693  
FXUS61 KLWX 221827  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
227 PM EDT FRI OCT 22 2021  
   
SYNOPSIS
 
 
A REINFORCING COLD FRONT APPROACHES THE REGION FROM THE  
NORTHWEST TONIGHT BEFORE DISSIPATING. WEAK HIGH PRESSURE RETURNS  
FOR THE WEEKEND, WITH DRY AND SEASONABLE CONDITIONS EXPECTED. THE  
NEXT FRONTAL SYSTEM WILL IMPACT THE AREA DURING EARLY PORTIONS  
OF NEXT WEEK. AN ADDITIONAL SYSTEM MAY FOLLOW LATER IN THE WEEK  
WHICH COULD LEAD TO CONTINUED UNSETTLED CONDITIONS.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS EXPECTED, CLOUD COVER IS ON THE INCREASE AHEAD OF A  
REINFORCING COLD FRONT AND AMIDST ANOTHER WAVE OF SHORTWAVE  
ENERGY THAT IS CURRENTLY OVER THE OHIO VALLEY. THIS IS ROTATING  
AROUND A MORE BROAD UPPER LOW THAT REMAINS STATIONARY OVER THE  
HUDSON BAY IN CANADA. NOT EXPECTING MUCH FROM THIS SYSTEM ASIDE  
FROM SOME MID-LEVEL CLOUDS AND PERHAPS A FEW UPSLOPE SHOWERS  
ALONG/WEST OF THE ALLGHENY FRONT BY THIS EVENING. IN TERMS OF  
TEMPERATURES, STILL ON TRACK FOR MOST AREAS TO REACH MID 60S TO  
LOW 70S FOR AFTERNOON HIGHS, LOCALLY INTO THE MID/UPPER 40S OVER  
HIGHER ELEVATIONS OF THE ALLEGHENY FRONT.  
 
SKIES WILL TURN MOSTLY CLOUDY FOR THE EVENING AND INTO TONIGHT.  
WHILE WINDS DO BECOME LIGHTER AS THE PRESSURE GRADIENT WEAKENS,  
THE THICK CLOUD COVER WILL OFFSET SOME OF THE NOCTURNAL  
COOLING. MOST LOCATIONS WILL STAY IN THE 40S TONIGHT, WITH LOW  
50S MORE COMMONPLACE FROM I-95 EASTWARD. A DRY FORECAST IS IN  
STORE FOR MANY, BUT FAR WESTERN MARYLAND AND THE EASTERN WEST  
VIRGINIA PANHANDLE MAY SEE ADDITIONAL UPSLOPE SHOWERS. THE  
ACTIVITY MAY BECOME SLIGHTLY MORE CONCENTRATED AS A MORE  
PROMINENT SHORTWAVE SWEEPS THROUGH OVERNIGHT.  
 

 
   
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
 
 
A BUILDING SURFACE HIGH PRESSURE OVER THE REGION AND RISING  
HEIGHTS IN THE MID-UPPER LEVELS WILL LEAD TO DRY AND SEASONABLE  
CONDITIONS ON SATURDAY. HIGH TEMPERATURES FOR MOST OF THE AREAS  
WILL BE IN THE MID TO UPPER 60S, WHILE THE MOUNTAINS STICK TO  
THE UPPER 40S TO MID 50S. CLOUDS MAY BE SLOW TO BURN OFF  
TOMORROW, BUT THINK WE SHOULD BE SEEING SOME SUN BY LATE  
MORNING/EARLY AFTERNOON. WEAK HIGH PRESSURE SETTING UP  
OVERHEAD SATURDAY NIGHT WILL AFFORD A BETTER CHANCE FOR DECENT  
RADIATIONAL COOLING EFFECTS. UPPER 30S ARE POSSIBLE OVER HIGHER  
ELEVATIONS OF THE ALLEGHENIES. WINDS SHOULD BE LIGHT, BUT  
TEMPERATURES MAY FALL JUST SHORT OF FROST CONCERNS. MOST OTHER  
SPOTS IN THE REGION WILL DROP INTO THE LOW/MID 40S, LOCALLY NEAR  
50 IN THE DC AND BALTIMORE CITY CENTERS.  
 
BY SUNDAY, WE WILL BE TRACKING A POTENT SHORTWAVE MOVING OUT OF  
THE CENTRAL ROCKIES TOWARDS THE GREAT LAKES BY SUNDAY NIGHT.  
MEANWHILE, THE SURFACE HIGH PUSHES OFFSHORE SUNDAY AS WELL,  
PUSHING A WARM FRONT NORTHWARD THROUGH THE REGION ON SUNDAY.  
TEMPERATURES WILL BE AT LEAST A FEW DEGREES WARMER (LIKELY INTO  
THE 70S) AS SOUTHERLY FLOW DEVELOPS BEHIND THE WARM FRONT. MOST  
WARM ADVECTION PRECIP IS EXPECTED TO STAY TO OUT NORTH BASED ON  
LATEST GUIDANCE. INTERESTINGLY, THE GUIDANCE DOES SHOW A RATHER  
HEALTHY SOUTHWESTERLY LOW-LEVEL JET OVERSPREADING THE I-95  
CORRIDOR DURING THE EVENING AND OVERNIGHT TIMEFRAME. WHILE  
NOCTURNAL INVERSIONS SHOULD SET UP, ANY MORE DEVELOPED SHOWER  
COULD MIX THESE 30 TO 40 KNOT WINDS DOWN TO THE SURFACE.  
NIGHTTIME TEMPERATURES ARE TO STAY IN THE 50S FOR THE MOST PART,  
WITH UPPER 40S CLOSER TO THE PENNSYLVANIA BORDER.  
 

 
   
LONG TERM /MONDAY THROUGH THURSDAY/
 
 
NEXT WEEK LOOKS LIKE IT WILL FEATURE AN ACTIVE STRETCH OF WEATHER,  
WITH TWO SYSTEMS IMPACTING THE AREA OVER THE COURSE OF THE WEEK.  
GUIDANCE IS COMING INTO RELATIVELY GOOD AGREEMENT THAT A SHORTWAVE  
WILL BE SITUATED JUST OFF TO OUR WEST AT THE START OF THE PERIOD ON  
MONDAY MORNING. THIS TROUGH AND ITS ASSOCIATED SURFACE LOW WILL  
TRACK TOWARD THE EAST THROUGH THE DAY, ULTIMATELY IMPACTING OUR  
FORECAST AREA MONDAY AFTERNOON INTO MONDAY NIGHT. A PERIOD OF RAIN  
APPEARS LIKELY ACROSS THE AREA, AND A FEW THUNDERSTORMS CAN'T BE  
COMPLETELY RULED OUT AS WELL, BUT LOW-LEVEL MOISTURE AND RELATED  
INSTABILITY APPEAR TO BE LACKING SOMEWHAT WITH THIS SYSTEM. IF  
INSTABILITY WERE TO BE GREATER THAN CURRENTLY MODELED, THERE COULD  
BE A CONDITIONAL THREAT FOR SOME STRONGER STORMS GIVEN THE  
IMPRESSIVE WIND FIELD, BUT THAT CURRENTLY LOOKS LIKE AN UNLIKELY  
OUTCOME.  
 
THAT SYSTEM WILL PROGRESS OFF TO OUR NORTH AND EAST ON TUESDAY, AND  
BRISK NORTHWESTERLY WINDS WILL FILTER INTO THE AREA IN ITS WAKE.  
UPSLOPE SHOWERS MAY ACCOMPANY THE NORTHWESTERLY WINDS ALONG THE  
ALLEGHENY FRONT, BUT ELSEWHERE THERE SHOULD BE A DRYING TREND OVER  
THE COURSE OF THE DAY. WINDS MAY GUST TO UPWARDS OF 30 MPH.  
WEDNESDAY LOOKS LIKE A QUIET DAY AS A NARROW UPPER LEVEL RIDGE  
BUILDS OVERHEAD BETWEEN THE TWO SYSTEMS OF INTEREST.  
 
THE SECOND SYSTEM OF INTEREST WILL MOVE INTO THE AREA ON THURSDAY.  
WHILE THERE'S STILL A DECENT AMOUNT OF SPREAD WITH RESPECT TO THE  
FINER SCALE DETAILS, THE GENERAL EVOLUTION ON THE SYNOPTIC SCALE IS  
FOR A POTENT MID-UPPER LEVEL TROUGH TO APPROACH FROM THE WEST AS IT  
SIMULTANEOUSLY TAKES ON A NEGATIVE TILT. LOW PRESSURE AT THE SURFACE  
IS EXPECTED TO TRACK INTO THE GREAT LAKES, WITH POTENTIALLY A SECOND  
AREA OF LOW PRESSURE DEVELOPING ALONG THE COAST. WHILE IT IS TOO  
EARLY TO GET INTO THE FINER DETAILS, THIS APPEARS TO BE A VERY  
DYNAMIC SYSTEM THAT COULD POTENTIALLY LEAD TO SOME HIGH IMPACT  
WEATHER. WE'LL CONTINUE TO MONITOR TRENDS WITH THIS SYSTEM OVER THE  
COMING DAYS.  
 

 
   
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
 
 
VFR CONDITIONS ARE EXPECTED ACROSS ALL TERMINALS TODAY THROUGH THIS  
WEEKEND AS DRY AIR PUSHES INTO THE REGION. INITIAL  
NORTHWESTERLY WINDS BEHIND THE COLD FRONT WILL SHIFT TO WESTERLY  
BY SATURDAY BEFORE TURNING SOUTHERLY ON SUNDAY AS A WARM FRONT  
LIFTS NORTHWARD. SOME SHOWERS RETURN TO THE PICTURE BY LATE  
SUNDAY AS WARM ADVECTION PICKS UP. FOR NOW, NOT THINKING THIS  
WILL HAVE MUCH (IF ANY) IMPACT ON THE TERMINALS. THIS UPTICK IN  
SOUTHERLY LOW-LEVEL FLOW MAY ALSO PROMPT SOME LOW-LEVEL WIND  
SHEAR CONCERNS AFTER SUNDOWN ON SUNDAY.  
 
SUB-VFR CONDITIONS APPEAR LIKELY AT TIMES MONDAY AFTERNOON INTO  
MONDAY NIGHT AS AN AREA OF LOW PRESSURE PASSES OVERHEAD. VFR  
CONDITIONS AND GUSTY WINDS APPEAR LIKELY ON TUESDAY.  
 

 
   
MARINE
 
 
NO MARINE HAZARDS ARE EXPECTED THROUGH SUNDAY, AS HIGH PRESSURE  
DOMINATES THE WEATHER PATTERN LEADING TO DRY CONDITIONS AND  
LIGHT WINDS. INITIAL NORTHWESTERLY FLOW BEHIND THE COLD FRONT  
WILL SHIFT TO WESTERLY ON SATURDAY. EVENTUALLY A WARM FRONT  
APPROACHES AND MOVES THROUGH ON SUNDAY WHICH INCREASES LOW-  
LEVEL WINDS. FOR SUNDAY NIGHT, PORTIONS OF THE WATERS MAY  
REQUIRE SCAS, PARTICULARLY OVER WIDER SECTIONS OF THE CHESAPEAKE  
BAY. WITH SHOWERS IN THE PICTURE, GUSTY SHOWERS CANNOT BE RULED  
OUT GIVEN 30 TO 40 KNOTS OF FLOW JUST ABOVE THE SURFACE AT  
925-MB.  
 
SCA CONDITIONS APPEAR POSSIBLE ON MONDAY, AND LIKELY ON TUESDAY  
BEHIND A DEPARTING AREA OF LOW PRESSURE.  
 

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

 
 

 
SYNOPSIS...CJL  
NEAR TERM...CJL  
SHORT TERM...CJL  
LONG TERM...CJL  
AVIATION...CJL/KJP  
MARINE...CJL/KJP  
 
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