Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 281824 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 124 PM EST SAT FEB 28 2015 .SYNOPSIS... WARM FRONT LATE TONIGHT INTO SUNDAY. COLD FRONT SUNDAY NIGHT. DRIER MONDAY INTO MONDAY NIGHT. ANOTHER WARM/COLD FRONT COMBO TUESDAY INTO WEDNESDAY. && .NEAR TERM /THROUGH SUNDAY/... WARM ADVECTION S FLOW INTO AN ARCTIC AIR MASS...ON THE BACK SIDE OF THE EXITING ARCTIC HIGH...WILL CREATE MIXED PRECIPITATION IN THE AREA OVERNIGHT TONIGHT AND SUNDAY..BENEATH FLAT UPPER LEVEL SW FLOW.. PRECIPITATION SHOULD SPREAD INTO THE OHIO VALLEY AFTER MIDNIGHT TONIGHT. MODELS WARM THE LAYERS ABOVE FREEZING MORE OR LESS AT THE SAME TIME ALTHOUGH BUFKIT SOUNDINGS DO SUGGEST A SHALLOW LAYER OF COLD AIR HANGING ON INTO SUNDAY AFTERNOON ESPECIALLY TO THE NW OF THE OHIO RIVER...AND IN THE GREENBRIER VALLEY. STILL GETTING AROUND 2 INCHES SNOW PERRY AND MORGAN COUNTIES TO KEEP THE ADVISORY GOING THERE...WITH A TOUCH OF FREEZING RAIN POSSIBLE THERE IN THE TRANSITION. ALSO CONSIDERING ADVISORY FOR FREEZING RAIN OVER THE EASTERN SLOPES OF OUR WV MOUNTAIN COUNTIES OF POCAHONTAS...FAYETTE AND RANDOLPH COUNTIES. WILL CONSIDER EXPANSION OF ADVISORY TO THESE COUNTIES IN COORD WITH NEIGHBORS THIS AFTERNOON. ANY FREEZING RAIN ELSEWHERE IS EXPECTED TO BE BRIEF AND RELATIVELY INCONSEQUENTIAL. USED NAM / MET BLENDED WITH PREVIOUS RUN FOR TEMPERATURES AND DEW POINTS. DO HOLD ON THE COLD AIR A LITTLE LONGER IN SE OHIO AND IN THE GREENBRIER VALLEY ON SUNDAY. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... GROWING CONCERN FOR FLOODING AND RIVER FLOODING MID WEEK NEXT WEEK. FIRST...THE SUNDAY SYSTEM. GOOD ISENTROPIC LIFT SUNDAY MORNING WITH WARM FRONT SHIFTING NW OF AREA. THERMAL PROFILES SUPPORT PRIMARILY SNOW IN THE MORNING ACROSS PORTIONS OF SE OH. AFTER COORDINATION WITH NEAR TERM FORECASTER AND SURROUNDING OFFICES...ELECTED TO HOIST A WINTER WX ADVISORY FOR PERRY AND MORGAN FOR 1 TO 3 INCHES OF SNOW. THIS SHOULD TURN TO SHRA MIDDAY AS SFC TEMPS WARM. ELSEWHERE...A BAND OF WAA PRECIP OVER SW VA/S AND C WV/NE KY ZONES FIRST HALF OF SUNDAY. THIS MAY TAKE THE FORM OF A BRIEF MIX ACROSS S ZONES SUNDAY MORNING. AS SUNDAY PROGRESSES...S ZONES MAY EXPERIENCE ONLY ISOLATED SHRA IN THE AFTERNOON WITH WAA LIGHT PRECIP SHIFTING INTO N WV/SE OH MAINLY IN THE FORM OF RAIN. HAVE TEMPS SPIKING INTO THE MID 40S ALONG AND S OF I64 WITH MID UPPER 30S TO LOWER 40S FURTHER N. SUNDAY NIGHT WILL FEATURE AFOREMENTIONED WARM FRONT SAGGING SE AS A COLD FRONT WITH HELP OF SURFACE HIGH TRYING TO NOSE INTO OH VALLEY FROM THE UPPER MIDWEST. RAIN SHOWERS WILL TRY TO CHANGE TO SNOW WITH FROPA BUT MOISTURE WILL BE WANING FOR ANY MEANINGFUL ACCUMULATION OUTSIDE OF THE MOUNTAINS. ACROSS THE N MOUNTAINS...THERMAL PROFILES REMAIN ON THE COLD SIDE IN THE HIGHER ELEVATIONS FOR A FEW INCHES TO ACCUMULATE SUNDAY NIGHT. HAVE TEMPS SLOWLY FALLING OVERNIGHT. FOR MONDAY...AFOREMENTIONED HIGH PRESSURE WILL SCOOT ACROSS THE UPPER OH VALLEY INTO PA BY EVENING. THIS WILL ALLOW FOR A MAINLY DRY DAY AFTER MORNING MOUNTAIN SNOW SHOWERS. WILL BE DEALING WITH SOME MID AND HIGH CLOUDS THOUGH. TEMPS WILL RUN AROUND 40 S ZONES...TO MID 30S ACROSS SE OH AND N WV. ATTENTION TURNS TO WHAT HAS BECOME A WELL ADVERTISED RAIN MAKER SLATED FOR MID WEEK. PREVIOUS FORECAST DISCUSSIONS HAVE HAMMERED HOME THE POTENTIAL FOR WATER PROBLEMS AND SEE NO REASON TO BACK DOWN FROM THAT. SIDED MORE WITH THE NEW ECMWF GIVEN POSITIVE TILT TO UPPER TROF HANGING BACK...OWING TO LESS PROGRESSION OF SFC FLOW. PRECIP WILL TRY TO BREAK OUT ALONG DEVELOPING WARM FRONT TUESDAY...WITH BEST CHANCES ACROSS SE OH. THERE MAY BE A VERY BRIEF MIX AT THE ONSET...BUT THIS IS PRIMARILY A RAIN MAKER ON TUESDAY. TRIED TO KEEP HIGH POPS ON E SLOPES AND ESPECIALLY N PORTIONS OF OUR SE OH COUNTIES AS AREA GETS IN THE WARM SECTOR. LLJ INCREASES TO NEAR 70 KTS TUESDAY NIGHT OUT OF SW WITH THE OVERALL FLOW TRYING TO BECOME PARALLEL TO THE SFC COLD FRONT AS IT BEGINS TO SLOW DOWN CONSIDERABLY ON APPROACH. COPIOUS AMOUNTS OF MOISTURE WILL BE POOLED ALONG FRONTAL BOUNDARY...WITH PWATS SURGING TO NEAR 1.5 INCHES ON IMPRESSIVE THETA E ADVECTION. IT APPEARS THE FIRST AREA OF CONCERN WILL BE SE OH TUESDAY NIGHT...SPREADING E INTO NE KY AND THE WV LOWLANDS ON WEDNESDAY AS THE BOUNDARY SAGS SE. THERE CONTINUES TO BE SOME HINT OF A WAVE FORMING ALONG THE BOUNDARY ON THE MODELS AND FAVORING THE SLOWER ECMWF WOULD PUT THE NEXT SLUG OF HVY PRECIP IN OUR AREA LATER WEDNESDAY AND WEDNESDAY NIGHT. THIS WOULD BE BAD NEWS GIVEN THE RESIDUAL SNOW PACK...ALTHOUGH A GOOD AMOUNT OF IT OUTSIDE OF THE MOUNTAINS WILL HAVE ALREADY RELEASED INTO CREEKS AND RIVERS. STILL...THERE IS GROWING CONCERN FOR THE POTENTIAL FOR FLOODING AND MAIN STEM RIVER FLOODING. THE NAEFS AND GEFS ENSEMBLES PAINT A SCARY SITUATION ON SOME OF THE RIVERS WITH AN AVG OF 2 INCHES OF QPF TO CONTEND WITH. ACROSS THE MOUNTAINS...THERE IS A CONSIDERABLE AMOUNT OF LIQUID ALREADY IN THE SNOW PACK...WITH SNOWSHOE CHECKING IN WITH 3.75 INCHES SWE ON A 30 INCH SNOWPACK. DEWPOINTS WILL ALSO BE WORRISOME ON THIS SNOWPACK...ALONG WITH WARMER TEMPS. HAVING SAID ALL THAT...WE STILL HAVE GFS AND ITS ENSEMBLES INDICATING A MORE PROGRESSIVE SOLUTION. GIVEN THIS...AND AFTER COORDINATING WITH SURROUNDING OFFICES...WILL HOLD OFF ON A LONG FUSE FLOOD WATCH FOR NOW AND CONTINUE WITH HWO. HOPEFULLY THE MORE PROGRESSIVE SCENARIO WILL EVENTUALLY PAN OUT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... MODELS STARTING TO COME INTO BETTER AGREEMENT WITH EACH OTHER IN TERMS OF OVERALL PATTERN...ALTHOUGH TIMING ISSUES REMAIN. BRIEF BREAK IN THE PRECIPITATION EXPECTED FOR THE FIRST PART OF TUESDAY...AS HIGH PRESSURE HOLDS ON A LITTLE LONGER. HOWEVER...THIS WILL CHANGE AS A WARM FRONTAL BOUNDARY LIFTS NORTH ACROSS THE REGION. DEPENDING ON SURFACE TEMPERATURES...COULD SEE A BRIEF PERIOD OF FREEZING RAIN OR EVEN SLEET AT THE ONSET TUESDAY...BEFORE ENOUGH WARM AIR IS ABLE TO SURGE NORTH TO SCOUR OUT COLDER SURFACE TEMPERATURES. STILL LOOKING LIKE GOOD TAP OF GULF MOISTURE SURGING INTO THE REGION TUESDAY INTO WEDNESDAY WITH STRONG SOUTHWESTERLY WINDS DEVELOPING...WITH PW VALUES EXPECTED TO RISE AROUND 1.2 TO 1.3 INCHES...OR ABOUT 3 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR. THIS...ALONG WITH THE STRONG DYNAMICS...WILL RESULT IN HEAVY RAIN ACROSS THE AREA...WITH A GENERAL 1 TO 2 INCHES OF RAIN EXPECTED...WITH THE HIGHER AMOUNTS AT THIS POINT EXPECTED ACROSS WV LOWLANDS AND SOUTHEAST OHIO. THE HEAVY RAIN...COMBINED WITH ANY SNOW MELT THAT IS ABLE TO OCCUR DUE TO WARMING TEMPERATURES...COULD CREATE FLOODING ISSUES. THERE IS A GENERAL 2 TO 4 INCHES OF WATER IN THE SNOW PACK ACROSS THE MOUNTAINS. OF COURSE THERE IS STILL UNCERTAINTY AS TO HOW MUCH SNOWMELT WILL OCCUR AND HOW RAPID IT WILL BE. WILL NEED TO MONITOR AREA CREEKS AND STREAMS INITIALLY WITH THIS SYSTEM...AND POSSIBLY RIVERS AS TIME PROGRESSES. THE GOOD NEWS IS...MODELS HAVE TRENDED TOWARDS A MORE SOUTHERLY TRACK WITH THE LOW THAT WILL DEVELOP AND PUSH ACROSS THE SOUTHEAST U.S. MID WEEK. THIS SHOULD HOPEFULLY KEEP THE BULK OF MOISTURE WITH THAT LOW TO OUR SOUTH. COLD FRONT WILL PUSH THROUGH THE CWA WEDNESDAY OR EARLY THURSDAY...WITH A GENERAL DRYING TREND TAKING HOLD AS HIGH PRESSURE BUILDS IN FROM THE WEST. ANY PRECIPITATION WILL CHANGE OVER TO LIGHT SNOWFALL BEHIND THE FRONT. WILL CONTINUE TO MENTION FLOODING POTENTIAL IN THE HWO FOR THE TIME PERIOD. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR FINISH TO THE DAY AS THE LAST MAJOR ARCTIC AIR MASS OF THE SEASON LEAVES THE AREA. THIS WILL GIVE WAY TO WARM ADVECTION TONIGHT AND SUDNAY...AS A WEAK LOW PRESSURE SYSTEM MOVES UP THE OHIO RIVER VALLEY. THIS WILL PUMP MOISTURE AND MILDER AIR INTO THE AREA. SNOW IS LIKELY TO OVERSPREAD THE MIDDLE OHIO VALLEY OVERNIGHT TONIGHT AND THEN MIX WITH SLEET...THEN BREIFLY TO FREEZING RAIN...AND THEN ALL RAIN BY 18Z SUNDAY. ANOTHER WEAK DISTURBANCE MOVING UP FROM THE S WILL BRING SNOW AND SLEET TO THE NRN WV MOUNTAINS EARLY SUNDAY MORNING WITH SLEET...FREEZING RAIN AND RAIN INTO THE SOUTHERN AND CENTRAL WV MOUNTAINS. THE PRECIPITATION IN THE MOUNTAINS WILL ALSO GO TO RAIN BY 18Z SUNDAY...SAVE FOR PERHAPS THE HIGHEST TERRAIN AND ERN SLOPES...WHERE A MIX MAY PERSIST. CIGS WILL DROP TO MVFR SUNDAY MORNING WITH LOW MVFR MOST PLACES BY 18Z SUNDAY. EXPECT MVFR VSBY IN PRECIPITATION SUNDAY MORNING BUT IFR SNOW WILL BE CLOSE BY PKB...TO THE W OF THE OHIO RIVER...AND IN THE HIGHER TERRAIN. LIGHT AND VARIABLE SFC FLOW WILL HAVE MOSTLY AN ERLY COMPONENT...A LITTLE STRONGER SE IN THE MOUNTAINS. LIGHT SW FLOW ALOFT WILL BECOME MODERATE SW OVERNIGHT TONIGHT AND THEN REMAIN SO ON SUNDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF ONSET OF PRECIPITATION AND ASSOCIATED LOWER CIGS AND VSBYS COULD VARY. IFR SNOW COULD GET INTO PKB SUNDAY MORNING. MUCH OF THE MOS GUIDANCE IS SUGGESTING IFR CIGS AND VSBYS BY MIDDAY SUNDAY. 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 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 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 H 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 H H H H H H AFTER 18Z SUNDAY... IFR POSSIBLE IN RAIN OR MIXED RAIN/SNOW LATE SUNDAY INTO EARLY MONDAY. IFR POSSIBLE AGAIN IN RAIN SHOWERS TUESDAY INTO WEDNESDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...WINTER WEATHER ADVISORY FROM 1 AM TO 1 PM EST SUNDAY FOR OHZ066-067. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/RPY/SL/30 NEAR TERM...TRM SHORT TERM...30 LONG TERM...SL AVIATION...TRM

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