Mesoscale Discussion 1480
NWS Storm Prediction Center Norman OK
1128 PM CDT Thu Aug 13 2020
Areas affected...Southeast Montana/northwest South Dakota/southern
North Dakota
Concerning...Severe potential...Watch possible
Valid 140428Z - 140630Z
Probability of Watch Issuance...60 percent
SUMMARY...The potential for severe thunderstorms capable of
hail/wind is expected to increase late this evening into the
overnight from southeast Montana into northwest South Dakota and
southern North Dakota. A Severe Thunderstorm Watch may be needed for
at least parts of the region.
DISCUSSION...A mid/upper-level trough will continue to amplify and
spread eastward over the northern High Plains late tonight,
accompanied by a strengthening deep-layer wind field highlighted by
50+ knot west-southwesterly mid-level winds. Storms have already
begun to increase across southeast Montana with aid of appreciable
forcing for ascent related to the advancing trough. While moisture
is limited within the post-frontal environment across southeast
Montana and the far western Dakotas, it is expected that storms will
gradually intensify and organize as they encounter somewhat richer
moisture and a moderate reservoir of instability with eastward
extent across southern North Dakota/northern South Dakota.
Isolated severe hail is the most probable risk initially, although
steep lapse rates/semi-dry sub-cloud layers should be conducive to
cold pool development and an increase in severe-caliber wind gust
potential with linear segments/bows overnight, particularly across
southern North Dakota. Developmental trends are being monitored for
a possible Severe Thunderstorm Watch.
..Guyer.. 08/14/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ABR...BIS...UNR...BYZ...
LAT...LON 46470514 46750290 47280033 46339981 45860090 45520511
46470514
Read morefrom SPC Forecast Products http://www.spc.noaa.gov/products/md/md1480.html
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