Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 280008 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 808 PM EDT THU AUG 27 2015 .SYNOPSIS... HIGH PRESSURE IN VICINITY OVERNIGHT. WARMING TREND FRIDAY INTO SATURDAY. MORE HUMID SUNDAY INTO EARLY NEXT WEEK...WITH THE POSSIBILITY OF SHOWERS RETURNING...ESPECIALLY ON SUNDAY. && .NEAR TERM /THROUGH FRIDAY/... 800 PM UPDATE... STRATOCU MORE OF A DIURNAL NATURE COMPARED WITH LAST EVENING...AND THUS LESS TENACIOUS. WITH THE CLOUDS DISSIPATING...THE FCST IS ON TRACK. PREV DISCN... AT 18Z...STRATOCUMULUS AROUND 4 TO 5 THSD FT AGL...UNDER THE SUBSIDENCE INVERSION LOCATED AT 6 TO 10 THSD FT AGL. STRATOCU IS MOST WIDESPREAD FROM PA SW...INTO OHIO...LEAST IN SOUTHERN WV AND SOUTHWEST VIRGINIA. CLOUDS SHOULD CONTINUE TO THIN AND FLATTEN DURING THE 18Z THU TO 00Z FRIDAY TIME FRAME. NO REASON TO CHANGE THE RIVER VALLEY FOG FORMING LATE...AFTER 06Z. FIRST IN THE COOLER MOUNTAIN VALLEYS AROUND EKN ON DOWN INTO THE UPPER GUYANDOTTE... UPPER TUG AND UPPER BIG SANDY...THEN LATER IN THE LOWER KANAWHA VALLEY AND OHIO VALLEY. THERE IS THE DILEMMA OVERNIGHT...ENOUGH MOISTURE LINGERS AROUND 5 THSD FT AGL...YOU CAN NOT RULE OUT SOME PATCHES OF DEAD STRATOCUMULUS LINGERING OR REFORMING. THAT WOULD DISRUPT THE VALLEY FOG FORMATION. ALSO SOME SE FLOW STIRS OVERNIGHT ON MOUNTAIN RIDGES AND SOUTHERN PLATEAU AROUND BKW. FOR CONSISTENCY...WILL LEAVE THE 15 TO 20 POP NEAR SNOWSHOE LATE FRIDAY AFTERNOON...FOR A MOUNTAIN THERMAL IN WEAK FLOW...BUT COLUMN APPEARS RELATIVELY DRY. 850 TEMPS WARM ABOUT 4 C BETWEEN THIS AFTERNOON TO FRIDAY AFTERNOON. NO MAJOR CHANGES TO MAXIMUM TEMPERATURE FORECAST FOR FRIDAY. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... UPPER RIDGE AND GENERAL SUBSIDENCE HOLDS OVER THE AREA. MOST AREAS WILL REMAIN RAIN FREE DESPITE INCREASING HEAT AND HUMIDITY. THE TARGET AREA FOR ANY AFTERNOON SHOWER WILL BE THE ELEVATED HEAT SOURCE IN THE MOUNTAINS. TEMPERATURES WILL APPROACH 90 DEGREES SATURDAY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE MAIN CHANGE TO THIS PERIOD WILL BE A STRONGER UPPER DISTURBANCE FROM THE LOWER MISSISSIPPI VALLEY LIFTING NORTHEAST ACROSS THE AREA SUNDAY AND SUNDAY NIGHT...ENHANCING THE POTENTIAL FOR SHOWERS AREA WIDE IN THE VERY WARM AND HUMID AIRMASS IN PLACE. THIS PERIOD STILL SHOWS A BERMUDA HIGH OVER THE WESTERN ATLANTIC EXPANDING WESTWARD. THIS EVOLVES INTO A WELL DEFINED UPPER RIDGE HOLDING OVER THE WESTERN U.S. AND A BUILDING UPPER RIDGE OVER THE WESTERN ATLANTIC...LEAVING A WEAK UPPER TROUGH BETWEEN THESE UPPER RIDGES OVER THE EASTERN U.S.. WITH THE SURFACE HIGH CENTER ALSO BUILDING OFF THE SOUTHEAST COAST...MOISTURE AND HEAT WILL CONTINUE TO INCREASE ON A SOUTHERLY FLOW REGIME THIS WEEKEND INTO EARLY NEXT WEEK. THIS WILL GIVE RISE TO A CHANCE OF MAINLY A DIURNAL SHOWER OR THUNDERSTORM...ESPECIALLY IN THE MOUNTAINS...AND ESPECIALLY SUNDAY AS A VERY WEAK UPPER DISTURBANCE LIFTS NORTHEAST FROM THE GULF STATES. TEMPERATURES WILL GENERALLY APPROACH 90 DEGREES EACH DAY WITH RATHER HUMID CONDITIONS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... STRATOCU MORE OF A DIURNAL NATURE COMPARED WITH LAST EVENING...AND THUS LESS TENACIOUS. WITH THE CLOUDS DISSIPATING...THERE IS NO REASON TO CHANGE THE RIVER VALLEY FOG FCST...OTHER THAN HASTENING THE TIMING BACK TO AROUND 06Z. THE FOG WILL FORM FIRST IN THE COOLER MOUNTAIN VALLEYS AROUND EKN ON DOWN INTO THE UPPER GUYANDOTTE... UPPER TUG AND UPPER BIG SANDY...THEN LATER IN THE LOWER KANAWHA AND MIDDLE OHIO VALLEYS...INCLUDING CRW...PKB...AND HTS. STILL CANNOT RULE OUT MOISTURE LINGERING AROUND 5 THSD FT AGL...RESULTING IN PATCHES OF DEAD STRATOCU OVER THE MOUNTAINS. THAT...ALONG WITH A LIGHT S FLOW STIRRING ON MOUNTAIN RIDGES AND SOUTHERN PLATEAU AROUND BKW...COULD DISRUPT THE VALLEY FOG FORMATION. A REPEAT OF THE DENSE FOG AT BKW LAST NT IS NOT EXPECTED OVERNIGHT TONIGHT. LIGHT AND VARIABLE SFC FLOW...NEARLY CALM OVERNIGHT...WILL TREND FROM NE TO SE ON FRI. LIGHT E FLOW ALOFT WILL SHIFT TO S OVERNIGHT AND BE LIGHT S TO SW ON FRI. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF DENSE RIVER VALLEY FOG 06Z TO 13Z FRI COULD VARY. 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. DATE FRI 08/28/15 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H M M M L L L L HTS CONSISTENCY H H H H H M L L L L L L BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H M M L L L L PKB CONSISTENCY H H H H H H H H M L L L CKB CONSISTENCY H H H H H H H H M L H H AFTER 00Z SATURDAY... IFR IN VALLEY FOG POSSIBLE 06Z TO 13Z SATURDAY. LESS LIKELY SUNDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/TRM/JMV NEAR TERM...KTB/TRM SHORT TERM...JMV LONG TERM...JMV AVIATION...KTB/TRM

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