Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1205 AM CDT Wed May 20 2026

Valid 201200Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST TEXAS...

...SUMMARY...
Scattered severe storms with large hail and isolated severe gusts
are expected today across parts of west Texas. A few storms with
isolated severe gusts and hail will also be possible from the
central Appalachians into the Mid-Atlantic and far southern New
England.

...Southern High Plains...
Southwesterly mid-level flow will remain in place today over the
south-central U.S. At the surface, a quasi-stationary front will be
positioned from west Texas eastward into the Texas Hill Country.
South of the front, surface dewpoints in the 70s F will result in an
axis of moderate instability. The strongest instability is forecast
to develop from the lower Rio Grande River Valley
north-northwestward into far west Texas and eastern new Mexico. As
instability increases during the day and low-level convergence
becomes focused along the front, scattered thunderstorms are
expected to develop across far west Texas. These storms will move
eastward into west-central Texas by early to mid evening. Additional
storms may develop further north-northwest into eastern New Mexico.

RAP forecast soundings along the instability axis in the late
afternoon from Fort Stockton northward to Midland have MLCAPE near
2000 J/kg. 0-6 km is forecast to be around 50 knots with 700-500 mb
lapse rate from 7 to 8 C/km. This environment will be favorable for
supercells with large hail. The more dominant storms will have
potential for hailstones greater than 2 inches in diameter. Isolated
severe wind gusts will also be possible. A more isolated severe
threat may also develop further north-northwest across the southern
High Plains along the instability axis.

...Central Appalachians/Mid-Atlantic/Far Southern New England...
West-southwesterly mid-level flow will be in place today across much
of the eastern U.S. At the surface, a cold front will advance
southward across the central Appalachians and Mid-Atlantic. To the
south of the front, surface dewpoints in the upper 60s F will enable
an axis of moderate instability to develop by afternoon. MLCAPE is
forecast to peak in the 1000 to 2000 J/kg range in most areas ahead
of the front. Increasing low-level convergence near the front will
lead to scattered thunderstorm development during the afternoon.
These storms will move eastward across the central Appalachians,
Mid-Atlantic and far southern New England. RAP forecast soundings at
21Z along and near the instability axis have 0-6 km shear up to 25
knots with steep low-level lapse rates. This should support a severe
threat with multicell storms. Isolated severe wind gusts and hail
will be possible. The severe threat may persist into the early
evening.

..Broyles/Squitieri.. 05/20/2026