ACUS01 KWNS 241300
SWODY1
SPC AC 241258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 AM CDT Wed Jul 24 2024

Valid 241300Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN ARIZONA...

...SUMMARY...
Isolated strong to severe thunderstorms may produce damaging wind
gusts across southern Arizona, and from parts of Iowa and Illinois
into Pennsylvania/New York. Other locally strong storms are possible
in parts of the Northwest, northern Rockies and Mid-Atlantic
regions.

...Arizona...
A relatively active scenario for thunderstorms is expected later
today with the potential for thunderstorms/outflows to spread
generally south-southwestward onto the desert floor by evening. The
upper-level ridge over the western states will remain centered over
parts of Nevada/Utah today, with 15-20 kt of northeasterly mid-level
flow across central/eastern Arizona. This should help steer storms
onto the desert flow where a moist/deeply mixed boundary layer
environment will exist, with the potential for severe-caliber wind
gusts and considerable blowing dust late this afternoon into
evening.

...Midwest including Iowa/Illinois/Indiana...
The region will be influenced by the western cyclonically curved
portion of the upper-level trough over the Great Lakes/Ontario, with
a cold front moving southward across Iowa/Illinois and into
Indiana/Ohio, with very warm and humid conditions south of the
front. Some thunderstorms are ongoing this morning across eastern
Iowa and northern Illinois, but a greater coverage and intensity of
storms is expected later this afternoon near/south of the front.
Moderately strong west-northwesterly flow aloft, steep lapse rates,
and ample buoyancy suggest the potential for strong/isolated severe
storms capable of damaging winds and some hail.

...Northeast including Pennsylvania/New York....
As a front sags into western New York, modestly enhanced
southwesterly low-level winds will strengthen warm advection and
lift over the region. This will likely lead to scattered
thunderstorms through the afternoon. Forecast soundings show MLCAPE
values over 1000 J/kg and sufficient deep-layer shear for a few
organized storm clusters capable of locally gusty/damaging winds.

...North Carolina/Virginia...
Deep west-southwesterly winds will strengthen by this afternoon
along a corridor from the southern Appalachians into the
Mid-Atlantic states. This enhanced flow/shear profile will aid in
helping to organize scattered diurnal thunderstorm development from
western North Carolina into parts of southern/eastern Virginia.
Mid-level lapse rates will be poor, but strong heating and high PWAT
values will promote a risk of a few intense storm clusters capable
of gusty/damaging winds.

...Northwest...
Relatively fast cyclonic flow aloft will remain over the Pacific
Northwest states into the northern Great Basin. Mid-level moisture
will spread eastward and aid in afternoon thunderstorm development
from Oregon into parts of Idaho/Montana. Forecast soundings show
weak CAPE, but a few of the stronger cells could produce locally
gusty/damaging winds.

...Coastal Texas/southern Louisiana...
Aided by the possibility of weak surface low development, some
guidance suggests that a modest strengthening of low-level flow may
occur today. However, mid-level winds will remain weak, with inland
destabilization expected to be limited. This should minimize the
potential for anything beyond a few very weak/transient
mesocyclones.

..Guyer/Jewell.. 07/24/2024

$$
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