284  
FXUS61 KRLX 141804  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
104 PM EST THU DEC 14 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE INTO FRIDAY. A CLIPPER SYSTEM THEN PASSES NORTH  
OF THE AREA FRIDAY NIGHT. WEAK SYSTEM BRINGS LIGHT RAIN SUNDAY  
AND MONDAY. ANOTHER CLIPPER CROSSES TUESDAY.  
 

 
   
NEAR TERM /THROUGH FRIDAY/
 
 
AS OF 100 PM THURSDAY...  
 
DIRTY HIGH PRESSURE BUILDING OVER THE AREA, BUT APPEARS THAT  
SOME COLD AIR STRATUS AND LEFT OVER LAKE EFFECT CLOUDS WILL  
BECOME TRAPPED UNDER THE HIGH. WITH PATCHES OF CLOUDS FLOATING  
AROUND, IT LEADS TO LOW CONFIDENCE TONIGHT ON WHERE CLOUDS WILL  
BE. THIS ALSO MAKES OVERNIGHT LOWS RATHER TRICKY. WITH WINDS  
BECOMING LIGHT, THINKING THERE WILL BE ENOUGH HOLES FOR  
TEMPERATURES TO DROP NEAR DEW POINTS.  
 
A WAVE MOVES WELL NORTH OF THE AREA ON FRIDAY. IT WILL CREATE A  
LITTLE MOISTURE INCREASE IN THE NORTH IN THE AFTERNOON. THIS  
COULD BE ENOUGH FOR FEW FLAKES DUE TO THE COLD 850 MB  
TEMPERATURES, SO WILL KEEP SOME SMALL POPS.  
 

 
   
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
 
 
AS OF 420 AM THURSDAY...  
 
WEAK HIGH PRESSURE OVER THE AREA FRIDAY MORNING QUICKLY GIVES  
WAY TO THE NEXT, AND THE LAST IN THE SERIES OF, WEAK CLIPPER  
SYSTEMS OF LATE. IT WILL TRACK EVEN FARTHER NORTH THAN ITS  
PREDECESSOR, CROSSING THIS MORNING, WHICH WAS TRACKING FARTHER  
NORTH THAN ITS PREDECESSORS, A SIGN OF THE BREAKING DOWN OF THE  
EASTERN U.S. LONG WAVE TROUGH PATTERN. HEIGHTS BUILD AND FLATTEN AS  
THE LONG WAVE TROUGH LIFTS OUT. THEREFORE, NORTHERN MOUNTAIN  
SNOW AMOUNTS FRIDAY NIGHT ARE LIMITED, AND THE COLD AIR PULLS  
OUT QUICKLY ON SATURDAY.  
 
A SOUTHERN STREAM SHORT WAVE TROUGH GETS LEFT BEHIND OVER THE  
SOUTHWESTERN STATES, AS THE EASTERN U.S TROUGH LIFTS OUT. IT  
THEN EJECTS EAST-NORTHEASTWARD, AS ANOTHER SHORT WAVE TROUGH DIGS  
INTO THE SOUTHWESTERN STATES. THIS WILL BRING MILDER AIR, ALONG  
WITH SOME LIGHT RAIN, ACROSS THE AREA SUNDAY AND SUNDAY NIGHT.  
 
CENTRAL GUIDANCE TEMPERATURES LOOKED GOOD, OTHER THAN SLIGHT  
NON DIURNAL WARMING EARLY SUNDAY MORNING.  
 

 
   
LONG TERM /MONDAY THROUGH WEDNESDAY/
 
 
AS OF 420 AM THURSDAY...  
 
WEAK HIGH PRESSURE BRIEFLY VISITS MONDAY MORNING, BUT WITH LOW  
LEVEL MOISTURE REMAINING IN PLACE, AND WEAK WARM ADVECTION AS  
THE HIGH EXITS DURING THE DAY ON MONDAY, IT WILL REMAIN CLOUDY,  
WITH THE CHANCE FOR LIGHT RAIN, OR DRIZZLE, INTO MONDAY NIGHT.  
 
A NORTHERN STREAM TROUGH DIGS INTO THE EASTERN U.S. MONDAY AND  
TUESDAY, TEMPORARILY RE-ESTABLISHING THE PATTERN THAT BREAKS  
DOWN OVER THE WEEKEND. THIS BRINGS THE CHANCE FOR RAIN SHOWERS  
ON TUESDAY, WHICH COULD TRANSITION TO SNOW SHOWERS TUESDAY NIGHT  
IN THE MOUNTAINS, WHILE ENDING ELSEWHERE.  
 
THE PERIOD ENDS DRY, BUT, AFTER A MODEST COOL DOWN WEDNESDAY,  
MILDER WEATHER TAKES HOLD FOR THURSDAY, AS SURFACE HIGH  
PRESSURE OVER THE AREA WEDNESDAY, MOVES EAST ON THURSDAY, AND  
AN UPPER RIDGE CROSSES.  
 
CENTRAL GUIDANCE TEMPERATURES ACCEPTED, OTHER THAN TO RAISE LOWS  
IN THE MOUNTAINS A BIT MONDAY NIGHT, TO SUPPORT AN ALL LIQUID  
PRECIPITATION TYPE. THIS REFLECTS ABOVE NORMAL TEMPERATURES,  
EXCEPT CLOSE TOP NORMAL ON WEDNESDAY. THE LATEST MEX IS HIGHER  
STILL, ALTHOUGH THAT MAY DEPEND UPON BETTER MIXING.  
 

 
   
AVIATION /18Z THURSDAY THROUGH TUESDAY/
 
 
AS OF 1230 PM THURSDAY...  
 
A COLD ADVECTION STRATUS/CUMULUS MVFR/VFR DECK WILL REMAIN  
ACROSS THE AREA THIS AFTERNOON, GRADUALLY RISING. PORTIONS OF  
THIS DECK ARE EXPECTED TO REMAIN OVERNIGHT, GRADUALLY SINKING  
BACK INTO THE MVFR RANGE, ESPECIALLY IN THE MOUNTAINS. THE DECK  
WILL GRADUALLY RAISE AGAIN ON FRIDAY.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...  
 
 
FORECAST CONFIDENCE: MEDIUM.  
 
ALTERNATE SCENARIOS: LOCATION OF STRATUS DECK OVERNIGHT COULD  
VARY.  
 
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 M  
HTS CONSISTENCY M H M H H H H H H H H M  
BKW CONSISTENCY M H M M H H H H H H H L  
EKN CONSISTENCY H H M M M M M M M M H L  
PKB CONSISTENCY H M H M H H H H H H H M  
CKB CONSISTENCY M M H M H H H H H H H L  
 
AFTER 18Z FRIDAY...  
ANOTHER ROUND OF SNOW IS EXPECTED ACROSS THE NORTHERN PORTION OF  
THE AREA FRIDAY NIGHT, WITH IFR CONDITIONS POSSIBLE IN HEAVIER  
SNOW SHOWERS.  
 

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

 
 

 
SYNOPSIS...TRM  
NEAR TERM...RPY  
SHORT TERM...TRM  
LONG TERM...TRM  
AVIATION...RPY  
 
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