Area Forecast Discussion
Issued by NWS La Crosse, WI

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304
FXUS63 KARX 210731
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
231 AM CDT Mon Oct 21 2019

.SHORT TERM...(Today through Tuesday night)
Issued at 231 AM CDT Mon Oct 21 2019

GOES water vapor imagery/surface analysis showing a potent
closed/nearly vertically stacked low churning northeast out of NE
into southeastern SD. Occluded/cold front extending southward from
the low into western IA/MO into eastern OK. Well established
subtropical tap from the Pacific/Mexico ahead of the
low/occluded/cold front. This was in turn producing a fairly solid
line of convection with some of that now edging into portions of
northeast IA and northeast IA.

The low will continue to lift northeast into southern MN today and
then into northern WI tonight. CAMs show band of showers/scattered
storms lifting fairly rapidly across our area this morning with the
dry slot of the occluded low moving in from north to south by this
afternoon. Rainfall could be locally on the heavier side as this
band of showers/storms lifts through this morning with amounts
generally in the 1/2 to 1 inch range. Depending on how much clearing
we get in this dry slot behind the frontal passage will determine
how warm we get today. Thinking right now this won`t be a totally
clean dry slot, so going with mid 50s to lower 60s.

Wrap around moisture/deep cyclonic flow will continue showers int
Tuesday. Of more concern will be gusty westerly winds on the
backside of the departing deep 988mb low moving into southern
Ontario. Sustained wind will be in the 25-30 mph range with gust 35
to 45 mph. As such, may need to hoist a Wind Advisory for Tuesday.
Will pass this onto the dayshift for further assessment. Otherwise,
a chilly/blustery day on tap with highs only in the mid 40s to lower
50s.

Winds trail off but remaining rather gusty through Tuesday night as
the low pulls further northeast into Ontario Canada. May still see
some lingering showers activity across northern WI/north of I-94 in
the evening while partial clearing takes place through the remainder
of the night. Look for lows in the low to mid 30s.

.LONG TERM...(Wednesday through Sunday)
Issued at 231 AM CDT Mon Oct 21 2019

A mid-level trough and weak surface low in northwest flow aloft
ripples southeast through the area Wednesday/Wednesday night,
producing a chance of rain. Some of this precipitation may be a
rain/snow mix at the onset Wednesday morning and later Wednesday
night on the trailing end. Otherwise, looking at a mostly cloudy day
with highs in the 40s/lower 50s. Lows Wednesday night are expected
to be in the 30s.

Thursday through Saturday look quite as high pressure establishes
itself over the central CONUS. Remaining fairly chilly through
Thursday/Friday with highs in the 40s. A little warmer toward normal
highs Saturday, topping off in the upper 40s to middle 50s.

Low pressure moving eastward through Canada will bring a cold front
into the region Saturday night into Sunday for a chance of showers.
Look for near normal highs Sunday in the upper 40s to middle 50s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1155 PM CDT Sun Oct 20 2019

A challenging and changeable set of weather conditions expected
the next 24+ hours, as strong low pressure takes shape across the
region. Showers are already noted working north toward RST and
will overspread much of the area through sunrise and beyond, with
current VFR conditions decreasing to MVFR and even briefly IFR in
heavier periods of rain, with a few thunderstorms also possible.
During that heavier rainfall, low level wind shear also becomes an
issue for all areas with a strong 50 knots of wind near 2k ft.
Rain and wind then quickly decrease for a time into midday and
early afternoon, with a return to VFR conditions expected, and
potentially even some clearing for an hour or two, before
additional showers (maybe some t-storms?) redevelop into later
afternoon and especially the evening. During that period, much
lower ceilings will spread back in from the west, with many areas
well into IFR or low-end MVFR range by 06Z Tuesday or just
beyond.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION...Lawrence



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