Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 190551 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1251 AM EST Thu Jan 19 2017 .SYNOPSIS... High pressure pushes into the region tonight. However, active pattern continues, with a warm front crossing Friday, and then a stronger, double-barreled low pressure system early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 1240 AM Thursday... Several forecast challenges through the near term period. The first is the clouds through this morning. Currently have low stratus in place across much of CWA, however southern edge is slowly eroding. Continued this trend, relying fairly heavily on the 4kNAM. Even as the low clouds erode, cirrus is already spreading over the forecast area ahead of surface warm front and upper level negatively tilted trough that will arrive tonight. And that is the second forecast challenge -- timing precip with the system overnight. Did not make any huge changes to previous forecast, although did revise timing and tried to tighten the leading gradient used a blend of the 4kNAM and WRFnmm. Have an area of likely POPs entering from the SW around 00Z tonight, and transitioning NE across the forecast area overnight. Generally have 0.2-0.3 inches of rain with this. Held off on any mention of thunder due to the time of day, but with decent upper level support would not be overly surprised to get a rumble or two. Although it does look like better upper level support may be lagging behind by a couple hours. Expecting a mild day today, with the pattern of above normal highs continuing. Have temps dropping a little late this evening, but then rebounding some through the pre-dawn hours of Friday as WAA kicks in. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 410 PM Wednesday... Warm front pushes northeastward through the area Thursday night into Friday. Decent convergence along the front, and a 50 kt h85 feed will lead to another decent rainfall across the area, keeping soils soggy. The weather dries out southwest to northeast on Friday as the warm front pushes off to the northeast. Low level southwest flow and upper level ridging will then lead to a mild and dry start to the weekend. A major piece of energy coming eastward out of a long wave trough over the western U.S. approaches Saturday and Saturday night. A warm wave out ahead of this system is likely to bring rain, at least to southeast portions of the forecast area, by dawn Sunday. No important deviations from guidance on temperatures, as the January thaw continues. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 410 PM Wednesday... There is general model agreement not only through the extended period, but even out to day ten, when a trend back to colder weather is progged. A distant early signal of this pattern change may be in trends with a major system progged to impact the area early next week. A large upper level low is now progged to move eastward across the gulf states Sunday through Monday, undercutting the east coast ridge, rather than lifting northeastward into it while opening up and dampening out. While the system will not have access to any new cold air, the forecast solution is trending colder by Monday afternoon given a stronger cyclone from the surface through the mid levels tracking farther south and east, now southeast of the forecast area. If these model trends continue, cold air being generated aloft via strong ascent could lead to snow across the very highest terrain as the system starts to pull out Monday night. A stronger closed upper level low tracking south of, rather than over or north of the area, also spells an increased potential for heavy precipitation. The system is actually progged as a double-barreled affair, with a lead warm wave bringing a decent rainfall event Sunday, and then the main low bring another copious shot of rain, at least mainly rain, Monday into Monday night. Will add HWO highlight for the potential for heavy rainfall that could become excessive, given saturated soils and yet another rain event in the short term. This energy is part of an ongoing train of systems with a history of bringing copious amounts of precipitation to the west coast and Cascades. The system pulls out quickly on Tuesday, as another large upper level low moves east across the U.S., pushing a cold front toward the area next Wednesday, day 7. Ridging building into the western states behind the large upper level low signals a pattern change, with the long wave trough position shifting to the eastern U.S, re-opening the door for cold air to come south out of central Canada. Temperatures close to time-averaged guidance, except pulled down toward latest deterministic guidance late Monday into Tuesday. Some of the raw model output shows snow across the highest terrain as early as Monday afternoon. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 1250 AM Thursday... To start the period, have mainly MVFR in low stratus. This will erode some from the south, but may lower some across the north. So have improving conditions through pre-dawn south, and ceilings lowering to IFR across the north. As the clouds break up across the south, may get some fog formation. Models not real excited about this at TAF sites, possibly due to cirrus already overspreading the area, but opted to include at least some MVFR fog at HTS and CRW. Relatively low confidence on this, and may go either way -- little to no fog or possibly dense IFR fog. Remaining low clouds will break up through the day. A warm front will lift through tonight with showers. For now will keep things MVFR, however could be brief IFR in heavier showers...mainly after 06Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of stratus deck clearing could vary. Fog may form overnight in areas where stratus clears. 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 01/19/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY H H H H M M M H M L H L HTS CONSISTENCY H H H H M M M M M H H M BKW CONSISTENCY M M H H L L L L M H H M EKN CONSISTENCY H H M H H M M M M L M L PKB CONSISTENCY H H H H H H M M M H H M CKB CONSISTENCY H H H H H M M M M H H M AFTER 06Z FRIDAY... IFR possible in rain late Thursday night into Friday, and then again at times Sunday through Monday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/MZ NEAR TERM...MZ SHORT TERM...TRM LONG TERM...TRM AVIATION...MZ

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