ACUS03 KWNS 240724
SPC AC 240723
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0223 AM CDT Mon Jul 24 2017
Valid 261200Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE UPPER GREAT LAKES AND THE ADJACENT MIDWEST REGION...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA...
Scattered strong/severe storms will be possible across portions of
the upper Great Lakes and Midwest regions Wednesday.
Upper flow-field amplification is forecast across the U.S. this
period, as phased troughing moving across the Great Lakes region
expands/strengthens, and a corresponding intensification of ridging
occurs over the West. As the western ridge expands, a short-wave
trough moving slowly inland over the West will weaken while being
shunted northeast across the northwest states.
At the surface, a cold front will continue making southeast progress
across the central third of the country, and should extend from the
Great Lakes southwest across the Midwest to the Oklahoma/northwest
Texas region by the end of the period.
Convection -- and possible/isolated severe risk -- should be ongoing
across northern and western portions of the risk area at the start
of the period, near/ahead of the advancing cold front. Warm-sector
destabilization will likely be hindered in many areas due to the
ongoing clouds/precipitation, especially across portions of the
Great Lakes area. Still, afternoon intensification of storms is
expected as the airmass diurnally destabilizes from the Wisconsin
area southwest into the Iowa vicinity. Storm organization will be
aided by relatively strong flow aloft, veering from southerly to
southwesterly with height and increasing to 40-plus kt. At this
time, hail and locally damaging winds appear to be the main risks,
with storms expected to spread east/southeast through the evening
hours before diurnally weakening overnight.