textproduct: Jackson

KEY MESSAGES

- High pressure supports cool early autumn weather for the start of the week.

- Warmer temperatures return from the middle to the end of the week, along with our next reasonable shot at seeing some rain.

LONG TERM

(Wednesday through Monday) Issued at 446 PM EDT MON SEP 28 2026

The long-term period opens Wednesday morning with upper level ridging in place over the Southeast CONUS, mirrored at the surface by high pressure offset to the east over the Western Atlantic. This will be maintaining a mild southerly flow across the Ohio Valley. Looking upstream, a mean 500 hPa trough will be in place over western Canada while a closed ~568 dam low spins over the Lower Colorado River Valley. The trough will be supporting an ~991 mb surface low over the Upper Mackenzie River Valley with a cold front extending southward into the Northern High Plains and then westward across the Columbia River Basin. Another ~1000 mb low is noted over the Southern Rockies ahead of the aforementioned closed low.

For the first few days of the long-term, the upper level ridging will drift eastward to off the Southeast Coast. This will keep southerly flow and an unseasonably warm air mass (mean 850 hPa temperatures ~16-18C, as per the LREF) and mostly dry conditions in place over eastern Kentucky through Friday. In the meantime, the closed low over the Desert Southwest will open up and be captured the eastward-propagating northern-stream trough. As that trough shifts eastward, it will suppress the 500 hPa ridging over the Ohio Valley, transitioning the flow aloft to quasi-zonal/weakly troughed. The cold front associated with the trough will move into the Ohio Valley but then struggle to make further southeastward progress Friday night-Saturday night as energy ejects out of the opening low and rides along the boundary. Meanwhile, PWATs could exceed the 90th percentile if the NAEFS/ECMWF mean solution materializes, amidst deep moisture advection from the Gulf of America. If ingredients come together ideally, a decent soaking rainfall is possible across portions of eastern Kentucky or adjacent regions this weekend, but forecaster confidence is low. From a more sensible standpoint, this pattern will bring back the return of a summer-like feel for the remainder of the work week with dew points recovering back through the 50s and into the 60s while afternoon temperatures peak in the low to mid 80s from Wednesday through Friday. Some of the hotter portions of the Cumberland could flirt with the upper 80s. Rain chances will then knock back the high temperatures for Saturday but it will still be quite humid with the threat of rainfall and possibly a few rumbles of thunder.

Change will be around the corner to close out the first weekend of October. Within the broad upper level troughing, a quick-moving shortwave trough transiting the 49th Parallel (US-Canada border) over the weekend will phase with northern stream energy diving southeast from the Yukon. This will bring height falls to the Ohio Valley early next week while slinging an associated cold front across the Coalfields Sunday into Monday. Behind that front, LREF mean 850 hPa temperatures drop to ~9-11C with much drier PWATs (0.6 to 0.8 inches) by late Monday. Rain chances taper off behind the first cold front on Sunday and appear minimal with this second boundary. Instead, the more noticeable effect will be a decline in temperatures to more seasonable levels for Monday with highs returning to the mid 60s to lower 70s and cool nighttime lows in the 40s and 50s.

AVIATION

(For the 18Z TAFS through 18Z Tuesday afternoon) ISSUED AT 151 PM EDT MON SEP 28 2026

VFR conditions are expected with light winds through the period, with the one exception being valley fog development late this evening and continuing into the couple of hours after sunrise Tuesday morning. Models continue to show the best moisture to the east, so fog may linger to 14z or slightly later before fully dissipating in some locations. As of right now, fog is not expected to impact TAF locations for an extended period of time, so will leave out and let future TAF issuances address this as confidence hopefully increases.

JKL WATCHES/WARNINGS/ADVISORIES

None.