Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 271938

Area Forecast Discussion
National Weather Service La Crosse WI
238 PM CDT SAT AUG 27 2016

.SHORT TERM...(This evening through Monday night)
Issued at 238 PM CDT Sat Aug 27 2016

Tonight could be a good night for fog to form across the area if
the clouds can clear out in time to allow for enough cooling.
Plenty of low level moisture trapped below the clouds today and
with light winds expected through the night but just how much
clearing will take place is the main question. Visible satellite
shows the current cloud deck extends well back into southwest
Iowa. Forecast soundings suggest this back edge of the clouds
should work its way into the area this evening. These sounding
also show the winds just above the surface remaining around 10
knots until late tonight, so this could lead to more of a low
cloud deck forming than fog. For now, will go with more of the low
clouds forming than fog but will show some fog, especially in the
river valleys.

Some small rain chances return to parts of the area Sunday. A weak
short wave trough is expected to come across the northern sections
of Minnesota and Wisconsin. This wave looks to be pretty flat with
very little pv advection, but there is some warm air advection in
the low levels that generates 2 to 4 ubar/s of up glide on the
305K isentropic surface. Not sure if this will be enough forcing
to generate any rain, but will carry a very small chance across
the northern sections Sunday afternoon and night for this.

Another weak short wave trough should pass along the Canadian
border Monday that will push a cold front in to the area Monday
night. Again, the wave looks to be pretty flat with little or no
pv advection and in fact, the upper level ridge could hold pretty
tight over the Upper Midwest. There could be a weak band of
frontogenesis in the 1000-700 mb layer with the front with 1 to 2
ubar/s of up glide on the 310K isentropic surface. The moisture
transport axis is well to the north of the area ahead of the short
wave trough so would only expect some scattered showers and storms
at best with this system.

.LONG TERM...(Tuesday through Saturday)
Issued at 238 PM CDT Sat Aug 27 2016

The GFS and ECMWF are in good agreement with a cold front and any
associated precipitation exiting the area to the south Tuesday
night. A ridge builds to the west, putting the area into northwest
flow until the ridge axis slides through the area later in the week.
While both the GFS and ECMWF slide a few shortwaves and
precipitation through following the ridge, the GFS is a bit faster,
bringing the precipitation in Friday night, while the 27.00Z ECMWF
holds off until Saturday morning and 27.12Z ECMWF keeps the area dry
until late Saturday night. As far as temperatures, seasonable highs
in the mid to upper 70s are expected, with lows in the 50s.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1232 PM CDT Sat Aug 27 2016

cyclonic low level flow, recent rains an abundant low level moisture
have combined to produce rather widespread IFR/MVFR cigs across much
of IA/southern MN/southwest WI thru this morning. With weak gradient
flow and a broader passing trough aloft, the lower clouds to persist
thru the afternoon into early this evening, with only a gradual slow
rise of cig hgts with the diurnal warming/mixing thru the afternoon.
Passage of the main mid level trough and the lower level cyclonic
circulation should allow for a decrease of clouds this evening.
However a moist/cool boundary layer with smaller temp-dew point
spreads will be left behind, with conditions very favorable for
radiational fog formation in the 08z-14z timeframe Sun morning. In
the 10-15z period, continued with IFR conditions in BR at KLSE and
added some MVFR vsbys to KRST. Will have to watch KLSE for LIFR
cigs/vsbys in FG around 12z Sun. Once any BR/FG lifts/dissipates Sun
morning, generally good VFR expected thru the remainder of Sun into
Sun evening.


Issued at 238 PM CDT Sat Aug 27 2016

River levels continue to fall on the Turkey River with both
Elkader and Garber expected to go below flood stage tonight. See
the latest flood statement for specific forecast information.


.ARX Watches/Warnings/Advisories...


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