946
FXUS63 KARX 090013
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
713 PM CDT Mon Jul 8 2024

.KEY MESSAGES...

- Pattern will feature isolated to scattered shower and storm
  chances over the next few days.

- High temperatures remain in the upper 70s to lower/mid 80s
  through the week, but an increasing trend looks likely into
  the weekend. Some locations could reach towards 90F.

&&

.DISCUSSION...
Issued at 203 PM CDT Mon Jul 8 2024

This Afternoon - Mid-week:

Continuing to monitor a few showers and storms ongoing across
portions of the forecast and surrounding areas this early afternoon.
SPC mesoanalysis suggests about 1000 J/kg of MLCAPE with 20-25 kts
of effective shear. With this, isolated to scattered shower chances
will continue to increase into the late afternoon and evening.
Overall, the threat for severe weather looks low, but with any
stronger storm some small hail and gustier winds cannot be ruled
out. While a widespread heavy rain is not expected, localized
amounts of 1 to 2" could be possible under any slow moving or
training storms. Otherwise, showers and storms should begin to
diminish with the loss of daytime heating.

The area remains under broad cyclonic flow with various shortwaves
moving through. This keeps shower and storm chances in the forecast
each day through at least mid-week. The remnants of Beryl will be
lifting northeast towards the Lower Great Lakes through Wednesday,
but ensemble guidance right now favors keeping any heavier rainfall
from this system to our southeast. Another shortwave follows behind
it on Wednesday with increasing shower and storm chances (25-45%).
However, there is some uncertainty with how quickly this moves
through the area, with potential to keep a few additional low shower
and storm chances for some Thursday if a slower solution is
realized.

End of the Week - Weekend:

Model guidance continues to indicate increasing heights as a mid-
level ridge builds over the CONUS. There are signals for
additional disturbances to ride the periphery of the ridge
centered over the Rockies. Shower and storm chances may be
possible with increasing moisture and instability. However,
there is quite a bit of variability/low predictability with the
placement and timing of any embedded shortwaves and in turn it
is hard to pin down exact details. For now, this is reflected in
the lower chances (20-30%) from the blended guidance for the
weekend.

Otherwise, this pattern looks to favor increasing temperatures for
the region into the weekend. Guidance is starting to hone in with
low spread (<= 5 degrees F) shown between the 25th and 75th
percentiles. High temperatures are forecast in the mid to upper 80s
for most, but NBM probabilities for 90F increase to 20 to 60% across
portions of northeast Iowa and southwest Wisconsin and as high as 60-
80% for areas within the Mississippi River Valley by Sunday. This
with increasing dewpoints into the upper 60s to 70s will make a
noticeable difference in how it feels outside.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 707 PM CDT Mon Jul 8 2024

Ongoing scattered thunderstorms have remained east of both TAF
sites (KLSE & KRST) from northeast Iowa into central Wisconsin.
KLSE has higher chance of seeing VCTS but with very low
confidence, have abstained from including in TAF at this time.
Continuing to monitor through the evening hours as storms
expected to wane post sunset.

Fog potential returns along river valleys tonight. Highest
confidence remains in the Wisconsin River Valley with lesser
confidence elsewhere. Last night remained 10SM at KLSE as off
deck winds provided sufficient mixing while cloud cover kept
surface temperatures away from saturation. Have continued
previous forecast (08.18Z) as still expect low level winds to
weaken in a short window, potentially concurrent with decreased
cloud cover. Again, moderate confidence given time of year
providing warmer temperatures.

&&

.HYDROLOGY...
Issued at 329 AM CDT Mon Jul 8 2024

Falling river stages can be noted from Guttenberg, IA on
northward along on the Mississippi River. Falling river stages
are expected to continue through this week from southwest
WI/northeast IA on northward. Currently, locations at La Crosse,
WI, McGregor, IA and Guttenberg, IA remain at Moderate flood
stage with several other locations at minor flood stage. As we
head through this week, expecting scattered showers and storms
during the afternoon/evening hours on Monday and Tuesday to
produce generally light rainfall amounts. Locally heavier
rainfall will be possible with slow moving storms or if storms
repeat over the same locations. Overall though these
showers/storms are not expected to have much impact on the
Mississippi River basin.

&&

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

&&

$$

DISCUSSION...EMS
AVIATION...Rieck
HYDROLOGY...Naylor