MD 2082 CONCERNING SEVERE THUNDERSTORM WATCH 667… FOR CENTRAL AND EASTERN ND…NORTHWEST MN
Mesoscale Discussion 2082
NWS Storm Prediction Center Norman OK
0917 PM CDT Mon Sep 04 2023
Areas affected…central and eastern ND…northwest MN
Concerning…Severe Thunderstorm Watch 667…
Valid 050217Z – 050415Z
The severe weather threat for Severe Thunderstorm Watch 667
continues.
SUMMARY…Numerous severe gusts associated with a bow echo will
likely continue to the northeast of Severe Thunderstorm Watch #667.
A new downstream severe thunderstorm watch will be needed by 10pm
CDT (03 UTC). Peak gusts 65-80 mph are forecast.
DISCUSSION…A compact but intense bow echo continues moving
northeast along and immediately to the northwest of a surface trough
oriented from southwest to northeast. Surface conditions ahead of
the bow echo are warm with temperatures in the mid-upper 70s and
dewpoints are mostly in the low to mid 60s. A RAWS site in Sioux
Co., ND sampled a peak gust of 88 mph around 0050 UTC with the bow
echo.
KBIS (Bismarck) 88D VAD shows a strong Rear Inflow Jet with the bow
echo with 60-kt flow less than 1km AGL. Despite some boundary layer
cooling through the remainder of the evening, steep 850-500 mb lapse
rates (7.1 deg C/km per the Bismarck 00 UTC raob), strengthening QG
forcing for ascent via the approach of a mid-level shortwave trough
and strengthening LLJ into southeast ND, the dynamic character of
the bow echo will combine to be favorable for a continuation of a
risk for severe gusts into the late evening. The peak gust
magnitude will probably be weaker than in southern ND but 65-80 mph
are forecast with the more intense downbursts.
..Smith.. 09/05/2023
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…FGF…BIS…
LAT…LON 47450076 48989885 49469510 49059474 48619503 46109882
46129917 46269956 47450076
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