Area Forecast Discussion
Issued by NWS Charleston, WV

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733 FXUS61 KRLX 210642 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 242 AM EDT Mon Aug 21 2017 .SYNOPSIS... High pressure into Tuesday. strong cold front late Tuesday/Tuesday night. Cooler and drier high pressure into the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 PM Sunday... Updated to include isolated shower mention from PKB north and west. A few showers have popped up recently. They are already falling apart as they drift northward so stayed in isolated range. These appear to have formed along a low level boundary that is likely the outflow from the thunderstorms that moved across the far northern CWA Saturday evening. As of 120 PM Sunday... Weak high pressure keeps the CWA dry and warm today. A minor impulse at 500 mb passes to our north overnight though trended towards SREF and GFS ensembles keeping the forecast dry. There should be fog again in the river valleys overnight though the impulse and a full day of sun today may lessen the density and extent overnight. Despite this, still kept a general mention of fog in the river valleys. Monday high pressure holds on albeit weakly, but should be enough to keep us dry again with minimal cloud cover except in the mountains where daytime heating may be enough to spark a few isolated showers. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 225 AM Monday... As the uppe level trough digs into the Great Lakes, there will be two actual cold front pushing through the Ohio Valley and the mountains. The first will carry the primary line of convection with it, and the second will be the main player in ushering in the Canadian airmass. SPC carries the slight risk for the bulk of the area Tuesday and Tuesday night, but the instability profiles suggest that the best chances for thunder will exist before 02Z, as CAPE drops off sharply into the Tuesday night period. Better low level jet dynamics exist further north and east, but the NAM is hinting at a modest streak pushing in from the west. Coarse NAM also indicates good large scale ascent in the upper levels of the atmosphere in the right rear quadrant of the 300mb jet for the northwestern zones. Airmass changing flow out of the northwest moves into southwest Ohio after 06Z Wednesday. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 225 AM Monday... 850mb temperatures drop 7-9C in the wake of the cold fronts, taking temperatures for the lowlands back into the mid to upper 70s for the end of the week. Dominant ridge/trough pattern from the western to eastern CONUS will continue to shape the weather through the extended. Surface high keeps the bulk of the long term dry, with chances slightly increasing for day 6 and 7. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... 06Z Monday thru 06Z Tuesday... As of 135 AM Monday... With an upper impulse and great cirrus coverage to combine with more tropical like dewpoints, will cut back just a bit on timing and intensity with river valley LIFR fog coverage early this morning, but most sites will still see at least some IFR fog between 09Z and 12Z. Thru 00Z Tuesday... Fog will dissipate quickly after sunrise. then VFR. Generally thin cirrus clouds this morning followed by SCT-BKN clouds 4500-6000 feet AGL this afternoon. An isolated shower this afternoon is possible across east facing slopes of the northern mountains due to elevated heat source and pooling of low level moisture there, and across parts of southeast OH with an upper disturbance. Light and variable wind early becoming southwest 3 to 7 KTS this afternoon. After 00Z... VFR with mainly thin cirrus with any river valley fog holding off til after 06Z and not as much as this early morning. Winds light and variable. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z TUESDAY... FORECAST CONFIDENCE: High, except low to medium with fog. ALTERNATE SCENARIOS: Timing and density of fog may vary based mainly on clouds. 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 MON 08/21/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H M M L L L L M H H H M HTS CONSISTENCY H H H M M L L M H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY M L L L L L L M H H H M PKB CONSISTENCY H H M M L L M H H H H M CKB CONSISTENCY H H H M M M H H H H H M AFTER 06Z TUESDAY... Dense river valley fog possible each morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JMV/26 NEAR TERM...JW/MZ SHORT TERM...26 LONG TERM...26 AVIATION...JMV

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