ACUS03 KWNS 020641
SWODY3
SPC AC 020640

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0140 AM CDT Fri Oct 02 2020

Valid 041200Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

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

...Discussion...
Mid/upper flow across much of North America appears likely to
continue to trend less amplified; but, models indicate that
large-scale ridging will persist across the eastern mid-latitude
Pacific into western North America, with large-scale troughing east
of the Rockies through the Atlantic Seaboard. Embedded within this
regime, there may be several short wave perturbations comprising
more substantive troughing across the Upper Midwest into the lower
Missouri Valley at the outset of the period. This is forecast to
remain progressive, as a vigorous upstream short wave impulse digs
across the Canadian Prairies. However, models indicate that the
smaller-scale perturbations may trend out of phase. The southern
portion of the remnant troughing may become most prominent, with
perhaps the most vigorous impulse pivoting across parts of the
Ohio/Tennessee Valleys into the southern Appalachians Sunday through
Sunday night.

A reinforcing low-level cool intrusion and subsidence in the wake of
the lead mid-level troughing probably will contribute to
diminishment of initially low convective potential over the interior
U.S. Sunday. There could still be some lingering risk for
convection capable of producing lightning, beneath the mid-level
cold pool across parts of the Great Lakes and Ohio Valley into the Appalachians. However, model spread concerning the smaller-scale
mid-level perturbations is sizable. Coupled with the weak nature of
the potential instability, and probable sparse thunderstorm
coverage, any risk for thunderstorms at this point still seems less
than 10 percent.

Otherwise, seasonably moist conditions likely will remain confined
to a narrow plume along a remnant frontal zone across the
southeastern Gulf of Mexico into areas near/east of the southern Mid
Atlantic coast. This may contribute to at least low probabilities
for thunderstorms across parts of the Florida Peninsula; but, models
indicate that substantive boundary-layer moisture and instability
will remain confined to areas near and east of the
southeastern/eastern Florida Atlantic coast.

..Kerr.. 10/02/2020

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ACUS03 KWNS 030631
SWODY3
SPC AC 030630

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0130 AM CDT Sat Oct 03 2020

Valid 051200Z - 061200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

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

...Discussion...
Models indicate that broad mid-level ridging within the mid-latitude
westerlies will develop inland of the Pacific coast, across and east
of the Canadian and northern U.S. Rockies during this period.
Downstream flow across much of the remainder of the northern and
central tier of the U.S. appears likely to remain more or less
zonal, with a number of embedded, progressive short wave troughs.
This includes one significant perturbation forecast to accelerate
east of the northern Mid Atlantic coast, and support further surface
wave development along a front across the western Atlantic.

In the wake of these features, mid-level subtropical ridging may
become a bit more prominent across Florida and the northeastern Gulf
of Mexico. In lower levels, models suggest that the surface frontal
zone will weaken and redevelop northward across the Peninsula into
northern Florida. As the boundary layer continues to moisten,
destabilization aided by daytime heating across parts of the
Peninsula may contribute to at least some potential for a few
thunderstorms Monday afternoon.

Elsewhere, generally dry and/or stable conditions are expected to
prevail, with negligible risk for thunderstorm activity.

..Kerr.. 10/03/2020

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