334  
FXUS61 KRLX 021034  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
617 AM EDT TUE SEP 2 2014  
   
SYNOPSIS
 
 
FRONTAL SYSTEM TODAY WITH SHOWERS AND STORMS...SOME STRONG. VERY  
WARM AND HUMID THROUGH THE END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
6 AM UPDATE. TWEAKED POPS INTO LIKELY FOR FAR NORTHWEST ZONES THIS  
MORNING...ALSO EXPANDED LOW POPS EARLY THIS MORNING INTO NORTH  
CENTRAL WV...ALL PER RADAR TRENDS.  
 
PREVIOUS DISCUSSION...  
EVEN THOUGH WE ARE TRANSITIONING INTO THE COOL SEASON...THE PATTERN  
STILL SHOWS SIGNS OF SUMMER AS STRONG UPPER RIDGING HOLDS ACROSS THE  
SOUTHERN PART OF THE NATION. THIS KEEPS OUR AREA IN THE SOUTHERN  
EDGE OF THE WESTERLIES WHICH HAS IMPLICATIONS ON ANY FRONT AFFECTING  
US.  
 
MODELS AGREE ON A STOUT UPPER TROUGH OVER THE MID MISSISSIPPI VALLEY  
LIFTING NORTHEASTWARD ACROSS THE NORTHERN OHIO VALLEY TODAY AND ON  
INTO NEW ENGLAND TONIGHT...WITH A VORT LOBE TRAILING SOUTH ACROSS  
OUR AREA. HOWEVER...THE ASSOCIATED COOL FRONT IS WEAK AND WILL LOSE  
DEFINITION AS IT TRIES TO DROP SOUTHEAST ACROSS THE AREA THIS  
AFTERNOON AND EVENING. IT APPEARS THE FRONT ITSELF WILL HAVE LESSER  
IMPACT ON OUR WEATHER. THE GREATEST IMPACT WILL COME FROM THE UPPER  
TROUGH DYNAMICS IN THE FORM OF A WELL DEFINED RIGHT ENTRANCE REGION  
OF THE UPPER JET AND THE TRAILING VORT LOBE. WITH PW'S AROUND 2  
INCHES AND A MODEST 850 MB SOUTHWESTERLY JET COINCIDING WITH THE  
UPPER DYNAMICS...WE EXPECT A BAND OF STRONG THUNDERSTORMS TO MOVE  
ACROSS THIS AFTERNOON AND EVENING. SPC DOES HAVE THE NORTHWEST HALF  
OF OUR AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS...SO WILL ADD  
GUSTY WINDS AND SMALL HAIL FOR NOW TO THE WEATHER THIS AFTERNOON.  
TIMING OF THE STORMS IS BASED ON GOOD MODEL AGREEMENT...REACHING THE  
OHIO RIVER AROUND 18Z AND PROGRESSING TO THE MOUNTAINS BY 22Z.  
THINGS QUICKLY WIND DOWN THIS EVENING AS THE UPPER TROUGH PULLS AWAY  
AND LOSS OF HEATING...LEAVING ONLY THE FAR SOUTHEAST WITH A SLIGHT  
CHANCE FOR SHOWERS BY MIDNIGHT. LEANING ON LOWER SIDE OF GUIDANCE  
FOR MAX TEMPS NORTHWEST AND HIGHER SIDE SOUTHEAST DUE TO CLOUDS AND  
CONVECTION.  
 
FOR TONIGHT...SURFACE FRONT BY THIS TIME IS ILL DEFINED AT BEST AS  
WEAK HIGH PRESSURE TAKES OVER. LOOKS LIKE ANY DRIER AIR THAT MAKES  
IT INTO THE NORTH AND WEST WILL NOT GET ANY FARTHER. SO WITH LOSS OF  
WIND FLOW AND DECREASING CLOUDS...EXPECT A GOOD DEAL OF RIVER AND  
VALLEY FOG TONIGHT...EVEN UP NORTH AND WEST AS BETTER RADIATIONAL  
COOLING WILL COMPENSATE FOR ANY LOSS OF MOISTURE. TEMPS TONIGHT WILL  
BE A BLEND OF GUIDANCE.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH FRIDAY/
 
 
STRONG UPPER LEVEL RIDGE OVER THE DEEP SOUTH PROVES TO BE PERSISTENT  
AND STILL WILL NOT BE ABLE TO SHAKE THE 590DKM LINE THROUGH THE END  
OF THE WEEK. DESPITE THE SURFACE HIGH PRESSURE BUILDING IN  
WEDNESDAY...THINK WE WILL HAVE ENOUGH LOW LEVEL MOISTURE TO POP  
ISOLATED SHOWERS/STORMS DURING THE DAYTIME HEATING HOURS. STRETCHED  
THE SLIGHT CHANCE POPS THROUGH THE ENTIRE CWA BASED ON THIS  
REASONING.  
 
LEFT THURSDAY LARGELY DRY AS IN THE PREVIOUS FORECAST...WITH THE  
MOUNTAINS AND TUG VALLEY IN THE SLIGHT CHANCE AREA AS BEFORE. NAM  
BRINGS A WEAK TROUGH AXIS ALOFT OVER THE NORTHWESTERN ZONES IN  
SOUTHEAST OHIO...BUT COLUMN WILL LIKELY BE TOO DRY AT THIS POINT FOR  
ANYTHING OF SIGNIFICANCE TO DEVELOP.  
 
BRING THE POPS BACK IN AS THE NEXT SYSTEM APPROACHES...AND FIGURE TO  
GET SOME BETTER DESTABILIZATION DURING THE DAY WITH PRESSURE FALLS.  
 
KEEP THE HIGH TEMPERATURES THROUGH THE PERIOD UNDER THE 90 DEGREE  
MARK GIVEN THE TIME OF YEAR AND MOIST GROUND.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
 
 
HEATING BACK UP...AS THE SOUTHERN 500 MB RIDGE BUILDS BACK NORTH FOR  
FRIDAY. SOME AFTERNOON CONVECTION COULD OCCUR FRIDAY...BUT POPS  
MOSTLY 20 AND 30 PERCENT.  
 
PER WPC MEDIUM COORDINATION...CONTINUE TO TREND SLOWER THAN THE GFS  
ON THE NEXT FRONT. 12Z GFS QUICKLY DRIES OUT OUR NORTHERN COUNTIES  
SATURDAY EVENING INTO SUNDAY. PREFER THE SLOWER ECWMF SOLUTION AT  
THIS TIME...INCREASED POPS INTO LIKELY CATEGORY ON SATURDAY INTO  
SATURDAY EVENING. HOLDING SOME CHANCE POPS EVEN INTO SUNDAY MORNING  
FOR NORTHERN COUNTIES...AND INTO SUNDAY NIGHT FOR SOUTHERN  
COUNTIES. DRY MONDAY...EXCEPT AGAIN SOME SLIGHT CHANCE POPS ALONG  
THE EASTERN SLOPES.  
 

 
   
AVIATION /12Z TUESDAY THROUGH SATURDAY/
 
 
12Z TUESDAY THRU 12Z WEDNESDAY...  
A FRONTAL BOUNDARY WILL PUSH INTO THE AREA THIS AFTERNOON AND  
LOSE DEFINITION AS IT TRIES TO CROSS THE AREA FROM WEST TO EAST  
LATER THIS AFTERNOON AND EVENING. NEVERTHELESS...EXPECT A LINE OF  
THUNDERSTORMS TO MOVE ACROSS...MAINLY THIS AFTERNOON AND EVENING.  
OUTSIDE OF CONVECTION...VFR WILL PREVAIL TODAY. ALSO...SOUTHWEST  
WINDS AHEAD OF THE FRONT WILL BECOME MODERATE THIS AFTERNOON WITH  
GUSTS TO NEAR 20 MPH IN SOME LOCATIONS.  
 
AFTER 00Z...FRONT CONTINUES TO LOSE DEFINITION AS WEAK HIGH  
PRESSURE DEVELOPS OVER THE AREA. WITH CLOUDS AND WINDS  
DECREASING...EXPECTING LIFR RIVER AND VALLEY FOG TO FORM BY  
06Z...AFFECTING MOST OF THE MAJOR TERMINALS.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...  
 
FORECAST CONFIDENCE: MEDIUM.  
 
ALTERNATE SCENARIOS: TIMING OF SHOWERS AND THUNDERSTORMS COULD VARY  
BY A COUPLE OF HOURS. ONSET OF FOG TONIGHT MAY BE DELAYED IF CLOUDS  
HANG ON LONGER.  
 
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.  
 
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22  
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18  
CRW CONSISTENCY H H H H H H H H H M M M  
HTS CONSISTENCY H H H H H H H H M M M M  
BKW CONSISTENCY H H H H H H H H H H H M  
EKN CONSISTENCY H H H H H H H H H H H H  
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 H  
 
AFTER 12Z WEDNESDAY...  
IFR IN RIVER AND VALLEY FOG EARLY WEDNESDAY MORNING.  
 

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

 
 

 
SYNOPSIS...JMV/26  
NEAR TERM...JMV  
SHORT TERM...26  
LONG TERM...KTB  
AVIATION...JMV  
 
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