-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 221856
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
256 PM EDT TUE JUL 22 2014

.SYNOPSIS...
UPPER TROUGH OVER THE GULF COAST STATES SHIFTS WEST THROUGH
WEDNESDAY LEAVING A RESIDUAL WEAK BOUNDARY AND LOW LEVEL MOISTURE
OVER THE AREA INTO MID WEEK. A COLD FRONT WILL BE ARRIVING
THURSDAY FROM THE NORTHWEST...THEN EXITING BY THURSDAY NIGHT. HIGH
PRESSURE BUILDS IN ON FRIDAY.
&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
AS OF 205 PM EDT TUESDAY...

WEAK SURFACE RIDGE ACROSS THE REGION THIS AFTERNOON COMBINING WITH
LIMITED INSTABILITY AND LACK OF FORCING TO KEEP OVERALL CONVECTIVE
COVERAGE AT A MINIMUM ATTM. BEST LOW LEVEL THETA-E ALSO SHOWING UP
JUST SOUTH OF THE REGION WHICH COULD STILL INTERACT WITH RESIDUAL
OUTFLOW TO PRODUCE A BIT BETTER COVERAGE OF MAINLY SHRA ACROSS THE
SOUTH/SE INTO THIS EVENING. ELSW APPEARS ANY LATE DAY COVERAGE
WILL BE QUITE ISOLATED AND PERHAPS ONLY OVER THE FAR NW ON THE
EDGE OF THE CURRENT CLOUD SHIELD WHERE MORE HEATING HAS OCCURRED.
THUS MAINTAINING THE HIGHEST POPS FAR SOUTH WITH MID TO LOW
CHANCES ELSW INTO EARLY EVENING.

UPPER LOW WELL TO THE SW WILL CONTINUE TO SHIFT WEST OVERNIGHT
LEAVING THE REGION IN A MOIST ENVIRONMENT BUT WITH LACK OF MUCH
SUPPORT FOR ADDED SHRA. IN ADDITION THE LOW LEVEL WEDGE WILL BE
BREAKING DOWN AS THE SURFACE HIGH SHIFTS ACROSS AND TO THE SOUTH
ALLOWING THE FLOW TO TURN LIGHT WESTERLY AFTER MIDNIGHT. THIS
SHOULD LIMIT MUCH -DZ POTENTIAL WITH ONLY SOME WEAK LEFTOVER
CONVERGENCE WESTERN SLOPES LATE TONIGHT. APPEARS MAY BE ABLE TO GO
DRY AFTER THIS EVENING BUT WITH DEEPER MOISTURE STILL OVER THE SW
LEFT IN A TOKEN POP THERE OVERNIGHT. LOWS AGAIN WARM/MUGGY WITH
MOST IN THE 65-72 RANGE GIVEN HIGH DEWPOINTS AND PATCHY FOG
AROUND.

NEXT STRONG 5H TROF AND ASSOCIATED COLD FRONT WILL BE APPROACHING
ON WED AS HIGH PRESSURE SHIFTS FARTHER SOUTH ALLOWING DEEPENING
WESTERLY FLOW AND A SUBSEQUENT LEE TROF WELL EAST OF THE BLUE
RIDGE. MODELS SPARK MOST AFTERNOON CONVECTION ALONG THE SOUTHERN
BLUE RIDGE GIVEN THE WEAK BOUNDARY LAYER SW FLOW AND BETTER
DIFFERENTIAL HEATING BUT STILL IFFY GIVEN WESTERLY FLOW ALOFT AND
ONLY FAINT LIFT. ELSW APPEARS RATHER ISOLATED DESPITE LINGERING
MOISTURE GIVEN DRY AIR ALOFT AND DOWNSLOPING WEST WINDS ACROSS
THE EAST SO KEEPING SHOTGUN CHANCE POPS. HOWEVER THE UPSTREAM PRE-
FRONTAL BAND OF TSRA WILL LIKELY BE NEARING THE NW SLOPES LATE.
THUS KEPT IN LOW LIKELYS EXTREME WEST...BUT MOSTLY TOWARD SUNSET
AT THIS POINT. SOME ISOLATED SEVERE POSSIBLE IF PULSE STORMS
ORGANIZE MORE EARLY...AND UPSTREAM ACTIVITY MOVES INTO THE WEST IN
MORE OF A LINE FEATURE...ALTHOUGH THIS MAY BE AFTER INSTABILITY IS
STARTING TO FADE. OTRW SHOULD SEE CLOUDS BREAK QUICKER UNDER THE
WESTERLY FLOW ALLOWING INSOLATION AND 85H TEMPS AROUND +20C TO AID
WEAK COMPRESSION IN PUSHING HIGHS INTO THE 80S WEST AND 90-95
EAST.
-- End Changed Discussion --
&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 345 AM EDT TUESDAY...

WILL START WEDNESDAY MORNING OFF WITH ONLY ISOLATED SHOWER ACTIVITY
UNDER LIGHT SOUTHWEST TO WESTERLY WIND FLOW AS A SURFACE TROUGH
DEVELOPS EAST OF THE BLUE RIDGE. COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL INCREASE DURING THE AFTERNOON HOWEVER AS A COLD
FRONT APPROACHES FROM THE OHIO RIVER VALLEY. BEST INSTABILITY WILL
BE FOUND ACROSS THE MOUNTAINS...WHERE CAPES WILL REACH INTO THE 1500-
2000 J/KG RANGE BY EARLY EVENING AS AFTERNOON HIGHS REACH INTO THE
MID 80S WEST TO THE LOW 90S EAST. BELIEVE SHOWERS AND STORMS WILL
DEVELOP ACROSS THE MOUNTAINS BY EARLY AFTERNOON AS PULSE HIT AND
MISS ACTIVITY...POSSIBLY MERGING INTO MORE ORGANIZED LINE SEGMENTS
ACROSS THE PIEDMONT DURING THE EVENING. WITH STRONG HEATING AND
ABUNDANT DRY AIR IN THE MID LEVELS...EXPECT A FEW STORMS TO BECOME
SEVERE DURING LATE AFTERNOON AND EVENING...PRODUCING STRONG WINDS AS
THE MAIN THREAT...IN ADDITION TO HAIL AND LOCALLY HEAVY RAIN. STORMS
WILL WEAK DURING LATE EVENING...BUT EXPECT WE WILL STILL HAVE
SHOWERS PASSING ACROSS THE AREA WEDNESDAY NIGHT AS THE COLD FRONT
ARRIVES ON OUR DOORSTEP.

MODELS ARE IN DECENT AGREEMENT THAT THE COLD FRONT WILL ENTER OUR
SOUTHEAST WEST VIRGINIA COUNTIES LATE MORNING/EARLY AFTERNOON ON
THURSDAY...AND CONTINUE EAST THROUGH THE DAY. HOWEVER...WITH AN
UPPER LEVEL TROUGH SHIFTING EAST OF OUR AREA AND INCREASED CLOUD
COVER TO LIMIT HEATING...ATMOSPHERIC INSTABILITY WILL NOT BE AS
INTENSE. EXPECT MORE IN THE WAY OF SHOWER ACTIVITY ON THURSDAY WITH
ONLY WIDELY SCATTERED THUNDERSTORMS IN THE MIX...MAINLY ACROSS THE
PIEDMONT. HIGHS WILL REACH INTO THE UPPER 70S ACROSS THE
MOUNTAINS...WHILE WE MAY TOUCH 90 ACROSS THE SOUTHSIDE BEFORE THE
COLD FRONT MOVES ACROSS.

WEAK HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...AND WILL BE IN
CONTROL OF OUR WEATHER PATTERN FOR FRIDAY. AS SUCH...EXPECT A LIGHT
NORTHERLY FLOW THAT WILL CARRY DRIER AIR INTO THE REGION FROM THE
GREAT LAKES. AFTERNOON HIGHS WILL VARY FROM THE MID 70S WEST TO THE
MID 80S EAST. MAY SEE THUNDERSTORMS RETURN TO THE AREA LATE FRIDAY
NIGHT AS WINDS ALOFT SHIFT NORTHWESTERLY...ALLOWING UPPER LEVEL
DISTURBANCES TO APPROACH THE AREA FROM THE MIDWEST.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 445 PM EDT MONDAY...


FOR THE WEEKEND AND INTO EARLY NEXT WEEK...THE AREA REMAINS
VULNERABLE TO NW FLOW DISTURBANCES TRACKING AROUND THE LARGE
WESTERN/CENTRAL CONUS UPPER RIDGE. THERE ARE SEVERAL SUCH STRONG
DISTURBANCES NOTED IN THE MODELS DURING THIS TIME FRAME...THE MOST
NOTABLE ON SUN...THAT COULD BRING THUNDERSTORMS BACK INTO THE
AREA. HAVE RETAINED EXISTING CHC POPS THAT WERE ADVERTISED WITH
EARLIER FORECAST PACKAGES...BUT CLEARLY THESE COULD POTENTIALLY
BECOME LIKELY AT SOME POINT AS THE DEVELOPMENT OF AN UPSTREAM MCS
BECOMES MORE APPARENT. BY EARLY THE FOLLOWING WEEK...MODELS IN
GOOD AGREEMENT ON THE UPPER TROUGH REAMPLIFYING ACROSS THE EASTERN
CONUS...WHICH SHOULD KEEP CONDITIONS UNSETTLED WITH NEAR TO
SLIGHTLY BELOW NORMAL TEMPERATURES WHILE THE EXTREME HEAT REMAINS
WELL TO OUR WEST AND WELL AWAY FROM OUR PART OF THE COUNTRY.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT TUESDAY...

HEATING OF LOW LEVEL MOISTURE HAS RESULTED IN AN EXPANSIVE CU
FIELD ACROSS THE REGION THIS AFTERNOON WITH BASES EXPECTED TO RISE
TO MOSTLY VFR LEVELS IN THE NEXT COUPLE OF HOURS. HOWEVER SPOTTY
CONVECTION DEVELOPING CLOSE TO KDAN MAY KEEP THEM MORE IN THE HIGH
END MVFR LEVEL RANGE AS WELL AS KLYH WHERE PERIODS OF MVFR LIKELY.
SOME ADDED SHRA OR TSRA MAY POP ALONG THE BLUE RIDGE BY MID OR
LATE AFTERNOON SO LEAVING IN A VCSH/VCTS MENTION MAINLY WHERE
ALREADY ONGOING WHICH EXCLUDES KBLF/KLYH FOR NOW. OTRW LOOKING AT
OVERALL CLOUD BASES OF 3-5K FT THIS AFTERNOON/EARLY EVENING WITH
SE WINDS LESS THAN 10 KTS.

MOST CONVECTION WEAKENS/SUBSIDES SHORTLY AFTER SUNSET WITH ONLY
ISOLATED SHRA/TSRA PERHAPS LINGERING MOUNTAINS BEFORE MIDNIGHT. FOG
FORMATION LIKELY LATE EVENING INTO OVERNIGHT BUT GIVEN LESS OF A
LOW LEVEL WEDGE AND LIGHT WEST WINDS NOT EXPECTING THE OVERALL
MORE WIDESPREAD IFR/LIFR CONDITIONS SEEN THE LAST FEW NIGHTS.
THINK THE VALLEY LOCATIONS SUCH AS KBCB AND KLWB HAVE THE BEST
CHANCE OF SEEING IFR/LIFR CONDITIONS WITH IFR TO MVFR AT KLYH/KDAN
BY EARLY WEDNESDAY MORNING.

LOW LEVEL FLOW TURNS MORE WESTERLY AHEAD OF AN UPSTREAM COLD FRONT
ON WEDNESDAY WHICH SHOULD ALLOW LOW CLOUDS/FOG TO SCOUR OUT A BIT
SOONER WEDNESDAY MORNING. THUS EXPECTING A RETURN TO VFR AT ALL
LOCATIONS BY MID OR LATE MORNING WEDNESDAY. HOWEVER HEATING WILL
AGAIN LEAD TO ADDED SHRA/TSRA DEVELOPMENT ESPCLY ALONG THE
SOUTHERN BLUE RIDGE DURING THE AFTERNOON AND ACROSS THE SE WEST VA
SITES BY EARLY EVENING. THIS MAY RESULT IN INCREASING PERIODIC
MVFR CONDITIONS OVER THE MOUNTAINS BUT MOSTLY VFR OUT EAST.

EXTENDED AVIATION DISCUSSION...

NEXT NORTHERN STREAM UPPER TROUGH AND ITS ASSOCIATED COLD FRONT
WILL APPROACH WEDNESDAY NIGHT AND WORK THROUGH THE REGION ON
THURSDAY. THIS WILL BRING THE BEST CHANCES OF MORE WIDESPREAD
SHOWERS TO THE MOUNTAINS AND PERHAPS SOME DEEPER CONVECTION EAST
OF THE BLUE RIDGE PENDING TIMING OF THE BOUNDARY THURSDAY
AFTERNOON. AIRMASS WILL DRY OUT BEHIND THE FRONT GOING INTO FRIDAY-
SATURDAY. OVERALL EXPECT SUB VFR AT TIMES THURSDAY WITH SHRA/TSRA
AND MAYBE SOME FOG THU NIGHT...FOLLOWED BY VFR FRI- SAT OUTSIDE OF
ANY VALLEY FOG AT KLWB/KBCB EACH MORNING.

&&

.EQUIPMENT...
-- Changed Discussion --
AS OF 245 PM EDT TUESDAY...

KFCX RADAR REMAINS DOWN. HOWEVER TECHNICIANS ARE CURRENTLY WORKING
ON THE PROBLEM AND WE MAY SEE A RETURN TO SERVICE LATER THIS
AFTERNOON.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...JH/WP
NEAR TERM...JH
SHORT TERM...NF
LONG TERM...PM/RAB
AVIATION...JH/WP
EQUIPMENT...JH/WP