Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 090617 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 117 AM EST TUE FEB 9 2016 .SYNOPSIS...
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ARCTIC FRONT CROSSES OVERNIGHT. UNSETTLED/COLDER IN ITS WAKE TUESDAY AND WEDNESDAY UNDER LARGE MID/UPPER LEVEL LOW...WITH ROUNDS OF SNOW SHOWERS THAT LINGER THROUGH MUCH OF THE WEEK.
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&& .NEAR TERM /THROUGH TODAY/...
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115 AM UPDATE... SNOW AMOUNTS MAY PUSH HIGH END OF ADV CRIT IN BAND OF SNOW JUST N OF UPPER LEVEL VORT LOBE ROTATING UP THROUGH THE MIDDLE OHIO VALLEY ABOUT UPPER LEVEL LOW OVER NRN OHIO. MADE POP ADJUSTMENTS FOR THAT ALONG WITH OTHER ADJUSTMENTS TO FINE TUNE WHEN AND WHERE THE SNOW SHOWERS WILL BE MOST NUMEROUS. MESOSCALE UPDATE... 700 PM UPDATE... TRACKING A POTENT LINE OF SQUALLS MOVING THRU SE OH AND INTO N WV AT THIS HR. EXPECT BRIEF WHITEOUT CONDITIONS AND GUSTY WINDS AS THIS MOVES THRU. THIS HAS HAD A HISTORY OF PUTTING DOWN A SLUSHY HALF INCH TO INCH WITH EVEN SOME EMBEDDED LIGHTNING OBSERVED. THE TEMP HERE AT THE OFFICE DROPPED FROM 42 TO 33 IN 15 MINUTES TIME AS THE SQUALL WENT THRU AS HAS HELD NEARLY STEADY SINCE. QUICK ON ITS HEELS IS ANOTHER POTENT LINE OF SQUALLS MOVING THRU E KY ATTM. THIS WILL TRACK INTO THE AREA AS THE EVENING PROGRESSES WITH AGAIN BRIEF WHITEOUT CONDITIONS. BEHIND THAT WE WAIT FOR THE TRUE CAA TO BE USHERED IN BY A POTENT S/W TROF AND FRONT AFTER MIDNIGHT. HAVE REWORKED HOURLY GRIDS INCLUDING POP/TEMP/WX TO REFLECT RADAR TRENDS. ACCUMULATIONS WERE REWORKED TO ACCOUNT FOR THE CURRENT SQUALL MOVING THRU AS WELL AS OVERNIGHT PERIOD USING LATEST NAM/HRRR/GFS. AM CONCERNED AMOUNTS MAY STILL BE TOO LOW OVER PORTIONS OF SE OH AND N WV LOWLANDS THRU TOMORROW GIVEN AN EMERGING CONSENSUS ON THE PROLONGED LOCATION OF BETTER FORCING. WILL WAIT FOR 00Z NEAR TERM MODELS TO ROLL IN BEFORE MAKING ANY MEANINGFUL CHANGES TO ACCUMULATIONS FOR THOSE AREAS. PREVIOUS DISCUSSION BELOW... OTHER THAN ADJUSTING THE TIME PERIODS FOR THE CHANGE TO ALL SNOW SHOWERS IN THE LOW LANDS TONIGHT...AND THE MOST LIKELY TIME PERIODS THEREAFTER FOR SNOW SHOWERS AND THUS ACCUMULATIONS...NOT TOO MUCH CHANGE FROM PREVIOUS FORECAST WHEN IT COMES TO FINAL SNOW ACCUMULATIONS THROUGH THE DAY TUESDAY. ONE THING IS TO SLOW THE ARCTIC FRONT TONIGHT JUST A BIT PER MODEL CONSENSUS. AHEAD OF THIS FRONT...LOW LEVEL SOUTHWESTERLY FLOW AND EVEN PEEKS OF SUNSHINE HAVE ALLOWED TEMPERATURES TO REACH THE 40S IN MANY LOW LAND SPOTS...BUT WITH AIR ALOFT QUITE COLD...STILL WET SNOW OUTSIDE THE MOUNTAINS MAY BE MIXED IN WITH THE RAIN SHOWERS THIS AFTERNOON...AND IN THE MOUNTAINS MAINLY SNOW SHOWERS. NEVERTHELESS...SNOW ACCUMULATIONS THIS AFTERNOON AND EVENING MAINLY CONFINED TO THE HIGHER ELEVATIONS OF THE MOUNTAINS. FOR TONIGHT...HAVE MINOR SNOW ACCUMULATIONS IN THE LOW LANDS GIVEN THE DELAY OF THE COLDER AIR AND NIGHT TIME LOWS NOT THAT FAR BELOW FREEZING...GENERALLY AROUND AN INCH OR SO...WITH 1 TO 4 INCHES IN THE MOUNTAINS. FOR TUESDAY...POST FRONTAL SNOW SHOWERS WIDESPREAD WITH UPPER DISTURBANCES ROTATING AROUND THE MEAN UPPER TROUGH TO OUR WEST. MODELS INDICATE THAT THE NORTHERN PORTIONS OF THE AREA WILL THE MAIN TARGET FOR THE HIGHEST AMOUNTS...ESPECIALLY NORTHERN MOUNTAINS...WHERE DAY TIME ACCUMULATIONS WILL RANGE FROM 1 TO 2INCHES LOW LANDS TO 2 TO 4 INCHES NORTHERN MOUNTAINS. THIS WILL MAINLY BE IN THE MORNING BEFORE THE STRENGTHENING FEBRUARY SUN TAKES EFFECT. LOOK FOR HIGHS TUESDAY TO STAY BELOW FREEZING.
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&& .SHORT TERM /TONIGHT THROUGH THURSDAY/... LARGE L/W UPPER LEVEL TROUGH OVER THE AREA TUE NT AND WED...STARTS TO LIFT OUT OF THE AREA WED NT AND THU. ONE IN A SERIES OF VORT LOBES ROTATING AROUND THE BASE OF THE TROUGH WILL BE EXITING TUE NT...AND A MORE W THAN NW LOW LEVEL FLOW WILL KEEP THE LAKE MI PLUME N OF THE FCST AREA. THIS MAY RESULT IN A LULL IN SNOW SHOWERS OVER THE MIDDLE OHO VALLEY. NEXT S/W IS PROGGED TO BE NEGATIVELY TILTED AND ESSENTIALLY BECOME THE MAIN L/W TROUGH AXIS AS IT CROSSES THE FCST AREA WED INTO WED NT. WITH DIURNAL HEATING...SNOW SHOWERS APPEAR LIKELY THROUGHOUT MUCH OF THE FCST AREA WED. AS THE LOW LEVEL FLOW VEERS A BIT MORE TO THE NW LATE WED INTO WED NT...THE LAKE MI PLUME MAY EASE BACK SWD INTO NRN PORTIONS OF THE FCST AREA...BEFORE THE ENTIRE PATTERN STARTS TO DRY OUT WED NT AND THU...AS UPPER HEIGHTS START TO RISE AND THE H85 COLD TROUGH STARTS TO LIFT OUT. THERE ARE LIKELY TO BE ADDITIONAL FINER DETAILS IN THE MIX AS THIS ALL PLAYS OUT...BUT UPSLOPE SNOW SHOWERS IN AND NEAR THE MOUNTAINS WILL BE ESSENTIALLY ONGOING WELL INTO WED NT BEFORE STARTING TO TAPER OFF. STILL FIGURING ON AN INCH OR TWO PER 12 HOUR PERIOD FOR THE LOWLANDS AND 2 TO 3 IN THE MOUNTAINS TUE NT...GRADUALLY WANING THEREAFTER. WITH 24 HOUR SNOW AMOUNTS STILL WELL BELOW WARNING CRITERIA...THE AREA WIDE ADVISORY LOOKS GOOD THOUGH COULD SEE HAVING TO EVENTUALLY EXTEND IT IN THE MOUNTAINS THROUGH AT LEAST WED. THAT WILL LIKELY BE A CASE OF DWINDLING AMOUNTS IN A CONTINUATION OF THE EXISTING ENCROACHMENT. NO MAJOR CHANGES TO TEMPERATURES IN THIS BELOW NORMAL PATTERN...BLENDED IN BIAS CORRECTED GUIDANCE FOR LOWS AND BLENDED IN RAW NAM OUTPUT FOR HIGHS. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... SOME LINGERING SNOW SHOWERS ACROSS THE NORTHERN MOUNTAINOUS COUNTIES TO START THE PERIOD. THIS IS DUE TO NW FLOW ALOFT. HOWEVER...A SURFACE HIGH PRESSURE IS NOSING IN SO IT WILL BE A TIGHTROPE WALK BETWEEN NORTHWEST FLOW AND DEPARTING MOISTURE. SOME UNCERTAINTY ON POPS THIS WEEKEND...AS ECMWF SLIDES A SURFACE LOW TO OUR NORTH DRIVING A COLD FRONT THROUGH. HOWEVER...THE GFS IS MUSH LESS ROBUST WITH THIS SYSTEM...WITH A WEAKER FRONT AND LESS MOISTURE. STAYED IN CHANCE POPS FOR NOW. EITHER WAY...REINFORCING SHOT OF COLD AIR ARRIVES WITH THIS FRONT SETTING UP A VERY CHILLY WEEKEND. STILL BREEZY DURING THIS TIME AS THE NEXT HIGH PRESSURE DOES NOT NOSE IN UNTIL DURING THE DAY SUNDAY. WILL MENTION POTENTIAL FOR WIND CHILL ADVISORY IN THE HWO. MOST WIDESPREAD ISSUE LOOKS TO BE SATURDAY NIGHT...BUT SHOULD HIGH ARRIVE SOONER THAN FORECAST...WIND COULD SHUT DOWN EARLY. ANOTHER SYSTEM LOOKS TO IMPACT THE END OF THE PERIOD...BUT WITH FAIRLY DRASTIC DIFFERENCES IN THE MODELS STUCK CLOSE TO WPC FOR NOW. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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A SOMEWHAT LOW CONFIDENCE FCST DURING THE 24 HOUR TAF PERIOD DUE TO THE VARIABILITY OF CONDITIONS WITH NUMEROUS SNOW SHOWERS ABOUT. A VERY COLD AIR MASS OVERTAKES THE AREA OVERNIGHT...AS AN UPPER LEVEL LOW SETTLES IN OVER THE UPPER OHIO VALLEY. THIS WILL KEEP SNOW SHOWERS...AND ASSOCIATED IFR CONDITIONS...MOST FREQUENT ACROSS THE MIDDLE OHIO VALLEY AND NRN WV ALTHOUGH...BECAUSE THIS IS AN UPSLOPE PATTERN...FREQUENT MVFR CONDITIONS WITH IFR AT TIMES CAN BE EXPECTED DOWN THE WV MOUNTAINS. THIS LEAVES ERN KY AND SRN WV WITH VFR VSBY MUCH OF THE TIME...BUT ANY SNOW SHOWER OR BAND CAN BRING A BRIEF PERIOD OF IFR. EVEN THERE...MVFR CIGS WILL BE PERSISTENT...PERHAPS LIFTING TO MVFR AT TIMES TUE AFTERNOON. SFC FLOW WILL BE MAINLY FROM THE W...AND BE GUSTY AT TIMES...MAINLY DURING THE DAY ON TUE. HOWEVER...WINDS WERE GUSTY AT HTS AS OF 06Z...JUST BEHIND THE ARCTIC FRONT...AND BRIEF GUSTY WINDS ARE LIKELY TO PROGRESS NEWD ACROSS WV THROUGH EARLY TUE MORNING...AS THE ARCTIC FRONT MOVES FROM SW TO NE THROUGH THE STATE. FLOW ALOFT WILL BE LIGHT TO MODERATE W. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE...LOW ALTERNATE SCENARIOS: TIMING AND EXTENT OF IFR WILL VARY IN SNOW SHOWERS OVERNIGHT AND ESPECIALLY ON TUE. 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 02/09/16 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY M L L L L L L M M M M M HTS CONSISTENCY L L M M M M M M M M M H BKW CONSISTENCY M M L L L L M M M M M M EKN CONSISTENCY M L L L L L L M M M M M PKB CONSISTENCY M M L L L L L L L L L L CKB CONSISTENCY M M L L L L L L M M M M AFTER 06Z WEDNESDAY... PERIODS OF IFR CONDITIONS IN SNOW SHOWERS ALL THE WAY THROUGH WEDNESDAY NIGHT...ESPECIALLY NORTH AND EAST PORTIONS OF AREA.
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&& .RLX WATCHES/WARNINGS/ADVISORIES...
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WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ005>011-013>020-024>040-046-047. OH...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR OHZ066- 067-075-076-083>087. KY...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR KYZ101>103-105. VA...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR VAZ003- 004.
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&& $$ SYNOPSIS...TRM/JMV/MZ NEAR TERM...TRM/JMV/30 SHORT TERM...TRM LONG TERM...MZ AVIATION...TRM

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