Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231117
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
615 AM CDT Mon Oct 23 2017

.SHORT TERM...(Today through Tuesday Night)
Issued at 247 AM CDT Mon Oct 23 2017

Fairly active/evolving mid-level dynamics taking place per latest
GOES Water Vapor loop. A trough was dropping southeast through the
Dakotas while a closed low was lifting slowly northeast over the
Bootheel of Missouri. These two features will join forces for an
active next 24-36 hours. Meanwhile, national radar mosaic was
showing a few high-based light showers ahead of that Dakotas
trough/surface cold front moving through western MN. Otherwise, our
area was relatively quiet early this morning in between lingering
rain/rain showers across southeast WI and those approaching showers
from MN. Partly cloudy/mostly clear skies was allowing some fog
formation across far southwest into central WI. Temperatures ranged
from the lower/middle 30s in the Sand Country of central WI, and in
the 40s elsewhere.

For today, we will be watching those showers moving into the area
ahead of the Dakotas trough/surface cold front. Bufkit model
soundings show very dry air in the lower levels with cloud bases
around 8kft for some evaporation, but feel there will be enough
forcing for a few/scattered showers to reach the ground. Will carry
a 20-40 pop/isolated-scattered shower mention. Otherwise, looks
mostly cloudy today with post-cold frontal passage picking up from
the northwest through the afternoon. Will see gusts approaching 30
mph west of the Mississippi River. Plan on temperatures right around
seasonal normals in the 50s.

Things get a bit more interesting tonight into Tuesday as the
Northern Plains trough joins forces with that closed low moving
north out of the mid-Mississippi River region. Result will be a
congealed closed mid-level low/deep 985-990mb occluded low over
northern lower MI by midnight tonight. This will increase northwest
winds while wrapping showers back into our area. Sustained winds
expected to be in the 15-25 mph range with gusts 25-40 mph after
midnight, strongest in the wind prone areas along and west of the
Mississippi River. Daytime mixing on Tuesday could produce some
higher winds, generally around 10 mph stronger than those overnight.
As such, will likely need a Wind Advisory. Will pass this onto the
dayshift today for further assessment with latest model data.
Otherwise, a pretty raw day in store with scattered showers as well
(mainly east of the Mississippi River) and highs only in the middle
40s with cold air advection.

The low slowly lifts northeast into Ontario Canada/fills Tuesday
night. After a mostly clear evening, plan on increasing clouds again
late as a weak trough drops across northern WI/MN. There is a slight
chance of a few showers across north central WI. Otherwise, plan on
diminishing winds with lows dipping into the lower/middle 30s.

.LONG TERM...(Wednesday through Sunday)
Issued at 247 AM CDT Mon Oct 23 2017

Wednesday looking dry as high pressure slides across the region but
then another passing low and cold front will bring a chance of
showers again Thursday afternoon into Friday. Don`t be surprised to
see a few flakes of snow mixing with rain at times later Thursday
night into Friday morning as temperatures dip into the lower/middle
30s.

An unseasonably chilly airmass will filter into the area for the
weekend as a closed low drops south out of Canada. Look for highs
Saturday and Sunday only in the 40s with lows in the upper 20s to
lower 30s. Cold/cyclonic flow will also bring a chance of showers as
well.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 615 AM CDT Mon Oct 23 2017

Cigs: sct-bkn mid level clouds into the afternoon hours, with
lowering to mvfr expected by 00z (or so) as an upper level shortwave
drops across the area. Should hold generally mvfr through the night.

WX/vsby: a cold front will track east across the region late this
morning/early afternoon, bringing -shra. Don`t expect any vsby
restriction and minimal accumulations. Areas of -shra will then
advances westward across WI as a low pressure system deepens over
the eastern great lakes and retrogrades west. Not certain how far
west the band of showers will make it, but seems like a decent shot
KLSE could see some. KRST likely staying dry.

Winds: tightening pressure gradient as that storm system to the east
deepens and moves over northern MI tonight. Strong/gusty from the
northwest starting this evening, persisting through 00z Wed. Gusts
around 35kts likely at KRST.

&&

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

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...Rieck


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