SPC MD 496

MD 0496 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR NORTHERN/EASTERN NE…WESTERN IA…SOUTHEAST SD…FAR SOUTHERN MN…EXTREME NORTHEAST KS/NORTHWEST MO

Mesoscale Discussion 0496
NWS Storm Prediction Center Norman OK
0401 PM CDT Sat Apr 15 2017

Areas affected...Northern/Eastern NE...Western IA...Southeast
SD...Far Southern MN...Extreme Northeast KS/Northwest MO

Concerning...Severe potential...Watch possible 

Valid 152101Z - 152300Z

Probability of Watch Issuance...40 percent

SUMMARY...An increase in thunderstorm coverage and intensity is
expected later this afternoon. A few severe thunderstorms are
possible with a primary threat of large hail and locally damaging
wind.

DISCUSSION...At 2045Z, a plethora of surface boundaries were
observed in visible satellite imagery, surface observations, and
radar across portions of eastern NE, western IA, and southeast SD
into southwest MN. Convection has recently started to increase
across portions of northeast NE/northwest IA along a wind shift/weak
surface trough, with other attempts at initiation noted near Omaha
near another weak surface boundary. Meanwhile, cumulus is increasing
across portions of southeast NE and also from southeast SD into
extreme southern MN in the vicinity of a cold front. 

As convection continues to deepen and increase in coverage, moderate
instability and effective shear of 35-45 kts (noted in recent
mesoanalysis) will support some organized storm structures with an
initial threat of large hail. Isolated damaging wind may become more
of a threat toward evening as some consolidation of storms is
possible into portions of western/central IA. An isolated tornado
will also be possible with any discrete supercell, primarily across
portions of far southeast NE into southwest IA where a modest
increase in the low-level jet is possible late this afternoon into
the early evening. 

The coverage and magnitude of the severe threat is expected to be
somewhat marginal, but watch issuance is possible across portions of
the MCD area later this afternoon if convective trends warrant.

..Dean/Thompson.. 04/15/2017

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

ATTN...WFO...MPX...DMX...EAX...FSD...OAX...TOP...

LAT...LON   43149708 43289701 43589641 43839438 43769406 43229323
            42299324 41289357 40479411 40199475 39929519 39829601
            39799655 39889706 40329724 41019682 41339686 41599693
            41729697 41869749 42139755 42509748 42699738 42749726
            43149708 

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