Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 180441
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1141 PM CDT Fri Mar 17 2017

.SHORT TERM...(This evening through Saturday)
Issued at 300 PM CDT Fri Mar 17 2017

Quieter weather is expected heading into the weekend. An upper
shortwave will slide across the region overnight tonight with
widespread low clouds across the area. The relatively tight
pressure gradient between low pressure across the northern Great
Lakes and high pressure nosing southeastward from the northern
plains along with cold advection and mixed layer winds remaining
near 35 kts will keep winds on the breezy/gusty side tonight. A
few rain/snow showers are possible into tonight, especially across
north-central WI with the trough passage and very cool mid-level
temps. Will have to watch late this afternoon for possible
southward expansion of pops.

Clouds will gradually decrease with deep subsidence Saturday as
the upper trough pulls away and ridging builds eastward. As the
surface ridge axis approaches, winds will also be on the decline.
Temps should reach near seasonal averages in the upper 30s to mid
40s.

.LONG TERM...(Saturday night through Friday)
Issued at 300 PM CDT Fri Mar 17 2017

The progressive upper level ridge will shift over the area Saturday
night into Sunday, while the surface high slides eastward.
Strengthening low to mid level warm advection will develop later Saturday
night into Sunday as low-level winds turn southerly ahead of an
upper trough/surface low moving across southern Canada. 925 mb
temps rise to 6-11C by late Sunday with the warmest 925 mb temps
just west of the area ahead of the approaching cold front. As a
result, most areas should warm into the 50s. There will likely be
some mid/high clouds, while some lower clouds could advect
northward with increasing moisture transport into the region,
which could impact highs. Winds will increase from the south,
gusting to 20 to 30 mph.

The cold front will move through Sunday night. Model solutions have
not been overly excited with precip potential over the region,
especially with the shortwave and strongest forcing remaining up
across Canada. There has been a signal for some elevated
convection to develop Sunday night ahead of the front near the
nose of a 925-850 mb jet in a region of steep 700-500 mb lapse
rates and some elevated instability. At this point, it looks like
the better chances for thunder may be just south of the region
closer to where models show the stronger low-level jet convergence.

With a mild start to the day, temps on Monday should climb up into
the 40s and 50s, even with cold advection. A secondary push of
cooler air will filter into the region Monday night into Tuesday as
surface high pressure builds into the Upper Midwest. This will just
serve to knock temps back down to near average.

Dry weather will continue through mid-week as upper level ridging
spreads back across the north central US.  The next potentially
impactful system to watch will be a shortwave trough coming out of
the Rockies late in the week. The global models indicate strong
moisture transport ahead of the system and with split flow, not a
lot of cold air may be available for the system to tap, and the
operational GFS/ECMWF have shown warmer, more northern solutions
the past few runs. That said, ensemble guidance still indicates
plenty of spread in possible solutions for this system with regard
to track and timing. So while it looks like precip chances will
increase late next week, confidence is not overly high on the
details at this point.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1141 PM CDT Fri Mar 17 2017

Satellite imagery continues to show a large expanse of clouds
caught up in the low level cyclonic flow around the surface over
southwest Ontario. With the slow southeast movement of the surface
low, the cyclonic flow and clouds will remain through Saturday
morning before scattering out early in the afternoon as high
pressure builds in from the west. Ceilings are expected to remain
MVFR until the clouds break up. The winds have become gusty as
cold air advection in the cyclonic flow as allowed some steep low
level lapse rates to form. There will be enough wind in the mixed
layer for the gusts to continue through the night before
diminishing late Saturday morning.

&&

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

$$

SHORT TERM...JM
LONG TERM...JM
AVIATION...04



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