SPC AC 291730
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sat Jun 29 2019
Valid 301200Z - 011200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
THE UPPER MISSISSIPPI VALLEY AND NORTHERN PLAINS AS WELL AS THE
NORTHERN HIGH PLAINS...
Strong to severe storms are possible Sunday from the upper
Mississippi Valley through the northern Plains, with damaging wind
and hail the main threats. A few strong storms with hail and gusty
winds are possible over southern New England from late morning into
...Upper Mississippi Valley region into the northern Plains...
The northern periphery of the upper ridge over the northern Plains
will be suppressed by a shortwave trough that will move east through
Saskatchewan and Manitoba Sunday. This feature will be accompanied
by a cold front that will extend from northwest MN to western NE by
12Z Sunday. By 00Z the cold front will extend from the western upper
peninsula of MI through southern MN and into western NE where it
will remain stationary. A warm front will have advanced north and
should stretch from northeast MN through central WI and into the OH
Though model solutions vary on the location/timing, an MCS should be
ongoing just north /east of the warm front from eastern MN into
northern or central WI. This feature may pose an ongoing threat for
mainly damaging wind. The warm sector will become very unstable
during the afternoon with a plume of steeper (7-7.5 C/km) mid-level
lapse spreading east above a very moist boundary layer with
dewpoints in the low 70s F contributing to 3000-3500 J/kg MLCAPE.
Diabatic warming of the surface layer should occur downstream of the
MCS and reintensification is expected during the afternoon as the
storms advance south and southeast through the remainder of WI and
into IL along and just to the cool side of the warm front. Damaging
wind and hail are expected as activity continues southward through
northern IL. Other storms may develop along cold front across
southern MN into southeast SD during the afternoon. Wind profiles
with weak vertical shear will favor multicells, but the
thermodynamic environment will promote a threat for damaging wind
and large hail.
...Northern High Plains...
Easterly post frontal upslope flow will develop from southeast MT
into northeast WY with dewpoints generally in the 50s to around 60F.
Plume of steeper lapse rates will persist over this region and the
atmosphere should become moderately unstable as low clouds mix out
from the west. Storms should develop during the afternoon over the
higher terrain and spread east into the High Plains where wind
profiles with 30-40 kt effective shear will support some supercell
structures. Large hail and isolated damaging wind will be possible
from late afternoon into mid evening.
...Southern New England...
Cold temperatures aloft associated with an amplifying upper trough
will overspread this region generally along and north of a cold
front that should move through southern New England the first half
of the day. Diabatic warming will further destabilize the atmosphere
with 500-1000 J/kg MLCAPE possible. Storms developing within this
regime may produce a few instances of hail and gusty winds from late
morning into mid afternoon.
...MAXIMUM RISK BY HAZARD...
Tornado: 2% - Marginal
Wind: 15% - Slight
Hail: 15% - Slight
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z