Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 130236
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1036 PM EDT SAT APR 12 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE EAST OF THE AREA TONIGHT THROUGH SUNDAY. A
COLD FRONT WILL GRADUALLY MOVE THROUGH THE REGION LATE MONDAY
NIGHT INTO TUESDAY...WITH HIGH PRESSURE BUILDING INTO THE AREA FOR
THE SECOND HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE...AND LIGHT RETURN FLOW HAS
ESTABLISHED ACROSS THE FORECAST AREA. DEW POINTS HAVE BEEN
STEADILY INCREASING THIS EVENING...AND THIS TREND WILL CONTINUE
OVERNIGHT. THERE WILL BE SOME POTENTIAL FOR STRATUS
DEVELOPMENT...PATCHY FOG...OR BOTH. CONFIDENCE IS NOT VERY
HIGH...AS THIS WILL DEPEND ON HOW MUCH RADIATIONAL COOLING
DEVELOPS WITH SOME MID-HIGH LEVEL CLOUDS. LOW TEMPS EXPECTED TO BE
GENERALLY IN THE UPPER 40S TO LOW 50S OVER MOST OF THE
REGION...AND THE MID 50S IN METRO BALTIMORE/WASHINGTON.

SUNDAY APPEARS TO BE A FANTASTIC...IF NOT SOMEWHAT HUMID...DAY.
EARLY STRATUS WILL GIVE WAY TO SCATTERED DIURNAL CUMULUS CLOUDS. THE
DEEP SOUTHERLY FLOW WILL YIELD HIGHS AROUND 80...BUT WITH
DEWPOINTS IN THE MIDDLE IF NOT UPPER 50S. WINDS WILL BE GUSTY IN
THE AFTERNOON...WITH WIND GUSTS NEAR 30 MPH POSSIBLE.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
SOUTHERLY FLOW PERSISTS SUNDAY NIGHT. SOME LOW CLOUD DEVELOPMENT IS
POSSIBLE BUT DECOUPLING WILL NOT OCCUR. GIVEN PERSISTENT LOW-LEVEL
MOISTURE AND THE WIND...LOWS MAY HAVE A DIFFICULT TIME DROPPING MUCH
BELOW 60 EAST OF THE BLUE RIDGE. DEEPER MOISTURE APPROACHES BY LATE
MONDAY AS A COLD FRONT ORGANIZES SLOWLY PUSHES ACROSS THE EASTERN
GREAT LAKES AND OHIO VALLEY. WHILE I AM NOT PARTICULARLY CONVINCED
ABOUT CONVECTIVE POTENTIAL WELL AHEAD OF THE FRONT ON MONDAY...AS
THE DEEPER MOISTURE ARRIVES LATE IN THE DAY...COMBINED WITH SOME
TERRAIN LIFT...MOUNTAIN -SHRA WILL BE POSSIBLE...MAYBE EVEN A TSTM.
CLOUDS SPREADING NORTHWARD AHEAD OF THE SYSTEM WILL HOLD HIGHS DOWN
JUST A BIT COMPARED TO SUNDAY...BUT STILL WELL ABOVE NORMAL.

PRECIPITATION SPREADS FURTHER EAST MONDAY NIGHT AS THE FRONT
APPROACHES. STILL SOME UNCERTAINTY WHETHER THERE WILL EVEN BE MUCH
PRE-FRONTAL PRECIP...SO POPS WERE KEPT BELOW CATEGORICAL ON MONDAY
NIGHT IN ALMOST ALL AREAS. A TSTM CANNOT BE RULED OUT AT ANY TIME
DURING THE NIGHT. THE BEST CHANCE OF RAIN APPEARS TO BE TUESDAY
MORNING /THOUGH THAT TIMING IS NOT YET A LOCK/ AS THE FRONT PUSHES
THROUGH. RAIN COULD BE HEAVY TUESDAY MORNING WITH PWATS AROUND 1.5
INCHES...BUT THE SYSTEM IS PROGRESSIVE OVERALL...WHICH WILL LIMIT A
FLOOD THREAT. AVERAGE RAINFALL LOOKS TO BE AROUND AN INCH.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A STRONG PUSH OF COLD AIR...WITH 850 MB TEMPERATURES AT OR BELOW 0 C
WILL MOVE INTO THE REGION BEHIND A DEPARTING COLD FRONT TUESDAY
EVENING. SNOW SHOWERS COULD MIX WITH ANY LINGERING PRECIPITATION
GENERALLY AT ELEVATIONS AT OR ABOVE 1500 FEET. LOW TEMPERATURES WILL
BE WELL BELOW NORMAL...GENERALLY IN THE 30S AREA-WIDE.

A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT AND MOVE NORTH
ALONG THE EASTERN SEABOARD DURING THE DAY WEDNESDAY.
MODELS/ENSEMBLES DIFFER ON HOW FAR EAST THE FRONT GETS BY THE TIME
LOW PRESSURE APPROACHES FROM THE SOUTH. THE 00Z DETERMINISTIC ECMWF
IS SLOWEST AND FURTHEST WEST WITH THE FRONT AND WAVE OF LOW
PRESSURE...WITH THE 12Z GFS FURTHER EAST. FOR NOW HAVE CHANCE POPS
ACROSS THE VA PIEDMONT AND I-95 CORRIDOR ON EAST WHERE HIGHEST
CHANCE OF RAIN WOULD BE.

HIGH PRESSURE WILL MOVE ACROSS THE AREA WEDNESDAY NIGHT THROUGH
THURSDAY WITH DRY WEATHER AND BELOW NORMAL TEMPERATURES EXPECTED.
ANOTHER STORM SYSTEM MAY APPROACH THE AREA TOWARDS THE END OF NEXT
WEEK...BUT TRACK AND TIMING DETAILS ARE FAR FROM CERTAIN AT THIS
JUNCTURE.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS EXPECTED THIS EVENING AND MOST OF THE NIGHT.
GUIDANCE CONTINUES TO INDICATE POTENTIAL FOR MVFR CIGS/VSBYS IN
THE PREDAWN HOURS AS LOW LEVEL MOISTURE INCREASES. CONFIDENCE IS
MODERATE...AS MOISTURE RETURN MAY NOT BE QUITE ENOUGH. LIGHT
SOUTHERLY FLOW EXPECTED.

VFR EXPECTED SUNDAY. WINDS WILL BECOME GUSTY BY SUNDAY
AFTERNOON...AND REMAIN FAIRLY BREEZY/GUSTY THROUGH TUESDAY. LOWER
CIGS/VSBY POSSIBLE IN -SHRA MONDAY NIGHT AND TUESDAY. TSRA ARE
POSSIBLE AS WELL.

SUB-VFR STILL POSSIBLE IN SHOWERS TUESDAY NIGHT...POSSIBLY
PERSISTING INTO WEDNESDAY ESPECIALLY FOR SOUTHERN AND EASTERN
TERMINALS /I.E. BWI-DCA-CHO SOUTH AND EAST/. NORTHERLY FLOW AROUND
10 KNOTS.

&&

.MARINE...
SMALL CRAFT ADVISORY IS IN EFFECT FOR CHESAPEAKE BAY FROM SANDY
POINT TO SMITH POINT. HIGH PRESSURE MOVING TO THE EAST DEVELOPED
ENOUGH OF A PRESSURE GRADIENT FOR MARGINAL SCA GUSTS. MODELS HAVE
HAD DIFFICULTY WITH THIS AND STILL SUPPORT LIGHTER WINDS
OVERNIGHT. INITIALLY RAISED SCA UNTIL 2 AM AND WILL HAVE TO
CONTINUE TO MONITOR THE NEXT SEVERAL HOURS.

SOUTHERLY FLOW INCREASES ON SUNDAY...AND A SMALL CRAFT ADVISORY IS
IN EFFECT. THAT ADVISORY HAS BEEN EXTENDED THROUGH SUNDAY
NIGHT...AND LIKELY WILL HAVE TO BE EXTENDED BEYOND THAT THROUGH
THE FIRST PART OF NEXT WEEK AS THE SOUTHERLY FLOW PERSISTS.

GUSTY NORTHERLY FLOW BEHIND DEPARTING COLD FRONT/WAVE OF LOW
PRESSURE COULD RESULT IN SCA LEVEL GUSTS ON PARTS OF THE WATERS
WEDNESDAY. HIGH PRESSURE NEAR THE AREA SHOULD THEN PRECLUDE SCA
CONDITIONS THROUGH THURSDAY.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES ARE CURRENTLY BETWEEN 0.5 AND 1.0 FOOT BELOW
NORMAL...BUT AS SOUTHERLY FLOW COMMENCES...THE ANOMALIES WILL
GRADUALLY TURN POSITIVE. WITH THE SOUTHERLY FLOW EXPECTED TO
PERSIST THROUGH MONDAY NIGHT...WATER LEVELS COULD APPROACH MINOR
FLOOD CRITERIA AT THE MORE SENSITIVE LOCATIONS BY MONDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR
     ANZ530>543.
     SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ532>534-543.

&&

$$
SYNOPSIS...JCE
NEAR TERM...JCE/KCS
SHORT TERM...JCE
LONG TERM...DFH
AVIATION...KCS/DFH
MARINE...JCE/KCS/DFH
TIDES/COASTAL FLOODING...JE







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