Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 140534
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1134 PM CST Mon Feb 13 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 300 PM CST Mon Feb 13 2017

Models remain in good agreement on dropping an upper level shortwave
trough out of northern Canada south/southeast across the Upper
Mississippi River Valley Tue afternoon, swinging east across the
eastern Great Lakes by late Tue night. Decent QG convergence in the
700:300 mb layer with the shortwave, along with some frontogenetic
forcing on the leading edge. Low level cooling leads to favorable
low level lapse rates - roughly 8 C/km in the 1000:850 mb layer over
WI Tue afternoon/evening. A decent amount of forcing for some pcpn
chances. However, saturation is going to be a limiting factor.
Northeast-southwest running x-section points to some increase in sub
700 mb saturation for Tue afternoon/evening across northern/eastern
WI, but keeps it rather dry as you head southwest. Is that enough RH
for the forcing to play with to produce some shower chances? Might
be - at least enough confidence to continue small chances for the I-
94 corridor eastward.

.LONG TERM...(Thursday through Monday)
Issued at 300 PM CST Mon Feb 13 2017

April temperatures for mid February next weekend.

Models continue to suggest its going to be shorts/tshirt kind of
weather for some this next weekend, building in strong upper level
ridging coupled with a surge northward of very mild air. First ridge
axis works over the Upper Mississippi River Valley by 18z Fri,
shifting east as an upper level shortwave trough quickly slides in
behind it - holding mostly over southern Canada. Not expecting any
pcpn chances with the shortwave. Upper level ridging then quickly
returns for later Sat/Sun.

850 mb temps progged to max out around +10 c at 00z Sat, cooling a
tad for the weekend, but could bump back to +10 on Monday. NAEFS 850
mb anomalies still around +1 to +2, but expect these to be on the
increase as we approach the weekend (if this warm signal persists).
The EC remains the warm model, highlighting some 60+ degree highs
for the weekend. The GFS is 10 to 15 degrees colder. GEFS plumes
continue to show a lot of variability (from 38 to 54 for highs at
KLSE Sunday), but all the trends point "up". Snow depth across the
local area ranges from zero to 6", but expect much of that to be
gone as we work into the weekend, eliminating a potential deterrent
to the warming. Going to continue to start with a consensus blend
for temperatures in this period, then mixing in more of the warmer
EC.

The next "decent" shot for pcpn comes for the start of the new work
week as a west coast upper level shortwave moves east. Broad north-
south running swath of pcpn favored by the GFS/EC with this system,
which would give most of the area a good shot at some wetting -
likely rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1134 PM CST Mon Feb 13 2017

The surface trough of low pressure was beginning to move across
the area swinging the winds around to the west/northwest. This
will be through KRST by 06Z and should go through KLSE between 08Z
and 09Z. Very little cloud cover with the trough and the mid level
VFR ceilings over northern Minnesota are expected to move by both
airports to the north. There is a continued signal in the models
of some low level moisture coming south out of Canada Tuesday to
produce VFR ceilings in the 4 to 6 thousand foot range. There are
some ceilings in this range over western Ontario this evening
where this moisture is supposed to come from so have included this
in both forecasts. Low level lapse rates will be steep enough to
support gusts to around 25 knots at both airport from about mid
morning through the afternoon.

&&

.HYDROLOGY...(for latter week into the weekend)
Issued at 311 AM CST Mon Feb 13 2017

Big warmup anticipated for Thursday into the weekend. Daytime highs
are expected to warm from the 30s/40s on Thursday into the 40s/50s
for Friday into the weekend. These temperatures are expected to melt
much of the existing snow pack across the area. This snowmelt
combined with a frozen layer of ground is expected to cause runoff
into area streams and rivers. Right now, no flooding is expected but
within bank rises are likely along with the potential for a few ice
jams. Those with interests along streams and rivers will want to
keep up with the latest forecasts.

&&

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

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...04
HYDROLOGY....DAS



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