253
ACUS01 KWNS 020542
SWODY1
SPC AC 020541

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 AM CDT Sun Jun 02 2024

Valid 021200Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms are forecast across much of the
Plains region this afternoon and evening, especially across the
central Plains of Nebraska and northwest Kansas. Very large hail,
severe gusts, possibly greater than 75 mph, and a few tornadoes are
expected.

...Plains Region...

Large-scale pattern has not changed appreciably across the CONUS
with seasonally strong westerlies persisting across the northern
tier States. Modest 500mb flow also extends along the southern
international border region into south-central TX.

Early this morning, a few small MCS-type clusters are ongoing across
the southern Plains from southwest TX into northwest OK, with more
isolated activity over the central Plains. This activity will
propagate east-southeast and slowly weaken by daybreak. Early-day
convection is not expected to be particularly strong. In the absence
of meaningful height falls, it appears boundary-layer heating will
prove instrumental in convective development later this afternoon.
Latest model guidance suggests surface-3km lapse rates will approach
dry adiabatic along/west of the dryline from far West TX, north into
the western Dakotas. By 21z CINH should be very weak and
thunderstorms are expected to develop as convective temperatures are
breached. While negligible height changes are expected across the
Plains, a few weak disturbances will likely approach this boundary
around peak heating. Of particular concern is the central High
Plains. Water-vapor imagery depicts troughing across the northern
Great Basin and 30-40kt 500 mb flow should be maintained north of
I-70. Current thinking is scattered supercells should develop by
late afternoon then propagate downstream into an air mass that will
be very unstable. Forecast sounding for GLD at 01z from the NAM
exhibits MLCAPE in excess of 4000 J/kg. With strong deep-layer shear
these supercells may generate hail in excess of 2 inches. If this
activity grows upscale then severe wind gusts will become more
common. Some tornado risk exists during the initial supercell phase.


Isolated-scattered supercells are also expected to develop south
along the dryline to near the Mexican border. Forecast soundings
across the southern High Plains also exhibit substantial instability
with very steep lapse rates. Large hail may be common with this
activity.

Farther north, a notable short-wave trough is forecast to spread
across MT/northern WY into the western Dakotas by 03/00z, but
another weaker feature should spread into central ND by 18z. LLJ
should respond to these features which will allow boundary-layer
moisture to advance north into this region. Most guidance suggest
lower 60s surface dew points will return across eastern SD into
eastern ND; however, true lower 60s dew points have yet to advance
beyond I-80 some this may be a bit optimistic. Regardless,
large-scale support will encourage robust convection and scattered
severe, including supercells, should develop ahead of primary
frontal surge. Hail/wind are the main threats.

..Darrow/Lyons.. 06/02/2024

$$