685
ACUS01 KWNS 051956
SWODY1
SPC AC 051954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Thu Jun 05 2025

Valid 052000Z - 061200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE SOUTHERN AND CENTRAL PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHEAST...

...SUMMARY...
Scattered severe thunderstorms are expected across the southern and
central Plains into tonight. Several tornadoes (some possibly
strong), large to very large hail, and severe gusts are possible.
Severe gusts are also possible over parts of the Northeast this
afternoon.

...20z Update...
The previous forecast largely remains on track with only some
adjustments needed. The primary change was an expansion of 15%
hail/wind probabilities east of the Front Range in CO where deep
convection is beginning to develop. Recent guidance continues to
display a dry bias across eastern CO where dewpoints have increased
to the low to mid 50s. Consequently, buoyancy is considerably higher
than previously anticipated by morning model solutions, which should
increase the potential for robust/severe thunderstorms as convection
begins to develop along subtle low-level confluence axes. See MCD
#1123 for additional near-term details.

A cold pool associated with a convective cluster across western OK
casts some uncertainty regarding the evolution of the convective
environment downstream of maturing storms over southeast CO later
this afternoon/evening. However, heating to the south of the cold
pool may yield a focused boundary for convective
development/propagation later tonight amid a modest strengthening of
southerly low-level flow around/after 00 UTC. Recent HRRR/RRFS
solutions appear to capture the ongoing trends well and continue to
suggest a well-organized cluster/MCS will emerge out of southwest KS
into the recovering air mass across northwest OK later tonight. As
such, risk probabilities are maintained.

Further south across western TX, the psuedo warm front/outflow
boundary is becoming increasingly apparent in GOES visible imagery.
A few initial attempts at convective initiation are noted along this
boundary with sustained convection becoming more probable through
mid-afternoon as residual capping continues to erode (evident by
dissipating billow clouds). The expectation is that the tornado
threat will likely be maximized along this boundary through the
evening hours given enhanced low-level SRH and the potential for
long storm residence times. The 10% tornado risk area has been
adjusted to account for this potential.

Elsewhere, the forecast largely remains on track. See MCDs 1118,
1121, 1122, 1123, 1124, and 1125 for additional near-term details.

..Moore.. 06/05/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jun 05 2025/

...Southern High Plains...
Morning surface analysis depicts a convectively reinforced
quasi-stationary surface boundary extending across north-central TX
westward through the TX South Plains to southeast/east-central NM.
This boundary may have a tendency of moving slowly northward as a
warm front over the High Plains later this afternoon -- in response
to an approaching midlevel impulse and gradually deepening lee
cyclone over southeast CO. Along/immediately south of this boundary
(over the TX South Plains), deep/rich boundary-layer moisture (upper
60s/lower 70s dewpoints) is in place, with impressive moisture
sampled by the 12Z MAF sounding (15.8 g/kg mean mixing ratio).
Persistent cloud coverage will tend to shelter this moisture from
diurnally driven boundary-layer mixing through the afternoon, while
heating in cloud breaks will still yield strong surface-based
instability (upwards of 3000 J/kg MLCAPE). As a low-amplitude
impulse and related jet streak advance east-northeastward across the
central High Plains, peripheral large-scale ascent will aid in
scattered thunderstorm development across east-central/southeast NM
into the TX South Plains -- focused near the intersection of the
northward-moving warm front and lee trough. Around 50-60 kt of
effective shear and the modest large-scale ascent will favor
discrete supercells, initially posing a risk of very large hail.
However, a strengthening evening low-level jet atop the backed
low-level flow near the boundary will support enlarging clockwise
hodographs (300+ m2/s2 effective SRH). Given the deep/rich moisture
and enhanced helicity, a focused corridor for tornadoes (some
possibly strong) is evident over the TX South Plains -- where
10-percent tornado probabilities were added. Localized upscale
growth into organized clusters is expected into western North Texas
this evening, where a swath of severe wind is possible.

Father south from the TX South Plains to parts of the TX Trans-Pecos
vicinity, deep boundary-layer mixing amid lower/middle 60s dewpoints
will contribute to moderate-strong surface-based instability, with a
long (albeit straighter) hodograph away from the surface boundary.
This will also support intense discrete/semi-discrete supercells,
though the primary concern here will be very large hail (possibly 3+
inches).

...Central High Plains into the southern Plains...
In the left-exit region of a 40-50-kt midlevel jet streak impinging
on the central High Plains, thunderstorm development is expected
ahead of a gradually deepening lee cyclone over southeastern CO this
afternoon. Diurnal heating (within cloud breaks) of a moist air mass
(lower 60s dewpoints) will yield moderate surface-based instability
ahead of developing storms. Given around 50 kt of effective shear
(characterized by a long/generally straight hodograph), several
semi-discrete supercell clusters are expected. Large hail and severe
wind gusts are expected, though the rich/sheltered boundary-layer
moisture and sufficient low-level streamwise vorticity for
established right-mover cells will support a couple tornadoes as
well. With time, storms will spread east-southeastward into
northwest OK -- where upscale growth into an MCS seems increasingly
likely. This will favor an increased risk of a swath of severe wind
gusts into the overnight hours.

...Northeast...
Widely scattered thunderstorms are expected along/ahead of a cold
front draped across the region this afternoon. Visible satellite
imagery shows a moist/destabilizing air mass ahead of the front,
where moderate surface-based instability is expected. The warm/moist
air mass, combined with around 30 kt of effective shear, should
promote a few loosely organized clusters capable of producing wind
damage -- aided by the steepening boundary-layer lapse rates.

$$