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000
FXUS61 KRNK 160736
AFDRNK

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

.SYNOPSIS...
A COLD FRONT IN THE OHIO VALLEY WILL DRIFT SLOWLY SOUTH ACROSS THE
MID ATLANTIC REGION TODAY 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 DURING THE AFTERNOON AND EVENING HOURS.
&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 252 AM EDT THURSDAY...

MAIN CONCERN WITH CONVECTIVE CHANCES TODAY AS THE COLD FRONT TO THE
NORTH SAGS SOUTH TOWARD NRN VA BY THIS EVENING AND TO JUST EAST OF
THE BLUE RIDGE LATE TONIGHT. MODELS SHOWING QUITE A BIT OF DEBRIS
CLOUDS OVER THE AREA THIS MORNING IN ADVANCE OF THE BAND OF
CONVECTION NOW ALONG THE BOUNDARY IN THE OHIO VALLEY BEFORE MIXING
THINGS OUT TO SOME DEGREE THIS AFTERNOON. DEEP WESTERLY FLOW AHEAD
OF THE FRONT COMBINED WITH A WEAK IMPULSE SHEARING EAST FROM THE
UPPER SYSTEM TO THE SW LIKELY TO SLOW THE SRN PROGRESS DOWN A BIT.
HOWEVER PWATS LOOK TO INCREASE LATER THIS AFTERNOON UNDER ONLY A
WEAK RESIDUAL CAP AND MORE OF AN INVERTED V SOUNDING PROVIDED ENOUGH
HEATING TAKES SHAPE. APPEARS SOME SORT OF DIFF HEATING BOUNDARY FROM
EARLY MORNING LEFTOVER CLOUDS TO THE NORTH MAY ACT TO FIRE MORE
BANDS OF TSRA ESPCLY NW LATER ON PER WESTERLY CONVERGENCE...AND
PERHAPS ACROSS THE NORTH/NE SECTIONS GIVEN BETTER INSTABILITY IF CAN
OVERCOME DOWNSLOPING. THIS MORE IN LINE WITH THE LATEST SPC WRF AND
HIRES ARW WHICH TEND TO SPLIT PRECIP BETWEEN THESE AREAS WHERE JUST
TOO MUCH WEST WIND UNTIL THIS EVENING. THUS HAVE SLOWED POPS DOWN
SOME UNTIL LATE MORNING/EARLY AFTERNOON NORTH...AND LIMITED CHANCES
NEW RIVER VALLEY...AND JUST OFF THE BLUE RIDGE WITH LOW LIKELYS FAR
NORTH/NW...AND MAINLY CHANCE TO SLIGHTS ELSW. DECENT PROGGED DCAPE
AND UNIDIRECTIONAL WESTERLY FLOW SUPPORTIVE OF SOME WIND THREAT FROM
NORTH TO SOUTH IF A BROKEN LINE CAN ORGANIZE SO WILL MENTION WIND
POTENTIAL IN THE HWO IN SPOTS. WARM START AND WEST WIND COMPRESSION
SHOULD AGAIN ALLOW THE PIEDMONT TO PUSH 90 PROVIDED ENOUGH
INSOLATION WITH 80S ELSW EXCEPT 70S EXTREME WEST-NW FOR HIGHS.

BETTER CONVECTIVE COVERAGE MAY COME DURING THE EARLY EVENING ONCE
MIXING DECREASES ALLOWING MORE CONVERGENCE TO DEVELOP AS DEWPOINTS
RISE. MAIN FOCUS WOULD AGAIN BE OVER THE NW AND FAR EAST CLOSER TO
THE FRONT WITH MORE SCATTERED NATURE COVERAGE ELSW AS SUGGESTED BY
THE RATHER WET LOCAL RNK-WRF SOLUTION WHICH LOOKS OVERDONE.
INSTABILITY APPEARS TO QUICKLY WANE AFTER MIDNIGHT AS THE WEAK
UPPER IMPULSE EXITS SO DECREASING POPS TO MORE ISOLATED COVERAGE
LATE AFTER MAINLY CHANCE COVERAGE DURING THE EVENING. SHOULD BE A
WARM/MUGGY NIGHT WITH SOME PATCHY FOG AROUND AND TEMPS MAINLY
UPPER 50S TO LOWER 60S.
&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 400 AM EDT THURSDAY...

UNSETTLED WEATHER EXPECTED ALONG AND SOUTH OF A FRONTAL BOUNDARY
WHICH DROPS SOUTH ACROSS THE MID ATLANTIC REGION THROUGH SATURDAY
NIGHT. THIS FRONT ENTERS NORTHERN PORTIONS OF OUR AREA FRIDAY AND
PUSHES TO THE VIRGINIA/NORTH CAROLINA BORDER ON SATURDAY.

CUT BACK POPS INITIALLY FRIDAY MORNING USING A BLEND OF THE GFS/NAM
WITH SCATTERED CONVECTION MAINLY IN THE WEST WITH LIGHTER CHANCES IN
THE EAST. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS
THE ENTIRE REGION FRIDAY AFTERNOON INTO FRIDAY EVENING. MLCAPE
VALUES ON FRIDAY MAY CLIMB TO 500 TO 1000 J/KG...WITH 0-6KM SHEAR
WEAK AROUND 20 KTS. LOWERED HIGHS A FEW DEGREES FRIDAY WITH VALUES
FROM THE LOWER 70S IN THE WEST TO THE LOWER 80S IN THE EAST. ALLOWED
FOR SOME SHOWERS WITH SHORTWAVE MAINLY ACROSS THE NORTH FRIDAY
NIGHT. FRIDAY NIGHT WILL BE MILD WITH READINGS FROM THE LOWER 50S IN
THE MOUNTAINS TO THE LOWER 60S IN THE EAST. INCREASED POPS TO LIKELY
ON SATURDAY WITH NAM...GFS AND ECMWF ALL SUPPORTING THUNDERSTORMS.
ROBUST CAPES OFF THE GFS FROM 1 TO 3K J/KG LEAD TO POTENTIAL FOR
STRONGER STORMS IN SOUTHSIDE. A PULSE TYPE SEVERE STORM MAY BE
POSSIBLE WITH WIND AND RAIN. TRAINING OF ECHOES COULD RESULT IN
FLOODING PROBLEMS WITH HIGHER PWAT VALUES. WENT WITH COOLER HIGHS
FOR SATURDAY IN THE 70S WITH BETTER COVERAGE AND THICK CLOUDS. HELD
ON TO CHANCE OF SHOWERS SATURDAY NIGHT...WITH LOWS FROM THE MID 50S
IN THE MOUNTAINS TO THE LOWER 60S IN THE PIEDMONT.
&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 100 PM EDT WEDNESDAY...

LARGE SCALE UPPER RIDGE OVER THE FORECAST AREA 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 /08Z THURSDAY THROUGH MONDAY/...
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.

&&

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

&&

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