008  
FXUS61 KLWX 191906  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
206 PM EST WED FEB 19 2020  
   
SYNOPSIS
 
 
AN AREA OF LOW PRESSURE WILL PASS WELL SOUTH OF THE REGION  
THURSDAY INTO THURSDAY NIGHT. HIGH PRESSURE WILL BUILD OVER THE  
MID-ATLANTIC THROUGH THE WEEKEND. LOW PRESSURE WILL APPROACH  
FROM THE MIDWEST EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
TRANQUIL CONDITIONS ARE EXPECTED THROUGH TONIGHT AS HIGH  
PRESSURE NOSES TOWARD THE REGION FROM THE MID SECTION OF THE  
COUNTRY. NBM/SUPERBLEND HAVE BEEN PERFORMING VERY WELL FOR LOW  
TEMPERATURES OF LATE, SO SAW NO REASON TO STRAY FROM THIS. DID  
TWEAK THE RIDGETOPS DOWN SLIGHTLY AND RAISE THE INNER CITY AREAS  
BY A COUPLE DEGREES PER CLIMO, BUT OVERALL THE BLEND SEEMS FINE.  
 

 
   
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
 
 
THE LAST SEVERAL MODEL CYCLES OF THE EC ENSEMBLE HAVE CONTINUED  
TO NUDGE NORTHWARD WITH THE NORTHERN END OF A PRECIP SHIELD  
ASSOCIATED WITH SOUTHERN STREAM LOW PRESSURE MOVING OFFSHORE OF  
THE CAROLINAS THURSDAY AND THURSDAY NIGHT. THE VAST MAJORITY OF  
THE LATEST 12Z GUIDANCE HAS ALSO FOLLOWED THIS TREND. THEREFORE,  
HAVE PAINTED LIKELY SNOW (OF LIGHT INTENSITY) WITH A DUSTING OF  
ACCUMULATION ACROSS OUR SOUTHERN-MOST ZONES FROM NEAR WAYNESBORO  
VIRGINIA TO FAR SOUTHERN MARYLAND.  
 
THE NAM12 IS THE STRONGEST WITH AN UPPER JET JUST TO OUR NORTH,  
THOUGH ALL MODEL GUIDANCE AGREES THIS JET WILL REACH SPEEDS OF  
AT LEAST 150 KNOTS AT 250 HPA (~35,000 FEET ABOVE GROUND).  
FRONTAL FORCING SHOWS THE POTENTIAL FOR BANDING WITH THIS  
SYSTEM AIDED IN PART BY THIS UPPER JET, THOUGH GIVEN THE  
SURFACE LOW TRACK MOVING SOUTHEAST OF CAPE HATTERAS NORTH  
CAROLINA, MORE APPRECIABLE BANDING SHOULD REMAIN JUST SOUTH OF  
OUR CWA.  
 
A NORTHERN STREAM TROUGH WILL ALSO BE DROPPING SOUTHWARD INTO  
THE REGION DURING THE LATE AFTERNOON AND EVENING HOURS ON  
THURSDAY. THE STRONG UPPER JET AND INCREASING MID LEVEL SPIN  
MAY RESULT IN ENOUGH LIFT TO OVERCOME LOW LEVEL DRY AIR AND  
SQUEEZE OUT MOISTURE MOVING DOWN OFF THE GREAT LAKES TO RESULT  
IN SCATTERED FLURRIES OR A FEW SNOW SHOWERS. ACCUMULATIONS  
OVERALL SHOULD BE LITTLE OR NONE, BUT A FEW SPOTS COULD PICK UP  
A QUICK DUSTING IF A MORE SUBSTANTIAL SNOW SHOWER MOVES OVERHEAD.  
 
HIGH PRESSURE WILL BUILD IN LATER THURSDAY NIGHT INTO FRIDAY  
WITH BLUSTERY NORTHWEST WINDS AND BELOW NORMAL TEMPERATURES.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
HIGH PRESSURE WILL BE IN CONTROL SATURDAY THROUGH SUNDAY. DRY  
CONDITIONS WITH MILD TEMPERATURES AND PLENTY OF SUNSHINE ARE  
EXPECTED BOTH DAYS.  
 
HIGH PRESSURE MOVES OFFSHORE SUNDAY NIGHT TO ALLOW FOR A  
SOUTHERLY RETURN FLOW AHEAD OF A LOW PRESSURE SYSTEM OVER THE  
MIDDLE MISSISSIPPI VALLEY.  
 
MONDAY COULD START OUT DRY WITH MILD TEMPERATURES AS THE  
SOUTHERLY FLOW INCREASES. HOWEVER, BY MIDDAY INTO THE AFTERNOON,  
CLOUDS WILL INCREASE AND RAIN BECOMES LIKELY. RAIN SHOULD STAY  
ON THE LIGHT SIDE OF THINGS.  
 
RAIN CHANCES WILL LINGER MONDAY NIGHT INTO TUESDAY AS AN  
ASSOCIATED COLD FRONT EXTENDING FROM THE LOW PRESSURE SYSTEM  
MOVES ACROSS THE REGION. TEMPERATURES SHOULD BE AVERAGE AT BEST  
WITH THE ADDITIONAL CLOUD COVER AND RAIN SHOWERS.  
 
MODELS ARE INDICATING THAT THE COLD FRONT COULD SLOW ITS  
FORWARD PROGRESS OR PERHAPS STALL TO THE EAST OF OUR REGION.  
THIS COULD SET THE STAGE FOR MORE RAIN SHOWERS AND, IF COLD AIR  
SHOVES INTO OUR REGION QUICKLY, A CHANCE FOR SNOW SHOWERS.  
 

 
   
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
 
 
MAINLY VFR IS EXPECTED THROUGH THE TAF PERIOD. POTENTIAL CAVEATS  
INCLUDE (1) THE NORTHERN END OF LIGHT SNOW APPROACHING CHO AFTER  
21Z THURSDAY, AND (2) A FEW FLURRIES OR SNOW SHOWERS FURTHER  
NORTH ASSOCIATED WITH AN UPPER DISTURBANCE. ANY RESTRICTIONS  
SHOULD BE BRIEF. NORTHWEST FLOW 5-10 KTS EXPECTED. HIGH CLOUDS  
WILL INCREASE LATE TONIGHT, THEN GRADUALLY LOWER AND THICKEN TO  
AROUND 4000-6000 FEET BY THURSDAY AFTERNOON.  
 
VFR EXPECTED UNDER BUILDING HIGH PRESSURE THURSDAY NIGHT INTO  
FRIDAY. N/NW WINDS MAY GUST 20-30 KTS AS THE HIGH BUILDS IN.  
 
VFR CONDITIONS SATURDAY THROUGH SUNDAY NIGHT. WINDS SOUTHWEST 5  
TO 10 KNOTS SATURDAY, BECOMING LIGHT AND VARIABLE SATURDAY  
NIGHT. WINDS SOUTHWEST BECOMING SOUTH AROUND 5 KNOTS SUNDAY AND  
SUNDAY NIGHT.  
 

 
   
MARINE
 
 
NORTHWEST FLOW WILL CONTINUE TO DIMINISH THROUGH TONIGHT, THOUGH  
THERE MAY BE A PERIOD LATE THIS EVENING OF ENHANCED NORTHERLY  
FLOW BEHIND A WEAK SECONDARY FRONT.  
 
A LITTLE LIGHT SNOW OR A FLURRY OR SNOW SHOWER CAN'T BE RULED  
OUT THURSDAY AFTERNOON AND EVENING ASSOCIATED WITH A SURFACE LOW  
PASSING OFFSHORE OF THE CAROLINAS AND AN UPPER DISTURBANCE  
APPROACHING FROM PENNSYLVANIA. THE BEST CHANCE FOR REDUCED  
VISIBILITY IN SNOW WILL BE SOUTH OF DRUM POINT MARYLAND.  
 
WINDS WILL INCREASE AND BECOME MORE NORTHERLY BETWEEN THE  
DEPARTING LOW AND HIGH PRESSURE BUILDING IN FROM THE MIDWEST.  
GUSTS OF 20 TO 30 KNOTS ARE LIKELY LATE THURSDAY NIGHT INTO  
FRIDAY AS A RESULT, BEFORE WINDS BECOME LIGHTER FRIDAY NIGHT AS  
HIGH PRESSURE NEARS AND THE GRADIENT RELAXES.  
 
NO MARINE HAZARDS EXPECTED SATURDAY THROUGH SUNDAY NIGHT. WINDS  
SOUTHWEST 10 KNOTS SATURDAY, BECOMING 5 TO 10 KNOTS SATURDAY  
NIGHT AND SUNDAY. WINDS SOUTH AROUND 10 KNOTS SUNDAY NIGHT.  
 

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

 
 

 
SYNOPSIS...DHOF  
NEAR TERM...DHOF  
SHORT TERM...DHOF  
LONG TERM...KLW  
AVIATION...KLW/DHOF  
MARINE...KLW/DHOF  
 
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