Area Forecast Discussion
Issued by NWS Charleston, WV

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173
FXUS61 KRLX 141048
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
548 AM EST SUN FEB 14 2016

.SYNOPSIS...
COMPLEX SYSTEM OVERRUNS SLOWLY EXITING ARCTIC AIR TODAY THROUGH
MONDAY...FOR A MESSY CONCOCTION OF WINTRY WEATHER. THE SYSTEM
EXITS EARLY TUESDAY...FOLLOWED BY ANOTHER TUESDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
FOCUS IN THE NEAR TERM IS ALMOST ENTIRELY ON THE UPCOMING WINTER
STORM THREAT. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH SYNOPTIC
PATTERN AS WELL AS LOW LEVEL THERMAL PROFILES. THIS IS ENTIRELY SNOW
IN THE NEAR TERM WITH THIS UPPER LEVEL SYSTEM AND WAA EVENT. WHERE
THE MODELS DIVERGE IS QPF AMOUNTS WHICH COULD MEAN THE DIFFERENCE
BETWEEN 12 HR WARNING CRITERIA OR AN ADVISORY. THE NAM SEEMS TO BE
THE WETTEST...ESPECIALLY ALONG AND N OF THE I64 CORRIDOR. GIVEN THE
LINGERING DRY ARCTIC AIRMASS IN PLACE...ELECTED TO SIDE WITH A TAMER
GFS WITH SOME INCORPORATION OF WPC GUIDANCE. NO DOUBT THE FIRST FEW
HOURS OF ECHOES ON THE RADAR WILL GO TO MOISTENING THE COLUMN...SO
TRIED TO SHAVE A BIT OFF THE SNOW AMOUNTS TO ACCOUNT FOR THIS ALONG
WITH A LATER START TIME TO HEADLINES BY AN HOUR OR SO. AFTER
COLLABORATION WITH SURROUNDING OFFICES...WE ISSUED A WINTER STORM
WARNING FOR THE COAL FIELDS/SW VA/SE WV PLATEAU/POCAHONTAS COUNTY.
THINKING 12 HR CRITERIA WILL BE MET WITH GENERALLY 3 TO 5 INCHES
EXPECTED BY MID MORNING MONDAY AND 4 TO 6 INCHES IN RALEIGH COUNTY.
POCAHONTAS WILL SEE A PROLONGED EVENT GIVEN COLD AIR DAMMING WHICH
THE SHORT TERM FORECASTER WILL COVER. WE ISSUED AN ADVISORY FOR NE
KY AND MOST OF SE OH AS WELL AS THE I 64 CORRIDOR IN WV. LOOKING AT
PRIMARILY 1 TO 3 WITH THE HIGHER END OF THAT SPECTRUM IN NE KY AND
ALONG I64 CORRIDOR IN WV LOWLANDS. WE ALSO ISSUED AN ADVISORY FOR
FAYETTE/NICHOLAS/RANDOLPH FOR SNOW AND EVENTUALLY SOME FREEZING RAIN
ON THE EASTERN PORTIONS OF THE THOSE COUNTIES BEYOND THE NEAR TERM.

SO...EXPECT SNOW TO DEVELOP FROM SW TO NE LATE THIS AFTERNOON AND
INTO THIS EVENING...BECOMING HEAVY AT TIMES IN SW VA AND S WV.
TEMPERATURES WILL FALL THIS AFTERNOON WITH WETBULBING AND HOLD
NEARLY STEADY IN THE 20S LOWLANDS AND TEENS MOUNTAINS TONIGHT BEFORE
RISING TOWARD MORNING.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
PERIOD STARTS WITH AN ONGOING WARM ADVECTION EVENT MON MORNING
THAT CONTINUES MUCH OF THE DAY. DEEP LAYER SW FLOW OVERRUNS LOW
LEVEL SE FLOW AT THE SFC...IN THE WAKE OF AN UPPER LEVEL S/W
TROUGH LIFTING AWAY FROM THE AREA THROUGH THE ERN GREAT LAKES AND
THE UPPER OHIO VALLEY. THE WARMING BRINGS THE COLUMN ABOVE
FREEZING BELOW H85...BUT WITH A SFC-BASED COLD LAYER HANGING ON
MUCH OF THE DAY ACROSS THE LOWLANDS...AND THROUGH MON NT IN THE
MOUNTAINS.

MODELS HAVE SLOWED BACK DOWN WITH A SECOND S/W TROUGH THAT
APPROACHES THE AREA MON NT AND THEN CROSSES TUE MORNING.  THIS
GENERATES A RELATIVELY WEAK SFC LOW OVER THE TN VALLEY MON THAT THEN
TRACKS NE ACROSS THE LOWLANDS OF THE FCST AREA MON NT.  THIS TAKES
OUT THE SFC BASED COLD LAYER ACROSS MUCH OF THE LOWLANDS BUT THE
COLD AIR DAMMING WEDGE E OF THE APPALACHIANS PERSISTS.

THE TRACK OF THE SYSTEM RIGHT OVER THE AREA LEAVES THE COLUMN
BELOW H85 VERY CLOSE TO FREEZING THROUGHOUT MUCH OF THE AREA MUCH
OF MON...AND ACROSS NW PORTIONS OF THE AREA...AND IN THE
MOUNTAINS...MON NT AND TUE. THIS GIVES RISE TO MUCH UNCERTAINTY IN
THE FCST PRECIPITATION TYPES AND AMOUNTS.

THE WARM ADVECTION EVENT ONGOING FROM THE NEAR TERM INTO MON
FEATURES A QPF AXIS ACROSS SRN PORTIONS OF THE AREA...MOST OF IT
OCCURRING WHILE THE COLUMN IS STILL COLD ENOUGH TO SUPPORT SNOW.
MOST OF THE ICE IN THIS EVENT COMES MON NT AS WARM AIR ALOFT
OVERRIDES THE COLD AIR IN THE DAMMING WEDGE E OF THE
APPALACHIANS. HAVE UP TO A QUARTER INCH OF ICE IN THE GREENBRIER
VALLEY...BUT THERE IS THE POTENTIAL FOR MORE AS THE NAM SUGGESTS.

AS A RESULT...WARNINGS FOR SNOW ARE POSTED INTO MON FOR THE SRN
COAL FIELDS AND THE SRN MOUNTAINS...AND FOR SNOW AND ICE IN THE
GREENBRIER VALLEY INTO TUE MORNING. ADVISORIES MOSTLY FOR SNOW
ARE POSTED INTO MON FOR THE CENTRAL LOWLANDS AND FOR SNOW...AND A
BIT OF ICE ON THE ERN EDGES...FOR THE CENTRAL AND NRN MOUNTAINS
OF WV THROUGH MON NT.

AFTER A DRIER BUT OVERCAST INTERLUDE BETWEEN SYSTEMS TUE...06Z
MODEL RUNS ARE FARTHER S WITH ANOTHER UPPER LEVEL S/W TROUGH AND
ASSOCIATED LOW PRESSURE SYSTEM PROGGED TO CROSS TUE NT. THIS WOULD
BRING COLDER AIR BACK INTO THE AREA FROM THE W THROUGHOUT THE
COLUMN OVERNIGHT TUE NT...CHANGING ANY RAIN...FREEZING RAIN OR
MIXED PRECIPITATION THAT RETURNS TUE EVENING...BACK TO SNOW...WITH
LIGHT ADDITIONAL AMOUNTS POSSIBLE.

USED MOSTLY A NAM/GFS BLEND FOR TEMPERATURES SFC AND ALOFT...ALSO
INCLUDED THE ECMWF AND WPC FOR QPF.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
BEHIND THE DEPARTING LOW...ANOTHER CLIPPER TYPE SYSTEM EXPECTED TO
IMPACT THE AREA...BRINGING A REINFORCING SHOT OF COOL AIR...AND
CREATING LIGHT SNOW SHOWERS LATE TUESDAY NIGHT INTO WEDNESDAY. THERE
ARE DIFFERENCES BETWEEN THE MODELS WITH THIS SYSTEM...WITH GFS AND
NAM INDICATING A STRONGER SYSTEM THAN THE ECMWF. GENERALLY FIGURING
AN INCH OR LESS ACROSS THE LOWLANDS...WITH 1 TO 3 ACROSS THE HIGHER
TERRAIN. SOME LIGHT SNOW SHOWERS ARE STILL POSSIBLE THROUGH
WEDNESDAY EVENING IN THE NORTHWESTERLY FLOW BEHIND THE DEPARTING
SYSTEM. DRIER...AND GRADUALLY WARMING WEATHER EXPECTED BEHIND THE
CLIPPER...WITH ANOTHER SYSTEM POSSIBLE LATE IN THE WEEK.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
SURFACE HIGH WILL PROVIDE FOR LIGHT WINDS THIS MORNING. VFR
CONDITIONS WILL PREVAIL THRU 18Z AS MID/HI CLOUDS OVERSPREAD THE
AREA. EXCEPTION BEING SOME PESKY STRATOCU OVER THE N MOUNTAINS
WHICH MAY BRING KEKN/KCKB A PERIOD OF MVFR CIGS EARLY THIS
MORNING.

AN UPPER LEVEL SYSTEM WILL BE APPROACHING IN THE AFTERNOON WITH
SNOW OVERSPREADING THE AREA FROM SW TO NE THRU THE EVENING. GIVEN
DRY AIRMASS IN PLACE...VIRGA MAY BE REALIZED FOR A TIME BEFORE
SNOW BEGINS TO REACH THE GROUND. HAVE USED THIS THINKING IN
FORMULATING THE TAFS. AS THE SNOW REACHES THE GROUND CLOUDS BASES
WILL LOWER INTO MVFR AS VSBY LOWERS INTO MVFR AND IFR. LOCALIZED
LIFR VSBY IS POSSIBLE IN ANY HEAVIER SNOW BURSTS. TIMING LOOKS TO
BE IN THE 21 TO 00Z TIME FRAME FOR KHTS/KBKW/KCRW AND 02 TO 04Z
TIME FRAME FOR N TERMINALS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...

FORECAST CONFIDENCE: MEDIUM

ALTERNATE SCENARIOS: TIMING OF SNOWFALL TOMORROW MAY VARY A FEW
HOURS FROM FORECAST.

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               SUN 02/14/16
UTC 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
EST 1HRLY       05   06   07   08   09   10   11   12   13   14   15   16
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z MONDAY...
IFR CONDITIONS POSSIBLE IN LIGHT SNOW TOMORROW NIGHT AND
MONDAY...TRANSITIONING TO A MIXED PRECIPITATION EVENT FOR MONDAY
INTO TUESDAY. WESTERN SLOPES MAY IMPROVE FOR A TIME MONDAY.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
     TUESDAY FOR WVZ036>038-047.
     WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 1 PM EST
     MONDAY FOR WVZ024-025-033>035.
     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
     MONDAY FOR WVZ005>008-013>016-026-027.
     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 AM EST
     TUESDAY FOR WVZ046.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
     MONDAY FOR OHZ083>087.
KY...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
     MONDAY FOR KYZ101>103-105.
VA...WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 1 PM EST
     MONDAY FOR VAZ003-004.

&&

$$
SYNOPSIS...TRM/30
NEAR TERM...30
SHORT TERM...TRM
LONG TERM...SL
AVIATION...30



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