-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 160745
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
345 AM EDT THU MAY 16 2013

.SYNOPSIS...
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A COLD FRONT WILL SAG SOUTHWARD ACROSS THE AREA TODAY. THE FRONT
WILL STALL JUST SOUTH OF THE REGION THROUGH THE WEEKEND WHILE HIGH
PRESSURE BUILDS TO THE NORTH IN NEW ENGLAND. THE STALLED FRONTAL
BOUNDARY WILL LIFT NORTHWARD ACROSS THE REGION AS A WARM FRONT
EARLY NEXT WEEK.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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AFTER HOVERING ABOUT THE I-70 CORRIDOR FOR MUCH OF THE DAY...THE
SLOW MOVING COLD FRONT IS STILL ON THE WAY FROM THE NORTH BUT MAKING
PROGRESS TOWARD THE MASON-DIXON LINE. SOME NEWER OVERNIGHT
CONVECTION STARTING UP ACROSS THE WINDWARD SIDE OF THE CNTL APLCNS
ALONG THE BOUNDARY. ONLY A FRACTION OF THIS ACTIVITY IS EXPECTED TO
CLEAR THE HIGHER TERRAIN AND MOVE INTO THE NRN TIER COUNTIES OF THE
CWA. MEANWHILE...FAST UPPER ZONAL FLOW WILL CONTINUE TO INTERACT W/
THIS FEATURE AND ALLOW FOR PERIODIC DEVELOPMENT OF ISOLATED
SHOWERS/TSTMS OVER THE COURSE OF THE DAY AND NIGHTTIME HRS.

THE FRONT...WHICH IS MORE OF A STATIONARY TRANSITIONAL BOUNDARY W/
AN INCOMING WARM FRONT OVER THE UPPER MIDWEST CONNECTING TO A COLD
FRONTAL PORTION FROM AN EXITING LOW PRESSURE SYSTEM OFF THE NEW
ENGLAND COAST. MORE SOLID AND UNINTERRUPTED CONVECTIVE LINES WILL
DEVELOP ACROSS SRN OH/IN TO NRN KY/WV. THE LEADING EDGE OF THESE
LINES WILL CONTINUALLY DISSIPATE AS THEY DRIFT ESE LATER THIS MRNG
AND EARLY AFTN. PLENTY OF PRECIP-LESS CLOUD DEBRIS WILL MAKE IT E OF
THE MTNS...COVERING THE AREA FOR MUCH OF THE DAY. A FEW ISOLATED
SHOWERS WILL DOT THE AREA DURING THE DAYTIME HRS...BUT MOST OF THE
REGION WILL STAY DRY.

SOME OF THE LOCAL GUIDANCE COMING INTO VIEW DEPICTS THE SRN HALF OF
THE CWA - N CNTRL VA IN PARTICULAR - AS THE FOCUS FOR AFTN
CONVECTIVE DEVELOPMENT THAT WILL EVENTUALLY SLIDE TOWARD THE
LOWER VA CHESAPEAKE/TIDEWATER LATER TONIGHT. INSTABILITY DOESN`T
LOOK TO BE AS FAVORABLE TODAY AS IT WAS ON WED...GIVEN THE DENSE
CLOUD COVER CUTTING DOWN ON AVAILABLE HEATING - BUT DEWPOINTS WILL
BE SIMILAR. ENOUGH MARGINAL INSTABILITY...SOME WEAK LOW LEVEL
CONVERGENCE AND GOOD BOUNDARY LAYER SHEAR WILL BE AVAILABLE FOR
SCATTERED STORMS THIS AFTN. CONVECTION COULD FIRE ANYWHERE IN THE
CWA...ALONG THE AFTN CHESPKE BAY BREEZE - THE SWD SAGGING FRONT OR
FROM A FEW PEAKS OF SUN OVER THE NRN VA PIEDMONT THIS AFTN.

CONVECTION WILL CONTINUE TO DEVELOP BACK TO THE WEST OF THE CNTRL
APLCNS OVERNIGHT...BANKING INTO THE TERRAIN AND DISSIPATING ON THE
EAST SIDE. ONLY A FRACTION OF THIS AND THE EARLIER STORMS WILL
CONTINUE LATE THIS EVE ACROSS THE SRN HALF OF THE CWA. CLOUDS WILL
BEGIN TO DISSIPATE AND DRIFT SWD ALONG W/ THE BOUNDARY...SLOWLY
USHERING IN SOME COOLER DEWPOINTS AND TEMPS AS WELL. OVERNIGHT LOWS
WILL DROP BACK INTO THE 50S AND L60S FOR THE METRO AREAS.
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&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
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FRONTAL BOUNDARY IS FORECAST TO STALL OUT TO THE SOUTH OF THE
AREA FRIDAY INTO THE WEEKEND AS HIGH PRESSURE BUILDS TO THE NORTH
ACROSS EASTERN CANADA AND NEW ENGLAND.

ON FRIDAY HAVE FOCUSED POPS/THUNDERSTORM POTENTIAL ACROSS THE
SOUTHWEST PORTION OF THE CWA CLOSEST TO THE BOUNDARY WITH A DRY
FORECAST FURTHER NORTHEAST TOWARD THE DC-BALT METRO AREA.

HOWEVER OVER THE WEEKEND...EVEN WITH THE BOUNDARY TO THE SOUTH
MODELS INDICATE SIGNS OF LIFT INCREASING TO THE NORTH LIKELY DUE TO
VORT MAXES/SHORTWAVES IN 500 MB FLOW IN TANDEM WITH LOW LEVEL
EASTERLY FLOW. THEREFORE POPS EXPAND NORTHEASTWARD DURING THE
WEEKEND.

AT THE SURFACE...AFOREMENTIONED EASTERLY LOW LEVEL FLOW IS EXPECTED
TO TREND MAXIMA DOWNWARD TO BELOW NORMAL OVER THE WEEKEND WITH NEAR
TO SLIGHTLY ABOVE NORMAL MINIMA.
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&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
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FRONTAL BOUNDARY WILL LIFT BACK TO THE NORTH AS A WARM FRONT EARLY
NEXT WEEK...ALLOWING TEMPERATURES TO TREND UPWARD THROUGH MID-WEEK
IN ADVANCE OF THE NEXT LARGER SCALE SHORTWAVE. UNSETTLED CONDITIONS
WITH A CHANCE OF CONVECTION IS EXPECTED THROUGH THEN.
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&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
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A SLOW-MOVING FRONTAL BOUNDARY WILL CONTINUE TO SAG SOUTH AND EAST
THIS MRNG AND AFTN. ISOLATED RA/TS ACTIVITY WILL DEVELOP ACROSS THE
REGION...ESPECIALLY HEADING THRU THE AFTN HRS. SOLID MID CLOUD DECKS
WILL STREAM ACROSS THE AREA TODAY...W/ A LIGHT WLY BREEZE. TS
ACTIVITY WILL DISSIPATE AND DRIFT SE OF THE AREA LATE TONIGHT.

FRONTAL BOUNDARY IS FORECAST TO STALL OUT TO THE SOUTH OF THE AREA
THROUGH THE WEEKEND THEN RETURN NORTH AS A WARM FRONT EARLY NEXT
WEEK. HUBS LOOK TO STAY DRY ON FRIDAY...BUT A CHANCE OF SHOWERS WILL
RETURN NORTH OVER THE WEEKEND AND THUNDERSTORMS WILL BE POSSIBLE
NEXT WEEK.
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&&

.MARINE...
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WINDS HAVE CALMED DOWN ACROSS THE WATERS FROM EARLIER. ONLY A
STEADY 10KT BREEZE THROUGHOUT THE DAY...HELPED BY THE INCREASE IN
CLOUD COVER TODAY. BATCHES OF ISOLATED TO SCATTERED TSTMS EXPECTED
TO DEVELOP LATER THIS AFTN...BRINGING THE POTENTIAL FOR SMW/MWS
ISSUANCES W/ STRONGER ACTIVITY. TSTMS WILL SUBSIDE AND DRIFT
TOWARD THE ESE LATER TONIGHT AND AWAY FROM THE REGION.

FRONTAL BOUNDARY WILL STALL OUT SOUTH OF THE WATERS THROUGH THE
WEEKEND BEFORE LIFTING BACK TO THE NORTH EARLY NEXT WEEK. GRADIENT
IS EXPECTED TO REMAIN FAIRLY WEAK THROUGH THE PERIOD. AS WINDS
BECOME EAST-SOUTHEAST OVER THE WEEKEND...WINDS MAY FLIRT WITH
MARGINAL SCA CRITERIA OVER A PORTION OF THE BAY.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
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&&

$$
SYNOPSIS...GMS/BPP
NEAR TERM...GMS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...GMS/BPP
MARINE...GMS/BPP