264 
FXUS63 KARX 111104
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
504 AM CST Thu Mar 11 2021

.SHORT TERM...(Today and tonight)
Issued at 300 AM CST Thu Mar 11 2021

Satellite imagery and surface observations indicate a pretty 
expansive cloud deck on the backside of the surface low tracking 
across northern Wisconsin this morning. The RAP indicates the low 
level moisture and clouds will remain over the area through much 
of the morning and then should pull off to the northeast pretty 
quick in the afternoon. This will allow for a decreasing cloud 
trends with plenty of sunshine expected for the latter part of the
afternoon. Tonight looks to be pretty quiet as an area of high 
pressure builds in from the west. Temperatures will be cooler 
behind the departing area of low pressure with highs today 
expected to range from the middle 40s to the lower 50s and lows 
tonight dropping back into the 20s.

.LONG TERM...(Friday through Wednesday)
Issued at 300 AM CST Thu Mar 11 2021

Main concern in the long term period remains precip chances 
Sunday night into Monday and perhaps Tuesday. Following a dry and 
cooler period with the area under the influence of surface high 
pressure and northwest flow aloft Friday and Saturday, a potent 
cutoff low will eject east-northeast out of the Desert Southwest. 
While the low looks to stay well south of the forecast area, good 
agreement that precip associated with the deformation band to the 
north will make it into at least southern portions of the forecast
area, with a good chunk of solutions giving at least some light 
precip to the entire region. 

That said, plenty of questions remain on amounts and precip type 
owing to differences in degree of weakening as the system moves 
in, and temperatures, especially on Monday. General trend has been
toward the band of precip moving in and gradually weakening 
through the day on Monday, but an increasing number of ensemble 
members, as well as the 11.00Z ECMWF have been suggesting the band
holds together and advances northeastward through much of 
Wisconsin. As far as temperatures go, still plenty of spread 
there, but a majority of EPS members suggest highs below 40 
degrees on Monday. Therefore, knocked down highs on Monday a few 
degrees by blending more toward raw model output vs. the NBM which
is likely too high due to higher bias-corrected temperatures from
the recent warmth. This gives a bit more snow through the day 
instead of rain, which seems to be in line with a majority of 
model-derived precip types shown by the GEFS and EPS. This does 
not necessarily mean we'll have an impactful winter storm on our 
hands, as the band of precip could be tapering off quite a bit, 
but the colder solution seems to make more sense given latest 
guidance. Will need to continue to monitor trends to see if 
further downward adjustments of temperature are needed.

Models diverge quite a bit for the end of the period, with some 
lingering precip into Tuesday or even bringing another bit of 
shortwave energy through, while others suggest high pressure 
builds in and leads to dry weather through much of Wednesday. 
Overall, confidence is rather low regarding potential impacts for 
the Sunday/Monday system and even lower regarding what happens in 
the days following.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 504 AM CST Thu Mar 11 2021

Satellite imagery shows lots of clouds covering much of the Upper
Midwest this morning behind an area of low pressure over southern
Lake Superior. The low will continue to move away from the area
today and the clouds will go with it over time. The RAP suggests
the low level moisture for the clouds will remain for much of the
morning but should quickly depart the area late this morning into
the early afternoon. Based on this, expecting ceilings to remain
MVFR until the clouds scatter out allowing VFR conditions to
return by late morning for both sites. The west/northwest winds
will remain gusty for much of the day until diminishing late this
afternoon as the mixing shuts down and the gradient relaxes with
an area of high pressure building in from the west.

&&

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

$$

SHORT TERM...04
LONG TERM...CA
AVIATION...04