Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/28/12


AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
102 AM EST WED DEC 26 2012 .PREV DISCUSSION... /ISSUED 737 PM EST TUE DEC 25 2012/ .SEVERE STORMS INCLUDING A FEW TORNADOES LIKELY TONIGHT/EARLY WED MORNING... .UPDATE... MAIN CONVECTIVE LINE AHEAD OF COLD FRONT IS PROGRESSING QUICKER THAN ANTICIPATED ACROSS CENTRAL AL THIS EVENING AND ARE NOW LOOKING AT POTENTIAL FOR SEVERE THREAT BEGINNING NEAR 03Z IN WESTERN PORTIONS OF THE FORECAST AREA. SOME DISCRETE CELLS SHOWING SIGNS OF ROTATION HAVE BEEN TRACKING MOSTLY NORTHWARD ACROSS SOUTHEASTERN AL NEAR THE NORTHERN EXTENT OF THE WARM SECTOR. BASED ON PROGGED SHORT RANGE ENSEMBLE MEMBERS... THE SOUTHWESTERN PORTION OF CENTRAL GA LOOKS TO HAVE THE BETTER INSTABILITY TONIGHT POTENTIALLY GETTING UP TO 500 J/KG OF MUCAPE...WHILE A LINGERING HYBRID CAD DOME HAS PRIMARILY SERVED TO LIMIT INSTABILITY FARTHER NORTHWARD. EARLIER SHOWER DEVELOPMENT DURING THE DAY MAY HAVE REINFORCED THIS FEATURE AND WILL MONITOR CONDITIONS CLOSELY. ALL CONSIDERED... BELIEVE BEST CHANCE FOR ISOLATED TORNADO POTENTIAL WILL BE SOUTHERN/SOUTHWESTERN TIER MAINLY SOUTH OF COLUMBUS AND MACON. MADE ADJUSTMENTS TO POP/WX GRIDS BASED ON PROGRESSION OF AFOREMENTIONED CONVECTION. BAKER && PREV DISCUSSION... /ISSUED 309 PM EST TUE DEC 25 2012/ .SHORT TERM /TONIGHT THROUGH THURSDAY/... INGREDIENTS STILL COMING TOGETHER FOR NOCTURNAL SEVERE WEATHER EVENT AFTER MIDNIGHT TONIGHT. 12Z RUNS HAVE CONTINUED TREND OF MORE FAVORABLE PARAMETERS. 0-1KM BULK SHEAR OF 45-55KT NOW IN BOTH NAM AND GFS...THOUGH THESE ARE SOMEWHAT EAST OF BEST MOISTURE/CAPE AXIS. IN SPITE OF THIS...FCST SIG TOR PARAMETER VALUES ARE NOW 1.5-2.5 IN GFS AND 4-5 WITH THE NAM. TORNADO THREAT IS QUITE HIGH FOR A COOL SEASON QLCS EVENT. TIMING ON GFS AND ECMWF HAS SHIFTED SLIGHTLY BACK TO BETTER MATCH THE SLOWER NAM. LATEST HRRR NOW SIMILAR TO GFS TIMING. DUE TO UNCERTAINTY IN MODELS AND WHETHER ANY PREFRONTAL STORM ACTIVITY WILL DEVELOP...HAVE NOT TWEAKED TIMING BACK TOO MUCH. TOTAL RAINFALL STILL HARD PRESSED TO EXCEED 2 INCHES. NO SIGNIFICANT FLOODING PROBLEMS EXPECTED. AFTER FRONT PASSES...PRECIP SHOULD END QUICKLY. WILL BE ISSUING A WIND ADVISORY FOR THE ENTIRE AREA BUT STARTING A LITTLE SOONER IN THE MOUNTAINS AS LOW LEVEL FLOW OF 50KTS COULD MIX DOWN TO HIGHER ELEVATIONS. ALSO HAVE CONTINUED SLT CHC/CHC RAIN/SNOW SHOWER MIX OVER PARTS OF FAR NE GA WED NIGHT. SHOULD NOT SEE ANY ACCUMULATION. REST OF FCST LOOKS GOOD. WE WILL CONTINUE TO MONITOR THE SITUATION. SNELSON && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... THE LONG TERM PORTION OF THE FORECAST BEGINS WITH WRAP AROUND MOISTURE FROM THE BACK SIDE OF THE EXITING LOW PRESSURE SYSTEM ACROSS N GA. COOLER AIR WILL ALSO BE FILTERING INTO THE STATE BUT IT LOOKS LIKE THE BETTER MOISTURE WILL STAY FAR ENOUGH NORTH THAT IT SHOULD NOT CAUSE ANY WINTER PRECIP ACROSS THE N GA MOUNTAINS THU NIGHT/FRIDAY MORNING. HIGH PRESSURE BUILDS IN THURSDAY WITH MOISTURE BEGINNING TO RETURN TO THE REGION FRIDAY. MOISTURE BEGINS PUSHING IN AHEAD OF NEXT SYSTEM WHICH WILL BRING ANOTHER ROUND OF PRECIP TO THE STATE FRIDAY NIGHT/SATURDAY. THIS NEXT SYSTEM DOES NOT LOOK AS STRONG AS THE ONE THAT WILL MOVE THROUGH TONIGHT...SO WILL CONTINUE WITH ONLY SHOWERS FOR NOW. THE MODELS SHOW THIS SECOND SYSTEM MOVING THROUGH THE AREA VERY FAST WITH THE RAIN MOVING INTO W GA AROUND 06Z SAT AND THE ENTIRE SYSTEM EXITING THE EAST SIDE OF THE STATE BY 18Z SAT. A STRONG HIGH PRESSURE RIDGE BUILDS IN BEHIND THIS SECOND SYSTEM AND IT LOOKS TO KEEP NORTH AND CENTRAL GEORGIA DRY SUNDAY AND MONDAY. 01 && .HYDROLOGY... FLASH FLOOD GUIDANCE REMAINS IN THE 1.5/2.5/3.0 FOR 1H 3H 6H GUIDANCE RESPECTIVELY. THESE ARE SLIGHTLY REDUCED VALUES WITH RECENT RAINS BUT LIKELY NOT SUFFICIENT FOR SIGNIFICANT FLOODING CONCERNS GIVEN INITIAL LIGHT TO MODERATE RAIN AHEAD OF SYSTEM AND THEN RAPID MOVEMENT OF COLD FRONT ONCE CONVECTIVELY ENHANCED BANDS SET UP. STILL WILL BE CLOSELY MONITORING THE NEXT 24 HOUR FOR ANY SHORT FUSE RIVER AND STREAM WARNINGS PRIMARILY. && .AVIATION... 06Z UPDATE... IFR TO NEAR HIGH END LIFR CIGS CONTINUE TO LINGER ACROSS MOST SITES TONIGHT. HEIGHTS SHOULD IMPROVE TO MVFR LEVELS NEAR 1500-2500 FT AFTER 08Z FROM THE WEST...AND ARE LIKELY TO LINGER ON INTO WEDNESDAY NIGHT. AREA OF WIDESPREAD SHOWERS AND THUNDERSTORMS CONTINUES TO PUSH EAST TONIGHT...WHILE BEST CHANCE FOR TSRA LOOKS TO BE SOUTH NEAR KCSG AND KMCN...AND RA TO -SHRA LIKELY FARTHER NORTH THOUGH CANNOT RULE OUT ISOLATED THUNDER. OVERNIGHT WINDS SE NEAR 12 KTS GUSTING TO 20 KTS WITH POSSIBLE HIGHER VALUES FROM ANY STORM DEVELOPMENT. MOST PRECIP SHOULD PUSH EAST OF THE SITES FROM ABOUT 10-12Z. WESTERLY WINDS OF NEAR 20 KTS WITH STRONG GUSTS OF 30-35 KTS ARE POSSIBLE FOR MOST SITES FROM ABOUT 17-01Z. VSBYS OF 4-6 SM OVERNIGHT WITH POSSIBLY LOWER IN PRECIP AREAS... THEN P6SM AFTER ABOUT 11Z. //ATL CONFIDENCE...06Z UPDATE... MEDIUM CONFIDENCE ON ENDING TIME FOR PRECIPITATION. HIGH CONFIDENCE ALL ELSE. BAKER && .PRELIMINARY POINT TEMPS/POPS... ATHENS 52 31 51 30 / 80 0 0 0 ATLANTA 49 30 49 32 / 20 0 0 0 BLAIRSVILLE 48 28 45 28 / 80 20 0 0 CARTERSVILLE 50 31 46 27 / 20 0 0 0 COLUMBUS 51 33 53 31 / 20 0 0 0 GAINESVILLE 50 31 48 32 / 60 0 0 0 MACON 55 33 54 29 / 60 0 0 0 ROME 49 32 47 26 / 20 5 0 0 PEACHTREE CITY 49 31 50 25 / 20 0 0 0 VIDALIA 60 36 56 36 / 80 0 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BIBB... BLECKLEY...BUTTS...CARROLL...CHATTAHOOCHEE...CLARKE...CLAYTON... COBB...COWETA...CRAWFORD...CRISP...DEKALB...DODGE...DOOLY... DOUGLAS...EMANUEL...FAYETTE...FORSYTH...GLASCOCK...GREENE... GWINNETT...HALL...HANCOCK...HARALSON...HARRIS...HEARD...HENRY... HOUSTON...JACKSON...JASPER...JEFFERSON...JOHNSON...JONES... LAMAR...LAURENS...MACON...MADISON...MARION...MERIWETHER... MONROE...MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE... PULASKI...PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING... STEWART...SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR... TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES...WILKINSON. TORNADO WATCH UNTIL 5 AM EST EARLY THIS MORNING FOR THE FOLLOWING ZONES: CHATTAHOOCHEE...HARRIS...MACON...MARION... MERIWETHER...MUSCOGEE...PIKE...SCHLEY...STEWART...SUMTER... TALBOT...TAYLOR...TROUP...UPSON...WEBSTER. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON... FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS... POLK...TOWNS...UNION...WALKER...WHITE...WHITFIELD. && $$ SHORT TERM...SNELSON/BAKER LONG TERM....01 AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1248 AM EST WED DEC 26 2012 .AVIATION... /06 UTC TAFS/ DETERIORATING MET CONDS ACRS NRN IN LATER THIS AM AS INTENSE STORM SYSTEM ACRS WRN TN TO MOVE INTO THE SOUTHERN OHIO VALLEY TODAY...THEN SHIFT ABRUPTLY EWD THIS EVENING AS FORCING FOCUS SHIFTS TO MID ATL REGN. STILL CONDS LKLY INTO IFR/TEMPO LIFR ESP ACRS NERN IN/WRN OH IN VCNTY OF BEST MSTR SOURCE. MINIMIZED FUEL ALT/LIFR AT KSBN TIL AFTN HOURS...WELL ON WRN FRINGE OF SYSTEM. GRTR CONFIDENCE WRT LIFR/EXTENDED FUEL ALT CONDS AT KFWA WITH HEAVIER SNOW BURST TIMED TO BEST OVERLAP OF MESOSCALE FEATURES. RAPID IMPROVEMENT NOTED AT END OF FCST PD...HIGHLIGHTING BRIEF/THOUGH SUBSTANTIVE IMPACT. && .PREV DISCUSSION... /ISSUED 811 PM EST TUE DEC 25 2012/ UPDATE... OBSERVATION/MODEL TRENDS CONT TO SUPPORT SNOW AND STRONG WINDS CAUSING BLOWING AND DRIFTING SNOW MAINLY ACROSS SE 1/2 OF CWA WED AS STRONG LOW OVER MS THIS EVE LIFTS NE TO VA BY WED EVE. LEADING EDGE OF PRECIP ASSOCIATED WITH THE LOW WAS LIFTING NORTH INTO SRN KY/SE MO ATTM... A LITTLE QUICKER THAN INDICATED BY LATEST MODEL QPFS... BUT STILL PLENTY FAR ENOUGH AWAY FROM OUR CWA TO REMOVE SLIGHT CHC POPS FOR THIS EVE IN THE GRIDS... WITH SNOW MENTION NOW CONFINED TO AFT 06Z. OTRWS NO CHANGES TO AFTN FCST PLANNED THIS EVE. PREV DISCUSSION... /ISSUED 406 PM EST TUE DEC 25 2012/ SHORT TERM... TONIGHT THROUGH WEDNESDAY NIGHT... SIGNIFICANT WINTER STORM TO IMPACT MUCH OF THE CWA IN THE SHORT TERM. WATER VAPOR IMAGERY SHOWING POTENT UPPER LOW DIGGING THROUGH TEXAS. 12Z RAOB AND LATEST RAP ANALYSIS HAS 100KT+ UPPER JET COMING INTO THE BASE OF THE TROUGH. ASSOCIATED SFC LOW NEAR TX/LA BORDER AT 18Z AND IS EXPECTED TO LIFT NE INTO THE CENTRAL TN VALLEY BY 12Z WED. GOOD ISENT ASCENT AHEAD OF THIS SYSTEM ALONG THE 290-295K SFC IS EXPECTED TO INITIATE PRECIP IN THE FAR SOUTHERN CWA AFTER MIDNIGHT TONIGHT WITH LARGE SCALE FORCING TO INTENSIFY PRECIP TO MOD-HVY SNOW AFTER 12Z. DESPITE A TREND TO A MORE SE TRACK...GOOD DEFORMATION AXIS STILL SETS UP OVER SE CWA ALONG WITH SUBSTANTIAL HEIGHT FALLS IN A DEEP MOISTURE COLUMN TO SUPPORT A WINDOW OF OPPORTUNITY FOR WARNING CRITERIA SNOWFALL. STRONG GRADIENT BRINGING 15 TO 25 MPH WINDS WITH GUSTS TO 30 MPH LENDS FURTHER CREDENCE IN MAINTAINING WINTER STORM WARNING. HAD TRANSITIONED REMAINING COUNTIES IN THE WATCH OVER TO AN ADVISORY WITH GENERALLY 1-3/2-4 INCH AMOUNTS BUT ALSO ACCOMPANIED BY GUSTY WINDS FOR BLOWING SNOW. POTENTIAL FOR MOD-HVY SNOW WILL BE SHORT-LIVED HOWEVER AS SYSTEM WILL QUICKLY EXIT TOWARD THE EAST COAST WEDNESDAY NIGHT. LONG TERM... THURSDAY THROUGH TUESDAY...THE CHALLENGES THIS PERIOD INCLUDE CHANCES FOR SNOW WITH THE PASSAGE OF A WEAK UPPER TROF LATE THIS WEEK. ALSO...HIGH AND LOW TEMPERATURES WITH AN EXTENDED PERIOD OF COLD AIR AND SNOW COVER OVER AT LEAST PART OF THE FORECAST AREA WILL PROVIDE ADDITIONAL CHALLENGES. FOR THIS PACKAGE...FAVORED THE GFS. THE GFS HAS AT LEAST AS GOOD OF RUN TO RUN CONSISTENCY AS THE ECMWF AND APPEARS TO BE HANDLING THIS PATTERN REASONABLY WELL. THE GFS TIMING OF THE SYSTEM LATE THIS WEEK HAS ALSO BEEN CONSISTENT FOR THE PAST 8 RUNS AND APPEARS ON TRACK. ALSO...THE OPERATION MOS AND ENSEMBLE MOS HAS BEEN RELATIVELY STABLE IN ITS OUTPUT FOR SEVERAL DAYS AND APPEARS IN LINE. HAVE MODIFIED HIGH AND LOW TEMPS GIVEN SNOW FIELD CONSIDERATIONS. AT THE START OF THE PERIOD...DOWNWARD MOTION WILL HAVE INCREASED SIGNIFICANTLY AS EVIDENCE OF NET ISENTROPIC ADIABATIC OMEGA WITH A DRYING OF THE MID LEVELS. AS A RESULT...HAVE REMOVED LINGERING FLURRIES THURSDAY OVER NW OHIO. FOR THE REST OF THE PERIOD...TRIED TO PUT SOME DETAIL IN THE TIMING OF THE UPPER LEVEL TROF THIS WEEKEND AND SUBSEQUENT LAKE EFFECT SNOW SHOWERS. THERE IS LITTLE MOISTURE TO WORK WITH AND FORCING IS WEAK...SO ANY SNOW AMOUNTS SHOULD BE LIGHT. LAKE EFFECT PARAMETERS ARE VERY MARGINAL WITH A LIMITED FETCH. DELTA T VALUES GENERALLY SHOULD BE 10 TO 14 WITH LOW INVERSION HEIGHTS. REMOVED THE CHANCE FOR SNOW SUNDAY AND SUNDAY NIGHT. GFS BUFKIT PROFILE SUPPORTS FREEZING DRIZZLE OVER SNOW GIVEN THE LACK OF ICE INDUCED IN THE CLOUD LAYER. TEMPERATURES IN A DEEP LAYER WARM ABOVE -10C. NOT OPTIMISTIC ABOUT SNOW CHANCES MONDAY... BUT FOR THE SAKE OF CONSISTENCY AND LINGERING UNCERTAINTY ABOUT EARLY NEXT WEEK...LEFT LAKE EFFECT SNOW SHOWERS IN THE FORECAST MONDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR INZ009. WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR INZ018-025>027-032>034. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR INZ005>008. WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR INZ015>017-020-022>024. MI...WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR MIZ079>081. OH...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR OHZ001-002-004-005. WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR OHZ015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ043-046. && $$ SHORT TERM...JAL LONG TERM...SKIPPER UPDATE...JT AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS DES MOINES IA
548 AM CST WED DEC 26 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TODAY/... THE FORECAST AREA WILL REMAIN IN THE WEAK CAA TODAY AS THE STRONG WINTER STORM TO THE SOUTHEAST CONTINUES TO PRESS FURTHER EAST...WHILE THE SURFACE HIGH CENTERED OVER THE DAKOTAS/NORTHERN MINNESOTA WILL SLOWLY NUDGE INTO NORTHERN IOWA. WILL SEE HIGH CIRRUS SHIELD CURRENTLY OVER MUCH OF THE FORECAST AREA DRIFT EAST WITH THE STRONG SURFACE LOW. THIS CLOUD DECK WILL HINDER MAX TEMPS SLIGHTLY TODAY...ESPECIALLY ACROSS THE EAST. SO WENT CLOSER TO THE COOLER MAV MOS ACROSS THE EAST...AND MORE TOWARDS THE WARMER SREF/NAM BLEND TO THE WEST. .LONG TERM /TONIGHT THROUGH TUESDAY/... STRONG UPPER LEVEL PV ANOMALY AND ASSOCIATED SHORT WAVE CURRENTLY MOVING INTO CNTRL CALIFORNIA THIS MORNING...IS THE PRIMARY SYSTEM EXPECTED TO IMPACT IOWA THROUGH THE PERIOD. ANOTHER STRONG SYSTEM IS MOVING THROUGH THE SOUTHEASTERN CONUS WILL LIFT THROUGH THE UPPER OHIO VALLEY AND INTO THE NEW ENGLAND REGION TODAY THROUGH THURSDAY. THIS SYSTEM IS DELAYING THE ARRIVAL OF THE WESTERN ENERGY A BIT AND MORE INTO THURSDAY NIGHT AND FRIDAY. BEFORE THEN...RIDGE OF HIGH PRESSURE WILL SLIDE EAST THROUGH CNTRL IA TONIGHT. OVERNIGHT LOW TEMPERATURES TONIGHT ARE DIFFICULT WITH A FAIR AMOUNT OF CLOUD DEBRIS UNDER THE HIGH. TEMPERATURES UNDER THE RIDGE CURRENTLY ARE ZERO TO 5 ABOVE AND READINGS SHOULD BE SIMILAR TONIGHT THOUGH CLOUD COVER SHOULD BEGIN INCREASING LATE AHEAD OF THE NEXT SYSTEM. GOOD THETA-E ADVECTION COMMENCES OVER SOUTHWEST IA THURSDAY MORNING AND LIFTING INTO CNTRL IA BY THE AFTERNOON. THE ARRIVAL WILL COINCIDE WITH THE ARRIVAL OF QG FORCING ASSOCIATED WITH THE APPROACHING SHORT WAVE. THE INITIAL FORCING WILL BE BURNT SATURATING THE DRY AIR BELOW 750 MB. ONCE SATURATION OCCURS...EXPECT A PROLONGED PERIOD OF GENERALLY LIGHT SNOW THAT COULD BECOME MODERATE AT TIMES CENTRAL AND NORTH. ONCE AGAIN A STRONGER SYSTEM WILL DEVELOP TO THE SOUTH DURING THIS PERIOD. THE SOUTHERN SYSTEM WILL STREAM ADDITIONAL MOISTURE NORTHWARD ALONG THE INVERTED TROUGH AXIS. FORCING PIVOTING THROUGH THE STATE INTO FRIDAY ALONG WITH SOME MOISTURE FLOW FROM THE WARM CONVEYOR OF THE SYSTEM TO THE SOUTH WILL KEEP SNOW CONTINUING INTO FRIDAY. STILL EXPECT SNOWFALL AMOUNTS OF 1 TO 3 INCHES TO BE COMMON WITH SNOW TO LIQUID RATIOS OF 15-20 TO 1 LIKELY. A DEEP DENDRITIC GROWTH ZONE DESPITE RELATIVE WEAK OVERALL FORCING COULD PUSH A FEW AREAS ABOVE 3 INCHES...ESPECIALLY OVER THE NORTH. FORTUNATELY...THERE WILL BE LITTLE TO NO WIND TO BLOW THIS FLUFFY NEW SNOW AROUND. THE REMAINDER OF THE FORECAST WILL BE QUIET THROUGH THE WEEKEND INTO EARLY NEXT WEEK. THE END OF THE WEEK SYSTEM WILL SHIFT EAST WITH WEAK RIDGING INTO IOWA FOR THE WEEKEND. A GOOD REMAINING SNOW PACK WILL LIMIT HIGH TEMPERATURES THROUGH THE PERIOD BUT MOSTLY DRY CONDITIONS WILL PREVAIL. THE STATE WILL BE STUCK BETWEEN AN EASTERN CANADA/NORTHEAST CONUS TROUGH AND AN UPPER LEVEL LOW DROPPING INTO THE DESERT SOUTHWEST BY EARLY NEXT WEEK. && .AVIATION...26/12Z MVFR STRATUS WILL PERSIST ACROSS SOUTHEAST IOWA THROUGH THE MORNING HOURS. RAP40/NAM12 HAVE THE STRATUS DECK SHIFTING FURTHER WEST BUT SOMEWHAT DISSIPATING PAST 15Z. MAY SEE A BRIEF PERIOD OF MVFR CIGS AT DSM/ALO...BUT LOW CONFIDENCE WITH STRATUS MOVING THAT FAR WEST. THE LATEST HRRR KEEPS THE STRATUS IN ITS CURRENT LOCATION BEFORE MOVING IT EASTWARD LATER THIS MORNING. LARGE SURFACE HIGH BUILDS INTO THE STATE TONIGHT WITH A FAIRLY STRONG INVERSION DEVELOPING OVERNIGHT. THIS LEADS TO A POTENTIAL FOR SOME LOW LEVEL MOISTURE TRAPPED RESULTING IN FOG/STRATUS. LEFT VFR FOR NOW DUE TO LOW CONFIDENCE WITH AMOUNT OF LOW LEVEL MOISTURE PRESENT. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS WICHITA KS
854 PM CST THU DEC 27 2012 .UPDATE... GONNA SEND OUT A QUICK UPDATE TO CHANGE MENTION OF FREEZING DRIZZLE POTENTIAL FOR SOUTHEAST KS...TO MORE OF A PATCHY FREEZING DRIZZLE CHANCE. NOT EXPECTING A WIDESPREAD FREEZING DRIZZLE EVENT...AS LATEST SHORT TERM MODEL SOUNDINGS NOT SHOWING NEAR ENOUGH SATURATION IN THE LOWEST 1000 FEET FOR A WIDESPREAD DRIZZLE CHANCE. BUT SOME SATURATION MAY EXIST IN THE 1000-3000 FOOT LAYER FOR SOME PATCHY DRIZZLE TO FORM...WHICH WOULD FREEZE ON CONTACT GIVEN THE FORECASTED BELOW FREEZING SFC TEMPS ACROSS SOUTHEAST KS. LATEST RUC SOUNDINGS ALSO SUGGEST SOME PATCHY FREEZING FOG JUST AHEAD OF THE SURFACE TROUGH AS IT PUSHES INTO SE KS BY AROUND 12Z/FRI. SO WILL MENTION THIS CHANCE AS WELL. NOT EXPECTING WIDESPREAD TRAVEL ISSUES...WITH MAINLY SOME BRIDGES AND OVERPASSES AFFECTED...SO WILL NOT ISSUE ANY KIND OF WINTER WEATHER ADVISORY HEADLINE. BUT WILL HIT IT HARD IN THE HAZARDOUS WEATHER OUTLOOK OR A SPECIAL WEATHER STATEMENT. KETCHAM && .PREV DISCUSSION... /ISSUED 543 PM CST THU DEC 27 2012/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU THE MAIN AVIATION CONCERN WILL BE THE LOW MVFR/IFR CONDITIONS EXPECTED THROUGH MUCH OF THE FORECAST PERIOD. DIFFICULT FORECAST TONIGHT...WITH MVFR CONDITIONS AT MOST LOCATIONS EXCEPT KCNU. WILL CONTINUE THE PESSIMISTIC FORECAST AT ALL TAF SITES...HAVING MVFR/IFR THROUGH MUCH OF THE FORECAST. WITH SOME IFR CEILINGS FOR KSLN AND KCNU AFTER FRI/05Z. NOT ALOT OF CONFIDENCE IN THIS IFR CLOUD DECK...AND COULD ACTUALLY SEE SOME LIFR CEILINGS DEVELOP. DO NOT SEE AN AREA FOR THE CEILINGS TO IMPROVE MUCH UNTIL DRIER AIR FILTERS INTO THE LOW LEVELS BEHIND THE NEXT WAVE DURING THE DAY ON FRIDAY. THIS WILL LEAD TO ALL TAF SITES IMPROVING TO VFR CEILINGS WITH THE BKN-OVC SKIES CONTINUING. KETCHAM PREV DISCUSSION... /ISSUED 312 PM CST THU DEC 27 2012/ DISCUSSION... TONIGHT-FRIDAY: UPPER TROUGH WILL CONTINUE PUSHING EASTWARD ACROSS THE CENTRAL PLAINS. THIS WILL ALLOW THE POLAR AIR TO PUSH BACK SOUTHEASTWARD ACROSS OUR FORECAST AREA. INITIAL PV ANOMALY IS ALREADY WELL NORTH OF THE AREA OVER NEBRASKA/SOUTH DAKOTA. MEASURABLE SNOW WILL THEREFORE REMAIN WELL NORTHEAST OF OUR AREA. ANOTHER PV ANOMALY WILL TRACK IN THE BASE OF THE TROUGH ACROSS THE SOUTHERN PLAINS TONIGHT INTO FRIDAY. WE DO EXPECT PRESENT AREA OF LOW CLOUDS NEAR AND NORTHWEST OF SURFACE LOW...TO CONTINUE TO WRAP BACK INTO OUR AREA OVERNIGHT INTO FRIDAY MORNING BEHIND THE LOW TRACK. THERE COULD BE PATCHY LIGHT FREEZING DRIZZLE/FOG DEVELOPING IN THE SOUTHEAST COUNTIES LATE TONIGHT/EARLY FRIDAY WITH SLIGHTLY DEEPER LOW-LEVEL MOISTURE IN THE SOUNDING DATA AND WEAK ISENTROPIC UPGLIDE...COINCIDENT WITH WEAK SOUTHERLY FLOW AHEAD OF THE COLD FRONT. HOWEVER...PROBABILITIES SEEM TO BE MORE OPTIMAL JUST TO OUR EAST/SOUTHEAST. BREEZY NORTHWESTERLY WINDS SHOULD HELP SCOUR OUT LOW CLOUDS FRIDAY WITH A CLEAR/COLD NIGHT SLATED FOR FRIDAY NIGHT. SATURDAY-SUNDAY: UPPER LOW WILL BE IN THE PROCESS OF DEVELOPING OVER THE SOUTHWEST...WHILE SURFACE POLAR HIGH SHIFTS EASTWARD OUT OF THE SOUTHERN PLAINS. RELATIVELY LIGHT WESTERLY COMPONENT SATURDAY WILL BACK TO SOUTH-SOUTHWESTERLY SATURDAY NIGHT WITH SPEEDS INCREASING TO BREEZY LEVELS SUNDAY. EXPECTING FULL SUNSHINE SATURDAY WITH PERHAPS SOME HIGH CLOUDS PUSHING IN FROM THE SOUTHWEST ON SUNDAY. OTHERWISE...EXPECTING MODERATING TEMPERATURES TO NEAR CLIMATOLOGY. MONDAY-THURSDAY: MEDIUM RANGE MODELS HAVE COME INTO AGREEMENT ON AN INITIAL SHORTWAVE/PV ANOMALY EJECTING OUT OF THE SOUTHWEST UPPER LOW...ACROSS KANSAS/OKLAHOMA MONDAY INTO MONDAY NIGHT. IN ADDITION...COLDER AIR ASSOCIATED WITH ENERGY IN THE NORTHERN BRANCH JET STREAM...WILL INFILTRATE SOUTHWARD THROUGH OUR AREA. A CONSERVATIVE CHANCE OF RAIN TO SNOW APPEARS REASONABLE AREA-WIDE...WITH RELATIVELY HIGHER PROBABILITIES IN THE SOUTHEAST COUNTIES. IF LATER MODEL RUNS CONTINUE TO SHOW THIS SCENARIO...PROBABILITIES OF PRECIPITATION WILL LIKELY BE INCREASED IN FORTHCOMING FORECASTS ESPECIALLY IN THE SOUTH. THE MAIN UPPER LOW MAY REMAIN SUPPRESSED OVER THE SOUTHWEST INTO MIDWEEK BASED ON THE ECMWF/CANADIAN WHILE LOW-LEVEL HIGH PRESSURE BUILDS INTO KANSAS. SO WILL MAINTAIN DRY FORECAST FOR TUESDAY-THURSDAY. TEMPERATURES ARE PROJECTED TO BE NEAR TO SLIGHTLY BELOW CLIMATOLOGY DURING THE PERIOD. FORECAST CONFIDENCE IS ONLY LOW-MEDIUM GIVEN THE GFS ENSEMBLES SHOW DECENT SPREAD/UNCERTAINTY IN BOTH THE NORTHERN BRANCH AND SOUTHERN BRANCH JETSTREAMS IN THE SPLIT UPPER PATTERN. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 17 30 12 40 / 10 10 0 0 HUTCHINSON 14 26 11 37 / 10 10 0 0 NEWTON 17 27 12 37 / 10 10 0 0 ELDORADO 19 29 11 38 / 10 10 0 0 WINFIELD-KWLD 22 32 13 40 / 10 10 0 0 RUSSELL 8 22 5 36 / 10 0 0 0 GREAT BEND 10 23 8 38 / 10 0 0 0 SALINA 14 24 9 35 / 10 10 0 0 MCPHERSON 14 26 10 36 / 10 10 0 0 COFFEYVILLE 25 34 16 39 / 10 10 0 0 CHANUTE 24 32 15 37 / 10 10 0 0 IOLA 24 31 16 36 / 10 10 0 0 PARSONS-KPPF 26 34 15 38 / 10 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
520 PM CST THU DEC 27 2012 .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... MAIN CONCERN IS THE POTENTIAL FOR MVFR CIGS TO MOVE IN BEHIND THE INVERTED SFC TROUGH LATE TONIGHT. THINK THE NAM IS OVERDONE WITH LOW LEVEL SATURATION DUE TO POOR INITIALIZATION OF SNOW COVER. THEREFORE KEPT CIGS ABOVE 1 KFT AND VSBY 6SM OR BETTER BASED OFF OF MAV GUIDANCE AND RAP FORECAST SOUNDINGS. FORECAST SOUNDINGS SHOW LITTLE IF ANY VERTICAL MOTION WITHIN THE CLOUD SO CONCERNS FOR FREEZING DRIZZLE ARE LOW AT THIS POINT. ALTHOUGH THERE COULD BE SOME -SHSN FRIDAY AFTERNOON GIVEN THE GFS FORECAST SOUNDINGS STEEPENING UP THE LOW LEVEL LAPSE RATES. THIS APPEARS TO BE A LOW PROB EVENT FOR NOW. PREV FORECAST TIMING OF MVFR CIGS MOVING IN LOOKS REASONABLE BASED ON THE TIMING OF THE SFC TROUGH MOVING EAST. NOT SURE HOW LONG THE CIGS WILL LINGER THROUGH THE DAY...SO OPTED TO KEEP A CIG IN THROUGH FRIDAY EVENING WHILE THE UPPER SYSTEM IS STILL OVERHEAD. WOLTERS && .PREV DISCUSSION... /333 PM CST THU DEC 27 2012/ TONIGHT THROUGH FRIDAY...MAIN FOCUS FOR THE SHORT TERM IS ON THE IMPACTS OF THE PASSING UPPER LEVEL TROUGH TONIGHT THROUGH FRIDAY MORNING. AS OF 21Z...THE UPPER LEVEL TROUGH WAS SWEEPING ACROSS THE NORTHERN AND CENTRAL PLAINS WITH THE SURFACE LOW OVER NORTHEAST NEW MEXICO. THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM HAS GENERALLY STAYED NORTH OF THE KANSAS/NEBRASKA BORDER...WITH LIGHT SNOW BEING REPORTED ACROSS MUCH OF NEBRASKA THROUGH THE DAY. AN UPPER LEVEL RIDGE HAS BEGUN TO MOVE ONTO THE PACIFIC COASTLINE...WHICH WILL HELP TO PUSH THE TROUGH ALMOST DUE EAST OVER THE NORTHERN PLAINS THROUGH THE EVENING AND OVERNIGHT HOURS. SOME LIGHT PRECIPITATION MAY STILL BE ABLE TO SKIM ALONG THE KANSAS/NEBRASKA BORDER THIS EVENING AND OVERNIGHT WITH THIS EASTWARD MOVING SYSTEM. THE BIG QUESTION WITH REGARDS TO PRECIPITATION POTENTIAL WILL BE WITH THE AMOUNT OF AVAILABLE MOISTURE OVER THE CWA. MODEL SOUNDINGS SHOW THE LOW LEVELS BECOMING FAIRLY SATURATED UP TO AROUND 850MB OVERNIGHT ACROSS A MAJORITY OF THE CWA. THIS LOW LEVEL MOISTURE COMBINED WITH SOME WEAK ISENTROPIC LIFT MAY BE ENOUGH TO PRODUCE SOME PATCHY FREEZING DRIZZLE AND MAYBE A FEW FLURRIES. MODEL SOUNDINGS SHOW THE LOW LEVEL MOISTURE INCREASING GENERALLY BETWEEN 06Z-09Z AND REMAINING FAIRLY SATURATED THROUGH AROUND 15Z BEFORE GRADUALLY DRYING OUT INTO THE EARLY AFTERNOON HOURS AS THE TROUGH PASSES EAST OF THE AREA. ANY LIGHT SNOW SHOWERS THAT ARE ABLE TO CLIP EXTREME NORTHERN KANSAS ARE NOT EXPECTED TO PRODUCE MORE THAN A DUSTING OF ACCUMULATION...AND CURRENTLY DO NOT ANTICIPATE ANY ICE ACCUMULATIONS WITH THE PATCHY FREEZING DRIZZLE. WITH THE SURFACE LOW OVER NORTHEAST NEW MEXICO...A BOUNDARY STRETCHED INTO NORTH CENTRAL KANSAS THIS AFTERNOON AND WILL GRADUALLY SLIDE SOUTHWARD ACROSS THE CWA THROUGH THE EVENING HOURS...CAUSING WINDS TO SHIFT FROM SOUTHEAST TO NORTHWEST. THIS NORTHWESTERLY FLOW WILL LEAD TO CAA AND OVERNIGHT LOWS DROPPING INTO THE LOW/MID 20S OVER EAST CENTRAL KANSAS AND PLUMMETING INTO THE LOW/MID TEENS ACROSS NORTH CENTRAL AND CENTRAL KANSAS WHERE THE BOUNDARY HAS ALREADY MOVED THROUGH. THESE NORTHWESTERLY WINDS WILL PERSIST THROUGH FRIDAY AND COOL TEMPERATURES DOWN A BIT COMPARED TO TODAY...WITH AFTERNOON HIGHS RANGING FROM LOW 20S OVER NORTH CENTRAL KANSAS TO LOW 30S ACROSS EAST CENTRAL KANSAS. ACH FRIDAY EVENING THROUGH THURSDAY...UPPER LEVEL RIDGING BUILDS INTO THE CENTRAL PLAINS FOR THE WEEKEND WITH DRY CONDITIONS EXPECTED. NOT MUCH CHANGE WAS MADE TO THIS PERIOD AS MODELS ARE STILL IN AGREEMENT WITH LIGHT WINDS BACKING TO THE WEST AND SOUTHWEST BY SUNDAY AS A SURFACE TROUGH DEVELOPS OVER WESTERN KANSAS. THE TIGHTENING PRESSURE GRADIENT WILL INCREASE SOUTHWEST WINDS BOOSTING HIGHS TO THE LOW AND MID 40S ON SUNDAY. THE WARMER AIR WILL BE SHORT LIVED HOWEVER AS EXTENDED MODELS ARE BEGINNING TO PHASE TOGETHER ON MONDAY INTO MONDAY EVENING FOR THE NEXT TROUGH TO IMPACT THE CWA. AN OPEN H5 WAVE FROM THE SOUTHWEST LIFTS NORTHEAST INTO NEW MEXICO PHASING WITH A CANADIAN TROUGH DIGGING SOUTHWARD THROUGH THE NORTHERN PLAINS. A COLD FRONT WILL SURGE THROUGH THE AREA MONDAY DROPPING HIGHS BACK INTO THE 30S...POSSIBLY EVEN COLDER BUT HELD OFF LOWERING HIGHS TOO MUCH JUST YET. BOTH THE ECMWF AND GFS CARRY SUFFICIENT GULF MOISTURE NORTHWARD WITH SCATTERED LIGHT RAIN MIXED WITH SNOW...TRANSITIONING TO ALL SNOW BY MONDAY EVENING. UNCERTAINTIES IN SNOWFALL AMOUNT AND THE DISTURBANCE PLACEMENT ITSELF ARE TOO DIFFICULT TO DETERMINE ATTM...HOWEVER RESIDENTS SHOULD MONITOR THIS SYSTEM OVER THE UPCOMING DAYS WITH THE TIMING CURRENTLY ON NEW YEARS EVE. SURFACE HIGH PRESSURE RETURNS THROUGH THE REMAINING PERIOD WITH POSSIBLY A WEAK COLD FRONT AFFECTING THE AREA BY WEDNESDAY. HIGH TEMPERATURES REMAIN BELOW NORMAL IN THE LOW 30S THROUGH THURSDAY. BOWEN && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1153 PM CST TUE DEC 25 2012 .UPDATE... ISSUED AT 1153 PM CST TUE DEC 25 2012 UPDATED AVIATION SECTION FOR 06Z TAF PACKAGE. UPDATE ISSUED AT 920 PM CST TUE DEC 25 2012 ONLY A SLIGHT SOUTHEASTWARD ADJUSTMENT WILL BE MADE TO THE HEAVY SNOW AXIS. IT WILL BE DIFFICULT TO SEE THE ADJUSTMENTS TO THE GENERAL FORECAST PRODUCTS. AT THIS POINT THERE IS NOT MUCH REASON TO KEEP HANGING OUT FOR EACH NEW MODEL RUN TO GET CUTE WITH TOTALS. A SUMMATION OF SOLUTIONS OF THE PAST SEVERAL DAYS IN ESSENCE YIELDS THE BEST AXIS ALONG AND JUST NORTH AND WEST OF THE OHIO UP TOWARD THE WABASH RIVER VALLEY REGION WITH AMOUNTS TAPERING OFF CONSIDERABLY HEADING EAST ACROSS WEST KENTUCKY. WEST KENTUCKY WILL CONTINUE TO BE THE REAL CHALLENGE REGION WHERE AMOUNTS...SOMEWHERE WILL TAPER DOWN CONSIDERABLY. NO CHANGES TO THE BLIZZARD WARNING EITHER. EARLY ONSET PRECIPITATION HAS BEEN A MIX OF RAIN...SLEET AND SNOW. AREAS FROM ALONG THE OHIO NORTH AND WEST INTO SEMO AND SRN IL WILL TRANSITION QUICKLY TO SNOW AS THE UPPER SYSTEM EJECTS NE...AND THE PRECIP SHIELD SEEN OVER ARKANSAS EXPANDS NORTH AND EAST INTO THE REGION. NEEDLESS TO SAY...CONDITIONS WILL DETERIORATE RAPIDLY FROM SW TO NE ACROSS THE REGION FROM 10 PM ON INTO THE OVERNIGHT...MAKING TRAVEL CONDITIONS DANGEROUS...LIFE THREATENING. BLOWING SNOW AND DRIFTS AS WELL WITH THE STRONG AND GUSTY WINDS. ..NOLES.. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... ISSUED AT 318 PM CST TUE DEC 25 2012 IN THE NEAR TERM...AN INTENSIFYING BAND OF MIXED PRECIPITATION IS LIFTING NORTHWARD FROM NORTHERN ARKANSAS AS OF 20Z. THIS BAND IS ASSOCIATED WITH STRONG WARM ADVECTION ON EASTERLY FLOW IN THE 850/700 MB LAYER. RUC MODEL BRINGS THE ZONE OF STRONG MID LEVEL WARM ADVECTION AND ASSOCIATED PRECIP INTO SOUTHEAST MISSOURI BY 00Z. PRECIP TYPE WILL GRADUALLY CHANGE TO SNOW BY MID EVENING IN SE MISSOURI...ONCE THE WARM ADVECTION DIMINISHES AND FRONTOGENETIC FORCING TAKES OVER. INTERESTING TO NOTE THAT RUC MODEL THERMAL PROFILES ARE SOMEWHAT COLDER THAN GFS/NAM PROFILES THIS EVENING. LATER IN THE EVENING...IN THE 03Z TO 06Z TIME FRAME...RUC INDICATES THE MAIN FORCING MECHANISM WILL BECOME MID LEVEL FRONTOGENESIS /850 TO 700 MB LAYER/. THIS WILL RESULT IN LOCALLY HEAVY PRECIPITATION ACQUIRING MORE OF A BANDED CHARACTER AS IT OVERSPREADS THE REMAINDER OF THE FORECAST AREA. LOOKING AT THE 12Z MODEL SUITE...MODELS ARE ALMOST IN LOCKSTEP AS THE EVENT IS NOW WITHIN THE NEXT 24 HOURS. THE PRIMARY ISSUES ARE PRECIPITATION TYPE AND LOCATION OF THE DEFORMATION ZONE /HEAVIEST QPF/. THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500 MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE. ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED. MODEL BOUNDARY LAYER AND 850 MB TEMPS IN THE FAR SOUTHEAST DO NOT SUPPORT MUCH SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH HAS BEEN DISCONTINUED FOR THAT AREA. WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35 KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25 KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE SOME POWER OUTAGES. AS FOR THE TIMING OF THE EVENT...PRECIP WILL SPREAD NORTH ACROSS THE ENTIRE FORECAST AREA THROUGH 06Z. THE HEAVIEST PRECIP WILL OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE BLOWING AND DRIFTING IN THE HEAVY SNOW AREA. .LONG TERM /THURSDAY THROUGH NEXT TUESDAY NIGHT/... ISSUED AT 318 PM CST TUE DEC 25 2012 IN THE EXTENDED FORECAST PERIOD...SHORTWAVE RIDGING ALOFT WILL DOMINATE DURING FROM THURSDAY THROUGH THE EARLY MORNING HOURS ON FRIDAY. ALTHOUGH THERE WILL BE A LITTLE MORE INSOLATION /SUNSHINE/ AVAILABLE...THERE WILL STILL BE WEAK COLD AIR ADVECTION OVER THE EXPECTED SNOW FIELD FROM THE TUESDAY NIGHT/WEDNESDAY MORNING WINTER STORM. WITH THIS IN MIND...LOWERED TEMPERATURES 3 TO 5 DEGREES FROM LIKELY HIGH TEMPERATURES DUE TO CLOUDS...WINDS AND SNOW COVER. THIS ADJUSTMENT WAS MAINLY DONE OVER AREAS WHERE TWO OR MORE INCHES WERE EXPECTED IN THE STORM TOTAL SNOWFALL GRIDDED FORECAST ACROSS THE WFO PAH FORECAST AREA. BY FRIDAY AFTERNOON...BOTH 12Z ECMWF AND GFS DETERMINISTIC MODEL GUIDANCE INDICATE SOME ENHANCEMENT OF THE SHORTWAVE TROUGH MOVING INTO THE WFO PAH FORECAST AREA IN THE SOUTHWESTERLY FLOW BEHIND THE AFOREMENTIONED SHORTWAVE RIDGE. THE LIFT ASSOCIATED WITH THIS FEATURE...COMBINED WITH A RESURGENCE OF CANADIAN POLAR AIR /AS WELL AS ANY ANTECEDENT SNOW COVER/ SHOULD FORCE THE DEVELOPMENT OF LIGHT WINTRY MIX LATE FRIDAY NIGHT. WITH THIS IN MIND...ATTEMPTED TO LIMIT AN MEASURABLE SNOW/SLEET POTENTIAL WHERE THERE WAS NOT A MIX WITH RAIN. AN INITIAL STAB AT SNOW/SLEET AMOUNTS WOULD LEAD TO AMOUNTS LESS THAN ONE INCH OVER SOUTHEAST MO...SOUTHERN IL....SOUTHWEST IN AND WESTERN KY ALONG THE OHIO RIVER. SHOULD THE COLDER AIR FILTER IN FASTER...MAXIMUM AMOUNTS MAY BE CLOSER TO 1.5 INCHES. SINCE THIS WEATHER SYSTEM LOOKS FOCUSED WITH MORE ISENTROPIC LIFT...LEFT THE PRECIPITATION ON THE LIGHTER SIDE IN TERMS OF INTENSITY AND SHORTER IN OVERALL DURATION OF MEASURABLE PRECIPITATION. BEYOND SATURDAY...RIDGING ALOFT WILL BUILD BACK INTO THE AREA WITH SURFACE HIGH PRESSURE AT THE SURFACE. THIS SCENARIO...WITH ANY ANTECEDENT SNOW COVER...WILL LEAD TOWARD SLIGHTLY COOLER TEMPERATURES THAN NORMAL OVER SOUTHERN ILLINOIS AND SOUTHWEST INDIANA THROUGH NEXT TUESDAY. THERE IS SOME DIFFERENCE IN TIMING OF THE NEXT SOUTHWEST LOW MOVING TOWARD THE AREA NEXT TUESDAY/WEDNESDAY...WITH THE ECMWF BEING COOLER AND FASTER AND THE GFS SLOWER AND WARMER. FOR NOW...WILL KEEP THINGS DRY THROUGH THE REMAINDER OF THIS FORECAST PACKAGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1153 PM CST TUE DEC 25 2012 MVFR CIGS WILL DROP TO IFR AND OCCASIONALLY LIFR AS A WINTRY MIX OF PRECIP CONTINUES ACROSS THE TAF SITES. PRECIP WILL BE A SLEET/SNOW MIX CHANGING TO ALL SNOW OVERNIGHT...WITH IFR/LIFR VSBYS ASSOCIATED WITH PRECIP. WINDY CONDITIONS EXPECTED WITH NE WINDS AT 15-25 KTS WITH 35-45 KT GUSTS. CONDITIONS WILL GRADUALLY IMPROVE TO MVFR FROM WEST TO EAST AFTER 14Z. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ075>078-080>089- 092-093. BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ090-091-094. MO...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR MOZ076-086-087-100- 107>112-114. IN...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR INZ081-082-085>088. KY...WINTER WEATHER ADVISORY FROM 6 AM TO NOON CST WEDNESDAY FOR KYZ012-017-021-022. BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR KYZ001>011-013>016- 018>020. && $$ SHORT TERM...MY LONG TERM....SMITH AVIATION...RST
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
112 PM EST WED DEC 26 2012 .SYNOPSIS... A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... UPDATE...WARM FRONT IS CURRENTLY DRAPED OVER CAPE HATTERAS DOWN INTO NW SC EARLY THIS AFTN AND IS SLOW TO LIFT NWD. OVERALL... THE LOCATION OF THE WARM FRONT IS MORE IN-LINE WITH RUC13 MODEL SOLUTIONS. BEST CONVECTION/LIGHTNING HAS BEEN OBSERVED RIGHT ALONG THIS BOUNDARY AND IS EXPECTED TO MOVE UP INTO NE NC AND FAR SE VA BY LATE AFTN/EARLY EVENING. PLACEMENT OF THE WARM FRONT WILL BE CRUCIAL IN DETERMINING GREATEST THUNDERSTORM THREAT THROUGH THE REMAINDER OF THIS AFTN/EARLY EVENING. MODEL SOUNDINGS FOR KECG HINTED AT BRIEF LLVL DRYING DEVELOPING DURING THIS AFTN BEFORE THE ATMOSPHERIC PROFILE BECOMES FULLY SATURATED AGAIN. IF THIS DRYING IS REALIZED...THEN THIS WOULD SUPPORT STRONG AND POTENTIALLY DAMAGING THUNDERSTORM WIND GUSTS IN THE NE NC AND FAR SE VA VICINITIES. THIS PARTICULAR REGION ALSO SITS WITHIN FAVORABLE VEERING WIND SHEAR PROFILES (20-25 KT SE SFC WINDS VEERING TO SW 45-70 KT ALOFT)...WHICH ALSO SUPPORTS ISOLATED TORNADO/WATERSPOUT POTENTIAL AS WELL AS . LATEST RADAR RETURNS/OBSERVATIONS DO SHOW A SMALL AREA OF LITTLE TO NO PRECIP AHEAD OF A MORE ORGANIZED CONVECTIVE LINE OF SHOWERS ASSOCIATED WITH THE SFC COLD FRONT...THUS SUPPORTING THE AFOREMENTIONED ASSESSMENT. WILL THEREFORE CONTINUE ENHANCED WORDING FOR STRONG TO SEVERE THUNDERSTORMS IN FAR SE CWA COUNTIES INTO EARLY THIS EVENING WHERE SPC CONTINUES ITS SLIGHT RISK AREA. PREVIOUS DISCUSSION (702 AM EST)...LATEST WX ANALYSIS DEPICTS A ~995 MB SFC LOW CENTERED ACRS ERN TENNESSEE...AND A ~1032 MB SFC HIGH PRESSURE NORTH OF THE CENTRAL GREAT LAKES. TEMPS ARE STILL ABOVE FREEZING OVER ALL OF THE CWA...EVEN IN THE PIEDMONT...BUT OBS HAVE REPORTED LIGHT SNOW AND/OR SLEET AT LKU/CHO AND NHK. INITIAL BATCH OF STEADIER MODERATE PRECIP IS NOW LIFTING OFF TO THE NE OF RICHMOND...WITH LIGHTER MORE SPOTTY PRECIP ALLOWING FOR RAIN TO MIX BACK IN AT LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT CONDITIONS...BUT LITTLE CHANGE IN OVERALL THINKING FOR TODAY...AS PRECIP RATES INCREASE THERE IS STILL THE POTENTIAL FOR MIXED SNOW/SLEET OVER FAR NORTHERN TIER OF CWA THROUGH 15Z...BECOMING CONFINED TO WRN LOUISA/FLUVANNA 15Z-17Z AND THEN SHOULD BE ALL RAIN THEREAFTER. LITTLE TO NO ACCUMULATION (IF THERE IS ANY ACCUMULATION IT SHOULD BE LIGHT AND LIMITED TO GRASSY SURFACES OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH FOR AN ADSY). THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH (LIGHTNING STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER... BUT WITH NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE EXTENDED CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER NORTH TO INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM BULK SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND THIS SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS EVEN WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6 PM WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED FCST FOR FAR SE VA/NE NC. OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS AFTN/EVENING. PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25 TO 1.75 INCHES (WHERE HIGHER AMTS WILL BE LOCATED ALONG THE IMMEDIATE COAST). SOME AREAS COULD SEE LOCALLY HIGHER AMTS. HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND POSSIBLY INTO THE UPPER 60S IN NE NC. && .SHORT TERM /10 PM THIS EVENING THROUGH FRIDAY/... STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO THE UPPER 40S TO AROUND 50. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP... ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE. STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES... BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS VERIFY. TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... IFR AND OCCASIONAL LIFR CONDITIONS PREVAIL ALL TERMINALS AT 18Z. IFR WILL DOMINATE THROUGH 21Z-22Z AT KRIC...WITH CONDITIONS GRADUALLY IMPROVING FROM WEST TO EAST ACROSS THE REGION AS INTENSE DRY SLOT MOVES THROUGH. THIS WILL ALLOW PRECIP TO SIGNIFICANTLY DIMINISH OR END COMPLETELY. AND...AS WINDS GRADUALLY SHIFT TO THE SW...DRIER AIR WILL MOVE IN AND CONDITIONS SHOULD IMPROVE TO MVFR BY 00Z AT KRIC...02Z-03Z AT KPHF/KECG/KORF AND BEFORE 06Z AT KSBY. STILL THE POSSIBILITY OF AN ISOLATED TSTM AT KORF/ECG...BUT POTENTIAL APPEARS TO HAVE DIMINISHED SOME OVER THE LAST FEW HOURS. HAVE MAINTAINED VCTS BOTH TERMINALS. CONDITIONS WILL CONTINUE TO IMPROVE OVERNIGHT...WITH VFR PREVAILING THURSDAY AND FRIDAY. HOWEVER...WINDS WILL REMAIN GUSTY THURSDAY OUT OF THE W/NW...WITH A FEW GUSTS APPROACHING 30 KT...ESPECIALLY AT KSBY. WINDS WILL SUBSIDE ON FRIDAY...WITH NEXT POTENTIAL FOR MVFR/IFR CONDITIONS ON SATURDAY WITH AN APPROACHING COLD FRONT. && .MARINE... ...AS OF 1 PM...GLW ISSUED FOR CHESAPEAKE BAY...AS OBSERVATIONS AND HI RES MODELS SUGGEST A 4-6 HOUR PERIOD OF GALES IN ASSOCIATION WITH LARGEST PRESSURE FALLS AHEAD OF SFC LOW. WINDS SHOULD DROP BACK TO SCA LEVELS BEFORE 00Z...WITH GUSTS AROUND 30 KT STILL A GOOD BET ON THE BAY. REMAINDER OF FORECAST IN GOOD SHAPE. .PREV DISCUSSION... EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON. STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS. WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON. BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN COASTAL WATERS AGAIN THURSDAY. A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT FRONT AND DEEPENING SFC LOW CROSS REGION. && .TIDES/COASTAL FLOODING... FORECAST TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL AT OCEAN CITY...BISHOPS HEAD AND CAMBRIDGE TONIGHT INTO THURS MORNING TIMEFRAME. STILL THE POSSIBILITY OF LOW END MINOR TIDAL FLOODING ON THE LOWER MD ESATERN SHORE AREAS ADJACENT TO THE BAY WITH THE HIGH TIDE TONIGHT. HOWEVER...CONFIDENCE STILL NOT HIGH...SO NO ADVY ISSUED ATTM. WILL CONTINUE TO EVALUATE FOR LATE AFTERNOON FORECAST ISSUANCE. IT APPEARS THAT OCEAN CITY WILL REMAIN BELOW MINOR FLOOD LEVELS SO NO ADVY ANTICIPATED THERE. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ633- 635>638. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 PM EST THURSDAY FOR ANZ630>632-634-656-658. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ630>632-634- 656-658. GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ650-652-654. && $$ SYNOPSIS...BMD/MAM NEAR TERM...BMD/LKB SHORT TERM...BMD/LKB LONG TERM...JAB AVIATION...WRS MARINE...JDM/SAM/WRS TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1205 PM EST WED DEC 26 2012 .SYNOPSIS... A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... UPDATE...WARM FRONT IS CURRENTLY DRAPED OVER CAPE HATTERAS DOWN INTO NW SC EARLY THIS AFTN AND IS SLOW TO LIFT NWD. OVERALL... THE LOCATION OF THE WARM FRONT IS MORE IN-LINE WITH RUC13 MODEL SOLUTIONS. BEST CONVECTION/LIGHTNING HAS BEEN OBSERVED RIGHT ALONG THIS BOUNDARY AND IS EXPECTED TO MOVE UP INTO NE NC AND FAR SE VA BY LATE AFTN/EARLY EVENING. PLACEMENT OF THE WARM FRONT WILL BE CRUCIAL IN DETERMINING GREATEST THUNDERSTORM THREAT THROUGH THE REMAINDER OF THIS AFTN/EARLY EVENING. MODEL SOUNDINGS FOR KECG HINTED AT BRIEF LLVL DRYING DEVELOPING DURING THIS AFTN BEFORE THE ATMOSPHERIC PROFILE BECOMES FULLY SATURATED AGAIN. IF THIS DRYING IS REALIZED...THEN THIS WOULD SUPPORT STRONG AND POTENTIALLY DAMAGING THUNDERSTORM WIND GUSTS IN THE NE NC AND FAR SE VA VICINITIES. THIS PARTICULAR REGION ALSO SITS WITHIN FAVORABLE VEERING WIND SHEAR PROFILES (20-25 KT SE SFC WINDS VEERING TO SW 45-70 KT ALOFT)...WHICH ALSO SUPPORTS ISOLATED TORNADO/WATERSPOUT POTENTIAL AS WELL AS . LATEST RADAR RETURNS/OBSERVATIONS DO SHOW A SMALL AREA OF LITTLE TO NO PRECIP AHEAD OF A MORE ORGANIZED CONVECTIVE LINE OF SHOWERS ASSOCIATED WITH THE SFC COLD FRONT...THUS SUPPORTING THE AFOREMENTIONED ASSESSMENT. WILL THEREFORE CONTINUE ENHANCED WORDING FOR STRONG TO SEVERE THUNDERSTORMS IN FAR SE CWA COUNTIES INTO EARLY THIS EVENING WHERE SPC CONTINUES ITS SLIGHT RISK AREA. PREVIOUS DISCUSSION (702 AM EST)...LATEST WX ANALYSIS DEPICTS A ~995 MB SFC LOW CENTERED ACRS ERN TENNESSEE...AND A ~1032 MB SFC HIGH PRESSURE NORTH OF THE CENTRAL GREAT LAKES. TEMPS ARE STILL ABOVE FREEZING OVER ALL OF THE CWA...EVEN IN THE PIEDMONT...BUT OBS HAVE REPORTED LIGHT SNOW AND/OR SLEET AT LKU/CHO AND NHK. INITIAL BATCH OF STEADIER MODERATE PRECIP IS NOW LIFTING OFF TO THE NE OF RICHMOND...WITH LIGHTER MORE SPOTTY PRECIP ALLOWING FOR RAIN TO MIX BACK IN AT LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT CONDITIONS...BUT LITTLE CHANGE IN OVERALL THINKING FOR TODAY...AS PRECIP RATES INCREASE THERE IS STILL THE POTENTIAL FOR MIXED SNOW/SLEET OVER FAR NORTHERN TIER OF CWA THROUGH 15Z...BECOMING CONFINED TO WRN LOUISA/FLUVANNA 15Z-17Z AND THEN SHOULD BE ALL RAIN THEREAFTER. LITTLE TO NO ACCUMULATION (IF THERE IS ANY ACCUMULATION IT SHOULD BE LIGHT AND LIMITED TO GRASSY SURFACES OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH FOR AN ADSY). THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH (LIGHTNING STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER... BUT WITH NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE EXTENDED CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER NORTH TO INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM BULK SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND THIS SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS EVEN WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6 PM WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED FCST FOR FAR SE VA/NE NC. OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS AFTN/EVENING. PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25 TO 1.75 INCHES (WHERE HIGHER AMTS WILL BE LOCATED ALONG THE IMMEDIATE COAST). SOME AREAS COULD SEE LOCALLY HIGHER AMTS. HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND POSSIBLY INTO THE UPPER 60S IN NE NC. && .SHORT TERM /10 PM THIS EVENING THROUGH FRIDAY/... STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO THE UPPER 40S TO AROUND 50. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP... ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE. STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES... BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS VERIFY. TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... STRONG SFC LOW PRESSURE WILL CONTINUE TO LIFT OUT OF THE DEEP SOUTH EARLY THIS MORNING AS HIGH PRESSURE REMAINS WEDGED OVER THE MID ATLANTIC. CURRENTLY...BKN/OVC SKIES WITH DECKS GENERALLY 3 TO 6K FT AGL WILL CONTINUE TO LOWER THROUGH 12Z UNDER NELY FLOW ALOFT. THE EXCEPTION WILL BE IN SE VA/NE NC WHERE NELY FLOW WILL RESULT IN LOCALIZED IFR CIGS THROUGH EARLY MORNING. OVERRUNNING WILL SPREAD LIGHT/MODERATE RAIN NEWD THIS MORNING ACROSS THE REGION. IN ADDITION...AN INCREASING LOW LEVEL JET MAY ENHANCE SOME WIND SHEER THIS MORNING AT KRIC AND KSBY. WILL LEAVE OUT OF TAFS AS TIMING WILL BE DIFFICULT AND CONFIDENCE IS LOW...SO WILL MONITOR AND AMEND IF NEEDED. WINDS THROUGH 12Z WILL BE NELY AT 5 TO 15 KT WITH GUSTS NEAR THE COAST UP TO 20 KT. EXPECT TO SEE THE CLOUDS GRADUALLY LOWER WITH THE LOW LEVELS BECOMING SATURATED BETWEEN 12Z AND 15Z. THIS WILL YIELD WIDESPREAD MVFR CONDITIONS DEVELOPING AND AS THE ISENTROPIC LIFT INCREASES. CIGS AND VSBYS DROP TO IFR LEVELS WITH THE INCREASING RAIN THREAT. THE CHALLENGE COMES DOWN TO THE STRENGTH OF THE WEDGE...WHICH THE MODELS TRY TO ERODE QUICKLY WITH THE SFC LOW FORMING OVER THE PIEDMONT AND LIFTING NE. BUT EXPECT THAT THE WEDGE WILL BE STRONG WITH THE LOW FORMING JUST EAST OF I-95. THIS WILL ALLOW THE WINDS TO SWITCH TO SE OR E FOR ORF/ECG/SBY AND MAYBE AT PHF...BUT ANTICIPATE THAT RIC WILL REMAIN CLOSER TO THE WEDGE SO DO NOT SHOW A GREAT DEAL OF IMPROVEMENT LATE IN THE PERIOD...KEEPING THE IFR CONDITIONS THROUGH THE TAF. THE OTHER SITES SHOULD BREAK INTO THE WARM SECTOR WHICH SHOULD BRING THE CEILINGS AND VSBY BACK TO MVFR OR EVEN VFR CONDITIONS AHEAD OF THE COLD FRONT...WHICH SHOULD CROSS BETWEEN 00Z AND 3Z. WINDS WILL BE STRONGEST NEAR THE COAST WITH GUSTS UP TO 25-30 KT THIS AFTERNOON. THERE COULD STILL BE A CHANCE FOR A TSTM AS THE COLD FRONT PUSHES THROUGH ON WEDNESDAY EVENING WITH BEST CHC AT ORF AND ECG. CONDITIONS WILL IMPROVE BACK TO VFR BY THURSDAY AND CONTINUE VFR ON FRIDAY. NEXT LOW APPROACHES FOR THE WEEKEND AND THIS COULD AGAIN GENERATE MORE MVFR AND IFR CEILINGS. && .MARINE... EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON. .PREV DISCUSSION... STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS. WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON. BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN COASTAL WATERS AGAIN THURSDAY. A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT FRONT AND DEEPENING SFC LOW CROSS REGION. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL AT OCEAN CITY...BISHOPS HEAD AND CAMBRIDGE THIS AFTERNOON TO THURS MORNING TIMEFRAME. THIS AFTERNOON/EVENINGS CYCLE IS THE LOWER OF THE 2 HIGH TIDES...SO TIDES WILL FALL BELOW ADVISORY CRITERIA TODAY. TIDES ALSO EXPECTED TO FALL BELOW ADVISORY CRITERIA AGAIN TONIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ630>638- 656-658. GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ650-652-654. && $$ SYNOPSIS...BMD/MAM NEAR TERM...BMD/LKB SHORT TERM...BMD/LKB LONG TERM...JAB AVIATION...SAM MARINE...SAM TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
702 AM EST WED DEC 26 2012 .SYNOPSIS... A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATEST WX ANALYSIS DEPICTS A ~995 MB SFC LOW CENTERED ACRS ERN TENNESSEE...AND A ~1032 MB SFC HIGH PRESSURE NORTH OF THE CENTRAL GREAT LAKES. TEMPS ARE STILL ABOVE FREEZING OVER ALL OF THE CWA...EVEN IN THE PIEDMONT...BUT OBS HAVE REPORTED LIGHT SNOW AND/OR SLEET AT LKU/CHO AND NHK. INITIAL BATCH OF STEADIER MODERATE PRECIP IS NOW LIFTING OFF TO THE NE OF RICHMOND...WITH LIGHTER MORE SPOTTY PRECIP ALLOWING FOR RAIN TO MIX BACK IN AT LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT CONDITIONS...BUT LITTLE CHANGE IN OVERALL THINKING FOR TODAY...AS PRECIP RATES INCREASE THERE IS STILL THE POTENTIAL FOR MIXED SNOW/SLEET OVER FAR NORTHERN TIER OF CWA THROUGH 15Z...BECOMING CONFINED TO WRN LOUISA/FLUVANNA 15Z-17Z AND THEN SHOULD BE ALL RAIN THEREAFTER. LITTLE TO NO ACCUMULATION (IF THERE IS ANY ACCUMULATION IT SHOULD BE LIGHT AND LIMITED TO GRASSY SURFACES OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH FOR AN ADSY). THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH (LIGHTNING STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER...BUT WITH NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE EXTENDED CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER NORTH TO INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM BULK SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND THIS SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS EVEN WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6 PM WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED FCST FOR FAR SE VA/NE NC. OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS AFTN/EVENING. PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25 TO 1.75 INCHES (WHERE HIGHER AMTS WILL BE LOCATED ALONG THE IMMEDIATE COAST). SOME AREAS COULD SEE LOCALLY HIGHER AMTS. HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND POSSIBLY INTO THE UPPER 60S IN NE NC. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO THE UPPER 40S TO AROUND 50. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP... ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE. STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES... BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS VERIFY. TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... STRONG SFC LOW PRESSURE WILL CONTINUE TO LIFT OUT OF THE DEEP SOUTH EARLY THIS MORNING AS HIGH PRESSURE REMAINS WEDGED OVER THE MID ATLANTIC. CURRENTLY...BKN/OVC SKIES WITH DECKS GENERALLY 3 TO 6K FT AGL WILL CONTINUE TO LOWER THROUGH 12Z UNDER NELY FLOW ALOFT. THE EXCEPTION WILL BE IN SE VA/NE NC WHERE NELY FLOW WILL RESULT IN LOCALIZED IFR CIGS THROUGH EARLY MORNING. OVERRUNNING WILL SPREAD LIGHT/MODERATE RAIN NEWD THIS MORNING ACROSS THE REGION. IN ADDITION...AN INCREASING LOW LEVEL JET MAY ENHANCE SOME WIND SHEER THIS MORNING AT KRIC AND KSBY. WILL LEAVE OUT OF TAFS AS TIMING WILL BE DIFFICULT AND CONFIDENCE IS LOW...SO WILL MONITOR AND AMEND IF NEEDED. WINDS THROUGH 12Z WILL BE NELY AT 5 TO 15 KT WITH GUSTS NEAR THE COAST UP TO 20 KT. EXPECT TO SEE THE CLOUDS GRADUALLY LOWER WITH THE LOW LEVELS BECOMING SATURATED BETWEEN 12Z AND 15Z. THIS WILL YIELD WIDESPREAD MVFR CONDITIONS DEVELOPING AND AS THE ISENTROPIC LIFT INCREASES. CIGS AND VSBYS DROP TO IFR LEVELS WITH THE INCREASING RAIN THREAT. THE CHALLENGE COMES DOWN TO THE STRENGTH OF THE WEDGE...WHICH THE MODELS TRY TO ERODE QUICKLY WITH THE SFC LOW FORMING OVER THE PIEDMONT AND LIFTING NE. BUT EXPECT THAT THE WEDGE WILL BE STRONG WITH THE LOW FORMING JUST EAST OF I-95. THIS WILL ALLOW THE WINDS TO SWITCH TO SE OR E FOR ORF/ECG/SBY AND MAYBE AT PHF...BUT ANTICIPATE THAT RIC WILL REMAIN CLOSER TO THE WEDGE SO DO NOT SHOW A GREAT DEAL OF IMPROVEMENT LATE IN THE PERIOD...KEEPING THE IFR CONDITIONS THROUGH THE TAF. THE OTHER SITES SHOULD BREAK INTO THE WARM SECTOR WHICH SHOULD BRING THE CEILINGS AND VSBY BACK TO MVFR OR EVEN VFR CONDITIONS AHEAD OF THE COLD FRONT...WHICH SHOULD CROSS BETWEEN 00Z AND 3Z. WINDS WILL BE STRONGEST NEAR THE COAST WITH GUSTS UP TO 25-30 KT THIS AFTERNOON. THERE COULD STILL BE A CHANCE FOR A TSTM AS THE COLD FRONT PUSHES THROUGH ON WEDNESDAY EVENING WITH BEST CHC AT ORF AND ECG. CONDITIONS WILL IMPROVE BACK TO VFR BY THURSDAY AND CONTINUE VFR ON FRIDAY. NEXT LOW APPROACHES FOR THE WEEKEND AND THIS COULD AGAIN GENERATE MORE MVFR AND IFR CEILINGS. && .MARINE... EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON. .PREV DISCUSSION... STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS. WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON. BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN COASTAL WATERS AGAIN THURSDAY. A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT FRONT AND DEEPENING SFC LOW CROSS REGION. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL AT OCEAN CITY...BISHOPS HEAD AND CAMBRIDGE THIS AFTERNOON TO THURS MORNING TIMEFRAME. THIS AFTERNOON/EVENINGS CYCLE IS THE LOWER OF THE 2 HIGH TIDES...SO TIDES WILL FALL BELOW ADVISORY CRITERIA TODAY. TIDES ALSO EXPECTED TO FALL BELOW ADVISORY CRITERIA AGAIN TONIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ630>638- 656-658. GALE WARNING FROM 10 AM THIS MORNING TO 9 PM EST THIS EVENING FOR ANZ650-652-654. && $$ SYNOPSIS...MAM NEAR TERM...LKB SHORT TERM...BMD/LKB LONG TERM...JAB AVIATION...SAM MARINE...SAM TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1140 AM CST WED DEC 26 2012 .UPDATE... ISSUED AT 809 AM CST WED DEC 26 2012 HAVE CANCELLED REMAINING ADVISORIES AND WARNINGS. BACK EDGE OF THE ACCUMULATING SNOW IS CURRENTLY EXITING THE AREA. ISSUED AT 553 AM CST WED DEC 26 2012 UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE IF ANY. BRITT && .SHORT TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TODAY) MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND SPEEDS CONTINUE TO INCREASE. LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS 1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY. IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND 650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES TO THE EAST. BRITT && .LONG TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TONIGHT THROUGH TUESDAY) TONIGHT AND THURSDAY...CONFIDENCE HIGH RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER OVER AREAS OF FRESH SNOW COVER. THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS. GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION. WEEKEND...CONFIDENCE MEDIUM SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE. NEXT WEEK...CONFIDENCE LOW MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT TEMPERATURES NEAR NORMAL VALUES. CVKING && .AVIATION... ISSUED AT 1125 AM CST WED DEC 26 2012 SURFACE LOW NOW OVER EASTERN KENTUCKY WILL CONTINUE MOVING AWAY...ALLOWING SURFACE HIGH PRESSURE TO BUILD IN FROM THE WEST. CIGS NEAR AOA 3K FT SHOULD PERSIST OVER EASTERN MO INTO IL THROUGH AROUND 06Z...THEN BEGIN TO CLEAR. WHILE A LARGE AREA OF CLEAR SKIES EXISTS OVER CENTRAL MO AS EVIDENT IN THE SATELLITE LOOP...CLOUDS BUILDING SOUTHWARD AGAIN SHOULD BRING CIGS AOA 3K FT BY EARLY AFTERNOON THERE. WINDS BECOME LIGHT AND VARIABE AREAWIDE BY LATE EVENING...SO THERE MAY BE SOME PATCHY FOG. SPECIFICS FOR KSTL...CIGS AOA 3K FT SOULD PERSIST UNTIL AT LEAST 06Z...THEN GRADUALLY CLEAR. GUSTY NW WINDS WILL ALSO DIMINISH BY AROUND 06Z...THEN BECOME SOUTHEAST BY AROUND 20Z THURSDAY AS SURFACE HIGH PRESSURE MOVES TO THE EAST. BROWNING && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
810 AM CST WED DEC 26 2012 .UPDATE... ISSUED AT 809 AM CST WED DEC 26 2012 HAVE CANCELLED REMAINING ADVISORIES AND WARNINGS. BACK EDGE OF THE ACCUMULATING SNOW IS CURRENTLY EXITING THE AREA. ISSUED AT 553 AM CST WED DEC 26 2012 UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE IF ANY. BRITT && .SHORT TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TODAY) MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND SPEEDS CONTINUE TO INCREASE. LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS 1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY. IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND 650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES TO THE EAST. BRITT && .LONG TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TONIGHT THROUGH TUESDAY) TONIGHT AND THURSDAY...CONFIDENCE HIGH RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER OVER AREAS OF FRESH SNOW COVER. THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS. GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION. WEEKEND...CONFIDENCE MEDIUM SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE. NEXT WEEK...CONFIDENCE LOW MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT TEMPERATURES NEAR NORMAL VALUES. CVKING && .AVIATION... ISSUED AT 514 AM CST WED DEC 26 2012 BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST- WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON. SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK TO THE NORTHWEST THIS MORNING. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
556 AM CST WED DEC 26 2012 .UPDATE... ISSUED AT 553 AM CST WED DEC 26 2012 UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE IF ANY. BRITT && .SHORT TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TODAY) MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND SPEEDS CONTINUE TO INCREASE. LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS 1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY. IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND 650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES TO THE EAST. BRITT && .LONG TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TONIGHT THROUGH TUESDAY) TONIGHT AND THURSDAY...CONFIDENCE HIGH RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER OVER AREAS OF FRESH SNOW COVER. THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS. GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION. WEEKEND...CONFIDENCE MEDIUM SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE. NEXT WEEK...CONFIDENCE LOW MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT TEMPERATURES NEAR NORMAL VALUES. CVKING && .AVIATION... ISSUED AT 514 AM CST WED DEC 26 2012 BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST- WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON. SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK TO THE NORTHWEST THIS MORNING. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING UNTIL 6 AM CST EARLY THIS MORNING FOR MADISON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO. WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR IRON MO-REYNOLDS MO-WASHINGTON MO. IL...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR BOND IL-CLINTON IL-FAYETTE IL. WINTER STORM WARNING UNTIL NOON CST TODAY FOR MARION IL-RANDOLPH IL-WASHINGTON IL. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
514 AM CST WED DEC 26 2012 .SHORT TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TODAY) MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND SPEEDS CONTINUE TO INCREASE. LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS 1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY. IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND 650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES TO THE EAST. BRITT && .LONG TERM... ISSUED AT 300 AM CST WED DEC 26 2012 (TONIGHT THROUGH TUESDAY) TONIGHT AND THURSDAY...CONFIDENCE HIGH RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER OVER AREAS OF FRESH SNOW COVER. THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS. GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION. WEEKEND...CONFIDENCE MEDIUM SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE. NEXT WEEK...CONFIDENCE LOW MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT TEMPERATURES NEAR NORMAL VALUES. CVKING && .AVIATION... ISSUED AT 514 AM CST WED DEC 26 2012 BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST- WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON. SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK TO THE NORTHWEST THIS MORNING. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING UNTIL 6 AM CST EARLY THIS MORNING FOR MADISON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO. WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR IRON MO-REYNOLDS MO-WASHINGTON MO. IL...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR BOND IL-CLINTON IL-FAYETTE IL-MONROE IL-ST. CLAIR IL. WINTER STORM WARNING UNTIL NOON CST TODAY FOR MARION IL-RANDOLPH IL-WASHINGTON IL. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1213 AM CST WED DEC 26 2012 .UPDATE... ISSUED AT 838 PM CST TUE DEC 25 2012 00Z NAM IS IN AND IT`S NOT LOOKING TOO GOOD FOR ACCUMULATING SNOW MUCH NORTH OF OUR CURRENT WARNING. THE GRADIENT WE HAVE IN OUR SNOWFALL FORECAST STILL LOOKS LIKE IT`S IN JUST ABOUT THE RIGHT PLACE...BUT AMOUNTS ARE LOOKING A BIT TOO HIGH IF YOU TAKE THE QPF VERBATIM. SINCE THE NAM IS THE ONLY NEW PIECE OF 00Z GUIDANCE WE`VE GOT AT THIS TIME (ASIDE FROM THE RUC)...I`M NOT FEELING PARTICULARLY BRAVE ABOUT CUTTING SNOWFALL AMOUNTS. THIS IS ESPECIALLY TRUE SINCE THE RUC REALLY RAMPS UP VERTICAL MOTION JUST SOUTH OF THE STL METRO OVER THE NEXT 2-4 HOURS. THIS MAY BE IN RESPONSE TO A BACK-BUILDING JET STREAK OVER THE GREAT LAKES. THE NAM SHOWS THIS TOO...BUT TO A LESSER EXTENT AND THE QPF LOOKS TO BE MORE DRIVEN BY ISENTROPIC LIFT AND FRONTOGENESIS FURTHER SOUTH ACROSS SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS. FOR NOW...WILL LET CURRENT HEADLINES/SNOW AMOUNTS RIDE. CARNEY && .SHORT TERM... ISSUED AT 335 PM CST TUE DEC 25 2012 (TONIGHT AND WEDNESDAY) THE LATEST WATER VAPOR IMAGERY AND WIND PROFILERS/VWPS SHOW THE UPPER LOW IS NOW LOCATED IN NW TX INVOF OF KTYR. THE STRONGEST WINDS APPEAR TO BE ENTERING THE BASE OF THE TROF. THIS WOULD SUGGEST THERE WILL BE CONTINUED EASTWARD MOTION INTO THE EVENING. THE MODELS ARE REASONABLY WELL CLUSTED WITH THE H5 AND H85 LOW CENTERS AND SEEM TO BE DOING A GOOD JOB. THE UPPER LOW SHOULD BOTTOM OUT INVOF OF THE AR/LA BORDER BETWEEN 00-03Z AND THEN TAKE ITS NEWD TURN EJECTING INTO THE WRN TN VALLEY OVERNIGHT AND INTO THE OH VALLEY ON WEDNESDAY. DESPITE THE GOOD AGREEMENT IN THE MASS FIELDS...THERE CONTINUE TO BE VARIANCES IN THE MODEL QPFS...ESPECIALLY THE NRN EXTENT. THE NEW FORECAST IS BASICALLY A MULTI-MODEL BLEND ON THE NRN FRINGE INCLUDING THE LATEST RUC. SNOW IS GRADUALLY SPREADING NWD ACROSS AR ATTM AND WILL BE ENCOUNTERING RELATIVELY DRIER NELY FLOW. THIS MAY INITIALLY SLOW THE PROGRESSES BUT AS THE LOW MOVES INTO THE LOWER MS VALLEY THIS EVENING AND THEN MAKES ITS NEWD TURN...THE LARGE SCALE ASCENT WILL OVERSPREAD SE MO AND SRN IL MID-LATE EVENING AND SPREAD NEWD INTO SW IL OVERNIGHT. FOLLOWING GOREE/YOUNKIN TECHNIQUES AND A MORE RECENT HEAVY SNOW SYNOPTIC CLIMO BY GOSSELIN...THE HEAVIEST SNOW BAND SHOULD BE SOUTH OF THE CWA ACROSS FAR SE MO AND SRN IL. THE HEAVIEST SNOW WITHIN THE CWA STILL LOOKS LIKE IT WILL BE ON THE SE FRINGE...WHERE THERE WILL ROUGHLY BE A PERIOD OF 6-8 HOURS OF SNOW...MODERATE TO HEAVY AT TIMES. THE HIGHEST AMOUNTS WILL BE SOUTH OF A LINE FROM CENTERVILLE TO FARMINGTON TO SPARTA TO SALEM IN THE 5-6 INCH RANGE. I HAVE UPGRADED THE ADVISORY TO A WINTER STORM WARNING GIVEN THESE SNOWFALL AMOUNTS AND THE STRONG AND GUSTY NORTH/NORTHWEST WINDS OF 25-35 MPH PRODUCING BLOWING AND DRIFTING SNOW. AN ADVISORY WILL ROUGHLY SPAN THE NRN FRINGE OF THE WARNING. ST LOUIS WILL BE IN THE GRADIENT OF MEASURABLE SNOWFALL AND THE WESTERN SUBURBS MAY SEE LITTLE TO NOTHING...WITH AMOUNTS OF 1-2 INCHES IN THE SE IL SUBURBS. THE EVENT SHOULD WIND DOWN BY MID-LATE MORNING ACROSS SW/SC IL. HOPEFULLY THERE WILL BE NO SURPRISES TONIGHT. GLASS && .LONG TERM... ISSUED AT 314 PM CST TUE DEC 25 2012 (THURSDAY THROUGH TUESDAY) THERE STILL LOOKS TO BE A CHANCE OF SNOW MAINLY FRIDAY NIGHT ALTHOUGH THE PROBABILITY LOOKS LESS THAN ADVERTISED 2 DAYS AGO. OVERALL THE PATTERN LOOKS SEASONABLY COLD. GLASS && .AVIATION... ISSUED AT 1210 AM CST WED DEC 26 2012 NO CHANGE WITH THE LATEST GUIDANCE WITH NWRN EDGE OF ACCUMULATING SNOWFALL SETTING UP JUST TO THE SW OF STL METRO AREA...WITH WHAT IS EXPECTED TO BE A FAIRLY WIDESPREAD AREA OF LIGHT FLURRIES OVER THE STL METRO AREA FOR OVERNIGHT. STILL FAVOR A MORE PESSIMISTIC TAF FOR KCPS WITH IFR VSBYS...BUT BELIEVE NOW THAT PERSISTENT LIFT OVER THE STL METRO AREA SHOULD RESULT IN 2-3HRS OF IFR CIGS AS WELL. ELSEWHERE TO THE NW OF THE STL METRO AREA...LOOK FOR VFR CIGS LOWERING TO MVFR OVERNIGHT THANKS TO AFOREMENTIONED LIFT. STRONG AND GUSTY N SFC WNDS WILL PERSIST THRU OVERNIGHT. SPECIFICS FOR KSTL...EXPECT JUST FLURRIES OVERNIGHT BUT MAY GET SOMETHING A BIT HEAVIER FOR AN HOUR OR TWO OVERNIGHT BEFORE EVERYTHING WINDS DOWN AROUND SUNRISE. SHOULD EVEN SEE A BRIEF PERIOD OF IFR CIGS THANKS TO PERSISTENT AND DEEPENING LIFT OVERHEAD WHICH HAS CAUSED CIGS TO LOWER THRU THE EVENING. ONCE THE SYSTEM PULLS AWAY LATER ON WEDNESDAY MORNING...LOOK FOR PERSISTENT MVFR CIGS FOR MUCH OF THE REST OF THE PERIOD WITH SFC WNDS GUSTING TO 25KTS OR SO...DIMINISHING TO LESS THAN 10KTS WEDNESDAY NIGHT. SOME QUESTION ON HOW WELL CIGS WILL BE ABLE TO HANG IN THERE WEDNESDAY NIGHT BUT FOR NOW...IN THE ABSENCE OF STRONG EVIDENCE... WENT WITH A PERSISTENCE FCST FOR NOW. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR MADISON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO. WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR IRON MO- REYNOLDS MO-WASHINGTON MO. IL...WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR BOND IL- CLINTON IL-FAYETTE IL-MONROE IL-ST. CLAIR IL. WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR MARION IL- RANDOLPH IL-WASHINGTON IL. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
638 AM MST WED DEC 26 2012 .SHORT TERM...VALID FOR TDY AND THU... UPDATED FORECAST TO EXTEND MORNING POPS FURTHER EAST AND INCREASE TO LIKELY OVER HIGHER ELEVATIONS WEST THIS MORNING. SHORTWAVE AND SOME MID LEVEL WARM ADVECTION MOVING ACROSS WESTERN AND CENTRAL MONTANA THIS MORNING ARE PRODUCING MORE PRECIPITATION THAN EXPECTED. SNOW HAS DEVELOPED AS FAR NORTH AND EAST AS GREAT FALLS THIS MORNING...AN AREA MODELS HAVE NOT BEEN ADVERTISING ANY PRECIPITATION. 06Z NAM AND LATES RAP HAVE SHOWN INCREASED LIFT AND MOISTURE ADVECTION FROM BIG HORN AND TREASURE COUNTY WEST. ALSO NOTING MORE COOLING CLOUD TOPS OVER NORTHERN WYOMING SHIFTING INTO SOUTH CENTRAL MONTANA THAN WAS EXPECTING HINTING THAT UPSTREAM SYSTEM MAY BE MOVING FASTER AND MAY BE STRONGER THAN 00Z MODELS WERE FORECASTING. AS A RESULT INCREASED AND SPREAD POPS FURTHER EAST THIS MORNING...AND INCREASED AFTERNOON POPS 10 TO 20 PERCENT OVER CENTRAL AND EASTERN ZONES ANTICIPATING A FASTER ARRIVAL OF SYSTEM INTO WYOMING THAT IS CURRENTLY IN UTAH. ANY SNOW THIS MORNING INTO EARLY AFTERNOON WILL BE VERY LIGHT. CHAMBERS .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... CONFIDENCE IN THE EXTENDED FORECAST REMAINS AVERAGE THROUGH THE WEEKEND...WITH CONFIDENCE DECREASING FOR EARLY NEXT WEEK. FRIDAY WILL BRING UPPER-LEVEL NORTHWESTERLY FLOW ACROSS THE FORECAST AREA IN THE WAKE OF A PACIFIC TROUGH. THIS PATTERN WILL ALLOW A SURFACE HIGH PRESSURE TO BUILD SOUTH AND WEST OF THE AREA WITH SURFACE PRESSURE FALLS ALONG THE FRONT RANGE. THIS WILL ALLOW FOR WESTERLY DOWNSLOPE FLOW TO INCREASE DURING THE DAY ON FRIDAY. THE MAGNITUDE OF WARMING DUE TO THE DOWNSLOPE FLOW WILL BE INHIBITED ON FRIDAY DUE TO LINGERING SNOW COVER ACROSS THE AREA AND A COLD AIR MASS IN PLACE WEST OF THE ROCKIES. EXPECT DRY CONDITIONS ACROSS THE FORECAST AREA ON FRIDAY THANKS TO RIDGING TO THE WEST AND THE DOWNSLOPE FLOW. THE WEST TO EAST ORIENTED SURFACE PRESSURE GRADIENT WILL INCREASE ACROSS WESTERN ZONES OF THE FORECAST AREA FRIDAY NIGHT INTO SATURDAY. THIS WILL BRING GUSTY WINDS FROM BILLINGS WEST AND ENHANCED DOWNSLOPE FLOW. EXPECT TEMPERATURES TO CONTINUE TO RECOVER ON SATURDAY THANKS TO THIS FLOW...BUT THE KLONDIKE NATURE OF THE CHINOOK AND THE EXPECTED CONTINUED SNOW COVER WILL KEEP HIGH TEMPERATURES REACHING ONLY AROUND FREEZING ACROSS THE WESTERN ZONES. A SHORTWAVE TROUGH IN THE NORTHWESTERLY FLOW WILL APPROACH THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY. THIS WILL PUSH A SURFACE LOW OFF THE FRONT RANGE AND BRING A COLD FRONT IN FROM THE NORTH AS A CANADIAN HIGH PRESSURE SYSTEM BUILD INTO THE AREA. THIS WILL RETURN TEMPERATURES ON SUNDAY BACK TO BELOW NORMAL VALUES...BUT WITH 850 MB TEMPERATURES AROUND -5C...SURFACE TEMPERATURES WILL REMAIN IN THE MID 20S FOR MOST PLACES. THIS SHORTWAVE WILL ALSO BRING SOME WEAK QG FORCING ACROSS THE AREA DURING THE DAY SUNDAY. HOWEVER...WITH THE STRENGTHENING DOWNSLOPE NORTHWESTERLY FLOW BEHIND THE SURFACE LOW...SNOW SHOWERS WILL MAINLY BE CONFINED TO MOUNTAIN LOCATIONS. DECIDED TO SHOW ONLY SLIGHT CHANCE POPS ACROSS THE PLAINS AS SNOW SHOWERS ACROSS THE PLAINS SHOULD REMAIN WIDELY SCATTERED. FOR MONDAY THROUGH WEDNESDAY...GLOBAL MODEL SOLUTIONS ARE CONSISTENT WITH BUILDING A HIGH AMPLITUDE RIDGE WEST OF THE FORECAST AREA WITH NORTHWESTERLY OVERHEAD. HOWEVER...THE MODELS ARE STRUGGLING WITH THE EXACT PLACEMENT OF THE RIDGE AND THUS ARE SHOWING WIDE VARIATIONS IN THE HIGH TEMPERATURE FORECASTS FROM RUN TO RUN. OVERALL THIS WILL BE A DRY PATTERN FOR THE FORECAST AREA WITH DOWNSLOPE FLOW PREVAILING. BACKDOOR COLD FRONTS WILL BE POSSIBLE IN THIS PATTERN DEPENDING ON HOW THE DETAILS DEVELOP. FOR NOW HAVE ELECTED TO RIDE CLOSE TO THE MIDDLE OF THE GUIDANCE ENVELOPE FOR TEMPERATURES DURING THIS PERIOD UNTIL THE MODELS BECOME MORE CONSISTENT WITH THE DETAILS. CHURCH && .AVIATION... VFR CONDITIONS WILL PREVAIL THIS MORNING ACROSS ALL TAF SITES. A WEATHER SYSTEM WILL BRING LOWERING CLOUD DECKS AND SNOW SPREADING FROM WEST TO EAST DURING THE DAY. EXPECT SNOW TO IMPACT KLVM WITH MVFR TO IFR CONDITIONS BY LATE WEDNESDAY MORNING. SNOW WILL SPREAD EAST...BRINGING MVFR TO IFR CONDITIONS TO KBIL AND KSHR BY LATE AFTERNOON OR EARLY EVENING. KMLS WILL SEE A LOWERING CLOUD DECK THIS AFTERNOON...BUT LIGHT SNOW BRINGING MVFR/IFR CONDITIONS WILL NOT BEGIN UNTIL AFTER MIDNIGHT TONIGHT. CHURCH && .PRELIMINARY POINT TEMP/POPS... TDY THU FRI SAT SUN MON TUE ------------------------------------------------------- BIL 014 008/017 006/026 014/033 015/025 011/031 014/034 5/S 87/S 01/E 01/N 22/S 11/B 10/N LVM 017 009/023 007/025 014/033 015/024 007/027 012/034 6/S 86/S 11/E 11/N 23/S 11/B 11/N HDN 014 007/016 002/026 011/031 011/025 011/030 014/033 5/S 87/S 11/E 01/B 12/S 11/B 10/B MLS 009 003/011 903/018 007/026 008/021 011/027 012/029 1/B 66/S 11/E 11/B 12/S 11/B 11/B 4BQ 012 005/013 903/022 007/030 009/023 007/030 011/034 2/S 88/S 31/E 11/B 12/S 11/B 10/B BHK 008 001/012 904/016 006/024 007/019 009/025 011/027 1/B 67/S 21/E 11/B 12/S 11/B 11/B SHR 018 008/018 006/028 007/031 007/026 008/030 012/031 4/S 88/S 31/E 01/U 12/S 11/B 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
707 PM CST THU DEC 27 2012 .UPDATE...MODEL INITIALIZATION FROM THE RAP AS OF 23Z INDICATES A WEAK LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS WITH MODEST RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY EXTENDS FROM WEST TEXAS...EAST/NORTHEAST INTO THE LOWER MISSISSIPPI VALLEY AND SOUTHEASTERN CONUS. TROPOSPHERIC FLOW OVER THE CENTRAL PLAINS REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT ~70KTS NEAR 300MB PER 23Z RAP ANALYSIS SOUNDING DATA FOR KGRI. WATER VAPOR IMAGERY INDICATES A MID LEVEL LOW OVER NORTHERN NEBRASKA AND SOUTHERN SOUTH DAKOTA...MOVING EAST/NORTHEAST. INCREASED VALUES OF MID LEVEL MOISTURE ARE ALSO NOTED OVER SOUTHERN PORTIONS OF THE CONUS...EXTENDING ALONG THE LEVEL JET AXIS. MID LEVEL MOISTURE FARTHER NORTHWEST HOWEVER...ACROSS OUR REGION...REMAINS FAIRLY MEAGER. AT THE SURFACE A STATIONARY BOUNDARY IS NOTED EXTENDING ACROSS PORTIONS OF CENTRAL AND EASTERN KANSAS AND AS OF 00Z WAS NOTED FROM NEAR KMHK...TO HEAR KHUT AND NEAR KICT. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE EAST/NORTHEAST AS A RESULT...WITH THE SOUTHEASTERLY LOW LEVEL WIND FIELD RELEGATED TO THE SOUTHEAST OF OUR AREA...SOUTHEAST OF THE LOW LEVEL BAROCLINIC ZONE. RAP DATA SUGGESTS THE PRIMARY AXIS OF MID LEVEL THERMAL ADVECTION AND DPVA HAVE DEPARTED OUR AREA TO THE NORTHEAST AND WITH AN OVERALL LACK IN OMEGA...SUBSTANTIAL SNOWFALL SHOULD BE HARD TO COME BY ACROSS OUR AREA THROUGH THE REST OF TONIGHT. THAT BEING SAID...THERMAL ADVECTION ACROSS THE AFOREMENTIONED LOW LEVEL BAROCLINIC ZONE IS PROMOTING ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY BETWEEN THE 275 AND 285K SURFACES. STRATUS HAS RESULTED ACROSS MUCH OF OUR AREA...WITH CEILINGS GENERALLY BETWEEN 1000 AND 3000FT AGL NOTED AS OF 00Z. SOUNDINGS FROM ACROSS THE CWA PER RAP ANALYSIS DATA SUGGESTS THIS STRATUS EXTENDS VERTICALLY TO NEAR 800MB...WITH THE TEMPERATURE NEAR 850MB JUST BARELY BREAKING INTO THE DENDRITIC ZONE AT AROUND -12 OR -13 C. PERIODIC SNOW FLURRIES HAVE BEEN NOTED ACROSS MUCH OF THE CWA THIS EVENING AS A RESULT. GIVEN THAT THE PRIMARY AXIS OF OMEGA HAS SHIFTED WELL NORTHEAST OF OUR AREA...OPTED TO REMOVE POPS FROM ACROSS THE CWA THROUGH THE REST OF TONIGHT...BUT ALSO EXTENDED ISOLATED FLURRIES ACROSS THE ENTIRE CWA TO ACCOUNT FOR THE CURRENT ACTIVITY. NOTHING MORE THAN TRACE AMOUNTS OF SNOWFALL ARE ANTICIPATED ACROSS THE CWA THROUGH TONIGHT. THERE ARE SOME INDICATIONS...IN PARTICULAR FROM THE NAM AND RAP...THAT LOWER TROPOSPHERIC RH VALUES COULD BE HIGH ENOUGH FOR THE DEVELOPMENT OF PATCHY FOG LATER TONIGHT...ESPECIALLY AS TEMPERATURES NEAR 850MB WARM SLIGHTLY...AS SUGGESTED BY THE NAM AND RAP...THUS MOVING THE CURRENT STRATUS LAYER OUT OF THE DENDRITIC ZONE. IT APPEARS THE MOST LIKELY AREA TO OBSERVE SUCH DEVELOPMENT WOULD BE ACROSS OUR SOUTHEASTERN CWA WHICH IS WHERE THE HIGHEST LOWER TROPOSPHERIC MOISTURE WILL RESIDE. CONTEMPLATED ADDING LIGHT FREEZING DRIZZLE TO THE GRIDS FOR TONIGHT AS IT APPEARS AS THOUGH 0-0.5KM RH VALUES WILL ALSO BE VERY HIGH...NOT JUST AT THE SURFACE. THAT BEING SAID...THE RAP AND NAM BOTH SUGGEST LOW LEVEL TURBULENT MIXING WILL REMAIN VERY WEAK WITH 0-0.5KM BULK SHEAR UNDER 10KTS THROUGH MUCH OF THE NIGHT...THUS MAKING FOG PRODUCTION THE MORE LIKELY SCENARIO. GIVEN ALL THIS...WENT AHEAD AND INSERTED PATCHY FREEZING FOG TO THE GRIDS FOR OUR SOUTHEASTER CWA FOR TONIGHT. THE VISIBILITY AT LOCATIONS SUCH AS KK61 AND KCNK HAVE DROPPED TO AROUND 5SM AT TIMES THIS EVENING AND THIS IS A TREND WHICH WILL NEED TO BE MONITORED. && .PREV DISCUSSION... /ISSUED 541 PM CST THU DEC 27 2012/ AVIATION...00Z KGRI TAF. MVFR TO IFR CONDITIONS FORECAST THROUGH THE TAF PERIOD. CEILINGS BETWEEN 1000FT AGL AND 3000FT AGL ARE LIKELY THROUGH MUCH OF THE TAF PERIOD. ALTHOUGH CONFIDENCE IS NOT AS HIGH...CEILINGS NEAR 800FT AGL WILL ALSO BE POSSIBLE TONIGHT. PERIODIC LIGHT SNOW WILL PERSIST AT THE TERMINAL THROUGH TONIGHT...WITH PATCHY FOG ALSO NOT OUT OF THE REALM OF POSSIBILITIES. THE PATCHY LIGHT SNOW AND POSSIBLE FOG WILL CREATE RESTRICTED VISIBILITY AT THE TERMINAL...GENERALLY BETWEEN 2SM AND 3SM...THROUGH 13Z. THE SURFACE WIND WILL REMAIN LIGHT AND VARIABLE TONIGHT...BECOMING MORE ESTABLISHED FROM THE NORTHWEST AT AROUND 11KTS DURING THE DAY FRIDAY. PREV DISCUSSION... /ISSUED 343 PM CST THU DEC 27 2012/ SHORT TERM...TONIGHT THROUGH FRIDAY. MAIN CHALLENGE WILL BE DETERMINING CHANCES OF SNOW TONIGHT. TROUGH AXIS HAS YET TO CROSS TO THE EAST...BUT MOST OF THE ENERGY RESPONSIBLE FOR ACCUMULATING SNOW HAS SHIFTED NORTH. THEREFORE CUT BACK CHANCES OF PRECIPITATION CONSIDERABLY...YET KEPT WIDESPREAD FLURRIES FOR MOST OF THE CWA THIS EVENING...WITH LINGERING SCATTERED FLURRIES OVERNIGHT AS THE TROUGH AXIS FINALLY MAKES ITS WAY TO THE EAST OF THE CWA OVERNIGHT. SURFACE HIGH BUILDS IN FOR FRIDAY...BUT STRATUS IS FORECAST TO BE STUBBORN TO LEAVE. STILL A LOT OF COLD AIR AROUND WITH SNOW ON THE GROUND AND CLOUDY SKY...THIS WILL ADD UP TO A COLDER THAN NORMAL DAY. YANKED FREEZING DRIZZLE FROM THE SOUTHEASTERN CWA AS TEMPERATURES SHOULD BE A LITTLE TOO COLD AT THE TOP OF THE LOW-LEVEL SATURATION LAYER TO ALLOW SUPERCOOLED WATER TO REMAIN...WITH PERHAPS SNOWGRAIN TYPE PRECIPITATION IF ANYTHING THIS EVENING. ALL IN ALL...MOST OF ANY APPRECIABLY ACCUMULATING SNOW HAS ENDED FOR THE CWA. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. BEGINNING FRIDAY NIGHT...AN UPPER TROUGH AXIS EXITS THE NORTHERN AND CENTRAL PLAINS. MODELS INDICATE POTENTIAL FOR LOW CLOUDS/STRATUS LINGERING ACROSS OUR EASTERN ZONES FOR A FEW HOURS DURING THE EVENING...THEN CLOUDS LOOK TO DEPART BY MIDNIGHT WITH DEPARTING TROUGH AND HEIGHTS RISES WHILE DOWNSLOPE LLVL FLOW DEVELOPS. THE COLD AIRMASS BEGINS TO DISLODGE ON SATURDAY AS AN INTERMOUNTAIN RIDGE EXPANDS EASTWARD ONTO THE PLAINS WITH WARMING AIDED BY A WESTERLY DOWNSLOPE WIND COMPONENT. THE SHORTWAVE RIDGE AXIS BREAKS DOWN HEADING INTO SUNDAY AS AN UPSTREAM TROUGH CROSSES THE NORTHERN PLAINS. THE ASSOCIATED COLD FRONTAL PASSAGE ASSOCIATED WITH THIS NEXT TROUGH HOLDS OFF UNTIL SUNDAY AFTN/EVE SO SUNDAY IS STILL LOOKING LIKE THE WARMEST DAY OF THE NEXT SEVERAL DAYS AHEAD OF THIS NEXT COLD FRONT. WILL AIM FOR HIGHS RIGHT AROUND 30 DEGREES WITH SOME MID/UPPER 30S IN NC KANSAS WHERE SNOW PACK/DEPTH IS NOT AS MUCH OF AN ISSUE. WILL NEED TO MONITOR FOR POTENTIAL FOG DEVELOPMENT IF WE CAN GET SOME DECENT MELTING OF THE SNOW. A 1030MB TO 1035MB SFC HIGH...WITH THE STRENGTH DEPENDENT UPON THE MODEL...BUILDS SOUTH BEHIND THE FRONT SUNDAY NIGHT INTO MONDAY AND SETTLES IN UNTIL AROUND THE TUESDAY TIME FRAME WITH A GENERAL COLD WINTER AIRMASS IN PLACE. A FEW DAYS AGO MODELS WERE INDICATING MUCH COLDER ARCTIC AIR THAN WHAT IS SUGGESTED AT THIS TIME NOW. EXTENDED MODELS DIVERGE EARLY TO MID WEEK OF NEXT WEEK WITH HANDLING OF SOUTHWEST CONUS SYSTEM WITH ECMWF STRONGER THAN THE MORE PROGRESSIVE GFS...AND CLOSES OFF THE SYSTEM VS GFS OPEN WAVE. CONFIDENCE LOWERS BY MID WEEK OF NEXT WEEK DUE TO MODEL DIFFERENCES AND WILL MAINTAIN STATUS QUO FOR TEMPS AND NOT SWING WARMER/COOLER OR WETTER UNTIL MODELS COME INTO BETTER AGREEMENT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE/AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...FAY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1212 PM CST WED DEC 26 2012 .AVIATION... 18Z TAFS FOR KOFK...KOMA AND KLNK. VFR CONDITIONS EXPECTED TO CONTINUE THROUGH 27/12Z WITH CONDITIONS BECOMING MVFR TO IFR AFTER 12Z AS UPPER SYSTEM SPREADS SNOW INTO THE AREA AS IT MOVES INTO THE NORTHERN PLAINS. && .PREV DISCUSSION... /ISSUED 305 AM CST WED DEC 26 2012/ DISCUSSION... SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR TEMPERATURE FLUCTUATIONS. EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F. WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL 0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1. QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND. WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5 LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2 INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE THURSDAY. WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST. TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH. AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY. MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN THE FORECAST AREA. CHERMOK && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ FOBERT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
607 AM CST WED DEC 26 2012 .AVIATION... 12Z TAFS FOR KOFK...KOMA AND KLNK. VFR CONDITIONS ARE EXPECTED THROUGH 27/12Z. AN AREA OF MID LEVEL CLOUDS WITH BASES OF 7000-10000 FT WILL DRIFT THROUGH EASTERN NEBRASKA THIS MORNING THEN CLEARING EXPECTED. LIGHT NORTHEAST WINDS SHOULD SLOWLY TURN TO THE EAST BUT MAY BE VARIABLE DUE TO THE HIGH PRESSURE AREA IN THE REGION. NIETFELD && .PREV DISCUSSION... /ISSUED 305 AM CST WED DEC 26 2012/ DISCUSSION... SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR TEMPERATURE FLUCTUATIONS. EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F. WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL 0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1. QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND. WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5 LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2 INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE THURSDAY. WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST. TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH. AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY. MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN THE FORECAST AREA. CHERMOK && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
305 AM CST WED DEC 26 2012 .DISCUSSION... SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR TEMPERATURE FLUCTUATIONS. EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F. WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL 0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1. QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND. WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5 LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2 INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE THURSDAY. WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST. TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH. AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY. MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN THE FORECAST AREA. CHERMOK && .AVIATION... 06Z TAFS FOR KOFK...KOMA AND KLNK. VFR CONDITIONS WILL PREVAIL THRU THE 24HR FCST PD. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
341 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK. && .NEAR TERM /THROUGH THURSDAY/... CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS AFTERNOON AS LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL WATER VAPOR IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING ACROSS THE EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY SLOT BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE SYSTEM/S MOVEMENT UP THE EAST COAST. THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND 06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z. FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE. ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD. SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14" WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH. FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC TO THE SOUTH. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY... STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325 DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR FLURRIES DURING THE DAY. NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY. MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW DOES NOT APPEAR LIKELY AT THIS TIME. .LONG TERM /SUNDAY THROUGH TUESDAY... GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID 20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... MODERATE TO HEAVY SNOW WILL OVERSPREAD THE TAF SITES FROM SOUTH TO NORTH THROUGH 22Z. VSBYS WILL FALL TO AROUND HALF A MILE AND OCCASIONALLY LOWER WITH CIGS BELOW 1000 FEET QUICKLY ONCE THE SNOW STARTS. SNOW WILL BECOME LIGHTER THEN CHANGE TO LIGHT MIXED PRECIPITATION AT AVP AFTER 01Z. FARTHER NORTH SNOW WILL BECOME LIGHTER AFTER 03Z. SNOW WILL BECOME SHOWERY ON THURSDAY WITH MVFR TO OCNL IFR CONDITIONS PERSISTING THROUGH THE DAY IN CENTRAL NY. MVFR TO OCNL VFR CONDITIONS CAN BE EXPECTED AT AVP WITH LIGHT MIXED PRECIPITATION CHANGING TO LIGHT SNOW SHOWERS DURING THE AFTERNOON. WINDS WILL BE E-NE AT 5 TO 15 KT TODAY INCREASING TO 10 TO 20 KT TONIGHT THEN SHIFTING TO NW AT 10 TO 20 KTS ON THURSDAY. OUTLOOK... THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY. FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE EFFECT SNOW. SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR. SUN...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE EFFECT SN. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR PAZ038>040- 043-044-047-048-072. NY...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NYZ009- 015>018-022>025-036-037-044>046-055>057-062. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...MSE LONG TERM...MSE AVIATION...MSE
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1255 PM EST WED DEC 26 2012 .SYNOPSIS... LOW PRESSURE SYSTEM WILL MOVE NORTH FROM TENNESSEE AND DEEPEN AS IT TRACKS TOWARD THE MID ATLANTIC COAST THROUGH THIS EVENING. SEVERE THUNDERSTORMS WILL BE POSSIBLE IN THE WARM MOIST AIRMASS THIS AFTERNOON. A COLD FRONT WILL CROSS THE REGION THIS EVENING. COOL AND DRY HIGH PRESSURE WILL BUILD IN THROUGH FRIDAY. ANOTHER COLD FRONT WILL MOVE THROUGH LATE SATURDAY FOLLOWED BY HIGH PRESSURE EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM WEDNESDAY...TORNADO WATCH CONTINUES WITH SEVERE WEATHER STILL POSSIBLE EARLY THIS AFTERNOON. SLIGHT RISK FROM SPC AS DYNAMIC FRONTAL SYSTEM MOVING UP FROM TENNESSEE TOWARD THE MID ATLANTIC COAST THROUGH TODAY. SOUTHERLY LLJ UP TO 65 KTS COMBINING WITH STRONG FORCING ASSOCIATED WITH A FAST MOVING COLD FRONT...AN INCREASINGLY CLOSED AND NEGATIVELY TILTED UPPER TROUGH AND FAVORABLE PLACEMENT RELATIVE TO AN UPPER JET EXIT REGION. WARM FRONT MOVING NORTH HAS CLEARED LOCAL CWA WITH AREA RICH IN DEWPOINTS IN THE LOWER 60S FOR THE MOST PART IN GUSTY SOUTHERLY WINDS. SOME REPORTS OF GUSTS TO 35 MPH REPORTED INTO EARLY THIS AFTERNOON. THIS WILL INCREASE SFC BASED CAPE BUT LATEST RUC NOT VERY IMPRESSIVE WITH HIGHER CAPES REMAINING OFF SHORE. NAM STILL SHOWING VALUES INCREASING UP TO 800 TO 1000 J/KG IN A SMALL AREA LEADING UP FROM WINYAH BAY UP THROUGH HORRY AND ROBISON COUNTIES EARLY THIS AFTERNOON. THIS AREA SHIFTS EAST NORTHEAST AND WEAKENS AS COLD FRONT APPROACHES FROM THE WEST. LATEST OBS SHOWING DRY AIR MAKING ITS WAY EAST INTO WESTERN PORTION OF CWA. DEWPOINTS DROPPING WEST OF I95 THROUGH SOUTH CAROLINA INTO NORTH CAROLINA WITH READINGS DOWN CLOSER TO 50 OR BELOW AS WINDS VEERING TO THE SOUTHWEST. WINDOW OF OPPORTUNITY FOR SEVERE WEATHER WILL BE SHRINKING THROUGH THIS AFTERNOON AS WINDS SHIFT TO SOUTHWEST AND DRY AIR MAKES ITS WAY IN. LOOKS LIKE SYSTEM HAS SPED UP IN TERMS OF BEST CHC OF SEVERE WEATHER WITH GREATEST PROBABILITY IN WARM SECTOR AHEAD OF APPROACHING COLD FRONT THROUGH MID AFTERNOON. MODELS IN FAIRLY GOOD AGREEMENT WITH PEAK IN SVR WEATHER THREAT BETWEEN NOON AND 2 PM WITH DRY AIR MAKING ITS WAY IN AS WINDS SHIFT TO SOUTHWEST TO WEST THROUGH LATE AFTERNOON. CONDITIONS RAPIDLY IMPROVE AFTER THIS...ALTHOUGH IT WILL REMAIN BREEZY OVERNIGHT WITH TEMPERATURES DROPPING INTO THE 30S MOST LOCATIONS AWAY FROM THE BEACHES. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...DEEP WEST TO NORTHWEST FLOW AND DRY AIR IN THE WAKE OF EXITING STORM SYSTEM WILL KEEP THE REGION DRY FOR MUCH OF THE PERIOD. COLD ADVECTION WILL BE LIMITED AS MID LEVEL TROUGH LIFTING NORTHEAST LEAVES PROGRESSIVE FLOW IN PLACE THU/THU NIGHT. AS ELONGATED SURFACE RIDGE AXIS SHIFTS EAST LOW LEVEL WINDS VEER FROM NORTHWEST THU TO NORTHEAST ON FRI. AT THE SAME TIME SHORTWAVE DROPPING INTO THE SOUTHWEST CONUS INDUCES WEAK MID LEVEL RIDGING OVER THE SOUTHEAST. DEEP SOUTHWEST FLOW ALOFT STARTS ADVECTING MOISTURE INTO THE REGION. FIRST HINT WILL BE CIRRUS DEVELOPMENT LATER FRI FOLLOWED BY MID AND LOW LEVEL CLOUDS FRI NIGHT. THE AFOREMENTIONED SOUTHWEST SHORTWAVE CONTRIBUTES TO DEVELOPMENT OF GULF COAST LOW PRESSURE AT THE START OF THE WEEKEND. THIS LOW AND ASSOCIATED MID LEVEL TROUGH MOVE INTO THE SOUTHEAST AS THE PERIOD ENDS. STILL SOME UNCERTAINTY ON THE TRACK OF THE LOW AND WHETHER OR NOT IT PASSES OVER OR OFF THE COAST BUT IT APPEARS THAT WILL BE AN ISSUE FOR THE LONG TERM. ALTHOUGH GUIDANCE IS QUICK TO SHOW SOUTHERLY FLOW DEVELOPING IT IS LIKELY THAT LOW LEVEL WEDGE HOLDS STRONG INTO FIRST PART OF SAT...KEEPING ANY PRECIP LIGHT AND STRATIFORM LATE FRI NIGHT. PLAN TO CARRY LOW CHANCE POP AS PERIOD ENDS BUT WITH LITTLE TO NO QPF GIVEN THE AMOUNT OF LOW LEVEL DRY AIR SHOWN IN FORECAST SOUNDINGS...SOMETHING WHICH FURTHER SUGGESTS THE WEDGE WILL HOLD. DESPITE LIMITED STRENGTH AND DURATION OF COLD ADVECTION TEMPERATURES WILL RUN BELOW CLIMO THU/THU NIGHT. LOW LEVEL COLD POOL WILL KEEP HIGHS IN THE UPPER 40S TO LOWER 50S WITH STRONG RADIATIONAL COOLING THU NIGHT DROPPING TEMPS BELOW FREEZING IN MANY AREAS. NORTHEAST FLOW FRI COMBINED WITH LOW SUN ANGLE LIMITS AIR MASS MODIFICATION DURING THE DAY. HIGHS END UP WARMER THAN THU BUT STILL BELOW CLIMO. CLOUD COVER AND WEAK BOUNDARY LAYER WINDS KEEP TEMPERATURES NEAR CLIMO FRI NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY...MOST SIGNIFICANT WEATHER FEATURE WILL ALREADY BE UNDERWAY AS THE PERIOD BEGINS. GULF COAST LOW TRACKING ACROSS THE SOUTHEAST WILL BRING RAIN...SHOWERS AND POSSIBLE THUNDERSTORMS TO THE SOUTHEAST SAT. UNCERTAINTY WITH RESPECT TO THE TRACK OF THE LOW LIMITS THE SPECIFICITY OF THE FORECAST AT THIS POINT...BUT DO HAVE FAIRLY HIGH CONFIDENCE IN PRECIP OCCURRING...HENCE LIKELY POP. MEDIUM RANGE GUIDANCE IS SPLIT ON TAKING LOW OVER OR OFF THE COAST SAT...THOUGH GFS ENSEMBLES HAVE BEEN TRENDING IN THE DIRECTION OF PASSING THE MAIN SURFACE LOW JUST SOUTHEAST OF THE REGION...IN LINE WITH 12Z ECMWF SOLUTION AND HPC SOLUTION. THIS SOLUTION WOULD SUGGEST RAIN OPPOSED TO SHOWERS AND ISOLATED THUNDERSTORMS. POSITIVE TO NEUTRAL TILT OF MID LEVEL TROUGH AND LIMITED INTERACTION WITH NORTHERN STREAM QUICKLY MOVE THE SYSTEM ACROSS THE SOUTHEAST AND INTO THE MID ATLANTIC REGION BY SAT NIGHT. AT THIS POINT THE MID LEVEL TROUGH ATTAINS SOME NEGATIVE TILT AND THE STORM STARTS TO DEEPEN. WHILE PRECIP WILL NOT BE AN ISSUE IN THE CAROLINAS STRONG COLD ADVECTION ON THE BACKSIDE OF THE STORM PUSHES COLD AIR OVER THE REGION FOR THE START OF NEXT WEEK. PARTIAL THICKNESS VALUES SUGGEST HIGHS IN THE UPPER 40S TO LOWER 50S WITH LOWS IN THE UPPER 20S TO LOWER 30S SUN AND MON. CONFIDENCE REMAINS LOW FOR THE END OF THE PERIOD WITH COLD FRONT DROPPING IN FROM THE NORTH THEN STALLING ACROSS OR JUST SOUTH OF THE AREA. MEANWHILE MEDIUM RANGE GUIDANCE IS SHOWING ANOTHER SOUTHWEST SHORTWAVE AND WEAK GULF COAST CYCLOGENESIS LATE MON INTO TUE...WHICH MAY OR MAY NOT QUICKLY MOVE ACROSS THE SOUTHEAST. GIVEN THAT THE WAVE IS WELL OUTSIDE THE UPPER AIR SENSING NETWORK AND ALMOST A WEEK AWAY WILL KEEP POP CAPPED AT SLIGHT CHANCE WITH TEMPERATURES NEAR CLIMO. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...CONVECTION MARCHING TO THE COAST. FLO SHOULD BE OUT OF THE WOODS EARLY ON...BECOMING VFR. LBT WILL FOLLOW SUIT AN HOUR OR SO LATER. THE COAST WILL EXPERIENCE INTERMITTENT IFR CONDITIONS THROUGH AROUND 21Z...WITH RAPIDLY IMPROVING CONDITIONS SHORTLY AFTER. TONIGHT...VFR WITH GUSTY WEST SOUTHWEST WINDS BEHIND THE FRONT. THINGS WILL SLOWLY SETTLE DOWN SOMEWHAT AFTER MIDNIGHT. THURSDAY...VFR WITH A PREDOMINATELY WEST WIND...STRONGEST GUSTS AROUND MID MORNING. EXTENDED OUTLOOK...VFR WILL CONDITIONS WILL PERSISTING THROUGH FRIDAY. MVFR/IFR CONDITIONS ARE POSSIBLE AGAIN SATURDAY AS ANOTHER LOW PRESSURE SYSTEM AFFECTS THE AREA. VFR CONDITIONS EXPECTED SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM WEDNESDAY...GALE WARNING CONTINUES WITH WINDS AND SEAS UP ACROSS THE LOCAL WATERS WITH WINDS UP BETWEEN 25 AND 35 MOST WATERS AND SEAS UP TO 6 TO 9 FT. EXTREMELY DANGEROUS BOATING CONDITIONS OVER ALL WATERS THROUGH TONIGHT...WITH A GALE WARNING IN EFFECT INTO THE EARLY MORNING HOURS OF THURSDAY. A POWERFUL STORM SYSTEM EMERGING FROM THE DEEP SOUTH WILL BRING THE POSSIBILITY OF HEAVY RAIN...THUNDERSTORMS AND WATER SPOUTS TO THE WATERS THROUGH THIS AFTERNOON. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM WEDNESDAY...WESTERLY FLOW AT THE START OF THE PERIOD MAY REQUIRE SCA FOR THE FIRST FEW HOURS OF THU MORNING BEFORE SPEEDS DROP UNDER 20 KT AS GRADIENT WEAKENS. SURFACE RIDGE AXIS SHIFTING EAST LEADS TO FURTHER REDUCTION IN GRADIENT. THIS RESULTS IN WINDS DECREASING AND VEERING FROM NORTHWEST LATE THU TO NORTHERLY THU NIGHT. WINDS DROP UNDER 10 KT EARLY FRI AS RIDGE AXIS SHIFTS EAST AND FLOW BECOMES NORTHEASTERLY. WEAK ONSHORE FLOW MAY DEVELOP LATE IN THE PERIOD...BUT THIS WILL DEPEND ON THE LOCATION AND TRACK OF SURFACE LOWS MOVING INTO THE SOUTHEAST AS THE PERIOD ENDS. STRONG WESTERLY FLOW WILL RESULT IN A WIDE RANGE OF SEAS AT THE START OF THE PERIOD...2 FT TO 7 FT NEAR 20 NM IN THE VICINITY OF FRYING PAN SHOALS. CONTINUED REDUCTION IN WINDS COMBINED WITH GRADUAL VEERING ALLOWS SEAS TO SUBSIDE TO 2 FT FOR FRI AND FRI NIGHT. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...BRIEF PERIOD OF SOUTHERLY FLOW POSSIBLE SAT...THOUGH EXACT TRACK OF MAIN SURFACE LOW REMAINS SOMEWHAT IN QUESTION AND FLOW COULD END UP OFFSHORE THROUGH THE DURATION OF THE PERIOD. CLOSE PROXIMITY OF WATERS TO SURFACE LOW WILL KEEP WINDS UNDER 15 KT THROUGH SAT AFTERNOON. WEST TO NORTHWEST FLOW INCREASES LATE SAT AS LOW EXITS AND STARTS TO DEEPEN OFF THE MID-ATLANTIC COAST. STRENGTHENING LOW AND HIGH PRESSURE BUILDING IN FROM THE WEST CONTRIBUTE TO AN INCREASE IN WINDS AND SEAS...POSSIBLY REQUIRING A HEADLINE LATE SAT NIGHT THROUGH MIDDAY SUN. SURFACE HIGH CONTINUES TO BUILD IN WITH GRADIENT STARTING TO RELAX IN THE AFTERNOON AND NORTHWEST FLOW DECREASING TO 10 TO 15 LATE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...GALE WARNING UNTIL 3 AM EST THURSDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...RGZ SHORT TERM...III LONG TERM...III AVIATION...DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1245 PM EST WED DEC 26 2012 .SYNOPSIS... LOW PRESSURE SYSTEM WILL MOVE NORTH FROM TENNESSEE AND DEEPEN AS IT TRACKS TOWARD THE MID ATLANTIC COAST THROUGH THIS EVENING. SEVERE THUNDERSTORMS WILL BE POSSIBLE IN THE WARM MOIST AIRMASS THIS AFTERNOON. A COLD FRONT WILL CROSS THE REGION THIS EVENING. COOL AND DRY HIGH PRESSURE WILL BUILD IN THROUGH FRIDAY. ANOTHER COLD FRONT WILL MOVE THROUGH LATE SATURDAY FOLLOWED BY HIGH PRESSURE EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM WEDNESDAY... SEVERE WEATHER STILL POSSIBLE EARLY THIS AFTERNOON. SLIGHT RISK FROM SPC AS DYNAMIC FRONTAL SYSTEM MOVING UP FROM TENNESSEE TOWARD THE MID ATLANTIC COAST THROUGH TODAY. SOUTHERLY LLJ UP TO 65 KTS COMBINING WITH STRONG FORCING ASSOCIATED WITH A FAST MOVING COLD FRONT...AN INCREASINGLY CLOSED AND NEGATIVELY TILTED UPPER TROUGH AND FAVORABLE PLACEMENT RELATIVE TO AN UPPER JET EXIT REGION. WARM FRONT MOVING NORTH HAS CLEARED LOCAL CWA WITH AREA RICH IN DEWPOINTS IN THE LOWER 60S FOR THE MOST PART IN GUSTY SOUTHERLY WINDS. SOME REPORTS OF GUSTS TO 35 MPH REPORTED INTO EARLY THIS AFTERNOON. THIS WILL INCREASE SFC BASED CAPE BUT LATEST RUC NOT VERY IMPRESSIVE WITH HIGHER CAPES REMAINING OFF SHORE. NAM STILL SHOWING VALUES INCREASING UP TO 800 TO 1000 J/KG IN A SMALL AREA LEADING UP FROM WINYAH BAY UP THROUGH HORRY AND ROBISON COUNTIES EARLY THIS AFTERNOON. THIS AREA SHIFTS EAST NORTHEAST AND WEAKENS AS COLD FRONT APPROACHES FROM THE WEST. LATEST OBS SHOWING DRY AIR MAKING ITS WAY EAST INTO WESTERN PORTION OF CWA. DEWPOINTS DROPPING WEST OF I95 THROUGH SOUTH CAROLINA INTO NORTH CAROLINA WITH READINGS DOWN CLOSER TO 50 OR BELOW AS WINDS VEERING TO THE SOUTHWEST. WINDOW OF OPPORTUNITY FOR SEVERE WEATHER WILL BE SHRINKING THROUGH THIS AFTERNOON AS WINDS SHIFT TO SOUTHWEST AND DRY AIR MAKES ITS WAY IN. LOOKS LIKE SYSTEM HAS SPED UP IN TERMS OF BEST CHC OF SEVERE WEATHER WITH GREATEST PROBABILITY IN WARM SECTOR AHEAD OF APPROACHING COLD FRONT THROUGH MID AFTERNOON. MODELS IN FAIRLY GOOD AGREEMENT WITH PEAK IN SVR WEATHER THREAT BETWEEN NOON AND 2 PM WITH DRY AIR MAKING ITS WAY IN AS WINDS SHIFT TO SOUTHWEST TO WEST THROUGH LATE AFTERNOON. CONDITIONS RAPIDLY IMPROVE AFTER THIS...ALTHOUGH IT WILL REMAIN BREEZY OVERNIGHT WITH TEMPERATURES DROPPING INTO THE 30S MOST LOCATIONS AWAY FROM THE BEACHES. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...DEEP WEST TO NORTHWEST FLOW AND DRY AIR IN THE WAKE OF EXITING STORM SYSTEM WILL KEEP THE REGION DRY FOR MUCH OF THE PERIOD. COLD ADVECTION WILL BE LIMITED AS MID LEVEL TROUGH LIFTING NORTHEAST LEAVES PROGRESSIVE FLOW IN PLACE THU/THU NIGHT. AS ELONGATED SURFACE RIDGE AXIS SHIFTS EAST LOW LEVEL WINDS VEER FROM NORTHWEST THU TO NORTHEAST ON FRI. AT THE SAME TIME SHORTWAVE DROPPING INTO THE SOUTHWEST CONUS INDUCES WEAK MID LEVEL RIDGING OVER THE SOUTHEAST. DEEP SOUTHWEST FLOW ALOFT STARTS ADVECTING MOISTURE INTO THE REGION. FIRST HINT WILL BE CIRRUS DEVELOPMENT LATER FRI FOLLOWED BY MID AND LOW LEVEL CLOUDS FRI NIGHT. THE AFOREMENTIONED SOUTHWEST SHORTWAVE CONTRIBUTES TO DEVELOPMENT OF GULF COAST LOW PRESSURE AT THE START OF THE WEEKEND. THIS LOW AND ASSOCIATED MID LEVEL TROUGH MOVE INTO THE SOUTHEAST AS THE PERIOD ENDS. STILL SOME UNCERTAINTY ON THE TRACK OF THE LOW AND WHETHER OR NOT IT PASSES OVER OR OFF THE COAST BUT IT APPEARS THAT WILL BE AN ISSUE FOR THE LONG TERM. ALTHOUGH GUIDANCE IS QUICK TO SHOW SOUTHERLY FLOW DEVELOPING IT IS LIKELY THAT LOW LEVEL WEDGE HOLDS STRONG INTO FIRST PART OF SAT...KEEPING ANY PRECIP LIGHT AND STRATIFORM LATE FRI NIGHT. PLAN TO CARRY LOW CHANCE POP AS PERIOD ENDS BUT WITH LITTLE TO NO QPF GIVEN THE AMOUNT OF LOW LEVEL DRY AIR SHOWN IN FORECAST SOUNDINGS...SOMETHING WHICH FURTHER SUGGESTS THE WEDGE WILL HOLD. DESPITE LIMITED STRENGTH AND DURATION OF COLD ADVECTION TEMPERATURES WILL RUN BELOW CLIMO THU/THU NIGHT. LOW LEVEL COLD POOL WILL KEEP HIGHS IN THE UPPER 40S TO LOWER 50S WITH STRONG RADIATIONAL COOLING THU NIGHT DROPPING TEMPS BELOW FREEZING IN MANY AREAS. NORTHEAST FLOW FRI COMBINED WITH LOW SUN ANGLE LIMITS AIR MASS MODIFICATION DURING THE DAY. HIGHS END UP WARMER THAN THU BUT STILL BELOW CLIMO. CLOUD COVER AND WEAK BOUNDARY LAYER WINDS KEEP TEMPERATURES NEAR CLIMO FRI NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY...MOST SIGNIFICANT WEATHER FEATURE WILL ALREADY BE UNDERWAY AS THE PERIOD BEGINS. GULF COAST LOW TRACKING ACROSS THE SOUTHEAST WILL BRING RAIN...SHOWERS AND POSSIBLE THUNDERSTORMS TO THE SOUTHEAST SAT. UNCERTAINTY WITH RESPECT TO THE TRACK OF THE LOW LIMITS THE SPECIFICITY OF THE FORECAST AT THIS POINT...BUT DO HAVE FAIRLY HIGH CONFIDENCE IN PRECIP OCCURRING...HENCE LIKELY POP. MEDIUM RANGE GUIDANCE IS SPLIT ON TAKING LOW OVER OR OFF THE COAST SAT...THOUGH GFS ENSEMBLES HAVE BEEN TRENDING IN THE DIRECTION OF PASSING THE MAIN SURFACE LOW JUST SOUTHEAST OF THE REGION...IN LINE WITH 12Z ECMWF SOLUTION AND HPC SOLUTION. THIS SOLUTION WOULD SUGGEST RAIN OPPOSED TO SHOWERS AND ISOLATED THUNDERSTORMS. POSITIVE TO NEUTRAL TILT OF MID LEVEL TROUGH AND LIMITED INTERACTION WITH NORTHERN STREAM QUICKLY MOVE THE SYSTEM ACROSS THE SOUTHEAST AND INTO THE MID ATLANTIC REGION BY SAT NIGHT. AT THIS POINT THE MID LEVEL TROUGH ATTAINS SOME NEGATIVE TILT AND THE STORM STARTS TO DEEPEN. WHILE PRECIP WILL NOT BE AN ISSUE IN THE CAROLINAS STRONG COLD ADVECTION ON THE BACKSIDE OF THE STORM PUSHES COLD AIR OVER THE REGION FOR THE START OF NEXT WEEK. PARTIAL THICKNESS VALUES SUGGEST HIGHS IN THE UPPER 40S TO LOWER 50S WITH LOWS IN THE UPPER 20S TO LOWER 30S SUN AND MON. CONFIDENCE REMAINS LOW FOR THE END OF THE PERIOD WITH COLD FRONT DROPPING IN FROM THE NORTH THEN STALLING ACROSS OR JUST SOUTH OF THE AREA. MEANWHILE MEDIUM RANGE GUIDANCE IS SHOWING ANOTHER SOUTHWEST SHORTWAVE AND WEAK GULF COAST CYCLOGENESIS LATE MON INTO TUE...WHICH MAY OR MAY NOT QUICKLY MOVE ACROSS THE SOUTHEAST. GIVEN THAT THE WAVE IS WELL OUTSIDE THE UPPER AIR SENSING NETWORK AND ALMOST A WEEK AWAY WILL KEEP POP CAPPED AT SLIGHT CHANCE WITH TEMPERATURES NEAR CLIMO. && .AVIATION /17Z WEDNESDAY THROUGH SUNDAY/... AS OF 18Z...CONVECTION MARCHING TO THE COAST. FLO SHOULD BE OUT OF THE WOODS EARLY ON...BECOMING VFR. LBT WILL FOLLOW SUIT AN HOUR OR SO LATER. THE COAST WILL EXPERIENCE INTERMITTENT IFR CONDITIONS THROUGH AROUND 21Z...WITH RAPIDLY IMPROVING CONDITIONS SHORTLY AFTER. TONIGHT...VFR WITH GUSTY WEST SOUTHWEST WINDS BEHIND THE FRONT. THINGS WILL SLOWLY SETTLE DOWN SOMEWHAT AFTER MIDNIGHT. THURSDAY...VFR WITH A PREDOMINATELY WEST WIND...STRONGEST GUSTS AROUND MID MORNING. EXTENDED OUTLOOK...VFR WILL CONDITIONS WILL PERSISTING THROUGH FRIDAY. MVFR/IFR CONDITIONS ARE POSSIBLE AGAIN SATURDAY AS ANOTHER LOW PRESSURE SYSTEM AFFECTS THE AREA. VFR CONDITIONS EXPECTED SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM WEDNESDAY...GALE WARNING CONTINUES WITH WINDS AND SEAS UP ACROSS THE LOCAL WATERS WITH WINDS UP BETWEEN 25 AND 35 MOST WATERS AND SEAS UP TO 6 TO 9 FT. EXTREMELY DANGEROUS BOATING CONDITIONS OVER ALL WATERS THROUGH TONIGHT...WITH A GALE WARNING IN EFFECT INTO THE EARLY MORNING HOURS OF THURSDAY. A POWERFUL STORM SYSTEM EMERGING FROM THE DEEP SOUTH WILL BRING THE POSSIBILITY OF HEAVY RAIN...THUNDERSTORMS AND WATER SPOUTS TO THE WATERS THROUGH THIS AFTERNOON. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM WEDNESDAY...WESTERLY FLOW AT THE START OF THE PERIOD MAY REQUIRE SCA FOR THE FIRST FEW HOURS OF THU MORNING BEFORE SPEEDS DROP UNDER 20 KT AS GRADIENT WEAKENS. SURFACE RIDGE AXIS SHIFTING EAST LEADS TO FURTHER REDUCTION IN GRADIENT. THIS RESULTS IN WINDS DECREASING AND VEERING FROM NORTHWEST LATE THU TO NORTHERLY THU NIGHT. WINDS DROP UNDER 10 KT EARLY FRI AS RIDGE AXIS SHIFTS EAST AND FLOW BECOMES NORTHEASTERLY. WEAK ONSHORE FLOW MAY DEVELOP LATE IN THE PERIOD...BUT THIS WILL DEPEND ON THE LOCATION AND TRACK OF SURFACE LOWS MOVING INTO THE SOUTHEAST AS THE PERIOD ENDS. STRONG WESTERLY FLOW WILL RESULT IN A WIDE RANGE OF SEAS AT THE START OF THE PERIOD...2 FT TO 7 FT NEAR 20 NM IN THE VICINITY OF FRYING PAN SHOALS. CONTINUED REDUCTION IN WINDS COMBINED WITH GRADUAL VEERING ALLOWS SEAS TO SUBSIDE TO 2 FT FOR FRI AND FRI NIGHT. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...BRIEF PERIOD OF SOUTHERLY FLOW POSSIBLE SAT...THOUGH EXACT TRACK OF MAIN SURFACE LOW REMAINS SOMEWHAT IN QUESTION AND FLOW COULD END UP OFFSHORE THROUGH THE DURATION OF THE PERIOD. CLOSE PROXIMITY OF WATERS TO SURFACE LOW WILL KEEP WINDS UNDER 15 KT THROUGH SAT AFTERNOON. WEST TO NORTHWEST FLOW INCREASES LATE SAT AS LOW EXITS AND STARTS TO DEEPEN OFF THE MID-ATLANTIC COAST. STRENGTHENING LOW AND HIGH PRESSURE BUILDING IN FROM THE WEST CONTRIBUTE TO AN INCREASE IN WINDS AND SEAS...POSSIBLY REQUIRING A HEADLINE LATE SAT NIGHT THROUGH MIDDAY SUN. SURFACE HIGH CONTINUES TO BUILD IN WITH GRADIENT STARTING TO RELAX IN THE AFTERNOON AND NORTHWEST FLOW DECREASING TO 10 TO 15 LATE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...GALE WARNING UNTIL 3 AM EST THURSDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS... NEAR TERM...RGZ SHORT TERM...III LONG TERM...III AVIATION...DL MARINE...
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1056 AM EST WED DEC 26 2012 .SYNOPSIS... LOW PRESSURE MOVING ACROSS TO THE NORTHWEST WILL PUSH A WARM FRONT ACROSS THE AREA FROM THE SOUTH THIS MORNING...AND THEN A COLD FRONT FROM THE WEST THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS FROM THE WEST THURSDAY AND FRIDAY. ANOTHER COMPLEX FRONTAL SYSTEM WILL AFFECT THE AREA SATURDAY AND SATURDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 10 AM WED...A POTENT STORM SYSTEM WILL CONTINUE TO IMPACT ERN NC THIS AFTERNOON AND A TORNADO WATCH HAS BEEN ISSUED THROUGH 5 PM THIS EVENING. A WARM FRONT IS JUST BEGINNING TO PUSH INLAND FROM CAPE HATTERAS THROUGH JACKSONVILLE AND HRRR PROGS IT TO PUSH TO AROUND THE I-95 CORRIDOR BY AROUND NOON TO 1 PM. THIS WILL PLACE ERN NC IN THE WARM SECTOR OF THE SYSTEM BRINGING INCREASED INSTABILITY AND SEVERE WEATHER THREAT. TREMENDOUS HELICITY IS IN PLACE ACROSS THE REGION WITH MODIFIED KMHX 12Z SOUNDING INDICATING OVER 700 M2/S2 0-3KM SRH AS WELL AS MODERATE INSTABILITY AROUND 600 J/KG ONCE WE MOVE INTO THE WARM SECTOR AND TEMPS CLIMB INTO THE M/U60S. SEVERAL CELLS ALREADY HAVE BEEN SHOWING SIGNS OF ROTATION AND THROUGH THE LATE MORNING INTO THE AFTERNOON WILL BE WATCHING FOR DISCRETE SUPERCELL POSSIBLE BRINGING TORNADOES AND DAMAGING WINDS...WHICH WILL POTENTIALLY BE FOLLOWED BY A STRENGTHENING QLCS AHEAD OF THE COLD FRONT WITH BOWING SEGMENTS POTENTIALLY BRINGING SEVERE WIND GUSTS AND TORNADOES. HRRR PROGS THIS LINE TO PUSH INTO WESTERN SECTIONS OF THE CWA AROUND 1-2 PM...THEN PUSH OFF THE COAST AROUND 6-7PM. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... AS OF 400 AM WED...COLD FRONT AND BACK EDGE OF SHRA/TSTMS EXPECTED TO BE NEAR COAST AT BEGINNING OF PERIOD AND OFFSHORE BY LATE EVENING...AND CONTINUED PREVIOUS FCST POPS. SOME DECREASE IN CLOUDS WILL FOLLOW FRONTAL PASSAGE BUT WHOLESALE CLEARING WILL BE DELAYED UNTIL PASSAGE OF UPR TROF TOWARD THU MORNING. GUSTY WINDS WILL CONTINUE OVERNIGHT WITH DEEPENING LOW PRES MOVING OFF MID ATLC COAST...AND CONTINUED WIND ADVSY FOR COASTAL SECTIONS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... COOLER/DRIER WEATHER FOLLOWS COLD FRONTAL PASSAGE FOR THURSDAY AND CONTINUING INTO FRIDAY. CIRCULATION AROUND DEPARTING LOW PRESSURE WILL KEEP BREEZY/WINDY CONDITIONS GOING INTO THURSDAY THEN DECREASING WINDS AS HIGH PRESSURE BUILDS INTO THE AREA THU NIGHT AND FRIDAY. HIGH TEMPS BOTH THU AND FRI UNIFORMLY WITHIN A FEW DEGS OF 50F. WITH LOWS THU NIGHT DIPPING INTO THE UPPER 20S (30S COAST) UNDER GOOD RADIATIONAL COOLING. THE PATTERN BECOMES MORE ACTIVE AND COMPLEX EARLY IN THE WEEKEND AS THE NEXT PROGRESSIVE AND POTENT SHORTWAVE MOVES ACROSS THE AREA. AT THE SURFACE A COASTAL WARM FRONT WILL NEGATIVE TILT UPPER TROF WILL MOVE RAPIDLY NE FROM THE TN VALLEY MOVE INTO COASTAL SECTIONS WHILE LOW PRESSURE DEVELOPS ALONG IT JUST OFF OF THE COAST. THIS LOW WILL DEEPEN RAPIDLY AS IT MOVES NE ALONG OR JUST OFF THE COAST SATURDAY AFTERNOON AND EVENING BEFORE MOVING OFF TO THE NE SATURDAY NIGHT. SHOWERS ARE EXPECTED TO DEVELOP LATE FRIDAY NIGHT AND CONTINUE FOR MUCH OF SATURDAY BEFORE ENDING SATURDAY EVENING. IT WILL AGAIN BE TURNING SHARPLY COLDER AND WINDY SATURDAY NIGHT AND SUNDAY. POSSIBLE WIDE RANGE IN HIGH TEMPERATURES SATURDAY WITH LOWER 60S COAST AND UPPER 40S DEEP INLAND. ON SUNDAY HIGHS ARE FORECAST TO ONLY BE IN THE MIDDLE TO UPPER 40S AREA WIDE. FAIR CONDITIONS WILL BE FORECAST MONDAY WITH HIGH PRESSURE OVER THE AREA THEN MOISTURE ROUNDING A BUILDING UPPER RIDGE OVER THE SOUTHEAST COULD BRING SOME RAIN TO THE AREA TUESDAY. TEMPERATURES REMAIN BLO NORMAL EARLY NEXT WEEK. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH 12Z THURSDAY/... AS OF 1030 AM WED...IFR CIGS ACROSS RTES THIS MORNING WITH PERIODS OF HEAVY RAIN. A WARM FRONT WILL BE LIFTING ACROSS THE REGION OVER THE NEXT COUPLE HOURS WITH WINDS SHIFTING TO SLY GUSTING AROUND 25 KT AND COULD SEE CIGS LIFT TO MVFR OUTSIDE OF HEAVIER SHOWERS. DISCRETE SUPERCELLS WILL CONTINUE TO IMPACT THE REGION THIS AFTERNOON AND COULD SEE DAMAGING WIND GUSTS AND ISOLATED TORNADOES. A STRONG SQUALL LINE IS THEN EXPECTED TO PUSH THROUGH AROUND 18-22Z THIS AFTERNOON AHEAD OF A COLD FRONT WHICH WILL BRING A CONTINUED THREAT OF DAMAGING WIND GUSTS AND TORNADOES. LONG TERM /THURSDAY THROUGH SUNDAY/... VFR EXPECTED THROUGH FRIDAY AS HIGH PRESSURE MOVES OVER THE AREA HOWEVER GUSTY WEST WINDS WILL PREVAIL OVER THE TERMINALS ON THU. RAIN AND SUB VFR CONDITIONS WILL DEVELOP LATE FRI NIGHT OR EARLY SATURDAY AND PERSIST THROUGH SATURDAY EVENING. ALTHOUGH VFR CONDITIONS SHOULD DEVELOP SATURDAY NIGHT AND SUNDAY STRONG NW WINDS ARE EXPECTED BEHIND A DEPARTING STRONG COASTAL LOW. && .MARINE... SHORT TERM /THROUGH TONIGHT/... AS OF 700 AM WED...WARM FRONT CONTINUING TO APPROACH FROM S WITH WINDS AROUND TO SE AT BUOY 41036 THIS HOUR. FCST ON TRACK WITH GALE FORCE SRLY WINDS EXPECTED TO DEVELOPE THIS AFTN. /PREVIOUS DISCUSSION/ AS OF 400 AM WED...NO SIGNIFICANT CHANGES TO PREVIOUS FCST. E-NE WINDS HAVE INCREASED TO 15-25 KT OVERNIGHT WITH TIGHTENING PRES GRAD IN ADVANCE OF WARM FRONT APPROACHING FROM S AND LOW PRES MOVING INTO ERN TN. AS LOW CONTINUES MOVING NE...WARM FRONT WILL LIFT N OVER AREA THIS MORNING WITH WINDS BECOMING SRLY AND INCREASING TO GALE FORCE IN FREQUENT GUSTS BY EVENING. COLD FRONT WILL MOVE ACROSS AREA THIS EVENING. WINDS WILL BECOME SW-W FOLLOWING FRONTAL PASSAGE BUT REMAIN STRONG AND GUSTY AS LOW PRES MOVES OFF MID ATLC COAST OVERNIGHT. WW3 UNDERDONE WITH SEAS EARLY THIS MORNING DUE TO STRONGER WINDS...AND HAVE ADJUSTED SEAS ACCORDINGLY FOR THIS MORNING. REST OF PERIOD MORE REASONABLE WITH SEAS EXPECTED TO BUILD TO 8-13 FT WITH GALE FORCE WINDS. STRONG WINDS MAY ALSO BRING MINOR COASTAL FLOODING UP TO 2 FT TO THE SOUND SIDE OBX AND LOW WATER ACROSS THE LOWER PORTIONS OF THE NEUSE AND PAMLICO RIVERS BEGINNING LATE TODAY INTO THURSDAY...BUT NOT ENOUGH CONFIDENCE FOR ANY ADVISORIES AS THIS TIME. LONG TERM /THURSDAY THROUGH SUNDAY/... GALE WARNINGS WILL CONTINUE FOR MUCH OF THE MARINE AREA INTO THURSDAY BEHIND THE STRONG COLD FRONT WITH DIMINISHING WINDS LATE THURSDAY AND THURSDAY NIGHT. SEAS WILL BE SUBSIDING DUE TO OFFSHORE WIND TRAJECTORY WITH SEAS FALLING BELOW 6 FT ALL AREAS BY LATE THU NIGHT OR EARLY FRIDAY AS HIGH PRESSURE BRIEFLY BUILDS OVER THE WATERS. THE BENIGN CONDITIONS WILL BE SHORT LIVED THOUGH AS THE NEXT POTENT SHORTWAVE LEADS TO STRONG CYCLOGENESIS OFF THE NC COAST SATURDAY AND SATURDAY EVENING. FOR NOW WILL FORECAST SMALL CRAFT ADVISORY CONDITIONS REDEVELOPING BUT COULD SEE ANOTHER PERIOD OF GALES WITH DOUBLE DIGIT SEA HEIGHTS ESPECIALLY SATURDAY NIGHT INTO SUNDAY. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...WIND ADVISORY UNTIL 4 PM EST THURSDAY FOR NCZ046-047-081-095- 103-104. MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 11 AM EST THURSDAY FOR AMZ135-150. SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR AMZ130. GALE WARNING UNTIL 4 PM EST THURSDAY FOR AMZ152-154. GALE WARNING UNTIL 11 AM EST THURSDAY FOR AMZ156-158. && $$ SYNOPSIS...JBM NEAR TERM...SK SHORT TERM...JBM LONG TERM...BTC/JME AVIATION...JBM/BTC MARINE...JBM/BTC
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
413 PM EST WED DEC 26 2012 .SYNOPSIS... POTENT WINTER STORM WILL RELAX ITS INFLUENCE ON THE OHIO VALLEY THROUGH TONIGHT AND BE REPLACED BY WEAK HIGH PRESSURE ON THURSDAY. NEXT WEAK TROUGH OF LOW PRESSURE WILL MOVE INTO THE AREA FRIDAY NIGHT WITH THE NEXT CHANCE OF SNOW...ALBEIT LIGHT...AND FOCUSED ON AREAS NEAR THE OHIO RIVER. TEMPERATURES OVER THE NEXT FEW DAYS WILL REMAIN SEASONABLY COLD. IN THE LONGER TERM...NO MAJOR WEATHER SYSTEMS ARE ON TAP FOR THE AREA. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... HAVE DOWNGRADED ALL WARNINGS TO ADVISORIES FOR MUCH OF THE AREA AS IMPACTS OF WINTER STORM ARE BEGINNING TO RELAX. HAVE SEEN A SLOW/STEADY DECREASE IN WINDS THROUGH THE AFTERNOON /THOUGH STILL 20-25KTS ACROSS WRN OH/ERN IND/...AND PRIMARY SNOW BAND THAT HAD DEPOSITED 6-9 INCHES OF SNOW FROM SERN IND INTO WCNTL OH HAS LARGELY BROKEN DOWN AND DECREASED IN INTENSITY. LARGER SYNOPTIC BAND OF SNOW ACROSS MICHIGAN INTO NRN IND MAY WRAP E-NE INTO FAR NRN FORECAST AREA THIS EVENING BUT LATEST RAP FORCING /FGEN/ DIAGNOSTICS INDICATE THIS WILL BEGIN TO BREAK DOWN AS WELL. SO OVERALL...EXPECT BROKEN BANDS OF SNOW /MIXED WITH OR JUST PLAIN RAIN ALONG AND SOUTH OF OHIO RIVER/ TO CONTINUE TO PROGRESS E-NE ACROSS THE FORECAST AREA AS TRANSFER OF ENERGY TO DEEPER SFC LOW ALONG THE ERN SEABOARD CONTINUES. STILL SEEING AN OCCASIONAL REPORT OF FZDZ/FZRA/FZRAPL FROM TIME TO TIME...AND GIVEN CRITICAL THERMAL STRUCTURE ON RAP FORECAST SOUNDINGS...SEE NO REASON WHY THIS WON/T CONTINUE NEXT 1-2 HOURS...BEFORE COOLING ALOFT WILL YIELD MORE OF A WIDESPREAD -SN SCENARIO FOR MOST OF THE ADVISORY AREA. DON/T EXPECT MUCH MORE THAN AN ADDITIONAL INCH OF SNOW FOR ANYONE...THOUGH AREAS NORTH/EAST OF COLUMBUS METRO STAND THE BETTER CHANCES FOR PERHAPS A LITTLE MORE THAN AN INCH. ANY BLOWING SNOW SHOULD DIMINISH EARLY TO MID EVENING...AND EXPECT TEMPS TO ONLY FALL BACK INTO THE MID 20S...WHICH SHOULD AID IN ROAD TREATMENTS/IMPROVEMENTS AS THE NIGHT WEARS ON. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... THURSDAY THROUGH FRIDAY ARE LARGELY A QUIET FORECAST...THOUGH RESIDUAL/STUBBORN LOW LEVEL MOISTURE MAY CONTINUE TO YIELD FLURRIES ESPECIALLY IN CNTL OHIO. TEMPERATURES THURSDAY NIGHT A TRICKY POINT...GIVEN FRESH/DEEP SNOW COVER IN WRN/NRN PARTS OF FORECAST AREA. APPRECIABLE CLEARING WILL SEND THOSE TEMPS INTO A NOSEDIVE...AND COULD YIELD A SINGLE DIGIT OR TWO IF CLEARING IS SUBSTANTIAL. NOT GOING THAT CLEAR ON SKY RIGHT NOW - SO HAVE KEPT TEMPS NEAR/JUST BELOW STATISTICAL MOS GUIDANCE. FRIDAY NIGHT A WEAK/POSITIVELY TILTED TROUGH /DISCUSSED BELOW IN .LONG TERM SECTION/ WILL RACE NORTHEAST FROM THE SRN PLAINS...AND INDUCE WEAK SFC LOW DEVELOPMENT IN THE SOUTHEAST. INVERTED TROUGH AND ATTENDANT WEAK FORCING WILL SPREAD NORTHEAST ALONG WITH A RATHER SUBSTANTIAL PLUME OF MOISTURE TO BRING RAIN/SNOW CHANCE BACK INTO THE AREA...ESP NEAR/SOUTH OF THE OHIO RIVER. SIDED WITH 26.12Z ECMWF FORCING AND THERMAL CHARACTERISTICS FOR THIS FORECAST THOUGH ADMITTEDLY 26.12Z GFS NOT TOO FAR OFF. SEE BELOW FOR MORE DETAILS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A BROAD TROUGH OVER THE CENTRAL CONUS WILL SLIDE ACROSS THE OHIO VALLEY ON SATURDAY. THE 26.12Z GFS/EUROPEAN/CANADIAN RUNS HAVE COME INTO PRETTY GOOD AGREEMENT WITH REGARD TO THE TIMING OF THIS FEATURE AND ITS ASSOCIATED MID LEVEL ENERGY AS IT PROGRESSES EASTWARD ACROSS THE AREA. SOME LIGHT SNOW WILL BE POSSIBLE...ESPECIALLY ACROSS THE SOUTHEASTERN CWA. COOLER AIR WILL SETTLE INTO THE REGION FOR THE WEEKEND WITH HIGHS SATURDAY IN THE LOWER TO MIDDLE 30S...HIGHS SUNDAY IN THE MID 20S TO LOWER 30S...AND LOWS BOTH NIGHTS IN THE TEENS TO LOWER 20S. CLOUDS WILL BEGIN TO DECREASE A BIT ON SUNDAY AS HIGH PRESSURE OVER THE LOWER MS VALLEY MOVES NORTHEAST INTO THE REGION. THIS SYSTEM WILL PROVIDE QUIET WEATHER THROUGH MONDAY MORNING. THE GFS AND ECMWF THEN BEGIN TO DIVERGE SIGNIFICANTLY FOR THE REMAINDER OF THE EXTENDED PERIOD...AND GEFS ENSEMBLE CLUSTERS SHOW CONSIDERABLE SPREAD. A COLD FRONT IS PROGGED TO PUSH THROUGH THE AREA LATE MONDAY NIGHT INTO TUESDAY...BRINGING THE NEXT CHANCE FOR SOME PRECIP. FORECAST SOUNDINGS INDICATE THE ONSLAUGHT OF PRECIPITATION MONDAY EVENING MAY BEGIN AS RAIN...SNOW...OR A MIX SOUTH OF THE OHIO RIVER BEFORE COLDER TEMPERATURES CHANGE IT TO LIGHT SNOW. ELSEWHERE... EXPECT JUST CHANCE/SLIGHT CHANCE FOR LIGHT SNOW AT TIMES THROUGH WEDNESDAY. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... CENTER OF LOW IS CURRENTLY SPINNING EASTWARD ACROSS SOUTHERN KENTUCKY. ACROSS OUR AREA AIR ALOFT HAS COOLED SUFFICIENTLY TO ALLOW PRECIPITATION TO FALL PRIMARILY AS ALL SNOW NOW. THE ONLY EXCEPTION APPEARS TO BE LOW LYING AREAS INCLUDING KLUK. THIS LOCATION WILL ALSO SEE A CHANGEOVER TO SNOW BY 20Z. PRECIPITATION WILL BEGIN TO TAPER OFF IN INTENSITY LATER THIS AFTERNOON AND BECOME MORE SHOWERY IN NATURE...ENDING BY AROUND MIDNIGHT. CIGS HAVE FALLEN TO IFR FOR THE MOST PART AND ARE EXPECTED TO REMAIN THAT WAY THROUGHOUT THE NIGHT. AFTER SUNRISE THURSDAY...CIGS WILL STRUGGLE TO RISE ABOVE IFR...ESPECIALLY NORTH TOWARD INTERSTATE 70. HOWEVER THERE MAY BE A WINDOW DURING THE LATE MORNING AND AFTERNOON WHEN MVFR CIGS DO OCCUR. CIGS ARE EXPECTED TO THEN LOWER BACK TO IFR BY THURSDAY EVENING. OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY INTO SATURDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ026- 034-035-042>046-051>056-060>065-070>074-077>080. KY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ089>099. IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ050- 058-059-066-073>075-080. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU SHORT TERM...BINAU LONG TERM...KURZ AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
501 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM BRINGS MIXED PRECIPITATION TODAY INTO THURSDAY. ANOTHER LOW PRESSURE SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING TO SNOW FOR THE END OF THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... ADJUSTED HOURLY TEMPERATURES AND DEWPOINTS TO MATCH LATEST SFC OBS AND THEN USED THE RUC13 THROUGH 8 AM. UPDATED WIND AND WINDS GUSTS PER LATEST SFC OBS AND RADAR SIGNATURE SHOWING GUST UP TO 20 KNOTS AT HTS AND BKW. WINDS COULD INCREASE OVERNIGHT EXCEPT AT PROTECTED VALLEYS...BUT MORE SO ON WEDNESDAY GUSTING AROUND 30 KNOTS ESPECIALLY HIGHER ELEVATIONS. PREVIOUS DISCUSSION BELOW... 900 PM UPDATE... MODEL SOUNDINGS SEEM TO HAMMER THE EASTERN SLOPES OF THE CENTRAL APPALACHIANS WITH ICE...SO HAVE EXPANDED ADVISORIES DOWN THROUGH NICHOLAS...FAYETTE AND RALEIGH COUNTIES...MAINLY FOR THE EASTERN SLOPES THEREOF. FROZEN QPF COULD ACTUALLY EXCEED 0.25 INCH BUT WITH UPDATED TEMPERATURES /WRFARW AND NAM12/ RIGHT AT FREEZING IN THAT AREA...THINKING ADVISORIES OUGHT TO SUFFICE. HAVE ADVISORIES GOING TO 18Z LIKE THOSE FURTHER N BUT HAVE DELAYED ONSET OF ALL WARNINGS AND ADVISORIES UNTIL 06Z OVERNIGHT. ALSO EXTENDED THE PERRY COUNTY WINTER STORM WARNING UNTIL 00Z AS TEMPERATURES THERE MAY NEVER GET ABOVE FREEZING. ALSO DELAYED ONSET OF POPS A BIT PER CURRENT TRENDS AND ALL ASPECTS OF THIS WINTER FORECAST APPEAR TO BE IN GOOD COORD. 700 PM UPDATE... NO SIGNIFICANT CHANGES NEEDED AT THIS TIME. PREV DISCN... GFS STILL THE PREFERRED MODEL OVER THE NAM AT THIS POINT...WHICH IS ALSO THE WARMER OF THE TWO MODELS...ESPECIALLY OFF THE SURFACE. THE KEY TO THE FORECAST THIS AFTERNOON IS THE OVERRUNNING AHEAD OF THE SYSTEM...AND THE WARM LAYER ALOFT OVER SUB FREEZING SURFACE TEMPERATURES WHICH WILL CREATE ICY CONDITIONS. GFS IS AGGRESSIVE WITH THIS...AND WILL SEE AN EXTENDED PERIOD OF FREEZING RAIN WITH SOME ICE PELLETS FOR THE NORTHERN TIER OF COUNTIES IN THE CWA...AND TO MORE OF AN EXTENT WITH THE COLD AIR DAMMING FOR RANDOLPH AND POCAHONTAS COUNTIES ON THE EASTERN SLOPES. THIS WINTRY MIX OF PRECIPITATION WILL BEGIN TONIGHT...TURNING TO MOSTLY RAIN BY WEDNESDAY EVENING...ESPECIALLY FOR THE LOWLAND AREAS. THIS MAY NOT HOLD TRUE FOR THE AFOREMENTIONED NORTHEAST MOUNTAINS AND PERRY AND MORGAN COUNTIES IN SOUTHEAST OHIO WHERE THE COLD AIR AT THE SURFACE HAS A BETTER CHANCE OF HOLDING IN PLACE AS THE FLOW BECOMES MORE NORTHERLY. COLD AIR TO COLLAPSE AS THE COASTAL SURFACE LOW BECOMES THE DOMINANT PLAYER...WHICH WILL ALSO AID IN THE PROCESS OVER SOUTHEAST OHIO. SNOW IS POSSIBLE ON THE NORTHEAST AND NORTHWEST FRINGES OF THE CWA WITH SOME ACCUMULATIONS POSSIBLE AND SHOULD NOT BE OVERLOOKED IN THIS FORECAST. MAY SEE A COATING TO A COUPLE OF INCHES PRIOR TO ONSET OF THE FREEZING RAIN ACROSS THE NORTH...AND NEAR THE END OF THE NEAR TERM LATE WEDNESDAY IN SOUTHEAST OHIO. STRONG LOW LEVEL JET LIKELY TO PRODUCE VERY STRONG SOUTHEAST WINDS OVER THE MOUNTAINS LATE TONIGHT AND WEDNESDAY. RIDGES AND MOUNTAIN TOPS WILL BE MOST LIKELY TO EXPERIENCE THE STRONG WINDS IN THE UPGLIDING NATURE OF THE FLOW AS SEEN ON ISENTROPIC SURFACES. INTERSTATE 77 LIKELY TO BE EXPOSED TO THESE EFFECTS JUST NORTH OF FLAT TOP IN RALEIGH COUNTY. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AT THE OUTSET OF THE PERIOD NWP GUIDANCE IN GOOD AGREEMENT WITH STRONG LOW PRESSURE SYSTEM NEARLY STACKED AND LOCATED ROUGHLY OFF THE DELMARVA/NJ COASTLINE AND MOVING NORTHEASTWARD UP THE COAST AND AWAY FROM THE FORECAST AREA...TAKING MUCH OF THE DEEP LAYER MOISTURE WITH IT AND LARGE SCALE FORCING FOR SUBSIDENCE OVERSPREADING THE AREA. OVERALL NOT MUCH CHANGE WITH REGARD TO EXPECTED POPS IN A GENERAL SENSE FOR THURSDAY BUT DID ELECT TO KEEP SLIGHT CHANCE POPS GOING JUST A BIT LONGER THURSDAY MORNING ACROSS NW ZONES WITH POINT SOUNDINGS AT LOCATIONS SUCH AS PKB STILL INDICATING ROUGHLY 2KFT OF LLVL MOISTURE IN PLACE AT 18Z WITH SOME WEAK WARM ADVECTION NOTED AT 850MB AND BELOW...CAN/T COMPLETELY RULE OUT A LOCATION SQUEEZING OUT A HUNDREDTH THOUGH A TRACE OR HEAVY MIST IS CERTAINLY MORE LIKELY. ALSO ELECTED TO KEEP LIKELY POPS GOING ACROSS THE EASTERN HIGH TERRAIN THROUGH 00Z FRI WITH TRAPPED LLVL MOISTURE IN PLACE WITH AN INCREASING TRAJECTORY OF LLVL FLOW OFF OF LAKE ERIE AS THE DAY PROGRESSES. SOME CONCERN EXISTS WITH PRECIP TYPE...ESPECIALLY DURING THE MORNING HOURS. AS PREV FCST MENTIONED...THERE IS THE POTENTIAL FOR SOME FREEZING DRIZZLE ACROSS THE AREA AS THE COLUMN DRIES FROM ABOVE. BOTH THE LATEST NAM AND GFS DRAG A STOUT DRY LAYER AT -10C ACROSS THE AREA FROM SW TO NE ROUGHLY BTWN 09Z-15Z. MEANWHILE...AGAIN BOTH MODELS AT CRW SHOW ROUGHLY 4KFT OF LLVL MOISTURE DEPTH IN PLACE AT 12Z THU BELOW -10C WITH SFC TEMPS PROGGED TO BE AROUND 30F GIVE OR TAKE. WITH THIS IN MIND...WILL ALLOW SNOW TO STILL BE PRIMARY PRECIP TYPE BUT ALSO INCLUDE A PATCHY FREEZING DRIZZLE MENTION AND LET THE DAYSHIFT REEVALUATE. AND FINALLY...ITS POSSIBLE A WIND ADV MAY BE NEEDED FOR THE EASTERN MOUNTAIN COUNTIES OF RANDOLPH AND POCAHONTAS THURSDAY WITH WINDS SPEEDS RUNNING AROUND THE 25-30KT RANGE. WILL DEFER ANY WIND HIGHLIGHT AT THIS TIME TO THE DAY SHIFT OR TONIGHT/S NIGHT SHIFT WITH THE MULTITUDE OF ONGOING WINTER WX HIGHLIGHTS CURRENTLY IN PLACE. OVERNIGHT THU NIGHT/FRI MORNING THE SYSTEM CONTINUES TO PULL AWAY FROM AREA WITH S/W RIDGING BUILDING OVERHEAD ALONG WITH SFC HIGH PRESSURE. LLVL WIND TRAJECTORY INTO THE NE HIGH TERRAIN GRADUALLY BACKS TOWARD THE WEST AND THUS THE FLOW OFF THE GREAT LAKES WANES...AT WHICH TIME PRECIP IN THE NORTHEAST MOUNTAINS BEGINS TO WIND DOWN. WINDS GO NEAR CALM THOUGH THERE IS SOME WARM ADVECTION FROM THE SOUTHWEST AFTER 06Z. NONETHELESS...A CHILLY NIGHT IS IN STORE PARTICULARLY IN SHELTERED VALLEY LOCATIONS AS WELL AS FAR NW ZONES WHERE FRESH SNOW COVER IS EXPECTED. FRIDAY...GENERALLY PARTLY CLOUDY SKIES CAN BE EXPECTED AS SFC HIGH PRESSURE MOVES OFF TO THE EAST AND FLOW ALOFT TURNS SOUTHWESTERLY. INHERITED MAX TEMPS GENERALLY LOOK GOOD WITH JUST A FEW MINOR TWEAKS. FRIDAY NIGHT AND SATURDAY MORNING THE NEXT SYSTEM QUICKLY MOVES NORTHEASTWARD INTO THE AREA SPREADING RAIN AND SNOW FROM SOUTHWEST TO NORTHEAST MAINLY AFTER 06Z SAT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... USED A BLEND OF THE ECMWF AND ECMWF ENSEMBLE MEAN FOR THE WEEKEND SYSTEM. THIS WOULD HAVE A LOW PASS SOUTH OF THE REGION...PROVIDING A LIGHT SNOW EVENT FOR SATURDAY WITH SOME MIXED PRECIPITATION POSSIBLE IN THE LOW LANDS. BY SUNDAY...COLDER AIR WOULD MOVE IN FOR AN UPSLOPE EVENT. FOR EARLY NEXT WEEK...RELIED ON A GEFS AND ECMWF ENSEMBLE MEAN...BUT NOT HIGH CONFIDENCE. THIS WOULD BRING A WEAK WINTRY SYSTEM THROUGH MONDAY NIGHT/TUESDAY. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... STARTING WITH VFR CONDITIONS AT THE BEGINNING OF THE PERIOD ALL SITES. RADAR IMAGES SHOW THE LEADING EDGE OF PCPN REACHING THE EXTREME SOUTHERN WV BY 05Z. EXPECT GUSTY WINDS INCREASING OVER HIGHER ELEVATIONS AND EXPOSED SITES OVERNIGHT. EKN MAY REMAIN CALM OR LIGHT AND VARIABLE FLOW THROUGH AT LEAST 13Z. TRICKY FORECAST IN TERMS OF PCPN TYPE. DUAL POL MELTING SIGNATURE IS EVIDENT IN THE LEADING EDGE OF PCPN SOUTH OF CRW AND HTS ABOUT 3K FEET AGL. ATTM...A RELATIVELY WARMER AIR MASS WILL ADVECT FROM THE SOUTH INTO A MUCH COLDER AIR NORTH ALONG AND NORTH OF A LINE FROM HTS...CRW...AND BKW. THEREFORE...EXPECT MOST PCPN TO BE LIQUID REACHING HTS...CRW AROUND 08Z. RAIN MIXED WITH ICE PELLETS AT BKW AROUND 08Z...TRANSITIONING TO FREEZING RAIN AROUND 10Z UNDER MVFR CONDITIONS. EXTENDED PERIOD OF FREEZING RAIN AND ICE AT BKW FROM 10-18Z...AND EKN FROM 10-20Z. A FEW HOURS ALSO AT CKB ARE EXPECTED STARTING AROUND 13-19Z. PKB MAY SEE BRIEF ICE AS WELL...BUT MORE LIKELY TO BE RAIN MIXED WITH ICE PELLETS AROUND 22Z BEFORE TRANSITIONING TO ALL SNOW BY 04Z THURSDAY. WIDESPREAD MVFR...AND IFR POSSIBLE AT TIMES LATE OVERNIGHT AND WEDNESDAY. HOWEVER...LOWLANDS ADJACENT TO THE WESTERN SLOPES SHOULD EXPERIENCE VFR CEILINGS IN DOWNSLOPING SOUTHEAST FLOW WEDNESDAY. LOWER VISIBILITIES TO IFR/LIFR AT THE END OF THE PERIOD WITH AREAS OF SNOW. FLOW BECOMES STRONG SOUTHEAST LATE OVERNIGHT AND REMAIN SO WEDNESDAY EAST OF THE OHIO RIVER...AND MODERATE NORTHEAST...ALONG AND WEST OF THE OHIO RIVER DURING THESE TIMES. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF PRECIPITATION TYPE TRANSITION COULD VARY. DURATION AND EXTENT OF ICE COULD VARY. DURATION AND EXTENT OF LOWER CIGS AND VSBYS IN PRECIPITATION COULD ALSO VARY. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE WED 12/26/12 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 CRW CONSISTENCY H H M H M M M L M H H H HTS CONSISTENCY H H H L L L L L L H M M BKW CONSISTENCY L L L L L L L L L L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY H L L L L L L M M M M M CKB CONSISTENCY H H L L L L L L L L L L AFTER 12Z THURSDAY... IFR POSSIBLE IN MIXED PRECIPITATION AND RAIN IN SE OHIO AND THE WV MOUNTAINS WED NIGHT...AND IN SNOW SHOWERS THROUGHOUT THE AREA BUT MORE SO IN THE MOUNTAINS LATE WEDNESDAY NIGHT INTO THURSDAY. IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE MOUNTAINS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR WVZ011-020-031-032-035>040. ICE STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ046-047. OH...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR OHZ067-075-076. WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ066. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/50 NEAR TERM...ARJ SHORT TERM...50 LONG TERM...RPY AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1247 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM BRINGS MIXED PRECIPITATION FROM LATE TONIGHT INTO THURSDAY. ANOTHER LOW PRESSURE SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING TO SNOW FOR THE END OF THE WEEKEND. && .NEAR TERM /UNTIL 10 AM THIS MORNING/... ADJUSTED HOURLY TEMPERATURES AND DEWPOINTS TO MATCH LATEST SFC OBS AND THEN USED THE RUC13 THROUGH 8 AM. UPDATED WIND AND WINDS GUSTS PER LATEST SFC OBS AND RADAR SIGNATURE SHOWING GUST UP TO 20 KNOTS AT HTS AND BKW. WINDS COULD INCREASE OVERNIGHT EXCEPT AT PROTECTED VALLEYS...BUT MORE SO ON WEDNESDAY GUSTING AROUND 30 KNOTS ESPECIALLY HIGHER ELEVATIONS. PREVIOUS DISCUSSION BELOW... 900 PM UPDATE... MODEL SOUNDINGS SEEM TO HAMMER THE EASTERN SLOPES OF THE CENTRAL APPALACHIANS WITH ICE...SO HAVE EXPANDED ADVISORIES DOWN THROUGH NICHOLAS...FAYETTE AND RALEIGH COUNTIES...MAINLY FOR THE EASTERN SLOPES THEREOF. FROZEN QPF COULD ACTUALLY EXCEED 0.25 INCH BUT WITH UPDATED TEMPERATURES /WRFARW AND NAM12/ RIGHT AT FREEZING IN THAT AREA...THINKING ADVISORIES OUGHT TO SUFFICE. HAVE ADVISORIES GOING TO 18Z LIKE THOSE FURTHER N BUT HAVE DELAYED ONSET OF ALL WARNINGS AND ADVISORIES UNTIL 06Z OVERNIGHT. ALSO EXTENDED THE PERRY COUNTY WINTER STORM WARNING UNTIL 00Z AS TEMPERATURES THERE MAY NEVER GET ABOVE FREEZING. ALSO DELAYED ONSET OF POPS A BIT PER CURRENT TRENDS AND ALL ASPECTS OF THIS WINTER FORECAST APPEAR TO BE IN GOOD COORD. 700 PM UPDATE... NO SIGNIFICANT CHANGES NEEDED AT THIS TIME. PREV DISCN... GFS STILL THE PREFERRED MODEL OVER THE NAM AT THIS POINT...WHICH IS ALSO THE WARMER OF THE TWO MODELS...ESPECIALLY OFF THE SURFACE. THE KEY TO THE FORECAST THIS AFTERNOON IS THE OVERRUNNING AHEAD OF THE SYSTEM...AND THE WARM LAYER ALOFT OVER SUB FREEZING SURFACE TEMPERATURES WHICH WILL CREATE ICY CONDITIONS. GFS IS AGGRESSIVE WITH THIS...AND WILL SEE AN EXTENDED PERIOD OF FREEZING RAIN WITH SOME ICE PELLETS FOR THE NORTHERN TIER OF COUNTIES IN THE CWA...AND TO MORE OF AN EXTENT WITH THE COLD AIR DAMMING FOR RANDOLPH AND POCAHONTAS COUNTIES ON THE EASTERN SLOPES. THIS WINTRY MIX OF PRECIPITATION WILL BEGIN TONIGHT...TURNING TO MOSTLY RAIN BY WEDNESDAY EVENING...ESPECIALLY FOR THE LOWLAND AREAS. THIS MAY NOT HOLD TRUE FOR THE AFOREMENTIONED NORTHEAST MOUNTAINS AND PERRY AND MORGAN COUNTIES IN SOUTHEAST OHIO WHERE THE COLD AIR AT THE SURFACE HAS A BETTER CHANCE OF HOLDING IN PLACE AS THE FLOW BECOMES MORE NORTHERLY. COLD AIR TO COLLAPSE AS THE COASTAL SURFACE LOW BECOMES THE DOMINANT PLAYER...WHICH WILL ALSO AID IN THE PROCESS OVER SOUTHEAST OHIO. SNOW IS POSSIBLE ON THE NORTHEAST AND NORTHWEST FRINGES OF THE CWA WITH SOME ACCUMULATIONS POSSIBLE AND SHOULD NOT BE OVERLOOKED IN THIS FORECAST. MAY SEE A COATING TO A COUPLE OF INCHES PRIOR TO ONSET OF THE FREEZING RAIN ACROSS THE NORTH...AND NEAR THE END OF THE NEAR TERM LATE WEDNESDAY IN SOUTHEAST OHIO. STRONG LOW LEVEL JET LIKELY TO PRODUCE VERY STRONG SOUTHEAST WINDS OVER THE MOUNTAINS LATE TONIGHT AND WEDNESDAY. RIDGES AND MOUNTAIN TOPS WILL BE MOST LIKELY TO EXPERIENCE THE STRONG WINDS IN THE UPGLIDING NATURE OF THE FLOW AS SEEN ON ISENTROPIC SURFACES. INTERSTATE 77 LIKELY TO BE EXPOSED TO THESE EFFECTS JUST NORTH OF FLAT TOP IN RALEIGH COUNTY. && .SHORT TERM /10 AM THIS MORNING THROUGH FRIDAY/... SHORT TERM COMMENCES WITH LOW PRESSURE SYSTEM PULLING OFF TO THE EAST...WITH COLDER AIR FILTERING IN BEHIND IT. THIS WILL RESULT IN A GRADUAL CHANGE OVER OF ANY MIXED PRECIPITATION TO SNOW WEDNESDAY NIGHT. HOWEVER...AS THE LOW PULLS AWAY FROM THE AREA...IT TAKES MUCH OF THE MOISTURE WITH IT...THEREBY LIMITING THE POTENTIAL FOR ANY SIGNIFICANT SNOWFALL ACCUMULATIONS ACROSS THE AREA. BEST LOCATION FOR ANY LIGHT SNOWFALL ACCUMULATIONS WILL BE IN THE NORTHERN MOUNTAIN ZONES...IN THE UPSLOPE WNW FLOW ALOFT. COULD EVEN BE A TRANSITION OVER TO DRIZZLE OR FREEZING DRIZZLE TOWARDS THE END OF THE EVENT AS MUCH OF THE MOISTURE IN THE DENDRITE GROWTH ZONE IS LOST WITH TIME. IN ADDITION TO ANY LINGERING WINTRY PRECIPITATION...GUSTY WINDS WILL STILL CONTINUE TO LINGER ACROSS THE HIGHER TERRAIN WEDNESDAY NIGHT FROM STRONG WINDS ALOFT. HIGH PRESSURE WITH GRADUAL CLEARING CONDITIONS WILL THEN BEGIN TO BUILD IN FOR FRIDAY NIGHT. DEPENDING ON THE AMOUNT OF CLEARING...AND SNOW COVER...COULD BE A RATHER CHILLY NIGHT ON TAP...PARTICULARLY ACROSS SOME OF THE SHELTERED MOUNTAIN VALLEYS. THE HIGH PRESSURE WILL REMAIN IN CONTROL FOR FRIDAY...HOWEVER...CLOUDS WILL BE ON THE INCREASE AGAIN FROM THE WEST AS YET ANOTHER STORM SYSTEM APPROACHES. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... USED A BLEND OF THE ECMWF AND ECMWF ENSEMBLE MEAN FOR THE WEEKEND SYSTEM. THIS WOULD HAVE A LOW PASS SOUTH OF THE REGION...PROVIDING A LIGHT SNOW EVENT FOR SATURDAY WITH SOME MIXED PRECIPITATION POSSIBLE IN THE LOW LANDS. BY SUNDAY...COLDER AIR WOULD MOVE IN FOR AN UPSLOPE EVENT. FOR EARLY NEXT WEEK...RELIED ON A GEFS AND ECMWF ENSEMBLE MEAN...BUT NOT HIGH CONFIDENCE. THIS WOULD BRING A WEAK WINTRY SYSTEM THROUGH MONDAY NIGHT/TUESDAY. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... STARTING WITH VFR CONDITIONS AT THE BEGINNING OF THE PERIOD ALL SITES. RADAR IMAGES SHOW THE LEADING EDGE OF PCPN REACHING THE EXTREME SOUTHERN WV BY 05Z. EXPECT GUSTY WINDS INCREASING OVER HIGHER ELEVATIONS AND EXPOSED SITES OVERNIGHT. EKN MAY REMAIN CALM OR LIGHT AND VARIABLE FLOW THROUGH AT LEAST 13Z. TRICKY FORECAST IN TERMS OF PCPN TYPE. DUAL POL MELTING SIGNATURE IS EVIDENT IN THE LEADING EDGE OF PCPN SOUTH OF CRW AND HTS ABOUT 3K FEET AGL. ATTM...A RELATIVELY WARMER AIR MASS WILL ADVECT FROM THE SOUTH INTO A MUCH COLDER AIR NORTH ALONG AND NORTH OF A LINE FROM HTS...CRW...AND BKW. THEREFORE...EXPECT MOST PCPN TO BE LIQUID REACHING HTS...CRW AROUND 08Z. RAIN MIXED WITH ICE PELLETS AT BKW AROUND 08Z...TRANSITIONING TO FREEZING RAIN AROUND 10Z UNDER MVFR CONDITIONS. EXTENDED PERIOD OF FREEZING RAIN AND ICE AT BKW FROM 10-18Z...AND EKN FROM 10-20Z. A FEW HOURS ALSO AT CKB ARE EXPECTED STARTING AROUND 13-19Z. PKB MAY SEE BRIEF ICE AS WELL...BUT MORE LIKELY TO BE RAIN MIXED WITH ICE PELLETS AROUND 22Z BEFORE TRANSITIONING TO ALL SNOW BY 04Z THURSDAY. WIDESPREAD MVFR...AND IFR POSSIBLE AT TIMES LATE OVERNIGHT AND WEDNESDAY. HOWEVER...LOWLANDS ADJACENT TO THE WESTERN SLOPES SHOULD EXPERIENCE VFR CEILINGS IN DOWNSLOPING SOUTHEAST FLOW WEDNESDAY. LOWER VISIBILITIES TO IFR/LIFR AT THE END OF THE PERIOD WITH AREAS OF SNOW. FLOW BECOMES STRONG SOUTHEAST LATE OVERNIGHT AND REMAIN SO WEDNESDAY EAST OF THE OHIO RIVER...AND MODERATE NORTHEAST...ALONG AND WEST OF THE OHIO RIVER DURING THESE TIMES. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF PRECIPITATION TYPE TRANSITION COULD VARY. DURATION AND EXTENT OF ICE COULD VARY. DURATION AND EXTENT OF LOWER CIGS AND VSBYS IN PRECIPITATION COULD ALSO VARY. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE WED 12/26/12 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY H H H H M H H M M L M H HTS CONSISTENCY H H H H H L L L L L L H BKW CONSISTENCY H L L L L L L L L L L L EKN CONSISTENCY H H L L L L L L L L L L PKB CONSISTENCY H H H L L L L L L M M M CKB CONSISTENCY H H H H L L L L L L L L AFTER 06Z THURSDAY... IFR POSSIBLE IN MIXED PRECIPITATION AND RAIN IN SE OHIO AND THE WV MOUNTAINS WED NIGHT...AND IN SNOW SHOWERS THROUGHOUT THE AREA BUT MORE SO IN THE MOUNTAINS LATE WEDNESDAY NIGHT INTO THURSDAY. IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE MOUNTAINS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR WVZ011-020-031-032-035>040. ICE STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ046-047. OH...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR OHZ067-075-076. WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ066. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/RPY/SL/26 NEAR TERM...ARJ/TRM/26 SHORT TERM...SL LONG TERM...RPY AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
441 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON BLENDED QPF AND PTYPE. WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION. THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS REMAINED SNOW AT THE SURFACE. STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES. RAP HAS SHOWN FREEZING RAIN AT TIMES. IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD GET IN THE LOWER 40S IN EASTERN AREAS. WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY. MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS. MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA. LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL DIMINISH THURSDAY EVENING. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE MAIN STORY FOR THE LONG TERM IS COLD...NOT TERRIBLE/ANOMALOUS COLD...BUT SEASONABLY COLD. THE PERIOD WILL START WITH THE EXIT OF THE FIRST REAL STORM OF THE YEAR. GUSTY WEST WINDS SHOULD DECREASE FROM ADVY LEVELS OVER THE SOUTH QUICKLY THURS EVENING/NIGHT. BUT THE WESTERLY FLOW WILL KEEP UPSLOPE SNOW SHOWERS GOING UNTIL THE SFC RIDGE GETS INTO WRN PA. THUS...WILL KEEP SCT/NMRS SHSN THURS NIGHT AND VERY EARLY FRI AM OVER THE WESTERN MTNS. AFTER A BREAK UNDER THE WEAK RIDGE...THE FAST FLOW BUCKLES A LITTLE AND DRAWS A SYSTEM THROUGH ON SAT FROM THE SW. PROGRESSIVE PATTERN WILL KEEP IT MOVING...BUT THERE IS A SMALL CHC THAT IT COULD PHASE WITH A CLIPPER-TYPE SHORT WAVE MOVING ACROSS THE UPPER GREAT LAKES ABOUT THAT SAME TIME. NONE OF THE MODELS REALLY FULLY PHASE THESE SYSTEMS. WHILE THE OUTLIER NAM ZIPS THE SRN SYSTEM BY TO OUR SOUTH AND MAKE LIGHT SNOW ONLY OVER THE LOWER SUSQ...THE GFS/EC/SREF MEANS DO SPREAD PRECIP OVER ALL OF OUR AREA. THIS MEANS THAT IT SHOULD BE A QUICK HITTER AND A 1-2 INCH SNOW FALL IS LIKELY AT THIS POINT IN THE GAME. BRIEF UPPER RIDGE MOVES IN FOR MONDAY...BUT THE FAST FLOW KEEPS IT MOVING. THE MIDDLE OF THE WEEK WILL BE LESS CERTAIN WITH GFS AND ECMWF DIFFERING ON THE UPPER HEIGHT PATTERN OVER THE WHOLE CONUS. THE GFS ALSO OUT OF LINE WITH THE GEFS MEAN...WHICH ALONG WITH THE ECMWF PORTRAY A MEAN TROUGH JUST EAST OF OUR LONGITUDE. THIS SHOULD CREATE A NWRLY FLOW AND GENERALLY COLD AND SNOW SHOWERY TIME FOR THE REST OF THE EXTENDED. A FEW CLIPPERS ARE PROGGED TO RUN THROUGH THE GREAT LAKES FROM UPPER ONTARIO DURING THE MID WEEK. SO WE KEPT POPS HIGH CHC IN THE NW AND LOWER/SLIGHT CHCS IN THE SE. THE COLD AIR WILL KEEP IT ALL SNOW. NO MORE BIG STORMS ON THE HORIZON OF DAY 7. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... WIDESPREAD IFR/LIFR WILL CONTINUE INTO THE EVENING WITH LOCALLY HEAVY SNOW IN CENTRAL AND NORTHERN AREAS...TRANSITIONING TO RAIN/SLEET/FREEZING RAIN OVER SERN AREAS. SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING. KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT. MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE SNOW AND MVFR IFR POSSIBLE SATURDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS. THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY IN N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME WE ARE OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN THAN OTHER PRECIP WOULD BE OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-017>019-024>028-033>035-037-041-042-045-046-049>053- 058. WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026- 033>036-064-065. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...ROSS NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM/ROSS LONG TERM...DANGELO AVIATION...GRUMM/ROSS/LA CORTE HYDROLOGY...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
432 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON BLENDED QPF AND PTYPE. WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION. THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS REMAINED SNOW AT THE SURFACE. STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES. RAP HAS SHOWN FREEZING RAIN AT TIMES. IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD GET IN THE LOWER 40S IN EASTERN AREAS. WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY. MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS. MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA. LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL DIMINISH THURSDAY EVENING. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE MAIN STORY FOR THE LONG TERM IS COLD...NOT TERRIBLE/ANOMALOUS COLD...BUT SEASONABLY COLD. THE PERIOD WILL START WITH THE EXIT OF THE FIRST REAL STORM OF THE YEAR. GUSTY WEST WINDS SHOULD DECREASE FROM ADVY LEVELS OVER THE SOUTH QUICKLY THURS EVENING/NIGHT. BUT THE WESTERLY FLOW WILL KEEP UPSLOPE SNOW SHOWERS GOING UNTIL THE SFC RIDGE GETS INTO WRN PA. THUS...WILL KEEP SCT/NMRS SHSN THURS NIGHT AND VERY EARLY FRI AM OVER THE WESTERN MTNS. AFTER A BREAK UNDER THE WEAK RIDGE...THE FAST FLOW BUCKLES A LITTLE AND DRAWS A SYSTEM THROUGH ON SAT FROM THE SW. PROGRESSIVE PATTERN WILL KEEP IT MOVING...BUT THERE IS A SMALL CHC THAT IT COULD PHASE WITH A CLIPPER-TYPE SHORT WAVE MOVING ACROSS THE UPPER GREAT LAKES ABOUT THAT SAME TIME. NONE OF THE MODELS REALLY FULLY PHASE THESE SYSTEMS. WHILE THE OUTLIER NAM ZIPS THE SRN SYSTEM BY TO OUR SOUTH AND MAKE LIGHT SNOW ONLY OVER THE LOWER SUSQ...THE GFS/EC/SREF MEANS DO SPREAD PRECIP OVER ALL OF OUR AREA. THIS MEANS THAT IT SHOULD BE A QUICK HITTER AND A 1-2 INCH SNOW FALL IS LIKELY AT THIS POINT IN THE GAME. BRIEF UPPER RIDGE MOVES IN FOR MONDAY...BUT THE FAST FLOW KEEPS IT MOVING. THE MIDDLE OF THE WEEK WILL BE LESS CERTAIN WITH GFS AND ECMWF DIFFERING ON THE UPPER HEIGHT PATTERN OVER THE WHOLE CONUS. THE GFS ALSO OUT OF LINE WITH THE GEFS MEAN...WHICH ALONG WITH THE ECMWF PORTRAY A MEAN TROUGH JUST EAST OF OUR LONGITUDE. THIS SHOULD CREATE A NWRLY FLOW AND GENERALLY COLD AND SNOW SHOWERY TIME FOR THE REST OF THE EXTENDED. A FEW CLIPPERS ARE PROGGED TO RUN THROUGH THE GREAT LAKES FROM UPPER ONTARIO DURING THE MID WEEK. SO WE KEPT POPS HIGH CHC IN THE NW AND LOWER/SLIGHT CHCS IN THE SE. THE COLD AIR WILL KEEP IT ALL SNOW. NO MORE BIG STORMS ON THE HORIZON OF DAY 7. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... SNOW IN NORTHERN AND CENTRAL AREAS WILL CONTINUE TO PRODUCE IFR TO LIFR CONDITIONS INTO THIS EVENING. SOME MORE INTENSE SNOW BANDS ARE POSSIBLE. SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING. KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT. MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE SNOW AND MVFR IFR POSSIBLE SATURDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS. THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY IN N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME WE ARE OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN THAN OTHER PRECIP WOULD BE OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-017>019-024>028-033>035-037-041-042-045-046-049>053- 058. WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026- 033>036-064-065. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...ROSS NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM/ROSS LONG TERM...DANGELO AVIATION...GRUMM/ROSS HYDROLOGY...GRUMM/ROSS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
343 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON BLENDED QPF AND PTYPE. WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION. THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS REMAINED SNOW AT THE SURFACE. STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES. RAP HAS SHOWN FREEZING RAIN AT TIMES. IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD GET IN THE LOWER 40S IN EASTERN AREAS. WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY. MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS. MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA. LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL DIMINISH THURSDAY EVENING. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... SNOW IN NORTHERN AND CENTRAL AREAS WILL CONTINUE TO PRODUCE IFR TO LIFR CONDITIONS INTO THIS EVENING. SOME MORE INTENSE SNOW BANDS ARE POSSIBLE. SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING. KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT. MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE SNOW AND MVFR IFR POSSIBLE SATURDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS. THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY IN N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN IS OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-017>019-024>028-033>035-037-041-042-045-046-049>053- 058. WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026- 033>036-064-065. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...ROSS NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM/ROSS LONG TERM...STEINBUGL AVIATION...GRUMM/ROSS HYDROLOGY...GRUMM/ROSS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
337 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON BLENDED QPF AND PTYPE. WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION. THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS REMAINED SNOW AT THE SURFACE. STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES. RAP HAS SHOWN FREEZING RAIN AT TIMES. IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD GET IN THE LOWER 40S IN EASTERN AREAS. WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY. MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS. MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA. LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL DIMINISH THURSDAY EVENING. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV. CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST. WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA EXPECTED THIS AFTERNOON AND EVENING. TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST. 18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO EARLY THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN IS OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-017>019-024>028-033>035-037-041-042-045-046-049>053- 058. WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026- 033>036-064-065. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...ROSS NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM/ROSS LONG TERM...STEINBUGL AVIATION...GRUMM/CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
258 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... SNOW RAPIDLY MOVED FROM SOUTH TO NORTH OVER CENTRAL PA THIS MORNING. STILL HAD NOT REACHED THE NORTHERN TIER COUNTIES AS OF 1 PM BUT SHOULD REACH THE NY BORDER BETWEEN 1 AND 130 PM THIS AFTERNOON. HEAVIEST PRECIPITATION OVER MOST OF THE REGION EXPECTED FROM ABOUT NOW UNTIL 6-8 PM. LOW-LEVEL COLD AIR...IN PART DUE TO EVAPORATIVE COOLING...HAS SNOW. THE MODELS ALL SUGGEST THE SOUTHERN TIER AND THE SOUTHEAST SHOULD MIX WITH ICE PELLETS THIS AFTERNOON AND THEN WITH SOME FREEZING RAIN. WHERE THE 850 HPA WET-BULB ZERO GETS TO THIS EVENING WILL DICTATED SNOWFALL AMOUNTS OVER CENTRAL AREAS. LOTS OF UNCERTAINTY. BUT SOUTHEAST SHOULD MIX WITH FREEZING RAIN AND THEN LANCASTER COUNTY SHOULD GO TO ALL RAIN...MOST OF DAUPHIN AND YORK COUNTIES TOO SHOULD CHANGE TO ALL RAIN. THE ICE PELLETS SHOULD MAKE IT AS FAR NORTH AS ALTOONA-STATE COLLEGE AND WILLIAMSPORT. MUCH NORTH AND WEST OF THERE SHOULD STAY ALL SNOW. FREEZING RAIN SHOULD GET AS FAR WEST AS LEWISTOWN. THE RAP CONTINUES TO SHOW A DRY SLOT COMING IN FROM THE SOUTHWEST THIS EVENING AND AN IMPLIED COMMA HEAD TO BRING MORE SNOW FROM SOUTHWESTERN AREAS...NEAR JOHNSTOWN AROUND 10 PM WHICH MOVES UP THROUGH CLINTON AND NORTHERN LYCOMING COUNTIES BY 5 AM. AHEAD OF THIS FEATURE THE PRECIPITATION COULD TAPER OFF THIS EVENING WITH THE DRY SLOT MOVING INTO SOUTHERN PA AROUND 7-8 PM AND INTO CENTRAL PA AFTER MIDNIGHT. THIS COULD PRODUCE SOME FREEZING DRIZZLE IN SOUTHERN AND EASTERN AREAS WHEN THE SEEDER-FEEDER EFFECT IS LOST. THE COMMA HEAD IN THE 4KM NAM AND 13KM RAP WILL BRING THE SECOND SURGE OF SNOW WHICH WILL NEED TO BE MONITORED OVERNIGHT. TEMPS MAINLY 20S NORTH AND 30S SOUTH AND PERHAPS SOME MID-40S SNEAK INTO LANCASTER COUNTY. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY ISSUED FOR SOUTHERN ZONES. MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS. LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. IN ANY CASE...THIS LOOK LIKE A LIGHT SNOW FOR MOST OF THE CWA. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV. CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST. WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA EXPECTED THIS AFTERNOON AND EVENING. TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST. 18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN IS OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-017>019-024>028-033>035-037-041-042-045-046-049>053- 058. WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026- 033>036-064-065. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...ROSS NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM LONG TERM...STEINBUGL AVIATION...GRUMM/CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1243 PM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... SNOW RAPIDLY MOVED FROM SOUTH TO NORTH OVER CENTRAL PA THIS MORNING. STILL HAD NOT REACHED THE NORTHERN TIER COUNTIES AS OF 1 PM BUT SHOULD REACH THE NY BORDER BETWEEN 1 AND 130 PM THIS AFTERNOON. HEAVIEST PRECIPITATION OVER MOST OF THE REGION EXPECTED FROM ABOUT NOW UNTIL 6-8 PM. LOW-LEVEL COLD AIR...IN PART DUE TO EVAPORATIVE COOLING...HAS SNOW. THE MODELS ALL SUGGEST THE SOUTHERN TIER AND THE SOUTHEAST SHOULD MIX WITH ICE PELLETS THIS AFTERNOON AND THEN WITH SOME FREEZING RAIN. WHERE THE 850 HPA WET-BULB ZERO GETS TO THIS EVENING WILL DICTATED SNOWFALL AMOUNTS OVER CENTRAL AREAS. LOTS OF UNCERTAINTY. BUT SOUTHEAST SHOULD MIX WITH FREEZING RAIN AND THEN LANCASTER COUNTY SHOULD GO TO ALL RAIN...MOST OF DAUPHIN AND YORK COUNTIES TOO SHOULD CHANGE TO ALL RAIN. THE ICE PELLETS SHOULD MAKE IT AS FAR NORTH AS ALTOONA-STATE COLLEGE AND WILLIAMSPORT. MUCH NORTH AND WEST OF THERE SHOULD STAY ALL SNOW. FREEZING RAIN SHOULD GET AS FAR WEST AS LEWISTOWN. THE RAP CONTINUES TO SHOW A DRY SLOT COMING IN FROM THE SOUTHWEST THIS EVENING AND AN IMPLIED COMMA HEAD TO BRING MORE SNOW FROM SOUTHWESTERN AREAS...NEAR JOHNSTOWN AROUND 10 PM WHICH MOVES UP THROUGH CLINTON AND NORTHERN LYCOMING COUNTIES BY 5 AM. AHEAD OF THIS FEATURE THE PRECIPITATION COULD TAPER OFF THIS EVENING WITH THE DRY SLOT MOVING INTO SOUTHERN PA AROUND 7-8 PM AND INTO CENTRAL PA AFTER MIDNIGHT. THIS COULD PRODUCE SOME FREEZING DRIZZLE IN SOUTHERN AND EASTERN AREAS WHEN THE SEEDER-FEEDER EFFECT IS LOST. THE COMMA HEAD IN THE 4KM NAM AND 13KM RAP WILL BRING THE SECOND SURGE OF SNOW WHICH WILL NEED TO BE MONITORED OVERNIGHT. TEMPS MAINLY 20S NORTH AND 30S SOUTH AND PERHAPS SOME MID-40S SNEAK INTO LANCASTER COUNTY. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM. MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO THE EAST. ...OLD DISCUSSION... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV. CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST. WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA EXPECTED THIS AFTERNOON AND EVENING. TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST. 18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS. IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD LEAD TO MINOR FLOODING IN THE SOUTHEAST. AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD IT GET WARMER AND MORE RAIN IS OBSERVED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006- 010>012-037-041-042. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019- 024>028-033>035-045-046-049>053-058. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...GRUMM/ROSS SHORT TERM...GRUMM LONG TERM...STEINBUGL AVIATION...GRUMM/CERU HYDROLOGY...GRUMM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1004 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... 930AM UPDATE TO ADD FREEZING RAIN MENTION SOUTHERN BORDER ZONES PER RECENT REPORTS. A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS. RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF 10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM. THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND NRN TIER ZONES BY LATE MORNING/EARLY AFTN. THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL. COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS. HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS. DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF FZDZ. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV. CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST. WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA EXPECTED THIS AFTERNOON AND EVENING. TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST. 18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT. POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING. ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS IN THE 1-4KFT LEVELS. SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR AT TIMES BEFORE 12Z THURSDAY. IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS. IMPROVING CONDTIONS EXPECTED THURSDAY NIGTH INTO FRIDAY. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR PAZ004>006-010>012-037-041-042. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019- 026>028-045-046-049>053-058. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025- 033>035. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...ROSS/STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...GRUMM/CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
933 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... 930AM UPDATE TO ADD FREEZING RAIN MENTION SOUTHERN BORDER ZONES PER RECENT REPORTS. A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS. RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF 10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM. THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND NRN TIER ZONES BY LATE MORNING/EARLY AFTN. THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL. COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS. HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS. DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF FZDZ. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW ARRIVES IN KJST AROUND 13Z. SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND 16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB. STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED EVE. MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER THROUGH 12Z TOMORROW MORNING. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR PAZ004>006-010>012-037-041-042. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019- 026>028-045-046-049>053-058. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025- 033>035. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...ROSS/STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
910 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... QUICK UPDATE TO BRING LANCASTER AND YORK INTO THE ADVISORY. PRECIP STARTING AS SNOW THERE AND EXPECT SOME ACCUMULATIONS BEFORE CHANGEOVER OCCURS. A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS. RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF 10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM. THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND NRN TIER ZONES BY LATE MORNING/EARLY AFTN. THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL. COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS. HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS. DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF FZDZ. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW ARRIVES IN KJST AROUND 13Z. SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND 16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB. STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED EVE. MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER THROUGH 12Z TOMORROW MORNING. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR PAZ004>006-010>012-037-041-042. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019- 026>028-045-046-049>053-058. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025- 033>035. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...ROSS/STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
758 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS. RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF 10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM. THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND NRN TIER ZONES BY LATE MORNING/EARLY AFTN. THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL. COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS. HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS. DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF FZDZ. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW ARRIVES IN KJST AROUND 13Z. SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND 16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB. STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED EVE. MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER THROUGH 12Z TOMORROW MORNING. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR PAZ004>006-010>012-037-041-042. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019- 026>028-045-046-049>053-058. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025- 033>035. WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...CERU HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
648 AM EST WED DEC 26 2012 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID-ATLANTIC COAST. && .NEAR TERM /THROUGH TONIGHT/... A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS. RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF 10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM. THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND NRN TIER ZONES BY LATE MORNING/EARLY AFTN. THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL. COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS. HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS. DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA ...MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF FZDZ. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW 00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS ON DAY 4/SAT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF AVAILABLE GUID. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... GENERALLY MVFR CIGS ACROSS CENTRAL PA OVERNIGHT AS FLOW TURNS EASTERLY...KEEPING STRATOCU TRAPPED IN INVERSION AROUND EDGES OF RETREATING HIGH PRESSURE AREA. AS SIGNIFICANT WINTER STORM APPROACHES FROM THE SW FOR WED...CIGS MAY SLIP TO VFR FOR A COUPLE OF HOURS BEFORE ONSET OF PRECIP /10Z-16Z/. BUT CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW ARRIVES IN KJST AROUND 11Z...KBFD-KUNV-KMDT AROUND 14-16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB. AS LAYER OF WARMER AIR TRIES TO WORK IN FROM THE SOUTH WED AFT/EVE...ICING WILL BECOME A CONCERN. A WINTRY MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED EVE. HEAVY PRECIP BEGINS TO END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER. OUTLOOK... WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS. THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W. FRI...NO SIG WX EXPECTED. SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE STATEWIDE. && .HYDROLOGY... MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR PAZ004>006-010>012-037-041-042. WINTER STORM WARNING FROM 10 AM THIS MORNING TO 7 AM EST THURSDAY FOR PAZ017>019-026>028-045-046-049>053-058. WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025- 033>035. WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 7 AM EST THURSDAY FOR PAZ036-056-057-059-063-064. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...CERU HYDROLOGY...STEINBUGL
AREA FORECAST DISCUSSION
NWS SPOKANE WA
949 PM PST Tue Dec 25 2012 .SYNOPSIS... Another storm system will spread steady light snow across the region tonight, before dissipating into snow showers through Wednesday night. Drier, colder conditions arrive for the end of the work week. While minor amounts of snow can be expected from time to time...there are no major storm systems expected for the next week. && .DISCUSSION... Update: The winter weather advisories for the Wenatchee area and Waterville Plateau, and the East Slopes of the North Washington Cascades have been cancelled. Water vapor satellite imagery shows a stretching frontal band over Eastern Washington as an upper trough along the Washington and Oregon coast continues to dive south. Latest 00z models as well as the HRRR shows just occasional rounds of very light snow over North Central Washington tonight and thus the threat for additional snow accumulations of over an inch has ended. As the stretching frontal band continued to move east into North Idaho tonight light snow will develop in places like Sandpoint, Coeur D`Alene, and Kellogg but accumulations will be very light. For the Lewiston area southwest downslope winds off the Blues will limit precipitation chances so pops were lowered in this area. With abundant low level moisture and high dew points in the upper 20s and lower 30s tonight stratus will be widespread which will limit temperature falls. Lows were increased slightly for most of the area. JW && .AVIATION... 06Z TAFS: An area of light snow associated with a weak front over Northeast Washington and North Idaho will continue to move east and weaken through 09. Meanwhile another wave over Central Oregon will move northeast towards KPUW/KLWS overnight and Wednesday morning. This weak feature in combination with a wind reversal to more favorable low level upslope west-northwest direction will likely bring lowering CIGS at KPUW and KLWS with an increasing chance for -SN especially KPUW. Elsewhere a deep and saturated boundary layer will promote a mix of IFR and MVFR stratus across the entire region through 6z Thursday. JW && .PRELIMINARY POINT TEMPS/POPS... Spokane 26 31 25 33 24 33 / 80 60 40 20 10 10 Coeur d`Alene 26 32 27 34 25 35 / 60 60 40 20 10 10 Pullman 29 33 29 34 27 34 / 80 60 60 40 20 10 Lewiston 33 39 31 41 30 41 / 50 50 50 30 20 10 Colville 26 31 25 33 25 34 / 50 50 30 20 10 10 Sandpoint 25 30 27 33 26 32 / 60 50 30 30 10 10 Kellogg 24 32 26 30 24 31 / 70 70 50 40 20 10 Moses Lake 26 32 25 35 25 37 / 80 40 20 10 0 10 Wenatchee 25 31 24 34 25 35 / 60 40 20 10 0 10 Omak 23 29 20 29 22 31 / 60 40 20 10 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
808 PM PST Tue Dec 25 2012 .SYNOPSIS... Another storm system will spread steady light snow across the region tonight, before dissipating into snow showers through Wednesday night. Drier, colder conditions arrive for the end of the work week. While minor amounts of snow can be expected from time to time...there are no major storm systems expected for the next week. && .DISCUSSION... Update: The winter weather advisories for the Wenatchee area and Waterville Plateau, and the East Slopes of the North Washington Cascades have been cancelled. Water vapor satellite imagery shows a stretching frontal band over Eastern Washington as an upper trough along the Washington and Oregon coast continues to dive south. Latest 00z models as well as the HRRR shows just occasional rounds of very light snow over North Central Washington tonight and thus the threat for additional snow accumulations of over an inch has ended. As the stretching frontal band continued to move east into North Idaho tonight light snow will develop in places like Sandpoint, Coeur D`Alene, and Kellogg but accumulations will be very light. For the Lewiston area southwest downslope winds off the Blues will limit precipitation chances so pops were lowered in this area. With abundant low level moisture and high dew points in the upper 20s and lower 30s tonight stratus will be widespread which will limit temperature falls. Lows were increased slightly for most of the area. JW && .AVIATION... 00Z TAFS: An occluded front over the Cascades at 00Z Wednesday will track through eastern Washington tonight. A 4 to 6 hour period of SN with likely IFR ceilings and Vis will occur at most TAF sites as this front approaches and passes. With a light surface pressure gradient...post frontal FG and IFR Stratus ceilings will be probable at the KEAT...KMWH and KGEG area TAF sites through 18Z Wednesday. KLWS and KPUW will experience periods of snow tonight...but should display significantly improving conditions after FROPA. After 18Z Wednesday and through 00Z Thursday...moist boundary layer air mass will promote continued widespread MVFR ceilings at most TAF sites./MJF && .PRELIMINARY POINT TEMPS/POPS... Spokane 26 31 25 33 24 33 / 80 60 40 20 10 10 Coeur d`Alene 26 32 27 34 25 35 / 60 60 40 20 10 10 Pullman 29 33 29 34 27 34 / 80 60 60 40 20 10 Lewiston 33 39 31 41 30 41 / 50 50 50 30 20 10 Colville 26 31 25 33 25 34 / 50 50 30 20 10 10 Sandpoint 25 30 27 33 26 32 / 60 50 30 30 10 10 Kellogg 24 32 26 30 24 31 / 70 70 50 40 20 10 Moses Lake 26 32 25 35 25 37 / 80 40 20 10 0 10 Wenatchee 25 31 24 34 25 35 / 60 40 20 10 0 10 Omak 23 29 20 29 22 31 / 60 40 20 10 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1037 PM CST TUE DEC 25 2012 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .UPDATE...TEMPS FALLING OFF THE CLIFF THIS EVENING SO LOWERED MINS TONIGHT BEFORE HIGH LEVEL CLOUDS FILTER NORTHWARD. RADAR SHOWS A BAND OF LAKE EFFECT SNOW SHOWERS WORKING INTO MANITOWOC COUNTY. CLOUD TOPS ONLY AROUND 5 K TO MID LAKE WITH THIS BAND SO LIKELY ONLY FLURRIES OR LIGHT SNOW SHOWERS AT THIS TIME. TDH && .PREV DISCUSSION...ISSUED AT 524 PM CST TUE DEC 25 2012... SHORT TERM...TONIGHT AND WEDNESDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT PLAINS AND NOSING ACROSS THE WESTERN GREAT LAKES. CLOUDS AND FLURRIES HAVE RETREATED NORTH OF THE UPPER PENINSULA BORDER EARLY THIS AFTERNOON AND ARE NO LONGER IMPACTING N-C WISCONSIN. MEANWHILE...LIGHT NE LOW LEVEL FLOW HAS ALREADY STARTED TO DEVELOP OVER NORTHEAST WISCONSIN AND LAKE CLOUDS ARE ALREADY PUSHING ACROSS THE FOX VALLEY. SNOW FLURRIES ARE SHOWING UP ON RADAR JUST OFFSHORE THE KEWAUNEE COAST...AND EVEN WHAT LOOKS LIKE A MID-LAKE BAND HAS BEEN MOVING EAST OVER CENTRAL LAKE MICHIGAN. AS DEEPER AND STRONGER NE FLOW DEVELOPS LATER TONIGHT AND WEDNESDAY...LAKE EFFECT SNOW CHANCES AND AMOUNTS ARE THE MAIN FORECAST CONCERNS. TONIGHT...SURFACE HIGH PRESSURE RIDGE AXIS WILL BE EXTENDING ACROSS NORTHERN WISCONSIN AND LAKE MICHIGAN AT THE START OF THE EVENING...BUT WILL SHIFT NORTHWARD THROUGH THE NIGHT. AS STRONG LOW PRESSURE MOVES OVER THE SOUTHERN OHIO VALLEY...WIND DIRECTION WILL BECOME NORTHEASTERLY FROM THE SURFACE UP TO 700MB. 12Z GRB SOUNDING WAS PRETTY DRY ABOVE 900MB THIS MORNING...BUT ONCE THE NE FLOW BECOMES ESTABLISHED...OUR AIR WILL BE COMING FROM NORTHERN LAKE MICHIGAN WHERE THE 12Z APX SOUNDING WAS CONSIDERABLY MORE SATURATED...UP TO 825MB. SINCE AMPLE CLOUD COVER ALREADY EXISTS OVER NORTHERN LAKE MICHIGAN...AND SHOWING NO SIGNS OF DISSIPATING...SEE NO REASON WHY THE LAKE CLOUDS COULD NOT CONTINUE TO PUSH ACROSS THE WESTERN FOX VALLEY AND POSSIBLY EXPAND INTO CENTRAL WISCONSIN. LAKE EFFECT SNOW POTENTIAL WILL IMPROVE THROUGH THE NIGHT WHEN 1000-850MB FLOW STRENGTHENS TO 15 KTS. COMBINED WITH LENGTHENING FETCHES AND DELTA T/S AROUND 16C...LAKE EFFECT SNOW SHOWERS LOOK LIKELY LATE TONIGHT OVER E-C AND NE WISCONSIN. THINK IT WILL TAKE AWHILE FOR THE MULTIPLE BANDS TO DEVELOP WITH WINDS LIGHT THIS EVENING. SO WILL SHOW ACCUMS UP TO AN INCH OVER E-C WISCONSIN...MAINLY AFTER MIDNIGHT. ELSEWHERE...CIRRUS WILL INCREASE FROM THE SW AFTER MIDNIGHT AHEAD OF A NORTHERN STREAM SHORTWAVE. LOWS SLIGHTLY BELOW ZERO OVER N-C WISCONSIN...TO THE UPPER TEENS NEAR LAKE MICHIGAN. WEDNESDAY...NORTHEAST FLOW WILL CONTINUE UNABATED FOR THE ENTIRE DAY. WITH A CIRRUS SHIELD OVERHEAD...DELTA T/S WILL REMAIN AROUND 15C WITH GREAT FETCH LENGTHS AND 1000-850MB WINDS BETWEEN 15-20KTS. IN ADDITION...AN INCOMING SHORTWAVE TROUGH WILL LIFT INVERSION HEIGHTS TO NEAR 800MB (PROBABLY UNDERESTIMATED DUE TO LAKE MICHIGAN MODIFICATIONS) AND CREATE LARGE-SCALE ASCENT...WHICH WILL SUBTLY IMPROVE LES POTENTIAL. WENT A LITTLE MORE BULLISH WILL SNOWFALL POTENTIAL DUE TO THESE FACTORS...AND WILL SHOW 1-2 INCHES IN THE FORECAST. AM CONCERNED THAT THE LONG FETCH LENGTHS AND A PERSISTENT WIND DIRECTION WILL LEAD TO HIGHER AMOUNTS SINCE THIS COULD LEAD TO ORGANIZED BANDING. ELSEWHERE...PLENTY OF CIRRUS OVERHEAD WILL CREATE TO PARTLY SUNNY TO MOSTLY CLOUDY CONDITIONS. HIGHS MAINLY IN THE LOW TO MID 20S. LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY. LAKE EFFECT SNOW SHOWERS WILL BE DIMINISHING EARLY IN THE PERIOD AS LOW-LEVEL WINDS BACK AND SURFACE HIGH PRESSURE MOVES IN. PACIFIC ENERGY MOVES ON SHORE WED AND QUICKLY MOVES INTO MIDWEST BY LATE IN WEEK. ASSOCIATED SHORTWAVE TROF AND SURFACE WAVE MOVE ACROSS REGION ON FRIDAY. ENOUGH MOISTURE ASSOCIATED WITH SYSTEM TO PRODUCE LIGHT COATING OF SNOW ACROSS AT LEAST THE SOUTHERN THIRD OR SO OF FORECAST AREA. SEASONAL TEMPS DURING PERIOD AS ARCTIC AIR...FOR THE MOST PART... REMAINS BOTTLE UP IN CANADA...NORTH AND NORTHEAST OF WI. && .AVIATION...VFR CONDITIONS EXPECTED TONIGHT INTO WEDNESDAY OVER NORTH CENTRAL AND MUCH OF CENTRAL WISCONSIN. PATCHY MVFR CIGS DUE TO A FLOW OFF LAKE MICHIGAN WILL BECOMING MORE WIDESPREAD BY WEDNESDAY AS COLD AIR ON NORTHEAST WINDS INCREASE. PATCHY MVFR CIGS FROM LAKE SUPERIOR ORIGIN MAY ALSO WORK INTO PARTS OF NORTH CENTRAL WISCONSIN LATER TONIGHT INTO WEDNESDAY. SCATTERED MVFR VSBYS DUE TO SNOW SHOWERS LIKELY OVER EAST CENTRAL WISCONSIN AND ESPECIALLY ALONG THE LAKE MICHIGAN SHORELINE. TDH && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1215 AM MST FRI DEC 28 2012 .UPDATE... ISSUED AT 945 PM MST THU DEC 27 2012 MOSTLY LIGHT SNOW CONTINUES TO FALL OVER THE REGION FOR ONE MORE NIGHT AND INTO FRIDAY BEFORE THIS STORM CYCLE COMES TO AN END. CHECKING SNOTEL SITES AT 8 PM THE NORTHERN AND SOUTHERN MTNS HAVE BOTH RECEIVED GENERALLY 6-8 INCHES WITHIN THE LAST 24 HOURS. THERE WERE SOME BIG OUTLIERS IN THE NORTHERN MTNS: RIPPLE CREEK IN THE FLATTOPS 15 INCHES...TOWER SITE NEAR STEAMBOAT MTN 17 INCHES. THE CENTRAL MTNS HAVE RECEIVED LESS...MORE LIKE 4-6 INCHES. LIGHT SNOWFALL ALL DAY AT POWDERHORN...OBSERVED BY SKIING FORECASTERS... DID NOT YIELD MUCH ACCUMULATION. AT THE RADAR TRANSMITTER ON THE GRAND MESA VAD WINDS SHOW A STRONG VEERING FROM WEST TO NNW BEGINNING AT 00Z. SATELLITE AND MODELS INDICATE THIS BOUNDARY IS INTO THE SAN JUANS AT 9 PM AND WILL PUSH INTO NEW MEXICO BEFORE MIDNIGHT. THIS WILL SHIFT SNOW ACCUMULATION EMPHASIS TO NORTH-FACING SLOPES. HIGHLIGHTS FOR NORTHERN VALLEYS AND UTAH MOUNTAINS END AT MIDNIGHT. THE FLY IN THAT SCENARIO IS A WEAK WAVE WORKING INTO NE UTAH AROUND MIDNIGHT AND PASSING ACROSS NW COLORADO THROUGH 6 AM. THE 00Z NAM AND 03Z RAP SHOW ONLY LIGHT ACCUMULATIONS WITH THIS WAVE AND THE SLC OFFICE CONFIRMS THE WAVE HAS ONLY BEEN PRODUCING LIGHT SNOWFALL IN SE IDAHO-NORTHERN UTAH. SO WILL LET THOSE HIGHLIGHTS EXPIRE AT MIDNIGHT BUT KEEP HIGH POPS AND LOW ACCUMULATIONS ACROSS THE NORTH. OTHERWISE THE EVENING MODELS ARE PRODUCING ONLY LIGHT ACCUMULATIONS OF A FEW INCHES ON FRIDAY FOR THE NORTH SLOPES OF THE COLORADO MTNS. FAVORABLE OROGRAPHICS ARE IN PLACE BUT MOISTURE IS LACKING IN THIS NEW AIR MASS. COLD AIR BEGINS TO MODIFY ON THE MTN SLOPES ON SATURDAY AS HIGH PRESSURE BUILDS IN. THE VALLEYS WILL BE STRONGLY CAPPED. THE NEXT CHANCE OF SNOW IS STILL TIMED FOR SUNDAY AFTERNOON THROUGH MONDAY EVENING TO PRODUCE A WHITE NEW YEAR TO MATCH THE WHITE CHRISTMAS PAST. && UPDATE ISSUED AT 600 PM MST THU DEC 27 2012 SATELLITE INFRARED SHOWING A RIBBON OF COOLING CLOUD TOPS FROM THE BOOKCLIFFS TO NERN COLORADO. THIS AREA OF COOLING CLOUD TOP MARKS THE DISORGANIZED TROUGH AXIS THAT IS CURRENTLY MOVING SOUTHEAST ACROSS THE STATE. A BROAD AREA OF LIGHT SNOW IS FALLING BENEATH THIS CLOUD MASS AND HAVE UPDATED FORECAST GRIDS TO REFLECT THIS. BUT AS THE EVENING PROGRESSES...THE WESTERN PART OF THE TROUGH AXIS BECOMES MORE DISORGANIZED EVEN MORE SO TOWARD MIDNIGHT. EXPECT THE SNOW TO DIMINISH LATE EVENING AFTER THIS "BURST" OF EVENING SNOW. SPECIFIC HUMIDITY VALUES ARE LOW AND THEREFORE ANY ACCUMULATIONS WILL BE ON THE LIGHT SIDE. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 257 PM MST THU DEC 27 2012 A COLD UPPER TROUGH WAS SLOWLY SWINGING ACROSS THE FORECAST AREA THIS AFTERNOON. A DEFORMATION/SHEAR AXIS NEAR THE SRN WY BORDER AT MIDDAY TRAILED AN UPPER LOW EJECTING OUT ACROSS SD/NE. THIS AXIS WAS WEAKENING PER WARMING CLOUD TOPS AND SHOULD CONTINUE TO DO SO AS IT ROTATES SOUTHEAST ACROSS WRN CO. THE DEFORMATION AXIS AND WEAK NW OROGRAPHIC FLOW KEPT LIGHT SNOW ACROSS THE NORTH THROUGH MIDDAY...WITH THE LIGHT SNOW EXPANDING ACROSS THE CENTRAL THE SOUTHERN MOUNTAINS THIS AFTERNOON AND TONIGHT AS THE ENTIRE COLD TROUGH EVENTUALLY ROTATES THROUGH. THE ACTUAL AMOUNT OF MOISTURE AMOUNT IN THE AIR IS LIMITED...BUT WITH THE AIR MASS SO MOIST IT SHOULD NOT TAKE MUCH TO SQUEEZE OUT SOME SNOW. SNOW TO WATER RATIO OF ABOUT 20:1 WAS OBSERVED ACROSS THE NORTH THIS MORNING. WITH ANOTHER ANOTHER 1-3 INCHES OF ACCUMULATION FORECAST IN THE MTNS TONIGHT FROM PERIODS OF SNOW...WILL CONTINUE WITH THE CURRENT WINTER WEATHER ADVISORIES AND LET THE EVENING SHIFT RE-EVALUATE FOR ANY EARLY CANCELLATIONS. WEST AND NORTH FACING SLOPES WILL BE THE FAVORED AREAS TONIGHT. OUTSIDE OF THE NW CO PLATEAU... SCATTERED SNOW SHOWERS WILL PERSIST IN THE VALLEYS BUT WITH LITTLE ACCUMULATION. WILL INCLUDE A MENTION OF FOG IN MOST VALLEYS TONIGHT AS WELL. LIGHT SNOW WILL DIMINISH ACROSS THE CENTRAL AND SOUTHERN MTNS EARLY FRIDAY MORNING...WHILE NW FLOW AND A FINAL EMBEDDED WAVE MAY KEEP SOME LIGHT SNOW ACROSS THE NRN MTNS INTO EARLY AFTERNOON. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 257 PM MST THU DEC 27 2012 LOOK FOR A QUIETER WEATHER PATTERN THROUGH THE END OF THE WEEK AS A SHORTWAVE RIDGE PASSES OVER THE AREA FRI NIGHT INTO SAT. EXPECT VERY COLD NIGHTTIME LOWS FRI NIGHT AS VALLEY INVERSIONS STRENGTHEN UNDER MOSTLY CLEAR SKIES. BELOW NORMAL TEMPS WILL FOLLOW ON SAT AS COLD AIR REMAINS TRAPPED IN THESE VALLEYS. HOWEVER TEMPS WILL APPROACH NORMAL VALUES IN THE MOUNTAINS...ABOVE THE INVERSIONS. AS THE SHORTWAVE RIDGE PASSES OVER OUR FORECAST AREA EARLY IN THE PERIOD...A LONG WAVE TROUGH WILL DEVELOP ALONG THE WEST COAST. THE MID RANGE MODELS HAVE BEEN IN DISAGREEMENT IN THE HANDLING OF THIS SPLITTING TROUGH AS IT TRACKS EAST. HOWEVER THE 12Z ECMWF HAS TRENDED MORE TOWARDS THE GFS SOLUTION. THEREFORE THERE IS A LITTLE MORE CONFIDENCE THAT THE SOUTHERN BRANCH WILL PHASE WITH ENERGY DROPPING OUT OF THE NORTHWEST AND INTO THE GREAT BASIN ON SUNDAY. THIS SOLUTION BRINGS THE TROUGH ACROSS OUR AREA SUN NIGHT-MON...WITH THE SOUTHERN HALF FAVORED DUE TO THE ENERGETIC SOUTHERN BRANCH. FOR THIS PACKAGE...HAVE STILL KEPT POPS ON THE LOW SIDE DUE TO CONTINUED UNCERTAINTY. BEYOND MON...MODEL AGREEMENT DECREASES. WE DO STAY IN NORTH-NORTHWEST FLOW AS ADDITIONAL ENERGY DROPS INTO THE MEAN TROUGH THROUGH LATE TUE. THE ECMWF AND CANADIAN SHOW A LOW SPLITTING TO THE SOUTHWEST. THE EC PUTS IT OVER THE 4-CORNERS EARLY TUE...WITH THE CANADIAN OVER THE AZ/UT/NV TRIPLE POINT. BY EARLY WED BOTH SOLUTIONS SHOW THIS SPLIT-OFF LOW OVER SOUTHERN AZ...WITH OUR FORECAST AREA BETWEEN THE LOW AND A NORTHERN BRANCH TROUGH. THE GFS SOLUTION IS MUCH LESS SPLIT...WITH A LESS AMPLIFIED NORTHERN BRANCH AS WELL. THESE PERIODS WILL GENERALLY BE ON THE DRY SIDE. HOWEVER CONFIDENCE IS LOW. THIS LACK OF CONFIDENCE FOLLOWS FOR THU AS THE MID RANGE MODELS CONTINUE TO HAVE PROBLEMS IN A GENERALLY ACTIVE AND COMPLICATED LARGE SCALE PATTERN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 945 PM MST THU DEC 27 2012 SNOWFALL WILL CONTINUE TO RESULT IN WIDESPREAD MOUNTAIN OBSCURATIONS THROUGH TONIGHT. THE EXCEPTION WILL BE OVER THE EASTERN UT MOUNTAINS WHICH SHOULD BEGIN TO SEE IMPROVING CONDITIONS AFTER 10Z. SNOWFALL WILL CONTINUE TO PRODUCE AREAS OF MOUNTAIN OBSCURATION IN THE HIGHER COLORADO MOUNTAINS THROUGH FRI MORNING...WITH CONDITIONS IMPROVING IN THE AFTERNOON. IN THE VALLEY AREAS...SNOW WILL CONTINUE TO DIMINISH THIS EVENING. HOWEVER THE NORTHWEST PLATEAU THROUGH THE STEAMBOAT SPRINGS AREA WILL HOLD ON TO SNOWFALL THROUGH 12Z. THEREFORE AT TIMES MVFR OR EVEN ISOLATED IFR CONDITIONS WILL DEVELOP IN SNOW AT THE NORTHWEST CO AND HIGHER ELEVATION AIRPORTS THROUGH THIS EVENING. THEN BEGINNING AROUND MIDNIGHT PATCHY FOG WILL FORM IN MOST VALLEYS. ALL AIRPORTS MAY SEE PERIODS OF MVFR CIGS/VSBYS...WITH BRIEF PERIODS OF IFR POSSIBLE AS A RESULT. CONDITIONS WILL BEGIN TO IMPROVE BY MID MORNING ON FRI. HOWEVER FOG MAY PERSIST IN SOME PRONE LOCATIONS THROUGHOUT THE MORNING...AND THE EASTERN UINTA BASIN MAY SEE AREAS OF MVFR VSBYS IN BR THROUGH THE AFTERNOON. OTHERWISE VFR CONDITIONS ARE EXPECTED AT THE TAF SITES BY NOON. SOME MTN OBSCURATION WILL CONTINUE OVER THE MTNS FROM KSBS SOUTH TO KEGE INCLUDING RABBIT EARS AND VAIL PASSES THROUGH 21Z FRIDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 6 AM MST EARLY THIS MORNING FOR COZ003-004-009-010-012-013-017>019. UT...NONE. && $$ UPDATE...JOE SHORT TERM...JAD LONG TERM...EH AVIATION...EH+JOE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1000 PM MST THU DEC 27 2012 .AVIATION...MAIN CONCERN CONTINUES TO BE LOW CIGS AND VIS ASSOCIATED WITH -SN THIS EVENING AND OVERNIGHT. KCOS REMAINS IFR AND WILL LIKELY TO REMAIN IFR THROUGH 09-12Z. CIGS MAY BRIEFLY FALL TO LIFR DURING THE EARLY MORNING HOURS. WILL SEE GRADUAL LIFTING OF CIGS BY SUNRISE AND SHOULD RETURN TO VFR BY 13-15Z. SOME MVFR CONDITIONS POSSIBLE AT KPUB BUT PRECIP SHOULD STAY MAINLY AWAY FROM THE TERMINAL SO HAVE IMPROVED CONDITIONS FOR THE KPUB TAF THIS MORN. KALS ALSO A BIT TRICKY THIS MORN...WITH THE POTENTIAL FOR PC FG OR BR GIVEN THE MOIST SURFACE AND LIGHT WINDS. CONDITIONS SOMEWHAT FAVORABLE FOR THIS THROUGH 12-14Z SO WILL RETAIN MENTION OF REDUCED VIS FOR THIS TIME...HOWEVER THERE IS STILL THE POSSIBILITY THAT KALS COULD REMAIN VFR. CONDITIONS AT ALL SITES WILL IMPROVE IN THE MORNING...AND WILL SEE GENERALLY CLEAR CONDITIONS BY AFTERNOON AND EV ON FRI. ROSE && .PREV DISCUSSION... /ISSUED 303 PM MST THU DEC 27 2012/ SHORT TERM... (TONIGHT AND FRIDAY) TRAILING TROF ACROSS THE GREAT BASIN/NRN U.S. ROCKIES WILL SHIFT SOUTHEASTWARD ACROSS CO TONIGHT WITH ANOTHER LOBE OF ENERGY WITHIN THE TRAILING TROF MOVING ACROSS THE REGION DURING THE EVENING HOURS. SFC HIGH WILL CONTINUE TO SINK SOUTHWARD ACROSS THE PLAINS WITH SHALLOW EASTERLY UPSLOPE FLOW DEVELOPING ACROSS EL PASO COUNTY. ALTHOUGH FORCING ALOFT IS NOT TERRIBLY STRONG...12Z MODEL RUNS DEEPLY SATURATE THE ATMOS FAIRLY QUICKLY THIS AFTERNOON AS MOISTURE MOVES IN FROM THE NW AND UPSLOPE HELPS SATURATE THE LOW LEVELS. GFS...NAM12...RAP13...AND SREF ALL SPREAD LIGHT SNOW EASTWARD ACROSS NRN SECTIONS OF THE SE MTNS/PLAINS THIS EVENING...NAMELY THE PIKES PEAK REGION. THERE IS SOME INSTABILITY TO WORK WITH AS WELL ESPECIALLY THIS AFTERNOON/EARLY EVENING. SO AS WEAK FORCING MOVES IN AND SHALLOW UPSLOPE DEVELOPS...EXPECT -SHSN BANDS TO BREAK OUT ACROSS PIKES PEAK AND EL PASO COUNTY DURING THE LATE AFTN/EARLY EVENING AND STREAK OFF TO THE SOUTHEAST. COULD SEE LOCAL SNOW ACCUMS OF AN INCH OR TWO FROM SOME OF THESE BANDS...AND RECENT RUNS OF THE HRRR AND LOCAL 4 KM WRF HAVE STARTED TO TREND TOWARDS THE OTHER MODELS IN DEPICTING THIS. THUS HAVE INCREASED POPS INTO THE SCATTERED AND EVEN LOW LIKELY CATEGORY FOR TELLER/NRN EL PASO COUNTIES THIS EVENING. RUC13 AND LOCAL 4 KM WRF SPREAD PCPN EASTWARD ACROSS NRN PORTIONS OF THE SE PLAINS OUT TOWARDS KIOWA COUNTY DURING THE OVERNIGHT HOURS. THUS WILL SPREAD AT LEAST SOME ISOLATED POPS TO THE SOUTH AND EAST WITH TIME. NOT MUCH ACCUMULATION IS EXPECTED FARTHER TO THE SOUTH AND EAST. SYSTEM CLEARS THE AREA BY FRIDAY MORNING WITH DRIER AIR MOVING IN...THOUGH THERE IS STILL ENOUGH MOISTURE IN NW FLOW TO KEEP SOME OROGRAPHIC SNOW SHOWERS CONTINUING ALONG THE WESTERN SLOPES OF THE MOSQUITO AND SAWATCH RANGES THROUGH THE DAY. OTHERWISE...COLD NW FLOW REMAINS ACROSS THE AREA FOR FRIDAY...TEMPS WILL PROBABLY ONLY WARM INTO THE 20S ACROSS THE PLAINS...WITH SFC INVERSIONS HOLDING STRONG IN THE SAN LUIS VALLEY WHERE HIGHS WILL ONLY CLIMB INTO THE TEENS. -KT LONG TERM... (SATURDAY - THURSDAY) ..ANOTHER SYSTEM FOR MONDAY... SATURDAY INTO SUNDAY... A SHARP SHORT WAVE RIDGE WILL MOVE ACROSS THE REGION DURING THE WEEKEND. ANY SNOW SHOWERS OVER THE C MTNS FRIDAY EVENING WILL QUICKLY END...AND DRY WEATHER WILL BE OVER THE REGION LATER FRIDAY NIGHT THROUGH SUNDAY DAY. MAX TEMPERATURES SAT AND SUN WILL BE SEASONABLE WITH TEMPS AROUND 40F PLAINS AND 20S AND 30S MTNS/VALLEYS. LATE SUNDAY INTO TUESDAY... ANOTHER PACIFIC NW WX SYSTEM WILL MOVE ACROSS THE REGION THROUGH THIS PERIOD. THERE IS DISAGREEMENT AMONGST THE LONGER RANGE GUIDANCE...BUT IT IS LIKELY THAT ANOTHER TROUGH WILL MOVE ACROSS THE REGION DURING THIS PERIOD. THE EC IS MOST PROMISING FOR OVERALL PRECIP ACROSS THE AREA...WITH THE GFS SHOWING MOST OF THE PRECIP MAINLY OVER THE MTNS. COOLER WEATHER WILL ONCE AGAIN MOVE INTO THE REGION WITH HIGHS LIKELY NOT GETTING ABOVE FREEZING MONDAY AND TUESDAY. FOR NOW...PAINTED HIGH END SCATTERED AMOUNTS ACROSS THE CONTDVD...SCATTERED POPS ACROSS THE REST OF THE MTNS AND ISOLD POPS IN THE VALLEYS. ACROSS THE PLAINS...PAINTED ISOLD POPS MAINLY ACROSS THE FAR E PLAINS AND THE RATON MESA. AT THIS TIME...SNOWFALL AMOUNTS SHOULD BE ON THE LIGHTER SIDE...WITH LOW END ADVISORY AMOUNTS POSSIBLE ALONG THE CONTDVD. WED AND THU... IT SHOULD BE DRY ACROSS THE REGION WITH TEMPS RISING INTO THE L40S ONCE AGAIN ACROSS THE PLAINS AND 20S MTNS/VALLEYS. AVIATION... LOWERING CLOUD LAYER WILL AFFECT THE TAF SITES WITH MVFR CIGS DEVELOPING IN KCOS BY 23Z. CIGS COULD EVEN FALL INTO THE IFR CATEGORY AFTER 00Z IF -SHSN MOVES ACROSS THE TERMINAL. SNOWFALL ACCUMULATIONS OF UP TO 1 INCH WILL BE POSSIBLE AT KCOS. KPUB WILL ALSO SEE LOWERING CIGS IN THE EVENING...WITH MVFR TO POSSIBLY IFR CIGS DEVELOPING AFTER 06Z WITH SOME PATCHY FOG. MAIN THREAT FOR -SHSN LOOKS TO STAY TO THE NORTH OF THE TERMINAL...SO WILL NOT INCLUDE IT INTO THE KPUB TAF JUST YET. ONCE SYSTEM PASSES OFF TO THE EAST...WINDS WILL SHIFT OUT OF THE NW TO N WITH CIGS/VIS RISING INTO THE VFR CATEGORY FOR KCOS AND KPUB AROUND/AFTER 09Z. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ058- 060-066-068. && $$ 44/50
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
950 PM MST THU DEC 27 2012 .UPDATE... ISSUED AT 945 PM MST THU DEC 27 2012 MOSTLY LIGHT SNOW CONTINUES TO FALL OVER THE REGION FOR ONE MORE NIGHT AND INTO FRIDAY BEFORE THIS STORM CYCLE COMES TO AN END. CHECKING SNOTEL SITES AT 8 PM THE NORTHERN AND SOUTHERN MTNS HAVE BOTH RECEIVED GENERALLY 6-8 INCHES WITHIN THE LAST 24 HOURS. THERE WERE SOME BIG OUTLIERS IN THE NORTHERN MTNS: RIPPLE CREEK IN THE FLATTOPS 15 INCHES...TOWER SITE NEAR STEAMBOAT MTN 17 INCHES. THE CENTRAL MTNS HAVE RECEIVED LESS...MORE LIKE 4-6 INCHES. LIGHT SNOWFALL ALL DAY AT POWDERHORN...OBSERVED BY SKIING FORECASTERS... DID NOT YIELD MUCH ACCUMULATION. AT THE RADAR TRANSMITTER ON THE GRAND MESA VAD WINDS SHOW A STRONG VEERING FROM WEST TO NNW BEGINNING AT 00Z. SATELLITE AND MODELS INDICATE THIS BOUNDARY IS INTO THE SAN JUANS AT 9 PM AND WILL PUSH INTO NEW MEXICO BEFORE MIDNIGHT. THIS WILL SHIFT SNOW ACCUMULATION EMPHASIS TO NORTH-FACING SLOPES. HIGHLIGHTS FOR NORTHERN VALLEYS AND UTAH MOUNTAINS END AT MIDNIGHT. THE FLY IN THAT SCENARIO IS A WEAK WAVE WORKING INTO NE UTAH AROUND MIDNIGHT AND PASSING ACROSS NW COLORADO THROUGH 6 AM. THE 00Z NAM AND 03Z RAP SHOW ONLY LIGHT ACCUMULATIONS WITH THIS WAVE AND THE SLC OFFICE CONFIRMS THE WAVE HAS ONLY BEEN PRODUCING LIGHT SNOWFALL IN SE IDAHO-NORTHERN UTAH. SO WILL LET THOSE HIGHLIGHTS EXPIRE AT MIDNIGHT BUT KEEP HIGH POPS AND LOW ACCUMULATIONS ACROSS THE NORTH. OTHERWISE THE EVENING MODELS ARE PRODUCING ONLY LIGHT ACCUMULATIONS OF A FEW INCHES ON FRIDAY FOR THE NORTH SLOPES OF THE COLORADO MTNS. FAVORABLE OROGRAPHICS ARE IN PLACE BUT MOISTURE IS LACKING IN THIS NEW AIR MASS. COLD AIR BEGINS TO MODIFY ON THE MTN SLOPES ON SATURDAY AS HIGH PRESSURE BUILDS IN. THE VALLEYS WILL BE STRONGLY CAPPED. THE NEXT CHANCE OF SNOW IS STILL TIMED FOR SUNDAY AFTERNOON THROUGH MONDAY EVENING TO PRODUCE A WHITE NEW YEAR TO MATCH THE WHITE CHRISTMAS PAST. && UPDATE ISSUED AT 600 PM MST THU DEC 27 2012 SATELLITE INFRARED SHOWING A RIBBON OF COOLING CLOUD TOPS FROM THE BOOKCLIFFS TO NERN COLORADO. THIS AREA OF COOLING CLOUD TOP MARKS THE DISORGANIZED TROUGH AXIS THAT IS CURRENTLY MOVING SOUTHEAST ACROSS THE STATE. A BROAD AREA OF LIGHT SNOW IS FALLING BENEATH THIS CLOUD MASS AND HAVE UPDATED FORECAST GRIDS TO REFLECT THIS. BUT AS THE EVENING PROGRESSES...THE WESTERN PART OF THE TROUGH AXIS BECOMES MORE DISORGANIZED EVEN MORE SO TOWARD MIDNIGHT. EXPECT THE SNOW TO DIMINISH LATE EVENING AFTER THIS "BURST" OF EVENING SNOW. SPECIFIC HUMIDITY VALUES ARE LOW AND THEREFORE ANY ACCUMULATIONS WILL BE ON THE LIGHT SIDE. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 257 PM MST THU DEC 27 2012 A COLD UPPER TROUGH WAS SLOWLY SWINGING ACROSS THE FORECAST AREA THIS AFTERNOON. A DEFORMATION/SHEAR AXIS NEAR THE SRN WY BORDER AT MIDDAY TRAILED AN UPPER LOW EJECTING OUT ACROSS SD/NE. THIS AXIS WAS WEAKENING PER WARMING CLOUD TOPS AND SHOULD CONTINUE TO DO SO AS IT ROTATES SOUTHEAST ACROSS WRN CO. THE DEFORMATION AXIS AND WEAK NW OROGRAPHIC FLOW KEPT LIGHT SNOW ACROSS THE NORTH THROUGH MIDDAY...WITH THE LIGHT SNOW EXPANDING ACROSS THE CENTRAL THE SOUTHERN MOUNTAINS THIS AFTERNOON AND TONIGHT AS THE ENTIRE COLD TROUGH EVENTUALLY ROTATES THROUGH. THE ACTUAL AMOUNT OF MOISTURE AMOUNT IN THE AIR IS LIMITED...BUT WITH THE AIR MASS SO MOIST IT SHOULD NOT TAKE MUCH TO SQUEEZE OUT SOME SNOW. SNOW TO WATER RATIO OF ABOUT 20:1 WAS OBSERVED ACROSS THE NORTH THIS MORNING. WITH ANOTHER ANOTHER 1-3 INCHES OF ACCUMULATION FORECAST IN THE MTNS TONIGHT FROM PERIODS OF SNOW...WILL CONTINUE WITH THE CURRENT WINTER WEATHER ADVISORIES AND LET THE EVENING SHIFT RE-EVALUATE FOR ANY EARLY CANCELLATIONS. WEST AND NORTH FACING SLOPES WILL BE THE FAVORED AREAS TONIGHT. OUTSIDE OF THE NW CO PLATEAU... SCATTERED SNOW SHOWERS WILL PERSIST IN THE VALLEYS BUT WITH LITTLE ACCUMULATION. WILL INCLUDE A MENTION OF FOG IN MOST VALLEYS TONIGHT AS WELL. LIGHT SNOW WILL DIMINISH ACROSS THE CENTRAL AND SOUTHERN MTNS EARLY FRIDAY MORNING...WHILE NW FLOW AND A FINAL EMBEDDED WAVE MAY KEEP SOME LIGHT SNOW ACROSS THE NRN MTNS INTO EARLY AFTERNOON. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 257 PM MST THU DEC 27 2012 LOOK FOR A QUIETER WEATHER PATTERN THROUGH THE END OF THE WEEK AS A SHORTWAVE RIDGE PASSES OVER THE AREA FRI NIGHT INTO SAT. EXPECT VERY COLD NIGHTTIME LOWS FRI NIGHT AS VALLEY INVERSIONS STRENGTHEN UNDER MOSTLY CLEAR SKIES. BELOW NORMAL TEMPS WILL FOLLOW ON SAT AS COLD AIR REMAINS TRAPPED IN THESE VALLEYS. HOWEVER TEMPS WILL APPROACH NORMAL VALUES IN THE MOUNTAINS...ABOVE THE INVERSIONS. AS THE SHORTWAVE RIDGE PASSES OVER OUR FORECAST AREA EARLY IN THE PERIOD...A LONG WAVE TROUGH WILL DEVELOP ALONG THE WEST COAST. THE MID RANGE MODELS HAVE BEEN IN DISAGREEMENT IN THE HANDLING OF THIS SPLITTING TROUGH AS IT TRACKS EAST. HOWEVER THE 12Z ECMWF HAS TRENDED MORE TOWARDS THE GFS SOLUTION. THEREFORE THERE IS A LITTLE MORE CONFIDENCE THAT THE SOUTHERN BRANCH WILL PHASE WITH ENERGY DROPPING OUT OF THE NORTHWEST AND INTO THE GREAT BASIN ON SUNDAY. THIS SOLUTION BRINGS THE TROUGH ACROSS OUR AREA SUN NIGHT-MON...WITH THE SOUTHERN HALF FAVORED DUE TO THE ENERGETIC SOUTHERN BRANCH. FOR THIS PACKAGE...HAVE STILL KEPT POPS ON THE LOW SIDE DUE TO CONTINUED UNCERTAINTY. BEYOND MON...MODEL AGREEMENT DECREASES. WE DO STAY IN NORTH-NORTHWEST FLOW AS ADDITIONAL ENERGY DROPS INTO THE MEAN TROUGH THROUGH LATE TUE. THE ECMWF AND CANADIAN SHOW A LOW SPLITTING TO THE SOUTHWEST. THE EC PUTS IT OVER THE 4-CORNERS EARLY TUE...WITH THE CANADIAN OVER THE AZ/UT/NV TRIPLE POINT. BY EARLY WED BOTH SOLUTIONS SHOW THIS SPLIT-OFF LOW OVER SOUTHERN AZ...WITH OUR FORECAST AREA BETWEEN THE LOW AND A NORTHERN BRANCH TROUGH. THE GFS SOLUTION IS MUCH LESS SPLIT...WITH A LESS AMPLIFIED NORTHERN BRANCH AS WELL. THESE PERIODS WILL GENERALLY BE ON THE DRY SIDE. HOWEVER CONFIDENCE IS LOW. THIS LACK OF CONFIDENCE FOLLOWS FOR THU AS THE MID RANGE MODELS CONTINUE TO HAVE PROBLEMS IN A GENERALLY ACTIVE AND COMPLICATED LARGE SCALE PATTERN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 945 PM MST THU DEC 27 2012 SNOWFALL WILL CONTINUE TO RESULT IN WIDESPREAD MOUNTAIN OBSCURATIONS THROUGH TONIGHT. THE EXCEPTION WILL BE OVER THE EASTERN UT MOUNTAINS WHICH SHOULD BEGIN TO SEE IMPROVING CONDITIONS AFTER 10Z. SNOWFALL WILL CONTINUE TO PRODUCE AREAS OF MOUNTAIN OBSCURATION IN THE HIGHER COLORADO MOUNTAINS THROUGH FRI MORNING...WITH CONDITIONS IMPROVING IN THE AFTERNOON. IN THE VALLEY AREAS...SNOW WILL CONTINUE TO DIMINISH THIS EVENING. HOWEVER THE NORTHWEST PLATEAU THROUGH THE STEAMBOAT SPRINGS AREA WILL HOLD ON TO SNOWFALL THROUGH 12Z. THEREFORE AT TIMES MVFR OR EVEN ISOLATED IFR CONDITIONS WILL DEVELOP IN SNOW AT THE NORTHWEST CO AND HIGHER ELEVATION AIRPORTS THROUGH THIS EVENING. THEN BEGINNING AROUND MIDNIGHT PATCHY FOG WILL FORM IN MOST VALLEYS. ALL AIRPORTS MAY SEE PERIODS OF MVFR CIGS/VSBYS...WITH BRIEF PERIODS OF IFR POSSIBLE AS A RESULT. CONDITIONS WILL BEGIN TO IMPROVE BY MID MORNING ON FRI. HOWEVER FOG MAY PERSIST IN SOME PRONE LOCATIONS THROUGHOUT THE MORNING...AND THE EASTERN UINTA BASIN MAY SEE AREAS OF MVFR VSBYS IN BR THROUGH THE AFTERNOON. OTHERWISE VFR CONDITIONS ARE EXPECTED AT THE TAF SITES BY NOON. SOME MTN OBSCURATION WILL CONTINUE OVER THE MTNS FROM KSBS SOUTH TO KEGE INCLUDING RABBIT EARS AND VAIL PASSES THROUGH 21Z FRIDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ001- 002-005. WINTER WEATHER ADVISORY UNTIL 6 AM MST FRIDAY FOR COZ003-004-009- 010-012-013-017>019. UT...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR UTZ023- 025-028. && $$ UPDATE...JOE SHORT TERM...JAD LONG TERM...EH AVIATION...EH+JOE
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
907 PM MST THU DEC 27 2012 .UPDATE... THE AREA WHERE A FEW SNOWBANDS WERE ABLE TO FORM MOVING SOUTH OVER THE URBAN CORRIDOR CONTINUES TO MOVE SOUTH OVER THE AREA WITH LITTLE ECHOES REMAINING ON RADAR. WILL LIKELY STILL SEE SOME LIGHT SNOW OVER THE PALMER DIVIDE AND INTO LINCOLN COUNTY FOR THE NEXT FEW HOURS. WITH CLEARING ON THE BACK OF THE SNOWBAND...NOT SURPRISED TO SEE SOME PATCHY FOG AS RECENT SNOWFALL MOISTENED UP THE AIR THEN CLEARING SKIES ALLOWS THE TEMPERATURE TO DROP. NOT COMPLETELY CONFIDENT ON SOME OF THE OBSERVATIONS COMING IN WITH FOG HOWEVER AS THE DEWPOINT SPREAD SEEMS TOO LARGE. BUT WILL STILL ADD SOME PATCHY FOG TO THE FORECAST. MORE CLOUDS UPSTREAM AS WELL AS WINDS EXPECTED TO BECOME DRAINAGE SHOULD LIMIT THE TIME OF FOG TO EXIST. AS THE ENHANCED BAND CONTINUES TO MOVE SOUTH...NOT MUCH MORE SNOW IS EXPECTED OVER THE MOUNTAINS. THEREFORE WILL CANCEL THE WINTER WEATHER ADVISORY FOR THE MOUNTAINS TWO HOURS AHEAD OF THE SCHEDULED EXPIRATION TIME. && .AVIATION...BESIDES SOME LIGHT FLURRIES AT BJC AND APA...SNOW IS ENDING ACROSS THE AREA NORTH TO SOUTH. WITH SOME CLEARING ON THE BACKSIDE...A FEW OBSERVATIONS REPORTING AREAS OF FOG. WOULD NOT BE SURPRISED TO SEE SOME AREAS FLOATING AROUND...HOWEVER WITH ADDITIONAL CLOUDS UPSTREAM AND EXPECTED DRAINAGE WINDS...FOG WILL NOT BE LONG LIVED. CEILINGS SHOULD BE IMPROVING AFTER 06Z WITH WINDS BECOMING DRAINAGE. WINDS TO REMAIN LIGHT SOUTHERLY THROUGH FRIDAY AS DRY CONDITIONS PREVAIL. && .PREV DISCUSSION... /ISSUED 341 PM MST THU DEC 27 2012/ SHORT TERM...MOUNTAIN WEB CAMS SHOWING ONGOING SNOWFALL...THOUGH BEGINNING TO SHOW SOME SIGNS OF DECREASING. LATEST RUC KEEPS AIRMASS FAIRLY MOIST THROUGH THE EVENING WITH FLOW BECOME MORE NORTHWEST. HOWEVER...LAPSE RATES BEGIN DECREASING ALONG WITH INCREASING SUBSIDENCE. THUS SHOULD SEE A GRADUAL DECREASE IN SNOWFALL THROUGH THE EVENING WITH PERHAPS ANOTHER 2 TO 4 INCHES DUE TO THE OROGRAPHICS. WILL KEEP THE ADVISORIES GOING THROUGH 06Z. ACROSS PLAINS...RADAR SHOWING LIGHT SNOW DEVELOPING ACROSS PALMER DIVIDE AS WELL AS ACROSS PORTIONS OF EASTERN LARIMER AND WESTERN WELD COUNTIES. LATEST MODELS SHOW THE SNOW PERSISTING ACROSS THE PALMER DIVIDE AND SOUTHERN FOOTHILLS THROUGH THE EVENING...SPREADING NORTH ALONG THE FOOTHILLS AND WESTERN SECTIONS OF THE URBAN CORRIDOR AND EAST INTO LINCOLN COUNTY BY 05Z. WILL CONTINUE THIS TREND FOR THE EVENING WITH THE HIGHER POPS IN THIS AREA AS WELL AS IN EASTERN LARIMER COUNTY. ELSEWHERE ALONG THE URBAN CORRIDOR...WILL CONTINUE WITH CHANCE POPS AS IT STILL APPEARS MOST OF SNOW SHOULD OCCUR CLOSER TO THE FOOTHILLS. LOWER POPS EASTWARD AWAY FROM THE FRONT RANGE. THE EASTERLY UPSLOPE STILL LOOKING FAIRLY WEAK...STILL THINKING ACCUMULATIONS WILL BE BELOW AN INCH THOUGH A FEW AREAS ALONG THE PALMER DIVIDE AND NEAR THE FOOTHILLS COULD SEE A BIT MORE. AS LAPSE RATES DECREASE AFTER 06Z...SHOULD SEE SNOW CHANCES DECREASE AS WELL. WILL KEEP A SLIGHT CHANCE OF LIGHT SNOW IN AND NEAR THE FOOTHILLS AS WELL AS ALONG THE PALMER DIVIDE INTO LINCOLN COUNTY. ON FRIDAY...NORTHWEST FLOW ALOFT TO CONTINUE WITH UPPER TROUGH OVER NORTHERN PLAINS. MODEL CROSS SECTIONS SHOW FAIRLY DECENT MOISTURE ACROSS THE MOUNTAINS...GRADUALLY DECREASING DURING THE AFTERNOON. THUS THERE SHOULD BE AT LEAST A CHANCE OF SNOW DUE TO THE FAVORED OROGRAPHICS. HOWEVER...QG VERTICAL VELOCITIES SHOW DOWNWARD MOTION...WHICH WILL LIMIT THE SNOW CHANCES AS WELL AS ACCUMULATIONS. ACROSS PLAINS...DRY CONDITIONS TO PREVAIL WITH A DECREASE IN CLOUD COVER BY THE AFTERNOON. TEMPERATURES ONLY EXPECTED TO WARM A FEW DEGREES FROM TODAY`S READINGS DUE TO SNOW COVER AND INVERSIONS. LONG TERM...DRIER AIR WILL BE MOVING OVER COLORADO FRIDAY NIGHT. IF ANY SNOW SHOWERS LINGER INTO THE EVENING HOURS...THEY WILL BE LIGHT AND SHORT LIVED. SKIES WILL CLEAR BY MIDNIGHT...IF NOT EARLIER. THE CLEAR SKIES WILL ALLOW TEMPERATURES IN LOW LYING AREAS TO PLUMMET. EXPECT THE MOUNTAIN VALLEYS TO DROP BELOW ZERO. COLD LOCATIONS LIKE KREMMLING WILL DROP TO AROUND -20 BY SATURDAY MORNING. WEAK DOWNSLOPE WINDS WILL DEVELOP ALONG THE FRONT RANGE. THIS WILL KEEP THE FOOTHILLS AND AREAS CLOSE TO FOOTHILLS WARMER WITH LOWS IN THE SINGLE DIGITS TO TEENS. UPPER LEVEL RIDGE WILL MOVE ACROSS COLORADO SATURDAY. AIRMASS UNDER IT WILL BE DRY RESULTING IN MOSTLY CLEAR SKIES. HIGHS WILL CLIMB INTO THE 30S FOR MOST OF NORTHEAST COLORADO. LOW LYING AREAS MAY BE STUCK UNDER AN INVERSION AND WILL STRUGGLE TO REACH THE 30S. CLOUDS WILL INCREASE SUNDAY AS AN UPPER LEVEL TROUGH MOVES OVER THE GREAT BASIN. THE MOISTURE WILL BE AT THE MID AND UPPER LEVELS OF THE ATMOSPHERE...SO NOT EXPECTING ANY SNOW UNTIL THE TROUGH NEARS WHICH WILL BE LATE SUNDAY NIGHT. THE UPPER LEVEL TROUGH WILL DIG SOUTHEAST AND MOVE ACROSS THE SOUTHERN ROCKIES MONDAY. A COLD FRONT ASSOCIATED WITH THE TROUGH WILL PUSH THROUGH THE AREA MONDAY. APPEARS THE TROUGH WILL BE TOO FAR SOUTH TO BRING THE AREA MUCH PRECIPITATION. WILL KEEP LOW POPS...10 TO 30 PERCENT...IN THE FORECAST FOR MONDAY AND TUESDAY. HIGHEST POPS BEING IN THE MOUNTAINS. COOL AIR WILL MOVE BACK INTO THE AREA FOR MONDAY AND TUESDAY. FOR WEDNESDAY AND THURSDAY...APPEARS THERE WILL BE SOME SORT OF RIDGE OVER THE WESTERN STATES. THIS WILL PRODUCE A DRY BUT COOL NORTHWEST FLOW ALOFT OVER COLORADO. WILL KEEP THE FORECAST DRY WITH TEMPERATURES AT OR SLIGHTLY BELOW NORMAL. AVIATION...LIGHT SNOW DEVELOPING ALONG PALMER DIVIDE AS WELL AS WESTERN AND SOUTHERN SECTIONS OF THE DENVER AREA. LATEST RUC AND HRRR KEEPS THE BEST CHANCE FOR SNOW AT APA AND BJC THROUGH 06Z... WILL CONTINUE THE TEMPO FOR MVFR/IFR CONDITIONS. STILL SOME CHANCE THAT SNOW COULD SPREAD INTO DIA WITH POSSIBLE MVFR/IFR CONDITIONS. FOR NOW WILL CONTINUE VCSH AND SEE HOW THINGS DEVELOP. SNOW CHANCES TO DECREASE AFTER 06Z WITH VFR CONDITIONS AND IMPROVING CEILINGS. EASTERLY WINDS TO DECREASE AFTER MIDNIGHT AND BECOME SOUTHERLY AS DRAINAGE PATTERN DEVELOPS. WINDS TO REMAIN LIGHT SOUTHERLY THROUGH FRIDAY AS DRY CONDITIONS PREVAIL. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....MEIER UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
305 AM EST FRI DEC 28 2012 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN AMPLIFIED BUT PROGRESSIVE UPPER LEVEL PATTERN OVER THE CONUS. FROM WEST TO EAST WE FIND NORTHERN STREAM FLOW RIDGING NORTHWARD ALONG THE PACIFIC COAST BEFORE DIGGING BACK SOUTH INTO LONGWAVE TROUGHING EJECTING EASTWARD FROM THE INTERMOUNTAIN WEST. FURTHER DOWNSTREAM THE FLOW THEN FORMS LONGWAVE RIDGING OVER MUCH OF THE EASTERN STATES IN THE WAKE OF THE SYSTEM NOW DEPARTING NEW ENGLAND TOWARD THE CANADIAN MARITIMES. THE FL PENINSULA IS UNDER WEAK UPPER RIDGING FORCED BY THE HEIGHT FALLS CURRENTLY SPREADING ACROSS THE SOUTHERN PLAINS. 28/00Z KTBW SOUNDING SHOWED A VERY DRY PROFILE BELOW 500MB...BUT THIS DRY COLUMN WILL BE SHORT-LIVED AS ALL GUIDANCE MEMBERS SHOWS A QUICK MOISTENING AND DESCENDING OF MOISTURE WORKING SOUTH TO NORTH TODAY. AT THE SURFACE...HIGH PRESSURE IS IN CONTROL FOR THE MORNING HOURS. THE LIGHT WINDS AND DRY COLUMN HAVE ALLOWED FOR GOOD RADIATIONAL COOLING...ESPECIALLY UP OVER THE NATURE COAST. TEMPERATURES WITHIN THE FREEZE WARNING HAVE BEEN NEAR OR JUST BELOW FREEZING FOR THE PAST COUPLE OF HOURS...AND AREAS OF DENSE RADIATIONAL GROUND FOG HAVE DEVELOPED. THIS FOG IS LIKELY QUITE SHALLOW IN NATURE. NOT ANTICIPATING MUCH MORE OF A TEMP DROP...AS THE ADVERTISED UPPER LEVEL MOISTURE IS BEGINNING TO SPREAD OVER THE REGION AND SHOULD SLOW ANY FURTHER RADIATIONAL COOLING THROUGH DAWN. SEEING THE FIRST SIGNS OF SURFACE CYCLOGENESIS ALONG THE UPPER TX COAST IN ADVANCE OF THE UPPER TROUGH. EXTENDING EASTWARD FROM THIS LOW...2 DIFFERENT WARM FRONTAL FEATURES CAN BE SEEN. ONE IS HUGGING THE NORTHERN GULF COAST...AND THE OTHER APPEARS TO BE FURTHER SOUTH. BOTH OF THESE FEATURES WILL BE BUILDING INTO THE EASTERN GULF TODAY AND MAKE FOR A SOMEWHAT TRICKY FORECAST. && .SHORT TERM (TODAY THROUGH SUNDAY)... TODAY/TONIGHT...AS MENTIONED ABOVE...COLUMN MOISTURE WILL BE INCREASING AND DESCENDING WITHIN A DEVELOPING LOW LEVEL UPGLIDE/ WAA PATTERN ALONG THE 290-305K SURFACES. SKIES WILL TRANSITION TO MOSTLY CLOUDY FROM SOUTHWEST TO NORTHEAST. UPGLIDE/WAA AND RESULTING MOISTENING APPEAR SUFFICIENT ENOUGH BY THE LATE AFTERNOON TO FORCE THE FIRST SHOWER DEVELOPMENT ALONG THE SUNCOAST ZONES. ANY SHOWERS THROUGH EARLY EVENING SHOULD BE SCATTERED...SHALLOW AND LIGHT...BUT DON`T BE SURPRISED TO SEE A FEW RAINDROPS ON THE WINDSHIELD FOR THE EVENING COMMUTE. THE TRICKY PART OF THE FORECAST COMES IN JUST HOW QUICKLY THE SOUTHERN WARM-FRONTAL FEATURE MOVES NORTHWARD AND JUST HOW QUICKLY / AGGRESSIVE THE DEVELOPMENT OF SHOWERS WILL BE ALONG AND NORTH OF THE BOUNDARY THIS EVENING. AS THE WARM FRONT MOVES NORTHWARD...THE CHANCES FOR SHOWERS TO THE SOUTH OF THE BOUNDARY WILL DECLINE...MEANING THE PROPER TIMING OF THE ITS MOVEMENT IS IMPORTANT. BASED ON AN ENSEMBLE APPROACH TO THE GUIDANCE...THE TAMPA BAY / I-4 CORRIDOR APPEARS TO BE THE TRANSITION POINT THIS EVENING AND INTO THE OVERNIGHT BETWEEN WIDELY SCT SHOWERS AND POTENTIALLY MORE WIDESPREAD ACTIVITY. THE POP GRIDS WILL SHOW THIS PHILOSOPHY ALONG WITH THE BIAS OF NWP MODELS TO BE TOO SLOW IN THE DEVELOPMENT AND EXIT OF UPGLIDE PRECIP. CURRENTLY HAVE OVERNIGHT RAIN CHANCES RISING TO CATEGORICAL ACROSS MUCH OF THE NATURE COAST...LIKELY THROUGH THE TAMPA BAY REGION...AND THEN CHANCE POPS FURTHER SOUTH ALONG THE SUNCOAST / INTERIOR SOUTHERN ZONES. SHOWALTER INDICES NORTH OF THE WARM FRONT ARE ALSO AROUND 0 OR SLIGHT NEGATIVE...AND HAVE CONTINUED ISOLATED THUNDER MENTION. THE BEST CHANCE OF THUNDER WILL BE UP OVER THE NATURE COAST WHERE THE DEEPER LIFT WILL EXIST. AS THE WARM FRONT SLOWLY MOVES NORTH TONIGHT...LOW TEMPS ARE LIKELY TO OCCUR IN THE LATE EVENING/MIDNIGHT TIME FRAME...AND THEN STEADILY RISE DURING THE PRE-DAWN HOURS. SATURDAY...LOW PRESSURE WILL QUICKLY TRANSLATE EASTWARD TO OUR NORTH DURING SATURDAY MORNING WITH THE WARM FRONT LIFTING NORTH OF OUR AREA EARLY. SURFACE LOW WILL THEN BEGIN RE-DEVELOPMENT / DEEPENING OFF THE EASTERN SEABOARD DURING THE AFTERNOON. TRAILING COLD FRONT WILL QUICKLY MOVE NORTHWEST TO SOUTHEAST ACROSS THE REGION DURING THE DAY. GFS IS THE FASTEST TO PUSH THE BOUNDARY THROUGH OUR NORTHERN ZONES...AND THE COLD FRONTAL FORCED BAND OF SHOWERS AND STORMS IS ESSENTIALLY DONE UP TOWARD LEVY /CITRUS COUNTIES BY EARLY/MID-MORNING. OTHER GUIDANCE MEMBERS INCLUDING THE NAM/ECMWF/SREF MEAN ARE A FEW HOURS SLOWER. THE GFS MAY VERY WELL BE CORRECT IN THE FASTER SOLUTION...BUT WILL SLOW THINGS DOWN BY A COUPLE HOURS OUT OF RESPECT FOR THE OTHER MEMBERS. EITHER WAY...BEST SHOWER/STORM CHANCES WILL BE THROUGH 18Z FROM THE TAMPA AREA /SARASOTA AREA NORTHWARD. GOOD AGREEMENT IN A DECLINE IN SHOWER/STORM ORGANIZATION ALONG THE FRONT DURING THE AFTERNOON AS THE BAND MOVES THROUGH THE SOUTHERN ZONES. THIS SCENARIO SEEMS PLAUSIBLE AS THE SURFACE LOW RACES NORTHEASTWARD AND THE WHOLE SYSTEM DOWN OUR WAY BEGINS TO BECOME STRETCHED / LESS FOCUSED. SATURDAY NIGHT/SUNDAY...COLD FRONT AND ANY LINGERING SHOWERS EXIT INTO SOUTH FLORIDA DURING THE EARLY EVENING AS A COOLER AND DRIER AIRMASS ARRIVES ON NW FLOW IN THE WAKE OF THE FRONT. TEMPERATURES WILL BE COOL BY DAWN SUNDAY WITH WIDESPREAD 40S...AND EVEN MID/UPPER 30S FOR CITRUS/LEVY COUNTIES. MAV MOS HAS A FEW 30-32 TEMPS UP OVER THE FAR NORTH LATE SATURDAY NIGHT...HOWEVER...MOS NUMBERS ARE ALMOST ALWAYS TOO COLD DURING THE FIRST ADVECTION NIGHT BEHIND A FRONT... AND FOR NOW FEEL SAFE KEEPING LOW TEMPS ABOVE FREEZING. WIND CHILLS ARE FORECAST TO BE WELL DOWN INTO THE 30S TO THE NORTH OF THE I-4 CORRIDOR THOUGH BY DAWN. STRONG CONTINENTAL HIGH PRESSURE BUILDS TO OUR NORTH ON SUNDAY AS HEIGHT RISE OVERHEAD. ALL THIS WILL RESULT IN A FAIR...BREEZY...AND SEASONABLY COOL DAY UNDER ABUNDANT SUNSHINE. && .LONG TERM (SUNDAY NIGHT THROUGH THURSDAY)... MODELS ARE IN VERY GOOD AGREEMENT THROUGH WEDNESDAY AND DO NOT DIVERGE QUITE AS MUCH FOR DAY 7 AS THEY HAD 24 HOURS AGO. THIS ALLOWED ME TO SLOW THE FRONT DOWN BY 18 TO 24 HOURS WHICH BRINGS IT THROUGH HERE ON THURSDAY INSTEAD OF WEDNESDAY. HIGH PRESSURE WILL RESIDE NORTH OF THE REGION SUNDAY NIGHT AND SLIDE INTO THE ATLANTIC ON MONDAY. THIS WILL TURN OUR WINDS SOUTHEASTERLY BRINGING WARMER AIR AND HIGHER MOISTURE INTO THE AREA. IN FACT...WE COULD SEE TEMPERATURES APPROACHING 80 DEGREES ON TUESDAY AND WEDNESDAY ESPECIALLY SOUTH OF TAMPA BAY. SUNDAY NIGHT SHOULD STILL BE COOL WITH LOWS IN THE MID 30S NORTH TO MID 40S INTERIOR CENTRAL AND SOUTH. ONE POTENTIAL RAIN MAKER WILL BE A WEAKENING FRONTAL BOUNDARY THAT IS FORECAST TO SETTLE INTO NORTH FLORIDA LATE TUESDAY THEN BECOME STATIONARY DURING WEDNESDAY. I THINK MOST OF THE AREA WILL GET BY WITHOUT RAIN ON TUESDAY...BUT SOME SHOWERS COULD AFFECT THE AREA TUESDAY NIGHT AND ESPECIALLY ON WEDNESDAY. THE BEST CHANCE OF RAIN ON WEDNESDAY WILL BE NORTH OF TAMPA BAY. LOW PRESSURE WILL BE DEVELOPING IN THE GULF OF MEXICO WEDNESDAY NIGHT WHICH WILL ENERGIZE THE STATIONARY FRONTAL BOUNDARY OVER FLORIDA. THE EXACT PLACEMENT OF THE FRONT IS STILL IN QUESTION...BUT THINK THERE WILL BE PLENTY OF LIFT FOR SHOWERS AND EVEN A FEW THUNDERSTORMS IN THE WARM AIR AHEAD OF THE LOW CENTER. AFTER THAT... THE GFS TAKES LOW PRESSURE QUICKLY ACROSS FLORIDA AND INTO THE ATLANTIC ON THURSDAY WITH THE FRONT TRAVELING QUICKLY SOUTHEAST ACROSS THE STATE. THE ECMWF IS SLOWER AND STILL HAS WAVES OF LOW PRESSURE ALONG THE FRONT ACROSS FLORIDA AND INTO THE GULF ON THURSDAY. HAVE BASICALLY BLENDED GUIDANCE FOR A COMPROMISE WHICH WILL CONTINUE OUR RAIN CHANCES THROUGH DAY SEVEN. && .AVIATION... CLOUDS SHOULD GRADUALLY INCREASE LATER THIS MORNING AND THEN LOWER THIS AFTERNOON AND TONIGHT. EXPECT VFR CEILINGS AROUND 7000 FEET TO BECOME MVFR THIS EVENING...THEN IFR AND PERHAPS EVEN LIFR OVERNIGHT. CONFIDENCE IN MVFR AND IFR CEILINGS IS HIGHER THAN AVERAGE. && .MARINE... WINDS SHIFT TO THE SOUTHEAST AND SOUTH WITH TIME TODAY AHEAD OF AN APPROACHING COLD FRONT. CAUTIONARY LEVEL WINDS ARE EXPECTED BY THIS EVENING OVER THE OFFSHORE WATERS AND THEN EXPANDING OVER ALL THE FORECAST WATERS AFTER MIDNIGHT. A COLD FRONT AND BAND OF SHOWERS AND STORMS WILL MOVE NORTHWEST TO SOUTHEAST ACROSS THE EASTERN GULF OF MEXICO DURING SATURDAY WITH WINDS SHIFTING TO THE NORTHWEST BY SATURDAY NIGHT. WINDS AND SEAS WILL BUILD TO ADVISORY LEVELS BEHIND THIS FRONT FOR SATURDAY NIGHT AND SUNDAY WHILE SHIFTING TO THE NORTHEAST. ELEVATED EASTERLY FLOW TO CAUTIONARY LEVELS IS EXPECTED TO PERSIST SUNDAY NIGHT INTO MONDAY. && .FIRE WEATHER... HIGH PRESSURE QUICKLY EXITS TO THE EAST OF THE REGION TODAY AS LOW PRESSURE ORGANIZES ALONG THE NORTHERN GULF COAST AND APPROACHES FROM THE WEST. LOW LEVEL MOISTURE WILL BE ON THE INCREASE FROM SOUTH TO NORTH TODAY. INTERIOR NATURE COAST LOCATIONS MAY BRIEFLY APPROACH 35 PERCENT THIS AFTERNOON...HOWEVER IT NOW APPEARS THAT THE MOISTURE WILL ARRIVE QUICK ENOUGH TO PREVENT ANY CRITICAL FIRE WEATHER CONDITIONS. SHOWERS OVERSPREAD THE REGION TONIGHT...ESPECIALLY FROM TAMPA BAY NORTHWARD. THESE SHOWERS AND EMBEDDED THUNDERSTORMS WILL THEN SHIFT SOUTH AND EAST DURING SATURDAY AHEAD OF A COLD FRONT. LINGERING SHOWERS AND THE COLD FRONT WILL EXIT SOUTH OF THE FORECAST AREA BY SATURDAY EVENING WITH A COOLER AND DRIER AIRMASS ARRIVING ONCE AGAIN FOR THE SECOND HALF OF THE WEEKEND. RELATIVE HUMIDITY VALUES ARE CURRENTLY FORECAST TO BRIEFLY REACH CRITICAL LEVELS SUNDAY AFTERNOON AWAY FROM THE COAST. && .PRELIMINARY POINT TEMPS/POPS... TPA 71 64 74 45 / 20 70 70 10 FMY 77 66 79 53 / 20 20 50 10 GIF 71 59 76 46 / 10 60 70 10 SRQ 73 64 74 50 / 20 60 70 10 BKV 69 58 73 42 / 10 80 70 10 SPG 69 64 73 51 / 20 70 70 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR CITRUS- HERNANDO-LEVY. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
304 AM CST FRI DEC 28 2012 .SYNOPSIS... 06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KEMP WITH A DIFFUSE FRONT RUNNING ACROSS NORTHERN MISSOURI AND INTO SOUTHERN ILLINOIS. A WEAK TROF RAN FROM NORTHEAST IOWA INTO NORTHERN INDIANA WHILE AN INVERTED TROF RAN FROM THE KANSAS LOW INTO THE EASTERN DAKOTAS. DEW POINTS WERE IN THE TEENS AND 20S ACROSS MUCH OF THE MIDWEST WITH 30S AND 40S IN THE SOUTHERN PLAINS AND DEEP SOUTH. && .SHORT TERM...TODAY AND TONIGHT... BASED ON SFC REPORTS...THE RADAR RETURNS ARE INDICATING MORE VIRGA THAN WHAT IS ACTUALLY REACHING THE GROUND. THE MECHANISM FOR GENERATING THE -SN IS NOT OBVIOUS BUT APPEARS TO BE TIED TO THE NARROW LAYER OF DRY AIR ON THE 00Z SOUNDING. RAP TRENDS ALONG WITH THE OTHER MODELS INDICATE SATURATION IN THE 800-850MB LAYER WILL OCCUR DURING THE DAY ALLOWING CONDENSATION PRESSURE DEFICITS IN THIS LAYER TO COLLAPSE. ALTHOUGH THE FORCING IS NOT GREAT IT WILL BE ENOUGH TO GENERATE LIGHT SNOW. THE INVERTED TROF COMPLICATES THINGS FURTHER SINCE INVERTED TROFS ARE NOTORIOUS FOR SURPRISES. BASED ON RAP TRENDS SAID INVERTED TROF WILL SLOWLY MOVE ACROSS THE CWFA DURING THE DAY. THUS THE BETTER SNOW SHOULD BE SEEN IN ADVANCE AND IMMEDIATELY AROUND THE INVERTED TROF WITH PRECIPITATION INTENSITY DECREASING ONCE THE INVERTED TROF GOES BY. TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BEFORE SLOWLY TAPERING OFF. VERY LIGHT SNOW OR FLURRIES IS EXPECTED TO CONTINUE UNTIL NEARLY SUNRISE. MOISTURE IS LIMITED AND THE MAIN FORCING FEATURES ARE ALSO QUITE WEAK. HOWEVER...ADDING THE INVERTED TROF TO EVERYTHING SHOULD RESULT IN MEASURABLE SNOWFALL ACROSS A MAJORITY OF THE CWFA. AMOUNTS OF 0.5 TO 1 INCH SHOULD BE SEEN FROM ABOUT HWY 30 ON NORTH WITH A TRACE TO 0.5 INCHES OF ACCUMULATION SOUTH OF HWY 30. ..08.. .LONG TERM...SATURDAY THROUGH THURSDAY... THE BULK OF THE LIGHT SNOW SHOULD BE EAST OF THE FORECAST AREA EARLY SATURDAY MORNING. HOWEVER...MODELS ARE SHOWING A SECOND SHORT WAVE OVER WESTERN IOWA/MISSOURI EARLY SATURDAY. HAVE HELD ONTO SOME FLURRIES IN THE EAST WITH THIS MID LEVEL FEATURE MOVING THROUGH BY 18Z SATURDAY. COLD TEMPERATURES WILL OVERSPREAD THE AREA SATURDAY NIGHT WITH SURFACE AND UPPER RIDGING MOVING THROUGH THE REGION. MODELS ARE SUGGESTING THAT THE SURFACE RIDGE AXIS WILL BE OVER THE FORECAST AREA AT 06Z AND EAST OF THE CWFA BY 12Z SO WE SHOULD SEE SOME LIGHT RETURN FLOW DEVELOPING AFTER MIDNIGHT. WITH SOUTH WINDS DEVELOPING LATE...KEPT OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE ZERO NORTH TO AROUND 15 IN THE FAR SOUTH. FOR THE BEGINNING OF THE WORK WEEK A SOUTHERN STREAM SYSTEM WILL MOVE OUT OF THE SOUTHWEST U.S. INTO THE LOWER MISSISSIPPI VALLEY MONDAY AND MONDAY NIGHT. THE NORTHERN EDGE OF THE PRECIPITATION SHIELD IS PROGGED TO BRUSH THE SOUTHERN COUNTIES MONDAY AND MONDAY NIGHT. TEMPERATURES WILL BE COLD ENOUGH FOR THIS PRECIPITATION TO BE ALL SNOW. HOWEVER...THE SNOW WILL BE LIGHT AND SHOULD NOT AMOUNT TO MUCH ACCUMULATION BY TUESDAY MORNING. NORTHWEST FLOW DEVELOPS OVER THE UPPER MIDWEST BY LATE TUESDAY WITH GOOD AGREEMENT AMONG THE LONG RANGE MODELS ON A SHORT WAVE DROPPING SOUTHEAST THROUGH REGION WEDNESDAY NIGHT AND THURSDAY. THE SYSTEM WILL BE ENCOUNTERING A DRY AIRMASS AND SHOULD NOT PRODUCE ANY PRECIPITATION. HOWEVER IT WILL DRAG A COLD AIRMASS SOUTH INTO THE MID MISSISSIPPI VALLEY BY THURSDAY. HAVE OPTED FOR THE COLDER GUIDANCE FOR THURSDAY/S TEMPERATURES. DLF && .AVIATION... /ISSUED 1108 PM CST THU DEC 27 2012/ LIGHT EAST WINDS AND STRATUS AT THE BORDERLINE BETWEEN MVFR/IFR WILL CONTINUE THROUGH ABOUT 14Z FRIDAY...WITH CIGS OF 900 TO 2000 FT. LIGHT EAST WINDS WILL CONTINUE TO FRIDAY AFTERNOON. LIGHT SNOW AND FOG SHOULD MOVE INTO ALL SITES AROUND 10Z-14Z FRIDAY. THOUGH SNOW SHOULD BE MAINLY LIGHT...MODELS DO SUGGEST A LOWERING OF VISIBILITY THROUGH FOG TO POSSIBLY UNDER A MILE FOR MUCH OF THE DAY AND EVENING. ALONG WITH THAT FOG...CIGS SHOULD DROP TO LESS THAN 1000 FT FOR MOST THE DAY FRIDAY AND FRIDAY EVENING. FOR NOW...WILL GO WITH 1SM VISIBILITY IN FOG AND LIGHT SNOW...AGAIN RESTRICTED BY FOG MORE THAN SNOW IN REALITY. WINDS MAY BECOME CALM AFTER 18Z FRIDAY...THROUGH EARLY FRIDAY EVENING BEFORE A 03Z SWITCH TO NORTHWEST AS THE WEAK LOW PRESSURE SYSTEM MOVES INTO ILLINOIS. ERVIN && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
344 AM CST FRI DEC 28 2012 .DISCUSSION... ROUND OF CLOUDS AND LIGHT FREEZING DRIZZLE OR SNOW COMING TO THE AREA AS AN UPPER LONGWAVE TROF MOVES EASTWARD OUT OF THE ROCKIES TODAY. TEMPERATURES HAVE HELD AROUND THE FREEZING MARK ALONG AND SW OF THE INCOMING LOW...WITH CHILLY SINGLE DIGIT TEMPERATURES NOTED OUT ON THE HIGH PLAINS. TODAY/TONIGHT...CAA CONTINUES THROUGHOUT THE DAY TODAY AS UPPER TROF PASSES OVER THE STATE IN PHASES AND PUSHES COLD AIR SOUTHWARD AS IT DOES SO. HIGHS TODAY NOT EXPECTED TO BE MORE THAN THE 20S IT IS NOW AT MANY LOCATIONS ALONG AND SE OF THE INTERSTATE. OVERNIGHT LOWS TONIGHT INTO SATURDAY EXPECTED TO BE QUITE CHILLY WITH SINGLE DIGITS COMMON FOR MUCH OF THE FORECAST AREA. RETURN OF THE UPPER RIDGE TO THE HIGH PLAINS INTO SATURDAY AFTERNOON MAY MAKE FOR A WARMER WEEKEND WITH HIGHS NEAR THE FREEZING MARK SATURDAY AND EVEN WARMER ON SUNDAY. MON-TUES...NEXT UPPER TROFS PROGGED OVER THE NORTHERN PLAINS WITH THE SOUTHERN PORTION SOUTHWARD OVER THE FOUR CORNERS REGION. SOUTHERN WAVE ADVECT WARMER TEMPERATURES AND MOISTURE WELL INTO THE CENTRAL PLAINS FOR MONDAY MORNING...BEFORE IT BECOMES A BATTLE FOR HOW QUICKLY THE NEXT ROUND OF COLD AIR CAN MOVE SOUTHWARD AS THE NORTHERN STREAM PASSES ACROSS THE HIGH PLAINS. COLUMN SATURATES TOP DOWN AND CURRENTLY WOULD EXPECT SNOW FROM THE PROFILE. PERHAPS MIXED WITH RAIN WHERE HIGHS ARE WARMER. EC TAKES SOUTHERN PORTION OF THE TROF AND SHEARS IT OUT ACROSS THE HIGH PLAINS AND WOULD THEREFORE LINGER PRECIPITATION INTO TUESDAY. MAY SEE A FEW INCHES OF SNOW FROM THIS STORM BUT WILL NEED TO MONITOR FOR POSSIBLE PRECIP TYPE CHANGES WITH STORM TRACK. WED/THURS MAY PAN OUT TO BE PRETTY CHILLY DAYS AS NORTH TO NORTHWEST FLOW SETS UP BYE THE MIDDLE OF NEXT WEEK. 67 && .AVIATION... OBS UPSTREAM HAVE SHOWN CIGS IMPROVING UPSTREAM AND BEHIND THE SURFACE TROUGH AXIS. HOWEVER RAP AND NAM FORECAST SOUNDINGS CONTINUE TO SUGGEST MVFR CIGS DEVELOPING BY MID MORNING. WILL BE A LITTLE MORE OPTIMISTIC WITH THIS FORECAST BASED ON LATEST TRENDS IN OBS UPSTREAM AND KEEP CIGS BETWEEN 2 AND 3 KFT AND MOVING IN A LITTLE LATER BETWEEN 09Z AND 12Z. BECAUSE THE UPPER TROUGH AND SURFACE LOW ARE SLOW TO MOVE EAST...MODELS CONTINUE TO WRAP MOISTURE AROUND INTO NORTHEAST KS...SO WILL HOLD ONTO THE MVFR CIGS THROUGH 06Z. SEE DISCUSSION ABOVE FOR FURTHER DETAILS. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1138 PM CST THU DEC 27 2012 .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU THE MAIN AVIATION CONCERN WILL BE THE LOW MVFR CEILINGS EXPECTED THROUGH THE EARLY PORTION OF THE FORECAST PERIOD. DIFFICULT FORECAST OVERNIGHT...WITH MVFR CONDITIONS AT MOST LOCATIONS EXCEPT KICT/KCNU. WILL CONTINUE THE PESSIMISTIC FORECAST AT ALL TAF SITES...HAVING MVFR CEILINGS THROUGH MUCH OF THE FORECAST. DO NOT SEE AN AREA FOR THE CEILINGS TO IMPROVE MUCH UNTIL DRIER AIR FILTERS INTO THE LOW LEVELS BEHIND THE NEXT WAVE DURING THE DAY ON FRIDAY. THIS WILL LEAD TO ALL TAF SITES IMPROVING TO VFR CEILINGS WITH THE BKN-OVC SKIES CONTINUING. KETCHAM && .PREV DISCUSSION... /ISSUED 854 PM CST THU DEC 27 2012/ UPDATE... GONNA SEND OUT A QUICK UPDATE TO CHANGE MENTION OF FREEZING DRIZZLE POTENTIAL FOR SOUTHEAST KS...TO MORE OF A PATCHY FREEZING DRIZZLE CHANCE. NOT EXPECTING A WIDESPREAD FREEZING DRIZZLE EVENT...AS LATEST SHORT TERM MODEL SOUNDINGS NOT SHOWING NEAR ENOUGH SATURATION IN THE LOWEST 1000 FEET FOR A WIDESPREAD DRIZZLE CHANCE. BUT SOME SATURATION MAY EXIST IN THE 1000-3000 FOOT LAYER FOR SOME PATCHY DRIZZLE TO FORM...WHICH WOULD FREEZE ON CONTACT GIVEN THE FORECASTED BELOW FREEZING SFC TEMPS ACROSS SOUTHEAST KS. LATEST RUC SOUNDINGS ALSO SUGGEST SOME PATCHY FREEZING FOG JUST AHEAD OF THE SURFACE TROUGH AS IT PUSHES INTO SE KS BY AROUND 12Z/FRI. SO WILL MENTION THIS CHANCE AS WELL. NOT EXPECTING WIDESPREAD TRAVEL ISSUES...WITH MAINLY SOME BRIDGES AND OVERPASSES AFFECTED...SO WILL NOT ISSUE ANY KIND OF WINTER WEATHER ADVISORY HEADLINE. BUT WILL HIT IT HARD IN THE HAZARDOUS WEATHER OUTLOOK OR A SPECIAL WEATHER STATEMENT. KETCHAM PREV DISCUSSION... /ISSUED 543 PM CST THU DEC 27 2012/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU THE MAIN AVIATION CONCERN WILL BE THE LOW MVFR/IFR CONDITIONS EXPECTED THROUGH MUCH OF THE FORECAST PERIOD. DIFFICULT FORECAST TONIGHT...WITH MVFR CONDITIONS AT MOST LOCATIONS EXCEPT KCNU. WILL CONTINUE THE PESSIMISTIC FORECAST AT ALL TAF SITES...HAVING MVFR/IFR THROUGH MUCH OF THE FORECAST. WITH SOME IFR CEILINGS FOR KSLN AND KCNU AFTER FRI/05Z. NOT ALOT OF CONFIDENCE IN THIS IFR CLOUD DECK...AND COULD ACTUALLY SEE SOME LIFR CEILINGS DEVELOP. DO NOT SEE AN AREA FOR THE CEILINGS TO IMPROVE MUCH UNTIL DRIER AIR FILTERS INTO THE LOW LEVELS BEHIND THE NEXT WAVE DURING THE DAY ON FRIDAY. THIS WILL LEAD TO ALL TAF SITES IMPROVING TO VFR CEILINGS WITH THE BKN-OVC SKIES CONTINUING. KETCHAM PREV DISCUSSION... /ISSUED 312 PM CST THU DEC 27 2012/ DISCUSSION... TONIGHT-FRIDAY: UPPER TROUGH WILL CONTINUE PUSHING EASTWARD ACROSS THE CENTRAL PLAINS. THIS WILL ALLOW THE POLAR AIR TO PUSH BACK SOUTHEASTWARD ACROSS OUR FORECAST AREA. INITIAL PV ANOMALY IS ALREADY WELL NORTH OF THE AREA OVER NEBRASKA/SOUTH DAKOTA. MEASURABLE SNOW WILL THEREFORE REMAIN WELL NORTHEAST OF OUR AREA. ANOTHER PV ANOMALY WILL TRACK IN THE BASE OF THE TROUGH ACROSS THE SOUTHERN PLAINS TONIGHT INTO FRIDAY. WE DO EXPECT PRESENT AREA OF LOW CLOUDS NEAR AND NORTHWEST OF SURFACE LOW...TO CONTINUE TO WRAP BACK INTO OUR AREA OVERNIGHT INTO FRIDAY MORNING BEHIND THE LOW TRACK. THERE COULD BE PATCHY LIGHT FREEZING DRIZZLE/FOG DEVELOPING IN THE SOUTHEAST COUNTIES LATE TONIGHT/EARLY FRIDAY WITH SLIGHTLY DEEPER LOW-LEVEL MOISTURE IN THE SOUNDING DATA AND WEAK ISENTROPIC UPGLIDE...COINCIDENT WITH WEAK SOUTHERLY FLOW AHEAD OF THE COLD FRONT. HOWEVER...PROBABILITIES SEEM TO BE MORE OPTIMAL JUST TO OUR EAST/SOUTHEAST. BREEZY NORTHWESTERLY WINDS SHOULD HELP SCOUR OUT LOW CLOUDS FRIDAY WITH A CLEAR/COLD NIGHT SLATED FOR FRIDAY NIGHT. SATURDAY-SUNDAY: UPPER LOW WILL BE IN THE PROCESS OF DEVELOPING OVER THE SOUTHWEST...WHILE SURFACE POLAR HIGH SHIFTS EASTWARD OUT OF THE SOUTHERN PLAINS. RELATIVELY LIGHT WESTERLY COMPONENT SATURDAY WILL BACK TO SOUTH-SOUTHWESTERLY SATURDAY NIGHT WITH SPEEDS INCREASING TO BREEZY LEVELS SUNDAY. EXPECTING FULL SUNSHINE SATURDAY WITH PERHAPS SOME HIGH CLOUDS PUSHING IN FROM THE SOUTHWEST ON SUNDAY. OTHERWISE...EXPECTING MODERATING TEMPERATURES TO NEAR CLIMATOLOGY. MONDAY-THURSDAY: MEDIUM RANGE MODELS HAVE COME INTO AGREEMENT ON AN INITIAL SHORTWAVE/PV ANOMALY EJECTING OUT OF THE SOUTHWEST UPPER LOW...ACROSS KANSAS/OKLAHOMA MONDAY INTO MONDAY NIGHT. IN ADDITION...COLDER AIR ASSOCIATED WITH ENERGY IN THE NORTHERN BRANCH JET STREAM...WILL INFILTRATE SOUTHWARD THROUGH OUR AREA. A CONSERVATIVE CHANCE OF RAIN TO SNOW APPEARS REASONABLE AREA-WIDE...WITH RELATIVELY HIGHER PROBABILITIES IN THE SOUTHEAST COUNTIES. IF LATER MODEL RUNS CONTINUE TO SHOW THIS SCENARIO...PROBABILITIES OF PRECIPITATION WILL LIKELY BE INCREASED IN FORTHCOMING FORECASTS ESPECIALLY IN THE SOUTH. THE MAIN UPPER LOW MAY REMAIN SUPPRESSED OVER THE SOUTHWEST INTO MIDWEEK BASED ON THE ECMWF/CANADIAN WHILE LOW-LEVEL HIGH PRESSURE BUILDS INTO KANSAS. SO WILL MAINTAIN DRY FORECAST FOR TUESDAY-THURSDAY. TEMPERATURES ARE PROJECTED TO BE NEAR TO SLIGHTLY BELOW CLIMATOLOGY DURING THE PERIOD. FORECAST CONFIDENCE IS ONLY LOW-MEDIUM GIVEN THE GFS ENSEMBLES SHOW DECENT SPREAD/UNCERTAINTY IN BOTH THE NORTHERN BRANCH AND SOUTHERN BRANCH JETSTREAMS IN THE SPLIT UPPER PATTERN. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 17 30 12 40 / 10 10 0 0 HUTCHINSON 14 26 11 37 / 10 10 0 0 NEWTON 17 27 12 37 / 10 10 0 0 ELDORADO 19 29 11 38 / 10 10 0 0 WINFIELD-KWLD 22 32 13 40 / 10 10 0 0 RUSSELL 8 22 5 36 / 10 0 0 0 GREAT BEND 10 23 8 38 / 10 0 0 0 SALINA 14 24 9 35 / 10 10 0 0 MCPHERSON 14 26 10 36 / 10 10 0 0 COFFEYVILLE 25 34 16 39 / 10 10 0 0 CHANUTE 24 32 15 37 / 10 10 0 0 IOLA 24 31 16 36 / 10 10 0 0 PARSONS-KPPF 26 34 15 38 / 10 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1100 PM CST THU DEC 27 2012 .DISCUSSION... THE LATEST RAP AND NAM MODEL SOUNDINGS CONTINUE TO SUGGEST SOME MVFR CIGS MOVING IN BEHIND THE INVERTED TROUGH AXIS...ALTHOUGH A LITTLE BIT SLOWER THAN EARLIER RUNS. BECAUSE OF THIS AND THE OVERCAST SKIES LIKELY TO PERSIST THROUGH THE MORNING ACROSS THE AREA...HAVE ALREADY UPDATED THE FORECAST TO WARM MIN TEMPS UP A COUPLE DEGREES. ALSO THE RAP AND NAM SHOW LITTLE IF ANY VERTICAL MOTION WITHIN THE STRATUS DECK WITH ISENTROPIC SURFACES SHOWING DOWNGLIDE DEVELOPING BEHIND THE WIND SHIFT. WITH NO REAL LARGE SCALE OR MESOSCALE FORCING TO POINT TO...HAVE REMOVED POPS AND ONLY MENTIONED FLURRIES OR A SLIGHT CHANCE FOR FREEZING DRIZZLE. THIS WOULD LIKELY ONLY OCCUR FOR A BRIEF PERIOD OF TIME OVER ISOLATED SPOTS. && .AVIATION... OBS UPSTREAM HAVE SHOWN CIGS IMPROVING UPSTREAM AND BEHIND THE SURFACE TROUGH AXIS. HOWEVER RAP AND NAM FORECAST SOUNDINGS CONTINUE TO SUGGEST MVFR CIGS DEVELOPING BY MID MORNING. WILL BE A LITTLE MORE OPTIMISTIC WITH THIS FORECAST BASED ON LATEST TRENDS IN OBS UPSTREAM AND KEEP CIGS BETWEEN 2 AND 3 KFT AND MOVING IN A LITTLE LATER BETWEEN 09Z AND 12Z. BECAUSE THE UPPER TROUGH AND SURFACE LOW ARE SLOW TO MOVE EAST...MODELS CONTINUE TO WRAP MOISTURE AROUND INTO NORTHEAST KS...SO WILL HOLD ONTO THE MVFR CIGS THROUGH 06Z. SEE DISCUSSION ABOVE FOR FURTHER DETAILS. WOLTERS && .PREV DISCUSSION... /333 PM CST THU DEC 27 2012/ TONIGHT THROUGH FRIDAY...MAIN FOCUS FOR THE SHORT TERM IS ON THE IMPACTS OF THE PASSING UPPER LEVEL TROUGH TONIGHT THROUGH FRIDAY MORNING. AS OF 21Z...THE UPPER LEVEL TROUGH WAS SWEEPING ACROSS THE NORTHERN AND CENTRAL PLAINS WITH THE SURFACE LOW OVER NORTHEAST NEW MEXICO. THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM HAS GENERALLY STAYED NORTH OF THE KANSAS/NEBRASKA BORDER...WITH LIGHT SNOW BEING REPORTED ACROSS MUCH OF NEBRASKA THROUGH THE DAY. AN UPPER LEVEL RIDGE HAS BEGUN TO MOVE ONTO THE PACIFIC COASTLINE...WHICH WILL HELP TO PUSH THE TROUGH ALMOST DUE EAST OVER THE NORTHERN PLAINS THROUGH THE EVENING AND OVERNIGHT HOURS. SOME LIGHT PRECIPITATION MAY STILL BE ABLE TO SKIM ALONG THE KANSAS/NEBRASKA BORDER THIS EVENING AND OVERNIGHT WITH THIS EASTWARD MOVING SYSTEM. THE BIG QUESTION WITH REGARDS TO PRECIPITATION POTENTIAL WILL BE WITH THE AMOUNT OF AVAILABLE MOISTURE OVER THE CWA. MODEL SOUNDINGS SHOW THE LOW LEVELS BECOMING FAIRLY SATURATED UP TO AROUND 850MB OVERNIGHT ACROSS A MAJORITY OF THE CWA. THIS LOW LEVEL MOISTURE COMBINED WITH SOME WEAK ISENTROPIC LIFT MAY BE ENOUGH TO PRODUCE SOME PATCHY FREEZING DRIZZLE AND MAYBE A FEW FLURRIES. MODEL SOUNDINGS SHOW THE LOW LEVEL MOISTURE INCREASING GENERALLY BETWEEN 06Z-09Z AND REMAINING FAIRLY SATURATED THROUGH AROUND 15Z BEFORE GRADUALLY DRYING OUT INTO THE EARLY AFTERNOON HOURS AS THE TROUGH PASSES EAST OF THE AREA. ANY LIGHT SNOW SHOWERS THAT ARE ABLE TO CLIP EXTREME NORTHERN KANSAS ARE NOT EXPECTED TO PRODUCE MORE THAN A DUSTING OF ACCUMULATION...AND CURRENTLY DO NOT ANTICIPATE ANY ICE ACCUMULATIONS WITH THE PATCHY FREEZING DRIZZLE. WITH THE SURFACE LOW OVER NORTHEAST NEW MEXICO...A BOUNDARY STRETCHED INTO NORTH CENTRAL KANSAS THIS AFTERNOON AND WILL GRADUALLY SLIDE SOUTHWARD ACROSS THE CWA THROUGH THE EVENING HOURS...CAUSING WINDS TO SHIFT FROM SOUTHEAST TO NORTHWEST. THIS NORTHWESTERLY FLOW WILL LEAD TO CAA AND OVERNIGHT LOWS DROPPING INTO THE LOW/MID 20S OVER EAST CENTRAL KANSAS AND PLUMMETING INTO THE LOW/MID TEENS ACROSS NORTH CENTRAL AND CENTRAL KANSAS WHERE THE BOUNDARY HAS ALREADY MOVED THROUGH. THESE NORTHWESTERLY WINDS WILL PERSIST THROUGH FRIDAY AND COOL TEMPERATURES DOWN A BIT COMPARED TO TODAY...WITH AFTERNOON HIGHS RANGING FROM LOW 20S OVER NORTH CENTRAL KANSAS TO LOW 30S ACROSS EAST CENTRAL KANSAS. ACH FRIDAY EVENING THROUGH THURSDAY...UPPER LEVEL RIDGING BUILDS INTO THE CENTRAL PLAINS FOR THE WEEKEND WITH DRY CONDITIONS EXPECTED. NOT MUCH CHANGE WAS MADE TO THIS PERIOD AS MODELS ARE STILL IN AGREEMENT WITH LIGHT WINDS BACKING TO THE WEST AND SOUTHWEST BY SUNDAY AS A SURFACE TROUGH DEVELOPS OVER WESTERN KANSAS. THE TIGHTENING PRESSURE GRADIENT WILL INCREASE SOUTHWEST WINDS BOOSTING HIGHS TO THE LOW AND MID 40S ON SUNDAY. THE WARMER AIR WILL BE SHORT LIVED HOWEVER AS EXTENDED MODELS ARE BEGINNING TO PHASE TOGETHER ON MONDAY INTO MONDAY EVENING FOR THE NEXT TROUGH TO IMPACT THE CWA. AN OPEN H5 WAVE FROM THE SOUTHWEST LIFTS NORTHEAST INTO NEW MEXICO PHASING WITH A CANADIAN TROUGH DIGGING SOUTHWARD THROUGH THE NORTHERN PLAINS. A COLD FRONT WILL SURGE THROUGH THE AREA MONDAY DROPPING HIGHS BACK INTO THE 30S...POSSIBLY EVEN COLDER BUT HELD OFF LOWERING HIGHS TOO MUCH JUST YET. BOTH THE ECMWF AND GFS CARRY SUFFICIENT GULF MOISTURE NORTHWARD WITH SCATTERED LIGHT RAIN MIXED WITH SNOW...TRANSITIONING TO ALL SNOW BY MONDAY EVENING. UNCERTAINTIES IN SNOWFALL AMOUNT AND THE DISTURBANCE PLACEMENT ITSELF ARE TOO DIFFICULT TO DETERMINE ATTM...HOWEVER RESIDENTS SHOULD MONITOR THIS SYSTEM OVER THE UPCOMING DAYS WITH THE TIMING CURRENTLY ON NEW YEARS EVE. SURFACE HIGH PRESSURE RETURNS THROUGH THE REMAINING PERIOD WITH POSSIBLY A WEAK COLD FRONT AFFECTING THE AREA BY WEDNESDAY. HIGH TEMPERATURES REMAIN BELOW NORMAL IN THE LOW 30S THROUGH THURSDAY. BOWEN && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
149 AM CST FRI DEC 28 2012 .UPDATE... .DISCUSSION... SATELLITE WATER VAPOR AND THE RAP MODEL SHOW/SUGGEST SOME DRY AIR IS FILTERING INTO NORTHWEST NEBRASKA. KIEN DROPPED 8 DEGREES IN ONE HOUR. THE DRY AIR WILL ENHANCE RADIATIONAL COOLING ALLOWING TEMPS TO FALL WELL BELOW ZERO. A NEW FORECAST IS OUT FOR TEMPERATURES ACROSS NORTHWEST NEBRASKA. ALSO ADDED SCATTERED FLURRIES FOR THE SHORT WAVE MOVING THROUGH THE FCST AREA OVERNIGHT. && .PREV DISCUSSION... /ISSUED 1155 PM CST THU DEC 27 2012/ AVIATION... LOW PRESSURE SYSTEM CONTINUES TO PUSH ACROSS S DAKOTA...WITH WRAP AROUND MVFR CIGS AND LIGHT SNOW IMPACTING MUCH OF NORTHERN NEB OVERNIGHT. EXPECT BKN025 TO BKN050 TO CONTINUE TO IMPACT MUCH OF THE AREA EARLY TONIGHT...THEN LINGER OVER N CENTRAL TERMINALS INTO THE MORNING HOURS. HAVE INCLUDING MVFR CIGS FOR KVTN TERMINAL...HOWEVER CONFIDENCE IS MARGINAL. LIGHT SNOW OR FLURRIES TO ALSO IMPACT AREAS WITH THE LOWEST CIGS...ALTHOUGH VSBY SHOULD REMAIN VFR OR POSSIBLY BRIEFLY TO 4SM OR 5SM. IMPROVING CONDITIONS TO VFR FROM SOUTHWEST TO NORTHEAST DURING MORNING HOURS TOMORROW. LEADING TO WIDESPREAD VFR FOR THE AFTERNOON AND EVENING HOURS...ALTHOUGH WILL STILL BE SOME VFR HIGH CLOUDS IN THE AREA. PREV DISCUSSION... /ISSUED 309 PM CST THU DEC 27 2012/ SYNOPSIS... H5 TROUGH OVER WESTERN CONUS WITH CLOSED LOW OVER SOUTHEAST SOUTH DAKOTA AND ANOTHER OVER THE NORTHEAST US. STRONG RIDGE INTO THE PACIFIC NORTHWEST. DISCUSSION... UPPER LOW CONTINUES TO SPIN OVER SOUTHERN SOUTH DAKOTA WITH DEFORMATION ZONE BACK THROUGH NORTHERN NEBRASKA. AREAS OF LIGHT SNOW OR FLURRIES DIMINISHING. LOOKING AT THE BUFR SOUNDINGS DEEP SATURATED LAYER IN DENDRITIC ZONE AND WILL NOT TAKE MUCH LIFT TO GET FLURRIES OR LIGHT SNOW LATE THIS AFTERNOON AND EVENING. SOME SUN TRYING TO BREAK THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS HAVE LIGHT SNOW EAST OF A LINE FROM ALLIANCE TO LEXINGTON. HAVE KEPT MENTION OF LIGHT SNOW IN THE FORECAST OVER NORTHERN NEBRASKA THROUGH MIDNIGHT AND THEN OVER NORTH CENTRAL THROUGH FRIDAY MORNING. HAVE CUT BACK ON POPS A LITTLE BUT LOOKS TO BE A HIGH POP LOW PRECIP FORECAST SITUATION. 20 AND 25 TO ONE RATIOS HAVE BEEN COMMON TODAY. SKY FORECAST TRICKY. SOME BREAKS AS MENTIONED OVER SOUTHERN NEBRASKA. IF SKIES CLEAR 850MB TEMPERATURES BOTTOM OUT AROUND -14C AND SOME BELOW ZERO TEMPERATURES ALONG THE PLATTE RIVER VALLEY AND OVER THE NORTHWEST. SKIES TO BECOME PARTLY CLOUDY ON FRIDAY AND WITH WEST TO NORTHWEST DOWNSLOPE WINDS AND SOME SUN EXPECT TEMPERATURES TO ROCKET INTO THE LOW 20S TO THE WEST AND TEENS EAST. WILL NOT BE ABLE TO GO MUCH HIGHER THAN THIS DUE TO -12 850MB TEMPERATURES OVER HEAD. NORTHWEST WINDS AT 5 TO 15 MPH OVER NORTH CENTRAL NEBRASKA TOMORROW MAY CAUSE SOME DRIFTING ON EAST WEST SECONDARY ROADS. DO NOT BELIEVE THAT THERE SHOULD BE ANY RESTRICTIONS TO VISIBILITY. ANOTHER SECONDARY WAVE MOVES ACROSS THE NORTHEAST FRIDAY NIGHT WITH THE RIDGE AND WARMER AIR ALOFT BUILDING TO THE EAST THROUGH THE DAY SATURDAY AND SUNDAY. TEMPERATURES RISE TO THE 30S SATURDAY AND SUNDAY. HAVE KEPT THEM ON COOLER SIDE OF GUIDANCE WITH SNOW COVER AND POSSIBILITY OF FOG FREEZING FOG DEVELOPING OVER THE AREA WITH SNOW MELT. WILL ADDRESS THE POSSIBILITY DAY TO DAY. COOLER AIR TO BE DRAWN INTO FORECAST AREA MONDAY AS A PROGRESSIVE POSITIVELY TILTED TROUGH BRINGS ENERGY OUT OF THE FOUR CORNERS ONTO THE CENTRAL PLAINS. THE NEW ECMWF HAS BROUGHT THIS ENERGY FURTHER NORTH WITH THE LATEST RUN MORE IN LINE WITH THE GFS SOLUTION. HAVE LEFT DRY FOR NOW BUT WILL HAVE TO BE WATCHED. STRONG SOUTHERN STREAM JET 140KT+ WILL MOVE THIS SYSTEM ALONG. ECMWF STILL FORMING A CUTOFF LOW TUESDAY OVER SOUTHWEST CONUS AND MOVING IT ACROSS THE SOUTHERN PLAINS. THIS WOULD LEAVE THE FORECAST AREA DRY WITH TEMPERATURES NEAR NORMAL FOR THE SEASON 36. HYDROLOGY... ICE JAMMING ALONG THE NORTH PLATTE RIVER WILL LEAD TO MINOR FLOODING OF THE RIVER UPSTREAM OF LAKE MCCONAUGHY AND NEAR THE CITY OF NORTH PLATTE. DUE TO THE DYNAMIC NATURE OF ICE JAMMING...SUDDEN FLUCTUATIONS MAY OCCUR...ESPECIALLY SINCE AIR TEMPERATURES ARE FORECAST TO REMAIN COLD THROUGH SUNDAY MORNING. THE FLOOD WARNING CONTINUES FOR THE NORTH PLATTE RIVER NEAR LEWELLEN AND NORTH PLATTE. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/EXTENDED...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1129 PM CST THU DEC 27 2012 .AVIATION...06Z KGRI TAF. MVFR CONDITIONS EXPECTED THROUGH 16Z...WITH VFR CONDITIONS FORECAST 16Z ONWARD. STRATUS CONTINUES ACROSS THE AREA WITH CEILINGS GENERALLY IN THE 3000FT AGL TO 4000FT AGL RANGE. THERE IS A CHANCE CEILINGS COULD DROP BELOW 3000FT AGL AT KGRI...BUT GUIDANCE SUGGESTS CEILINGS WILL REMAIN ABOVE 3000FT AGL AND PLAY CLOSE TO THIS GUIDANCE IN THE TAF. VISIBILITY RESTRICTION TO AROUND 3SM IN LIGHT SNOW AND PERHAPS BR WILL ALSO PERSIST AT THE TERMINAL HEADING INTO FRIDAY MORNING...WITH UNRESTRICTED VISIBILITY CURRENTLY FORECAST 16Z ONWARD. THE SURFACE WIND WILL REMAIN LIGHT AND VARIABLE TONIGHT...BECOMING MORE ESTABLISHED FROM THE NORTHWEST AT AROUND 11KTS DURING THE DAY FRIDAY. && .PREV DISCUSSION... /ISSUED 707 PM CST THU DEC 27 2012/ UPDATE...MODEL INITIALIZATION FROM THE RAP AS OF 23Z INDICATES A WEAK LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS WITH MODEST RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY EXTENDS FROM WEST TEXAS...EAST/NORTHEAST INTO THE LOWER MISSISSIPPI VALLEY AND SOUTHEASTERN CONUS. TROPOSPHERIC FLOW OVER THE CENTRAL PLAINS REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT ~70KTS NEAR 300MB PER 23Z RAP ANALYSIS SOUNDING DATA FOR KGRI. WATER VAPOR IMAGERY INDICATES A MID LEVEL LOW OVER NORTHERN NEBRASKA AND SOUTHERN SOUTH DAKOTA...MOVING EAST/NORTHEAST. INCREASED VALUES OF MID LEVEL MOISTURE ARE ALSO NOTED OVER SOUTHERN PORTIONS OF THE CONUS...EXTENDING ALONG THE LEVEL JET AXIS. MID LEVEL MOISTURE FARTHER NORTHWEST HOWEVER...ACROSS OUR REGION...REMAINS FAIRLY MEAGER. AT THE SURFACE A STATIONARY BOUNDARY IS NOTED EXTENDING ACROSS PORTIONS OF CENTRAL AND EASTERN KANSAS AND AS OF 00Z WAS NOTED FROM NEAR KMHK...TO NEAR KHUT AND NEAR KICT. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE EAST/NORTHEAST AS A RESULT...WITH THE SOUTHEASTERLY LOW LEVEL WIND FIELD RELEGATED TO THE SOUTHEAST OF OUR AREA...SOUTHEAST OF THE LOW LEVEL BAROCLINIC ZONE. RAP DATA SUGGESTS THE PRIMARY AXIS OF MID LEVEL THERMAL ADVECTION AND DPVA HAVE DEPARTED OUR AREA TO THE NORTHEAST AND WITH AN OVERALL LACK IN OMEGA...SUBSTANTIAL SNOWFALL SHOULD BE HARD TO COME BY ACROSS OUR AREA THROUGH THE REST OF TONIGHT. THAT BEING SAID...THERMAL ADVECTION ACROSS THE AFOREMENTIONED LOW LEVEL BAROCLINIC ZONE IS PROMOTING ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY BETWEEN THE 275 AND 285K SURFACES. STRATUS HAS RESULTED ACROSS MUCH OF OUR AREA...WITH CEILINGS GENERALLY BETWEEN 1000 AND 3000FT AGL NOTED AS OF 00Z. SOUNDINGS FROM ACROSS THE CWA PER RAP ANALYSIS DATA SUGGESTS THIS STRATUS EXTENDS VERTICALLY TO NEAR 800MB...WITH THE TEMPERATURE NEAR 850MB JUST BARELY BREAKING INTO THE DENDRITIC ZONE AT AROUND -12 OR -13 C. PERIODIC SNOW FLURRIES HAVE BEEN NOTED ACROSS MUCH OF THE CWA THIS EVENING AS A RESULT. GIVEN THAT THE PRIMARY AXIS OF OMEGA HAS SHIFTED WELL NORTHEAST OF OUR AREA...OPTED TO REMOVE POPS FROM ACROSS THE CWA THROUGH THE REST OF TONIGHT...BUT ALSO EXTENDED ISOLATED FLURRIES ACROSS THE ENTIRE CWA TO ACCOUNT FOR THE CURRENT ACTIVITY. NOTHING MORE THAN TRACE AMOUNTS OF SNOWFALL ARE ANTICIPATED ACROSS THE CWA THROUGH TONIGHT. THERE ARE SOME INDICATIONS...IN PARTICULAR FROM THE NAM AND RAP...THAT LOWER TROPOSPHERIC RH VALUES COULD BE HIGH ENOUGH FOR THE DEVELOPMENT OF PATCHY FOG LATER TONIGHT...ESPECIALLY AS TEMPERATURES NEAR 850MB WARM SLIGHTLY...AS SUGGESTED BY THE NAM AND RAP...THUS MOVING THE CURRENT STRATUS LAYER OUT OF THE DENDRITIC ZONE. IT APPEARS THE MOST LIKELY AREA TO OBSERVE SUCH DEVELOPMENT WOULD BE ACROSS OUR SOUTHEASTERN CWA WHICH IS WHERE THE HIGHEST LOWER TROPOSPHERIC MOISTURE WILL RESIDE. CONTEMPLATED ADDING LIGHT FREEZING DRIZZLE TO THE GRIDS FOR TONIGHT AS IT APPEARS AS THOUGH 0-0.5KM RH VALUES WILL ALSO BE VERY HIGH...NOT JUST AT THE SURFACE. THAT BEING SAID...THE RAP AND NAM BOTH SUGGEST LOW LEVEL TURBULENT MIXING WILL REMAIN VERY WEAK WITH 0-0.5KM BULK SHEAR UNDER 10KTS THROUGH MUCH OF THE NIGHT...THUS MAKING FOG PRODUCTION THE MORE LIKELY SCENARIO. GIVEN ALL THIS...WENT AHEAD AND INSERTED PATCHY FREEZING FOG TO THE GRIDS FOR OUR SOUTHEASTER CWA FOR TONIGHT. THE VISIBILITY AT LOCATIONS SUCH AS KK61 AND KCNK HAVE DROPPED TO AROUND 5SM AT TIMES THIS EVENING AND THIS IS A TREND WHICH WILL NEED TO BE MONITORED. PREV DISCUSSION... /ISSUED 343 PM CST THU DEC 27 2012/ SHORT TERM...TONIGHT THROUGH FRIDAY. MAIN CHALLENGE WILL BE DETERMINING CHANCES OF SNOW TONIGHT. TROUGH AXIS HAS YET TO CROSS TO THE EAST...BUT MOST OF THE ENERGY RESPONSIBLE FOR ACCUMULATING SNOW HAS SHIFTED NORTH. THEREFORE CUT BACK CHANCES OF PRECIPITATION CONSIDERABLY...YET KEPT WIDESPREAD FLURRIES FOR MOST OF THE CWA THIS EVENING...WITH LINGERING SCATTERED FLURRIES OVERNIGHT AS THE TROUGH AXIS FINALLY MAKES ITS WAY TO THE EAST OF THE CWA OVERNIGHT. SURFACE HIGH BUILDS IN FOR FRIDAY...BUT STRATUS IS FORECAST TO BE STUBBORN TO LEAVE. STILL A LOT OF COLD AIR AROUND WITH SNOW ON THE GROUND AND CLOUDY SKY...THIS WILL ADD UP TO A COLDER THAN NORMAL DAY. YANKED FREEZING DRIZZLE FROM THE SOUTHEASTERN CWA AS TEMPERATURES SHOULD BE A LITTLE TOO COLD AT THE TOP OF THE LOW-LEVEL SATURATION LAYER TO ALLOW SUPERCOOLED WATER TO REMAIN...WITH PERHAPS SNOWGRAIN TYPE PRECIPITATION IF ANYTHING THIS EVENING. ALL IN ALL...MOST OF ANY APPRECIABLY ACCUMULATING SNOW HAS ENDED FOR THE CWA. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. BEGINNING FRIDAY NIGHT...AN UPPER TROUGH AXIS EXITS THE NORTHERN AND CENTRAL PLAINS. MODELS INDICATE POTENTIAL FOR LOW CLOUDS/STRATUS LINGERING ACROSS OUR EASTERN ZONES FOR A FEW HOURS DURING THE EVENING...THEN CLOUDS LOOK TO DEPART BY MIDNIGHT WITH DEPARTING TROUGH AND HEIGHTS RISES WHILE DOWNSLOPE LLVL FLOW DEVELOPS. THE COLD AIRMASS BEGINS TO DISLODGE ON SATURDAY AS AN INTERMOUNTAIN RIDGE EXPANDS EASTWARD ONTO THE PLAINS WITH WARMING AIDED BY A WESTERLY DOWNSLOPE WIND COMPONENT. THE SHORTWAVE RIDGE AXIS BREAKS DOWN HEADING INTO SUNDAY AS AN UPSTREAM TROUGH CROSSES THE NORTHERN PLAINS. THE ASSOCIATED COLD FRONTAL PASSAGE ASSOCIATED WITH THIS NEXT TROUGH HOLDS OFF UNTIL SUNDAY AFTN/EVE SO SUNDAY IS STILL LOOKING LIKE THE WARMEST DAY OF THE NEXT SEVERAL DAYS AHEAD OF THIS NEXT COLD FRONT. WILL AIM FOR HIGHS RIGHT AROUND 30 DEGREES WITH SOME MID/UPPER 30S IN NC KANSAS WHERE SNOW PACK/DEPTH IS NOT AS MUCH OF AN ISSUE. WILL NEED TO MONITOR FOR POTENTIAL FOG DEVELOPMENT IF WE CAN GET SOME DECENT MELTING OF THE SNOW. A 1030MB TO 1035MB SFC HIGH...WITH THE STRENGTH DEPENDENT UPON THE MODEL...BUILDS SOUTH BEHIND THE FRONT SUNDAY NIGHT INTO MONDAY AND SETTLES IN UNTIL AROUND THE TUESDAY TIME FRAME WITH A GENERAL COLD WINTER AIRMASS IN PLACE. A FEW DAYS AGO MODELS WERE INDICATING MUCH COLDER ARCTIC AIR THAN WHAT IS SUGGESTED AT THIS TIME NOW. EXTENDED MODELS DIVERGE EARLY TO MID WEEK OF NEXT WEEK WITH HANDLING OF SOUTHWEST CONUS SYSTEM WITH ECMWF STRONGER THAN THE MORE PROGRESSIVE GFS...AND CLOSES OFF THE SYSTEM VS GFS OPEN WAVE. CONFIDENCE LOWERS BY MID WEEK OF NEXT WEEK DUE TO MODEL DIFFERENCES AND WILL MAINTAIN STATUS QUO FOR TEMPS AND NOT SWING WARMER/COOLER OR WETTER UNTIL MODELS COME INTO BETTER AGREEMENT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE/AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...FAY
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
331 AM CST FRI DEC 28 2012 .SHORT TERM... SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL. WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM. BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED. AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE. .LONG TERM... AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF 2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE FIRST PART OF JANUARY. && .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 42 33 35 24 / 90 100 30 05 CLARKSVILLE 39 30 34 22 / 90 100 20 05 CROSSVILLE 45 34 34 22 / 70 100 30 20 COLUMBIA 43 33 36 24 / 100 90 20 05 LAWRENCEBURG 44 33 36 24 / 100 90 20 05 WAVERLY 39 30 34 22 / 100 90 20 05 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHAMBURGER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
332 AM MST FRI DEC 28 2012 .SHORT TERM...NW FLOW ALOFT WILL BE OVER THE AREA AS A DISTURBANCE MOVES ACROSS THE MTNS THIS AFTN. OVERALL MOISTURE DEPTH IN THE MTNS IS NOT THAT DEEP HOWEVER WITH FAVORABLE OROGRAPHIC FLOW WILL CONTINUE TO SEE SOME LIGHT SNOW. AT LOWER ELEVATIONS EXPECT DRY CONDITIONS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER ACROSS NERN CO WITH READINGS IN THE MID 20S OVER THE FAR NERN PLAINS WITH LOWER TO MID 30S NEAR DENVER. SOME GUSTY WINDS WILL OCCUR IN THE HIGHER MTNS AND HIGHER FOOTHILLS THIS AFTN INTO THE EVENING HOURS BUT SPEEDS WILL STAY WELL BLO HIGH WIND CRITERIA. FOR TONIGHT MOISTURE WILL DECREASE IN THE MTNS WITH LIGHT SNOW ENDING BY MIDNIGHT. .LONG TERM...MODELS SHOW A FAIRLY HIGH AMPLITUDE SHORT WAVE RIDGE TO MOVE EASTWARD ACROSS COLORADO ON SATURDAY. BY SATURDAY NIGHT... PRETTY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE CWA. ON SUNDAY...STRONG SOUTHWESTERLY FLOW ALOFT IS OVER THE CWA. IN FACT THERE IS A 150-170 KNOT JET MAXIMUM STRETCHED FROM SOUTH CENTRAL COLORADO TO THE NORTHEAST CORNER OF THE STATE AT 00Z LATE SUNDAY AFTERNOON. BY 12Z MONDAY MORNING...THE FLOW ALFOT IS SOUTH- SOUTHWESTERLY AND LIGHTER AS AN UPPER TROUGH AXIS IS JUST WEST OF THE COLORADO WESTERN BORDER. THE SYNOPTIC SCALE ENERGY IS DOWNWARD SATURDAY...THEN UPWARD SATURDAY NIGHT THROUGH SUNDAY NIGHT. AT 12Z MONDAY MORNING...THE MODELS AGREE PRETTY WELL ON A FAIRLY STRONG UPWARD Q-G ASCENT OVER NORTH CENTRAL NEW MEXICO. THE UPWARD VERTICAL VELOCITY PROGGED FOR OUR CWA IS FAIRLY WEAK AT THAT TIME. THE PROGGED BOUNDARY LAYER FLOW FOR THE CWA THROUGH MUCH OF THE PERIOD IS DOMINATED BY DOWNSLOPING. THERE IS SOME WEAK UPSLOPE PROGGED SUNDAY NIGHT FOR THE PLAINS AND LOWER FOOTHILLS. FOR MOISTURE...SATURDAY AND SATURDAY NIGHT LOOK PRETTY DRY...JUST SOME UPPER LEVEL MOISTURE PROGGED HERE AND THERE. MOISTURE INCREASES FROM THE WEST ON SUNDAY...ESPECIALLY DURING THE AFTERNOON. BY SUNDAY NIGHT MOISTURE IS DEEP OVER THE MOUNTAINS AND FOOTHILLS. THERE IS QUITE A BIT IN THE MID AND UPPER LEVELS OF THE PLAINS AS WELL. THE QPF FIELDS START TO BRING IN MEASURABLE PRECIPITATION TO THE MOUNTAINS BY SUNDAY AFTERNOON. THERE ARE LIMITED AMOUNTS OVER THE MOUNTAINS AND FOOTHILLS SUNDAY NIGHT. FOR POPS IN THE MOUNTAINS...WILL START SOME MINOR ONES UP BY SUNDAY AFTERNOON... AND WILL GO WITH "CHANCE"S IN THE HIGH MOUNTAINS SUNDAY NIGHT. OROGRAPHICS ARE NOT GOOD AND THE SYNOPTIC SCALE ENERGY IS MEAGER ...BUT THERE IS PLENTY OF MOISTURE. NO POPS FOR THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 2-4 C WARMER THAN TODAY`S. SUNDAY`S HIGHS ARE SIMILAR TO SATURDAY`S. FOR THE LATER DAYS... MONDAY THROUGH THURSDAY...THE UPPER TROUGH AXIS MOVES INTO COLORADO ON MONDAY...BUT IT IS SLOW AND WEAKENING AND SOMEWHAT DEVELOPING BACK INTO A MORE EAST-WEST ORIENTATION. THE UPPER LEVEL WIND SHIFT DOESN`T GET THROUGH THE CWA UNTIL TUESDAY NIGHT ON BOTH THE GFS AND ECMWF. BY WEDNESDAY AT 12Z...BOTH OF THOSE MODELS HAVE AN UPPER CLOSED LOW OVER THE SOUTHERN BORDER OF ARIZONA AND NEW MEXICO. THIS IS SLOWER THAN YESTERDAY`S 00Z MODEL RUNS INDICATED. SO THE FLOW ALOFT ON WEDNESDAY IS NORTHERLY FOR THE CWA. BY THURSDAY...THERE IS UPPER RIDGING OVER THE CWA...BUT THE LOOK OF IT AND TIMING DIFFERS BETWEEN THE ECMWF AND THE GFS. MOISTURE IS PRETTY DEEP MONDAY AND MONDAY NIGHT...MORE SO ON THE ECMWF. THE ECMWF ALSO HAS PRETTY DEEP MOISTURE OVER THE PLAINS...THE GFS DOES NOT. THE GFS GETS DRY AFTER THAT ALL THE WAY THROUGH THURSDAY. THE ECMWF IS DRY LATER ON TUESDAY INTO EARLY THURSDAY...THEN MOISTURE RETURNS...ESPECIALLY FOR THE MOUNTAINS BY THURSDAY. SO WILL KEEP SOME POPS IN MONDAY AND MONDAY NIGHT...THEN NOTHING AFTER THAT FOR NOW. TEMPERATURES LOOK TO STAY BELOW SEASONAL NORMALS ALL FOUR DAYS. && .AVIATION...THERE WAS SOME FOG AND LOW CLOUDS OVER WELD COUNTY EARLY THIS MORNING WITH SOME DENSE FOG REPORTED NR BRIGHTON. HOWEVER WEB CAMS ALONG E470 NR BRIGHTON DO NOT SHOW ANY FOG. FOR NOW IF LOW LVL WINDS STAY SSW LOW CLOUDS AND FOG SHOULD STAY TO THE NORTH OF THE AIRPORT. THUS WILL KEEP CONDITIONS VFR IN THE TAF. AS FAR AS WINDS LATEST HRRR SHOWS WINDS BECOMING MORE WNW BY EARLY AFTN AS GUSTY WINDS IN THE FOOTHILLS MIX DOWN TO THE SFC WITH SPEEDS IN THE 10-15 MPH RANGE. BY EARLY EVENING WINDS MAY GO MORE WLY AND THEN BACK TO SSW BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM....RJK AVIATION...RPK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1000 AM EST FRI DEC 28 2012 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 333 AM EST FRI DEC 28 2012 HIGH PRESSURE OVER CENTRAL INDIANA WILL BE FOLLOWED BY A WEAK COLD FRONT THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE IS FORECAST TO RETURN FOR THE WEEKEND. MONDAY ANOTHER COLD FRONT IS EXPECTED TO CROSS OUR STATE. AFTER THAT...HIGH PRESSURE WILL TAKE CHARGE AGAIN FOR SEVERAL DAYS. MUCH COLDER AIR WILL ARRIVE OVER THE REGION LATE NEXT WEEK...WITH LOW TEMPERATURES DROPPING INTO THE SINGLE DIGITS. && .NEAR TERM /TODAY/... ISSUED AT 1000 AM EST FRI DEC 28 2012 NEITHER RUC NOR HRR BRING IN ANY QPF TIL AFTER 00Z...WHICH LINES UP WELL WITH MAV AND ECM POPS. WILL DROP POPS BELOW 15 MOST AREAS. PLAN TO RETAIN THEM SOUTHWEST BUT MAKE THEM LOWER AND INDICATE ANY PCPN COMING IN QUITE LATE. TEMPERATURES LOOKING GOOD FOR THE MOST PART. BUT DID MAKE MINOR TWEAKS BASED ON LATEST OBS. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... ISSUED AT 333 AM EST FRI DEC 28 2012 FORECAST FOCUS WAS ON SNOW FORECAST FOR TONIGHT PERIOD. LATEST MODEL RUNS SHOW BETTER MOISTURE AND LIFT ACROSS THE OHIO VALLEY FROM 00-12Z. THE GFS AND GEM ESPECIALLY ARE DEPICTING MUCH HIGHER MOISTURE AMOUNTS OF OVER FOUR TENTHS OF AN INCH ACROSS THE FAR SE COUNTIES...WHILE THE NAM STICKS TO AROUND A TENTH. THE LATEST EURO APPEARS TO TAKE A BLEND OF THE THE DIFFERING SOLUTIONS...PLACING AROUND TWO TO THREE TENTHS OF AN INCH OF QPF ACROSS THE SE COUNTIES...WHICH SEEMS MORE REASONABLE AND IN LINE WITH HPC GUIDANCE. TRENDED FORECAST WITH HIGHER POPS...ESPECIALLY ACROSS THE SOUTH AND EAST WHERE THIS FEATURE WILL MOVE CLOSEST TO. TOTAL SNOWFALL AMOUNTS WILL RANGE FROM 0.5-1.0 INCHES NORTHWEST...TO 2 TO 3 INCHES SOUTHEAST. ADVISORY CRITERIA IS 4 INCHES...SO OPTED NOT TO ISSUE ONE AT THIS TIME AND PLAN ON SENDING OUT AN SPS. PRECIP TYPE DOES NOT LOOK TO BE AN ISSUE FOR TONIGHT AND SHOULD BE ALL SNOW. SYSTEM STILL LOOKS FAIRLY PROGRESSIVE AND SHOULD BE MOVING AWAY FROM THE FORECAST AREA...HOWEVER A FEW SHOW SHOWERS AND/OR FLURRIES MAY LINGER ON THE BACK SIDE OF LOW. WIDESPREAD CLEARING DOES NOT BEGIN UNTIL SATURDAY NIGHT. HIGH PRESSURE AND DRIER WEATHER WILL BE THE RULE FOR THE REST OF THE PERIOD. && .LONG TERM /MONDAY THROUGH THURSDAY/... ISSUED AT 333 AM EST FRI DEC 28 2012 FORECAST FOCUS IS ON CHANCES FOR SNOW MONDAY THROUGH TUESDAY. MODELS AND ENSEMBLES ARE SHOWING A DECENT AMOUNT OF VARIABILITY BY MONDAY AND SAW NO REASON TO CHANGE FROM ALLBLEND. A CLIPPER TYPE SYSTEM WILL MOVE ACROSS ONTARIO INTO QUEBEC AND POSSIBLY BRING A COLD FRONT THROUGH ON MONDAY WHICH COULD PROMPT CHANCES FOR SNOW. MONDAY NIGHT A LOW FORMS IN THE SOUTHERN PLAINS AND TRACKS NORTHEAST INTO TUESDAY. RIGHT NOW OPERATIONAL GFS AND ECMWF FAVOR A TRACK ACROSS WESTERN TENNESSEE AND THROUGH EASTERN KENTUCKY WHICH WOULD FAVOR HIGH POPS FOR THE SOUTH AND CENTRAL COUNTIES...BUT THE MAJORITY OF THE ENSEMBLE MEMBERS TRACK THIS LOW QUITE A BIT FURTHER SOUTH WHICH WOULD BE MUCH LESS FAVORABLE. THUS THE ALLBLEND CHANCE POPS WITH THE HIGHEST NUMBERS IN THE SOUTH LOOK GOOD FOR NOW AND A COMPROMISE. THERMAL PROFILES IN THE SOUTH INDICATE POTENTIAL FOR SOME MIXED PRECIP AND WILL KEEP THE RAIN SNOW MIX IN THE SOUTH MONDAY AFTERNOON FROM PREVIOUS FORECAST. WILL HAVE TO CONTINUE TO MONITOR PRECIP TYPE WITH UPCOMING FORECASTS FOR THIS TIME. BY TUESDAY NIGHT HIGH PRESSURE BUILDS IN AND SHUTS DOWN SNOW CHANCES FOR THE REST OF THE EXTENDED. WITH SNOW COVER CONTINUING AND COLD AIR INTRUSIONS MAKING THEIR WAY FURTHER SOUTH WITH THE FRONTAL PASSAGE SHOULD SEE BELOW NORMAL TEMPERATURES AFTER MONDAY. && .AVIATION /DISCUSSION FOR 281500 TAF UPDATE/... ISSUED AT 925 AM EST FRI DEC 28 2012 MVFR CONDITIONS WILL CONTINUE. DID LOWER CEILINGS TO BELOW 2000FT BASED ON CURRENT CONDITIONS AND UPSTREAM OBSERVATIONS. COULD STILL RISE ABOVE 2000FT FOR A TIME THIS AFTERNOON. SNOW STILL LOOKS TO HOLD OFF TILL AFTER 00Z. PREVIOUS DISCUSSION FOLLOWS... MVFR CEILINGS WILL REMAIN THROUGHOUT THE DAY TODAY BEFORE DROPPING TO IFR TONIGHT WITH THE ARRIVAL OF SOME SNOW. COULD SEE SOME FLURRIES BEFOREHAND BUT EXPECT SNOW OF ANY IMPACT TO THE SITES WON/T COME IN UNTIL AFTER 0Z. KLAF COULD BE NORTH ENOUGH TO AVOID SNOW ALTOGETHER BUT CONTINUED WITH A FLURRY MENTION THERE. SNOW SHOULD MOVE OUT OF THE AREA BY SATURDAY MORNING...AND AFTER THE SNOW GUIDANCE SHOWS MVFR TO IFR VISIBILITIES AND CEILINGS REMAINING AND AGREE WITH THIS BASED ON LIGHTER WINDS AND A LOW PRESSURE TO THE SOUTH. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMF NEAR TERM...JK SHORT TERM...SMF LONG TERM....CP AVIATION...CP/50
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
554 AM CST FRI DEC 28 2012 .UPDATE... 12Z SOUNDING...CURRENTLY UNDERWAY...SO FAR CONTINUES TO SHOW A DRY LAYER IN THE 800-850MB LAYER WHICH IS RESULTING IN MORE VIRGA THAN PRECIPITATION. RADAR RETURNS THE PAST HOUR HAVE LIT UP WITH RETURNS GENERALLY TO THE NORTH AND WEST OF THE QUAD CITIES. THESE RETURNS INDICATE THE DRY LAYER IS SATURATING. RECENT RAP TRENDS SHOW STRONG FORCING OVER THE NORTHERN CWFA. THE DRY 800-850MB LAYER IS PREVENTING PRECIPITATION THERE BUT SAID LAYER IS CLOSER TO SATURATION OVER THE WESTERN HALF. THIS FORCING EXITS THE AREA BY MID MORNING LEAVING WEAK TO NEUTRAL LIFT BUT MORE OF A SATURATED ATMOSPHERE. THUS THERE MAY BE A BRIEF SHOT OF VERY LIGHT SNOW ONCE SATURATION IS ACHIEVED BEFORE GOING BACK TO FLURRIES. BY MID DAY THE RAP IS SHOWING VERY STRONG FORCING MOVING NORTH OUT OF MISSOURI ASSOCIATED WITH A VORT MAX. IF CORRECT...THIS FORCING SHOULD ALLOW LIGHT SNOW TO BREAK OUT ACROSS THE CWFA BEFORE IT EXITS INTO MN/WI BY MID AFTERNOON. HOWEVER...BY THIS TIME THE INVERTED TROF IS COMING INTO PLAY SO LIGHT SNOW SHOULD CONTINUE ACROSS THE CWFA INTO LATE AFTERNOON/EVENING. AMOUNTS ARE STILL QUESTIONABLE BUT THE INITIAL 0.5 TO 1 INCH ALONG/NORTH OF HWY 30 STILL LOOKS REASONABLE. THE TRACE TO 0.5 INCH SOUTH OF HWY 30 MAY BE OVERLY GENEROUS BUT THERE SHOULD BE AT LEAST A DUSTING DOWN TO THE I-80 CORRIDOR. AN UPDATE REFLECTING THESE TRENDS SHOULD BE AVAILABLE WITHIN 30 TO 60 MINUTES. ..08.. && .AVIATION... A LAYER OF DRY AIR FROM 4.5 TO 6.0 KFT AGL IS HOLDING BACK THE DEVELOPMENT OF -SN. RADAR RETURNS DO SHOW SATURATION TAKING PLACE SO MVFR/VFR CONDITIONS SHOULD CONTINUE AT KDBQ/KCID WITH VFR AT KMLI/KBRL. RAP MODEL TRENDS INDICATE STRONG FORCING MOVING NORTH OUT OF MISSOURI BY 18Z/28 WHICH SHOULD SATURATE THE ATMOSPHERE AND ALLOW -SN TO DVLP. THUS EXPECT CONDITIONS TO DETERIOTE TO IFR AND POSSIBLY LIFR. KCID/KDBQ WILL HAVE THE BETTER CHANCES AT LIFR. CONDITIONS TO SLOWLY IMPROVE TO MVFR AFT 03Z/29. ..08.. && .PREV DISCUSSION... /ISSUED 304 AM CST FRI DEC 28 2012/ SYNOPSIS... 06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KEMP WITH A DIFFUSE FRONT RUNNING ACROSS NORTHERN MISSOURI AND INTO SOUTHERN ILLINOIS. A WEAK TROF RAN FROM NORTHEAST IOWA INTO NORTHERN INDIANA WHILE AN INVERTED TROF RAN FROM THE KANSAS LOW INTO THE EASTERN DAKOTAS. DEW POINTS WERE IN THE TEENS AND 20S ACROSS MUCH OF THE MIDWEST WITH 30S AND 40S IN THE SOUTHERN PLAINS AND DEEP SOUTH. SHORT TERM...TODAY AND TONIGHT... BASED ON SFC REPORTS...THE RADAR RETURNS ARE INDICATING MORE VIRGA THAN WHAT IS ACTUALLY REACHING THE GROUND. THE MECHANISM FOR GENERATING THE -SN IS NOT OBVIOUS BUT APPEARS TO BE TIED TO THE NARROW LAYER OF DRY AIR ON THE 00Z SOUNDING. RAP TRENDS ALONG WITH THE OTHER MODELS INDICATE SATURATION IN THE 800-850MB LAYER WILL OCCUR DURING THE DAY ALLOWING CONDENSATION PRESSURE DEFICITS IN THIS LAYER TO COLLAPSE. ALTHOUGH THE FORCING IS NOT GREAT IT WILL BE ENOUGH TO GENERATE LIGHT SNOW. THE INVERTED TROF COMPLICATES THINGS FURTHER SINCE INVERTED TROFS ARE NOTORIOUS FOR SURPRISES. BASED ON RAP TRENDS SAID INVERTED TROF WILL SLOWLY MOVE ACROSS THE CWFA DURING THE DAY. THUS THE BETTER SNOW SHOULD BE SEEN IN ADVANCE AND IMMEDIATELY AROUND THE INVERTED TROF WITH PRECIPITATION INTENSITY DECREASING ONCE THE INVERTED TROF GOES BY. TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BEFORE SLOWLY TAPERING OFF. VERY LIGHT SNOW OR FLURRIES IS EXPECTED TO CONTINUE UNTIL NEARLY SUNRISE. MOISTURE IS LIMITED AND THE MAIN FORCING FEATURES ARE ALSO QUITE WEAK. HOWEVER...ADDING THE INVERTED TROF TO EVERYTHING SHOULD RESULT IN MEASURABLE SNOWFALL ACROSS A MAJORITY OF THE CWFA. AMOUNTS OF 0.5 TO 1 INCH SHOULD BE SEEN FROM ABOUT HWY 30 ON NORTH WITH A TRACE TO 0.5 INCHES OF ACCUMULATION SOUTH OF HWY 30. ..08.. LONG TERM...SATURDAY THROUGH THURSDAY... THE BULK OF THE LIGHT SNOW SHOULD BE EAST OF THE FORECAST AREA EARLY SATURDAY MORNING. HOWEVER...MODELS ARE SHOWING A SECOND SHORT WAVE OVER WESTERN IOWA/MISSOURI EARLY SATURDAY. HAVE HELD ONTO SOME FLURRIES IN THE EAST WITH THIS MID LEVEL FEATURE MOVING THROUGH BY 18Z SATURDAY. COLD TEMPERATURES WILL OVERSPREAD THE AREA SATURDAY NIGHT WITH SURFACE AND UPPER RIDGING MOVING THROUGH THE REGION. MODELS ARE SUGGESTING THAT THE SURFACE RIDGE AXIS WILL BE OVER THE FORECAST AREA AT 06Z AND EAST OF THE CWFA BY 12Z SO WE SHOULD SEE SOME LIGHT RETURN FLOW DEVELOPING AFTER MIDNIGHT. WITH SOUTH WINDS DEVELOPING LATE...KEPT OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE ZERO NORTH TO AROUND 15 IN THE FAR SOUTH. FOR THE BEGINNING OF THE WORK WEEK A SOUTHERN STREAM SYSTEM WILL MOVE OUT OF THE SOUTHWEST U.S. INTO THE LOWER MISSISSIPPI VALLEY MONDAY AND MONDAY NIGHT. THE NORTHERN EDGE OF THE PRECIPITATION SHIELD IS PROGGED TO BRUSH THE SOUTHERN COUNTIES MONDAY AND MONDAY NIGHT. TEMPERATURES WILL BE COLD ENOUGH FOR THIS PRECIPITATION TO BE ALL SNOW. HOWEVER...THE SNOW WILL BE LIGHT AND SHOULD NOT AMOUNT TO MUCH ACCUMULATION BY TUESDAY MORNING. NORTHWEST FLOW DEVELOPS OVER THE UPPER MIDWEST BY LATE TUESDAY WITH GOOD AGREEMENT AMONG THE LONG RANGE MODELS ON A SHORT WAVE DROPPING SOUTHEAST THROUGH REGION WEDNESDAY NIGHT AND THURSDAY. THE SYSTEM WILL BE ENCOUNTERING A DRY AIRMASS AND SHOULD NOT PRODUCE ANY PRECIPITATION. HOWEVER IT WILL DRAG A COLD AIRMASS SOUTH INTO THE MID MISSISSIPPI VALLEY BY THURSDAY. HAVE OPTED FOR THE COLDER GUIDANCE FOR THURSDAY/S TEMPERATURES. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
656 AM CST FRI DEC 28 2012 .AVIATION DISCUSSION... FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...WITH A WARM FRONT SPOKING SOUTHEAST THROUGH LAFAYETTE ...AND A COLD FRONT SPOKING SOUTH THROUGH BEAUMONT. THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE WESTERN UPPER GULF COAST STATES THIS AFTERNOON. PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT. && .PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/ DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR. LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT 850 MB TRANSPORTING IN VERY MOIST AND WARM AIR. TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF. LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST TO EAST ACROSS THE AREA. VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT. 0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM TOWARD A SEVERE THREAT. RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER ACADIANA. WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY SEE OUR COOLEST MORNING THIS SEASON SUNDAY. REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE NEXT FEW DAYS. MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING ..WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 69 38 53 30 55 / 80 10 0 0 0 KBPT 68 36 51 31 54 / 80 10 0 0 0 KAEX 63 35 49 27 53 / 80 10 0 0 0 KLFT 72 41 52 30 55 / 80 20 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM. SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: VERMILION BAY. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
449 AM CST FRI DEC 28 2012 .DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR. LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT 850 MB TRANSPORTING IN VERY MOIST AND WARM AIR. TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF. LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST TO EAST ACROSS THE AREA. VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT. 0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM TOWARD A SEVERE THREAT. RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER ACADIANA. WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY SEE OUR COOLEST MORNING THIS SEASON SUNDAY. REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE NEXT FEW DAYS. && .MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING ...WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 69 38 53 30 55 / 80 10 0 0 0 KBPT 68 36 51 31 54 / 80 10 0 0 0 KAEX 63 35 49 27 53 / 80 10 0 0 0 KLFT 72 41 52 30 55 / 80 20 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM. SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: VERMILION BAY. && $$ MARCOTTE
AREA FORECAST DISCUSSION
NWS TULSA OK
907 AM CST FRI DEC 28 2012 .DISCUSSION... THE BULK OF THE WARM CONVEYOR PRECIP IN ADVANCE OF AN APPROACHING UPPER TROUGH HAS SHIFTED EAST OF THE FORECAST AREA INTO ARKANSAS. A WELL DEFINED PV MAX WAS EVIDENT ON WV IMAGERY OVER WESTERN OK...AND A BAND OF SNOW HAS DEVELOPED OVER CENTRAL OK MOVING EAST. I HAVE INSERTED SOME AFTERNOON POPS INTO THE FORECAST FOR SNOW AND WILL ADJUST THE FORECAST AS NEEDED LATER TO SEE HOW THINGS EVOLVE. THE LATEST HRRR HAS ANOTHER BAND DEVELOPING OVER FAR EASTERN OK OR FAR WESTERN AR THIS AFTERNOON AS WELL. LACY && .PREV DISCUSSION... /ISSUED 530 AM CST FRI DEC 28 2012/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. IFR TO LIFR CONDITIONS IN DRIZZLE AND FOG WILL AFFECT SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS SITES THIS MORNING...WITH MAINLY MVFR CEILINGS AT THE NORTHEAST OKLAHOMA SITES. CONDITIONS WILL IMPROVE BY AFTERNOON...WITH VFR RETURNING TO THE NORTHEAST OKLAHOMA SITES AT THAT TIME...TO KMLC BY THIS EVENING...AND TO THE NORTHWEST ARKANSAS SITES BY LATE TONIGHT. PREV DISCUSSION... /ISSUED 407 AM CST FRI DEC 28 2012/ DISCUSSION... WEAK UPPER LEVEL SYSTEM CURRENTLY OVER TX/OK PANHANDLE REGION CONTINUES TO PROVIDE JUST ENOUGH LIFT FROM SE OKLAHOMA INTO WEST CENTRAL ARKANSAS FOR SCATTERED VERY LIGHT RAIN MAINLY SOUTH OF I-40 THIS MORNING. SFC TEMPS MOSTLY AT OR SLIGHTLY ABOVE FREEZING BUT HAVE SEEN A FEW REPORTS OF FREEZING DRIZZLE AND EXPECT THAT MAINLY ELEVATED ROADWAYS WILL CONTINUE TO BE IMPACTED THROUGH THE MORNING. WILL LEAVE THE FREEZING RAIN ADVISORY IN TACT THROUGH 8 AM...REST OF AREA COULD SEE A LITTLE FREEZING DRIZZLE OR FREEZING FOR THIS MORNING...AND A FEW FLURRIES NOT EVEN OUT OF THE QUESTION AS THE SYSTEM MOVES OVER THE AREA LATER TODAY. ASSOCIATED COLD FRONT WILL PUSH THROUGH AND WILL BRING DRIER LOW LEVEL AIR IN AND HELP SHUT OFF DRIZZLE THIS AFTERNOON. CLEARING SKIES AND COLDER TONIGHT WITH A SLOW WARM UP THROUGH THE WEEKEND AHEAD OF THE NEXT APPROACHING SYSTEM...DUE TO BRING PRIMARILY A RAIN EVENT FOR SUNDAY NIGHT AND NEW YEARS EVE. A LITTLE CONCERNED THAT SHALLOW COLD AIR MAY REMAIN ENTRENCHED IN SOME NW ARKANSAS VALLEYS JUST ENOUGH FOR POCKETS OF LIGHT FREEZING RAIN INTO EARLY MON MORNING. COOLER AIR MOVING IN BEHIND THE SYSTEM MAY ALLOW FOR A CHANGEOVER TO SLEET OR SNOW IN NORTHERN AREAS NEW YEARS DAY...ALTHOUGH MOST MODELS SUGGEST THAT MAIN UPPER ENERGY WILL BE NORTH BY THAT TIME. && .PRELIMINARY POINT TEMPS/POPS... TUL 37 17 41 23 / 20 0 0 0 FSM 40 24 40 23 / 30 0 0 0 MLC 37 18 40 19 / 20 0 0 10 BVO 36 14 42 13 / 10 0 0 0 FYV 35 17 37 15 / 30 0 0 0 BYV 35 20 35 21 / 30 0 0 0 MKO 37 17 38 19 / 20 0 0 10 MIO 35 18 37 19 / 20 0 0 0 F10 36 17 40 20 / 20 0 0 10 HHW 40 21 41 22 / 20 0 0 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...FREEZING RAIN ADVISORY UNTIL 10 AM FRIDAY FOR OKZ072-OKZ074- OKZ075-OKZ076. AR...FREEZING RAIN ADVISORY UNTIL 10 AM FRIDAY FOR ARZ019-ARZ020- ARZ029. && $$ LONG TERM....30
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
747 AM CST FRI DEC 28 2012 .DISCUSSION... LATEST RADAR IMAGERY AND NUMEROUS REPORTS INDICATE A WIDESPREAD RAIN/SLEET MIX HAS OVERSPREAD THE SOUTHWESTERN PORTIONS OF MIDDLE TENNESSEE. SO FAR NO SIGNIFICANT ACCUMULATION HAS BEEN REPORTED...AND SURFACE OBSERVATIONS INDICATE TEMPERATURES ARE NOW AT OR ABOVE FREEZING FOR NEARLY ALL LOCATIONS. THUS A CHANGEOVER TO ALL RAIN IS STILL EXPECTED IN THE NEXT COUPLE OF HOURS AS TEMPERATURES/DEWPOINTS CONTINUE TO WARM. HAVE UPDATED FORECAST FOR THIS MORNING TO REMOVE MENTION OF FZRA AS PRECIP SHOULD BE PREDOMINATELY RAIN/SLEET. IN ADDITION...06Z GUIDANCE CONTINUES TREND FROM 00Z MODELS WITH LIGHT SNOW ACCUMULATIONS OVER NORTHWEST ZONES LATE FRIDAY EVENING INTO FRIDAY NIGHT AS CAA INCREASES AND TEMPERATURES FALL BACK TO NEAR FREEZING. ADJUSTED POPS/WX GRIDS ACCORDINGLY AND RAISED TOTAL SNOW ACCUMS IN THIS AREA INTO THE 0.5-1.0 INCH RANGE. WILL LET DAY SHIFT ANALYZE THE 12Z GUIDANCE TO SEE IF A WINTER WX ADVISORY WILL BE NECESSARY FOR THE NORTHWEST ZONES FRIDAY NIGHT. REST OF FORECAST REMAINS UNCHANGED. && .PREV DISCUSSION... /ISSUED 428 AM CST FRI DEC 28 2012/ UPDATE...FOR 12Z TAFS AVIATION...12Z TAFS RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET. CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY RESTRICTION AT CKV. PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/ SHORT TERM... SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL. WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM. BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED. AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE. LONG TERM... AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF 2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE FIRST PART OF JANUARY. && .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 42 33 35 24 / 90 100 30 05 CLARKSVILLE 39 30 34 22 / 90 100 20 05 CROSSVILLE 45 34 34 22 / 70 100 30 20 COLUMBIA 43 33 36 24 / 100 90 20 05 LAWRENCEBURG 44 33 36 24 / 100 90 20 05 WAVERLY 39 30 34 22 / 100 90 20 05 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHAMBURGER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
428 AM CST FRI DEC 28 2012 .UPDATE...FOR 12Z TAFS && .AVIATION...12Z TAFS RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET. CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY RESTRICTION AT CKV. && .PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/ SHORT TERM... SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL. WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM. BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED. AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE. LONG TERM... AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF 2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE FIRST PART OF JANUARY. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
702 AM CST FRI DEC 28 2012 .UPDATE... SNOW HAS STRUGGLED TO DEVELOP ACROSS THE SOUTH BUT HAS FINALLY STARTED AT KDBQ KMRJ AND KLNR THIS HOUR. DRY LAYER AROUND 850 MB HAS STRUGGLED TO MOISTEN AND THAT HAS DELAYED START OF SNOW IN THE SOUTH. GIVEN LOW LEVEL ASCENT AND LACK OF ICE CRYSTALS HAVE HAD A PERIOD OF FREEZING DRIZZLE HERE IN THE WAUKESHA/JEFFERSON COUNTY AREA SO ADDED FREEZING DRIZZLE IN SOUTHEAST 1/4 OF CWA FOR THE MORNING. MEANWHILE SNOW FILLING IN NICELY ACROS NORTHERN HALF GENERALLY ALONG AND NORTH OF SURFACE TROUGH/REMNANTS OF LAKE BAND. EASTERLY LOW LEVEL FLOW OFF LAKE APPEARS TO BE HELPING THE SEEDING AND MOISTENING PROCESS AND WE SHOULD ALSO SEE LAKE ENHANCEMENT IN THAT AREA SO ADVISORY STILL LOOKS GOOD. GIVEN DRY AIR AND SLIGHTLY DRIER LOOK TO 06Z NAM/GFS AND MOST RECENT RAP MODELS IN THE SOUTH...ADJUSTED DOWN THE QPF AND SNOW AMOUNTS ABOUT AN INCH MOST AREAS BUT ESPECIALLY TOWARD ILLINOIS BORDER IN SOUTHEAST. WILL NOT BE SURPRISED TO SEE LESS THAN AN INCH IN THAT AREA. RECENT RAP RUNS CONTINUE TO SHOW DECENT LIFT IN THE DENDRITE GROWTH ZONE (-12 TO -18C) OVER THE NORTHERN PART OF CWA. THAT COUPLED WITH LAKE ENHANCEMENT SHOULD ALLOW HIGHER SNOW TOTALS TO VERIFY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST SATURDAY FOR WIZ046-047- 051-052-058>060. LM...NONE. && $$ UPDATE...CRAVEN TODAY/TONIGHT AND AVIATION/MARINE...CRAVEN SATURDAY THROUGH THURSDAY...KAPELA
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
255 PM MST FRI DEC 28 2012 .SHORT TERM...LATEST WATER VAPOR AND IR LOOPS SUGGESTING A WEAK SHORTWAVE CURRENTLY MOVING ACROSS AREA AS NOTED BY SOME CLOUD ENHANCEMENT. HOWEVER...WEB CAMS SHOW THE LIGHT SNOW CONFINED TO AREAS ALONG THE CONTINENTAL DIVIDE AS WELL AS ACROSS THE PARK RANGE IN WESTERN JACKSON COUNTY. SOME GUSTY WINDS ACROSS THE HIGHER MOUNTAINS AND OVER THE NORTHERN FOOTHILLS WITH A FEW GUSTS AROUND 35 MPH. LATEST MODELS SHOW THE SHORTWAVE MOVING EAST OF THE AREA DURING THE EVENING WITH THE FLOW ALOFT BECOMING MORE NORTH NORTHWEST. CROSS SECTIONS INDICATE A DECREASE IN MOISTURE WITH INCREASING SUBSIDENCE. SHOULD SEE MOUNTAIN SNOW COMING TO AN END BY MIDNIGHT WITH CLEARING SKIES. WINDS TO REMAIN A BIT GUSTY INTO THE EVENING...BEFORE DECREASING AROUND MIDNIGHT. CLEARING SKIES... LIGHT WINDS AND SNOW COVER WILL ALLOW FOR THE DEVELOPMENT OF INVERSIONS IN THE MOUNTAIN VALLEYS AS WELL AS LOW LYING AREAS ACROSS THE PLAINS. THUS...SHOULD GET QUITE COLD IN THESE AREAS OVERNIGHT WITH TEMPERATURES BELOW ZERO ESPECIALLY THE KREMMLING AREA IN GRAND COUNTY. ON SATURDAY...UPPER LEVEL RIDGE BUILDS OVER COLORADO WITH FLOW ALOFT BECOMING MORE WESTERLY. 7H TEMPERATURES WARM ABOUT 6-8 DEGREES CELSIUS FROM TODAY`S READINGS. THUS SHOULD SEE WARMER TEMPERATURES ACROSS MUCH OF THE AREA WITH MAINLY CLEAR SKIES. HOWEVER...INVERSIONS WILL LIMIT THE WARMUP...ESPECIALLY IN THE MOUNTAIN VALLEYS. TEMPERATURES ACROSS THE PLAINS TO BE MAINLY IN THE 30S...WITH MID TO UPPER 20S IN THE GREELEY AREA. WINDS ALOFT TO BE FAIRLY LIGHT...WITH SOME GUSTY WINDS POSSIBLE ACROSS THE HIGHER RIDGES. .LONG TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL SATURDAY NIGHT AND SUNDAY AS AN UPPER LEVEL TROUGH MOVES ONTO THE WEST COAST. THE TROUGH WILL CONTINUE TO DIG SOUTHEAST AND BE CENTERED OVER THE SOUTHWESTERN STATES SUNDAY NIGHT. EXPECT A COLD NIGHT IN THE MOUNTAIN VALLEYS SATURDAY NIGHT UNDER MOSTLY CLEAR SKIES. LOWS SHOULD DROP BELOW ZERO IN THE MOUNTAIN VALLEYS. CLOUDS WILL INCREASE DURING THE DAY SUNDAY AS MID AND HIGH LEVEL MOISTURE INCREASE WITH THE APPROACH OF THE UPPER LEVEL TROUGH. STILL A LOT OF DIFFERENCES AMONG THE MODELS ON THE TRACK OF THE UPPER LEVEL TROUGH. THE LATEST ECMWF AND NAM ARE STARTING TO NUDGE THE TRACK MORE NORTHERLY. MEANWHILE THE GFS CONTINUES TO FAVOR A SOUTHERLY TRACK ACROSS THE SOUTHERN ROCKIES. BECAUSE OF THIS NORTHERLY SHIFT...WILL INCREASE POPS ACROSS THE AREA FOR SUNDAY NIGHT AND MONDAY. WILL HAVE LIKELY POPS FOR THE MOUNTAINS NEAR AND SOUTH OF I-70. EVEN THE SOUTHERLY TRACK OF GFS SHOWS SNOW FOR THE CENTRAL AND SOUTHERN MOUNTAINS OF COLORADO. WILL HAVE CHANCE TO SLIGHT CHANCE ELSEWHERE. AS THIS SYSTEM NEARS...LATER SHIFTS CAN TREND UP OR DOWN AS THE TRACK OF THE TROUGH BECOMES MORE CLEAR. EXPECT HIGH TEMPERATURES TO BE COOL MONDAY AND TUESDAY UNDERNEATH THIS SYSTEM. ONCE THE TROUGH EXITS THE REGION...QUIET WEATHER WILL PREVAIL. EVEN THOUGH MODELS ARE SHOWING DIFFERENT UPPER LEVEL PATTERN...ALL OF THE DIFFERENT SOLUTIONS WOULD RESULT IN COOL AND DRY CONDITIONS. THEREFORE WILL CONTINUE WITH THE COOL AND DRY CONDITIONS CURRENTLY IN THE FORECAST. && .AVIATION...WINDS HAVE TRENDED TOWARD LIGHT EASTERLY ACROSS THE AREA AIRPORTS. LATEST RUC AND HRRR INDICATING WINDS TO BECOME NORTHWEST BY 00Z...THEN SOUTHWESTERLY BY 03Z AS DRAINAGE FLOW DEVELOPS. THIS TREND SEEMS REASONABLE THOUGH THE DIRECTION WILL BE MORE WESTERLY AT BJC. ON SATURDAY...MODELS HINT AT A WEAK CYCLONE DEVELOPING NORTH OF THE DENVER AREA BY 18Z. THUS...LIGHT SOUTHERLY WINDS SHOULD PREVAIL AT THE AREA AIRPORTS THROUGH THE DAY... PERHAPS MORE SOUTHEAST AT DEN. VFR TO CONTINUE WITH UNLIMITED CEILINGS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....MEIER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
953 AM MST FRI DEC 28 2012 .UPDATE... && .SHORT TERM...WEB CAMS ACROSS MOUNTAINS SHOWING AREAS OF LIGHT SNOW ALONG THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES. SNOW ALSO OCCURRING IN THE STEAMBOAT AREA ON THE UPSLOPE SIDE OF THE PARK RANGE. LATEST MODELS HINT AT A WEAK DISTURBANCE MOVING ACROSS THE AREA THIS AFTERNOON AS THERE IS A BIT OF ASCENT NOTED ON THE QG VERTICAL VELOCITY PROGS. LATEST RAP/RUC KEEPS FAIRLY DEEP MOISTURE THROUGH THE DAY ALONG WITH FAVORABLE OROGRAPHICS. AT THIS TIME...IT`S HARD TO FIND ANY TYPE OF DISTURBANCE IN THE CURRENT SATELLITE LOOPS. WILL CONTINUE WITH THE CHANCE OF SNOW FOR THE THE MOUNTAINS THIS AFTERNOON DUE TO THE FAVORED OROGRAHICS. MOISTURE DECREASES THIS EVENING...SHOULD SEE SNOW ENDING BY MIDNIGHT. ELSEWHERE...DRY CONDITIONS TO PREVAIL. OVERALL CURRENT FORECASTS LOOKING ON TRACK WITH SOME MINOR ADJUSTMENTS FOR CURRENT CONDITIONS. WINDS LOOK TO INCREASE ACROSS MOUNTAINS AND HIGHER FOOTHILLS BY THE EVENING...STAYING BELOW HIGH WIND CRITERIA. .AVIATION...CURRENT FORECAST TRENDS LOOK REASONABLE. MAY NEED TO INCLUDE A BROKEN DECK AROUND 7000 FEET AGL FOR AN HOUR OR SO AS SATELLITE SHOWING A BATCH OF CLOUDS CURRENTLY MOVING ACROSS THE DENVER AREA. BY 19Z...THIS BATCH OF CLOUDS SHOULD BE WELL SOUTHEAST OF THE AREA. LATEST HRRR AND RAP/RUC CONTINUE TO SHOW WINDS SHIFTING TO THE NORTHWEST BY 20Z...THEN BACK TO SOUTHWEST BY 03Z. THIS TREND STILL LOOKING REASONABLE. && .PREV DISCUSSION... /ISSUED 332 AM MST FRI DEC 28 2012/ SHORT TERM...NW FLOW ALOFT WILL BE OVER THE AREA AS A DISTURBANCE MOVES ACROSS THE MTNS THIS AFTN. OVERALL MOISTURE DEPTH IN THE MTNS IS NOT THAT DEEP HOWEVER WITH FAVORABLE OROGRAPHIC FLOW WILL CONTINUE TO SEE SOME LIGHT SNOW. AT LOWER ELEVATIONS EXPECT DRY CONDITIONS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER ACROSS NERN CO WITH READINGS IN THE MID 20S OVER THE FAR NERN PLAINS WITH LOWER TO MID 30S NEAR DENVER. SOME GUSTY WINDS WILL OCCUR IN THE HIGHER MTNS AND HIGHER FOOTHILLS THIS AFTN INTO THE EVENING HOURS BUT SPEEDS WILL STAY WELL BLO HIGH WIND CRITERIA. FOR TONIGHT MOISTURE WILL DECREASE IN THE MTNS WITH LIGHT SNOW ENDING BY MIDNIGHT. LONG TERM...MODELS SHOW A FAIRLY HIGH AMPLITUDE SHORT WAVE RIDGE TO MOVE EASTWARD ACROSS COLORADO ON SATURDAY. BY SATURDAY NIGHT... PRETTY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE CWA. ON SUNDAY...STRONG SOUTHWESTERLY FLOW ALOFT IS OVER THE CWA. IN FACT THERE IS A 150-170 KNOT JET MAXIMUM STRETCHED FROM SOUTH CENTRAL COLORADO TO THE NORTHEAST CORNER OF THE STATE AT 00Z LATE SUNDAY AFTERNOON. BY 12Z MONDAY MORNING...THE FLOW ALOFT IS SOUTH- SOUTHWESTERLY AND LIGHTER AS AN UPPER TROUGH AXIS IS JUST WEST OF THE COLORADO WESTERN BORDER. THE SYNOPTIC SCALE ENERGY IS DOWNWARD SATURDAY...THEN UPWARD SATURDAY NIGHT THROUGH SUNDAY NIGHT. AT 12Z MONDAY MORNING...THE MODELS AGREE PRETTY WELL ON A FAIRLY STRONG UPWARD Q-G ASCENT OVER NORTH CENTRAL NEW MEXICO. THE UPWARD VERTICAL VELOCITY PROGGED FOR OUR CWA IS FAIRLY WEAK AT THAT TIME. THE PROGGED BOUNDARY LAYER FLOW FOR THE CWA THROUGH MUCH OF THE PERIOD IS DOMINATED BY DOWNSLOPING. THERE IS SOME WEAK UPSLOPE PROGGED SUNDAY NIGHT FOR THE PLAINS AND LOWER FOOTHILLS. FOR MOISTURE...SATURDAY AND SATURDAY NIGHT LOOK PRETTY DRY...JUST SOME UPPER LEVEL MOISTURE PROGGED HERE AND THERE. MOISTURE INCREASES FROM THE WEST ON SUNDAY...ESPECIALLY DURING THE AFTERNOON. BY SUNDAY NIGHT MOISTURE IS DEEP OVER THE MOUNTAINS AND FOOTHILLS. THERE IS QUITE A BIT IN THE MID AND UPPER LEVELS OF THE PLAINS AS WELL. THE QPF FIELDS START TO BRING IN MEASURABLE PRECIPITATION TO THE MOUNTAINS BY SUNDAY AFTERNOON. THERE ARE LIMITED AMOUNTS OVER THE MOUNTAINS AND FOOTHILLS SUNDAY NIGHT. FOR POPS IN THE MOUNTAINS...WILL START SOME MINOR ONES UP BY SUNDAY AFTERNOON... AND WILL GO WITH "CHANCE"S IN THE HIGH MOUNTAINS SUNDAY NIGHT. OROGRAPHICS ARE NOT GOOD AND THE SYNOPTIC SCALE ENERGY IS MEAGER ..BUT THERE IS PLENTY OF MOISTURE. NO POPS FOR THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 2-4 C WARMER THAN TODAY`S. SUNDAY`S HIGHS ARE SIMILAR TO SATURDAY`S. FOR THE LATER DAYS... MONDAY THROUGH THURSDAY...THE UPPER TROUGH AXIS MOVES INTO COLORADO ON MONDAY...BUT IT IS SLOW AND WEAKENING AND SOMEWHAT DEVELOPING BACK INTO A MORE EAST-WEST ORIENTATION. THE UPPER LEVEL WIND SHIFT DOESN`T GET THROUGH THE CWA UNTIL TUESDAY NIGHT ON BOTH THE GFS AND ECMWF. BY WEDNESDAY AT 12Z...BOTH OF THOSE MODELS HAVE AN UPPER CLOSED LOW OVER THE SOUTHERN BORDER OF ARIZONA AND NEW MEXICO. THIS IS SLOWER THAN YESTERDAY`S 00Z MODEL RUNS INDICATED. SO THE FLOW ALOFT ON WEDNESDAY IS NORTHERLY FOR THE CWA. BY THURSDAY...THERE IS UPPER RIDGING OVER THE CWA...BUT THE LOOK OF IT AND TIMING DIFFERS BETWEEN THE ECMWF AND THE GFS. MOISTURE IS PRETTY DEEP MONDAY AND MONDAY NIGHT...MORE SO ON THE ECMWF. THE ECMWF ALSO HAS PRETTY DEEP MOISTURE OVER THE PLAINS...THE GFS DOES NOT. THE GFS GETS DRY AFTER THAT ALL THE WAY THROUGH THURSDAY. THE ECMWF IS DRY LATER ON TUESDAY INTO EARLY THURSDAY...THEN MOISTURE RETURNS...ESPECIALLY FOR THE MOUNTAINS BY THURSDAY. SO WILL KEEP SOME POPS IN MONDAY AND MONDAY NIGHT...THEN NOTHING AFTER THAT FOR NOW. TEMPERATURES LOOK TO STAY BELOW SEASONAL NORMALS ALL FOUR DAYS. AVIATION...THERE WAS SOME FOG AND LOW CLOUDS OVER WELD COUNTY EARLY THIS MORNING WITH SOME DENSE FOG REPORTED NR BRIGHTON. HOWEVER WEB CAMS ALONG E470 NR BRIGHTON DO NOT SHOW ANY FOG. FOR NOW IF LOW LVL WINDS STAY SSW LOW CLOUDS AND FOG SHOULD STAY TO THE NORTH OF THE AIRPORT. THUS WILL KEEP CONDITIONS VFR IN THE TAF. AS FAR AS WINDS LATEST HRRR SHOWS WINDS BECOMING MORE WNW BY EARLY AFTN AS GUSTY WINDS IN THE FOOTHILLS MIX DOWN TO THE SFC WITH SPEEDS IN THE 10-15 MPH RANGE. BY EARLY EVENING WINDS MAY GO MORE WLY AND THEN BACK TO SSW BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1141 AM EST FRI DEC 28 2012 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 333 AM EST FRI DEC 28 2012 HIGH PRESSURE OVER CENTRAL INDIANA WILL BE FOLLOWED BY A WEAK COLD FRONT THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE IS FORECAST TO RETURN FOR THE WEEKEND. MONDAY ANOTHER COLD FRONT IS EXPECTED TO CROSS OUR STATE. AFTER THAT...HIGH PRESSURE WILL TAKE CHARGE AGAIN FOR SEVERAL DAYS. MUCH COLDER AIR WILL ARRIVE OVER THE REGION LATE NEXT WEEK...WITH LOW TEMPERATURES DROPPING INTO THE SINGLE DIGITS. && .NEAR TERM /TODAY/... ISSUED AT 1000 AM EST FRI DEC 28 2012 NEITHER RUC NOR HRR BRING IN ANY QPF TIL AFTER 00Z...WHICH LINES UP WELL WITH MAV AND ECM POPS. WILL DROP POPS BELOW 15 MOST AREAS. PLAN TO RETAIN THEM SOUTHWEST BUT MAKE THEM LOWER AND INDICATE ANY PCPN COMING IN QUITE LATE. TEMPERATURES LOOKING GOOD FOR THE MOST PART. BUT DID MAKE MINOR TWEAKS BASED ON LATEST OBS. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... ISSUED AT 333 AM EST FRI DEC 28 2012 FORECAST FOCUS WAS ON SNOW FORECAST FOR TONIGHT PERIOD. LATEST MODEL RUNS SHOW BETTER MOISTURE AND LIFT ACROSS THE OHIO VALLEY FROM 00-12Z. THE GFS AND GEM ESPECIALLY ARE DEPICTING MUCH HIGHER MOISTURE AMOUNTS OF OVER FOUR TENTHS OF AN INCH ACROSS THE FAR SE COUNTIES...WHILE THE NAM STICKS TO AROUND A TENTH. THE LATEST EURO APPEARS TO TAKE A BLEND OF THE THE DIFFERING SOLUTIONS...PLACING AROUND TWO TO THREE TENTHS OF AN INCH OF QPF ACROSS THE SE COUNTIES...WHICH SEEMS MORE REASONABLE AND IN LINE WITH HPC GUIDANCE. TRENDED FORECAST WITH HIGHER POPS...ESPECIALLY ACROSS THE SOUTH AND EAST WHERE THIS FEATURE WILL MOVE CLOSEST TO. TOTAL SNOWFALL AMOUNTS WILL RANGE FROM 0.5-1.0 INCHES NORTHWEST...TO 2 TO 3 INCHES SOUTHEAST. ADVISORY CRITERIA IS 4 INCHES...SO OPTED NOT TO ISSUE ONE AT THIS TIME AND PLAN ON SENDING OUT AN SPS. PRECIP TYPE DOES NOT LOOK TO BE AN ISSUE FOR TONIGHT AND SHOULD BE ALL SNOW. SYSTEM STILL LOOKS FAIRLY PROGRESSIVE AND SHOULD BE MOVING AWAY FROM THE FORECAST AREA...HOWEVER A FEW SHOW SHOWERS AND/OR FLURRIES MAY LINGER ON THE BACK SIDE OF LOW. WIDESPREAD CLEARING DOES NOT BEGIN UNTIL SATURDAY NIGHT. HIGH PRESSURE AND DRIER WEATHER WILL BE THE RULE FOR THE REST OF THE PERIOD. && .LONG TERM /MONDAY THROUGH THURSDAY/... ISSUED AT 333 AM EST FRI DEC 28 2012 FORECAST FOCUS IS ON CHANCES FOR SNOW MONDAY THROUGH TUESDAY. MODELS AND ENSEMBLES ARE SHOWING A DECENT AMOUNT OF VARIABILITY BY MONDAY AND SAW NO REASON TO CHANGE FROM ALLBLEND. A CLIPPER TYPE SYSTEM WILL MOVE ACROSS ONTARIO INTO QUEBEC AND POSSIBLY BRING A COLD FRONT THROUGH ON MONDAY WHICH COULD PROMPT CHANCES FOR SNOW. MONDAY NIGHT A LOW FORMS IN THE SOUTHERN PLAINS AND TRACKS NORTHEAST INTO TUESDAY. RIGHT NOW OPERATIONAL GFS AND ECMWF FAVOR A TRACK ACROSS WESTERN TENNESSEE AND THROUGH EASTERN KENTUCKY WHICH WOULD FAVOR HIGH POPS FOR THE SOUTH AND CENTRAL COUNTIES...BUT THE MAJORITY OF THE ENSEMBLE MEMBERS TRACK THIS LOW QUITE A BIT FURTHER SOUTH WHICH WOULD BE MUCH LESS FAVORABLE. THUS THE ALLBLEND CHANCE POPS WITH THE HIGHEST NUMBERS IN THE SOUTH LOOK GOOD FOR NOW AND A COMPROMISE. THERMAL PROFILES IN THE SOUTH INDICATE POTENTIAL FOR SOME MIXED PRECIP AND WILL KEEP THE RAIN SNOW MIX IN THE SOUTH MONDAY AFTERNOON FROM PREVIOUS FORECAST. WILL HAVE TO CONTINUE TO MONITOR PRECIP TYPE WITH UPCOMING FORECASTS FOR THIS TIME. BY TUESDAY NIGHT HIGH PRESSURE BUILDS IN AND SHUTS DOWN SNOW CHANCES FOR THE REST OF THE EXTENDED. WITH SNOW COVER CONTINUING AND COLD AIR INTRUSIONS MAKING THEIR WAY FURTHER SOUTH WITH THE FRONTAL PASSAGE SHOULD SEE BELOW NORMAL TEMPERATURES AFTER MONDAY. && .AVIATION /DISCUSSION FOR THE 281800Z TAF ISSUANCE/... ISSUED AT 1141 AM EST FRI DEC 28 2012 GENERALLY MVFR CONDITIONS GIVING WAY TO IFR AFTER 00Z. CEILINGS WILL GENERALLY HANG AROUND BKN015-BKN025 THROUGH 00Z...BUT THERE IS A CHANCE SOME OF THE BREAKS IN THE LOWER CLOUDS ACROSS SOUTHERN ILLINOIS COULD WORK INTO THE SITES. HOWEVER STUCK WITH THE PESSIMISTIC FORECAST BASED ON AN INVERSION ALOFT AND PERSISTANCE. SNOW WILL OVERSPREAD THE AREA AFTER 00Z FROM SOUTHWEST TO NORTHEAST RESULTING IN IFR CEILINGS AND VISIBILITIES. LIFR CONDITIONS ARE POSSIBLE IN SOME HEAVIER BANDS OF SNOW. SNOW WILL EXIT THE AREA BEF0RE 12Z BUT IFR CEILINGS SHOULD PERSIST THROUGH AT LEAST 18Z SATURDAY. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMF NEAR TERM...JK SHORT TERM...SMF LONG TERM....CP AVIATION...50
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1237 PM CST FRI DEC 28 2012 .DISCUSSION... FOR THE 18Z TAF PACKAGE. && .AVIATION... BKN BAND OF CONVCTN WORKING EAST TWD C CENTRAL LA...HAVING CLRD KBPT-KLCH-KAEX. WILL CARRY TEMPO GROUPS AT KLFT-KARA FOR THIS ACTIVITY...WITH THE TIMING A BEST ESTIMATE BASED ON LATEST RADAR TRENDS. CONVECTION HAS RUN AHEAD OF THE ACTUAL COLD FRONT...ESPECIALLY OVER CENTRAL LOUISIANA. CONSIDERABLE LOW CLOUD COVER EXTENDS WELL INTO CENTRAL TX IN THE POST FRONTAL AIRMASS. DRY AIR COMING FROM THE SOUTHWEST ALONG THE TX COAST AND INTO SE TX/SW LA CAUSING CIGS TO BOUNCE AROUND A BIT...AND MAY PREVENT THE PREVAILING IFR CURRENTLY AT KAEX. TIMING OF CLOUD COVER AND CIG HTS WERE BASED ON A BLEND OF SATELLITE TRENDS AND MODEL FCST SOUNDINGS. 13 && .PREV DISCUSSION... /ISSUED 1008 AM CST FRI DEC 28 2012/ UPDATE... LINE OF SHOWERS AND THUNDERSTORMS THAT EXTENDS FROM AVOYELLES PARISH SOUTHWEST OFF THE SOUTHEAST TEXAS COAST IS A FRONTAL SYSTEM THAT IS PUSHING THROUGH THE REGION THIS AM. TEMPS OUT AHEAD OF THE FRONT ARE RUNNING IN THE UPPER 60S WITH TEMPS DROPPING INTO THE UPPER 50S BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE NORTHWEST AND BE BRISK THROUGH THE AFTERNOON HOURS. PREV DISCUSSION... /ISSUED 656 AM CST FRI DEC 28 2012/ AVIATION DISCUSSION... FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...WITH A WARM FRONT FROM SOUTHEAST THROUGH LAFAYETTE ..AND A COLD FRONT FROM SOUTH THROUGH BEAUMONT. THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE WESTERN UPPER GULF COAST STATES THIS AFTERNOON. PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT. PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/ DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR. LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT 850 MB TRANSPORTING IN VERY MOIST AND WARM AIR. TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF. LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST TO EAST ACROSS THE AREA. VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT. 0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM TOWARD A SEVERE THREAT. RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER ACADIANA. WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY SEE OUR COOLEST MORNING THIS SEASON SUNDAY. REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE NEXT FEW DAYS. MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 69 38 53 30 / 90 10 0 0 KBPT 68 36 51 31 / 40 10 0 0 KAEX 63 35 49 27 / 90 10 0 0 KLFT 72 41 52 30 / 90 20 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT 20 NM-COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA OUT 20 NM-COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM-WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60 NM-WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60 NM-WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM. SMALL CRAFT EXERCISE CAUTION UNTIL 6 PM CST THIS EVENING FOR CALCASIEU LAKE-SABINE LAKE-VERMILION BAY. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1008 AM CST FRI DEC 28 2012 .UPDATE... LINE OF SHOWERS AND THUNDERSTORMS THAT EXTENDS FROM AVOYELLES PARISH SOUTHWEST OFF THE SOUTHEAST TEXAS COAST IS A FRONTAL SYSTEM THAT IS PUSHING THROUGH THE REGION THIS AM. TEMPS OUT AHEAD OF THE FRONT ARE RUNNING IN THE UPPER 60S WITH TEMPS DROPPING INTO THE UPPER 50S BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE NORTHWEST AND BE BRISK THROUGH THE AFTERNOON HOURS. && .PREV DISCUSSION... /ISSUED 656 AM CST FRI DEC 28 2012/ AVIATION DISCUSSION... FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...WITH A WARM FRONT FROM SOUTHEAST THROUGH LAFAYETTE ..AND A COLD FRONT FROM SOUTH THROUGH BEAUMONT. THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE WESTERN UPPER GULF COAST STATES THIS AFTERNOON. PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT. PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/ DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR. LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT 850 MB TRANSPORTING IN VERY MOIST AND WARM AIR. TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF. LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST TO EAST ACROSS THE AREA. VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT. 0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM TOWARD A SEVERE THREAT. RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER ACADIANA. WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY SEE OUR COOLEST MORNING THIS SEASON SUNDAY. REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE NEXT FEW DAYS. MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING .WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 69 38 53 30 55 / 80 10 0 0 0 KBPT 68 36 51 31 54 / 80 10 0 0 0 KAEX 63 35 49 27 53 / 80 10 0 0 0 KLFT 72 41 52 30 55 / 80 20 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM. SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: VERMILION BAY. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1206 PM CST FRI DEC 28 2012 .UPDATE... ISSUED AT 1205 PM CST FRI DEC 28 2012 LATEST DATA INDICATE SHORTWAVE LIFTING NE OUT OF ARKANSAS WILL BRING A BIT MORE PRECIP IN THE FORM OF SNOW TO SE PARTS OF THE CWA THAN EARLIER EXPECTED...AND REGIONAL RADAR TRENDS SEEM TO BE SUPPORTING THIS NWD SHIFT IN THE N EDGE OF THE PRECIP SHIELD. ALL 12Z GUIANCE SUGGESTS MEASUREABLE SNOW IN OUR FAR SE COUNTIES WITH SNOWFALLS IN THE 1-3 INCH RANGE. MODELS ARE A BIT LESS CERTAIN WRT N EDGE OF THE SNOWFALL...AND ATTM HAVE USED THE HRRR TO DELINEATE THE N EDGE OF THE SNOWFALL...ESSENTIALLY...AND ONCE AGAIN...OVER S SECTIONS OF THE ST LOUIS METRO AREA. HAVE POSTED A WINTER WEATHER ADVISORY FOR THIS AFTERNOON AND EVENING FOR OUR EXTREME SOUTHEAST COUNTIES...AND WILL MONITOR TRENDS DURING THE AFTERNOON TO SEE IF THIS NEEDS TO BE EXPANDED N FOR THE EVENING RUSH HOUR. TRUETT && .SHORT TERM... ISSUED AT 353 AM CST FRI DEC 28 2012 .SYNOPSIS... TWO WEATHER SYSTEMS WILL IMPACT THE REGION OVER THE NEXT WEEK. ONE TODAY AND THE OTHER EARLY NEXT WEEK. THE AREA IS UNDER THE INFLUENCE OF SW FLOW ALOFT THIS MORNING ON THE FRONT SIDE OF A LONGWAVE TROUGH AND A COUPLE OF SHORT WAVES. WATER VAPOR IMAGERY SHOWS A TIGHT CIRCULATION ACROSS SE ND AND NE NEB THIS MORNING. THIS FEATURE WAS RESPONSIBLE FOR A 2-6 INCH SWATH OF SNOW ACROSS THAT AREA OVER THE PAST 24 HRS. AT THE SURFACE...WEAK LOW PRESSURE ALONG THE KS/MO BORDER IS AT THE TOP OF AN INVERTED TROF EXTENDING FROM A STRONGER AREA OF LOW PRESSURE ALONG THE SE COAST OF TX. .SHORT TERM (TODAY THRU SUNDAY NIGHT)... THE WX SCENARIO OVER THE NEXT 24 HRS HAS PROVIDED A TRICKY FCST...ESP WRT TO P-TYPE. ALOFT...THE H500 LOW OVER THE PLAINS WILL BECOME ABSORBED INTO THE LEAD SHORT WAVE TODAY. A BAND OF LIGHT SNOW WILL CONTINUE TO BE ASSOC WITH THIS FEATURE WELL TO THE OF THE CWA. THE WEAK SFC LOW ALONG THE KS/MO BORDER WILL PROGRESS TO CNTRL IL BY THIS EVENING WHILE THE STRONGER LOW MOVES TO STHRN/CNTRL MS BY 00Z. THE INVERTED TROF STRUCTURE REMAINS INTACT THRU THE PERIOD. THERE ARE SEVERAL QUESTIONS WRT TO PRECIP AMOUNT AND TYPE ACROSS THE CWA TODAY. FIRST...WHAT ARE THE CHANCES FOR FZDZ TODAY? THE AREA REMAINS UNDER WEAK FORCING THRU THE PERIOD. UPPER FORCING WAINS THRU THE MORNING AS MID/HIGH LEVEL MOISTURE MOVES EAST AS WELL. WHAT REMAINS IS A SHALLOW SATURATED LAYER NEAR THE SFC THAT IS MAINLY ABOVE -10C THRU THE LAYER. THIS PRECLUDES ICE CRYSTALS SO WE ARE LEFT WITH DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SFC TEMPS. THE AMOUNT OF PRECIP IS ALSO ANOTHER CONCERN AS IT OBVIOUSLY DOESN/T TAKE MUCH -FZDZ TO CAUSE ISSUES. AFTER THE UPPER LEVEL FORCING MOVES EAST THIS MORNING...WEAK LOW LEVEL FORCING REMAINS IN ASSOC WITH THE APPROACHING SHORT WAVE. THE CONCERN IS IF THIS WILL BE ENOUGH LIFT TO GENERATE MEASURABLE PRECIP. DUE TO THE WEAK NATURE OF THE LIFT I HAVE DOUBTS THAT THIS WILL BE THE CASE. SO...I DROPPED MENTIONABLE POPS ACROSS THE CWA AND WENT WITH A TRACE EVENT WITH AREAS OF FZDZ/DZ. NON-MEASURABLE DOESN/T NECESSARILY MEAN NOT IMPORTANT AS WE HAVE SEEN IN THE PAST...IT DOESN/T TAKE MUCH FZDZ TO CAUSE PROBLEMS ON THE ROADS. GROUND TEMPS ARE AT OR JUST ABOVE FREEZING SO I THINK THE BIGGEST THREAT FROM FZDZ WILL BE ELEVATED SFCS INCLUDING BRIDGES AND OVERPASSES. WITH ANY LUCK...THE MAJORITY OF THE DRIZZLE WILL HOLD OFF UNTIL AFTER THE MORNING RUSH AND TEMPS GET ABOVE FREEZING. THE NEXT CONCERN IS PRECIP CHANCES ACROSS THE SE CWA. 00Z MODELS RUNS HAVE THE QPF GRADIENT ALONG THE CWA WITH PAH. MODELS CONSENSUS IS THAT OUR SERN COUNTIES WILL SEE MEASURABLE PRECIP STARTING LATER THIS AFTN AND CONTINUING INTO THIS EVENING. MODEL GUIDANCE INDICATES DECENT LIFT FROM OMEGA AND FRONTOGENETICAL CIRCULATIONS ALONG THE BORDER AS WELL. THIS WILL BE A CLOSE CALL AS THE QPF GRADIENT WILL LIKELY BE FAIRLY TIGHT. IT/S CERTAINLY POSSIBLE THAT ALL/MOST OF THE PRECIP COULD REMAIN IN PAH/S CWA AND OUR AREA RECEIVES LITTLE TO NO PRECIP. ON THE OTHER HAND...A SLIGHT SHIFT NORTH AND OUR AREA COULD RECEIVE AT LEAST A TENTH OF AN INCH. THIS IN ITSELF IS NOT A BIG DEAL UNTIL TEMP PROFILES ARE EXAMINED. SOME MODELS INDICATE MOST IF NOT ALL OF THIS MAY FALL IN THE FORM OF SNOW. THE NAM IS A WARM OUTLIER AND WAS NOT USED IN THE TEMPS FCST TODAY OR TONIGHT. THE HEAVILY NAM INFLUENCED SREF WAS ALSO WARM. SURPRISINGLY THE LOCAL WRF WAS SIGNIFICANTLY COOLER THAN THE NAM. THE LOCAL WRF...GFS...ECMWF AND GEM ALL HAD SFC WET BULB AND TEMPS IN THE 30-35 DEGREE RANGE WITH CRITICAL THICKNESSES VERY CLOSE AS WELL. THE EVENT SHOULD START AS RAIN OR A RAIN/SNOW MIX AND THEN TRANSITION TO ALL SNOW AS THE EVENING PROGRESSES WITH SFC TEMPS COOLING AND COLDER AIR ALOFT CONTINUING TO FILTER IN. HAVE BUMPED POPS UP ACROSS THE SERN ZONES AND ADDED IN LESS THAN AN INCH OF SNOW. THIS WILL HAVE TO BE FINE TUNED THRU THE DAY. LASTLY...THERE IS A SMALL CHANCE AT MEASURABLE SNOW ACROSS NE MO AND W CNTRL MO LATE THIS AFTN INTO THIS EVENING IN ASSOC WITH WHAT/S LEFT OF THE H500 LOW CURRENTLY ACROSS NE NEB AND SE SD. THIS SEEMS A LOW PROB EVENT SO CHOSE TO COVER IT WITH FLURRIES. THE FIRST SHORT WAVE CLEARS THE AREA LATE FRIDAY EVENING/FRIDAY NIGHT WITH THE SECOND SHORT WAVE CLOSE ON ITS HEALS PASSING THRU SATURDAY. LOW LEVEL MOISTURE REMAINS IN PLACE UNTIL THE PASSAGE OF THE SECOND SHORT WAVE HAVE LEFT A CHANCE OF FLURRIES THRU THE NIGHT AND INTO SATURDAY MORNING FOR AREAS EAST OF THE MS RIVER. THINGS QUIET DOWN FOR THE WEEKEND WITH A 500MB RIDGE BUILDING IN AND A 1030+MB SFC HIGH PASSING THRU. RETURN FLOW BEGINS BY SUNDAY AFTN. THE PATTERN BECOMES ACTIVE AGAIN BY SUNDAY NIGHT WITH THE APPROACH OF THE STHRN STREAM ENERGY. THE MET GUIDANCE LOOKS TOO WARM FOR TODAY. LOCAL CLIMO INDICATES A DIURNAL RISE OF 6 OR 7 DEGREES WHICH FITS THE MAV MOS BETTER. WITH CLOUDS AND POTENTIAL LIGHT PRECIP...WENT ON THE COOLER SIDE OF GUIDANCE TODAY AND WARMER TONIGHT. USED A BLEND FROM SATURDAY AND BEYOND. MILLER && .LONG TERM... ISSUED AT 353 AM CST FRI DEC 28 2012 .LONG TERM (MONDAY THRU THURSDAY)... ENERGY DIVES DOWN THE WEST COAST OVER THE WEKND AND EJECTS OUT ON MONDAY. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT PRECIP WILL OVERSPREAD THE CWA MONDAY MORNING. THE GFS IS FURTHER NORTH WITH THE PRECIP AND CONSEQUENTLY WARMER. IT ALSO LINGERS THE PRECIP LONGER AT THE END OF THE EVENT. TEMPS WILL BE CRITICAL WITH THIS EVENT. THE ECMWF AND GEM HAVE 850 TEMPS BELOW ZERO FOR THE ENTIRE EVENT WHILE THE GFS HAS THE ZERO DEGREE 850MB LINE ALMOST UP TO THE MO RIVER. SFC TEMPS WILL ULTIMATELY DETERMINE P-TYPE. MOST OF THE PRECIP SHOULD OCCUR DURING THE DAY. WOULD HAVE A BETTER CHANCE FOR MORE SNOW IF THE SYSTEM SLOWED AND THE BULK OF THE PRECIP OCCURRED AT NIGHT. THIS EVENT CERTAINLY BEARS WATCHING AS THERE COULD BE ACCUMULATING SNOW SOMEWHERE IN OUR CWA. ANOTHER VORT MAX DROPS INTO THE DESERT SW EARLY NEXT WEEK AND BECOMES CUT OFF BY THE MIDDLE OF THE WEEK. THE MODELS ARE HAVING A TOUGH TIME DECIDING HOW TO HANDLE THIS SCENARIO. THE NTHRN STREAM TRANSITIONS TO NW FLOW...SO LOOK FOR BELOW NORMAL TEMPS FOR THE LATTER PART OF THE WORK WEEK. NOT CLEAR IF OR WHEN UPPER LEVEL FLOW WILL PHASE AGAIN...SO THE FCST REMAINS DRY BEYOND TUESDAY. MILLER && .AVIATION... ISSUED AT 1205 PM CST FRI DEC 28 2012 SC WILL CONTINUE TO DOMINATE ALL TAF SITES...WITH SNOWFALL MENTIONED IN SHORT TERM AFD PERHAPS AFFECTING CPS LATE THIS AFTERNOON/EARLY THIS EVENING. CIGS ARE GENERALLY RUNNING IN THE 3-4KFT RANGE ATTM...BUT STILL EXPECT THEM TO LOWER INTO MVFR CAT LATER THIS AFTERNOON AND EVENING...ESPECIALLY AFTER PASSAGE OF SURFACE TROF. SPECIFICS FOR KSTL...HAVE HELD CIGS IN THE 3-4KFT RANGE FOR MUCH OF THE AFTERNOON...WITH CIGS DIPPING INTO MVFR RANGE HEADING INTO THE EARLY EVENING HOURS. ATTM BELIEVE MOST OF THE SNOWFALL OVER S SECTIONS OF OUR CWA WILL REMAIN S OF THE STL AREA....BUT WILL CAREFULLY MONITOR THIS DURING THE AFTERNOON. TRUETT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR IRON MO- MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE. GENEVIEVE MO. IL...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO MIDNIGHT CST TONIGHT FOR CLINTON IL-MARION IL-RANDOLPH IL-WASHINGTON IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1025 AM CST FRI DEC 28 2012 .DISCUSSION... MAIN CHALLENGES WILL BE TEMPS AND LINGERING CLOUD COVER. MOSTLY CLOUDY CONDITIONS OVER THE AREA ATTM KEEPING TEMPS PROPPED UP...WITH THE EXCEPTION BEING AROUND COOPERSTOWN WHERE THE TEMPS ARE COOLER. OTHERWISE...EXPECT TEMPS TO FOLLOW THE CURVE FOR NOW AND ONLY MINOR ADJUSTMENTS MADE. REST OF FORECAST LOOKS ON TARGET. AVIATION... BAND OF THICKER MID CLOUDS FROM CENTRAL INTO SOUTHWESTERN MANITOBA THEN INTO CNTRL ND WILL SPREAD EAST TODAY WITH LATEST RAP MODEL INDICATING CLEARING OF THIS BAND EASTWARD TONIGHT. EAST OF THIS THICKER CLOUD BAND...SKY COVER IS MUCH MORE VARIABLE WITH POCKETS OF THIN MVFR STRATOCU AND A GENERALLY CLEAR SKY. EXPECT THIS AREA OF MORE THINNER CLOUDS TO HOLD INTO THE AFTERNOON AND WILL MAKE FOR SOME VARIABLE CEILING AREAS WITH MIXED MVFR/VFR. && .PREV DISCUSSION... /ISSUED 407 AM CST FRI DEC 28 2012/ DISCUSSION...FORECAST CHALLENGE CONCERNS LINGERING -SN CHANCES AND TEMPERATURES. MODELS OVERALL IN GOOD AGREEMENT WITH NO REAL PREFERENCE. MID LEVEL TROUGH FROM N CENTRAL TO SW US TO PROPAGATE GRADUALLY EAST TODAY. A WEAK NORTHERN STREAM IMPULSE WILL CROSS FA TODAY. KMVX-88D CONTINUES TO SHOW WEAK RETURNS ACROSS NORTHERN VALLEY REGION WITH A VERY GRADUAL WEAKENING TREND. SURFACE METARS INDICATING VSBY ACROSS THE REGION IN THE 3-5 MILE RANGE SO ACCUMULATING/MEASURABLE SNOWFALL LIKELY TO BE ISOLATED. WITH TROUGH SLOWLY PROGRESSING EASTWARD AND MOIST COLUMN WILL PROBABLY SEE SOME AREAS OF -SN/FLURRIES BUT A TOSS UP ON WHETHER TO GO FLURRIES OR LOW POPS. ONLY MADE SOME MINOR POP ADJUSTMENTS HOWEVER MAINTAIN MENTION OF FLURRIES OR ISOLATED SHSN. WITH NEUTRAL THERMAL ADVECTION AND ANTICIPATED CLOUD COVER MAXIMUM TEMPERATURES TODAY SHOULD BE PRETTY CLOSE TO WHAT HAPPENED YESTERDAY. HIGH PRESSURE BUILDS INTO FA TONIGHT AND THROUGH SATURDAY. TEMPERATURES WILL HINGE GREATLY ON CLOUD TRENDS. THERE IS SOME CLEARING WORKING ACROSS SASK AT THIS TIME AND MODELS DO INDICATE SOME DRYING THROUGH THE COLUMN SO COULD SEE SOME CLEAR AREAS ALLOWING TEMPERATURES TO DROP. CURRENT FORECAST REFLECTS THIS SO WILL HOLD WITH COLDER TEMPERATURES TONIGHT. COLUMN DOES WARM SATURDAY HOWEVER MIXING VERY LIGHT AND WITH COLDER START VALUES WILL BE LOWER THAN PAST COUPLE DAYS. SOME BRIEF MODERATION IN TEMPERATURES ANTICIPATED SUNDAY AS THERMAL RIDGE SHIFTS OVER FA AHEAD OF APPROACHING COLD FRONT. ALL MODELS INDICATING BAND OF -SN ALONG COLD FRONT SO WILL KEEP POPS ACROSS FAR NORTH AS BOUNDARY REACHES FA BY LATE MORNING. HIGH PRESSURE QUICKLY BUILDS IN SUNDAY NIGHT AND IF CLOUDS CLEAR OUT MINIMUMS FORECAST COULD BE 5-10 DEGREES COLDER. LONG TERM...MONDAY THROUGH THURSDAY. LONG WAVE UPPER LEVEL RIDGE REMAINS OVER THE WESTERN CANADA AND LONG WAVE TROUGH WAS OVER EASTERN CANADA/GREAT LAKES. PATTERN WILL SHIFT SLIGHTLY EAST DURING THIS PERIOD. ECMWF UPPER AIR REMAINS THE FASTER SOLUTION THAN THE GFS. HOWEVER THE LOW LEVEL THERMAL FIELD THE ECMWF WAS A SLOWER SOLUTION. WILL PREFER THE SLOWER ECMWF. HIGH TEMPS WERE LOWERED A DEGREE OR TWO FOR MON AND TUE. LOWERED TEMPS STRONGER FOR WED AND THU BY 5 TO 10 DEGREES. ADDED CHANCE FOR LIGHT SNOW IN THE NORTHEAST ZONES TUE NIGHT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ HOPKINS
AREA FORECAST DISCUSSION
NWS TULSA OK
1133 AM CST FRI DEC 28 2012 .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. BAND OF LIGHT SNOW MOVING FROM CENTRAL OK INTO EASTERN OK. THIS IS IN RESPONSE TO AN UPPER LEVEL TROUGH MOVING RAPIDLY THROUGH THE SOUTHERN PLAINS. EXPECT THIS SNOW TO MOVE EAST ABOUT 20-25KT AND GRADUALLY WEAKEN AND THE UPPER LEVEL SHIFTS INTO AR BY ABOUT 00Z. IFR CONDITIONS PROBABLE WHERE SNOW IS OCCURRING. RAPID CLEARING EXPECTED BEHIND THE TROUGH...WHICH IS EVIDENT IN VISIBLE SATELLITE IMAGES OVER WESTERN OK AT THIS TIME. /SA && .PREV DISCUSSION... /ISSUED 907 AM CST FRI DEC 28 2012/ DISCUSSION... THE BULK OF THE WARM CONVEYOR PRECIP IN ADVANCE OF AN APPROACHING UPPER TROUGH HAS SHIFTED EAST OF THE FORECAST AREA INTO ARKANSAS. A WELL DEFINED PV MAX WAS EVIDENT ON WV IMAGERY OVER WESTERN OK...AND A BAND OF SNOW HAS DEVELOPED OVER CENTRAL OK MOVING EAST. I HAVE INSERTED SOME AFTERNOON POPS INTO THE FORECAST FOR SNOW AND WILL ADJUST THE FORECAST AS NEEDED LATER TO SEE HOW THINGS EVOLVE. THE LATEST HRRR HAS ANOTHER BAND DEVELOPING OVER FAR EASTERN OK OR FAR WESTERN AR THIS AFTERNOON AS WELL. LACY .PRELIMINARY POINT TEMPS/POPS... TUL 34 16 40 21 / 70 0 0 0 FSM 39 23 38 21 / 20 0 0 0 MLC 37 18 39 19 / 50 0 0 10 BVO 34 14 41 13 / 30 0 0 0 FYV 36 17 35 15 / 20 0 0 0 BYV 35 19 35 20 / 20 0 0 0 MKO 36 16 38 19 / 70 0 0 10 MIO 35 16 36 18 / 60 0 0 0 F10 36 17 39 20 / 60 0 0 10 HHW 37 21 40 22 / 10 0 0 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...WINTER WEATHER ADVISORY UNTIL 6 PM FRIDAY FOR OKZ054-OKZ055- OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-OKZ063- OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070-OKZ071- OKZ072-OKZ073-OKZ074-OKZ075. AR...NONE. && $$ SHORT TERM...30 LONG TERM....10 AVIATION...02
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1148 AM CST FRI DEC 28 2012 .UPDATE...ADDED AVIATION SECTION FOR 18Z TAF`S. && .AVIATION...BNA/CKV/CSV...MORNING RA/IP HAS FOR THE MOST PART DISSIPATED, LEAVING MIDDLE TN WITH VFR CIGS AND GRADUALLY INCREASING WINDS. MUCH LARGER AREA OF LIGHT TO MODERATE RAIN IS MOVING INTO THE MID STATE AND WILL AFFECT US MUCH OF THE AFTERNOON. EXPECTING COLD FROPA DURING THE LATE EVENING AS THE SURFACE LOW TRACK BISECTS MIDDLE TENNESSEE. PROBABLY WON`T SEE ANY FROZEN PRECIP UNTIL AFTER FROPA, BUT BY THEN THE MOISTURE WILL HAVE THINNED OUT AND WE`LL BE LEFT WITH LIGHT RA/SN DURING THE OVERNIGHT PERIOD. LOOK FOR WINDS TO PICK UP TOWARD MORNING AS THE SURFACE PRESSURE GRADIENT INCREASES. THERE SHOULD BE ENOUGH LOW- LEVEL MOISTURE PRESENT AFTER 12Z TO KEEP LOW CLOUDS IN AND SQUEEZE OUT SOME COLD ADVECTION FLURRIES, BUT NOT EXPECTING ANY ACCUMULATION. && .PREV DISCUSSION... /ISSUED 747 AM CST FRI DEC 28 2012/ DISCUSSION... LATEST RADAR IMAGERY AND NUMEROUS REPORTS INDICATE A WIDESPREAD RAIN/SLEET MIX HAS OVERSPREAD THE SOUTHWESTERN PORTIONS OF MIDDLE TENNESSEE. SO FAR NO SIGNIFICANT ACCUMULATION HAS BEEN REPORTED...AND SURFACE OBSERVATIONS INDICATE TEMPERATURES ARE NOW AT OR ABOVE FREEZING FOR NEARLY ALL LOCATIONS. THUS A CHANGEOVER TO ALL RAIN IS STILL EXPECTED IN THE NEXT COUPLE OF HOURS AS TEMPERATURES/DEWPOINTS CONTINUE TO WARM. HAVE UPDATED FORECAST FOR THIS MORNING TO REMOVE MENTION OF FZRA AS PRECIP SHOULD BE PREDOMINATELY RAIN/SLEET. IN ADDITION...06Z GUIDANCE CONTINUES TREND FROM 00Z MODELS WITH LIGHT SNOW ACCUMULATIONS OVER NORTHWEST ZONES LATE FRIDAY EVENING INTO FRIDAY NIGHT AS CAA INCREASES AND TEMPERATURES FALL BACK TO NEAR FREEZING. ADJUSTED POPS/WX GRIDS ACCORDINGLY AND RAISED TOTAL SNOW ACCUMS IN THIS AREA INTO THE 0.5-1.0 INCH RANGE. WILL LET DAY SHIFT ANALYZE THE 12Z GUIDANCE TO SEE IF A WINTER WX ADVISORY WILL BE NECESSARY FOR THE NORTHWEST ZONES FRIDAY NIGHT. REST OF FORECAST REMAINS UNCHANGED. PREV DISCUSSION... /ISSUED 428 AM CST FRI DEC 28 2012/ UPDATE...FOR 12Z TAFS AVIATION...12Z TAFS RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET. CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY RESTRICTION AT CKV. PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/ SHORT TERM... SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL. WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM. BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED. AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE. LONG TERM... AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF 2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE FIRST PART OF JANUARY. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ROSE
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1132 AM CST FRI DEC 28 2012 .AVIATION... DRY SURFACE RIDGE OF HIGH PRESSURE BUILDING INTO S CENTRAL TX THIS AFTERNOON AND PREVAILING TONIGHT AND SATURDAY. VFR CONDITIONS PREVAILING FOR THE NEXT 24 HOURS...EXCEPT BKN-OVC MVFR CIGS WILL SKIRT THE NERN PARTS OF S CENTRAL TX...NE OF A LINE FROM KAGO(LLANO) TO KAUS(AUSTIN) TO K3T5(LA GRANGE) UNTIL ABOUT 00Z. OTHERWISE NW-NLY WINDS OF 10-15 KNOTS WITH GUSTS TO 25 KNOTS THIS AFTERNOON....BECOMING NEAR 10 KNOTS AFTER 00Z AND 5-10 KNOTS SATURDAY. && .PREV DISCUSSION... /ISSUED 1047 AM CST FRI DEC 28 2012/ UPDATE... ADJUSTED TEMPS/DEWPOINTS/WEATHER AND SKY GRIDS ACCORDINGLY FOR REST OF TODAY BASED ON LATEST SATELLITE PHOTOS/RADAR PROFILERS DATASETS AND SURFACE OBSERVATIONS AS WELL AS RUC13 AND HIRES (NMM/ARW) MODELING SOLUTIONS. NEW ZONES OUT SHORTLY. DISCUSSION... DRY AND STABLE CONDITIONS ARE IN STORE FOR SOUTH CENTRAL TEXAS LATE THIS MORNING INTO THE UPCOMING WEEKEND IN THE WAKE OF A COLD FRONT THAT MOVED THROUGH THE AREA EARLIER THIS MORNING. EXPECT BREEZY NORTHWEST TO NORTH WINDS AT 15 TO 20 MPH WITH GUSTS UP TO 30 MPH THIS AFTERNOON...ESPECIALLY ACROSS THE WESTERN HALF OF SOUTH CENTRAL TEXAS. AS A FRIENDLY REMINDER...A RED FLAG WARNING IS IN EFFECT FROM NOON UNTIL 7 PM CST THIS EVENING ACROSS THE WESTERN HALF OF OUR AREA DUE TO THIS CONDITIONS AND HUMIDITY VALUES FALLING TO THE TEENS AND 20 PERCENT RANGE. PREV DISCUSSION... /ISSUED 646 AM CST FRI DEC 28 2012/ UPDATE... WITH WEAK COOL AIR ADVECTION BREAKING UP MOST OF THE FOG...THIS UPDATE ALSO LOWERS HIGH TEMPERATURES UP TO 3 DEGREES OVER CENTRAL COUNTIES. WARMER TEMPERATURES UP TO THE LOW 70S REMAINS EXPECTED OVER FAR SW COUNTIES ONCE THE MID LEVEL WESTERLIES MIX DOWN WITH THE BASE OF THE UPPER TROUGH PASSING TO THE NORTH. PREV DISCUSSION... /ISSUED 550 AM CST FRI DEC 28 2012/ AVIATION... /12Z TAFS/ COLD FRONT WILL PROGRESS RAPIDLY EASTWARD THIS MORNING AS DRY AIR MIXES DOWN IN WEST NORTHWEST FLOW ALOFT. KDRT TERMINAL VFR CONDITIONS WITH A GRADUAL INCREASE IN NORTHWEST WINDS FROM 5 TO 10 KTS EARLY THIS MORNING TO NORTHWEST TO NORTH 15 TO 25 KTS BY NOON. NORTH WINDS LOWERING TO 5 TO 10 KTS AFTER DARK. KAUS TERMINAL GRADUAL LIFTING TO IFR CIGS VSBYS LIFTING TO MVFR IN FOG AND PATCHY DRIZZLE. BY LATE MORNING CONDITIONS BECOMING VFR. NORTHWEST WINDS 5 TO 10 KTS INCREASING TO NORTHWEST TO NORTH AT 10 TO 15 KTS BY LATE MORNING. KSAT TERMINAL MVFR CIGS AND VSBYS IN FOG EARLY THIS MORNING BECOMING VFR BY LATE MORNING. NORTHWEST WINDS 5 TO 10 KTS BECOMING NORTH 15 TO 25 KTS BY MIDDAY AND LOWERING TO NORTH AROUND 10 KTS AFTER DARK. PREV DISCUSSION... /ISSUED 406 AM CST FRI DEC 28 2012/ DISCUSSION... DENSE FOG EVENT CONTINUES ACROSS NEARLY ALL COUNTIES. AS A COLD FRONT DRAWS CLOSER TO THE AREA...SOME ADJUSTMENT MAY BE NEEDED TO THE HAZARD AREA THAT CONTINUES AFTER DAYBREAK. BY NOON MODELS SHOW ALL THE FOG CLEARED OF THE AREA...ALONG WITH ANY PRECIPITATION. COLD AIR OVER THE CENTRAL PLAINS ENHANCED BY SNOWFALL SHOULD REINFORCE FREEZING NIGHTTIME TEMPERATURES OVER ALL AREAS FOR SATURDAY MORNING. WILL AVOID FORECASTING THE COLDER GUIDANCE NUMBERS...AS WINDS WILL NOT HAVE A CHANCE TO DECOUPLE BY DAYBREAK SATURDAY. FILTERED SUNSHINE FROM THIN HIGH CLOUDS AND THE COLD ADVECTION SHOULD KEEP AFTERNOON HIGHS ABOUT 10 DEGREES BELOW NORMAL...WITH ANOTHER FREEZE TO FOLLOW FOR MOST AREAS SUNDAY. AREAS TO THE SOUTHWEST MAY NOT HIT FREEZING SUNDAY DUE TO INCREASING CLOUDS AND RETURN FLOW ABOUT THE SURFACE RIDGE. LATE SUNDAY THROUGH MONDAY NIGHT...GOOD RAIN CHANCES DEVELOP OVER TX AS AN UPPER TROUGH DIGS OVER NW MEXICO. THE RUN-TO-RUN GFS MODEL TRENDS FAVOR DECREASING TROUGH DEPTH WHICH IS A COMMON GFS TRAIT TO OVERFORECAST RAIN FOR THE AREA IN THE MEDIUM RANGE. WILL CONTINUE TO SCALE BACK POPS OFF THE MEX GUIDANCE BY ABOUT 20-30 PERCENT MONDAY. THE GENERAL PATTERN OF THE GFS IS FAVORED OVER THE ECMWF WHICH OFFERS A MORE PROLONGED OPPORTUNITY FOR RAIN FROM A SECONDARY UPPER LOW TO MOVE THROUGH WEDNESDAY. NEW YEARS EVE PROJECTIONS THUS FAVOR A DAMP EVENING FOR MOST AREAS...WITH DRYING AND A REINFORCING COLD FRONT OVERNIGHT ON THE 1ST. FURTHER NORTHWARD ADJUSTMENTS OF THE UPPER TROUGH COULD MEAN A MORE FIRE WEATHER SENSITIVE FORECAST FOR NEW YEARS EVE. THE SECONDARY UPPER LOW COULD ALSO PRESENT SOME WINTER WEATHER POSSIBILITIES FOR WEDNESDAY...BUT WITH THE MEDIUM RANGE FORECSTS IN LOW CONFIDENCE...WILL STEER CLEAR OF PROJECTING ANY WINTER WEATHER FOR NOW. FIRE WEATHER... A LOW END CRITICAL FIRE WEATHER EVENT FOR TODAY MAY NEED TO BE CONSIDERED FOR AT LEAST THE WESTERN 1/3. RH VALUES WILL LIKELY REACH CRITERIA OVER THE RIO GRANDE PLAINS...BUT THE WIND SPEEDS WILL BE MARGINAL GIVEN THE EXPECTED MIXING OF DIRECTIONAL SHEAR IN THE WINDS ALOFT TO POSSIBLY LOWER SURFACE WINDS BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 60 26 52 29 55 / 10 0 0 0 10 AUSTIN BERGSTROM INTL AIRPORT 61 26 51 21 55 / 10 0 0 0 10 NEW BRAUNFELS MUNI AIRPORT 64 28 54 26 57 / 10 0 0 0 10 BURNET MUNI AIRPORT 55 24 49 26 51 / 10 0 0 0 10 DEL RIO INTL AIRPORT 66 31 55 34 54 / 0 0 0 - 20 GEORGETOWN MUNI AIRPORT 59 23 51 25 54 / 10 0 0 0 10 HONDO MUNI AIRPORT 65 26 55 28 55 / 10 0 0 - 10 SAN MARCOS MUNI AIRPORT 62 28 53 24 56 / 10 0 0 0 10 LA GRANGE - FAYETTE REGIONAL 63 30 52 30 57 / 30 0 0 0 10 SAN ANTONIO INTL AIRPORT 65 29 54 29 56 / 10 0 0 0 10 STINSON MUNI AIRPORT 67 29 55 30 57 / 10 0 0 0 10 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BEXAR...DIMMIT...EDWARDS...FRIO... GILLESPIE...KENDALL...KERR...KINNEY...MAVERICK...MEDINA...REAL... UVALDE...VAL VERDE...ZAVALA. && $$ MESOSCALE/AVIATION...01 SYNOPTIC/GRIDS...17 PUBLIC SERVICE/DATA COLLECTION...30
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1047 AM CST FRI DEC 28 2012 .UPDATE... ADJUSTED TEMPS/DEWPOINTS/WEATHER AND SKY GRIDS ACCORDINGLY FOR REST OF TODAY BASED ON LATEST SATELLITE PHOTOS/RADAR PROFILERS DATASETS AND SURFACE OBSERVATIONS AS WELL AS RUC13 AND HIRES (NMM/ARW) MODELING SOLUTIONS. NEW ZONES OUT SHORTLY. && .DISCUSSION... DRY AND STABLE CONDITIONS ARE IN STORE FOR SOUTH CENTRAL TEXAS LATE THIS MORNING INTO THE UPCOMING WEEKEND IN THE WAKE OF A COLD FRONT THAT MOVED THROUGH THE AREA EARLIER THIS MORNING. EXPECT BREEZY NORTHWEST TO NORTH WINDS AT 15 TO 20 MPH WITH GUSTS UP TO 30 MPH THIS AFTERNOON...ESPECIALLY ACROSS THE WESTERN HALF OF SOUTH CENTRAL TEXAS. AS A FRIENDLY REMINDER...A RED FLAG WARNING IS IN EFFECT FROM NOON UNTIL 7 PM CST THIS EVENING ACROSS THE WESTERN HALF OF OUR AREA DUE TO THIS CONDITIONS AND HUMIDITY VALUES FALLING TO THE TEENS AND 20 PERCENT RANGE. && .PREV DISCUSSION... /ISSUED 646 AM CST FRI DEC 28 2012/ UPDATE... WITH WEAK COOL AIR ADVECTION BREAKING UP MOST OF THE FOG...THIS UPDATE ALSO LOWERS HIGH TEMPERATURES UP TO 3 DEGREES OVER CENTRAL COUNTIES. WARMER TEMPERATURES UP TO THE LOW 70S REMAINS EXPECTED OVER FAR SW COUNTIES ONCE THE MID LEVEL WESTERLIES MIX DOWN WITH THE BASE OF THE UPPER TROUGH PASSING TO THE NORTH. PREV DISCUSSION... /ISSUED 550 AM CST FRI DEC 28 2012/ AVIATION... /12Z TAFS/ COLD FRONT WILL PROGRESS RAPIDLY EASTWARD THIS MORNING AS DRY AIR MIXES DOWN IN WEST NORTHWEST FLOW ALOFT. KDRT TERMINAL VFR CONDITIONS WITH A GRADUAL INCREASE IN NORTHWEST WINDS FROM 5 TO 10 KTS EARLY THIS MORNING TO NORTHWEST TO NORTH 15 TO 25 KTS BY NOON. NORTH WINDS LOWERING TO 5 TO 10 KTS AFTER DARK. KAUS TERMINAL GRADUAL LIFTING TO IFR CIGS VSBYS LIFTING TO MVFR IN FOG AND PATCHY DRIZZLE. BY LATE MORNING CONDITIONS BECOMING VFR. NORTHWEST WINDS 5 TO 10 KTS INCREASING TO NORTHWEST TO NORTH AT 10 TO 15 KTS BY LATE MORNING. KSAT TERMINAL MVFR CIGS AND VSBYS IN FOG EARLY THIS MORNING BECOMING VFR BY LATE MORNING. NORTHWEST WINDS 5 TO 10 KTS BECOMING NORTH 15 TO 25 KTS BY MIDDAY AND LOWERING TO NORTH AROUND 10 KTS AFTER DARK. PREV DISCUSSION... /ISSUED 406 AM CST FRI DEC 28 2012/ DISCUSSION... DENSE FOG EVENT CONTINUES ACROSS NEARLY ALL COUNTIES. AS A COLD FRONT DRAWS CLOSER TO THE AREA...SOME ADJUSTMENT MAY BE NEEDED TO THE HAZARD AREA THAT CONTINUES AFTER DAYBREAK. BY NOON MODELS SHOW ALL THE FOG CLEARED OF THE AREA...ALONG WITH ANY PRECIPITATION. COLD AIR OVER THE CENTRAL PLAINS ENHANCED BY SNOWFALL SHOULD REINFORCE FREEZING NIGHTTIME TEMPERATURES OVER ALL AREAS FOR SATURDAY MORNING. WILL AVOID FORECASTING THE COLDER GUIDANCE NUMBERS...AS WINDS WILL NOT HAVE A CHANCE TO DECOUPLE BY DAYBREAK SATURDAY. FILTERED SUNSHINE FROM THIN HIGH CLOUDS AND THE COLD ADVECTION SHOULD KEEP AFTERNOON HIGHS ABOUT 10 DEGREES BELOW NORMAL...WITH ANOTHER FREEZE TO FOLLOW FOR MOST AREAS SUNDAY. AREAS TO THE SOUTHWEST MAY NOT HIT FREEZING SUNDAY DUE TO INCREASING CLOUDS AND RETURN FLOW ABOUT THE SURFACE RIDGE. LATE SUNDAY THROUGH MONDAY NIGHT...GOOD RAIN CHANCES DEVELOP OVER TX AS AN UPPER TROUGH DIGS OVER NW MEXICO. THE RUN-TO-RUN GFS MODEL TRENDS FAVOR DECREASING TROUGH DEPTH WHICH IS A COMMON GFS TRAIT TO OVERFORECAST RAIN FOR THE AREA IN THE MEDIUM RANGE. WILL CONTINUE TO SCALE BACK POPS OFF THE MEX GUIDANCE BY ABOUT 20-30 PERCENT MONDAY. THE GENERAL PATTERN OF THE GFS IS FAVORED OVER THE ECMWF WHICH OFFERS A MORE PROLONGED OPPORTUNITY FOR RAIN FROM A SECONDARY UPPER LOW TO MOVE THROUGH WEDNESDAY. NEW YEARS EVE PROJECTIONS THUS FAVOR A DAMP EVENING FOR MOST AREAS...WITH DRYING AND A REINFORCING COLD FRONT OVERNIGHT ON THE 1ST. FURTHER NORTHWARD ADJUSTMENTS OF THE UPPER TROUGH COULD MEAN A MORE FIRE WEATHER SENSITIVE FORECAST FOR NEW YEARS EVE. THE SECONDARY UPPER LOW COULD ALSO PRESENT SOME WINTER WEATHER POSSIBILITIES FOR WEDNESDAY...BUT WITH THE MEDIUM RANGE FORECSTS IN LOW CONFIDENCE...WILL STEER CLEAR OF PROJECTING ANY WINTER WEATHER FOR NOW. FIRE WEATHER... A LOW END CRITICAL FIRE WEATHER EVENT FOR TODAY MAY NEED TO BE CONSIDERED FOR AT LEAST THE WESTERN 1/3. RH VALUES WILL LIKELY REACH CRITERIA OVER THE RIO GRANDE PLAINS...BUT THE WIND SPEEDS WILL BE MARGINAL GIVEN THE EXPECTED MIXING OF DIRECTIONAL SHEAR IN THE WINDS ALOFT TO POSSIBLY LOWER SURFACE WINDS BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 26 52 29 55 46 / 0 0 0 10 30 AUSTIN BERGSTROM INTL AIRPORT 26 51 21 55 42 / 0 0 0 10 30 NEW BRAUNFELS MUNI AIRPORT 28 54 26 57 45 / 0 0 0 10 30 BURNET MUNI AIRPORT 24 49 26 51 43 / 0 0 0 10 40 DEL RIO INTL AIRPORT 31 55 34 54 44 / 0 0 - 20 20 GEORGETOWN MUNI AIRPORT 23 51 25 54 42 / 0 0 0 10 30 HONDO MUNI AIRPORT 26 55 28 55 46 / 0 0 - 10 30 SAN MARCOS MUNI AIRPORT 28 53 24 56 44 / 0 0 0 10 30 LA GRANGE - FAYETTE REGIONAL 30 52 30 57 47 / 0 0 0 10 30 SAN ANTONIO INTL AIRPORT 29 54 29 56 47 / 0 0 0 10 30 STINSON MUNI AIRPORT 29 55 30 57 47 / 0 0 0 10 30 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BEXAR...DIMMIT...EDWARDS...FRIO... GILLESPIE...KENDALL...KERR...KINNEY...MAVERICK...MEDINA...REAL... UVALDE...VAL VERDE...ZAVALA. && $$ MESOSCALE/AVIATION...01 SYNOPTIC/GRIDS...17 PUBLIC SERVICE/DATA COLLECTION...30