Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 181736

Area Forecast Discussion
National Weather Service La Crosse WI
1136 AM CST Sat Feb 18 2017

.SHORT TERM...(Today through Monday)
Issued at 200 AM CST Sat Feb 18 2017

Unseasonable warmth yesterday, with highs mostly from the mid 50s to
lower 60s...aside from a small pocket over southeast MN where snow
cover still held sway. Highs there only reached 50. Low level temps
cooling a bit today with the passage of a "cold" front from last
night, but expected to flirt with 10 C at 850 mb again Sun/Mon.
NAEFS anomalies hold from +1 to +2. Highs will remain more April
like into Monday, even in the "cold" spot of southeast MN - which
will lose the rest of their lingering snow cover. Monday has some
questions as an increasing cloud/shower threat would temper the
warmth a bit. Near record (record?) temps possible Sun, potentially
again Monday.

As for that next precipitation upper level shortwave
trough is slated to lift northeast out of the desert southwest
Sunday morning, with the trough axis sliding east of the region Tue
morning. Low level warm air advection pushes ahead of the trough
with a decent north-south running frontogenetic response. Strong low
level moisture surge into this system as it works across the area -
NAEFS pw anomalies upwards of +4. Rain is expected. The snow pack is
more or less gone, but grounds are wet/frozen, so with around 1/2
inch of rain expected, there should be decent runoff into area
river/streams. Some rises should be expected along with the
potential for ice jams for those locations where ice exists. If
amounts are more, flooding could become a concern. Some meager -
very meager - instability in the soundings, mainly across the south.
Will continue an isolated thunder threat.

.LONG TERM...(Tuesday through Friday)
Issued at 200 AM CST Sat Feb 18 2017

GFS and EC still favoring a winter storm for next weekend, taking a
west coast upper level trough east and lifting it across the eastern
Great Lakes by 12z Sat. Cyclogenesis occurs in the lee of the
Rockies, with both models taking the sfc low straight across the
local forecast area at 18z Friday. Remarkable agreement on
timing/strength. We`ll see how long that holds true. Hefty qg
convergence through the layers of the atmosphere - deepest/strongest
northwest of the sfc low. Nice fetch of 850 mb moisture transport
for mid Feb leads the system into the region. Little to no
instability indicated. What is suggested in bufkit soundings is
barely a whisper. Not enough confidence to add to the forecast, but
something to watch. The current progged track would keep the bulk of
the area in the warm sector - thus rain. Main deformation snow band
would lie from southwest MN into northwest WI with many inches
possible. It`s a storm that we`ll have to keep a close eye on.

Post the storm cold, more seasonable air returns. It is February
after all.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1136 AM CST Sat Feb 18 2017

High pressure, currently centered over eastern Nebraska, will
drift east/northeast through Sunday morning. Other than some high
level clouds starting to arrive from the large upper level low
over the southwest, little in the way of cloud cover is expected.
There is a slowly increasing threat for some fog at night, but not
anticipating this to be much of a problem tonight as the forecast
soundings continue to show very dry air just above the surface.
The fog may become more of a concern for Sunday night as higher
dew point will start to move in and spread over the cold ground.


Issued at 200 AM CST Sat Feb 18 2017

Well...temperatures were certainly warm on Friday but fell shy of
records. Today 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




LONG TERM....Rieck
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