551  
FXUS61 KRNK 211142  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
742 AM EDT MON OCT 21 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BRIEFLY PROVIDE FAIR WEATHER ACROSS THE MID-  
ATLANTIC STATES TODAY BEFORE A STRONG COLD FRONT CROSSES THE  
AREA TUESDAY ASSOCIATED WITH SHOWERS. THE MIDDLE OF THE WEEK IS  
EXPECTED TO BE DRY AS HIGH PRESSURE MOVES OVERHEAD. MORE RAIN  
IS FORECAST TOWARD THE END OF THE WEEK AS LOW PRESSURE DEVELOPS  
OVER THE SOUTHEASTERN US.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 400 AM EDT MONDAY...  
 
A MISTY MONDAY MORNING AS COMBINATION OF MOIST GROUND FROM THE  
WEEKEND RAINFALL AND LITTLE TO NO AIR MOVEMENT IS CONTRIBUTING  
TO HIGH HUMIDITY, PATCHY STRATUS AND FOG. DEWPOINTS REMAIN  
ELEVATED SO THERE IS QUITE A BIT OF DAMPNESS IN THE AIR.  
 
FOR TODAY, THE FORECAST AREA WILL RESIDE UNDERNEATH A WEAK AREA  
OF HIGH PRESSURE EAST OF THE APPALACHIANS. THIS AIRMASS IS STILL  
VERY MOIST IN THE BOUNDARY LAYER, SO ANY LIFT FROM DAYTIME  
HEATING WILL RESULT IN AREAS OF LOW LEVEL CLOUD COVER. A FRONT  
OVER THE MID-SECTION OF THE COUNTRY WILL BE ENTERING THE OH/TN  
VALLEYS. SOUTHERLY FLOW AHEAD OF THIS FEATURE WILL BEGIN TO TURN  
OUR WINDS AROUND TO THE SOUTHEAST...A FLOW PATTERN THAT SUPPORTS  
INCREASING UPSLOPE CLOUDS ALONG THE SPINE OF THE BLUE RIDGE.  
UPPER LEVEL MOISTURE WILL ALSO BE ON THE INCREASE, SO THE  
EXPECTATION IS FOR MULTIPLE CLOUD LAYERS AS WE TRANSITION  
THROUGH THE DAY. ANY PRECIPITATION (DURING THE DAY) SHOULD  
REMAIN CONFINED TO THE SOUTHWESTERN CWA INTO THE NC HIGH COUNTRY  
WHERE THE LIFT FROM THE INCREASING SOUTHEAST WIND FLOW WILL  
PROMOTE THICKENING LOW LEVEL CLOUDS AND THE POTENTIAL FOR LIGHT  
RAIN OR DRIZZLE. FOG/STRATUS WILL ALSO BECOME MORE PREVALENT  
ALONG THE BLUE RIDGE WITH POTENTIAL FOR VISIBILITY RESTRICTIONS  
TO LINGER THROUGHOUT THE DAY NEAR FANCY GAP AND INTO THE NC  
MOUNTAINS.  
 
IN SPITE OF THE MOIST ENVIRONMENT, THE TEMPERATURES SHOULD  
REBOUND INTO THE 60S. ANY SUN, AND WE COULD EASILY TEST 70. THE  
PIEDMONT MAY ACTUALLY GET INTO THE LOWER 70S WHERE THERE SHOULD  
BE SUNNY BREAKS TODAY.  
 
FOR TONIGHT, THE COLD FRONT WILL DRAW CLOSER. THIS FRONT IS  
EXPECTED TO BE RATHER AGRESSIVE WITH CONVERGENCE RESULTING IN A  
QUASI LINEAR BAND OF DEEP CONVECTION ALONG OUR JUST AHEAD OF  
THE FRONT. THIS QLCS IS EXPECTED TO RACE EAST, POTENTIALLY  
REACHING OUR WESTERN CWA TOWARD DAYBREAK TUESDAY. THIS LATE  
NIGHT-EARLY MORNING TIMING SUGGEST THIS FEATURE WILL BE IN A  
MUCH WEAKENED STATE, SO NOT ANTICIPATING ANY SEVERE WEATHER.  
THAT SAID, THERE SHOULD STILL BE A GRADIENT WIND AHEAD OF THE  
BOUNDARY, WHICH COULD MIX DOWN TO RIDGE TOP LEVEL DURING THE  
OVERNIGHT. WINDS AHEAD OF THE FRONT ARE FORECAST FROM THE SSE,  
WHICH IS FAVORABLE FOR DOWNSLOPE GUSTS ON THE WEST SIDE OF THE  
APPALACHIANS. ATTM THINK GUSTS OF 25-35 MPH ARE POSSIBLE FOR  
WESTERN GRAYSON, SMYTH, TAZEWELL AND INTO WESTERN MERCER...JUST  
UNDER ADVISORY CRITERIA (THRESHOLD IS 45 MPH).  
 
TEMPERATURES THROUGH THE OVERNIGHT ARE EXPECTED TO REMAIN MILD  
WITH INCREASING WARM AIR ADVECTION AHEAD OF THE FRONT...LOWS IN  
THE 50S. RAIN CHANCES WILL GRADUALLY INCREASE, THE BULK OF THE  
MOISTURE HOLDING OFF UNTIL EARLY TUESDAY WHEN THE FRONT ACTUALLY  
CROSSES THE FORECAST AREA.  
 

 
   
SHORT TERM /TUESDAY THROUGH THURSDAY/
 
 
AS OF 300 AM EDT MONDAY...  
 
A POTENT COLD FRONT SHOULD MOVE OVERHEAD FROM WEST TO EAST DURING  
TUESDAY, WHICH WILL PROVIDE ANOTHER ROUND OF BENEFICIAL RAIN TO EASE  
THE DROUGHT AND FIRE WEATHER ISSUES. QPF AMOUNTS APPEAR TO GENERALLY  
RANGE FROM A HALF AN INCH TO ONE INCH, BUT THERE WILL LIKELY BE SOME  
LOCALLY HIGHER AMOUNTS. MODEL SOUNDINGS HINT AT SOME ELEVATED CAPE,  
BUT THE CONVECTIVE THREAT IS RATHER WEAK GIVEN THAT THE MAIN  
DYNAMICS OF THE FRONT CROSS OVERHEAD DURING THE LATE NIGHT INTO THE  
MORNING OVER THE MOUNTAINS. STILL, THERE IS ENOUGH CONFIDENCE TO  
MENTION A SLIGHT CHANCE OF THUNDER, BUT THE BEST CHANCE IS IN THE  
PIEDMONT BY THE AFTERNOON AS THE FRONT DEPARTS TOWARD THE COAST.  
BECAUSE OF THE EXPECTED CLOUDY AND WET CONDITIONS, TEMPERATURES WERE  
LEANED TO THE COOLER SIDE OF GUIDANCE.  
 
ONCE THE COLD FRONT EXITS OFFSHORE BY TUESDAY NIGHT, THERE MAY BE  
SOME GUSTY NORTHWEST WINDS DUE TO THE PRESSURE GRADIENT FROM LOW  
PRESSURE DEPARTING AND HIGH PRESSURE BUILDING EASTWARD. HOWEVER, THE  
WINDS ARE NOT EXPECTED TO BE OVERLY SIGNIFICANT, BUT THEY WILL  
PROVIDE SOME COLD AIR ADVECTION INTO WEDNESDAY MORNING. THOSE WINDS  
SHOULD RELAX BY WEDNESDAY EVENING AS HIGH PRESSURE SETTLES OVER THE  
MID ATLANTIC. CLEAR SKIES, CALM WINDS, AND GOOD RADIATIONAL COOLING  
FOR WEDNESDAY NIGHT COULD PRESENT ANOTHER OPPORTUNITY FOR FROST AND  
FREEZE CONCERNS WEST OF THE BLUE RIDGE BY THURSDAY MORNING. CONFIDENCE  
IS HIGH THAT DRY WEATHER WILL PERSIST THROUGH WEDNESDAY AND  
THURSDAY.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 227 PM EDT SUNDAY...  
 
AN UPPER LEVEL TROUGH WILL DIG SOUTHWARD THROUGH THE PLAINS ON  
THURSDAY. WHAT HAPPENS NEXT IS DIFFERENT DEPEND ON YOUR MODEL  
CHOICE. PATTERN EVOLUTION UNCERTAINTY RESULT IN LOW FORECAST  
CONFIDENCE FORECAST. THE WEATHER WILL BE UNSETTLED INTO THE WEEKEND.  
ON THE ECMWF, THE LOW BECOMES CUTOFF OVER TEXAS AND OKLAHOMA FRIDAY  
AND LIFTS NORTHEAST DURING THE WEEKEND, WHILE THE GFS HOLDS AN OPEN  
TROUGH THAT PROGRESSES EAST. DECIDED TO USE A BLEND OF THE NBM AND  
WPC FOR THE EXTENDED PERIOD WITH THE MORE PROGRESSIVE SOLUTION.  
 
HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC THURSDAY MORNING WILL  
SLIDE EAST AND PUSH OFF THE COAST THURSDAY EVENING INTO THURSDAY  
NIGHT. A COLD FRONT WILL APPROACH FROM THE WEST FRIDAY AND MOVE  
ACROSS FRIDAY NIGHT. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE  
BOUNDARY AROUND FRIDAY NIGHT AND PROPEL IT NORTH ON SATURDAY INTO  
SATURDAY NIGHT. THE PLACEMENT OF THE UPPER TROUGH ON SUNDAY REMAINS  
IN QUESTION WITH MODEL DIFFERENCES. ELECTED TO GO WITH THE MORE  
PROGRESSIVE DRIER SOLUTION FROM THE GFS WITH HIGH PRESSURE BUILDING  
SOUTH FROM PENNSYLVANIA SUNDAY. DETAILS ON THE LONG RANGE WILL  
BECOME CLEAR OVER TIME.  
 

 
   
AVIATION /12Z MONDAY THROUGH FRIDAY/
 
 
AS OF 745 AM EDT MONDAY...  
 
EARLY THIS MORNING, HIGH PRESSURE WILL CONTINUE TO NOSE SOUTH  
ALONG THE LEE (EAST SIDE) OF THE SPINE OF THE APPALACHIANS. THE  
GROUND IS MOIST FROM RECENT WIDESPREAD RAINS. WINDS WILL BE  
CALM OR LIGHT AND VARIABLE THROUGH THE MORNING. AS SUCH,  
INGREDIENTS ARE PLACE FAVORABLE FOR STRATUS AND PATCHY FOG WITH  
POTENTIAL FOR LOCAL LIFR/IFR THROUGH MID MORNING (14Z/10AM).  
 
CONDITIONS WILL IMPROVE SLOWLY, WITH MOST LOCATIONS EAST OF THE  
BLUE RIDGE TRANSITIONING TO VFR CONDITIONS BY THE EARLY  
AFTERNOON. CONDITIONS ACROSS THE MOUNTAINS MAY ONLY IMPROVE TO  
MVFR BY THE LATE AFTERNOON PER INCREASING UPSLOPE LOW LEVEL WIND  
FLOW WHICH WILL CAUSE LOW LEVEL CLOUDS TO PERSIST.  
 
WINDS WILL START TO INCREASE FROM THE SOUTHEAST BY MID-DAY AS A  
LOW LEVEL JET INCREASES AHEAD OF APPROACHING COLD FRONT OVER THE  
MID SECTION OF THE COUNTRY. SOME OF THE HIGHER ELEVATIONS MAY  
SEE SUSTAINED WINDS CLOSE TO 10 TO 15 KTS BY THE LATE  
AFTERNOON, BECOMING GUSTY LATE IN THE DAY AND OVER THE RIDGE  
CRESTS MONDAY NIGHT. BLF WILL LIKELY EXPERIENCE WIND GUSTS UP  
TO 25 KTS AHEAD OF THE FRONT MONDAY NIGHT AND INTO EARLY TUESDAY  
MORNING. SOME OF THE MODELS ARE INDICATING POTENTIAL FOR A  
PERIOD OF LOW LEVEL WIND SHEAR JUST AHEAD OF THE FRONT TOWARD  
DAYBREAK TUESDAY.  
   
EXTENDED AVIATION DISCUSSION
 
 
A COLD FRONT WILL BRING THE NEXT CHANCE OF RAIN AND MVFR  
CONDITIONS BETWEEN MIDNIGHT MONDAY NIGHT AND NOON TUESDAY. DRY  
WEATHER AND VFR CONDITIONS ARE EXPECTED BY WEDNESDAY. MOISTURE  
IS EXPECTED TO RETURN BY FRIDAY WITH ANOTHER OPPORTUNITY FOR  
RAIN AND SUB-VFR.  
 

 
   
FIRE WEATHER
 
 
THE REMNANTS OF TROPICAL STORM NESTOR PROVIDED A WIDESPREAD  
WETTING RAIN OVER THE PAST WEEKEND (OCT 19-20TH) WITH RAINFALL  
AMOUNTS OF 1 TO 3 INCHES ACROSS THE HYDROLOGIC SERVICE AREA  
(HSA). ADDITIONAL RAINFALL IS LIKELY WITH A FRONTAL PASSAGE  
TUESDAY, AND MORE RAIN IS FORECAST TOWARD THE END OF THE WEEK.  
 
THE WEATHER PATTERN SUPPORTS THE POTENTIAL FOR RAIN EVERY 4 TO 7  
DAYS. THIS TREND IS EXPECTED TO IMPROVE GROUND WATER CONDITIONS  
AND HELP MUTE FIRE CONCERNS.  
 

 
   
RNK WATCHES/WARNINGS/ADVISORIES
 
 
VA...NONE.  
NC...NONE.  
WV...NONE.  
 

 
 

 
SYNOPSIS...PM  
NEAR TERM...PM  
SHORT TERM...PW  
LONG TERM...KK  
AVIATION...PM  
FIRE WEATHER...PM  
 
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