textproduct: Jackson

KEY MESSAGES

- Thunderstorms are possible at times from Saturday through Wednesday.

- Heavy rainfall is possible on Saturday and Saturday night and could lead to isolated instances of flash flooding.

UPDATE

Issued at 913 AM EDT FRI JUL 31 2026

Fog continues to mix out across river valleys this morning, with most having already done so. Any remaining fog should shortly mix out within the next hour. The SAF was updated to remove fog wording, and the grids were freshened up using the latest observational T/Td information. No significant changes were made to the forecast.

UPDATE Issued at 740 AM EDT FRI JUL 31 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 445 AM EDT FRI JUL 31 2026

The first part of the extended will be dealing with a seemingly too early synoptic low slowly working east through the eastern Ohio Valley. This will keep low clouds and some, mostly stratiform, rain around well into the start of the new work week - eventually taking on a diurnal pattern to the convection.

The previous long term discussion follows:

The long-term period opens 12Z Saturday with a positively-tilted 500 hPa shortwave trough digging into the Mid-Mississippi Valley behind shortwave ridging departing east of the Appalachians. An ~1003 mb area of low pressure will be situated over southwest Illinois just ahead of the shortwave trough. A warm front will extend southeast from the low across Middle Tennessee and Northern Georgia, while a cold front arcs to the south into the Missouri Bootheel and then southwest to over Northern Texas. Further to the north, 500 hPa troughing is focused over and adjacent to Hudson and James Bay, supporting a second cold front draped from a surface low over southern Baffin Island southward to the Ottawa Valley, and then westward across the Upper Great Lakes and Dakotas. Meanwhile further west, an ~599 dam high is situated over the Lower Colorado River basin while a ridge axis extends northeastward across the Canadian Prairie Provinces.

The most active weather of the long-term forecast will occur during the first two days of the period. The aforementioned shortwave trough will continue to amplify as it becomes more meridionally oriented on Saturday and Saturday night while its attendant surface low tracks over the Lower Ohio Valley. This will send the warm front pushing into eastern Kentucky while the trailing cold front catches up and occludes. At the same time, the northerly trough will also amplify across the Great Lakes and capture some or much of the vorticity energy associated with the more southerly shortwave. There is admittedly substantial disparity from model- to-model and run- to-run regarding how much upper-level support remains with the closed-off low or perturbation that lingers. In any case, the much diminished upper-level support of the surface low leaves it to meander southward and dissipate early next week along with its associated frontal structures as relatively subtle weakness lingers in the heights aloft. Meanwhile, a new area of low pressure will form near or over the Eastern Great Lakes and New England as the northern stream trough pulls away to the east. The system's cold front will sag southward into the Central Appalachians through mid- week but stagnate there. Another upper level trough and cold front may approach the Ohio Valley around and just beyond the end of the forecast period.

The main concern during the long-term period will be the potential for heavy rainfall on Saturday into early Sunday as PWATs rise to 1.75 to 2.00 inches (or 90th to 95th percentile relative to climo) in the WAA regime ahead of the surface low. WPC's Slight Risk (2 of 4) for excessive rainfall was expanded to cover all but the easternmost portions of Pike County. Efficient warm layer rainfall processes combined with the potential for training convection in a high PWAT environment are all supportive of a locally heavy rainfall threat, possibly leading to instances of flooding. A notable mitigating factor is the antecedent drying ongoing prior to the event---the 3-hour FFG currently ranges from 1.75 to 2.50 inches across most of the JKL CWA and will likely improve further with an additional 36 to 48 hours of drying. As for any severe weather potential, shear may be sufficient for limited organization, but overall destabilization remains highly uncertain, especially east of I-75. If any strong to severe storms materialize, they would most likely occur west of I-75. PWATs fall back somewhat Sunday and Sunday night as the surface low weakens and dissipates, but the second cold front fails to press far enough south to drop PWAT levels below seasonal norms. Lingering moisture combined with the remnant weakness aloft will still combine with the daily heating cycle to keep the continued threat for primarily afternoon and evening convection in the forecast from Monday onward.

In sensible weather terms, clouds and shower and thunderstorm chances increase on Saturday, with coverage peaking Saturday night followed by a secondary peak on Sunday afternoon. Some of the showers and thunderstorms could produce torrential downpours, especially on Saturday and Saturday night. It will be muggy both weekend days with high temperatures mainly in the lower 80s and lows not far from 70F. Looking ahead to the new work week, temperatures start the week with highs near 80F on Monday before slowly warming into the mid to upper 80s by Thursday, while nighttime lows range from the 60s to near 70F. Scattered showers and thunderstorms are expected each day as well, primarily during the afternoon and evening.

AVIATION

(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 755 AM EDT FRI JUL 31 2026

VFR conditions will continue to prevail through the 12Z TAF period for most terminals. Mostly clear skies will be the predominant sky cover through the bulk of the day. Limited valley fog early this morning will likely not impact any of the TAF sites. The fog lifts and mixes out by 13Z. After that, expect VFR conditions to continue area-wide with the small potential for a shower or thunderstorm to impact KSME right around dawn on Saturday. Winds will remain light, but they will likely veer towards a more easterly and then southerly orientation by late in the day.

JKL WATCHES/WARNINGS/ADVISORIES

None.