677  
FXUS61 KRLX 220207  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
1007 PM EDT MON AUG 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE CONTINUES INTO TUESDAY. STRONG COLD FRONT LATE  
TUESDAY INTO TUESDAY NIGHT. COOLER AND DRIER HIGH PRESSURE INTO  
THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TUESDAY/
 
 
AS OF 1000 PM MONDAY...  
 
MADE SOME MINOR TWEAKS TO TEMPS AND DEWPOINTS THIS EVENING, BUT  
NO OTHER CHANGES MADE WITH FORECAST ON TRACK.  
 
AS OF 210 PM MONDAY...  
 
MAINLY DRY EXCEPT IN THE NORTH WHERE A FEW ISOLATED SHOWERS ARE  
POSSIBLE THIS AFTERNOON AND EVENING. HIGH PRESSURE LINGERS INTO  
TUESDAY, BUT THEN A WELL DEFINED SYSTEM TRANSLATES THROUGH  
TUESDAY EVENING.  
 
ALL INDICATIONS SUGGEST THAT THERE COULD BE SOME SEVERE WEATHER  
WITH THIS FRONTAL SYSTEM THOUGH BELIEVE IT WILL BE NORTH OF THE  
I-64 CORRIDOR. AMPLE MOISTURE, UPPER AND LOW LEVEL FORCING, AND  
WIND SHEAR ALL PROVIDE A FAVORABLE ATMOSPHERE FOR STORM  
DEVELOPMENT AND MAINTENANCE. VEERING WIND PROFILES ALSO SUGGEST  
SOME POTENTIAL FOR ROTATING STORMS. TIMING OF THE SYSTEM, WITH  
THE FRONT MOVING THROUGH IN THE LATE AFTERNOON, IS JUST ABOUT  
RIGHT FOR MAXIMUM REALIZATION OF CAPE. PW'S ARE ALSO QUITE HIGH  
IN THE 2.5" ARENA, SO HEAVY DOWNPOURS WILL ALSO ACCOMPANY THESE  
STORMS. LUCKILY THEY SHOULD HAVE ENOUGH FORWARD PROPAGATION THAT  
ONLY LOCAL WATER ISSUES MAY RESULT. FOR NOW, GUSTY OUTFLOW FROM  
CELLS LOOKS LIKE THE LARGEST THREAT WITH DAMAGING WINDS  
POSSIBLE. THE TORNADO AND FLASH FLOODING THREATS ARE FAIRLY  
LOW, BUT NON-ZERO.  
 

 
   
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
 
 
AS OF 350 PM MONDAY...  
 
AS HAS BEEN DESCRIBED WITH PREVIOUS FORECAST ISSUANCES, THIS  
SYSTEM WILL FEATURE TWO DISTINCT SURFACE FRONTS. THE INITIAL  
FRONT WILL BE THE FOCUS OF CONVECTION AND WILL BE LOCATED NEAR  
THE OHIO RIVER BY 8 PM TUESDAY. SEVERE POTENTIAL WILL BE WANING  
WITH THE LOSS OF DAYTIME HEATING AND INSTABILITY, THOUGH PRECIP  
LOADING FROM HEAVY DOWNPOURS COMBINED WITH MOMENTUM TRANSFER OF  
UPPER LEVEL WINDS CAN STILL GENERATE OCCASIONALLY STRONG GUSTS  
OVERNIGHT. THIS FRONT WILL CLEAR THE CWA BY DAY BREAK WEDNESDAY.  
 
THE SECONDARY FRONT, BEHIND WHICH LIES THE MUCH-ANTICIPATED  
CANADIAN AIRMASS, WILL MOVE THROUGH THE EASTERN MOUNTAINS BY  
THE END OF THE DAY WEDNESDAY. SCATTERED REDEVELOPMENT OF  
SHOWERS AND PERHAPS STORMS ALONG THE FRONT IN THE WV MOUNTAINS  
AND SOUTHWEST VA IS LIKELY DURING THE WEDNESDAY AFTERNOON HOURS.  
MEANWHILE, THE REMAINDER OF THE AREA OUTSIDE OF THE MOUNTAINS  
WILL ENJOY HIGH TEMPERATURES 5-10 DEG F BELOW NORMAL WITH  
COMFORTABLE DEWPOINTS IN THE 50'S UNDER THE FULL INFLUENCE OF  
DEEP NORTHWEST FLOW.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
AS OF 350 PM MONDAY...  
 
THE REGION WILL BE UNDER THE INFLUENCE OF DEEP NORTHWEST FLOW TO  
START THE PERIOD. EASTERLY LOW-LEVEL FLOW FROM THE ATLANTIC IN  
THE PIEDMONT WILL PROVIDE SOME LOW-LEVEL MOISTURE FOR  
DISTURBANCES EMBEDDED WITHIN NW FLOW TO POTENTIALLY DRUM UP  
SHOWERS IN THE MOUNTAINS DURING THE WEEKEND. AREAS WEST OF THE  
MOUNTAINS WILL ENJOY PERSISTENT DRY NORTHEASTERLY SURFACE  
WINDS. THIS SYNOPTIC PATTERN WILL HOLD WHILE THE PARENT CLOSED  
UPPER- LEVEL LOW STRUGGLES TO EXIT EASTERN CANADA. AT THE VERY  
END OF THE FORECAST PERIOD, LONG- TERM MODELS INDICATE AN  
EMBEDDED SHORT- WAVE DEVELOPING A SURFACE SYSTEM TO INCREASE  
PRECIPITATION CHANCES TO START THE WORK-WEEK.  
 

 
   
AVIATION /02Z TUESDAY THROUGH SATURDAY/
 
 
AS OF 730 PM MONDAY...  
 
CIRRUS ON THE INCREASE OVERNIGHT INTO TUESDAY MORNING. THIS, AND  
SOME FLOW SHOULD KEEP DENSE FOG OUT OF MOST AREAS. DID INCLUDE  
SOME IFR AT EKN IN THE DEEPER VALLEY AND WITH THE THINEST  
CLOUDS.  
 
ISOLATED THUNDERSTORMS WILL DEVELOP TUESDAY AFTERNOON AHEAD OF A  
COLD FRONT. THESE SHOULD DRIVE FROM SW TO NE. INCLUDED VCTS DUE  
TO UNCERTAINTY WITH LOCATION AND TIMING.  
 
STRONGER AND MORE ORGANIZED STORMS EXPECTED LATE AFTERNOON INTO  
THE EVENING AS A COLD FRONT PUSHES IN FROM THE WEST. WOULD  
EXPECT BRIEF DROPS INTO IFR AS THESE MOVE FROM WEST TO EAST INTO  
TUESDAY NIGHT.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY...  
 
FORECAST CONFIDENCE: HIGH.  
 
ALTERNATE SCENARIOS: MAY HAVE POCKETS OF DENSER FOG TONIGHT. MAIN  
LINE OF STORMS WITH COLD FRONT TUESDAY EVENING COULD ARRIVE A  
BIT EARLIER THAN FORECAST.  
 
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 TUE 08/22/17  
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11  
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07  
CRW CONSISTENCY H H H H H H H H H H H L  
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 H H M M M L L L M  
PKB CONSISTENCY H H H H H H H H H H H L  
CKB CONSISTENCY H H H H H H H H H H H M  
 
AFTER 00Z WEDNESDAY...  
IFR POSSIBLE IN SHOWERS AND STORMS TUESDAY NIGHT. IFR POSSIBLE  
IN LOW STRATUS AND SHOWERS/FOG INTO EARLY WEDNESDAY. RIVER  
VALLEY FOG POSSIBLE EACH MORNING THROUGH THE WEEKEND.  
 

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

 
 

 
SYNOPSIS...JW/MC  
NEAR TERM...JW/MZ  
SHORT TERM...MC  
LONG TERM...MC  
AVIATION...MZ  
 
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