661  
FXUS61 KLWX 250033  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
833 PM EDT SAT JUN 24 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD WEST OF THE AREA THROUGH THE REST OF  
THE WEEKEND AND INTO NEXT WEEK AS A SERIES OF WEAK COLD FRONTS  
CROSS THE REGION. THESE FRONTS WILL BRING WITH THEM LITTLE IF  
ANY PRECIPITATION. THE SPRAWLING SURFACE RIDGE WILL THEN CROSS  
THE REGION WEDNESDAY AND SETTLE OVER THE WESTERN ATLANTIC OCEAN  
LATE IN THE WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
A COUPLE SHOWERS HAVE POPPED UP OVER WEST VIRGINIA THIS EVENING.  
AN ISOLATED SHOWER CANNOT BE RULED OUT IN THE ALLEGHENY AND  
POTOMAC HIGHLANDS THIS EVENING...BUT MOST PLACES WILL END UP  
DRY. LATEST MESOANALYSIS SHOWS LITTLE TO NO INSTABILITY EAST OF  
THE ALLEGHENY HIGHLANDS.  
 
HIGH PRESSURE WILL CONTINUE TO BUILD FROM THE WEST TONIGHT. A  
WEST TO NORTHWEST FLOW AHEAD OF THE HIGH WILL USHER IN DRY AND  
COMFORTABLE CONDITIONS FOR THIS TIME OF YEAR. MIN TEMPS WILL  
RANGE FROM THE 50S IN THE ALLGHENY AND POTOMAC HIGHLANDS...TO  
THE 60S ACROSS MOST OTHER LOCATIONS...TO THE LOW 70S IN DOWNTOWN  
WASHINGTON AND BALTIMORE.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
 
 
UPPER LEVEL TROUGHING OVER THE NORTHEASTERN US WILL DEFINE THE  
REST OF THE WEEKEND AND EARLY WEEK PERIOD, WITH A SPRAWLING  
SURFACE HIGH DEVELOPING OVER THE MIDWEST AND OHIO VALLEY. THIS  
WILL ALLOW SEVERAL WEAK FRONTAL FEATURES TO DROP THROUGH THE  
NORTHEAST STATES DURING THIS TIME.  
 
THE FIRST WILL CROSS PORTIONS OF THE NORTHEAST ON SUNDAY. FOR  
THE MOST PART THIS WILL REMAIN OFF TO OUR NORTHEAST, WITH  
WESTERLY FLOW AND A MIX OF SUN AND CLOUDS. HIGHS FROM 75-85F.  
FAIR WEATHER CONTINUES SUNDAY NIGHT, WITH TEMPERATURES COOLING  
OFF INTO THE 50S/60S.  
 
THE NEXT WEAK FRONTAL PASSAGE WILL OCCUR ON MONDAY, BRINGING  
WITH IT ADDITIONAL CUMULUS AND PERHAPS A FEW ISOLATED SHOWERS.  
HIGHS MONDAY IN THE 70S TO AROUND 80F, DROPPING OFF AT NIGHT  
INTO THE 50S TO AROUND 60F.  
 

 
   
LONG TERM /TUESDAY THROUGH SATURDAY/
 
 
UPPER LEVEL TROUGH AND ITS ASSOCIATED SURFACE REFLECTION WILL  
SLIDE EAST, AND ITS AXIS WILL MOVE ACROSS OUR AREA TUESDAY. THIS  
TROUGH COULD CREATE ENOUGH INSTABILITY TO ALLOW FOR SOME  
SHOWERS AND THUNDERSTORMS MAINLY TUESDAY AFTERNOON. TEMPERATURES  
WILL BE BELOW NORMAL WITH HIGHS IN THE 60S AND 70S, AND LOWS IN  
THE 40S AND 50S.  
 
SURFACE HIGH PRESSURE BUILDS EAST TUESDAY NIGHT, THEN MOVES OFFSHORE  
LATE WEDNESDAY, SETTLING AS A BERMUDA HIGH INTO THURSDAY AS  
FLOW BECOMES MORE SOUTHERLY. TEMPERATURES WILL BE ON THE RISE  
AND DRY CONDITIONS CONTINUE INTO THURSDAY NIGHT. GUIDANCE  
SUGGEST THAT UPPER LEVEL ENERGY COULD BRING SHOWERS AND  
THUNDERSTORMS OVER PARTS OF OUR AREA FRIDAY INTO SATURDAY. COLD  
FRONT APPROACHES FROM WEST ON SATURDAY.  
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
VFR EXPECTED THROUGH THE FORECAST PERIOD. GUSTS OUT OF THE  
WEST/NORTHWEST TO AROUND 20 KNOTS LIKELY SUNDAY AND MONDAY. AN  
ISOLATED SHOWER COULD ALSO OCCUR MONDAY WITH A WEAK COLD FRONT,  
BUT COVERAGE WILL BE EXTREMELY LIMITED.  
 
SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE TUESDAY AS UPPER  
AIR DISTURBANCE MOVES THROUGH, WHICH COULD CAUSE PERIODS OF SUB-  
VFR CONDITIONS. VFR CONDITIONS RETURN TUESDAY NIGHT INTO  
THURSDAY WITH HIGH PRESSURE BUILDING IN.  
 

 
   
MARINE
 
 
WINDS HAVE DIMINISHED THIS EVENING. A PRESSURE SURGE BEHIND A  
TROUGH IS EXPECTED LATE TONIGHT. NORTHWEST WINDS MAY APPROACH  
SCA CRITERIA ALONG THE BAY AND LOWER TIDAL POTOMAC RIVER.  
HOWEVER...CONFIDENCE IS TOO LOW FOR AN SCA AT THIS TIME SINCE  
THE SURGE WILL BE WEAK. WILL CONTINUE TO MONITOR OVERNIGHT.  
 
ADDITIONAL GUSTS UP TO ABOUT 20 KNOTS LIKELY SUNDAY  
AFTERNOON/EVENING ACROSS THE NORTHERN CHESAPEAKE BAY, SO HAVE  
ISSUED A SMALL CRAFT ADVISORY FROM 1 PM THROUGH 10 PM. AS COOLER  
AIR MOVES IN OVER WARMER WATER TEMPERATURES SUNDAY NIGHT,  
INCREASED MIXING MAY LEAD TO THESE WINDS PERSISTING THROUGH  
SUNDAY NIGHT...BUT CONFIDENCE FOR AN ADVISORY IS TOO LOW AT THIS  
TIME SINCE THE PRESSURE GRADIENT WILL BE WEAK.  
 
ADDITIONAL GUSTS NEAR SCA CRITERIA MAY OCCUR MONDAY AND MONDAY  
NIGHT WITH PERSISTENT WEST-NORTHWEST FLOW AND WEAK FRONTAL  
PASSAGES.  
 
SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE TUESDAY  
AS UPPER AIR DISTURBANCE MOVES THROUGH. CONDITIONS IMPROVE TUESDAY  
NIGHT WITH HIGH PRESSURE BUILDING IN AND WEATHER REMAINING DRY INTO  
THURSDAY. WINDS GUSTS WILL BE BELOW THE SMALL CRAFT ADVISORY  
CRITERIA TUESDAY THROUGH EARLY THURSDAY. WIND GUSTS WILL INCREASE  
THURSDAY AFTERNOON.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 1 PM TO 10 PM EDT SUNDAY FOR  
ANZ530>532-538>540.  
 

 
 

 
SYNOPSIS...MM  
NEAR TERM...BJL/MM  
SHORT TERM...MM  
LONG TERM...IMR  
AVIATION...BJL/MM/IMR  
MARINE...BJL/MM/IMR  
 
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