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ACUS01 KWNS 061239

SWODY1

SPC AC 061237



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0737 AM CDT Sat Apr 06 2024



Valid 061300Z - 071200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHWEST

INTO SOUTHERN NEBRASKA AND CENTRAL AND EASTERN KANSAS...



...SUMMARY...

Severe storms will be possible across parts of the central Plains

this afternoon and early evening.  Severe gusts and large hail are

the primary risks with the stronger storms.



...Central Plains vicinity...

Water-vapor imagery this morning shows a powerful negative-tilt mid-

to upper-level trough over the Four Corners.  This upper disturbance

will eject east-northeastward into the central Great Plains later

this afternoon, before evolving into a deep mid-level low near the

SD/NE border Sunday morning.  An attendant 500-mb speed max will

move through the base of the trough and overspread the warm sector

of a deepening cyclone centered over the central High Plains.  A

cold front will move eastward across KS/OK through the day, with an

occluded portion of the front expected to extend northwestward from

north-central KS into western/central NE. 



Early morning surface analysis indicates the northern periphery of

50+ deg F surface dewpoints to be confined to OK/TX Red River

vicinity. Strong low-level moist advection will lead to a narrow but

adequately moist plume arcing from north TX northward through

central OK and into central KS/southwestern NE by mid afternoon. 

Model guidance continues to show surface dewpoints likely remaining

in the 40s F across most of NE, and only reach the low 50s F

into parts of central KS---thereby limiting both buoyancy (500 J/kg

or less of MLCAPE) and the overall magnitude/coverage of the severe

threat.  Despite the moisture/buoyancy limitations, very strong

large-scale ascent attendant to the ejecting upper-level trough will

aid in initial storm development by early afternoon near the

occluded front across central/western NE, with development possible

into northern/central KS by mid/late afternoon.  A few low-topped

supercells are forecast before a transition to more linear modes

this evening.  



Storms that can acquire supercell characteristics would yield the

greatest threat for isolated large hail (1.0-1.5 inch diameter). 

While the tornado threat may tend to be limited by sparse low-level

moisture, sufficient low-level shear/SRH could support at least a

brief tornado threat with any stronger sustained supercell,

especially in closer proximity to the surface low over southern NE

and far northern KS.  It appears the predominant risk will be severe

gusts in the 60-80 mph range owing to steep 0-2 km lapse rates, very

strong boundary-layer flow, and a more linear mode with time. 



While the primary severe threat is expected from southwest/central

NE into central/eastern KS, some threat could spread into eastern NE

before convection weakens by late evening.  A lower probability for

thunderstorm development seemingly exists farther south of the

mid-level speed max across eastern OK and north TX.  A few storms

will probably develop by early evening along/ahead of the

dryline/Pacific front.



..Smith/Mosier.. 04/06/2024



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