Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 131726

Area Forecast Discussion
National Weather Service La Crosse WI
1126 AM CST Mon Feb 13 2017

.SHORT TERM...(Today through Tuesday Night)
Issued at 311 AM CST Mon Feb 13 2017

Surface map this morning features high pressure centered over MO
with ridge axis extending northward into the Upper Mississippi River
Valley. This was resulting in clear skies across our forecast area
with temperatures as of 2 am ranging from 14 degrees at Black River
Falls to 28 at Oelwien and Charles city Iowa.

High pressure pushes off to the east today and a cold front drops
through the Dakotas into MN. This will set up warm air advection
across the forecast area with 925mb temperatures pushing into the 3-
6C range (per latest RAP) along with abundant sunshine. This is
expected to warm surface temperatures to well above normal levels
again with readings topping off in the upper 30s to the upper 40s.

For Tuesday afternoon into Tuesday night, a cold front will drop
across the area into the Great Lakes region for a chance of snow
showers. These showers should be confined east of the Mississippi
River where steeper low-level lapse rates will exist along with
better mid-level PV-advection. Look for highs Tuesday in the middle
30s to lower 40s with lows Tuesday night dropping into the teens and
lower 20s.

.LONG TERM...(Wednesday through Sunday)
Issued at 311 AM CST Mon Feb 13 2017

After a chillier (but still slightly above normal) day Wednesday
with highs in the 20s/30s, a significant warming trend is set for
the remainder of the week into the weekend.

Models showing a very consistent signal for warming as mid/upper
level ridge of high pressure pushes into/amplifies over the region.
High temperatures expected to warm from the 30/40s on Thursday into
the 40/50s for Friday through Sunday. This raises some
hydrology/river concerns. See special hydrology section for details.

Strong upper level ridging slated to build in from the Plains for
next weekend, with the ridge axis overhead by 18z Fri, slipping east
Sat. A lot of unseasonably warm air slated to accompany the ridge
with 850 mb temps progged to max out around +10 C or so. NAEFS 850
mb temp anomalies hover from +1 to +2 for the weekend. Snow cover
roughly 1 to 6 inches across the forecast area, and expect a lot (if
not most) of that to melt off over the next several days. With skies
looking mostly sunny for the weekend, and eliminating the snow cover,
the setup is ripe for highs more reminiscent of early April rather
then mid February. The EC is a lot more aggressive with its warming,
suggesting some 60 degree temps are possible. The GFS is 10 degrees
colder while also showing quiet a spread in its ensemble members
(for instance,  from 51 to 30 for highs on Sat at La Crosse).
Either way, much above normal. Will start with the model blend
for temps, but increase a bit toward the warm EC.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 1126 AM CST Mon Feb 13 2017

Good VFR conditions expected thru this afternoon and tonight as a
drier low level airmass prevails over the region. With winds in the
valley at KLSE S-SE around 10kts and lowest gates on the KARX WSR-
88D indicating SW winds 3-35kts, did include mention of LLWS at KLSE
thru much of the afternoon as a heads-up to those on approach or
climb-out from KLSE this afternoon. Otherwise, SW winds 10-20kts
this afternoon/evening will swing to the NW at 10-15kts overnight as
the sfc trough/front passes. Some indication for an increase of
lower level moisture behind the front/trough for very late tonight
and Tue morning. However, models looking too robust with this
moisture/clouds upstream across southern Man/Saskat and western Ont
late this morning, and bulk of the deeper moisture looks to pass
across central/eastern WI, closer to the passing sfc-mid level low.
For now, only carried sct 3K-4K Tue morning.


.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.




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