793
ACUS01 KWNS 290556
SWODY1
SPC AC 290555

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Wed May 29 2024

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered strong storms posing a risk for severe hail and wind
appear likely across the northern and central High Plains late this
afternoon and evening. Isolated strong storms will also be possible
over parts of the southern Plains to lower Mississippi Valley, into
the middle Rio Grande Valley.

...Synopsis...
Early morning satellite imagery shows a pair of shortwave troughs
within the northern stream, one moving southeastward across the
Upper Midwest and another progressing eastward through the Pacific
Northwest. Full-latitude shortwave ridging exists between these two
features, extending from northern Mexico into central Saskatchewan.

Eastern shortwave trough is forecast to pivot more eastward as it
moves into the OH Valley before then continuing eastward throughout
the day through the northern Mid-Atlantic States. Thunderstorm
development is anticipated ahead of this system from the middle OH
Valley through the northern Mid-Atlantic and southern New England. A
damaging gust or two is possible with these storms, but a
predominantly multicellular mode and weak vertical shear is expected
to limit the overall severe coverage.

Farther west, the Pacific Northwest shortwave is expected to
continue eastward across the northern Rockies into the northern
Plains. As it does, lee troughing will sharpen across the northern
High Plains, with eventual cyclogenesis anticipated. The resultant
surface low is then forecast to track northeastward across eastern
MT and western ND late Wednesday night/early Thursday morning.
Thunderstorms are anticipated ahead of this shortwave and attendant
surface low as well as down the lee trough across the central and
southern High Plains.

...Northern Rockies into the Northern High Plains...
Afternoon thunderstorm development is anticipated ahead of the
approaching shortwave trough from southwest MT into
northwest/north-central WY and southeast MT. In this region, strong
boundary-layer mixing and increasing mid-level moisture will
contribute to airmass destabilization ahead of the approaching wave.
Buoyancy will be modest, but the high-based character of the storms
could still result in strong outflow capable of producing damaging
gusts.

Afternoon thunderstorm development is anticipated ahead of the
shortwave trough as well, where strong heating, moderate low-level
moisture and low-level convergence will support convective
initiation. A relatively narrow axis of destabilization is
anticipated across the western Dakotas, where a storm could become
strong enough to produce hail and/or damaging gusts. The eastern
extent of the severe threat will be limited by diminishing buoyancy
into the central Dakotas.

...Central/Southern High Plains...
Strong heating and low-level moisture advection will support airmass
destabilization across the central and southern High Plains.
Persistent low-level convergence coupled with glancing large-scale
ascent is expected to result in convective initiation by the late
afternoon/early evening. Highest coverage is expected across the
central High Plains, with weakening large-scale ascent with southern
extent likely limiting coverage. Large hail is possible with initial
development, but outflow-dominant storm structures are likely, with
damaging gusts as the primary risk.

...Central/Southeast TX into Lower MS Valley...
Thunderstorms may still be ongoing across central TX this morning,
supported by persistent warm-air advection across remnant outflow.
Given the weak large-scale ascent and potential presence of a
convectively generated vorticity maximum, the evolution of these
early morning storms is uncertain. Some guidance suggests there is
potential for an MCS to develop as the vorticity maximum moves into
the moist airmass across central TX. Other guidance shows
development along the northeast and southern periphery of the
vorticity maximum, but with little linear organization. Modest
westerly flow aloft atop southeasterly surface winds along with
moderate instability will favor hail and areas of strong gusts with
any mature convection. However, the uncertainty on convective
evolution and resulting coverage precludes upgrading probabilities
across the region with this outlook.

..Mosier/Barnes.. 05/29/2024

$$