874 FXUS61 KRLX 022022 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 422 PM EDT FRI NOV 2 2012 .SYNOPSIS... SOME LIGHT PRECIPITATION COULD LINGER IN THE MOUNTAINS TONIGHT. A LOW PRESSURE CENTER PASSES TO THE SOUTH LATE SATURDAY AND SATURDAY NIGHT. A SYSTEM PASSES SOUTH AND EAST OF THE REGION FOR MID WEEK. && .NEAR TERM /THROUGH SATURDAY/... AT THE BEGINNING OF THE PERIOD THE UPPER 500MB LOW PROGGED TO BE LOCATED OFF THE SOUTHERN NEW ENGLAND COAST WITH NW FLOW ALOFT OVER THE AREA. AT THE SURFACE...HIGH PRESSURE WILL BE NOSING IN FROM THE NORTHWEST. GOOD FORCING FOR SUBSIDENCE WILL CONTINUE OVER THE AREA TONIGHT ON THE BACKSIDE OF THE UPPER LOW. DESPITE THIS...WILL RAMP UP POPS AGAIN TO LOW/MID CHANCE DURING THE OVERNIGHT/EARLY MORNING HOURS IN THE EASTERN HIGH TERRAIN MAINLY WEBSTER COUNTY AND POINTS NORTHEAST WITH FAVORABLE UPSLOPE CONDITIONS AND TRAPPED LLVL MOISTURE IN PLACE. DO HAVE A CONCERN HOWEVER WITH FREEZING DRIZZLE/MIST IN THOSE AREAS. NAM/GFS/SREF SOUNDINGS ARE ALL DRY AT -10C WITH GOOD SATURATION ONLY EXTENDING TO ABOUT -7C TO -8C AND SFC TEMPS WELL BELOW FREEZING. TOUGH CALL ON THIS REGARDING PRECIP TYPE HOWEVER AS OFTENTIMES IT SEEMS SOUNDINGS IN THIS AREA WOULD INDICATE FREEZING DRIZZLE YET SNOW IS STILL THE RESULT. QPF AMOUNTS ARE IN THE TWO TO FIVE HUNDREDTHS ROUGHLY. WILL LEAVE ANY ICE ACCUM OUT OF GRIDS FOR NOW AND LET EVENING SHIFT TAKE ANOTHER LOOK WITH SUBSEQUENT DATA. PRECIP SHOULD QUICKLY WIND DOWN DURING THE MORNING HOURS ACROSS THE HIGH TERRAIN. HEIGHTS INITIALLY RISE DURING THE MORNING HOURS AS UPPER LOW CONTINUES AWAY FROM AREA BUT ANOTHER S/W TROUGH DIGGING THROUGH THE CENTRAL MISS VALLEY ESSENTIALLY TURNING THE FLOW FROM NW DURING THE MORNING TO ZONAL BY END OF PERIOD. A WARM FRONT WILL EXTEND EASTWARD FROM SFC LOW OVER WEST/CENTRAL TENN TO AROUND THE NC/VA BORDER BY LATE AFT SATURDAY. SOME WEAK ISENTROPIC LIFT IS NOTED ON 300K-305K SFCS WELL ABOVE AGL AND THE SOUNDING IS VERY WEAKLY CONVECTIVE. BUT AS PREV FCST NOTED...MUCH OF THE FORCING IS FRONTOGENETIC IN NATURE AND FLOW AT H85 AND H7 ESSENTIALLY PARALLEL TO WARM FRONT...SO NOT REALLY AN OVERRUNNING SCENARIO. ELECTED TO SLOW DOWN POPS JUST A TAD BUT PREV FCST STILL HAD A GENERAL GOOD HANDLE ON PRECIP MOVING INTO THE SW ZONES BY END OF PERIOD. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... LOW PRESSURE PASSES S OF THE AREA THIS WEEKEND. ASSOCIATED WARM ADVECTION AND ISENTROPIC LIFT SPREADS PRECIPITATION INTO SOUTHERN PORTION OF THE AREA LATE SAT OR SAT EVENING DEPENDING UPON HOW LONG IT TAKES TO MOISTEN THE LOW LEVELS. EXPECT PRECIPITATION TO BE LIGHT GIVEN VERY ACUTE ANGLE ON PRESSURE ADVECTION ON THE 295 AND 300 K ISENTROPIC SURFACES. MAINLY A RAIN EVENT GIVEN THERMAL FIELDS. EVEN WHERE NEAR 0C AT H85...THERE IS NO MECHANISM TO GET SURFACE TEMPERATURES DOWN TO FREEZING ACROSS LOWLANDS. SOME SNOW IS POSSIBLE HIGH TERRAIN OF CENTRAL MOUNTAINS SAT NT BUT HAVE LOW CHANCE THERE ON NORTHERN EDGE OF SYSTEM. SYSTEM PULLS AWAY SUN BUT UPPER LEVEL S/W TROUGH WILL LIKELY KEEP SOME CLOUDS AROUND. THIS FEATURE EXITS FIRST THING MON MORNING...ALLOWING HIGH PRESSURE TO PROVIDE FOR A NICE START TO THE NEW WORK WEEK. WITH PRECIPITATION HYDROLOGICALLY INSIGNIFICANT...LOWS IN THE 20S TO AROUND FREEZING AND HIGHS IN THE 40S WHERE THE HIGH TERRAIN SNOW PACK IS...THE SLOW MELT CONTINUES...WITH NOTHING MORE THAN LOCALIZED SMALL STREAM AND CREEK ISSUES WHERE STORM DEBRIS CREATES BLOCKAGES. IT LOOKS LIKE SWE VALUES IN THE SNOW PACK ARE DOWN TO THE TWO TO FOUR INCH RANGE. BLENDED IN BIAS CORRECTED ADJMET ON TEMPERATURES EARLY ON AND THEN BIAS CORRECTED CONSALL - OVERALL NO MAJOR CHANGES INVOLVED. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... USED A BLEND OF THE ECMWF AND ECMWF ENSEMBLE MEAN FOR THIS PERIOD. THIS WOULD HAVE A STORM SYSTEM SOUTH AND EAST OF THE REGION POSSIBLY GRAZING THE AREA FOR MID WEEK. A WARM FRONT WOULD THEN PUSH NORTHWARD TOWARD THE END OF THE WEEK. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... 18Z FRIDAY THRU 18Z SATURDAY...GENERAL VFR CONDITIONS EXPECTED ACROSS THE AREA FOR THE VALID PERIOD. THE ONLY EXCEPTION TO THIS WILL BE EKN...WHERE UPSLOPE FLOW AND TRAPPED LLVL MOISTURE SHOULD BE ENOUGH TO WRING OUT A SOLID MVFR/IFR CLOUD DECK WITH SOME LIGHT MIXED PRECIP IN THE AREA. THIS SHOULD DISSIPATE DURING THE MORNING HOURS. OTHERWISE...A WEST/NORTHWEST WIND WILL CONTINUE THROUGH THE PERIOD AROUND 5 TO 10KTS OVERNIGHT...WITH GUSTS TO AROUND THE 15-20KT RANGE BOTH THIS AFTERNOON AND LATE MORNING SAT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF CIG HEIGHTS AND PRECIP CONDITIONS AT EKN MAY VARY. 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 20 21 22 23 00 01 02 03 04 05 06 07 EDT 1HRLY 16 17 18 19 20 21 22 23 00 01 02 03 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 H H H H H H H H H H H H EKN CONSISTENCY H H H H H M M M M L L L PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z SATURDAY... NO WIDESPREAD IFR EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/RPY/50 NEAR TERM...50 SHORT TERM...TRM LONG TERM...RPY AVIATION...50