-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 160522
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
122 AM EDT THU MAY 16 2013

.SYNOPSIS...
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A COLD FRONT IN THE OHIO VALLEY WILL DRIFT SLOWLY SOUTH ACROSS THE
MID ATLANTIC REGION THURSDAY BEFORE REACHING THE BLUE RIDGE FRIDAY
INTO FRIDAY NIGHT. THIS FRONT WILL REMAIN IN THE AREA THROUGH THE
WEEKEND...PROVIDING THE FOCUS FOR SPOTTY SHOWER AND THUNDERSTORM
ACTIVITY...MAINLY EACH AFTERNOON AND EVENING.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 400 PM EDT WEDNESDAY...

LOOKING AT RELATIVELY CLEAR SKIES THROUGH THE REMAINDER OF THE
EVENING NOW THAT MID LEVEL CLOUDS ARE EXITING THE EAST. MAY SEE A
FEW CLOUDS POP UP ALONG THE RIDGELINES...HOWEVER THESE WILL
DIMINISH AT SUNSET AS DAYTIME HEATING ENDS. WEST WINDS REMAIN
GUSTY AND CHINOOK-LIKE THIS AFTERNOON...AND WHEN COMBINED WITH
UPPER LEVEL RIDGING ALONG THE APPALACHIAN CHAIN HAVE ALLOWED HIGHS
TODAY TO CLIMB FROM THE MID 80S TO NEAR 90 EAST...AND THE UPPER
70S TO LOW 80S ACROSS THE MOUNTAINS.

OVERNIGHT...SURFACE WINDS WILL DECREASE WITH THE LOSS OF DAYTIME
HEATING...BUT WILL AGAIN SEE WINDS BECOME SOMEWHAT GUSTY ALONG THE
RIDGES AS ANOTHER WEAK TROUGH PASSES ACROSS THE REGION...REACHING
35 TO 40 MPH AT TIMES AT THE HIGHEST PARTS OF THE NORTH CAROLINA
MOUNTAINS INTO GRAYSON COUNTY. WILL ALSO SEE HIGH CLOUDS INCREASE
THROUGH THE NIGHT AS A COLD FRONT SINKS FROM THE GREAT LAKES
TOWARD THE OHIO RIVER VALLEY...AND EXPECT TO SEE A CANOPY OF
CIRRUS ACROSS THE AREA AT SUNRISE. DESPITE UPPER LEVEL RIDGING
BREAKING DOWN OVERNIGHT...WILL STILL SEE WARM AIR BUILD IN AHEAD
OF THE APPROACHING COLD FRONT...WITH OVERNIGHT LOWS RANGING FROM
THE MID 50S TO LOW 60S MOST AREAS.

CLOUD COVER AND SHOWER ACTIVITY WILL INCREASE THROUGH THE DAY ON
THURSDAY AS THE COLD FRONT CONTINUES ITS SOUTHWARD PUSH. MAY SEE A
FEW THUNDERSTORMS DEVELOP ACROSS THE MOUNTAINS WITH AFTERNOON
HEATING...A FEW OF WHICH MAY BECOME STRONG FOR BRIEF PERIODS OF
TIME...HOWEVER BETTER INSTABILITY IS EXPECTED TO REMAIN TO THE
NORTH OF OUR AREA. INCREASED CLOUD COVER WILL HELP LIMIT
HEATING...ALTHOUGH AFTERNOON HIGHS WILL STILL BE WARM...RANGING
FROM THE UPPER 70S WEST TO THE MID/UPPER 80S EAST.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 400 PM EDT WEDNESDAY...

SIMILAR TO PAST FEW DAYS HIGHEST PROBABILITY OF PRECIPITATION WILL
LINE UP ALONG AND JUST SOUTH OF THE FRONT ACROSS THE OHIO VALLEY AND
MID ATLANTIC STATES WITH THE BEST AREAL COVERAGE IN THE AFTERNOON
AND EVENING. GFS AND NAM BROUGHT FRONT AND HIGHER CONVECTIVE
AVAILABLE POTENTIAL ENERGY INTO THE NORTHERN COUNTY WARNING AREA ON
FRIDAY THEN CLOSER TO THE VIRGINIA/NORTH CAROLINA BORDER ON
SATURDAY. 850MB BOUNDARY DOES NOT ADVANCE AS FAR SOUTH SO IT SEEMS
FORECAST AREA WILL BE IN THE BAROCLINIC ZONE. SHORT WAVE COMING OUT
OF THE SOUTHERN PLAINS AND MCS ACTIVITY MAY ALSO INFLUENCE POSITION
OF THE FRONT AND THEREFORE THE MOST LIKELY LOCATION FOR
PRECIPITATION.

LITTLE CHANGE IN AIR MASS THIS TIME FRAME. OF COURSE VARIATION IN
DAYTIME HIGH TEMPERATURES WILL BE DEPENDENT ON CLOUD COVER AND
LOCATION OF RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 100 PM EDT WEDNESDAY...

LARGE SCALE UPPER RIDGE OVER THE FORECAST AREA SATURDAY NIGHT AND
SUNDAY...BIT WITH A SHORT WAVE OVER THE SOUTHERN APPALACHIANS.
MODELS DIFFER IN THE SURFACE REFLECTION OF THE SOUTHERN WAVE.
MAIN FRONT WILL BE TO THE NORTH OF THE FORECAST AREA BUT INFLUENCE
OF THE SOUTHERN APPALACHIANS FEATURE MAY BE ENOUGH TO RESULT IN
BETTER AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS ON SUNDAY.

UPPER LOW CUTS OFF OVER THE DAKOTAS ON MONDAY. THE LOW MOVES EAST
THROUGH WEDNESDAY AND WILL PUSH A COLD FRONT INTO THE AREA BY
WEDNESDAY OR THURSDAY.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
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AS OF 105 AM EDT THURSDAY...

HIGH CONFIDENCE THAT VFR CONDITIONS WILL CONTINUE OVERNIGHT INTO
MUCH OF THURSDAY WITH JUST SOME MID/HIGH CLOUDS THROUGH EARLY
MORNING. MAY SEE SOME LOWER STRATO-CU REACH KLWB AROUND DAYBREAK
ASSOCIATED WITH CONVECTION TO THE NORTH BUT STILL APPEARS ABOVE
MVFR LEVELS FOR NOW. WEST WINDS WILL REMAIN GUSTY ALONG THE RIDGES
OVERNIGHT AND MAY SEE PERIODIC GUSTS AT KROA LINGER THRU MORNING.
OTRW SHOULD SEE LIGHTER WINDS OVERNIGHT BEFORE ONCE AGAIN GUSTING
15-25 KTS DURING THE DAY ON THURSDAY.

EXPECT A BROAD AREA OF SCTD/BKN CI/AC TO INIT THURSDAY...THEN MORE
CU AS HEATING DEVELOPS AHEAD OF A COLD FRONT SAGGING IN FROM THE
NORTH. THIS BOUNDARY SHOULD ALSO ACT TO PRODUCE SCATTERED SHOWERS
AND THUNDERSTORMS BY MID AFTERNOON AND EVENING ON THURSDAY. AT
THIS POINT APPEARS LOCATIONS ACROSS SE WVA...NAMELY KLWB...AND OUT
EAST AROUND KLYH HAVE THE BEST SHOT AT SEEING A BAND OF LATE DAY
SHRA/TSRA. THUS INCLUDED A VCTS/CB MENTION AT THESE LOCATIONS
AFTER 19Z/3PM AND A PREVAILING -SHRA MENTION AT KLWB DURING THE
EARLY EVENING. ELSW LOW CONFIDENCE IN SEEING TSRA GIVEN DEEP
WESTERLY FLOW BUT IF CONVECTION CAN ORGANIZE INTO MORE OF A LINE
FEATURE TO THE NORTH THEN ISOLATED -TSRA COULD AFFECT MUCH OF THE
REGION ESPCLY AFTER 00Z/8PM. OTRW APPEARS ANY AREAS OF MVFR IN
SHRA/TSRA SHOULD END LATE THURSDAY EVENING WITH MAINLY VFR CIGS
AND SOME LATE NIGHT MVFR VSBYS IN FOG PENDING EARLIER RAINFALL.

FRIDAY THROUGH THE WEEKEND WILL BE A PERSISTENT PATTERN OF SCATTERED
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS AS WEAK IMPULSES
PASSING ALOFT WILL OFFER UPPER LEVEL SUPPORT. PERIODS OF MVFR/IFR
ARE POSSIBLE DURING ANY TIMES OF SHOWERS AND THUNDERSTORMS.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...JH/NF
NEAR TERM...NF
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...CF/JH