266
FXUS63 KARX 141858
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
158 PM CDT Tue May 14 2024

.KEY MESSAGES...

- Maybe some patchy frost in central and north-central Wisconsin
  tonight. Far too low coverage to warrant a Frost Advisory.

- Periodic showers and storms into early next week. Highest rain
  chances from Wednesday night into Thursday night and from
  Saturday night into Sunday.

&&

.DISCUSSION...
Issued at 158 PM CDT Tue May 14 2024

Tonight and Wednesday

18z WV satellite shows an upper low over MO with latest surface obs
and 12z RAOBs showing easterly flow in the low levels. This has
largely ushered near-surface smoke from Canadian wildfires to our
southwest with no visibility reductions seen today. That said,
continued westerly flow aloft has allowed a light distant haze to
persist. Given flow pattern and latest guidance, expect the smoke
aloft to remain a factor through Wednesday. As sunset approaches
Wednesday, some near-surface smoke may return ahead of an
approaching trough, but confidence is too low for inclusion in the
forecast with this update. Otherwise, expect lows a bit below
average tonight given light winds and highs around average for mid-
May Wednesday afternoon.

Wednesday Night into Thursday Night

The 14.12z models are in good agreement that 2 northern stream
shortwave troughs will move east through the region. The first moves
through the region late Wednesday night and Thursday morning. 0-1 km
most unstable CAPES are generally less than 250 J/kg, and 0-3 km and
0-6 km shear remain weak; therefore, not expecting any severe
weather. Precipitable water values will climb to around 1 inch.
Rainfall amounts will generally range from a 0.25 to 0.50 inch.
There is less than a 10 percent chance that the rain will exceed a
half inch.

A second shortwave trough will move through the region on Thursday
evening. There appears that there will be enough clearing in between
these systems to allow the 0-1 km most unstable CAPES to climb up
500 J/kg. The highest values are primarily located in the eastern
portion of northeast Iowa and in Wisconsin. Like its predecessor,
both the 0-3 km and 0-6 km wind shear remains weak, so not expecting
any severe weather. However, with an inverted-V in the sub-cloud
layer, there will be likely some gusty winds associated with the
showers and storms. Wind gusts will be 20 to 25 mph. Rainfall
amounts will generally range from a 0.10 to 0.50 inch. There is less
than a 10 percent chance that the rain will exceed a half inch.

Weekend

The models are generally showing zonal (west-east) flow across the
northern US. There is a series of weak shortwave troughs embedded in
this flow. There continues to be timing issues with these systems.
As a result, there will be periodic showers and storms. Overall, the
best 0-3 km and 0-6 km shears are closer to the International border
and southern Canada, so not  any severe weather.

Early Next Week

The spread in the 500 mb pattern is increasing. While many models
are continuing to show zonal flow across the northern US. There are
some models suggesting that a 500 mb ridge will develop from the Mid
and Upper Mississippi River Valley northeast to Hudson Bay. Due to
this uncertainty has been growing, so stayed closer to the NBM
when it comes to both temperatures and precipitation.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1213 PM CDT Tue May 14 2024

VFR conditions are expected to prevail over the next 24 hours at
RST/LSE. A few MVFR cumulus clouds at or around 4 kft cannot be
ruled out this afternoon. Otherwise, only expect some hazy skies
due to smoke aloft from distant wildfires - visibility
reductions at the ground are not expected.

&&

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

&&

$$

DISCUSSION...Boyne/Ferguson
AVIATION...Ferguson