Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 290559
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
159 AM EDT SAT AUG 29 2015

.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL SLIDE SOUTH AND
REMAIN ABOUT OVERHEAD INTO SATURDAY. A WEAK UPPER LEVEL
DISTURBANCE WILL LIFT NORTH ALONG THE APPALACHIANS SUNDAY INTO
MONDAY AHEAD OF A WEAK COLD FRONT TO THE WEST. UPPER LEVEL HIGH
PRESSURE WILL STRENGTHEN IN THE WAKE OF THIS FEATURE...RESULTING
IN MORE DIURNAL NATURE SHOWERS AND STORMS INTO THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 1137 PM EDT FRIDAY...

OUTER RING OF HIGH CLOUDS FROM WHAT WAS LEFT OF DANNY STREAMING
ACROSS THE SRN CWA WITH MID CLOUDS ACROSS THE MOUNTAINS AND
NORTHERN SECTIONS OF THE VIRGINIA PIEDMONT ALONG/NORTH FROM LYH TO
ROA.

FORECAST OVERNIGHT FAVORS A MIX OF CLOUDS AND STARS...WITH SOME
VALLEY FOG FORMING. OVERNIGHT LOWS WILL BE WARMER THAN PREVIOUS
NIGHTS AS DEWPOINTS ARE IN THE UPPER 50S TO LOWER 60S. ADJUSTED
SOME TEMPS UP. LOWS BE IN THE MID TO UPPER 50S...WITH SOME URBAN
AREAS IN THE LOWER 60S.

PREVIOUS VALID DISCUSSION...

THE MAIN WEATHER FEATURE DRIVING OUR WEATHER INTO THE FIRST PART OF THE
WEEKEND WILL CONTINUE TO BE AN AREA OF HIGH PRESSURE LINGERING OVER THE
EASTERN SEABOARD WITH ANY SIGNIFICANT SYNOPTIC SHORT WAVE ENERGY
SLIDING BY WELL TO OUR NORTH. SATURDAY WILL HAVE A SIMILAR FLAVOR
WITH ISOLATED SHOWERS POSSIBLE WEST OF THE RIDGE. HIGHS SATURDAY
WILL BE IN THE MIDDLE 80S EAST TO UPPER 70S/AROUND 80 WEST.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 230 PM EDT FRIDAY...

RIDGING BOTH SURFACE AND ALOFT WILL LINGER INTO SATURDAY NIGHT BEFORE
GIVING WAY TO AN UPSTREAM UPPER TROUGH AND ASSOCIATED WEAK FRONTAL
BOUNDARY SUNDAY INTO MONDAY. THIS SHOULD ALLOW FOR A PLUME OF DEEPER
MOISTURE ACROSS THE SOUTHEAST TO BE PULLED NORTHWARD ALONG THE
APPALACHIANS WITH EMBEDDED SHORTWAVE ENERGY AIDING LIFT ALONG WITH
HEATING.

MODELS CONTINUE TO SHOW THE BEST FOCUS IN AN ARC ACROSS THE
MOUNTAINS WITH BETTER INSTABILITY...DIFFLUENCE AND THETA-E RIGHT ALONG
THE WESTERN SLOPES ESPECIALLY LATER SUNDAY INTO EARLY MONDAY. HOWEVER
THIS AGAIN WITHIN AN AREA OF LOW LEVEL SUBSIDENCE ENHANCED VIA WEAK
SURFACE RIDGING ACROSS THE MOUNTAINS SO EXPECTING MORE SCATTERED NATURE
COVERAGE AT THIS POINT. THUS HOLDING OFF ON GOING MUCH MORE THAN MID
CHANCE POPS...MAINLY BLUE RIDGE WEST FROM SUNDAY AFTERNOON INTO LATE
MONDAY...WITH HIGHEST ACROSS THE FAR WESTERN COUNTIES WHERE FORECAST
SOUNDINGS SHOW QUITE A MOIST/WEAKLY VEERED PROFILE BY MONDAY AFTERNOON.
WITH LOW LEVEL MOISTURE A BIT LESS EAST OF THE MOUNTAINS...APPEARS
SHOWERS MORE ISOLATED SO ONLY KEEPING A 20ISH POP OUT EAST FOR NOW.

WARMING 85H TEMPS SUPPORT RATHER WARM TEMPS EAST OF THE MOUNTAINS BOTH
SUNDAY AND MONDAY WHEN TEMPS MAY GET CLOSE TO 90 PIEDMONT PENDING
DEGREE OF CLOUDS. OTHERWISE BECOMING MORE MUGGY GIVEN INCREASING
DEWPOINTS...AND HIGHS MOSTLY IN THE 80S WITH SOME 70S POSSIBLE FAR WEST
ESPECIALLY IF SHOWERS ARE MORE WIDESPREAD SUNDAY/MONDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1240 PM EDT FRIDAY...

OVERALL PERSISTENCE FORECAST AT LEAST EARLY ON AS UPPER RIDGING
STRENGTHENS ACROSS THE REGION IN THE WAKE OF THE PASSING WAVE ALOFT AND
IN INCREASING SUBSIDENCE WELL NORTH OF ERIKA. THIS SHOULD RESULT IN A
MORE DIURNALLY DRIVEN TREND OF DAILY SHOWERS AND ISOLATED STORMS EACH
AFTERNOON/EVENING WITH A GRADUAL INCREASE IN COVERAGE/EXPANSE FROM
TUESDAY THROUGH THURSDAY GIVEN BETTER PWATS/MOISTURE AND SLIGHT COOLING
ALOFT. HOWEVER THINK LOW/MEDIUM CHANCE POPS CONFINED MAINLY ALONG/WEST
OF THE BLUE RIDGE PER OROGRAPHICS...AND MORE ISOLATED ELSEWHERE
ESPECIALLY GIVEN MOISTURE OVER TOP A LINGERING SURFACE RIDGE. THUS
FOLLOWED CLOSER TO TRENDS FROM WPC WITH A GRADUAL BOOST IN POPS EACH
DAY BUT LITTLE DURING THE OVERNIGHTS INTO THURSDAY. THINGS BECOME MORE
UNCERTAIN BY DAY7 WITH MODELS LOWERING HEIGHTS ACROSS THE APPALACHIANS
AND FROM THE NE WITH A POSSIBLE ASSOCIATED BACKDOOR COOL FRONT. THIS
COULD HELP FOCUS MOISTURE GIVEN A BETTER EASTERLY TRAJECTORY TO THE
NORTH OF ERIKA OR ITS REMNANTS ON FRIDAY. THEREFORE GOING WITH MORE
WIDESPREAD CHANCE POPS PER POTENTIAL TROPICAL TYPE PWATS OVER THE AREA
DURING HEATING FRIDAY AFTERNOON.

OTHERWISE LITTLE CHANGE IN DAILY TEMPS GIVEN SUCH A HUMID/WARM
AIRMASS...SUPPORTING HIGHS MOSTLY IN THE 80S AND LOWS IN THE 60S EXCEPT
PERHAPS A BIT COOLER FRIDAY PENDING CLOUDS/SHOWERS.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 155 AM EDT SATURDAY...

HIGH PRESSURE IS CENTERED OVER THE DELMARVA THIS MORNING...MAKING
FOR VERY LIGHT SOUTH SOUTHEASTERLY WINDFLOW ACROSS THE AREA. LOW
LEVEL MOISTURE IS GRADUALLY INCREASING AS THIS WINDFLOW DRAWS
ATLANTIC AIR UPSLOPE INTO THE MOUNTAINS. AS SUCH...SURFACE
OBSERVATIONS ACROSS THE MOUNTAINS AND FOOTHILLS HAVE DETECTED
SCATTERED CEILINGS IN THE 4KFT TO 6KFT RANGE...WHICH ARE EXPECTED
TO PERSIST THROUGH THE NIGHT. MAY ALSO SEE THE VISIBILITY BOUNCE
UP AND DOWN IN SPOTS...DEPENDING ON CLOUD COVER...AS PATCHY GROUND
FOG DEVELOPS ACROSS LOCATIONS WHERE THE SKIES CLEAR.

ANY FOG WILL BURN OFF QUICKLY AFTER 29/14Z WITH DAYTIME HEATING...
RESULTING IN VFR CONDITIONS AREAWIDE. INCREASING MOISTURE WILL
MAKE FOR A SCT CU FIELD DEVELOPING LATE MORNING...POSSIBLY
BECOMING BKN ACROSS THE MOUNTAINS DURING LATE AFTERNOON...WITH
CEILING BASES 4KFT TO 6KFT. INSTABILITY IS LIMITED...BUT MAY BE
SUFFICIENT TO TRIGGER ISOLATED SHOWERS ACROSS SOUTHEAST WEST
VIRGINIA...POSSIBLY AS FAR EAST AS KBCB. EVEN THEN...SHOWER
THREAT IS NOT EXPECTED TO RESULT IN SUB VFR CONDITIONS WHERE THEY
OCCUR FOR MORE THAN A FEW MINUTES. CONVECTION WILL WANE TOWARD
SUNSET.

EXTENDED AVIATION DISCUSSION...
AS OF 130 PM EDT FRIDAY...

EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY
INCREASES...WHICH WILL RAISE OUR CHANCES FOR DIURNAL SHOWERS AND
STORMS AS WE HEAD INTO THE FIRST PART OF NEXT WEEK. SHORT WAVE
ENERGY MOVING UP FROM THE SOUTH WILL GIVE THE BEST CHANCES FOR
MORE WIDESPREAD CONVECTIVE ACTIVITY IN THE SUNDAY/MONDAY TIME
FRAME. GENERALLY EXPECT THE BEST CHANCES FOR MVFR/IFR TO BE LATE
NIGHT/EARLY MORNING DUE TO FOG AND STRATUS DEVELOPMENT FROM THE
BLUE RIDGE WEST ESPECIALLY AT KLWB/KBCB.

&&

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

&&

$$
SYNOPSIS...JH
NEAR TERM...MBS/WP
SHORT TERM...JH
LONG TERM...JH
AVIATION...NF/WP


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