605
FXUS63 KARX 100310
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1010 PM CDT Mon Sep 9 2024

.KEY MESSAGES...

- Tuesday brings a small (10-20%) chance for a light shower to
  a good portion of the area with these showers bringing
  potential for sporadic gusty winds.

- Warm and dry conditions with smoke aloft for the remainder of
  the work week.

- Low (10-20%) potential for tropical moisture advection from
  Francine to result in precip this weekend.

&&

.DISCUSSION...
Issued at 226 PM CDT Mon Sep 9 2024

Tuesday: A Few Showers and Sporadic Gusty Winds

19z WV satellite shows subtle upper ridging over the upper midwest
with quasi-zonal flow aloft extending from the Dakotas westward to
the Pacific Northwest. Embedded within this flow is a shortwave
moving eastward over NE/SD with this kicking off a few sporadic
light showers. With progged soundings suggesting saturation will
occur above around 600mb ahead of this wave, should get a few
sporadic showers across the area Tuesday.  Main limiting factor for
rain potential will be the increasingly dry low levels which should
result in many locations only seeing virga or very minor amounts.
This outcome is borne out in the 09.12z HREF which shows most areas
north of a line defined by the IA/MN border having a 10 to 45
percent chance for at least 0.01" but the probability for greater
than 0.10" in this same area is 10 percent at the very best. Only
potential hazard with this light shower threat would be gusty winds
given the aforementioned low level dry conditions within a pretty
well mixed boundary layer.

Remainder of Work Week: Warm, Smoky, and Dry

Wednesday through Friday look to feature highs in the mid to upper
80s, around 5 to 10 degrees above normal as an upper ridge builds
over the western Great Lakes. A few spots could presumably reach
90 Thursday, with some locations in the MS and WI river valleys
having NBM probabilities to reach 90 degrees of 40 to 70
percent. Unfortunately for the fans of the 90s, smoke from
wildfires in the northwestern CONUS looks to arrive Tuesday and
should stick around through at least Wednesday/Thursday,
limiting insolation. Have thus largely kept sub-90
deterministic NBM highs despite some probabilistic data and the
overall weather pattern sans smoke suggesting these may be a bit
underdone.

Weekend: Tropical Moisture Potential

Majority of guidance brings the remnants of newly christened
Tropical Storm Francine to the mid-Mississippi Valley sometime
between late Friday and next Monday. While plenty of moisture may
reach our CWA, other upper level features do not appear to
supportive of generating the robust lift needed for widespread
precipitation to occur. Nevertheless, should this moisture reach the
forecast area, any showers that manage to develop would bring a risk
for locally heavy rainfall given the modified tropical air mass that
would be in place. Given uncertainty about multiple elements -
timing, available moisture, and forcing for ascent - 10 to 20 PoPs
are spread across Saturday through Monday for now.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1010 PM CDT Mon Sep 9 2024

VFR conditions are forecast through the TAF period, with SCT-
BKN mid to high level clouds increasing across the area. Models
continue to show echoes developing and cannot rule out some
areas seeing a few sprinkles/showers. However, as mentioned
before, dry lower levels may be a limiting factor to
coverage/amounts of any rain. South winds increase into the day,
with increased wind gusts around 20 kts possible. Otherwise,
smoke aloft will continue to be noted across the region, but
impacts to visibility look less likely at this time.

&&

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

&&

$$

DISCUSSION...Ferguson
AVIATION...EMS