Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 180357

Area Forecast Discussion
National Weather Service La Crosse WI
957 PM CST Fri Feb 17 2017

Issued at 535 PM CST Thu Feb 16 2017

What an awesome weather day, even for a winter weather fan such
as myself. We fell shy of records by a couple of degrees but highs
ended up still well into the 50s and lower 60s for many areas.
Only exceptions were across portions of southeast MN with a
southerly wind trajectory traversing remnant deeper snow pack per
afternon satellite imagery under clear skies, and areas near/north
of I-94 where up to 8 inches of snow remains on the ground.
Interesting that while we cool aloft tomorrow behind a weak cold
front, northwest wind trajectory will likely bring warmer warmer
temps to those spots who missed out on today`s warmth.

All in all, an exceptionally quiet weather night, with guidance
hints of widespread stratus/fog appearing way overdone per
upstream obs. Can`t totally rule out a touch of some fog for snow
covered areas where melting occurred today, but don`t envision
anything widespread. Just a milder February evening/night -


.SHORT TERM...(This evening through Saturday)
Issued at 245 PM CST Fri Feb 17 2017

Temps have warmed nicely this afternoon into the 50s and low 60w
with abundant sun and continued 925 mb warm advection. Snow-
covered areas of NE IA/SE MN and north central WI have remained a
bit cooler.

Upper level ridging over the area this afternoon will
flatten as a fast moving shortwave trough transits the US/Canadian
border region tonight. This wave will drag a weak cold front
through tonight, but the impacts to our weather will be minimal.
Temps will trend slightly cooler tomorrow, but will remain well
above average in the low to mid 50s in most areas, although snow-
covered areas may remain a little cooler. Some high cloud cover
may spill eastward into the area with the flattening upper flow.

.LONG TERM...(Saturday night through Friday)
Issued at 245 PM CST Fri Feb 17 2017

Weak surface high pressure across the area Saturday night will
give way to strengthening southerly flow on Sunday/Sunday night
ahead of developing low pressure across the high plains. By
afternoon, 925 mb temps rise to 9-13C. This should help boost
temps back to near record values in the 50s to low 60s. High
level moisture depicted in model 300 mb RH fields suggests some
high cloud cover.

17.12Z guidance has remained in good agreement overall with an
upper trough and associated frontal system sweeping across the
region Monday/Monday night although the GFS is slightly faster
compared with the ECMWF. Strong moisture advection ahead of the
system will transport dewpoint into the low 50s into the area and
precipitable water values over an inch (3-4 standard anomalies
above climo). Good agreement persists in a band of showers
shifting eastward with the frontal system Monday- Monday night
with the GEFS indicating around 1/4 to 3/4 of an inch of rain
possible, dependent on any convection which could result in
locally higher amounts. The GFS shows modest MUCAPE of around 300
J/kg along the front, so a few embedded storms are possible. Temps
will begin the day on Monday very mild in the 40s over much of
the area. The main limiting factor for how warm temps get on
Monday will be increasing lower cloud cover/showers, but it still
should be a very mild day.

Long range models are in agreement placing the region under mainly
zonal flow Tuesday and Wednesday, with a shortwave passing by to our
north late Tuesday/early Wednesday. GFS and ECMWF are slightly out
of phase with this feature, but no weather impacts expected other
than a slight chance for a few light rain showers. Temperatures
should remain 20-30F above normal Tuesday and Wednesday, with highs
in the 50s and lows in the 30s to lower 40s. The main forecasting
concern during the extended period will be a vigorous upper-level
trough ejecting eastward off the Rockies toward the Upper Midwest
Thursday into Friday. In contrast to the 16.12Z run, the 17.12Z GFS
now projects more of an open wave sliding across the north-central
CONUS, placing the associated surface low track from the Central
Plains, through our CWA, and towards the eastern UP of Michigan. The
17.12Z ECMWF persists with digging the trough deeper, but is fairly
in line with the track of both the upper-level and surface lows
relative to the 17.12Z GFS. Long story short, this system will have
a potential to bring impactful weather in the form of mixed
precipitation to the region Thursday and Friday.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 957 PM CST Fri Feb 17 2017

VFR conditions continue through Saturday evening with just some
increase in higher level cirrus expected after sunrise. Winds will
shift to the west and northwest as a cold front passes, with
speeds generally 8 to 15 knots subsiding Saturday afternoon and
evening as high pressure approaches.


Issued at 535 PM CST Thu Feb 16 2017

Well...temperatures were certainly warm on Friday but fell shy of
records. Saturday overall looks a bit cooler behind a passing weak
cold front, but with some chance for us to approach records again
Sunday and perhaps Monday, pending timing of clouds and rainfall
to start the work week.

Below are the records for La Crosse and Rochester through Monday
February 20th:

                          Record Highs

             La Crosse                     Rochester
            -----------                   -----------

Sat (18th)    64/1981        Sat (18th)     60/1981
Sun (19th)    59/1930        Sun (19th)     59/1930
Mon (20th)    61/1930        Mon (20th)     60/1930

                         Record High Lows

Sat (18th)    38/1981        Sat (18th)     37/1954
Sun (19th)    38/2002        Sun (19th)     36/2002
Mon (20th)    41/1930        Mon (20th)     34/1954




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