MD 2080 CONCERNING SEVERE THUNDERSTORM WATCH 666… FOR NORTHWEST AND NORTH-CENTRAL SD…SOUTHERN AND CENTRAL ND
Mesoscale Discussion 2080
NWS Storm Prediction Center Norman OK
0452 PM CDT Mon Sep 04 2023
Areas affected…northwest and north-central SD…southern and
central ND
Concerning…Severe Thunderstorm Watch 666…
Valid 042152Z – 042345Z
The severe weather threat for Severe Thunderstorm Watch 666
continues.
SUMMARY…Scattered severe gusts are probable across the northeast
part of severe thunderstorm watch #666 as a band of storms moves
northeastward. A downstream severe thunderstorm watch is expected
within the next hour in parts of northern SD and southern ND. Peak
gusts with the most intense downdrafts are forecast to range 70-90
mph through 01 UTC (8pm CDT/7pm MDT) over northern SD and southern
ND.
DISCUSSION…Radar mosaic late this afternoon shows an intensifying
band of storms over western SD. Surface analysis ahead of this
activity indicates temperatures are in the 95-100 deg F range south
of a southwest-northeast oriented surface trough. The airmass where
the ongoing storms are located in western SD is adequately moist
(mid 50s deg F dewpoints) but relatively dry compared to
south-central ND where dewpoints are in the lower 60s. As a result,
PW increases from southwest to northeast. This increase in moisture
will probably result in both storms moving in a more favorable
environment of buoyancy and moisture for evaporatively cooled
downdrafts.
It appears the most intense phase of the developing squall line will
commence over the next few hours as storms move into northern SD and
into southern ND. The negatively tilted mid-level shortwave trough
over WY will continue to pivot eastward towards the Dakotas this
evening. The combination of very steep low to mid-level lapse
rates, a linear storm mode, and appreciable large-scale forcing for
ascent will favor scattered severe gusts through the evening across
the Dakotas with the squall line. Peak gusts are forecast to range
from 70-90 mph.
..Smith.. 09/04/2023
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…FGF…ABR…BIS…UNR…
LAT…LON 44300172 44250220 44340250 45460364 45700370 45950357
47300105 47409982 47229892 46789830 46129834 45419893
44300172
Comments