Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 170800 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 400 AM EDT THU APR 17 2014 SYNOPSIS... HIGH PRESSURE OVER NEW ENGLAND WILL RIDGE SOUTHWARD TOWARD THE MID-ATLANTIC COAST THROUGH THE REMAINDER OF THE WEEK. AN AREA OF LOW PRESSURE AND COLD FRONT MAY AFFECT THE AREA SATURDAY. A SECOND COLD FRONT LOOKS TO MOVE THROUGH THE REGION TUESDAY. && .NEAR TERM /TODAY/...
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AS OF 07Z...1041MB SFC HIGH CENTERED OVER NRN MAINE WITH A SFC RIDGE/COLD AIR DAMMING WEDGE EXTENDING SOUTHWEST DOWN THE PIEDMONT TO THE DEEP SOUTH STATES. THE RIDGE AXIS ROUGHLY EXTENDS DOWN I-95 WITH ELY FLOW OVER THE BAY AND SRN MD AND MAINLY CALM CONDITIONS ELSEWHERE. SKIES ARE CLEAR WITH OFFSHORE LOW CLOUDS ALONG THE GULF STREAM/LABRADOR CURRENT BOUNDARY OFF THE DELMARVA (ACCORDING TO GOES-EAST IR IMAGERY). TEMPERATURES ARE GENERALLY LOW TO MID 30S WITH UPR 30S FOR NEARSHORE AND URBAN AREAS. THE WEDGE PERSISTS TODAY. ABUNDANT SUNSHINE AGAIN...THOUGH EAST OF THE RIDGE AXIS COULD SEE MARINE LAYER CLOUDS SPREAD IN FROM THE OCEAN (THE DAY SHIFT WILL NEED TO MONITOR THIS). THE WARM MID APRIL SUN WILL CONTINUE TO MODIFY THE AIRMASS WITH MAX TEMPS GENERALLY MID 50S ACROSS THE BALT-WASH METRO WITH UPR 50S TO LOW 60S OVER WEST AND SOUTHWEST SECTIONS OF THE CWA. AREAS WEST OF THE BLUE RIDGE SHOULD BE WELL PROTECTED FROM LOW CLOUDS AND COULD WARM INTO THE MID 60S.
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&& .SHORT TERM /TONIGHT THROUGH FRIDAY/...
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THE QUESTION FOR TONIGHT IS WILL LIGHT FLOW PREVENT DECOUPLING AND WILL LOW CLOUDS SPREAD ACROSS AT LEAST EASTERN SECTIONS OF THE CWA. NAM FORECAST SOUNDINGS ARE CLOUDIER THAN GFS ONES...AND THUS MET GUIDANCE MIN TEMPERATURES ARE HIGHER THAN MAV ONES. NORTH CENTRAL MARYLAND SEEMS TO BE THE COLDEST AREAS WITH AN ACTIVE GROWING SEASON TONIGHT. WITH MINS FORECAST IN THE LOW 30S...WENT AHEAD WITH A FREEZE WATCH FOR FREDERICK MD TO HARFORD. DAY SHIFT WILL HAVE TO DETERMINE IF A FROST/FREEZE OR NEITHER IS NECESSARY. FRIDAY...MODIFICATION/MODERATION CONTINUES WITH MAX TEMPS IN THE UPR 50S EAST TO MID 60S WEST. CLOUD COVER WILL CONTINUE TO PLAY AN IMPORTANT ROLE WITH THE SFC RIDGE AXIS NEARLY STATIONARY.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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MID ATLC HAS XPRNCD WHAT SEEMED LK A NEVERENDING SERIES OF WVS. BUT FOR A CHG THE WX SHOULD BE RLVTLY BENIGN IN THE XTND - NO WINTRY CONCERNS FOR ONE THING. OVERALL UPR LVL FLOW COULD BE CHARACTERIZED AS A FAIRLY HIGH ZNL NEAR THE U.S./CANADIAN BORDER. THIS WL AID IN KEEPING TEMPS ON THE MODERATE SIDE - NEITHER TOO HOT OR COLD...MORE LK WHAT SHOULD BE OCCURRING IN MID APR. ONE SHORT WV IS XPCTD TO PUSH THRU THE NERN U.S. BUT THIS IS LOOKING LESS AND LESS LK A PCPN PRODUCER. THE NEXT PCPN CHC LOOKS TO BE ON TUE W/ ANOTHER FROPA. NO COLD TEMPS TO WORRY ABT - HIGHS IN THE L70S...LOWS IN THE U40S/L50S.
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&& .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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VFR AT LEAST INTO THE AFTERNOON ACROSS THE TERMINALS. A SFC RIDGE WILL PERSIST OVER THE AREA WITH AN ONSHORE FLOW I-95 AND EAST. OCEAN CLOUDS WITH MVFR CIGS MAY MOVE IN LATE TODAY/TONIGHT IN THIS ONSHORE FLOW. RISK FOR MVFR CIGS ALSO FOR FRIDAY. VFR CONDS ARE XPCTD FOR THE MAJORITY OF THE XTND PD.
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&& .MARINE...
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ONSHORE FLOW ACROSS THE WATERS. OFTEN TIMES THIS FLOW IS STRONGER THAN PROGGED BY MODELS. SO FAR HOWEVER...ELY FLOW HAS MAINLY BEEN GUSTING TO 15 KT...LESS THAN PROGGED BY MODELS. STILL EXPECT IT TO INCREASE THIS MORNING AS NELY FLOW OVERSPREADS THE WATERS. A BIT OF A LULL DURING THE AFTERNOON...THEN ONSHORE FLOW INCREASES AGAIN. SCA MOST OF THE MD PART OF THE BAY THIS MORNING...THEN SRN MD WATERS FOR THE AFTERNOON. MOST OF THE WATERS IN AN SCA TONIGHT. ONSHORE FLOW LOOKS TO BE SUB SCA FOR FRIDAY. WINDS MAY GUST TO 20 KT ON SAT. NO PROBS FORESEEN SUNDAY.
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&& .CLIMATE...
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RECORD LOWS FOR APRIL 17... 3 AM TEMP BWI...26F IN 1962 33 DCA...26F IN 1875 41 IAD...27F IN 1983 30
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&& .EQUIPMENT...
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MANASSAS NWR XTMR IS WORKING INTERMITTENTLY. PHONE TECHNICIANS HAVE BEEN NOTIFIED.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR DCZ001. MD...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MDZ004>007- 009>011-013-014-016>018. FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR MDZ004>007. VA...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR VAZ036>040-042- 050>057-501-502. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 AM EDT FRIDAY FOR ANZ532>534-537- 540-541-543. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 3 AM EDT FRIDAY FOR ANZ531-536-538-539-542. SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR ANZ530- 531-538-539.
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&& $$ PRODUCTS...BAJ/WOODY!

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