Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 280426
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1126 PM EST SAT DEC 27 2014

.SYNOPSIS...
A COLD FRONT CROSSES LATE TONIGHT INTO SUNDAY. A WAVE OF LOW
PRESSURE MOVES ALONG THE FRONT SUNDAY. DRIER...COLDER AIR SLOWLY
BUILDS IN EARLY NEXT WEEK TO CLOSE OUT 2014.

&&

.NEAR TERM /THROUGH SUNDAY/...
RADAR IMAGES SHOW AN AREA OF RAIN SHOWERS ACROSS EASTERN TN AND KY
MOVING NORTH NORTHEAST. THESE SHOWERS WILL LIKELY AFFECT EXTREME
SOUTHWEST VA AND THE CENTRAL MOUNTAINS OF WV. THEREFORE...INCREASED
POPS TO LIKELY OVERNIGHT THERE. REST OF FORECAST REMAINS
REPRESENTATIVE.

PREVIOUS DISCUSSION BELOW...
630 PM UPDATE...TWEAKED POP AND SKY GRIDS...BASED ON CURRENT
RADAR/SATELLITE TRENDS. THUS...SLOWED DOWN PROGRESSION BY JUST A
COUPLE OF HOURS. IN ADDITION WITH THE DRY ATMOSPHERE IN
PLACE...MAY TAKE A LITTLE WHILE AFTER SEEING RADAR RETURNS FOR
PRECIPITATION TO ACTUALLY MAKE IT TO THE GROUND. OTHERWISE...NO
CHANGES WERE NECESSARY.

PREVIOUS DISCUSSION FOLLOWS...
MOST OF WEST VIRGINIA IS BASKING IN THE SUN AT THE MOMENT...BUT
THAT SHOULD CHANGE AS A COLD FRONT MOVES THROUGH TONIGHT AND TURNS
INTO A STATIONARY FRONT USHERING WAVES OF MOISTURE INTO THE STATE.
LUCKILY...MOST MODEL SIGNALS INDICATE THAT TOTAL PRECIPITATION
BETWEEN NOW AND SUNDAY SHOULD REMAIN LESS THAN AN INCH.

WITH INCREASED MODEL CONFIDENCE BOOSTED THE POPS OVER MUCH OF THE
FORECAST AREA. ALSO NOTCHED UP THE WINDS IN SE OH PER HRRR
GUIDANCE FOR THIS AFTERNOON.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
THE MIDDLE OHIO VALLEY DRIES OUT SUN NT...AS A POSITIVE TILT UPPER
LEVEL S/W TROUGH...ORIGINATING FROM THE EXTREME SWRN CONUS THIS
MORNING...MOVES ON THROUGH.  HUNG ON TO A HIGH CHANCE FOR RAIN IN
THE CENTRAL APPALACHIANS ON MON...ALTHOUGH MOST OF IT SHOULD BE
LIGHT RAIN OR EVEN DRIZZLE...AS MOISTURE DEPTH BECOMES SHALLOW
BENEATH FLAT W TO SW UPPER LEVEL FLOW.  A FLAT WAVE ALSO BRUSHES BY
JUST TO THE SE.

MON NT DOES NOT BRING MUCH CHANGE IN THE POSITION OF THE FRONT...OR
ITS ASSOCIATED PRECIPITATION...AS THE UPPER LEVEL FLOW BACKS AHEAD
OF ANOTHER UPPER LEVEL S/W TROUGH THAT CROSSES ON TUE...AND A LOW
LEVEL CONVERGENCE AXIS HANGS OVER THE MOUNTAINS MON NT INTO TUE
MORNING.  THE UPPER LEVEL S/W IS THE FIRST FEATURE COMING OF A NEW
LARGE S/W TROUGH DROPPING DOWN THROUGH THE WRN CONUS AGAIN...AND
BRINGS IN COLDER...DRIER AIR AS IT PHASES WITH A NRN STREAM TROUGH.
DESPITE THE DRIER AIR...THE UPPER DYNAMICS COULD BRING A BIT OF AN
UPTICK IN PRECIPITATION TUE EVEN BACK INTO THE MIDDLE OHIO
VALLEY...AS THE COLDER AIR BECOMES MORE SUPPORTIVE OF ICE CRYSTAL
GROWTH IN LOWER LAYERS.

THERE MAY BE SNOW SHOWERS ON THE WRN AND NRN EDGES OF THE
PRECIPITATION OVER THE MIDDLE OHIO VALLEY AND NRN WV MON MORNING.
MON NT INTO TUE MORNING IS THE ONLY PERIOD WHERE SFC TEMPERATURES
GET BELOW FREEZING BEFORE WE COMPLETELY LOSE THE WARM LAYER ALOFT.
THIS OCCURS IN A NARROW SW TO NE ORIENTED SLIVER THROUGH CENTRAL
WV...AND IN THE MOUNTAINS...WHERE A BIT OF SLEET IS POSSIBLE.
MODELS RANGE FROM A QUARTER TO A HALF AN INCH ADDITIONAL LIQUID
EQUIVALENT PRECIPITATION SUN NT THROUGH TUE.

BLENDED IN NAM...MET AND GFS-BASED MOS FOR HOURLY TEMPERATURES AND
DEW POINTS...SLIGHTLY LOWER THAN PREVIOUS FCST BY TUE BUT OVERALL
THE MODELS APPEAR CONSISTENT WITH MOVING THE BAROCLINIC ZONE THROUGH
THE AREA THIS PERIOD.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
850MB TEMP TROUGH ENTERING AT THE BEGINNING OF THE LONG TERM. HAVE A
SLIGHT CHANCE OF POPS FOR THE NORTHERN MOUNTAINOUS COUNTIES WITH
THIS. ALTHOUGH MOISTURE DOES LOOK RATHER LIMITED...SO COULD BE
NOTHING MORE THAN SOME FLAKES DRIFTING THROUGH THE AIR AS THE COLDER
AIR MOVES IN. THEN HIGH PRESSURE DOMINATES FOR A BULK OF THE LONG
TERM BEFORE A SURFACE LOW DEVELOPS IN THE SOUTHERN PLAINS/LOWER
MISSISSIPPI VALLEY. THE ECMWF CONTINUES TO HAVE A POOR CONSISTENCY
RECORD THIS SEASON...SO STUCK CLOSER TO THE GFS FOR PLACEMENT AND
TIMING OF POPS.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS THROUGH AT LEAST 06Z...WHEN -RA WILL MOVE INTO THE
AREA...AFFECTING SOUTHEAST OHIO AND SOUTHWEST VA/SOUTHERN WV
INITIALLY. CIGS WILL DROP FROM VFR...TO MVFR...AND FINALLY BE IN
THE IFR/LIFR CATEGORY FOR MUCH OF THE TAF PERIOD ON SUNDAY...GENERALLY
BEYOND 12Z.

SOME GENERAL IMPROVEMENT TO IFR/MVFR AFTER 21Z...PARTICULARLY
ACROSS THE NORTH...BUT MOUNTAINS WILL LIKELY CONTINUE TO LINGER IN
IFR OR WORSE CONDITIONS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...

FORECAST CONFIDENCE: LOW.

ALTERNATE SCENARIOS: TIMING AND DEVELOPMENT OF IFR CIGS MAY VARY
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 12/28/14
UTC 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
EST 1HRLY       21   22   23   00   01   02   03   04   05   06   07   08
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M
HTS CONSISTENCY  H    H    H    M    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    H
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    M    L    L
PKB CONSISTENCY  H    H    M    M    M    M    H    H    H    H    M    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M

AFTER 06Z MONDAY...
IFR POSSIBLE IN RAIN AND LOW CIGS INTO MONDAY.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...TRM/MZ/JW
NEAR TERM...ARJ/SL/JW
SHORT TERM...TRM
LONG TERM...MZ
AVIATION...SL







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