284  
FXUS61 KRLX 131937  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
237 PM EST THU DEC 13 2018  
   
SYNOPSIS
 
 
SOUTH TO SOUTHWEST FLOW BRINGS AN INCREASE IN TEMPERATURES AND  
MOISTURE THROUGH TONIGHT. STRONG STORM SET TO IMPACT THE AREA  
FRIDAY INTO THIS WEEKEND.  
 

 
   
NEAR TERM /THROUGH FRIDAY/
 
 
AS OF 220 PM THURSDAY...  
 
A SOMEWHAT ILL-DEFINED WARM FRONTAL BOUNDARY WILL CONTINUE  
LIFTING NORTHWARD THROUGH THE FORECAST AREA THROUGH THURSDAY  
EVENING. WHILE THE FEATURE HAS HELPED MAINTAIN A STRATUS DECK  
ACROSS THE AREA THIS AFTERNOON, THERE HAS BEEN VERY LITTLE  
IMPACT ACROSS THE REGION OTHER THAN SOME LIGHT ECHOES VISIBLE ON  
THE REGIONAL RADAR MOSAIC.  
 
A SURFACE HIGH WILL SLIDE OFF THE COAST OF NEW ENGLAND THIS EVENING  
WHICH WILL HELP TO PROMOTE A WEDGE OF HIGH PRESSURE ALONG THE EAST  
SIDE OF THE MOUNTAINS. MEANWHILE, A LOW PRESSURE SYSTEM WILL BE  
MOVING ACROSS THE LOWER MISSISSIPPI VALLEY OVERNIGHT. STRONG  
MOISTURE TRANSPORT AHEAD OF THIS SYSTEM WILL ALLOW PRECIPITATION TO  
INCREASE IN COVERAGE FROM SOUTH TO NORTH BY FRIDAY MORNING. AS  
PRECIPITATION INITIALLY ARRIVES FRIDAY MORNING, THERE IS A CHANCE OF  
FREEZING RAIN ALONG THE EASTERN SLOPES OF THE APPALACHIAN RIDGE. DUE  
TO THE STRENGTHENING WARM AND MOIST SOUTHEAST FLOW ON FRIDAY, THIS  
FREEZING RAIN THREAT WILL BE VERY BRIEF AS SUB-FREEZING AIR NEAR THE  
SURFACE GETS SCOURED OUT QUICKLY. THUS, THERE IS POTENTIAL FOR A  
VERY LIGHT GLAZE OF ICE BEFORE A TRANSITION TO RAIN ACROSS THE  
REGION. DOWNSLOPE FLOW SHOULD LIMIT QPF AMOUNTS ACROSS THE LOWLANDS,  
BUT PERIODS OF RAIN WILL PERSIST THROUGH THE NEAR TERM PERIOD.  
 

 
   
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 215 PM THURSDAY...  
 
FORECAST REMAINS ON TRACK WITH HIGHER ELEVATIONS LIKELY TO BE IN  
AREAS OF ENHANCED RAINFALL FOR THE FIRST HALF OF THE WEEKEND.  
THE CENTER OF THE UPPER LEVEL LOW VARIES A BIT BETWEEN THE  
MODELS, WHICH WILL CONTRIBUTE TO A TRICKIER FORECAST FOR MONDAY  
NIGHT, DISCUSSED MORE IN THE LONG TERM PORTION. STORM TOTAL  
RAINFALL FROM THIS AFTERNOON'S FORECAST PACKAGE HINTS THAT  
HIGHEST AMOUNTS WITH THIS WEEKEND SYSTEM WILL LIE ALONG THE  
RIDGETOPS WHILE THE LOWLANDS WILL LIKELY RECEIVE ONE AND A  
QUARTER INCHES OF RAIN THROUGH THE DURATION OF THIS STORM.  
FLOODING CONCERNS HAVE LOWERED THIS AFTERNOON GIVEN THE LATEST  
OBSERVATIONS OF DIMINISHING SNOWPACK ACROSS THE AREA. OUR  
SOUTHERN VIRGINIA COUNTIES WILL BE THE BIGGEST AREA OF FOCUS  
FOR LOCALIZED FLOODING POTENTIAL DUE TO SNOW STILL HOLDING  
STRONG COMPARED TO THE REST OF THE CWA.  
 
CLOUDS WILL DOMINATE CENTRAL APPALACHIA THROUGH MUCH OF THE  
WEEKEND UNTIL THE UPPER LEVEL LOW EXITS EASTWARD LATE IN THE  
SHORT TERM.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
AS OF 205 PM THURSDAY...  
 
WHILE THE UPPER LEVEL LOW IS EXPECTED TO PUSH INTO THE ATLANTIC  
BY SUNDAY EVENING, THERE IS STILL SOME UNCERTAINTY WITH THE  
POTENTIAL FOR AN UPSLOPE EVENT MONDAY NIGHT AND WHETHER COLD  
AIR WILL BE USHERED OVER THE MOUNTAINS IN TIME FOR THAT TO  
OCCUR. THE SUPERBLEND KEPT US DRY FOR NOW DURING THAT TIME  
FRAME, BUT I WILL BE KEEPING A CLOSE EYE ON MODEL TRENDS FOR  
TOMORROW'S FORECAST UPDATE TO DETERMINE WHETHER OR NOT TO  
INTRODUCE SNOW FOR MONDAY NIGHT. BIGGEST CONTENDER FOR AN  
UPSLOPE EVENT LIES WITH THE GFS CURRENTLY WHERE COLD AIR  
ADVECTION WILL TAKE SHAPE, WHILE THE ECMWF SOLUTION REMAINS  
DRIER WITH THE LAST MODEL GUIDANCE. ONCE WE GET PAST THIS  
SHORTWAVE FEATURE, MODELS RETURN TO AN AGREEMENT OF HIGH  
PRESSURE BUILDING IN FOR MIDWEEK, THEN HINTING AT THE NEXT  
DISTURBANCE MOVING UP FROM THE SOUTH LATE NEXT WEEK.  
 

 
   
AVIATION /20Z THURSDAY THROUGH TUESDAY/
 
 
AS OF 100 AM THURSDAY...  
 
A WARM FRONTAL BOUNDARY CONTINUES TO LIFT NORTHWARD ACROSS THE  
REGION THIS AFTERNOON. BRIEF PERIODS OF MVFR CONDITIONS ARE POSSIBLE  
AS THIS FEATURE LIFTS THROUGH AS CIGS TEMPORARILY LOWER, BUT AM NOT  
EXPECTING VSBY RESTRICTIONS WITH THIS FEATURE. BY 00Z FRIDAY, THE  
WARM FRONT WILL BE NORTH OF THE REGION WITH CIGS GRADUALLY RISING  
OVERNIGHT THROUGH AROUND 06Z, AND THEN BEGIN LOWERING AGAIN AS RAIN  
INCREASES IN COVERAGE FROM SOUTH TO NORTH AHEAD OF A STORM SYSTEM  
DEVELOPING TO OUR SOUTH.  
 
SOUTHEAST WINDS WILL BECOME GUSTY BY FRIDAY MORNING AT BKW AS THE  
LEADING EDGE OF THE PRECIPITATION SHIELD ARRIVES, WHERE WINDS COULD  
GUST AS HIGH AS 25 KTS. WIDESPREAD RAIN SHOULD ARRIVE AREA-WIDE BY  
FRIDAY AFTERNOON WITH PERIODS CIG AND VSBY RESTRICTIONS POSSIBLE,  
BUT CONFIDENCE IN TIMING OF THE HEAVIEST SHOWERS REMAINS TOO LOW TO  
INCLUDE IN TAF.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...  
 
FORECAST CONFIDENCE: HIGH EXCEPT AT BKW.  
 
ALTERNATE SCENARIOS: IFR CONDITIONS POSSIBLE BY 12Z AT BKW.  
 
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 18 19 20 21 22 23 00 01 02 03 04 05  
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00  
CRW CONSISTENCY H H H H H H H H H H H H  
HTS CONSISTENCY H H H H H H H H H H H H  
BKW CONSISTENCY H H H H H H H H H H H H  
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 H  
CKB CONSISTENCY H H H H H H H H H H H H  
 
AFTER 18Z FRIDAY...  
IFR IN STRATUS POSSIBLE IN RAIN FRIDAY INTO SUNDAY.  
 

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

 
 

 
SYNOPSIS...ARJ/MPK/MEK  
NEAR TERM...RG  
SHORT TERM...MEK  
LONG TERM...MEK  
AVIATION...RG  
 
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