Mesoscale Precipitation Discussion 0602
NWS Weather Prediction Center College Park MD
400 AM EDT Mon Aug 06 2018

Areas affected...Central & Eastern IA...Ext Southwest WI...Ext
Northwest IL

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

Valid 060800Z - 061200Z

SUMMARY...General weakening expected but ongoing convection will
train through areas saturated throughout the day with additional
1-2", maintaining flash flooding concerns into early morning
hours.

DISCUSSION...Deep moisture remains available north along the 8H
frontal boundary but instability is starting to exhaust as
condensation reduces the lapse rates along the low level shear
axis.  RAP analysis depicts MUCAPES falling below 1000 J/kg. 
Currently, the LLJ's angle of incidence to the boundary is about
30-40 degrees (per DMX/DVN VWP) supporting sufficient moisture
convergence to maintain/develop weaker narrower updrafts from
central IA toward northeast and the WI/IL border.  The slow
veering is already noted but will further flatten to the boundary
around 10-11z, limiting convergence to isolated wave
features/storm scale flanking lines after the 10z period.

Still, the ongoing rain showers continue to be favorably oriented
to the track of observed rainfall earlier today from
Pocahontas/Calhoun county, IA to SW Layfette/Jo Daviess counties
in SW WI/NW IL where totals exceeded 1.5", with spots near Ft.
Dodge, IA over 4" and from ALO to DBQ  2.5-3".  An additional 1-2"
are possible given upstream cells (1-1.5"/hr rain rates per
DMX/DVN) will track through these same areas.  As such
inundation/slower rise flooding is likely with some locations to
possibly experience some isolated flash flooding.  Though the
threat will significantly reduce after 11z and not extend into
South Cent WI/N Cent IL given drier soils.

Gallina

ATTN...WFO...ARX...DMX...DVN...MKX...

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

LAT...LON   43009236 42979081 42959048 42679002 42119012
            42029111 42049192 42089435 42829429