930  
FXUS61 KLWX 160045 AAA  
AFDLWX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
845 PM EDT SUN SEP 15 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA TONIGHT,  
BEFORE PUSHING TO OUR SOUTHEAST ON MONDAY. WARM ON MONDAY, AS  
SOUTHERLY FLOW RETURNS AHEAD OF ANOTHER COLD FRONT THAT WILL  
PUSH THROUGH THE REGION TOMORROW NIGHT INTO TUESDAY MORNING,  
WITH SHOWERS POSSIBLE. HIGH PRESSURE THEN BUILDS ACROSS THE  
NORTHEASTERN US THROUGH THE END OF THE WEEK, LEADING TO DRY  
WEATHER AND COOLER TEMPERATURES.  
 

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
HIGH PRESSURE WILL SLIDE OVERHEAD TONIGHT, WITH MOSTLY CLEAR  
SKIES EXPECTED TO CONTINUE ACROSS THE MAJORITY OF THE REGION.  
SOME PATCHY FOG IS EXPECTED TO DEVELOP IN THE FAVORED RURAL AND  
VALLEY LOCATIONS. ADDITIONALLY, LATEST GUIDANCE IS INDICATING  
THAT SOME LOW CLOUDS/FOG MAY ALSO TRY TO DEVELOP ACROSS MUCH OF  
CENTRAL VIRGINIA TOWARDS RICHMOND, AND MAY REACH UP INTO THE  
CENTRAL VA PIEDMONT, AND EVEN POSSIBLY INTO SOUTHERN MD. LOWS  
TONIGHT WILL BE IN THE LOW 60S FOR MUCH OF THE AREA, WITH THE  
USUAL URBAN HOT SPOTS HOLDING IN THE UPPER 60S.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
 
 
SURFACE HIGH PRESSURE SHIFTS TO THE SOUTHEAST ON MONDAY, PUSHING  
OFFSHORE. THIS WILL RESULT IN WARM SOUTHEASTERLY FLOW, WHICH  
WILL LEAD TO A WARMER DAY TOMORROW. MONDAY IS LIKELY TO BE THE  
WARMEST DAY OF THE FORECAST PERIOD WITH HIGHS REACHING THE UPPER  
80S TO NEAR 90. TEMPERATURES COULD BE SOMEWHAT LIMITED UP NORTH,  
AS A COLD FRONT WILL BE PUSHING INTO THE REGION LATE MONDAY INTO  
TUESDAY MORNING. CLOUDS AHEAD OF THIS FRONT COULD KEEP THINGS  
SLIGHTLY COOLER ALONG THE MASON-DIXON LINE, DEPENDING ON  
EXACTLY WHEN THEY ARRIVE. ADDITIONALLY, GUIDANCE HAS BEE  
PERSISTENTLY SHOWING SOME SHOWERS ACROSS THE POTOMAC HIGHLANDS  
MONDAY AFTERNOON IN ASSOCIATION WITH THIS FRONT, SO HAVE UPPED  
POPS A BIT TO SHOW THIS. NOT SEEING A LOT OF CONVECTIVE  
POTENTIAL THOUGH, AS MOISTURE RETURN TO THAT REGION LIKELY WON'T  
BE QUICK ENOUGH. KEEPING WITH SLIGHT CHANCE TO LOW END CHANCE  
POPS THROUGH THE AFTERNOON.  
 
INCREASED CLOUD COVER ELSEWHERE LATE MONDAY INTO TUESDAY  
MORNING AS THE FRONTAL BOUNDARY PUSHES THROUGH, BUT THINKING IT  
WILL BE TOO DRY FOR SHOWERS TO MAKE IT EAST OF THE BLUE RIDGE.  
LOW TEMPERATURES ON MONDAY NIGHT WILL BE IN THE MID 60S.  
 
A MUCH DRIER AIR MASS PUSHES INTO THE REGION BEHIND THIS COLD  
FRONT, WITH NORTHWEST FLOW RETURNING. CLOUDS SHOULD QUICKLY  
CLEAR ON TUESDAY, WITH ABUNDANT SUNSHINE EXPECTED INTO THE  
AFTERNOON. HIGH TEMPERATURES WILL ONLY REACH THE MID TO UPPER  
70S. CLEAR AND COOLER ON TUESDAY NIGHT, WITH LOW TEMPERATURES  
DOWN INTO THE MID 50S.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
THE EXTENDED WILL FEATURE HIGH PRESSURE ALONG WITH A CONTINUATION OF  
THE RECENT DRY WEATHER AND SLIGHTLY BELOW NORMAL TEMPERATURES. FROM  
MID-WEEK THROUGH THE FIRST PART OF THE WEEKEND...A STRONG RIDGE OF  
HIGH PRESSURE WILL EXTEND FROM NEW ENGLAND DOWN THE EASTERN SEABOARD  
TO THE MID-ATLANTIC AND DOMINATE CONDITIONS HERE. PRECIPITABLE WATER  
VALUES DURING THE EXTENDED WILL BE LESS THAN 0.75 INCHES...AND ON  
THUR AND FRI BELOW 0.5 INCHES. THE ONLY CHALLENGE WILL BE THE  
DIRECTION OF LOW LEVEL FLOW OFF THE ATLANTIC. IF PARCEL TRAJECTORIES  
CAN PICK UP ENOUGH ATLANTIC MOISTURE...THAT COULD CAUSE SOME  
CLOUDINESS TO BE BANKED UP EAST OF THE BLUE RIDGE LATE IN THE WEEK.  
BUT THE AIRMASS WILL BE VERY DRY. VERTICAL 12Z GFS PROFILES SUGGEST  
SOME CLOUDS DURING THE DAY WEDNESDAY INTO WEDNESDAY NIGHT. OTHER  
THAN THAT, CLEAR WEATHER IS EXPECTED.  
 

 
   
AVIATION /01Z MONDAY THROUGH FRIDAY/
 
 
SHOULD REMAIN MAINLY VFR THROUGH MONDAY EVENING, ALTHOUGH SOME  
PATCHY FOG AND REDUCTIONS ARE POSSIBLE AT CHO/MRB OVERNIGHT INTO  
EARLY MONDAY MORNING. A BACKDOOR COLD FRONT WILL PUSH SOUTH  
LATER MONDAY NIGHT INTO TUESDAY MORNING, AND MAY BRING SOME  
BRIEF SUB- VFR INTERVALS, MOST LIKELY WITH REGARDS TO CIGS, BUT  
THESE LIKELY ARE TRANSIENT AND RETURN TO VFR BY TUESDAY  
AFTERNOON.  
 
HIGH PRESSURE IS EXPECTED WEDNESDAY INTO THE LATER PART OF NEXT  
WEEK. EXPECTING VFR FOR THE EXTENDED WITH BRIEF LOCALIZED MVFR/IFR  
CONDITIONS POSSIBLE DUE TO MORNING FOG AT CHO/MRB.  
 

 
   
MARINE
 
 
LIGHT WINDS ARE EXPECTED TONIGHT WITH HIGH PRESSURE OVERHEAD.  
WINDS MAY INCREASE A BIT ON MONDAY AFTERNOON AHEAD OF ANOTHER  
COLD FRONT. BEST CHANCE OF SCA LOOKS TO BE OVERNIGHT MONDAY INTO  
TUESDAY AS THAT FRONT PASSES AND NORTHEASTERLY FLOW STRENGTHENS  
BEHIND IT.  
 
WINDS ARE EXPECTED REMAIN BELOW SCA LEVELS THROUGH THE EXTENDED.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...CJL  
NEAR TERM...MM/CJL  
SHORT TERM...CJL  
LONG TERM...SMZ  
AVIATION...MM/SMZ/CJL  
MARINE...MM/SMZ/CJL  
 
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