SPC Apr 1, 2025 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1233 PM CDT Tue Apr 01 2025

Valid 021200Z - 031200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THE
MID-MISSISSIPPI VALLEY TO THE LOWER OHIO VALLEY...

...SUMMARY...
Numerous severe storms are likely Wednesday and Wednesday night
across the southern Great Lakes, Mid Mississippi Valley, and North
Texas into the ArkLaTex. Severe wind gusts, very large hail, and
strong tornadoes are possible.

...Synopsis...
A broad mid-level trough and powerful 100+ kt jet streak will
accelerate northeastward from the central Plains to the Great Lakes 
on Wednesday. Strong ascent from the advancing upper trough and
primary shortwave impulse will support a deep (~990mb) surface low
moving from the northern Plains into the western Great Lakes. A warm
front will rapidly move north through the morning which will allow
for a broad warm sector featuring 60s F dewpoints to expand as far
north as eastern Iowa to north-central Ohio/southern Michigan by
Wednesday afternoon/evening.  A cold front attendant to the deep
surface cyclone will sweep eastward, with widespread strong to
severe storms expected to be ongoing along/ahead of the front at
daybreak.

...Mid Mississippi Valley to the Lower Ohio Valley...
Thunderstorms will likely be ongoing from northeast Texas to the
Upper Midwest at the beginning of the period. East of this activity,
a warm front will surge rapidly north across Illinois and Indiana
with mid 60s dewpoints expected across the Mid-Mississippi Valley to
the Lower Ohio Valley by mid-day. As temperatures warm into the
upper 70s to low 80s, moderate to strong instability will develop by
early afternoon. A cap, centered around 700mb, should keep deeper
convection suppressed for much of the day. However, as height falls
overspread the warm sector after 21Z and ascent increases in the
right entrance region of the upper-level jet, this cap will erode.
Simultaneously, even richer low-level theta-e, with upper 60s
dewpoints and mean mixing ratio in excess of 14 g/kg will advect
into the mid-Mississippi valley. This will provide an environment
for explosive supercell development given 45-55 knots of effective
shear. In addition, low-level shear will support the threat for
tornadoes.

A broad, strong low-level jet will be present across the warm sector
for the entire day. However, there will be some relative weakening
during the 18-22Z period. This may limit the tornado threat
initially, but by 00Z, most guidance shows a renewed low-level jet
strengthening and elongating of the hodographs. Therefore, the
primary threat could be hail for a few hours during the evening
before the tornado threat increases by 23Z-00Z and persists into the
evening hours. Orientation of the storms and potential for training
do provide some uncertainty, but in the moist environment, expect
multiple mature supercells to persist into the evening when very
strong low-level shear develops. Multiple strong to potentially
intense tornadoes are possible during this period. 

...North Texas to the ArkLaTex...
Late Wednesday night (after 06Z Thu), initially elevated supercells
will likely develop along and north of the front across northwest
Texas. Hail will be the primary threat initially, but some damaging
wind threat will also exist from these elevated storms. As they move
east, and the front starts to move northward, these storms may
eventually become surface-based early Thursday morning along the Red
River from north-central Texas to the ArkLaTex.

...Upper Midwest to Upper Great Lakes...
A conditional, potentially potent, severe weather threat could
materialize across northern Illinois and into southern Michigan on
Wednesday. This area, closer to the surface low and beneath the very
strong mid-level jet streak, will have a wind profile favorable for
all severe weather hazards. However, destabilization will depend
heavily on the overnight convection Tuesday night from the central
Plains into Missouri. If morning convection can clear, and
especially if even broken clouds can permit some heating across some
of the region, a greater tornado threat is possible across parts of
northern Illinois.

..Bentley.. 04/01/2025

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