|D4||Thursday Aug 5 2021 - Friday Aug 6 2021
||D7||Sunday Aug 8 2021 - Monday Aug 9 2021
|D5||Friday Aug 6 2021 - Saturday Aug 7 2021
||D8||Monday Aug 9 2021 - Tuesday Aug 10 2021
|D6||Saturday Aug 7 2021 - Sunday Aug 8 2021
||(All days are valid from 12 UTC - 12 UTC)
PREDICTABILITY TOO LOW is used to indicate severe storms may be
possible based on some model scenarios.
However, the location or occurrence of severe storms are in doubt
1) large differences in the deterministic model solutions,
2) large spread in the ensemble guidance, and/or
3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of
organized severe storms appears highly unlikely during the entire
period (e.g. less than a 30% probability for a regional severe
storm area across the CONUS through the entire Day 4-8 period).
ACUS48 KWNS 010829
SPC AC 010827
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CDT Sun Aug 01 2021
Valid 041200Z - 091200Z
For the Wed/D4 to Fri/D6 period, a front will remain along the Gulf
and Mid Atlantic Coasts with an upper trough slowly moving from the
OH Valley into the Northeast. Numerous showers and storms will occur
near this boundary, though mainly offshore.
During this time frame, a shortwave trough will move east out of the
Pacific Northwest, reaching the northern Plains by Sat/D7. Low-level
moisture and instability may be sufficient for a isolated severe
storms, primarily from the eastern Dakotas into MN. Shear will not
be particularly strong with this initial wave, with midlevel winds
around 35 kt.
By Sun/D8, a stronger, progressive shortwave trough will move across
MT and into the western Dakotas, with favorable large-scale lift
from the Dakotas into MN. Instability will be stronger as well due
to a return of 70s F dewpoints. Predictability of such a wave is
inherently low at D8, but a Slight Risk could eventually be issued
in later outlooks.