-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 161428
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1028 AM EDT SUN JUN 16 2013

.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE REGION FROM THE WEST LATE
TODAY AND TONIGHT BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA
ONCE AGAIN...A FEW OF WHICH MAY BECOME STRONG TO SEVERE LATE TODAY
AND THIS EVENING. THE FRONT WILL STALL SOUTH OF THE REGION MONDAY
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 TONIGHT/...
-- Changed Discussion --
AS OF 1025 AM EDT SUNDAY...

HIGH PRESSURE MOVING EAST OFF THE ATLANTIC COAST RESULTING IN
SOUTHERLY FLOW BRINGING MOISTURE BACK INTO THE MID ATLANTIC
REGION FOR THIS FATHERS DAY. THIS MORNING RNK 8AM/12Z SOUNDING
SHOWED A WEAK CAP ABOUT 700MB...NORTHWEST FLOW AND PWATS AT
1.3 INCHES. EXPECT THIS CAP TO GRADUALLY DIMINISH THIS AFTERNOON
AS THE RIDGE FLATTENS...UPPER LEVEL COOL AND MOISTURE INCREASES
AS SHORTWAVE APPROACHES FROM THE WEST. A COLD FRONT WILL MOVE EAST
ACROSS OUR REGION THIS AFTERNOON INTO TONIGHT. SCATTERED SHOWERS
AND THUNDERSTORMS WILL DEVELOP AHEAD AND ALONG THE FRONT THIS
AFTERNOON INTO TONIGHT. SOME OF THE STORMS MAY BE STRONG TO
SEVERE THIS AFTERNOON INTO TONIGHT ESPECIALLY ACROSS THE NORTH
WITH BETTER DYNAMICS WITH MAIN THREAT BEING DAMAGING WINDS.
THE RNK WRFARW AND NAM SHOWED CONVECTION ENTERING THE NORTH
AROUND 18Z TO 20Z THIS AFTERNOON THEN MOVING EASTWARD INTO THIS
EVENING. THE LIMITING FACTOR OF CONVECTION WILL BE UPSTREAM
SHRA/TSRA DEBRIS CLOUDINESS THAT COULD LIMIT HEATING AND POTENTIAL
INSTABILITY. MORE UPDATES LATER THIS AFTERNOON...

AS OF 500 AM EDT SUNDAY...

ACTIVE WEATHER TO RETURN TO THE CWA TODAY...AND PERSIST WELL INTO
NEXT WEEK. MAIN CONCERN TODAY WILL BE A STRONG...HIGHLY KINEMATIC
SHORT WAVE TRACKING FROM MID-MISSISSIPPI VALLEY TOWARD THE OHIO
VALLEY AND MID-ATLANTIC REGION. MOISTURE RETURN HAS ALREADY BEGUN
IN EARNEST WITH DEWPOINTS ALREADY CREEPING BACK INTO THE LOW 60S
ACROSS MUCH OF THE AREA EAST OF THE ALLEGHANYS...WITH 50S ACROSS
SE WV AND THE HIGHER TERRAIN OF NW NC AND SW VA. INSTABILITY IS
MORE THAN SUFFICIENT FOR STRONG TO SEVERE THUNDERSTORMS BY
AFTERNOON/EVENING GIVEN EXPECTED MAX TEMPS IN THE 80S EAST TO THE
70S WEST AS THE SHORT WAVE APPROACHES FROM THE WEST. THIS COMBINED
WITH VERY HEALTHY DYNAMICS...0-2KM HELICITY APPROACHING 300 M2/S2
ACROSS AREAS NORTH OF I-64 AROUSES CONSIDERABLE CONCERN FOR STRONG
TO SEVERE TSRA THIS AFTERNOON...WITH DAMAGING WIND BEING THE MAIN
THREAT. THE LIMITING FACTOR WILL BE UPSTREAM SHRA/TSRA DEBRIS
CLOUDINESS THAT COULD LIMIT HEATING AND POTENTIAL INSTABILITY. FOR
NOW...SPC HAS HIGHLIGHTED THE AREA IN A 5 PERCENT RISK AREA...BUT
COULD UPGRADE THIS TO A SLIGHT RISK BASED ON LATER ANALYSES. HAVE
DECIDED TO MENTION STRONG/SEVERE IN GRIDS FOR 18Z-02Z TIME FRAME
FROM NW TO SE AS A RESULT.

ANOTHER CONCERN IS ACTUAL SHRA/TSRA COVERAGE. THERE DOES APPEAR TO
BE AT LEAST SOME CHANCE FOR THIS EVENT TO DO AN ALLEGHANY
SPLIT...WITH GOOD COVERAGE OF CONVECTION ACROSS SE WV...THEN
JUMPING ACROSS THE NEW RIVER VALLEY AREA/SW VA...REDEVELOPING
TOWARD THE VA PORTION OF THE PIEDMONT. NOT TOTALLY SOLD ON THIS
IDEA AT THIS POINT AND NEITHER ARE ANY OF THE MODELS. THUS...HAVE
ADVERTISED CATEGORICAL POPS ACROSS THE SPINE OF THE ALLEGHANYS
NEAR THE VA/WV BORDER 18Z-00Z...WITH MID TO HIGH CHC POPS
ELSEWHERE FROM NW TO SE IN THE 18Z-06Z TIME FRAME. DROPPED MENTION
OF TSRA AFTER 06Z FROM ALL OF THE CWA...BUT RETAINED SLIGHT CHC
SHRA AS THERE IS NO REAL COOLING/DRYING EVIDENT WITH THIS
RELATIVELY ZONAL/FAST WEST UPPER FLOW REGIME IN PLACE.

OVERALL MAX TEMPS SAT WERE WARMER THAN ADVERTISED...WITH THE
EXCEPTION OF LWB. HOWEVER...MID/HIGH CLOUD COVER SHOULD RETARD
WARMING SOMEWHAT TODAY...EVEN THOUGH 850MB TEMPS ARE SLIGHTLY
WARMER. HAVE SIDED WITH THE COOLER MAV OVERALL...ESPECIALLY LWB
FOR MAX TEMPS TODAY. AS NOTED ABOVE...COOLING/DRYING BEHIND THE
FRONT IS MINIMAL AS IT STALLS TO THE SOUTH OF THE AREA MON.
THUS...MIN TEMPS MON MORNING WILL BE ON THE MILD SIDE WITH
DEWPOINTS REMAINING NEAR 60...HENCE MIN TEMPS AS WELL...CLOSER TO
70 ACROSS THE PIEDMONT.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 345 AM EDT SATURDAY...

A COLD FRONT DROPPING SE FROM THE OHIO VALLEY WILL SETTLE OVER THE
REGION FOR THE BEGINNING OF THE WEEK. TOUGH CALL AS TO WHERE EXACTLY
THE FRONT WILL STALL...WHICH WILL DETERMINE WHERE THE MOST RAIN WILL
FALL AND FOR HOW LONG. THE SREF/NAM/GFS/ECMWF ALL HAVE BEEN WAVERING
SUBSTANTIALLY FROM RUN TO RUN WITH FRONT SPEED AND QPF PLACEMENT.
NONETHELESS...IT APPEARS THAT TUESDAY MAY BE THE WETTEST AND COOLEST
OF THE NEXT THREE DAYS...WITH POSSIBLY SOME HEAVY RAINFALL IF MODEL
PROJECTIONS OF PWATS VERIFY. ALTHOUGH GUIDANCE SWEEPS THE FRONT
SOUTH ENDING ALL PRECIP TUESDAY NIGHT...DID HOLD ONTO POPS ACROSS
THE SOUTHSIDE AND NC PIEDMONT INTO WEDNESDAY MORNING JUST BASED ON
MODEL VARIABILITY. SOME SURFACE CONVERGENCE MAY ALSO KEEP AFTERNOON
SHOWERS AND STORMS AROUND THROUGH NW NC AND THE NC PIEDMONT INTO
WEDNESDAY...WITH CLEARING ELSEWHERE.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 1245 PM EDT SATURDAY...

RESIDUAL 5H TROUGHING PATTERN WILL CONTINUE IN PLACE FOR THE
MOST PART THROUGH THE PERIOD BEFORE FLATTENING A BIT TOWARD NEXT
WEEKEND AHEAD OF MORE SHORTWAVE ENERGY APPROACHING FROM THE NW.
THIS IN THE WAKE OF A PASSING COLD FRONT TO THE SOUTH EARLIER IN
THE WEEK SHOULD ALLOW FOR A TRANSIENT AREA OF WEAK HIGH PRESSURE
TO WORK EAST FROM THE OHIO VALLEY MIDWEEK...TO ALONG/OFF THE MID
ATLANTIC COAST BY THE WEEKEND. HOWEVER THE DEGREE OF DRYING
THROUGH THE LOW LEVELS WILL REMAIN IN QUESTION...ESPCLY WITH
PERHAPS ANOTHER WEAK WAVE PASSING THURSDAY...AND LIGHT EAST/SE
FLOW UNTIL SATURDAY WHEN A MORE UNIFORM SW TRAJECTORY WILL TAKE
SHAPE. THIS COMBINED WITH HEATING AND LEFTOVER COOL AIR ALOFT
LIKELY ENOUGH TO SPARK SOME DAILY CHANCES OF SHOWERS/ISOLD TSRA
ESPCLY WEST...WITH LESS COVERAGE OVERNIGHT AND BY WEEKS END AS
HEIGHTS START TO BUILD A BIT. TEMPS TO REMAIN AT OR BELOW SEASONAL
LEVELS FOR MUCH OF THE PERIOD GIVEN WEAK COOL ADVECTION MIDWEEK
AND THEN MORE SE FLOW WHICH SHOULD KEEP HIGHS MAINLY IN THE 70S TO
LOWER 80S UNTIL THE WEEKEND WHEN A BUMP INTO THE 80S LIKELY.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
AS OF 735 AM EDT SATURDAY...

VFR CONDITIONS EXPECTED THROUGH THE FIRST HALF OF THE TAF VALID
PERIOD...ALTHOUGH AN EXTENSIVE INCREASE IN MID-LEVEL ACCAS HAS
BEEN NOTED FROM NW-SE ACROSS THE HEART OF THE CWA AT 12Z. A SURE
SIGN OF GOOD MID-LEVEL INSTABILITY ALREADY IN PLACE. MAIN CONCERN
WILL BE FRONTAL SYSTEM WITH FAIRLY HEALTHY DYNAMICS AND INCREASING
INSTABILITY ALONG WITH STRONG WAA PATTERN SUGGEST GOOD POTENTIAL
FOR THUNDERSTORM ACTIVITY THIS AFTERNOON/EVENING. THERE IS ENOUGH
CONCERN FOR SOME STRONG TO SEVERE THUNDERSTORMS AS WELL FROM MID
AFTERNOON THROUGH EARLY EVENING. CONVECTIVE ACTIVITY SHOULD MOVE
INTO/DEVELOP TOWARD EASTERN WV BY 18Z...THEN SPREAD SE TOWARD DAN
IN THE 00Z-02Z TIME FRAME. HAVE INTRODUCED/CONTINUED VCTS/TSRA IN
ALL TAFS FROM 18Z BLF/LWB TOWARD 00Z LYH/DAN...ENDING ALL SITES BY
06Z. MID-LEVEL CLOUDS AND GROUND FOG FROM MOIST GROUND WILL BE THE
CONCERN AFTER 06Z...WITH MVFR CIGS ADVERTISED FOR BLF/LWB.
OTHERWISE...CIGS EXPECTED TO BE MID/HIGH VARIETY THROUGH THE
DAYTIME WITH SCT VFR CU. INTRODUCED MVFR CIGS BCB/BLF/LWB WITH
TSRA ACTIVITY. MID/HIGH CLOUDS THIS MORNING AND LAST NIGHT HAVE
PRECLUDED FOG DEVELOPMENT...WITH VFR P6SM VSBYS AT ALL SITES AT
12Z. NO VSBY ISSUES UNTIL SHRA/TSRA ACTIVITY ARRIVES LATER TODAY.
THEN...MOSTLY MVFR IN HEAVIER ACTIVITY...POTENTIALLY LINGERING
BCB/LWB OVERNIGHT WITH MOIST GROUND AND NEAR CALM WINDS AND LITTLE
AIR MASS CHANGE. WILL NEED TO WATCH LYH AS WELL. WINDS BECOME SW
10-12KTS WITH GUSTS TO NEAR 20KTS MANY TAF SITES...EXCEPT LWB...BY
AFTERNOON...DECREASING AFT 00Z...EXCEPT IN/NEAR THUNDERSTORM
ACTIVITY.

MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN 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 SHRA/TSRA LIKELY MON THROUGH
TUE AS WAVES OF LOW PRESSURE RIDE ALONG A STALLED FRONTAL BOUNDARY
SOUTH OF THE CWA.

BLF ASOS REMAINS UNAVAILABLE BECAUSE OF A POWER OUTAGE. WILL
CONTINUE AMD NOT SKED...BUT CONDITIONS LATER TODAY MAY WARRANT A
NIL TAF FOR BLF.

&&

.EQUIPMENT...
ASOS OBSERVATION FROM BLUEFIELD (BLF) REMAINS UNAVAILABLE UNTIL
FURTHER NOTICE BECAUSE OF A POWER OUTAGE.

&&

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

&&

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