Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 280219
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1019 PM EDT THU AUG 27 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
TONIGHT AND REMAIN ENTRENCHED ACROSS THE AREA INTO SATURDAY. A
WEAK UPPER LEVEL DISTURBANCE WILL SLIDE NORTH ALONG THE
APPALACHIANS SUNDAY INTO MONDAY BRINGING BETTER CHANCES OF SHOWERS
AND STORMS...MAINLY TO THE MOUNTAINS INTO EARLY NEXT WEEK. HIGH
PRESSURE STRENGTHENS IN THE WAKE OF THIS FEATURE RESULTING IN
DRIER AND WARMER WEATHER BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 1000 PM EDT THURSDAY...

CLOUD COVER PERSISTS ALONG THE EASTERN...UPSLOPE AREAS OF THE
MOUNTAINS FROM NORTHWEST NC TO SOUTHEAST WV. ALL INDICATIONS ARE
THAT THIS WILL CONTINUE WITH AN INTENSIFYING MARINE INVERSION
AROUND 700MB SUPPORTED BY EASTERLY LOW-LEVEL FLOW. WITH NO CHANGE
IN THE SYNOPTIC SITUATION...THIS PATTERN SHOULD PERSIST. THIS
COMBINED WITH SLOWLY INCREASING DEWPOINTS SHOULD HOLD MIN TEMPS UP
A FEW DEGREES TONIGHT IN THE WEST. LESS CLOUDS IN THE EAST SHOULD
GENERALLY SUPPORT ADVERTISED MIN TEMPS. OTHER THAN THESE CHANGES
TO THE TEMP/MIN T/SKY GRIDS...SO OTHER CHANGES WERE NEEDED AT THIS
TIME.

AS OF 300 PM EDT THURSDAY...

WITH NO MAJOR SYNOPTIC CHANGES WE WILL CONTINUE TO SEE RELATIVELY QUIET
WEATHER THROUGH THE END OF THE WORKWEEK. SURFACE HIGH PRESSURE WILL BE
SLIDING BY TO OUR NORTH AND GIVING US LIGHT ELY/NELY WINDS...WHILE A
PROGRESSIVE PATTERN FEATURING WEAK TROFING ALOFT WILL KEEP SOME SHORT
WAVE ENERGY FLOWING THROUGH THE REGION. VISIBLE SATELLITE IMAGES SHOW A
FAIRLY EXTENSIVE CU FIELD ACROSS THE REGION BUT AS OF EARLY THIS
AFTERNOON RADAR DOES NOT INDICATE ANY SHOWERS. HOWEVER...BELIEVE THERE
WILL BE ENOUGH OROGRAPHIC FORCING ALONG AND WEST OF THE BLUE RIDGE TO
GENERATE AN ISOLATED SHOWER OR TWO. WILL CONTINUE WITH SLIGHT CHANCE
POPS ACROSS THE FAR WEST WITH ANY SHOWERS DISSIPATING AFTER SUNSET.
OVERNIGHT SHOULD SEE SOME FOG FORMATION AGAIN MAINLY IN THE VALLEYS
WEST OF THE RIDGE. FRIDAY LOOKS TO FEATURE VERY SIMILAR CONDITIONS TO
WHAT WE HAVE TODAY WITH ANOTHER SLIGHT CHANCE FOR AN AFTERNOON SHOWER
WEST OF THE RIDGE.

TEMPERATURES TONIGHT AND FRIDAY WILL BE AT OR SLIGHTLY BELOW NORMAL
WITH LOWS AROUND 60S ACROSS THE PIEDMONT TO THE LOW/MID 50S WEST OF THE
RIDGE...AND HIGHS IN THE MIDDLE 80S EAST TO GENERALLY MIDDLE 70S WEST.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 245 PM EDT THURSDAY...

RIDGING BOTH SURFACE AND ALOFT WILL REMAIN DOMINANT TO START THE
WEEKEND WITH DEEPER MOISTURE AND INSTABILITY STAYING TO THE SOUTH/WEST
OF THE REGION INTO SATURDAY EVENING. THIS SEEN IN THE LATEST MODELS
INCLUDING FORECAST SOUNDINGS THAT SHOW A MUCH DRIER COLUMN ALOFT THAN
SEEN FROM YESTERDAY. THEREFORE KEPT POPS OUT FRIDAY NIGHT AND CUT BACK
TO MORE ISOLATED MOUNTAIN COVERAGE SATURDAY INTO SATURDAY EVENING WITH
SLIGHT CHANCES WEST.

UPPER TROUGH SLIDING IN FROM THE NW BY SUNDAY WILL CAUSE HEIGHTS TO
LOWER WHILE IN TURN SCOOPING UP A WEAK SHORTWAVE FROM THE SOUTH ALONG
AN AXIS OF HIGHER PWATS. THIS WAVE ALONG WITH SOME UPPER DIFFLUENCE TO
THEN SLIDE NORTH ACROSS THE MOUNTAINS SUNDAY WITH GUIDANCE SHOWING A
DECENT AMOUNT OF WEAK LIFT DESPITE SURFACE HIGH PRESSURE IN PLACE.
AGAIN THINK ENOUGH TO BRING A PERIOD OF SHOWERS IN FROM THE SOUTH LATE
SATURDAY NIGHT AND PERHAPS A CLUSTER OF SHOWERS AND STORMS ESPECIALLY
WESTERN HALF SUNDAY. COULD EVENTUALLY GO TO LOW LIKELY POPS SUNDAY
AFTERNOON BUT GIVEN TREND OF MOISTURE/UVV SLIDING FARTHER WEST WILL
HOLD WITH HIGHER CHANCE POPS...EXCEPT MAINLY SLIGHT POPS PIEDMONT.

LITTLE CHANGE TO GOING TEMPS EXCEPT TO GO A BIT COOLER WEST UNDER MORE
CLOUDS/SHOWERS SUNDAY...OTHERWISE CLEAR/PC WITH HIGHS LOW/MID 80S AND
LOWS 58-65.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 1230 PM EDT THURSDAY...

WEAKNESS ALOFT SPLITTING THROUGH THE UPPER EASTERN RIDGE WILL BE ALONG
THE APPALACHIANS SUNDAY NIGHT PRIOR TO PINCHING OFF ALLOWING A WEAK
UPPER LOW TO SHIFT TO THE SW BEFORE HEIGHTS REBUILD EARLY NEXT WEEK
NORTH OF ERIKA. THIS COMBINED WITH A PIECE OF WEAK SHORTWAVE ENERGY
SLIDING UP FROM THE SOUTH...AND HIGHER PWATS SUPPORTS BETTER CHANCES OF
CONVECTION SUNDAY EVENING/OVERNIGHT AND AGAIN MONDAY ESPECIALLY ALONG
THE MOUNTAIN CHAIN. HOWEVER GIVEN WEAK SURFACE RIDGING IN PLACE...WONT
GO MUCH HIGHER THAN MEDIUM CHANCES WEST INTO MONDAY AND KEEP MOSTLY
ISOLATED FAR EAST. PASSING OF THIS FEATURE SHOULD ALLOW RIDGING ALOFT
TO BUILD BACK INTO THE REGION FROM THE EAST...AND ENHANCED BY LIKELY
SUBSIDENCE TO THE NORTH OF ERIKA OFF THE FLORIDA/SE COAST TUESDAY INTO
WEDNESDAY. THUS EXPECTING A GRADUAL DECREASE IN POPS STARTING TUESDAY
WITH PERHAPS ONLY ISOLATED MOUNTAIN COVERAGE AT BEST BY WEDNESDAY INTO
THURSDAY. HOWEVER PENDING TRACK OF ERIKA COULD SEE ENOUGH MOISTURE
PUSHED INTO THE PIEDMONT WITHIN THE EASTERLY FETCH AHEAD OF THE SYSTEM
TO SPARK A FEW SHOWERS SOUTHEAST ON DAY7 SO KEPT MAINLY ISOLATED POPS
IN SPOTS. OTHERWISE MORE CLOUDS SUNDAY NIGHT INTO MONDAY...THEN PC TO
MOSTLY SUNNY AND MOSTLY CLEAR AT NIGHT INTO MIDWEEK FOR NOW.

TEMPS BASICALLY A PERSISTENCE FORECAST THROUGH THE PERIOD UNDER WEAK
SURFACE HIGH PRESSURE AND LITTLE CHANGE IN THE AIRMASS EXCEPT FOR
INCREASING MOISTURE. THUS RUNNING WITH MAINLY LOW 80S WEST TO MID/UPPER
80S EAST...WITH OVERALL LOWS IN THE LOW/MID 60S...CLOSER TO THE WARMER
EC MOS THROUGH THE PERIOD.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
AS OF 745 PM EDT THURSDAY...

THROUGH THE OVERNIGHT...MOST AREAS WILL REMAIN VISUAL FLIGHT RULES.
THERE WILL BE PATCHY MARGINAL VISUAL FLIGHT RULES MIST IN THE
RIVER AND MOUNTAIN VALLEYS. ALSO...PATCHY AREAS OF MARGINAL VISUAL
FLIGHT RULE CEILINGS ARE EXPECTED TO DEVELOP...MAINLY ALONG AND A
COUPLE TIERS OF COUNTIES WEST OF THE BLUE RIDGE. ANY SUB-VISUAL
FLIGHT RULE CONDITIONS ARE EXPECTED TO IMPROVE TO VISUAL FLIGHT
RULES BY 14Z/10AM FRIDAY. WINDS WILL REMAIN CALM OR LIGHT AND
VARIABLE ALSO THROUGH THIS TIME FRIDAY MORNING. BY THE LATE
MORNING INTO THE EARLY AFTERNOON A SOUTHEAST TO SOUTH 5 TO 10 KNOT
WIND IS EXPECTED.

EXTENDED AVIATION DISCUSSION...
AS OF 1230 PM EDT THURSDAY...

EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY
INCREASES BY THE WEEKEND WITH ISOLATED TO SCATTERED CONVECTION
POSSIBLE...WITH BRIEF PERIODS OF MVFR CIGS/VSBYS POSSIBLE.
TYPICAL LATE NIGHT/EARLY MORNING MVFR TO LIFR FOG THREAT AT
LWB/BCB/LYH THROUGH THE PERIOD.

&&

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

&&

$$
SYNOPSIS...JH
NEAR TERM...MBS/RAB
SHORT TERM...JH
LONG TERM...JH
AVIATION...AMS/DS/MBS


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