Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 300153
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
953 PM EDT WED JUL 29 2015

.SYNOPSIS...
UPPER RIDGE WILL STAY CENTERED OVER THE SOUTHERN U.S. TONIGHT. A
FRONT WILL SLIDE ACROSS OUR REGION THURSDAY...STALLING ALONG THE
SOUTHEAST COAST FRIDAY INTO SATURDAY.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 950 PM EDT WEDNESDAY...

LOCAL WRF AND SOME RUNS OF HRRR HAVE SOME PRE-FRONTAL SHOWERS AND
THUNDERSTORMS MOVING INTO THE MOUNTAINS AROUND AFTER
MIDNIGHT...AROUND 05/06Z. HAVE TRIMMED BACK PROBABILITY OF
PRECIPITATION BASED ON THE LATEST RADAR TRENDS THEN HAVE
PROBABILITY INCREASING IN THE WEST LATE TONIGHT. LITTLE TO NO
CHANGE NEEDED FRO MINIMUM TEMPERATURES.

A COLD FRONT APPROACHES TONIGHT FROM THE WEST AND SHOULD REACH
THE OHIO RIVER BY 8 AM THURSDAY MORNING. LOW LEVEL MOISTURE AND
LIGHT WINDS WILL RESULT IN AREAS OF FOG OVERNIGHT. LOWS WILL RANGE
FROM THE UPPER 60S TO LOWER 70S FOR MOST OF THE REGION.

A COLD FRONT WILL TRAVEL EAST ACROSS THE REGION THURSDAY INTO
THURSDAY EVENING. SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP AHEAD AND ALONG THE FRONT. THE SWODY2 CONVECTIVE OUTLOOK
KEEPS OUR CWA IN THE GENERAL THUNDERSTORMS AND SPLITS THE MARGINAL
POTENTIAL TO OUR NORTH AND SOUTH. HIGH TEMPERATURES WILL CLIMB INTO
THE MID 70S IN THE NORTHWEST MOUNTAINS TO THE LOWER 90S IN THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 230 PM EDT WEDNESDAY...

COLD FRONT WILL BE HEADING TO THE COAST THURSDAY EVENING FOLLOWED BY
COOLER HIGH PRESSURE THAT WILL BUILD IN FROM THE WEST THURSDAY NIGHT
INTO FRIDAY. LIKELY TO SEE A BAND OF POST FRONTAL TYPE SHALLOW
CONVECTION OVER THE PIEDMONT DURING THE EARLY EVENING GIVEN MODEST
FORECAST INSTABILITY BEFORE THE AXIS OF DEEP MOISTURE PUSHES TO THE
EAST AND OUT OF THE REGION BY MIDNIGHT. THUS LEAVING IN SOME LOW CHANCE
POPS EAST OF THE BLUE RIDGE BEFORE SEEING CLEARING AND COOLER WEATHER
ALL SECTIONS LATER THURSDAY NIGHT.

WITH 85H TEMPS FALLING TO BETWEEN +14-16C EXPECT QUITE A FEW LOW TEMPS
IN THE 50S TO AROUND 60 ACROSS THE VALLEYS WITH DRIER LOW/MID 60S OUT
EAST. A MAINLY SUNNY AND MUCH LESS HUMID FRIDAY LOOKS ON TAP UNDER GOOD
SUBSIDENCE AND LOW LEVEL NW FLOW. HOWEVER HEATING OF THE DRY AIR WILL
PUSH TEMPS BACK INTO THE LOW/MID 80S MOUNTAINS...AND STILL CLOSE TO 90
SE BUT WITH MUCH LESS HUMIDITY.

AFTER ANOTHER RATHER COOL MORNING SATURDAY...SHOULD SEE TEMPS REBOUND
SLIGHTLY SATURDAY AFTERNOON AS THICKNESS VALUES RISE A BIT AHEAD OF A
SECONDARY TYPE DRY BOUNDARY THAT WILL CROSS THE REGION LATE WITH
ANOTHER QUICK SHOT OF COOL ADVECTION INTO SATURDAY NIGHT. CANT TOTALLY
RULE OUT AN UPSLOPE SPRINKLE OVER NW SECTIONS LATE SATURDAY WHEN LOW
LEVEL NW FLOW WILL BE STRONGEST OTRW TOO DRY FOR MUCH MORE THAN SOME
CLOUDS AT BEST. THIS TO BE FOLLOWED BY YET ANOTHER COMFORTABLE
OVERNIGHT WITH TEMPS FALLING INTO THE 50S TO LOW 60S MOUNTAINS AND
LOW/MID 60S AGAIN OUT EAST.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 1230 PM EDT WEDNESDAY...

PREDOMINATE UPPER TROFFINESS ACROSS THE MID ATLANTIC WILL KEEP NW FLOW
ALOFT IN PLACE FROM THE WEEKEND THROUGH AT LEAST THE MIDDLE OF NEXT
WEEK. THIS SHOULD INITIALLY KEEP OVERALL DRY WEATHER IN PLACE WITH
SURFACE HIGH PRESSURE BUILDING ACROSS THE REGION FROM THE NW SUNDAY-
MONDAY...AND TO THE SOUTH AHEAD OF A REINFORCING COLD FRONT BY
WEDNESDAY. ONLY EXCEPTION TO THIS COULD BE WITH MOISTURE BEING LIFTED
BACK INTO THE SE EARLY NEXT WEEK WITH LOW PRESSURE DEVELOPING ALONG THE
RESIDUAL FRONT NEAR THE COAST. HOWEVER THE EARLIER ECMWF AND CMC ABOUT
THE ONLY SOLUTIONS THAT STILL HINT AT THIS SO BASICALLY LEAVING OUT
MOST POPS OUTSIDE OF SOMETHING ISOLATED SE SECTIONS ON MONDAY.

COLUMN WILL GRADUALLY MOISTEN ENOUGH BY MIDWEEK TO POSSIBLY SUPPORT A
BIT MORE CONVECTION AS WEAK SHORTWAVES ALOFT TRAVERSE THE NW FLOW ON
TUESDAY AHEAD OF A STRONGER UPPER LOW AND COLD FRONT TO THE NORTH
WEDNESDAY. GUIDANCE REMAINS A BIT HESITANT TO PRODUCE MUCH IN THE WAY
OF PRECIP GIVEN MAIN LIFT TO THE NORTH BUT APPEARS ENOUGH FOCUS WITH
HEATING TO SUPPORT SOME LOW POPS TUESDAY AFTERNOON. BETTER CHANCES MAY
COME WEDNESDAY AS THE FRONT SAGS TOWARD THE AREA FROM THE NORTH AND
DEWPOINTS RISE BUT EVEN THEN SUPPORT THIS FAR SOUTH LACKING SO CHANCE
POPS IN ORDER. OTRW MAINLY A PERSISTENCE FORECAST WITH HIGHS 80S TO
AROUND 90 SE AND 60S OVERNIGHT EXCEPT SOME COOLER 50S VALLEYS EARLY IN
THE WEEK AS DEWPOINTS/HUMIDITY REMAIN LOW.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
AS OF 800 PM EDT WEDNESDAY...

AREA RADARS SHOWED ISOLATED SHOWERS AND THUNDERSTORMS OVER WEST
VIRGINIA...SOUTHWEST VIRGINIA AND NORTHWEST NORTH CAROLINA THIS
EVENING. SOME OF THE RAIN WAS CLOSE TO THE LOCAL AIRPORTS...BUT
NOT CLOSE ENOUGH TO INCLUDE IN THE TAFS AT THIS TIME.

AIR MASS REMAINS VERY MOIST AT LOW LEVELS TONIGHT. HIGH CONFIDENCE
FOR THE DEVELOPMENT OF MVFR FOG BY MIDNIGHT. COVERAGE OF SHOWERS
AND THUNDERSTORMS WILL REMAIN ISOLATED UNTIL THE FRONT APPROACHES
THE APPALACHIANS AFTER 10Z/6AM. IFR TO LIFR FOG IS ALSO EXPECTED
AT KBCB AND KLWB.

MODELS...INCLUDING DIFFERENT VERSIONS OF THE HRRR SUGGESTS SOME PREFRONTAL
SHOWERS AND THUNDERSTORMS MAY MOVE INTO THE MOUNTAINS AFTER
MIDNIGHT...BUT THAT THERE WILL BE LITTLE TO PRECIPITATION ALONG
THE ACTUAL FRONT. THUNDERSTORMS MAY DEVELOP ALONG THE BOUNDARY
EAST OF THE BLUE RIDGE SO HAVE INCLUDED VC IN THE KLYH AND KDAN
TAFS FOR THURSDAY AFTERNOON.

A MUCH DRIER AIR MASS COMES INTO THE REGION BEHIND THE FRONT BY
THURSDAY NIGHT.

EXTENDED AVIATION FORECAST...

BEHIND THE FRONT THE WEATHER WILL BE DRY AND VFR FRIDAY THROUGH
SUNDAY.

THE NEXT CHANCE OF MVFR CONDITIONS WILL BE ON MONDAY AND TUESDAY
AS MOISTURE AND A LOW PROBABILITY OF SHOWERS AND THUNDERSTORMS
RETURN TO THE REGION.

&&

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

&&

$$
SYNOPSIS...AMS/WP
NEAR TERM...KK
SHORT TERM...JH
LONG TERM...JH
AVIATION...AMS/KK



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