Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 182353 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 753 PM EDT Thu Apr 18 2019 .SYNOPSIS... Large storm system brings showers and a thunderstorms Friday, along with cooler conditions. Upper level low pressure system exits Sunday night. && .NEAR TERM /THROUGH FRIDAY/... As of 415 PM Wednesday... Bumped up temperatures this afternoon to account for local and regional observations depicting most areas extending up into the mid-80s. As of 155 PM Wednesday... Cold front approaches the region overnight and pushes through tomorrow. Widespread showers are expected as well as the possibility of a few thunderstorms, and some could be quite strong. Inhibiting factors for storms tomorrow will be instability. Current guidance indicates persistent cloud cover and on-going showers entering the region after sunrise Friday. CAPE values likely will be less than 500 J/kg, however wind profiles are impressive. So once again, we will have high shear and low instability, but if there are a few breaks of sun then maybe some low topped storms could develop. Main threat would be for damaging wind gusts. Meanwhile, PWATs are forecast to be about 1.3", which is slightly anomalous for this time of year. The fact that convection could be limited should help us from seeing rainfall rates that could produce flash flooding. Nonetheless, if afternoon convection were to develop across the mountains, where FFG values are lowest, then some water issues could pop up. At this time, decided to hold off from any flash flood watch after coordinating with surrounding WFOs. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 225 PM Thursday... No significant changes to the evolution of the upper low as it wobbles northeastward through the CWA. The Saturday time frame will have reduced POPs from the near term due to some likely dry air intrusion. While the forecast will not have an actual mention of thunder, the possibility is definitely there on Saturday with the steepening lapse rates from the cold pool aloft. Any thunder should be isolated overall. Conversely, the 1000-500mb thicknesses bottom out on Saturday at 536dkm, but there has developed some significant spread in the model guidance for the high temps Saturday. Had to bring down the blender values several notches as they looked to high. Expect wet snow showers in the highest elevations Saturday night. All precipitation effects from the upper low should end Sunday night. There is also more spread now in the forecast highs fir Sunday, as the exit of the upper low and recovering low level warm air advection may be pushed off another 12 to 18 hours. Still should be easily warmer than Saturday, but have backed off the near 70F lowland temps by several degrees. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 225 PM Thursday... Keeping the theme of some inconsistencies in the models and guidance, the nature of the baroclinic zone oscillation keeps the forecast from going categorically wet or dry in the extended. So as the features drifts south and north across the CWA in response to differing synoptic scale upper wave setups, it can be expected that the chances for showers and the temperatures through Wednesday are going to be in some flux over the next couple of days. With that said, not expecting any extremes at this point. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 750 PM Thursday... VFR remains the primary flight category this evening ahead of tomorrow`s FROPA. Gusty winds observed across all terminals today will begin to subside with the loss of daytime heating, with the exception of the mountain terminals of EKN and BKW, where gusts are likely to continue through the overnight period. Winds aloft begin to increase tonight in response to the next approaching low pressure system, which could pose an issue for low level wind shear for many TAF sites during the predawn hours Friday morning. Therefore, included a period of LLWS at all sites except for PKB and EKN. Confidence on timing and locations of wind shear are still mediocre at best, but may become more clear with the 06Z TAF issuance on whether or not ground winds would be conducive to justify wind shear. Either way, low level turbulence is anticipated Friday morning due to increasing winds aloft. The cold front pressing in from the west will enter into the forecast region near daybreak Friday morning. Heavy rain and afternoon thunderstorms will accompany the front, leading to MVFR/IFR flight restrictions at times through the remainder of the period. Winds will once again be gusty after sunrise, once the nocturnal inversion erodes, as well as shift out of the northwest in the wake of the front`s passage late in the TAF period. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... ALTERNATE SCENARIOS: Timing and location of LLWS early Friday morning may vary from forecast. Flight restrictions in regards to showers and thunderstorms passing through the area will also vary at all terminals. 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 04/19/19 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 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 H H H 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 00Z SATURDAY... IFR possible in showers and thunderstorms late Friday night, with additional brief IFR in showers over the weekend. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/MPK NEAR TERM...MPK/MEK SHORT TERM...26 LONG TERM...26 AVIATION...MEK is the U.S. government's official web portal to all federal, state and local government web resources and services.