583
AWUS01 KWNH 220046
FFGMPD
MIZ000-WIZ000-MNZ000-220500-

Mesoscale Precipitation Discussion 0300
NWS Weather Prediction Center College Park MD
846 PM EDT Tue May 21 2024

Areas affected...far eastern MN into WI and the U.P. of MI

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

Valid 220044Z - 220500Z

SUMMARY...Despite an overall progressive nature for many
locations, Heavy rain with embedded areas of training may produce
localized 2-3 inch rainfall totals across portions of the Upper
Midwest tonight. Localized to scattered areas of flash flooding
may result through 05Z.

DISCUSSION...GOES East water vapor imagery at 00Z showed a well
defined, negatively titled shortwave trough over northern IA,
tracking toward the northeast. Radar imagery and surface
observations showed a commahead region of mostly stratiform
rainfall but with embedded convection, producing hourly rainfall
of 0.5 to 1 inch to the southeast of St. Cloud and St. Paul
through 0030Z, located within a deformation axis to the N and NW
of a vorticity max over IA. Weak elevated instability up to 500
J/kg was seen on the 00Z SPC mesoanalysis over eastern MN into
northwestern WI. Farther south and east, a line of severe
thunderstorms was tracking through west-central WI with a
secondary line over south-central WI.

Convective activity over WI is expected to continue in a mostly
progressive manner off toward the northeast with mean storm
movement of 40-50 kt toward the northeast within MLCAPE of
1000-2000 J/kg. However, the orientation of heavy rainfall echoes
will support short term training at times with 1-2 in/hr rainfall
rates. The majority of this activity should clear WI by about 04Z.
Back to the west, a pivoting axis of deformation will allow slower
movement of embedded moderate to heavy rain from far eastern MN
into northwestern WI and western portions of the U.P. of MI. Here,
localized 2-3 inch totals with rainfall rates possibly exceeding 1
in/hr on a localized basis at times within weak instability but a
strong dynamically forced regime ahead of the upper trough will be
favored. Anomalous moisture will help to support heavy rain with
the 00Z sounding from GRB indicating an anomalous precipitable
water value of 1.53 inches, near the climatological max for mid to
late May according to the SPC sounding climatology.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ARX...DLH...GRB...MKX...MPX...MQT...

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

LAT...LON   47718843 47468731 46578652 45658671 44108768
            43038857 42858962 43219045 43999102 44529217
            44599310 44829361 45469369 46519316 47389171
            47698980