Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 141439 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1039 AM EDT MON APR 14 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OFF THE EAST COAST TODAY. A COLD FRONT
WILL CROSS THE APPALACHIANS LATE TONIGHT AND MOVE THROUGH THE
AREA TUESDAY. HIGH PRESSURE WILL BUILD EAST INTO THE NORTHERN
MID-ATLANTIC WEDNESDAY AND REMAIN OVER THE AREA THROUGH FRIDAY.
LOW PRESSURE MAY IMPACT THE REGION ON SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
A WARM BUT BREEZY S-SWLY WIND WILL BE THE STORY FOR TODAY...
BUILDING UP TO A RAINY AND DYNAMIC TUESDAY. THE WARM WX OF THE
PAST FEW DAYS WILL BE FADING QUICKLY THIS TIME TOMORROW...BUT FOR
TODAY WE`LL HAVE TEMPS SLOWLY CLIMBING INTO THE 70S W/ A GUSTY
SOUTH WIND. DEWPOINTS WILL ALSO BE FAIRLY HIGH...W/ DEWPOINTS WELL
INTO THE U50S AND L60S. THE COMPLEX STORM SYSTEM ON THE WAY FROM
THE WEST IS ACTUALLY A COUPLE OF FEATURES...THE COLDER AND MORE
POTENT COMPLEX IS DRIFTING TOWARD THE GREAT LAKES AND THE OTHER
WILL BE STRENGTHENING OVER THE NEXT DAY OR SO.

SKIES HAVE FILLED-IN QUICKLY THIS MRNG...MAINLY W/ UPPER CIRRUS
DEBRIS BUT THE BOUNDARY LAYER IS ALSO BECOMING SATURATED OVER MUCH
OF THE AREA. THIS WILL TEMPER OUR HIGHS A BIT...FROM THE LACK OF
SUNSHINE BUT STILL MUCH WARMER THAN IT WILL BE ON TUE AFTN/EVE.

FROM PREV DISC...
CONSENSUS OF HIRES GUIDANCE KEEPS ORGANIZED PRECIP WITH THE COLD
FRONT TO THE WEST OF THE ALLEGHENY FRONT UNTIL LATE THIS AFTN AND
SOME OF THE SLOWER MODELS HOLD IT OFF IN THE FAR WEST UNTIL
SUNSET. POPS REFLECT MAINLY SCT COVERAGE OF SHOWERS WEST OF CHO-
OKV-MRB THIS AFTN. CANNOT RULE OUT AN ISO SHOWER THIS AFTN FARTHER
EAST EVEN TOWARD I-95 BUT KEPT IT OUT OF THE FCST FOR NOW WITHOUT
DISCERNIBLE LIFT.

THE COLD FRONT WILL APPROACH THE WRN SIDE OF THE APPALACHIANS THIS
EVE BEFORE CROSSING THE MTS LATE TNGT. TNGT WILL BE MILD WITH
SLY FLOW AND PRE-FRONTAL WARM SECTOR BECOMING INCREASINGLY
ESTABLISHED IN THE MID-ATLANTIC REGION. POPS INCREASE FROM WEST TO
EAST TNGT AS THE COLD FRONT APPROACHES FROM THE WEST. SHOWERS
EXPECTED TO BECOME WIDESPREAD OVNGT INTO ERY TUE MRNG. INSTABILITY
PROFILES RATHER MEAGER ACROSS THE CWA OWING TO WEAK MID-LVL LAPSE
RATES. MENTION OF A SLIGHT CHANCE FOR THUNDER CONFINED TO THE
SHENANDOAH VLY/POTOMAC HIGHLANDS FOR LATE THIS AFTN AND EVE.
HIGHER INSTABILITY FROM THE 00Z NAM WOULD SUPPORT CHANCES FOR
TSTMS EVERYWHERE...BUT A QUICK COMPARISON OF OBS TO THE 6-H NAM
FCST INDICATES THE MODEL WAS ALREADY OVERDOING THE MOISTURE RETURN.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
TUESDAY...A RATHER AMPLIFIED TROUGH/COLD FRONT FROM A HUDSON BAY LOW
SHIFTS EAST ACROSS THE ERN CONUS THROUGH THE DAY...PUSHING OFF THE
COAST THAT NIGHT. THE LOW LEVEL JET INCREASES TO 50-60 KT AHEAD OF
THE COLD FRONT WITH 60F DEWPOINTS SPREADING IN EAST OF THE BLUE
RIDGE. STRONG DYNAMICS CONTINUE ACROSS THE FRONT WITH ARCTIC AIR
SPILLING IN BEHIND. EXPECT SWATHS OF MODERATE TO LOCALLY HEAVY RAIN
WITH GUSTY WINDS AHEAD OF THE FRONT WITH A THIN SQUALL ON THE
LEADING EDGE OF THE FRONT. WENT WITH SCHC OF THUNDER...THOUGH
LIGHTNING IS NOT OFTEN PRESENT WITH QLCS ACTIVITY. SPC DAY TWO
HIGHLIGHTS SERN PORTION OF CWA FOR DAMAGING WIND THREAT. WILL NEED
TO BE ON THE LOOKOUT FOR STRONG GUSTS ACROSS THE BALT-WASH METRO.
THE COLD FRONT IS FAIRLY PROGRESSIVE...SO IN SPITE OF A MAX PWAT
AROUND 1.5 INCHES (ABOVE 2 STDEV FOR KIAD) WIDESPREAD FLOODING IS
NOT EXPECTED. QPF OF HALF TO ONE INCH CAN BE EXPECTED. TEMPERATURES
WILL REACH INTO THE 70S IN THE AFTERNOON AHEAD OF THE FRONT...EAST
OF I-95 (60S FARTHER WEST BUT TO EARLIER FROPA).

RAPID COOL DOWN BEHIND THE COLD FRONT THAT CROSSES LATE AFTERNOON.
THE GROWING SEASON STARTS APRIL 15 EAST OF THE BLUE RIDGE...SO EVEN
THOUGH A FREEZE IS POSSIBLE ACROSS CWA A HEADLINE WOULD ONLY BE EAST
OF THE BLUE RIDGE. MIN TEMPS 20S WEST OF THE BLUE RIDGE AND THE MD
PIEDMONT. LOW 30S VA PIEDMONT AND INTERIOR CENTRAL MD. MAY BE TOO
MUCH MIXING TO ALLOW FROST...SO A FROST ADVISORY MAY NOT BE
NECESSARY FOR LOCATIONS 33-36F MIN TEMPS. SNOWFLAKES ARE POSSIBLE AT
END OF PRECIP ACROSS MOST OF THE CWA...BUT ACCUM SHOULD BE LIMITED
TO ABOVE 2000 FT...UP TO AN INCH OR SO. STRONG WINDS BEHIND THE COLD
FRONT...WIND ADVISORY POSSIBLE FOR RIDGELINES TUESDAY NIGHT...
GUSTING AT LEAST 40 MPH EAST ACROSS THE REST OF THE CWA.

WEDNESDAY...HIGH PRESSURE BUILDS EAST ACROSS THE NRN MID-
ATLANTIC...THEN NEW ENGLAND WEDNESDAY NIGHT. MAX TEMPS AROUND 50F
IS 15 OR SO DEGREES BELOW NORMAL.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SFC PRESSURE RIDGE/COLD AIR DAMMING PERSISTS WEDNESDAY NIGHT THROUGH
FRIDAY NIGHT...UNTIL THE NEXT DISTURBANCE DISLODGES THE ONSHORE
FLOW. EXPECT BELOW NORMAL TEMPS WITH THE ONSHORE FLOW...BECOMING
SATURATED FRIDAY NIGHT. UNCERTAINTY ON WEEKEND SYSTEM ON WHETHER IT
IS A COLD FRONT (LIKE 00Z GFS) OR LOW SYSTEM (LIKE 00Z ECMWF).

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
A SURGE OF LLVL MOISTURE TO OUR SW WILL CONTINUE TO THICKEN THE
2-3KFT STRATUS DECK INTO THE EARLY AFTN HRS. OTHERWISE BREEZY SLY
WINDS GUSTING TO 25 KT TDA.

A COLD FRONT APPROACHES FROM THE WEST TNGT. SHOWERS WILL INCREASE
IN COVERAGE FROM WEST TO EAST TNGT...ESPECIALLY AFTER MIDNIGHT.
MVFR CIGS/VSBYS LIKELY IN SHOWERS WITH THE POTENTIAL FOR IFR BY
ERY TUE MRNG.

STRONG COLD FRONT CROSSES THE TERMINALS TUESDAY WITH WIDESPREAD
RAIN... STRONG SOUTH WIND (AND LLWS) AND LOW CHANCES FOR THUNDER
AHEAD WITH STRONG NW FLOW TUESDAY NIGHT BEHIND. JUST SOME
SNOWFLAKES...NO ACCUM POSSIBLE AT THE TERMINALS. HIGH PRESSURE
WEDNESDAY...WITH COLD AIR DAMMING THEN THROUGH FRIDAY.

&&

.MARINE...
SLY WIND GUSTS NEAR 20-25 KT WILL BE COMMON TDA. SCA CONTINUES
TNGT WITH BREEZY SLY WINDS AHEAD OF AN APPROACHING COLD FRONT.

SCA EXTENDED INTO TUESDAY FOR ALL MARINE ZONES WITH GUSTY SLY
FLOW AHEAD OF A COLD FRONT. TSTMS POSSIBLE TUE AHEAD OF THE COLD
FRONT. STRONG NW WINDS BEHIND THE COLD FRONT LATE AFTERNOON/EARLY
EVENING TUESDAY. GALES MAY BE NEEDED LATE TUESDAY AFTERNOON AND
CERTAINLY TUESDAY NIGHT. SCA THEN FOR WEDNESDAY AS HIGH PRESSURE
BUILDS NORTH. ONSHORE FLOW THEN THROUGH FRIDAY.

&&

.TIDES/COASTAL FLOODING...
POSITIVE TIDAL ANOMALIES OVNGT HAVE BEEN STEADY AROUND ONE-HALF TO
THREE-QUARTERS FOOT ALONG THE WRN SHORE OF THE MD CHSPK BAY. POSITIVE
ANOMALIES WILL CONTINUE TO GRADUALLY INCREASE TDA AND TNGT. WITH
THE SOUTHERLY FLOW EXPECTED TO PERSIST THRU TUESDAY MRNG AND A
FULL MOON UPCOMING...WE BELIEVE WATER LEVELS COULD APPROACH MINOR
FLOOD CRITERIA AT THE MORE SENSITIVE LOCATIONS AROUND TIMES OF THE
HIGHER HIGH TIDES EARLY TUESDAY MRNG. CBOFS GUIDANCE HOWEVER FCSTS
TIDAL LVLS BELOW MINOR COASTAL FLOODING THRESHOLDS AT ALL SITES.

&&

.CLIMATE...
UNUSUALLY WARM CONDITIONS WERE OBSERVED ACROSS THE AREA EARLY THIS
MORNING. LOW TEMPERATURES WERE AROUND 20 DEGREES ABOVE NORMAL.
DEPENDING ON HOW LOW TEMPERATURES GET THIS EVENING...RECORD DAILY
HIGH MINIMUM TEMPERATURES COULD BE TIED OR BROKEN AT DCA...BWI AND
IAD. BELOW IS A TABLE OF RECORDS FOR THE DAY AND LOW TEMPERATURES
OBSERVED SO FAR.

SITE...PREVIOUS RECORD...LOW SO FAR...
DCA....63 F IN 1896......65 F.........
BWI....62 F IN 1896......62 F.........
IAD....58 F IN 1972......63 F.........

&&

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

&&

$$
UPDATE...GMS
PREV DISCUSSION...JRK/BAJ








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