ACUS01 KWNS 191255

SWODY1

SPC AC 191254



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0754 AM CDT Wed Aug 19 2026



Valid 191300Z - 201200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OZARKS

INTO THE MID MS VALLEY AND SOUTHERN AZ....



...SUMMARY...

Thunderstorms with severe wind gusts and hail will be possible this

afternoon across the mid Mississippi Valley. Isolated severe gusts

and hail will also be possible from the lower to mid Missouri Valley

westward into the Great Plains. A few severe gusts could also occur

in southern Arizona and in the Southeast.



...Mid MO Valley...

Early-morning satellite imagery depicts a low-amplitude shortwave

trough moving through western SD/NE. Showers and thunderstorms are

ongoing downstream of this wave across central/eastern SD and

north-central/northeast NE. Recent surface analysis place a corridor

of moderate low-level moisture (i.e. upper 60s dewpoints) from

eastern NE northwestward to a weak surface low over central SD.

Instability will likely build within this corridor as the shortwave

continues eastward, potential resulting increasing thunderstorm

coverage and intensity later this morning into the afternoon across

eastern NE. Vertical shear will be strong enough for organized storm

structures and the potential for a few supercells. This potential

will be largely dictated by how much the airmass can destabilize

amid the cloud cover and limited heating. Large hail is possible

within the initially more cellular activity, but a transition to a

more linear mode results in damaging gusts becoming the primary

hazard with eastward/southeastward extent.



...Ozarks into the Mid MS Valley...

Regional radar imagery shows a large cluster of showers and

thunderstorms progressing across the region. A few stronger updrafts

are possible within this cluster, but limited buoyancy downstream

and a weakening low-level jet are forecast to result in gradually

diminishing storm strength over the next few hours. The airmass is

forecast to gradually recover in the wake of this cluster, with

strong buoyancy (i.e. MLCAPE over 2000 J/kg) in place by the late

afternoon. The shortwave trough mentioned in the preceding paragraph

is forecast to continue southeastward, and ascent attendant to this

wave coupled with weak low-level convergence along the cold front

will support thunderstorm development within this destabilized

airmass this evening. Strengthening mid-level flow will result in

moderate to strong deep-layer vertical shear supportive of

supercells. Large hail and damaging gusts are the primary hazards,

but a strengthening low-level jet will result in enough low-level

shear to support the potential for a few tornadoes as well. Storms

will tend to cluster with eastward extent, with the threat for

damaging gusts persisting within these bowing line segments.



...Ohio Valley...

A somewhat secondary area of late afternoon/early evening

thunderstorm development is anticipated from central IL into central

IN and central OH. Moderate buoyancy and strong westerly flow aloft

support the potential for isolated supercells capable of large hail

and isolated damaging gusts.



...Central/Southern High Plains...

Surface analysis places 60s dewpoints into the Colorado Foothills

this morning, increasing into the upper 60s farther east/southeast

into southwest KS. Strong heating/mixing of this airmass is

anticipated this afternoon, promoting the development of moderate

buoyancy. Thunderstorm development is expected across the high

terrain before then progressing eastward into the lower elevations.

Moderate northwesterly flow aloft will be support organized storms

structures, and large hail is possible along the Foothill.

Thereafter, a trend towards an outflow-dominant storm mode will

result in strong to severe gusts across portions of the

central/southern High Plains. Higher probabilities may be needed in

later outlooks if guidance continues to indicate increased coverage.





...AZ...

The presence of monsoon moisture will support moderate buoyancy

across the lower elevations of south-central AZ during the late

afternoon. This should allow for storms that develop over the high

terrain to maintain intensity as they process southwestward into the

lower elevations this afternoon/evening. Steep low to mid-level

lapse rates and large temperature-dewpoint spreads will support the

potential for severe gusts.



...Southeast into northern FL...

A very moist airmass (i.e. dewpoints in the 70s) will be in place

today from MS into FL. Strong heating is anticipated, with high

temperatures in the upper 90s across much of the region. As surface

temperatures warm, moderate instability will develop, with scattered

thunderstorms expected amid modest low-level convergence from MS

into western/southern AL and across the FL Panhandle into northern

FL. The deep low-level moisture combined with steep low-level lapse

rates will support an isolated wind-damage threat during the mid to

late afternoon.



..Mosier/Bunting.. 08/19/2026



$$