Mesoscale Discussion 1764

Issued

Sep 16, 2021, 8:53 PM CDT (01:53 UTC)

Expired

Sep 16, 2021, 11:00 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Tornado watch 504

The Minneapolis radar (KMPX), 94 km from the middle of the area, began a volume at 01:55 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

601 
ACUS11 KWNS 170153
SWOMCD
SPC MCD 170153 
MNZ000-WIZ000-170400-

Mesoscale Discussion 1764
NWS Storm Prediction Center Norman OK
0853 PM CDT Thu Sep 16 2021

Areas affected...Southern and Eastern Minnesota...Far Northwest
Wisconsin

Concerning...Tornado Watch 504...

Valid 170153Z - 170400Z

The severe weather threat for Tornado Watch 504 continues.

SUMMARY...An isolated severe threat will likely continue for a few
more hours across WW 504 and WW 505. Although large hail and wind
damage will be the most probable threats, a tornado still cannot be
ruled out in parts of eastern and northeastern Minnesota. A new
weather watch is not anticipated to the east of the ongoing watches.

DISCUSSION...The latest radar imagery from Minneapolis shows a
north-to-south oriented cluster of strong to severe storms in
northeast Minnesota. More widely spaced convection is located across
south-central Minnesota. The storms are located along the eastern
edge of a corridor of moderate instability along which the RAP is
estimating MLCAPE in the 1500 to 2000 J/Kg range. In addition, the
WSR-88D VWP at Minneapolis has directional shear in the lowest 2 km
with 50 to 60 kt of west-southwest flow in the mid-levels. This will
continue to support supercell potential this evening. Supercells
will be capable of producing isolated large hail and wind damage. A
tornado threat will continue across parts of eastern and
northeastern Minnesota where low-level shear is more favorable. The
storms will continue to move east-northeastward over the next few
hours, encountering more stable air to the east of the ongoing
watches. For this reason, any severe threat should become marginal
late this evening.

..Broyles.. 09/17/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DLH...MPX...FSD...

LAT...LON   48349119 47589216 46069377 44909492 44359543 43999560
            43659535 43639498 43709451 44059363 45559235 47319073
            48029037 48349119

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.