF THE WEEK). ONLY REMAIN SNOWFALL SHOULD BE ACROSS THE NRN HALF OF THE CWA WHERE JUST A FEW LIGHT SNOW SHOWERS WILL REMAIN POSSIBLE WITHIN A SLIGHTLY DEEPER LOW LEVEL MOISTURE REGIME AS 850 MB TEMPS DROP BACK INTO THE NEGATIVE TEENS BEHIND THE SHORT WAVE. LACK OF DEEP MOISTURE WILL INHIBIT SNOWFALL PRODUCTION FOR LOCATIONS ALONG AND SOUTH OF M 72. THESE LOCATIONS MAY ACTUALLY SEE SOME PARTIAL SUN ON WEDNESDAY...WHILE THE NRN HALF OF THE CWA SHOULD STAY MOSTLY CLOUDY. ABOVE NORMAL TEMPS WILL CONTINUE...AS HIGH TEMPS WARM BACK INTO THE LOWER TO MID 30S. LONGER TERM (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)...THERE IS THE POTENTIAL FOR A SIGNIFICANT WINTER STORM TO AFFECT ALL OF NORTHERN MICHIGAN LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE DETAILS OF THIS SYSTEM WILL BE THE FOCUS OF THE REMAINDER OF THIS PACKAGE. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MODELS CONTINUE TO SPIN UP A DEEPENING AREA OF LOW PRESSURE EARLY WEDNESDAY ACROSS THE ROCKIES AND SWIFTLY TRACK IT NORTHEAST THROUGH THE PLAINS WEDNESDAY NIGHT THEN ACROSS CENTRAL LOWER MICHIGAN THURSDAY NIGHT. WARM AIR ADVECTION/ISENTROPIC ASCENT (I285/290) WILL CRANK UP OUT AHEAD OF THIS SYSTEM LATE WEDNESDAY NIGHT INTO THURSDAY. IN ADDITION...A COUPLED JET CONFIGURATION WILL HELP INTENSIFY THE SYSTEM WITH REGION IN THE RIGHT ENTRANCE REGION OF A 115 KNOT JET AND THE LEFT EXIT REGION OF A 135 KNOT JET LEADING TO LOTS OF UPWARD MOTION (THIS IS ALSO EVIDENT IN Q-VECTOR FIELDS). THERE IS AN EXTREMELY IMPRESSIVE BAROCLINIC ZONE WITH 850 MB TEMPERATURES RANGING FROM -20C OVER CENTRAL UPPER TO NEAR ZERO NEAR THE THUMB OF MICHIGAN. PRECIPITATION TYPE ISSUES MAY CREEP INTO THE FORECAST ACROSS SOUTHEAST ZONES DURING THE DAY ON THURSDAY BUT HAVE OPTED TO CONTINUE WITH ALL SNOW FOR NOW. WINDS WILL INCREASE DUE TO THE VERY TIGHT SURFACE PRESSURE GRADIENT BETWEEN THE 996 MB LOW AND 1050 MB HIGH ACROSS SOUTH CENTRAL CANADA. THIS WILL LEAD TO NEAR BLIZZARD CONDITIONS THURSDAY AFTERNOON AND NIGHT WITH GUSTS OF 35 TO 40 MPH OR HIGHER POSSIBLE. MODELS ARE CRANKING OUT IN EXCESS OF AN INCH OF QPF SO SNOWFALL ACCUMULATIONS COULD BE UPWARDS OF A FOOT OR MORE. THEREFORE...WILL HOIST A WINTER STORM WATCH ACROSS NORTHERN LOWER FOR LATE WEDNESDAY NIGHT INTO THURSDAY NIGHT AND THURSDAY AND THURSDAY NIGHT ACROSS EASTERN UPPER. INITIALLY THE SNOW IS NOT EXPECTED TO BE ESPECIALLY HEAVY LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A FEW INCHES EXPECTED. HEAVIEST SNOW WILL LIKELY FALL THURSDAY AFTERNOON AND NIGHT WHEN STRONG FORCING ARRIVES. THE AMOUNT OF ENHANCEMENT IS STILL IN QUESTION AS MODELS DISAGREE IN HOW THERMAL FIELDS WILL EVOLVE (GFS WARMER THAN NAM FOR THE FIRST HALF OF THE EVENT). IF COLDER NAM IS RIGHT THEN THERE COULD BE ENHANCEMENT OFF OF LAKE HURON THROUGH THURSDAY AFTERNOON THEN AS THE WINDS BACK INTO THE NORTH AND NORTHWEST...OFF OF LAKES MICHIGAN AND SUPERIOR THURSDAY NIGHT. FRIDAY...WRAP AROUND MOISTURE WILL LINGER THROUGH THE MORNING WITH MARKED DRYING IN THE AFTERNOON. VERY COLD 850 MB TEMPERATURES FLOOD INTO THE REGION FROM THE NORTHWEST (-20 TO -25C) SO LAKE EFFECT SNOW SHOWERS WILL BE LIKELY. HIGHS SHOULD ONLY STRUGGLE INTO THE TEENS FOR HIGHS. SATURDAY AND BEYOND...MEAN TROUGH WILL CONTINUE TO BE CENTERED ACROSS THE CENTRAL STATES. THIS WILL LEAD TO VERY COLD TEMPERATURES (WITH SOME MODERATION NEXT WEEK) AND A CHANCE FOR LAKE EFFECT SNOW SHOWERS AS UPPER LEVEL DISTURBANCES ROTATE THROUGH THE FLOW. 850 MB TEMPERATURES WILL BE IN THE NEGATIVE TEENS TO NEAR 20C LEADING TO NEARLY IDEAL DELTA TS. THE AMOUNT OF MOISTURE COULD BE A LIMITING FACTOR HOWEVER. WILL CONTINUE TO KEEP THE FORECAST GENERAL WITH CHANCE POPS. HIGHS ON SATURDAY ONLY IN THE TEENS WITH UPPER TEENS AND 20S EXPECTED THEREAFTER. LOWS WILL BE LARGELY DEPENDENT ON CLOUD COVER WITH SINGLE DIGITS ABOVE ZERO WHERE THE CLOUDS HANG ON (ESPECIALLY WEST OF INTERSTATE 75) BUT PLACES WHERE IT CAN PARTIALLY CLEAR...WELL BELOW ZERO READINGS CAN BE EXPECTED. SULLIVAN && .APX...WATCHES/WARNINGS/ADVISORIES...HEAVY SNOW WARNING TONIGHT...MIZ020-025-026. SNOW ADVISORY TONIGHT...MIZ019-021>023-027>029. WINTER STORM WATCH...LATE WEDNESDAY NIGHT TROUGH THURSDAY NIGHT NORTHERN LOWER...WINTER STORM WATCH THURSDAY AND THURSDAY NIGHT EASTERN UPPER. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 745 PM EST TUE FEB 14 2006 .UPDATE...CAN NOW EXPOUND A BIT ON RATIONALE FOR THE HEADLINES. TIGHT BAROCLINIC ZONE EMERGING FROM THE NORTHERN GREAT LAKES BACK INTO THE NORTHERN PLAINS WITH SFC TEMPS IN THE SINGLE DIGITS ACROSS ONTARIO AND THE NRN PLAINS...40S AND 50S JUST OFF TO THE SOUTH. ALONG THIS TIGHT THERMAL GRADIENT...INTERESTING NARROW SYNOPTIC SNOW BAND BEGAN TO UNFOLD LATE THIS AFTERNOON FROM NRN LOWER MICHIGAN BACK THROUGH WISCONSIN...COURTESY OF STRONG FRONTOGENETIC/ DEFORMATION PROCESSES. IN FACT...CLASSIC LOOK TO IR SATELLITE DATA THIS EVENING WITH A BAND OF COOLING CLOUD TOPS EXTENDING ALL THE WAY BACK INTO MINNESOTA AND NARROW BAND OF MOD-HEAVY PRECIP OCCURRING ALONG THE SOUTHERN FRINGE OF THE COOLING CLOUD TOPS. 18Z NAM/GFS80 AS WELL AS LATEST RUC80 DATE SUGGEST STRONG RESPONSE WILL REMAIN FOCUSED WITHIN THIS NARROW BAND ACROSS NRN LOWER MICHIGAN THROUGH THE EVENING HOURS BEFORE WEAKENING OVERNIGHT. BASED ON REPORTS OF 3 TO 4 INCHES ALREADY RECEIVED AROUND THE GRAND TRAVERSE BAY AREA (SEE ARBPNSAPX ISSUED AT 7 PM)...ANOTHER 3 INCHES A GOOD BET THIS EVENING PUSHING THIS AREA TOWARD WARNING CRITERIA. FURTHER INLAND AND TO THE NORTH...HAVE SEEN SOME HIGHER RETURNS ON RADAR OVER THE LAST FEW HOURS PROBABLY HELPED OUT BY TERRAIN. HEAVIEST SNOWFALL ALSO APPEARS TO BE SLOWLY PUSHING NORTHWARD JUST A BIT BECOMING FOCUSED BETWEEN M-72 AND M-68. SO BASED ON THESE TRENDS...ISSUED SNOW ADVISORY FOR INLAND COUNTIES NORTH OF M-72. WILL OF COURSE WATCH HOW THIS ALL PLAYS OUT OVER THE NEXT COUPLE OF HOURS FOR POSSIBLE HEADLINE ADDITIONS/UPGRADES...ETC. ADAM && .UPDATE...WILL BE ISSUING FORECAST UPDATE TO ADD HEAVY SNOW WARNING/ADVISORIES TO PORTIONS OF NORTHERN LOWER MICHIGAN THROUGH TONIGHT. ALREADY RECEIVED REPORTS OF OVER 3 INCHES IN LEELANAU AND GD TRAVERSE COUNTY...AND ANOTHER 3 OR SO INCHES ACROSS PORTIONS OF NRN LOWER MICHIGAN A GOOD BET FOR THIS EVENING. ADAM && .PREV DISCUSSION...ISSUED AT 400 PM EST TUE FEB 14 2006 DISCUSSION...SURFACE LOW HAS REACHED CENTRAL LAKE SUPERIOR LATE THIS AFTERNOON. FIRST AREA OF SNOW CONTINUES TO SLOW SPREAD EAST INTO NRN LOWER MICHIGAN...DRIVEN BY WEAK ISENTROPIC ASCENT (I290) AND DPVA FROM THE FIRST OF TWO SHORT WAVES SCHEDULED TO IMPACT THE REGION OVER THE NEXT 12 HOURS. LOWEST VSBY SEEN SO FAR IN REGION OBS HAS BEEN A HALF OF A MILE...BUT VSBYS AT LOCATIONS RECEIVING SNOW HAVE BEEN A MILE OR GREATER MOST OF THE AFTERNOON. RADAR REFLECTIVITIES SUPPORT VSBYS REPORTED BY REGIONAL OBS...ONLY SHOWING A FEW SPECKS OF 28+ DBZ EMBEDDED WITHIN LIGHT TO OCCASIONALLY MODERATE SNOW. AREA OF SNOW DRIVEN BY THE SECOND SHORT WAVE IS GEARING UP OVER CENTRAL WISCONSIN ATTM. MAIN FORECAST ISSUES WILL CONTINUE TO BE POPS AND SNOWFALL POTENTIAL AS THESE TWO SHORT WAVES MOVE THRU THE REGION TONIGHT. WEDNESDAY BRINGS THE CALM BEFORE THE NEXT BIG STORM SLATED TO HIT THE REGION LATE WEDNESDAY NIGHT THRU FRIDAY. TONIGHT...INITIAL SHORT WAVE AND RESULTING AREA OF SNOW WILL CONTINUE TO IMPACT NRN LOWER MICHIGAN ZONES THRU EARLY EVENING... EXITING THE REGION BY MIDNIGHT. ISENTROPIC ASCENT WILL CONTINUE TO LEND SOME SUPPORT TO SNOWFALL PRODUCTION...BUT LIFT WILL BE WEAK AND FLEETING...WITH ONLY AROUND A 30 DEGREE ANGLE BETWEEN THE WINDS AND THE PRESSURE SURFACES AND ONLY DURING A 3 TO 4 HOUR WINDOW FROM AROUND 00Z TO 03Z. MIXING RATIOS DURING THIS TIME WILL BE AROUND 2 G/KG...SUGGESTING UNDER AN INCH OF SNOW POSSIBLE FROM ISENTROPIC CONTRIBUTION ALONE. SECOND SHORT WAVE AND RESULTING AREA OF SNOW WILL TAKE A SIMILAR TRACK THRU NRN LOWER MICHIGAN OVERNIGHT...WITH NO ISENTROPIC ASCENT AVAILABLE FOR ADDITIONAL SUPPORT. TEMP PROFILE WILL BE TOO WARM FOR ANY LAKE CONTRIBUTION (I.E. 850 MB TEMPS OF AROUND -4 C). BOTTOM LINE IS THAT SNOWFALL IS ANTICIPATED TO REMAIN BELOW ADVISORY CRITERIA... BUT LOCATIONS ALONG AND 25 MILES EITHER SIDE OF A LINE FROM MBL TO HIGGINS LAKE TO HARRISVILLE SHOULD SEE AROUND 2 INCHES OF NEW SNOW THROUGHOUT THE NIGHT. THE REST OF THE CWA WILL SEE AROUND AN INCH OF NEW SNOW. LIFT AND MOISTURE ASSOCIATED WITH THIS FEATURE SHOULD EXIT THE REGION JUST BEFORE DAYBREAK...BRINGING AN END TO ACCUMULATING SNOWFALL. TEMPS WILL BE ABOVE NORMAL OVERNIGHT...WITH LOW TEMPS ONLY DROPPING INTO THE LOWER TO MID 20S. WEDNESDAY...A RELATIVELY QUIET WEATHER DAY IS ON TAP (BEFORE BIG SNOW DEVELOPS DURING THE LAST HALF OF THE WEEK). ONLY REMAIN SNOWFALL SHOULD BE ACROSS THE NRN HALF OF THE CWA WHERE JUST A FEW LIGHT SNOW SHOWERS WILL REMAIN POSSIBLE WITHIN A SLIGHTLY DEEPER LOW LEVEL MOISTURE REGIME AS 850 MB TEMPS DROP BACK INTO THE NEGATIVE TEENS BEHIND THE SHORT WAVE. LACK OF DEEP MOISTURE WILL INHIBIT SNOWFALL PRODUCTION FOR LOCATIONS ALONG AND SOUTH OF M 72. THESE LOCATIONS MAY ACTUALLY SEE SOME PARTIAL SUN ON WEDNESDAY...WHILE THE NRN HALF OF THE CWA SHOULD STAY MOSTLY CLOUDY. ABOVE NORMAL TEMPS WILL CONTINUE...AS HIGH TEMPS WARM BACK INTO THE LOWER TO MID 30S. LONGER TERM (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)...THERE IS THE POTENTIAL FOR A SIGNIFICANT WINTER STORM TO AFFECT ALL OF NORTHERN MICHIGAN LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE DETAILS OF THIS SYSTEM WILL BE THE FOCUS OF THE REMAINDER OF THIS PACKAGE. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MODELS CONTINUE TO SPIN UP A DEEPENING AREA OF LOW PRESSURE EARLY WEDNESDAY ACROSS THE ROCKIES AND SWIFTLY TRACK IT NORTHEAST THROUGH THE PLAINS WEDNESDAY NIGHT THEN ACROSS CENTRAL LOWER MICHIGAN THURSDAY NIGHT. WARM AIR ADVECTION/ISENTROPIC ASCENT (I285/290) WILL CRANK UP OUT AHEAD OF THIS SYSTEM LATE WEDNESDAY NIGHT INTO THURSDAY. IN ADDITION...A COUPLED JET CONFIGURATION WILL HELP INTENSIFY THE SYSTEM WITH REGION IN THE RIGHT ENTRANCE REGION OF A 115 KNOT JET AND THE LEFT EXIT REGION OF A 135 KNOT JET LEADING TO LOTS OF UPWARD MOTION (THIS IS ALSO EVIDENT IN Q-VECTOR FIELDS). THERE IS AN EXTREMELY IMPRESSIVE BAROCLINIC ZONE WITH 850 MB TEMPERATURES RANGING FROM -20C OVER CENTRAL UPPER TO NEAR ZERO NEAR THE THUMB OF MICHIGAN. PRECIPITATION TYPE ISSUES MAY CREEP INTO THE FORECAST ACROSS SOUTHEAST ZONES DURING THE DAY ON THURSDAY BUT HAVE OPTED TO CONTINUE WITH ALL SNOW FOR NOW. WINDS WILL INCREASE DUE TO THE VERY TIGHT SURFACE PRESSURE GRADIENT BETWEEN THE 996 MB LOW AND 1050 MB HIGH ACROSS SOUTH CENTRAL CANADA. THIS WILL LEAD TO NEAR BLIZZARD CONDITIONS THURSDAY AFTERNOON AND NIGHT WITH GUSTS OF 35 TO 40 MPH OR HIGHER POSSIBLE. MODELS ARE CRANKING OUT IN EXCESS OF AN INCH OF QPF SO SNOWFALL ACCUMULATIONS COULD BE UPWARDS OF A FOOT OR MORE. THEREFORE...WILL HOIST A WINTER STORM WATCH ACROSS NORTHERN LOWER FOR LATE WEDNESDAY NIGHT INTO THURSDAY NIGHT AND THURSDAY AND THURSDAY NIGHT ACROSS EASTERN UPPER. INITIALLY THE SNOW IS NOT EXPECTED TO BE ESPECIALLY HEAVY LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A FEW INCHES EXPECTED. HEAVIEST SNOW WILL LIKELY FALL THURSDAY AFTERNOON AND NIGHT WHEN STRONG FORCING ARRIVES. THE AMOUNT OF ENHANCEMENT IS STILL IN QUESTION AS MODELS DISAGREE IN HOW THERMAL FIELDS WILL EVOLVE (GFS WARMER THAN NAM FOR THE FIRST HALF OF THE EVENT). IF COLDER NAM IS RIGHT THEN THERE COULD BE ENHANCEMENT OFF OF LAKE HURON THROUGH THURSDAY AFTERNOON THEN AS THE WINDS BACK INTO THE NORTH AND NORTHWEST...OFF OF LAKES MICHIGAN AND SUPERIOR THURSDAY NIGHT. FRIDAY...WRAP AROUND MOISTURE WILL LINGER THROUGH THE MORNING WITH MARKED DRYING IN THE AFTERNOON. VERY COLD 850 MB TEMPERATURES FLOOD INTO THE REGION FROM THE NORTHWEST (-20 TO -25C) SO LAKE EFFECT SNOW SHOWERS WILL BE LIKELY. HIGHS SHOULD ONLY STRUGGLE INTO THE TEENS FOR HIGHS. SATURDAY AND BEYOND...MEAN TROUGH WILL CONTINUE TO BE CENTERED ACROSS THE CENTRAL STATES. THIS WILL LEAD TO VERY COLD TEMPERATURES (WITH SOME MODERATION NEXT WEEK) AND A CHANCE FOR LAKE EFFECT SNOW SHOWERS AS UPPER LEVEL DISTURBANCES ROTATE THROUGH THE FLOW. 850 MB TEMPERATURES WILL BE IN THE NEGATIVE TEENS TO NEAR 20C LEADING TO NEARLY IDEAL DELTA TS. THE AMOUNT OF MOISTURE COULD BE A LIMITING FACTOR HOWEVER. WILL CONTINUE TO KEEP THE FORECAST GENERAL WITH CHANCE POPS. HIGHS ON SATURDAY ONLY IN THE TEENS WITH UPPER TEENS AND 20S EXPECTED THEREAFTER. LOWS WILL BE LARGELY DEPENDENT ON CLOUD COVER WITH SINGLE DIGITS ABOVE ZERO WHERE THE CLOUDS HANG ON (ESPECIALLY WEST OF INTERSTATE 75) BUT PLACES WHERE IT CAN PARTIALLY CLEAR...WELL BELOW ZERO READINGS CAN BE EXPECTED. SULLIVAN && .APX...WATCHES/WARNINGS/ADVISORIES...HEAVY SNOW WARNING TONIGHT...MIZ020-025-026. SNOW ADVISORY TONIGHT...MIZ019-021>023-027>029. WINTER STORM WATCH...LATE WEDNESDAY NIGHT TROUGH THURSDAY NIGHT NORTHERN LOWER...WINTER STORM WATCH THURSDAY AND THURSDAY NIGHT EASTERN UPPER. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 545 PM EST TUE FEB 14 2006 .DISCUSSION... MAIN FCST CONCERNS INCLUDE LES ACCUMULATION TONIGHT INTO WED OVER NW COUNTIES WITH INITIAL CLIPPER SYSTEM...AND THEN POSSIBLE SIGNIFICANT SNOW THU/THU NIGHT AHEAD OF ARCTIC AIRMASS. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW INITIAL SHORTWAVE APPROACHING FROM WRN ONTARIO. SHORTWAVE ENERGY DIVING INTO PAC NW TROF WILL BE FOCUS FOR DEVELOPING SYSTEM OVER THE SRN PLAINS WED NIGHT INTO THU WHICH COULD BE HEAVY SNOW PRODUCER FOR MUCH OF CWA THU INTO THU NIGHT. AT SFC...LOW PRES OVER NE LAKE SUPERIOR CONTINUES TO TRACK E AND WILL BRING A COLD FRONT OVER NE MN ACROSS UPR MI TONIGHT. MODELS GENERALLY REMAIN IN GOOD AGREEMENT THROUGHOUT FCST PD ON LARGE/SYNOPTIC SCALE FEATURES. TONIGHT INTO WED CONCERN IS POTENTIAL FOR LES OVER NW COUNTIES AS COLD FRONT FM MN SWEEPS ACROSS AREA THIS EVENING. 850 MB TEMPS FALL QUICKLY TO AROUND -18C/-19C OVER WRN LAKE SUPERIOR BY 06Z AND AROUND -16C OVER ERN LAKE SUPERIOR. 21Z UPSTREAM TAMDAR AT KINL SHOWS INVERSION HGT AT AROUND 800 MB WITH -18C TEMP AT BASE OF INVERSION. ALTHOUGH THERE INSTABILITY IS THERE INHIBITING FACTOR FOR GOOD LES BANDS MAY BE DRY AIR APPARENT BLO THE INVERSION FM SFC TO 900 MB. ALSO LOW-LVL FLOW BECOMES QUICKLY ANTICYCLONIC BEHIND COLD FRONT BTWN 06-12Z. THERE WILL LIKELY BE A QUICK SHOT OF SNOW WITH CONVERGENCE ALONG AND BEHIND THE FRONT THROUGH 06Z BUT THEN EXPECT DRIER AIR...ANTICYCLONIC FLOW AND LOWERING INVERSION HGTS PER MODEL SNDGS WILL TAPER LES OFF LATER TONIGHT INTO WED. WOULD EXPECT LES ACCUMULATIONS OF GENERALLY 1 TO 3 INCHES FROM NRN ONTONAGON COUNTY THROUGH KEWEENAW WITH SOME POSSIBLE UP TO 4 INCH ACCUMS OVER A FEW HIGHER TERRAIN AREAS TONIGHT. WITH POOR SNOW GROWTH AND DRIER AIR ADVECTING IN FOR WED HAVE TRIMMED ACCUMS BACK TO AN INCH OR TWO. THE BIG EVENT STILL LOOKS TO BE THU INTO THU NIGHT WITH AS POSSIBLE SIGNIFICANT WINTER STORM TAKING SHAPE OVER THE SRN PLAINS AND HEADING NE TOWARD THE GREAT LAKES. 18Z GFS AND NAM FAIRLY SIMILAR...TRACKING DEVELOPING SFC LOW NEAR SRN TIP OF LAKE MI BY 00Z FRI AND INTO EASTERN ONTARIO LATE FRI NIGHT. 12Z ECMWF AND UKMET SOLNS ARE A BIT FARTHER WEST AND SLIGHTLY SLOWER THAN 18Z GFS TAKING SFC LOW THROUGH SRN LWR MI TO GEORGIAN BAY BY LATE FRI NIGHT. THE ECMWF HAS BEEN A BIT MORE CONSISTENT RUN TO RUN THAN GFS...AND IF THIS MORE WRN TRACK VERIFIES...WOULD MEAN DEEPER MSTR AND LIFT FOR ENHANCEMENT WOULD STAY A BIT LONGER OVER CNTRL AND ERN COUNTIES THU NIGHT. EVEN SO...GFS SOLN STILL SHOWS STRONG 800-700 MB F-GEN FORCING LATE THU INTO THU EVENING FOR HEAVY SNOW OVER CENTRAL AND ERN COUNTIES IN RESPONSE TO STRONG UPR DIVERGENCE IN COUPLED 3H JET STRUCTURE. GFS QPF TOTALS OF .4 TO .7 ALONG WITH LIKELY A HIGHER SNOW/WATER RATIO OF NEAR 20/1 GIVEN COLDER AIRMASS ALREADY IN PLACE WOULD YIELD SNOW TOTALS OF 8 TO 15 INCHES ACROSS CENTRAL AND ERN UPR MI. GOOD DENDRITIC SNOW GROWTH ALSO NOTED ON BUFR SNDGS FM LATE THU INTO THU EVENING. IDEAL ENHANCEMENT AND UPSLOPE NE FLOW ALONG HIGHER TERRAIN OF NCNTRL COUNTIES THROUGH THU NIGHT INTO EARLY FRI WOULD LIKELY BOOST SNOW AMTS EVEN HIGHER. GIVEN TRACK OF QPF SWATH AND BEST FORCING...HAVE DECIDED TO ISSUE WINTER STORM WATCHES FOR ALL COUNTIES FROM IRON-BARAGA EASTWARD TO LUCE COUNTY FOR THU INTO THU NIGHT. AGAIN EXPECT SNOW TOTALS OF 8 TO 12 INCHES OVER SNCNTRL COUNTIES WITH TOTALS IN EXCESS OF A FOOT OVER AREAS ALONG LAKE SUPERIOR. FRIDAY...EXPECT LAKE ENHANCEMENT TO TRANSITION TO PURE LES BY LATE MORNING OVER NCNTRL COUNTIES AS FLOW BEGINS TO BACK NW. WOULD STILL EXPECT THE POTENTIAL FOR SEVERAL MORE INCHES OF SNOW ALONG LAKE SUPERIOR WITH SCT LIGHT SNOW SHOWERS INLAND. FRI NIGHT THROUGH SUN...ARCTIC AIR OF -20 TO -28C AT 850 MB WILL DOMINATE THE AREA BEHIND THE SYSTEM. AS FLOW BACKS A BIT MORE WRLY TEMPS WILL PLUMMET INTO THE DOUBLE DIGITS BLO ZERO FOR INLAND AREAS AT NIGHT AND LIKELY STRUGGLE TO GET ABOVE 10F IN THE INTERIOR W HALF DURING THE DAYTIME. WOULD NOT BE SURPRISED IF WIND CHILL HEADLINES WILL BE NEEDED OVER THE WEEKEND FOR MANY AREAS. CONTINUED W-NW FLOW AND POTENTIAL FOR WEAKER SHORTWAVE TO MOVE ACROSS AREA WILL WARRANT KEEPING A CHC MENTION OF -SHSN INTO EARLY PART OF NEXT WEEK ACROSS NRN COUNTIES. SOME MODERATION IN TEMPS IS POSSIBLE AS 850 MB READINGS RISE TO AROUND -16C TO -18C. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH IN EFFECT FOR THU THROUGH THU NIGHT FOR MIZ004>007-010>014. && $$ VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1123 AM EST TUE FEB 14 2006 .DISCUSSION... THE MAIN CONCERN WITH THIS UPDATE IS THE POTENTIAL FOR PRECIPTIATION THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/NAM SHOWING A ZONAL FLOW ACROSS NORTHERN CONUS WITH A NUMBER OF WEAK SHORTWAVES RACING ALONG THE CANADIAN/CONUS BORDER. A SHORTWAVE OVER WESTERN ONTARIO WILL SPEED TO JUST SOUTH OF JAMES BAY THIS AFTERNOON...WHILE A WEAK SHORTWAVE OVER SOUTH DAKOTA WILL REACH EASTERN WISCONSIN BY LATE AFTERNOON. MEANWHILE...AT THE SURFACE A LOW OVER THE ARROWHEAD OF MINNESOTA WILL TRACK QUICKLY ACROSS LAKE SUPERIOR DRAGGING A COLD FRONT INTO CENTRAL U.P. AND ANOTHER COLD FRONT ACROSS THE CONUS/CANADIAN BORDER. KMQT-88D DEPICTING A COLD DECK AROUND 10K FEET PRODUCING SNOW...BUT LITTLE IF ANY OF THIS SNOW IS REACHING THE GROUND AT THIS TIME. WRF AND RUC INDICATE A WEAK SHORTWAVE WILL PASS OVER THE SOUTHERN PART OF THE U.P. THIS AFTERNOON. BOTH INDICATE THAT LOW LEVEL MOISTURE WILL BE CONCENTRATED MAINLY OVER THE SOUTHERN COUNTIES AND ALONG THE LAKE MICHIGAN. NAM/GFS ARE KEEPING THE MOISTURE AND INSTABILITY A LITTLE SOUTH OF THE FORECAST AREA. SATELLITE AND COMPOSITE RADAR SEEMS TO SUPPORT A COMPROMISE OF THESE TWO SCENERIOS. THEREFORE...WILL KEEP A BETTER CHANCE OF SNOW FOR THE SOUTHERN COUNTIES AND ALONG LAKE MICHIGAN THIS AFTERNOON...WHILE ELSEWHERE THE INSTABILITY WILL BE LESS SO WILL STAY WITH JUST A CHANCE. THUS WILL UPDATE MAINLY FOR WORDING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RALEIGH NC 1057 AM EST TUE FEB 14 2006 .SHORT TERM (REST OF TODAY)... MODEL SOUNDINGS FROM KGSO...KRNK...AND KOHX SHOW A DRY AIR MASS OVER AND NEAR CENTRAL NORTH CAROLINA...SUPPORTED BY BOTH HIGH DEW POINT DEPRESSIONS AT 700MB AND 850MB ON THE 12Z UPPER-AIR ANALYSIS AND THE MORNING WATER VAPOR LOOP...INDICATING VERY DRY MID-LEVEL AIR AS WELL. 850MB WINDS WERE IN THE RANGE OF 30KTS AT 12Z THIS MORNING...AND RUC FORECAST 925MB WINDS FOR THE AFTERNOON GENERALLY ARE FROM 15 TO 20KT. SUBSIDENCE WILL BE THE RULE THIS AFTERNOON IN MID-LEVEL CONFLUENT FLOW...AND FEW IF ANY CLOUDS ARE EXPECTED. SHOULD BE SUFFICIENT MIXING WITH THE HEATING OF THE AFTERNOON TO PROVIDE FOR WINDS AT LEAST AROUND 10 MPH IN MOST LOCATIONS...WITH A GUST OR TWO IN THE TEENS EXPECTED. LOCAL THICKNESS SCHEME SUGGESTS MAXES AT LEAST IN THE MID 50S AND HAVE MAINTAINED CURRENT FORECAST OF HIGHS FOR THE AFTERNOON OR MAYBE NUDGED UP A DEGREE GIVEN GOOD WARMING TO START THE DAY UNDER FULL SUN. GRIDDED AND WORDED FORECASTS HAVE BEEN ISSUED. && .PREVIOUS DISCUSSION... (ISSUED 210 AM EST TUE FEB 14 2006) SHORT TERM (TODAY THROUGH THURSDAY NIGHT)... NEARLY ZONAL FLOW ALOFT WILL GRADUALLY BECOME SOUTHWEST DURING WEDNESDAY THROUGH REMAINDER OF PERIOD. S/W WILL SKIRT ACROSS LATE MORNING/EARLY AFTERNOON BUT MOISTURE STARVED...A FEW CLOUDS AT BEST. ANOTHER FAIRLY STRONG S/W PASSES WELL SOUTH OVERNIGHT TONIGHT. AT THE SURFACE...HIGH PRESSURE WILL SHIFT OFF THE SOUTHEAST ATLC COAST WITH RETURN FLOW DEVELOPING. NAM A BIT STRONGER ON RETURN DEEPER MOISTURE AND ISENTROPIC LIFT DEVELOPING OVER THE AREA ON THURSDAY. GFS DRIER. CONTINUE PARTLY CLOUDY FOR THURSDAY INTO THURSDAY NIGHT. GOOD LOW LEVEL WARMING AS LOW LEVEL THICKNESS INCREASES 30+ METERS TODAY (RANGE OF 1330-1335 METERS ACROSS CWA). EXPECT HIGHS IN THE MID TO UPPER 50S TODAY WHICH WILL AVERAGE ABOUT 10 DEGREES OR SO WARMER THAN THOSE YESTERDAY. A CONTINUED WARM UP THROUGH LATE WEEK WHICH WILL RESULT IN UNSEASONABLE MILD TEMPERATURES. HIGHS WEDNESDAY AND THURSDAY IN THE 60S. LONG TERM (FRIDAY THROUGH MONDAY)... FRIDAY...COLD FRONT APPROACHING FROM THE WEST EARLY FRIDAY AND QUICKLY MOVING THROUGH DURING THE AFTERNOON. THIS WILL BRING A QUICK SHOT OF SHOWERS MAINLY DURING THE MORNING AND EARLY AFTERNOON. THE FRONT WILL STALL SOUTH OF THE AREA FRIDAY NIGHT. SATURDAY THROUGH MONDAY... LITTLE ADJUSTMENTS TO CURRENT FORECAST TRENDS DURING THIS PERIOD. WITH THE FRONT STALLING SOUTH OF THE AREA...GFS/ECMWF AND OTHER MEDIUM RANGE MODEL TRENDS INDICATE OVERRUNNING RAINS DEVELOPING ACROSS AREA DURING SATURDAY. A RETURN TO MUCH COLDER WEATHER FOR THE WEEKEND AS COLD ARCTIC HIGH DIVES SOUTHEAST. THE BRUNT OF THE VERY COLD AIR WILL BUILD SOUTH THROUGH THE ROCKIES BUT SOME OF THIS COLDER AIR WILL SPREAD EAST...EVENTUALLY SLIDING SOUTH INTO THE SOUTHEAST MID ATLC LATE IN THE WEEKEND AND EARLY NEXT WEEK. AVIATION... VFR CONDITIONS EXPECTED AT ALL TAF SITES OVER THE FORECAST AREA THROUGH 00Z WEDNESDAY AS THE PATTERN ALOFT BECOMES MORE ZONAL WITH SLIGHT H5 RIDGING EXPECTED LATER THIS AFTERNOON AS SFC HIGH PRESSURE OVER THE SOUTHEAST PASSES SOUTH OF THE AREA OFFSHORE INTO THE ATLANTIC. VORT MAX ASSOCIATED WITH WEAK SHORTWAVE RIDES ALONG THE PERIPHERY OF DEVELOPING H5 RIDGE THROUGH THE CWA BETWEEN 09-18Z TODAY. HOWEVER...DEEP LAYER RH'S WILL BE QUITE LOW AND UPSTREAM IR SAT IMAGERY CO-LOCATED WITH VORT MAX SHOWS FEW OR NO CIRRUS. THUS...EXPECTING SKC CONDS ALL DAY W/FEW250 CIRRUS POSSIBLE THIS MORNING INTO MID AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJF nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 928 AM EST TUE FEB 14 2006 .SHORT TERM (REST OF TODAY)...HIGH PRESSURE OVER NORTHERN FLORIDA WILL MOVE EAST TODAY. WELL-DEFINED UPPER LEVEL SHORTWAVE WILL PASS THROUGH TODAY. HOWEVER TIME SECTIONS AND FORECAST SOUNDINGS SHOW VERY DRY CONDITIONS THROUGHOUT. CURRENT FORECAST LOOKS GOOD. NO ZONE UPDATES NEEDED THIS MORNING. && .AVIATION...VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS. && .MARINE...DIAMOND BUOY WINDS AND SEAS BOTH WELL ABOVE CURRENT FORECAST LEVELS. CAPE LOOKOUT CMAN WINDS ALSO STRONGER THAN FORECAST. LATEST RUC DOES INDICATE A MID LVL VORT MAX MOVING THROUGH THE REGION WOULD COULD BE ACCOUNTING FOR THE SLIGHTLY STRONGER WINDS. HAVE UPPED THE WINDS AND SEAS OVER ALL WATERS FOR TODAY AND RAISED SCA FOR THE CENTRAL WATERS. WIND AND SEAS SHOULD BEGIN TO SUBSIDE BY LATE AFTN INTO THE EVNG. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FOR AMZ152-154-156 UNTIL 6 PM TUESDAY. && $$ HSA/MLF nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 909 PM CST TUE FEB 14 2006 .UPDATE... LATEST SATELLITE DATA INDICATES PARTLY CLOUDY SKIES DOMINATE WEST CENTRAL TEXAS THIS EVENING. LATEST MODEL DATA SUGGESTS THIS LEVEL OF CLOUD COVER WILL CONTINUE FOR THE REMAINDER OF TONIGHT. IN ADDITION...LATEST METAR DATA INDICATES WINDS ACROSS WEST CENTRAL TEXAS HAVE DIMINISHED. LATEST KSJT WSR-88D VAD WIND PROFILE DATA SHOW SOUTHWEST WINDS AROUND 30 KNOTS AT THE LOWEST GATE. LATEST RUC SOUNDING DATA SUGGESTS LOW-LEVEL TEMPERATURE INVERSION WILL DEVELOP AGAIN ACROSS WEST CENTRAL TEXAS DURING THE NEXT SEVERAL HOURS. THUS...EXPECT DEVELOPING INVERSION AND ASSOCIATED DECOUPLING TO CONTINUE TO INHIBIT DOWNWARD MOMENTUM TRANSPORT TONIGHT. SENT A RECENT UPDATE TO ADJUST SKY CONDITIONS AND WINDS FOR THE REMAINDER OF TONIGHT. OTHERWISE...NO OTHER CHANGES. 23/HUBER && .PREV DISCUSSION... (ISSUED 524 PM CST TUE FEB 14 2006) AVIATION... SURFACE LOW IN PANHANDLE BEGINS TO TIGHTEN AFTER 6Z...AS 850 MB 35-40 KT LEVEL JET DEVELOPS. NOT SURE WHETHER KABI AND KSJT WILL REACH WIND SHEAR CRITERIA...AND WILL LEAVE MENTION IN TAF OUT FOR NOW. WILL HOWEVER...CONTINUE TOMONITOR VAD WINDS AT SAN ANGELO AND DYESS RADARS...ESPECIALLY AFTER 4Z. KABI WILL PROBABLY HAVE THE BETTER CHANCE OF LLWS...MAINLY TOWARD 9Z. PUT GUSTS IN AND INCREASED WINDS 15-16Z WITH INCREASING SURFACE MIXING AND DEVELOPING SURFACE LOW. PREV DISCUSSION... (ISSUED 320 PM CST TUE FEB 14 2006) SHORT TERM... HIGH CLOUDS CONTINUE TO STREAM ACROSS WEST CENTRAL TEXAS THIS AFTERNOON...A LITTLE THICKER THAN THE MODELS ORIGINALLY INTENDED. AFTER TAKING A LOOK OUTSIDE...WILL GO AHEAD AND BOOST CLOUD COVER TO START THE FIRST PERIOD OFF AND THEN TREND DOWN THROUGH TONIGHT. OVERNIGHT LOWS WILL BE WARMER TONIGHT THAN IN PREVIOUS NIGHTS...AS CLOUD COVER AND GOOD MIXING FROM THE LOW LEVEL JET KEEP TEMPS UP. STILL GOING BELOW GUIDANCE A COUPLE OF DEGREES WITH A DRY AIR MASS IN PLACE. FIRE WEATHER A CONCERN ONCE AGAIN ON WEDNESDAY AFTERNOON. WITH MODEL DEWPOINTS HAVING BEEN PRETTY HORRIBLE OVER THE LAST FEW MONTHS...ESPECIALLY WHEN FACED WITH WEST OR SOUTHWEST WINDS...WILL UNDERCUT GUIDANCE DEWPOINTS. PRESSURE GRADIENT TIGHTENS UP TOMORROW AS WELL...ALTHOUGH MAY NOT QUITE GET TO RED FLAG WARNING CRITERIA. WITH AS DRY AS IT HAS BEEN...WILL NOT TAKE ANY CHANCES THROUGH AND HAVE ALREADY ISSUED THE WARNING. OTHERWISE...WARM AND BREEZY THROUGH THURSDAY. LONG TERM... ARCTIC FRONT PASSAGE THROUGH WEST CENTRAL TEXAS HAS BEEN VERY CONSISTENT FOR SEVERAL RUNS...PASSING ACROSS WEST CENTRAL TEXAS THURSDAY EVENING INTO EARLY FRIDAY MORNING. THEN THE MODELS BEGIN TO HAVE ISSUES. RUN TO RUN AND MODEL TO MODEL CONSISTENCY HAS BEEN POOR FROM SUNDAY THROUGH EARLY NEXT WEEK. WITH THE CENTER OF THE SURFACE HIGH NOT REALLY BUILDING IN...BUT INSTEAD JUST RIDGING INTO PLACE...AND WITH THE QUICK TURN AROUND TO SOUTHERLY WINDS AT 850 MB...TEMPERATURES WILL BE TRICKY. GFS TRIES TO EAT AWAY AT THE ARCTIC AIR MASS FROM ABOVE...PROBABLY A LITTLE TOO FAST. WILL TREND TEMPS UP BUT NOT QUITE AS QUICKLY. GFS SHOWS THE NEXT FRONT DROPPING THROUGH MONDAY. COULD BE A VERY COLD AIR MASS...BUT CONSIDERING THE INCONSISTENCIES...WILL UNDERCUT GUIDANCE BUT BE CONSERVATIVE ABOUT IT. $$ && .SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 10 AM WEDNESDAY TO 6 PM WEDNESDAY FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...CONCHO... CROCKETT...FISHER...HASKELL...IRION...JONES...MCCULLOCH... MENARD...NOLAN...RUNNELS...SCHLEICHER...SHACKELFORD...STERLING... SUTTON...TAYLOR...THROCKMORTON...AND TOM GREEN. && $$ 23/HUBER tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 930 PM PST TUE FEB 14 2006 .SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...LATEST SHORT RANGE MODEL PRODUCTION CONTINUES TO SHOW A MAJOR CHANGE TAKING PLACE ACROSS THE WESTERN STATES ON WEDNESDAY. CURRENTLY...IR SATELLITE IMAGERY ALONG WITH RUC-40 TEMPERATURE ANALYSIS SHOWS A SIGNIFICANT UPPER TROUGH DEVELOPING OVER THE PACIFIC NORTHWEST WITH 500MB TEMPERATURES APPROACHING MINUS 40 DEG-C. WHILE THE AFFECTS OF THE COLD SURGE WERE FELT TODAY...MOST LOCATIONS WERE ONLY A COUPLE OF DEGREES COOLER FROM THAT OF MONDAY. TIMING STILL ON TRACK FOR THE BIG PUSH TO OCCUR ON WEDNESDAY AS THE SIGNIFICANT UPPER TROUGH GETS EVEN CLOSER TO THE DISTRICT. MODELS STILL SHOWING MUCH COOLER AIR INVADING THE REGION WEDNESDAY AS THE UPPER TROUGH DIGS SOUTH THROUGH CENTRAL CALIFORNIA...DROPPING TEMPERATURES FROM WELL ABOVE NORMAL TO SEVERAL DEGREES BELOW NORMAL. LITTLE CHANGE IS STILL EXPECTED AFTERWARD AS ADDITIONAL SHORTWAVE ENERGY REINFORCES THE UPPER TROUGH. THEREFORE...WHILE THE FREEZE WATCH AND WIND ADVISORY WILL BE UPDATES AND CONTINUED...WILL MAKE NO CHANGES TO THE FORECAST ELEMENTS AS CURRENT PACKAGE ON TRACK WITH LATEST MODEL RUNS. .LONG TERM...FOR FRIDAY NIGHT THROUGH TUESDAY...MEDIUM RANGE CONTINUE IN GOOD AGREEMENT FOR MUCH OF THE PERIOD. A COLD UPPER LOW OVER THE PACIFIC NORTHWEST WILL MOVE SOUTH FRIDAY NIGHT PUSHING EAST OF CENTRAL CALIFORNIA LATE SUNDAY. ADDITIONAL COLD AIR AND UPPER ENERGY WILL REINFORCE THE TROUGH BRINGING THE BEST CHANCES FOR MEASURABLE PRECIPITATION FRIDAY NIGHT TO SATURDAY NIGHT. SOME PRETTY COLD AIR ALOFT IS ASSOCIATED WITH THIS SYSTEM AND WOULD LOWER SNOW LEVELS POSSIBLY DOWN TO AROUND 3000-3500 FEET. GFS BEGINNING TO SHOW DEEPER MOISTURE WITH THIS SYSTEM AND A COUPLE OF TENTHS OF QPF DOWN TO THE CENTRAL SAN JOAQUIN VALLEY. HEAVY PRECIPITATION THREAT MAY BE LIMITED AS THE SUBTROPICAL MOISTURE CONNECTION APPEARS TO REMAIN WELL SOUTH NEAR BAJA. THE UNSTABLE AIRMASS WARRANTS PRECIP CHANCES THROUGH THE WEEKEND. TEMPERATURES WILL CONTINUE BELOW NORMAL THROUGH THE PERIOD. && .AVIATION...AREAS OF MVFR VISIBILITIES DUE TO HAZE IN THE SAN JOAQUIN VALLEY THROUGH 02Z WED...OTHERWISE VFR CONDITIONS EXPECTED THROUGH 00Z THURSDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO TAFS FOR KMCE...KFAT AND KBFL. && .HNX WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FOR THE KERN COUNTY MOUNTAINS AND DESERTS LATE TONIGHT AND WEDNESDAY. SOUTHERN SAN JOAQUIN VALLEY WEDNESDAY NIGHT. && $$ WWW.WEATHER.GOV/HANFORD /USE ALL LOWER CASE/ MOLINA/MV ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1108 PM CST TUE FEB 14 2006 .AVIATION... KDYX AND KSJT VAD WAS SHOWING A 45KT/40KT LOW LEVEL JET AT 3000 MSL RESPECTIVELY AT 5Z. MENTIONED WIND SHEAR AT BOTH KABI AND KSJT TAFS UNTIL 13Z. INCREASED WINDS AROUND 15Z DUE TO HEATING/MIXING. WILL SEE A SLIGHTLY STRONGER LOW LEVEL JET SET UP TOMORROW EVENING...AS SURFACE LOW IN PANHANDLE CONTINUES TO DEVELOP. && .PREV DISCUSSION... (ISSUED 909 PM CST TUE FEB 14 2006) UPDATE... LATEST SATELLITE DATA INDICATES PARTLY CLOUDY SKIES DOMINATE WEST CENTRAL TEXAS THIS EVENING. LATEST MODEL DATA SUGGESTS THIS LEVEL OF CLOUD COVER WILL CONTINUE FOR THE REMAINDER OF TONIGHT. IN ADDITION...LATEST METAR DATA INDICATES WINDS ACROSS WEST CENTRAL TEXAS HAVE DIMINISHED. LATEST KSJT WSR-88D VAD WIND PROFILE DATA SHOW SOUTHWEST WINDS AROUND 30 KNOTS AT THE LOWEST GATE. LATEST RUC SOUNDING DATA SUGGESTS LOW-LEVEL TEMPERATURE INVERSION WILL DEVELOP AGAIN ACROSS WEST CENTRAL TEXAS DURING THE NEXT SEVERAL HOURS. THUS...EXPECT DEVELOPING INVERSION AND ASSOCIATED DECOUPLING TO CONTINUE TO INHIBIT DOWNWARD MOMENTUM TRANSPORT TONIGHT. SENT A RECENT UPDATE TO ADJUST SKY CONDITIONS AND WINDS FOR THE REMAINDER OF TONIGHT. OTHERWISE...NO OTHER CHANGES. 23/HUBER PREV DISCUSSION... (ISSUED 524 PM CST TUE FEB 14 2006) AVIATION... SURFACE LOW IN PANHANDLE BEGINS TO TIGHTEN AFTER 6Z...AS 850 MB 35-40 KT LEVEL JET DEVELOPS. NOT SURE WHETHER KABI AND KSJT WILL REACH WIND SHEAR CRITERIA...AND WILL LEAVE MENTION IN TAF OUT FOR NOW. WILL HOWEVER...CONTINUE TOMONITOR VAD WINDS AT SAN ANGELO AND DYESS RADARS...ESPECIALLY AFTER 4Z. KABI WILL PROBABLY HAVE THE BETTER CHANCE OF LLWS...MAINLY TOWARD 9Z. PUT GUSTS IN AND INCREASED WINDS 15-16Z WITH INCREASING SURFACE MIXING AND DEVELOPING SURFACE LOW. PREV DISCUSSION... (ISSUED 320 PM CST TUE FEB 14 2006) SHORT TERM... HIGH CLOUDS CONTINUE TO STREAM ACROSS WEST CENTRAL TEXAS THIS AFTERNOON...A LITTLE THICKER THAN THE MODELS ORIGINALLY INTENDED. AFTER TAKING A LOOK OUTSIDE...WILL GO AHEAD AND BOOST CLOUD COVER TO START THE FIRST PERIOD OFF AND THEN TREND DOWN THROUGH TONIGHT. OVERNIGHT LOWS WILL BE WARMER TONIGHT THAN IN PREVIOUS NIGHTS...AS CLOUD COVER AND GOOD MIXING FROM THE LOW LEVEL JET KEEP TEMPS UP. STILL GOING BELOW GUIDANCE A COUPLE OF DEGREES WITH A DRY AIR MASS IN PLACE. FIRE WEATHER A CONCERN ONCE AGAIN ON WEDNESDAY AFTERNOON. WITH MODEL DEWPOINTS HAVING BEEN PRETTY HORRIBLE OVER THE LAST FEW MONTHS...ESPECIALLY WHEN FACED WITH WEST OR SOUTHWEST WINDS...WILL UNDERCUT GUIDANCE DEWPOINTS. PRESSURE GRADIENT TIGHTENS UP TOMORROW AS WELL...ALTHOUGH MAY NOT QUITE GET TO RED FLAG WARNING CRITERIA. WITH AS DRY AS IT HAS BEEN...WILL NOT TAKE ANY CHANCES THROUGH AND HAVE ALREADY ISSUED THE WARNING. OTHERWISE...WARM AND BREEZY THROUGH THURSDAY. LONG TERM... ARCTIC FRONT PASSAGE THROUGH WEST CENTRAL TEXAS HAS BEEN VERY CONSISTENT FOR SEVERAL RUNS...PASSING ACROSS WEST CENTRAL TEXAS THURSDAY EVENING INTO EARLY FRIDAY MORNING. THEN THE MODELS BEGIN TO HAVE ISSUES. RUN TO RUN AND MODEL TO MODEL CONSISTENCY HAS BEEN POOR FROM SUNDAY THROUGH EARLY NEXT WEEK. WITH THE CENTER OF THE SURFACE HIGH NOT REALLY BUILDING IN...BUT INSTEAD JUST RIDGING INTO PLACE...AND WITH THE QUICK TURN AROUND TO SOUTHERLY WINDS AT 850 MB...TEMPERATURES WILL BE TRICKY. GFS TRIES TO EAT AWAY AT THE ARCTIC AIR MASS FROM ABOVE...PROBABLY A LITTLE TOO FAST. WILL TREND TEMPS UP BUT NOT QUITE AS QUICKLY. GFS SHOWS THE NEXT FRONT DROPPING THROUGH MONDAY. COULD BE A VERY COLD AIR MASS...BUT CONSIDERING THE INCONSISTENCIES...WILL UNDERCUT GUIDANCE BUT BE CONSERVATIVE ABOUT IT. $$ SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 10 AM WEDNESDAY TO 6 PM WEDNESDAY FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...CONCHO... CROCKETT...FISHER...HASKELL...IRION...JONES...MCCULLOCH... MENARD...NOLAN...RUNNELS...SCHLEICHER...SHACKELFORD...STERLING... SUTTON...TAYLOR...THROCKMORTON...AND TOM GREEN. $$ && .SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 10 AM WEDNESDAY TO 6 PM WEDNESDAY FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...CONCHO... CROCKETT...FISHER...HASKELL...IRION...JONES...MCCULLOCH... MENARD...NOLAN...RUNNELS...SCHLEICHER...SHACKELFORD...STERLING... SUTTON...TAYLOR...THROCKMORTON...AND TOM GREEN. && $$ 99/99/04 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1053 AM EST WED FEB 15 2006 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST UPDATE PACKAGE IS THE LAKE EFFECT SNOW POTENTIAL FOR THE FORECAST AREA. WATER VAPOR IMAGERY AND RUC/NAM SHOWING A DEEP LOW DIGGINIG OVER NORTHEAST UTAH...WHILE A LONGWAVE TROUGH IS DEEPENING OVER CENTRAL CANADA. A SHORTWAVE SWINGING THROUGH THE BASE OF THIS TROUGH IS SPEEDING THROUGH UPPER MICHIGAN. AT THE SURFACE A LOW IS OVER EAST CENTRAL ONTARIO MOVING INTO QUEBEC WHILE A BROAD RIDGE IS EDGING INTO THE UPPER MISSISSIPPI RIVER VALLEY. COLD AIR ADVECTING INTO THE AREA IS PRODUCING A LAKE-850MB DELTA-T'S OF 22C. THE AIR MASS NORTH OF LAKE SUPERIOR IS VERY DRY...WITH SURFACE DEW POINT ON THE ORDER OF -22F. THIS IS LIMITING THE DEVELOPMENT OF LAKE EFFECT SNOWS...HOWEVER...THE LONGER FETCHES ARE STILL PICKING UP ENOUGH MOISTURE TO GENERATE LAKE EFFECT SNOW OVER THE KEWEENAW PENINSULA AND EAST PART OF THE CWA. KCMX HAS BEEN REPORTING VISIBILITIES DOWN TO 1 MILE FOR A FEW HOURS THIS MORNING IN LAKE EFFECT SNOWS. THE HOUGHTON COUNTY SHERIFFS REPORTED AT LEAST 2 INCHES OF SNOW FELL SO FAR THIS MORNING. THE SHORTWAVE OVER THE FORECAST AREA WILL SLIDE OFF TO THE EAST THIS AFTERNOON WEAKENING THE UPPER LEVEL INSTABILITY. A 700MB LOW OVER THE FORECAST AREA WILL LIKEWISE MOVE EAST TODAY. LOW LEVEL CONVERGENCE WILL WEAKEN AS WELL AS THE WINDS BACKING MORE TO THE WEST. THIS SHOULD KEEP THE LAKE EFFECT SNOW BANDS CONTINUING OVER THE KEWEENAW PENINSULA. SINCE BANDS WILL CONTINUE THIS AFTERNOON... WILL GO WITH AN ADVISORY FOR THE KEWEENAW PENINSULA FOR THE REST OF TODAY. AS THE LOW RIDGE APPROACHES BY LATE AFTERNOON...THE WINDS WILL ALSO DIMINISH. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH IN EFFECT FOR THU THROUGH THU NIGHT FOR MIZ004>007-010>014. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1155 AM CST WED FEB 15 2006 .DISCUSSION... MINOR UPDATE TO FORECAST THIS AFTERNOON TO LOWER LIGHT RAIN CHANCES A BIT AND TO ADJUST HIGH TEMPERATURES IN A FEW SPOTS. MOSTLY CLOUDY THIS AFTERNOON WITH 20/30 PERCENT CHANCE OF LIGHT RAIN. HIGHS RANGING FROM AROUND 40F NW AT GALESBURG...TO THE UPPER 50S OVER SE IL. MIDDAY SURFACE MAP HAS 1008 MB LOW PRESSURE ALONG THE EASTERN KS/OK BORDER WITH A FRONTAL BOUNDARY EXTENDING NE ACROSS CENTRAL MO AND CENTRAL IL FROM TAYLORVILLE TO DECATUR TO CHAMPAIGN. NOON TEMPS RANGE FROM THE UPPER 30S NW OF THE IL RIVER WITH GALESBURG AT 37F TO THE LOWER 50S SOUTH OF I-70 WITH FLORA UP TO 54F. MOSTLY CLOUDY SKIES ACROSS IL WITH BROKEN MID LEVEL CLOUDS AROUND 12 KFT WHILE BROKEN TO OVERCAST LOW CLOUDS AROUND 2000 FT OVER SE IL SE OF I-70. RADAR MOSAIC SHOWS LIGHT ECHO RETURNS OVER NORTHERN IL...SE IOWA AND FAR SOUTHERN WI BUT NOT GETTING MUCH GROUND TRUTH REPORTS OF PRECIPITATION YET. RUC AND NAM KEEP CENTRAL IL FAIRLY DRY THIS AFTERNOON WITH RAIN DEVELOPING AFTER 00Z/6 PM AS FRONTAL BOUNDARY STRENGTHENS WHILE REMAINING NEARLY STATIONARY FROM TAYLORVILLE TO DECATUR TO CHAMPAIGN AS LOW PRESSURE DEEPS INTO SW MO BY SUNSET. NAM DOES SHOW A LITTLE BIT OF LIGHT QPF OVER CENTRAL IL NEAR THE FRONT BETWEEN 21Z-00Z (3-6 PM). THERE IS GOOD ISENTROPIC LIFT DEVELOPING THIS AFTERNOON ESPECIALLY LATE WHEN CONDENSATION PRESSURE DEFICITS SATURATE SO WILL KEEP CHANCE OF LIGHT RAIN SHOWERS FOR LATE THIS AFTERNOON. NEARLY A 20 DEGREE TEMP GRADIENT FROM NW TO SE ACROSS CENTRAL/SE IL WITH THE FRONT NEARLY STATIONARY ACROSS CENTRAL IL. HIGHS AROUND 40F FAR NW AT GALESBURG TO UPPER 50S OVER SE IL WHICH NAM AND RUC AGREE ON. ALL GUIDANCE SUPPORTS JUST RAIN AT PEORIA TONIGHT WITH TEMPS STAYING ABOVE FREEZING...WHILE FREEZING RAIN STILL POSSIBLE TONIGHT FAR NW AT GALESBURG WHERE TEMPS APPROACH 30F LATER TONIGHT. SPC HAS ALL OF CENTRAL IL IN GENERAL RISK OF THUNDER TONIGHT FOR ELEVATED THUNDERSTORMS WITH STRONG LOW LEVEL JET AND GOOD MOISTURE AND DYNAMICS WITH FRONTAL BOUNDARY STAYING CLOSE TO I-55. SPC DAY2 OUTLOOK HAS UPGRADED CENTRAL/SE IL TO A SLIGHT RISK OF SEVERE THUNDERSTORMS SE OF THE IL RIVER ON THU AFTERNOON AS 2ND 997 MB LOW ALONG THE CO/UT BORDER TRACKS NE INTO CENTRAL IL. MEANWHILE A WINTER STORM WITH HEAVY SNOW ON TRACK FOR WI AND NE IOWA TONIGHT AND THU. && .PREV DISCUSSION... PERIOD OF FREEZING RAIN OR FREEZING DRIZZLE POSSIBLE FAR NORTHWEST AREAS OVERNIGHT TONIGHT INTO EARLY HOURS THURSDAY MORNING. FREEZING PRECIP AREA WILL BE AWFULLY CLOSE TO PEORIA METRO AREA. ICE ACCUMULATIONS EXPECTED TO BE MINIMAL... BUT THAT DOES NOT PRECLUDE RISK OF LIGHT GLAZING CAUSING SOME PROBLEMS. SHORT TERM...TODAY THROUGH FRIDAY... QUASI-STATIONARY FRONT HAS MOVED SLOWLY TO THE EAST OVERNIGHT... AND IS CURRENTLY JUST EAST OF A CHI-PIA-UIN LINE. DEEPER POOL OF COLDER AIR REMAINS POOLED UP OVER THE DAKOTAS AND THE UPPER MIDWEST... BUT THIS WILL EVENTUALLY SLIDE FARTHER SOUTH DURING THE DAY THURSDAY AS POLAR VORTEX CENTERED OVER NORTHERN MANITOBA RETROGRADES INTO SOUTHERN SASKATCHEWAN. INITIAL SHORTWAVE TROUGH/MID LEVEL SPEED MAX IS MOVING THROUGH WESTERN KANSAS THIS MORNING.... WITH ATTENDANT INITIAL SFC WAVE OVER WESTERN OKLAHOMA. PRIMARY SFC LOW OF CONCERN IS TAKING SHAPE OVER THE GREAT BASIN. AS INITIAL DISTURBANCE MOVES CLOSER TO THE AREA... LOW LEVEL FLOW WILL DEEPEN OUT OF THE SOUTHWEST... WHICH SHOULD ALLOW SFC FRONT ACROSS THE AREA TO DRIFT BACK TO THE NORTHWEST SOMEWHAT. ISENTROPIC LIFT WILL INCREASE TONIGHT AS LLJ STEADILY INCREASES AHEAD OF INITIAL SHORTWAVE. COULD SEE A FEW SHOWERS BREAK OUT SOUTH OF THE I-72/74 CORRIDOR EARLY THIS AFTERNOON... WITH COVERAGE INCREASING TOWARDS EVENING. ETA/GFS BOTH IN VERY GOOD AGREEMENT ON OVERALL TRACK OF THE SYSTEM... THOUGH GFS CONTINUES TO HANDLE AMPLIFICATION OF PRIMARY SHORTWAVE A BIT BETTER THAN THE ETA. HOWEVER... FEEL THE ETA IS COMING IN LINE ENOUGH TO TRUST ITS HIGHER RESOLUTION FOR SOME OF THE INITIAL DETAILS. THAT SAID... ETA SOUNDINGS FOR PIA AND GBG INDICATE SHALLOW LAYER OF SUB-FREEZING COOLER/DRIER AIR DEVELOPING AND MAINTAINING ITSELF BETWEEN 00-15Z THU... WITH PLENTY OF WARM AIR ABOVE 950MB. DRIER BOUNDARY LAYER IN SOUNDINGS SUGGESTS INITIAL EVAPORATIVE COOLING WILL AID IN DEVELOPMENT OF NEAR-SFC FREEZING LAYER AFTER DARK WITH ONSET OF PRECIPITATION. LAYER IS VERY SHALLOW... AND NOT TERRIBLY FAR BELOW FREEZING POINT... SO EXPECT THAT ANY FREEZING PRECIP PROCESS WOULD BE SELF-DESTRUCTIVE IN TIME... WITH LATENT HEAT RELEASE IN THE FREEZING PROCESS EVENTUALLY WARMING THE LAYER. FOR NOW... QPF AMOUNTS AND NARROW TIMEFRAME OF FREEZING PRECIP SUGGEST MINIMAL ICE ACCUMULATIONS... BUT THIS DOES NOT MEAN LIGHT GLAZING AND ASSOCIATED TRAVEL HAZARDS WILL NOT OCCUR. WE WILL NEED TO WATCH POSITION OF COLD FRONT VERY CAREFULLY TODAY... WITH SPECIAL ATTENTION TO SFC TEMPS IN THE FAR NW CWA. SIGNIFICANT WARMING OF BOUNDARY LAYER ABOVE CURRENTLY FORECASTED MAX TEMPS MAY MITIGATE INITIAL FREEZING PRECIP THREAT. GUIDANCE CONTINUES TO INDICATE THAT PRECIPITATION MAY BE EPISODIC IN NATURE... ESPECIALLY SW OF THE ILLINOIS RIVER... AWAY FROM STALLED OUT FRONT. STILL EXPECT PRECIP TO BEGIN TO BREAK OUT ACROSS THE SOUTH LATE THIS AFTERNOON INTO THE EVENING... BUT BEST FRONTOGENETIC FORCING AND STEEPEST ISENTROPIC UPGLIDE QUICKLY SHIFTS NORTHWARD AS LLJ INCREASES AND IMPINGES ON STALLED OUT BAROCLINIC ZONE. AT THE SAME TIME... SOME MID-LEVEL DRY AIR WILL BEGIN TO GET PULLED IN AS SHEARED-OUT INITIAL SHORTWAVE MOVES THROUGH. DRY AIR IS ALREADY EVIDENT PUNCHING IN FROM AZ/NM BEHIND THE INITIAL WAVE ON WATER VAPOR THIS MORNING. HAVE TAPERED POPS ACROSS THE SOUTH TONIGHT INTO THE FIRST HALF OF TOMORROW CONSIDERING THIS. PRECIP COVERAGE SHOULD INCREASE THURSDAY MORNING... ESPECIALLY ALONG THE FRONT IN THE NORTHWEST CWA AS SECOND SHORTWAVE AND ATTENDANT SFC LOW APPROACH THE AREA... ALLOWING LLJ TO BEGIN INCREASING AGAIN. SFC LOW WILL CAUSE SOME KINKING OF THE STALLED OUT BAROCLINIC ZONE... ALLOWING WARMER AIR TO FLOW BACK INTO THE NORTHWEST CWA... PUTTING AN END TO FREEZING PRECIP THREAT FOR THE TIME BEING. POPS INCREASE IN THE EASTERN CWA THROUGH THE AFTERNOON AS COLD FRONT AND ASSOCIATED STRONG FORCING MARCHES ACROSS. SHEAR PARAMETERS STILL LOOK IMPRESSIVE... AND WITH SFC TEMPS REACHING THE UPPER 50S/LOWER 60S ACROSS THE FAR EAST AND SOUTHEAST... SOME MODEST INSTABILITY SHOULD ALSO BE PRESENT. LINE OF CONVECTION LOOKS QUITE POSSIBLE... WITH SVR THREAT ALSO PRESENT. DAMAGING WINDS WOULD BE MOST LIKELY ISSUE TO CONTEND WITH. SNOW BAND LOOKS TO SET UP TO OUR NORTH AND WEST... LIKELY SETTING UP OVER NORTHEASTERN IOWA THROUGH WISCONSIN. STILL EXPECT THAT SOME AREAS... ESPECIALLY IN THE NORTHERN CWA WILL COULD BE SCRAPED BY SOME SNOW AS A RAPID CHANGEOVER IS EXPECTED WITH TEMPERATURES DROPPING DRAMATICALLY BEHIND THE FRONT. AREAS ACROSS THE SOUTH MAY BE DRY SLOTTED AGAIN JUST BEHIND THE FRONT... SO SNOW THREAT IS LESSENED THERE. ACCUMULATION AMOUNTS ARE STILL EXPECTED TO BE UNDER AN INCH AT THIS TIME EVEN IN THE NORTH. COOLER... DRIER CONDITIONS ON FRIDAY AS HIGH PRESSURE BEGINS NOSING IN. SOME THREAT OF SCATTERED FLURRIES EARLY ESPECIALLY EASTERN AREAS WITH CONTINUED CYCLONIC FLOW. GUSTY WINDS ALSO POSSIBLE... BUT AT THIS TIME EXPECT THAT PRESSURE GRADIENT WILL SLACKEN THROUGHOUT THE DAY FRIDAY AS LOW PRESSURE RAPIDLY MOVES OUT. LONG TERM...SATURDAY THROUGH TUESDAY... INDICATIONS ARE THAT CORE OF COLDEST AIR WILL PASS TO OUR NORTH SATURDAY... HOWEVER STILL EXPECT SOME VERY COLD MORNINGS SATURDAY AND ESPECIALLY SUNDAY MORNING AS HIGH PRESSURE SETS UP... WINDS SLACKEN... AND CLOUDS WILL BE LESS OF AN ISSUE. LONG RANGE MODELS CONTINUE TO FLIP-FLOP ON NEXT SYSTEM FOR EARLY NEXT WEEK. GENERAL CONSENSUS IS THAT STRONG HIGH PRESSURE AND AND COLDER AIR MOVING IN WILL SQUASH MAIN BAROCLINIC ZONE AND RESULTANT STORM TRACK TO OUR SOUTH... LESSENING CHANCES OF SNOW. HOWEVER... CONSIDERING RUN-TO-RUN INCONSISTENCIES... AS WELL AS NEWER INDICATIONS THAT CORE OF COOLEST AIR WILL REMAIN A BIT FARTHER NORTH THAN PREVIOUSLY EXPECTED... WILL KEEP PRECIP CHANCES UNCHANGED FOR THIS CYCLE. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HUETTL/HARDIMAN il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 PM EST WED FEB 15 2006 .DISCUSSION... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CUTOFF LO IN THE ARCTIC BRANCH CENTERED OVER NRN MANITOBA. H5/7/85 TEMPS UNDER THIS UPR LO ARE -47C/-40C/-35C...AND THIS FEATURE IS DRIFTING SLOWLY SW WITH TIME IN NNE FLOW E OF BLDG RDG INTO AK/YUKON. IN THE POLAR JET... DEEP TROF HAS DVLPD OVER THE WRN CONUS AS POTENT SHRTWV DIGGING S ALG THE W COAST. 00Z-12Z HGT FALLS AS GREAT AS 170M AT RENO ASSOCIATED WITH THIS SYS. FA CURRENTLY UNDER CONFLUENT WSW FLOW ALF BTWN ARCTIC BRANCH TO THE N AND WSW POLAR BRANCH FLOW ACRS MOST OF THE CONUS E OF DEEPENING TROF IN THE W. SFC-H85 LO HAS DVLPD OVER THE SCNTRL PLAINS E OF THE DEEPENING WRN TROF. OTRW...FA REMAINS IN COLD WNW FLOW E OF ARCTIC HI PRES IN THE NRN PLAINS. LES FELL HEAVY AT TIMES OVER THE KEWEENAW THIS MRNG PROMPTING ISSUANCE OF EARLIER ADVY...BUT INFUSION OF VERY DRY AIR OVER NE MN PER SFC DWPTS AS LO AS -20F/VERY LO ABSOLUTE HUMIDITY SHOWN ON THE 12Z INL SDNG HAS CAUSED THIS ACTIVITY TO WANE. BUT SOME HEAVIER SHSN FALLING E OF MUNISING WHERE LONGER FETCH ACRS LK SUP HAS ADDED MOISTURE AND MITIGATED DRY ADVCTN. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES COVG/AMTS TNGT...THEN FOCUS SHIFTS TO IMPACT OF SHRTWV NOW OVER THE WRN CONUS AND GOING WATCH/NEED FOR WRNGS. EXPECT LINGERING LES TO BE ONGOING AT FCST ISSUANCE TIME OVER THE KEWEENAW/E OF MUNISING...BUT ARRIVING DRY AIR/MORE ACYC FLOW AND WEAKENING FLOW/WEAKER PRES GRADIENT SHOULD ALL CONSPIRE TO WEAKEN THE LES BANDS. WL ALLOW THE ADVYS FOR HOUGHTON/KEWEENAW COUNTIES TO EXPIRE AT 4 PM...BUT CONTINUE SCT -SHSN OVER THE KEWEENAW AND MOST OF THE LK SUP SHORELINE AS LLVL FLOW VEERS TO LGT NE OVERNGT AND DISORGANIZED ACTIVITY MAINTAINED BY FVRBL THERMAL INSTABILITY LINGERS. OTRW...UPR CONFLUENT ZN/JET AXIS PROGGED TO DRIFT N ACRS THE FA AND INTO SE CAN AS ARCTIC VORTEX DRIFTS SLOWLY SW THRU SCNTRL CAN. BACKING UPR FLOW/PLACEMENT OF FA IN RRQ OF H3 JET MAX LATER TNGT WL ALLOW HIER CLD NOW STREAMING INTO THE UPR MS VALLEY TO INCRS OVER THE FA. ALTHOUGH ANTECEDENT AIRMASS LOOKS TOO DRY TO ALLOW FOR ANY PCPN AWAY FM THE LKS TNGT...NAM/GFS SHOW SOME LGT PCPN OVER THE FAR SCNTRL. SO WL MAINTAIN LO CHC POPS NR LK MI AFTER MIDNGT TO COINCIDE WITH ARRIVAL OF UPR DVGC MAX IN RRQ OF UPR JET. CONSIDERING THE VERY DRY AIR UPSTREAM...SUSPECT TEMPS OVER THE INTERIOR AREAS WL FALL SHARPLY THIS EVNG TOWARD LOWER NGM MOS GUIDANCE BEFORE GOING STEADY/SLOWLY RISING OVERNIGHT. AS MAIN UPR SHRTWV LIFTS OUT TO THE NE ON THU...SFC/H85 LOW NOW DVLPG OVER THE SRN PLAINS IS FCST TO MOVE NE TOWARD SRN LK MI BY 00Z FRI AND INTO SE ONTARIO BY 12Z FRI. ALTHOUGH SFC/H85 LO LOOK TO PASS FAIRLY FAR TO THE SE CLOSER TO MAIN H85 THERMAL GRADIENT...FCST TRACK OF H7 LO IS MUCH FARTHER TO THE NW TO A POSITION NOT FAR FM IMT AT 00Z FRI AND TOWARD SRN JAMES BAY BY 12Z FRI. IMPRESSIVE H7-3 QVECTOR CNVGC AND UPR DVGC/A STRIPE OF SHARP H7-5 FRONTOGENESIS JUST TO THE W OF THE H7 LO TRACK/SOME NEGATIVE EPV IN THE LYR JUST ABV THE SHARPEST FRONTOGENESIS TO SUG POTENTIAL FOR SLANTWISE AND OR UPRIGHT CNVCTN IN RRQ OF UPR JET IN ONTARIO/DEFORMATION BAND ON COLD SIDE OF H7 LO TRACK SHOULD OVERCOME RATHER WEAK LLVL THERMAL ADVCTN AND UNFVRBL SN GROWTH MICROPHYSICS (TEMPS GENERALLY AOB -20C IN FCST SHARPEST UVV) TO WARRANT UPGRADE FM GOING WATCHES TO WRNGS. EXPECTED FVRBL SN/WATER RATIO AS WELL AS POTENTIAL FOR SGNFT LK ENHANCENT (H85 TEMPS AOB -15C) AND UPSLOPE NNE FLOW ESPECIALLY OVER THE HIER TERRAIN OF THE NCNTRL INCRS CONFIDENCE IN WRNGS. THE BEST DYNAMICS ARE FCST TO MISS THE WRN TIER OF COUNTIES...SO WL GO WITH JUST ADVYS FM IWD-P59. HOWEVER...FVRBL CYC NNE FLOW DOWN THE W END OF LK SUP MIGHT REQUIRE UPGRADE TO LO END WRNGS FOR GOGEBIC/ONTONAGON ZNS. MAIN CONCERN NOW FOR THERE IS VERY DRY AIR JUST TO THE N WOULD LIMIT SN FALL. WL INCLUDE BLSN IN ADVYS AS SHARPENING PRES GRADIENT/ STRG NNE WIND WL BLOW POWDERY SN EASILY. DYNAMICS FCST TO DEPART LATE THU NGT...BUT WL KEEP HEADLINES GOING THRU THE DAY ON FRI FOR AREAS THAT SEE CONTINUED LES IN FCST NW FLOW LEFT IN WAKE OF DEPARTING SHRTWV/LO PRES AS H85 TEMPS BLO -20C PASS ACRS LK SUP. MEDIUM/EXTENDED RANGE GUIDANCE INDICATES COLDEST AIRMASS OF THE SEASON WL FOLLOW THU STORM SYSTEM INTO THIS WEEKEND. 06Z GFS SHOWS H85 TEMPS FALLING AS LO AS -30C FRI EVNG INTO SAT AS THERMAL TROF EASES ACRS THE UPR GRT LKS...WHILE ECMWF INDICATES -25C. EXPECT LES TO BE WDSPRD IN AREAS FAVORED BY WNW FLOW IN ADVANCE OF ARCTIC HI PRES BLDG INTO THE NRN PLAINS...BUT VERY LO TEMPS/POOR SN GROWTH MAY HINDER ACCUMS. FARTHER INLAND...WIND CHILLS MAY REACH HEADLINE CRITERIA AT SOME TIME WITH UNMODIFIED ARCTIC AIR/SHARP PRES GRADIENT. SOME MODERATION/WEAKENING OF THE LES FCST FOR SUN IN SW FLOW IN WAKE OF ARCTIC HI PASSING TO THE S...BUT H85 TEMPS STILL FCST IN -16C TO -18C RANGE. MAJORITY OF GUIDANCE HINTS AT ANOTHER SHRTWV PASSAGE IN NW FLOW ALF IN MON-TUE RANGE...SO WL CARRY SHSN CHCS DURING THIS TIME. THEN A BIT MORE MODERATION ON WED AS NEXT CLIPPER IS FCST TO TRACK ACRS ONTARIO. COORDINATED WITH GRB/APX. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING MIZ012 11Z THU-06Z FRI WINTER STORM WARNING MIZ010-011 14Z THU-06Z FRI WINTER STORM WARNING MIZ004-005-013 17Z THU-11Z FRI WINTER STORM WARNING MIZ014 17Z THU-17Z FRI WINTER STORM WARNING MIZ006-007-085 17Z THU-23Z FRI SNOW AND BLOWING SNOW ADVISORY MIZ001>003-009-084 17Z THU-23Z FRI. && $$ KC mi AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 305 PM MST WED FEB 15 2006 .DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS ARCTIC BOUNDARY STRETCHING FROM NORTHEAST NEB...THROUGH CENTRAL AND NORTHWEST SD...AND INTO EASTERN MT. VERY COLD AND DRY AIR IN PLACE TO THE NORTH AND EAST OF THE BOUNDARY. MAIN AREA OF LOW PRESSURE IS LOCATED ACROSS WESTERN CO WITH WINDS NOW TURNING MORE NORTHEAST AND EAST ACROSS THE AREA. UPPER LEVELS SHOW LOW SLIDING SOUTHEAST ACROSS EASTERN ID AND INTO WESTERN MT WITH SOUTHWEST FLOW ACROSS OUR AREA. THIS IS SETTING UP AN EXTENSIVE BAND OF OVERRUNNING PCPN...WITH AREAS OF MODERATE TO HEAVY SNOW STRETCHING FROM SOUTHEAST WY...THRU NORTHWEST NEB...AND INTO SOUTHWEST SD. UPSLOPE ENHANCED BANDS OF SNOW ARE NOW SETTING UP ACROSS THE EASTERN FOOTHILLS AND ADJACENT PLAINS AS WINDS SHIFT AROUND. AS OF 230 PM...SNOWFALL AMOUNTS HAVE BEEN IN THE 2 TO 4 INCH RANGE ACROSS SOUTHWEST SD AND THE HILLS...WITH SOME LOCALLY HIGHER AMOUNTS AROUND THE AREA. AROUND 2 INCHES SO FAR IN RAPID CITY. SHORT RANGE MODELS IN DECENT AGREEMENT...WITH SOME DIFFERENCES IN SPECIFICS. WILL TAKE A BLEND OF THE GFS AND THE LATEST VERSIONS OF THE RUC FOR THE NEXT 12 TO 24 HRS. NOT MUCH CHANGE TO THE FORECAST THAT WAS UPDATED THIS MORNING. HAVE HEAVIEST SNOW AMOUNTS ACROSS SOUTHERN SD AND ALONG THE EASTERN SLOPES OF THE HILLS. MAIN BANDS OF SNOW WILL SHIFT ACROSS WESTERN NEB AND SOUTHERN SD LATE THIS AFT AND NIGHT WITH MAIN ACCUMULATIONS DURING THIS TIME. BEST PERIOD FOR ENHANCED UPSLOPE ALONG THE EASTERN SLOPES OF THE HILLS WILL BE LATE THIS AFTERNOON AND EVENING AS EASTERLY WINDS INCREASE...BEST MOISTURE IS IN PLACE...AND FROUDE NUMBER IS MOST FAVORABLE. WILL STILL GO WITH GENERAL 6 TO 12 INCH AMOUNTS IN THE WARNED AREAS...WITH LOCALLY HIGHER AMOUNTS ACROSS FAR SOUTHERN SD POSSIBLE. 3 TO 7 INCH AMOUNTS EXPECTED IN THE ADVISORY AREAS...WITH LITTLE OR NOTHING ACROSS MUCH OF NORTHWEST SD. SNOW SHOULD BEGIN TO WIND DOWN BY THURSDAY MORNING AT MOST LOCATIONS...SO WILL SHORTEN UP THE LENGTH OF THE HEADLINES...HAVING THEM END LATE IN THE MORNING. THERE WILL STILL BE SOME SNOW SHOWERS AROUND INTO THE AFTERNOON...ESPECIALLY ACROSS THE HILLS AREA...AS LAPSE RATES REMAIN STEEP. AS SYSTEM EXITS...ARCTIC AIR WILL BE ABLE TO POUR IN LATE IN THE DAY AND THURSDAY NIGHT. SOME BRISK WINDS CAN BE EXPECTED ACROSS THE PLAINS AND WITH COLD TEMPS THURSDAY...WIND CHILLS WILL BE A CONCERN. WILL HOLD OFF ON ANY KIND OF HEADLINES FOR THIS RIGHT NOW...BUT WILL MAKE NOTE OF LOW WIND CHILLS IN THE ZONES. ARCTIC AIRMASS ACROSS THE REGION WILL MAKE FRIDAY THE COLDEST DAY OF THE SEASON WITH HIGH TEMPERATURES STRUGGLING TO REACH ZERO. AN ELONGATED UPPER TROUGH AXIS WILL SLIDE SE FROM CANADA BRINGING A CHANCE OF SOME MORE SNOW...BUT QPF AMOUNTS SHOULD REMAIN RATHER LIGHT UNDER A TENTH OF AN INCH. TEMPS WILL AGAIN DROP FRI NIGHT TO THEIR COLDEST VALUES ANYWHERE FROM 20 BELOW TO 10 BELOW. MAV AND MET BOTH SEEM TO BE IN FAIRLY GOOD AGREEMENT AT THIS POINT WITH MIN TEMP VALUES...WHICH WAS TRENDING COLDER IN THE LATEST RUNS. AS WEAK WARM AIR ADVECTION BEGINS IN THE LOWEST LEVELS...SATURDAY WILL SEE SLIGHTLY WARMER TEMPS THAN FRIDAY WITH HIGHS IN THE SINGLE DIGITS...BUT THIS TIME ABOVE ZERO. WITH CYCLONIC FLOW CONTINUING OVER THE AREA SATURDAY..COULD SEE SOME SNOW PARTICULARLY ACROSS THE FAR SOUTHERN ZONES...OTHERWISE EXPECT CLOUD COVER TO PERSIST. EXTENDED...WARMING TREND WILL CONTINUE IN THE LONG TERM THROUGH THE FIRST HALF OF THE NEXT WORK WEEK. A COLD FRONT WILL CROSS THE AREA LATE MONDAY INTO EARLY TUESDAY WHICH WILL BRIEFLY STALL THE WARMING TREND TUESDAY. NORTHWEST FLOW WILL REMAIN OVER THE AREA AS THE REGION IS PINNED BETWEEN A TROUGH ACROSS THE EASTERN CONUS AND A RIDGE OVER THE PACIFIC COAST. WEAK DISTURBANCES ARE PROGGED TO CROSS THE AREA INTO THE MID WEEK TIMEFRAME. WILL HOLD OFF ON ANY POPS FOR NOW SINCE MODELS DO NOT USUALLY RESOLVE THE TIMING AND INTENSITY OF THESE SHORTWAVES WITH MUCH SKILL ON DAYS 6 AND 7. && .AVIATION...WIDESPREAD IFR CONDITIONS ARE EXPECTED THROUGH THE OVERNIGHT HOURS AS SNOW CONTINUES TO FALL. SNOW IS EXPECTED TO GRADUALLY LET UP THROUGH TOMORROW MORNING...BUT WITH ONSET OF SNOW SHOWERS CIGS ARE EXPECTED TO FLUCTUATE BETWEEN IFR AND LOW MVFR FOR MOST OF THE DAY TOMORROW. && .UNR...WATCHES/WARNINGS/ADVISORIES... SD...WINTER STORM WARNING THROUGH THURSDAY MORNING FOR THE BLACK HILLS AREA AND SOUTHERN SOUTH DAKOTA. ...WINTER WEATHER ADVISORY THROUGH THURSDAY MORNING FOR THE SPEARFISH FOOTHILLS...SOUTHERN MEADE COUNTY...AND HAAKON COUNTY. WY...WINTER STORM WARNING THROUGH THURSDAY MORNING FOR SOUTHERN CAMPBELL COUNTY...WESTON COUNTY...AND THE WYOMING BLACK HILLS. ...WINTER WEATHER ADVISORY THROUGH THURSDAY MORNING FOR NORTHERN CAMPBELL COUNTY AND THE CROOK COUNTY PLAINS. && $$ sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 340 PM CST WED FEB 15 2006 .SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT CONCERN CONTINUES TO BE ON STORM SYSTEM HITTING THE REGION TONIGHT INTO THURSDAY. LATEST MSAS ANALYSIS SHOWS THE SFC STILL CENTERED OVER WESTERN COLORADO...WITH THE AREA OF ARCTIC HIGH PRESSURE IN CONTROL OF THE EASTERN PORTION OF THE NORTHERN PLAINS. REGIONAL RADAR IMAGERY INDICATES AREA OF SNOW ACROSS MUCH OF THE SOUTH HALF OF WESTERN SOUTH DAKOTA...ALL OF WESTERN NEBRASKA...AND MUCH OF WYOMING. ALSO HAVE A DECENT STREAM OF COOLING CLOUD TOPS WITH THE SNOW OVER WESTERN AND CENTRAL SD...SHOWING INDICATIONS THAT THE SNOWFALL INTENSITY SHOULD PICK UP OVER THE NEXT FEW HOURS. CALLS TO JONES COUNTY WHERE IT HAS BEEN SNOWING FOR ABOUT 3 HOURS INDICATE AROUND A HALF AN INCH HAS FALLEN SO FAR. THE UPPER LEVEL LOW CONTINUES TO SLOWLY EJECT OUT OF THE GREAT BASIN...WHILE THE PARENT LOW CONTINUES TO SPIN OVER THE HUDSON BAY AREA. THE UPPER LOW WILL EJECT TO THE NORTHEAST AND IS EXPECTED TO BE OVER SD BY THURSDAY AFTERNOON. THE ASSOCIATED SFC LOW WILL PUSH TO THE SOUTHEAST OF THE CWA...WITH THE GREATEST FORCING STILL EXPECTED ALONG AND TO THE SOUTH OF THE I-90 CORRIDOR IN SOUTH DAKOTA. THE LATEST RUC SHOWS INCREASING AMOUNTS OF LIFT INDICATED IN THE MID-LEVEL OMEGA FIELDS THROUGH THE EVENING...WITH SLIGHT ISENTROPIC UPGLIDE OVER THE SAME AREA EARLY THIS EVENING ON THE 280K THETA SURFACE. BEST FRONTOGENETIC LIFT IS OVER THE SOUTH CENTRAL CWA TONIGHT...THEN SLIDING EASTWARD THROUGH THE THURSDAY AS THE SYSTEM LIFTS INTO THE NORTHERN PLAINS. WWD GRAPHICS INDICATE POTENTIAL FOR SLIGHTLY LESS SNOWFALL ACROSS THE SOUTH CENTRAL ZONES...HOWEVER THEY STILL PAINT AN AREA OF AROUND 6 INCHES ACROSS THE SOUTHERN PORTIONS OF LYMAN AND JONES COUNTIES. LATEST GFS/NAM RUNS IN GOOD AGREEMENT WITH THE GFS BRINGING THE LIFT SLIGHTLY FURTHER NORTH THAN THE NAM. THEREFORE DID ADD IN A MENTION OF SLIGHT CHANCE POPS ACROSS THE NORTH CENTRAL ZONES...AND FLURRIES ACROSS THE NORTHERN TIER THE REMAINING COUNTIES IN THE NORTHEASTERN CWA THAT PREVIOUSLY HAD NO PRECIPITATION MENTION. SYSTEM SHOULD LIFT OUT THURSDAY WITH SNOW ENDING ACROSS THE CWA FROM WEST TO EAST THROUGH THE DAY. GFS HINTS AT SOME WEAK LIFT ACROSS THE WESTERN CWA LATER IN THE DAY THURSDAY AND THURSDAY NIGHT AHEAD A SECONDARY PUSH OF ARCTIC AIR. THEREFORE INSERTED CHANCE POPS FOR LIGHT SNOW ACROSS THE WESTERN CWA THURSDAY NIGHT...AND FLURRIES FOR MIDDLE THIRD OF THE CWA. WITH THE COLD ARCTIC AIR PUSHING INTO THE CWA...AND SOME PEEKS IN THE CLOUDS EXPECTED ACROSS THE EXTREME EASTERN CWA THURSDAY NIGHT...DID DROP TEMPS A DEGREE OR SO. OTHERWISE TEMPERATURES ARE ON TRACK. ALSO CONCERN FOR DANGEROUS WIND CHILLS STILL AN ISSUE TO MONITOR FOR THURSDAY NIGHT. COULD SEE SOME WIND CHILLS CLOSE TO ADVISORY CRITERIA LATE TONIGHT INTO THURSDAY...BUT SHOULD STAY IN THE -15 TO -20 RANGE SO SHOULD NOT NEED A HEADLINE QUITE YET. HOWEVER MUCH OF THE CWA HAS WIND CHILL VALUES FALL INTO THE -20F TO -35F RANGE WITH WINDS ABOVE 10 MPH THURSDAY NIGHT SO MOST LIKELY WILL NEED AN ADVISORY FOR THAT PERIOD. .MID TERM...FRIDAY AND SATURDAY CONCERNS THROUGH THE PERIOD ARE THE PRECIPITATION CHANCE INTO THE DAYTIME FRIDAY...AND COLD TEMPERATURES THROUGHOUT THE WEEKEND. TO START THIS PERIOD A WOBBLE IN THE LARGE POLAR VORTEX USHERS IN THE RELATIVE COLDEST AIR OF THE FORECAST PERIOD. TEMPERATURES AT 850HPA FALL FROM THE MINUS TEENS CELSIUS ON THURSDAY 18Z TO THE LOW 30S TO MID 20S BELOW ZERO BY 18Z FRIDAY. GFS AND NAM BOTH AGREE THAT NOSE OF DENSE COLD PUSH WILL BE FRONTOGENETIC ACROSS SOUTH DAKOTA. ISENTROPIC ANALYSIS ALSO SUGGESTS THAT PRESSURE ADVECTION ABOVE COLD DOME WILL ALLOW FOR LIGHT SNOW PROBABILITIES ACROSS THE CWA FOR THE START OF THE MIDTERM. EXPECT CLOUDS ABOVE LARGE TEMPERATURE INVERSION BEHIND THE POLAR AIRMASS PUSH...UNTIL STRONG 1040MB PLUS SURFACE HIGH PRESSURE GRIPS CONTROL. DROPPED INHERITED MAXIMUM TEMPERATURES A FEW DEGREES ON FRIDAY BETWEEN GUIDANCE VALUES. QUESTIONING THE TENDENCY OF THE MODELS TO MODERATE THE POLAR AIRMASS WAY TOO QUICKLY INTO SATURDAY. CUT TEMPERATURE VALUES CLOSE TO NEIGHBORS...WAY BELOW GUIDANCE..BUT COULD SEE A PERSISTENCE IN SATURDAY MAXIMUM TEMPERATURES BELOW THE ZERO MARK. .LONG TERM...SUNDAY THROUGH WEDNESDAY COLD UPPER FLOW CONTS THROUGH EXTENDED PERIOD...WITH STRONG UPPER LOW SHEARING SLOWLY TOWARD THE EAST BUT ELONGATED E-W TROF STRETCHING ACROSS NORTHERN PLAINS. 5H TEMPS BEGIN EXTENDED IN THE MINUS 30 TO 35 CELCIUS RANGE...AND LOWER INTO THE MINUS 40'S CELCIUS BY 12Z TUESDAY. 85H TEMPS CONT TO HOVER IN THE MINUS TEENS TO MINUS 20S THROUGH THE PERIOD. LATEST GFS GUIDANCE ACTUALLY SHOWS A SMALL WARMING TREND BEGINNING THE FIRST OF THE WEEK. HOWEVER AM GOING TO DISREGARD FOR NOW AND CONT CHILLY TEMPS THROUGH WEDNESDAY. AS FOR PCPN CHCS...GFS CONTS TO SHOW MINOR WAVES DROPPING OVER CWA IN COLD FLOW. WITH SUCH COLD 5H TEMPS ALOFT...ANY WAVE WOULD BE ABLE TO WRING OUT A FLURRY OR TWO...BUT DETERMINING WHICH ONE WOULD IS DIFFICULT AT BEST. SPECIFICALLY FOR SUNDAY-MONDAY TIME PERIOD...UPPER SUBSIDENCE MOVES INTO CWA BEHIND PASSING SFC FRONT. GFS HINTS AT SMALL AMOUNTS OF 85H-7H Q-VECTOR CONVERGENCE FROM LATE SUNDAY AFTERNOON TO EARLY MONDAY MORNING. FOR NOW...WILL LEAVE PCPN GRIDS AS IS...WITH SLGT CHC S- MONDAY AFTERNOON AND DRY FOR REMAINING PERIODS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER STORM WARNING FOR JONES AND LYMAN COUNTIES THROUGH 18Z THURSDAY. SNOW ADVISORY FOR STANLEY...HUGHES...AND BUFFALO COUNTIES FROM THROUGH 18Z THURSDAY. MN...NONE. && $$ ALBRECHT/BEHNKE/HINTZ sd