Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 241846
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
246 PM EDT THU JUL 24 2014

.SYNOPSIS...
A COLD FRONT WILL SLOWLY PASS THROUGH SOUTHERN VIRGINIA TODAY.
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH FRIDAY BEFORE
MOVING OFF THE COAST DURING THE WEEKEND. A COLD FRONT WILL PASS
THROUGH THE AREA EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH WILL CONTINUE TO APPROACH THE MID-ATLANTIC
THIS AFTERNOON. A SHORTWAVE TROUGH HAS MOVED INTO WV AND CONVECTION
HAS INITIATED ACROSS THE APPALACHIANS. THIS ACTIVITY WILL CONTINUE
TO MOVE E-SE AND STAY IN THE VICINITY OF THE COLD FRONT THAT IS
IN SRN VA. THE FOOTHILLS AND PIEDMONT REGION IN THE MID-ATLANTIC
ARE STILL TAPPING INTO 500-1000 J/KG OF CAPE AND SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED AND TRACKED E-SE. THIS ACTIVITY WILL
SLOWLY MOVE SOUTH AS THE FRONT SLOWLY MOVES SOUTHWARD AND BE NON-
SEVERE IN THIS REGION.

DRY NRLY FLOW HAS ADVECTED INTO THE REGION BEHIND THE COLD FRONT
AND DEWPTS HAVE DROPPED IN THE 50S NEAR THE MASON DIXON LINE TO
THE UPPER 60S AT CHO. DEWPTS WILL CONTINUE TO DROP FROM NORTH TO
SOUTH TONIGHT AS THE COLD FRONT MOVES AWAY FROM THE REGION.

THE UPPER LEVEL TROUGH AXIS WILL CROSS THE REGION OVERNIGHT AND DRY
AND COOLER CONDITIONS WILL ENSUE. FCST MIN TEMPS RANGE FROM THE
UPPER 50S IN THE HIGHLANDS TO THE LOW TO MID 60S NEAR I-95 CORRIDOR.
HIGH PRESSURE WILL MOVE INTO THE REGION FRIDAY. THE CENTER OF THE
HIGH MOVES OFF THE COAST BY FRIDAY AFTERNOON AND LIGHT RETURN FLOW
MOVES INTO THE REGION. FCST MAX TEMPS ARE IN THE LOW TO MID 80S. A
CU FIELD SHOULD DEVELOP AS MOISTURE ALOFT PERSISTS. A FEW SHOWERS
MAY BE POSSIBLE IN THE CENTRAL FOOTHILLS AS MOISTURE CREEPS INTO
THE REGION FRI AFTERNOON. CONFIDENCE OF SHOWERS IS LOW AT THIS
TIME.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...

WESTERLY ZONAL FLOW ALOFT WILL CONTINUE INTO SATURDAY AS THE HIGH
MOVES WELL OFF THE EAST COAST. A SHORTWAVE TROUGH MAY CROSS NORTH OF
THE REGION SATURDAY AND SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE
NEAR THE MASON DIXON LINE. A LEE TROUGH IS EXPECTED TO FORM AND MAY
INITIATE THUNDERSTORMS. MOISTURE BEGINS TO POOL INTO THE REGION WITH
INCREASE PWATS AND THETA-E ADVECTION. FCST MAX TEMPS WILL BE IN
THE UPPER 80S.



&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A TROUGH TO THE EAST OF THE APPALACHIAN MOUNTAINS SATURDAY NIGHT AND
PASSING UPPER LEVEL ENERGY MAY BE ENOUGH TO SPAWN A COUPLE OF
SHOWERS AND THUNDERSTORMS.

THERE IS A BETTER CHANCE FOR HEAVIER SHOWERS AND GUSTY THUNDERSTORMS
SUNDAY AND SUNDAY NIGHT AS THE MAIN UPPER LEVEL FEATURE OVER THE
GREAT LAKES BEGINS TO TREK ITS WAY EASTWARD...ALLOWING A SURFACE LOW
PRESSURE TO DEVELOP ALONG THE ALREADY-ESTABLISHED TROUGH OF LOW
PRESSURE ALONG THE SHENANDOAH VALLEY. THE MAIN THREAT FROM THE
THUNDERSTORMS WILL BE DAMAGING WINDS AS LAPSE RATES APPEAR FAVORABLE
AND MID LEVEL AND UPPER LEVELS MAY BE STRONGER THAN RECENT DAYS.

AS THE MAIN UPPER LEVEL STORM MOVES INTO SOUTHEAST CANADA MONDAY
INTO MONDAY NIGHT...ITS ASSOCIATED SURFACE COLD FRONT WILL PUSH TO
THE EAST COAST BY TUESDAY MORNING. AHEAD OF THE FRONT...PERHAPS ONE
FINAL ROUND OF SHOWERS AND THUNDERSTORMS COULD DEVELOP IN THE REGION
MONDAY INTO MONDAY EVENING.

TUESDAY AND WEDNESDAY WILL BE NOTICEABLY DRIER AND COOLER WITH HIGH
PRESSURE BUILDING IN FROM THE WEST.

A GRADUAL RETURN FLOW THURSDAY WILL BRING MOISTURE BACK INTO THE
REGION. HIGH PRESSURE WILL BE OFFSHORE BY THIS TIME. SOME WEAK UPPER
LEVEL ENERGY WILL SLIDE NORTHWARD AND COULD SPAWN A SHOWER OR
THUNDERSTORM IN THE HIGHER TERRAIN.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED TODAY AND TONIGHT. SHOWERS WILL TAPER OFF
THIS AFTERNOON AND EVENING AS A COLD FRONT ACROSS SRN VA MOVES AWAY
FROM THE REGION. WINDS WILL REMAIN OUT OF THE N AT 5-10 KTS.

HIGH PRESSURE WILL MOVE INTO THE REGION TONIGHT AND CONTINUE FRIDAY.
VFR CONDITIONS EXPECTED FRIDAY. SOUTHERLY FLOW WILL BEGIN FRIDAY
AFTERNOON AND CONTINUE INTO SATURDAY. SHOWERS AND THUNDERSTORMS
POSSIBLE SATURDAY AFTERNOON.

MVFR OR IFR CONDITIONS COULD DEVELOP WITH SHOWER AND THUNDERSTORM
ACTIVITY SATURDAY NIGHT...MAINLY NEAR CHO AND MRB TERMINALS.
SOUTHERLY WINDS AT 5 TO 10 KNOTS BUT GUSTING 15 TO 20 KNOTS CLOSE
TO THE CHESAPEAKE BAY.

IFR CONDITIONS MAY BE MORE LIKELY AT ANY OF THE TERMINALS SUNDAY
INTO SUNDAY NIGHT WITH HEAVY SHOWERS AND GUSTY THUNDERSTORMS. SOUTH
WINDS BECOMING SOUTHWEST AROUND 10 KNOTS AND GUSTING 15 TO 20 KNOTS
NEAR THE BAY.

VFR CONDITIONS ON MONDAY WITH HIGH PRESSURE BUILDING IN FROM THE
WEST. WINDS BECOMING WEST AT 10 KNOTS WITH AN APPROACHING COLD
FRONT.

&&

.MARINE...
A COLD FRONT WILL CONTINUE TO MOVE AWAY FROM THE WATERS TODAY.
NORTHERLY CHANNELING IS EXPECTED TODAY AND WINDS SHOULD INCREASE
LATE TONIGHT AND INTO FRIDAY MORNING. A SCA IS IN EFFECT DURING
THIS TIME FOR THE MD CHESAPEAKE BAY SOUTH OF POOLES ISLAND AND THE
LOWER TIDAL POTOMAC. HIGH PRESSURE MOVES OVER THE WATERS FRIDAY
AND WINDS WILL SUBSIDE BEFORE BECOMING SOUTHERLY BY FRI AFTERNOON.
SRLY WINDS WILL CONTINUE INTO SATURDAY.

SMALL CRAFT ADVISORIES MAY BE NEEDED SATURDAY NIGHT THROUGH MONDAY
WITH GUSTY SOUTHWEST TO WESTERLY WINDS AHEAD OF A COLD FRONT.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 8 AM EDT FRIDAY FOR
     ANZ531>534-537-539>543.

&&

$$
SYNOPSIS...HAS
NEAR TERM...HAS
SHORT TERM...HAS
LONG TERM...KLW
AVIATION...HAS/KLW
MARINE...HAS/KLW







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