ACUS01 KWNS 151244
SWODY1
SPC AC 151243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Thu Aug 15 2024

Valid 151300Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE OZARKS...LOWER MISSOURI VALLEY...AND ILLINOIS...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the
Midwest through tonight.  Severe gusts capable of wind damage and
large hail are the primary risks with the stronger thunderstorms.

...Central Plains to the Mid Mississippi Valley...
Morning water-vapor imagery shows a series of embedded disturbances
rotating through a larger-scale trough centered over the northern
Great Plains.  A notable shortwave trough is located near the
WY/NE/SD vicinity and this feature will move east reaching the Upper
Great Lakes by Friday morning.  A lead convectively augmented
disturbance is moving east across the mid MS Valley this morning,
and it will move east into the southern Great Lakes and weaken
during the day.  Broken bands of showers/thunderstorms associated
with this lead impulse will progress east this morning and move into
a less unstable airmass across the Wabash Valley.  Some rejuvenation
of storms is possible later today on the southern portion of the
trailing outflow near the MS-OH River confluence westward into the
Ozarks.  Appreciable uncertainty exists at this time on the
intensity/coverage of storms in the aforementioned corridor.
Nonetheless, heating of a moist airmass will potentially yield an
environment favorable for at least isolated to widely scattered
storms capable of a wind/hail threat.

In wake of the early day cloud debris and overnight storm activity,
strong boundary-layer heating is expected across much of the Plains
into portions of the mid MS Valley.  As a result, strong buoyancy
will develop along the eastern edge of this steeper lapse-rate
plume.  Model guidance suggests very strong instability (MLCAPE
>3000 J/kg) will probably develop by mid-late afternoon from
portions of eastern KS/MO into southern IA.  Thunderstorms may focus
along a synoptic front that will arc from southeast MN-eastern
IA-northern MO-southeast KS-northern OK by late afternoon.  Some
guidance (i.e., 00Z MPAS and recent HRRR runs) indicates lower storm
coverage until later this evening across the lower MO Valley/mid MS
Valley portion of the Slight Risk.  Regardless, deep-layer shear
should be adequate for supercells and organized clusters and
wind/hail can be expected with the most robust updrafts.  High-based
thunderstorms are also expected to develop along the trailing
boundary into the southern Plains where surface temperatures will
easily rise through the upper 90s to near 100F.  The stronger
evaporatively cooled downdrafts will potentially result in severe
gusts before this activity diminishes by mid-late evening.

...New England...
Upper troughing will hold across New England today with cool
mid-level temperatures and modest northerly flow at 500mb. Strong
boundary-layer heating will allow convective temperatures to be
breached by 19z and scattered convection is expected to develop
within a sheared environment that favors robust multi-cell updrafts.
Some of this activity could generate strong gusts and marginally
severe hail.  Convection will be diurnally driven and should weaken
with loss of daytime heating.

...Northern Rockies...
A mid- to upper-level trough over the Pacific Northwest will
gradually move northeast impinging on the northern Rockies by
afternoon.  The favorable timing of large-scale ascent and diurnal
destabilization will yield scattered to numerous thunderstorms
developing from the Upper Snake Valley north-northwestward into
north-central ID and western MT by early evening.  Forecast
soundings show steep lapse rates and potentially favorable for
localized severe gusts with the stronger thunderstorm cores and
outflow-dominant clusters.

..Smith.. 08/15/2024

$$
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