Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231807 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 207 PM EDT THU APR 23 2015 .SYNOPSIS... HIGH PRESSURE MOVES ACROSS THE AREA THROUGH TOMORROW. LOW PRESSURE APPROACHES SATURDAY AND CROSSES LATE SATURDAY NIGHT. WEAK UPPER TROUGH AXIS MONDAY. HIGH PRESSURE TUESDAY. && .NEAR TERM /THROUGH FRIDAY/... LATEST SURFACE ANALYSIS SHOWS DRY AIR THAT WAS SEEN ON MORNING UPPER AIR ANALYSIS HAS MIXED DOWN WITH DEWPOINTS ACROSS SOUTHERN COUNTIES IN THE TEENS AND LOWER 20S. MAINLY DIURNAL CLOUDS HAVE DEVELOPED ACROSS NORTHERN PORTIONS OF THE AREA. MODELS SUGGEST A WEAK FEATURE WILL MOVE ACROSS THIS EVENING INTO THE NIGHTTIME HOURS...POSSIBLY PRODUCING SOME LIGHT RAIN OR SNOW ACROSS OUR FAR NORTHEASTERN COUNTIES BEFORE MIDNIGHT. THE SYSTEM SHOULD THEN PUSH EAST...TAKING MOST OF THE CLOUDS WITH IT. THE COMBINATION OF FEW CLOUDS...DRY LOW-LEVEL AIRMASS AND LIGHT WINDS SHOULD RESULT IN FAVORABLE CONDITIONS FOR RADIATIONAL COOLING...ESPECIALLY ACROSS OUR SOUTH. WITH THIS IN MIND... ADJUSTED LOW TEMPS ACROSS THE SOUTH DOWNWARD. THIS CHANGE RESULTED IN MUCH OF THE AREA POSSIBLY SEEING LOWS TONIGHT RIGHT AROUND FREEZING. I AM SURE AREAS ALONG THE RIVERS AND URBAN AREAS WILL BE WARMER. HOWEVER...OUTLYING AREAS WILL LIKELY SEE TEMPS AT OR BELOW FREEZING BY MORNING. HAVE EXPANDED FREEZE WARNING TO INCLUDE ALL OF OUR REGION...EXCEPT FOR THE CENTRAL AND NORTHERN COUNTIES...WHERE THE GROWING SEASON HAS NOT STARTED YET. LOTS OF SUNSHINE...LIGHT WINDS AND DRY CONDITIONS SHOULD RESULT IN NICE CONDITIONS BY TOMORROW AFTERNOON. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... FROSTY START TO THE PERIOD WITH CANADIAN HIGH PRESSURE EXTENDING SOUTHEASTWARD FROM CENTRAL CANADA SEWD THROUGH THE MIDDLE OHIO VALLEY AND SRN APPALACHIANS...TO THE SERN CONUS. MUCH OF THE PORTION OF THIS RIDGE AXIS OVER THE CONUS GETS TAKEN OUT BY SAT AFTERNOON...AS A LARGE LOW PRESSURE SYSTEM COMES OUT OF THE CENTRAL PLAINS...AND GETS CLOSER TO ANOTHER LOITERING WELL OFF THE E COAST. UPSTAIRS...THE SRN STREAM S/W TROUGH SUPPORTING THE APPROACHING SFC LOW MINORS OUT AS IT MOVES EWD...AND GETS DRAWN INTO CIRCULATION OF A LARGE UPPER LEVEL LOW MEANDERING ABOUT NEW ENGLAND AND THE CANADIAN MARITIMES. AS A RESULT...THE SFC LOW TAKES A MORE NRN TRACK INITIALLY...PUSHING INTO THE MIDDLE OHIO VALLEY...AND PUSHING MILDER AIR INTO THE FCST AREA. IT THEN JUMPS THE MOUNTAINS TO A POSITION OFF THE NC COAST EARLY SUNDAY MORNING...ALLOWING THE RETURN OF COOLER AIR TO THE FCST AREA. MODELS ARE IN GOOD AGREEMENT ON A WET SAT AND SAT NT. THE SHOWERS MOVE INTO THE FCST AREA FIRST THING SAT MORNING...WITH THE CHANCE FOR THUNDERSTORMS PUSHING INTO THE SW HALF OF FCST AREA SAT...AND THEN RETREATING BACK TOWARD THE TUG FORK SAT NT. USED 8C DEW POINT AT H85 AS A THRESHOLD FOR THUNDER TO REFLECT THE ELEVATED INSTABILITY DRIVING THE CONVECTION. AS FOR GENERAL POPS...THE SHOWERS ARE LIKELY TO LINGER LONGEST OVER THE NRN WV MOUNTAINS SAT NT...IN THE DEFORMATION AXIS NEAR WHAT WILL BE A VANISHING CONFLUENCE ZONE. MODEL AVERAGES CLOSE TO AN INCH TOTAL QPF ACROSS SRN PORTIONS OF THE FCST AREA AND THE FCST IS CLOSE TO AN INCH THERE. THAT SHOULD CAUSE NOTHING MORE THAN SOME POOR DRAINAGE PONDING...AND THE ELEVATED CONVECTION SHOULD BE NOT BE STRONG. HOWEVER...DOWNPOURS ARE POSSIBLE WHEN PW VALUES PEAK AROUND 1.2 NEAR THE TUG FORK IN THE WARM ADVECTION SAT MORNING...AND PEAK AGAIN NEAR 1.3 NEAR OR JUST S OF THE LOW PRESSURE CENTER...AGAIN NEAR THE TUG FORK...SAT EVENING. THE LAST OF THE SHOWERS PULL OUT W TO E SUNDAY. LOW CLOUDS WILL LINGER FOR A TIME SUNDAY MORNING BEFORE MIXING OUT FOR SOME SUNSHINE W TO E SUNDAY AFTERNOON. ALLBLEND SEEMED TO WORK FOR TEMPERATURES. IT WAS IN LINE WITH PREVIOUS FCST FOR HIGHS FRI AND THAT FCST WAS LEFT UNCHANGED. HAVE HIGHS A LITTLE HIGHER THAN PREVIOUS FOR SAT AND A LITTLE LOWER FOR SUNDAY...REFLECTING THE INITIAL NRN TRACK OF THE LOW AND THEN ITS REDEVELOPMENT TO THE SE. HIGHS THIS WEEKEND ARE BELOW MOS GUIDANCE IN THE CLOUDS / RAIN. STILL HAVE A SLIGHT RISE IN TEMPERATURES TOWARD DAWN SAT AND RAISED LOWS FOR SUNDAY MORNING JUTS A BIT WITH A SLOWER EXODUS OF THE ELONGATED LOW PRESSURE SYSTEM. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AFTER THE MID ATLANTIC LOW EXITS...UPPER LOW RETROGRADES FROM ATLANTIC CANADA SOUTHWESTWARD INTO NEW YORK STATE...DROPPING A WEAK TROUGH AXIS IN FROM THE NORTH. CARRY LOW END MOUNTAIN POPS FOR THIS FEATURE FOR MONDAY...WITH HIGH PRESSURE MOVING IN FOR TUESDAY. OPERATIONAL MODELS DIVERGE SIGNIFICANTLY AFTER MONDAY...WITH THE GFS BRINGING A LOW PRESSURE SYSTEM ACROSS THE SOUTH AGAIN...WHILE THE 00Z ECMWF KEEPS THE CWA DRY THROUGH THE EXTENDED. GOING CLOSER TO THE GFS FOR THIS ISSUANCE WITH SOME BELOW AVERAGE CONFIDENCE WITH THE POPS THROUGH THE MIDDLE OF THE WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... 18Z THURSDAY THRU 18Z FRIDAY... MAINLY VFR CONDITIONS EXPECTED DURING THE PERIOD. GUSTY WINDS WILL GENERALLY SLACKEN AFTER 00Z...ALTHOUGH OCCASIONAL GUSTS WILL CONTINUE ACROSS THE MOUNTAINS. UNTIL 00Z...GUSTS TO 25 KT ARE POSSIBLE ACROSS THE LOWLANDS WITH 35 KT GUSTS POSSIBLE ACROSS THE HIGHEST ELEVATIONS. AFTER 14Z...EXPECT WINDS WILL INCREASE WITH GUSTS GENERALLY LESS THAN 15 KT ACROSS THE LOWLANDS AND 25 KT OVER THE MOUNTAINS LATE. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: HIGH. ALTERNATE SCENARIOS: NONE. 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 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 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 FRIDAY... IFR POSSIBLE IN STRATUS SAT NT INTO SUNDAY MORNING AS RAIN DIMINISHES. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR WVZ005>011- 013>020-024>031-033-034. OH...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR OHZ066-067-075- 076-083>087. KY...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR KYZ101>103-105. VA...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR VAZ003-004. && $$ SYNOPSIS...JSH/ARJ/26 NEAR TERM...JSH SHORT TERM...TRM LONG TERM...26 AVIATION...JSH

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