Area Forecast Discussion
Issued by NWS La Crosse, WI

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235
FXUS63 KARX 292337
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
537 PM CST Tue Nov 29 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 255 PM CST Tue Nov 29 2016

Main forecast concerns are on rain and snow showers on Wednesday
with the potential for some very light snow accumulation mainly on
grass surfaces.

Low pressure continues to spin across the Upper Midwest late this
afternoon and will start edging eastward into the local area late
tonight through Wednesday. The cloud cover forecast will be
challenging tonight across the southeast 1/2 of the forecast area.
Clouds across portions of northeast Iowa, southeast Minnesota, and
central Wisconsin will edge southeast leading to cloudy skies
across most if not all of the area. However, this may not happen
until Wednesday as the the low moves in. Light rain and snow is
possible tonight mainly west of the Mississippi River as the first
wave of vorticity moves through. Periods of light rain and snow
showers are expected on Wednesday, especially late morning into
the afternoon when low level lapse rates will be the steepest.
Minor snow accumulations are possible and under the steadier snow
showers we could pick up a trace to perhaps a few tenths
accumulation before quickly melting. Also, the snow showers may
produce some brief visibility restrictions at times.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 255 PM CST Tue Nov 29 2016

The low continues to edge east Wednesday night but we will stay in
cyclonic flow providing cloudy skies and perhaps some very light
rain or snow. Rain/snow chances linger into Thursday morning then
weak surface high pressure edges into the Upper Mississippi River
Valley. We should finally start to break out of the pesky low
clouds by late in the day Friday as the cyclonic flow aloft
finally shifts east. Cooler temperatures are on the way for
Thursday into Friday. Friday looks to be the cooler of these two
days when highs will struggle to get out of the 30s.

The 29.12Z GFS and ECMWF have come into better agreement on the
synoptic pattern through the weekend, but timing differences still
exist. Both models bring two shortwaves through the region. The
first one early Saturday is weaker and slightly out of phase between
the models. The second one is stronger and passes through on Sunday.
Moisture and forcing are not that impressive, especially with the
first wave. The ECMWF is a little more excited with spreading QPF
across our area on Sunday with the second wave. The GFS and ECMWF
bring ridging through late Sunday into Monday ahead of a shortwave
progged to move from Texas towards the Great Lakes and a deepening
longwave trough over the western CONUS. The GFS is slightly quicker
bringing the Texas shortwave towards our region late Monday. Both
models contain good forcing and moisture signals for precipitation
from this system, which could be a wintry mix.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 537 PM CST Tue Nov 29 2016

The surface low spinning over western Minnesota will move into
western Wisconsin through Wednesday morning and the reform to the
east of Lake Michigan. This will be in response to the upper level
low moving east across the region and as the short wave trough
over the Dakotas swings around the upper level low. Some light
rain or snow is occurring with this system and this is expected to
move into the area Wednesday morning. It should primarily be a
rain/snow mix for KRST with just rain at KLSE. Ceilings will drop
down to IFR/MVFR ahead of the precipitation and then remain there
for the rest of Wednesday. The visibility will go down in the
precipitation as well with IFR expected at KRST and MVFR at KLSE.

&&

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

$$

SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp
AVIATION...04



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