Mesoscale Discussion 1346
NWS Storm Prediction Center Norman OK
0959 AM CDT Wed Jul 19 2017
Areas affected...Portions of northern ND and northwest MN
Concerning...Severe potential...Watch unlikely
Valid 191459Z - 191730Z
Probability of Watch Issuance...20 percent
SUMMARY...Some isolated severe-hail risk may accompany convection
spreading across areas near and just south of the international
border through the day. Present indications are that Watch issuance
will be unlikely.
DISCUSSION...Regenerative convection within a corridor of modest,
though capped, boundary-layer moisture return through western ND and
into parts of southern Manitoba will continue to train
east-southeastward. This activity will affect areas near and south
of the international border through the day. Multiple, subtle foci
for large-scale ascent -- accompanying a mid-level speed maximum
crossing a corridor of elevated buoyancy accompanying the moisture
return -- will maintain the risk for thunderstorms through the day.
The 12Z Bismarck sounding indicates a layer of near 9-C/km lapse
rates in the mid levels, encouraging strong upward accelerations for
convection rooted atop the stable boundary layer.
As potentially robust updrafts, associated with marginal to moderate
elevated buoyancy, interact with 50-60 kt of effective shear --
developing eastward with time -- the most robust convective cores
could produce isolated severe hail through the day. However, with
effective inflow layers rooted above the stable surface layer, and
given lack of more appreciable moisture return somewhat limiting
buoyancy, a more substantial severe risk is not anticipated.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 47929658 48039914 48700089 48990044 48999905 48879601
48509536 48149556 47929658