-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 181753
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
153 PM EDT SAT MAY 18 2013

.SYNOPSIS...
A WEAK FRONT REMAINS NEARLY STATIONARY OVER SOUTHWEST VIRGINIA AND
NORTH CAROLINA THROUGH TONIGHT. THE FRONT WILL SLOWLY LIFT BACK TO THE
NORTH LATER SUNDAY INTO MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
1 PM UPDATE...A PERSISTENT AREA OF SHOWERS WILL CONTINUE ACROSS
NORTHERN PORTIONS OF THE FA NORTH OF RICHMOND AND EAST TO THE
LOWER EASTERN SHORE AND HAVE LIKELY POPS IN THESE AREAS. OTHER
SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE AFTN ACROSS
PIEDMONT...SOUTH CENTRAL VIRGINIA AND NORTHEAST NORTH CAROLINA.
SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE OVER
SOUTHEAST VIRGINIA.

MOST SURFACE WINDS WERE FROM THE EAST WITH SOUTHERLY WINDS
DEVELOPING ACROSS NORTHEAST NORTH CAROLINA AND SOUTHEAST VIRGINIA.
A POORLY DEFINED FRONT EXTENDS CLOSE TO THE VA/NC BORDER THEN
BENDS NORTHWEST THROUGH WEST VIRGINIA TOWARD THE OHIO VALLEY. THIS
FRONT WILL MEANDER THROUGH THE SAME AREA AND MAY MOVE BACK TO THE
SOUTH OVERNIGHT.

ANY SHOWER AND THUNDERSTORM ACTIVITY THIS AFTN WILL BE CAPABLE OF
PRODUCING HEAVY DOWNPOURS WITH PRECIPITABLE WATER VALUES AROUND
1.5 INCHES WHICH IS WELL ABOVE NORMAL.

HAVE LOWERED TEMPERATURES SLIGHTLY OVER SRN PORTIONS OF THE AREA FOR
THE REST OF THE AFTN...BASED ON TRENDS AND LATEST LAV GUIDANCE.
HAVE MAX READINGS FROM AROUND 70 ON THE LOWER ERN SHORE AND LOW TO
MID 70S N OF INTERSTATE 64 TO UPR 70S ALONG OUR SRN BORDER.

TONIGHT...LATEST INDICATIONS ARE THAT SHOWER AND TSTM ACTIVITY
WILL DIMINISH THIS EVENING WITH MOST AREAS REMAINING DRY
OVERNIGHT. WILL KEEP AT LEAST 20 TO 40 PERCENT POPS ACRS THE AREA
DUE TO LOW LEVEL INSTABILITY. LOW TEMPERATURES WILL BE GENERALLY
IN THE LOW TO MID 60S WITH UPR 50S ON THE MD EASTERN SHORE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
WET WEATHER WILL CONTINUE THROUGH THE SHORT TERM AS THE STALLED
FRONT BEGINS TO LIFT NWD AS A WARM FRONT SUN AND MON. MAIN
FORECAST CHALLENGES WILL BE TIED TO PRECIP COVERAGE AND QPF.

WEAKENING UPPER LOW EXPECTED TO MEANDER IN THE VICINITY OF THE
CUMBERLAND PLATEAU SUNDAY. POTENT TROUGH TRAVERSING THE PLAINS SUN
WILL AMPLIFY THE RIDGE OVER THE ERN CONUS...HELPING LIFT THE
STALLED BOUNDARY NWD AS A WARM FRONT LATE SAT NIGHT AND SUN. AT
THE SAME TIME...INCREASING SW FLOW (H85 WINDS 20-30 KT) WILL
ADVECT NEARLY +2 STD DEV PRECIP WATER VALUES INTO THE REGION.
ADDITIONAL WEAK IMPULSES WILL EJECT EWD FROM THE UPPER
LOW...COMBINING WITH ABUNDANT MOISTURE FOR ADDITIONAL SHOWERS AND
THUNDERSTORMS DURING THE AFTERNOON AND EVENING SUN. THETA-E
ADVECTION AND TEMPS IN THE UPPER 70S/LOW 80S WILL MAINTAIN A
MARGINALLY UNSTABLE AIRMASS (500-1000 J/KG CAPE) OVER SRN
VA...RESULTING IN A GOOD CHANCE FOR AFTERNOON THUNDERSTORMS.
COMBINATION OF CONVECTION AND DEEP MOISTURE COULD LEAD TO A THREAT
OF FLASH FLOODING...ESPECIALLY IF WIDESPREAD RAINFALL OCCURS THIS
AFTERNOON (SAT AFTERNOON).

MIDWEST TROUGH WILL KICK WHATS LEFT OF THE UPPER LOW EWD MONDAY OVER
THE APPALACHIANS...LOCATING OVER THE FA MONDAY. MEANWHILE...THE
WARM FRONT WILL LIFT NORTH OF THE FA. ABUNDANT MOISTURE AND GOOD
DYNAMICS WILL RESULT IN ADDITIONAL SHOWERS AND THUNDERSTORMS.
WARMER TEMPS WILL RESULT IN GREATER INSTABILITY...WITH ADDITIONAL
ROUNDS OF HEAVY RAIN POSSIBLE.

72 HR QPF TOTALS FORECAST TO RANGE FROM OVER 2 INCHES ACROSS THE
PIEDMONT TO JUST OVER HALF AN INCH FOR THE MD ERN SHORE. SE VA/NE
NC COULD SEE TOTALS UPWARDS OF ONE INCH. IN ADDITION TO THE FLASH
FLOOD THREAT...SEVERAL ROUNDS OF RAINFALL OVER THE REGION MAY LEAD
TO RIVER FLOODING CONCERNS.

HI TEMPS WILL GENERALLY RANGE FROM THE LOW/MID 70S NORTH TO LOW
80S SOUTH (NEAR SEASONABLE NORMS) SUN. COOLER ALONG THE IMMEDIATE
COAST. WARMER MONDAY WITH HIGHS GENERALLY IN THE LOW 80S.
AGAIN...COOLER ALONG THE IMMEDIATE COAST.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
LONG TERM PERIOD WILL FEATURE PERIODS OF UNSETTLED WX AND ABOVE
NORMAL HI/LO TEMPS ON AVG. FOR TUE...MID-LVL S/W TROF PUSHES
OFFSHORE ERLY IN THE DAY WITH A CHC FOR SHWRS MAINLY OVER SE AREAS.
DECREASING CLDS DURING THE AFTN WITH TEMPS CLIMBING INTO THE MID
80S. S/SW FLOW CONTINUES WED AND THU LEADING TO CONTINUED WARM TEMPS
(HIGHS IN THE MID TO UPR 80S) AND A CHC FOR MAINLY DIURNAL SHWRS/TSTMS
WITH WEAK SFC TROFS OVER THE AREA. BEST CHC FOR RAIN WILL BE FRI AS
A COLD FRNT ADVANCES TOWARDS THE AREA. WILL CAP POPS AT 40% FOR
NOW WITH HOW FAR OUT IN TIME THIS IS ALBEIT FAIRLY GOOD
CONSISTENCY AMONGST MODEL GUIDANCE WITH THE FRNTAL TIMING. HI
TEMPS ONLY IN THE UPR 70S TO NEAR 80 FRI DUE TO PRECIP AND
WIDESPREAD CLOUDINESS.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
TRICKY AVIATION FORECAST THIS AFTERNOON THROUGH SUNDAY. SHOWERS
FROM RIC TO SBY WERE SLOWLY PUSHING EAST AND SHOULD MAKE THEIR WAY
TO PHF AROUND 19-20Z. EVEN WITH THE SHOWERS CONDITIONS AT RIC WERE
MVFR AS OF 1730Z AND SHOULD REMAIN MVFR WITH A BRIEF PERIOD OF IFR
THROUGH 22Z AS PERIODS OF RAIN REDUCE VSBYS TO JUST BELOW 3SM AND
THE NE FLOW DROPS CEILINGS TO JUST LESS THAN 1KFT. AT SBY
PREVAILING IFR CONDITIONS SHOULD HOLD OFF UNTIL AROUND 06Z WHEN
SE WINDS INCREASE AND STRATUS MOVES IN FROM THE OCEAN. THE SHOWERS
NEAR RIC TO PTB SHOULD REACH PHF SHORTLY AFTER 20Z AND MVFR
CONDITIONS AT PFH COULD BECOME BRIEFLY IFR WITH A FEW HEAVER
SHOWERS THROUGH 23Z. ONCE THE COVERAGE IN SHOWER ACTIVITY
DECREASES WITH SUNSET MVFR CONDITIONS WILL PREVAIL AT PHF.

MORE SHOWERS WERE ONGOING FROM NEAR ECG WEST ALONG THE NC/VA
BORDER ALONG ANOTHER BOUNDARY. THIS AREA OF SHOWERS MAY EXPAND
BRIEFLY BUT THE BULK OF THE RAIN MAY STAY WEST OF ORF AND ECG THIS
AFTN AND EVENING. A BRIEF PERIOD OF SHOWERS MAY REACH ORF FROM
21Z-02Z BUT SHOWER ACTIVITY SHOULD BE VERY SCATTERED AS FAR EAST
AS ORF AND PHF. OVERALL CONDITIONS AT ORF AND PHF SHOULD REMAIN
MVFR WITH A BRIEF PERIOD OF IFR POSSIBLE IN THE SHOWERS.

GUIDANCE SUGGESTS RIC WILL BECOME IFR WITH STRATUS OVERNIGHT ALONG
WITH SBY AND REMAIN IFR THROUGH MID MORNING SUNDAY. CLOSER TO THE
COAST THE REMAINDER OF THE TAF SITES REMAIN MVFR OVERNIGHT. FOR
SUNDAY EXPECT MUCH OF THE SAME WITH MVFR-VFR CONDITIONS OVER SE VA
AND NE NC AND MVFR-IFR CONDITIONS AT RIC AND SBY.
-- End Changed Discussion --


&&

.MARINE...
A WEAK FRONTAL BOUNDARY ACROSS THE REGION IS BEGINNING TO SLOWLY
LIFT NE AS A WARM FRONT EARLY THIS MORNING. THIS SLOW PROCESS IS
EXPECTED TO CONTINUE THROUGH THE DAY INTO TONIGHT. MEANWHILE...HIGH
PRESSURE WILL REMAIN ANCHORED OFF CAPE COD AS TROUGH OF LOW PRESSURE
APPROACHES FROM THE WEST. THIS WILL RESULT IN A TIGHTENING PRESSURE
GRADIENT ACROSS THE REGION LATER THIS AFTERNOON INTO TONIGHT. A
10-15KT ESE WIND IS EXPECTED TO APPROACH 20KT LATER THIS AFTERNOON
THROUGH THIS EVENING FOR THE BAY/LOWER JAMES. SIMILAR SPEEDS ARE
EXPECTED FOR THE OCEAN. HOWEVER...THE ONSHORE COMPONENT TO THE WIND
SHOULD ALLOW SEAS TO BUILD TO 5FT LATER TODAY INTO TONIGHT...MAINLY
N OF CAPE CHARLES. HENCE SCA FLAGS HAVE BEEN RAISED FOR THE
AFOREMENTIONED AREAS BEGINNING AT 20Z/4PM THIS AFTERNOON AND
CONTINUING THROUGH 04Z/12AM FOR THE BAY/LOWER JAMES AND 10Z/6AM FOR
THE OCEAN. THE WARM FRONT FINALLY CLEARS THE REGION LATER SUNDAY
AFTN/EVE ALLOWING FOR THE WIND TO SHIFT TO S AND EVENTUALLY SW.
SPEEDS SHOULD GENERALLY REMAIN AOB 15KT. HOWEVER...A BRIEF INCREASE
IS POSSIBLE MONDAY AFTN/EVE AS LOW PRESSURE TRACKS N OF THE REGION.
SEAS SHOULD LARGELY BE 3-4FT WITH ~2FT WAVES.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ630>632-
     634-638.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ650-652-654.

&&

$$
SYNOPSIS...LKB/LSA
NEAR TERM...LSA
SHORT TERM...SAM
LONG TERM...MAS
AVIATION...JAO
MARINE...AJZ