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Area forecast discussion 
National Weather Service La Crosse WI
500 PM CST Friday Mar 6 2015

Short term...(tonight through Saturday night)
issued at 208 PM CST Friday Mar 6 2015

Concern in the short term includes a couple waves of low pressure
that may impact parts of the area with some light snowfall...mainly
across northern WI tonight and then across southeast Minnesota/northeast
Iowa/southwest WI late Saturday night.

For tonight...will be watching an area of low pressure dropping
southeast out of eastern Saskatchewan toward the area. By
sunrise...this low is expected to deepen and be located just north
of Lake Superior. Lift in warm air advection ahead of this wave will
bring in/thicken cloud cover but appears any snow chances will
remain over far northern WI. Kept small-end 20-30 probability of precipitation across Clark
and Taylor counties. Otherwise...with cloud and warm air advection
overnight...plan on low temperatures in the upper teens to the
middle 20s.

For Saturday...looks like a breezy day as that area of low pressure
departs to the east keeps US in a fairly tight pressure gradient.
Also looks like we will see some cumulus/stratocumulus in lingering
cyclonic flow. Expecting northwest winds in the 10-20 miles per hour range with
gusts in the 15-25 miles per hour range. Fairly neutral temperature advection
noted behind this wave of low pressure in the thermal field...so
looks like highs should top off in the middle 30s to the lower 40s.

Saturday night brings a decent chance of light snow across portions
of southeast Minnesota/northeast Iowa..into southern WI. This is in
response to an approaching middle-level trough out of the Dakotas and
interaction with right entrance region 90-110kt 300mb jet/850-500mb
frontogenesis. Latest 06.12z Gem and European model (ecmwf) not flinching much from
previous runs yielding quantitative precipitation forecast across portions of southeast Minnesota/northeast
Iowa/far southwest WI. The NAM and GFS have Sam synoptic forcing...but
keep precipitation just south outside the arx forecast area. As
such...and after coordination with surrounding offices...will
maintain a 40-ish pop for the aforementioned area late Saturday nigh
into Sunday morning. Either way...snowfall looks to be on the light
side...with the potential of around an inch.

Long term...(sunday through friday)
issued at 208 PM CST Friday Mar 6 2015

Past the snow light snow chances across the south Sunday
morning...warm-up looks underway into next week as upper level ridge
builds toward the central Continental U.S.. overall westerly wind trajectory
off the plains will continue to draw warmer/downsloped air over the
plains into our area through Wednesday. Look for highs Sunday and
Monday in the upper 30s to the lower 40s...warming into the middle
40s/lower 50s Tuesday and Wednesday. On Thursday...it appears
slightly cooler temperatures by a few degrees will be seen as a
Canadian high builds into the Great Lakes region...turning winds to
a southeasterly direction away from the warmer plains. Latest
GFS/European model (ecmwf) show the upper level ridge breaking down a bit as a trough
rides through southern Canada. This doesnt appear to have too much
affect on high temperatures though as blended model output still
yields highs in the middle 40s to the lower 50s.

&&

Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 500 PM CST Friday Mar 6 2015

Surface boundary sweeping across the area toward 12z Sat...and while any
precipitation chances look to stay north...some models suggest a period of
MVFR ceilings. NSSL WRF synthetic Sat imagery also points to this
possibility...which matches with some low clouds over southern Canada
at this moment. Doesn/T look like it would last long and confidence
is not high in its occurrence. Will hold with some tempo MVFR ceilings
for now.

Winds are going to bounce from the south/southwest to the northwest
Sat morning as the surface boundary moves throughout. Speeds will pick up
as the pressure gradient increases...with some gustiness as near surface
lapse rates climb.

&&

Arx watches/warnings/advisories...
WI...none.
Minnesota...none.
Iowa...none.
&&

$$

Short term...das
long term...das
aviation...rieck

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