textproduct: Jackson

KEY MESSAGES

- Severe storms capable of producing tornadoes, some possibly strong, damaging winds and large hail, are likely this afternoon into early Thursday.

- Locally heavy rainfall and areas of flooding are likely, with further drought relief expected.

MESOSCALE UPDATE

Issued at 1005 AM CDT Wed May 6 2026

Rest of Today...The threat for severe storms remains across the entire forecast area later this afternoon into early Thursday. Until then, warm advection showers have already developed beneath the capping inversion, which is fairly stout according to this morning's 12Z KJAN RAOB. This trend is forecast to continue through the morning hours into early this afternoon as a cold front, which is currently oriented across the forecast area along a northeast to southwest line extending from around Greenwood, MS to around Bastrop, LA. As daytime heating continues into mid-afternoon, storms are forecast to begin developing along and near this front as it slowly moves more into East Central Louisiana and Central and Northeast Mississippi. This is when the threat for severe storms will begin to increase, as these storms will have the potential for producing wind gusts to 70 mph and up to golf ball size hail.

As we move into the late afternoon and evening hours, an area of ascent lifts northeast across the region. With the expected weakening capping inversion, increasing instability, steep mid-level lapse rates, and increasing overall wind shear and lengthening hodographs, the potential for severe storms increases further, with the threat of tornadoes likewise increasing, some of which could be strong. This will especially be the case within an area currently stretching from near Columbus, MS to near Rayville, LA to near Natchez, MS and to near Laurel, MS, where an "Enhanced Risk" for severe storms exists. Outside of this area and across the remainder of the CWA, a "Slight Risk" for severe storms resides. Damaging winds to 70 mph, tornadoes, and quarter to golf ball size hail will be possible.

Now with all that said, there are some "flies in the ointment" that could indeed hamper the development of storms, along with their potential intensity today. Much of it is what we're currently seeing across the area at the time of this discussion. The combination of masking cloud cover and light warm advection showers could limit heating across the area today. This would bring into question later this afternoon and evening whether or not the capping inversion becomes the dominate feature that limits the development of robust convection. This will continue to monitored during the day through observations, high-res model data, and a special KJAN RAOB that's expected to be released early this afternoon.

In addition to the severe weather threat today, an "Elevated Threat" for flash flooding due to heavy rainfall and training of convection is likely given the increase in atmospheric moisture across the region, 2-2.25 inch precipitable H2O values advertised. This will particularly be the case across portions of East Central Louisiana and into portions of Central, East Central, and South Mississippi. Here, rainfall amounts of 3-5 inches, and locally higher, will be possible in a short amount of time. Elsewhere, a "Limited Threat" for flash flooding exists with rainfall amounts ranging from 2-3 inches will be possible in a short amount of time.

The ongoing forecast is currently in good shape. HWO graphics will be updated accordingly through the course of the day to reflect our latest thinking and collaberative efforts with both SPC and WPC in terms of severe risk and heavy rainfall threat areas. Otherwise, other than some minor tweaks to hourly elements of the forecast based on current trends, no major changes will be made on this morning's forecast update. /19/

DISCUSSION

Issued at 529 AM CDT Wed May 6 2026

Today through early next week...

Today and Thursday: Water vapor and synoptic imagery early this morning depict longwave trough axis stretched from Baja Peninsula to Desert Southwest and extending northeast to the cold core over eastern Canada and the Hudson Bay area. This is helping southwesterly flow become entrenched in the area and moist ascent to continue to feed into the area. GOES East satellite derived total precipitable water (PWs) indicate moist ascent has really moistened the deep atmospheric column (around one and a half inches to one and three quarter inches). This is driving widespread cloudiness across the region, with frontal zone draped across central TX into the ArkLaTex and Mid South. There continues to be juxtaposition of lapse rates, destabilization aloft (MUCAPE around 1000 J/kg) and deep layer effective bulk shear (50-55kts) to support a low end severe threat through daybreak in the Delta. There is some convection ongoing across southeast AR that may support some isolated severe storms, with damaging wind gusts and hail threat, through daybreak. Will continue the ongoing HWO severe graphic this morning.

Main concerns turns to the severe storms expected and heavy rain and flash flood potential this afternoon into tonight. As the front sags southward through today, moist ascent will bring increased coverage of rain and storm coverage will begin to pick up into the afternoon. Broad zone of increased deep layer shear (0-1km around 20-30kts, 0- 3km around 35-40kts and 0-6km around 55-70kts), steepening lapse rates/vertical totals and destabilization (1500-2500 J/kg MLCAPE and 2500-3500 J/kg MUCAPE). This environment will support a storm mode of predominately supercell and bowing segments, with some splitting cell storm mode as well. All modes of severe weather remain likely, including tornadoes, damaging wind gusts up to 70mph and large hail up to golf ball size. With an increase in the low-level jet (LLJ) into the afternoon to evening, a ramp up in tornado potential will increase on the edge of a significant tornado parameter (STP) gradient. This gradient has shifted from the northern half of the Natchez Trace corridor to further southward into the Interstate 20 corridor. Convective allowing models, including the HRRR, ARW and FV3, and ensembles (REFS and HREF), are narrowing the corridor closer to along and south of the Interstate 20 corridor. There will be large elevated mixed layer (EML) capping inversion that will gradually erode with daytime heating and mixing of the planetary boundary layer (PBL) and as ascent weakens the cap. Convective initiation (CI) should develop around 1-3PM, with the primary severe weather threat after around 3-4PM onward. This will only heighten as the LLJ increases into the evening, with the strong tornado potential becoming heightened in this timeframe into late afternoon and evening hours. Recent model trends in updraft helicity (UH) tracks have shifted southward to along and south of the Interstate 20 to Highway 84 corridors. Based on that and with recent coordination with SPC, adjusted the HWO graphic for severe storms (Enhanced risk area) graphic slightly southwest to account for some CI and UH tracks near the MS River corridor and as far southward as near Highway 84 to Interstate 59 corridors. Also pulled all of the Pine Belt into the Slight risk area. This should persist through around midnight to 1AM, but cannot rule out some potential persisting into the overnight hours. Some westerly shear and destabilization may reinvigorate into Thursday afternoon, but recent trends have pushed the boundary southward towards the Gulf Coast. No HWO graphics are needed for Thursday.

Deep moisture will peak today into Thursday (around 2 to 2.25 inch precipitable water and 340-345K 850mb Theta E) combined with strong cloud bearing layer flow around 45-50kts and somewhat of a slight ridge of backbuilding vectors, albeit around 20kts, will likely result in some flash flooding concerns being likely. Recent CAMs and HREF/REFS runs indicate some higher rainfall accumulations, of 3-5 inches, with as high as exceeding 6-8 inches in east to southeast Mississippi around the Interstate 59 corridor. Probabilities of rainfall totals exceeding 3 to 5 inches are reasonable (40 to 70 percent greater than 3-4 inches and around 30 percent greater than 5 inches). HREF neighborhood probs to exceed 3 inches (around 30 percent) over the Natchez Trace corridor southeast into the Highway 84 to Interstate 59 corridors indicate potential for flash flooding being heightened, especially as the totals could approached some localized probabilistic match mean (LPMM) values around 5 inches and maximum values in excess of 6-8 inches. Based on that, added an Elevated in the Natchez Trace to north of Highway 84 to Interstate 59 corridors. Areas of flooding will be likely, especially in urban locations, where rainfall totals accumulate rapidly in a short duration, which could flood roads or structures. Based on the high rainfall duration in these areas, some quick rises on area rivers could approach action or minor stages if the higher end totals are realized. Otherwise this rain will be a much needed reprieve in the long duration rainfall deficits that have been observed. Rain will shift southward into Thursday night but stall across the Gulf Coast areas into late week.

Seasonable warmth this morning will turn to seasonably cool during the mid to late week period on Thursday.

Late week through early next week (Friday through next Tuesday): Rain chances begin to shift southeast into late week. Synoptic and surface features will consist of cutoff low aloft near the International Border with frontal zone shifting southeast into the northern Gulf. This will keep some rain chances along the Natchez Trace through before daybreak Friday, with highest coverage into the Pine Belt to Highway 84 to Interstate 59 corridors but shifting northward into the Interstate 20 corridor through the day. As shortwave trough swings into the ArLaTex into the weekend, expect rain coverage to pick up Saturday and into Sunday (25 to 55 percent) ahead of another front.

Temperature forecast become more seasonable as return flow gradually shifts around into the weekend (highs in upper 70s Friday to low to mid 80s Saturday and Sunday to mid to upper 80s Sunday and lows in upper 50s to low 60s Friday night to low to mid 60s Saturday and Sunday night). As shortwave becomes absorbed in the developing trough and deepening axis over the region, this will help drive clearing front through the area and rain chances out likely by early to midday Monday of next week. High pressure and seasonably cool conditions will build in the wake. /DC/

AVIATION

(12Z TAFS) Issued at 652 AM CDT Wed May 6 2026

Some MVFR ceilings have moved in throughout the area and will persist through the morning. Later on showers and thunderstorms are expected to build into the area with a decent potential for severe characteristics throughout the area around 06/18-20Z for most sites, showers could precede thunder, but for the most part once precipitation starts, thunder is expected to follow shortly after. Ceilings could dip down into LIFR/IFR range intermittently as early as midday in north central sites. A firm eye will be kept on trends to ensure forecast represents current and expected conditions./OAJ/DC/

PRELIMINARY POINT TEMPS/POPS

Jackson 83 63 74 58 / 80 100 10 10 Meridian 83 65 77 56 / 80 100 20 10 Vicksburg 84 60 73 57 / 90 90 0 10 Hattiesburg 84 69 80 61 / 80 90 60 30 Natchez 85 64 75 60 / 90 100 20 30 Greenville 72 56 71 54 / 100 90 0 0 Greenwood 77 58 73 54 / 100 90 0 0

JAN WATCHES/WARNINGS/ADVISORIES

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