AWUS01 KWNH 311148
FFGMPD
WIZ000-ILZ000-MNZ000-IAZ000-311745-

Mesoscale Precipitation Discussion 0903
NWS Weather Prediction Center College Park MD
747 AM EDT Fri Jul 31 2026

Areas affected...Portions of the Upper Midwest

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

Valid 311147Z - 311745Z

SUMMARY...Concerns for isolated and mainly urban flash flooding
will exist across portions of the Upper Midwest going through midday.

DISCUSSION...The early morning GOES-E IR satellite imagery shows a
well-defined mid-level trough and associated closed 700/500mb low
center across the Upper Midwest which is driving a regional area
of heavy showers and thunderstorms. Much of the current activity
is situated out ahead of a surface low and is elevated in nature
across central and especially southern MN, along with an axis down
across northeast IA.

Focused warm air advection into the region and coupling with the
right-entrance region of the upper-level jet is providing focused
corridors of deep layer ascent. This coupled with modest
instability (MUCAPE values ~500 J/kg), but rather strong low-level
moisture convergence, has been the key driver of the morning
convective footprint across the region.

An axis of 2.0 to 2.25 inch PWs are noted across south-central MN
through central IA just ahead of the approaching cold front, and
this moisture coupled with the aforementioned forcing is helping
to yield rainfall rates as high as 1.5 inches/hour with the
stronger convective cores. The relatively lackluster instability
is actually helping to mitigate the rainfall rate potential a bit,
but the current activity is also rather slow-moving. Therefore,
this is allowing for concerns for locally heavy rainfall totals to
materialize.

The latest multi-model hires CAMs and global model guidance show
some additional amplification of the mid-level trough, and with
the rather strong dynamical forcing, the overall convective
footprint is likely to persist despite the relative lack of instability.

Slow cell-motions will encourage persistence of locally heavy
rainfall rates that may allow for an additional 2 to 4 inches
going through midday. While generally south-central MN down
through northeast IA should see the heaviest rains, some of these
rains may edge into western WI and northwest IL toward midday.
This rainfall is expected to support concerns for isolated and
mainly urban flash flooding.

Orrison

ATTN...WFO...ARX...DMX...DVN...FSD...MKX...MPX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   45419426 45159272 44319119 43409027 42608984 
            41918974 41538981 41329016 41319108 42039204 
            43009321 43549475 43969589 44589633 45229572 
            
$$
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