Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 131647 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1140 AM EST SAT FEB 13 2016 .SYNOPSIS...
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HIGH PRESSURE BUILDS IN FOR OVERNIGHT. BITTER COLD AIR. STRONG WARM AIR ADVECTION SUNDAY INCREASES MOISTURE AND EVENTUALLY SNOW AT SURFACE. CONTINUED SOUTHERLY FLOW CAUSES WINTRY MIX MONDAY AND TUESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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LATE MORNING UPDATE THIS SATURDAY... COLDEST 850 MB AIR IN THE MINUS 20 TO MINUS 22C OVER US NOW. AS IS USUAL IN ARCTIC AIR...LOTS OF SUNSHINE DESPITE LINGERING FLURRIES AND SNOW SHOWERS AT 16Z OVER THE MOUNTAINS. WE STILL KEEP ELEVATIONS AOA 4 THSD FT BELOW ZERO THIS AFTERNOON. OTHERWISE READINGS ONLY CREEP UP A FEW DEGREES. CLOUDS MAY INCREASE BRIEFLY AGAIN 16Z TO 19Z BEFORE DECREASING FURTHER...BUT WAS MORE OPTIMISTIC ON CLOUDS. A FEW CLOUDS MAY LINGER TONIGHT...BUT STILL LIKE OUR FORECAST OF COLDER TEMPERATURES THAN MOST MOS...AS WINDS DIMINISH. CLOUDS THICKEN AND LOWER SUNDAY FROM SW TO NE. WHEN LIGHT SNOW REACHES THE GROUND WILL BE A TOUGH CALL. DID SLOW DOWN POPS ALONG THE ROUTE 50 CORRIDOR...IN OUR NORTHERN COUNTIES.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY/... COMPLEX SYSTEM THIS PERIOD LOOKS JUST A LITTLE COLDER. THE LOWLANDS LOOK TO GET MOST OF THEIR SNOW FROM WARM ADVECTION SUN NT INTO MON WITH HIGH END ADVISORY AMOUNTS POSSIBLE. THE NRN MOUNTAINS ALSO RECEIVE A POUNDING MON NT WHICH WOULD WARRANT WARNINGS IF CURRENT MODEL OUTPUT HOLDS UP. THE CENTRAL AND SRN MOUNTAINS COULD GET ADVISORY CRITERIA ICE AMOUNTS. GIVEN DIFFERENCES AMONG THE MODELS AND FROM RUN TO RUN...IT WAS AGREED AMONG NEIGHBORING OFFICES TO HOLD OFF ON CODING THIS UP AT THIS POINT...ESPECIALLY WITH ONGOING ADVISORIES IN THE NEAR TERM. WILL UPDATE THE HWO TO BETTER REFLECT THESE POSSIBILITIES. THE HIGH PRESSURE SYSTEM REPRESENTING THE CENTER OF THE ARCTIC AIR MASS OVERTAKING THE AREA AT THIS TIME...WILL EXIT THE AREA ON SUNDAY...AND A WARM ADVECTION / OVERRUNNING PATTERN SETS UP LATE SUNDAY THROUGH MON...IN DEEP LAYER S TO SW FLOW VEERING WITH HEIGHT...AHEAD OF UPPER LEVEL S/W TROUGHS APPROACHING FROM THE W. THE FIRST ONE MOVES THROUGH THE GREAT LAKES AND UPPER OHIO VALLEYS SUN NT...WITH INCREASING MOISTURE...CLOUD AND PRECIPITATION OVERRUNNING THE AREA AS A RESULT. WITH THE ANTECEDENT ARCTIC AIR...THE COLUMN REMAINS PROGGED TO REMAIN COLD ENOUGH FOR SNOW THROUGHOUT THE AREA SUN NT...LEADING TO INITIAL ACCUMULATIONS OF GENERALLY 1 TO 3 INCHES LATE SUN AFTERNOON THROUGH SUN NT...THE HIGHEST AMOUNTS S. ONGOING WARM ADVECTION MON EVENTUALLY BRINGS THE COLUMN ABOVE FREEZING FROM H85 DOWN SOMETIME MON AFTERNOON THROUGHOUT MUCH OF THE LOWLANDS. THIS LIMITS SNOWFALL ACCUMULATIONS TO AN INCH OR LESS ACROSS THE LOWLANDS...WHILE ANOTHER 1 TO 3 INCHES ARE POSSIBLE OVER THE NRN MOUNTAINS. A COLD LAYER IS PROGGED TO LINGER BETWEEN H85 AND THE SFC FOR A TIME MON...LEADING TO A PERIOD OF SLEET AND / OR FREEZING RAIN IN THE TRANSITION. THE SECOND S/W TROUGH TRACKS FARTHER S THAN THE FIRST...AS A L/W TROUGH OVER THE ERN U.S BECOMES REESTABLISHED. ONE DIFFERENCE FROM PREVIOUS RUNS IS THAT SFC LOW PRESSURE CENTER GENERATED BY THIS S/W APPEARS TO BE MORE OF A FLAT WAVE AND FARTHER S. AMIDST THE ESTABLISHMENT OF THE L/W TROUGH IN THE E...THIS AMOUNTS TO A COLDER SOLN COMPARED WITH PREVIOUS RUNS...A TREND THAT MAY BE INTERESTING TO FOLLOW. THE S/W APPROACHES MON AND CROSSES MON NT...AS THE SFC WAVE RIDES NEWD JUST E OF THE CENTRAL APPALACHIANS MON NT. ONE LIMITING FACTOR IN A TRANSITION BACK TO SNOW ACROSS THE LOWLANDS MON NT IS THE LACK OF FRESH COLD AIR ARRIVING BEHIND THE SYSTEM. HOWEVER...IT MAY NOT TAKE TOO MUCH FURTHER A TREND TOWARD COLDER TO IMPACT THE PRECIPITATION TYPE FCST FOR MON NT GIVEN THE MARGINAL NATURE OF THE COLUMN TEMPERATURES CURRENTLY PROGGED. AS IS...THE TRACK OF THE SYSTEM AND THE RETURN OF THE COLD AIR ALOFT COULD RESULT IN THE HIGHER ELEVATIONS IN THE MOUNTAINS OF NRN WV GETTING CLOCKED WITH SIGNIFICANT SNOWFALL MON NT. ANOTHER FACTOR IN THIS COMPLEX EVENT IS THE COLD AIR DAMMING IN THE TYPICAL E OF THE MOUNTAINS WEDGE AREA...WHICH COULD RESULT IN AT LEAST ADVISORY CRITERIA ICE ACROSS THE CENTRAL AND SRN MOUNTAINS OF WV AND DOWN INTO SW VA...MAINLY THE ERN SLOPES OR ERN PORTIONS OF THE ERN FLANK COUNTIES OF THE FCST AREA. THE PRECIPITATION WINDS DOWN LATE MON NT INTO TUE AS THE SYSTEM PULLS OUT...ENDING AS RAIN OR DRIZZLE ACROSS THE LOWLANDS TUE AS WE LOSE THE UPPER LEVEL MOISTURE AND WITH IT THE CRYSTAL GROWTH ZONE. USED A NAM AND CONSENSUS BLEND FOR SFC TEMPERATURES AND THE NAM FOR TEMPERATURES ALOFT...AND A NAM/GFS/ECMWF/WPC BLEND FOR QPF. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... STILL LOTS OF UNCERTAINTY CONCERNING EARLY NEXT WEEK STORM...AND THUS...LOW CONFIDENCE IN THE FORECAST. GFS AND NAM SEEMS TO BE TRENDING COLDER/MORE EASTERLY WITH THE LOW EARLY NEXT WEEK...WHILE THE ECMWF CONTINUES TO SHOW A WARMER/MORE WESTERLY TRACK WITH THE SYSTEM. THE UNCERTAINTY IN THE PATH...OF COURSE...CREATES CONUNDRUMS IN THE PRECIPITATION TYPE AND AMOUNT FORECAST. REGARDLESS OF WHICH MODEL...GOOD 40+KT LLJ WILL AID IN HIGH MOISTURE TRANSPORT INTO THE REGION. ONE THING THAT DOES LOOK FAIRLY CERTAIN...IS MOUNTAINOUS COUNTIES SHOULD GET DECENT ACCUMULATIONS...WITH LOWLANDS LESS CERTAIN...AS MAY TRANSITION TO A RAIN SNOW MIX OR EVEN ALL RAIN MONDAY AFTERNOON AND NIGHT...BEFORE TRANSITIONING TO ALL SNOW...THEN POSSIBLY BACK TO A MIX OR ALL RAIN TUESDAY AFTERNOON. SOUTHEAST OHIO ZONES ARE ALSO QUITE UNCERTAIN...AS DEPENDING ON THE PATH OF THE SYSTEM...THERE MAY BE A SHARP GRADIENT...WITH THE POSSIBILITY THAT SOUTHEAST OHIO ZONES COULD SEE LITTLE TO NO PRECIPITATION. IN ADDITION...IF THE STORM TAKES A MORE WESTERLY TRACK...MAY EVEN SEE PERIODS OF A WINTRY MIX INCLUDING PERIODS OF SLEET ACROSS THE AREA PARTICULARLY MONDAY NIGHT. SO ALL IN ALL...STILL LOTS OF UNCERTAINTY...BUT WILL START HIGHLIGHTING THIS SYSTEM IN THE HWO. IN ADDITION...ANY SNOW THAT OCCURS...WILL BE A HEAVY WET SNOW. IN ADDITION TO THE WINTRY PRECIPITATION...EXPECTING QPF OF OVER AN INCH ACROSS THE MOUNTAINS...AND UP TO AN INCH ACROSS THE LOWLANDS. THIS...PARTICULARLY IF QUITE A BIT OF IT FALLS AS RAIN...COULD LEAD TO RISES ON AREA STREAMS AND CREEKS...AND POTENTIALLY LEAD TO STRONG RISES ON THE MAIN STEM RIVERS NEXT WEEK. THIS WILL NEED TO BE CLOSELY MONITORED. STAY TUNED TO THE LATEST FORECAST. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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ARCTIC FRONT NOW CROSSING THE MOUNTAINS AS OF 06Z WITH A BAND OF SQUALLS...TEMPORARILY DROPPING MOUNTAIN TERMINALS INTO IFR VSBY/MVFR ALONG WITH GUSTY WINDS TO 35 KTS. BEHIND THIS...GENERALLY VFR CONDITIONS WITH OCCASIONAL DROPS INTO MVFR WITH ANY PASSING SHSN WITH MAINLY MVFR SHSN CONTINUING THRU 12Z. GUSTY WINDS 20 TO 30 KTS WILL CONTINUE...WITH THE HIGHEST GUSTS FOR THE MOUNTAIN TERMINALS. AFTER 12Z...MAINLY SCT/BKN VFR STRATOCU WITH OCCASIONAL MOUNTAIN FLURRIES. WINDS WILL GRADUALLY DIMINISH...BUT STILL LOOKING AT 15 TO 20 KTS. HIGH PRESSURE WILL BUILD IN TONIGHT WHICH WILL ALLOW WINDS TO FINALLY SUBSIDE. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: MEDIUM ALTERNATE SCENARIOS: UPSLOPE SNOW SHOWERS THIS MORNING MAY LINGER A BIT LONGER IN THE MOUNTAINS. 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 15 16 17 18 19 20 21 22 23 00 01 02 EST 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 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 M M M M M M M M M M H H EKN CONSISTENCY M M M M M M M M M M M H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY M M H H H H H H H H H H AFTER 18Z SUNDAY... IFR CONDITIONS POSSIBLE IN LIGHT SNOW SUNDAY NIGHT AND MONDAY...TRANSITIONING TO A MIXED PRECIPITATION EVENT FOR TUESDAY.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR WVZ032-035>040- 046-047. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/30 NEAR TERM...KTB SHORT TERM...TRM LONG TERM...SL AVIATION...30

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