Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 192012

Area Forecast Discussion
National Weather Service La Crosse WI
312 PM CDT Mon Jun 19 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 312 PM CDT Mon Jun 19 2017

Diurnally driven thunderstorms with some upper level support from
weak short-waves in northwest flow aloft will continue late this
afternoon into the early evening. With upwards of 500 J/kg of
CAPE and cold mid-level temperatures, may see a few storms
produce small hail and gusty winds, especially for areas south of
Interstate 90. Storms should dissipate soon after sunset.

A stronger Canadian short-wave will drop south across the area
tonight into Tuesday morning. This will result in another round
of showers and some isolated thunderstorms from around 09Z tonight
through the noon hour on Tuesday. For this period, increased POPs
into the low-end likely category for areas mainly north of a line
from Dodge Center, MN to Platteville, WI. Some areas could pick up
a quick quarter inch of rain.

Surface high pressure builds across the region Tuesday afternoon
in the wake of the departing wave aloft. This will allow skies to
clear with a return to dry conditions. Temperatures Tuesday will
range from the upper 60s across north central WI to the upper 70s
across portions of northeast IA.

.LONG TERM...(Tuesday night through Monday)
Issued at 312 PM CDT Mon Jun 19 2017

Much of Wednesday now looks dry as an elevated warm layer moves
over the forecast area, providing a thermal capping inversion
between 800 and 700 hPa. At the same time, southerly return flow
across much of the plains will result in an impressive instability
plume across the eastern Dakotas and NE into western MN/IA by
Wednesday afternoon. This plume folds over into a southwest-
northeast orientation Wednesday night into Thursday morning ahead
of an eastward advancing cold front. Amount of available
instability across the forecast area is still somewhat uncertain,
but with 0-3 km shear increasing to between 30 to 40 kts, a few
stronger to severe thunderstorms are possible, especially for
areas west of the MS River. This matches well with the SPC Day 3
convective outlook and bears watching over the next 24 to 48

12Z model suite then shows the aforementioned cold front stall out
in the vicinity of the IA/IL/WI border region on Thursday.
Placement of front will be critical in areas of greatest
instability and additional thunderstorm chances, but for now, it
looks like there may be additional storms Thursday and Thursday
night mainly south of I-90.

While much of Friday looks dry under the influence of high
pressure, on and off shower chances return for the weekend as a
series of ill-resolved short waves moves across the region. Could
see a few isolated thunderstorms each afternoon, but overall
available instability looks very weak.

Warmest temperatures of the week will be Wednesday/Thursday with
highs in the mid 70s to lower 80s. However, cooler values return
for the weekend with most areas struggling to top the mid 70s.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1231 PM CDT Mon Jun 19 2017

The combination of cold air and cyclonic flow aloft will produce
showers and scattered thunderstorms this afternoon. A few of these
storms may produce some small hail at times. Due to the scattered
nature of the thunderstorms just went with vicinity showers for
now and update as needed to add thunderstorms. These showers and
storms may cause visibilities and ceilings to become briefly




LONG TERM...Rogers
AVIATION...Boyne is the U.S. government's official web portal to all federal, state and local government web resources and services.