Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 280602
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
202 AM EDT TUE JUL 28 2015

.SYNOPSIS...
AHEAD OF A COLD FRONT...SCATTERED SHOWERS AND THUNDERSTORMS ARE
POSSIBLE EACH AFTERNOON AND EVENING THROUGH WEDNESDAY. A COLD
FRONT WILL ARRIVE THURSDAY WITH THE NEXT CHANCE FOR MORE
WIDESPREAD SHOWERS AND THUNDERSTORMS. WEAK HIGH PRESSURE AND
MOSTLY DRY WEATHER IS EXPECTED BY THE WEEKEND. OTHERWISE...IT WILL
REMAIN WARM AND HUMID FOR THE NEXT SEVERAL DAYS.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 1155 PM EDT MONDAY...

SHOWERS AND THUNDERSTORMS HAVE DEVELOP ALONG AN AXIS FROM SOUTHERN
ALLEGHENY COUNTY VIRGINIA TO DANVILLE. SIMILAR TO MOST OF THE
STORMS MONDAY AFTERNOON AND EVENING...STORMS WERE SLOW MOVING AND
WILL PRODUCE HEAVY RAIN. HAVE ADJUSTED PROBABILITY OF
PRECIPITATION TO ACCOUNT FOR THE LATEST RADAR TRENDS.

FLOW IS RELATIVELY WEAK ALOFT BUT ENOUGH ENERGY AND INSTABILITIES
REMAINS OVERNIGHT TO KEEP SHOWERS ACTIVITY ONGOING UNTIL THE EARLY
MORNING HOURS TUESDAY. THERE SHOULD BE A LULL IN ACTIVITY TUESDAY
MORNING...THEN ANOTHER WAVE ROUNDING THE UPPER LEVEL RIDGE OVER THE
SOUTHERN PLAINS IS EXPECTED TO TRACK ACROSS THE REGION TUESDAY
AFTERNOON.

LESS CLOUD COVER IS EXPECTED TOMORROW...THEREFORE WE SHOULD SEE
TEMPERATURES WARMING TO NEAR NORMAL WITH MID 80S WEST TO THE LOWER
90S EAST.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS OF 305 PM EDT MONDAY...

SCATTERED DIURNAL SHOWERS AND THUNDERSTORMS WILL DIMINISH TUESDAY
EVENING INTO TUESDAY NIGHT. THE COMBINATION OF THE DIFFUSE FRONTAL
BOUNDARY AND DIFFERENTIAL HEATING ACROSS THE HIGHER ELEVATIONS
SHOULD FOCUS THE BEST CHANCE OF CONVECTION ACROSS SOUTHERN PORTIONS
OF FORECAST AREA...ESPECIALLY NORTHWEST NORTH CAROLINA. MOST OF THE
CONVECTION WILL END BEFORE MIDNIGHT. PARTLY TO MOSTLY CLOUDY SKIES
WITH AREAS OF FOG EXPECTED TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW
TEMPERATURES TUESDAY NIGHT WILL BE MILD WITH READINGS FROM THE MID
60S IN THE MOUNTAINS TO AROUND 70 DEGREES.

A COLD FRONT WILL APPROACH FROM THE OHIO VALLEY ON WEDNESDAY. SOLAR
HEATING AND LINGERING SFC BOUNDARIES WILL RESULT SCATTERED DIURNAL
SHOWERS AND THUNDERSTORMS...WITH BEST POTENTIAL WEST OF INTERSTATE
77. HIGH TEMPERATURES WEDNESDAY AFTERNOON WILL CLIMB INTO THE MID
80S IN THE MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT.

THE STRONG SUBTROPICAL RIDGE IN CENTRAL UNITED STATES RETROGRADES
INTO SOUTHWEST...AS LOW PRESSURE ALOFT MOVES EASTWARD ALONG CANADIAN
BORDER. THIS WILL DRIVE A COLD FRONT SOUTHEAST ACROSS THE REGION.
THE FRONTAL BOUNDARY ENTERS OUR WESTERN MOUNTAINS WEDNESDAY NIGHT
INTO THURSDAY...ON BOTH THE ECMWF AND GFS. LOWS WEDNESDAY NIGHT WILL
VARY FROM THE MID 60S IN THE WEST TO THE LOWER 70S IN THE EAST.

A COLD FRONT WITH SEVERAL WAVES OF LOW PRESSURE ALONG IT MOVES EAST
ACROSS THE AREA ON THURSDAY INTO THURSDAY NIGHT. SHOWERS AND
THUNDERSTORMS WILL SPREAD FROM WEST TO EAST ACROSS OUR AREA. HIGH
TEMPERATURES THURSDAY WILL RANGE FROM THE UPPER 70S IN THE WESTERN
MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. PLACED THE HIGHEST POPS
IN THE EAST THURSDAY NIGHT AS FRONT PUSHES INTO THE ATLANTIC OCEAN.
LOWS THURSDAY NIGHT WILL BE FROM THE MID 60S IN THE WEST TO LOWER
70S IN THE EAST.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 305 PM EDT MONDAY...

THE DEEPENING UPPER TROUGH OVER NORTHEAST WILL ENABLE THE FRONTAL
BOUNDARY TO MOVE SOUTH INTO THE SOUTHEAST STATES BEFORE IT STALLS.
CONSEQUENTLY...ANY SUBSEQUENT LOW PRESSURE WILL REMAIN SOUTH OF THE
REGION RIDING ALONG THE FRONTAL BOUNDARY.

HIGH PRESSURE WILL BUILD EAST OUT OF THE OHIO VALLEY INTO OUR AREA
FRIDAY INTO FRIDAY NIGHT. THE BEST CHANCE FOR ANY CONVECTION ON
FRIDAY WILL OCCUR ACROSS THE SOUTHEAST. THIS IS BECAUSE DRIER AIR
WITH LOWER DEWPOINTS WILL MOVE INTO OUR AREA...HINDERING
INSTABILITIES. WITH A WAVE OF LOW PRESSURE LIFTING THE BOUNDARY
NORTH AS IT TRAVERSES EASTWARD ON SATURDAY. DECIDED TO USED THE
SUPERBLEND WITH ITS SLIGHT CHANCE OF CONVECTION IN THE SOUTHERN
HALF OF FORECAST AREA SATURDAY INTO SATURDAY NIGHT. WITH THE
DIFFERENCES IN GFS AND ECMWF...IT IS HARD TO TELL HOW FAR NORTH
MOISTURE ACTUALLY LIFTS. ON SUNDAY...BOTH THE ECMWF AND GFS
TRANSPORT SOME MOISTURE IN NORTHERN NORTH CAROLINA.

BY MONDAY...THE UPPER TROUGH ACROSS THE GREAT LAKES DEEPENS AS SHORT
WAVE ENERGY TRACKS THROUGH THE BASE OF THE TROUGH. THIS WILL PUSH
THE NEXT COLD FRONT AND ITS ASSOCIATED PRECIPITATION SOUTHEAST. THE
COLD FRONT WILL BE JUST TO OUR WEST SUNDAY NIGHT AND TRAVEL EAST
ACROSS THE REGION MONDAY INTO MONDAY NIGHT.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 200 AM EDT TUESDAY...

LATEST RADAR IMAGES INDICATE THE BURST OF LATE NIGHT CONVECTIVE
ACTIVITY IN THE DIFFUSE FRONTAL ZONE OVER THE REGION IS
DIMINISHING BUT ACTIVE WEATHER STILL CONTINUES NEAR KLYH. BELIEVE
COHESIVE ACTIVITY WILL PERSIST FOR ANOTHER 1 TO 3 HOURS AS
BOUNDARY INTERACTION RUNS ITS COURSE. AMOUNT OF FOG FORMATION IS
QUESTIONABLE GIVEN RESIDUAL CLOUD COVER SO WILL KEEP THINGS
GENERALLY MVFR EAST OF THE BLUE RIDGE BUT TEMPO TO IFR TO THE
WEST. OBSERVATIONS FROM KLWB SHOW A LIGHT NORTHEAST FLOW AND MODEL
GUIDANCE INDICATES THIS FLOW WILL BE IN AND OUT THROUGH TONIGHT.
THIS USUALLY MITIGATES DENSE FOR AT KLWB BUT WHEN THE WIND GOES
CALM LIFR CONDITIONS CAN WAFT IN. WILL USE A TEMPO LIFR GROUP AT
KLWB AND TAG IT WITH CALM WIND CONDITIONS TO CONVEY THIS TRAIN OF
THOUGHT.

NOT MUCH CHANGE WITH THE SYNOPTIC PATTERN FOR TODAY AS THE FRONTAL
BOUNDARY WILL LINGER IN THE AREA AND HELP KICK OFF MORE SHOWERS
AND STORMS THIS AFTERNOON. ISOLATED ACTIVITY WILL BE FLOATING
AROUND THROUGHOUT THE MORNING BUT THINGS REALLY DONT GET GOING
UNTIL THE AFTERNOON SO WILL CONFINE MENTION OF THUNDER TO AFTER
16Z. ENVIRONMENT CONTINUES TO BE WEAKLY FORCED SO EXPECT HEAVY
RAINERS WITH A LOW SEVERE THREAT. ACTIVITY WILL THEN START TO WIND
DOWN WITH LOSS OF HEATING AFTER SUNSET.

EXTENDED AVIATION FORECAST...

WEDNESDAY WILL BE ANOTHER DAY OF MVFR TO IFR VALLEY FOG IN THE
MORNING AND SCATTERED AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS.

MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED ON THURSDAY
AS A COLD FRONT CROSSES THROUGH REGION FROM THE NORTHWEST. THIS
FRONT SHOULD PUSH SOUTH OF THE AREA AND ALLOW FOR DRIER AND MOSTLY
VFR CONDITIONS FRI-SAT.

&&

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

&&

$$
SYNOPSIS...RCS
NEAR TERM...RCS
SHORT TERM...KK
LONG TERM...KK
AVIATION...MBS/AMS



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