Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 301820 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 219 PM EDT WED JUL 30 2014 .SYNOPSIS... COOL...DRY AIRMASS HANGS ON THROUGH THURSDAY. HIGHER TEMPERATURES AND HUMIDITY BEGINNING FRIDAY WILL LEAD TO CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND...ESPECIALLY IN THE MOUNTAINS. && .NEAR TERM /THROUGH TONIGHT/... SHOWERS AND THUNDERSTORMS FORMING IN CENTRAL OHIO EARLY THIS AFTERNOON...IN RESPONSE TO AN UPPER LEVEL S/W TROUGH THERE...WILL MOVE ESEWD ACROSS THE AREA THIS AFTERNOON INTO THIS EVENING. NAM12 HAS NEAR TERM MODEL SUPPORT ON THIS IDEA. HAVE SCT COVERAGE BUT MAY HAVE TO BUMP UP PER DEVELOPMENT UPSTREAM. THE WEATHER SETTLES DOWN WITH LESS CLOUD AND LOW LEVEL MOISTER LATER TONIGHT AND THU SAVE FOR THE POST-RAIN EFFECTS OVERNIGHT TONIGHT. IT AND THE CLEAR...CALM CONDITIONS THAT WILL ENSUE BEHIND THE AXIS OF CONVECTION SHOULD ALLOW DENSE VALLEY FOG TO FORM ESPECIALLY AS WE ARE NEARING IF NOT ENTERING FOG SEASON. A NICE DAY IS ON TAP FOR THU ONCE THE MORNING FOG IS GONE. A SOUTHERN STREAM UPPER LEVEL FEATURE MAY BRING CONVECTION INTO SW VA AS THU DRAWS TO A CLOSE THOUGH. TEMPERATURES LOOKED CLOSE TO LATEST BIAS CORRECTED GUIDANCE ON LOWS TONIGHT AND STRAIGHT UP GUIDANCE ON HIGHS THU...AS H85 VALUES CLIMBING UP TO 14C SUPPORT AT LEAST LOWER 80S LOWLANDS. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... GENERAL MODEL AGREEMENT ON A WEAK BUT SHARPENING UPPER TROUGH OVER THE EASTERN THIRD OF THE NATION...AS THE BERMUDA HIGH IN THE WESTERN ATLANTIC EXPANDS WESTWARD. A DRY AND STILL RATHER MILD THURSDAY IS EXPECTED WITH SURFACE HIGH PRESSURE OVER THE AREA. THE HIGH SHIFTS EAST BY FRIDAY...ALLOWING WARMER AND MUCH MORE HUMID AIR TO RETURN ON SOUTH TO SOUTHEASTERLY FLOW. THIS IN COMBINATION WITH UPPER DISTURBANCES ROTATING AROUND THE UPPER TROUGH WILL BRING INCREASING CHANCES FOR SHOWERS AND STORMS. THE BIG QUESTION IS HOW FAR WEST WILL THESE DISTURBANCES...AND HENCE THE PRECIPITATION SHIELD...TRACK AS THEY RIDE UP THE EASTERN SIDE OF THE UPPER TROUGH. GENERAL CONSENSUS...WITH THE NAM A WESTERN OUTLIER...KEEPS MOST OF THE PRECIPITATION THIS PERIOD IN THE MOUNTAINS AND EAST AS AN INVERTED SURFACE TROUGH FORMS EAST OF THE MOUNTAINS. WILL HAVE HIGH POPS MOUNTAINS FRIDAY ONWARD...WITH MUCH LOWER POPS WEST OF THE MOUNTAINS. HIGH TEMPERATURES WILL STILL BE BELOW NORMAL THIS PERIOD...IN THE LOWER 80S...BECAUSE OF THE WIDESPREAD CLOUDS EXPECTED. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... SHOWERS AND THUNDERSTORMS INCREASE IN COVERAGE FRIDAY NIGHT AND INTO SATURDAY AS A LOW MOVES INTO THE AREA FROM THE SOUTHWEST. INCREASED POPS TO HIGH CHANCE/LOWER LIKELIES IN THIS TIME FRAME UNSETTLED WEATHER WILL CONTINUE FOR MUCH OF THE EXTENDED PERIOD...AS ADDITIONAL UPPER LEVEL ENERGY DROPS SOUTHEAST INTO THE MIDWEST...DEEPENING THE UPPER TROUGH ACROSS THE AREA...AND KEEPING THE WEATHER ON THE COOL AND UNSETTLED SIDE. DRIER WEATHER WILL FINALLY SETTLE IN TOWARDS EARLY TO MID NEXT WEEK AS THE UPPER TROUGH PUSHES OFF TO THE EAST...AND SURFACE HIGH PRESSURE BUILDS IN. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... LINGERING LOW LEVEL MOISTURE MAY STILL LEAD TO MVFR CIGS THIS AFTERNOON ALTHOUGH VFR WILL PREVAIL MOST OF THE TIME. AN UPPER LEVEL DISTURBANCE WILL BRING AN AXIS OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THIS AFTERNOON INTO THIS EVENING. TAFS MAY NEED AMENDED FOR THUNDER AND MVFR OR WORSE CONDITIONS IF IT APPEARS A THUNDERSTORM WILL TRACK OVER AN AIRPORT. OTHERWISE THE VCTS / CB GROUPS DEFINE THE TIME BRACKETS FOR THE DIFFERENT AIRPORTS. CLEARING IN THE WAKE OF THIS SYSTEM WILL ALLOW DENSE VALLEY FOG TO FORM OVERNIGHT TONIGHT. ONCE THE FOG BURNS OFF THU MORNING...THE DAY WILL FEATURE NEITHER MORNING CU NOR THUNDERSTORMS...SO VFR IS FCST. LIGHT SW SFC FLOW WILL BECOME W TO NW ONCE THE AXIS OF SCATTERED CONVECTION MOVES THROUGH. A THUNDERSTORM CAN BRING GUSTS UP TO 25 KTS. THE SFC FLOW WILL BECOME CALM TONIGHT AND THEN LIGHT W TO SW ON THU. FLOW ALOFT WILL REMAIN LIGHT W. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: MVFR STRATOCU MAY OR MAY NOT POP UP AGAIN THIS AFTERNOON. A THUNDERSTORM COULD DIRECTLY IMPACT AN AIRPORT. THE TIMING AND EXTENT OF FOG OVERNIGHT INTO EARLY THU MORNING MAY VARY FROM FORECAST. 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 THURSDAY... NO SIGNIFICANT IFR CONDITIONS EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KMC/JMV NEAR TERM...TRM SHORT TERM...JMV LONG TERM...SL AVIATION...TRM

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