Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 180453
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1153 PM EST WED DEC 17 2014

.SYNOPSIS...
HIGH PRESSURE OVER THE UPPER MIDWEST WILL GRADUALLY BUILD EAST
ACROSS THE AREA RESULTING IN OVERALL DRY WEATHER THROUGH FRIDAY.
PERIODS OF MID/UPPER LEVEL CLOUDINESS WILL SKIRT THE FORECAST
AREA PER MOISTURE FESTERING OVER TEXAS. AN AREA OF LOW PRESSURE
WILL EVENTUALLY DEVELOP OVER TEXAS BY FRIDAY...MOVING NORTHEAST
AND PROVIDING THE MID ATLANTIC REGION A WINTRY MIX OF
PRECIPITATION FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1000 PM EST WEDNESDAY...

FORECAST ON TRACK THIS EVENING...DEALING WITH HIGH CLOUDS SPILLING
EAST OF THE BLUE RIDGE...AND LOWER CLOUDS OVER WRN SLOPES OF SE
WV/FAR SW VA AND PORTIONS OF THE NC MTNS. MOISTURE IS SCANT PER
00Z RNK SOUNDING...AND PER EARLIER FORECAST MAY ONLY SEE PATCHY
FZDZ AT TIMES THRU EARLY OVERNIGHT IN THE WRN MTNS OF GREENBRIER
COUNTY. NOTHING OF CONSEQUENCE...AND SHOULD CONTINUE TO SEE OFF
AND ON CIRRUS OVERNIGHT IN THE SRN HALF OF THE CWA...WITH SKIES
STAYING MAINLY CLEAR TO PC...AS MOST OF THE CIRRUS HAS BEEN THIN.

LOWS WILL RANGE FROM THE MID 20S FAR WEST...TO LOWER 30S
SOUTHEAST. WIND STAYING UP WILL PREVENT TEMPS FROM DROPPING
FURTHER.

PREVIOUS VALID DISCUSSION...



BY THURSDAY...AREA OF MOISTURE ASSOCIATED WITH THE DISTURBANCE
OVER TX/OK WILL GET CAUGHT UP IN THE FAST WESTERLY FLOW
ALOFT...QUICKLY ZIPPING ACROSS THE OH/TN VALLEYS AND REACHING OUR
FORECAST AREA DURING THE AFTERNOON/EVENING. THE CONFLUENT FLOW
ALOFT HOWEVER...WILL SQUASH ANY CHANCE FOR ANY MEASURABLE
PRECIP...ALTHOUGH CERTAINLY CAN`T RULE OUT SOME SPRINKLES OR
FLURRIES...A TRACE EVENT. WITH MORE CLOUDS...TEMPERATURES WILL NOT
GET NEARLY AS WARM AS THEY DID WEDNESDAY...TOPPING OUT IN THE 40S
AS OPPOSED TO THE 50S...A CHANGE OF 10 DEGREES.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 400 PM EST WEDNESDAY...

WEAK SHORT WAVE WILL MOVE QUICKLY OFF EAST COAST.
MUCH OF THE CLOUD COVER WILL CLEAR FOR THURSDAY NIGHT AND FRIDAY.
EARLY FRIDAY NIGHT HIGH CLOUDS AHEAD OF THE NEXT SYSTEM WILL FILL
IN FROM THE SOUTHWEST. MAV GUIDANCE USED FOR MAXIMUM AND MINIMUM
TEMPERATURES THIS TIME FRAME.

WATER VAPOR LOOP SHOWED A COMPACT BUT WELL DEFINED SHORT WAVE OVER
SOUTHERN CALIFORNIA. MODELS TRACK THIS FEATURE ACROSS THE SOUTHERN
PLAINS THEN INTO THE MID ATLANTIC REGION. SPEED AND TIMING OF THIS
SYSTEM ON THE GFS AND ECMWF WERE STILL REASONABLE. THIS BRING THE
BEST POSITIVE VORTICITY ADVECTION OVER THE FORECAST AREA ON SATURDAY
AFTERNOON AND EVENING...SLIGHTLY SLOWER THAN ON PREVIOUS RUNS. BEST
ISENTROPIC LIFT REMAINS JUST SOUTH OF THE FORECAST AREA...AND IS
MAINLY ON SATURDAY.

FRIDAY NIGHT AND SATURDAY THE SURFACE HIGH MOVES FROM THE GREAT
LAKES TO NEW ENGLAND. ON SATURDAY THE SURFACE LOW WILL TRANSITION
FROM THE FLORIDA PANHANDLE TO OFF THE SOUTH CAROLINA COAST. THIS
WILL BRING WINDS AROUND TO THE EAST THEN NORTHEAST. PRECIPITATION ON
SATURDAY WILL HELP ENHANCE AND MAINTAIN AN IN-SITU WEDGE. BUFKIT
SOUNDINGS SUPPORT MIXED PRECIPITATION WITH DENDRITIC GROWTH THROUGH
21Z/4PM SATURDAY THEN MAINLY RAIN OR FREEZING RAIN AFTER THAT. ONLY
SITE THAT WAS CLEARLY COLD ENOUGH FOR SNOW FOR FROM THE ONSET
THROUGH THE DAY SATURDAY WAS NEAR HOT SPRINGS. NAM WAS WARMER WITH
THE WARM LAYER ALOFT. LEANING TOWARD COOLER GFS FOR THE EXPECTED
TEMPERATURE PROFILE. SURFACE TEMPERATURES ON SATURDAY AND SATURDAY
NIGHT WILL HAVE A NON-DIURNAL PROFILE.&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 250 PM EST WEDNESDAY...

THIS PORTION OF THE FORECAST HAS THE POTENTIAL TO BE AN ACTIVE
WEATHER PATTERN BASED UPON THE VARIOUS MODELS. HOWEVER...THESE SAME
MODELS OFFER ENOUGH DIFFERENCES TO MAKE THE DETAILS OF THE SENSIBLE
WEATHER ENOUGH OF CHALLENGE THAT CONFIDENCE IN THE SPECIFICS IS NOT
HIGH.

ON SUNDAY...THE CENTER OF SATURDAY/SATURDAY NIGHT SYSTEM WILL TO OUR
EAST ALONG A BAROCLINIC ZONE THAT WILL BE ALONG THE EAST COAST FROM
NORTH CAROLINA TO FLORIDA. WHAT REMAINS AS A QUESTION MARK IS
WHETHER OR NOT ANOTHER WAVE ALONG THIS SAME BAROCLINIC ZONE WILL
PROGRESS FROM GEORGIA NORTHEAST ALONG THE COAST AND DRAW MOISTURE
BACK INTO AT LEAST THE EASTERN PORTIONS OF THE REGION. THEN...BY
MONDAY...THIS SAME LOW MAY OR MAY NOT STRENGTHEN AND DEEPEN AS
ANOTHER CLOSED COASTAL LOW OFF THE COAST OF NORTH CAROLINA.
DEPENDING UPON HOW MUCH OR LITTLE THIS SYSTEM DEEPENS WILL CORRELATE
TO HOW LONG ANY ASSOCIATED PRECIPITATION REMAINS OVER OUR REGION.
THE PRECIPITATION TYPE ACROSS THE AREA IS ALSO A QUESTION. EACH
MODEL HAS A DIFFERENT TAKE ON THE MAGNITUDE OF THE WARM NOSE OVER
OUR REGION. THE ONLY CONSISTENT ELEMENT IS THE EXISTENCE OF A WARM
NOSE. GIVEN THIS...WILL OFFER RAIN VERSUS FREEZING RAIN FORECAST
DURING THE LATE SUNDAY NIGHT THROUGH MONDAY PORTION OF THE FORECAST.
PRECIPITATION CHANCES THOUGH WILL BE ON THE LOW SIDE...MAINLY
RANGING IN THE SLIGHT CHANCE CATEGORY.

BY MONDAY NIGHT...GUIDANCE IS IN FAIRLY GOOD AGREEMENT OF BRINGING A
CANADIAN LOW PRESSURE SYSTEM INTO THE NORTHERN MISSISSIPPI VALLEY.
FROM THAT POINT...A DEEP LONGITUDINAL TROUGH DEVELOPS SOUTH TO THE
GULF OF MEXICO BY TUESDAY AFTERNOON WITH INCREASING SOUTHERLY LOW
LEVEL FLOW ACROSS OUR REGION...ACCOMPANIED BY AN INCREASING MOISTURE
FETCH. BY TUESDAY NIGHT INTO EARLY WEDNESDAY...BOTH THE GFS AND
ECWMF CONTINUE TO DEEPEN THE UPPER LOW AND ASSOCIATED TROUGH AND
NEGATIVELY TILT THE FEATURE SO THAT THE TROUGH AXIS SHIFTS TO OFF
THE COAST OF THE CAROLINAS...COINCIDENT TO THE POSITION OF THE
ASSOCIATED SURFACE OCCLUDED FRONT....WITH THE TRIPLE POINT PASSING
SOMEWHERE NEAR OR JUST SOUTH OF OUR REGION. THIS PAINTS A PICTURE OF
VERY ACTIVE WEATHER ACROSS OUR REGION LATE TUESDAY NIGHT INTO
WEDNESDAY WITH PLENTY OF SHOWERS...VERY GUSTY...IF NOT DAMAGING...
WINDS...AND IF THE TRIPLE POINT PROGNOSTIC IS ACCURATE...SEVERE
WEATHER...OR AT LEAST A RUMBLE OR TWO OF THUNDER...OVER OR VERY
CLOSE TO OUR REGION OF THE COUNTRY. HOWEVER...THIS SCENARIO STILL IS
DAY 6 INTO DAY 7 OF THE FORECAST...AND THERE IS PLENTY OF TIME FOR
CHANGES IN THE OPERATIONAL MODELS TO TREND TOWARD A LESS AGGRESSIVE
SYSTEM. GIVEN THIS...WILL OFFER A FORECAST LATE MONDAY NIGHT INTO
TUESDAY THAT OFFERS INCREASING CHANCES OF LIGHT RAIN OR FREEZING RAIN
     WITH LIGHT TO MODERATE RAIN ON TUESDAY...WITH MODERATE RAIN
SHOWERS TUESDAY NIGHT INTO EARLY WEDNESDAY ALONG WITH GUSTY WINDS.
TIMING OF THE PUSH OF COLDER AIR INTO THE REGION AS WELL AS THE
MAGNITUDE OF THAT COLDER AIR VARIES BETWEEN THE GFS AND ECWMF.
HOWEVER...THE FORECAST WILL ALLOW FOR THE POTENTIAL FOR COLD ENOUGH
AIR TO REACH WESTERN...HIGHER PARTS OF THE AREA LATE TUESDAY NIGHT
INTO WEDNESDAY FOR ACCUMULATING SNOW SHOWERS.

TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL TREND MILDER
THROUGH AT LEAST TUESDAY. WEDNESDAY MAY BE A BIT MILDER IN THE
EAST...AND SLIGHTLY COOLER IN THE WEST AS COMPARED TO TUESDAY. ALL
DAYS OF THIS PORTION OF THE FORECAST ARE EXPECTED TO BE ABOVE NORMAL
FOR THIS TIME OF YEAR.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 250 PM EST WEDNESDAY...

THIS PORTION OF THE FORECAST HAS THE POTENTIAL TO BE AN ACTIVE
WEATHER PATTERN BASED UPON THE VARIOUS MODELS. HOWEVER...THESE SAME
MODELS OFFER ENOUGH DIFFERENCES TO MAKE THE DETAILS OF THE SENSIBLE
WEATHER ENOUGH OF CHALLENGE THAT CONFIDENCE IN THE SPECIFICS IS NOT
HIGH.

ON SUNDAY...THE CENTER OF SATURDAY/SATURDAY NIGHT SYSTEM WILL TO OUR
EAST ALONG A BAROCLINIC ZONE THAT WILL BE ALONG THE EAST COAST FROM
NORTH CAROLINA TO FLORIDA. WHAT REMAINS AS A QUESTION MARK IS
WHETHER OR NOT ANOTHER WAVE ALONG THIS SAME BAROCLINIC ZONE WILL
PROGRESS FROM GEORGIA NORTHEAST ALONG THE COAST AND DRAW MOISTURE
BACK INTO AT LEAST THE EASTERN PORTIONS OF THE REGION. THEN...BY
MONDAY...THIS SAME LOW MAY OR MAY NOT STRENGTHEN AND DEEPEN AS
ANOTHER CLOSED COASTAL LOW OFF THE COAST OF NORTH CAROLINA.
DEPENDING UPON HOW MUCH OR LITTLE THIS SYSTEM DEEPENS WILL CORRELATE
TO HOW LONG ANY ASSOCIATED PRECIPITATION REMAINS OVER OUR REGION.
THE PRECIPITATION TYPE ACROSS THE AREA IS ALSO A QUESTION. EACH
MODEL HAS A DIFFERENT TAKE ON THE MAGNITUDE OF THE WARM NOSE OVER
OUR REGION. THE ONLY CONSISTENT ELEMENT IS THE EXISTENCE OF A WARM
NOSE. GIVEN THIS...WILL OFFER RAIN VERSUS FREEZING RAIN FORECAST
DURING THE LATE SUNDAY NIGHT THROUGH MONDAY PORTION OF THE FORECAST.
PRECIPITATION CHANCES THOUGH WILL BE ON THE LOW SIDE...MAINLY
RANGING IN THE SLIGHT CHANCE CATEGORY.

BY MONDAY NIGHT...GUIDANCE IS IN FAIRLY GOOD AGREEMENT OF BRINGING A
CANADIAN LOW PRESSURE SYSTEM INTO THE NORTHERN MISSISSIPPI VALLEY.
FROM THAT POINT...A DEEP LONGITUDINAL TROUGH DEVELOPS SOUTH TO THE
GULF OF MEXICO BY TUESDAY AFTERNOON WITH INCREASING SOUTHERLY LOW
LEVEL FLOW ACROSS OUR REGION...ACCOMPANIED BY AN INCREASING MOISTURE
FETCH. BY TUESDAY NIGHT INTO EARLY WEDNESDAY...BOTH THE GFS AND
ECWMF CONTINUE TO DEEPEN THE UPPER LOW AND ASSOCIATED TROUGH AND
NEGATIVELY TILT THE FEATURE SO THAT THE TROUGH AXIS SHIFTS TO OFF
THE COAST OF THE CAROLINAS...COINCIDENT TO THE POSITION OF THE
ASSOCIATED SURFACE OCCLUDED FRONT....WITH THE TRIPLE POINT PASSING
SOMEWHERE NEAR OR JUST SOUTH OF OUR REGION. THIS PAINTS A PICTURE OF
VERY ACTIVE WEATHER ACROSS OUR REGION LATE TUESDAY NIGHT INTO
WEDNESDAY WITH PLENTY OF SHOWERS...VERY GUSTY...IF NOT DAMAGING...
WINDS...AND IF THE TRIPLE POINT PROGNOSTIC IS ACCURATE...SEVERE
WEATHER...OR AT LEAST A RUMBLE OR TWO OF THUNDER...OVER OR VERY
CLOSE TO OUR REGION OF THE COUNTRY. HOWEVER...THIS SCENARIO STILL IS
DAY 6 INTO DAY 7 OF THE FORECAST...AND THERE IS PLENTY OF TIME FOR
CHANGES IN THE OPERATIONAL MODELS TO TREND TOWARD A LESS AGGRESSIVE
SYSTEM. GIVEN THIS...WILL OFFER A FORECAST LATE MONDAY NIGHT INTO
TUESDAY THAT OFFERS INCREASING CHANCES OF LIGHT RAIN OR FREEZING RAIN
     WITH LIGHT TO MODERATE RAIN ON TUESDAY...WITH MODERATE RAIN
SHOWERS TUESDAY NIGHT INTO EARLY WEDNESDAY ALONG WITH GUSTY WINDS.
TIMING OF THE PUSH OF COLDER AIR INTO THE REGION AS WELL AS THE
MAGNITUDE OF THAT COLDER AIR VARIES BETWEEN THE GFS AND ECWMF.
HOWEVER...THE FORECAST WILL ALLOW FOR THE POTENTIAL FOR COLD ENOUGH
AIR TO REACH WESTERN...HIGHER PARTS OF THE AREA LATE TUESDAY NIGHT
INTO WEDNESDAY FOR ACCUMULATING SNOW SHOWERS.

TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL TREND MILDER
THROUGH AT LEAST TUESDAY. WEDNESDAY MAY BE A BIT MILDER IN THE
EAST...AND SLIGHTLY COOLER IN THE WEST AS COMPARED TO TUESDAY. ALL
DAYS OF THIS PORTION OF THE FORECAST ARE EXPECTED TO BE ABOVE NORMAL
FOR THIS TIME OF YEAR.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 1150 PM EST WEDNESDAY...

MOST OF THE REGION WILL EXPERIENCE VFR CONDITIONS THROUGH THE NEXT
24 HOURS. THE EXCEPTION WILL BE THE THOSE AREAS MAINLY ALONG AND
WEST OF A KBLF-KLWB LINE. THINK LWB WILL SCATTER OUT WITH ONLY A
TEMPO FOR BKN MVFR THROUGH 08Z.

MODELS FAVOR BLF LIFTING TO VFR AFTER 15Z. WINDS WILL ALSO WEAKEN
THROUGH THURSDAY.

EXTENDED DISCUSSION...

THURSDAY NIGHT AND FRIDAY LOOK RELATIVELY BENIGN.

THE FRI NIGHT-SAT SYSTEM NOW HAS TRENDED WEAKER BUT WILL STILL
NEED TO BE WATCHED AS IT WILL LIKELY BRING A PERIOD OF SUB VFR
WINTRY WEATHER ESPECIALLY FROM THE BLUE RIDGE WEST SAT.

AVIATION INTERESTS WILL NEED TO MONITOR THIS SITUATION AS LATER
FORECASTS BECOME AVAILABLE. THIS WILL LIKELY HAVE AN IMPACT ON AIR
TRAVEL OVER THE WEEKEND...FROM THE SOUTHERN APPALACHIANS AND
CAROLINAS NORTH TO THE MID ATLANTIC.

ON THE HEELS OF THIS FRIDAY/SATURDAY SYSTEM WILL BE ANOTHER SYSTEM
TO POTENTIALLY IMPACT MAINLY THE EASTERN PORTION OF THE REGION
MONDAY INTO TUESDAY. ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO
HEAD NORTH ALONG THE EAST COAST WITH SCATTERED PRECIPITATION ON
ITS WESTERN FLANKS ENTERING THE REGION. AT THIS POINT A WINTRY MIX
IS POSSIBLE ALONG WITH LOCALIZED MVFR CIGS.

&&

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

&&

$$
SYNOPSIS...PM
NEAR TERM...PM/WP
SHORT TERM...AMS
LONG TERM...DS
AVIATION...DS/PM/WP


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