Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 121145
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
545 AM CST Sun Nov 12 2017

.SHORT TERM...(Today and tonight)
Issued at 316 AM CST Sun Nov 12 2017

09Z water vapor loop shows a well defined short-wave across
central SD. At the surface, an inverted trough extends from MO
into IA. Regional radars show widespread rains across much of IA
into IL with the northern extent of this precipitation impacting
the southernmost counties of the forecast area. Temperatures and
dewpoints have generally been steady between 32 and 34 degrees,
meaning rain should continue to be dominant p-type. That said,
could still see a few slick spots on cold untreated surfaces. This
rain will continue to move south and east early this morning,
exiting the forecast area by around 15Z.

Clearing skies north of I-90 may allow for areas of fog to
develop through sunrise, some of which could become locally
dense. Rochester and Austin, MN have flirted with 1/4 mile in fog
at times this morning, but increasing high clouds should help
limit additional fog development and reductions in visibility
across southeast MN.

For the rest of today, high pressure will build across the region.
Clouds across the south will slowly push east, although another
area of clouds currently across eastern ND and northern MN will
drop south across portions of the forecast area. While there could
be breaks of sun between these two cloud masses through the day,
partly sunny to mostly cloudy skies will be the rule. Afternoon
highs will top out in the mid 30s to lower 40s with light
northwest wind. Dry conditions will continue into tonight with
temperatures dependent on cloud cover. In general, most areas will
drop into the lower to mid 20s.

.LONG TERM...(Monday through Saturday)
Issued at 316 AM CST Sun Nov 12 2017

Surface high pressure drifts eastward on Monday, with southerly
return flow developing across the region. Skies will be partly
sunny with highs rising into the lower to mid 40s.

Low-level moisture advection and isentropic lift increase Tuesday
ahead of the next wave aloft. This could result in periods of
light rain or drizzle through the day, but with model soundings
showing no ice aloft, morning surface temperatures will need to
be watched closely for possible freezing impacts. Temperatures
warm enough into the afternoon for the p-type to be all rain.
Precipitation chances then increase further Tuesday night as a
surface cold front sweeps across the forecast area. Thermal
profiles continue to support rain, but deep layer moisture is
still lacking, so overall rainfall amounts will likely be on the
low-side, generally a tenth of an inch or less. Afternoon highs
Tuesday will top out in the 40s for most locations.

Dry conditions return Wednesday into Thursday with a progressive
surface high moving across the Upper Midwest. Temperatures in the
40s on Wednesday will drop a bit into Thursday with highs from the
mid 30s to lower 40s.

Still watching a strong Eastern Pacific trough for late in the
week. Model timing, strength, and placement differences persist
resulting in various surface low tracks and thermal profiles. Will
continue to follow a model consensus, keeping POPs generally in
the 30 to 70 percent range Thursday night through Friday. No
matter the model, the system looks to be east of the area by
Saturday, with a return to drier, but colder conditions.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 545 AM CST Sun Nov 12 2017

IFR conditions are expected in fog and low stratus early this
morning at KRST with visibilities reduced to less than 1 mile at
times. Brief MVFR conditions are expected in stratus at KLSE, but
most of the stratus should be scattered. Both sites will improve
to VFR by mid morning into the late morning hours but then we are
watching a broad area of MVFR stratus approach from the north.
This stratus deck is expected to stay north of KRST but could
impact KLSE this afternoon.

&&

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

$$

SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...Wetenkamp



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