National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 151928
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
328 PM EDT WED MAY 15 2013

.SYNOPSIS...
-- Changed Discussion --
A COLD FRONT WILL MOVE SLOWLY EAST ACROSS THE REGION TONIGHT AND
REMAIN STALLED OVER THE SOUTHERN MID-ATLANTIC THROUGH THE WEEKEND AS
SURFACE HIGH PRESSURE BUILDS TO THE NORTH CREATING AN ONSHORE FLOW.
HIGH PRESSURE WILL BUILD OVER THE MID-ATLANTIC EARLY NEXT
WEEK...AIDING A SOUTHERLY FLOW.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH THURSDAY/...
MIXING IS ONGOING THIS AFTERNOON PRETTY MUCH EVERYWHERE EXCEPT
NORTHEAST MARYLAND. WARM FRONT WILL MOVE NORTH THROUGH THOSE LOCALES
THROUGH THE REMAINDER OF THE AFTERNOON HOURS WITH TEMPERATURES
RISING INTO THE 70S. ELSEWHERE...EXPECT WARM TEMPERATURES IN THE 80S
OVER MOST LOCALES. MOST OF VIRGINIA AND METRO AREAS WILL BE CAPPED
TODAY WITH SCATTERED SHOWER/ISOLATED THUNDERSTORMS STILL POSSIBLE
MAINLY NORTH ALONG THE MASON DIXON LINE LATER THIS AFTERNOON INTO
TONIGHT NEAR THE VICINITY OF THE FRONTAL BOUNDARY. SOUTHERLY FLOW
WILL REMAIN A BIT BREEZY THROUGH SUNSET MOST LOCALES.

WINDS WILL SHIFT INTO THE WEST AS THE WEAK COLD FRONT EDGES EAST
ACROSS THE FORECAST AREA LATER THIS EVENING. MOST LOCALES WILL SEE
OVERNIGHT LOW TEMPERATURES IN THE 60S...POSSIBLY A FEW 50S OVER THE
HIGHER TERRAIN OF THE POTOMAC HIGHLANDS. SCATTERED LIGHT RAIN
SHOWERS WILL BE POSSIBLE OVERNIGHT ALONG THE BOUNDARY ESPECIALLY
OVER THE WESTERN HIGH TERRAIN. WILL FOCUS ALL POPS OUT THAT WAY.

CLOUD COVER IS EXPECTED TO HOLD IN FOR MUCH OF THURSDAY...OCCASIONAL
BREAKS STILL POSSIBLE WITH FRONTAL BOUNDARY IN VICINITY. SCATTERED
SHOWERS AGAIN POSSIBLE ON THURSDAY JUST ABOUT ANYWHERE. SLIGHTLY
COOLER WITH HIGHS IN THE 60S OVER THE WEST WITH 70S TO NEAR 80
ELSEWHERE. SIDED TOWARD THE COOLER END OF GUIDANCE WITH EXPECTED
CLOUD COVER.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
THE COLD FRONT SHIFTS SOUTH OF DC THURSDAY EVENING...SHUNTING
SHOWERS/THUNDERSTORMS TO THE SRN PERIPHERY OF THE LWX CWA (INCL
KCHO). NWLY FLOW FILLS IN BEHIND THE COLD FRONT AND SINCE THIS MIXES
DOWN ON FRIDAY...THERE SHOULD BE LITTLE CHANGE IN THE TEMPERATURES
(MAX TEMPS FRIDAY AROUND 80F...PERHAPS MID 80S SOUTH OF DC).
SCATTERED THUNDERSTORMS POSSIBLE IN THE TERRAIN W/SW OF KCHO
FRIDAY.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
-- Changed Discussion --
ONSHORE FLOW OR CAD WEDGE THIS WEEKEND WITH HIGH PRESSURE EITHER
STALLED ALONG THE NEW ENGLAND COAST OR OFF THE MID-ATLANTIC COAST. A
QUICK LOOK AT THE 12Z ECMWF SUGGESTS THE HIGH STALLS ALONG THE NEW
ENGLAND COAST AND GIVES A CAD WEDGE FOR THE MID-ATLANTIC. MAX
TEMPERATURES WERE KNOCKED DOWN 5-10 DEGREES BELOW NORMAL...LOW 70S
(WITH MID 70S SOUTH OF DC) ON SATURDAY AND SOME UPPER 60S FOR SUNDAY
(WITH LOW 70S SRN MD). PRECIP LOOKS TO REMAIN SHUNTED TO THE FAR
SWRN ZONES FOR LWX (WEST FROM KCHO).


LONG WAVE (WARM) RIDGE BUILDS OVER THE MIDWEST EARLY NEXT WEEK.
SLY/SELY FLOW WILL BRING QUITE A WARMUP TO THE REGION WITH
TEMPERATURES BACK ABOVE NORMAL BY MON OR TUE. MOISTURE INFLUX ACROSS
THE REGION IN THE SLY FLOW SHOULD BRING SOME INSTABILITY ACTIVITY
THROUGH THE EARLY AND MID PARTS OF NEXT WEEK.
-- End Changed Discussion --

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
VFR EXPECTED REST OF TODAY INTO THURSDAY. COVERAGE OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS BEST NEAR THE MASON DIXON LINE THE
REMAINDER OF THIS AFTERNOON INTO THIS EVENING. ADDITIONAL CHANCES ON
THURSDAY MOST AREAS WITH SOME SUB VFR CONDITIONS POSSIBLE AT TIMES
BUT NOT LOWER THAN MVFR.

VFR CONDS PREVAIL THURSDAY NIGHT INTO THE WEEKEND. SCATTERED
THUNDERSTORMS WANE AND SHIFT SOUTH FROM THE DC METROS THURSDAY
EVENING AND PERSIST NEAR KCHO INTO THE EARLY MORNING HOURS.
THUNDERSTORMS ON FRIDAY LOOK TO BE WEST FROM THE BLUE RIDGE.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
SCA CONDITIONS FROM LATE THIS AFTERNOON INTO THE EVENING HOURS. A
FEW GUSTS OVER 20 KTS EXPECTED ESPECIALLY OVER THE OPEN WATERS OF
THE CHESAPEAKE BAY. WESTERLY WIND SHIFT EXPECTED TONIGHT WITH
DIMINISHING WINDS. WINDS WILL REMAIN BELOW SCA ON THURSDAY.

NO SCAS EXPECTED THURSDAY NIGHT THROUGH THIS WEEKEND. NWLY FLOW
10 TO 15 KT THURSDAY EVENING BECOMES NLY THURSDAY NIGHT...THEN
VEERING SELY THROUGH FRIDAY. EXPECT AN ONSHORE FLOW THROUGH THIS
WEEKEND.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
SOUTHERLY CHANNELING WILL CONTINUE FOR THE NEXT SEVERAL HOURS WITH
WIND SHIFT TO THE WEST EXPECTED LATER THIS EVENING/TONIGHT. HIGHEST
WATER LEVELS HAVE LIKELY OCCURRED WITH THIS MORNINGS HIGH TIDE
CYCLE. LEVELS PEAKED BELOW MINOR FLOOD THRESHOLDS AT BOTH ANNAPOLIS
AND BALTIMORE. WESTERLY FLOW LATE TONIGHT INTO THURSDAY WILL PUT AN
END TO ELEVATED LEVELS ALL ALONG THE WESTERN SHORE OF THE BAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ531>534-
     537-539>541-543.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ530-
     535-536-538-542.

&&

$$
SYNOPSIS...BAJ/KRW
NEAR TERM...KRW
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/KRW
MARINE...BAJ/KRW
TIDES/COASTAL FLOODING...KRW