Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Sat Oct 04 2025
Valid 042000Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS...
...SUMMARY...
Isolated severe wind gusts/hail may accompany the stronger
thunderstorms that develop from the central Rockies/High Plains into
the northern Plains late this afternoon into tonight.
...20Z Update...
The forecast remains on track, and only minor adjustments were made
with this update. The MRGL risk in MN was expanded slightly
southward based on the latest positioning of the surface front (per
19Z surface analysis). Marginally severe hail accompanying elevated
overnight thunderstorms will be the primary concern here.
Elsewhere, a northeastward extension of the SLGT risk into southern
SD was considered, where middle/upper 50s dewpoints will contribute
to slightly larger buoyancy along the surface boundary. While a
localized uptick in thunderstorm intensity is possible here tonight
(as depicted by some high-resolution guidance), confidence in this
scenario is too low for the upgrade -- especially considering the
late timing/nocturnally cooling boundary layer.
See the previous discussion below for more details.
..Weinman.. 10/04/2025
.PREV DISCUSSION... /ISSUED 1110 AM CDT Sat Oct 04 2025/
...Central Rockies/High Plains into the Northern Plains...
An upper trough/low with attendant strong south-southwesterly
mid-level jet will advance eastward today from the Great Basin
across the central Rockies/High Plains, eventually reaching the
northern Plains late tonight. At the surface, a cold front extends
from the Dakotas southwestward to eastern WY/north-central CO. This
front should serve as a focus for strong to isolated severe
thunderstorms this afternoon through tonight. Recent observations
and 12Z observed soundings along/ahead of the front show limited
low-level moisture, with surface dewpoints generally in the mid 40s
to 50s. Even with filtered diurnal heating through this afternoon,
instability is forecast to remain rather weak as low-level lapse
rates gradually steepen with deep boundary layer mixing. Stronger
mid-level flow associated with the upper trough is expected to
overspread the central High Plains by mid to late afternoon, where
up to 500 J/kg of MLCAPE appears plausible.
Current expectations are for high-based thunderstorms to spread
northeastward from the central Rockies into the adjacent High Plains
this afternoon and evening in a weakly unstable but strongly sheared
environment. This may support an organized cluster or two, capable
of producing mainly isolated strong to severe gusts. The greatest
severe wind potential still appears focused across parts of
southeast WY/northeast CO into the NE Panhandle, where the Slight
Risk has been maintained with no changes. Other thunderstorms may
eventually form this evening/overnight across parts of the northern
Plains and northwest MN as low-level warm advection gradually
strengthens in tandem with an increasing southerly low-level jet.
This activity should tend to remain elevated along/north of the cold
front. But, given sufficient MUCAPE and strong deep-layer shear
forecast, the more robust cores may be capable of producing isolated
severe hail/wind.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TNTT2r
