Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 311519
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1119 AM EDT FRI OCT 31 2014

.SYNOPSIS...
LOW PRESSURE DROPS SOUTHEAST/INTENSIFYING OFF NORTH CAROLINA COAST
SATURDAY. COLD POOL ALOFT MOVES THROUGH SOUTHERN COUNTIES OVERNIGHT
INTO SATURDAY MORNING. SNOW ACCUMULATION MAINLY IN MOUNTAIN COUNTIES.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPDATED POPS EASTERN PROGRESSION A TAD QUICKER AS PER RADAR. DID
ADJUST QPF AND SNOW AMOUNTS A TAD ACROSS THE EASTERN RIDGES OF OUR
SW VA COUNTIES AS PER NEW MODEL TRENDS. OTHERWISE NO OTHER MAJOR
CHANGES EXPECTED.

PREVIOUS DISCUSSION...
UNDER THE COVER OF DARKNESS LAST NIGHT...CLEARING OCCURRED OVER
SOUTHERN AND CENTRAL WEST VIRGINIA. THIS ALLOWED TEMPERATURES IN
SOME OF THE WESTERN VALLEYS TO DROP TO AROUND FREEZING.

IN CASE YOU MISSED THE PNS FROM THURSDAY EVENING...WITH OCTOBER
ENDING RLX HAS TERMINATED ITS FROST/FREEZE PROGRAM FOR THE AUTUMN.
SO THERE WILL BE NO FROST/FREEZE HEADLINES FROM US THIS NOVEMBER
WEEKEND.

IN OUR FAST PACE PATTERN...CLOUDS ARE QUICKLY INCREASING AGAIN FROM
THE WEST OVER THE OHIO RIVER COUNTIES THIS PREDAWN.  NO MAJOR
CHANGES ON TIMING THE INCREASING POPS FROM WEST TO EAST
TODAY...MAYBE A BIT SLOWER REACHING THE WV MOUNTAIN COUNTIES.  WILL
TRY TO HOLD DOWN MAXIMUM TEMPERATURE IN THE WEST WITH THE CLOUDS AND
SHOWERS/RAIN.

500 MB LOW DROPS SOUTH FROM WI AT 07Z TO NEAR SDF AT 00Z THEN
REACHING SE OF THE SMOKY MOUNTAINS BY 12Z SATURDAY. COULD SEE A FEW
SEPARATE AREAS OF RAIN TODAY...BEFORE COVERAGE INCREASES WITH
DYNAMICS AHEAD OF...AND NORTH OF THE 500 MB LOW...LATE TODAY AND
OVERNIGHT.  COULD NOT COMPLETELY RULE OUT AN EMBEDDED THUNDER IN OUR
SOUTHERN COUNTIES THIS EVENING AS 500 MB TEMPS DROP.

OF COURSE...THE COLDEST AIR AT 850 MB IS ALONG AND TO THE WEST OF
THE 500 MB TRACK...WHICH LEAVES A 2 TO 3C GRADIENT IN 850 MB TEMP
JUST SW OF HTS-CRW OVERNIGHT.  IN THERE WAS ANY TREND IN THE
AMERICAN MODELS OVERNIGHT...MAYBE A SLIGHT TENDENCY TOWARD WARMER
ALOFT FROM HTS-CRW-BKW.  DID INCREASE LOW TEMPERATURE A DEGREE OR SO
FROM CRW TO BKW.

HAVE THE FIRST FLAKES IN OUR CWA OVER THE HIGH TERRAIN OF DICKENSON
COUNTY AROUND 00Z SATURDAY- THIS FRIDAY EVENING.  WILL ALSO INCREASE
THE WINDS OVER SOUTHWEST VIRGINIA TONIGHT IN THE COLD AIR
ADVECTION.  DID INCREASE SNOW AMOUNTS OVER THE HIGH TERRAIN IN
BUCHANAN AND DICKENSON COUNTIES TO AROUND 4 INCHES BY DAWN. ALSO
ADDED AN INCH OR LESS OVER HILLTOPS IN INTERIOR NE KY.

NO CHANGES PLANNED IN THE COUNTIES UNDER OUR WINTER HEADLINES.
DEPENDING ON WHERE THE MID/UPPER SUPPORT SET UP THE BURST OF SNOW
06Z TO 12Z SATURDAY...COULD SEE MORE SNOW OVER THE HIGH TERRAIN IN
THE HEADLINE COUNTIES...BEFORE THE COLD POOL DRAINS AWAY.

OUR SNOW AMOUNTS NOT THAT MUCH LESS IN RALEIGH COUNTY...BUT OF
COURSE...THERE IS A HIGHER SNOW CRITERIA SET THERE FOR HEADLINES.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
UPPER LEVEL LOW CROSSES CAROLINAS ON SATURDAY AS IT GRADUALLY GETS
OVERPOWERED AND ABSORBED INTO A LOW DEVELOPING OVER EASTERN CANADA.
AS THIS HAPPENS PRECIP OVER THE CWA WILL BECOME MORE UPSLOPE TYPE
AND NW FLOW MOVE IN. THE LOWLANDS WILL GRADUALLY WARM SATURDAY
CHANGING SNOW BACK TO RAIN....HOWEVER IT WILL STILL BE A RATHER RAW
DAY WITH GUSTY WINDS AND HIGH TEMPS ONLY GETTING INTO THE LOW 40S
ACROSS THE LOWLANDS...WITH MID TO UPPER 30S HIGHER UP. DEPENDING
JUST HOW LONG MOISTURE HANGS ON...THE WV LOWLANDS MAY TRANSITION
BACK TO SNOW SATURDAY NIGHT AS PRECIP QUICKLY WINDS DOWN FROM WEST
TO EAST. SOME LIGHT SNOW MAY LINGER IN THE NORTHERN MOUNTAINOUS
COUNTIES INTO SUNDAY AFTERNOON...WITH GENERALLY A COUPLE INCHES OF
SNOW AT MID AND HIGH ELEVATIONS SATURDAY AND SUNDAY. HIGH PRESSURE
NOSES IN FROM THE SOUTHWEST FOR SUNDAY INTO SUNDAY NIGHT.

BLENDED IN BIAS-CORRECTED MOSGUIDE FOR HIGHS...AND SATURDAY NIGHT.
MAIN CHANGE WAS A TOUCH COOLER SATURDAY NIGHT. USED WPC GUIDANCE FOR
SUNDAY NIGHT RESULTING IN MINIMAL CHANGES.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
STRONG DRY CANADIAN HIGH PRESSURE WILL BE THE DOMINANT FEATURE
THROUGH MONDAY NIGHT. THE HIGH PRESSURE CENTER WILL SETTLE OVER THE
AREA SUNDAY NIGHT...THEN SHIFT OFF THE ATLANTIC COAST MONDAY. THIS
WILL BRING A DRAMATIC TURNAROUND IN TEMPERATURES THIS PERIOD. WELL
BELOW NORMAL TEMPERATURES SUNDAY NIGHT WITH WIDESPREAD SUB FREEZING
TEMPERATURES UNDER THE CENTER OF HIGH PRESSURE...WILL WARM UP TO
NEAR NORMAL VALUES BY TUESDAY AS THE HIGH SHIFTS OFF THE ATLANTIC
COAST.

MODELS SHOW ANOTHER UPPER TROUGH DIGGING INTO THE MISSISSIPPI VALLEY
AND DRIVING A COLD FRONT EASTWARD BY THE MIDDLE PART OF NEXT WEEK.
MODELS HAVE SLOWED THIS SYSTEM DOWN A BIT AS A WAVE OF LOW PRESSURE
RIPPLES UP ALONG THE FRONT THROUGH THE WESTERN OHIO VALLEY MONDAY
NIGHT AND TUESDAY. THIS SYSTEM WILL AFFECT OUR AREA LATE TUESDAY AND
ESPECIALLY ON WEDNESDAY. BY THIS TIME... TEMPERATURES WILL BE WELL
ABOVE FREEZING FOR A RAIN EVENT.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MORNING UPDATE...
DID MAKE A FEW MINOR ADJUSTMENTS TO TAFS FOR VSBY AND CIGS EARLY
ON. SOME MVFR CONDITIONS POSSIBLE THIS AFTERNOON WITH RAIN SHOWERS
MOVING THROUGH. REST OF FORECAST ON TRACK TIL NEXT ISSUANCE.

PREVIOUS DISCUSSION...
SOME LOCAL MVFR IN VALLEY FOG DID FORM OVER SOUTHERN WV FOR THE
PREDAWN. SOME 5 TO 6 MILES IN HAZE MAY LINGER PAST 12Z AS CLOUDS
INCREASE.

CEILINGS AT 4 TO 7 THSD FT INCREASING W TO E 12Z TO 15Z TODAY.
SPOTTY LIGHT RAIN OR LIGHT RAIN SHOWERS DEVELOPING OVER OHIO VALLEY
COUNTIES 12Z TO 15Z...SPREADING EAST DURING THE AFTERNOON.

CONDITIONS DETERIORATING OVER TRI STATE AROUND HTS INCLUDING NE KY
AND SE OHIO 18Z TO 21Z AS MID LEVEL SUPPORT INCREASES...AHEAD OF
STRONG 500 MB LOW.  WITH THIS SUPPORT DROPPING SE THROUGH SOUTHERN
WV...TRIED TO BE SLOW LOWERING CONDITIONS FURTHER N...INCLUDING
VCNTY CKB AND NORTH CENTRAL WV.

CEILINGS LOWERING INTO 1 TO 3 THSD FT AND VSBY AOB 3 MILES IN
RAIN...BECOMING MIXED WITH SNOW MAINLY S OF A HTS-CRW LINE BY 03Z
AND MOSTLY SNOW BY 03Z OVER DICKENSON AND BUCHANAN COUNTIES IN SW VA
UNDER THE COOL POOL ALOFT.  HARD TO DETERMINE IF BKW WILL GO TO ALL
SNOW OR STAY MIX...WITH COLDEST 850 MB TEMPERATURES PASSING TO ITS
SOUTH.

SURFACE AND LOW LEVEL WINDS INCREASING OVER EASTERN KENTUCKY ON SE
INTO THE BORDER COUNTIES OF SOUTHERN WEST VIRGINIA AND SOUTHWEST
VIRGINIA 00Z TO 06Z. IN CONTRAST...WINDS NEAR SURFACE REMAIN
FAIRLY LIGHT OVER NORTH CENTRAL WV INCLUDING CKB THROUGH 06Z
SATURDAY...BEFORE BECOMING NORTH NEAR 10 KNOTS BY 12Z SATURDAY.

HARD TO FIGURE HOW LOW CEILINGS DROP FROM 06Z TO 12Z
SATURDAY...ESPECIALLY AWAY FROM THE DYNAMICS...LIKE PKB TO CKB
CORRIDOR.

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

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: TIMING THE DETERIORATING CONDITIONS 18Z TODAY
THROUGH 00Z SATURDAY MAY VARY.  BKW MAY STAY MIXTURE RATHER THAN ALL
SNOW BEFORE 12Z SATURDAY.

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.

UTC 1HRLY       14   15   16   17   18   19   20   21   22   23   00   01
EDT 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
CRW CONSISTENCY  H    H    H    H    H    H    H    L    H    H    M    H
HTS CONSISTENCY  H    H    H    M    H    H    H    M    H    M    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    M    H    H    M    H    H    M    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    H

AFTER 12Z SATURDAY...
WIDESPREAD IFR IN RAIN/SNOW AND LOW CLOUDS 06Z TO 18Z
SATURDAY...LINGERING INTO SATURDAY NIGHT FOR THE MOUNTAIN COUNTIES
INCLUDING AROUND EKN AND BKW.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 2 PM EDT
     SATURDAY FOR WVZ033-034.
OH...NONE.
KY...NONE.
VA...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 2 PM EDT
     SATURDAY FOR VAZ003-004.

&&

$$
SYNOPSIS...KTB/MZ
NEAR TERM...JS/KTB
SHORT TERM...MZ
LONG TERM...JMV
AVIATION...JS/KTB








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