508 
FXUS61 KRLX 270237
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1037 PM EDT FRI OCT 26 2012

.SYNOPSIS...
A COLD FRONT OOZES THROUGH THE MIDDLE OHIO VALLY TONIGHT...AND THE 
CENTRAL APPALACHIANS SATURDAY.  SANDY COMBINES WITH A STRONG UPPER 
LEVEL SYSTEM TO IMPACT THE AREA SUNDAY THROUGH MUCH OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
UPDATE...
SHOWERS VERY SLOW TO MOVE INTO WESTERN ZONES...AND WILL CONTINUE
TO BE THE CASE OVERNIGHT. THEREFORE...TRIMMED POPS BACK EVEN MORE
WITH THE EXCEPTION OF PERRY COUNTY.

SANDY CONTINUES TO MAKE NORTHWARD PROGRESS AND HAVING SOME EFFECT
ON THE SLOWNESS OF THE COLD FRONT AND LINE OF SHOWERS.

PREVIOUS DISCUSSION...
COLD FRONT IS EXTREMELY SLOW MOVING BUT MODELS ARE IN GOOD 
AGREEMENT.  TEMPERATURES ARE REALLY TRICKY.  COULD NOT USE A DIURNAL 
CURVE WITH THE COLD FRONT COMING IN FROM THE WEST.  USED A MODEL 
BLEND BETWEEN THE MAV AND THE MET TO DETERMINE TEMPERATURES.  POPS 
ARE STILL IFFY IN THE EASTERN TERRITORY AS THE DYNAMICS STAY NORTH 
OF THE REGION SO WE WILL KEEP POPS HIGHEST IN THE WEST.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
MODELS ARE IN GOOD AGREEMENT WITH A SLOW MOVING COLD
FRONT...BECOMING STATIONARY ACROSS THE AREA SATURDAY NIGHT INTO
SUNDAY. BUFKIT SOUNDINGS INDICATE MOST OF THE PCPN WILL FALL AS
LIQUID LOWLANDS AT LEAST THROUGH SUNDAY. 

AN MID TO UPPER LEVEL TROUGH WILL BRING MUCH COLDER AIR BEHIND THE
FRONT SUNDAY NIGHT THROUGH MID NEXT WEEK. THIS COLD AIR WILL
PRODUCE A PCPN TRANSITION FROM RAIN...MIXED INTO SNOW BY SUNDAY
MORNING OVER THE NORTHEAST HIGHER ELEVATIONS. WITH THE WARM
GROUNDS...AND A RELATIVELY WARM BOUNDARY LAYER...MOST AREAS WILL
BE UNDER RAIN. 

MEANWHILE...WHAT IS CURRENTLY HURRICANE SANDY...IS EXPECTED TO
MOVE INLAND AS AN EXTRA TROPICAL CYCLONE...BETWEEN DELAWARE AND
NEW JERSEY...MOVING WEST INTO PA AND NORTHERN WV. ABUNDANT
TROPICAL MOISTURE WILL INTERACT WITH THE AFOREMENTIONED UPPER
LEVEL TROUGH TO PRODUCE A LONG DURATION PRECIPITATION EVENT ACROSS
THE AREA FROM MONDAY THROUGH THURSDAY. 

BY 18Z MONDAY...LATEST NAM/SREF/ECMWF MODELS SHOW THE MINUS ONE
TO THREE DEGREES CELSIUS AT H850 FILTERING FROM THE WEST. THE GFS
BRINGS MINUS FOUR DEGREES...SUGGESTING PCPN TO TRANSITION TO ALL
SNOW ACROSS THE AREA BY MONDAY EVENING. MUCH COLDER AIR MOVES IF
FROM THE WEST PER ALL MODELS UNDER STRONG H850 NORTHWEST FLOW
AROUND 40-50 KNOTS. SEEMS LIKE THE INTERACTION OF SANDY REMNANTS
AND THE UPPER LEVEL TROUGH WILL INTENSIFY INTO A VERY STRONG EXTRA
TROPICAL CYCLONE ACROSS THE SOUTHEAST U.S....TO CONTINUE UPSLOPE
SNOW UNDER STRONG NORTHWEST FLOW ACROSS THE EASTERN
MOUNTAINS...COLD AND MOISTURE ADVECTION.

THESE INGREDIENTS CALL FOR SIGNIFICANT SNOWFALL ACCUMULATIONS
ALONG THE NORTHEAST MOUNTAINS THROUGH WEDNESDAY. THEREFORE...ISSUE
A WINTER WEATHER WATCH FOR POCAHONTAS...RANDOLPH AND WEBSTER
THROUGH 00Z WEDNESDAY. 

PREVIOUS TEMPERATURES LOOK GOOD AND COMPARABLE TO LATEST GUIDANCE.
STRONG GUSTY WINDS UP TO 45 KNOTS OR GREATER ARE LIKELY MAINLY
OVER THE HIGHER TERRAIN THROUGH MID WEEK.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
PRIMARY FORECAST CONCERN FOR THIS PERIOD OBVIOUSLY CONTINUES TO 
REVOLVE AROUND SANDY/S TRACK AND POTENTIAL IMPACTS FOR THE NORTHEAST 
CONUS IN GENERAL...AND SPECIFICALLY POTENTIAL IMPACTS FOR OUR 
FORECAST AREA. WITH REGARD TO WHERE SANDY/S LANDFALL...NHC/S TRACK 
HAS SHIFTED SOUTHWARD AND NOW BRINGS THE CENTER ASHORE OVER THE 
DELMARVA PENINSULA. WITH THE STORM STILL BEING FOUR DAYS AWAY 
SIGNIFICANT DIFFERENCES OBVIOUSLY STILL EXIST WITH HOW EXT GUIDANCE 
HANDLES SANDY/S TRACK. TO SOME EXTENT EVEN GREATER UNCERTAINTY 
EXISTS WITH HOW SANDY/S POST-TROPICAL EVOLUTION TAKES PLACE WITH 
STRONG COLD AIR INTRUSION OUT OF THE NORTHWEST...AND THIS WILL HAVE 
MAJOR RAMIFICATIONS AS TO THE SNOW/ICE IMPACTS OUR FORECAST AREA 
EXPERIENCES AND TO A LESSER EXTENT WIND SPEEDS.

BREAKING DOWN THE SIG DIFFERENCES BETWEEN THE EXT MODELS AND 
STARTING WITH THE 00Z EC...SANDY/S CENTER COMES ASHORE OVER DELMARVA 
AREA MONDAY AFTERNOON AND SLOWLY MOVES TOWARDS THE EASTERN PANHANDLE 
WV AREA BY 12Z TUE. THE SFC CENTER FILLS RAPIDLY BY TUESDAY MORNING 
AS WELL WITH A SFC PRESS OF 982MB BY SAME TIME WITH WARM ADVECTION 
WRAPPING AROUND THE BACKSIDE. THIS SCENARIO WOULD LIKELY MEAN MUCH 
HIGHER PRECIP AMOUNTS FOR THE OVERALL AREA BUT WOULD ALSO MEAN A 
LESSER LIKELIHOOD OF ACCUM SNOWFALL FOR LOWER ELEVATIONS AS THE 
540DAM THICKNESS HEIGHT LINE REMAINS GENERALLY ALONG AND WEST OF OUR 
FORECAST AREA. HIGH RAINFALL AMOUNTS BECOME THE BIGGER ISSUE WITH 
THIS SCENARIO FOR LOWLANDS WITH A GENERAL 2-4 INCHES OF QPF DEPICTED 
WITH HIGHER AMOUNTS CERTAINLY POSSIBLE.     
   
MEANWHILE THE 12Z GFS CONTINUES TO BRING SANDY/S CENTER ASHORE NEAR 
NYC TUES AFTERNOON WITH A SW RETROGRADE NEAR PHILLY BY TUE 
EVE...BEFORE KICKING IT OUT TO THE N/NW WEDNESDAY. THIS SCENARIO 
BRINGS A LONGER WIND EVENT CONTINUING WELL INTO TUE WITH THE SFC LOW 
FARTHER AWAY. THIS SCENARIO ALSO ALLOWS COLDER AIR INTO THE 
AREA...WITH THE 540DAM LINE COMPLETELY ENCOMPASSING AND WELL SOUTH 
OF THE FORECAST AREA. THIS SCENARIO WOULD SPELL SNOWFALL FOR LOWLAND 
LOCATIONS AS WELL. EVEN SO...WITH WARM SFC TEMPS FROM A WEEK OF VERY 
WARM WEATHER IT WOULD PROBABLY TAKE SOME TIME BEFORE SNOW BEGINS TO 
ACCUM ON ROADWAYS.

WITH ALL THIS IN MIND...WILL SIDE THE FORECAST TOWARDS THE EC WHICH 
IS MUCH CLOSER TO NHC/S CURRENT TRACK AND THUS WILL LEAN THE 
EVOLUTION OF THE SYSTEM IN THIS DIRECTION AS WELL. EITHER 
WAY...THOUGH THE BEGINNING OF THE EVENT IS STILL 2-3 DAYS OUT 
CONFIDENCE IS GROWING WITH A SIGNIFICANT SNOWFALL EVENT FOR THE HIGH 
COUNTRY...PARTICULARLY FOR THE HIGHEST LOCATIONS SUCH AS SNOWSHOE. 
IN COORDINATION WITH THE SHORT TERM FORECASTER...WILL KEEP WINTER 
STORM WATCH FOR THESE AREAS GOING THROUGH 00Z WED WITH THE LONG 
DURATION POTENTIAL. ACROSS THE LOWLANDS AMOUNTS GENERALLY UNDER TWO 
INCHES ARE EXPECTED FOR WV ZONES...WITH MUCH OF IT COMING DURING THE 
OVERNIGHT HOURS WITH PRIMARILY RAIN DURING THE DAY. LITTLE SNOW 
SHOULD ACCUMULATE ON ROAD SURFACES WITH SUCH VERY WARM TEMPS IN 
PLACE THIS WEEK. HAVE ALSO LOWERED MAX TEMPS TUESDAY AND WEDNESDAY. 
AGAIN...STILL A GOOD DEAL OF UNCERTAINTY WITH THE FINAL TRACK AND 
ANY SHIFT NORTH OR SOUTH COULD MAKE SUBSTANTIAL DIFFERENCES IN 
RAIN/SNOW AMOUNTS RECEIVED AND WHERE...SNOW ACCUMULATIONS...ALONG 
WITH WINDS.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
MVFR CLOUDS TO ADVECT SLOWLY INTO AREA WITH CONVECTIVE SHOWERS OFF
TO THE WEST. ALREADY SEEING ALTOCUMULUS EAST OF CRW AT THIS
POINT...BUT NO RESTRICTIONS IN THE CEILINGS JUST YET. BULK OF THE
FORECAST TO HAVE LOW END MVFR CEILINGS AT 1-2KFT LATE TONIGHT AND
SATURDAY WITH SHOWERS PREVAILING FOR MUCH OF THE DAY. PAIR UP MVFR
VISIBILITIES WITH THE HIGHER POPS IN THE FORECAST...AND SOME IFR
IS POSSIBLE IN ABUNDANT LOW LEVEL MOISTURE AFTER NEWLY FALLEN
RAIN. 

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY...
     
FORECAST CONFIDENCE: HIGH.

ALTERNATE SCENARIOS: IFR MATERIALIZATION IN QUESTION 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.

DATE                                                  SAT 10/27/12
UTC 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
EDT 1HRLY       22   23   00   01   02   03   04   05   06   07   08   09
CRW CONSISTENCY  H    H    H    H    H    H    M    M    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    H    L    L    L    L    L    L    L
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    L    L    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 00Z SUNDAY...
IFR POSSIBLE IN RAIN WITH REMNANTS OF SANDY EARLY NEXT WEEK. THIS
INCLUDES SNOW SHOWERS ACROSS THE HIGHER TERRAIN.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH TUESDAY 
     EVENING FOR WVZ038-046-047.
OH...NONE.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...ARJ/RPY/50/LS
NEAR TERM...RPY/26/LS
SHORT TERM...ARJ
LONG TERM...50
AVIATION...26