Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 271910

Area Forecast Discussion
National Weather Service La Crosse WI
211 PM CDT Sat May 27 2017

.SHORT TERM...(Tonight through Sunday Night)
Issued at 211 PM CDT Sat May 27 2017

Surface analysis this afternoon has a weak windshift/cold front
extending from central Upper MI through far southwest WI. Meanwhile,
water vapor imagery showing a deep mid-level trough pushing
southeast through the Dakotas/western MN. Water vapor also showing a
dissipating MCV pushing northeast through central IA. As a result,
visible satellite showing quite a bit of high cloud and a few
cumulus across our area. Despite the fairly thick cloud cover,
temperatures as of 2 pm were in the upper 60s to the lower 70s.

May have to keep an eye on a few showers/thunderstorms going into
this evening as that MCV over IA moves into the area along the
lingering cold front through southern sections of the forecast area.
Then mid-level trough and another weak surface cold front push into
the area after midnight. Not expecting any severe weather as CAPE
wanes with loss of surface heating and given lack of appreciable
shear. Kept pops later this afternoon into this evening in the 20-30
percent range, increasing into likely category across central into
southwest WI/northeast IA after midnight as better forcing from the
mid-level trough pushes through.

For Sunday into Sunday night...long wave mid-level trough with a
couple embedded weak shortwave troughs will rotate over the area
with fairly steep lapse rates resulting. This will continue to
produce shower chances along with a chance for a few thunderstorms
Sunday afternoon during peak heating as CAPE increases and as
another surface cold front pushes in. Right now, looks like this
front and better CAPE pushes east of the area by afternoon. Drier
and breezy conditions spread in behind the front in tightening
pressure gradient. Looks like any showers Sunday night will be
confined northeast of I-94. Otherwise, look for highs in the upper
60s to the lower 70s and overnight lows falling into the upper
40s/lower 50s.

.LONG TERM...(Monday through Saturday)
Issued at 211 PM CDT Sat May 27 2017

Showers chances continue Memorial Day into Tuesday as cooler
cyclonic flow prevails overhead. Steeper lapse rates Monday
afternoon may be enough to spark an isolated storm or two as well.
Otherwise, plan on cooler highs with reading Monday topping off in
the 60s and in the upper 50s to middle 60s Tuesday. Plenty of
cumulus again for Wednesday in cooler cyclonic flow but will leave
dry for now. Look for highs in the 65-70 degree range.

Northwest flow aloft brings in another shortwave trough on Thursday
for a chance of showers. Heights are building aloft overall though
as the closed low moves farther east of the area, so highs will be a
few degrees warmer in the 70-75 degree range.

Extended models diverging quite a bit for Friday and Saturday. GFS
keeps us cooler/dry as surface high settles across the region.
Meanwhile, the ECMWF has us in warm air advection scheme with low
pressure moving through the Northern Plains. This would push a few
showers through the area. Will settle on consensus with small-end
rain chances at this time.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1130 AM CDT Sat May 27 2017

Cigs: mostly mid/high level clouds expected for today and tonight,
with mostly bkn cigs for the night time hours.

WX/vsby: some threat for shra later this afternoon/tonight. Meso
model trends would favor keeping most of the activity south of the
TAF sites into early evening, with the HRRR runs suggesting
scattered showers after 06z - tied with an upper level shortwave
trough. Matches reasonably well with latest RAP and NSSL WRF runs.
Will add some -shra tonight, but no vsby restriction for now. Don`t
see much of a thunder threat with loss of daytime heating.

Winds: northwest becomes light west/vrb tonight. Should increase a
bit and hold west by mid/late Sun morning.


Issued at 211 PM CDT Sat May 27 2017

Elevated river levels continue along the Mississippi River with
flood warnings in effect for some areas. Stronger than normal
current associated with the elevated water level will produce
increased debris in the water which may be hazardous to watercraft.
Continue to exercise extreme caution if you are planning any
recreational activities on or near the Mississippi River. Continue
to closely monitor river forecasts and the latest river statements.





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