966 
FXUS63 KARX 090428
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1028 PM CST Wed Nov 8 2023

.DISCUSSION...(This evening through Wednesday)
Issued at 237 PM CST Wed Nov 8 2023

Key Messages: 

 - Periods of windy conditions tonight and Thursday. Wind gusts 30 to
   40+ mph (50 to 100%). Spotty rain ending this this evening. 
   Temperatures remain seasonable Thursday.

 - Seasonable, mostly dry through the weekend. Warming up next week. 

Overview:

Water vapor satellite imagery/500mb heights/lightning highlight a 
ridge over the southeast U.S. with a broad trough from the Northern 
Plains southwest toward Utah and southern California with a ridge 
off the West Coast. At noon, WSR-88D mosaic had showers and a few 
storms that developed in a line from near Green Bay toward Coloma, 
WI. These showers and storms were on the edge of the deeper moisture 
and along the 850mb front.  Farther west, a plume of mid-level 
moisture combined with mid-level vorticity advection and 
frontogenesis is resulting in a band of clouds along with some light 
rain and drizzle.  In-between, where the low level moisture remained 
and lift is weak, there is areas of fog and some patchy drizzle.  Of 
note related to the winds upstream...VAD wind profilers both 
925/850mb were 40 to 50kts across North Dakota with several reports 
of 35 to 40kts winds.

Spotty rain ending. Periods of gusty winds 30 to 40+ mph tonight and 
Thursday. Temperatures remain seasonable Thursday:

Through Thursday, the 500mb trough will continue to push southward, 
with a lobe of energy and a cold front pushing through the area this 
evening.  The instability and deeper low level moisture axis shift 
east of the area by 00Z with the mid-level moisture axis waning into 
the evening.  The hi-res models hint at at a narrow band of 
sprinkles or light rain re-developing north of I94 with the 
steepening mid level lapse rates did leave some spotty low pops in 
to account for this.

The nose of the low level jet moves into the region this evening 
with the cold front.  Gusty winds develop as the stronger winds mix 
down for a few hours this evening for now, have winds gusting 20 to 
35 mph with stronger gusts in open areas.  The gusts back off later 
tonight, but increase again for Thursday with the next surge of 
stronger winds aloft.  The 08.00Z EPS/GEFS/Canadian ensembles only 
had a 50% chance for winds greater than 30mph, however the 08.00Z 
HREF had 80-90% probability for winds greater than 30mph, 80-90% 
greater than 35mph and 10-15% probability greater than 40mph. The 
08.12Z HREF data was similar.  Have most wind gusts in the 30 to 45 
mph range both tonight and Thursday.

Looking ahead:

High pressure continues to build across the Northern Plains late this 
week into the weekend leading to mostly dry, seasonable conditions. 
The biggest forecast question in the next 5 days revolves around the 
chance for light precipitation late Saturday night as a shortwave 
trough moves through. As discussed in previous discussions, ensemble 
guidance in both the EPS and GEFS shows mixed signals with a 50/50 
mix of members that precipitate to those that don't. There are 
timing differences between members as well. All of this uncertainty 
is presenting itself as low 10-20% PoPs in the NBM, mainly north of 
I-90. Regardless of timing, location, and occurrence of 
precipitation, accumulations look very light so we are not foreseeing 
this to be an impactful weather system. 

An amplified upper-level ridge builds in early next week resulting 
in above-normal temperatures. Ensemble guidance suggests there's a 
>90% chance for temperatures over 50 degrees across the entire 
forecast area. Some locations could even hit 60.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1028 PM CST Wed Nov 8 2023

VFR conditions are expected through the TAF period with two rounds 
of blustery winds, one tonight with a frontal passage and another
during the late morning and afternoon hours tomorrow. Winds will 
remain west to southwest but will be around 15-25 kts with gusts 
reaching 35 kts, particularly across southeast MN. There is still 
the possibility for a few stray gusts higher than this with 
forecast sounds showing winds atop the mixed layer in the 40-50 kt
range. Winds will begin to subside during evening hours on 
Thursday to around 10 kts. LLWS may be present during the morning 
hours as winds decrease slightly and the low-level jet remains 
fairly robust. Otherwise, expecting mainly clear skies through the
TAF period.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

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