Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Wed Sep 09 2026
Valid 091300Z - 101200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OHIO
FROM WESTERN NEW YORK...
...SUMMARY...
Isolated strong to severe thunderstorms are possible across portions
of the central Plains to the Ohio Valley today. A more organized
severe weather threat is expected from eastern Ohio to western New
York.
...Synopsis...
Early-morning satellite imagery show broad upper troughing from the
Pacific Northwest/British Columbia through the Upper Great Lakes and
Ontario. Several shortwave troughs are embedded within this larger
upper troughing, including one moving into northern MN and another
farther north across far northwestern Ontario. A belt of moderate to
strong mid-level westerly/southwesterly flow extends between the
base of these two waves. Expectation is the southern wave to move
quickly eastward through the Upper Great Lakes and Ontario,
accompanied by mid-level jet max.
Surface analysis places a occluded low over far northwestern
Ontario, with a cold front extending southward into western Upper MI
and then back southwestward through central NE. An outflow-augmented
pre-frontal trough precedes this front, extending from a low in
southwest Lower MI to another low over northeast KS to another over
far southwest KS/far southeast CO. Both the cold front and
pre-frontal trough are expected to progress modestly
southward/southeastward today. Two corridors of relatively higher
thunderstorm coverage are anticipated this afternoon/evening, one
from eastern OH into western PA/western NY and the other farther
southwest from the Lower MO Valley into the TX/OK Panhandles.
...Central Ohio into western New York...
Moist low-levels are already in place from the OH Valley into
western PA and NY, with recent surface analysis sampling upper 60s
dewpoints in central OH decreasing to the low/mid 60s across western
PA and western NY. This moist airmass is expected to destabilize
amid modest low-level moisture advection and filtered insolation,
ahead of a convectively augmented vorticity maximum. With the cold
front still well to the northwest, this vorticity maximum will be
the primary impetus for thunderstorm development, augmenting the
weak low-level confluence along the weak pre-frontal trough. A
predominately linear/clustered storm mode is anticipated, but
strengthening mid-level flow will support effective bulk shear from
30 to 40 kt, which could support some more persist/organized line
segments. Damaging gusts are the primary risk with any of these more
organized segments. Low-level hodographs do show some notable
curative, particularly from western PA into western NY after 00Z,
amid a strengthening low-level jet. As such, there is a
low-probability tornado risk is these areas.
...Lower OH and MO Valleys into the TX/OK Panhandles...
Thunderstorm coverage is gradually expected to increase across the
region this afternoon and evening, beginning near a surface low move
across the Lower MO Valley before expanding back southwestward along
the southward-progressing front. The stronger vertical shear will be
displace north of the front, and a largely disorganized,
outflow-dominant storm mode is anticipated. Slightly better flow
aloft may favor a more focused cluster across the Mid-Mississippi
Valley into western Kentucky/Tennessee. Steep low-level lapse rates
and high cloud bases could support strong gusts from the Lower MO
Valley into the TX/OK Panhandles.
...Southern AZ...
Afternoon thunderstorms are expected over the higher terrain near
the southern AZ/NM border. There is some potential this activity
progresses westward into the lower elevations of southern AZ.
However, upper ridging will be centered over this region and
vertical shear will be weak, resulting in slow storm motion and
disorganized, outflow-dominant structures. A few strong gusts could
result from any more persistent updrafts.
..Mosier/Lyons.. 09/09/2026
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