####018002542####
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