106  
FXUS61 KLWX 230156 AAA  
AFDLWX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
856 PM EST FRI FEB 22 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL REMAIN TO OUR NORTH THROUGH TONIGHT WHILE A  
BOUNDARY STALLS OVER THE SOUTHEASTERN CONUS. LOW PRESSURE  
DEVELOPING OVER THE MIDDLE MISSISSIPPI RIVER VALLEY WILL  
STRENGTHEN AS IT MOVES NORTHEASTWARD ACROSS THE GREAT LAKES INTO  
CANADA THIS WEEKEND. HIGH PRESSURE WILL BUILD FROM THE NORTHERN  
GREAT PLAINS TOWARD THE GREAT LAKES AND EVENTUALLY INTO THE  
NORTHEAST THROUGH THE FIRST HALF OF NEXT WEEK. LOW PRESSURE  
DEVELOPING OVER THE TENNESSEE VALLEY COULD APPROACH THE REGION  
DURING THE MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
 
 
LOW PRESSURE WILL BEGIN TO STRENGTHEN OVER THE ROCKIES  
OVERNIGHT AND HIGH PRESSURE WILL REMAIN TO OUR NORTH. THE LOW-  
LEVEL FLOW WILL BEGIN TO TURN TO THE SOUTHWEST AND THIS WILL  
ALLOW FOR OVERRUNNING TO INCREASE. STILL FEEL THAT MOST AREAS  
ACROSS THE CENTRAL AND NORTHERN CWA WILL BE DRY...CLOSER TO THE  
HIGH. HOWEVER, LIGHT RAIN WILL LIKELY SPREAD NORTH INTO THE  
POTOMAC HIGHLANDS AND CENTRAL VIRGINIA TOWARD MORNING. THERE  
WILL BE ENOUGH EVAPORATIVE COOLING FOR A COLD LAYER TO DEVELOP  
BETWEEN ABOUT 2KFT AND 4KFT. THIS WILL CAUSE FREEZING RAIN ALONG  
THE RIDGES. A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE  
POTOMAC/ALLEGHENY HIGHLANDS AND CENTRAL/NORTHERN VIRGINIA BLUE  
RIDGE MOUNTAINS, WHERE CONFIDENCE IS HIGHEST FOR PRECIPITATION  
TO OCCUR IN THAT COLD LAYER. ICE ACCUMULATIONS WILL BE AROUND  
ONE- TENTH OF AN INCH OR LESS. LOWS GENERALLY 28-38F.  
 

 
   
SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/
 
 
LOW PRESSURE WILL INTENSIFY AS IT MOVES THROUGH THE MIDWEST  
SATURDAY. THE LOW AND MID-LEVEL FLOW WILL STRENGTHEN AND TURN  
MORE SOUTH TO SOUTHWESTERLY, CAUSING MORE OVERRUNNING. THIS WILL  
CAUSE RAIN TO OVERSPREAD THE REST OF THE AREA FROM SOUTHWEST TO  
NORTHEAST SATURDAY MORNING INTO SATURDAY AFTERNOON. A MODERATE  
TO PERHAPS EVEN LOCALLY HEAVY RAIN IS EXPECTED ACROSS PORTIONS  
OF THE POTOMAC HIGHLANDS AND CENTRAL VIRGINIA SOUTH OF  
INTERSTATE 64. A FLOOD WATCH IS IN EFFECT FOR THESE AREAS.  
 
ELSEWHERE, RAIN SHOULD BE LIGHT ENOUGH TO PREVENT FLOODING  
SATURDAY INTO SATURDAY EVENING, BUT IT COULD BE CLOSE DURING THE  
EVENING HOURS NEAR THE CHARLOTTESVILLE AREA. THE REASON WHY THE  
STEADIER RAIN WILL BE TO THE SOUTHWEST IS THAT OVERRUNNING WILL  
BE DEEPER FARTHER AWAY FROM THE HIGH.  
 
WILL ALSO HAVE TO WATCH FOR FREEZING RAIN ALONG THE RIDGES AS  
WELL. THE WINTER WEATHER ADVISORY CONTINUES THROUGH SATURDAY  
MORNING FOR THE CENTRAL/NORTHERN BLUE RIDGE INTO THE  
POTOMAC/ALLEGHENY HIGHLANDS. FURTHER EXPANSION MAY BE NEEDED  
INTO WESTERN ALLEGANY COUNTY IN MARYLAND, BUT CONFIDENCE WAS  
NOT HIGH ENOUGH AT THIS TIME DUE TO UNCERTAINTIES WITH THE  
TIMING AND ARRIVAL OF THE STEADIER PRECIPITATION.  
 
LOW PRESSURE WILL MOVE INTO THE GREAT LAKES SATURDAY NIGHT AND  
INTO CANADA SUNDAY. THE WARM FRONT ASSOCIATED WITH THE LOW WILL  
APPROACH SATURDAY NIGHT BEFORE PASSING THROUGH MIDDAY SUNDAY  
AND THE COLD FRONT ASSOCIATED WITH THE LOW WILL PASS THROUGH  
SUNDAY AFTERNOON.  
 
FOR SATURDAY NIGHT INTO EARLY SUNDAY, A SOAKING RAIN IS EXPECTED  
ACROSS MOST AREAS DUE TO INCREASED OVERRUNNING AND FORCING FROM  
A STRENGTHENING LOW-LEVEL JET. COPIOUS AMOUNTS OF MOISTURE  
REMAIN IN PLACE. RAINFALL AMOUNTS AROUND 0.75 TO 1.50" ARE MOST  
LIKELY, WITH LOCALLY 2-3" POSSIBLE. THE HIGHEST AMOUNTS FOR THE  
ENTIRE EVENT (TONIGHT THROUGH SUNDAY MORNING) ARE MOST LIKELY  
ACROSS THE CENTRAL SHENANDOAH VALLEY INTO THE POTOMAC HIGHLANDS.  
HAVING THAT BEEN SAID, RECENT SNOW MELT HAS CAUSED SATURATED  
SOILS AND FLOOD GUIDANCE IS LOW DUE TO THAT. THEREFORE, FLOODING  
OF SMALL STREAMS AND CREEKS AS WELL AS LOW LYING URBAN AREAS IF  
POSSIBLE ACROSS THE ENTIRE AREA SATURDAY NIGHT INTO SUNDAY.  
CONFIDENCE WAS NOT HIGH ENOUGH FOR A WATCH AT THIS TIME DUE TO  
THE LATER START TIME OF THE STEADIER PRECIPITATION AND THE FACT  
THAT IT MAY BE SEPARATED FURTHER FROM WHEN MOST OF THE SNOW  
MELTING HAS OCCURRED (THURSDAY INTO FRIDAY OF THIS WEEK). WILL  
HAVE TO REASSESS ON LATER SHIFTS.  
 
DRIER CONDITIONS WILL OVERSPREAD THE AREA FROM WEST TO EAST  
SUNDAY MORNING AND LOW PRESSURE WILL INTENSIFY AS IT MOVES INTO  
SOUTHERN CANADA. A STRONG GRADIENT BETWEEN THE LOW AND HIGH  
PRESSURE OVER THE CENTRAL CONUS WILL CAUSE WINDY CONDITIONS  
BEHIND THE COLD FRONT LATER SUNDAY MORNING INTO THE POTOMAC  
HIGHLANDS AND SUNDAY AFTERNOON ELSEWHERE. THE WINDY CONDITIONS  
WILL PERSIST THROUGH SUNDAY NIGHT. A HIGH WIND WATCH IS IN  
EFFECT, MAINLY FOR THE RIDGES OF ALLEGHENY AND POTOMAC HIGHLANDS  
AS WELL AS THE BLUE RIDGE MOUNTAINS. WIND GUSTS AROUND 60 MPH  
ARE POSSIBLE. ELSEWHERE, WIND GUSTS OF 35 TO 55 MPH ARE MOST  
LIKELY, ESPECIALLY ACROSS NORTHERN AND CENTRAL AREAS (INCLUDING  
THE WASHINGTON AND BALTIMORE METRO AREAS). WILL CONTINUE TO  
MONITOR FOR THE POTENTIAL OF WIND ADVISORIES AND/OR HIGH WIND  
WARNINGS.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
STRONG CANADIAN HIGH PRESSURE WILL BE BUILDING SOUTHWARD INTO THE  
CENTRAL U.S. ON MONDAY, AS LOW PRESSURE LIFTS AWAY FROM NEW  
ENGLAND TO THE NORTHEAST. THIS WILL MAINTAIN A TIGHT PRESSURE  
GRADIENT ACROSS THE MID ATLANTIC STATES, SO CONTINUED WINDY  
CONDITIONS CAN BE EXPECTED. DRY CONDITIONS, NEAR NORMAL  
TEMPERATURES AND MOSTLY CLEAR SKIES ARE LIKELY INTO MID WEEK AS  
HIGH PRESSURE BUILDS OVER THE REGION. GFS HINTING AT THE  
POTENTIAL FOR A WEAK AREA OF LOW PRESSURE PASSING TO OUR NORTH  
ON WEDNESDAY, ALTHOUGH MOSTLY DRY CONDITIONS LOOK TO PERSIST,  
OUTSIDE OF SOME UPSLOPE SHOWERS. HIGH PRESSURE LOOKS TO BUILD  
BACK OVER THE REGION THROUGH THURSDAY, WITH CONTINUED DRY  
CONDITIONS. WE WILL KEEP TEMPERATURES RUNNING NEAR NORMAL FOR  
LATE FEBRUARY GIVEN DIFFERING SOLUTIONS BETWEEN DETERMINISTIC  
AND ENSEMBLE GUIDANCE AT THIS TIME.  
 

 
   
AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
 
 
VFR CONDITIONS ARE EXPECTED THROUGH TONIGHT AT ALL TERMINALS.  
CHANCES THEN BEGIN TO INCREASE FOR MVFR AT CHO SATURDAY MORNING.  
 
LOW CLOUDS AND RAIN WILL THEN OVERSPREAD THE TERMINALS SATURDAY  
AFTERNOON INTO SATURDAY NIGHT, AND LAST INTO SUNDAY MORNING WITH  
IFR CONDITIONS LIKELY AND SUBIFR CONDITIONS POSSIBLE. A COLD  
FRONT WILL PASS THROUGH THE TERMINALS SUNDAY, AND STRONG WINDS  
ARE POSSIBLE BEHIND THE COLD FRONT LATER SUNDAY AFTERNOON AND  
SUNDAY NIGHT.  
 
VFR CONDITIONS EXPECTED MONDAY AND TUESDAY AS HIGH PRESSURE  
BUILDS TO OUR WEST. THE GRADIENT WILL REMAIN TIGHT ON MONDAY  
WITH THE EXITING LOW OFF OF NEW ENGLAND AND THE BUILDING HIGH,  
SO STRONG GUSTY NORTHWEST WINDS CAN BE EXPECTED. THE GRADIENT  
WILL WEAKEN MONDAY NIGHT, WITH LIGHT NORTHERLY WINDS FORECAST  
THROUGH TUESDAY.  
 

 
   
MARINE
 
 
HIGH PRESSURE WILL BUILD TO THE NORTH THROUGH SATURDAY AND WINDS  
SHOULD REMAIN BELOW SCA CRITERIA. LOW PRESSURE WILL PASS BY TO  
THE WEST SATURDAY NIGHT INTO SUNDAY AND THE COLD FRONT  
ASSOCIATED WITH THE LOW WILL PASS THROUGH LATER SUNDAY  
AFTERNOON. WINDS MAY APPROACH SCA CRITERIA SATURDAY NIGHT, BUT  
CONFIDENCE IS TOO LOW FOR A HEADLINE AT THIS TIME.  
 
STRONGER WINDS ARE EXPECTED SUNDAY, ESPECIALLY SUNDAY AFTERNOON  
THROUGH SUNDAY NIGHT BEHIND THE COLD FRONT. A GALE WARNING WILL  
LIKELY BE NEEDED FOR THE WATERS DURING THIS TIME.  
 
GALE CONDITIONS LIKELY ON MONDAY AS THE GRADIENT REMAINS QUITE  
STRONG BETWEEN AN EXISTING LOW OFF OF NEW ENGLAND AND HIGH  
PRESSURE BUILDING INTO THE CENTRAL U.S. SCA CONDITIONS LIKELY  
PERSIST INTO MONDAY NIGHT BEFORE DROPPING BELOW CRITERIA TUESDAY  
AND TUESDAY NIGHT AS HIGH PRESSURE BUILDS TOWARD THE REGION.  
 

 
   
HYDROLOGY
 
 
GIVEN RECENT SNOWMELT AND SATURATED GROUND, 0.75" TO AROUND 1.5"  
OF RAIN MAY BE ENOUGH TO RESULT IN MINOR FLOODING ISSUES THIS  
WEEKEND, PARTICULARLY OVER EASTERN WEST VIRGINIA. THE OVERALL  
TREND HAS BEEN FOR SLIGHTLY LESS RAIN, BUT NOT SO MUCH LESS TO  
COMPLETELY AVOID A FLOOD THREAT. DESPITE THE SLIGHTLY LOWER QPF  
TOTALS IN THE 12Z MODEL SUITE, MMEFS STILL INDICATES >50%  
CHANCE OF MINOR FLOOD AT SEVERAL RIVER FORECAST POINTS LATER  
THIS WEEKEND.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...HIGH WIND WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR  
MDZ501.  
HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING  
FOR MDZ003-004-502.  
VA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY  
NIGHT FOR VAZ025-036-037-503-504-508.  
WINTER WEATHER ADVISORY FROM 3 AM TO NOON EST SATURDAY FOR  
VAZ503-504-508.  
HIGH WIND WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR  
VAZ503-504-507-508.  
WINTER WEATHER ADVISORY FROM 7 AM TO NOON EST SATURDAY FOR  
VAZ507.  
WV...WINTER WEATHER ADVISORY FROM 3 AM TO NOON EST SATURDAY FOR  
WVZ505-506.  
HIGH WIND WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR  
WVZ501>503-505-506.  
HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING  
FOR WVZ050>052-055-504.  
WINTER WEATHER ADVISORY FROM 7 AM TO NOON EST SATURDAY FOR  
WVZ501-503.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...BJL  
NEAR TERM...BJL/MM  
SHORT TERM...BJL  
LONG TERM...BKF  
AVIATION...BJL/MM/BKF  
MARINE...BJL/MM/BKF  
HYDROLOGY...BJL  
 
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