Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 160758 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 358 AM EDT WED APR 16 2014 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD OVERHEAD DURING MIDWEEK...BEFORE MOVE OFFSHORE LATE IN THE WEEK. AN AREA OF LOW PRESSURE MAY AFFECT THE AREA SATURDAY.
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&& .NEAR TERM /TODAY/...
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AS OF 07Z...1028MB SFC HIGH CENTERED OVER SWRN OHIO WILL INTENSIFY AS IT MOVES NORTHEAST ACROSS THE NRN MID-ATLANTIC TODAY. PRESSURE GRADIENT SLOWLY DECREASES THROUGH THE DAY...WITH NWLY GUSTS OF 30 TO 35 MPH EASING THROUGH THE AFTERNOON AND BECOMING NLY. NELY FLOW TONIGHT AS A SFC RIDGE STALLS OVER THE AREA...SETTING UP COLD AIR DAMMING THAT WILL PERSIST INTO THE WEEKEND. MAX TEMPS AROUND 50F TODAY CWA WIDE (LOW 50S S OF KCHO).
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&& .SHORT TERM /TONIGHT THROUGH THURSDAY/...
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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.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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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.
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&& .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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VFR THROUGH TAF PERIOD AND GUSTY TODAY AS HIGH PRESSURE BUILDS NORTHEAST ACROSS THE REGION. NW WINDS GUSTING AROUND 30 KT EARLY THIS MORNING SLOWLY EASE THROUGH THE DAY. 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.
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&& .MARINE...
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NWLY GALES OBS HAVE BEEN FAIRLY FEW AND FAR BETWEEN...EXCEPT WHERE CHANNELING IS OCCURRING (SUCH AS AT COVE PT WHICH HAS HAD GUSTS AROUND 40 KT). DCA HAD A 240 AM PEAK GUST OF 34 KT...SO THE GALE WARNING WILL REMAIN UP FOR NOW FOR ALL WATERS. WILL PROBABLY BE ABLE TO DROP BEFORE 6AM FOR NWRN PORTIONS OF THE WATERS...BUT EXTENDED UNTIL 9AM FOR LOWER SRN MD WATERS FOR CONTINUED CHANNELING. SCA FOR ALL WATERS TO 2PM AND MOST MD BAY UNTIL 6PM. 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.
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&& .TIDES/COASTAL FLOODING...
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STRONG NW WINDS HV CAUSED WATER LEVELS IN THE CHES BAY TO DROP TO 1 TO 1.5 FT BLO NRML. TIDAL BLOWOUT CONDITIONS ARE EXPECTED TO CONTINUE TODAY WITH ANOMALIES UP TO 2 FEET BELOW NORMAL. MWS HAS BEEN ISSUED FOR THIS. WATER LVLS SHOULD BEGIN TO RECOVER THIS AFTN.
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&& .CLIMATE...
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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
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR DCZ001. FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR DCZ001. MD...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR MDZ004>007-009>011-013-014-016>018. FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MDZ011-013-014- 016>018. FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MDZ004>007-009- 010. VA...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR VAZ036>040-042-050>057-501-502. FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR VAZ052>057. FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR VAZ036>040-042- 050-051-501-502. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EDT THIS EVENING FOR ANZ531-532-537-539>541. SMALL CRAFT ADVISORY FROM 3 AM TO 6 PM EDT THURSDAY FOR ANZ530>533-538>541. GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ530>532- 535>542. SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 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 9 AM THIS MORNING TO 6 PM EDT THIS EVENING FOR ANZ533-534-543. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EDT THURSDAY FOR ANZ534-537-543. GALE WARNING UNTIL 9 AM EDT THIS MORNING FOR ANZ533-534-543.
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&& $$ PRODUCTS...BAJ/WOODY!

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