921
FXUS63 KARX 050731
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
231 AM CDT Sat Jul 5 2025

.KEY MESSAGES...

- Periods of showers and storms throughout the day today. Heavy
  rain and strong wind gusts will be the primary hazards with
  any stronger storms.

- Seasonable temperatures expected for the upcoming week with
  highs in the upper 70s to middle 80s.

- Additional off and on storm chances (20-40%) throughout much
  of upcoming week.

&&

.DISCUSSION...
Issued at 231 AM CDT Sat Jul 5 2025

Today: Periods of Showers and Storms

GOES-19 water vapor imagery and 05.06z RAP 500mb heights shows the
mid-level pattern fairly nicely early this morning with a pronounced
mid-level shortwave situated just to our west with yesterday`s
ridging pushing eastbound. As this 500mb wave pushes eastbound,
expecting the attending surface cold front to begin to move towards
the region. This along with some Q-vector convergence in the mid-
levels will aid in developing some scattered showers for the morning
hours and again during the afternoon/evening as the main cold front
progresses from west to east across the local area. Confidence is
fairly high for amounts of 0.5" across the much of the area as the
05.00z HREF has high probabilities (40-80%) for amounts in excess of
this through Saturday night. However, higher amounts of 1-2" or
greater will be possible (20-50% in the 05.00z HREF) where storms
frequent as storm motions will be fairly slow.

As for any severe potential, instability profiles are fairly skinny
with only around 1000-2000 J/kg of MLCAPE across much of the area.
Consequently, relatively weak parcel acceleration will keep from
rapid storm development. Additionally, weak flow aloft and near the
surface will keep 0-6km bulk shear values to a minimum which in turn
should keep storm organization to multi-cellular to perhaps
linear as the cold front pushes through the area later into the
afternoon and evening. Therefore, expecting virtually no hail
threat with these storms and really only thinking that some
strong wind gusts may be a possibility with any more vigorous
storm cluster/linear segments given the higher precipitable
waters to around 1.75-2.5".

Sunday & Next Work Week: Seasonable with Storm Chances

In the wake of the mid-level shortwave for Sunday, weak subsidence
behind the aforementioned wave will enable clearing skies with
seasonable temperatures for the day on Sunday with highs generally
in the upper 70s to middle 80s with brief northwesterly flow in
place. As we begin the upcoming work week, quasi-zonal upper-level
flow will return to the region with occasional shortwave passages
throughout the week. The first of these approaches the area later on
Monday and into Tuesday. Overall, confidence seems fairly
respectable that some measurable precipitation will occur in the
local area with the grand ensemble (GEFS/EC/Canadian ensemble)
having high probabilities (60-90%) for measurable precipitation
with lower confidence on exact coverage. Consequently, have
held with the lower NBM probabilities during this time range
until coverage details can be refined.

As we head past Tuesday for the upcoming week, the upper-level flow
pattern turns slightly more northwesterly as some upper-level
ridging develops over the western CONUS. Regardless, still expecting
some pieces of shortwave energy to sneak through the flow resulting
in some low-end precipitation chances throughout the week, however
ensemble guidance struggles to pinpoint any specific window for
higher confidence. Consequently, there remains vast uncertainty on
any severe potential for the upcoming week until any shortwave
perturbations can be resolved, as is typical for this time of
year. In any case, temperatures will likely remain on the
seasonable side with relatively steady-state flow throughout the
course of next week with highs in the upper 70s to middle 80s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1228 AM CDT Sat Jul 5 2025

Period of rainfall, associated MVFR conditions, and potential TS
arrives Saturday morning and looks to persist into the late
afternoon and early evening. While there is high confidence in
MVFR conditions being present, timing of TS at any given point
is less certain. Have therefore included multi hour PROB30
groups to illustrate the thunder potential. Future issuances
will focus on narrowing these periods of TS mentions.

&&

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

&&

$$

DISCUSSION...Naylor
AVIATION...Ferguson