Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
000
FXUS63 KARX 262346
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
646 PM CDT Tue Mar 26 2024

.KEY MESSAGES...

- Cold air moves into tonight areawide with snow ending. Chilly
  conditions remain into Thursday.

- Periodic precipitation chances and near normal temperatures
  Friday through Tuesday.

&&

.DISCUSSION...
Issued at 155 PM CDT Tue Mar 26 2024

Snow ending Tonight but Chilly into Thursday

The departing surface cyclone will track towards Lake Superior by
early this evening with gusty west winds and colder air wrapping
into the area. Some light deformation band precip will lift
northeastward through late afternoon before diminishing north of I-
94 this evening as strong subsidence develops in the mid-levels
behind the cyclone. The precip will transition from rain to snow as
the cooler air arrives, with up to around an inch of additional snow
possible from west-central through north-central Wisconsin, but
impacts look minor given warmer ground temps.

Otherwise, a chilly mid-week period is in store with wind chills
falling towards zero in spots overnight with blustery winds and
overnight lows in the teens and 20s. Another mid-level trough will
rotate east across the Upper MS Valley, with lower clouds likely
remaining stubborn, especially north of I-90 through the day on
Wednesday. A snow shower could not be ruled out across north-central
Wisconsin in the afternoon as lapse rates steepen beneath cyclonic
flow.

Precipitation Chances Return This Weekend and Again Early Next
Week

Ridge building begins Thursday with the longwave pattern favoring a
western U.S. and active zonal flow downstream over the central
states. Warm advection will begin Thursday with highs expected to
warm 10 degrees or so but still be slightly below normal. The
next shortwave trough later on Friday and into Saturday provides
a weak surface low tracking south of the area with the latest
ensembles in reasonable/good agreement. This will spread light
rain chances into the area by Friday evening along the inverted
trough extending northward from the low and north of a warm
front roughly on the I-80 corridor. Amounts look light, with
only a 50% chance in the Grand Ensemble over 0.10" by Saturday
morning and mainly in WI. Will have to watch for possibly some
freezing drizzle or freezing rain Saturday morning. Right now,
it appears to be a small probability outcome to watch north of
I-94. Friday may be the warmest day in the forecast period and
only about 5F above normal.

The longwave trough begins to shift east late in the weekend and
with various degrees of northern stream phasing into early next week
depicted in the ensemble outcomes. Ensemble agreement isnt too bad
actually and most indications are that precipitation chances will
increase starting Sunday night and last into the new week. Timing on
this complex evolution as well as the frontal location and warm
advection across the area for precipitation types is of lower
confidence though. Overall, there seems to be good agreement among
the Grand Ensemble on this pattern evolution and forcing for
precipitation which appears to be mainly rain. Temperatures during
this period look near normal.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 647 PM CDT Tue Mar 26 2024

MVFR conditions will begin the TAF period as afternoon snow pulls
away from the region leaving a low stratus deck in its wake. Low
stratus will prevail through much of the overnight and through the
morning hours on Wednesday. Questions remain exactly how effectively
mixing and higher sun angle will clear out the cloud deck during the
afternoon creating some confidence issues for timing. However, by
2100z the 26.18z HREF has zero probabilities for MVFR cigs along and
south of the I-90 corridor so opted to remove MVFR mention from the
TAFs by 2100z. Otherwise, winds will decrease slightly overnight to
around 10-15 kts with gusts of up to 25 kts but will remain
from the west/northwest.

&&

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

&&

$$

DISCUSSION...Baumgardt/JM
AVIATION...Naylor


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.