522
AWUS01 KWNH 220723
FFGMPD
WIZ000-MNZ000-IAZ000-221300-

Mesoscale Precipitation Discussion 0487
NWS Weather Prediction Center College Park MD
323 AM EDT Sat Jun 22 2024

Areas affected...North-central & Northeast IA...Central & Southern
WI...Far Southeast MN...

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

Valid 220730Z - 221300Z

SUMMARY...Broad area of moderate rainfall with embedded stronger
cells will start to align more favorably for southwest to
northeast training through early morning.  Spots of 2-3" may
result in possible scattered incidents of flash flooding.

DISCUSSION...07z surface analysis depicts a surface low across
north-central IA with a warm front that is starting to bow
northeasterly across northeastern IA into far SW WI before
dropping south across northeast IL. Persistent southerly flow
within the warm sector has been starting to veer slowly and is
likely to continue over the next few hours becoming southwesterly
at 850mb. This should reduce eastward propagation of the remaining
stronger thunderstorms across and smaller overshooting tops seen
downshear of the surface wave.  This will shift focus toward more
elevated thunderstorm activity on strengthening WAA/isentropic
ascent; though some speed convergence upstream along should
maintain some active convective embedded cores capable of 1.5"/hr;
though broader shield precip will likely remain above .5"/hr; so
totals will slowly reach 2-3" with more intense cores potentially
triggering localized flashy/rapid rise flooding through the
morning...with highest probability of totals across northeast IA,
far southeast MN, into southwest WI.

Larger scale synoptic forcing with approach of the shortwave will
focus the low level 850-700mb cyclone slowly eastward perhaps
pivoting in proximity to Minneapolis-St.Paul or toward Eau Claire,
WI.  This will allow for increased speed convergence at 850-700mb
across western to east-central WI through mid-morning with
potential showers/thunderstorms slowing/merging across the
elevated warm front in this region. Cells along this elevated
boundary may slow with some discrete  cell rotation relative to
the boundary allowing for increased duration and spots of 1.5"/hr
rates.  However, there remains some uncertainty to the LFC axis;
if activation of the LFC by steeper isentropes and moisture
convergence further south the axis may be across Baraboo to Fond
du Lac (and so the eastern portion of the MPD is expanded to
account for such uncertainty.

Gallina

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

ATTN...WFO...ARX...DMX...GRB...MKX...MPX...

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

LAT...LON   45079123 44969012 44758920 44248799 43918745
            43198745 42708834 42969012 42669207 42319290
            41879435 42069493 42599481 43529292 44189224
            44879181