223  
FXUS61 KLWX 260122  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
922 PM EDT SUN JUN 25 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD WEST OF THE AREA THROUGH TUESDAY AS A  
SERIES OF WEAK BOUNDARIES CROSS THE REGION. THE HIGH WILL THEN  
CROSS THE REGION WEDNESDAY AND SETTLE OVER THE WESTERN ATLANTIC  
OCEAN LATE IN THE WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
...UPDATE TO ADD SMALL CRAFT ADVISORY FOR TONIGHT ACROSS THE  
MARYLAND CHESAPEAKE BAY NORTH OF DRUM POINT. PREVIOUS DISCUSSION  
FOLLOWS...  
 
SURFACE HIGH PRESSURE WILL REMAIN CENTERED OVER THE MIDWEST  
INTO THE TENNESSEE VALLEY TONIGHT WHILE AN UPPER- LEVEL TROUGH  
REMAINS OVERHEAD. A WEST TO NORTHWEST FLOW WILL ALLOW FOR DRY  
AND COOL CONDITIONS FOR THIS TIME OF YEAR. LEANED TOWARD THE  
COOLER GUIDANCE THINKING THAT THE ATMOSPHERE WILL DECOUPLE...AND  
WITH MAINLY CLEAR SKIES...LIGHT WINDS AND LOW DEWPOINTS THIS  
DOES FAVOR RADIATIONAL COOLING. MIN TEMPS ARE FORECAST TO RANGE  
FROM THE 40S IN THE COLDER VALLEYS OF THE POTOMAC HIGHLANDS AND  
SHENANDOAH VALLEY...TO THE 50S ACROSS MOST OTHER LOCATIONS...TO  
THE MIDDLE 60S IN DOWNTOWN WASHINGTON AND BALTIMORE.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
 
 
ANOTHER WEAK TROUGH/BOUNDARY WILL MOVE NEAR THE REGION MONDAY.  
AGAIN, LITTLE IF ANY SENSIBLE IMPACTS EXPECTED. WILL ONCE AGAIN  
SEE AN INSTABILITY-DRIVEN CUMULUS FIELD DEVELOP. A VERY LOW  
CHANCE OF A SHOWER EXISTS, MAINLY NORTH. THE REGION WILL REMAIN  
IN WESTERLY FLOW WITH GUSTS UP TO ABOUT 20 MPH. HIGHS FROM THE  
MID 70S TO LOW 80S. QUIET WEATHER WILL CONTINUE MONDAY NIGHT,  
WITH LOWS IN THE 50S TO LOW 60S.  
 
THE HIGHEST CHANCES OF ANY PRECIPITATION IN THIS STRETCH WILL  
COME ON TUESDAY AS AN UPPER TROUGH AND ITS SURFACE REFLECTION  
MOVE ACROSS THE AREA. WITH A SMALL AMOUNT OF INSTABILITY DUE TO  
THE ANOMALOUSLY COOL TEMPERATURES ALOFT, THERE WILL LIKELY BE  
SOME ISOLATED- SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS  
AROUND THE AREA. THIS WILL ALSO BE THE COOLEST DAY WITH HIGHS IN  
THE 70S AREA-WIDE. HIGH PRESSURE WILL BUILD IN OVERHEAD, WITH  
LOWS IN THE 50S.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
HIGH PRESSURE WILL BE IN CONTROL WEDNESDAY, BRINGING DRY  
CONDITIONS AND BELOW NORMAL TEMPERATURES, BEFORE SLIDING  
OFFSHORE THURSDAY.  
 
AS HIGH PRESSURE MOVES OVER THE WESTERN ATLANTIC, WARMER  
TEMPERATURES AND INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS  
WILL DEVELOP THURSDAY NIGHT THROUGH SUNDAY. THE BEST CHANCE FOR  
SHOWERS AND STORMS WILL BE SATURDAY AND SUNDAY.  
 

 
   
AVIATION /02Z MONDAY THROUGH FRIDAY/
 
 
VFR EXPECTED THROUGH AT LEAST TUESDAY NIGHT WITH A FAIR WEATHER  
CUMULUS DECK EACH DAY. MAIN CONCERN WILL BE AN ISOLATED  
SHOWERS/THUNDERSTORMS ON TUESDAY. OTHERWISE, WINDS GENERALLY  
WESTERLY WITH GUSTS TO ABOUT 20 KNOTS DURING THE DAYLIGHT HOURS.  
 
VFR CONDITIONS WEDNESDAY THROUGH FRIDAY. WINDS NORTHWEST  
TO START WILL TURN SOUTH/SOUTHWEST BY LATE IN THE WEEK. CHANCES  
FOR SHOWERS/THUNDERSTORMS ARE INTRODUCED BY FRIDAY.  
 

 
   
MARINE
 
 
SMALL CRAFT ADVISORY IS IN EFFECT UNTIL 5 AM FOR THE MARYLAND  
CHESAPEAKE BAY NORTH OF DRUM POINT. AS COOLER AIR MOVES OVER  
THE WARM WATER TEMPERATURES OVERNIGHT, GUSTS UP TO 20 KNOTS ARE  
EXPECTED.  
 
WIND FIELD LOOKS SLIGHTLY LOWER ON MONDAY, BUT GUSTS MAY AGAIN  
APPROACH SCA-CRITERIA MONDAY AFTERNOON. HAVE KEPT FORECAST BELOW  
AT THIS TIME.  
 
WESTERLY FLOW WILL CONTINUE ON TUESDAY WITH MARGINAL SCA  
CONDITIONS POSSIBLE. THERE WILL ALSO BE AN INCREASED CHANCE FOR  
SOME ISOLATED-SCATTERED SHOWERS/THUNDERSTORMS.  
 
NO MARINE HAZARDS EXPECTED WEDNESDAY AND WEDNESDAY NIGHT. WINDS  
SOUTH 5 TO 10 KNOTS. SMALL CRAFT ADVISORIES MAY BE NEEDED THURSDAY  
AND THURSDAY NIGHT. WINDS SOUTHWEST 10 TO 15 KNOTS GUSTS 20  
KNOTS.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT MONDAY FOR ANZ530>533-  
538>541.  
 

 
 

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