Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 222248

Area Forecast Discussion
National Weather Service La Crosse WI
448 PM CST Fri Nov 22 2019

.SHORT TERM...(This evening through Saturday)
Issued at 158 PM CST Fri Nov 22 2019

Pesky morning stratus has given way to clear skies and sunshine this
afternoon, with many areas warming into the 30s. Mostly clear skies
should continue into tonight as high pressure drifts south of the
area. This should allow temperatures to drop into the lower 20s for
much of the area, and perhaps even the low teens across the
favored cold bog areas of central Wisconsin as the boundary layer
decouples there overnight.

Quiet weather looks to continue for Saturday, with many areas
topping out in the upper 30s to mid 40s under partly cloudy to
mostly sunny skies.  Any clouds we do see should be mainly high
clouds associated with a shortwave trough passing overhead Saturday
morning. Low levels remain dry and precipitation is not expected
out of this feature.

.LONG TERM...(Saturday night through Friday)
Issued at 158 PM CST Fri Nov 22 2019

Pleasant late November weather will continue through the remainder
of the weekend. A couple weak mid-level shortwaves will drop through
the Upper Mississippi Valley Saturday night into Sunday, but dry low
levels should preclude anything more than some periodic mid and high
clouds. H8 temperatures approaching 5C or slightly higher on Sunday
will translate into another warmer-than-normal day with highs
largely in the 40s, perhaps upper 40s in a few locations. Sunday
night into Monday a surface low is progged to trek across southern
Ontario. This track looks to be far enough to our north to keep the
forecast area dry, so have significantly trimmed back or removed
precip chances across our northern zones. However, the system will
drag a cold front through the region, ushering in a return to colder
conditions for the rest of the week.

Main focus of this period remains a pre-Thanksgiving storm system
that looks to lift somewhere through the region Tuesday into Tuesday
night. Confidence remains low in specific forecast details/impacts,
but the latest suite of guidance finally looks to be coming into
some consensus on a potential storm track. A potent mid-level wave
will cross the Rockies Monday night, inducing a developing Colorado
low that is progged to eject towards the Great Lakes on Tuesday.
While there remains some noticeable spread amongst deterministic
solutions and GEFS/EPS members, the 22.12Z model suite seems to be
coming into general agreement for a track roughly from somewhere in
the vicinity of St. Louis to Chicago, give or take ~50 to 100 miles
north or south. To put it plainly, confidence is increasing in a
storm system impacting pre-Thanksgiving travel across a portion of
the Midwest Tuesday through Tuesday night, but being several days
out exact precipitation types/amounts and resultant impacts have yet
to be pinned down. Locally, it looks like the deformation zone will
keep the bulk of precipitation generally along and south of
Interstate 90. The current expected colder system track would favor
snow within the forecast area, perhaps mixed with rain in our
southern zones, but it`s much too far out to delineate where the
rain/snow line will lie. Above all, it must be stressed that the
forecast will continue to be refined over the next few days as
models come into better agreement. Those with early holiday travel
plans will need to keep close tabs on the regional forecast for
inevitable changes.

Those planning to travel on Wednesday look to have more favorable
weather as surface high pressure drifts eastward across the region
with dry conditions. Southerly return flow and warm air advection
will develop in its wake on Thanksgiving Day, bringing small precip
chances through Friday, perhaps in the form of a light wintry mix.
Again, low confidence being this far out in time.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 448 PM CST Fri Nov 22 2019

VFR conditions are expected through Saturday afternoon. An area of
high pressure centered over northern Missouri will move off to the
east overnight allowing a weak front to slip through the region
Saturday. With a dry atmosphere in place, only a few high clouds
are expected with the passage of the front. Winds will switch from
the south to the west with the front with some gusts to around 20
knots expected at KRST.




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