Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 161822
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
122 PM CDT Sat Mar 16 2024

.KEY MESSAGES...

- Cold start to the new week - below normal for a change. Single
digit wind chills for most Monday morning.

- Moderating temps for the rest of the week (back to normal)
  with rain (or snow) chances returning by the weekend.

&&

.DISCUSSION...
Issued at 120 PM CDT Sat Mar 16 2024

* COLD START TO THE NEW WEEK - below normal for a change

Cold air starts to pile in from Canada tonight with the passage of a
cold front this morning and upper level trough carving out across
the upper mississippi river valley/great lakes. 850 mb temps
expected to drop from around -4 C at 00z this evening...to as cold
as -14 C by 12z Mon. HREF and LREF probabilities for temps of 40+ F
for Sun and Mon are essentially "0" although the upper 10% of the
GEFS and EPS suites hint that 40 could be cracked at a few locations
Monday. All in all, below normal temperatures for the next couple
days - the first time we will be able to say that since the end of
February. In addition, winds will be stirring enough late Sun
night/Mon morning to produce low teens/single digit wind chills.

Precipitation chances?

Come Monday night, a bit of upper level energy progged to drop
southeast across northern WI, dragging a sfc cold front along with
it. Fgen with the front and deeper, stronger QG convergence holds
northeast of the area as does the deeper saturation (mostly mid-
upper level). Time/height x-sections and bufkit soundings show this
well. Medium and long range guidance mostly hold any pcpn chances to
north/northeast WI - with the saturation challenges being the
limiting factor farther southwest. Could be rain or snow but amounts
minor eitherway. Will let the model blend detail any chances, which
locally would be northeast of I-94 (10-20%).


* MID WEEK - moderating temps, rain chances for the weekend?

Long range guidance continues to paint a mixed picture of how the
upper level pattern could evolve as we move past Monday and into the
latter parts of the new week. Over-arching view suggested in the EPS
and GEFS suite of members is for broad ridging/zonal flow to develop
and shift across the region for the latter half of the new work
week. How strong and positioning varies a lot, evidenced via the WPC
clusters. The EPS and GEFS have shares in each of the 4 possible
outcomes, which have a variety of possible outcomes - all which
would impact the local sensible weather.

The upshot despite the lack of clarity is for rebounding temps.
Again though, spreads in both the EPS and GEFS push upwards of 40+
degrees for possible high temps. Latest deterministic runs settle
in to the bottom 50% (colder) of those outcomes. The model blend
paints a return to the mid March normals, and this looks reasonable
(for now).

As for precipitation chances, long range guidance suggests a
shortwave could drop southeast out of Canada, spinning across
portions of the Upper Mississippi River Valley Thu/Fri. Depending on
where the broad upper level ridge lies, more shortwave activity
could then shift west-east across the region for the weekend. All
would bring pcpn chances (rain or snow, temp dependent). However, as
already mentioned, a lot of uncertainty in how the upper level
pattern will evolve as we move through the new week, keeping
forecast confidence low on the details. As it sits, trends do favor
dry conditions for the middle part of the new week, with some
shot(s) for pcpn Thu through the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1230 PM CDT Sat Mar 16 2024

VFR conditions are expected through the TAF period with winds
remaining gusty. With afternoon mixing beginning to take shape
today, winds will continue to remain blustery at 15-25 kts with
gusts upwards of 30-35 kts, potentially higher at KRST and in
unsheltered areas. As evening approaches, winds will diminish
overnight but will likely increase marginally again by Sunday
afternoon. Cigs throughout the period will remain mostly VFR
with model soundings showing low-level saturation varying
between 4-7kft through the TAF period. There is some hints of
MVFR towards the end of the TAF period on Sunday morning across
southeaster Minnesota. The 16.12z HREF has lower confidence
(20-50% chance) for MVFR cigs across portions of southeastern
Minnesota with the higher probabilities for MVFR being across
north-central Wisconsin (70-90% chance) on Sunday morning.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...Naylor


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