textproduct: Jackson

KEY MESSAGES

- Lower humidity and dry weather continues today.

- 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.

LONG TERM

(Friday through Wednesday) Issued at 333 PM EDT WED JUN 24 2026

The long-term period opens at 12Z Friday with quasi-zonal flow and embedded shortwaves across the Ohio Valley and adjacent regions. This is mirrored at the surface by a weak wave of low pressure near/over Lake Ontario with a frontal boundary trailing southwestward to another weak low over Missouri, and then southwest to another weak low in the vicinity of the Oklahoma and Texas panhandles. This leaves eastern Kentucky residing in the warm sector. Well upstream, a much more substantial trough axis extends from the Alaska Panhandle southward to along the California coastline.

The pattern will change only slowly on Friday and Saturday, with the quasi-zonal flow over our region gradually giving way to an emerging ridge over the Mississippi Valley being pumped up in response to the upstream trough digging deeply and closing off into a deep upper low over the Pacific Northwest. In response, the surface frontal boundary will tend to lift northward across the Plains states while simultaneously settling southward on the eastern side of the Appalachians, leaving the Mid-Ohio Valley as the pivot point for the boundary. Multiple upper-level perturbations aloft combined with 1.6 to 1.9 inch PWATs (LREF mean) and diurnally modulated instability (generally peaking in the 1,000 to 2,000 J/kg of MUCAPE each afternoon) will keep the threat of showers and thunderstorms in the forecast with the accompanying threat of torrential downpours. The overall flow, though modest, should be strong enough to keep individual convective cores progressive, but the repeated rounds of convection, focused by the nearby frontal boundary, could lead to locally excessive rainfall. This risk is noted in the Day 3 WPC ERO Slight Risk over northwestern portions of the CWA on Friday (Marginal Risk further southeast) and then a Day 4 ERO Slight Risk for nearly all of the CWA on Saturday. Synoptically, shear is rather weak, which, combined with limited instability, is likely to keep the threat of any severe weather low. However, modest mesoscale kinematic enhancement near the frontal boundary might support slightly better convective organization in the northern and eastern counties closer to the front.

The frontal boundary will become more north-south oriented and situated to our east by Sunday as upper-level ridging strengthens further into a closed high over the Lower Mississippi River Valley. One more day of scattered to numerous showers and thunderstorms can be expected again on Sunday as the front remains nearby. That boundary then lifts northeast heading into the new work week with the center of the upper-level high drifting up into the Mid-Mississippi Valley. This will keep high humidity in place from Monday through through the end of the period, 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. Robust CAPE (2,500 to 3,500 J/kg) formation is modeled each afternoon, largely trapped by the capping inversion. However, differential heating over the rugged Coalfield topography (with the Cumberland Mountains and Pottsville Escarpment being the most notable focusing topographic features) may be sufficient to break the cap and yield isolated to scattered 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 hot, with LREF mean 850 hPa temperatures reaching 21 to 22C on Monday, around 22C on Tuesday, and 22 to 23C on Wednesday. Probabilities for temperatures exceeding 90F across the lower elevations are in the 50 to 70 percent range on Monday, 60 to 90 percent range on Tuesday, and 70 to 90 percent on Wednesday. The heat combined with dew points in the low to mid 70s should support heat indices nearing and in many cases exceeding 100F from Monday afternoon onward.

In sensible weather terms, look for occasional rounds of showers and thunderstorms, some of which could produce heavy rainfall and instances of flooding, on Friday and Saturday, becoming less numerous on Sunday. It will be mild and muggy with highs in the low to mid 80s on Friday and Saturday, warming into the 85 to 90F range for Sunday. During that time, nighttime forecast lows range within several degrees of 70F. From Monday onward, it will be hot and steamy with temperatures soaring into the low to mid 90s each afternoon while nighttime lows stay mostly in the 70s. Isolated to scattered showers and thunderstorms will be possible each afternoon and may bring localized relief from the heat for some.

AVIATION

(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 214 PM EDT WED JUN 24 2026

VFR conditions are forecast to prevail at the TAF sites for the duration of the 18z issuance period. A field of cumulus clouds has developed this afternoon across the region. These should subside after sunset, perhaps giving way to some passing high level clouds overnight. Conditions are primed for river valley fog formation after 04z, but this is still not expected to affect any of the TAF sites. Observations will need to be monitored in the Cumberland region (KLOZ and KSME) as this time frame approaches, as there is a low-end chance (less than 25 percent) for fog- related MVFR vsby reductions in the LAMP guidance for these terminals. In general, expect light and variable winds and non- impactful sky cover to persist into tomorrow morning. Winds adopt a more southwesterly orientation and strengthen to speeds greater than 6 knots towards the very end of the TAF period tomorrow afternoon, when another cu-type cloud field is expected to develop.

JKL WATCHES/WARNINGS/ADVISORIES

None.