655
ACUS03 KWNS 030728
SWODY3
SPC AC 030727

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 AM CDT Wed Sep 03 2025

Valid 051200Z - 061200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms will be possible across much of the West, the southern
Rockies, Florida, and along and near a frontal boundary from New
England into the southern Plains. Widespread organized severe
weather is not anticipated.

... Discussion ...

The amplified midlevel pattern of the previous few days will persist
through Friday/Day-3 across North America, with a western Canada
ridge and a continental-scale trough across eastern Canada and the
eastern US. Within the eastern trough, a seasonably strong closed
low over Ontario should begin to fill by late in the forecast
period. As this is occurring, multiple shortwave troughs traversing
the larger scale flow field will rotate around the Ontario low.

The strongest of these shortwave troughs will have moved south
through Canada the day before and should be located in the vicinity
of the Lower Great Lakes at the start of the forecast period. In
response to this shortwave trough, strong northerly low-to-mid-level
flow across the Plains overnight Thursday into Friday will help
tighten the low-level thermal gradient across the Plains. This front
will slowly move south through Friday into Friday night.

A modest surface low is expected to develop across southwest
Oklahoma or northwest Texas, along the surface front, by Friday
morning. This surface low should slowly sag south through the day
with the front. Despite moving south, away from Oklahoma, the flow
around this surface low will still be able to draw Gulf moisture
northward into Oklahoma and Arkansas. As this increasing low-level
moisture converges along the front, diurnal heating of this
moistening airmass will yield most-unstable CAPE values perhaps in
excess of 3000 J/kg along and south of the surface front.

Despite the strong instability and strong thermal gradient, the slow
moving nature of the front will tend to favor anafrontal
circulations. This appears to be borne out in the latest operational
guidance suite with precipitation being favored on the cold side of
the thermal gradient. This would tend to limit the overall risk of
severe weather. However, given the degree of instability and the
presence of a strong cold front, the risk of warm-sector convection
remains. If confidence in warm-sector convection occurring
increases, severe probabilities may be warranted across portions of
eastern Oklahoma east through Arkansas into western Tennessee and
northern Mississippi.

..Marsh.. 09/03/2025

$$