141  
FXUS61 KLWX 290736  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
336 AM EDT WED MAR 29 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD OVERHEAD THROUGH TONIGHT BEFORE MOVING  
OFF THE COAST THURSDAY. LOW PRESSURE WILL PASS THROUGH THE AREA  
THURSDAY NIGHT THROUGH FRIDAY NIGHT AND THE COLD FRONT  
ASSOCIATED WITH THE LOW WILL PASS THROUGH SATURDAY. HIGH  
PRESSURE WILL RETURN FOR SUNDAY BEFORE LOW PRESSURE POSSIBLY  
IMPACTS THE AREA MONDAY AND TUESDAY OF NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH 6 PM THIS EVENING/
 
 
RIDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH THE DAY  
TODAY BEHIND THE DEPARTING FRONTAL SYSTEM THAT BROUGHT THE SHOWERS  
AND THUNDERSTORMS YESTERDAY. THERE ARE STILL PLENTY OF LOW CLOUDS  
AND EVEN SOME PATCHY FOG AND DRIZZLE OUT THERE EARLY THIS MORNING,  
BUT AS COOL AND DRY AIR ADVECTION TAKE HOLD, MARKED CLEARING IS  
EXPECTED TO DEVELOP BY MID TO LATE MORNING. OVERALL A NICE EARLY  
SPRING DAY WITH A NORTHERLY BREEZE FROM ABOUT 5 TO 15 MPH  
GUSTING UP TO 20 MPH. HIGHS 60-70F.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/
 
 
AS RIDGE BUILDS FROM CENTRAL CANADA AND INTO THE NORTHEASTERN  
STATES, WE'LL SEE IT WEDGE DOWN THE EASTERN US COASTLINE TONIGHT AND  
THROUGH THURSDAY, PROMOTING NORTHEASTERLY FLOW AND COOLER  
TEMPERATURES. MAIN SURGE OF THIS APPEARS TO OCCUR OVERNIGHT TONIGHT  
WITH SHIFT TO NORTHEAST WINDS AND NOTICEABLE DROP/GRADIENT OF 925MB  
TEMPERATURES. THEREFORE WHILE TONIGHT WILL START MOSTLY CLEAR FOR  
MOST LOCATIONS, DEVELOPING EASTERLY FLOW MAY LEAD TO THE DEVELOPMENT  
OF A STRATUS DECK OF CLOUDS, ESPECIALLY ALONG THE EASTERLY UPSLOPE  
FAVORED LOCATIONS ACROSS THE HIGHLANDS AND BLUE RIDGE. COULD EVEN  
SEE SOME LIGHT RAIN OR DRIZZLE DEVELOP TOWARDS MORNING IN THOSE  
LOCATIONS. LOWS TONIGHT 35-42F.  
 
CAD WILL MORE OR LESS REMAIN IN PLACE IN THE LOW LEVELS THURSDAY. AT  
THE SAME TIME, LOW PRESSURE SYSTEM WILL BE EJECTING OUT OF THE  
PLAINS WITH WARM/MOIST AIR ADVECTION. THIS WILL LEAD TO CLOUDS AND  
PERHAPS SOME SHOWERS BY LATER IN THE DAY ACROSS WESTERN AREAS,  
ALTHOUGH THE BEST FORCING ON THURSDAY WILL REMAIN TO THE NORTHWEST.  
HIGHS THURSDAY WILL REMAIN IN THE 50S UNDER THE CLOUDS/EASTERLY  
FLOW.  
 
WARM AND MOIST AIR ADVECTION CONTINUES THURSDAY NIGHT AND WITH THAT  
WE'LL SEE INCREASING CHANCES FOR RAIN SHOWERS. LOWS MAINLY IN THE  
40S. MODEL GUIDANCE IN GOOD AGREEMENT THAT THE LOW PRESSURE SYSTEM  
WILL TRACK EAST-NORTHEASTWARD FROM NEAR ST. LOUIS THURSDAY EVENING  
TO OHIO BY FRIDAY AFTERNOON, BEFORE REDEVELOPING NEAR THE DELMARVA  
LATE FRIDAY AND FRIDAY NIGHT. THUS, MOST WIDESPREAD COVERAGE OF RAIN  
EXPECTED FROM FRIDAY AND INTO THE FIRST HALF OF FRIDAY NIGHT. WE'LL  
ALSO HAVE TO MONITOR HOW FAR NORTH THE WARM SECTOR CAN MAKE IT  
FRIDAY AFTERNOON. LATEST GFS INDICATES IT MAY APPROACH PORTIONS OF  
CENTRAL VA AND SOUTHERN MD, SO HAVE INTRODUCED A CHANCE OF TSTORMS  
THERE FRIDAY AFTERNOON. HIGHS ON FRIDAY 50-60F. SHOWERS WILL  
CONTINUE FRIDAY NIGHT, BUT GRADUALLY BEGIN TO TAPER OFF AS THE LOW  
PULLS AWAY.  
 

 
   
LONG TERM /SATURDAY THROUGH TUESDAY/
 
 
LOW PRESSURE WILL MOVE AWAY FROM THE AREA SATURDAY...BUT A WEAK  
COLD FRONT ASSOCIATED WITH THE LOW WILL PASS THROUGH DURING THE  
AFTERNOON AND EVENING HOURS. A FEW SHOWERS CANNOT BE RULED  
OUT...BUT MUCH OF THE TIME SHOULD TURN OUT DRY DUE TO A  
NORTHWEST FLOW AND SUBSIDENCE BEHIND THE DEPARTING LOW.  
 
HIGH PRESSURE WILL BUILD OVERHEAD FOR LATER SATURDAY NIGHT  
THROUGH SUNDAY...BRINGING DRY AND COOL CONDITIONS.  
 
HIGH PRESSURE WILL MOVE OFFSHORE MONDAY AND LOW PRESSURE MAY  
IMPACT THE AREA MONDAY NIGHT AND TUESDAY WITH UNSETTLED  
CONDITIONS POSSIBLE.  
 

 
   
AVIATION /07Z WEDNESDAY THROUGH SUNDAY/
 
 
LINGERING MVFR IN SOME STRATUS EARLY THIS MORNING WILL GIVE WAY TO  
VFR AND CLEARING SKIES BY MID TO LATE MORNING AS DRIER AIR WORKS  
INTO THE REGION. VFR WILL CONTINUE THROUGH THIS AFTERNOON AND  
THROUGH AT LEAST THE FIRST HALF OF TONIGHT. NORTHERLY WINDS FROM 5-  
10 KNOTS WITH GUSTS 15-18 KNOTS EXPECTED THROUGH TODAY.  
 
WINDS WILL TURN NORTHEASTERLY LATER TONIGHT, AND EAST-SOUTHEASTERLY  
ON THURSDAY. THIS WILL HELP USHER IN ADDITIONAL CLOUDS, ALTHOUGH  
CEILINGS STILL EXPECTED TO REMAIN VFR. HIGHEST CHANCES FOR SOME MVFR  
CEILINGS WILL BE AT CHO AND MRB.  
 
GREATER CHANCES FOR SUB-VFR CONDITIONS WILL OCCUR THURSDAY NIGHT  
THROUGH FRIDAY NIGHT WITH WIDESPREAD RAINFALL. IFR CONDITIONS  
LIKELY.  
 
A NORTHWEST FLOW WILL ALLOW FOR CIGS/VSBYS TO IMPROVE SATURDAY  
BEHIND DEPARTING LOW PRESSURE...BUT A FEW SHOWERS CANNOT BE  
RULED OUT. HIGH PRESSURE WILL BUILD OVERHEAD FOR SATURDAY NIGHT  
THROUGH SUNDAY.  
 

 
   
MARINE
 
 
LIGHT NORTHERLY FLOW TO START THE MORNING WILL INCREASE DURING  
THE MORNING HOURS AS NORTHERLY FLOW STRENGTHENS, AND A SMALL  
CRAFT ADVISORY GOES INTO EFFECT AT 6 AM FOR ALL OF THE WATERS.  
GUSTS WILL THEN TAPER OFF LATER THIS AFTERNOON AND SCA EXPIRES  
AT 6 PM FOR SOME OF THE WATERS. A SECOND SURGE OF NORTHEASTERLY  
WINDS IS EXPECTED LATER TONIGHT, AND A SCA WILL CONTINUE FOR THE  
CHESAPEAKE BAY AND LOWER TIDAL POTOMAC UNTIL 6 AM THURSDAY.  
 
SUB-SCA WINDS THEN EXPECTED THURSDAY, WITH NEXT POTENTIAL FOR  
INCREASING WINDS ON THURSDAY NIGHT/FRIDAY AHEAD OF OUR NEXT  
SYSTEM, ESPECIALLY ACROSS OUR SOUTHERN WATERS.  
 
LOW PRESSURE WILL MOVE AWAY FROM THE WATERS SATURDAY AND  
NORTHWEST FLOW WILL DEVELOP. A SMALL CRAFT ADVISORY MAY BE  
NEEDED FOR PORTIONS OF THE WATERS DURING THIS TIME. HIGH  
PRESSURE WILL BUILD OVERHEAD SATURDAY NIGHT INTO SUNDAY BEFORE  
MOVING OFFSHORE MONDAY.  
 

 
   
TIDES/COASTAL FLOODING
 
 
LOW PRESSURE WILL PASS THROUGH THE AREA FRIDAY NIGHT. AN  
ONSHORE FLOW WILL DEVELOP AHEAD OF THE LOW AND THIS WILL CAUSE  
ELEVATED WATER LEVELS FRIDAY INTO FRIDAY NIGHT. MINOR TIDAL  
FLOODING NEAR HIGH TIDE IS POSSIBLE DURING THIS TIME.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ530>534-  
537-539>541-543.  
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ535-  
536-538-542.  
 

 
 

 
SYNOPSIS...BJL  
NEAR TERM...MM  
SHORT TERM...MM  
LONG TERM...BJL  
AVIATION...BJL/MM  
MARINE...BJL/MM  
TIDES/COASTAL FLOODING...BJL  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab VA Page
The Nexlab MD Page
The Nexlab WV Page Main Text Page