Area Forecast Discussion
Issued by NWS Charleston, WV

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647 FXUS61 KRLX 251353 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 953 AM EDT WED MAY 25 2016 .SYNOPSIS... Weak disturbances within ridge aloft today into Thursday. Ridge stronger Friday/Saturday. Southeast flow may eventually increase shower coverage Sunday into Monday...especially over mountains. && .NEAR TERM /THROUGH TONIGHT/... 950 AM update...tweaked sky and pop grids based on current trends. Otherwise...forecast appears to be on track. Previous Discussion... Seeing increases in dewpoints this today...topping the 60s in the western zones in the transition to a warmer and higher moisture content airmass. Now under the influence of weak ridging aloft...a couple of weak waves within the flow suggests convection today. But the upper level feature does not have much in the way of surface forcing...and mid and upper level moisture are expected to overspread the CWA simultaneously. These factors will limit the coverage today...with an early peak to the activity to the western zones because of the dampening of the upper level wave. There will be some CAPE out there...but little low level flow and the aforementioned clouds limit thunder activity. NAM indicates a few more weak disturbances this evening and tonight...so largely held low chances through the near term. POPS come up to chance late tonight with small scale frontogenesis developing over the northeastern zones. Held the western zones back a couple of degrees on the high temperatures today...and went slightly higher than guidance tonight on overnight lows. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... Certainly hard to grasp any significant feature and run with it. Will have to wait until these time periods get into the near term...and try to get more specific. So...as of now...hourly pops certainly can not get out of the chance range. Weak mid/upper level disturbances linger Thursday...before 500 mb heights increase slightly Thursday night into Friday. Most of the moisture plume in the lower Ohio Valley should remain to our west through Saturday. Yet...the precipitable water still jump back to around 1.25 inches Thursday and Friday. Then the southeast flow actually brings drier air aloft on Saturday...lowering the precipitable water. A weak flow dominates with afternoon and evening instability...so reserved the mention of thunder for the afternoon and evening hours. In the weak flow...tried to have the higher chance pops on Thursday over the mountain counties. On Friday afternoon and evening...some hints on both the 00z gfs and 00z nam that if some convective cells form the southern mountains...it may try to drift north...off the mountains into the southern lowlands. Figuring a breeze stirs overnight Thursday night in southeast Ohio...so have minimum temperatures a bit higher there. Otherwise... in the light winds...have minimum temperatures a bit below guidance in the hollers further south and east...but leftover clouds could hurt that thinking. We still have some 90 degree temperatures on Saturday...in the southern river valleys...as that mentioned drying aloft occurs. Of course...most official temperature sites in the lowlands have not reached 90 degrees yet this year. Due to a weak southeast flow...maximum temperatures along the eastern slopes...including the southern plateau around Beckley...are not forecast to be higher Saturday compared to Friday. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... Summer like weather is still on tap for the Memorial Day weekend. Upper level ridging holds into Sunday before drifting off the east coast. Have just the slight chance for the late day shower or thunderstorm Saturday, and then a better chance on Sunday as the ridge begins to drift east. As the ridge drift offshore, a weak upper level over the Carolinas this weekend will start meandering to the northwest. This may actually bring a developing tropical or subtropical feature inland. Models generally differ with the track and lose the system under the light upper level flow. Suffice it to say for now that the forecast gets a bit dirtier early next week, with a better chance for late day showers and thunderstorms and a non- negligible chance at night. Either way, the very warm and humid air remains in place through the period, and even beyond. The midnight shift coded 90 for Charleston for Saturday, which may be a touch aggressive, but the pattern and guidance are close enough to give it a chance. Overall, not much disparity between ongoing temperatures and guidance. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... VFR ceilings and visibilities prevail today despite the passage of a few weak upper level disturbances today and tonight. These may kick off showers...and in the isolated instance thunder...but chances are too low to warrant prevailing or TEMPO conditions in the TAF. Some low level VFR cumulus could form after 16Z...but expect mid and upper level moisture to increase through the day. This moisture will become the prevailing ceiling...especially in the evening and overnight. Clouds tonight will keep fog from forming. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Brief MVFR in a shower is possible. 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 10 11 12 13 14 15 16 17 18 19 20 21 EDT 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 CRW CONSISTENCY M M M H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY L L M H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z THURSDAY... No widespread IFR conditions expected. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...KTB/26 NEAR TERM...SL/AJV/26 SHORT TERM...KTB LONG TERM...TRM AVIATION...26

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