Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 210749
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
349 AM EDT SUN SEP 21 2014

.SYNOPSIS...
LOW PRESSURE WILL TRACK NORTH ALONG THE SOUTHEAST AND MID ATLANTIC
COASTS TODAY. A COLD FRONT WILL CROSS THE REGION LATE THIS AFTERNOON
INTO THIS EVENING...FOLLOWED BY A RETURN OF HIGH PRESSURE MONDAY
THROUGH WEDNESDAY.
&&

.NEAR TERM /THROUGH TONIGHT/...
DEVELOPING LOW PRESSURE WILL MOVE ALONG THE CAROLINA COAST THIS
MORNING BEFORE HEADING OUT TO SEA THIS AFTERNOON. RAINBANDS
ASSOCIATED WITH THIS SYSTEM ARE EXPECTED TO REMAIN TO THE SOUTH AND
EAST OF THE FORECAST AREA. SOME PATCHY FOG IS STILL POSSIBLE EARLY
THIS MORNING BUT WESTERLY WINDS WILL HELP MIX OUT THE BOUNDARY LAYER
AFTER SUNRISE WITH REMAINING FOG BURNING OFF. BEHIND THE DEPARTING
LOW...WESTERLY WINDS WILL AID IN DOWNSLOPE WARMING ACROSS THE
REGION. AFTERNOON HIGH TEMPERATURES ARE EXPECTED TO REACH THE 80S IN
MOST LOCATIONS...ESPECIALLY EAST OF THE BLUE RIDGE. DAYTIME HEATING
COMBINED WITH AN APPROACHING COLD FRONT WILL HELP TOUCH OFF
SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS FIRST OVER
THE POTOMAC HIGHLANDS AND I-81 CORRIDOR THEN SPREADING EAST ACROSS
THE METRO AREAS LATE THIS AFTERNOON AND INTO THE EVENING. SOME OF
THE STORMS COULD PRODUCE DAMAGING WINDS ALTHOUGH AN ISOLATED THREAT.
CONVECTIVE THREAT WILL END BY MID EVENING. A FEW SHOWERS MAY REMAIN
OVER THE POTOMAC HIGHLANDS. COOLER AND DRIER AIR WILL FILTER INTO
THE REGION OVERNIGHT WITH TEMPERATURES COOLING BACK TO THE 40S TO
50S WEST AND UPPER 50S TO MIDDLE 60S EAST.
&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD INTO THE MIDDLE ATLANTIC ON MONDAY BRINGING
PLENTY OF SUNSHINE AND PLEASANT TEMPERATURES. AFTERNOON HIGHS
MAINLY IN THE 60S TO LOWER 70S CAN BE EXPECTED ALONG WITH LOWS IN
THE UPPER 30S TO LOW 40S WEST TO THE MID 40S TO 50S EAST OF THE BLUE
RIDGE.
&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
SFC HIPRES WL BE ACROSS MOST OF THE ERN CONUS THRU THE END OF THE
WK. H5 RDG WL BE BLDG TOO. AT FIRST GLANCE...THAT WUD SEEM LIKE A
CUT-N-DRY FCST. HWVR...THERE IS A CATCH.

ECMWF GDNC SUGGESTING A CUTOFF LOW IN THE MIDST OF THE H5 RDG...OR
IN OTHER WORDS...A WEAKNESS IN THE HGT PTTN. THERE/S RATHER POOR
AGREEMENT ON A FEATURE SO SUBTLE SVRL DAYS OUT. HWVR...SFC FLOW WL
BE NLY TUE BUT VEER ELY WED-THU...AS THE CENTER OF THE SFC HIGH WL
BE ATOP NEW ENGLAND/NYS BY THEN. AT THE VERY LEAST...CANNOT RULE OUT
AN INCREASE IN MSTR AND MAYBE A SPRINKLE OR TWO /OR A PATCH OF DZ?/.
SO AT THIS JUNCTURE...WL KEEP TUE SUNNY...BRING CLDS INLAND WED...
AND OFFER UP SOME LOW END POPS /20-30 PCT/ WED NGT-THU. CHOOSING A
STRATIFORM PCP CHARACTER.

AM THINKING AS THE UPR RDG BLDS TO THE W OF THE AREA...THAT MAY BE
ENUF TO ALLOW SFC RDGG TO RETROGRADE. IF THAT DOES HPPN...THEN WE/LL
LOSE THE ONSHORE FLOW...AND THE MARINE AMS WL LOSE ITS GRIP ON THE
RGN. DONT HV THE HIEST OF CONFIDENCE IN THIS OUTLOOK...BUT DONT WANT
TO CARRY A PROLONGED PD OF LOW POPS UNDER HIPRES W/O A CLEARER
SIGNAL.

CAN SAY THIS...HIER HGTS WL LEAD TO WARMER TEMPS. MAXT TUE-THU NOT
FAR OFF FM BAY WATER TEMPS...WHICH IS ABT 5 OR 6 DEGF COOLER THAN
CLIMO. WE/LL BE BACK NEAR NORMAL AGN FRI-SUN.
&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
PATCHY EARLY MORNING FOG WILL GIVE WAY TO VFR CONDITIONS BY MID
MORNING. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON AND EVENING AHEAD OF A COLD FRONT. SOME IMPACT TO THE
TERMINALS MAY BE POSSIBLE...ESPECIALLY 18-00Z. PATCHY FOG COULD
REDEVELOP LATE TONIGHT INTO EARLY MONDAY.

OUTLOOK...
MON-TUE...VFR UNDER HIPRES.
WED-THU...ONSHORE FLOW MAY BRING A STRATUS DECK INLAND. FLGT
RESTRICTIONS PSBL...BUT CONFIDENCE LOW.
&&

.MARINE...
WINDS WILL REMAIN BELOW SCA LEVELS TODAY EXCEPT WHERE SHOWERS AND
THUNDERSTORMS DEVELOP LATE THIS AFTERNOON INTO THIS EVENING. SCA
CONDITIONS ARE EXPECTED BEHIND A COLD FRONT OVERNIGHT THROUGH
MONDAY.

NLY FOW TUE WL VEER ELY FOR WED-THU. GDNC SUGGESTING ELY FLOW MAY BE
STIFF...POTENTIALLY SUPPORTING SCA CONDS OVER A PORTION OF THE
WATERS /MID BAY/.
&&

.TIDES/COASTAL FLOODING...
TIDAL DEPARTURES...WHICH ROSE DRAMATICALLY YDA...HAVE SINCE LESSENED
AS HIGH TIDE ROLLS IN. AS A RESULT...TIDES MAXING OUT RIGHT NEAR
MINOR CRITERIA AT SOLOMONS/PINEY POINT/ANNAPOLIS. THE TIDE IS IN AA
COUNTY RIGHT NOW. THUS WL BE ABLE TO CANX ADVY FOR CALVERT AND SAINT
MARYS. FURTHER...SINCE DEPARTURES LOWER...DO NOT BELIEVE THRESHOLDS
WILL BE MET AT BALTIMORE. WILL CANCEL THAT ONE AS WELL. DO NOT HAVE
A GOOD FEEL FOR THE UPPER POTOMAC RIGHT NOW...SO WILL ALLOW THOSE
ADVYS TO CONTINUE.

THE PM TIDE WILL BE A BIT MORE OF A CHALLENGE TO FORECAST. IT WILL
BE THE LOWER ASTRONOMICAL TIDE. SWLY WINDS WILL BECOME WLY...SO
PERHAPS WE WILL GET A PINCH OF RELIEF FROM THAT. AND...BASELINE
DEPARTURES GOING IN APPEAR TO BE BELOW +1. ALL SAID...WL FOLLOW THE
PREMISE THAT REACHING CAUTION STAGE PROBABLE BUT MINOR THRESHOLD
LESS LIKELY.
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY UNTIL 9 AM EDT THIS MORNING FOR DCZ001.
MD...COASTAL FLOOD ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MDZ014.
VA...COASTAL FLOOD ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT MONDAY FOR
     ANZ530>543.

&&

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






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