SPC Jul 1, 2020 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0221 AM CDT Wed Jul 01 2020

Valid 031200Z - 041200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN INTERMOUNTAIN REGION TO THE NORTHERN PLAINS...

...SUMMARY...
A few severe storms will be possible Friday from the northern
Intermountain region to the northern Plains.

...Synopsis...
The upper pattern over the U.S. will continue to deamplify gradually
Friday, as the western and eastern U.S. troughs weaken.  As this
occurs, a belt of moderate anticylonic westerly flow will evolve
from the northern Intermountain region across the north-central U.S.
and Great Lakes, and into the Northeast.  Within this arcing belt of
westerlies, embedded perturbations move quickly through the flow
field through the period, supporting areas of enhanced thunderstorm
coverage.

At the surface, a generally weak/nondescript pattern is expected
from the synoptic-scale perspective, given the prevailing upper
ridging.  As such, more subtle, sub-synoptic-scale boundaries will
prevail through the period.

...Northern Intermountain region into the north-central states...
An MCS may be ongoing at the start of the period over the eastern
Dakotas/mid Missouri Valley region, though uncertainty prevails
regarding the specific location of this system.  While limited
severe risk could accompany this convection, or newly developing
afternoon storms near any remnant MCV/outflows, uncertainty
precludes inclusion of a risk area.

Meanwhile, a somewhat more prominent small-scale perturbation
embedded in the upper flow, emanating from the Intermountain West,
is currently expected to cross the Idaho/Montana/Wyoming vicinity
through the day, and eventually reach the northern Plains late. 
With ample destabilization expected across the northern High Plains
vicinity during the afternoon, and 30 to 40 kt mid-level flow atop
low-level southeasterlies, CAPE/shear combination will be sufficient
to support isolated severe storms.  Given ongoing uncertainty with
respect to timing these small-scale, fast-moving perturbations, will
only include a 5%/MRGL risk at this time.  Later forecasts may
require a SLGT risk upgrade, as uncertainty diminishes.

..Goss.. 07/01/2020

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from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day3otlk_0730.html