952  
FXUS61 KLWX 250127  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
927 PM EDT FRI SEP 24 2021  
   
SYNOPSIS
 
 
DRY AND COOLER THROUGH SATURDAY WITH HIGH PRESSURE OVERHEAD. WEAK  
COLD FRONT MOVES THROUGH BY SATURDAY NIGHT. HIGH PRESSURE RETURNS  
SUNDAY AND MONDAY FROM THE SE BEFORE THE NEXT COLD FRONT PASSES  
THROUGH BY THE MIDDLE PORTION OF THE WORK WEEK.  
 

 
   
NEAR TERM /THROUGH SATURDAY/
 
 
SOME PATCHY FOG IS POSSIBLE IN THE VALLEYS TONIGHT. OTHERWISE,  
DRY AND FALL-LIKE TEMPERATURES EXPECTED THROUGH THE PERIOD.  
OVERNIGHT LOWS WILL BE IN THE 40S AND 50S WITH LIGHT VARIABLE  
WINDS.  
 
HIGH PRESSURE WILL BUILD INTO THE REGION SATURDAY TO KEEP THE  
DRY AND SEASONABLE CONDITIONS GOING THROUGH THE AFTERNOON.  
 

 
   
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
 
 
AN UPPER LEVEL TROUGH WILL APPROACH THE AREA BY SATURDAY NIGHT,  
LEAVING THE AREA OF HIGH PRESSURE TO BRIEFLY WEAKEN. A MOISTURE  
STARVED COLD FRONT WILL APPROACH FROM THE WEST AND MAY BRING  
SOME SHOWERS ALONG AND WEST OF THE ALLEGHENY FRONT BUT STILL NOT  
EXPECTED TO PRODUCE MUCH RAIN TO THE EAST AS WESTERLY  
DOWNSLOPING CONTINUES AND KEEPS AN ALREADY MOISTURE-RIDDEN FRONT  
FROM PROGRESSING FURTHER EASTWARD IN TERMS OF PRECIP.  
NONETHELESS, WILL KEEP SOME LOW END POPS FOR AREAS JUST BEYOND  
THE ALLEGHENIES FOR THE CHANCE FOR AN ISOLATED SHOWER DURING THE  
TIME PERIOD.  
 
AS THE FRONT PASSES, EXPECT WINDS TO INCREASE ACROSS A LARGE PORTION  
OF THE AREA ON SUNDAY. HIGH PRESSURE RETURNS FROM THE SE AND WILL  
ALLOW FOR CONDITIONS TO RETURN TO MOSTLY CLEAR FOR THE  
REMAINDER OF THE PERIOD WITH LIGHT WINDS AS HIGH PRESSURE MOVES  
CLOSER OVERHEAD.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
BY MONDAY MORNING, IT APPEARS A DEEP UPPER-LEVEL LOW WILL BE  
DIGGING TOWARD THE COAST OF BRITISH COLUMBIA, CANADA. THIS WILL  
CAUSE AN AMPLIFICATION OF RIDGING OVER THE NORTH-CENTRAL CONUS.  
MEANWHILE, A WEAKER UPPER- LEVEL LOW LOOKS LIKE IT WILL GET  
CAUGHT BENEATH THE RIDGE OVER THE FOUR CORNERS REGION, WHILE  
ANOTHER UPPER-LEVEL LOW SPINS OVER SOUTHEASTERN CANADA - ITS  
EASTWARD PROGRESS HALTED BY ANOTHER AMPLIFYING RIDGE/TROUGH  
COUPLET DOWNSTREAM NEAR THE DAVIS STRAIT/ICELAND, RESPECTIVELY.  
 
AS THE PATTERN AMPLIFIES NEXT WEEK, MODEL GUIDANCE BEGINS TO  
STRUGGLE WITH THE EVOLUTION OF THE LOW OVER SOUTHEASTERN CANADA. THE  
SHARP AMPLIFICATION AMID PERSISTENT RIDGING NEAR THE WEST-CENTRAL  
ATLANTIC OCEAN MAY CAUSE THE LOW TO SPLIT, WITH A PIECE OF IT  
RETROGRADING BACK DOWN THE EAST COAST BY THE SECOND HALF OF NEXT  
WEEK. BEFORE THAT HAPPENS, A SURFACE COLD FRONT AHEAD OF THE UPPER-  
LEVEL TROUGH/LOW SHOULD PROGRESS SOUTHWARD THROUGH THE AREA AROUND  
TUESDAY. DEPENDING ON THE STRENGTH OF THE FRONT AND HOW MUCH  
MOISTURE IS PRESENT ALONG AND AHEAD OF IT, SHOWERS OR EVEN A FEW  
THUNDERSTORMS MAY RESULT. SHEAR WILL INCREASE AS WELL, SO THERE  
COULD BE A CONDITIONAL SEVERE WEATHER (DAMAGING WIND) RISK IF ANY  
APPRECIABLE INSTABILITY DEVELOPS ALONG AND AHEAD OF THE FRONT.  
 
GENERAL ONSHORE FLOW LOOKS LIKELY THE SECOND HALF OF THE WEEK, BUT  
HOW STRONG REMAINS IN QUESTION. THE WEATHER WILL DEPEND VERY HIGHLY  
ON WHAT HAPPENS WITH THE AFOREMENTIONED RETROGRADING LOW, A SCENARIO  
RIDDLED WITH VERY HIGH UNCERTAINTY AT THIS TIME RANGE.  
 

 
   
AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
 
 
SOME PATCHY FOG POSSIBLE TONIGHT BUT GUIDANCE REMAINS MAINLY  
UNSUPPORTIVE OF THIS OCCURRING ACROSS THE WESTERN TERMINALS  
(CHO/MRB).  
 
VFR CONDITIONS CONTINUE THROUGH SUNDAY WITH ONLY A FEW SHOWERS  
POSSIBLE SATURDAY NIGHT WITH MRB BEING THE ONLY LIKELY CANDIDATE FOR  
ANY PRECIP TO MAKE IT IN THE TERMINALS. WITH THIS WEAK FRONTAL  
PASSAGE, WINDS WILL SHIFT FROM OUT OF THE SSW TO W SATURDAY NIGHT  
WITH POTENTIAL FOR SOME GUSTS REACHING 15-20 KNOTS DURING THE  
EVENING AND OVERNIGHT HOURS INTO SUNDAY.  
 
PREVAILING VFR CONDITIONS ARE EXPECTED MONDAY INTO TUESDAY, THOUGH  
SOME PATCHY EARLY MORNING FOG CAN'T BE RULED OUT. THERE IS A CHANCE  
FOR SHOWERS OR A FEW THUNDERSTORMS ON TUESDAY ALONG AND AHEAD OF AN  
APPROACHING COLD FRONT. THE WIND SHOULD BE GENERALLY SOUTHWESTERLY  
MONDAY INTO TUESDAY BEFORE BECOMING NORTHWESTERLY BEHIND THE FRONT.  
 

 
   
MARINE
 
 
AS AN AREA OF HIGH PRESSURE BUILDS OVERHEAD, WINDS WILL CALM  
TONIGHT. WEAK COLD FRONT APPROACHES FROM THE WEST AND WILL  
INCREASE WINDS FOR SATURDAY NIGHT INTO SUNDAY, YIELDING AT LEAST  
A SCA. IF GUIDANCE CONTINUES TO TREND UPWARD, GALES MAY BE  
POSSIBLE FOR THE LOWER PART OF THE WATERS.  
 
GUSTINESS MAY INCREASE A BIT OUT OF THE SOUTHWEST MONDAY AFTERNOON  
INTO TUESDAY AHEAD OF AN APPROACHING FRONT, AND AGAIN BEHIND SAID  
FRONT TUESDAY NIGHT. SMALL CRAFT ADVISORIES MAY BE NEEDED AT  
TIMES.  
 

 
   
TIDES/COASTAL FLOODING
 
 
ANOMALIES WILL REMAIN NEAR ONE FOOT NEAR THE MOUTH OF THE BAY.  
AS NORTHWESTERLY FLOW BECOMES LIGHTER THROUGH TONIGHT, SOME OR  
ALL OF THIS EXCESS WATER WILL RETURN NORTHWARD. THE INCREASE IN  
WATER LEVELS WILL RE-INTRODUCE A THREAT FOR MINOR TIDAL  
FLOODING, ESPECIALLY AT MORE SENSITIVE SITES LIKE ANNAPOLIS,  
STRAITS POINT, AND DC SW WATERFRONT.  
 

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

 
 

 
SYNOPSIS...ADM  
NEAR TERM...KLW/ADM  
SHORT TERM...ADM  
LONG TERM...DHOF  
AVIATION...KLW/DHOF  
MARINE...KLW/DHOF  
TIDES/COASTAL FLOODING...KLW  
 
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