Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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821 FXUS63 KJKL 170654 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 254 AM EDT Tue Sep 17 2024 .KEY MESSAGES... - A cool-down arrives for Tuesday, with a warming trend expected through the remainder of the week. - A potential for showers arrives from the east tonight into Tuesday. Additional shower (and possible thunderstorm) chances will occur through midweek. && .UPDATE... Issued at 1211 AM EDT TUE SEP 17 2024 Only minor changes have been made as obs were blended into the forecast. UPDATE Issued at 819 PM EDT MON SEP 16 2024 Have updated sky cover to go with a little bit faster increase in high clouds tonight. Otherwise, the forecast is unchanged. && .SHORT TERM...(This evening through Tuesday night) Issued at 505 PM EDT MON SEP 16 2024 Observations and satellite show bright sunshine fading this afternoon as a cloud shield, associated with low pressure coming ashore near Myrtle Beach, SC, advances westward. Thermometers show temperatures ranging from the mid 70s to around 80 near/east of US-23 to the mid 80s west of I-75 and near/north of I-64. At elevations above 2,500, temperatures are mainly in the 60s. Regional radar has at times shown some weak reflectivity echoes associated with a thicker mid-level cloud deck drifting into far eastern Kentucky, perhaps leading to some virga. Dewpoints range from the 40s near and northeast of KY-15 to mid 50s further southwest. This first surge of Atlantic moisture from the coastal low will raise PWATs back above 1 inch across the two tiers of counties adjacent to VA and WV this evening. Most echoes on radar should be virga, though the strongest of echoes could perhaps lead to a few sprinkles, warranting mention in Pike and adjoining county forecasts. The cloud shield will overspread the remainder of the JKL CWA this evening. As the coastal low drifts toward the Southern Appalachian mountains overnight, a stronger surge of deep moisture (PWATS above 1.5 inches) and attendant 500H vorticity lobe crosses over the Central Appalachians, likely causing a light to moderate rain band to reach the VA-KY border around or after 6z. Tonight`s lows are forecast to range from the mid 50s to lower 60s tonight, a few degrees warmer than last night due to cloud cover and, for some, rainfall. The deeper moisture will continue to spread westward during the morning hours on Tuesday but lingering dry air over Central Kentucky and diminishing forcing aloft will likely lead to a sharp cutoff in rainfall, perhaps near/north of I-64 and near/west of I-75. Once the initial band clears the forecast area during the first part of the day Tuesday, additional spotty showers (20-50% chance, highest northeast of KY-15) are possible during the afternoon. A rumble of thunder cannot be entirely ruled out as well, though abundant cloud cover will limit daytime heating and instability. The lack of sun will also keep maximum temperatures noticeably cooler, mainly in the upper 60s to mid 70s. The dissipating coastal low`s remnants continue to approach on Tuesday night, keeping plenty of cloud cover and a low probability (mainly under 30% chance) of showers over the area. Overnight temperatures remain mild, holding mainly in the lower to middle 60s. Rainfall totals through Tuesday night are forecast to range from 0.5 to 0.7 inches near the Virginia/Kentucky border to 0.1 inch or less west of I-75 and north of I-64. Given ongoing dry conditions across much of eastern Kentucky, this rainfall should be highly beneficial. .LONG TERM...(Wednesday through Monday) Issued at 427 PM EDT MON SEP 16 2024 The models start off in good agreement through the remainder of the work week. By the start of the extended on Wednesday morning, the low that is currently affecting the southeast Atlantic Coast will have moved inland and will be sitting over the Southern Appalachian region. Here the troughing will remain for the next few days. With deep north flow across the region, this will result in cooler temperatures for a couple of days. The system to our east will also provide a daily chance of showers and thunderstorms. These chances will increase as you head farther east towards West Virginia and Virginia. Not overly impressed with the instability however. Models have the precip ending by Friday, as the system starts to pull farther northeast. Despite continued northerly flow aloft, temperatures will begin moderating a bit warmer each day, leading to a warming trend to end out the work week Thursday and Friday. For the weekend, there is still quite a bit of disagreement in the models. Both the GFS and ECMWF show rising heights across the region as a strong upper level ridge builds in the from the far southern Conus. However, with the trough now just off the Atlantic Coast, the ECMWF tries to keep some level of troughing across the eastern portion of the state through the weekend, while the GFS keeps a ridge in place instead. The ECMWF continues to strengthen this system over the Atlantic, while the GFS takes it much farther north and away from the Mid-Atlantic Seaboard. For sensible weather, this pattern would promote a potential for isolated/scattered showers and thunderstorms in Kentucky according to the ECWMF solution. Meanwhile, the GFS is dry. By Monday, the ECWMF has the system and moisture really ramping up across the Atlantic, pulling moisture eastward and away from Kentucky. However, the GFS shows a shortwave and potential frontal system nearing the state from the west, which would increase precip during the day Monday. Very different solutions with not a lot of confidence in either. As such, just stuck with the NBM at this point. It is favoring a dry solution through the weekend, then introduces slight chance pops again on Monday - closer to the GFS solution. This is very late in the period, granted, so do expect these model solutions and therefore the forecast to change. The current forecast is for temperatures in the low to mid 80s during the weekend, warmest on Saturday - however this may also change some as one model solution becomes favored. Don`t expect a huge increase or decrease, but possibly a few degrees either way. Overnight temperatures should remain fairly steady through the extended with clearing skies and light winds allowing for good radiational cooling. Lows will generally be in the mid and upper 50s, coolest in the deeper valleys. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 239 AM EDT TUE SEP 17 2024 Clouds are thickening with light rain developing, expected to slowly spread from southeast to northwest overnight and early Tuesday. This will lead to worsening conditions, with a mix of MVFR and IFR conditions developing northwestward over the region from about 09Z-18Z. Winds will mostly be from the northeast at less than 10 kts. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...GEERTSON LONG TERM...JMW AVIATION...HAL/GINNICK