Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Mon Aug 03 2026
Valid 031200Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF NORTHERN MINNESOTA INTO
ADJACENT PORTIONS OF THE EASTERN DAKOTAS...
...SUMMARY...
Strong to severe thunderstorm development appears possible today
across parts of northern Minnesota into adjacent portions of the
eastern Dakotas, as well as across the eastern Arizona international
border vicinity and parts of the northern Mid Atlantic through
western New England.
...Discussion...
A compact, but fairly deep, lower/mid-tropospheric cyclone over the
Canadian Prairies is forecast to migrate across northern Manitoba
into western Hudson Bay today through tonight. One initial trailing
cold front is already advancing into the northern Great Plains, with
a more substantive cold front approaching the international border
and forecast to overtake it by mid afternoon, roughly across the
northwestern Minnesota through southeastern North Dakota, central
South Dakota, and western Nebraska vicinity.
As a notable upstream mid-level short wave trough accelerates across
the northern U.S. Rockies, toward northwestern Ontario, it appears
that a secondary surface low emerging from Wyoming will weaken while
migrating northeast of the Black Hills through the adjacent middle
Missouri Valley early today. Another surface low may form along the
front across northern Minnesota into northwestern Ontario this
evening, but it appears that the most rapid deepening will occur
north of Lake Superior overnight.
To the south and southwest of the mid-level wave, models indicate
that mid-level ridging will build across the Southwest during the
day, with highest heights becoming centered along an axis across
southwestern through central Arizona into north central New Mexico
by late afternoon.
Within the downstream westerlies, a notable mid-level trough is
forecast to pivot east and northeast of the lower Great Lakes
through New England. As it does, a remnant perturbation digging
toward the southern Appalachians may evolve into a weak mid-level
low across the Southeast, cut off from the westerlies.
...Northern Great Plains into Upper Midwest...
The influence of possible early period convection and associated
cloud cover on destabilization and convective potential later today
across parts of the central and eastern Dakotas into Minnesota
remains a bit unclear. However, by mid to late afternoon, guidance
generally indicates that a fairly sharp quasi-stationary
near-surface baroclinic zone will evolve across northwestern
Minnesota through southeastern North Dakota. It appears that this
may become a focus for at least a narrow corridor of modest
boundary-layer destabilization, coincident with strengthening south
to southwesterly lower/mid-tropospheric wind fields (including
30-40+ kt around 850 mb and 50-70 kt around 500 mb). This may
provide a window of opportunity for strong to severe storm
development, including a couple of supercells, by this evening,
before the front overtakes the instability axis with the passage of
the frontal wave.
...Southeastern Arizona/adjacent New Mexico...
Low-level moisture appears likely to remain relatively modest across
central and southern Arizona, with strong daytime heating and mixing
lowering surface dew points through the mid to lower 50s F by late
afternoon. However, along the southern periphery of the stronger
mid-level ridging, it appears that this may support at least
moderate boundary layer CAPE near the international border vicinity,
beneath 25+ kt east-northeasterly mid-level steering flow.
The higher terrain either side of the southern Arizona/New Mexico
state border will provide potential for a more substantive
clustering of convection, which may propagate across and south of
the international border by early this evening. If preceding
thunderstorm development, initially developing in the unstable
environment near the international border, does not generate too
much stabilizing outflow, it is possible that this could become
supportive of a swath of strong to severe wind gusts, aided by
evaporative cooling in a deeply mixed sub-cloud layer with 40-50 F
temperature/dew point spreads.
...Northern Mid Atlantic through western New England...
Along and ahead of a weak cold front, trailing a deepening surface
low migrating northeastward toward the lower St. Lawrence Valley,
boundary-layer destabilization will probably be slowed, if not
inhibited, by weak mid-level lapse rates and early day cloud
cover/precipitation, However, strengthening deep-layer wind fields
and shear will potentially become more supportive of organized
thunderstorm development with a risk for damaging wind gusts and
perhaps a tornado or two, if pre-frontal breaks in cloud cover can
allow for sufficient destabilization with daytime heating.
..Kerr/Supinie.. 08/03/2026
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