740  
FXUS61 KRLX 121117  
AFDRLX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON WV  
617 AM EST TUE DEC 12 2017  
   
SYNOPSIS
 
 
STRONG UPPER TROUGH BRINGS COLD AIR AND SNOW SHOWERS TODAY.  
ANOTHER SYSTEM ARRIVES BY LATE WEEK WITH ANOTHER CHANCE FOR SNOW  
SHOWERS.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 415 AM TUESDAY...  
 
AS OF 09Z, THE COLD FRONT WAS ALMOST THROUGH THE AREA AND WILL  
LIKELY BE EAST OF THE MOUNTAINS BY DAYBREAK. LOOKING AT UPSTREAM  
OBSERVATIONS EARLY THIS MORNING, THE COLD AIR IS RUSHING IN VERY  
QUICKLY BEHIND THE FRONT AS PREVIOUSLY FORECAST. HIGH  
TEMPERATURES FOR THE DAY HAVE BEEN HIT ALREADY THIS MORNING AND  
WE CAN EXPECT OUR TEMPERATURES TO NOW CONTINUE TO DROP THROUGH  
THE DAY TODAY. RADAR IS NOT SHOWING MUCH NOW, BUT THERE HAVE  
BEEN A FEW FLAKES FALLING AT SNOWSHOE WITH THE FRONT APPROACHING,  
AND WE CAN EXPECT SNOW SHOWERS TO BECOME MORE WIDESPREAD IN THE  
MOUNTAINS IN THE NW UPSLOPE FLOW AFTER THE FRONT PASSES.  
 
ELSEWHERE, SNOW SHOWERS/SQUALLS WILL BECOME MORE WIDESPREAD BY  
LATER THIS MORNING TO EARLY THIS AFTERNOON AS DEEP UPPER TROUGH  
SINKS SOUTHWARD OVER THE AREA. DECENT FETCH ACROSS LAKE MICHIGAN  
WITH THE NW FLOW WILL ADVECT LAKE MOISTURE TO THE SE. CURRENT  
FORECAST SOUNDINGS THIS AFTERNOON INDICATE A FAIRLY SATURATED  
DENDRITIC GROWTH ZONE, AND LAPSE RATES BECOME QUITE STEEP THIS  
AFTERNOON...NOT SURPRISING WITH AN 18 DECIMETERS H500 FALL FROM  
THIS MORNING THROUGH THIS AFTERNOON WITH THE NEGATIVELY TILTED  
UPPER TROUGH.  
 
AS MENTIONED IN THE PREVIOUS FORECAST, EXPECTING TO SEE AREAS  
OF LAKE STREAMERS SET UP AND BRING SHORT/INTENSE PERIODS OF SNOW  
AT TIMES. THIS WILL LIKELY MAKE FOR INTERESTING TRAVEL TODAY,  
AS SNOW SQUALLS COULD CAUSE VERY RAPIDLY CHANGING TRAVEL  
CONDITIONS WITH AREAS OF REDUCED VISIBILITIES AND SLICK ROADS.  
 
HAVE SLIGHTLY TWEAKED SNOWFALL TOTALS OVERALL AND AS SUCH I  
DECIDED TO INCLUDE SOUTHEAST RALEIGH COUNTY INTO THE WINTER  
WEATHER ADVISORY. ALTHOUGH THEY DON'T NECESSARILY REACH SNOWFALL  
CRITERIA, THE THOUGHT IS THAT STRONG WIND GUSTS CAUSING BLOWING  
SNOW WITH REDUCED VISIBILITIES AND WIND CHILLS BELOW ZERO  
OVERNIGHT WARRANTED AN ADVISORY. ALL OTHER AREAS ARE HIGHLIGHTED  
IN THE HWO TODAY, AND WE WILL LIKELY HANDLE HEAVIER SNOW SHOWERS  
THIS AFTERNOON WITH SPECIAL WEATHER STATEMENTS.  
 
SNOW SHOWERS ACROSS THE LOWLANDS WILL WIND DOWN TONIGHT, BUT  
UPSLOPE MOUNTAIN SNOW SHOULD CONTINUE THROUGH THE OVERNIGHT  
HOURS. FORECAST ACCUMULATIONS ACROSS THE LOWLANDS WILL LIKELY BE  
SPOTTY DEPENDING ON WHERE THE HEAVIEST SQUALLS HIT, BUT  
DEFINITELY NOT UNLIKELY FOR A FEW JACKPOT AREAS THAT SEE 1 TO 2  
INCHES.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/
 
 
AS OF 233 AM TUESDAY...  
 
HIGH PRESSURE BUILDS INTO THE AREA ON WEDNESDAY BRINGING ANY  
REMAINING MOUNTAIN SNOWS TO AN END. AS THE HIGH BUILDS IN, WINDS  
SHOULD DIMINISH ALLOWING THE WIND CHILL ADVISORIES TO COME TO AN  
END AS WELL.  
 
THE DRY WEATHER DOES NOT LAST LONG. AN UPPER LEVEL TROUGH AND  
SURFACE LOW PRESSURE WILL PUSH EAST WEDNESDAY NIGHT INTO  
THURSDAY BRINGING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE  
REGION.  
 
ANOTHER UPPER LEVEL TROUGH AND SURFACE LOW WILL BRING YET  
ANOTHER PERIOD OF UNSETTLED WEATHER FROM LATE THURSDAY NIGHT  
INTO FRIDAY NIGHT.  
 
WENT WITH MODEL BLENDS FOR TEMPERATURES THROUGH THE PERIOD.  
 

 
   
LONG TERM /SATURDAY THROUGH MONDAY/
 
 
AS OF 233 AM TUESDAY...  
 
ANOTHER AREA OF HIGH PRESSURE WILL BUILD IN SATURDAY. AS A  
RESULT, DRY WEATHER IS ANTICIPATED FOR MUCH OF SATURDAY INTO  
EARLY SUNDAY. ANOTHER LOW PRESSURE SYSTEM WILL APPROACH THE AREA  
FROM THE SOUTHWEST ON SUNDAY AND THEN PUSH EAST SUNDAY NIGHT.  
EXPECT PRECIPITATION ASSOCIATED WITH THIS FEATURE TO SPREAD INTO  
THE AREA ON SUNDAY WITH PRECIPITATION CHANCES EXPECTED TO  
CONTINUE INTO MONDAY.  
 
WITH SOUTHWESTERLY WINDS IN PLACE AHEAD OF THE LOW, EXPECT  
TEMPERATURES TO REBOUND WITH DAYTIME TEMPERATURES ABOVE NORMAL  
ON SATURDAY. THE AIRMASS IMMEDIATELY BEHIND THE LOW IS NOT THAT  
COLD. SO EXPECT AFTERNOON READINGS ON SUNDAY TO BE CLOSE TO  
NORMAL.  
 

 
   
AVIATION /11Z TUESDAY THROUGH SATURDAY/
 
 
AS OF 620 AM TUESDAY...  
 
A STRONG UPPER LEVEL SYSTEM WILL BE PUSHING INTO THE REGION  
TODAY. IN THE NW FLOW, WE WILL SEE LAKE EFFECT STREAMERS OF SNOW  
SPREAD ACROSS THE AREA AND BRING PERIODS OF HEAVY SNOW. IN THE  
MOUNTAINS THE SNOW WILL BE MORE PERSISTENT AND IFR CONDITIONS  
WILL BE MORE LIKELY AT EKN AND BKW TODAY, WHILE OTHER SITES WILL  
BE MORE HIT OR MISS.  
 
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...  
 
FORECAST CONFIDENCE: MEDIUM.  
 
ALTERNATE SCENARIOS: TIMING OF SNOW SHOWERS AND DETERIORATING  
CONDITIONS ON TODAY WILL VARY FROM FORECAST. CONDITIONS MAY BE  
WORSE THAN CURRENTLY 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 12/12/17  
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 H M H M M M L H H H M M  
HTS CONSISTENCY H H H M L M M M H H M M  
BKW CONSISTENCY H H M H M L L L L L L L  
EKN CONSISTENCY H M M M L L L L L L L L  
PKB CONSISTENCY H H M M M M M H H H M M  
CKB CONSISTENCY H M M M L M M M M L L L  
 
AFTER 12Z WEDNESDAY...  
SCATTERED SNOW SHOWERS AND GUSTY WINDS WILL RESULT IN CONTINUED  
AREAS OF IFR INTO WEDNESDAY MORNING PARTICULARLY ACROSS THE  
MOUNTAINS. ANOTHER ROUND OF SNOW IS EXPECTED WEDNESDAY NIGHT AND  
THURSDAY, PARTICULARLY ACROSS THE NORTH, WITH IFR CONDITIONS  
POSSIBLE.  
 

 
   
RLX WATCHES/WARNINGS/ADVISORIES
 
 
WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ516-  
518-520-522>526.  
WIND CHILL ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST  
WEDNESDAY FOR WVZ518-520-522>526.  
OH...NONE.  
KY...NONE.  
VA...NONE.  
 

 
 

 
SYNOPSIS...JSH/MPK  
NEAR TERM...JB/MPK  
SHORT TERM...JSH  
LONG TERM...JSH  
AVIATION...MPK  
 
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