515  
FXUS61 KRLX 210717  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
317 AM EDT SAT OCT 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE CONTINUES THROUGH THE WEEKEND WITH MOSTLY CLEAR  
SKIES. A STRONG COLD FRONT AND LOW PRESSURE SYSTEM CROSSES  
EARLY NEXT WEEK, WITH MUCH COOLER WEATHER MIDWEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 255 AM SATURDAY...  
 
TEMPERATURES WILL BE A BIT WARMER TODAY THAN WHAT WE SAW THE  
LAST FEW DAYS. HIGH PRESSURE SLOWLY DRIFTS EASTWARD TODAY AND  
LOW LEVEL FLOW SWITCHES AROUND TO THE SW...HENCE THE WARMER  
TEMPS, BUT WE WILL CONTINUE TO SEE MOSTLY CLEAR SKIES, OTHER  
THAN SOME CIRRUS PASSING THROUGH FROM THE WEST. ALSO, LOOKING AT  
SOME WARMER TEMPS OVERNIGHT WITH DEW POINTS COMING UP A BIT WITH  
THE WARM MOIST SW FLOW. TONIGHT WE WILL SEE THE POSSIBILITY FOR  
VALLEY FOG ONCE AGAIN, BUT OTHERWISE A NICE NIGHT OVERALL.  
 

 
   
SHORT TERM /SUNDAY THROUGH TUESDAY/
 
 
AS OF 315 AM SATURDAY...  
 
HIGH PRESSURE DEPARTING TO THE NE TO START THE PERIOD AS A  
STRONG COLD FRONT APPROACHES FROM THE WEST. SLOWED DOWN POPS A  
BIT ON THE FRONT SIDE...KEEPING THE SUNDAY NIGHT PERIOD DRY.  
THEN HAVE POPS RAPIDLY INCREASING MONDAY AFTERNOON WITH 80-90  
POPS LATE MONDAY EVENING AND MONDAY NIGHT. MODELS STILL  
STRUGGLING A BIT WITH THE LOCATION OF THE SURFACE LOW AND COLD  
FRONT, BUT BOTH GFS AND ECMWF POINTING TO A RAINY NIGHT. THE  
ECMWF HAS THE FRONT THROUGH THE FORECAST AREA BY 12Z TUESDAY,  
WHILE THE GFS IS A BIT SLOWER WITH THE FRONT STILL CROSSING THE  
MOUNTAINS AROUND THAT TIME. THIS APPEARS TO BE DUE TO THE GFS  
CLOSING OFF A SOUTHERN STREAM UPPER LOW OVER THE LOWER  
MISSISSIPPI RIVER VALLEY, WHILE THE ECMWF KEEPS IT OPEN AND MORE  
PROGRESSIVE. NO STRONG FEELING EITHER WAY AT THIS POINT, SO  
STAYED CLOSE TO THE CONSENSUS BLEND.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
 
 
AS OF 315 AM SATURDAY...  
 
WITH THE COLD FRONT TO THE EAST TO START THE PERIOD, ATTENTION  
TURNS TO THE TRAILING UPPER LEVEL TROUGH. THE TROUGH AXIS SHOULD  
BE CROSSING THE FORECAST AREA EARLY WEDNESDAY, SO HAVE LINGERED  
CHANCE POPS THROUGH MOST OF THE DAY -- ENVISIONING SCATTERED  
SHOWERS AS THE COLD AIR FILTERS IN. GFS CONTINUES TO BE COLDER  
THAN THE ECMWF AT 850MB -- AND HAVE INCLUDED SOME SNOW FLAKES  
ACROSS THE NORTHERN MOUNTAINS BOTH TUESDAY NIGHT AND WEDNESDAY  
NIGHT. SURFACE TEMPERATURES MUCH COLDER BY MID WEEK AS WELL,  
WITH HIGHS ON WEDNESDAY GENERALLY IN THE 40S AND LOW-MID 50S.  
 

 
   
AVIATION /07Z SATURDAY THROUGH WEDNESDAY/
 
 
AS OF 145 AM SATURDAY...  
 
HIGH PRESSURE HAS PUSHED OVER THE REGION AND LOW LEVEL WINDS ARE  
WEAKER EARLY THIS MORNING THAN THEY WERE LAST NIGHT. HOWEVER,  
THERE REMAINS A LOT OF UNCERTAINTY ON HOW MUCH VALLEY FOG WILL  
DEVELOP. FORECAST MODEL GUIDANCE IS NOT INTERESTED IN ANY FOG  
UNTIL MOST RECENT RUNS PINNING IFR FOG AT EKN AROUND SUNRISE.  
DECIDED TO USE UPS CROSSOVER TECHNIQUE FOR THIS MORNINGS FOG  
FORECAST, AND ALTHOUGH GUIDANCE IS NOT INDICATING FOG, EKN AND  
HTS SHOULD AT THE VERY LEAST HIT THEIR CROSSOVER TEMPERATURES,  
SO HAVE ONLY INCLUDED IFR CONDITIONS AT THOSE LOCATIONS. CRW  
WILL BE A BIT TOUGHER TO FOG SO HAVE LEFT AT MVFR FOR NOW.  
 
VFR CONDITIONS ARE EXPECTED THROUGH THE DAY SATURDAY WITH DRY  
HIGH PRESSURE REMAINING OVER THE AREA.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY...  
 
FORECAST CONFIDENCE: MEDIUM OVERNIGHT.  
 
ALTERNATE SCENARIOS: IFR OR WORSE FOG IS STILL UNCERTAIN AT THIS  
TIME.  
 
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY  
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:  
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.  
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.  
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.  
 
DATE SAT 10/21/17  
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17  
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13  
CRW CONSISTENCY H H H H H M L H H H H M  
HTS CONSISTENCY H H H H H H H H H H H M  
BKW CONSISTENCY H H H H H H H H H H H M  
EKN CONSISTENCY H H H L L L L M H H H M  
PKB CONSISTENCY H H H H H H H H H H H M  
CKB CONSISTENCY H H H H H H H H H H H M  
 
AFTER 06Z SUNDAY...  
DENSE VALLEY FOG POSSIBLE SUNDAY MORNING. HEAVY RAIN AT TIMES  
EARLY NEXT WEEK COULD ALSO BRING IFR CONDITIONS.  
 

 
   
RLX WATCHES/WARNINGS/ADVISORIES
 
 
WV...NONE.  
OH...NONE.  
KY...NONE.  
VA...NONE.  
 

 
 

 
SYNOPSIS...MZ/MPK  
NEAR TERM...MPK  
SHORT TERM...MZ  
LONG TERM...MZ  
AVIATION...MPK  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WV Page
The Nexlab OH Page
The Nexlab KY Page
The Nexlab VA Page Main Text Page