000
ACUS01 KWNS 040531
SWODY1
SPC AC 040529

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1229 AM CDT Sat Jul 04 2020

Valid 041200Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are expected across the northern
Plains. Wind and hail are the primary threats.

...Northern Plains...

Weak short-wave trough, currently located over eastern MT at 0530z,
is forecast to eject northeast and flatten the northern Plains ridge
downstream over ND. Strong convection has developed in response to
this feature, and scattered thunderstorms are expected to be ongoing
at the start of the period. Remnants of this overnight convection
should progress into eastern ND by mid afternoon as surface
temperatures ahead of this activity warm through the mid 80s.
Forecast soundings are quite unstable, and uncapped at these
temperatures (except near the SD border), so there is some concern
that convection may reintensify by peak heating. If so, damaging
winds and hail can be expected as modest shear should support at
least organized multi-cellular updrafts.

Upstream, a secondary notable short-wave trough is forecast to
translate across western MT after 18z, and this feature should
encourage low-level easterly component as boundary layer warms
rapidly. Latest guidance suggests at least 1km low-level easterly
flow will maintain moisture into the higher terrain west of HLN. By
20z, parcels should reach their convective temperatures, and
thunderstorms are expected to develop, aided by the approaching
short wave. Strong deep-layer shear will support organized rotating
updrafts and scattered supercells should evolve. This activity will
progress toward the western Dakotas during the late
evening/overnight hours. Hail/wind can be expected with these
storms.

...Central/Southern High Plains...

Strong boundary-layer heating will once again contribute to
convective development over/east of the higher terrain of CO and
eastern NM. Models suggest a weak short-wave trough will translate
across this region which should contribute to potential clustering
within a few hours of initiation. If so, wind/hail threat would
necessarily be somewhat higher. Will introduce low severe probs
across this region to account for this scenario.

..Darrow/Moore.. 07/04/2020

$$