Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 080906 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 406 AM EST MON FEB 8 2016 .SYNOPSIS... COLD FRONT TODAY. UNSETTLED/COLDER TUESDAY AND WEDNESDAY UNDER LARGE MID/UPPER LEVEL LOW...WITH ROUNDS OF SNOW SHOWERS THAT LINGER THROUGH MUCH OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... UPPER LEVEL LOW CONTINUES ITS SLOW TREK...DROPPING INTO THE GREAT LAKES AND MIDDLE OHIO VALLEY. SURFACE FRONTAL SYSTEM COUNTERPART WILL TAKE A COLD FRONT THROUGH THE AREA TODAY...FOLLOWED BY A SERIES OF UPPER LEVEL VORTICITY LOBES AND TROUGH AXES WELL INTO THE SHORT TERM FORECAST PERIOD. EXPECTING A SIGNIFICANT CHANGE IN AIRMASS IN TERMS OF TEMPERATURE WITH A PROLONGED PERIOD OF BELOW FREEZING WEATHER BEGINNING TONIGHT. SHOULD SEE A SLIGHTLY UNUSUAL PATTERN FOR THE TEMPERATURES AND PRECIPITATION TYPE AS THE DAY EVOLVES. MAY SEE A LITTLE LIGHT SNOW AT FIRST GIVEN THE POTENTIAL TO WET BULB...AS DEWPOINTS RESIDE IN THE LOW TO MID 20S CURRENTLY WHILE TEMPERATURES ARE IN THE UPPER 20S TO MID 30S. SHOULD TRANSITION TO RAIN AS TEMPERATURES CLIMB TO THE UPPER 30S AND LOWER 40S OVER THE LOWLANDS...AND FALL OFF BEHIND THE FRONT THIS EVENING AND TONIGHT...CHANGING BACK TO SNOW. THE HIGHER ELEVATIONS SHOULD NOT GET ABOVE FREEZING...SO THIS SHOULD BE AN ALL SNOW EVENT FRONT THE GET GO...AND HENCE...THE ADVISORY BEGINNING AT 18Z FOR RANDOLPH AND POCAHONTAS COUNTIES. 850MB TEMPERATURES DROP HARD TONIGHT IN THE TRANSITION TO A MUCH COLDER ENVIRONMENT THAT WILL SUPPORT THE OFF AND ON SNOW SHOWERS...BRIEFLY HEAVY AT TIMES. SHOULD NOT HAVE ANY ISSUES AT THE ONSET WITH SATURATION IN THE DENDRITIC GROWTH LAYER...AND WILL SEE MODEST ACCUMULATIONS BEGINNING TONIGHT...ESPECIALLY OVER THE NORTHERN ZONES...AND IN THE NORTHEAST MOUNTAINS. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... DEEP L/W TROUGH OVER THE ERN U.S. THIS ENTIRE PERIOD SPELLS BELOW NORMAL TEMPERATURES AND SNOW SHOWERS. THE PARTY BEGINS RIGHT AT THE START OF THE PERIOD MON NT...WITH COLD ADVECTION OVERSPREADING THE AREA FROM SW TO NE...BEHIND A NW TO SE ORIENTED SFC LOW PRESSURE TROUGH EXTENDING FROM THE ERN GREAT LAKES TO THE DELMARVA PENINSULA BY 12Z TUE. OUTSIDE WIDESPREAD UPSLOPE SNOW SHOWERS...MODELS DEPICT A LAKE MI TRAJECTORY COMING ACROSS THE NRN TIER OF THE FCST AREA MON NT INTO TUE...ENHANCING LOWLAND SNOW AMOUNTS THERE VS. AREAS FARTHER S. BEYOND THAT...TOUGH TO TIME THE SMALLER SCALE FEATURES ROTATING AROUND THE EVOLVING UPPER LOW NEARBY TO THE N...BUT IT LOOKS LIKE THE GENERAL TRAJECTORIES MAY NOT CHANGE MUCH. WITH H85 TEMPERATURES DROPPING INTO THE TEENS BELOW ZERO C TUE AND SLOWLY DROPPING FURTHER BEYOND THAT...DENDRITIC CRYSTAL GROWTH IS FAVORED...RESULTING IN HIGH SNOW TO LIQUID RATIOS. FOR STARTERS...SNOW TOTALS FOR MON NT THROUGH TUE ARE CLOSE TO 12 HOUR ADVISORY CRITERIA BUT 3-5 INCHES SHORT OF WARNING CRITERIA ON A COUNTY AVERAGE BASIS THROUGHOUT THE FCST AREA. THUS NOT INTRODUCING ANY HEADLINES AT THIS TIME ALTHOUGH IT IS PLAUSIBLE ADVISORIES WILL BE NEEDED FOR THAT PERIOD...AND THEN TUE NT INTO WED LOOK TO BE NEARLY AS SNOWY WITH THE UPPER LEVEL LOW AND L/W TROUGH AXIS STILL OVER THE UPPER AND MIDDLE OHIO VALLEYS. THE LAKE MI TRAJECTORY INTO NRN PORTIONS OF THE FCST AREA MAY STILL BE THERE OR MAY BE BECOMING REESTABLISHED WED AFTERNOON. TEMPERATURES WERE LOWER THAN GUIDANCE BUT GENERALLY STAYED CLOSE TO PREVIOUS PACKAGE AND RAW GUIDANCE IN THIS ANOMALOUS PNA PATTERN...PERHAPS JUST SLOWING DOWN THE COOLING A BIT MON NT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... STILL EXPECTING SCT SNOW SHOWERS OVER THE AREA WEDNESDAY NIGHT. STREAMLINE ANALYSIS AND HYSPLIT BACKWARDS TRAJECTORY PARCELS ALONG WITH OMEGA/RH IN THE DENDRITIC GROWTH ZONE DO INDICATE SOME ENHANCEMENT FROM LAKE MICHIGAN FOR A TIME IN THE EVENING...AFFECTING SE OH AND ESPECIALLY N WV. THIS IS ENHANCED FURTHER WITH A SUBTLE VORT MAX ROUNDING THE BASE OF THE UPPER TROF. SO...HAVE KEPT SOME FAIRLY HEALTHY POPS OVER THE N DURING THE NIGHT. HOWEVER...EXPECT THIS TO BE A LOW QPF/HIGH POP SCENARIO WITH GREATEST ACCUMULATIONS WEDNESDAY NIGHT OVER THE N WV MOUNTAINS WHERE AN INCH OR TWO OF ADDITIONAL SNOW MAY FALL. THURSDAY MORNING WILL FEATURE SOME LINGERING SNOW SHOWERS AND FLURRIES...PRIMARILY WITHIN ANY LAKE MICHIGAN PLUME AS SHOWN ON GFS. H85 THERMAL TROF LINGERS IN THE VICINITY SO HARD TO SEE MUCH IN THE WAY OF IMPROVEMENT WITH THE EROSION OF THE STRATOCU AND ANY TEMPERATURE MODERATION. WE FINALLY GET SOME WAA GOING THURSDAY NIGHT WHICH SHOULD BE ENOUGH FOR SOME CLEARING AREAWIDE. AT THE SURFACE HIGH PRESSURE WILL BE BUILDING IN WHICH WILL MAKE FOR A VERY COLD NIGHT SHOULD WE INDEED LOSE THE CLOUDS AMID A FRESH SNOW PACK. SOME BELOW ZERO READINGS ARE POSSIBLE IN THE IN THE TYPICAL COLD SPOTS OF THE MOUNTAIN VALLEYS. CONFIDENCE BEGINS TO DECREASE HEADING INTO THE WEEKEND. THE GLOBAL MODELS ARE HAVING SOME ISSUES RESOLVING FEATURES AND THE OVERALL MEAN TROF OVER THE EASTERN CONUS. THUS HAVE STAYED CLOSE TO WPC WHICH FAVORED A COLDER ECMWF SOLUTION FOR THE WEEKEND AMID ANOTHER ARCTIC HAMMER DROP. NO BIG SYSTEM IS ENVISIONED OVER THE WEEKEND THOUGH. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... EXPECTING OVERALL DETERIORATING AVIATION CONDITIONS THROUGH THE TAF PERIOD...WITH A STRONG COLD FRONT PASSING THROUGH TODAY...BRINGING RAIN CHANGING TO SNOW...LOWERING CEILING...AND VISIBILITIES THAT WILL LIKELY BOUNCE IN AND OUT OF PRECIPITATION. FOR THE CEILINGS...INTRODUCE MVFR NEAR THE ONSET...BUT HAVE IFR AT SOME LOCATIONS AS THE LOWEST LEVELS SATURATE IN THE POST FRONTAL ENVIRONMENT. WITH THE VISIBILITIES...GENERALLY USE MVFR WITH THE ONSET AND IN RAIN...BUT IFR LIKELY AFTER SEVERAL HOURS OF LIGHT RAIN...AND ESPECIALLY ONCE THE TRANSITION TO LIGHT SNOW OCCURS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z TUESDAY... FORECAST CONFIDENCE...HIGH IN THE DETERIORATING TRENDS...AND MEDIUM IN THE DETAILS AND TIMING. ALTERNATE SCENARIOS: TIMING OF IFR WILL VARY. LOW LEVEL SATURATION MAY REQUIRE EARLIER ONSET OF IFR ONCE THE COLD FRONT PASSES. 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 MON 02/08/16 UTC 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20 EST 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY H H M M M L L M M M M M HTS CONSISTENCY H H M L L M M M M M M M BKW CONSISTENCY H H H M M M L L L L L M EKN CONSISTENCY H H H H H H H M H H H M PKB CONSISTENCY H H M L L L L M M M M M CKB CONSISTENCY H H H H H H H H H H M M AFTER 06Z TUESDAY... PERIODS OF IFR CONDITIONS POSSIBLE IN RAIN/SNOW SHOWERS ALL THE WAY THROUGH WEDNESDAY NIGHT...WITH THE WORST CONDITIONS EXPECTED TUESDAY MORNING THROUGH WEDNESDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST WEDNESDAY FOR WVZ005>011-013>020-024>040. WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM EST WEDNESDAY FOR WVZ046-047. OH...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST WEDNESDAY FOR OHZ066-067-075-076-083>087. KY...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST WEDNESDAY FOR KYZ101>103-105. VA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST WEDNESDAY FOR VAZ003-004. && $$ SYNOPSIS...ARJ/26 NEAR TERM...26 SHORT TERM...ARJ LONG TERM...30 AVIATION...26

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