461
ACUS02 KWNS 211730
SWODY2
SPC AC 211729

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Fri Jun 21 2024

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR ADJACENT
PORTIONS OF MISSOURI...IOWA...ILLINOIS...AND WISCONSIN...

...SUMMARY...
Severe storms will be possible across the upper Mississippi Valley
and upper Midwest on Saturday. Damaging wind, isolated hail, and a
tornado or two are all possible.

...East-central Great Plains into the upper Midwest...
A convectively augmented mid-level disturbance will move east across
WI into MI during the morning into the early afternoon.
Showers/thunderstorms will likely accompany this feature with some
strong to severe risk possible, especially on a localized basis over
the northern half of Lower MI as some heating contributes to
destabilization.  In the wake of morning convection, moderate to
locally strong buoyancy is expected to develop from eastern
KS/southeast NE northeastward into parts of southern WI/northern IL,
along/south of an outflow-reinforced front.  Scattered to numerous
thunderstorms are expected to develop along the front by
late afternoon into the evening from northern MO to the Lake MI
vicinity.  Effective shear generally in the 30-40 kt range will
support a few organized cells/clusters.  Relatively strong heating
and large PW will support strong/damaging gusts as the most likely
hazard.  Warm 500-mb temperatures (-6 to -8 deg C) will tend to
limit the overall magnitude of buoyancy and the potential hail risk
with the stronger cells.  A tornado or two will also be possible, in
the presence of moderate low-level southwesterly flow and modestly
enhanced SRH.

Farther east, intensification of morning convection and/or afternoon
redevelopment will be possible across parts of Lower MI. While
instability will be weaker compared to areas father west, somewhat
enhanced low/midlevel flow will support a threat for isolated
damaging wind and possibly a brief tornado.

...South-central AZ...
Model forecast soundings show seasonally high PW across the Sonoran
Desert on Saturday.  Intense surface heating will result in surface
temperatures quickly rising into the 100s across the lower desert
with mainly 50s deg F dewpoints.  Very steep 0-3 km lapse rates and
weak buoyancy will probably lead to isolated thunderstorm
development initially in orographically favored locations.  Existing
storms` cold pools may potentially interact and promote additional
storms during the evening.  The environment in which these
pulse-like thunderstorms develop will support large evaporative
potential with the downdrafts.  The more water-laden cores will
possibly yield a risk for severe gusts (60-75 mph) before this
activity diminishes in the 03-05z period.

...Parts of the Northeast...
Model guidance continues to indicate widely scattered thunderstorms
will be possible across parts of the Northeast during the afternoon
and evening, within a warm, moderately unstable, and weakly capped
environment along/south of a cold front draped across parts of New
England.  Isolated strong to locally severe gusts (50-60 mph) are
possible with the stronger storms.

...Parts of ND...
No change in thinking from the previous forecast.  A mid/upper-level
shortwave trough will move across parts of SK/MB on Saturday, with
some influence of this shortwave expected to extend into parts of
ND.  Isolated to widely scattered thunderstorm development will be
possible during the afternoon/evening, with moderate buoyancy and
sufficient deep-layer shear supporting potential for a few organized
storms capable of isolated hail and strong/severe gusts.

..Smith.. 06/21/2024

$$