SPC May 15, 2025 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0802 PM CDT Wed May 14 2025

Valid 150100Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN PLAINS...

...SUMMARY...
Scattered strong to severe thunderstorms will occur over parts of
the Dakotas and Nebraska this evening, and across far western Iowa
and southwestern Minnesota overnight. Very large hail, severe wind
gusts, and a couple of tornadoes will be possible. A few marginally
severe storms may also occur from the Lower Ohio Valley into the
Carolinas.

...Central and Northern Plains...
The latest water vapor imagery shows a mid-level trough in the
Rockies, with a diffluent pattern over the central and northern
Plains. A pronounced dry slot is evident from the southern Rockies
into the central Plains, with multiple bands of convection ongoing
to the north of this feature. At the surface, a dual-centered 991 mb
low is over far southwest Kansas and southern Nebraska, with an
inverted trough extending north-northeastward into the eastern
Dakotas. To the west of the trough, a cold front is moving
east-southeastward across the central and northern Plains.
Thunderstorms across the Dakotas are post-frontal, while the storms
in Nebraska are straddling the boundary on both sides. These storms
are located along an axis of low-level moisture, where surface
dewpoints are in the mid to upper 50s F.

The strongest instability is located across southwestern and central
Nebraska, where temperatures have reached the lower 80s F. Across
southern Nebraska, the RAP has MLCAPE in the 2000 to 3000 J/kg
range. So far, several semi-discrete supercells have developed along
the northern edge of the strongest instability, from near North
Platte, northward into Cherry County, Nebraska. This activity is
expected to become more linear with time, as it moves
east-northeastward across the remainder of northern Nebraska and
into southeastern South Dakota. The greatest tornado potential will
exist over the next couple hours in central and northern Nebraska,
before convection becomes more linear. The latest WSR-88D VWP at
North Platte has 0-3km storm-relative helicity near 230 m2/s2.
Low-level shear should strengthen some this evening, helping to
maintain a tornado threat with supercells that remain semi-discrete.


In addition, a plume of steep mid-level lapse rates is analyzed by
the RAP from eastern Colorado into central Nebraska. Supercells at
the northeastern edge of this plume will have a large hail threat,
and hailstones of greater than 2 inches in diameter will be
possible. The wind-damage threat will likely increase as a line
segments becomes more organized later this evening. Several
short-term models suggest that a small-scale bow echo will develop
over parts of the central Plains this evening into early tonight,
where severe gusts exceeding 70 knots will be possible. The severe
threat is expected to move northeastward into parts of Iowa and
southwest Minnesota tonight.

...Lower Ohio Valley/Southern Appalachians/Carolinas...
A positively-tilted mid-level trough is currently located from the
central Appalachians southeastward into the Carolinas. At the
surface, a moist airmass is in place across much of the region, with
surface dewpoints mostly in the 60s F. Across the moist airmass, the
RAP has moderate instability analyzed from the lower Ohio Valley
southeastward into the Carolinas. Along this corridor, moderate
deep-layer shear is present according to WSR-88D VWPs, which should
be enough for a marginal severe threat for a couple more hours this
evening. Isolated severe gusts and hail will be the primary threats.

..Broyles.. 05/15/2025

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