737
FXUS63 KARX 091941
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
141 PM CST Sat Nov 9 2024

.KEY MESSAGES...

- Rain will continue to move through the region late this
  afternoon and evening. A second round of rain (with isolated
  thunder) will move through the region for the morning and
  early afternoon on Sunday. Rainfall amounts of around 0.25" or
  less are expected in most locations.

- Seasonable to seasonably warm temperatures next week. Rain
  chances return late Tuesday night and Wednesday.

&&

.DISCUSSION...
Issued at 128 PM CST Sat Nov 9 2024

Rest of Today - Sunday: Periodic Showers This Weekend

GOES-16 satellite imagery depict a very prominent mid-latitude
cyclone centered over portions of the Great Plains this afternoon
associated with a uniformly closed low pressure center. As this low
continues to eject northeast bound, isentropic lift associated with
700-850mb theta-e advection will continue to instigate showers
further northeast throughout the remainder of the afternoon and
evening. Overall, guidance has tended to favor lighter amounts with
the recent 09.12z HREF only having lower probabilities (0-40%) for
amounts over 1/10". That being said, radar trends certainly show
pockets of heavier rainfall rates across northeast IA so would not
rule out some locally higher amounts of 0.2 to 0.4" with this first
round of precipitation.

As we move past the evening and into the overnight hours, the band
of showers lifts northeast of the region as the recent CAMs continue
to indicate minimal precipitation within a relatively weakly forced
regime overnight ahead of the low pressure center. Eventually
towards daybreak on Sunday, the closed low moves overhead bringing
additional chances for precipitation with the 09.12z HREF having
slightly higher probabilities (60-80%) of over 1/10" of rain during
the morning hours. With some weak instability present in the long-
range HRRR soundings, would not rule out a rumble of thunder or two.
Overall though, expecting rainfall amounts from now through Sunday
to be generally around 0.25" or less with locally higher amounts
possible within more robust showers and any storms.

Sunday night into the workweek:

Sunday night into Monday, a shortwave trough is forecast to rotate
through the U.P. of Michigan.  At this time, the HREF is mainly dry,
however a few rain mixed with snow showers could clip parts of north
central Wisconsin.  09.12Z HREF has a zero joint probability of
850mb temperatures dropping below 0 deg C. and a trace or more of
precipitation, however by 15/18Z, the 09.00 deterministic
models do cool 0 to 5 below zero north of Black River Falls.
HREF probabilities through 12Z Monday for a trace of
precipitation are 10 to 50%, but only 0 to 30% for 0.01. Lows
have cooled a few degrees from the previous forecast and are
currently forecast to range from the mid 30s north of BCK
northward to lower 40s Monday morning, if the cooling occurs
earlier or if any precipitation is falling, mixed precipitation
could occur. It will be something to keep an eye on. Highs
Monday should be in the 40s and to mid 50s.

Ridging is forecast to build in for Tuesday with highs in the 50s.
This warmth is short-lived as the next trough is already working
east through the Rockies.  Rain chances increase late Tuesday night
into Wednesday with the trough and associated cold front.  The track
of the surface low is farther north into northern MN/southern
Canada, thus the more organized rainfall appears to be tracking
north of the local area. 09.00Z LREF probabilities are 45 to 60%
for 0.10" or more.

Ridging returns later Wednesday night through Friday with continued
seasonably warm temperatures from the mid 40s to the mid 50s. Beyond
Friday, there is some disagreement as to how the next trough over
the West Coast deepens or if it will be less amplified moving
into the Rockies sending some energy ahead of it with a warm
front/precipitation developing Friday night into Saturday. At
this time, the rainfall probabilities are 10 to 20% for 0.10" or
more, so stay tuned.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1132 AM CST Sat Nov 9 2024

Showers and low clouds will be the primary TAF consideration as
a low pressure system moves through the region. As showers push
into the region later this afternoon and evening, expecting low-
VFR to MVFR cigs with occasionally dropping to MVFR
visibilities with any robust showers. As the low pressure center
begins to move towards the region tonight, IFR cigs appear
likely (60-80% chance) with low-level saturation across the
area. Still some probabilities (15-25%) in the 09.13z NBM that
cigs could fall to LIFR levels however this remains lower
confidence. The low pressure center then passes overhead during
the morning and afternoon hours tomorrow with lift and low-
level saturation enabling additional precipitation production.
As a result, showers may reduce vsbys to MVFR/IFR during this
period. After the low pressure center passes, expecting
conditions to improve some after 18z.

&&

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

&&

$$

DISCUSSION...Naylor/Zapotocny
AVIATION...Naylor