|Mesoscale Discussion 1345|
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Mesoscale Discussion 1345
NWS Storm Prediction Center Norman OK
0955 AM CDT Wed Jul 19 2017
Areas affected...northeast South Dakota through southwest Minnesota
Concerning...Severe potential...Watch possible
Valid 191455Z - 191700Z
Probability of Watch Issuance...60 percent
SUMMARY...Potential exists for small cluster of storms over north
central ND to intensify and continue through northeast SD and
southwest MN with damaging wind and large hail the primary threats.
However, some uncertainty remains regarding this scenario, so ww
issuance will ultimately depend on convective trends.
DISCUSSION...Cluster of storms over north central ND is moving east
southeast at around 35-40 kt. Based on recent observations and both
model and observed 12Z RAOB data, updrafts are still elevated above
a stable layer. However, sufficient dry air exists in the lowest 3
km to support strong to severe downdrafts. The storms are developing
in response to a southwesterly 35 kt low-level jet that will migrate
eastward with time in association with a progressive shortwave
trough. These processes might help to sustain the convection until
the boundary layer destabilizes sufficiently downstream to support
surface based storms, and possibly a forward propagating MCS with
embedded bowing segments and supercells. However, storms scale model
solutions are dispersive, and some uncertainty remains whether or
not storms will be able to persist as they transition to surface
based given the warm elevated mixed layer with 12-14 C temperatures
at 700 mb.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 44449892 45169860 45639827 45259686 44649554 43749595
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