169
FXUS63 KARX 061052
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
552 AM CDT Sun Jul 6 2025

.KEY MESSAGES...

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

- Shower and storm chances (30-60%) for Monday night and Tuesday
  with the probability for strong to severe storms being very low
  at this time.

- Additional chances (45-65%) for showers and storms on Friday.

&&

.DISCUSSION...
Issued at 245 AM CDT Sun Jul 6 2025

Today - Tuesday: Dry & Seasonable for Today, Precipitation Chances
Return Overnight Monday and into Tuesday

GOES-19 water vapor imagery and 500mb heights in the 06.06z RAP
display our shortwave moving east of the local area early this
morning allowing for some briefing ridging to move in behind for
today. Aside for some areas of fog into the early morning hours this
morning, expecting dry conditions with partly cloudy skies as some
diurnal cumulus develops near peak heating for today. Additionally,
with northwesterly flow behind the cold front that passed through
the area yesterday, temperatures will be fairly seasonable with
highs in upper 70s to middle 80s. So should be a fairly nice day
outside for the final day of the holiday weekend!

For Monday, quasi-zonal flow will keep our temperatures fairly
steady as highs remain in the upper 70s to middle 80s. Deterministic
guidance generally agrees on bringing a shortwave trough into the
region though by Monday night and into Tuesday with increase
precipitation chances along with it. Currently, the recent grand
ensemble (GEFS/EC/Canadian ensemble) has high probabilities (50-80%)
for rainfall amounts over 0.1" from Monday night into Tuesday
which is trending more consistent with the NBM as it has been
increasing its precipitation chances over the last few cycles.
Overall, seems that the current favored timing across ensemble
guidance keeps the precipitation moving through during the
morning and early afternoon hours on Tuesday. Consequently,
instability appears fairly limited with only medium
probabilities (30-60%) for surface based CAPE over 1000 J/kg in
the grand ensemble (GEFS/EC/Canadian ensemble) across the area
on Tuesday. This coupled with generally weak flow aloft and
meager 0-6km bulk shear values in the 06.00z NAM/GFS would
indicate that the probability for organized severe weather with
this wave would seem low which much of the AI/Machine-learning
severe outlook guidance tends to agree with at this time.
Regardless, certainly seems like our next robust chance for any
rainfall.

Wednesday - Saturday: Remaining Seasonable, Additional Storm Chances

Upper-level flow turns marginally more northwesterly by mid-week as
some upper-level ridging begins to build over the western CONUS. As
a result, will have to watch mid-week to see if any subtle shortwave
perturbations manage to sneak through the flow but as of right now
guidance is not highlighting any features for the Wednesday-Thursday
period. The next tangible feature of note moves into the area by
Friday in the form of a more robust shortwave trough that descends
from south-central Canada and into the Northern Plains. Overall,
probabilities for 0.1" or greater of rainfall with this wave are
respectably high (60-70%) in the grand ensemble with the passage of
this wave. Consequently, thinking that likely mentions within the
NBM on Friday seem appropriate with the main point of uncertainty
being exactly how this wave orients itself, still remains some
timing and amplification questions within deterministic/ensembles
members. Either way, with little change to the synoptic flow pattern
throughout the week, guidance favors keeping temperatures steady-
state throughout the week with highs in upper 70s to middle 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 545 AM CDT Sun Jul 6 2025

MVFR/IFR ceilings - and FEW/SCT coverage - abound at issuance
time. Current thinking is that these will slowly erode over the
next few hours this morning as sporadic ceilings eventually give
way to consistent VFR conditions. Guidance signal remains mixed
for stratus and/or fog after 06z so have continued to leave
mentions out with this issuance.

&&

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

&&

$$

DISCUSSION...Naylor
AVIATION...Ferguson