Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Wed Jul 15 2026
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NEW ENGLAND...THE MID-ATLANTIC...NORTHERN ROCKIES...AND ARIZONA...
...SUMMARY...
There is a conditional risk for severe storms capable of large hail
and damaging winds in the Mid-Atlantic Wednesday afternoon and
evening. Isolated occurrences of mainly damaging wind gusts appear
possible in northern New England, the northern Rockies, and Arizona.
...Synopsis...
A high-over-low blocking pattern will remain anchored over central
North America with an embedded shortwave trough and associated 70 kt
mid-level jet streak translating through New England and the
northern Mid-Atlantic Wednesday afternoon. That system will be
attended by a surface front, which will settle south into the
central Mid-Atlantic during the peak of the diurnal heating cycle.
...Mid-Atlantic...
Temperatures in the 90s to around 100 are forecast south of the
front, which coupled with dewpoints in the upper 60s to low 70s,
will contribute to a moderately unstable air mass by afternoon with
MLCAPE of 1500-2500 J/kg. The strongest height falls/forcing for
ascent associated with the shortwave trough are expected to remain
north of the surface frontal zone, and as a result, the extent of
thunderstorm development along the boundary remains uncertain.
Another factor that could limit storm development is the potential
for instability reduction along the front due to the existence of
wildfire smoke, as depicted in recent HRRR runs.
Given the uncertainty in storm initiation and sustenance, a level
1/Marginal Risk will be maintained with this forecast. However, on
the condition that surface-based storms develop, the presence of
seasonably strong mid-level winds and resultant 40-50+ kt of
effective bulk shear will support supercells capable of large hail
and damaging winds.
...Northern New England...
Within the zone of strongest forcing for ascent associated with the
shortwave trough, a band of low-topped showers and thunderstorms is
expected to develop during the afternoon amidst a marginally
unstable environment. Steepening low-level lapse rates and a
unidirectional wind profile with 35-40 kt winds as low as 1.5-2.0 km
AGL will support the potential for locally damaging wind gusts.
...South-central Montana and north-central Wyoming...
Heating along the high terrain coupled with the glancing influence
of a subtle disturbance is expected to foster widely scattered
afternoon thunderstorms amidst a moderately unstable air mass
featuring a relatively deep, well-mixed boundary layer. A number of
the 00Z CAMs indicate the potential for some cold pool organization
with an attendant risk for isolated severe wind gusts into the
evening.
...Arizona...
Scattered afternoon and evening thunderstorms are expected from the
Colorado and San Francisco Plateaus into the Sonoran Desert amidst a
moderately unstable air mass with a deep and well-mixed boundary
layer. That thermodynamic environment will be supportive of isolated
strong downbursts; however, more organized severe wind gust
potential is expected to be limited by the weak vertical shear that
is forecast.
..Mead/Lyons.. 07/15/2026
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