Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231925
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
225 PM CDT Mon Oct 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 225 PM CDT Mon Oct 23 2017

Main impactful weather concerns are on strong northwest winds
tonight through Tuesday.  These strong winds will create driving
difficulties for lightweight and high profile vehicles.  Also,
unsecured lightweight objects may be blown around.

Strong northwest winds of 25 to 30 mph with gusts to 45 mph will
develop this evening across the open areas of southeast Minnesota
and northeast Iowa. These strong winds will then spread eastward
into western and central Wisconsin early Tuesday morning as low
pressure tracks into eastern Upper Michigan and rapidly
intensifies/deepens. A wind advisory is in effect for all of
southeast Minnesota and northeast Iowa starting at 7 PM tonight and
continuing through 6 PM Tuesday. A wind advisory will also be in
effect for all of western into central Wisconsin from 7 AM Tuesday
through 7 PM Tuesday. The strongest winds in Wisconsin will be
confined to open areas and ridge top locations. A band of light rain
showers will track east across the area late this afternoon into
this evening thanks to frontogenesis in the 900-700 mb layer. This
band of showers is expected to increase in coverage and intensify
slightly across portions of western and central Wisconsin as the low
deepens. The low then retrogrades west as a trough digs into the
Upper Mississippi River Valley. Rain showers will then gradually
spread back to the west with light to perhaps moderate rain across
much of Wisconsin and periods of showers expected across northeast
Iowa and southeast Minnesota. It will be rather chilly on Tuesday
too with highs only making it into the lower to mid 40s. Winds will
subside Tuesday evening as the low heads east into Ontario.

.LONG TERM...(Tuesday night through Monday)
Issued at 225 PM CDT Mon Oct 23 2017

After the windy day Tuesday, conditions will settle down Tuesday
night as the surface low moves off into southern Ontario. This
will allow the winds to quickly diminish and be under 10 mph from
about late evening through the overnight. Any lingering showers
late Tuesday afternoon will also quickly dissipate/move east of
the area and right now do not plan to carry any precipitation
chance into Tuesday evening.

The 23.12Z models continue to show a period of short wave ridging
building in over the Upper Midwest for Wednesday and Wednesday
night before the next system comes south out of Canada on the
northwest flow aloft. The general trend is for this short wave
trough to help form an upper level low over the Upper Midwest
Thursday and Thursday night. Some differences start to show on how
long this system will remain over the region. Heading into the
weekend, the 23.12Z GFS is forming a large cut off low over
Hudsons Bay which swings the trough out of the Upper Midwest and
into the eastern Great Lakes. The 23.12Z ECMWF is much weaker with
the system over Hudsons Bay allowing the upper level low and
troughing to remain over the Upper Midwest and Great Lakes through
much of the weekend. These differences are also seen at the
surface where the GFS would take the precipitation out of the area
late on Friday while the ECMWF holds onto some light precipitation
into Saturday night. For now, will go with the faster evolution of
the GFS but may need to adjust this with later forecasts to hold
onto the precipitation chances a bit longer. This system will also
usher in the coolest air of the season. Overnight lows will dip
into the 20s and lower 30s from Thursday night through Sunday
night with 20s for almost the entire area Friday and Saturday
nights. Daytime highs during this period will primarily be in the
40s but some spots Friday could be stuck in the 30s the entire
day. With these cool temperatures, the precipitation types will
change between rain in the day to some light snow at night. At
this point, it does not look the snow should amount to much.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1228 PM CDT Mon Oct 23 2017

Main aviation concerns are on strong northwest winds tonight
through Tuesday and MVFR stratus. Look for strong northwest winds
of 15 to 20 kts with gusts up to 35 kts to develop at KRST this
evening and continue through the overnight hours. Some gusts to
around 40 kts are expected after 13Z Tuesday. Winds will also be
strong at KLSE with sustained winds of 14 to 19kts developing
tonight with gusts approaching 30 kts on times. Wind gusts will
strengthen after sunrise on Tuesday with gusts approaching 33
kts. Stratus will overspread the TAF sites tonight with cloud
bases of 2-3 kft. The MVFR stratus deck is expected to lift to
VFR by Tuesday afternoon.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Advisory from 7 AM to 7 PM CDT Tuesday for WIZ017-029-
     032>034-041>044-053>055-061.

MN...Wind Advisory from 7 PM this evening to 6 PM CDT Tuesday for
     MNZ079-086>088-094>096.

IA...Wind Advisory from 7 PM this evening to 6 PM CDT Tuesday for
     IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...Wetenkamp
LONG TERM...04
AVIATION...Wetenkamp



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