SPC Jun 17, 2025 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1203 PM CDT Tue Jun 17 2025

Valid 181200Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
LOWER MICHIGAN INTO NORTHWEST OHIO...INDIANA...SOUTHERN
ILLINOIS/MISSOURI...AND EXTREME WESTERN KENTUCKY...

...SUMMARY...
Strong to severe storms are expected on Wednesday from parts of
southern Missouri northeastward into southern lower Michigan.
Damaging winds, isolated hail, and a few tornadoes will be possible.
More isolated severe storms may develop across the southern Plains.

...Synopsis...
A mid-level trough will traverse from MO/IA to the Southern Great
Lakes on Wednesday. A surface low will accompany this mid-level
trough and move from eastern Iowa to Michigan. A cold front will
extend from this surface low to the southern Great Plains. Severe
thunderstorms are expected along much of this frontal zone on
Wednesday.

...Midwest into the Southern Great Lakes...
Upper 60s to low 70s dewpoints will be present ahead of a cold front
across the Midwest/Great Lakes on Wednesday morning. Some cloudcover
is likely across the region, but only minimal heating (mid 70s)
appears necessary for convective initiation. Therefore, expect
relatively early storm development along and ahead of a cold front
north of I-70 during the late morning to mid-day timeframe. Moderate
instability and modest shear (35 to 40 knots) will promote storm
organization. Very weak (~5.5 C/km) mid-level lapse rates amid a
moist profile, should mostly limit hail production. Therefore,
damaging wind gusts will likely be the primary threat. However, some
tornado threat will also exist as forecast soundings show strong
low-level curvature and significant streamwise vorticity in the
lowest 1km. There is some uncertainty with storm mode, but a tornado
threat would exist with either a broken line or a QLCS as it moves
across northern Indiana into southern Michigan and northwest Ohio. 

...Ozarks into the Mid-Mississippi Valley...
There is uncertainty across southern Missouri and northern Arkansas
regarding the strength of morning convection across the region. It
is unclear whether this morning convection will reintensify and move
east/northeast with a renewed threat, or if additional development
will occur during the afternoon and be the primary threat. However,
given the lack of strong low-level jet support, expect the overnight
MCS to be weakening by morning with the additional afternoon
development solution preferred. Moderate to potentially strong
instability is forecast by mid-afternoon with modest (25-30 knots)
of shear. This will support mostly multicell clusters with a threat
for damaging wind gusts. 

...Southern Plains...
Strong heating is forecast south of the boundary across the southern
Plains. This will result in moderate to potentially strong
instability amid 25-30 knots of shear. Very warm 700mb temperatures
(12C) will likely limit overall convective coverage. However,
forecast soundings show a mostly uncapped environment where a
surface boundary should be present. Therefore, at least isolated
storms are possible. Modest shear and very steep lapse rates will
support some hail/wind threat from any storms which can develop
within this region. 

...Northern Plains...
Despite generally limited low-level moisture, relatively steep lapse
rates and cool temperatures aloft may support a pocket of moderate
destabilization across parts of far northeast MT and ND into
northern MN Wednesday afternoon. Wind profiles will be relatively
weak and unidirectional, but a couple stronger cells or clusters
will be possible during the afternoon and evening, with localized
potential for hail and strong to severe gusts.

...Mid Atlantic...
Strong heating, combined with low 70s dewpoints will result in
moderate to strong instability in the Mid-Atlantic on Wednesday. 12Z
guidance has trended weaker with a belt of mid-level flow across the
Mid-Atlantic Wednesday afternoon/evening. However, sufficient
mid-level flow is still forecast for modest shear and some multicell
clusters. Damaging wind gusts will be the primary threat from these
scattered storms.

..Bentley.. 06/17/2025

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