-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 111926
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
326 PM EDT TUE MAR 11 2014

.SYNOPSIS...
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HIGH PRESSURE WILL RELINQUISH CONTROL OF THE WEATHER ACROSS THE
MID-ATLANTIC REGION OVERNIGHT AS LOW PRESSURE DEVELOPS OVER THE
MIDWEST AND MOVES RAPIDLY EAST ON WEDNESDAY. AN ASSOCIATED STRONG
COLD FRONT WILL BRING SHOWERS AND POSSIBLY A FEW STRONG
THUNDERSTORMS DURING THE DAY...FOLLOWED BY HIGHS WINDS AND MUCH
COLDER AIR WEDNESDAY NIGHT INTO THURSDAY.
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&&

.NEAR TERM /THROUGH WEDNESDAY/...
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AS OF 320 PM EDT TUESDAY...

ANOTHER VERY MILD NIGHT ON TAP AS WE AWAIT SIGNIFICANT CHANGES
TOMORROW. SHOULD START OFF CLEAR AND COULD COOL OFF IN VALLEYS
FAIRLY RAPIDLY WHILE RIDGES REMAIN MIXED AND WARM. CLOUDS WILL BE ON
THE INCREASE HOWEVER AS LOW PRESSURE DEVELOPS OVER THE MISS/OHIO
VALLEY TONIGHT WHILE INTENSIFYING RAPIDLY WITH THE UPPER SUPPORT
FROM AMPLIFYING SHORT WAVE. THIS FEATURE DEEPENS TO NEAR A 980 MB
LOW AS IT TRACKS RAPIDLY EASTWARD ACROSS SOUTHERN PENNSYLVANIA
TOWARD NEW YORK CITY BY 00Z/13 WITH THE TRAILING FRONT ACCELERATING
VERY QUICKLY ACROSS THE CENTRAL/SOUTHERN APPALACHIAN MOUNTANS
BETWEEN ABOUT 18Z TO 00Z. COLD AIR PLUNGE IS IMPRESSIVE ESPECIALLY
AFTER WE HAVE BEEN BASKING IN SUCH EARLY SEASON WARMTH. H85 TEMPS
WHICH ARE NEAR +10C TODAY AND EVEN MID-MORNING TOMORROW ARE FORECAST
TO FALL IN THE LATE AFTERNOON TO AROUND -10C BY 00Z IN THE WEST AND
FURTHER YET OVERNIGHT. TO BE SERVED UP WITH THAT DOSE OF COLD AIR
WILL BE A SIDE DISH OF HIGH WINDS AND PRESSURE RISES BEGINNING
LATE IN THE AFTERNOON. CROSS-BARRIER H85 WINDS OF 50 TO 60 KNOTS
ARE SHOWN ON SEVERAL MODELS...ESPECIALLY AFTER 00Z. QPF WITH THIS
FAST-MOVING SYSTEM NOT EXPECTED TO BE MUCH...GENERALLY WENT WITH
HPC NUMBERS WHICH SEEM REASONABLE OF UNDER 0.25 INCHES WITH THE
LOW TRACKING WELL NORTH OF THE CWA. COULD BUMP UP PRECIP AMOUNTS
IN A FEW STRONGER CELLS IF THESE MATERIALIZE. ALSO HAVE CHANCE OR
SLIGHT CHANCE OF THUNDER WITHIN THE GENERAL BAND OF SHOWERS WITH
THE FRONT AS SOME MODEL CAPES/LIS APPROACH 400 J/KG AND -1 TO -2
WITH THE HIGHER NUMBERS OUT OVER THE PIEDMONT. SPC HAS PLACED
ABOUT THE NORTHEAST HALF OF THE CWA IN SLIGHT RISK FOR DAMAGING
WINDS DUE TO THE COMBINATION OF JET WINDS ALOFT AND CHANCES FOR
LOW-TOPPED CONVECTION WITHIN QUASI-LINEAR BANDS EXPECTED AHEAD OF
THE FRONT.
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&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
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AS OF 300 PM EDT TUESDAY...

500 MB TROF AXIS CROSSES THROUGH FORECAST AREA AND EASTERN UNITED
STATES WEDNESDAY NIGHT AS UPPER LOW CLOSES OFF OVER NEW HAMPSHIRE.
FORECAST AREA WILL BE UNDER WEAK UPPER RIDGING BY FRIDAY.

MANY PARAMETERS STILL VERY FAVORABLE FOR STRONG WINDS WEDNESDAY
NIGHT INCLUDING...TIGHT PRESSURE GRADIENT AND STRONG COLD AIR
ADVECTION. VALUES FOR 6 HOUR PRESSURE RISES BY 00Z THURSDAY/8PM
WEDNESDAY ARE EVEN LARGER THAN ON THE MODELS FROM YESTERDAY...NOW
PEAKING AT 19MB/6HOURS OVER WEST VIRGINIA. BUKFIT SOUNDINGS START
WITH A 55-60 KNOT NORTHWEST JET...ABOUT RIDGE LEVEL...WITH MEAN
GUSTS WELL ABOVE 40 KNOTS. WILL BE ISSUING A HIGH WIND WATCH FROM
LATE WEDNESDAY AFTERNOON THROUGH EARLY THURSDAY MORNING.

BY THURSDAY AFTERNOON WINDS WILL BEGIN TO DIMINISH AND THE LOW LEVEL
MOISTURE WRAPPING AROUND THE LOW WILL ERODE. SURFACE HIGH PRESSURE
MOVING ACROSS THE SOUTHEAST UNITED STATES WILL BE CENTERED OVER THE
CAROLINAS AND GEORGIA BY FRIDAY MORNING.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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AS OF 300 PM EDT TUESDAY...

WARM FRONT CROSSING TROUGH THE OHIO VALLEY FRIDAY NIGHT MAY BRING
CLOUDS INTO THE NORTHERN COUNTY WARNING AREA.

NEXT SHORT WAVE IN THE NORTHERN STREAM PASSES THROUGH THE TROF BUT
NORTH OF THE FORECAST AREA ON FRIDAY NIGHT AND SATURDAY. MODELS WERE
SHOWING A MORE AMPLIFIED TROF IN THE EAST BY MONDAY BUT WERE STILL
DIFFERENT ON THE TIMING. SIMILARLY...THE DIFFERENCES IN THE MODELS
SHOW UP ON THE SURFACE FORECASTS. CANADIAN HAS A LOW OVER VIRGINIA
BY SUNDAY MORNING WHILE THE 00Z ECMWF HAS IT IN THE GULF OF MEXICO.
COMPROMISE FROM WPC HAS AN ELONGATED SURFACE LOW FROM GEORGIA TO THE
CAROLINA COAST.

850 MB TEMPERATURES DROP BACK DOWN JUST BELOW ZERO BEHIND THE FRONT
ON SATURDAY. FORECAST AREA REMAINS IN THAT AIR MASS THROUGH MONDAY.
STILL THE POTENTIAL FOR A STRIPE OF SNOW OR WINTER PRECIPITATION ON
THE NORTHERN EDGE OF WHEREVER THE PRECIPITATION SHIELD ENDS UP
SUNDAY NIGHT AND MONDAY.

WARM AIR ADVECTION PICKS UP AGAIN ON TUESDAY AND BULK OF DEEP
MOISTURE MOVES WELL OFF THE EAST COAST.
-- End Changed Discussion --

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 130 PM EDT TUESDAY...

EXPECTING VFR AT ALL LOCATIONS WITH NO AVIATION ISSUES THROUGH ROUGHLY
THE FIRST HALF OF THE TAF PERIOD. WILL KEEP SOME LIGHT GUSTS IN EARLY...
THOUGH TREND WILL BE FOR SLACKENING WINDS AND FEWER GUSTS. NEXT SYSTEM
APPROACHES OVERNIGHT AND WILL SEE CONDITIONS DETERIORATING TOWARDS DAYBREAK.

AS LOW PRESSURE STRENGTHENS AND MOVES THROUGH THE OHIO VALLEY...MOISTURE
WILL BE MOVING IN RAPIPDLY FROM THE SOUTHWEST ALONG WITH SOME ISENTROPIC
LIFT AND UPPER DIVERGENCE. EXPECTING MVFR CIGS TO DEVELOP TOWARD 12Z AND
BEST CHANCE OF SOME PRE DAWN SHOWERS LOOKS TO BE AT WESTERN SITES
KBLF/KLWB/KBCB.

AS THE LOW MOVES TO THE MIDDLE ATLANTIC COAST IT WILL SWING A STRONG COLD
FRONT THROUGH THE REGION...THOUGH FROPA WILL BE OUTSIDE OF THE TAF WINDOW
FOR THIS PACKAGE. SWLY FLOW WILL INCREASE AS THE FRONT APPROACHES AND EXPECT
A GOOD SWLY WIND TO BE BLOWING AT ALL LOCATIONS AS WE GET TOWARD 18Z. ALSO...
MODEL SOUNDINGS INDICATE STEEP MID LEVEL LAPSE RATES AND BELIEVE THUNDER IS
A GOOD BET SO WILL INCLUDE LATE.

.EXTENDED AVIATION...
WEDNESDAY NIGHT INTO THURSDAY...COLD AIR BEHIND THE COLD FRONT WITH
LINGERING MOISTURE WILL BRING SNOW SHOWERS TO THE
MOUNTAINS....KLWB AND KBLF. POTENTIAL BRIEF IFR CONDS WITH MVFR
PROBABLE. ALSO...STRONG WINDS ARE EXPECTED WEDNESDAY NIGHT INTO
THURSDAY BEHIND THE FRONT. WIND GUSTS VCNTY OF THE MTNS MAY
APPROACH 40 KTS.

BY FRIDAY...HIGH PRESSURE WILL SETTLE OVER THE AREA AND BRING A
DECREASE IN WIND SPEED AND A RETURN TO VFR CONDITIONS FOR THE
ENTIRE AREA.

&&

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

&&

$$
SYNOPSIS...PC/PM
NEAR TERM...PC
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...MBS