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000
FXUS61 KRNK 162357
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
757 PM EDT SUN JUN 16 2013

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTH THROUGH THE REGION INTO MONDAY BRINGING
PERIODS OF SHOWERS AND THUNDERSTORMS TO THE AREA. THE FRONT WILL
STALL SOUTH OF THE REGION MONDAY NIGHT AWAITING YET ANOTHER COLD
FRONT TUESDAY. A WIDESPREAD SOAKING RAIN AND SCATTERED
THUNDERSTORMS ARE EXPECTED TUESDAY INTO WEDNESDAY BEFORE WEAK HIGH
PRESSURE BUILDS ACROSS THE AREA THURSDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 658 PM EDT SUNDAY...

WIDESPREAD SHOWERS...WITH ISOLATED TO SCATTERED THUNDER AND SOME
WITH VERY HEAVY RAINFALL...CONTINUE TO MOVE INTO THE WESTERN
PORTION OF THE AREA AHEAD OF A WEAK UPPER LEVEL WAVE OVER CENTRAL
KY AT THIS TIME. WITH INSTABILITY BEGINNING TO SLOWLY
DIMINISH...ANY SEVERE THREAT IS VERY SMALL TO JUST ABOUT
GONE...AND BY 8PM SHOULD BE NON-EXISTENT. HOWEVER THE COVERAGE OF
SHOWERS WITH TEH SHORT WAVE MAY INCREASE IN THE WEST...AND WITH
SOME UPSLOPE HELPING TO ANCHOR NEW DEVELOPMENT IN A FEW
SPOTS...BIGGER CONCERN IS LOCALIZED HEAVY RAINFALL THROUGH AT
LEAST MIDNIGHT...WITH AN ISOLATED FLASH FLOOD THREAT IN THE WEST.
MOST HIGH RES MODELS STILL SUGGEST THE BULK OF CONVECTIVE ACTIVITY
WILL SHIFT MORE INTO SOUTHER PART OF THE AREA BY MIDNIGHT..AND
THEN DIMINISH MORE RAPIDLY. A FEW SHOWERS OR ISOLATED STORMS MAY
MAKE IT EAST OF THE BLUE RIDGE...MAINLY NORTH OF US 460 THIS
EVENING...AND POSSIBLY INTO PIEDMONT OF NC LATE TONIGHT...BUT
SHOULD BE MAINLY SHOWERS BY THEN.

MADE SLIGHT ADJUSTMENTS TO POPS TO MATCH CURRENT
COVERAGE...INCLUDING MENTION OF HEAVY RAINFALL IN FAR WEST...AND
REDUCED THUNDER TO CHANCE OR SLIGHT CHANCE REST OF THE NIGHT...BUT
WITH LIKELY TO CAGETORICAL POPS FAR WEST FOR A FEW MORE HOURS THIS
EVENING.

PREV DISCUSSION AS OF 340 PM EDT SUNDAY...

HIGH PRESSURE LOCATED IN THE WESTERN ATLANTIC THIS AFTERNOON
RESULTING IN SOUTHERLY FLOW TRANSPORTING MOISTURE BACK INTO THE MID
ATLANTIC REGION FOR THIS FATHERS DAY. DEW POINTS IN THE 60S HAVE
PUSH NORTH TO THE MASON-DIXON LINE THIS AFTERNOON. DESPITE THE CLOUD
COVER TEMPERATURES HAVE CLIMBED INTO THE MID 80S ACROSS SOUTHERN
PORTIONS OF CWA. THE COMBINATION OF A WEAK CAP ABOUT 700MB...AND
THUNDERSTORM DEBRIS CLOUDINESS HINDERING THUNDERSTORM DEVELOPMENT.
A COUPLE OF MID LEVEL SHORTWAVES TRACK EAST ACROSS THE REGION OVERNIGHT
INTO MONDAY. MEANWHILE SFC COLD FRONT DROPS SOUTHWARD ACROSS THE REGION
DURING THE PERIOD AS WAVES OF LOW PRESSURE ROLL EAST ALONG THE BOUNDARY.
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD AND ALONG THE
FRONT THIS AFTERNOON INTO MONDAY. AN ISOLATED STRONG TO SEVERE
MAY BE POSSIBLE ESPECIALLY ACROSS THE NORTH WITH BETTER DYNAMICS WITH
MAIN THREAT BEING DAMAGING WINDS. THE 12Z RNK WRFARW HAS THE GREATEST
COVERAGE OF CONVECTION THIS AFTERNOON ACROSS THE WESTERN MOUNTAINS THEN
SHIFT ACTIVITY EAST TONIGHT. THE GFS INDICATED SCATTERED CONVECTION
SPREADING EAST ACROSS THE REGION...THEN WORKS IN SOME DRIER AIR LATE
TONIGHT AND EARLY MONDAY. THE NAM WAS SIMILAR WITH CONVECTION THEN
PUNCH IN DRIER AIR ALONG THE EASTERN SLOPES OF THE BLUE RIDGE. HARD TO
TELL HOW MUCH DRIER AIR WORKS IN BEHIND THE SHORTWAVE OVERNIGHT...BUT
ELECTED TO TRIM POPS A LITTLE ACROSS THE NORTH. WITH CLOUD COVER AND
PRECIPITATION PLAYED LOW TEMPERATURES OVERNIGHT CLOSER TO WARMER ADJMAV
VALUES FROM THE UPPER 50S IN THE NORTHWEST MOUNTAINS TO NEAR 70 DEGREES
IN THE PIEDMONT. BLENDED THE ECMWF AND ADJMAVBC FOR HIGH TEMPERATURES ON
MONDAY RESULTING IN READINGS FROM THE MID 70S IN THE MOUNTAINS TO
THE MID 80S IN THE SOUTHEAST.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 255 PM EDT SUNDAY...

WILL FOLLOW CLOSER TO THE 00Z ECMWF AS IT HAS LESS CONVECTIVE
FEEDBACK AND TOO STRONG A VORT CENTERS...ALTHOUGH CANNOT RULE OUT
SOME CLUSTERS OF CONVECTION TO OUR WEST. GOING INTO MONDAY NIGHT A
SHORTWAVE PUSHES FROM MIDDLE KY/TN ESE INTO OUR REGION BY 12Z
TUESDAY. THIS IS ACTUALLY WITH A PREFRONTAL SFC TROUGH AND MAIN LIFT
GOES BY TO THE SOUTH WITH NEXT VORT INDUCED WAVE ARRIVING INTO THE
WEST BY MID MORNING TUESDAY. MONDAY NIGHT KEPT HIGHER POPS ACROSS
THE SOUTHWEST WHERE BETTER LOW LVL CONVERGENCE OCCURS. WILL STILL
BLEND IN OTHER MODELS TUESDAY GIVEN UNCERTAINTY ON FRONTAL
PASSAGE...BUT WE LOOK TO AT LAST SEE LIKELY POPS CWA WIDE...ALTHOUGH
THE 12Z ECMWF NOW COMING IN HAS PUSHED EVEN FURTHER SOUTH THE DEEPER
MOISTURE AND FRONT WHERE HEAVIEST RAIN WILL FALL FROM TN INTO NC.

SVR THREAT SEEMS MARGINAL GIVEN HOW MUCH CLOUD COVER IS
EXPECTED...LEADING TO POOR LOW LVL LAPSE RATES...AND DYNAMICS ALOFT
APPEAR LACKING.

TRICKY FORECAST WILL CONTINUE TUE NIGHT-WED AS IT DEALS WITH HOW FAR
SOUTH THE FRONT GOES AND WHERE THE BEST PRECIP CHANCES LIE. WILL
TRANSITION MORE TO STRATIFORM TUE NIGHT/EARLY WED GIVEN FRONT TO THE
SOUTH AND OVERRUNNING. WILL GO WITH LOWER POPS FOR NOW BUT IF THE
MODELS BECOME CONSISTENT ON A FURTHER NORTH LOCATION OF THE FRONT
COULD SEE HIGHER POPS TUE NIGHT-WED. FOR WHAT ITS WORTH THIS PERIOD
LOOKS MORE CLOUDY AND DAMP. WENT WITH HIGHS COOLER THAN MOS THINKING
THE PRECIP WILL HOLD TEMPS DOWN. WITH SFC HIGH MOVING NORTH OF US
WEDNESDAY...AND WIND FROM THE NE SHOULD KEEP US COOL.

&&

.LONG TERM /WEDNESDAY NIGHT 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 /00Z MONDAY THROUGH FRIDAY/...
AS OF 755 PM EDT SUNDAY...

MAINLY MVFR SHOWERS AND THUNDERSTORMS ALREADY IMPACTING THE WV
TAF SITES...AND BY 01-02 UTC SHOULD BE INTO BCB AND POSSIBLY
ROA/LYH BY 02-03 UTC ALTHOUGH THUNDER CHANCES MINIMIZING THE
FARTHER EAST AND LATER INTO THE EVENING. APPEARS GUSTY WINDS AT
THIS TIME NOT EXPECTED TO BE A BIG CONCERN WITH ANY STORMS AND
REDUCED THOSE SPEEDS CONSIDERABLY IN THE TAFS. WITH PLENTY OF MID
LEVEL DEBRIS CLOUDS OVERNIGHT AND EVEN LINGERING SHOWERS POSSIBLY
FARTHER SOUTH WELL PAST MIDNIGHT SUCH AS DAN...HAVE NOT REDUCED
VSBYS TO IFR EXCEPT LWB AND LYH...AND THIS IS NOT A VERY HIGH
CONFIDENCE AT LYH ESPECIALLY GIVEN UNCERTAINTLY IN MID TO HIGH
CLOUDS AND HOW MUCH PRECIP THEY MAY GET THIS EVENING.

FOR DAYTIME HOURS MONDAY...SOME SHOWERS MAY BE LINGERING ACROSS
THE SOUTH...BUT EXPECT CONDITIONS TO IMPROVE TO VFR BY MID MORNING
AT LEAST. SOME SCT STORM COULD DEVELOP AGAIN BY
AFTERNOON...MAINLY ACROSS THE SOUTHERN PORTION SO ONLY MENTIONED
CB AT BLF/BCB/DAN AND KEPT VFR EVERYWHERE.

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

EXTENDED AVIATION DISCUSSION...ANY BREAK FROM THE INCLEMENT
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.

BLF ASOS IS ONCE AGAIN AVAILABLE BUT ALL OBSERVATIONS ARE SLOW TO
MAKE IT INTO INTERNAL NWS SYSTEM NOW PER A NATIONAL COMMUNICATIONS
ISSUES. THEY ARE FLOWING AGAIN BUT BEHIND SCHEDULE. FOR NOW...WILL
PLAN ON AMENDMENTS AT ALL SITES UNLESS WEATHER CONDITIONS BEGIN TO
CHANGE RAPIDLY AND OBSERVATIONS REMAIN WAY BEHIND.

&&

.EQUIPMENT...
ASOS OBSERVATION FROM BLUEFIELD (BLF) APPEARS TO BE AVAILABLE ONCE
AGAIN...HOWEVER DUE TO A NWS GATEWAY COMMUNICATIONS ISSUE THAT IS
NEW THIS EVENING...MOST NWS OFFICES ARE SLOW TO INGEST CURRENT
ASOS AND AWOS OBSERVATIONS...NOR ARE WE INGESTING ANY LIGHTNING
DATA. A BACK LOG OF OBSERVATIONS ARE BEGINNING TO FILL IN BUT IT
MAY TAKE A WHILE BEFORE THEY CATCH UP.

&&

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

&&

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