Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 131322
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
922 AM EDT SUN APR 13 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE EAST COAST THROUGH
MONDAY. 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 MONDAY/...
FORECAST AREA IS SOLIDLY IN THE WARM SECTOR THIS MORNING...WITH
SIGNIFICANTLY MORE HUMID AIR THAN YESTERDAY AND TEMPERATURES THAT
ARE SIMILAR TO YESTERDAY AT THIS TIME EAST OF THE BLUE RIDGE...AND
SIGNIFICANTLY WARMER WEST OF THE BLUE RIDGE. TEMPS ARE ALREADY
AROUND 70 IN VALLEYS...AND MID 60S AT HIGHER ELEVATIONS...WEST OF
THE BLUE RIDGE.

FORECAST FOR TODAY LOOKS GENERALLY ON TRACK...WITH HIGHS IN THE
UPPER 70S TO LOWER 80S. HOWEVER...SOME SLIGHT ONSHORE FLOW WILL
HOLD TEMPS DOWN ALONG THE WESTERN SHORE OF THE BAY. THIS IS
ALREADY ACCOUNTED FOR IN THE FORECAST.

THE ONLY UPDATE WAS TO ADD ISOLATED SHOWERS LATE THIS MORNING
ALONG THE WESTERN SLOPES OF MINERAL AND ALLEGANY COUNTIES...AS
SOME LIGHT PRECIP APPROACHES FROM THE WEST. THAT PRECIP WILL NOT
SURVIVE CROSSING THE MOUNTAINS...SO ELSEWHERE SHOULD STAY DRY.

HIPRES WILL RETREAT FURTHER OFFSHORE TNGT AS A COLD FRONT ADVANCES
EWD INTO THE MIDWEST/GREAT LAKES REGIONS TNGT. MOIST SLY WINDS 5-15
MPH WILL PERSIST AFTER SUNSET...KEEPING TEMPS MILD TNGT AND FOG
POTENTIAL LOW. FCST MIN TEMPS IN THE UPPER 50S/LOWER 60S FAVORED THE
WARMER BIAS CORRECT MET/NAM GUIDANCE. STRATUS MAY DEVELOP AGAIN NEAR
THE CHSPK BAY.

THE COLD FRONT WILL APPROACH THE WRN SIDE OF THE APPALACHIANS ON
MON. HEIGHT FALLS ALOFT AHEAD OF THE AMPLIFY CENTRAL CONUS TROUGH
WILL SPREAD EWD TOWARD THE ERN SEABOARD DURING THE DAY AND SLY LLVL
JET WILL TRANSPORT MOISTURE INTO THE REGION. HOWEVER...POPS WERE
KEPT LOW AND COVERAGE LIMITED TO THE MTS AS THE MAIN SYNOPTIC LIFT
REMAINS UPSTREAM OF THE CWA. NOT MUCH INSTABILITY PRESENT ON MON DUE
TO THE PRESENCE OF A MID-LVL CAPPING INVERSION. THE MID-LVL
SUBSIDENCE INVERSION WEAKENS LATE IN THE DAY ACROSS THE WRN
HIGHLANDS...WHERE SLIGHT CHANCE OF TSTMS WERE MENTIONED. TEMPS
EXPECTED TO REACH THE MID TO UPPER 70S ACROSS MUCH OF THE AREA
DESPITE INCREASING CLOUD COVER.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
MON NIGHT...THE 00Z/03Z ENSEMBLE MODEL GUIDANCE IN GENERALLY GOOD
AGREEMENT ON POSITION OF THE APPROACHING COLD FRONT MOVING THROUGH
THE GREAT LAKES/OHIO/TENNESSEE VALLEY EARLY IN THE PERIOD. MODELS
ARE SLOWER WITH FRONTAL PASSAGE THEN WAS ADVERTISED YESTERDAY...SO
THE CWA WILL STILL BE IN A MILD SOUTHERLY REGIME THIS PERIOD.

TUE AND TUE NIGHT...THE COLD FRONT WILL MOVE THROUGH DURING THE
DAYTIME. STRONG COLD ADVECTION BEHIND THE FRONT WILL USHER IN MUCH
COLDER CONDITIONS. RAIN WILL DEVELOP JUST AHEAD AND ALONG THE FRONT
WITH AMOUNTS OF BETWEEN ONE HALF TO ONE INCH CWA WIDE...WITH SOME
HIGHER AMOUNTS UP TO ONE AND ONE-HALF INCH POSSIBLE IN CONVECTION.
INSTABILITY NOT HIGH OWING TO AMPLE CLOUD COVER...BUT SOME ELEVATED
CONVECTION INSTABILITY OF 100-500 J/KG...SO THUNDERSTORMS POSSIBLE.

TUE NIGHT...THERE COULD BE LINGERING POST-FRONTAL SHOWERS...AND
ALONG AND WEST OF THE BLUE RIDGE...COLD AIR ALOFT COULD MEAN SOME
SNOW MIXED IN WITH SHOWERS...BUT NOTHING APPRECIABLE EXPECTED FOR
ACCUMULATIONS. 85H TEMPS FALL TO -6C TO -10C RANGE LATE TUE NIGHT.
STRONG CAA WILL KEEP NW WINDS

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
WED...HIGH PRESSURE CENTER OVER THE OHIO VALLEY WILL MOVE EAST
AND AND BE OVER THE REGION BY THE END OF WED. TEMPERATURES ON WED
WILL BE UNSEASONABLY COOL BY A GOOD 10 TO 15 DEGF WITH BLUSTERY
WINDS TO START THE DAY...GRADUALLY DIMINISHING BY LATE AFTERNOON.

THU-FRI...HIGH PRESSURE WILL MOVE NORTHEAST AND FORM A RIDGE ALONG
THE EASTERN SEABOARD BRINGING DRY WEATHER AND NORTH TO NORTHEAST
WINDS. COOL TEMPS EXPECTED THUR...ALTHOUGH NOT QUITE AS COOL AS WED.
TEMPS MODERATE A BIT MORE ON FRI.

SAT...LOTS OF UNCERTAINTY AS WE HEAD TOWARD THE WEEKEND. RIGHT NOW
IT LOOKS DRY FOR SAT...BUT VARIOUS MODEL SOLNS ARE SHOWING LOW
PRESSURE SOMEWHERE OF THE EASTERN SEABOARD...OR GREAT LAKES...
DEPENDING ON WHAT MODEL GUIDANCE ONE LOOKS AT. FOR NOW WILL DOWNPLAY
PRECIP CHANCES AS UNCERTAINTY IS HIGH.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS THROUGH THIS EVENING. WINDS ARE INCREASING AND WILL
BE GUSTY AROUND 20 KTS THIS AFTERNOON.

STRATUS MAY DEVELOP ERY MON MRNG AGAIN NEAR THE BAY. VFR ON MON WITH
SLY WINDS 15-25 KT.

MON NIGHT VFR CONDITIONS INITIALLY...WITH LOWERING CIGS TO MVFR
DURING THE OVERNIGHT. ON TUE...IFR CIGS AND VSBYS IN AREAS OF RAIN
ALONG AND AHEAD OF THE FRONT...WITH BRIEF PDS OF TSTMS POSSIBLE.
FRONT MOVES THROUGH TUE AFTERNOON...WITH CONDITIONS VFR EXPECTED
LATE TUE THROUGH THE END OF THE WEEK. NW WINDS 15 TO 20 KT WITH
GUSTS TO 25 KT LATE TUE NIGHT AND WED MORNING.

&&

.MARINE...
WINDS GRADUALLY INCREASING OVER THE MARINE AREA...WITH SCA
STARTING AT NOON. WIND GUSTS 20-25 KNOTS EXPECTED THROUGH THE
EVENING. SCA CONTINUES THROUGH MONDAY...THOUGH THERE MAY BE A
BRIEF PERIOD OF LIGHTER WINDS LATE TONIGHT ESPECIALLY ON THE UPPER
TIDAL POTOMAC.

SCA LEVEL WINDS ARE EXPECTED MON NIGHT THROUGH WED. NEAR GALE FORCE
WIND GUSTS POSSIBLE LATE TUE EVENING AND EARLY WED MORNING ON THE
LOWER BAY AND LOWER TIDAL POTOMAC. WINDS DIMINISH BELOW SCA LEVELS
BY LATE WED. THEN SMALL CRAFT ADVISORY LEVEL CONDITIONS ARE NOT
LIKELY AGAIN THROUGH THE END OF THE WEEK.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES HAVE NOW TURNED POSITIVE AS SOUTHERLY FLOW
PERSISTS. POSITIVE ANOMALIES WILL CONTINUE TO GRADUALLY INCREASE
OVER THE NEXT 48 HOURS. ALTHOUGH CBOFS GUIDANCE KEEPS ALL WRN
SHORE FCST POINTS BELOW MINOR COASTAL FLOOD THRESHOLD...WITH THE
SOUTHERLY FLOW EXPECTED TO PERSIST THRU MONDAY NIGHT AND A FULL
MOON UPCOMING...WE BELIEVEWATER LEVELS COULD APPROACH MINOR FLOOD
CRITERIA AT THE MORE SENSITIVE LOCATIONS AROUND THE HIGHER HIGH
TIDES EARLY MONDAY AND EARLY TUESDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR ANZ530>543.

&&

$$
SYNOPSIS...JRK
NEAR TERM...JE/JRK
SHORT TERM...SMZ
LONG TERM...SMZ
AVIATION...JE/JRK/SMZ
MARINE...JE/SMZ
TIDES/COASTAL FLOODING...JRK/JE





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