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000
FXUS63 KARX 100326
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1026 PM CDT Tue Apr 9 2024

.KEY MESSAGES...

- Isolated showers possible mainly north of Interstate 90 from
  this afternoon into this evening.

- From Wednesday Night into Thursday Night, there will be
  additional showers possible with the highest rain chances on
  Thursday and Thursday evening.

- From Saturday through Monday, temperatures will range from 10
  to 20 degrees warmer than normal for Saturday through Monday.

- Rain chances return Tuesday.

&&

.DISCUSSION...
Issued at 147 PM CDT Tue Apr 9 2024

Late this Afternoon and Evening - Isolated showers possible
mainly north of Interstate 90

The 500 mb low will continue to slowly weaken and drift north
northeast across Ontario. With daytime heating, surface-based CAPES
may climb up to 50 J/kg late this afternoon and early evening ahead
of an approaching shortwave trough. The CAMs continue to generate
some isolated showers mainly north of Interstate 90. With a dry
subcloud layer below 825 mb, wind gusts may climb up to 30 mph in
these showers. High temperatures this afternoon will range from the
mid-50s to lower 60s.

Wednesday Night through Thursday Night - Additional showers
possible with the highest rain chances on Thursday and Thursday
evening

A northern stream shortwave trough will move southeast into the area
on Wednesday night. This will bring with it isolated to scattered
showers.

This trough then merges with a deepening low in the southern stream
over the Great Lakes on Thursday and Thursday night. This will
result in higher rain chances (50-80%) from Thursday into Thursday
night. Looking at the 100 ensemble members consisting of 50 ECMWF
ECE, 30 GEFS, and 20 Canadian ensemble members, a vast majority of
the members show low probabilities of a quarter-inch or greater. Out
of 4 clusters, only 1 of these clusters has high chances (40-70% in
southwest and central Wisconsin) for a quarter-inch of rain or more.
This cluster included 2/3rds of the ECMWF members, no GEFS members,
and just 5% of the Canadian. It had a stronger shortwave trough
which allows more moisture to propagate west into Wisconsin. The
remainder were less than 15% for the aforementioned rainfall amounts.

It continues to look like this system will be predominantly a rain
producer. Just 1 member in each of ECMWF ECE and GEFS produces
measurable snow in central and north-central Wisconsin.

High temperatures will be in the mid- and upper 60s on Wednesday.
With more clouds and colder 850 mb temperatures being advected south
on Thursday, high temperatures will be in the mid- and upper 50s.
This is close to normal.

Friday through Monday - 10 to 20 degrees warmer than normal for
Saturday through Monday

A 500 mb ridge continues to build and move east into the region.
However, this ridge is slower at moving east and less amplified.
This allows a shortwave trough to move southeast through the area on
Saturday night. This could result in some isolated showers. In
addition, the high temperatures will not be quite as warm. High
temperatures will range from the lower 60s to lower 70s on Saturday,
and from the mid-60s to mid-70s on Sunday and Monday. The
probabilities for lower to mid-80s has decreased to less than 10%
for Sunday.

Tuesday - Rain chances returns

A strengthening low pressure area will be moving northeast into the
Central Plains. There continues to be plenty of uncertainty on how
fast this occurs. Much of this uncertainty deals with how the upper
level moves east and breaks down. There are still 4 clusters among
the 100 ensemble members. 3 of these clusters contain 92 of the 100
members. These 3 clusters are nearly equally weighted (ranging from
24 to 36%) and have this low anywhere from southern California to
the Central Plains, so confidence remains low on the timing of when
this will occur.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1026 PM CDT Tue Apr 9 2024

VFR conditions expected for the TAF period. Light south to
southeast winds will continue through the overnight period
before shifting to southwesterly winds Wednesday morning. Some
CIGS, between 6kft and 10kft, will remain for areas mostly north
of I-90 for the next few hours. After these clouds move out, mostly
clear skies are expected until Wednesday morning when mid-level
clouds move into the area.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Cecava