Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Mon Jun 30 2025
Valid 301300Z - 011200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS
OF THE DESERT SOUTHWEST AND WEST COAST...
...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
southern Plains into the Midwest and the Mid-Atlantic, and in parts
of the Desert Southwest, and also in adjacent parts of southern
Oregon and northern California today.
...Synopsis...
Water-vapor imagery this morning shows an upper trough over the
Dakotas/Upper Midwest, and this feature is forecast to move into the
Great Lakes by tonight. At the same time, sub-tropical ridging will
build over the Plains, keeping stronger flow aloft displaced to the
north. Farther west, an upper trough/low will meander slowly
eastward over the eastern Pacific towards the CA coast. At the
surface, a weak cold front will sag southward from the
Midwest to the southern Plains.
...Southern Plains into the Midwest and Mid-Atlantic states...
A myriad of prior convective outflow in addition to the cold front
will serve as foci for storm development today. Ahead of the
slow-moving cold front, rich low-level moisture and heating will
lead to moderate to strong destabilization in areas void of
persistent early day cloud debris. Small clusters and bands of
storms may locally concentrate some damaging-wind threat, but
predictability of these meso-beta corridors remains uncertain.
Nonetheless, scattered storms will gradually progress east and
southward during the day and through the evening across the Marginal
Risk area. Strong to severe downdrafts will be the primary severe
threat, but large hail may occur with a few storms over parts of the
southern Plains where lapse rates/buoyancy are greater than areas
farther northeast. The overall severe threat will likely remain
tempered by weak to modest mid-level flow.
...Southwest NM and far southeast AZ...
Strong heating of an adequately moist airmass will result in
appreciable buoyancy by peak heating. Scattered thunderstorms
developing within an environment characterized by very steep lapse
rates and inverted-v profiles, will support isolated severe gusts
(60-70 mph) with the stronger evaporatively cooled downdrafts during
the late afternoon and early evening.
...Northern CA into southern OR...
Ahead of the weak upper trough immediately west of the CA coast,
southerly flow will aid in increasing mid-level moisture across
parts of northern CA and southern OR. Ample heating coupled with
weak large-scale and orographic ascent will aid in isolated to
scattered high-based thunderstorm development. Very steep lapse
rates and a deep, dry sub cloud layer will favor evaporatively
cooled downdrafts capable of isolated 55-65 mph gusts.
..Smith/Broyles.. 06/30/2025
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