588 FXUS63 KJKL 302049 AFDJKLAREA FORECAST DISCUSSION National Weather Service Jackson KY 449 PM EDT Tue Sep 30 2025
.KEY MESSAGES...
- Some moisture around the outskirts of Tropical Storm Imelda`s circulation could produce a few rain showers in Southeastern Kentucky into this evening.
- Dry and seasonably warm conditions return on Wednesday and then persist into early next week.
- Valley fog is likely to develop each night this week in the deeper river valleys of eastern Kentucky.
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.SHORT TERM...(This evening through Wednesday night) Issued at 232 PM EDT TUE SEP 30 2025
As of the 15Z surface analysis, the map is relatively quiet, with the majority of significant activity centered around the two offshore hurricanes. A dry cold front is currently oriented from the mid-Atlantic westward to the northern Plains. Locally, conditions are quiet as the forecast area is situated between surface high pressure centered over northern Missouri and the aforementioned tropical activity. However, high-level cirrus clouds associated with the two hurricanes are streaming overhead.
Throughout the remainder of the day and extending through much of the forecast period, the surface high-pressure system will shift eastward and become the dominant synoptic feature, leading to predominantly dry conditions. Despite this, sufficient upper-level forcing and instability remain to support isolated showers and thunderstorms this afternoon across portions of far southeastern Kentucky. As the forcing mechanisms shift eastward and diurnal heating wanes, these showers and storms are expected to dissipate, leading to a quiet overnight period.
Maximum temperatures today and Wednesday are forecast to reach the upper 70s to lower 80s. Upper-level northerly flow will advect drier air into the region, resulting in lower dew points, which represents the most significant deviation from the NBM throughout the forecast window. With decreasing cloud cover expected later this evening, clearing skies overnight will allow for effective radiational cooling, increasing the potential for localized dense fog formation within river valleys both tonight and tomorrow night. Overnight minimum temperatures are expected to fall into the low to upper 50s.
.LONG TERM...(Thursday through Tuesday) Issued at 440 PM EDT TUE SEP 30 2025
The period is expected to begin with an upper level trough extending into the Southeast Conus and portions of the Gulf while an upper level ridge is progged to be in place across the OH and TN Valleys and into the Appalachians, eastern Great Lakes, and Mid Atlantic States. A shortwave trough is expected to extend from the Upper MS Valley toward the Ozarks while another upper ridge should be centered over NM and extend into Parts of the Southern Plains as well as Southern Rockies to Central Plains. Further west, the axis of an upper level trough should extend south west of the west coast of the COnus from an upper low nearing the BC coast and the Pacific Northwest. At the surface, the period should begin with a sfc high centered over Quebec/St Lawrence Valley and extending southwest toward the mid MS Valley and down the eastern seaboard while weak inverted troughing should extend from LA and into the Commonwealth.
From Thursday to Friday night, upper level ridging per the consensus of guidance should become centered form the OH Valley to the mid Atlantic coast while weak upper troughing remains over parts of the Southeast to the central and eastern Gulf with a stronger upper ridge extending from Mexico into the Southern Plains to mid MS Valley region. Further west, the upper trough should move into and across portions of the western Conus and reach the Northern Rockies to Great Basin to AZ by late Friday night. By late Friday night, a weak upper low may develop over the Lower MS Valley vicinity. Meanwhile, the sfc ridge should become centered further south over the mid Atlantic states into the Southern Appalachians. For eastern KY, this scenario will favor dry and mild weather with temperatures a few degrees above normal. Valley fog, perhaps areas of fog, especially along rivers, larger creeks, and area lakes should be a fixture each night through a couple of hours after sunrise each day.
Saturday to Sunday night, upper level ridging is expected initially to extend from the Atlantic into VA and Carolinas to OH Valley while an upper level low is expected in the Lower MS Valley to western Gulf areas while an upper level trough spreads from the western Conus into parts of the Central to Northern Plains. The weak upper level low should meander over the Northern Gulf to Lower MS Valley vicinity while the axis of upper level ridging should become centered east of the coast of the Carolinas. The 12Z ECMWF operational run maintains a stronger ridge and higher heights into eastern KY as compared to the most recent GFS operational run while both also bring an upper level trough into the upper MS Valley that nears the Great Lakes. This leads to differences in how quickly moisture returns into eastern KY. More recent GFS would support enough moisture return for a few showers possibly encroaching the TN border to VA border counties Sunday night. Either scenario favors above normal temperatures continuing into the weekend and dry weather for most of if not all the weekend. Valley fog, especially along rivers, larger creeks, and area lakes should be a fixture each night through a couple of hours after sunrise each day. For now maintained the NBM pops that remained 10 percent or lower even into Sunday night and generally reflect the ECMWF runs more closely.
Monday and Tuesday, guidance generally has a series of shortwave troughs moving from the Plains across the Great Lakes to the St Lawrence Valley with a corresponding sfc frontal zone that gradually moves toward the Northeast, across the Great Lakes, and into the OH Valley. Guidance generally keeps an upper low over the western Gulf to Lower MS Valley vicinity to begin the week, but the GFS runs maintain deeper moisture and more moisture return across eastern KY into Monday compared to the ECMWF. That would support some shower chances Monday especially over the south while the ECMWF is drier has more of an increase in moisture and better chances for showers as the front nears later Monday night and Tuesday. For now have maintained the isolated to scattered pops of the NBM from late Monday night into Tuesday which are more toward the ECMWF end of the guidance. Temperatures are expected to continue to remain above normal ahead of the front.
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.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 124 PM EDT TUE SEP 30 2025
VFR conditions are expected throughout the TAF window. There`s cloud cover associated with the tropical activity but as mentioned, these CIGS will remain VFR. Clouds will decrease overnight leading to increased river valley fog but fog should remain out of the 5 main TAFs. Winds will remain light and variable through the period.
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.JKL WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...VORST LONG TERM...JP AVIATION...VORST
NWS JKL Office Area Forecast Discussion