565
FXUS63 KARX 081933
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
133 PM CST Fri Nov 8 2024

.KEY MESSAGES...

- Rain returns to the area Saturday afternoon into Sunday.
  Rainfall amounts are expected to be up to a quarter of an
  inch.

- Next chance of rain is middle next week.

&&

.DISCUSSION...
Issued at 129 PM CST Fri Nov 8 2024

Rain Chances Saturday Afternoon Into Sunday

The upper level closed low that has been situated over the southwest
United States the last several days has begun its march
northeastward today, with water vapor imagery currently indicating
it is located over the Texas/Oklahoma Panhandles. Moisture advection
ahead of this low will make its way into the Upper Mississippi River
Valley region Saturday which combined with broad ascent associated
with the low will allow for rain to overspread the area Saturday
afternoon into Sunday. A high consistency in the NAEFS has been
observed over the past several runs regarding PWAT values across our
area this weekend, generally 0.8-1 inch, which are in the 90th
percentile compared to climatology for this time of year, although
the highest moisture content and deeper saturation continues to be
depicted to the south and east of our area. Despite the above normal
moisture, rainfall amounts are still expected to be on the lighter
side owing to a fairly progressive system as well as the higher
moisture content to the southeast. A general 0.25" of rain is
expected across the area with perhaps locally higher amounts if some
of the higher moisture to the southeast is able to make it into our
area. However, probabilities of higher rainfall amounts have been
decreasing over the last several runs of ensemble guidance. The
08.12z LREF indicates < 40% chance for amounts > 0.25" and <
10% chance of amounts > 0.5". For reference, the 07.12z LREF
indicated a ~50% chance for > 0.25" and < 20% chance of amounts
> 0.5". Overall, amounts are expected to be closer to 0.25" or
less through the weekend given the low probabilities for higher
amounts and progressive nature of this low.

Rain Chances Mid Next Week

500hPa ridging briefly builds into the region Sunday night into
Monday in the wake of the low departing to the northeast before a
500hPa shortwave trough dives south into the region, dragging a cold
front across our area Monday into Monday night. Expecting the front
to remain dry as it moves through as the stronger forcing and better
moisture look to be situated to the north. The 08.12z LREF is
consistent with this thinking as it suggests a < 15% chance of
light precipitation across north central Wisconsin.

Better chances for rainfall remain Wednesday into Thursday as the
longwave pattern amplifies across the central United States. 08.12z
LREF cluster analysis for Day 5 depicts a few scenarios as there are
still differences noted in the strength and timing of this trough
and associated surface frontal system largely due to differences
between the ENS and GEFS. The first scenario has a slower
trough situated across the central CONUS whereas the second
scenario has a more progressive trough situated across the Great
Lakes. The speed and location of said trough along with the
surface frontal features will influence overall rainfall amounts
during this timeframe, but 40-60% probabilities of precipitation
are currently forecast.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1100 AM CST Fri Nov 8 2024

CIGS: a gradually increase in high clouds overnight, out ahead of an
approaching low pressure system moving northeast out of the plains.
The cigs will continue to thicken and lower through Sat, with short
term guidance favoring a drop into MVFR (possibly IFR) later Sat
night.

WX/vsby: no impacts through Sat morning. Scattered -shra should
spread in Sat afternoon with the aforementioned low pressure system.
On and off showers expected into Sunday morning. Amounts look
minimal through the period (1/4" or less). Guidance holds off on
most of the related vsby impacts until later Sat night.

WINDS: light northerly swing to the east then southwest tonight.
Speeds will pick up for Sat (10 to 15 kts, a few higher gusts near
20 kts possible at KRST).

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Rieck