Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 172045
AFDARX

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

.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 18Z TAFS through 18Z Saturday afternoon)
Issued at 1131 AM CST Fri Feb 17 2017

A warm front will work its way across the area today and then be
followed by a very weak cold front tonight. High pressure will
then settle in over the region for the weekend. Not much sensible
weather is expected with these front with only a wind shift from
the south around to the west. Wind speeds should remain around 10
knots or less, but there will likely be some speed shear for KLSE
this evening. Stronger wind speeds above the inversion of 30 to 35
knots will be in place until the cold front moves through and
these settle down a few hours behind the passage of the front.

&&

.CLIMATE...
Issued at 321 AM CST Thu Feb 16 2017

Temperatures will be some 20 to 30 degrees above normal Friday
through Monday.

Here are some record highs and record high lows for La Crosse and
Rochester for Friday February 17th through Monday February 20th:

                          Record Highs
                          ------------

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

Fri (17th)    64/1981        Fri (17th)     63/1981
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
                         ----------------

Fri (17th)    41/1981        Fri (17th)     35/1981
Sat (18th)    38/1981        Sat (18th)     37/1954
Sun (19th)    38/2002        Sun (19th)     36/2002
Mon (20th)    41/1930        Mon (20th)     34/1954

&&

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

$$

SHORT TERM...JM
LONG TERM...JM/Hollan
AVIATION...04
CLIMATE......DAS



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