Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 151043 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 543 AM EST MON DEC 15 2014 .SYNOPSIS... SHOWERS TONIGHT AHEAD OF A TUESDAY COLD FRONT. ANOTHER LOW APPROACHES FRIDAY INTO SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... UPDATE... NO CHANGES TO THE FORECAST PACKAGE THIS MORNING. PREVIOUS DISCUSSION... WELL ADVERTISED DEMISE OF THE SUBSIDENCE INVERSION THAT HAS KEPT THE CWA CLOUDY WITH INTERMITTENT MIST/FOG/DRIZZLE WILL OCCUR WITH BOUNDARY LAYER FLOW TURNING SOUTHEASTERLY. THIS WILL BE A DRY FLOW AND WILL ALLOW FURTHER MIXING TO TAKE PLACE WITH CLEARER CONDITIONS THIS AFTERNOON. NO DRASTIC TIMING CHANGES IN THE TONIGHT FORECAST WITH AN INITIAL BAND OF FRONTOGENESIS AHEAD OF THE COLD FRONT ITSELF ARRIVING IN THE NORTHEAST KENTUCKY ZONES JUST AFTER 00Z TONIGHT. SECOND BAND ARRIVES AROUND 09Z...BUT NEITHER OF THESE ARE ASSOCIATED WITH THE COLD FRONT ITSELF WHICH WILL BE A SHORT TERM FORECAST FEATURE. DID OPT TO REMOVE THE THUNDER TONIGHT WITH UNIMPRESSIVE SPEED SHEAR AND LIFTED INDICES DOWN IN THE 2-3 RANGE. CANNOT SAY THERE WILL NOT BE A VERY ISOLATED LIGHTNING STRIKE HERE OR THERE...BUT THINK THIS DOES NOT WARRANT THE MENTION OF THUNDER IN THE GRIDS. SPC DOES HAVE THE GENERAL THUNDERSTORM OUTLOOK CLIPPING NORTHEAST KENTUCKY. FOR TEMPERATURES...HUGGED THE LAV GUIDANCE WHICH HAS PERFORMED WELL OF LATE FOR THE MAX TEMPERATURES TODAY IN THE WARM AIR ADVECTION WITH THE APPROACHING SYSTEM...AND WENT ABOVE GUIDANCE TONIGHT AS MOS NUMBERS TRY TO DIURNALLY DROP THEM TOO MUCH IN WARM ADVECTION FLOWS. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... CONTRARY TO THE PAST SEVERAL DAYS OF STAGNANT WEATHER...THE PATTERN ACROSS THE LOWER 48 STATES BECOMES PROGRESSIVE. A SERIES OF SOUTHERN STREAM SYSTEMS OFF THE PACIFIC COAST MARCH ACROSS THE NATION...TO THE SOUTH OF A BLOCKY PATTERN ACROSS CANADA. WITH THE REALLY COLD AIR BOTTLED UP IN CANADA...WE JUST LOOK FOR NEAR SEASONABLE TEMPERATURES BEHIND THESE SOUTHERN STREAM SYSTEMS. THE SYSTEM IN PROGRESS TUESDAY LIFTS UP INTO THE GREAT LAKES AND SWINGS A COLD FRONT ACROSS DURING TUESDAY. NOT MUCH DIFFERENCE SEEN IN THE MODELS...SO THE GFS IS USED FOR DETAILS. RAIN SHOWERS WILL ACCOMPANY THE FRONT WITH INITIALLY MILD TEMPERATURES IN THE 50S AHEAD OF THE FRONT. THUNDER CANNOT BE RULED OUT BUT INSTABILITY IS RATHER MEAGER SO WILL LEAVE OUT OF FORECAST FOR NOW. BEHIND THE FRONT...IT TAKES A WHILE FOR THE COLD AIR TO COME IN TUESDAY NIGHT...ALMOST A SECONDARY FRONT DEPICTED. SO MODELS CONTINUE POST FRONTAL RAIN SHOWERS INTO TUESDAY NIGHT AND EARLY WEDNESDAY... FINALLY CHANGING TO SCATTERED SNOW SHOWERS LATER TUESDAY NIGHT IN THE HIGHER MOUNTAIN ELEVATIONS WITH LITTLE ACCUMULATION. MODELS IN BETTER AGREEMENT IN DRYING THINGS OUT IN THE LOW LANDS LATER TUESDAY NIGHT AS CANADIAN HIGH PRESSURE BUILDS IN. LINGERING MAINLY NORTHERN MOUNTAIN SNOW SHOWERS WEDNESDAY MORNING WILL DRY UP AS THE HIGH CONTINUES TO BUILD IN...AGAIN WITH LITTLE SNOW ACCUMULATION. MODELS KEEP THE NEXT SOUTHERN STREAM SYSTEM SOUTH OF THE AREA THURSDAY...SO LOOK FOR DRY WEATHER THERE. AS MENTIONED EARLIER...TEMPERATURES BEHIND THE TUESDAY SYSTEM WILL BE NEAR SEASONABLE LEVELS FOR WEDNESDAY AND THURSDAY. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... THE PERIOD STARTS WITH HORIZONTAL FLOW ALOFT. H850 FREEZING LINE LIES SOUTH OF THE AREA WHILE THE MINUS 5C DEGREES ACROSS OUR NORTHERN BORDER THROUGH 12Z WEDNESDAY NIGHT. THIS TRANSLATES IN TO MAINLY DRY WEATHER WILL COOL NIGHTS AND SEASONAL AFTERNOONS THROUGH THURSDAY NIGHT. THE LOW PRESSURE SYSTEM LIFTS NORTHEAST ACROSS TN AND KY INTO WV...TO BRING PERIODS OF RAIN DURING THE AFTERNOONS FRIDAY AND SATURDAY...TRANSITIONING INTO WINTRY MIX OR SNOW FRIDAY NIGHT..AS THEY SPREAD FROM SOUTH TO NORTH. BOTH THE GFS AND ECMWF SHOW THE SAME TIMING IN THEIR QPF FIELDS. ALTHOUGH THE GFS TAKES THE LOW PRESSURE OVER THE OH VALLEY MOVING NORTHEAST INTO NORTHERN WV...WHILE THE ECMWF TRAJECTORY IS FURTHER SOUTH AND EAST INTO SATURDAY NIGHT. HOWEVER...THE ECMWF BRINGS STRONGER FORCING WITH A NEGATIVELY TILTED TROF AT H500 THAN THE GFS AND CMC FOR SATURDAY. KEPT LIKELY POPS ACROSS THE SOUTH AND CENTRAL WV...AND EASTERN MOUNTAINS THROUGH SATURDAY EVENING. WENT WITH A BLEND OF THE ECMWF AD HPC GUIDANCE FOR SEASONAL TEMPERATURES THROUGH THE PERIOD. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... EXPECT IMPROVING CONDITIONS THROUGH THE MORNING WITH VFR BY 20Z TODAY UNDER LIGHT SOUTHEASTERLY SURFACE FLOW. CLOUDS THICKEN WITH BANDS OF SHOWERS ARRIVING AFTER 03Z TONIGHT...FIRST REACHING HTS AND PKB AND PUSHING EASTWARD THROUGH THE NIGHT. SHOWER INTENSITY IS NOT EXPECTED TO BE STRONG...DO NOT FEEL IFR VISIBILITIES IN THE RAIN WILL NOT BE AN ISSUE. KEEP CEILINGS AND VISIBILITIES MVFR IN THESE SHOWERS. IFR IS POSSIBLE IN THE MOUNTAINS IN LOW CLOUDS AND -SHRA/BR...BUT NOT AT ANY OF THE TERMINALS KEEPING IT OUT OF EKN AND BKW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z TUESDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF VFR THIS MORNING MAY VARY SLIGHTLY. 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 12/15/14 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 CRW CONSISTENCY H H H H M M M M M M H H HTS CONSISTENCY H H H H H H M M M M H H BKW CONSISTENCY H H H M L L M M M M H H EKN CONSISTENCY L L M M L L L M H M H H PKB CONSISTENCY H H H H H H H M M M L L CKB CONSISTENCY M M M M M M M L H H L H AFTER 12Z TUESDAY... IFR POSSIBLE IN CLOUDS IN THE MOUNTAINS WEDNESDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/26 NEAR TERM...26 SHORT TERM...JMV LONG TERM...ARJ AVIATION...26

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