Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 140533
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1133 PM CST Tue Feb 13 2018

.SHORT TERM...(Tonight and Wednesday)
Issued at 212 PM CST Tue Feb 13 2018

Mid-level clouds have been stubborn to dissipate within a region of
weak lift ahead of an upstream upper trough. However, clouds should
be on the decrease through late afternoon with increasing mid/upper
level subsidence as the trough swings through the area. NAM/RAP
soundings indicate very dry air through much of the atmosphere
tonight, so expect mostly clear skies. Continued low-level warm
advection will keep temps milder than previous nights, with lows
mainly in the teens to low 20s.

On Wednesday, the upper flow will remain quasi-zonal over the
Midwest. Warm advection will ahead of a surface low passing across
southern Canada will help boost 925 mb temps to 2-4C through the
day. This would support highs in the upper 30s to as high as the mid
40s over central Wisconsin, even with a snowpack. There is some
concern lower clouds may try to spread northward later in the day
with increasing low-level moisture, but much of the area is expected
to remain in a dry airmass through the the day (precipitable water
values remaining 0.20 to 0.35 inches), so the lower clouds may skirt
by mainly to the southeast.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 212 PM CST Tue Feb 13 2018

Liking the idea of Wednesday`s break from winter? Some of that
mildness looks to stick around into Thursday as well as the local
area sits in continued westerly flow in advance of out next
approaching cold front. That feature should arrive sometime Thursday
afternoon, but not before highs likely warm well into the 30s to
potentially even near 40 in a few spots, held back only by a lack of
better mixing in the pre-frontal environment, and potentially some
lower clouds clipping parts of the area, especially early on.

Don`t get too used to the warmer conditions, as a sharp return to
reality arrives behind the cold front Thursday night into Friday
with a quick round of upper troughing working back into the region.
driving highs (you guessed it) back below normal to wrap the work
week, though thankfully lots of sunshine by Friday afternoon as some
quite dry air rolls back into the region. Prior to that, however,
still watching some small potential for a little light snow mainly
Thursday evening/early overnight with some weak mid level FGEN
response with a shortwave sliding through the area, though overall
moisture is lacking and forcing is waning with southward extent.
Still, probably worth at least a mention, especially near and north
of I-90.

Beyond Friday, things get a little murky into the weekend and
especially next week, with plenty of model disagreement on how to
handle various streams of energy over the western CONUS in a quite
fast flow regime. GFS/GEM don`t dig as much of a western CONUS
trough with time as the ECMWF does, which is a bit at odds with
their ensemble means and doesn`t exactly add to the confidence
factor (i.e. we`re in that type of pattern where things can change
quickly in model world). Suffice it to say that the overall weather
regime across the region looks more active into next week with some
semblance of western troughing and pronounced southeast ridging
favoring a rather tight baroclinic zone somewhere across the Mid
Mississippi River Valley. While exact placement will be key with
regard to precipitation type locally, there does appear to be at
least some risk for more wintry weather across the area into next
week. Even prior to that time, will be watching the Sunday timeframe
with persistent hints for a shortwave crossing the area and
providing some precip risk, though with low confidence on exact type
given poor run-to-run continuity regarding thermal profiles.
Certainly plenty of details to be worked out the next 7-10 days.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1133 PM CST Tue Feb 13 2018

LLWS will continue at KLSE through around 11Z. Otherwise, the main
aviation concern will be the potential for MVFR visibility in BR.
Low level moisture increasing over the region is creating
visibility restrictions into the 4 to 7 SM range. Plan on mainly
VFR conditions then through the daytime hours on Wednesday. There
is the potential for low stratus to move into the region Wednesday
evening but the latest indications are that this will stay well
south of Interstate 90.

&&

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

$$

SHORT TERM...JM
LONG TERM...Lawrence
AVIATION...Wetenkamp



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