732
FXUS63 KARX 070304
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1004 PM CDT Sat Jul 6 2024

.KEY MESSAGES...

- Intermittent showers/storms are possible through the middle of the
  coming week, although most hours will be dry. Overall, the
  risk for organized heavy rain/severe weather is low.

- Temperatures likely will remain near to below average through
  much of the coming week, possibly warming back above average
  towards next weekend.

- The Mississippi River is near crest south of La Crosse to
  Guttenberg, IA, and is slowly falling to the north. By early
  next week, falling river levels are expected along the Upper
  Mississippi River from southwest WI/northeast IA northward.

&&

.DISCUSSION...
Issued at 145 PM CDT Sat Jul 6 2024

This Evening - Sunday:

Broad mid-level troughing persists from the northern Plains through
the Great Lakes this afternoon. GOES water vapor imagery showed an
embedded shortwave across the northern plains, which will slowly
progress into Minnesota over the coming day. Regional radar mosaics
showed areas of showers/storms in association with this wave across
the Dakotas into Minnesota as of early afternoon.

Late this afternoon, lift is quite nebulous, but as inhibition is
eroded, a small (10%) chance for a shower/storm exists, with the RAP
indicating 1000-1500 J/kg MLCAPE from southeast MN into north-
central WI. Heading into tonight and Sunday, modest moisture
transport/warm advection ahead of the trough will spread across the
area, with an attendant increased chance for showers/storms. With
instability waning as rain approaches later this evening/tonight,
expect showers and subsevere storms. Additional scattered
storms are possible later Sunday/Sunday evening ahead of a weak
boundary approaching from the northwest as weak inhibition is
eroded by daytime heating. Although flow fields will increase
relative to today, overall, modest instability (SBCAPE 1000-1500
J/kg) should be a mitigating factor for stronger storms, but
gusty winds/small hail could not be ruled out with a few storms.
Given the lack of deeper moisture and instability, the
potential for heavy rains is limited, but any slower moving
storms could produce localized amounts of 1 inch or more.

Monday - Saturday:

Weak mid-level troughing will persist through the first half of the
work week across the Upper Mississippi Valley, keeping the region in
a seasonably cool temperature regime. Additional showers/storms will
remain possible (30-50%) on Monday, highest chances across
Wisconsin near and ahead of the weak boundary. Additional
showers/storms, primarily diurnal in nature, will be possible
(20-50%) through mid- week given the weakly cyclonic mid/upper
flow atop seasonable boundary layer moisture. With weak flow
aloft, the risk for severe storms in this pattern looks quite
low. Also, similar to this weekend, organized heavy rainfall
potential is also low, but localized heavier rain amounts cannot
be ruled out in slow-moving storms.

Gradually building mid-level heights are forecast later in the week.
As this occurs, temps should trend upward late in the week into
next weekend, while rain chances trend downward (10-30%).

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1001 PM CDT Sat Jul 6 2024

Probability for showers and perhaps a bit of thunder continues
to trend lower at RSE/LSE overnight. Have therefore removed the
SHRA mention at LSE and continued to refrain from thunder
mentions. Moving ahead to Sunday afternoon, continue to see a
good signal in guidance for MVFR cumulus development and have
therefore placed this into the TAFs for a few hours at each
site. A shower or thunderstorm may develop out of this cumulus,
but probability remains too low for a mention with this update.

&&

.HYDROLOGY...
Issued at 145 PM CDT Sat Jul 6 2024

The Mississippi River is near crest south of La Crosse and has
been falling from near La Crosse and points north. By early
next week, Mississippi River stages will begin falling across
northeast Iowa/southwest Wisconsin.

Off and on shower/storm chances are expected tonight and Sunday
which could yield additional rainfall amounts of 0.1" to 0.25"
with localized higher amounts. An unsettled pattern is expected
to persist through the first half of next week, but rain amounts
are generally expected to remain light. That said any thunderstorms
could produce localized higher amounts over 1".

&&

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

&&

$$

DISCUSSION...JM
AVIATION...Ferguson
HYDROLOGY...Naylor