Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 230357
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1157 PM EDT FRI AUG 22 2014

.SYNOPSIS...
OVER THE WEEKEND A FRONT IS EXPECTED TO MOVE SOUTH ALONG THE EAST
COAST...WHICH WILL BRING COOLER AIR TO AREAS EAST OF THE
APPALACHIANS...WHILE VERY WARM SULTRY WEATHER CONTINUES ACROSS THE
MID SECTION OF THE UNITED STATES.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1146 PM EDT FRIDAY...

BASED ON LATEST RADAR DATA AND MODEL DATA...THE MAIN AXIS OF
HEAVIER SHRA/TSRA HAS SHIFT JUST WEST OF THE MTN EMPIRE OF SW
VA...AND NOT REALLY EXPECTING THE SHOWERS UPSTREAM TO BE TOO HEAVY
TO CAUSE FLASH FLOODING...THEREFORE...DROPPED THE FLASH FLOOD
WATCH FOR THE REST OF THE SW CWA EARLY. CANNOT RULE OUT THE
TYPICAL PONDING OF WATER ON ROADS...AND FLOODED DITCHES.

OTHERWISE...UPDATED THE OVERNIGHT POPS TO ACCOUNT FOR THE 00Z NAM
WHICH IS NOT TOO FAR OFF COURSE FROM WHAT IS CURRENTLY GOING ON.
MAY SEE MORE DEVELOPMENT IN THE PIEDMONT THROUGH DAWN.

PREVIOUS VALID DISCUSSION...

A BACKDOOR COLD FRONT WILL BEGIN TO DROP SOUTH ACROSS OUR AREA AS
HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES REGION.
REGARDLESS...LIGHT WINDS... MOIST SOILS AND BREAKS IN THE CLOUD
COVER WILL ALLOW PATCHY DENSE FOG TO DEVELOP ONCE AGAIN. OVERNIGHT
LOWS WILL RANGE FROM THE MID 60S WEST TO AROUND 70 EAST.

THE COLD FRONT WILL CONTINUE TO PUSH SOUTH ON SATURDAY. WILL SEE
NORTHEASTERLY WINDFLOW ACROSS THE PIEDMONT AS HIGH PRESSURE
CONTINUES TO WEDGE SOUTH...WHILE NORTHWESTERLY WINDS WILL PERSIST
ACROSS THE MOUNTAINS. AS SUCH...SHOULD SEE A REDEVELOPMENT OF
SHOWERS ALONG THE BLUE RIDGE DUE TO THE INCREASED LOW LEVEL
CONVERGENCE. WILL STILL HAVE MOIST ATMOSPHERIC CONDITIONS TO START
THE DAY...HOWEVER MOISTURE WILL GRADUALLY DECREASE DURING THE
AFTERNOON AS DRIER AIR MOVES IN FROM THE NORTHEAST.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 245 PM EDT FRIDAY...

SURFACE WEDGE BECOMES FIRMLY ESTABLISHED SATURDAY NIGHT AND SUNDAY.
LOW LEVEL MOISTURE...ESPECIALLY ALONG AND JUST EAST OF THE BLUE
RIDGE DIMINISHED BY SUNDAY NIGHT. ENOUGH DRY AIR TO CUT BACK ON
PROBABILITY OF PRECIPITATION ON SUNDAY NIGHT AND CLOUD COVER FOR
MONDAY.

WILL KEEP MAXIMUM TEMPERATURES BELOW GUIDANCE FOR SUNDAY. MONDAY
WILL BE A BALANCE BETWEEN COOLER AIRMASS IN THE WEDGE AND AUGUST
SUN.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1145 AM EDT FRIDAY...

DEEP UPPER TROF CROSSING THROUGH THE CENTRAL UNITED STATES
COMPLETELY FLATTENS THE SOUTHEAST RIDGE ON WEDNESDAY AND THURSDAY.
SPREAD OF SOLUTIONS ON MODELS BECOMES QUITE LARGE BY WEDNESDAY.
WPC WAS LEANING TOWARD THE LESS AMPLIFIED...MORE PROGRESSIVE
ECMWF.

THE SURFACE HIGH THAT WEDGES DOWN THE APPALACHIANS STARTS OUT
OVER NEW ENGLAND...THEN BY WEDNESDAY THE PARENT HIGH MOVES
OFFSHORE. BY THAT TIME THE AMOUNT OF EASTERLY FLOW AND RIDGING
WILL BE INFLUENCED BY WHATEVER TROPICAL SYSTEM WILL BE FATHER EAST
IN THE ATLANTIC.

A COLD FRONT OVER THE GREAT LAKES ON WEDNESDAY WILL APPROACH THE
FORECAST AREA LATE ON THURSDAY. MODELS SUGGEST NOT A LOT OF
SOUTHWARD PUSH OF THIS FRONT. BOUNDARY MAY STILL BE IN THE AREA ON
FRIDAY. AS THE SURFACE WEDGE BREAK DOWN AND THE FRONT
APPROACHES...850 MB TEMPERATURES WILL RISE.

FORECAST AREA WILL BE DRY AT MID AND UPPER LEVELS MONDAY NIGHT
THROUGH WEDNESDAY NIGHT. THEN BY THURSDAY DEEPER MOISTURE COMES
BACK INTO THE AREA ALONG THE FRONT. ECMWF EVEN SHOWED DRYING WELL
BELOW 850 MB ON TUESDAY.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
AS OF 715 PM EDT FRIDAY...

CONTINUE TO OBSERVE LIGHT TO MODERATE SHOWER ACTIVITY MAKING ITS
WAY FROM SOUTHEAST WEST VIRGINIA...ACROSS KBCB-KROA.
HOWEVER...STRONGER CONVECTION IS OBSERVED DEVELOPING ACROSS
SOUTHERN WEST VIRGINIA...WHICH IS DRIFTING SOUTHEAST TOWARD KBLF.
SHOWERS WILL CONTINUE TO PASS OVER THE AREA FROM BLUEFIELD WV TO
MOUNT AIRY NC INTO THE EARLY MORNING HOURS. VFR CONDITIONS EXPECT
WHEN THERE IS NO RAIN TO HIGH-END MVFR WHEN SHOWERS PASS OVER.
SHOWERS DRIFTING INTO A SLIGHTLY STABLE AIR MASS WITH LIGHTNING
ACTIVITY ISOLATED OVER THE MOUNTAINS. ONE STORM BEARS WATCHING
WILL TRACK FROM THE NORTHWEST NORTH CAROLINA HIGH COUNTY AND INTO
THE FOOTHILLS THIS EVENING. AS THIS STORM DRIFTS EAST OF THE BLUE
RIDGE...IT MAY INTENSIFY AND DISRUPT TRAFFIC BETWEEN ROANOKE VA
AND CHARLOTTE NC. WIND GUSTS WITH THIS STORM HAS BEEN AS HIGH AS
40 MPH.

SHOWERS WILL DECREASE IN COVERAGE OVERNIGHT...BUT WILL NOT
DISAPPEAR ALTOGETHER. EXPECT A RETURN OF MVFR/IFR CEILINGS ACROSS
THE MOUNTAINS...WHEREAS CEILINGS WILL REMAIN VFR ACROSS THE
PIEDMONT FOR MUCH OF THE NIGHT...BEFORE FALLING TO MVFR/IFR TOWARD
DAWN. HIGH PRESSURE WILL BUILD SOUTH FROM THE GREAT LAKES...
FINALLY PUSHING THE STALLED FRONTAL BOUNDARY THROUGH THE FORECAST
AREA FROM THE NORTHEAST TO FORM A WEDGING PATTERN. LOW LEVEL
CONVERGENCE ALONG THE BLUE RIDGE WILL TRIGGER MORE SHOWERS
SATURDAY AFTERNOON...HOWEVER THE ATMOSPHERE WILL GRADUALLY DRY
FROM THE NORTH AS THE HIGH SETTLES IN.

EXTENDED AVIATION...

EXPECT FLYING CONDITIONS TO SLOWLY IMPROVE SATURDAY NIGHT AND
SUNDAY AS HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTHEAST.
WILL SEE A FEW SHOWERS DEVELOP ON SUNDAY AFTERNOON...HOWEVER THE
MAIN CONCERN WILL BE EARLY MORNING FOG AND STRATUS. STRATUS WILL
BE SLOW TO BURN OFF THROUGH THE DAY...ALTHOUGH BREAKS WILL DEVELOP
DURING THE AFTERNOON. A BETTER PUNCH OF DRY AIR WITH HIGH PRESSURE
BUILDING IN FROM THE NORTHEAST MAY BE ENOUGH WITH MIXING/HEATING
TO ALLOW FOR INCREASING VFR CONDITIONS MONDAY INTO TUESDAY UNDER
MAINLY DRY CONDITIONS.

&&

.EQUIPMENT...
THE ASOS AT LYNCHBURG (LYH) VA REMAINS PARTIALLY INOP DUE TO A
BOARD FAILURE. PARTS HAVE BEEN ORDERED WITH THE RETURN OF
COMPLETE SERVICE UNKNOWN AT THIS TIME.

THE NOAA WEATHER RADIO AT WYTHEVILLE VA...WZ2500...BROADCASTING
ON A FREQUENCY OF 162.450 MHZ IS OFF THE AIR. VERIZON HAS BEEN
CONTACTED.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...NF/RCS/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...NF/RCS
EQUIPMENT...


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