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ACUS48 KWNS 110857

SWOD48

SPC AC 110856



Day 4-8 Convective Outlook  

NWS Storm Prediction Center Norman OK

0356 AM CDT Thu Apr 11 2024



Valid 141200Z - 191200Z



...DISCUSSION...

...Significant severe weather episode possible late afternoon and

evening on Monday...

A mid/upper low over the central CA vicinity at 12Z Sunday should

evolve into an open wave as it ejects across the Southwest and into

the central Great Plains by around Tuesday morning. As it crosses

the Rockies onto the High Plains, the tropospheric flow field will

amplify with substantial lee cyclogenesis in the central High Plains

on Monday afternoon. While a moderate amount of spread persists

across respective ensemble systems, 00Z deterministic runs have

converged towards greater agreement with the aforementioned scenario

through D5, with progressively lower predictability in D6-8. 



With about 3 days of persistent low-level moisture modification from

the western Gulf beneath an extensive elevated mixed layer, the

northern extent of mid 60s surface dew points should reach into most

of OK east of the dryline by Monday afternoon. Late afternoon

thunderstorm initiation along the dryline appears probable in the

eastern TX Panhandle/western north TX to western OK vicinity, within

a kinematic and thermodynamic profile favorable for strong

supercells. Convective development will blossom both south and

especially north extent during the evening across the central and

southern Great Plains. For this outlook, have expanded the 30

percent area to highlight the greater spatial confidence in a

substantial severe weather episode.



Despite increasing predictability concerns and the impact of prior

day convection, very strong flow fields should persist into at least

the first half of D6/Tuesday as a deep surface cyclone pivots

northeast towards the Upper MS Valley vicinity. While instability

will be weaker compared to Monday, organized severe potential is

evident within an arc from a portion of the Upper MS Valley to the

Mid-South.



In the wake of this lead system, the shortwave trough digging into

the Pacific Northwest may carve out a broad, positive-tilt trough in

the West by mid-week. Consensus of guidance suggests that rich

low-level moisture over the southern Great Plains will not be

scoured by the lead wave. This may yield daily bouts of severe

thunderstorms across parts of the central and southern Great Plains

late in the period and beyond. Predictability for individual day

highlights is too low to warrant 15 percent probabilities yet.



..Grams.. 04/11/2024