210
FXUS63 KARX 181130
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
630 AM CDT Thu Jul 18 2024

.KEY MESSAGES...

- Pleasant, quiet weather continues into the weekend with
  temperatures running just below normals. Good scenario as
  rivers continue to fall.

- Threat for diurnal shower activity returns this weekend into
  next week but no strong signal for prolonged, heavy rains.

&&

.DISCUSSION...
Issued at 145 AM CDT Thu Jul 18 2024

In the midst of a much needed break from storms and heavy rain
with drier air well in place in this northwest flow. Not only
are the lower dew points welcomed but this dry time is allowing
area waterways to continue their receding.

Overall pattern does not change much through this period with
mean ridge across Intermountain West and troughing across the
eastern CONUS. Given our location in the flow, will be watching
for waves dropping into the Cornbelt and western Great Lakes
for diurnal rain threats.

Today-Friday

Surface high in place today into Friday for very pleasant couple
days. Could see more diurnal clouds with last couple GFS runs
suggesting a smattering of light showers. Other guidance and
CAMS keep things dry which looks more reasonable given the lower
precipitable water values and weak flow.

Friday into Next Weekend

On Friday there are hints of a wave dropping into the Cornbelt
region and with axis of higher precipitable water values in that
area, banking that main rain threat will reside closer to the
wave /west of the area/. The only problem is it looks like this
feature, albeit weak, could become cutoff from stronger flow to
the northeast. If this materializes, we could see several days
of mainly diurnal shower activity going into next week.

While there is some increase in precipitable water values,
perhaps closer to normals for late July, ingredients for heavier
rain threat are lacking. Modest CAPE values expected so unsure
how widespread diurnally driven convection will actually be. But
it does make sense to see timing during the afternoons and early
evenings with cooler air aloft and summer sun angle/heating.

Some hints in longer range guidance that western ridge could
slide east later next week with a warming trend but will have to
see how things transition.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 616 AM CDT Thu Jul 18 2024

Besides ongoing fog and accompanying LIFR in select western and
central Wisconsin cold spots/river valleys, VFR expected across
the forecast area from northeast Iowa, southeast Minnesota, and
western into central Wisconsin for most of the 18.12Z TAF
period.

Valley fog potential returns late tonight into Friday morning,
potentially more widespread. Therefore, could potentially
impact Mississippi River Valley and KLSE TAF site. Expect
daytime cumulus to dissipate and subsequently allow sufficient
surface cooling to reach saturation. Other ingredients such as
light wind are also conducive to valley fog formation.

&&

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

&&

$$

DISCUSSION...Shea
AVIATION...JAR