Area Forecast Discussion
Issued by NWS Charleston, WV

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607 FXUS61 KRLX 270232 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1032 PM EDT Wed Jul 26 2017 .SYNOPSIS... Low pressure system brings rounds of showers and thunderstorms, with heavy rain, Thursday through Friday. High pressure with cooler and less humid air follows for the weekend into next week. && .NEAR TERM /THROUGH THURSDAY/... As of 1030 PM Wednesday... No significant changes. As of 8 PM Wednesday... No significant changes. As of 210 PM Wednesday... Flat cu field mainly from I-77 to the east. Otherwise noted some CI working in from the northwest. An upper level wave sweeps south across the Great Lakes with mid level clouds expected to spread across the forecast area across the forecast area Thursday. Moisture in atmospheric column increases significantly by Thursday afternoon as forecast area comes under the influence of high PW plume. Think severe threat will be somewhat diminished due to high precipitable water values. Heavy downpours and gusty winds will be threat increasing from west to east in the afternoon hours. Latest model information has dipped most max temp values down a degree or two across the board for Thursday. The solution generally accepted since there will be more clouds than sun that could offset any warm air advection. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 315 PM Wednesday... General forecast pattern remains the same this period, although there are still timing and tracking differences in the axis of heaviest QPF with these features. Lead short wave out ahead of a strong upper low dropping southeastward thru the Great Lakes will drag a cold front eastward into the Ohio Valley Thursday. A low pressure center will then form and ride up the front to our west as the strong upper low drops southeastward thru the Great Lakes later Thursday and Friday. With anonymously high PW`s AOA 2 inches feeding northeastward ahead of the front and good dynamics, the result will be a large swath of heavy showers and thunderstorms along and ahead of the low and slow moving cold front. While it appears the severe thunderstorm threat has been reduced with all the expected clouds and less sheared environment, the heavy rain potential continues to be a real threat. Again, the axis of heaviest rains remain in question, as the the models target different parts of the area. With this uncertainty, will continue to highlight heavy rain potential in the Hazardous Weather product Thursday and Friday. Newer model runs show the upper low to be progressive enough for things to clear out Saturday morning. A cool season like Canadian high pressure system will build in behind the front later Friday and gain real control Saturday. Look for an abnormally cool and rainy Friday, and a cool but drier Saturday. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 335 PM Wednesday... A tranquil period under a dry northwest flow aloft with Canadian high pressure hanging around. There will be a slow increase in high temperatures each day with abundant sunshine, but it will be dry with still at or below normal temperatures. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... As of 8 PM Wednesday... Fog overnight tonight will be limited to the valleys of northeastern West Virginia, as a low pressure system approaching from the west brings increasing cloud. Have IFR only in the Tygart Valley and MVFR mist for CKB, PKB and possibly CRW /6SM coded there/. As the system moves in Thursday, the likelihood for showers and thunderstorms increases. Clouds and the near widespread coverage of the showers and thunderstorms limits the severe risk, but thunderstorms could still produce strong wind gusts, and any thunderstorm can bring IFR conditions in heavy downpours. Surface flow will generally be light south to southeast, while light southwest flow aloft tonight becomes light west to southwest for Thursday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY... FORECAST CONFIDENCE: Medium to high. ALTERNATE SCENARIOS: Formation and timing of fog could vary overnight, and the dissipation of fog can vary by an hour or two early Thursday morning. Timing of showers and thunderstorms, and associated flight categories, could vary on Thursday, with short term amendments likely needed. 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 THU 07/27/17 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 H H H H H H L HTS CONSISTENCY H H H H H H H H H H H L BKW CONSISTENCY H H H H H H M H H M M L EKN CONSISTENCY H H H M M M M M M L L L PKB CONSISTENCY H H H H H H H M M M M L CKB CONSISTENCY H H H H H H H H M M M L AFTER 00Z FRIDAY... Brief periods of IFR conditions with thunderstorms likely Thursday night into Friday, perhaps more persistent in low clouds Friday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...KMC/TRM/JMV NEAR TERM...KMC/TRM SHORT TERM...JMV LONG TERM...JMV AVIATION...TRM

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