Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 031833 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 233 PM EDT THU SEP 3 2015 .SYNOPSIS... UNSTABLE AIRMASS CONTINUES INTO FRIDAY. SOUTHEAST FLOW DEVELOPS FRIDAY NIGHT INTO SATURDAY. INSTABILITY DRIVEN BY DIURNAL HEATING PRODUCES ISOLATED TO SCATTERED CONVECTION. && .NEAR TERM /THROUGH FRIDAY/... PITTSBURGH AND BLACKSBURG SOUNDINGS CAME IN THIS MORNING WITH EXTENSIVE CAPE ABOVE THE BOUNDARY LAYER FROM THE 12Z TIME FRAME...SO WE WERE SET UP FROM THE START FOR CONVECTION FROM AN INSTABILITY PERSPECTIVE. MOISTURE HAS ALWAYS BEEN THE LIMITING FACTOR AS WELL AS ANY REASONABLY ORGANIZED FLOW. THE RESULT IS ISOLATED TO SCATTERED COVERAGE...EXPECTED TO BE HIGHEST OVER THE HIGHER ELEVATIONS TO THE EAST AND IN THE OHIO VALLEY. EXPECT CLOUDS TO DISSIPATE OVERNIGHT...BUT HOLD ONTO LOW END POPS FOR THE MAJORITY OF THE OVERNIGHT. WILL NOT TAKE MUCH TO FIRE A STRAY SHOWER OR STORM. AREAS THAT CLEAR AND RECEIVE ANY RAINFALL WILL HAVE A BETTER CHANCE AT VALLEY FOG. THE GREAT LAKES TO THE MID ATLANTIC WILL CONTINUE TO EXHIBIT WEAKNESSES IN THE 500MB RIDGE THAT HAS BEEN PARKED OVER THE AREA...LEADING TO VERY LITTLE CHANGE IN THE SENSIBLE FORECAST FOR FRIDAY. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... BROAD AREA OF LOW PRESSURE IS CAUSING WEAK FLOW GIVING WIDELY SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS FOR FRIDAY AND SATURDAY. THESE WOULD BE SLOW MOVERS...WITH A LOCAL DOWNPOUR. OVERALL THOUGH...THE AREA REMAINS IN A RELATIVELY DRY PATTERN THROUGH LABOR DAY AND SHOWERS MAY EVEN BE HARD PRESSED TO FORM ON LABOR DAY AS A WEAK LOBE OF HIGH PRESSURE NUDGES IN. WEAK VORT MAXES CONTINUE TO LINGER IN THE REGION...BUT THEIR WHEREABOUTS ARE ERRATIC AND DIFFICULT TO PREDICT. && .LONG TERM /MONDAY THROUGH THURSDAY/... 12Z GFS SOLUTION WAS FASTER THAN THE 12Z ECMWF WITH A SHORT WAVE AND ASSOCIATED SURFACE FRONT TRYING TO DENT THE RIDGE BY DAY 7/TUESDAY. AT THIS DISTANCE IN TIME...WILL NOT JUMP ON THE FASTER SOLUTION BUT STILL HAVE CHANCE POPS IN SE OHIO AND NORTHERN WV TUESDAY AFTERNOON AND EVENING. TRIED TO HOLD MAXIMUM TEMPERATURE DOWN A BIT FOR DAY 4/SATURDAY IN THE SOUTHEAST UPSLOPE AREAS...OTHERWISE NO MAJOR CHANGES. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... ISOLATED TO SCATTERED CONVECTION NOW FIRING ACROSS THE AREA WARRANTING VCTS FOR THE 19Z TO 23Z PERIOD. NO PREVAILING TSRA IN THE TAFS FOR NOW...WHICH SHOULD IN THEORY LEAD TO A FOG FORECAST SIMILAR TO CONDITIONS LAST NIGHT. HOWEVER...CLOUD COVER REMAINS A CHALLENGE IN THIS ENVIRONMENT...AND IF TERMINALS RECEIVE RAIN AFTER A PROLONGED DRY PERIOD...FOG TIMING COULD CHANGE AND INCREASE. MORE CONVECTION EXPECTED FRIDAY...ISOLATED TO SCATTERED...IN THIS PERSISTENT PATTERN. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND COVERAGE OF FOG TONIGHT MAY VARY FROM FORECAST. MAY NEED AMENDMENTS AND TEMPOS IF STORMS FORM/MOVE TOWARDS TERMINALS. 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 M 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 M H M PKB CONSISTENCY H H H H H H H H H M M M CKB CONSISTENCY H H H H H H H H H H M M AFTER 18Z FRIDAY... IFR POSSIBLE IN VALLEY FOG FRIDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...26/JW NEAR TERM...26 SHORT TERM...JW LONG TERM...FB/KTB AVIATION...26

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