Flash Flood and Flooding in Wisconsin, July 14, 2020

Area Forecast Discussion
National Weather Service La Crosse WI
231 AM CDT Tue Jul 14 2020

.SHORT TERM...(Today through Tonight)
Issued at 231 AM CDT Tue Jul 14 2020

Strong to severe thunderstorm/heavy rainfall will be the main focus
for today into tonight.

Currently watching ongoing line of thunderstorms stretching from
near the arrowhead of MN into northwest WI...ahead of a cold front
and in an axis of strong 850MB moisture transport. Question this
morning is if this convection will reach into our northwestern area
before weakening this morning. Will also have to watch for storms
ahead of an MCV rotating northeast from the Plains. Models show most
of this staying just northwest of our area or just brushing areas
north of I-94. Another concern is how strong these storms will be
given cape pool around 1500J/kg in place.

Re-firing/rejuvenation of thunderstorms expected again this
afternoon into tonight as that cold front makes a surge southeast
into the area. Challenge will be how strong/possibly severe these
storms get as it will depend if the atmosphere can recover from
possibly ongoing convection/cloud cover. Latest convective allowing
models/CAMs showing that MCV-induced thunderstorm activity pretty
much pushed out of the area by early afternoon and should allow some
recoup in cape. For rest of the afternoon, most of these CAMs then
show a broken line of thunderstorms firing along the frontal
boundary. As cape increases this afternoon, the 0-1/0-3km bulk shear
also will be on the increase -into the 20-25kt and 30-35kt range
respectively. As a matter of fact, CAMs and high resolution ensemble
forecast (HREF) showing a slight risk of significant to strong
tornado potential north of I-94 this afternoon in this better shear.
The rest of the area looks like it will see mainly a damaging
wind/large hail threat. In addition, due to the relatively slow
movement of the cold front and high precipitable water values around
2 inches, we'll have to keep an eye on torrential downpours/heavy
rainfall with these storms. Will be keeping a close eye on how
things evolve today into this evening.

There will still be a chance of showers/thunderstorms overnight as
that frontal boundary slides southeast and another mid-level trough
rotate northeast along it. Otherwise, look for highs today in the
upper 70s/low 80s where that ongoing convection will be today over
the northwest, to the mid 80s elsewhere along with fairly
uncomfortable dewpoints in the mid 60s to near 70.

.LONG TERM...(Wednesday through Monday)
Issued at 231 AM CDT Tue Jul 14 2020

Aforementioned mid-level wave running northeast along stalled
frontal boundary will keep storm chances going across mainly central
WI into northeast IA. Will also have to keep an eye on this activity
as the NAM indicating around 1500J/kg of cape and decent 0-3km shear
in the 20-30kt range.

High pressure dries things out going into Thursday into Thursday
night. This appears to be short-lived though as high-zonal flow sets
up across the northern CONUS Friday through Monday. This will bring
several impulses and shower/storm chances across the region.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 1017 PM CDT Mon Jul 13 2020

Main forecast concern is with SHRA/TSRA chances.

Overall, a relatively low confidence forecast over the next 24
hours, especially with respect to precip. At least scattered
SHRA/TSRA may develop in the predawn hours ahead of a cold front.
Some guidance brings additional storms in from across the plains
into the area during the morning hours on Tuesday, while
additional storms could form along the cold front passing through
during the afternoon/early evening hours, but this evolution will
depend on how much heating/destabilization can occur behind any
morning storms. Southerly winds, gusty at times, will become
northerly behind the front by Tuesday evening. MVFR/IFR conditions
may occur in/around any storms along with potential for locally
strong wind gusts. Timing of convection will need to be refined as
confidence increases.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...JM

Hazardous Weather Outlook
National Weather Service La Crosse WI
355 AM CDT Tue Jul 14 2020

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-151000-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-
Taylor-Clark-Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-
Adams-Vernon-Crawford-Richland-Grant-
355 AM CDT Tue Jul 14 2020

This Hazardous Weather Outlook is for portions of southeast
Minnesota...northeast Iowa and southwest into central Wisconsin.

.DAY ONE...Today and Tonight

Severe storms are possible, mostly during the afternoon and
evening hours. Strong winds, hail and locally heavy rain are the
main threats. Isolated tornadoes are also possible.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

There are additional storms chances through the weekend. It is
too early to discern if there would be a severe risk.

.SPOTTER INFORMATION STATEMENT...

A few spotter groups may be needed today into this evening.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Rieck