339
ACUS01 KWNS 151633
SWODY1
SPC AC 151631

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Wed Jul 15 2026

Valid 151630Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC...NORTHERN NEW ENGLAND...NORTHERN ROCKIES/HIGH
PLAINS...PACIFIC NORTHWEST...ARIZONA...AND SOUTH-CENTRAL TEXAS...

...SUMMARY...
There is a conditional risk for severe thunderstorms capable of
producing large hail and damaging winds across parts of the
Mid-Atlantic this afternoon and evening. Isolated damaging winds
appear possible for portions of northern New England, the northern
Rockies/High Plains, Pacific Northwest, and Arizona. A brief tornado
or two may also occur across parts of south-central Texas.

...Northern Mid-Atlantic into the Northeast...
Recent surface analysis places a cold front from northern ME
southwestward into northern NY before arcing westward across
southeastern Ontario and west-northwestward across northern MI and
far northern WI into central MN. Eastern portion of this front is
expected to push southeastward through the Northeast today, moving
ahead of a low-amplitude and progressive shortwave trough currently
moving through eastern Ontario into far southern Quebec. Large-scale
ascent associated with this wave will spread across the region, but
warm temperatures aloft will likely limit thunderstorm coverage
across much of the region. A band of low-topped showers and
isolated/brief thunderstorms may develop during the afternoon
across northern New England, where forcing for ascent will be the
strongest. Overall buoyancy will be modest, but steepening low-level
lapse rates, a unidirectional/westerly wind profile with height
through mid levels, and 30-40 kt of flow around 1-2 km AGL will
support the potential for locally damaging wind gusts.

Farther south in the northern Mid-Atlantic, warm and moist
conditions will persist south of the front. However, warm mid-level
temperatures may prevent the airmass from fully destabilizing, with
lingering convective inhibition likely. Given this inhibition and
displacement farther south of the stronger forcing for ascent,
robust convective development remains highly uncertain.
Additionally, residual smoke could also limit heating, keeping
convective inhibition in place. That being said, strong deep-layer
westerly flow and steep mid-level lapse rates would support strong
outflow and perhaps even isolated hail with any storms that can
develop and mature.

...Northern Wyoming into Southern Montana...
Recent satellite imagery shows a weak vorticity maximum over eastern
ID. This vorticity max is forecast move northeastward today across
the northern Rockies and into the adjacent northern High Plains.
Diurnal heating across the higher terrain coupled with
the glancing influence of this subtle disturbance should foster the
development of scattered afternoon thunderstorms. Weak to moderate
instability is forecast, with a relatively deep and well-mixed
boundary layer across lower elevations. Scattered thunderstorm
coverage could result in some upscale growth into a loosely
organized cluster with cold pool organization, and a risk for
isolated severe wind gusts into the evening. However, the overall
severe threat should be tempered by modest deep-layer shear and
limited storm duration.

...Pacific Northwest...
Multiple rounds of isolated to scattered thunderstorms are possible
this afternoon along and east of the Cascades from central OR into
southern WA. The first round during the afternoon will be aided by
orographic influences and a weak shortwave trough preceding a closed
upper low off the coast of the Pacific Northwest. High cloud bases
and a deeply mixed boundary layer will support the potential for a
few strong gusts with this activity. Another round of storms is
possible later this evening/overnight as another weak shortwave
trough rounds the upper low as the low itself also drifts closer to
the coast. Very dry low to mid-levels will persist throughout the
evening/overnight, with the potential for isolated strong gusts
remaining possible.

...South-Central Texas...
Weak mid-level low over south-central TX will only drift slightly
westward today, remaining largely in place within the very moist
airmass over the region. Recent EWX VAD profiles show about 30 kt of
southerly flow between 1-3 km along the eastern periphery of this
low. Resulting hodographs show just enough low-level curvature to
support brief tornadoes given the tropical airmass in place.

...Arizona...
Weak east-northeasterly mid-level flow is forecast today across AZ,
which is on the southern periphery of upper ridging extending across
much of the central CONUS. Daytime heating of a seasonably moist
low-level airmass across southern/central AZ will yield modest
instability by mid afternoon. Initial development is anticipated
over the Mogollon Rim and higher terrain of southeast AZ, before
subsequently spreading westward into the lower deserts. A deeply
mixed boundary layer across the lower elevations could support
isolated strong to severe gusts.

..Mosier/Squitieri.. 07/15/2026

$$