Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 280808
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
308 AM CDT Thu Mar 28 2024

.KEY MESSAGES...

- Quiet today; Light precipitation moves in Friday night.
  10-60% probability for light icing across Taylor County early
  Saturday morning.

- Periodic precipitation chances increase Sunday into Monday
  night or Tuesday with seasonable temperatures.

&&

.DISCUSSION...
Issued at 250 AM CDT Thu Mar 28 2024

Overview:

Latest water vapor satellite imagery, heights, and lightning showed
a closed 500mb low over Ontario with a ridge moving into the Rockies
and another closed mid-tropospheric low off the Pacific
Northwest coast. Lightning was noted ahead of the longwave
trough across the Southeast Atlantic Seaboard. Surface high
pressure was centered from eastern South Dakota through Iowa
into Missouri. Local metars had light westerly winds with
temperatures in the teens and 20s. The GOES nighttime
microphysics satellite imagery showed and area of low to mid
clouds fl030-050 across much of the Upper Mississippi Valley
with a few areas of light snow or flurries for parts of northern
Wisconsin.

Quiet today-Light precipitation moves in Friday night. 10-60%
probability for light icing across Taylor County early Saturday
morning:

We remain under northwest flow aloft with ridging building in today
and tonight.  A trough moves through the Northern Plains Friday,
flattening the ridge with zonal flow through the weekend.  Forecast
soundings are on the dry side today, so should see more sunshine,
however temperatures remain below normal. A snowcover lingers to
the northwest...thus this could hold temperatures down over the
northwest part of the forecast area again today. With the
ridge, upper level relative humidity progs show cirrus
overspreading the area by 12Z Friday. Broad mid-level warm
advection through the day Friday should result in increasing mid
clouds. 850mb moisture increases from the Southern Plains
through the Mid Mississippi Valley during the day and heads
east toward the Ohio River Valley Friday night. A couple of
ripples embedded in the flow/warm air advection combine with the
right rear entrance jet support and low level moisture
transport for a little light precipitation Friday night. The
most likely amounts would be a trace to 0.10" with a 50-60%
probability for around 0.10" north of I94. Due to the
timing/thermal profiles, some of this may fall as freezing rain.
The MDZ forecast sounding shows a warm nose of +3 to +4 deg at
850mb with temperatures 30 to 32 degrees. The WSSI-P also hints
that freezing rain could occur across parts of Taylor Co. with
light icing. The 27.12Z GEFs/Canadian ensembles have a mean
10-60% probability for a light icing across Taylor County. The
mean ensemble higher CAPE is farther to the south across Iowa
and Illinois, however elevated CAPE pushes toward DBQ Friday
night, so have some thunder chances in our south.

Sunday into early next week:

The closed 500mb low over the Pacific Northwest coast is
forecast to drop south over California Saturday and phase with
troughing moving through the Rockies. An area of 500mb low
pressure closes off over the Central Plains and heads east
toward the Mid Mississippi Valley. Although the general pattern
is similar in the deterministic EC/GFS...there are details in
the latitude and strength that have yet to be resolved. Over the
last four runs of the mean ensembles, there has been a slight
shift southward in the highest probabilities for a wetting rain
of 0.1"+. The first area of showers will be possible Sunday with
periodic precipitation chances through Monday night or possibly
Tuesday. Through Monday the precipitation type is more rain,
with rain or a mix Monday night. We`ll continue to monitor
trends for the weekend and into early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1014 PM CDT Wed Mar 27 2024

CIGS: some BKN vfr lingering into the late evening, otherwise
expected SKC/SCT conditions into Thu night. Upper/mid level VFR cigs
return Friday afternoon ahead of the next weather system with
MVFR/IFR looking likely by the overnight hours.

WX/vsby: threat for light pcpn Friday night (40-60%, trending toward
rain). Related vsby impacts look minimal at this time.

WIND: westerly winds tonight/Thu 10 kts or less...then becoming
light easterly Thu night.

&&

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

&&

$$

DISCUSSION...Zapotocny
AVIATION...Rieck


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