-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 191744
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
144 PM EDT SUN MAY 19 2013

.SYNOPSIS...
A WEAK FRONT OVER SOUTHERN VIRGINIA AND LIFTING SLOWLY NORTH AND WILL
DISSIPATE ACROSS MARYLAND ON MONDAY. A RIDGE OF HIGH PRESSURE OFF
THE SOUTHEAST COAST WILL DOMINATE INTO THE MIDDLE OF THE WEEK. A
COLD FRONT WILL PASS THROUGH THE MID ATLANTIC STATES AROUND
FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1 PM UPDATE...INCREASED POPS TOWARD THE COAST OVER SE VA AND NE NC
WHERE WIDESPREAD SHOWERS ARE DEVELOPING IN AREAS THAT RECEIVED
SUNSHINE THIS MORNING.

10AM UPDATE...MADE SMALL CHANGES TO THE FORECAST AND BUMPED POPS
UP SLIGHTLY OVER SOUTHEAST PORTIONS SO THAT THE ENTIRE CWA HAS
LIKELY SHOWERS. MOST OF THE AREA WILL REMAIN MOSTLY CLOUDY TO
CLOUDY BUT SIGNIFICANT BREAKS SHOULD CONTINUE TO APPEAR OVER SE VA
AND NE NC WHICH WILL PROMOTE SHOWER DEVELOPMENT IN THE AFTN. MAX
TEMPERATURE FORECAST REMAINS MOSTLY IN THE MID TO UPR 70S WITH NEAR
80 DEGREES EXPECTED OVER INTERIOR SOUTHEAST VIRGINIA. LOWEST
READINGS WILL BE IN NORTHERN PORTIONS AND ALONG THE COAST. CONTINUED
WITH ISOLATED THUNDER EXCEPT IN PORTIONS OF THE MD EASTERN SHORE.
WENT WITH ISOLATED DUE TO CONVERGENCE AND CAPE BEING WEAKER THAN THEY
WERE SATURDAY.

PREVIOUS DISCUSSION...
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW STUBBORN
UPPER LOW OVER WRN KY WITH A RATHER BROAD MID/UPPER LEVEL TROUGH
SITUATED FROM KY DOWN INTO THE CAROLINAS. AT THE SFC...STATIONARY
FRONT/BOUNDARY STILL LOCATED OVER NRN NC. AREA OF SHOWERS AND
EMBEDDED THUNDERSTORMS DEVELOPED ALONG THE BOUNDARY IN N CNTRL NC
EARLIER THIS MORNING...BUT HAVE SINCE WEAKENED AS THEY MOVED NORTH
INTO THE REGION. CLOUD TOPS HAVE WARMED...BUT A FEW SHALLOW
SHOWERS ONGOING OVER THE ERN SHORE...AIDED BY MID LEVEL
ENERGY/SHORTWAVE. RUC H7 OMEGA HANDLES THIS AREA OF SHOWERS
WELL...WITH THE SHOWERS PUSHING OFFSHORE IN THE NEXT FEW HOURS. IN
ADDITION...VERY MOIST BOUNDARY LAYER...WAA AND CALM WINDS HAVE
RESULTED IN AREAS OF FOG THIS MORNING...WITH SOME VISIBILITIES AS
LOW AS HALF A MILE IN THE RICHMOND AREA.

ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE DYING UPPER LOW
INTO A WARM/MOIST AIRMASS...WITH THE FIRST ARRIVING LATER THIS
MORNING. COOLING CLOUD TOPS ALREADY OBSERVED THIS MORNING OVER WRN
NC. PRECIP WATERS STILL AROUND 1.5 INCHES (+1 STD DEV). EXPECT
SHOWERS TO INCREASE IN COVERAGE ACROSS THE ERN VA PIEDMONT BY MID
MORNING. FOR THIS AFTERNOON...WEAKENING UPPER LOW WILL REMAIN IN
THE VICINITY OF WRN KY AS THE BOUNDARY BEGINS TO LIFT NWD AS A
WARM FRONT. SHORTWAVE WILL LIFT THROUGH VA...COMBINING WITH WEAK
DIVERGENCE ALOFT TO PROVIDE FORCING FOR ASCENT...ALBEIT WEAK.
HOWEVER...WITH ABUNDANT MOISTURE IN PLACE...IT WILL BE ENOUGH TO
TRIGGER ADDITIONAL SHOWERS THIS AFTERNOON...MAINLY ACROSS THE
PIEDMONT INTO CNTRL VA. INSTABILITY WILL BE LIMITED...BUT GOOD LOW
LEVEL LAPSE RATES AND THETA-E ADVECTION WILL BE ENOUGH FOR
SCATTERED AFTERNOON THUNDERSTORMS....MAINLY ACROSS SRN VA. S/SE
FLOW WILL LIMIT THE AMOUNT OF INSTABILITY ALONG THE COAST AND OVER
THE ERN SHORE. MID LEVEL WIND FIELDS ARE RATHER WEAK...SO THE
MAIN THREAT FROM THUNDERSTORMS WILL BE HEAVY RAIN.

ANOTHER CLOUDY/WET DAY WILL PREVENT TEMPS FROM REACHING THEIR FULL
POTENTIAL...WITH HIGHS GENERALLY IN THE MID/UPPER 70S. COLDER
ALONG THE IMMEDIATE COAST AND OVER THE ERN SHORE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
REMNANTS OF THE UPPER LOW WILL EJECT OVER THE APPALACHIANS SUNDAY
NIGHT INTO MONDAY AS A POTENT UPPER TROUGH REACHES THE MIDWEST. AT
THE SFC...WARM FRONT WILL LOCATE NORTH OF THE FA MONDAY AFTERNOON
AS HIGH PRESSURE LOCATED OVER THE WRN ATLANTIC EXTENDS WWD INTO
THE LOWER MID ATLANTIC AND SE STATES. WARM/MOIST AIRMASS WILL
BUILD IN AS S/SW FLOW ADVECTS DEEP MOIST FROM THE ATLANTIC...WITH
PRECIP WATER VALUES APPROACHING +1.5 STD DEV. WEAK SHORTWAVE AND
DIVERGENCE ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT...BUT
EXPECT MOST FORCING AND RESULTANT CONVECTION TO BE DIURNALLY
DRIVEN. WHILE THETA-E ADVECTION AND WARM TEMPERATURES WILL PROVIDE
MARGINAL INSTABILITY (500-1000 J/KG CAPE)...A WEAKENING MID LEVEL
WIND FIELD WILL PROVIDE LIMITED SHEAR. THE RESULT WILL BE
SCATTERED THUNDERSTORMS WITH VERY LITTLE ORGANIZATION. THE
SHORTWAVE AXIS PROGGED TO BE AROUND THE ERN VA PIEDMONT...WITH THE
BEST CHANCES FOR SHOWERS/THUNDERSTORMS BEING TO THE EAST OF THE
AXIS OVER CNTRL AND ERN VA.

TROUGH AXIS WILL LOCATE ALONG THE COAST TUESDAY AS THE CNTRL CONUS
TROUGH AMPLIFIES THE UPPER RIDGE OVER THE EAST. RESIDUAL MOISTURE
AND SUBTLE UVM WILL BE SUFFICIENT FOR SHOWERS ALONG THE COAST
TUESDAY AFTERNOON. DEWPOINTS IN THE MID 60S AND AFTERNOON TEMPS IN
THE LOW/MID 80S WILL RESULT IN GREATER INSTABILITY (~1500 J/KG
CAPE AND ~-6 LIFTED INDEX) FOR CONVECTION/THUNDERSTORMS. FORCING
WILL BE MOSTLY DIURNALLY DRIVEN. HOWEVER...SHEAR REMAINS WEAK SO
EXPECT NO ORGANIZED THUNDERSTORMS.

NEAR SEASONABLE NORMAL TEMPS MONDAY (UPPER 70S/LOW 80S) BEFORE A
WARMING TREND TUESDAY. INCREASING HEIGHTS/THICKNESSES...AS WELL AS
850 TEMPS APPROACHING +1 STD DEV...WILL RESULT IN TEMPS GENERALLY
IN THE MID 80S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODELS SIMILAR OVER THIS TIME PERIOD WITH THE TIMING OF ANOTHER TROF
DEEPING AT 500 MB TOWARD FRIDAY AND SATURDAY. THIS WILL USHER A
STRONGER COLD FRONT THROUGH THE REGION FRIDAY INTO SATURDAY. THE
FRONT WILL HAVE SOME SHOWERS AND THUNDERSTORMS WITH IT AS IT MOVES
THROUGH. BEFORE THAT A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY
ACROSS THE GREAT LAKES AND NEW ENGLAND. SOUTH OF THIS AREA WILL HAVE
GENERAL SOUTH TO SOUTHWEST FLOW ACROSS THE AREA. COULD SEE AN
ISOLATED AFTERNOON THUNDERSTORM. ANY THUNDERSTORMS THAT FORM NORTH
ALONG THE BOUNDARY COULD PUSH INTO THE NORTHERN PART OF THE AREA
DURING THE EVENINGS. TEMPERATURES WILL BE AT OR ABOVE NORMAL UNTIL
THE FRONT PASSES. THEN TEMPERATURES WILL DROP BACK ON SATURDAY TO AT
OR BELOW NORMAL.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
A MIX OF VFR AND MVFR CONDITIONS ACROSS THE REGION THIS AFTERNOON
WITH SHOWERS DEVELOPING FROM ECG TO ORF AND SOUTH OF RIC. EXPECT
MAINLY MVFR CONDITIONS AT RIC INTO THIS EVENING WITH A FEW SHOWERS
MOVING THROUGH AFTER 19Z. AT ORF CONDITIONS SHOULD REMAIN VFR
UNTIL HEAVIER SHOWERS REACH THE AIRPORT AROUND 19Z REDUCING VSBY
TO MVFR AND PERHAPS EVEN TEMPORARILY IFR. NELY FLOW AT ORF IS DUE
TO A WEAK BAY BREEZE AND WILL BECOME SLY THIS EVENING. JUST TO THE
NORTH PHF HAS BEEN SLOW TO IMPROVE AND WILL REMAIN MVFR FOR THE
AFTERNOON AND EVENING. SBY HAS CONTINUE TO SEE IFR CONDITIONS BUT
THIS WILL TEMPORARILY IMPROVE TO MVFR BY THIS EVENING BEFORE
RETURNING TO IFR OVERNIGHT.

SHOWERS WILL DISSIPATE WITH LOSS OF HEATING OVERNIGHT OUTSIDE OF A
FEW STRAY SHOWERS HERE AND THERE. DESPITE MOST OF THE GUIDANCE
KEEPING CONDITIONS ABOVE IFR DUE TO THE LOW LEVEL MOISTURE AND
CONTINUES BOUNDARY ACROSS THE REGION EXPECT IFR CEILINGS AND FOG TO
RE-DEVELOP OVERNIGHT AT ALL TAF SITES. THESE IFR CONDITIONS WILL
LINGER INTO MONDAY MORNING IMPROVING SLOWLY THROUGH MID MORNING.
MORE WIDESPREAD SHOWERS ARE EXPECTED MONDAY AFTERNOON AND EVENING
WITH MORE COVERAGE OF HEAVY SHOWERS THAN COMPARED TO SUNDAY.
-- End Changed Discussion --

&&

.MARINE...
S/SE WINDS PREVAIL ACROSS THE MARINE AREA THIS MORNING...WITH
SPEEDS BELOW SCA CRITERIA EVERYWHERE EVEN INTO THE AFTERNOON. WINDS
GENERALLY 10 KT THROUGH LATE MORNING INCREASING TO 10-15KT ON THE
BAY/RIVERS/SOUND...AND 10-20 KT ON THE OCEAN /HIGHEST N OF CAPE
CHARLES LIGHT/. THESE CONDITIONS EXPECTED TO PERSIST NEXT 2-3
DAYS...BEFORE WINDS BECOME SSWLY/SWLY IN THE TUE TIME FRAME.

SEAS ON THE COASTAL WATERS CONTINUE TO RUN AROUND 4-5 FEET AND
HAVE BEEN SLOWLY DECREASING OVER THE LAST FEW HOURS. WIND FORECASTS
DO NOT APPEAR TO BE SUFFICIENT TO CAUSE SEAS TO INCREASE TO 5+
FEET. HOWEVER...WAVEWATCH GUIDANCE PERSISTS IN PLACING MOST OF THE
COASTAL WATERS IN 5-6 FOOT SEAS TODAY/TONIGHT. WILL MAINTAIN SCA
FOR THE NRN 2 CSTL ZONES FOR SEAS THROUGH 00Z MON AS WINDS MAY
TEMPORARILY INCREASE THIS AFTERNOON PUSHING SEAS IN THE NORTH OF
NEAR 5 FT. SEAS EXPECTED TO SUBSIDE BELOW 5 FEET AFTER 00Z MON.

&&

.HYDROLOGY...
RIVER LEVEL FORECASTS HAVE BEEN LOWERED SUBSTANTIALLY DUE TO LACK
OF SIGNIFICANT RAINFALL IN THE HEADWATERS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ650.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ652.

&&

$$
SYNOPSIS...LKB/LSA
NEAR TERM...SAM/LSA
SHORT TERM...SAM
LONG TERM...JAB
AVIATION...JAO
MARINE...WRS
HYDROLOGY...