####018004726####
ACUS48 KWNS 030901

SWOD48

SPC AC 030900



Day 4-8 Convective Outlook  

NWS Storm Prediction Center Norman OK

0400 AM CDT Fri May 03 2024



Valid 061200Z - 111200Z



...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/MON...



...DISCUSSION...

A multi-day period of organized severe thunderstorm potential

appears likely across parts of the central to eastern CONUS next

week, beginning on Day 4/Monday across the Plains, and continuing

through at least Day 6/Wednesday.



...Day 4/Monday...

A negatively tilted upper trough will eject northeastward over the

northern/central Plains on Monday. Pronounced low-level mass

response will encourage rich low-level moisture to advect northward

over the southern/central Plains, as a surface low rapidly deepens

over the northern High Plains. Strong deep-layer shear and at least

moderate instability are expected to be in place ahead of a surface

dryline extending across the southern/central Plains.



Thunderstorms will likely erupt along the length of the dryline by

late Monday afternoon from southern NE into central KS and

north-central OK. Supercells are likely to be the dominant mode

initially given the strength of the deep-layer shear. Both very

large hail and tornadoes will be possible with these supercells as

they spread eastward across the southern/central Plains through

Monday evening. With a southerly low-level jet forecast to

strengthen to at least 50-60 kt Saturday evening, a corresponding

rapid increase in low-level shear will likely support a continued

threat for tornadoes with any discrete convection. Some of these

tornadoes could be strong. The severe threat will likely continue

Monday night with eastward extent across the Plains, before

convection possibly weakens some towards early Tuesday morning.

Given increased confidence in high-end severe potential, a 30%

severe area has been introduced from parts of southern NE into

central KS and north-central OK.



...Day 5/Tuesday...

The large-scale upper trough/low is forecast to gradually occlude

over the northern Plains on Tuesday. But, an enhanced mid-level jet

and embedded vorticity maximum will likely overspread parts of the

Upper Midwest, mid MS Valley, and OH Valley through Tuesday evening.

An expansive warm sector will likely be in place across these

regions ahead of a surface cold front/dryline. Robust convection

should develop along/ahead of these boundaries through the day.

Sufficient instability and deep-layer shear will likely exist to

support organized severe thunderstorms, including supercells posing

a threat for all severe hazards. The northeastward extent of the

warm sector remains somewhat uncertain into the OH Valley. Still,

some severe risk will probably persist into Tuesday evening/night

with eastward extent across the mid MS Valley and lower OH

Valley/Midwest. Expansion of the 15% severe area may be needed in

later outlooks, pending better model agreement and increased

confidence in the eastward extent of rich low-level moisture and

related instability.



...Day 6/Wednesday...

The upper trough/low should gradually evolve eastward across the

northern Plains on Wednesday. While there are still some differences

in model guidance regarding the evolution of an embedded shortwave

trough, there appears to be enough agreement in the synoptic pattern

to include a 15% severe delineation for Wednesday for parts of the

southern Plains into the ArkLaTex/Ozarks and towards the mid MS

Valley. Across these areas, strong instability is forecast to

develop east of a front/dryline. With enhanced mid-level flow

persisting with a westerly mid/upper-level jet, organized severe

thunderstorms should once again develop Wednesday afternoon.

Supercells posing a threat for all severe hazards may occur. The

northern/eastern extent of the severe threat is unclear, as the

convection from Tuesday may tend to limit better low-level moisture

return into the OH/TN Valleys. Depending on model trends over the

next few days, the 15% severe area may need to be expanded to

include these regions.



...Day 7/Thursday and Day 8/Friday...

Some severe threat may continue on Thursday from parts of TX into

the lower MS Valley/Southeast, generally along/south of a front and

any convection that develops Wednesday. Too much uncertainty

currently exists to include a 15% severe area at this time, but

trends will be monitored. A severe risk also appears possible next

Friday across the same general regions, but confidence in the

placement of the front and convection is even lower than Thursday.



..Gleason.. 05/03/2024