606
AWUS01 KWNH 022328
FFGMPD
WIZ000-030330-

Mesoscale Precipitation Discussion 0543
NWS Weather Prediction Center College Park MD
728 PM EDT Tue Jul 02 2024

Areas affected...Southern Wisconsin...

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

Valid 022330Z - 030330Z

SUMMARY...Quick moving but relatively efficient warm advection
showers crossing saturated/low FFG soils pose possible low-end
flash flooding over the next few hours.

DISCUSSION...23z surface analysis denotes a pre-frontal surface
low along the QLCS crossing eastern IA. The larger synoptic
triple-point remains further upstream across north-central IA with
the warm front crossing northeast IA into southern WI; generally
driven northward by clearing skies and strengthening 10-15kts of
south-southeasterly flow.  Temps have rebounded into the upper
70s/lower 80s with mid to upper 60s Tds in the vicinity of the
warm front, but not much to support surface based CAPE.  Still,
there is a modest 500-1000 J/kg of MUCAPE to maintain/develop a
few elevated thunderstorms north of the pre-frontal surface wave.
These cells have some overshooting tops and cooling to -60C and
with the low level moisture flux though 850mb should be supportive
of 1.5-2"/hr rates.  Forward speed is likely to limit overall
duration, given the orientation of the southwesterly steering
there is a bit of cross-tracks for the elevated cells to support
1-1.5 hours of heavy rainfall resulting a streak or two of
1.5-2.5" totals across southern Wisconsin in the next few hours.

This would normally be of little concern, but a recently wet
period has saturated the upper soil column with broad areas of
60-65+% ratios and 200-300% of normal over the last 7-14 days per
AHPS.  As such, hourly FFG values are below 1.5" and <2"/3hrs
across much of the MPD area.  Given the rates and totals,
localized flash flooding is considered possible through the
evening hours as the line passes.

Gallina

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

ATTN...WFO...ARX...GRB...MKX...

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

LAT...LON   44538803 44268749 43378774 42838763 42518792
            42538998 42639058 43339045 43988947