Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KLWX 260149
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
949 PM EDT WED MAR 25 2015

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE COAST OVERNIGHT. A
WARM FRONT WILL PASS THROUGH THE AREA THURSDAY MORNING FOLLOWED BY
ACOLD FRONT THAT WILL MOVE THROUGH THURSDAY NIGHT. AN UPPER-
LEVEL DISTURBANCE WILL PASS THROUGH THE AREA LATER FRIDAY THROUGH
SATURDAY. HIGH PRESSURE WILL RETURN FOR SUNDAY.

&&

.NEAR TERM /OVERNIGHT/...

LATE AFTN SFC ANLYS SHOWED HIGH PRES OFF THE DELMARVA...A WARM
FRONT CURVING FM SERN VA INTO NRN NC AND UP THE ERN SIDE OF THE
APLCHNS...THEN A COLD FRONT ACROSS INDIANA...BCMG A WARM FNT
ACROSS OK. THE ERN WARM FNT HASN`T MADE A LOT OF NWRD PROGRESS
THIS EVE...AND HV CUT BACK ON THE POPS THIS EVE BECAUSE OF IT.
SREF 850-1000 THCKNS PATTERN IMPLIES THE FNT WL BE MAKING NWD
PROGRESS OVRNGT...AND RNGL RDR NOW STARTING TO SHOW LGT ECHOES
ALONG THE VA/NC BRDR...SO WL LV THE CHC OF RA IN BTWN 06-12Z.
MUCH OF THE TIME WILL TURN OUT DRY.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...

THE WARM FRONT WILL PASS THROUGH OUR AREA THURSDAY MORNING. A FEW
SHOWERS ARE POSSIBLE WITH THE FRONTAL PASSAGE...ESPECIALLY ACROSS
SOUTHERN MARYLAND AND THE VIRGINIA PIEDMONT WHERE ATLANTIC
MOISTURE WILL GET DRAWN INTO THE AREA.

THERE MAY BE A SIGNIFICANT BREAK IN PRECIPITATION BEHIND THE WARM
FRONT THURSDAY. GUSTY SOUTHERLY WINDS ARE EXPECTED TO DEVELOP AND
THIS WILL USHER IN WARMER TEMPERATURES. MAX TEMPS ARE EXPECTED TO
BE IN THE 70S ACROSS MOST LOCATIONS. THERE MAY EVEN BE A FEW
LOCATIONS IN THE VIRGINIA PIEDMONT THAT APPROACH 80 DEGREES.

A POTENT COLD FRONT WILL MOVE INTO THE POTOMAC HIGHLANDS LATE IN
THE AFTERNOON BEFORE PASSING THROUGH THE BALTIMORE AND WASHINGTON
METROPOLITAN AREAS EARLY IN THE EVENING...THEN EVENTUALLY PAST
SOUTHERN MARYLAND OVERNIGHT. A LINE OF GUSTY SHOWERS AND POSSIBLY
EVEN A COUPLE THUNDERSTORMS WILL ACCOMPANY THE FRONT. GUSTY WINDS
ARE EXPECTED...BUT AS OF NOW THE THREAT FOR SEVERE WEATHER IS LOW
DUE TO A CAPPING INVERSION IN THE LOW-LEVELS LIMITING INSTABILITY.
WILL HAVE TO CONTINUE TO MONITOR...BECAUSE THERE ARE PLENTY OF
STRONG WINDS ALOFT THAT WILL BE ABLE TO MIX DOWN TO THE SURFACE IF
THE ATMOSPHERE IS UNSTABLE ENOUGH AHEAD OF THE BOUNDARY.

THE COLD FRONT WILL PUSH OFF TO THE EAST OVERNIGHT THURSDAY...BUT
THE UPPER-LEVEL TROUGH WILL REMAIN WELL BEHIND OVER THE GREAT
LAKES INTO THE OHIO VALLEY. AN UPPER-LEVEL DISTURBANCE AHEAD OF
THE TROUGH WILL SWING THROUGH OUR AREA...CAUSING MORE RAIN BEHIND
THE FRONT. NORTHWEST WINDS WILL CAUSE MUCH COLDER CONDITIONS AS
WELL. IN FACT...RAIN WILL CHANGE TO SNOW ACROSS THE ALLEGHENY AND
POTOMAC HIGHLANDS. SNOWFALL ACCUMULATIONS WILL BE CONFINED MAINLY
TO AREAS ABOVE 2KFT ALONG AND WEST OF THE ALLEGHENY FRONT.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FOR FRIDAY THROUGH SATURDAY...PERIOD IS DOMINATED BY H5 HEIGHT FALLS
AS SHORT WAVE OVER GREAT LAKES PRODUCES CUTOFF LOW ON SATURDAY OVER
THE MASON-DIXON LINE AS INDICATED BY THE 12Z GFS. SFC TEMPS DURING
THIS TIME WILL BE 10-15F BELOW NORMAL.

ON FRIDAY...THE SURFACE FRONT IS PROGGED BY BOTH THE 12Z GFS AND 12Z
ECMWF TO BE EAST OF DELMARVA.  THIS WILL PUT DECREASING POPS FROM
WEST TO EAST ACROSS THE CWA IN THE MORNING...WITH THE EXCEPTION OF
AN UPSLOPE COMPONENT IN THE HIGHLANDS WHERE SNOW SHOWERS WILL BE
LIKELY.  FRIDAY NIGHT THE CWA WILL BE PRECIP FREE XCPT FOR UPSLOPE
AGAIN IN H85 CAA AND DOWNSLOPING.

BY 12Z SATURDAY...H85 TEMPS ARE PROGGED TO BE A0B -9C ACROSS THE
ENTIRE CWA...WHICH WILL MAKE FOR A VERY CHILLY AND BLUSTERY DAY ON
SATURDAY WITH CHC OF SNOW SHOWERS ACROSS THE ENTIRE REGION DUE TO
LOW LEVEL INSTABLITY AND APPROACHING CUT UPPER LOW...WITH HIGHER
POPS IN UPSLOPE AREAS AGAIN.

AN UPPER-LEVEL TROUGH WILL BE MOVING AWAY SATURDAY NIGHT INTO
SUNDAY WHILE HIGH PRESSURE BUILDS OVER THE REGION. THE HIGH WILL
MOVE OFF THE COAST ON SUNDAY. HIGH TEMPS WILL BE IN LOW 50S.

A COLD FRONT APPROCHES THE REGION AND WILL MOVE ACROSS THE AREA
EARLY ON MONDAY... BRINGING A CHANCE FOR SHOWERS. HIGH PRESSURE
RETURNS ON TUESDAY AND A WARM FRONT APPROACHES ON WEDNESDAY.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...

CIGS WILL OSCIALLATE ALONG THE 030 BOUNDARY FOR MUCH OF THE OVRNGT
HRS. A PERIOD OF IFR IS POSSIBLE THURSDAY MORNING AS THE WARM
FRONT SWINGS THROUGH. LOW-LEVEL WIND SHEAR IS PSBL EARLY THURSDAY
MORNING DUE TO A POTENT LL JET AND A LACK OF MIXING CAUSING LIGHT
WINDS NEAR THE SURFACE.

CIGS WILL IMPROVE BEHIND THE BOUNDARY LATER THURSDAY MORNING.
SOUTHERLY WINDS WILL BECOME GUSTY AHEAD OF AN APPROACHING COLD
FRONT THURSDAY AFTERNOON. GUSTS AROUND 25 TO 30 KNOTS ARE
EXPECTED. VFR CONDITIONS WITH GUSTY NORTHWEST ARE EXPECTED FRIDAY
THROUGH SATURDAY.

VFR CONDITIONS ARE EXPECTED FOR SUNDAY. COLD FRONT MOVING ACROSS
ON MONDAY WILL BRING A CHANCE FOR SHOWERS TO THE TERMINALS.

THE COLD FRONT WILL PASS THROUGH LATE THURSDAY AFTERNOON AND
EVENING. A LINE OF SHOWERS AND PERHAPS A COUPLE THUNDERSTORMS WILL
ACCOMPANY THE FRONTAL PASSAGE. GUSTY WINDS ARE POSSIBLE WITH THIS
LINE OF CONVECTION. WINDS WILL SHIFT TO THE NORTHWEST BEHIND THE
FRONT. MORE RAIN WILL HANG AROUND FOR OVERNIGHT THURSDAY WITH
POSSIBLE SUBVFR CONDITIONS.

&&

.MARINE...

WINDS HV DIMINISHED ON THE N SIDE OF AN APRCHG WARM FRONT. THIS WILL
PASS THROUGH THE WATERS THURSDAY MORNING. GUSTY SOUTHERLY WINDS
ARE EXPECTED BEHIND THE BOUNDARY. A SMALL CRAFT ADVISORY IS IN
EFFECT THU AND THU NIGHT. SOUTHERLY WINDS WILL SHIFT TO THE
NORTHWEST BEHIND THE COLD FRONT. A LINE OF HEAVY SHOWERS AND
PERHAPS A COUPLE THUNDERSTORMS WILL ACCOMPANY THE FRONTAL PASSAGE.
LOCALLY GUSTY WINDS ARE POSSIBLE AS THIS SYSTEM PASSES THROUGH.

A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS
FRIDAY. NO MARINE HEADLINES ANTICIPATED FRIDAY NIGHT THROUGH
SUNDAY. SCA MAY BE NEEDED ON MONDAY AS COLD FRONT MOVES ACROSS
THE REGION.

&&

.TIDES/COASTAL FLOODING...
SOUTHERLY WINDS WILL DEVELOP THROUGH TONIGHT AND THE SOUTHERLY
FLOW WILL INCREASE AHEAD OF A COLD FRONT THURSDAY. THE INCREASED
SOUTHERLY FLOW WILL CAUSE WATER LEVELS TO ELEVATE...AND TIDAL
ANOMALIES MAY BE HIGH ENOUGH FOR MINOR FLOODING NEAR TIMES OF HIGH
TIDE THURSDAY INTO THURSDAY NIGHT.

THE COLD FRONT WILL PASS THROUGH LATER THURSDAY EVENING AND A
NORTHWEST FLOW WILL CAUSE WATER LEVELS TO DECREASE LATE THURSDAY
NIGHT INTO FRIDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THURSDAY TO 6 AM EDT FRIDAY
     FOR ANZ530>543.

&&

$$
UPDATE...WOODY!
PRVS...BJL/JEL/IMR


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.