009  
FXUS61 KLWX 231900  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
200 PM EST FRI FEB 23 2018  
   
SYNOPSIS
 
 
A WARM FRONT WILL GRADUALLY PUSH NORTH ACROSS THE REGION  
TONIGHT THROUGH SUNDAY MORNING. A COLD FRONT WILL THEN CROSS THE  
REGION SUNDAY NIGHT. HIGH PRESSURE WILL RETURN EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH SATURDAY/
 
 
LATEST SURFACE ANALYSIS PLACES LOW PRESSURE NEAR LAKE SUPERIOR,  
HIG PRESSURE NEAR NOVA SCOTIA, AND ANOTHER HIGH PRESSURE BETWEN  
THE CAROLINAS AND BERMUDA. A WARM FRONT EXTENDS BETWEEN THE TWO  
HIGH PRESSURES, WESTWARD ACROSS NORTH CAROLINA, THEN NORTHWARD  
ALONG THE APPALACHIANS TO THE VICINITY OF PITTSBURGH. THERE IT  
TURNS WEST AND MEETS THE COLD FRONT EXTENDING SOUTHWARD FROM THE  
LOW IN THE GREAT LAKES. THE COLD FRONT THEN CONTINUES SOUTHWEST  
TOWARD MEMPHIS AND FINALLY APPROACHES HOUSTON.  
 
TONIGHT THROUGH SATURDAY, THE LOW PRESSURE WILL HEAD EASTWARD TO  
OUR NORTH. SOUTHERLY FLOW WILL ENCOURAGE THE WARM FRONT TO PUSH  
NORTHWARD AS WELL, BUT THE ODDS IT REACHES VERY FAR INTO OUR CWA  
ARE NOT HIGH. THE MORE PESSIMISTIC BUT OFTEN MORE REALISTIC (IN  
THESE SITUATIONS, AT LEAST) NAM SHOWS THE WARM FRONT REACHING  
PORTIONS OF THE WEST VIRGINIA EASTERN PANHANDLE AND THE  
SHENANDOAH VALLEY, BUT STRUGGLING TO REACH ANY PORTION OF THE  
CWA EAST OF THE BLUE RIDGE. THERE MAY BE AN ATTEMPT AT A LITTLE  
CLEARING THIS EVENING AS THIS ALL TRIES TO OCCUR, BUT OTHERWISE,  
CLOUDS AND DRIZZLE WITH PATCHY MIST/FOG WILL LIKELY CONTINUE.  
WITH THE MAIN FORCING STAYING TO OUR NORTH, SIGNIFICANT RAINFALL  
IS NOT EXPECTED ACROSS OUR REGION, BUT A FEW SHOWERS COULD SKIM  
THE REGION, PARTICULARLY WESTERN MARYLAND. TEMPERATURES WILL BE  
FAIRLY STEADY, PERHAPS EVEN RISING A BIT, BUT LARGE CHANGES ARE  
NOT EXPECTED IN MOST OF THE REGION.  
 
ON SATURDAY, THE FRONT MAY ACTUALLY SINK BACK SOUTH A BIT AS THE  
PASSAGE OF THE LOW TO OUR NORTH CAUSES THE FLOW TO SHIFT A BIT  
MORE NORTHERLY. THUS, THE MORNING SHOULD BE MORE OF THE  
SAME...DAMP AND DREARY, BUT NOT A WASHOUT. LATER IN THE MORNING  
AND IN THE AFTERNOON, LOW PRESSURE DEVELOPING TO THE WEST OVER  
THE PLAINS WILL BRING INCREASED WARM ADVECTION ALOFT AND FGEN  
ACROSS WESTERN ZONES, SPREADING EASTWARD LATE IN THE DAY. THIS  
WILL INCREASE THE RISK OF STEADIER RAIN. GIVEN AMPLE MOISTURE  
AVAILABLE, SOME LOCALLY HEAVY RAIN COULD OCCUR IN THE WESTERN  
PORTIONS OF THE FORECAST AREA, BUT CONFIDENCE IS LOW REGARDING  
ANY FLOODING RISK, SO HAVE NOT ISSUED ANY FLOOD WATCHES YET.  
HIGHS ON SATURDAY WILL BE A BIT WARMER THAN TODAY AS THE WARM  
FRONT ONCE AGAIN ATTEMPTS TO LIFT NORTH, WITH 50S AND 60S  
BECOMING MORE COMMON. HOWEVER, IF THE FRONT ENDS UP FURTHER  
SOUTH THAN CURRENTLY EXPECTED, IT COULD STAY COOLER.  
 

 
   
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
 
 
WARM FRONT MAKES MORE PROGRESS NORTHWARD ON SATURDAY NIGHT AND  
SUNDAY AS LOW PRESSURE WAVE PUSHES NORTHEASTWARD TO OUR  
NORTHWEST. THIS SHOULD ALLOW TEMPERATURES TO WARM MORE  
SIGNIFICANTLY AFTER THE RAIN SATURDAY NIGHT, WITH 70S LOOKING  
MORE LIKELY ON SUNDAY. AN INTERVAL OF RELATIVELY PLEASANT  
WEATHER MAY OCCUR LATE MORNING INTO EARLY AFTERNOON, WITH MORE  
SUNSHINE, BUT THEN THE COLD FRONT WILL APPROACH FROM THE  
NORTHWEST. STILL SOME UNCERTAINTY ON ANY SEVERE THREAT, BUT  
CERTAINLY WITH THE AVAILABLE MOISTURE AND WARMTH, SOME  
INSTABILITY WILL BE PRESENT, SO ALLOWED SLIGHT CHANCE OF  
THUNDER INTO THE FORECAST SUNDAY AFTERNOON. THE FRONT WILL SLIDE  
SOUTHEAST ACROSS THE REGION SUNDAY NIGHT, SO A DRYING, COOLING  
TREND WILL DEVELOP. HOWEVER, THE FRONT WILL SLOW DOWN OVERNIGHT  
AS YET ANOTHER WAVE OF LOW PRESSURE DEVELOPS TO OUR SOUTHWEST,  
SO RAIN CHANCES WILL NOT COMPLETELY END IN SOUTHERN PARTS OF THE  
REGION.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
WITH EXCEPTION TO A COUPLE OF LINGERING RAIN SHOWERS NEAR  
SOUTHERN MARYLAND AND PARTS OF THE CENTRAL CHESAPEAKE BAY MONDAY  
MORNING, CONDITIONS WILL DRY OUT AS A RIDGE OF HIGH PRESSURE  
BUILDS IN FROM THE WEST. THE HIGH WILL PERSIST THROUGH TUESDAY  
NIGHT BEFORE MOVING OFFSHORE EARLY WEDNESDAY.  
 
INTERACTION BETWEEN THE HIGH PRESSURE AND A DEVELOPING LOW  
PRESSURE SYSTEM OVER THE CENTRAL GREAT PLAINS WILL PROVIDE A  
SOUTHERLY RETURN FLOW INTO OUR REGION. EXPECT MILDER AND MORE  
MOIST AIR TO RETURN WEDNESDAY AND WEDNESDAY NIGHT. THERE COULD  
BE A COUPLE OF RAIN SHOWERS DEVELOP OVER THE APPALACHIANS AND IN  
PARTS OF THE CENTRAL SHENANDOAH VALLEY LATER IN THE DAY  
WEDNESDAY.  
 
A DEVELOPING WARM FRONT OVER SOUTHWEST VIRGINIA AND WESTERN  
NORTH CAROLINA WILL WORK ITS WAY NORTH ACROSS OUR REGION  
WEDNESDAY NIGHT. AHEAD OF AND ALONG THIS WARM FRONT, ADDITIONAL  
RAIN SHOWERS WILL DEVELOP AND SPREAD NORTHEASTWARD ACROSS OUR  
REGION WEDNESDAY NIGHT. EVEN MORE WARMER AND MOIST AIR IS  
EXPECTED TO FOLLOW THE WARM FRONT NORTHWARD WEDNESDAY NIGHT INTO  
THURSDAY.  
 
SHOWERS, SOME MODERATE AT TIMES, SHOULD PERSIST INTO THURSDAY  
MORNING AS THE WARM FRONT MOVES TO THE MASON-DIXON REGION JUST  
AHEAD OF AN APPROACHING COLD FRONT THAT SHOULD PASS THROUGH OUR  
AREA THURSDAY NIGHT. SOME DRIER AND COOLER AIR WILL WORK IN  
BEHIND THE PASSING COLD FRONT; HOWEVER, MODELS ARE TRYING TO  
PUSH A CUT-OFF LOW PRESSURE SYSTEM OVER THE GREAT LAKES REGION  
EASTWARD. THIS CUT-OFF LOW, IT'S UPPER LEVEL ENERGY SUPPORT, AND  
A LITTLE DAYTIME HEATING COULD SPAWN ADDITIONAL RAIN SHOWERS  
LATER THURSDAY NIGHT AND DURING THE DAY FRIDAY. NORTHWESTERLY  
WINDS COULD BECOME QUITE GUSTY AS WELL IN THE WAKE OF THE  
PASSING SURFACE COLD FRONT AND AHEAD OF THE CUT- OFF LOW  
PRESSURE SYSTEM.  
 
OVERALL, TEMPERATURES THROUGHOUT NEXT WEEK WILL BE MILD WITH  
HIGHS APPROACHING 60 DEGREES OR HIGHER IN ANY WARM SECTOR.  
FRIDAY MAY BE THE EXCEPTION AND COULD BE COOLER, BUT FOR NOW WE  
WILL KEEP TEMPERATURES NEAR NORMAL.  
 

 
   
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
 
 
CHANGEABLE CONDITIONS EXPECTED THROUGH THE NEXT 48-60 HOURS AS A  
WARM FRONT REMAINS STALLED TO OUR SOUTH MUCH OF THE TIME,  
RESULTING PERIODS OF LOW CLOUDS, FOG, MIST AND DRIZZLE. GUIDANCE  
SUGGESTS A BREAK IN THE LOW CLOUDS COULD DEVELOP LATE THIS  
AFTERNOON AND THIS EVENING, BUT GIVEN THE COLD AIR DAMNING WEDGE  
OVER THE REGION, THIS DOES NOT SEEM LIKELY, SO HAVE KEPT ALL THE  
TAFS AT LEAST MVFR THROUGH THE TAF PERIOD. IF CONDITIONS DO  
RELAX, IT WON'T BE FOR LONG, AS WE WILL LIKELY SEE FOG OR LOW  
CLOUDS REDEVELOP QUICKLY OVERNIGHT. THE WARM FRONT WILL PROBABLY  
STAY SOUTH OF ALL THE TERMINALS, SAVE PERHAPS CHO, DURING THE  
DAY SATURDAY, RESULTING IN MORE OF THE SAME. STEADIER RAIN MAY  
OVERSPREAD THE REGION, ESPECIALLY THE NORTHERN TERMINALS, BY  
SATURDAY NIGHT. CONDITIONS LOOK MORE LIKELY TO IMPROVE FROM DC  
ON SOUTH AND WEST ON SUNDAY AS A WARM FRONT LIFTS NORTHWARD, BUT  
BWI/MTN MAY HAVE TROUBLE BREAKING OUT OF THE LOW CLOUDS AND FOG  
AS THE FRONT MAY STRUGGLE TO PASS THAT AREA. COLD FRONT THEN  
FINALLY DROPS SOUTHEAST ACROSS THE REGION, BRINGING SHOWERS AND  
PERHAPS A THUNDERSTORM SUNDAY AFTERNOON, BUT LIKELY RESULTING  
CONDITIONS FINALLY GOING BACK TO VFR WITH DRIER AIR FILTERING  
SOUTH SUNDAY NIGHT.  
 
VFR CONDITIONS EXPECTED MONDAY THROUGH TUESDAY NIGHT. WINDS  
NORTHWEST 5 KNOTS OR LESS MONDAY AND MONDAY NIGHT. WINDS  
BECOMING SOUTHWEST AROUND 5 KNOTS TUESDAY AND TUESDAY NIGHT.  
 

 
   
MARINE
 
 
WITH WEAK GRADIENT AND A FRONT TO THE SOUTH, EXPECT WINDS TO  
STAY BELOW SMALL CRAFT ADVISORY STRENGTH THROUGH SATURDAY  
EVENING ACROSS ALL WATERS. LATE SATURDAY NIGHT, WARM FRONT  
APPROACHING FROM THE SOUTH MAY FINALLY LIFT NORTH OF THE MIDDLE  
BAY, ALLOWING THE STRONG SOUTHERLY FLOW TO REACH THE SURFACE AND  
BRING GUSTS UP TO SCA LEVELS, BUT FOR NOW AM WAITING TO ISSUE A  
HEADLINE. SCA LOOKS LIKELY ACROSS AT LEAST THE SOUTHERN WATERS  
WE COVER, PERHAPS REACHING UP TO THE NORTHERN BAY AS WELL, AS  
THE WARM FRONT LIFTS NORTH AND GUSTY SOUTH WINDS DEVELOP IN THE  
WARM SECTOR. AS WITH THE RECENT ROUND ON TUESDAY AND WEDNESDAY,  
THIS WILL BE PRIMARILY NEAR-SHORE GUSTS, WITH WEAKER WINDS OVER  
THE OPEN WATERS DUE TO THE CHILLY WATER TEMPERATURES LIMITING  
MIXING. COLD FRONT WILL PUSH SOUTHEAST ACROSS THE WATERS SUNDAY  
NIGHT, BUT AT THIS TIME SCA DOES NOT APPEAR LIKELY WITH THIS  
FRONTAL PASSAGE.  
 
NO MARINE HAZARDS EXPECTED MONDAY THROUGH TUESDAY NIGHT. WINDS  
NORTHWEST 5 TO 10 KNOTS MONDAY AND MONDAY NIGHT. WINDS BECOMING  
SOUTHWEST 5 TO 10 KNOTS TUESDAY AND TUESDAY NIGHT.  
 

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

 
 

 
SYNOPSIS...RCM  
NEAR TERM...RCM  
SHORT TERM...RCM  
LONG TERM...KLW  
AVIATION...RCM/KLW  
MARINE...RCM/KLW  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab VA Page
The Nexlab MD Page
The Nexlab WV Page Main Text Page