Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 250546
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1246 AM EST TUE NOV 25 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE EAST ACROSS THE REGION TONIGHT. NORTHWEST
FLOW BEHIND THE FRONT WILL BRING COLDER TEMPERATURES TUESDAY INTO
WEDNESDAY. A STORM SYSTEM MOVING UP ALONG THE CAROLINA COAST WILL
BRING THE NEXT ROUND OF PRECIPITATION FOR THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 930 PM EST MONDAY...

SFC COLD FRONT IS ALONG THE SPINE OF THE APPALACHIANS AND IS
SLOWLY INCHING ITS WAY EAST. COOLER/DRIER AIR LAGS WELL BEHIND
FRONT...THUS AREAS ALONG AND EAST OF BLUE RIDGE LIKELY TO REMAIN
MILD OVERNIGHT. BUMPED UP LOW TEMPS OVERNIGHT ACROSS SOUTHSIDE VA
AND THE PIEDMONT OF NC TO ACCOUNT FOR THIS LAG. WARM/MOIST AIR
ADVECTION AHEAD OF THE SFC FRONT IS ALSO RESULTING IN RISING
DEWPOINTS ACROSS THE PIEDMONT...DANVILLES DEWPOINT CLIMBING FROM
53 TO 60 SINCE SUNSET. THESE DEWPOINTS WILL LIKELY REMAIN ELEVATED
UNTIL FROPA LATE TONIGHT...THUS FAVORING WARMER T-MINS.

LATEST SAT PIX INDICATES THICKENING CLOUDS OVER THE
CAROLINAS...THIS UPPER LEVEL MOISTURE ASSOCIATED WITH THE UPPER
JET. MODEL RH FIELDS AT 250 MB SUGGEST ALL AREAS EAST OF THE BLUE
RIDGE WILL DEVELOP LAYER OF HIGH LEVEL CIRRUS...WHICH WILL BECOME
BKN-OVC DURING THE OVERNIGHT. INCREASED CLOUD COVER TO ACCOUNT FOR
THIS DEVELOPING CIRRUS SHIELD. LIGHT RAIN IS CURRENTLY FALLING
FROM RALEIGH NC SOUTHWARD INTO SOUTH CAROLINA...PRIMARILY ALONG
I95 CORRIDOR. MODELS KEEP THIS PRECIP CONFINED TO AREAS JUST
SOUTHEAST OF OUR CWA IN THE NEAR TERM.

SURFACE COLD FRONT IS FORECAST TO MOVE EAST TO ALONG THE COAST ON
TUESDAY...COOLER/DRIER AIR TRICKLING INTO THE FORECAST AREA VIA A
LIGHT NORTHWEST WIND. HIGH PRESSURE WILL BUILD EAST OUT OF THE
OHIO VALLEY DURING THE DAY TUESDAY...ENSURING A DRY DAY. ANY SUN
HOWEVER WILL BE FILTERING THROUGH HIGH CLOUDS FOR MOST OF THE
AREA...JET STREAM CIRRUS REMAINING OVERHEAD. HIGH TEMPERATURES
WILL RANGE FROM THE 40S IN THE WESTERN MOUNTAINS TO AROUND 60
ACROSS THE SOUTHEAST.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS OF 335 PM EST MONDAY...

TWO STRONG SHORT WAVES COME THROUGH THE LONG WAVE TROF OVER THE
EASTERN UNITED STATES THIS TIME FRAME. THE FIRST CROSSES THE
FORECAST AREA FROM THE SOUTHERN STREAM ON WEDNESDAY AND THE NEXT
FROM THE NORTHERN STREAM ON WEDNESDAY NIGHT.

IN ADDITION TO THE POSITIVE VORTICITY ADVECTION ON WEDNESDAY THERE
WILL ALSO BE GOOD Q-VECTOR FORCING AND UPPER DIFFLUENCE. WILL BE
INCREASING PROBABILITY OF PRECIPITATION FOR LATE TUESDAY NIGHT INTO
WEDNESDAY NIGHT ACROSS THE SOUTHERN COUNTY WARNING AREA.

MODELS HAVE COME INTO BETTER AGREEMENT AND HAVE TRENDED WEST WITH
TRACK OF THE 850MB AND SURFACE LOWS. 12Z NAM IS COLDER WITH THE
TEMPERATURE PROFILE ON TUESDAY NIGHT AND WEDNESDAY THAN 12Z GFS. AT
THIS TIME WILL BE TAKING A BLEND. LOWEST LAYERS DROP BELOW FREEZING
IN THE WEST LATE TUESDAY NIGHT WITH BUFKIT WAS SHOWING PERIODS OF
ISOTHERMAL TEMPERATURES. PRECIPITATION TYPE WILL ALSO BE DEPENDENT
ON INTENSITY AND RATES. TEMPERATURES WEDNESDAY WILL BE NEARLY STEADY
AND 10 TO 15 DEGREES BELOW NORMAL. SOME OF COOLING IS EXPECTED AS
THE TEMPERATURE DROPS TOWARD WET BULB VALUES...BUT EVEN SO...ONLY
HIGHER ELEVATIONS OF THE BLUE RIDGE AND AREAS WEST WILL HAVE SURFACE
TEMPERATURES COLD ENOUGH FOR SNOW ACCUMULATION.

COMBINING THE PRECIPITATION AMOUNTS AND SNOWFALL FROM THE TUESDAY
NIGHT AND WEDNESDAY SYSTEM WITH THE SNOWFALL FROM THE CLIPPER ON
WEDNESDAY NIGHT MAY PUSH SNOWFALL TOTALS IN SOME LOCATIONS ABOVE
WARNING CRITERIA. CHALLENGING TO SAY AT THIS POINT HOW WIDESPREAD
THIS WILL BE AND HOW MUCH OF A GAP THERE WILL BE FROM THE TIME THE
COASTAL LOW PRECIPITATION EXITS TO THE TIME THE SNOW WITH THE
CLIPPER COMES THROUGH.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 130 PM EST MONDAY...

HIGH PRESSURE WILL KEEP THE REGION DRY ON FRIDAY AND THROUGH THE
START OF THE UPCOMING WEEKEND. BY SUNDAY...AND TO A SLIGHTLY BETTER
DEGREE ON MONDAY...THE CENTER OF THE HIGH WILL SHIFT TO THE
COAST...AND A COLD FRONT WILL BECOME STALLED OVER THE OHIO VALLEY.
THIS WILL SET THE REGION UP FOR A SOUTHWEST FLOW...WARM AIR
ADVECTION PATTERN. LIFT WITHIN THE VICINITY OF THE STALLED FRONT
WILL ALLOW FOR LIGHT PRECIPITATION TO SLOWLY INCREASE IN COVERAGE
FROM NORTHWEST TO SOUTHEAST AS WE HEAD FROM SUNDAY INTO MONDAY.
THERE MAY BE A PRECIPITATION TYPE ISSUE THESE TWO DAYS WHERE SURFACE
TEMPERATURES ARE BELOW OR HOVER AROUND THE FREEZING MARK DURING THE
LATE OVERNIGHT AND EARLY MORNING HOURS AND A STRONG WARM NOSE EXISTS
ALOFT. AT THIS TIME...WILL HAVE A RAIN VERSUS FREEZING RAIN
FORECAST...WITH VERY LITTLE IN THE WAY OF FREEZING RAIN COVERAGE AND
ALSO IN TIME DURATION.

TEMPERATURES THROUGH THIS PERIOD WILL TREND MILDER EACH DAY SO THAT
BY MONDAY UPPER 50S TO LOWER 60S WILL BE COMMON ACROSS THE REGION
FOR HIGH TEMPERATURES. THIS CONTRASTS TO HIGHS IN THE MID 30S TO
NEAR 40 ACROSS THE MOUNTAINS AND LOW TO MID 40S ACROSS THE PIEDMONT
ON FRIDAY.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1235 AM EST TUESDAY...

SURFACE COLD FRONT IS CURRENTLY MOVING ACROSS THE MOUNTAINS...BUT
FORWARD SPEED HAS BEEN SLOWING WITH TIME PER WIND FLOW ALOFT
BECOMING PARALLEL WITH FRONT. THIS FRONT IS EXPECTED TO MOVE EAST
OF THE MOUNTAINS DURING THE OVERNIGHT...THEN TO ALONG THE COAST
TUESDAY AFTERNOON. WINDS BEHIND THE FRONT WILL SHIFT TO THE WEST
INITIALLY...THEN TREND MORE NORTHERLY WITH TIME DURING THE DAY
TUESDAY AS HIGH PRESSURE BUILDS INTO THE FORECAST AREA FROM THE
NORTHWEST. CLOUD BASES THROUGH THE 24 HR TAF PERIOD ARE EXPECTED
BE VFR EXCEPT ACROSS THE FAR SOUTHEAST AROUND KDAN WHERE A PERIOD
OF MVFR IN LOWER STRATO-CU COULD OCCUR THROUGH DAYBREAK TUESDAY.

MEDIUM TO HIGH FCST CONFIDENCE DURING THE TAF PERIOD.


EXTENDED DISCUSSION...

A DEVELOPING STORM SYSTEM IS EXPECTED TO MOVE UP THE SOUTHEAST
COAST BY EARLY WEDNESDAY WHICH MAY BRING WINTRY PRECIP TO THE AREA
ALONG WITH SUB VFR AT ALL SITES. LOOKS LIKE FLIGHTS WILL BE
IMPACTED GREATLY ACROSS THE MID ATLANTIC INTO THE NORTHEAST WITH
THIS SYSTEM WITH WITH WIDESPREAD PRECIPITATION. FOR THE CENTRAL
APPALACHIANS BEST CHC FOR SUB VFR WILL OCCUR WED INTO EARLY
THANKSGIVING BEFORE HIGH PRESSURE WORKS IN FROM THE WEST. WESTERN
SLOPES...VCNTY OF BLF/LWB...MAY KEEP LOWER CIGS UNTIL FRIDAY
AFTERNOON.

&&

.CLIMATE...
NO RECORD HIGH TEMPERATURES OCCURRED YESTERDAY...HOWEVER DANVILLE
SET A NEW RECORD HIGH MINIMUM TEMPERATURE OF 57 DEGREES FOR THE
24TH. THIS BREAKS THE OLD RECORD HIGH MINIMUM FOR DANVILLE OF 56
DEGREES FROM 2004.

&&

.EQUIPMENT...
AS OF 330 AM EST MONDAY...

THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT
OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN
THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS
STAFFED.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...JH/KK
NEAR TERM...KK/PM
SHORT TERM...AMS
LONG TERM...DS
AVIATION...JH/KK/WP
CLIMATE...JH
EQUIPMENT...JH


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