560
ACUS03 KWNS 270703
SWODY3
SPC AC 270702

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0202 AM CDT Sat Sep 27 2025

Valid 291200Z - 301200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for severe thunderstorms appears negligible across the U.S.
Monday through Monday night.

...Discussion...
Amplification within the westerlies appears likely to continue to
translate eastward through this period, with mid-level ridging
building across much of interior Canada and adjacent portions of the
northern U.S. and downstream troughing slowly digging across the
northwestern Atlantic through Canadian Maritimes and northern New
England.  Upstream, large-scale troughing across the mid-latitude
eastern Pacific into western North America may begin to lose
amplitude, as a couple of embedded short waves progress
northeastward inland of coastal areas.  However, it appears that
deeper troughing will be reinforced offshore of the British
Columbia/Pacific Northwest coast by a much more vigorous digging
short wave trough, which models indicate will support renewed
significant cyclogenesis across the northeastern Pacific.

In the southern mid- to subtropical latitudes preceding this regime,
troughing within generally weak flow is forecast to slowly shift
east/northeast of the southern Rockies into the Great Plains Monday
through Monday night.  However, it appears that a downstream
mid-level high will be maintained across the Midwest, and models
indicate little general movement to weak mid-level troughing across
the Southeast.

A pair of tropical cyclones are likely to continue slowly migrating
north-northwestward across parts of the subtropical western
Atlantic, including one north of the Bahamas toward the Carolina
coast.

...Carolina coastal vicinity...
The timing of the approach of Potential Tropical Cyclone Nine
remains uncertain, with increasing impacts along coastal areas most
probable late Monday night or later.  However, as it approaches
coastal areas, the latest NAM output, among other guidance, suggests
that cool advection aided by strengthening north to northeasterly
near surface flow may contribute to a better-defined baroclinic zone
near the Carolina coast, perhaps reinforced to the cool side of the
boundary by evaporation of precipitation spreading downstream of the
cyclone.  Even if enlarged, clockwise curved low-level hodographs do
evolve along coastal areas late in the period, the potential for the
inland advection of a sufficiently moist and buoyant boundary layer
to support a risk for tornadoes still appears negligible at this
time.

..Kerr.. 09/27/2025

$$