651
FXUS63 KARX 161148
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
648 AM CDT Thu May 16 2024

.KEY MESSAGES...

- Showers and storms continue to push through the area this
  morning. Additional storms may develop east of the Mississippi
  River this early afternoon with some strong to marginally
  severe storms possible.

- Additional shower and storm chances spot the forecast through
  the weekend into early next week. Stay up to date with the
  latest forecast as detail continue to be refined.

- Temperatures increase into the weekend with highs in the 70s
  to low/mid 80s.

&&

.DISCUSSION...
Issued at 437 AM CDT Thu May 16 2024

Today - Tonight:

Current radar mosaic shows showers and thunderstorms moving across
the forecast area ahead of a surface boundary and approaching upper
level shortwave trough. By 3 AM local observations showed a few
locations picked up around 0.25 to 0.50". These showers and storms
will continue to push northeast/east through the area slowly
clearing west of the Mississippi River through the morning. However,
will be monitoring conditions through the day as hi-res guidance
shows some additional development east of the Mississippi River in
the early afternoon with the aforementioned shortwave and a trailing
piece of energy along with increasing moisture. As was mentioned
with the previous forecast, there will be some dependency on timing
and how much instability we can build through the day. Short term
guidance would suggest potential for SBCAPE to increase to around
1000-1500 J/kg, though there is some question on how quickly the
moisture axis may be displaced eastward. SPC has maintained a
marginal risk (1 of 5) for severe weather for portions of far
southwest into central Wisconsin where there may be a short window
this early afternoon for strong to marginally severe storms (main
threats hail 1-2", gusty winds with any storm) to develop before
pushing eastward by late afternoon.


Friday - Next Week:

Drier conditions look to follow for Friday before another system
moves through the region over the weekend. Warmer air moving in the
region ahead of this system will allow highs to increase into the
mid 70s to low/mid 80s Friday into the weekend. An upper level
shortwave trough is forecast to track across southern
Canada/Northern Plains Saturday with an associated surface front
swinging across the region. Ensemble solutions suggest a few showers
and perhaps storms developing late Saturday along the front, though
there appear to be some differences between individual ensemble
members on how much and even how far south showers and storms
develop.

Model guidance appears to be in good agreement in an upper level
trough across the western U.S. by the start the week. Multiple
rounds of shortwave energy look to eject from the mean trough
through the early start of the week. However, there remains lower
predictability in narrowing down details such as timing and
location of these waves and in turn developing surface features
with the extended forecast range. This is reflected with quite a
bit of variability in GEFS and ECMWF ens solutions through the
period. With this said, the current forecast would point towards
Sunday night into early Monday for the next chance for
increasing shower and storm chances. Will maintain blended model
guidance until further details can be refined, but a more
active period looks to be possible into early next week. Will
note that with these uncertainties temperature spread begins to
increase into the week as well. However, current signals in
guidance would suggest highs remain generally around and
slightly above the seasonable normals to start the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 643 AM CDT Thu May 16 2024

The bulk of the shower and thunderstorm activity has shifted to
the east with some lingering showers and drizzle gradually
working east early this morning. Re-development is currently
expected to remain east of the TAF sites after 15Z. Ceilings
are variable MVFR/VFR. Initially, forecasts for MVFR were 40 to
50%, however the latest RAP hi res RH progs are a little more
pessimistic. For now will include a mention of MVFR conditions
and then will improve conditions to VFR. Southeast to southwest
winds shifting to the west and northwest today 5 to 12kts wit
some gusts to 20kts for a time at RST.

&&

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

&&

$$

DISCUSSION...EMS
AVIATION...Naylor/Zapotocny