textproduct: Jackson

KEY MESSAGES

- Dangerous levels of heat stress will continue to be a concern early this week. - There is a marginal risk for a strong to severe storms late Monday over especially northern portions of the forecast area.

MESOSCALE UPDATE

Issued at 935 PM CDT Sun Sep 20 2026

Latest observations support trend in mesoscale guidance heading into the overnight hours. Following from earlier convection across Alabama to our east this afternoon, an outflow boundary marks an increase in humidity across our eastern zones. Analyzed PWAT values are generally above 1.7 inches east of Interstate 55 late this evening, and MUCAPE values associated with elevated instability are in the 2000-3000 J/kg range. With a weakening ridge of high pressure directly over our area being squeezed by troughing from the northwest and southeast, it would seem that surface/low-level convergence will be the primary instigator of new convection overnight. HRRR and other high-res guidance disagree with coverage and initiation, but a zone from Jackson, MS to Columbus, MS appears to be the most favorable. Satellite imagery shows active mid-level cloud deck in a similar zone, and some weak showers are noted near the KGWX radar in northeast MS/northwest AL. Severe storms are not expected, but would not be surprised to get some elevated thunderstorms with heavy downpours and loud thunder plus or minus the hours around midnight tonight.

Also looked at guidance for tomorrow afternoon and tomorrow evening, and updated with latest POPs values - filling in and accounting for low biases under a changing regime. The trough moving in from the northwest will replace the lingering shortwave ridge overhead tomorrow afternoon. Weaker inhibition across the area, and a nearby frontal boundary to our north will help to trigger afternoon convection. Still low-to-moderate (20-40%) POPs, but any location in the area at least has a chance for showers or thunderstorms tomorrow. The Marginal Risk for strong to severe storms remains in place across the northern half of the area, with damaging wind gusts being the main hazard. With rain chances increasing, and a remnant of drier air hanging on through the Delta areas, the local graphic for heat risk tomorrow was leveled at "Limited" (1 of 4) for tomorrow. Max heat index values should top out near 105 in the hottest areas. /NF/

DISCUSSION

Issued at 300 PM CDT Sun Sep 20 2026

Above normal upper ridging continues to promote well above normal surface heat, and in spite of the lower dewpoints and greater mixing, we're still seeing limited to elevated heat danger in the near term ahead of an approaching cold front. However, relief from the heat is on the way. The cold front is expected to move through the area by Tuesday night/Wednesday, and this will bring temperatures and humidity levels that are much more typical of September.

Aside from the heat, we will be monitoring for the potential of a few strong/severe storms ahead of the cold front early this week. For Monday, per SPC, there is a marginal severe risk for a few pulse severe storms during peak heating over northern portions of the area. For Tuesday, there is currently no official SPC severe outlook in our forecast area, but it wouldn't be a surprise to see eastern portions of the area enter the picture for a possible marginal risk as we get closer in time. Looking ahead for the late week into next weekend, as mentioned, drier conditions can be expected with "less hot" temperatures. Overall, weather impacts should mostly be tied to early week heat and convective potential. /EC/

AVIATION

(06Z TAFS) Issued at 1234 AM CDT Mon Sep 21 2026

Isolated -TSRA wl affect GTR-JAN-HKS through 07Z before dissipating. Additional isolated to scattered -TSRA wl be psbl this aftn over the central and eastern portions of the CWA. Away from any TSRA VFR conditions wl continue to prevail through the TAF period. /22/

PRELIMINARY POINT TEMPS/POPS

Jackson 72 96 70 93 / 20 10 10 0 Meridian 71 96 69 93 / 30 20 10 0 Vicksburg 72 96 71 93 / 20 10 0 0 Hattiesburg 72 96 71 95 / 30 20 10 0 Natchez 72 97 72 95 / 20 10 10 0 Greenville 72 96 69 91 / 20 10 0 0 Greenwood 71 96 68 92 / 20 10 0 0

JAN WATCHES/WARNINGS/ADVISORIES

MS...None. LA...None. AR...None.