000
FXUS63 KARX 101827
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
127 PM CDT Wed Apr 10 2024

.KEY MESSAGES...

- Isolated showers tonight and showers and scattered storms on
  Thursday and Thursday night. Highest chances (40-80 percent)
  on Thursday afternoon.

- Northwest wind gusts in the excess of 30 mph from Thursday
  night into Friday.

- Well above-normal temperatures (15 to 20F) this weekend.

- Maybe some severe weather chances from Monday into Tuesday.

&&

.DISCUSSION...
Issued at 127 PM CDT Wed Apr 10 2024

Tonight - Small chance (less than 25%) of showers

A northern stream 500 mb trough will move east into the Upper
Mississippi River Valley. The CAMs continue to show that this
trough will bring with it isolated showers. Rain chances will
be up 25%. Rainfall totals will be up to 5 hundredths of an
inch. Low temperatures will be in the lower and mid-40s.

Thursday and Thursday Night - Showers and scattered storms

A northern stream shortwave trough will merge with a stronger trough
in the southern stream over the Great Lakes. The CAMs and 10.12z
deterministic models have trended further west with the better
moisture and instability. The 10.12z HREF precipitable water values
range from 0.5 to 0.6 inches and mean surface CAPES range from 150
to 250 J/kg. The highest values are along and east of the
Mississippi River. Due to this kept the isolated to scattered storms
in the forecast along east of the Mississippi River on Thursday
afternoon and evening. The 0-6 km shear quickly weakens during the
afternoon and remains weak during the evening. As a a result, not
anticipating severe weather. 10.12z HREF has a mean 24-hour
precipitation of around a half-inch in central Wisconsin. These mean
totals rapidly decrease as you head further west. For much of the
remainder of the forecast area, rainfall totals are mainly less than
a tenth of an inch.

With more clouds and colder 850 mb temperatures being advected south
into the region on Thursday, high temperatures will range from the
mid-50s to lower 60s. This is close to normal.

Thursday Night into Friday Night - Wind gusts in the excess of
30 mph

The surface pressure gradient tightens across the area on
Thursday Night as the surface low continues to tightens as it
moves northeast into Ontario and high pressure begins to build
east into the Upper Mississippi River Valley. This will result
in some stronger winds. Many of the GEFS and ECMWF have wind
gusts during the day in the 30s. The 10.13z NBM has up 20%
probability that the wind gusts could exceed 40 mph across Adams
and Juneau counties in central Wisconsin. This gradient then
gradually weakens in the afternoon and evening as the low move
moves northeast through Quebec.

High temperatures will range from the mid-50s to lower 60s.

This Weekend - Temperatures 15 to 20F warmer than normal

A southern stream 500 mb ridge will move gradually east into the
region. Meanwhile, the northern stream will be zonal along the
US/Canadian border. This might allow for some small rain chances
(less than 30%) on Saturday night and Sunday morning, but confidence
remains low (less than 30%).

High temperatures will range from the mid-60s to mid-70s on Saturday
and from the upper 60s and upper 70s on Sunday. The 10.13z NBM has
the probabilities of 80F or warmer high temperatures anywhere from a
15 to 50% probability on Saturday and 15 to 30% probability on
Sunday.

Monday and Tuesday - Severe weather possible

A strong southern stream trough and deepening low pressure system
will be lifting out of the southwest US. Like the past couple of
days, there is quite a bit of uncertainty on the timing of when this
shortwave trough will move through the region and the track of the
surface low. A further west track would greatly enhance our chances
of seeing severe weather from this system. Meanwhile, a further
east track would keep the severe weather south and east of our
area. On Monday, CIPS Experimental Analog has a 10-20%
probability of severe weather in northeast Iowa and CSU-MLP has
5-15% probability for much of the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1140 AM CDT Wed Apr 10 2024

CIGS: increasing mid level VFR deck tonight. Expect lowering moving
through Thu morning as low saturation tied to weather systems in
both the northern and southern portions of the flow start to
influence the local area. Could see a drop into MVFR for a few hours
late morning/early afternoon Thu, with medium range guidance
favoring another period for Thu night.

WX/vsby: a smattering of -shra as we move into tonight. Any shower
likely falls from a mid deck, battling a lot of dry air in the sub
cloud layer. Any light pcpn will have a challenging time reaching
the sfc. Not enough coverage to warrant inclusion into the forecast
at this time. CAMS models and medium range guidance produces more
widespread showers for Thu afternoon/evening with higher chances (40-
70%) to impact the TAF sites. Isolated storms possible (10-20%).

WINDS: west/southwest becomes more light/vrb tonight...then
increasing early Thu as the pressure gradient tightens with a low
pressure system off to the east. Sustained northwest near 20 kts and
gusts into the mid/upper 20s kts probable for Thu afternoon.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Rieck