913
ACUS01 KWNS 300600
SWODY1
SPC AC 300559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Thu May 30 2024

Valid 301200Z - 311200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST TEXAS...

...SUMMARY...
Scattered severe storms are expected this afternoon and evening
across parts of the southern Plains and central High Plains, where
large hail and wind damage will be possible. The greatest severe
threat should be in parts of west Texas, where hailstones greater
than 2 inches in diameter may occur. A more isolated severe threat
is expected further east across parts of the central Plains,
Ark-La-Tex and Sabine River Valley.

...Southern and Central Plains...
An upper-level trough will move eastward across the northern High
Plains today, as west-northwesterly mid-level flow remains over much
of the southern and central Plains. An MCS is expected to be ongoing
at the start of the period over parts of Nebraska, Kansas and
Oklahoma. This convection is forecast to move eastward into the
Ozarks and Ark-La-Tex during the day, and could be accompanied by a
marginal severe threat. Further to the west, a shortwave trough is
forecast to move eastward into the southern High Plains during the
day. A moist and unstable airmass will be in place ahead of the
shortwave trough across much of the region. During the afternoon, a
dryline will likely become focused from southeast Colorado extending
southward across far eastern New Mexico. As surface temperatures
warm during the afternoon, scattered convective initiation is
expected along and to the east of the dryline. As storm coverage
increases during the late afternoon and early to mid evening, MCS
development will become likely.

The airmass to the east of the dryline is forecast to become
moderately to strongly unstable by afternoon. The deterministic
models suggest that MLCAPE will reach the 2500 to 4000 J/kg range by
mid to late afternoon. RAP forecast soundings during the late
afternoon near the western edge of the moist sector have surface
dewpoints in the upper 50s F with 0-6 km shear around 40 knots, and
700-500 mb lapse rates near 8 C/km. This environment will be
favorable for supercells with large hail. As cells mature during the
late afternoon and early evening, hailstones over 2 inches in
diameter will be possible with the more dominant storms. The
greatest threat for large hail is expected from near Amarillo
southward to near Lubbock, where the combination of mid-level lapse
rates and instability is forecast to be most favorable. An isolated
tornado threat could also develop, and will be dependent upon
mesoscale factors. As an MCS organizes and moves eastward into
western Oklahoma and the Texas Low Rolling Plains during the
evening, a mixed mode is expected with supercell structures and
short line segments. A threat for severe wind gusts and isolated
large hail appears likely to continue through much of the evening.
An isolated and marginal severe threat could continue into the
overnight period, as the MCS moves southeastward across central and
east Texas.

...Central Plains/Mid Missouri Valley...
Westerly to west-southwesterly mid-level flow will be in place today
across much of the north-central U.S. Low-level moisture advection
will take place across much of the region. Surface dewpoints should
increase into the mid to upper 50s and lower 60s F from parts of
northeastern Colorado east-northeastward into eastern Nebraska and
southeastern South Dakota. As surface temperatures warm across this
moist airmass, isolated to scattered thunderstorms are expected to
develop. A few clusters may persist and have potential for a severe
threat during the late afternoon and early evening. RAP forecast
soundings from near North Platte eastward into northeast Nebraska
have 0-6 km shear in the 30 to 40 knot range. In addition, low-level
lapse rates are forecast to be steep. This suggests that a marginal
severe threat will be possible with the stronger storms. However,
the lack of large-scale ascent will likely keep convective coverage
more isolated, with any severe threat remaining widely spaced.

..Broyles/Barnes.. 05/30/2024

$$