287
ACUS02 KWNS 161727
SWODY2
SPC AC 161726

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Thu May 16 2024

Valid 171200Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
GULF COAST STATES...

...SUMMARY...
Scattered severe thunderstorms with a few tornadoes, very large
hail, and damaging winds are possible across parts of the Gulf Coast
States on Friday through Friday night.

...South-central to Southeast States...
A messy severe weather setup is expected on Friday into Friday night
amid a series of low-amplitude impulses ejecting within and around
the positive-tilt, southern-stream shortwave trough across the
southern Great Plains. Synoptic surface pattern appears nebulous and
likely driven on the mesoscale by several rounds of convection today
through the end of D2. Primary changes with this outlook are to
expand severe probabilities west and east, while reducing
probabilities across the northern portion of the threat area.

An MCS or clustered remnants of an early morning one should be
ongoing at 12Z Friday across parts of the central Gulf Coast region.
Outflow from this preceding D1 activity will serve as the focus for
renewed thunderstorm development later in the day. Most guidance
suggests a separate area of upstream convection may be ongoing or
will develop by midday across parts of south TX and the TX Gulf
Coast along and behind the composite outflow/cold front that will
surge southeast in TX on D1. With the fastest mid-level
southwesterlies expected to overlie the western to central Gulf
Coast during the first half of the period, supercells capable of
very large hail will be possible. This threat should be focused in a
narrow corridor along the TX Gulf Coast initially, and then develop
later in the afternoon to evening in the central Gulf Coast. Some of
this latter activity will have relatively greater potential for
tornado/wind threats, focused along the outflow in the wake of the
early-morning MCS.

Additional isolated to scattered thunderstorm development should
occur within the post-frontal/outflow air mass centered on parts of
the Red River Valley and in south-central TX near the Rio Grande.
This activity will likely be aided by the embedded low-amplitude
impulses within the southern-stream shortwave trough. Residual
buoyancy should be adequate for an isolated hail/wind threat amid
more muted deep-layer shear closer to the trough axis.

...Northern Great Plains...
A vigorous, northern-stream shortwave trough will move across the
northern Rockies into the Prairie Provinces and adjacent parts of
MT/ND through early Saturday. Primary surface cyclone will occlude
over SK/MB, with secondary cyclogenesis occurring near the SD/WY/MT
border area along the trailing Pacific cold front. With only
modified moisture return ahead of the front, MLCAPE will remain
rather weak. Initial convective development will probably occur
within the post-frontal upslope flow regime during the early to mid
afternoon. This activity should spread east and likely expand during
the late afternoon into the evening. With deeply mixed thermodynamic
profiles ahead of the front, and steep lapse rates being maintained
behind it, high-based thunderstorms with amalgamating outflows are
expected. While the bulk of strong 700-500 mb westerlies will lag
behind the front, the strengthening flow should support a threat for
strong to isolated severe surface gusts before convection wanes
after dusk.

..Grams.. 05/16/2024

$$