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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