949
ACUS48 KWNS 020818
SWOD48
SPC AC 020816

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Thu May 02 2024

Valid 051200Z - 101200Z

...DISCUSSION...
A large upper trough with a strong embedded shortwave will develop
across the western CONUS on Sunday/D4, with an 80 kt 500 mb speed
max forecast over CO and NM by 12Z Monday. This trough will
progressively become negatively tilted, moving quickly across the
central and northern Plains during the day on Monday/D5. Even with
the leading wave moving northeast, height falls will persist as far
south as northern TX as a secondary speed max noses into CO/NM
through Tuesday/D6 morning.

Although model differences exist regarding the timing of the strong
lead wave, the combination of a deepening surface low, strong
large-scale ascent and moderate to strong instability will support
scattered to perhaps widespread severe storms on Monday. Low-level
moisture return will increase Sunday/D4 night as a southerly
low-level jet develops. During the day on Monday/D5, models show low
to mid 60s F dewpoints as far north as I-80 in NE/IA, with upper 60s
to lower 70s F from OK into TX.  The end result will be 2000 to
perhaps 3000 J/kg MUCAPE across the warm sector, with strengthening
shear. The strong wind fields and progressive nature of trough will
lead to an eastward expansion of steep low-level lapse rates across
most of NE, KS, and into central OK by late afternoon, aiding
surface-based storms including supercells, tornadoes, particularly
damaging winds and very large hail. If slower solutions such as the
ECMWF verify, the severe risk could last well into the evening
across eastern KS, OK, and western MO.

Given the aforementioned timing and positioning differences with the
parent trough and cold front/dryline, will maintain a broad 15% risk
area, with upgrades in later outlooks as predictability increases.

For the Tuesday/D6 through Thursday/D8 period, significant severe
weather potential is likely primarily from parts of TX, OK, and AR,
and eventually LA and MS as strengthening zonal flow will be
possible across the region. A moist and unstable air mass beneath
such a flow regime (moderate west/southwest flow with subtle
disturbances) would lead to an eastward expansion of the EML, with
not only a tornado risk but very large hail. Additional severe
outlooks are likely as these details become more predictable.

..Jewell.. 05/02/2024