Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat May 17 2025
Valid 172000Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER NORTHEAST TEXAS...SOUTHEAST OKLAHOMA...SOUTHWEST
ARKANSAS...AND NORTHWEST LOUISIANA.......
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF
UPSTATE NEW YORK AND WESTERN NEW ENGLAND...
...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.
...20z Update...
Adjustments were made to the 20z to remove the Marginal risk across
portions of Georgia into South Carolina and across the northeast
behind morning convection.
The Slight Risk and Moderate Risk were nudged further south in far
southern Texas to account for potential for storms to come out of
Mexico this evening with potential for large hail and severe winds.
Otherwise, the risk areas across the main region of the
southern/central Plains were not changed. Thunderstorm development
has begun across the dryline from southern/central Texas to the Red
River in Oklahoma. See MCD#840 and MCD#838 for more information on
the short term risks in these areas.
..Thornton/Hart.. 05/17/2025
.PREV DISCUSSION... /ISSUED 1117 AM CDT Sat May 17 2025/
...Central TX/Southern OK into the ArkLaTex Region...
Morning water vapor loop shows a well-defined shortwave trough over
southern AZ tracking northeastward. Ahead of this system, southerly
low-level winds and steep lapse rates aloft have established a very
moist and extremely unstable air mass from southern OK into central
TX. Dewpoints in the low/mid 70s and ample daytime heating will
yield afternoon MLCAPE values over 4000 J/kg. As the upper system
and associated mid-level jet max approach the dryline, thunderstorms
are expected to rapidly develop by mid-afternoon. Splitting
supercells capable of very large hail will be the main initial
concern, along with damaging winds and a tornado or two. Most model
solutions suggest upscale growth of these storms into a bowing MCS
by evening, tracking eastward across the ArklaTex region. Have
extended the ENH a little farther east to accommodate this scenario,
with damaging winds and large hail being the main concerns. This
cluster of storms may persist overnight, tracking into
central/northern MS.
...Northwest OK...
The plume of dense cirrus ahead of the AZ shortwave trough will move
east of northwest OK by late afternoon, allowing strong heating and
destabilization. This combined with southeasterly low level winds
near a retreating warm front will provide a corridor of strong
instability and favorable low-level shear for supercell development.
The coverage of storms in this area is uncertain and varied between
the morning CAM solutions. However, the storms that form will pose
a risk of very large hail, damaging winds, and a tornado or two. It
is also unclear how far east this threat may persist, with some
concern for an MCS tracking into northeast OK overnight.
...NY/New England...
A progressive shortwave trough and associated mid-level jet is
tracking eastward across the Great Lakes region today. Cooling
temperatures aloft and strong daytime heating will lead to pockets
of moderate CAPE and steep low/mid level lapse rates. Storms are
beginning to form across NY and will move into a progressively more
favorable air mass for strong/severe convection (including a few
supercells) by mid-afternoon. Locally damaging winds are the main
concern, but the strongest cells could also produce hail and perhaps
a tornado or two. Refer to MCD #837 for further details.
Read more CHECK UPDATE ZOOM GRAPHIC
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