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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 171733
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
133 PM EDT MON JUN 17 2013

.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTH TOWARD THE REGION TODAY BRINGING
SCATTERED SHOWERS AND THUNDERSTORMS TO THE AREA. THE FRONT WILL
STALL SOUTH OF THE REGION LATER TONIGHT AWAITING YET ANOTHER COLD
FRONT TUESDAY. THIS COMBINED WITH ANOTHER WEAK UPPER DISTURBANCE
SHOULD BRING ADDITIONAL SHOWERS...AND POSSIBLE STORMS BACK TO THE
REGION TUESDAY INTO TUESDAY NIGHT BEFORE WEAK HIGH PRESSURE BUILDS
ACROSS THE AREA THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 125 PM EDT MONDAY...

INCREASED POPS ALONG THE BLUE RIDGE ESPECIALLY THE SOUTHERN BLUE
RIDGE THIS AFTERNOON INTO TONIGHT WHERE CONVECTION IS DEVELOPING
WHERE THE BEST MOISTURE CONVERGENCING ENHANCING ACTIVITY.
MODIFIED TEMPERATURES ACCORDING TO LATEST OBS AND MODEL TREND FOR
THIS AFTERNOON.

AS OF 930 AM EDT MONDAY...

ADJUSTED POPS ACCORDING TO LAST RADAR TRENDS WITH HIGH POPS
IN THE EAST AND LOWER CHANCES IN THE NORTHWEST FOR THIS MORNING.
WEAK FRONTAL BOUNDARY WILL CONTINUE TO DROP SOUTH TODAY AS
A COUPLE OF SHORTWAVES SPARK PERIODS OF SHOWERS AND THUNDERSTORMS.
THIS MORNING 8AM/12Z RNK SOUNDING LOOKED QUITE MOIST WITH A PWAT
AT 1.40 INCH AND WEST TO SOUTHWEST FLOW. WITH HEATING STILL EXPECT
DEVELOPMENT ALONG THE BLUE RIDGE ESPECIALLY SOUTHERN BLUE RIDGE
THIS AFTERNOON INTO TONIGHT. SOME ISOLATED PULSE SEVERE POSSIBLE
GIVEN DECENT LAPSES WITH HEATING WHILE OVERALL WEAK WINDS ALOFT
AND WARMING SHOULD HINDER SEVERE CONVECTION POTENTIAL. MODIFIED
TEMPERATURES AND DEW POINTS WITH OBS AND LATEST MODEL TRENDS. WILL
MAKE ADDITIONAL ISC GRIDS ADJUSTMENTS AS THE DAY PROGRESSES.


AS OF 315 AM EDT MONDAY...

WEAK FRONT TO THE NORTH WILL CONTINUE TO DRIFT SLOWLY SOUTH
TOWARD THE AREA TODAY AS SHORTWAVE ENERGY CURRENTLY DRIVING
SHRA/TSRA ATTM HEADS OFF TO THE SE LATER TODAY. THIS SHOULD
GRADUALLY SHIFT THE FOCUS FOR ADDED CONVECTION TO THE SOUTH
AND SE THIS AFTERNOON AFTER EARLY MORNING COVERAGE ACROSS THE
CENTRAL/SOUTHERN SECTIONS. MAY ALSO SEE A FEW SHOWERS OR STORMS
DEVELOP ALONG THE SOUTHERN BLUE RIDGE THIS AFTERNOON PENDING
HEATING AND DEGREE OF LIGHT WEST/SW FLOW AS SUPPORTED BY THE
LATEST SPC WRF. OTRW TREND WILL BE FOR LOWERING THETA-E FROM
NW TO SE DURING THE DAY WITH PROGGED CAPES PERHAPS AROUND 1500
J/KG PIEDMONT AND LESS TO THE NORTH/WEST. THUS HAVE CUT BACK POPS
TO LOW/SLIGHT CHANCE NW LATER...AND LIMITED ANY LIKELYS TO THE
EXTREME SOUTH/SW WHICH MAY BE GENEROUS GIVEN DEGREE OF DRYING
ALOFT. SOME ISOLATED PULSE SEVERE POSSIBLE GIVEN DECENT LAPSES
WITH HEATING WHILE OVERALL WEAK WINDS ALOFT AND WARMING SHOULD
KEEP ORGANIZED SEVERE TO A MINIMUM. OTRW QUITE WARM AND MUGGY
AGAIN THIS AFTERNOON ALTHOUGH LEANED CLOSER TO THE SLIGHTLY
COOLER MET MOS PER EARLY CLOUDS AND SCTD SHRA.

TRAJECTORIES TURN MORE WEST OR NW OVERNIGHT NEAR THE FRONT WITH
FORECAST SOUNDINGS SHOWING QUITE A BIT OF ADDED DRYING ALOFT AND
OVERALL WEAK SINKING MOTION AHEAD OF THE NEXT MID LEVEL WAVE
OFF TO THE WEST. MOST GUIDANCE NOW BASICALLY DRY OVERNIGHT WITH
MAINLY CLOUDS AROUND BUT LITTLE LIFT AS MOISTURE SHALLOWS OUT
UNDER WEAK LOW LEVEL RIDGING. HOWEVER GIVEN POTENTIAL FOR MODELS
TO DRY THINGS OUT TOO FAST...WHILE BEING SLOW WITH RETURN MOISTURE
ADVECTION...WILL LEAVE IN SOME SHRA...BUT CUT LIKELY POPS BACK TO
CHANCE WEST...AND GO WITH MAINLY 20ISH COVERAGE EAST. IF MORE
BREAKS DEVELOP THEN MORE IN THE WAY OF FOG LIKELY WITH TEMPS
CLOSER TO THE COOLER MAV ESPCLY VALLEYS.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 400 AM EDT MONDAY...

MODELS GENERALLY GOOD AGREEMENT THROUGH WED AS SERIES OF SHORT WAVES
EMBEDDED WITHIN LARGER SCALE BROAD EASTERN U.S. TROUGH CONTINUE TO
KEEP AN UNSETTLED WEATHER PATTERN ACROSS THE REGION. A QUASI-
STATIONARY FRONT SHOULD BE LOCATED FROM NORTH GA ACROSS SOUTHERN NC
OR NORTHERN SC IN THIS TIME FRAME AWAITING AWAITING A
STRONGER...TRAILING SHORT WAVE...LOCATED EARLY TUESDAY ACROSS THE
UPPER MID-WEST...TO FINALLY GIVE THE FRONT A PUSH TO THE SE AND
SWEEP THE DEEPER MOISTURE EASTWARD OUT OF THE AREA. THERE IS NO
QUESTION THAT THE TUE-EARLY WED PERIOD WILL BE WET WITH LIKELY TO
CATEGORICAL POPS ACROSS THE REGION...ESPECIALLY THE SOUTHERN
HALF...BUT BIGGER QUESTIONS WITH RESPECT TO QPF AND SEVERE POTENTIAL
REMAIN. WITH RESPECT TO THE LATER...SEVERE THREAT SHOULD BE LITTLE
TO NONE DURING THIS TIME FRAME AS MOST IF NOT ALL OF THE CWA
REMAINS ON THE NORTH...COOLER...MORE STABLE SIDE OF THE FRONT. MOST
PRECIPITATION SHOULD BE IN THE FORM OF OVERRUNNING WITH MINIMAL
DYNAMICS. CERTAINLY CANNOT RULE OUT ISOLD TSRA DURING THE WARMER
HOURS OF THE DAY...ESPECIALLY NC AND THE PIEDMONT REGION...BUT THERE
IS NO DYNAMIC SUPPORT AND LIMITED THERMODYNAMIC SUPPORT FOR ANYTHING
SEVERE. ON THE OTHER HAND...QPF IS A BIGGER ISSUE AND A MORE
DIFFICULT QUESTION TO ANSWER AS WELL. OVERALL...MODEL AND WPC QPF IN
THE 0.5 TO 1.0 INCH RANGE ACROSS THE NORTH AND 1.0 TO 1.5 INCH RANGE
SOUTH...WHICH IS CONSISTENT WITH THINKING NOTED ABOVE.
NORMALLY...THESE AMOUNTS WOULD NOT BE ANY CONCERN...BUT GIVEN THE
TOTALLY SATURATED GROUND ACROSS THE AREA...THERE COULD BE SOME LOCAL
ISSUES IF ANY EMBEDDED CONVECTION PRODUCES HEAVY RAINFALL OVER A
SHORT TIME PERIOD. WILL CONTINUE WITH HEAVY RAIN WORDING IN
HWO...BUT NOT ENOUGH WIDESPREAD CONCERN AT THIS POINT FOR ANY FFA.

THE MAIN SHORT WAVE WILL EXIT THE REGION EARLY WED. DRIER AIR WILL
WORK ITS WAY INTO THE REGION...FIRST FROM THE NORTH...AND THEN FROM
THE NORTHEAST WED...LIMITING POPS TO THE FAR SE PART OF THE CWA FOR
THE MOST PART. CLOUDS WILL LINGER...HOWEVER...GIVEN NE SFC FLOW ON
THE BACK SIDE OF THE UPPER SYSTEM. FOR THU...THE UPPER RIDGE
ATTEMPTS TO BUILD INTO THE EASTERN U.S. IN A WEAK FASHION. 850MB
TEMPS BEGIN TO WARM SLIGHTLY AS WELL...BUT OVERALL THE MID-ATLANTIC
REGION REMAINS ON THE SW PERIPHERY OF THE BROAD NE U.S. UPPER LOW.
SFC WIND CONVERGENCE IS EVIDENT ALONG THE ALLEGHANYS AND THIS
COMBINED WITH INCREASED INSOLATION AND DIFFERENTIAL HEATING SHOULD
YIELD INCREASED AFTERNOON PULSE THUNDERSTORMS...A FEW OF WHICH COULD
BECOME STRONG.

TEMPERATURES WILL REMAIN MOSTLY BELOW SEASONAL NORMALS THROUGH WED.
CLOUDS AND PCPN WILL HOLD TEMPS IN THE 70S MANY AREAS TUE...AND
HIGHER ELEVATIONS MAY EVEN STAY IN THE 60S. WED WILL REMAIN BELOW
NORMAL WITH NE SFC WINDS. BY THU...INCREASED 850MB TEMPS AND BETTER
INSOLATION SHOULD ALLOW TEMPERATURES TO WARM BACK INTO THE 80S
PIEDMONT AND 70S MOUNTAINS.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 1245 PM EDT SUNDAY...

MODELS THIS PERIOD KEEPING A BROAD TROUGH INTO THE EAST BUT EDGING
EAST BY FRIDAY AS HIGH PRESSURE EXPANDS FROM TEXAS TO JUST WEST OF
US. SFC HIGH PRESSURE STAYS JUST NORTHEAST OF US AND KEEPS OUR
REGION IN THE LIGHT EAST TO SOUTH FLOW AS A FRONTAL BOUNDARY STALLS
AND WEAKENS SOUTH OF US MIDWEEK. THIS WILL SET UP A PATTERN OF
INVERTED TROUGHINESS ACROSS THE MTNS THRU FRIDAY WHERE BEST THREAT
OF SHOWERS EXISTS AND PERHAPS SOME THUNDERSTORMS AS WELL. NO CLEAR
DEFINITIVE SHORTWAVE BUT WILL SEE SOME WEAK ONES HELP TRIGGER
CONVECTION. AT THIS TIME KEPT POPS LOW CHANCE IN THE WEST TO SLIGHT
CHANCE ACROSS THE MIDDLE OF THE CWA/BLUE RIDGE AND LITTLE TO NONE IN
THE EAST. TEMPS WARM BACK ABOVE NORMAL BY THE WEEKEND AS THE UPPER
RIDGE BUILDS NORTHEAST...AND STILL SEEING POTENTIAL FOR CONVECTION
PUSHING SOUTHEAST INTO THE AREA DURING THIS TIME BUT OVERALL FLOW
KEEPS MOST NORTH OF US ALONG A FRONT DRAPED FROM THE MIDWEST INTO
THE GREAT LAKES. SO ASIDE FROM MAINLY DIURNAL CONVECTION IT SHOULD
BE DRY.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 130 PM EDT MONDAY...

SCATTERED MVFR SHOWERS AND THUNDERSTORMS EXPECTED THIS AFTERNOON
INTO TONIGHT ESPECIALLY ALONG THE BLUE RIDGE MOUNTAINS.
OTHERWISE...MOSTLY A VFR DAY WITH BKN-OVC MID CLOUDS AND PATCHY CU/SC.

OVERNIGHT...THE STALLED BOUNDARY WILL SERVE AS A FOCUSING
MECHANISM FOR SIGNIFICANT ISENTROPIC LIFT THAT WILL BEGIN IN
EARNEST EARLY TUESDAY. A STRONGER UPPER SHORTWAVE WILL APPROACH
FROM THE NORTHWEST RENEWING SHRA/TSRA ACTIVITY TO OUR
SOUTH...WHICH WILL SPREAD UP/OVER THE REGION TUESDAY...WITH
WIDESPREAD RAIN AS A RESULT.

THIS IS NOT EXPECTED TO REACH OUR SOUTHERN CWA BORDER UNTIL AFT
DAYBREAK TUE. OVERNIGHT...THE USUAL SPOTS...LWB/BCB/LYH...WILL BE
SUBJECT TO RADIATIONAL FOG DEVELOPMENT AS CLOUDS SHOULD REMAIN MID-
HIGH MOST OF THE NIGHT. LWB HAS THE BEST POTENTIAL FOR IFR-LIFR FG
AT THIS POINT. HOWEVER...FOG COULD DEVELOP IN ANY LOCATIONS WHICH
RECIEVES A THUNDERSTORMS THIS AFTERNOON INTO TONIGHT.

WINDS WILL BECOME CALM QUICKLY AROUND SUNSET AND
REMAIN SO OVERNIGHT. OVERALL...WINDS SPEED ON TUESDAY WILL BE LIGHT
WITH NORTHWEST TO WEST DIRECTION FAVORED IN THE MOUNTAINS.

MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH TAF VALID PERIOD.

EXTENDED AVIATION DISCUSSION...ANY BREAK FROM THE POOR FLYING
CONDITIONS WILL BE BRIEF...WITH MORE MVFR SHRA/TSRA LIKELY THROUGH
TUESDAY AS WAVES OF LOW PRESSURE RIDE ALONG A STALLED FRONTAL
BOUNDARY SOUTH OF THE CWA. CLOUDS ALONG WITH A FEW SHOWERS MAY
LINGER INTO WEDNESDAY BEFORE DRIER AIR BRINGS A RETURN TO OVERALL
VFR THURSDAY INTO FRIDAY...WITH ONLY ISOLATED DIURNAL MOUNTAIN
CONVECTION.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...JH/KK/RAB
NEAR TERM...JH/KK
SHORT TERM...RAB
LONG TERM...WP
AVIATION...JH/KK