Mesoscale Precipitation Discussion 0546
NWS Weather Prediction Center College Park MD
1202 AM EDT Sun Jun 29 2025

Areas affected...eastern South Dakota, southern/central Minnesota

Concerning...Heavy rainfall...Flash flooding likely

Valid 290339Z - 290800Z

Summary...Intense thunderstorms have taken on a favorable
orientation for training, with spots of 2-3 inch/hr rates
persisting for a couple hours just southeast of Watertown, SD. 
Heavy to extreme rain rates could pose locally significant flash
flood potential through at least 07Z.

Discussion...Recent mesoscale trends indicate a linear MCS
extending from just southwest of Watertown, SD to near Willmar,
MN.  The linear MCS was backbuilding along the northern extent of
a 25-30 kt southwesterly 850mb jet centered near Sioux Falls, SD. 
Substantial training was also occurring with this activity, and
MRMS estimates of 5-7 inches of rainfall exist just southeast of
Watertown recently.  Steep lapse rates and abundant moisture will
continue to fuel backbuilding in the short term, and heavy to
extreme rain rates will likely accompany the storms.

While the evolution of this band through the night is a bit
uncertain, observations suggest that training convection will
continue for at least the next 3-4 hours at least with
synoptic-scale atmospheric features not expected to evolve much in
that timeframe.  The ongoing band will likely continue to
backbuild while either remaining stationary or moving slowly
southeastward in response to local cold pool development and other
mesoscale processes.  The band may also build eastward in to more
of southern Minnesota.  The degree of training in any one spot
will be a primary factor modulating rainfall totals through 07Z. 
Additional 3-7 inch rainfall totals cannot be ruled out.  Locally
significant flash flooding may occur with this activity.

Cook

ATTN...WFO...ABR...ARX...FSD...MPX...

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

LAT...LON   45269446 45109341 44569281 43969300 43639568
            43859793 44659807 45099677