586
ACUS01 KWNS 280602
SWODY1
SPC AC 280600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Apr 28 2024

Valid 281200Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PART OF
EAST TEXAS...NORTHWEST LOUISIANA...FAR EASTERN
OKLAHOMA...WESTERN-CENTRAL ARKANSAS AND SOUTHWEST TO SOUTH-CENTRAL
MISSOURI...

...SUMMARY...
Severe thunderstorms are likely today from parts of east Texas and
northwest Louisiana north-northeastward into southwest Missouri.
Damaging winds and a few tornadoes are expected along the stronger
parts of the line. A couple of strong tornadoes could occur from
southwest Arkansas into east Texas. A more isolated severe threat is
expected today over parts of the lower to mid Missouri Valley.

...East Texas/Ark-La-Tex/Ozarks...
A large linear MCS will move eastward across the Ozarks and
Ark-La-Tex early in the period. The line is expected to become
unorganized after daybreak and dissipate by late morning. A moist
and unstable airmass is likely to remain mostly undisturbed across
much of east Texas and Louisiana. This airmass is forecast to advect
northward across the Ark-La-Tex during the afternoon. On the
large-scale, a negatively tilted mid-level trough will move across
the southern and central Plains today. As surface temperatures warm,
thunderstorms will reform along the western edge of the warm sector
by mid-afternoon. The convection is expected to organize into a
line, producing wind damage and hail, moving eastward across the
Ark-La-Tex and Ozarks during the late afternoon. The greatest severe
threat will likely be along the southern half of the line, from
southwest Arkansas and far southeast Oklahoma south-southwestward
into east Texas.

RAP forecast soundings at 00Z/Monday across far southwest Arkansas
and in northeast Texas have MLCAPE ranging from 1500 to 3000 J/kg,
with 0-6 km shear generally from 35 to 45 knots. Also, 0-3 km
storm-relative helicity is forecast to increase into the 200 to 300
m2/s2 range during the late afternoon and early evening, as a 50 to
60 knot low-level jet strengthens. This environment will be
favorable for tornadoes with embedded supercells, and with rotating
elements near the leading edge of the line. A couple of strong
tornadoes will be possible, mainly in the Ark-La-Tex and in east
Texas, where instability is expected to be greatest. Hailstones
greater than two inches in diameter could occur near the southern
end of the line, if a couple supercells can remain semi-discrete.
The more intense bowing segments will likely be accompanied by wind
damage. Although a substantial severe threat is expected as far
south as southeast Texas, there could be a gap in the line across
part of east Texas where the severe threat is locally minimized. On
the northern end of the line in the Ozarks, the magnitude of the
severe threat will be conditional upon destabilization in the wake
of the morning MCS. The severe threat associated with the line
should persist into the late evening as the new MCS approaches the
Mississippi River.

...Lower to Mid Missouri Valley/Mid to Upper Mississippi Valley...
An upper-level trough will move eastward across the lower to mid
Missouri Valley today. Ahead of the trough, a moist airmass will be
in place across much of Missouri northward into southern Iowa. As
surface heating takes place today, thunderstorms are forecast to
develop along the western edge of the moist sector from east-central
Kansas into southeast Nebraska. The storms will move eastward into
Missouri and southern Iowa during the afternoon. RAP forecast
soundings near Kansas City by 21Z have MLCAPE near 1200 J/kg, with
0-6 km shear around 60 knots. This, combined with steep low to
mid-level lapse rates should support a severe threat during the
afternoon. The primary hazards should be wind damage and hail. As
convective coverage increases during the late afternoon and early
evening, a line is expected to organize. Wind damage should become
the primary threat as it approaches the Mississippi River during the
evening.

..Broyles/Thornton.. 04/28/2024

$$