-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 170821
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
421 AM EDT FRI MAY 17 2013

.SYNOPSIS...
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A COLD FRONT WILL CONTINUE TO SINK SOUTH TOWARD THE REGION
TODAY BEFORE SETTLING ACROSS THE EASTERN HALF OF THE FORECAST
AREA BY THIS EVENING. THE FRONT WILL STALL OVER NORTH CAROLINA
OVERNIGHT INTO SATURDAY NIGHT BEFORE LIFTING BACK NORTHEAST AS A
WARM FRONT BY EARLY NEXT WEEK. A WEAK UPPER LEVEL DISTURBANCE
WILL RIDE EAST ALONG THE FRONT ENHANCING THE THREAT FOR SHOWERS
AND THUNDERSTORMS ESPECIALLY OVER THE WEEKEND.
-- End Changed Discussion --
&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 255 AM EDT FRIDAY...

CONVECTIVE COVERAGE AGAIN THE MAIN CONCERN TODAY INTO
TONIGHT AS THE WEAK COLD FRONT TO THE NORTH DRIFTS SOUTH REACHING
THE BLUE RIDGE THIS EVENING. FORCING ALOFT RATHER WEAK AS WILL BE
IN BETWEEN THE OUTFLOW BAND THAT PASSED TO THE SE EARLIER AND
BETTER LIFT WITH THE RESIDUAL UPPER LOW WELL TO THE SW. HOWEVER
MODELS INDIDCATE DECENT LOW LEVEL CONVERGENCE STARTING OVER THE SW
EARLY ON PER SOUTH/SE FLOW AHEAD OF THE BOUNDARY AND IN AN AREA OF
HIGHER THETA-E. THIS SIMILAR TO THE LASTEST SPC AND HIGH RES ARW
MODELS BUT OVERALL GUIDANCE CONSENSUS LACKING PER SPREAD IN
GFS/NAM OUTPUT THIS AFTERNOON. BEST INSTABILITY APPEARS OVER THE
SOUTHERN AND SW AHEAD OF THE FRONT SO BOOSTED POPS FOR A PERIOD OF
LOW END CATEGORICAL ALONG THE BLUE RIDGE...WITH SOME OF THIS
COVERAGE SPILLING EAST AND GRADUALLY UNZIPPING IN CONJUNCTION WITH
THE SW MOVING BOUNDARY. THIS SUPPORTS KEEPING LIKELY POPS ELSW
THIS AFTERNOON ALTHOUGH SEVERE POTENTIAL LOOKS TO BE MORE PULSE
NATURE PER LESS DRY AIR ALOFT AND SMALLER DCAPES WITH MORE SLOWER
MOVING SHRA/TSRA LIKELY. KEPT HIGH TEMPS IN BETWEEN MET/MAV MOS AS
EXPECT A DECENT PERIOD OF HEATING AFTER EARLY MID DECK ERODES AND
BEFORE COVERAGE OF SHOWERS INCREASES.

LINGERING INSTABILITY WILL GET SHOVED BACK TO ALONG AND
WEST OF THE BLUE RIDGE OVERNIGHT AS THE FRONT PASSES INTO THE FAR
SOUTHERN AREAS BY DAYBREAK. WILL HAVE CONTINUED HIGH POPS DURING
THE EVENING PENDING WHERE MORE ORGANIZED TSRA TAKES SHAPE...THEN
DECREASING BY MIDNIGHT ESPCLY EAST IN THE WAKE OF THE BOUNDARY.
WESTERN AREAS MAY SEE SHRA INCREASE AGAIN LATE AHEAD OF THE
APPROACHING UPPER LOW BUT IFFY...SO ONLY KEEPING CHANCE POPS GOING
THERE. OTRW MOSTLY CLOUDY AND MUGGY WITH LOWS IN THE 50S TO LOWER
60S.
-- End Changed Discussion --
&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
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AS OF 349 AM EDT FRIDAY...

BOUNDARY JUST TO OUR NORTH WILL SINK SOUTH OVER THE WEEKEND...IN A
BACKDOOR FASHION AS HIGH PRESSURE SLIPS OVER NEW ENGLAND. THIS
BOUNDARY IN COMBINATION WITH SOUTHEAST UPSLOPE WINDS AGAINST THE
BLUE RIDGE...AND AN UPPER WAVE MOVING ACROSS TN...SHOULD PRODUCE A
SOMEWHAT COOL AND DAMP WEEKEND. SUNDAY APPEARS TO BE THE WETTEST DAY
WITH THE UPPER DISTURBANCE RIGHT ON OUR DOORSTEP THEN MOVING INTO
VIRGINIA DURING THE DAY. PWATS START OUT FAIR SATURDAY BUT REALLY
INCREASE SUNDAY TO 1/5" IN SPOTS. WITH DEAD FLOW ALOFT AND WEAK MBE
VELOCITIES...STORMS MAY BE SLOW MOVING AND LATCHED ONTO THE BLUE
RIDGE...POSSIBLY LEADING TO SOME WATER PROBLEMS. INSTABILITY ISN`T
THE STRONGEST...AS SUNSHINE WILL BE LIMITED BY ABUNDANT CLOUDS...BUT
COOLING ALOFT THANKS TO THE UPPER WAVE COULD LEAD TO A MINIMAL
STRONG STORM THREAT...ALTHOUGH NOT TOO THRILLED ABOUT SEVERE
WEATHER. SURFACE WINDS VEER ON MONDAY...MORE OF A S TO SSW WIND AS
THE SHORTWAVE MOVES EAST...THUS ONLY CHC POPS AND WARMER AFTERNOON
TEMPS...ESPECIALLY WEST OF THE BLUE RIDGE WITH LESS CLOUDS.
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&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
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AS OF 415 AM EDT FRIDAY...

FRONT LIFTS TO OUR NORTH TUESDAY WHICH SHOULD BE OUR BEST BET TO
AVOID PCPN GIVEN SOME SHORT WAVE RIDGING...THOUGH LOCAL MOUNTAIN
EFFECTS MAY STILL COOK UP SOME ISOLATED CONVECTION. NEXT FRONT
WILL BE APPROACHING FROM THE WEST ON WEDNESDAY SO EXPECT
INCREASING CHC OF THUNDER AS WE GET INTO WEDNESDAY AFTERNOON. THE
FRONT WANTS TO PUSH THROUGH AND CLEAR THE AREA FOR
THURSDAY...THOUGH WAVE DEVELOPMENT ON THE FRONT MAY SLOW IT DOWN
AND DO NOT HAVE A GREAT DEAL OF CONFIDENCE WITH FRONTAL POSITION
THIS FAR OUT WITH MODELS STILL SORTING THINGS OUT.
-- End Changed Discussion --
&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AS OF 104 AM EDT FRIDAY...

EXPECTING OVERALL VFR OUTSIDE OF THE NW VALLEYS WHERE WILL SEE
AREAS OF IFR/LIFR IN FOG STRATUS DEVELOP THROUGH EARLY FRIDAY
MORNING. COULD SEE KLWB EVEN LOWER TO VLIFR BY DAYBREAK. OTRW
MAINLY SCTD/BKN HIGH/MID CLOUDS INTO EARLY FRIDAY MORNING WITH
SPOTS OF LOWER VSBYS AND PERHAPS SOME STRATUS TAKING SHAPE AROUND
KLYH AND KBCB THAT WERE IN PROXIMITY TO EVENING SHRA/TSRA.

WEAK BACKDOOR COLD FRONT TO THE NORTH WILL DRIFT SOUTH/SW ON
FRIDAY BEFORE STALLING NEAR THE BLUE RIDGE LATE IN THE DAY. THIS
COMBINED WITH INCREASING MOISTURE...HEATING AND OROGRAPHICS WILL
PROVIDE THE FOCUS FOR ADDED SHRA/TSRA BY EARLY AFTERNOON WITH SOME
OF THIS COVERAGE LINGERING AND SPREADING NE BY EVENING. APPEARS
THE SW TIER OF THE AREA WILL HAVE THE INITIAL BEST SHOT OF SEEING
CONVECTION BUT CANT RULE OUT AT LEAST CLUSTERS OF STORMS ACROSS
THE REGION BY LATE IN THE DAY. THUS WILL MAINTAIN THE GOING
VCSH/VCTS MENTION FROM KBCB/KROA WESTWARD EARLY FRIDAY AFTERNOON
AND THEN INCLUDE A PREVAILING MVFR MENTION OF TSRA AT MOST SITES
MAINLY DURING THE 19-00Z/2-8PM PERIOD. THINK EASTERN LOCATIONS
SUCH AS KLYH MAY SEE LESS OF A THREAT EARLY ON SO DELAYED
INCLUSION OF CONVECTION A FEW HOURS THERE. EXPECT COVERAGE TO
DIMINISH WITH LOSS OF HEATING FRIDAY EVENING BUT STILL ENOUGH
INSTABILITY AROUND ESPCLY SOUTH/SW SECTIONS TO KEEP -SHRA GOING A
WHILE LONGER INTO THE EARLY OVERNIGHT.

THE FRONT WILL LINGER ACROSS THE AREA THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK...RESULTING IN A PERSISTENT PATTERN OF SCATTERED
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS AS WEAK IMPULSES
PASS ACROSS THE FRONTAL BOUNDARY...OFFERING UPPER LEVEL SUPPORT.
PERIODS OF MVFR/IFR ARE EXPECTED TO BE ASSOCIATED WITH THE
SHOWER AND THUNDERSTORM ACTIVITY. PATCHY EARLY MORNING FOG CAN
ALSO BE EXPECTED.
&&

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

&&

$$
SYNOPSIS...JH/NF
NEAR TERM...JH
SHORT TERM...KM
LONG TERM...AMS/MBS
AVIATION...JH/PM