AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
418 AM EDT FRI JUL 8 2011

.SYNOPSIS...
AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL AMPLIFY TODAY AS IT
APPROACHES THE REGION FROM THE WEST. THIS WILL PUSH A SLOW MOVING COLD
FRONT THROUGH THE MID ATLANTIC STATES LATE TONIGHT THROUGH SATURDAY.
DRIER CONDITIONS WILL MOVE INTO THE AREA FROM SATURDAY EVENING
THROUGH SUNDAY...AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.

&&

.NEAR TERM /THROUGH TONIGHT/...
00Z SUITE OF NAM/GFS/ECMWF REMAIN IN GOOD AGREEMENT WITH
MID/UPPER LEVEL PATTERN OF AN AMPLIFYING TROUGH OVER THE OHIO/TN
VALLEYS TODAY...CROSSING THE MTNS LATE TONIGHT THROUGH MIDDAY SAT.
ALL MODELS SHOW THE TROUGH BECOMING LESS PROGRESSIVE/FLATTENING
OUT FARTHER SOUTH TOWARDS SOUTHERN VA/NC. THIS WILL ALLOW THE
FRONT TO SLOW ITS SE PROGRESSION SIGNIFICANTLY...AND VIRTUALLY
STALL OVER THE REGION BETWEEN 00Z-12Z/SAT. UPPER DYNAMICS WITH THIS
SYSTEM ARE RATHER IMPRESSIVE FOR EARLY JULY...WITH A DECENT SWATH
OF RRQ UPPER JET FORCING (70-75 KT JET CORE AT 300 MB). WITH THE
WITH SOME MINOR DIFFERENCES...THE MODELS TEND TO FOCUS THE MOST
FAVORABLE COMBINATION OF LOW-MID LEVEL FGEN AND QVECTOR
CONVERGENCE OVER ABOUT THE NORTHERN 1/3 OF THE CWA FROM 00-09Z
TONIGHT. HAVE HOISTED A FLASH FLOOD WATCH FOR THESE AREAS...APPROXIMATED
FROM FLUVANNA COUNTY EAST TO THE NRN NECK AND ON INTO THE MD ERN
SHORE. ELSEWHERE...UPPER SUPPORT IS SLIGHTLY WEAKER SO CONFIDENCE
FOR A WATCH IS TOO LOW ATTM. HOWEVER...DEEP LAYER MOISTENING WILL
AFFECT THE ENTIRE CWA AS PWATS CLIMB TO OR JUST ABOVE
2.25"...THEREFORE HAVE CONTINUED WITH THE LIKELY (>50%) POPS WITH
THE FRONTAL PASSAGE...AS WELL AS WITH THE LOCALLY HEAVY RAIN
MENTION DURING THIS PERIOD. WILL ALSO HIGHLIGHT THE RISK OF
LOCALLY HEAVY (LOCALIZED FLOODING) IN THE HWO.

OTHER CONCERN WILL BE SEVERE POTENTIAL...SHEAR INCREASES LATER THIS
AFTN SO THERE WILL BE AN ENHANCED RISK FOR SEVERE STORMS MAINLY
FROM MID-LATE AFTN THROUGH THE EVENING. LIMITING FACTOR WILL BE
HOW MUCH SUN WE CAN GET...BUT TRENDS INDICATE THERE MAY BE A GOOD
DEAL OF SUNSHINE THIS MORNING FOR SIGNIFICANT DESTABILIZATION.
WITH VERY MOIST AIRMASS MAIN SEVERE THREAT WILL BE WET MICROBURSTS
ALTHOUGH LARGE HAIL WILL BE POSSIBLE WITH STRONGEST STORMS. HIGHS
WILL GENLY RANGE FROM THE MID-UPPER 80S NW TO AROUND 90 SE.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
WILL LINGER HIGH CHANCE (50%) TO LIKELY (60%) POPS THROUGH LATE
SAT MORNING...HIGHEST SOUTH AND EAST. HAVE ALSO SLOWED THE
DRYING/CLEARING TREND OVER SRN ZONES AND HAVE BUMPED AFTN POPS UP
AS FINAL SHORTWAVE DIVES SE THROUGH SRN VA DURING THE LATE
MORNING OR AFTN HRS. DRIER AIR MOVING IN BY LATE AFTN FROM THE N.
HIGHS SAT 85-90...COOLEST SE WHERE CLOUDS HANG AROUND THE LONGEST.
COOLER SAT NIGHT WITH LOWS INTO THE 60S OVER NW 1/2 OF
CWA...AROUND 70 SE. DRY ON SUN WITH SEASONABLY WARM TEMPS (HIGHS
FROM THE MID 80S ALONG THE ATLC COAST TO THE LOWER 90S FARTHER
INLAND).

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
GOING WITH A COMBINATION OF THE 12Z GFS/ECMWF FOR THE EXTENDED
PERIOD. HI PRES MOVING OFF THE NRN MID ATLC CST WILL MAINTAIN DRY WX
SUN NGT AND MON. A COLD FRONT WILL APPROACH FM THE NNW LATE MON NGT
THEN PUSH INTO AND ACRS THE REGION TUE INTO WED. THIS WILL RESULT IN
ANOTHER SLGT OR SML CHC OF SHOWERS AND TSTMS. HI PRES WILL BLD BACK
IN FM THE NNE FOR LATE WED THRU THU.

MIN TEMPS WILL BE IN THE UPR 60S TO LWR 70S MON MORNG...IN THE LWR
TO MID 70S TUE AND WED MORNGS...AND IN THE MID 60S TO LWR 70S THU
MORNG. MAX TEMPS WILL BE IN THE UPR 80S TO MID 90S MON...IN THE UPR
80S TO LWR 90S TUE...IN THE MID 80S TO NEAR 90 WED...AND IN THE MID
TO UPR 80S THU.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
PATCHY MFVR FOG/STRATUS WILL DISSIPATE BY MID MORNING. FOCUS THEN
TURNS TO EXPECTED WIDESPREAD SHOWERS AND THUNDERSTORMS THIS
AFTERNOON AND EVENING AT ALL TAF SITES. HAVE INCLUDED CB REMARKS
BEGINNING BETWEEN 19 AND 23Z. MVFR TO LCL IFR CONDITIONS WILL BE
COMMON IN THE HEAVIEST THUNDERSTORMS LATE TODAY INTO TONIGHT.

OUTLOOK...SCTD CONVECTION IS EXPECTED THROUGH MIDDAY SATURDAY. A
COLD FRONT WILL PUSH ACROSS THE REGION LATE SATURDAY AND VFR/DRY
CONDITIONS ARE IN STORE FOR SUNDAY AND MONDAY. THERE IS A CHC FOR
TSTMS ON TUESDAY.

&&

.MARINE...
S-SW FLOW WILL CONTINUE TODAY IN ADVANCE OF A SLOW MOVING COLD
FRONT. EXPECTING WINDS GENERALLY IN THE 10-15 KT RANGE...EXCEPT
15-20 KT SOUTH OF THE VA/NC BORDER WITH A FEW GUSTS UP TO 25 MPH BY
LATE TODAY. SEAS MAY BRIEFLY BUILD TO BETWEEN 4-5 FT ON THE COASTAL
WATERS THIS EVENING/OVERNIGHT AS SE SWELL INCREASES DUE TO THE LARGE
FETCH AROUND A LARGE CENTRAL ATLANTIC HIGH. HOWEVER... CONFIDENCE IS
NOT HIGH ENOUGH ATTM THAT SEAS WILL REACH 5 FT SO AN SCA IS NOT
WARRANTED. WAVES ON THE BAY/CURRITUCK SOUND WILL REMAIN UNDER 2 FT.
THE FRONT MOVES OVER THE WATERS LATE TONIGHT/EARLY SAT WITH WINDS
BECOMING MORE WESTERLY...THEN N-NE ON SAT. WINDS WILL GENERALLY BE
IN THE 10-15 KT RANGE TONIGHT/SAT. HIGH PRESSURE WILL BUILD TO THE
NNE AND OFF THE COAST FOR LATE SAT THRU MON. ANOTHER COLD FRONT WILL
DROP INTO THE REGION DURING TUE.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...FLASH FLOOD WATCH FROM 3 PM EDT THIS AFTERNOON THROUGH
     SATURDAY MORNING FOR MDZ021>025.
NC...NONE.
VA...FLASH FLOOD WATCH FROM 3 PM EDT THIS AFTERNOON THROUGH
     SATURDAY MORNING FOR VAZ048-049-062>064-074>077.
MARINE...NONE.

&&

$$
SYNOPSIS...LKB