textproduct: Jackson

KEY MESSAGES

- Unsettled weather returns to end the week and into the weekend, with rounds of showers and storms possibly producing heavy rain and a flood threat.

- An extended period of hot temperatures begins Monday, with high temperatures reaching into the low to mid 90s and heat indices nearing or exceeding 100 degrees by Tuesday.

UPDATE

Issued at 135 AM EDT FRI JUN 26 2026

No significant changes were made to the forecast with mainly just the inclusion of the latest obs and trends for the T/Td/Sky grids as well some slight tinkering to the minimal PoPs through the rest of the night. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the zones.

UPDATE Issued at 818 PM EDT THU JUN 25 2026

Some adjustments were made to increase sky over a bit over the next few hours with extensive high cloud/cirrus debris from upstream convection. Otherwise, hourly temperatures and dewpoints were fine-tuned based on recent observations. Valley fog formation is still problem around or after midnight, but at this time it is expected to not have as significant reductions in visibility as compared to Thursday morning.

LONG TERM

(Saturday through Thursday) Issued at 346 PM EDT THU JUN 25 2026

A significant pattern change to much hotter weather is still anticipated as we close out the month of June and turn the calendar to July. When the long-term period opens at 12Z Saturday, the models are in good agreement showing shortwave troughing aloft over the Ohio Valley to Eastern Great Lakes while a developing ridge extends northward across the Plains from a broad upper-level high extending from Bermuda to Northern Mexico. An ~550 dam closed low will also be diving into the Pacific Northwest from the Gulf of Alaska. At the surface, a weak area of low pressure will be situated near/over the Bay of Fundy with a cold front extending southwest from the low to a weak area of low pressure over southern Indiana and then west to a lee trough along the eastern slopes of the Colorado Rockies. Convection is likely to be ongoing across eastern Kentucky after daybreak Saturday within the warm sector of the low, amidst a high PWAT air mass (nearing 2.00 inches) and weak skinny instability (750-1250 J/kg of MLCAPE).

While guidance varies on overall speed, the surface low will scoot north of the JKL CWA during the day on Saturday with the trailing cold front sagging to along or south of the Lower Ohio River, though overall progress across the Commonwealth is uncertain due to guidance spread. With morning convection and categorical PoPs, sufficient destabilization for severe weather ahead of the cold front remains an open question. Of greater confidence will be the deep warm cloud layer, PWATs near or exceeding 2 inches and skinny CAPE with high RH to the stratosphere, all of which will be supportive of torrential downpours. Where rainfall is most persistent, isolated instances of flash flooding remain a legitimate concern and so most locations south of I-64 are in a Day 3 WPC ERO Slight Risk.

By Sunday, troughing over the Western CONUS will continue to deepen while the downstream ridging builds over the Central CONUS and a closed high takes shape over the Lower Mississippi Valley. In response, the frontal boundary will lift back to the north and east with a generally lower probability of showers and thunderstorms (mostly chance PoPs) on Sunday afternoon. The boundary continues to progressively lift northeast through the new work week as the center of the upper-level high drifts up into the Mid- Mississippi and Lower Ohio Valleys. This will keep high humidity in place from Monday through Thursday, but the rising heights will tend to lead to some mid-level capping. LREF mean PWATs are in the 1.5 to 1.6 inch range during this period. High humidity values at the low-levels will support robust instability (2,500 to 3,500 J/kg of MUCAPE) formation each afternoon but it will remain largely trapped by the capping inversion. However, differential heating over the rugged Coalfield topography may be sufficient to break the cap and yield isolated afternoon and evening pulse thunderstorms. With weak flow and mid-level dry air in place, it does appear that there is a risk for a few of the most robust cores to produce strong to severe microburst winds as they collapse. Temperatures will also be very hot with LREF mean 850 hPa temperatures reaching 20 to 21C on Monday, around 22C on Tuesday, 22 to 23C on Wednesday, and around 23C on Thursday. Probabilities for temperatures exceeding 90F across the lower elevations are in the 50 to 70 percent range on Monday, 70 to 90 percent range on Tuesday, 80 to 100 percent on Wednesday, and 90 to 100 percent on Thursday. The high temperatures combined with dew points in the low to mid 70s should support heat indices nearing and in many locations exceeding 100F, especially by mid- week.

In sensible weather terms, look for occasional rounds of showers and thunderstorms, some of which could produce heavy rainfall and instances of flooding on Saturday, becoming less numerous on Sunday. It will be mild and muggy with highs in the low to mid 80s on Saturday, warming into the 85 to 90F range for Sunday, while nighttime lows range within several degrees of 70F. Thereafter, it will be hot and steamy with temperatures soaring into the upper 80s to lower 90s on Monday, and low to mid 90s each subsequent afternoon. Nighttime lows stay mostly in the 70s. Heat indices will reach new highs each afternoon with most places eclipsing the 100F mark by Thursday. Isolated showers and thunderstorms will be possible each afternoon and may bring localized relief for some.

AVIATION

(For the 06Z TAFS through 06Z Friday night) ISSUED AT 200 AM EDT FRI JUN 26 2026

VFR conditions should prevail for a good portion of the forecast period, with a couple of caveats. Valley fog formation is anticipated in southeast Kentucky again tonight, with reductions down to MVFR or IFR levels, though this should not affect any of the terminals. Mid to high level clouds, debris from upstream convection, will likely affect the sky for the latter portion of the period. Cumulus again develops during the 14Z to 17Z period, which should eventually yield convective chances during the last 6 to 12 hours of the aviation period as a cold front sags toward the Ohio Valley. Light and variable winds are expected through about 14Z, giving way to south to southwest winds at 10 kts or less.

JKL WATCHES/WARNINGS/ADVISORIES

None.