Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 240754
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
254 AM CDT Thu May 24 2018

.SHORT TERM...(Today through Friday night)
Issued at 255 AM CDT Thu May 24 2018

Mid/upper ridging was positioned over the Upper MS Valley early this
morning. Scattered showers and storms were percolating across
central/northern MN into northwest WI on the nose of the stronger
850 mb moisture transport. A few of these could sneak into Clark
or Taylor Counties this morning, but better chances will be to the
north.

Through the rest of the day into tonight, a shortwave trough over
eastern Montana will lift into Manitoba, with the axis of
stronger low level moisture transport and weak mid-level height
falls spreading east across the region. With limited upper support
today, expect most areas to remain dry. As 925 mb temps continue
to inch upwards, high temps should peak in the mid to upper 80s in
most areas along with increasingly breezy southerly winds,
especially west of the MS River.

With the approach of the upper troughing, expect shower/storm
chances to increase from the west tonight. Confidence in
coverage/timing isn`t very high with high res models showing a
range of possible solutions. However, it is possible that
convection developing west of the area could move into the area
during the evening, with at least some potential for additional
scattered shower/storm development as moisture transport/low-level
jet axis aims into the area through the night.

The convective scenario for Friday remains similarly muddled given
weak upper level forcing and ill-defined surface boundaries.
Moderate instability should build, with potential for at least
isolated to scattered showers/storms during the afternoon/evening.
Weak deep layer shear should inhibit storm organization, but a
few stronger storms could develop with locally heavy rain possible
given the moist environment and relatively slow storm motions.

.LONG TERM...(Saturday through Wednesday)
Issued at 255 AM CDT Thu May 24 2018

This weekend into early next week the main belt of westerlies
remains up across Canada while an upper low rotates slowly eastward
across the western US, promoting ridging downstream into the
Midwest. A shortwave trough dropping into the northern Great Lakes
could help spark a few showers/storms on Saturday, especially across
northern WI. Overall, however, predominantly dry weather is expected
through the holiday weekend. Have maintained some low rain chances
at times with the GFS more aggressive in bringing several weak upper
waves through the upper ridge. However, GFS boundary layer moisture
appears way too high, likely contributing to its propensity to
develop more convection. By the middle of the week shower/storm
chances may increase as the upper flow becomes southwesterly with an
upper trough ejecting towards the region.

Very warm/hot temps are expected through the weekend with
impressive 850 mb temp anomalies focused from the northern plains
into the Upper MS Valley. Some 90 degree readings look likely
Sat/Sun and possibly into Monday. Temps should cool a bit for mid-
week, but remain above average.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1104 PM CDT Wed May 23 2018

06Z TAFS will be VFR. Winds will be increasing on Thursday and
becoming gusty at KRST. In the evening, TSRA chances are going to
be increasing for KRST. Some thunderstorm activity may approach
from the west but at this time confidence is too low to include in
the TAF. LLWS may also present itself Thursday night and will be
assessed in future forecasts.

&&

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

$$

SHORT TERM...JM
LONG TERM...JM
AVIATION...Baumgardt



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