Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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945 FXUS63 KJKL 251953 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 353 PM EDT Wed Sep 25 2024 .KEY MESSAGES... - Showers and thunderstorms could result in heavy rain and isolated flooding through tonight. - The remnants of tropical system Helene are forecast to bring a widespread, soaking rain event later in the week. - Flash flooding could result from the remnants of Helene, but the potential may be limited by the quick movement of the system. - High temperatures will average near normal the rest of the week. && .UPDATE... Issued at 1236 PM EDT WED SEP 25 2024 Hourly grids were freshened up based on recent observations and radar trends. This led to only minor adjustments to temperatures and dewpoints, while pops across the southeastern portions of the CWA near the VA border were increased per radar trends as well as trends of recent CAMS. && .SHORT TERM...(Today through Thursday) Issued at 608 AM EDT WED SEP 25 2024 A large upper low will drop slowly south from the mid Mississippi Valley during the period, becoming more closed with time. Our flow aloft will initially be from the southwest, still pulling deep moisture over our area, and continuing showers/thunderstorms at times for most places today and tonight. Clouds and precip will limit destabilization today and keep the severe weather threat much lower than on Tuesday. As we move into the day Thursday, tropical system Helene moving north through the eastern gulf will interact more strongly with the mid latitude upper low to our west. Our flow aloft will turn toward the southeast while low level flow sets in from the east. Even though precipitable water is expected to increase to near 2" by evening, the downslope wind components will probably work to limit precip amounts until Helene gets closer in the long term period. .LONG TERM...(Friday through Wednesday) Issued at 352 PM EDT WED SEP 25 2024 The forecast period begins with the area beginning to feel the impacts from the remnants of Helene. The hurricane is expected to make landfall on the Florida Panhandle Thursday evening and through the overnight hours quickly track north-northwestward toward the Commonwealth. By the start of the extended forecast window, the NHC has Tropical Storm Helene moving up the spine of the Appalachian Mountains but getting sheared apart by frictional forces from the mountains. The bulk of the remnants are expected to take a hard westerly turn to the northwest and fizzle out and get absorbed into a cut-off upper-level closed circulation. However, before that occurs, wind and rain will pound the entire CWA starting Thursday night and persisting through Saturday morning. Total QPF through the duration of Helene is expected to range from 1.00" to 1.50" along the eastern mountains to upwards of almost 2.00" to 3.00" along and west of the I-75 corridor. The easterly flow across the southeastern mountains will create a rain shadow effect for counties along the mountains and diminish overall QPF; however, the further away from the mountains; the less impact rain shadowing has on the QPF. Near high wind warning criteria winds are expected across the high terrain of the eastern mountains with sustained winds approaching 20 mph in the lower elevations are expected through Friday evening. Higher upper-level winds exist; however, with no widespread convection or mechanism to translate those winds to the surface, those winds will remain aloft. Through the evening Friday into Saturday, Helene will drift west-northwest toward western Kentucky and eventually be absorbed into a closed circulation that`s been largely stationary all week. After the merging of the closed circulation and the remnants of Helene takes place, the closed circulation will continue to aimlessly spin over the Commonwealth and keep persistent chances of showers and thunderstorms through the weekend. Models continue to remain in rather good agreement going into next week with the circulation getting picked up by the mean flow and ejecting out of the area by Monday morning but lingering PoP chances will exist through the end of the period as an upper-level trough, moving through southern Canada, drags a cold front through the region Tuesday afternoon which will then usher in cooler and drier weather for the middle of next week. Overall, the forecast period will be highlighted by multiple rounds showers and thunderstorms. The remnants of Helene will bring the best chances through Friday afternoon before the closed circulation keeps PoP through the middle of next week. Temperatures through the period will remain rather seasonal as highs are forecast to in the upper-60s to upper-70s. Overnight lows, will be warmer with the approach of Helene but with the approach of a cold front on Tuesday, cooler temperatures and fall-like weather will be in place for the end of the period. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 221 PM EDT WED SEP 25 2024 A mixture of mainly MVFR and VFR was reported at issuance time, though IFR was reported in and near some of the heavier showers. Showers and storms are expected from time to time through the period. The prevailing MVFR or lower should prevail the longest nearer the VA border during the first 6 hours of the period. A couple of hours of MVFR or lower ceilings are probable at the TAF sites to begin the period with the exception of KSME. A general deterioration to MVFR is expected from southeast to northwest between 00Z and 12Z with some IFR while MVFR should generally prevail for most areas from 12Z to 18Z. Winds will be light and variable. && .JKL WATCHES/WARNINGS/ADVISORIES... High Wind Watch from Thursday evening through Friday evening for KYZ087-088-118. && $$ UPDATE...JP SHORT TERM...HAL LONG TERM...VORST AVIATION...JP