MD 1808 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PARTS OF EAST-CENTRAL MN AND NORTHWEST WI
Mesoscale Discussion 1808
NWS Storm Prediction Center Norman OK
0456 PM CDT Tue Sep 20 2022
Areas affected...Parts of east-central MN and northwest WI
Concerning...Severe potential...Watch possible
Valid 202156Z - 210030Z
Probability of Watch Issuance...40 percent
SUMMARY...The area is being monitored for increasing severe-storm
potential this afternoon into the evening. Storm coverage and
intensity remain uncertain, though a supercell or two capable of
severe gusts and large hail appear possible. Trends are being
monitored for a possible watch.
DISCUSSION...Latest visible satellite imagery shows an increasingly
agitated boundary-layer cumulus field along and ahead of a
NE-SW-oriented cold front draped across parts of north-central MN.
Ahead of the boundary, temperatures have warmed into the upper 70s
amid upper 60s dewpoints north of a weak warm front extending from
southern MN eastward into western WI. RAP forecast soundings suggest
lingering inhibition at the base of a pronounced EML over the area,
which combined with lingering status clouds has suppressed
convective initiation thus far. However, increasing low-level warm
advection accompanying a strengthening/expanding 850-mb jet could
act to erode the aforementioned inhibition in support of isolated
convective initiation along/ahead of the cold front during the next
couple hours. In fact, an isolated updraft has already been
attempting to deepen along the front in northeast MN.
If convection can initiate along the boundary, 40-50 kt of effective
shear and modest veering in the boundary layer would conditionally
support a right-moving supercell or two capable of locally severe
gusts and large hail. Given the modest forcing for ascent and
oblique to perpendicular deep-layer shear/storm motion orientation
to the boundary, a discrete or semi-discrete supercell mode will be
possible. Overall, the coverage and intensity of convection remains
uncertain, though trends will be monitored for a possible watch this
afternoon.
..Weinman/Thompson.. 09/20/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...ARX...MPX...
LAT...LON 45949487 46269427 46609360 46829266 46929198 46839109
46309076 45439086 44939104 44479209 44329388 44489471
44999514 45469515 45949487
