ACUS01 KWNS 261235

SWODY1

SPC AC 261233



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0733 AM CDT Thu Jun 26 2025



Valid 261300Z - 271200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON

ACROSS FAR SOUTHEAST MN...NORTHERN IA AND SOUTHERN WI...



...SUMMARY...

A few tornadoes and isolated wind damage will be possible this

afternoon from northern Iowa and southwest Minnesota into southwest

Wisconsin. Isolated wind damage will be possible across a broad area

of the eastern Plains, Ohio Valley, Mid-Atlantic, the Southeast and

Montana.



...Southern MN/IA/Southern WI...

Early morning radar and satellite imagery show a well-defined MCV

moving northeastward into eastern NE. Surface analysis reveals a low

over eastern NE, which is associated with this vorticity maximum as

well. A stationary boundary extends northeastward from this low

through northwestern IA to another low in the MN/IA/WI border

intersection vicinity. This boundary, which separates a moist

airmass characterized by 70s dewpoints from a more continental

airmass with low 60s dewpoints, could act as a favored corridor for

northeastward progress of the surface low throughout the day. At the

same time, strengthening southerly low-level flow will increase the

low-level moisture advection south of this boundary, resulting in

some tightening of this boundary throughout the day. Some guidance

suggests this boundary could move slightly northward as a warm front

as well. This low-level moisture advection will also help offset

surface dewpoint reductions due to mixing, with dewpoints likely

remaining in the 70s along and south of the boundary. Strong heating

of this moist airmass will bring temperatures in the upper 70s/low

80s, fostering airmass destabilization and strong buoyancy by the

early afternoon.



Thunderstorm development is expected as the approaching vorticity

maximum and associated surface low interact with this unstable

airmass, with initiation occurring both near the surface low as well

as farther east amid the convergence along the warm front. The

development near the low should becoming linear quickly while the

activity along the front should remain more cellular longer. The

initial/more discrete storms could be supercells with the potential

to produce a few tornadoes within the moderately sheared and

vorticity rich environment along the front. Damaging gusts will be

possible with the linear segments as well, particularly in close

vicinity to the surface low where mesoscale circulations could

augment updrafts and downdrafts.



...Central/Eastern KS into Western/Central OK...

Recent surface analysis reveals weak surface troughing to the south

of a low over eastern NE. This troughing will likely shift eastward

as its parent low progresses northeastward, with convergence along

this boundary contributing to thunderstorms across central and

eastern KS. The character of the boundary will become more diffuse

with southern extent, but modest low-level confluence should still

be enough to support afternoon thunderstorm development. Vertical

shear will be weak through this entire corridor, but thermodynamic

profiles will favor strong downdrafts and the potential for isolated

strong-severe outflow gusts for a few hours this afternoon/evening.



...Southeast...

Overnight convection has resulted in extensive cloudiness across

much of the region this morning. Even so, ample low-level moisture

remains in place and the airmass is expected to destabilize by the

early afternoon amid strong heating. Initial development appears

most likely near the westward progressing outflow moving across MS,

with additional development later near a convectively generated

vorticity maximum moving across central GA. Widespread storms are

also expected across FL as an upper low drifts slowly

west-northwestward. Shear will be weak areawide and a largely

disorganized storm mode is anticipated. Surging outflow is possible

with the strongest storms, fostering the potential for damaging

gusts and also contributing to additional storm development. Several

forward-propagating clusters are possible although their location,

strength, and longevity are uncertain, precluding any increased

severe probabilities with this outlook. 



...MT this afternoon/evening...

A subtle midlevel trough and associated/diffuse front will move

across the northern Rockies this afternoon into tonight.  Deep

mixing and inverted-V profiles will favor some potential for

strong-severe outflow gusts with scattered high-based thunderstorms

along and ahead of the diffuse front this afternoon into this

evening.



...OH Valley into the Mid-Atlantic this afternoon...

Scattered thunderstorms are expected again this afternoon as the

airmass destabilizes amid strong daytime heating and ample low-level

moisture. Residual boundaries from prior convection, and terrain

circulations will act as favored areas for initiation. Vertical

shear will be weak, but steep low-level lapse rates and

precipitation loading could support isolated wind damage with

downbursts from mid afternoon into the evening.



..Mosier/Wendt.. 06/26/2025



$$

