Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Tue Apr 28 2026
Valid 281200Z - 291200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
NORTHERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY...
...SUMMARY...
Multiple rounds of strong to severe thunderstorms are likely across
parts Texas into the lower Mississippi and Tennessee Valleys this
afternoon and evening. Very large hail, swaths of damaging wind, and
a few tornadoes are possible.
...Synopsis...
A series of mid-level troughs, embedded within a broader
low-amplitude mid-level flow regime, will traverse the central U.S.
today. A surface low and associated cold front will continue to
progress across the OH Valley toward the East Coast during the day.
However, the approach of another mid-level trough over the Ozark
Valley region will encourage either a weak surface low or surface
trough to develop over central TX. This will stall the southward
progression of the surface cold front given appreciable low-level
warm-air/moisture advection. Seasonally cold air aloft and
accompanying upper support from multiple embedded mid-level
perturbations will overspread the warm-air advection regime,
supporting several rounds of thunderstorms. Given strong vertical
wind shear over the warm sector, severe storms are likely,
especially over portions of the southern Plains toward the TN
Valley.
...Portions of northern TX into the TN Valley...
A complex severe weather scenario is expected across TX into the TN
Valley through the period, with multiple rounds of severe
thunderstorms likely. The first round of storms is currently
initiating over western TX, and may increase in coverage between
12-18Z across central OK into northern TX as a lead mid-level
impulse traverses a WAA regime. 7-8 C/km mid-level lapse rates amid
50+ kts of effective bulk shear will support elevated multicells
capable of producing severe hail. These storms will progress across
the MS Valley through the day. Some guidance indicates that these
storms may evolve into an MCS by afternoon, accompanied by a
damaging gust threat over the Gulf coast states.
Regardless of the evolution of earlier storms, guidance consensus
depicts adequate clearing behind this initial wave over TX into the
Ozark Valley region. Strong surface heating will encourage surface
temperatures to reach 90 F in some locales, amid 70+ F surface
dewpoints. Given 8-9 C/km mid-level lapse rates, MLCAPE should reach
the 2500-4000 J/kg range by mid to late afternoon. By this time, the
primary mid-level trough will overspread the southern Plains,
promoting enough deep-layer ascent for another round of storms to
initiate. Given 50 kts of effective bulk shear and initially
straight hodographs, supercells are expected, accompanied by a
severe hail threat. The most intense supercells may develop over
northern TX and progress eastward, and will be capable of producing
severe hail as large as 3-4 inches in diameter. Given a lingering
low-level jet (supporting elongated hodographs with some low-level
curvature) over the Sabine River Valley, a few dominant/right-moving
supercells may produce a few tornadoes, though the tornado threat
will be conditional on adequate boundary-layer
mixing/destabilization. Later in the afternoon/early evening, severe
hail/isolated tornado producing supercells may merge into an MCS,
accompanied by a severe wind threat across the Lower MS Valley.
...Portions of central into southern TX...
Forcing for ascent will be weak across portions of central into
southwestern TX. Nonetheless, 8-9 C/km mid-level lapse rates will
overspread a well-mixed boundary layer. Tropospheric speed shear
exceeding 40 kts will yield elongated hodographs, so any storm that
can initiate, mature, and sustain itself should be supercellular in
nature, accompanied by a severe hail threat. Any instance of hail
with these storms may include stones exceeding 2 inches in diameter.
Since a second, low-amplitude mid-level impulse will overspread
western and central TX toward the end of the period, isolated
supercell initiation will be possible across portions of central
into southwestern TX late this afternoon into early (12Z) Wednesday
morning.
..Squitieri/Moore.. 04/28/2026
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