Mesoscale Precipitation Discussion 0871
NWS Weather Prediction Center College Park MD
622 PM EDT Thu Sep 20 2018

Areas affected...Southern MN into West Central WI

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

Valid 202221Z - 210251Z

SUMMARY...A line of thunderstorms producing 1-2"/hr rates will
track across portions of southern Minnesota into west-central
Wisconsin over an area of low FFG which may lead to flash
flooding, particularly in urban centers.

DISCUSSION...A warm front was analyzed generally along the
Iowa/Minnesota border drifting northward while a deepening surface
low tracked into southwest Minnesota. MUCAPE values of 1000 to
2000 J/kg were across southern Minnesota in line with an area of
strong 850mb moisture transport. Recent radar imagery from FSD and
MPX showed pockets of 1 to 2 inch per hour rates developing in an
increasingly organized line of convection. This is all moving
across an area of low FFG values due to repeated rounds of heavy
rainfall.

Latest runs of the HRRR and other CAMs suggest this convection
will track across south-central MN into west-central WI over the
next several hours, likely across the Minneapolis-St. Paul metro
area which picked up from 1 to locally 2 inches earlier this
afternoon. An additional 1 to 2 inches with locally higher amounts
appears possible through early this evening. As such, flash
flooding is possible due to the intense rainfall rates and
additional totals of 1-3 inches.

Taylor

ATTN...WFO...ARX...DLH...GRB...MPX...

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

LAT...LON   46269163 46179074 45578978 45268994 44829098
            44449244 44059375 44049435 44249475 44529521
            44839520 45149476 45289443 45439419 45709344
            45979263