textproduct: Jackson

KEY MESSAGES

- Hot and humid weather persists at quite oppressive levels to begin the weekend.

- Small chances for showers and storms return this afternoon and evening, before building over the weekend.

- Storms through the middle of next week may produce strong, to locally damaging, wind gusts along with heavy rainfall, potentially leading to a few instances of flooding.

UPDATE

Issued at 200 PM EDT FRI JUL 3 2026

Hourly grids have been freshened up based on recent observations and trends. Although the center of the ridge is shifting east gradually, cumulus across eastern KY has thus far been more muted compared to some locations south and west of eastern KY. Some development could still occur near the KY and VA border or the Lake Cumberland this afternoon or early this evening, but pops were cut back from NBM PPI values giving more credit to recent HRRR runs or the NAM versus the likely too aggressive ARW and FV3.

UPDATE Issued at 730 AM EDT FRI JUL 3 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. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the zones.

LONG TERM

(Saturday night through Thursday) Issued at 200 AM EDT Fri Jul 3 2026

A pattern change is in store for Eastern Kentucky during the long term forecast period. The antecedent ridging responsible for the past week's excessive heat is progged to break down by the end of the holiday weekend. A well-defined shortwave trough digs into the Upper Midwest in its wake, with the commonwealth positioned just below the base of its axis. At the surface, this pattern shift is marked by the departure of an anticyclone to the east and the approach of a cold frontal boundary to the north. This allows a plume of prefrontal moisture return to funnel into the forecast area early next week, and the coverage of showers/storms accordingly increases on Sunday and Monday. The related increase in sky cover and localized pockets of rain-cooled air will provide some relief from the heat, but it comes with a catch. Forecast guidance generally resolves that frontal boundary coming to a crawl within the forecast area, as its parent support aloft will propagate off to the east and orphan it. On the warm/moist side of the resultant quasi-stationary boundary, ample instability and atmospheric moisture will favor additional convective development, especially during peak diurnal heating and in Southern Kentucky. Given the potential for multiple rounds of activity and the parallelism between the quasi-zonal flow aloft and the increasingly west->east oriented boundary, excessive rainfall concerns emerge early next week. This is the aforementioned catch, but there is currently too much forecast uncertainty to pinpoint specific details regarding that risk.

When the period opens on Saturday evening, scattered, diurnally- driven convection is likely to be ongoing across the CWA. The previously-discussed instability should subside after sunset, with modest ridge-valley temperature splits forecast. A few of the conventionally cooler valleys could descend into the upper 60s on Saturday night, with the rest of the area remaining in the low 70s. These warmer-than-average MinTs reinforce the notion that an exceptionally warm airmass will remain in place across the CWA ahead of the early week boundary, although there should still be enough radiational cooling for patchy river valley fog formation. Wet grounds from earlier convection could cause locally dense pockets of fog elsewhere, but confidence in this was not high enough to explicitly include it in the grids.

Saturday night's warmth will give Sunday's temperatures a head start, but greater precipitation coverage and the related increase in sky cover will relegate Sunday afternoon highs to the upper 80s/lower 90s. Sunday's PoPs are bolstered by the arrival of relatively greater forcing, with dynamic, frontal, and convective lifting mechanisms all in play. Forecast model soundings are not particularly impressive from a severe convective standpoint, as the 1500-3000 J/kg of SBCAPE is met with less than 25 knots of effective bulk shear for storms to get organized and sustain themselves. Thus, minus the low-end chance for a cold pool-driven cluster/MCSes to move in from upstream, Sunday's convection looks pulsy yet again. LREF mean PWAT values are in the 1.7-1.9 inch range, which ranks around the 90th percentile of model climatology. We will need to watch closely for water loaded downdrafts to produce gusty winds and torrential downpours, and storms are not likely to be moving very quickly. This setup persists into Monday in Southern and Eastern portions of the CWA, and WPC has accordingly outlined our CWA in Marginal (Level 1/4) Risks for Excessive Rainfall on both days. While widespread flooding is not currently anticipated, we will need to closely watch for any areas that experience multiple slow-moving downpours multiple days in a row. Those locales will be the most susceptible to flash flooding, and that risk will compound with each day that this wet pattern remains in place.

It is currently unclear how long those rain chances will persist, as model spread increases considerably early next week. The progressive GFS continues to depict the the flow aloft backing towards a more northwesterly orientation as the front pushes south and a postfrontal high briefly builds into the area on Tuesday. The European model family keeps the flow aloft parallel to the stalled surface boundary while another shortwave trough organizes in the Ozarks. While the former favors a return to drier weather and the latter would allow the wet weather and hydro concerns to persist, both favor temperatures relatively cooler than what we have experienced in Eastern Kentucky as of late. The blended model guidance used to populate the long term forecast grids smooths out to 30-50% PoPs across most of the CWA through the end of the period. The greatest chances will likely align with peak diurnal instability each afternoon/evening, but future forecast packages will likely contain changes to both the numeric values and the spatiotemporal details of these rain chances. Regardless of the specific set-up, either the advection of a cooler continental airmass into the area or the presence of increased cloud cover and rain-cooled air will bump high temperatures back down into the 80s next week. This is much-welcome relief from the exceptionally hot conditions forecast within the short term period, but interests in southern and southeastern KY are encouraged to stay tuned to precipitation forecast updates in the coming days.

AVIATION

(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 210 PM EDT FRI JUL 3 2026

High pressure will likely keep the majority of the period VFR for most locations. Diurnally driven cumulus was across the region at issuance time, but has been rather muted. There remains a small chance for a thunderstorm through around 00Z, mainly near KLOZ and KSME and possibly areas south of the KJKL and KSJS. A PROB30 was kept for KLOZ and KSME for this possibility. Valley fog will likely be a concern again between 04Z and 13Z and some of this lifting into some of the TAF sites is possible, especially if they receive rain. However, opted to not include fog in any of the TAFs yet due to low confidence. Winds will remain generally light and variable, away from any storm.

JKL WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 8 PM EDT this evening for KYZ044- 050>052-058>060-068-069-079-080-083>085.

Heat Advisory from 8 PM this evening to 9 PM EDT Saturday for KYZ044-050>052-058>060-068-069-079-080-083>085.

Extreme Heat Warning until 9 PM EDT Saturday for KYZ086>088-104- 106>120.