Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 170450

Area Forecast Discussion
National Weather Service La Crosse WI
1150 PM CDT Sat Sep 16 2017

Issued at 127 PM CDT Sat Sep 16 2017

Afternoon GOES Water Vapor imagery showing a vigorous mid-level
trough rotating northeast from the Dakotas into northwest MN. This
was driving a surface cold front eastward into the area. Current
radar was showing scattered showers and a few storms working
northeast into the area from IA in 850mb moisture transport ahead
of the front.


.SHORT TERM...(This evening through Sunday)
Issued at 127 PM CDT Sat Sep 16 2017

For tonight...main focus will be on convection along/ahead of the
cold front pushing through the area. Given,the main mid-level pv
support rotating northeast through northern MN and better CAPE
pool remaining south of the area over southern IA/MO, thinking
(and latest CAMs confirm), showers/storms will be fairly scattered
in nature along the front as it pushes east through our area.
CAPE will be waning as this convection moves into/through the area
with better bulk shear post-frontal. As such, not expecting any
severe storms but cannot rule out an isolated stronger storm or
two that may produce gusty winds of 30-35 mph and maybe some pea-
size hail. Cooler air filtering into the area after midnight will
drop temperatures into the 50s and lower 60s.

Cooler/drier air filters into the area Sunday as high pressure
builds in. After some morning clouds, skies will be mostly sunny
by afternoon with highs more typical of mid-September in the
middle 60s to middle 70s.

.LONG TERM...(Sunday night through Saturday)
Issued at 127 PM CDT Sat Sep 16 2017

The high will begin to move off to the east Sunday night as a weak
mid-level trough ejects northeast out of the Central Plains. This
will bring increasing mid=level clouds along with a slight chance
of showers across northeast IA. This trough will continue to move
northeast across the area Monday for scattered showers along with
a slight chance of a few storms across portions of northeast
IA/far southwest WI. Otherwise, looking cooler than normal with
the cloud cover and scattered rain showers. Plan on highs only in
the middle 60s to the lower 70s.

For Tuesday through Saturday, southwest flow aloft will continue
to produce periodic showers and storm chances. Temperatures are
expected to be slightly above normal through this period.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1150 PM CDT Sat Sep 16 2017

Batch of showers and thunderstorms continues to work across the
region, but has struggled thus far to make too much northward
progress. Still think RST will see some showers and likely a few
rumbles of thunder through 08Z, while LSE does the same through
about 09Z or so, before activity quickly shifts east of the area.
As envisioned, lower stratus of MVFR to even briefly IFR levels
continues to overspread the area, but it too will quickly exit
the terminal sites before sunrise as much drier air sweeps in from
the west. That drier air should set up increasing sunshine for
much of Sunday, with northwest winds averaging 10 knots up through




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