textproduct: Jackson

KEY MESSAGES

- Dangerous heat stress conditions are expected across at least portions of the forecast area through the end of this week.

- Isolated severe storms capable of damaging wind gusts are possible across portions of the area again today.

DISCUSSION

Issued at 352 AM CDT Thu Aug 20 2026 Through tonight: It will be a little less oppressive with a greater coverage of convection through this evening. However, heat and humidity will remain the main concern in the short term. In addition, there will also be the potential for isolated strong to severe storms generally north of Highway 84 this afternoon into this evening. Early morning satellite imagery/RAP analysis still showed our CWA on the eastern periphery of a weakened 592dam ridge but also at the base of a deepening upper level trough that will continue to provide northwest flow aloft through tonight and lead to a greater coverage of convection. At the surface there was still a nearly diffuse stalled frontal boundary that was noted across our northern most counties Similar to Wednesday, convection is expected to initiate along this stalled boundary and spread to the southeast across our CWA into this evening. Latest guidance suggests the environment will support isolated strong to severe storms capable of damaging wind gusts. This will bring some relief to the heat stress today but otherwise, temperatures in the upper 90s to lower 100s will combine with relatively high humidity to result in heat indices between 105- 110F again. Thus, a Heat Advisory remains in effect for the whole CWA today. The convection will taper off by midnight but the warm and humid conditions will continue through tonight. /22/

Friday through next Thursday...

Dangerous heat and humid conditions will continue to be the primary focus for our area over the next several days and into the new work week. Several sites will continue to see afternoon highs peak around 100 degrees, with peak heat index reading values around the 105-110 degree range. A few sites across portions of west MS could see heat index values briefly reach 115 degrees. An "Elevated" threat for dangerous heat will continue to be advertised across our entire forecast area for Friday. Likewise, an areawide Heat Advisory will likely be needed for Friday as well.

Similar to yesterday, late afternoon/early evening showers and t- storms should keep heat index values just below Extreme Heat Warning criteria. Will reassess during the morning shift later this morning to see if an upgrade to an Extreme Heat Warning may be needed. If an heat warning is introduced for Friday, original thinking is to have the warning cover portions of west MS, southwest MS, and portions of northeast LA.

Regarding the rain chances for Friday, guidance continues to show the frontal boundary remaining locked in place over the southeast CONUS. This stalled boundary combined with steady moisture content (as seen with dewpoints remaining in the low to mid 70s Friday afternoon), will help increase the risk for some scattered strong to marginally severe t-storms along and south of I-20. The slightly higher storm coverage (PoPs between 35-40%) does appear to be across portions of southeast MS.

Gradual easing is expected as this frontal boundary and drier air edge southward into the weekend, but afternoon heat index values are still expected to peak near or above 105 degrees into early next week especially in the southwestern half of our forecast area. Late afternoon/early evening rain coverage will begin to increase across much of our forecast by early next week Monday and continue through Thursday. /CR/

AVIATION

(12Z TAFS) Issued at 624 AM CDT Thu Aug 20 2026

Isolated to scattered TSRA are psbl again this aftn over most of the TAF sites with the exception of GLH and HEZ. Any TSRA will likely bring lower flying conditions and gusts in excess of 30kts. Otherwise, VFR conditions will prevail areawide through the end of the TAF period. /22/

PRELIMINARY POINT TEMPS/POPS

Jackson 99 74 99 72 / 20 40 30 10 Meridian 99 73 97 71 / 20 30 30 10 Vicksburg 99 75 99 73 / 10 40 20 10 Hattiesburg 99 74 98 72 / 40 30 40 20 Natchez 100 75 100 74 / 10 30 30 10 Greenville 102 75 100 73 / 20 40 10 10 Greenwood 100 73 98 70 / 30 30 10 0

JAN WATCHES/WARNINGS/ADVISORIES

MS...Heat Advisory from 11 AM this morning to 8 PM CDT this evening for MSZ018-019-025>066-072>074.

LA...Heat Advisory from 11 AM this morning to 8 PM CDT this evening for LAZ007>009-015-016-023>026.

AR...Heat Advisory from 11 AM this morning to 8 PM CDT this evening for ARZ074-075.