Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 161431
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1031 AM EDT WED APR 16 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVERHEAD DURING MIDWEEK...BEFORE MOVE OFFSHORE
LATE IN THE WEEK. AN AREA OF LOW PRESSURE MAY AFFECT THE AREA SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE BUILDS IN FROM OHIO THIS AFTERNOON. GUSTY WINDS THIS
MORNING SHOULD DIMINISH INTO THE AFTERNOON AS THE GRADIENT
RELAXES. ASIDE FROM A FEW CIRRUS THERE WILL BE PLENTY OF SUNSHINE
TODAY BUT DESPITE THE SUNSHINE MAXIMA WILL STRUGGLE TO GET ABOVE
THE 50 DEGREE MARK GIVEN THE COLD AIR MASS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
MIN TEMPS TONIGHT WILL BE MODERATED FROM NELY FLOW COMING OFF MID
40S OCEAN TEMPS AND LOW 50S BAY TEMPS. LEFT FREEZE WARNING DECISION
TO DAY SHIFT SINCE MOST GUIDANCE HAS ZONES IN THE LOW 30S. PIEDMONT
AND CENTRAL FOOTHILLS AREAS HAVE THE BEST CHANCE OF SEEING
SUBFREEZING TEMPS TONIGHT.

LOW CLOUDS SPREAD EAST INTO SRN MD THURSDAY AS THE ONSHORE FLOW
SATURATES. MAX TEMPS GENERALLY INCREASE NE TO SW BASED ON ONSHORE
FLOW...MID 50S FOR NERN MD TO UPR 50S/LOW 60S IN CNTRL SHEN VLY/KCHO.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
HIGH PRES OVR NEW ENGLAND WL BE TRACKING SLOWLY NE THU NGT AND
FRI...LVG THE MID ATLC IN A WEDGING SITUATION WHICH IS XPCTD TO
LEAD TO A PD OF CAD CONDITIONS - NERLY LO LVL WINDS WHICH WL
CREATE A LOW CLD DECK OVR THE RGN E OF THE MTNS. THE SUNNIEST
PLACE IN THE FCST AREA FRI WL LKLY BE W OF THE BLUE RDG. NO PCPN
IS XPCTD - IF ANYTHING WERE TO DVLP IT WOULD BE DZ. LOWS THU NGT
IN THE 30S/L40S. HIGHS FRI 55-60.

ON SAT AN UPR LVL TROF WL TRACK N OF THE AREA...BUT WL DRAG A CD
FNT THRU THE RGN. SOMETIMES CAD ENVIRONMENTS OF LO CLDS CAN HANG
ARND IN THE MID ATLC UP TO 4 DAYS...BUT THIS DOES NOT LOOK TO BE
THE CASE THIS TIME...AS CD FOPA IS PRBLY THE #1 WAY TO DISLODGE
CAD. BUT W/ THIS WL ALSO COME THE PSBLTY OF RA. HIGHS SAT IN THE
M60S.

SUN LOOKING TO BE THE BETTER DAY OF THE WKND FOR OUTDOOR
ACTIVITIES - SKIES SHOULD CLR AS HIGH PRES RETURNS. LOWS SAT NGT
U30S/L40S. HIGHS IN THE LM60S.

TEMPS XPCTD TO SLOWLY CLIMB DURG THE 1ST PART OF THE NEW WK W/ UPR
LVL FLOW MORE OR LESS ZNL. BY TUE HIGH TEMPS SHOULD BE BACK ABV 70
ACROSS MUCH OF THE AREA.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR THROUGH TAF PERIOD AND GUSTY INTO EARLY AFTERNOON AS HIGH
PRESSURE BUILDS NORTHEAST ACROSS THE REGION. ONSHORE FLOW FROM
COLD AIR DAMMING RIDGE TONIGHT...THURSDAY (CONTINUING INTO
SATURDAY).

A CAD SET UP IN XPCTD THU NGT/FRI. THIS WOULD LKLY LEAD TO CIGS IN
THE MVFR RNG. A CD FNT IS XPCTD TO MOVE INTO THE AREA SAT WHICH
COULD PSBLY SPAWN RA/RW. VFR CONDS XPCTD SUN AS HIGH PRES RETURNS.

&&

.MARINE...
HAVE ALLOWED GALES TO EXPIRE AS WIND GUSTS HAVE DROPPED BELOW 30
KT...BUT SCA CONDITIONS ARE LIKELY TO LAST WELL INTO THE AFTERNOON
BEFORE GRADIENT RELAXES ENOUGH. FLOW BECOMES NELY THIS
EVENING...INCREASING TO 20 KT FOR LOWER SRN MD WATERS AFTER
MIDNIGHT (WHEN AN SCA GOES INTO EFFECT)...THEN EXPANDING UP THE
REST OF THE MD BAY BEFORE SUNRISE. ALL BUT THE UPPER TIDAL POTOMAC
IN AN SCA FOR THE DAY THURSDAY WITH NELY FLOW GUSTING AROUND 20
KT.


SMALL CRAFT ADVISORY LEVEL WIND GUSTS ARE POSSIBLE FOR PARTS OF
THE WATERS SAT NIGHT IN A TIGHTENING PRESSURE GRADIENT BETWEEN
LOW PRESSURE DEPARTING TO THE NORTH AND HIGH PRESSURE BUILDING IN
FROM THE WEST.

&&

.TIDES/COASTAL FLOODING...
STRONG NW WINDS HV CAUSED WATER LEVELS IN THE CHES BAY TO DROP TO
2 FT OR MORE FT BLO NRML. TIDAL BLOWOUT CONDITIONS ARE EXPECTED
TO CONTINUE TODAY. MWS HAS BEEN ISSUED FOR THIS. WATER LVLS SHOULD
BEGIN TO RECOVER THIS AFTN.

&&

.CLIMATE...
A VERY COLD AIRMASS FOR MID APRIL IS CAUSING TEMPS TO APPROACH
RECORD MINIMUM TEMPERATURES THIS MORNING. BELOW IS A TABLE OF RECORD
MINIMUM TEMPERATURES FOR APRIL 16 ALONG WITH THE 3 AM TEMPS.

SITE...RECORD LOW TEMP   3 AM WED TEMP
DCA....29 F IN 1928      35
BWI....30 F IN 1962      33
IAD....28 F IN 1981      32

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR
     DCZ001.
MD...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR
     MDZ004>007-009>011-013-014-016>018.
VA...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR
     VAZ036>040-042-050>057-501-502.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
     ANZ531>534-537-539>541-543.
     SMALL CRAFT ADVISORY FROM 3 AM TO 6 PM EDT THURSDAY FOR
     ANZ530>533-538>541.
     SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ530-
     535-536-538-542.
     SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT THURSDAY FOR ANZ536-
     542.
     SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EDT
     THURSDAY FOR ANZ534-537-543.

&&

$$
BPP/BAJ/WOODY!






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