SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 PM CDT Wed Jun 15 2022
Valid 152000Z - 161200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF WISCONSIN...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN APPALACHIANS TO THE CENTRAL GULF COAST
STATES...
...SUMMARY...
Scattered severe thunderstorms are likely this afternoon into
tonight across parts of the Upper Midwest and Upper Great Lakes.
Several tornadoes, large to very large hail, and damaging winds all
appear likely. Some of the tornadoes could be strong.
...Discussion...
The current outlook continues to accurately reflect future
expectations, as the anticipated severe weather event begins to
unfold across the Upper Mississippi Valley/Upper Great Lakes region.
Storms are expected to increase substantially in coverage and
intensity over the next few hours, in and near the newly issued
tornado watch across this area.
Storms are also evolving now across the central and southern
Appalachians, and southeastward across the Savannah River Valley
area, with a ramp-up in severe potential over the next couple of
hours expected in this region as well.
Given current and anticipated convective trends, only minor tweaks
to the outlook areas appears necessary in this update.
..Goss.. 06/15/2022
.PREV DISCUSSION... /ISSUED 1217 PM CDT Wed Jun 15 2022/
...Upper Midwest including Wisconsin/Iowa/Upper Michigan...
A regional outbreak of severe storms is expected this afternoon and
evening, particularly across eastern Iowa/far southeast Minnesota
into southern/central/eastern Wisconsin and Upper Michigan. Aside
from large hail, this includes the potential for tornadoes, some of
which may be strong, along with a focused corridor of appreciable
damaging wind potential.
Related to a decayed overnight MCS, morning surface analysis shows a
precipitation-reinforced semi-stalled boundary extending from
west/central Iowa into southwest/central Wisconsin, with some
persistent precipitation and a few stronger storms/differential
heating reinforcing this boundary. A notable upper trough over the
northern Plains will influence the region particularly later today
into tonight with increasing large-scale forcing for ascent and
strengthening deep-layer southwesterly winds. Modest surface
cyclogenesis is expected along the southwest/northeast-oriented
boundary, with the gradually deepening wave expected to help
maintain an easterly component to the near-surface winds.
Surface dewpoints in the lower 70s F and steep mid-level lapse rates
will yield MLCAPE values of 3000+ J/kg especially from eastern Iowa
into much of central/southern Wisconsin. Strong deep-layer shear and
large hodographs will promote supercells capable of very large hail
and a few tornadoes during the first several hours of surface-based
initiation. A few of the tornadoes could be strong (EF2+), although
there are some mode-related uncertainties over time. Storms are
likely to trend upscale across interior parts (central/southern) of
Wisconsin with damaging wind potential appreciably increasing.
Storms will move into Lower Michigan and northern Illinois after
sunset, with a continued risk of locally damaging wind gusts
persisting, potentially as far east as Lower Michigan and northern
Indiana.
...Southeast/Mid-Atlantic/Northeast States...
A hot and humid low-level air mass is in place today from the
central/northern Appalachians and interior Carolinas southwestward
into Mississippi/Alabama, with widespread temperatures in the 90s
and dewpoints in the upper 60s and lower 70s. This will result in
MLCAPE values over 3000 J/kg and steep low-level lapse rates
throughout the region. The details of the timing and location of
convective development remains uncertain even in the short-term, but
multiple corridors of storms may unfold this afternoon into tonight
on the periphery of the southern Appalachians-centered upper-level
ridge. Sufficiently strong northeasterly flow aloft will aid in
southwestward-propagating clusters capable of strong/damaging wind
gusts. A conditional severe risk will exist as far north as
west-central Pennsylvania and western New York today near the front.
Several models also imply the potential for late-night MCS
development centered across southern New York/west-central
Pennsylvania into Maryland.
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