Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 171817 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 217 PM EDT WED SEP 17 2014 .SYNOPSIS... HIGH PRESSURE THROUGH THE WEEKEND. COLD FRONT POSSIBLY TOWARD THE END OF THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... UPDATE... FOG NOW LIFTING INTO A STRATUS DECK...AND WILL BE STUBBORN TO ERODE. EXPECT THE EDGES OF THIS DECK OVER THE OHIO VALLEY TO START DISSOLVING AS HEATING COMMENCES AND WE DRY OUT THE LOWEST LAYER FROM A RELATIVE HUMIDITY PERSPECTIVE. PREVIOUS DISCUSSION... AREAS OF DENSE FOG AND LOW STRATUS WILL GRADUALLY DISSIPATE BY MID OR LATE MORNING. BROAD HIGH PRESSURE WILL CONTINUE IN CONTROL TO PRODUCE MOSTLY CLEAR AFTERNOON AND EVENINGS THROUGH AT LEAST SATURDAY. NEAR CALM FLOW IN THE BOUNDARY LAYER AND MOSTLY CLEAR SKIES WILL PRODUCE AREAS OF DENSE FOG ONCE AGAIN OVERNIGHT TONIGHT INTO EARLY THURSDAY MORNING. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... VERY QUIET PATTERN WITH SURFACE RIDGE CENTERED OVER QUEBEC THURSDAY NIGHT AND VERY BROAD UPPER LEVEL TROUGHING ACROSS THE EASTERN HALF OF NORTH AMERICA. ON FRIDAY THE SURFACE RIDGE WILL SHIFT EAST TO BE CENTERED JUST OFFSHORE OF MAINE WHILE AN UPPER LEVEL LOW FORMS OVER THE SOUTHEASTERN US. MODELS ARE SHOWING MOISTURE FROM THIS UPPER LEVEL LOW CREEPING NORTH UP THE APPALACHIANS SO HAVE INCLUDED SLIGHT CHANCE POPS IN THE MOUNTAINS. DRY WEATHER WILL PREVAIL FRIDAY NIGHT AND SATURDAY AS UPPER LEVEL TO THE SOUTH GETS PUSHED EAST AND OFFSHORE. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... USED WPC THINKING WITH SOME MINOR TWEAKS. COLD FRONT WILL PUSH SOUTHEAST ON SUNDAY WITH HIGH PRESSURE TAKING CONTROL BY MONDAY. THE HIGH SHOULD REMAIN IN CONTROL THROUGH THE REMAINDER OF THE PERIOD. WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... WEAK TROUGH AXIS ALOFT WILL GENERATE ENOUGH LIFT FOR SOME MID LEVEL CLOUD FORMATION TONIGHT...WHICH SHOULD BE ENOUGH TO PLAY HAVOC WITH THE AVIATION/FOG FORECAST. CLOUDS WILL INCREASE AFTER 03Z...BUT GUIDANCE NUMBERS DO NOT SEE ENOUGH THERE TO KEEP LIFR CONDITIONS FROM FORMING. WITH NEARLY IDEAL CONDITIONS FOR RIVER VALLEY FOG FORMATION OTHERWISE...A TUG OF WAR WILL ENSUE. GIVEN THE QUICKNESS AND THICKNESS OF THE VALLEY FOG EARLIER THIS MORNING UNDER SIMILAR CONDITIONS LESS THE AFOREMENTIONED PASSING CLOUDS...WILL KEEP THE LIFR IN THE FORECAST FOR TONIGHT. THE RH SIGNATURE IS NOT STRONG PER SE...AND IS BETTER SEEN ON THE NAM BUFR SOUNDINGS ABOVE 7KFT. HOWEVER...THIS WEAK TROUGH AXIS IS EVIDENT ON BOTH THE NAM AND THE GFS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: GOING WITH MEDIUM CONFIDENCE GIVEN THE THICKNESS AND COVERAGE OF THE MID LEVEL DECK TONIGHT. 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 L L HTS CONSISTENCY H H H H H H H H H H M 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 L L PKB CONSISTENCY H H H H H H H H H H M L CKB CONSISTENCY H H H H H H H H H H M M AFTER 18Z THURSDAY... IFR RIVER VALLEY FOG EXPECTED DURING THE PREDAWN HOURS FRIDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/50 NEAR TERM...ARJ/26 SHORT TERM...JR LONG TERM...JSH AVIATION...26

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