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000
FXUS63 KARX 221939
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
239 PM CDT Mon Apr 22 2024

.KEY MESSAGES...

- Periodic rain chances from this afternoon through Tuesday
  evening and from Thursday night into Monday. There may be some
  strong storms on Friday afternoon into Friday night.

&&

.DISCUSSION...
Issued at 238 PM CDT Mon Apr 22 2024

Tonight - Scattered showers and slackening winds

The 22.12z deterministic models are in good agreement that a weak
northern stream shortwave will move east through the region. This
wave is ahead of a longwave moving southeast through the
Dakotas. There will be scattered light rain showers this
evening. Rainfall amounts will range from a trace to a couple of
hundredths of an inch.

Soundings continue to show a dry sub-cloud layer below 800 mb. As a
result, there will likely be some evaporation of the rain from these
showers. This may result in some wind gusts of 30 to 40 mph through
10 PM.

Tuesday and Tuesday Evening - Scattered showers and storms

A broad longwave trough will move east southeast through the Upper
Mississippi River Valley. This wave will produce more synoptic lift.
This will result another round of showers for the area. Rainfall
amounts will be up to a tenth of an inch. Surface-based CAPES will
climb up to 250 J/kg. In addition with cold air aloft, 950-700 mb
CAPES will exceed 8 C/km. This will result in some isolated to
scattered storms. A dry sub-cloud layer will help translate wind
gust of 25 to 35 mph downward to the surface. In addition with the
skinny CAPES aloft, there may be even some small hail with the
stronger storms. High temperatures will range from the upper 50s to
mid-60s.

Thursday Night into Saturday - More Showers and Storms - Some may be
strong

While the models are in good agreement that a southern stream
shortwave trough will eject out of the western broad longwave
trough and it will bring showers and storms into the Upper
Mississippi River Valley, there is plenty of uncertainty on the
track of the surface low. This will greatly impact on far north
the warm sector will get This in turn will impact our chances of
severe weather. The SPC Outlook for Friday and Friday night
(Day 5) has its 15% risk of severe weather just south of of our
area. The 22.13z NBM has a 30- 50% probability of rainfall
greater than 1 inch. Due to this heavy rain, WPC has a marginal
risk for heavy rain.

Saturday night into Monday - Another round of showers

Another shortwave will be ejecting out of the western longwave
trough. With the front being pushed further southeast, this will
keep the warm sector well to our southeast. As a result, not
expecting any severe weather from this system. In addition, the risk
for heavy rain is further southeast. The 22.13z NBM has a
probability of 1 inch up to 25% north of Interstate 90 and 25 to
50% for the remainder of the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1156 AM CDT Mon Apr 22 2024

VFR conditions will persist through this TAF cycle with a period
of mid-level ceilings later this afternoon into early and
scattered light showers (30-60% chance). Southerly winds
gusting 25 to 35 kts will diminish and become westerly overnight
behind a front. A brief period of low-level wind shear could
occur this evening if surface winds slacken before the low-level
jet moves east. Additional scattered showers/isolated storms
are possible Tuesday afternoon, with the higher chances across
parts of Wisconsin. Winds will become gusty from the west to
northwest behind a secondary front on Tuesday.

&&

.FIRE WEATHER...
Issued at 400 AM CDT Mon Apr 22 2024

Ahead of a cold front today, a dry airmass is in place with
strengthening southwest winds and warming temperatures into the
60s. Lowest relative humidity values drop to 20 to 30 percent
through mid afternoon, then improve with increasing rain
chances. Fuels have increased with some drying over the last
couple of days and the warmer temperatures today. Due to the
strong winds developing from the southwest with gusts 30 to 40
mph, burning should be avoided due to the elevated fire weather
conditions.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Advisory until 5 PM CDT this afternoon for MNZ086-087-094-
     095.
IA...Wind Advisory until 5 PM CDT this afternoon for IAZ008>010-018-
     019-029.

&&

$$

DISCUSSION...Boyne
AVIATION...JM
FIRE WEATHER...Zapotocny