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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 171412 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1012 AM EDT FRI MAY 17 2013

.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OUT TO THE SOUTH THROUGH THIS
WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF ACROSS THE NORTH
ATLANTIC. THE FRONTAL BOUNDARY WILL RETURN TO THE NORTH AS A WARM
FRONT EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
COLD FRONT HAS CLEARED ALL BUT THE SOUTHWESTERN QUADRANT OF THE
CWFA. A STABLE AIRMASS WILL CONTINUE TO THE NORTH OF THE BOUNDARY
WITH ABUNDANT SUNSHINE AND COOLER TEMPERATURES TODAY VERSUS THE
PAST COUPLE OF DAYS. SOME MID AND HIGH LEVEL CLOUDS WILL MOVE IN
LATER IN THE DAY. SCATTERED SHOWERS/ISOLATED STORMS STILL POSSIBLE
OVER WESTERN SECTIONS THIS AFTERNOON IN AREA OF WEAK CONVERGENCE
ALONG THE STALLED FRONTAL BOUNDARY. NOT EXPECTING ANY ORGANIZED
CONVECTION.

TEMPS TODAY WILL BE EVEN MORE MODERATED FROM YESTERDAY W/ DRIER
AIR AND A LIGHT BUT STEADY NE BREEZE COMING DOWN THE I-95 CORRIDOR
FOR MUCH OF THE DAY. MOST AREAS WILL PEAK IN THE U70S...W/ A FEW
LOCALES HITTING 80 LATE THIS AFTN. OVERNIGHT LOWS WILL BE DROP
INTO THE U50S/L60S.
-- End Changed Discussion --

&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
FRONTAL BOUNDARY WILL REMAIN STALLED OUT TO THE SOUTH THIS
WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF OFF THE NORTHEAST
COAST AND NORTH ATLANTIC.

RESULT WILL BE AN EAST OR SOUTHEAST FLOW IN THE LOW LEVELS WHICH
WILL PROMOTE CLOUDY SKIES MUCH OF THE TIME AND ALSO TEMPER WARMING.
THE DEGREE TO WHICH WARMING IS TEMPERED DIFFERS BETWEEN THE NAM AND
GFS DERIVED MOS GUIDANCE...WITH THE GFS BEING LOWER BY 10 DEGREES
IN SOME CASES FOR MAXIMA. DIFFERENCES ARE LIKELY EXPLAINED BY THE
PRESENCE OF PRECIPITATION OR LACK THEREOF.

THE GFS IS MUCH MORE AGGRESSIVE BRINGING MEASURABLE RAINFALL ACROSS
THE CWA WHILE THE NAM IS MORE CONSERVATIVE. SREFS FORMS A NICE
COMPROMISE...FOCUSING SHOWERS /AND PERHAPS A FEW THUNDERSTORMS/
ACROSS THE SOUTHWEST PORTION OF THE CWA SATURDAY AND THEN
SPREADING CHANCES /OR LIKELIHOODS/ FOR RAINFALL NORTHEAST INTO
SUNDAY. MOISTURE IS CERTAINLY THERE...WHETHER ISENTROPIC LIFT
WORKS THIS FAR NORTH AND WHETHER THERE ARE SHORTWAVES IN 500 MB
FLOW IS SOMEWHAT IN QUESTION.

FOR TEMPERATURES...HAVE TAKEN A BLEND OF BIAS CORRECTED MAV/MET AND
ALSO ECMWF WHICH FAVORS LOWER 70S ACROSS MUCH OF THE AREA FOR
MAXIMA. NO MATTER HOW ONE SLICES IT...MAXIMA OVER THE WEEKEND WILL
LIKELY BE BELOW NORMAL WITH NEAR TO SLIGHTLY ABOVE NORMAL MINIMA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
FRONTAL BOUNDARY WILL LIFT BACK TO THE NORTH AS WARM FRONT EARLY
NEXT WEEK...MOST LIKELY LATE MONDAY INTO EARLY TUESDAY AND PLACING
THE CWA IN A WARM SECTOR DURING THE MIDDLE OF THE WEEK. THIS SHOULD
BRING LOW LEVEL SOUTH-SOUTHWEST FLOW WHICH WILL KEEP MOISTURE ACROSS
THE AREA AND SOME SURFACE-BASED INSTABILITY. THEREFORE FORECAST
REFLECTS A CHANCE OF MAINLY DIURNAL CONVECTION EACH DAY. FRONTAL
BOUNDARY MAY APPROACH ON THURSDAY.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
AREAS TO THE SOUTH AND WEST OF KCHO WILL REMAIN THE TARGET FOR
ISOLATED SHOWERS/STORMS LATER TODAY. OUTSIDE OF THIS AREA...ONLY A
FEW BATCHES OF MID/UPPER CLOUD DECKS TODAY...SO SOLID VFR
CONDITIONS THRU THE TAF PERIOD. A LIGHT NELY FLOW THIS MRNG WILL
EVENTUALLY SWITCH SELY LATER TONIGHT.

EAST-SOUTHEAST FLOW DEVELOPS THIS WEEKEND. IT IS BECOMING MORE
LIKELY THAT A PERIOD OF MVFR/IFR CIGS WILL DEVELOP SATURDAY NIGHT
INTO EARLY SUNDAY AND AGAIN SUNDAY NIGHT INTO EARLY MONDAY BEFORE A
STALLED FRONTAL BOUNDARY WORKS BACK TO THE NORTH AS A WARM FRONT
EARLY NEXT WEEK. PRECIPITATION WOULD LIKELY BE SHOWERS OVER THE
WEEKEND...THEN THUNDERSTORMS WILL BE POSSIBLE EARLY TO MID NEXT WEEK
IN THE WARM SECTOR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
LIGHT WINDS TODAY AND TONIGHT...AS A WEAK FRONTAL BOUNDARY SLIDES
SOUTHWARD. BEHIND THE FRONT...WINDS WILL COME DOWN FROM THE NE FOR
THE MRNG AND EVENTUALLY TURN SELY LATER TODAY AS THE BOUNDARY
DROPS SOUTH OF THE TP/CHES BAY CONFLUENCE REGION.

FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE WATERS THROUGH THE WEEKEND
BEFORE LIFTING BACK TO THE NORTH EARLY NEXT WEEK. EAST-SOUTHEAST
FLOW IS EXPECTED BUT WITH A RELATIVELY WEAK GRADIENT WINDS ARE
GENERALLY EXPECT TO REMAIN BELOW SCA CRITERIA. WINDS TURN TO THE
SOUTH EARLY NEXT WEEK.
-- End Changed Discussion --

&&

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

&&

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