577
FXUS63 KARX 281915
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
215 PM CDT Tue May 28 2024

.KEY MESSAGES...

- Maybe some patchy to areas of fog tonight and Wednesday night.

- Periodic shower and storms chances from Thursday night into
  Week 2. Overall severe weather chances look low through
  Sunday.

- Below to near normal temperatures into Thursday and then near
  to above normal into week 2

&&

.DISCUSSION...
Issued at 215 PM CDT Tue May 28 2024

Remainder of This Afternoon and Evening - Periodic showers and
storms

The combination of cyclonic flow aloft and steep 950-800 mb (8-9
C/kg) lapse rates will produce periodic showers and storms this
afternoon and evening. Soundings show that there will be
potential for hail up to nickles and gusty winds up to 30 mph.

Overnight Tonight through Thursday Evening - Mainly Dry

A Canadian high pressure system will build gradually southeast
into the region tonight. This high will be overhead on Wednesday
and then drift east of the area on Wednesday night and Thursday.
Other than a few members of the GFS that produce scattered
showers across Wisconsin on Wednesday afternoon, it looks dry.

With the low level moisture and light winds being rather shallow
overnight tonight, we are not expecting too much fog tonight. If
it does develop, it is expected to be shallow and it should
dissipate rapidly after sunrise.

On Wednesday night, the soundings show a much deeper layer (up
to 700 mb) of light winds. While wind profile is favorable for
the development of fog, the moisture profile is not that
favorable, so like tonight not expecting too much fog.

Temperatures will be cooler to near-normal.

Late Thursday Night into Next Week - Periodic Showers and Storms

The 500 mb flow becomes zonal across the northern US. Embedded
shortwave in this flow pattern will bring periodic showers and
storms. Colorado State severe weather probabilities are showing
probabilities less than 5% through Sunday and then increases
into the 5 to 15% range for Monday and Tuesday.

With the zonal flow keeping the cooler air north of the area,
we are looking at temperatures near to above normal.

Days 8 to 14 - Periodic Showers and Storms Persist

Many of the ensembles are in agreement that a strong and
amplified 500 mb ridge will develop. The ECMWF ECE keeps this
ridge mainly over the western US. Meanwhile, the Canadian
ensemble has this ridge over the Northern Plains and western
Great Lakes. The GEFs is in between these 2 solutions. With a
majority of the ensemble members keeping this ridge west of
area, it looks like we will likely see northwest flow aloft.
Embedded shortwave troughs in this flow will likely keep a risk
for periodic showers and storms for this time period.
Temperatures will remain near to above normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 635 AM CDT Tue May 28 2024

Valley fog early this morning has brought 0 SM to KLSE and LIFR
at other smaller Mississippi River Valley airports. Showers
sagging southeast through Minnesota early this morning. VFR
ceilings have been observed but with cold air advection expect
some lowering. Therefore, have kept a pessimistic forecast.
Thunder possible with passing storms from northwest to southeast
later this morning through the afternoon. Storms linger east of
the Mississippi River into tonight. Low confidence for lifting
out of MVFR, so have kept it given the ongoing pattern. Forecast
models suggest another round of fog Wednesday morning but an
incoming dry airmass has its doubts. Will be subsequent forecast
detail after storm chances.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...JAR