Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 021732

Area Forecast Discussion
National Weather Service La Crosse WI
1132 AM CST Fri Dec 2 2016

.SHORT TERM...(Today and Saturday)
Issued at 248 AM CST Fri Dec 2 2016

Latest water vapor satellite imagery shows upper level closed low
over eastern Canada and northeast United States and longwave trough
over the Rocky Mountains. With the area remaining under the
influence of cyclonic flow aloft...cloudy skies were seen across
much of the Upper Midwest Region per low cloud/fog product satellite

The 02.00z GFS/NAM in decent agreement in building surface ridge
over the Dakotas today into tonight. This allows cyclonic flow to
remain over the Upper Great Lakes Region. Low stratus deck of clouds
will continue to persist over the forecast area today into tonight.
Clouds may begin to break up late tonight after
surface/upper level ridge axis builds into eastern Minnesota and
western Wisconsin Saturday morning. Forecast area may see some
sunshine during the day Saturday. High temperatures today are
expected to remain nearly steady in the lower to middle 30s...with
highs Saturday in the upper 20s to middle 30s.

.LONG TERM...(Saturday night through Thursday)
Issued at 248 AM CST Fri Dec 2 2016

The 02.00z GFS/NAM/ECMWF indicate upper level long wave trough
breaks down Saturday night into Sunday and west to east zonal
flow develops over the northern tier states. The deterministic
models are in good agreement in tracking shortwave trough embedded
in the west to east zonal flow into the Great Lakes Region
Saturday night into Sunday. The models show deep forcing and lift
with the shortwave trough. Chances of precipitation are
increasing across much of the forecast area after 06z Sunday. The
big question will there be enough warm air near the surface to
change snow into rain or rain to mix in with snow. At this
time...the 02.00z GFS/NAM suggest the atmosphere column will
remain below freezing and the majority of the precipitation will
be all snow across the forecast area Saturday night into Sunday
morning. Temperatures will climb into the middle to upper 30s
Sunday afternoon and rain will mix in or be all rain across much
of the forecast area. Snowfall amounts are expected to be around
an inch along and east of the Mississippi River.

Main forecast concerns Monday through Thursday are precipitation
chances through the period. The 02.00z GFS/ECMWF/GEM are in
agreement in digging upper level trough over the central United
States through the period. However...the deterministic models differ
in placement of the upper level trough. This will have impacts on
movement/placement of individual pieces of energy moving around
the periphery of the upper level trough through the middle
of next week. Hence...precipitation chances across the forecast
area in the middle of next week. At this time...confidence during
this time frame is low. Temperatures will be cooler
Wednesday/ the 02.00z GFS/ECMWF suggest cooler
airmass advects into the forecast area.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1132 AM CST Fri Dec 2 2016

Widespread stratus will persist across the region through tonight
with ceilings generally in the MVFR range. It is possible that
KLSE may jump into the low VFR range for a time this afternoon,
but for now kept the idea of predominantly MVFR. Some improvement
in ceilings back into the VFR range is possible towards the end of
this TAF period, but confidence in timing is low. Otherwise
northwest winds generally around or below 10 kts will shift
westerly tonight.




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