Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231352 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 852 AM EST FRI JAN 23 2015 .SYNOPSIS... STRENGTHENING LOW PRESSURE ACROSS SOUTHEAST TODAY AND OFF NEW ENGLAND COAST SATURDAY. CLIPPER LATE SUNDAY/SUNDAY NIGHT. TURNING COLDER MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 850 AM UPDATE...TWEAKED POPS A BIT...TO INCLUDE A CHANCE ACROSS THE SOUTH A COUPLE OF HOURS QUICKER BASED ON RADAR TRENDS. OTHERWISE...NO SIGNIFICANT CHANGES NEEDED AT THIS POINT. PREVIOUS DISCUSSION BELOW... ALL ON EYES ON SURFACE LOW TRAVERSING THRU THE SE STATES TODAY...FOLLOWED BY AN UPPER TROF AXIS CROSSING THE REGION OVERNIGHT. THERE ARE A NUMBER OF MITIGATING FACTORS THAT WILL KEEP THE WINTRY EFFECTS FROM THIS MINIMAL. A LACK OF A SURFACE HIGH TO THE N...MARGINAL COLD AIR ALOFT...AND A PESKY INVERTED SURFACE TROF OVER THE AREA...ALL POINT TO MORE OF A NUISANCE EVENT. AS FOR THE NITTY GRITTY DETAILS... SPED UP POPS A BIT FROM PREVIOUS FORECAST...PRIMARILY USING THE HRRR TIMING. A RELATIVELY DEEP DOWNSLOPING SSE TO SE FLOW INTO MIDDAY MAY GIVE TEMPS A SPIKE. HOWEVER...NONE OF THE MODELS ARE SHOWING THIS EXCEPT HRRR AND RUC. SO KEPT HIGHS IN CHECK BUT STILL A FEW DEGREES ABOVE GUIDANCE FROM ALONG US119 AND I79 CORRIDOR OVER TO W SLOPES. THERMAL PROFILES FROM VARIOUS HI RES MODELS INDICATED PRECIP STARTING AS RAIN OUTSIDE OF THE MOUNTAINS. PRECIP SHOULD START OUT AS SNOW OR A MIX OF SNOW AND SLEET IN THE MOUNTAINS...WHERE A FEW INCHES WERE CODED UP FOR LATE THIS AFTERNOON. THIS EVENING...THE STEADY PRECIP WILL HAVE SHIFTED INTO SE OH AND N WV WITH SCT COVERAGE IN THE MID LEVEL DRY PUNCH ELSEWHERE. THE SURFACE LOW WILL BE MAKING A RUN OFF THE TIDEWATER REGION WITH THE INVERTED SURFACE TROF LINGERING OVER THE AREA. MODEL SOUNDINGS SHOW A WARM LAYER ALOFT ACROSS THE MOUNTAINS...DEEP ENOUGH FOR THE PRECIP TO CHANGE TO FREEZING RAIN ACROSS THE ELEVATION ABOVE 3.5KFT...WITH SOME SLEET EXPECTED OVER THE TYGART AND ESPECIALLY THE GREENBRIER VALLEY. IT IS EVEN POSSIBLE SNOWSHOE CHANGES TO LIGHT RAIN FOR A TIME. MEANWHILE...THE CHANGEOVER TO WET SNOW WILL BE OCCURRING ACROSS NE KY AND SE OH AS THE UPPER TROF AXIS CLOSES IN WITH COOLING ALOFT. THERE CONTINUES TO BE A DEFORMATION BAND OF SORTS SHOWING UP ON THE MODELS AS THE UPPER TROF CROSSES. HAVE ORIENTED THE POPS TO REFLECT THIS THINKING...SLOWLY TRACKING IT E FROM SE OH/NE KY INTO C WV BY PREDAWN HRS. THIS SHOULD COINCIDE WITH THE CHANGEOVER TO WET SNOW. HAVE ALLOWED AROUND AN INCH TO FALL ACROSS SE OH/NE KY/W WV WITH A COATING FURTHER E AS THE OVERALL BAND BEGINS TO WEAKEN. ACROSS THE MOUNTAINS...PRECIP WILL CHANGE BACK TO SNOW AFTER MIDNIGHT BUT PRECIP SHOULD BE SPOTTY UNTIL THE UPPER TROF AXIS AND DEFORMATION BAND MOVES IN TOWARD MORNING. AFTER COLLABORATION WITH SURROUNDING OFFICES...HAVE HOISTED A WINTER WEATHER ADVISORY FOR RANDOLPH AND POCAHONTAS. DESPITE NOT REACHING CRITERIA SNOW WISE...THERE IS EXPECTED TO BE SOME FREEZING RAIN IN THE HIGHER ELEVATIONS WHICH MAY ACCRUE TO AROUND A TENTH OF AN INCH. STARTED IT THIS AFTERNOON TO HIT THE INITIAL LIGHT ACCUMULATION OF SNOW WITH THE ICE THREAT FROM 00 TO 06Z. ENDED IT AT 15Z WHEN THE UPPER TROF IS EXPECTED TO HAVE MOVED THRU. && .SHORT TERM /SATURDAY THROUGH MONDAY/... MODELS SHOW SYSTEM PULLING OUT EARLY SATURDAY. SOME MARGINAL UPSLOPE THEN APPEARS POSSIBLE SATURDAY NIGHT AS NORTHWEST WINDS PULL IN SOME COOLER AIR. 850 MB TEMPERATURES ARE MARGINAL FOR AUTO CONVECTION IN THE LOWER LEVELS...SO WILL KEEP POPS IN THE CHANCE CATEGORY. MODELS ARE A BIT FASTER WITH A CLIPPER MOVING THROUGH LATE SUNDAY/SUNDAY EVENING. BOTH NAM AND GFS ARE SHOWING LOTS OF LIFT WELL SOUTH OF THE LOW TRACK...BUT CLIPPERS USUALLY STRUGGLE TO PRODUCE PRECIPITATION SOUTH OF THE LOW. THEREFORE...WILL SHOW A NORTH SOUTH GRADIENT OF POPS. COLDER AIR BEHIND THE CLIPPER ON MONDAY IS COLD ENOUGH FOR AUTO CONVECTIVE CONDITIONS IN THE LOWER LEVELS...SO WILL KEEP HIGH POPS OF SNOW. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... THE TREND THAT WE MENTIONED YESTERDAY REMAINS...THE CLIPPER COMING EAST THROUGH THE MIDWEST INTO THE UPPER OHIO VALLEY...AT A HIGHER LATITUDE REMAINS. AS A RESULT...WAS A BIT SLOWER BRINGING IN THE COLDER AIR LATE SUNDAY NIGHT INTO MONDAY. POPS INCREASE NW TO SE DURING SUNDAY NIGHT IN THE WAKE OF THE CLIPPER PASSING OUR LONGITUDE. WE WILL BE CONSISTENT WITH POPS IN THE LIKELY CATEGORY MONDAY INTO MONDAY EVENING BEFORE WANING FROM WEST TO EAST. AS MOISTURE THINS...850 TEMPS BECOME COLDER...SO HELD ONTO SOME FLAKES EVEN INTO TUESDAY EAST OF THE OHIO RIVER. STILL DRY ON WEDNESDAY. WARMING 850 TEMPS WEDNESDAY NIGHT INTO THURSDAY. NEXT WESTERN FRONT LONG ABOUT THURSDAY AFTERNOON. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... 12Z FRIDAY THRU 12Z SATURDAY... A LOW PRESSURE SYSTEM WILL APPROACH FROM THE SOUTH SOUTHWEST TODAY. CIGS WILL LOWER AS PRECIP MOVES IN FROM THE SW THIS AFTERNOON...FIRST ACROSS SW VA AND SE WV AFFECTING KBKW BY 18Z WITH MVFR. PRECIPITATION OVERSPREADS THE REGION TOWARD EVENING WITH MOST OF REMAINING TERMINALS EXPERIENCING MVFR CIGS IN PRECIP BY 21Z. MVFR VSBY WILL LAG BEHIND A FEW HRS. EXPECT BULK OF PRECIP THRU 00Z TO BE LIQUID...SAVE FOR A HR OR TWO OF A MIX FOR KBKW AT ONSET. CIGS WILL LOWER INTO IFR LATE THIS AFTERNOON AND EARLY EVENING WITH A GRADUAL CHANGEOVER TO WET SNOW OVERNIGHT. VSBY WILL FOLLOW SUITE WITH LOCALIZED VLIFR VSBY. IN THE HIGH TERRAIN A VARIETY OF PRECIP TYPES CAN BE EXPECTED DEPENDING ON ELEVATION. LOW LEVEL FLOW WILL BRIEFLY STRENGTHEN OUT OF SSE THIS MORNING...PROVIDING FOR SOME 15 TO 20 KT GUSTS AT KBKW. OTHERWISE 5 TO 10 KT WINDS OUT OF NE FOR W TERMINALS AND E FOR THE MOUNTAIN TERMINALS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIO: TIMING LOWERING OF CIGS INTO MVFR OR WORSE ALONG WITH VSBY MAY VARY A FEW HRS THIS AFTERNOON/EVENING. 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 14 15 16 17 18 19 20 21 22 23 00 01 EST 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20 CRW CONSISTENCY H H H H H M M M M M M M HTS CONSISTENCY H H H H H M M M M M H H BKW CONSISTENCY H H M L H H H H H H H H EKN CONSISTENCY H H H H H M H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H M H H M H M AFTER 12Z SATURDAY... IFR POSSIBLE EARLY SATURDAY MORNING IN SNOW. IFR POSSIBLE IN SNOW IN THE HIGHER ELEVATIONS OF THE MOUNTAINS SUNDAY/SUNDAY NIGHT. IFR POSSIBLE AREA WIDE IN SNOW SHOWERS MONDAY/MONDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 10 AM EST SATURDAY FOR WVZ046-047. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/RPY/30 NEAR TERM...SL/30 SHORT TERM...RPY LONG TERM...KTB AVIATION...30

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