Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Sat May 17 2025
Valid 171200Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH TEXAS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
SOUTHERN PLAINS AND OVER PORTIONS OF THE NORTHEAST...
...SUMMARY...
Severe thunderstorms producing large to very large hail, damaging
gusts and a couple of tornadoes are expected across the southern
Plains. Additional severe storms are possible across the Northeast.
...Southern Plains Region...
Strong southern-stream short-wave trough is clearly evident in
water-vapor imagery just west of the Baja Peninsula early this
morning. This feature appears to be handled well by latest model
guidance, and is forecast to advance into southern AZ/northwest
Mexico by sunrise, and to near the NM/TX border by 18/00z. There is
some indication that a weak disturbance will translate into far west
TX just ahead of the main trough, and this weak feature may prove to
be the more meaningful disturbance in regards to severe thunderstorm
development later today...especially across north TX.
Latest surface analysis depicts a sharp demarcation in moisture
along a stalled surface front across TX. Surface dew points in the
lower 70s will easily advance north with this boundary as it returns
across the southern Plains today. Extreme buoyancy will develop
across the warm sector ahead of the aforementioned disturbance, and
more pronounced short wave. 00z model guidance is fairly consistent
regarding early-day convective initiation along the dry line.
Forecast soundings suggest negligible CINH from SJT-ABI by 17-18z,
and robust convection will likely develop by early afternoon.
Deep-layer flow is more than sufficient for supercells and cool,
steep lapse rates favor very large hail (>3 inches possible) with
the strongest storms. Given the strong, consistent signal in the 00z
model guidance, will increase severe probabilities across much of
north TX to account for scattered-numerous supercells/clusters
spreading toward the DFW Metroplex by late afternoon. While
low-level shear is not particularly strong, some tornado potential
will likely exist with the more organized supercells.
Farther north across OK into southern KS, substantial
destabilization is expected as 70s dew points spread rapidly north
as a warm front establishes itself across southern KS overnight.
Precip signal is not particularly noteworthy along the dry line over
OK, but weak CINH does cause concern for isolated supercell
development. Storm potential appears somewhat greater across
southern KS near/after sunset as moisture returns to this region.
Some consideration was given to higher tornado probabilities along a
narrow wedge of northwest OK into southwest KS near the boundary for
this possibility. This may need to be adjusted in later outlooks.
...Northeast...
Strong 12hr mid-level height falls will spread across much of the
northeastern U.S. today in response to the approaching Great Lakes
upper low. High-level diffluent flow aloft will overspread much of
NY into New England as the left-exit region of the 500mb jet
translates across PA. Scattered thunderstorms are expected to
develop along/ahead of the synoptic cold front across upstate NY,
with subsequent movement expected into western New England.
Wind/hail are the primary risks with this activity, though a brief
tornado can not be ruled out with stronger supercells.
..Darrow/Halbert.. 05/17/2025
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