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Area Forecast Discussion

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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/...

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.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...

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.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

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.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...

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.

&&

.MARINE...

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.

&&

.CLIMATE...

RECORD LOWS FOR APRIL 17...
                     3 AM TEMP
BWI...26F IN 1962    33
DCA...26F IN 1875    41
IAD...27F IN 1983    30

&&

.EQUIPMENT...

MANASSAS NWR XTMR IS WORKING INTERMITTENTLY. PHONE TECHNICIANS HAVE
BEEN NOTIFIED.



&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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.

&&

$$
PRODUCTS...BAJ/WOODY!





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