-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 170848
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
448 AM EDT FRI MAY 17 2013

.SYNOPSIS...
A WEAK FRONT MOVES SOUTH ACROSS VIRGINIA EARLY THIS MORNING INTO
THIS AFTERNOON...THEN STALLS OVER NORTH CAROLINA ON SATURDAY. THE
FRONT WILL SLOWLY LIFT BACK TO THE NORTH ON SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE MOVING THROUGH THE
CAROLINAS AND A WEAKENING UPPER LOW LOCATED OVER THE MID MS RIVER
VALLEY. AT THE SFC...WEAK FRONTAL BOUNDARY IS LOCATED OVER SRN PA
EXTENDING WWD INTO THE OH VALLEY. OVER THE LOCAL AREA...WEAK SFC
TROUGH IS LOCATED OVER ERN VA INTO N CNTRL NC. SHORTWAVE OVER THE
CAROLINAS WILL CONTINUE TO PROGRESS EWD...PUSHING OFFSHORE EARLY
THIS MORNING...BRINGING AN END TO PRECIP CHANCES THIS MORNING.
CALM WINDS AND A MOIST BOUNDARY LAYER WILL BE ENOUGH TO PRODUCE
SOME SHALLOW FOG EARLY THIS MORNING IN AREAS THAT SEE A FEW BREAKS
IN THE CLOUDS. DO NOT EXPECT ANYTHING WIDESPREAD.
OTHERWISE...CONFLUENCE OVER THE NE WILL ALLOW HIGH PRESSURE TO
BUILD OVER THE GREAT LAKES...EXTENDING SEWD INTO FAR NE VA. UPPER
LEVEL RIDGE WILL ALSO AMPLIFY OVER THE CNTRL CONUS. THE RESULTANT
AMPLIFYING PATTERN WILL NUDGE THE SFC BOUNDARY SWD ACROSS THE
LOCAL AREA THIS MORNING...REACHING THE NC/VA BORDER EARLY THIS
AFTERNOON. THE MIDWEST UPPER LOW WILL LOSE UPPER LEVEL
SUPPORT...SO EXPECT VERY LITTLE MOVEMENT TODAY.

FOR THIS AFTERNOON...LOW LEVEL SW FLOW AND MOISTURE ADVECTION WILL
RETURN AS H85 HIGH PRESSURE POSITIONS OFF THE SE COAST. BEST
MOISTURE RETURN WILL BE OVER THE SRN FA WHERE PRECIP WATERS
PROGGED TO BE AROUND 1.5 INCHES (+1 STD DEV) ALONG THE BOUNDARY.
WEAK IMPULSES ROUNDING THE BASE OF THE MIDWEST LOW WILL EJECT
EWD...PROVIDING SUBTLE FORCING FOR ASCENT. HOWEVER...EXPECT BEST
FORCING TO BE DIURNALLY DRIVEN UNDER MAX HEATING. WILL MAINTAIN
SLIGHT CHANCE/CHANCE POPS OVER THE SE FA. THETA-E ADVECTION AND
WARM TEMPS WILL PROVIDE MARGINAL INSTABILITY (500-1500 J/KG CAPE)
FOR THUNDERSTORMS. MAIN THREATS WILL BE LOCALLY HEAVY RAINFALL AND
STRONG (NOT DAMAGING) WINDS. FALLING H85 TEMPS AND LOW LEVEL
THICKNESSES WILL RESULT IN SLIGHTLY COOLER TEMPS TODAY COMPARED TO
THE PREVIOUS FEW DAYS WITH HIGHS IN THE (MID 80S).

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE SHORT TERM AS THE
FRONT STALLS ACROSS NC. MIDWEST UPPER LOW WILL CONTINUE TO SLOWLY
PROGRESS EWD SAT...LOCATING OVER THE TN VALLEY SAT AFTERNOON.
MEANWHILE...SFC HIGH PRESSURE WILL ORIENT ALONG THE NE
COAST...EXTENDING SWD INTO THE MID ATLANTIC. RESULT WILL BE
ONSHORE FLOW AND CORRESPONDING COOLING. SEVERAL WEAK SHORTWAVES
WILL PROVIDE SUBTLE FORCING FOR ASCENT IN ADDITION TO DIURNAL
FORCING (AFTERNOON HEATING). SW FLOW WILL ALSO ADVECT +1 STD DEV
PRECIP WATERS (1.25-1.50 INCHES) INTO THE MID ATLANTIC. THE RESULT
WILL BE AN EXTENDED PERIOD OF CLOUDY AND WET WEATHER. 72 HOUR QPF
AMOUNTS WILL GENERALLY RANGE FROM NEARLY 2 INCHES FROM THE SW TO
.75 INCHES E. THETA-E ADVECTION AND TEMPS IN THE LOW 80S WILL
MAINTAIN A MARGINALLY UNSTABLE AIRMASS (500-1500 J/KG CAPE) OVER
SRN VA/NE NC EACH AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL
BE IN THAT AREA.

HI TEMPS WILL GENERALLY RANGE FROM THE LOW/MID 70S NORTH TO LOW 80S
SOUTH (NEAR SEASONABLE NORMS)...COOLER ALONG THE IMMEDIATE COAST
DUE TO ONSHORE WINDS. LOW TEMPS FRI AND SAT NIGHT GENERALLY UPPER
50S/LOW 60S INLAND TO MID 60S ALONG THE COAST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE MID-ATLANTIC SUNDAY
NIGHT INTO MONDAY. THIS IS IN ADDITION TO A WEAK UPPER DISTURBANCE
PASSING OVERHEAD WILL PRODUCE A CHANCE FOR SHOWERS AND
THUNDERSTORMS. AN H5 RIDGE AXIS SHOULD BUILD OVER THEN EASTERN U.S.
TUESDAY OF NEXT WEEK...THEN SLIDES OFF TO THE EAST LATE WEDNESDAY AS
THE NEXT SYSTEM BEGINS TO IMPACT THE MID-ATLANTIC. WILL MAINTAIN
SLIGHT CHC POPS ON TUESDAY DUE TO SOME UNCERTAINTY IN THE MODELS AS
TO WHETHER OR NOT THE UPPER DISTURBANCE PUSHES FAR ENOUGH OFF THE
COAST. THE NEXT SYSTEM LOOKS LIKE IT WILL BRING A GOOD CHANCE OF
SHOWERS BY LATE WEDNESDAY INTO NEXT THURSDAY. TEMPS WILL REMAIN ON
THE WARM/MILD SIDE THROUGH THE PERIOD WITH HIGHS IN THE 70S AND 80S
AND LOWS IN THE 60S.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
A WEAK COLD FRONT WILL DROP INTO NC THIS MORNG...WITH SW OR W
WINDS LESS THAN 10 KT BECMG NNE. MAINLY JUST HI CLOUDS EXPECTED
THRU THIS MORNG WITH LIGHT PATCHY FOG POSSIBLE. FRONTAL BOUNDARY
WILL LIKELY REMAIN NEARLY STATIONARY ACRS NC THRU AT LEAST
SAT...THEN SLOWLY LIFT BACK N AS A WARM FRONT DURING SUN. CHCS FOR
SCTD SHOWERS AND TSTMS AND LWR CIGS AND VSBYS WILL INCREASE LATE
TNGT AND CONTINUE THRU SUN.

&&

.MARINE...
-- Changed Discussion --
A WEAK COLD FRONT WILL DROP ACRS SRN VA INTO NC TODAY. WNW WINDS 10
KT OR LESS EARLY THIS MORNG...WILL BECOME NNE LESS THAN 15 KT FOR
LATER THIS MORNG INTO THIS AFTN. GENERALLY E WINDS LESS THAN 15
KT THEN EXPECTED FOR TNGT THRU SAT...AS THE FRNT STALLS OVR NC.
THE FRONT WILL LIFT BACK N AS A WARM FRONT SUN INTO SUN NGT...WITH
SE OR S WINDS ARND 15 KT OR LESS. SEAS MAY BLD TO 5 FT OVR THE NRN
CSTL WTRS ON SUN.
-- End Changed Discussion --

&&

.CLIMATE...
THURSDAYS HIGH OF 90 AT SALISBURY TODAY TIES A RECORD HIGH FOR MAY 16TH
(ALSO SET IN 1944). AT RICHMOND...THE TEMPERATURE DROPPED INTO THE
60S WITH THE EVENING TSTMS...SO NO RECORDS WERE SET (THE RECORD
HIGH MIN FOR MAY 16TH REMAINS 70 F SET IN 1976).

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...LKB
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...JDM
AVIATION...TMG
MARINE...TMG
CLIMATE...AKQ