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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 151816
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
216 PM EDT WED MAY 15 2013

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE EAST AND OFFSHORE THE SOUTHEAST COAST
TODAY ALLOWING FOR A RETURN SOUTHWEST FLOW OF VERY WARM AIR INTO
THIS AFTERNOON. DEEP LOW PRESSURE PASSING ACROSS THE NORTHERN
GREAT LAKES WILL LIFT AN ASSOCIATED WARM FRONT NORTH OF THE AREA
LATER TODAY WITH AN ASSOCIATED COLD FRONT APPROACHING FROM THE
NORTH BY EARLY THURSDAY. THIS FRONTAL BOUNDARY WILL DROP SOUTH
INTO THE REGION LATER THURSDAY BEFORE STALLING OVER OR NEAR THE
AREA INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT WEDNESDAY...

SURFACE OBSERVATIONS INDICATE THAT WIND SPEEDS ACROSS THE NORTH
CAROLINA MOUNTAINS INTO GRAYSON COUNTY ARE COMING DOWN
SIGNIFICANTLY FROM THE STRONGER GUSTS OF THE OVERNIGHT...AND
THEREFORE HAVE CANCELLED THE WIND ADVISORY FOR THAT AREA. THAT
STATED...THE PRESSURE GRADIENT BETWEEN A DEEP LOW PRESSURE SYSTEM
NORTH OF THE GREAT LAKES AND HIGH PRESSURE OFF THE COAST WILL
REMAIN TIGHT TODAY...AND WE CAN EXPECT ANOTHER ROUND OF GUSTY WEST
WINDS THROUGH THE DAY...OCCASIONALLY REACHING 25 MPH AT TIMES.
THIS DOWNSLOPE WIND...WHEN COMBINED WITH INCREASED RIDGING IN THE
UPPER LEVELS...WILL RESULT IN SOME OF THE WARMEST TEMPERATURES
THIS FAR INTO THE YEAR...WITH AFTERNOON HIGHS PUSHING THE UPPER
80S TO 90 EAST OF THE BLUE RIDGE...AND UPPER 70S TO MID 80S ACROSS
THE MOUNTAINS. SCATTERED CLOUDS SOUTH OF THE INTERSTATE 81
CORRIDOR ARE EXPECTED TO PUSH OUT OF THE AREA BY EARLY
AFTERNOON...MAKING FOR MOSTLY SUNNY SKIES THEREAFTER.

UPPER RIDGING WILL BREAKDOWN SOMEWHAT OVERNIGHT AS A COLD FRONT
TO THE NORTH SAGS SOUTH. WINDS ABOVE THE SURFACE AHEAD OF THE
FRONT WILL AGAIN INCREASE AS A WEAK MID LEVEL TROF SWINGS BY TO
THE NORTHEAST OVERNIGHT. HOWEVER SOUNDINGS SHOW LESS MIXING DOWN
ACROSS THE HIGHER ELEVATIONS WITH MORE MOISTURE IN PLACE SO NOT
EXPECTING A REPEAT OF THIS EARLY MORNINGS GUSTS OVER THE MOUNTAINS.
OTHERWISE...CLOUDS AHEAD OF THE BOUNDARY WILL INCREASE SOME
LATE...WITH PERHAPS A THIN BAND OF SHOWERS NEARING THE FAR
NORTHWEST. SINCE LATEST MODELS ARE SLOWER GIVEN THE STRONG
RIDGING...ONLY KEPT A VERY LOW CHANCE OF RAIN...WITH SKIES
MAINLY CLEAR OVER THE SOUTHERN HALF OF THE FORECAST AREA THROUGH
MORNING AND BECOMING PARTLY CLOUDY ELSEWHERE. QUITE A WARM AND
ALMOST MUGGY NIGHT WITH DEWPOINTS JUMPING INTO THE 50S AND LIGHT
MIXING/WARM ADVECTION KEEPING LOWS 60-65 ON THE RIDGES AND...WITH
ONLY THE VALLEYS SEEING SOME 50S.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 400 AM EDT WEDNESDAY...

UNSETTLED PERIOD WITH FRONTAL BOUNDARY TRAVELING ACROSS
OUR REGION. WITH BROAD MID LEVEL RIDGING OVER THE AREA
INITIALLY...SLOWED DOWN THE ADVANCE OF POPS THURSDAY
MORNING. BY THURSDAY AFTERNOON...H5 TROUGH WILL ROLL
ACROSS THE MISSISSIPPI RIVER VALLEY. FRONTAL BOUNDARY
WILL SLOW DROP SOUTH THURSDAY. PLACED THE HIGHEST POPS
ACROSS THE NORTHWEST ON THURSDAY. HIGH TEMPERATURES ON
THURSDAY WILL BE COOLER THAN TODAY BECAUSE OF ADDITIONAL
CLOUD COVER WITH READINGS FROM THE UPPER 60S IN THE
NORTHWEST TO THE MID 80S IN THE SOUTHEAST.

A WEAKENING AREA OF LOW PRESSURE WILL TRAVEL EAST ACROSS THE
TENNESSEE VALLEY THURSDAY NIGHT...THEN MOVES INTO THE SOUTHERN
APPALACHIANS FRIDAY. MOISTURE WILL INCREASE AND CLOUDS THICKEN
AND LOWER THURSDAY NIGHT. KEPT THE HIGHER POPS IN THE WEST.
EXPECT A MILD THURSDAY NIGHT WITH CLOUDS AND SOUTHERLY
FLOW...WITH LOWS FROM LOWER 50S IN THE WEST TO LOWER 60S IN THE
EAST.

ON FRIDAY...A SHORTWAVE ROTATING THROUGH THE UPPER TROUGH OVER
NEW ENGLAND WILL PUSH THE FRONTAL BOUNDARY SOUTH...THEN IT
RETREATS BACK NORTHWARD BY FRIDAY NIGHT. COMBINATION OF BOTH THE
SHORT WAVE AND FRONT WILL BRING THE MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS INTO THE AREA. HIGHS ON FRIDAY WILL VARY FROM
UPPER 60S IN THE NORTHWEST TO LOWER TO MID 80S IN THE SOUTHEAST.
HARD TO PIN POINT POPS FOR FRIDAY NIGHT...BUT SHAPE TOWARDS
ECMWF/GFS BLEND WITH HIGHER POPS IN THE EAST. ANOTHER MILD AND
HUMID NIGHT WITH LOWS IN MID 50S TO LOWER 60S.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 330 PM EDT TUESDAY...

SEEING SIGNIFICANT DIFFERENCES BETWEEN THE 00Z/14 ECMWF AND
GFS BY SUNDAY WITH THE LONG WAVE TROF IN THE CENTRAL UNITED
STATES. ECMWF SHOWED A DISTINCT SOUTHERN PIECE OF THE TROF
AND WAS MUCH SLOWER THAN THE GFS.

STARTING OUT SATURDAY MORNING WITH THE SURFACE FRONT FROM
WISCONSIN INTO NORTHWESTERN VIRGINIA. BY SUNDAY THE FRONT HAS
MOVED BACK NORTH. LEANING TOWARD THE SLOWER ECMWF KEEPS THE
FORECAST AREA DEEP IN THE WARM UNSTABLE AIR THROUGH TUESDAY.

MODELS ALSO ARE TAKING THE UPPER LOW ACROSS THE ROCKIES...THEN
THE TENNESSEE VALLEY...THEN INTO THE SOUTHERN APPALACHIANS SUNDAY
NIGHT. SUSPECT THE DETAILS MAY NOT BE CORRECT THIS FAR OUT BUT
IDEA OF A SHORT WAVE CUTTING INTO THE EASTERN UPPER RIDGE IS
REASONABLE. MAY HAVE ENHANCED PROBABILITY OF PRECIPITATION WITH
ANY FEATURE LIKE THIS SATURDAY THROUGH TUESDAY.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 200 PM EDT WEDNESDAY...

EXPECT VFR CONDITIONS FOR ALL AIRPORTS THROUGH THE 15/18Z TAF
PERIOD.

THROUGH THE REMAINDER OF WEDNESDAY...SCT MID LEVEL CLOUDS IN THE
VICINITY OF DAN AND LYH WILL CONTINUE EAST...MAKING FOR CLEAR TO
MOSTLY CLEAR SKIES...POSSIBLY WITH A FEW AFTERNOON CU. WINDS WILL
REMAIN GUSTY FROM THE WEST...OCCASIONALLY REACHING 25KTS FOR ROA
AND POINTS WESTWARD...AND 20KTS AT DAN AND LYH. WIND SPEEDS WILL
DIMINISH WITH SUNSET.

A WEAK COLD FRONT WILL APPROACH FROM THE NORTH LATE TONIGHT WITH
A RIBBON OF LOWER CEILINGS LIKELY PRECEDING THE BOUNDARY ACROSS
THE FAR NORTH AROUND 16/12Z. MID AND HIGH CLOUDS WILL THICKEN
AFTER SUNRISE THURSDAY...AND LOW CLOUDS MAY APPROACH CLOSE ENOUGH
TO LWB FOR A LOW END VFR STRATO-CU DECK TO SETTLE ACROSS THE
FIELD.

SHOWER ACTIVITY WILL INCREASE FROM THE NORTH ON THURSDAY AS THE
FRONT SINKS FURTHER TO THE SOUTH...WITH SOME SHOWERS DEVELOPING
INTO THUNDERSTORMS DURING LATE MORNING WITH DAYTIME HEATING. AT
THIS TIME...BELIEVE BEST COVERAGE OF CONVECTION WILL BE DURING MID
AFTERNOON AND EVENING...WITH BETTER CHANCES ACROSS THE MOUNTAINS.

THURSDAY BEGINS A PERIOD OF SCATTERED SHOWER AND THUNDERSTORM
ACTIVITY THAT WILL LAST THROUGH THE WEEKEND AS THE FRONT STALLS
JUST NORTH OF THE FORECAST AREA...WITH WEAK IMPULSES PASSING ALOFT
TO OFFER UPPER LEVEL SUPPORT. APPEARS THE AFTERNOON AND EARLY
EVENING HOURS WOULD HAVE THE BEST CHANCE OF SEEING PERIODS OF
MVFR/IFR IN SHRA/TSRA...ESPECIALLY FRIDAY INTO SUNDAY AFTERNOON
PENDING WHERE THE FRONT ENDS UP. WILL ALSO SEE PATCHY FOG DURING
THE OVERNIGHTS.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...JH/NF
NEAR TERM...JH/NF
SHORT TERM...KK
LONG TERM...AMS
AVIATION...JH/NF