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