336  
FXUS61 KRLX 181147  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
647 AM EST FRI JAN 18 2019  
   
SYNOPSIS
 
 
WEAK SYSTEM EXITS TODAY, BUT LOW CLOUDS LINGER. A STRONGER  
STORM SATURDAY AND SATURDAY NIGHT, FOLLOWED BY MUCH COLDER AIR  
AND UPSLOPE SNOW SUNDAY/SUNDAY NIGHT.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 645 AM FRIDAY...  
 
FORECAST ON TRACK.  
 
AS OF 345 AM FRIDAY...  
 
VERY LIGHT PRECIPITATION LINGERS OVER THE AREA, MAINLY EAST OF  
THE OHIO RIVER, EARLY THIS MORNING, AS DEEP LAYER FORCING /  
MOISTURE ASSOCIATED WITH AN UPPER LEVEL SHORT WAVE TROUGH, HAD  
ALREADY SHIFTED TO THE EAST OF THE AREA. THE LIGHT RAIN AND  
DRIZZLE WILL TAPER OFF ACROSS THE LOWLANDS FIRST THING THIS  
MORNING, BUT LIGHT SNOW AND FREEZING DRIZZLE WILL PERSIST INTO  
THIS AFTERNOON OVER THE HIGHER TERRAIN, AS THE TOP OF THE  
SHALLOW MOIST LAYER BENEATH THE SEEMINGLY EVER PRESENT INVERSION  
WAVERS RIGHT IN THE -6 TO -10C RANGE, MARGINAL FOR THE PRESENCE  
OF ICE CRYSTALS IN CLOUD.  
 
THUS WILL LEAVE ADVISORY UP ACROSS THE HIGHEST RIDGES WHICH  
CURRENTLY EXPIRES 10 AM THIS MORNING, WHILE CANCELING THE  
REMAINDER OF IT.  
 
OTHERWISE THE STRATUS IN THE MOIST LAYER BENEATH THE INVERSION,  
WHICH BECOMES A BIT MORE SHALLOW IN TIME, PERSISTS RIGHT UP  
UNTIL THE APPROACH OF THE NEXT SYSTEM, EARLY SATURDAY MORNING.  
 
TEMPERATURES AND DEW POINTS CLOSE TO PREVIOUS AND NEAR TERM  
GUIDANCE, WITH CONTINUING SMALL DIURNAL RANGES BENEATH THE  
STRATUS. TEMPERATURES WILL BE BELOW FREEZING ACROSS THE NORTHERN  
LOWLANDS AS PRECIPITATION ARRIVES THERE TOWARD DAWN SATURDAY.  
MODELS BRING IN LOW LEVEL MOISTURE AHEAD OF THE MID LEVEL  
MOISTURE, RESULTING IN A NEARLY ISOTHERMAL LAYER NEAR 0C IN THE  
SATURATED LAYER, UP THROUGH H8, THUS LIGHT FREEZING RAIN.  
 

 
   
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
 
 
AS OF 415 AM FRIDAY...  
 
A COMPLEX STORM SYSTEM WILL DRIVE THE WEATHER THROUGH THE SHORT TERM  
PERIOD. STARTING OFF SATURDAY, A SURFACE LOW WILL BE MOVING THROUGH  
THE LOWER OHIO RIVER VALLEY. CUT BACK POPS A TOUCH TO START THINGS,  
BUT THEN RAMP THEM UP VERY QUICKLY THROUGH THE MORNING. PRECIP TYPE  
IS A BIT TRICKY EARLY ON, AS SUB-FREEZING SURFACE AIR WILL BE IN  
PLACE ACROSS THE NORTH. MODEL SOUNDINGS SHOW TWO LAYERS OF MOISTURE,  
ONE NEAR THE SURFACE, AND ANOTHER UP NEAR 500MB. THINK THE DRY LAYER  
BETWEEN IS TOO DRY AND THICK TO ALLOW A SEEDER FEEDER PROCESS, SO  
WENT WITH FREEZING RAIN AS THE PRECIPITATION STARTS ACROSS THE  
NORTH, WITH JUST RAIN FARTHER SOUTH WITH TEMPERATURES ABOVE  
FREEZING. EXPECTING TEMPERATURES TO SLOWLY WARM ABOVE FREEZING  
ACROSS THE NORTH THROUGH THE MORNING, WITH A TRANSITION TO RAIN  
FOR MOST OF THE FORECAST AREA BY SATURDAY AFTERNOON. A PERIOD  
OF MODERATE TO HEAVY RAIN ON SATURDAY AFTERNOON WILL PROVIDE  
TOTALS OF 0.6" TO 1.0", WITH LOCALLY HIGHER AMOUNTS POSSIBLE --  
ESPECIALLY IN THE TRI-STATE REGION. THIS COULD LEAD TO SOME  
WATER ISSUES, AND WILL CONTINUE MENTION IN THE HWO.  
 
AS THE SURFACE LOW CROSSES AND HEADS EAST, COLD AIR RUSHES IN FROM  
THE NW. THIS WILL TRANSITION THE RAIN TO SNOW FROM WEST TO EAST  
AFTER SUNSET SATURDAY NIGHT. STILL SOME UNCERTAINTY ON JUST HOW THE  
COLD AIR AND BEST MOISTURE LINE UP, BUT ECMWF AND NAM SHOW A GOOD  
SLUG OF MOISTURE, AND STRONG FROTOGENESIS NEAR THE OHIO RIVER AS THE  
COLD AIR PLOWS IN, RESULTING IN A PERIOD OF HEAVY SNOWFALL ACROSS  
PORTIONS OF SE OHIO. HAVE ISSUED A WINTER STORM WATCH FOR SNOWFALL  
AMOUNTS OF 4-6 INCHES SATURDAY NIGHT ACROSS VINTON, ATHENS, PERRY,  
MORGAN AND WASHINGTON COUNTIES. THE MOISTURE PULLS OUT PRETTY  
QUICKLY, SO THESE COUNTIES REPRESENT THE AREA OF HIGHER CONFIDENCE.  
SOME ADJUSTMENTS SOUTH AND EAST MAY BE NECESSARY IF THE  
MOISTURE LOOKS TO LINGER LONGER.  
 
UPSLOPE SNOW SHOWERS WILL LINGER INTO SUNDAY NIGHT ACROSS THE  
WESTERN SLOPES AND MOUNTAINS. GENERALLY HAVE 1-2" ACROSS LOWER  
ELEVATIONS SOUTH AND EAST OF THE OHIO RIVER WITH 3-5" FOR THE  
NORTHERN MOUNTAINOUS COUNTIES OF WV. AS SKIES BEGIN TO CLEAR SUNDAY  
NIGHT, TEMPERATURES WILL DROP LIKE A ROCK WITH MOST AREAS IN THE  
SINGLE DIGITS ABOVE/BELOW ZERO.  
 

 
   
LONG TERM /MONDAY THROUGH THURSDAY/
 
 
AS OF 415 AM FRIDAY...  
 
ARCTIC HIGH PRESSURE SKIRTS BY TO THE NORTH MONDAY, WITH A VERY  
CHILLY DAY EXPECTED. FLOW THEN TURNS SOUTHERLY ON THE BACK SIDE  
OF THIS HIGH, AND WE GET A GOOD REBOUND OF TEMPERATURES TUESDAY  
INTO WEDNESDAY. THIS IS FAIRLY SHORTLIVED HOWEVER, AS A COLD  
FRONT PUSHES THROUGH TUESDAY NIGHT OR WEDNESDAY -- BASED ON  
MODEL PREFERENCE. THE GFS IS FASTER THAN THE ECMWF HERE. EITHER  
WAY, EXPECT RAIN TO BEGIN WITH, CHANGING OVER TO SNOW AS ANOTHER  
SHOT OF COLD AIR DRAINS IN. THIS FRONT LOOKS TO PICK UP A  
SOUTHERN STREAM SURFACE LOW WEDNESDAY NIGHT INTO THURSDAY.  
AGAIN, MODELS DIFFER SOME ON THIS, BUT THIS SHOULD GIVE ANOTHER  
SHOT OF MOISTURE TO KEEP PRECIPITATION GOING INTO THURSDAY. WITH  
THIS TRACKING EAST OF THE APPALACHIANS, OUR FORECAST AREA  
REMAINS COLD ENOUGH FOR MOSTLY SNOW, BUT THIS FAR OUT CONFIDENCE  
IS PRETTY LOW AND STUCK CLOSE TO THE CONSENSUS BLEND.  
 

 
   
AVIATION /11Z FRIDAY THROUGH TUESDAY/
 
 
AS OF 645 AM FRIDAY...  
 
WIDESPREAD IFR CEILINGS ACROSS THE AREA EXCEPT FOR HTS, WHICH  
HAD ALREADY IMPROVED TO MVFR, ALTHOUGH IFR IS STILL POSSIBLE AT  
TIMES EARLY THIS MORNING. THE LOWEST CEILINGS WERE AT CKB AND  
BKW WHICH SHOULD BE IN THE 200 TO 500 FOOT RANGE MUCH OF THE  
MORNING. CEILINGS WILL IMPROVE TO LOW MVFR LATER THIS MORNING,  
EXCEPT REMAINING IFR BKW, WITH A SLOW IMPROVEMENT TOWARD 1000  
FEET THERE BY TONIGHT. HOLES IN THE STRATUS MAY DEVELOP  
OVERNIGHT TONIGHT OVER CENTRAL WV, AHEAD OF THE NEXT APPROACHING  
SYSTEM. HAVE CRW, CKB AND EKN GOING VFR 07Z-09Z SATURDAY.  
 
VISIBILITY WILL FLUCTUATE FROM MVFR TO IFR IN LIGHT RAIN,  
DRIZZLE AND MIST/FOG IN THE MOUNTAINS THIS MORNING.  
PRECIPITATION WILL GRADUALLY DIMINISH TODAY, AND VISIBILITY WILL  
IMPROVE TO VFR AT CKB AND EKN, BUT MVFR VISIBILITY MAY PERSIST  
AT BKW INTO TONIGHT. LOWLAND SITES HTS, PKB AND CRW WILL HAVE  
VFR VISIBILITY, SAVE FOR MVFR IN DRIZZLE AT TIMES EARLY THIS  
MORNING.  
 
LIGHT WEST TO NORTHWEST FLOW AT THE SURFACE TODAY WILL SWITCH  
TO LIGHT EAST TO NORTHEAST OVER THE LOWLANDS, AND LIGHT  
SOUTHEAST OVER THE MOUNTAINS, TONIGHT. LIGHT TO MODERATE WEST  
FLOW ALOFT TODAY WILL BECOME LIGHT NORTHWEST TONIGHT, AND THEN  
LIGHT SOUTH TO SOUTHEAST OVERNIGHT.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z  
SATURDAY...  
 
FORECAST CONFIDENCE: MEDIUM.  
 
ALTERNATE SCENARIOS: CEILINGS AND VISIBILITY MAY FLUCTUATE  
EARLY THIS MORNING, AND THEN TIMING AND DEGREE OF IMPROVEMENT  
TODAY MAY 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.  
 
DATE FRI 01/18/19  
UTC 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21  
EST 1HRLY 05 06 07 08 09 10 11 12 13 14 15 16  
CRW CONSISTENCY M M L M M M M M H H H H  
HTS CONSISTENCY L L M M M M M H H H H H  
BKW CONSISTENCY L M M M L M M M M M M M  
EKN CONSISTENCY M M M M M M M M M L M M  
PKB CONSISTENCY M M L L M M M M M M H H  
CKB CONSISTENCY H M M M M M L M M M M M  
 
AFTER 12Z SATURDAY...  
IFR/LIFR POSSIBLE IN MAINLY RAIN SATURDAY INTO SATURDAY NIGHT,  
WITH FREEZING RAIN ALSO POSSIBLE NORTH SATURDAY MORNING.  
IFR/LIFR POSSIBLE IN SNOW SHOWERS BY SUNDAY MORNING, PERSISTING  
INTO SUNDAY AFTERNOON, AS A STRONG SYSTEM MOVES THROUGH. WINDY  
FROM THE NORTHWEST, AND SHARPLY COLDER, SUNDAY.  
 

 
   
RLX WATCHES/WARNINGS/ADVISORIES
 
 
WV...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR  
WVZ522-523-526.  
OH...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY  
MORNING FOR OHZ066-067-075-076-084.  
KY...NONE.  
VA...NONE.  
 

 
 

 
SYNOPSIS...TRM/MZ  
NEAR TERM...TRM  
SHORT TERM...MZ  
LONG TERM...MZ  
AVIATION...TRM  
 
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