Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 291943
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
343 PM EDT FRI AUG 29 2014

.SYNOPSIS...
A STALLED FRONTAL BOUNDARY NEAR THE SOUTH CAROLINA...NORTH
CAROLINA BORDER WILL GRADUALLY MOVE NORTH TONIGHT THROUGH
SATURDAY...AND BE POSITIONED OVER NORTHERN VIRGINIA BY SATURDAY
AFTERNOON. A MORE SUBSTANTIAL COLD FRONT WILL APPROACH THE AREA
SATURDAY NIGHT AND MOVE THROUGH THE AREA SUNDAY AND SUNDAY NIGHT.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 310 PM EDT FRIDAY...

A FRONTAL BOUNDARY WAS STALLED ALONG THE NC/SC BORDER. HIGH PRESSURE
WAS CENTERED OVER NEW YORK STATE. ANTI-CYCLONIC FLOW AROUND THE HIGH
IS ADVECTING MOISTURE INTO THE AREA FROM THE ATLANTIC OCEAN. AN
INVERTED TROUGH WAS PUTTING A WRINKLE IN THE SOUTHWEST SIDE OF THE
HIGH BETWEEN KY/WV. THROUGH THE REMAINDER OF THE AFTERNOON AND INTO
THE EVENING...WE STILL EXPECT ISOLATED TO SCATTERED COVERAGE OF
SHOWERS...AND MAYBE A FEW STORMS...MAINLY WITHIN THE AREA OF
GREATEST INSTABILITY NEAR THE AXIS OF THE INVERTED TROUGH FED BY THE
STREAM OF ATLANTIC MOISTURE.

THROUGH THE OVERNIGHT HOURS...THE NC/SC STALLED FRONT WILL LIFT
SLOWLY NORTH AS A WARM FRONT AND STALL NEAR A LINE FROM WASHINGTON
D.C. TO NORFOLK VA BY MIDDAY SUNDAY. WE EXPECT LIGHT...ISOLATED
COVERAGE OF SHOWERS TO ACCOMPANY THIS FRONT ON ITS JOURNEY TONIGHT
ACROSS THE AREA. PLENTY OF LOW LEVEL MOISTURE WILL ALSO CONDENSE
INTO PLENTY OF LOW LEVEL CLOUDS ACROSS THE AREA OVERNIGHT ALONG WITH
PATCHY FOG TO AREAS OF FOG DEVELOPING BY MIDNIGHT AND LASTING INTO
AT LEAST THE MID MORNING ON SATURDAY.

WE EXPECT A BREAK IN THE PRECIPITATION BY LATE TONIGHT THROUGH MIDDAY
SATURDAY WITH THE FORCING ASSOCIATED WITH THE FRONT NORTH OF THE
REGION. HOWEVER...BY THE AFTERNOON...ENOUGH DAYTIME HEATING IS
EXPECTED TO REFIRE SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE
NORTHERN PARTS OF THE REGION CLOSEST TO THE NEW LOCATION OF THE
STALLED FRONT. ALSO...INCREASING SOUTHERLY WINDS WILL FOCUS UPSLOPE
ISOLATED SHOWER AND THUNDERSTORM POTENTIAL ALONG THE CREST OF THE
BLUE RIDGE.

LOW TEMPERATURES TONIGHT WILL BE A MIX OF LOW TO MID 60S ACROSS THE
MOUNTAINS WITH MID TO UPPER 60S ACROSS THE PIEDMONT. ON
SATURDAY...HIGH TEMPERATURES IN THE LOW TO MID 80S WILL BE COMMON IN
THE MOUNTAINS WITH UPPER 80S TO NEAR 90 ACROSS THE PIEDMONT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 330 PM EDT FRIDAY...

UPPER LEVEL RIDGE FORECAST OVER THE SOUTHEASTERN CONUS TO REMAIN IN
PLACE IN THE SHORT-TERM WITH THE MAIN WEATHER FEATURE A SERIES OF
SOUTHERN STREAM SHORT-WAVES EXPECTED TO TRACK FROM THE GULF COAST
NORTHEAST INTO THE OHIO VALLEY. 12Z MODEL RUNS OF GFS/NAM/EURO
SHOWING THIS FEATURE OR SERIES OF FEATURES TRACKING SOMEWHAT
FURTHER WEST THAN PREVIOUS RUNS DUE PARTLY TO THE STRONG RIDGE.
AXIS OF HEAVIEST RAINFALL SHOULD STAY WEST OF OUR CWA BUT STILL
HAVE LIKELY POPS IN THE FAR WEST ON SUNDAY TAPERING TO CHANCE
ACROSS THE PIEDMONT ON SUNDAY. RIDGE FLATTENS SOMEWHAT ON MONDAY
AS UPPER TROUGH ENERGY REMAINS WILL NORTH BUT WILL STILL BE
CHANCES FOR MAINLY AFTERNOON SHOWERS AND SCATTERED THUNDERSTORMS
MONDAY AFTERNOON. TEMPS WILL REMAIN WARM THROUGH THE PERIOD WITH
MAINLY 80S FOR HIGHS AND 60S FOR LOWS EVEN WITH CONSIDERABLE
CLOUDS ON SUNDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...

FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 130 PM EDT FRIDAY...

VISIBILITY SENSOR AT KDAN REMAINS INOPERABLE. PARTS ARE ON
ORDER. UNTIL REPAIRS COMPLETE...NO AMENDMENTS WILL BE SCHEDULED.

MORNING MVFR STRATOCU CLOUDS OVER MUCH OF THE CENTRAL AND
SOUTHEASTERN PARTS OF THE REGION HAVE FINALLY ERODED...OR LIFTED
TO LOW END VFR SCT-BKN. THE ATMOSPHERE IS BECOMING UNSTABLE ACROSS
THE WESTERN PART OF THE REGION BETWEEN KBLF-KTNB. NEW MVFR-LOW END
VFR CUMULUS CLOUDS ARE DEVELOPING IN THIS REGION...AND ISOLATED
SHOWERS AND PERHAPS A FEW THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON INTO THE EARLY EVENING IN THIS REGION.

OVERNIGHT...A STATIONARY FRONT WILL MAKE SOME PROGRESS NORTH AS A
WARM FRONT ALONG WITH SOME PATCHY SHOWERS SOUTH OF IT. LOW LEVEL
MOISTURE WILL INCREASE AN BECOME TRAPPED UNDER THE NOCTURNAL
INVERSION. ANTICIPATE MOST OF THE REGION TO DEVELOP MVFR CIGS WITH
SOME REGIONS OF IFR. VSBYS WILL ALSO DECREASE WITH MOST AREAS
HAVING MVFR WITH POCKETS OF IFR.

ANY SUB-VFR CONDITIONS WILL BE FAIRLY SLOW TO IMPROVE TO VFR AFTER
SUNRISE SATURDAY. 15Z/11AM IS THE MOST LIKELY TIME MOST OF THE
REGION WILL BE BACK TO VFR.

EXTENDED DISCUSSION...

ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
CONFINED TO AN AREA ALONG AND NORTH OF A KHSP-KFVX LINE SATURDAY
AFTERNOON...JUST SOUTH OF THE AGAIN STALLED FRONTAL BOUNDARY.

LATE SATURDAY NIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE
WILL HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW
ENGLAND. ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION
BRINGING A GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR
CONDITIONS ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.

ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CIRCUMSTANCES
TUESDAY INTO TUESDAY NIGHT. HOWEVER...MODEL GUIDANCE FOR THIS ONE
OFFERS PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS
SUCH...THE MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.

&&

.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...

THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.

&&

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

&&

$$
SYNOPSIS...DS
NEAR TERM...DS
SHORT TERM...PC
LONG TERM...PC
AVIATION...DS
EQUIPMENT...AMS



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