Area Forecast Discussion
Issued by NWS Sterling, VA

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178
FXUS61 KLWX 031857
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
257 PM EDT TUE MAY 3 2016

.SYNOPSIS...A SURFACE TROF WILL REMAIN ACROSS THE AREA THROUGH
THURSDAY. A LARGE AREA OF UPPER LEVEL LOW PRESSURE IS EXPECTED TO
IMPACT THE AREA THURSDAY AND FRIDAY BEFORE HIGH PRESSURE RETURNS
FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...DIFFERENTIAL HEATING HAS ALLOWED
A FEW SHOWERS AND T-STORMS TO DEVELOP OVER THE SRN SHENANDOAH
VALLEY. A MODIFIED ACARS 1736Z SOUNDING FROM BWI YIELDS SKYNNY
CAPE AROUND 350 J/KG. ANTICIPATING T-STORMS TO SHOW SOME WEAKENING
AS THEY MOVE FARTHER EAST INTO THE DC METRO. OVERALL...THERE IS
LITTLE FORCING TODAY FOR ORGANIZED CONVECTION OTHER THAN A WEAK
SFC TROF OR CONVERGENCE LINE BETWEEN LOW PRES OFF SOUTHEAST VA AND
DETROIT MI. AS INSTABILITY WANES TONIGHT AND ONLY WEAK FORCING IS
AVAILABLE ANTICIPATE STRATIFORM LIGHT RAIN OR DRIZZLE TO BECOME
THE MAIN PRECIP TYPE. SKIES MAY BRIGHTEN A LITTLE BIT LATE
TOMORROW BUT OTHERWISE A LOT OF CLOUDS.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...A
SHORTWAVE-TROUGH OVER THE WRN GREAT LKS WILL DIG INTO THE OH
VALLEY WED AND FORM A DEEP CLOSED LOW ALOFT. LARGE SCALE LIFT
INCREASES OVER THE AREA WED NIGHT WITH RAIN DEVELOPING NORTH OF
THE H5 LOW TRACK. A SWATH OF 1 TO 2 INCHES OF RAIN APPEARS LIKELY
ALONG AND WEST OF THE BLUE RIDGE MTNS WHERE MODELS SHOW A
CONVERGENT UPSLOPE NORTHEAST LOW-LEVEL FLOW SETTING UP. THIS
APPEARS A PROLONGED PERIOD OF MDT RAINS WHICH COULD RESULT IN SOME
FLOODING ISSUES GIVEN INCREASINGLY SOGGY CONDITIONS AND VERY SLOW
MOVEMENT OF PRECIP AREA. WE`LL NEED TO MONITOR RAINFALL TOTALS
OVER THE NEXT DAY OR SO.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...AN UPPER LEVEL DISTURBANCE WILL
MEANDER ABOUT THE NEW JERSEY COAST FRIDAY AND FRIDAY NIGHT. THE
CHANCE FOR RAIN SHOWERS WILL EXIST THROUGHOUT THE PERIOD.
TEMPERATURES WILL BE COOLER THAN NORMAL.

AS THE DISTURBANCE WEAKENS AND SLIDES SLIGHTLY TO THE NORTH...A
BRIEF RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE REGION
SATURDAY. CONDITIONS WILL BE TEMPORARILY DRY BEFORE THE NEXT
DISTURBANCE MOVES ACROSS THE GREAT LAKES...DRAGGING A COLD FRONT
SOUTHWARD INTO OUR REGION. THE RAIN CHANCES RETURN SATURDAY
NIGHT. TEMPERATURES WILL REMAIN COOLER THAN NORMAL.

THE CHANCE OF RAIN SHOWERS LINGER SUNDAY AND IN THE WEST SUNDAY
NIGHT WITH THE SURFACE FRONT AND AFFILIATED DISTURBANCE NEARBY.

THE FRONT WILL TRY TO MOVE NORTHWARD AS A WARM FRONT MONDAY
INTO TUESDAY. THIS WILL BRING BACK THREAT FOR SHOWERS OR A
THUNDERSTORM. THE BIGGER THREAT WILL BE TUESDAY. TEMPERATURES
WILL BE SLIGHTLY ABOVE NORMAL.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...MVFR CIGS EAST TAF SITES
DETERIORATING TO IFR EVERYWHERE LATE TONIGHT IN LIGHT NORTHEAST
FLOW AND DRIZZLE. A T-STORM IS POSSIBLE THIS AFTERNOON AND EARLY
EVENING AT KDCA AND KCHO.

MVFR TO IFR CONDITIONS WITH THE CHANCE OF RAIN SHOWERS FRIDAY INTO
FRIDAY NIGHT. WINDS NORTHWEST AROUND 10 KNOTS FRIDAY. WINDS
NORTHWEST 5 TO 10 KNOTS FRIDAY NIGHT.


&&

.MARINE...WINDS 10 KT OR LESS THROUGH THU MORNING INCREASING
SOMEWHAT THU AFTERNOON.

SMALL CRAFT CONDITIONS LIKELY FRIDAY AS PRESSURE GRADIENT
TIGHTENS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...KLW
AVIATION...KLW
MARINE...KLW



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