Mesoscale Precipitation Discussion 0721
NWS Weather Prediction Center College Park MD
1030 PM EDT Sun Aug 26 2018

Areas affected...Southern Wisconsin

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

Valid 270228Z - 270828Z

Summary...Heavy thunderstorms will continue to develop over
southern Wisconsin during the overnight hours.

Discussion...Regional radars showed scattered thunderstorms moving
northeast across southern Wisconsin and interacting with a remnant
boundary/cold pool from the earlier thunderstorm complex that has
pushed east across Lake Michigan. So far these scattered
thunderstorms have had rain rates of 1.0 to 1.5 in/hr. However,
potential for heavier activity is likely given high moisture
instability and the low level southeasterly flow into the front.

Upstream of this front, the 00Z KDVN RAOB had a precipitable water
value of 1.9 in and GPS data suggest some 2 in precipitable water
in eastern IA. RAP analysis suggests 3000 J/KG is present south of
the front. Recent HRRR runs (including 01Z) depict thunderstorms
persisting over southern Wisconsin through 09Z. One hour flash
flood guidance is around 1.5 in/hr with local areas less from
recent isolated heavy rain totals.

Strong deep layer southwesterly flow has kept ongoing activity
progressive, so the main threat is from repeating cells. As
coverage may not increase past scattered, the flash flood threat
is possible.

Jackson

ATTN...WFO...ARX...DVN...GRB...LOT...MKX...

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

LAT...LON   44059054 43968801 43318768 42398767 42388881
            42399057 42489112 43819141