Mesoscale Precipitation Discussion 0731
NWS Weather Prediction Center College Park MD
555 PM EDT Tue Aug 28 2018

Areas affected...NORTH AND CENTRAL MICHIGAN

Concerning...Heavy rainfall...Flash flooding possible

Valid 282155Z - 290355Z

Summary...A convective complex moving across eastern Wisconsin and
towards Lake Michigan will race eastward along a frontal boundary
into Michigan this evening. This activity has the potential to
produce 2 to 3 inches of rainfall over an area that has seen 3 to
6 inches of rainfall in the past few days. Flash flooding is
possible.

Discussion...Strong thunderstorms with very heavy rainfall have
organized ahead of a cold front in Eastern Wisconsin. This cluster
will move across Lake Michigan during the next hour and into the
L.P. this evening. The environment across Michigan is primed for
these storms to persist with latest RAP analyzed MLCape of
1500-2000 J/kg combined with PWATs already from 1.7 to 2.0 inches,
more than 2 standard deviations above normal. Although latest high
res guidance still shows some variation in placement of heaviest
rainfall, best RAP moisture transport and instability should
combine across north-central Michigan near the latitude of Saginaw
Bay. This is supported by translating current activity to the ENE
using 0-6km storm motion vectors, and by the latest ARW simulated
reflectivity. Although individual cells will likely move rapidly
from SW to NE across the state, training of storms along the
southward sinking boundary and very high rainfall rates - 1.5 to
2.0 inches in an hour - create a flash flood threat through 04Z.

Weiss/Burke

ATTN...WFO...APX...DTX...GRR...

ATTN...RFC...NCRFC...

LAT...LON   45758410 45208334 44888314 44298298 43978275
            43468255 43208285 43098373 43038521 43158658
            43998672 44758645 45298598 45298598 45358568
            45728507