000
FXUS63 KARX 220918
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
418 AM CDT Mon Apr 22 2024

.KEY MESSAGES...

- Elevated fire weather conditions across parts of Wisconsin
  before rain chances increase later today.

- Strong winds from the southwest 30 to 40 mph developing today
  ahead of a cold front.

- Light rain amounts later today into Tuesday, with a stormier,
  wetter period Thursday night into early next week.

- Frost/Freeze Wednesday morning.

&&

.DISCUSSION...
Issued at 400 AM CDT Mon Apr 22 2024

Overview:

Starting out a little milder today with light and variable or
light southwest winds and temperatures in the 20s, 30s, and
40s. Water vapor satellite imagery and heights early this
morning showed a mid tropospheric ridge with some high clouds
spilling into the area.  An area of closed low pressure was
centered over Saskatchewan.

Today through Tuesday night:

The closed low will move into the region today breaking down the
ridge and swinging through the Northern Plains and Upper Mississippi
Valley through Tuesday evening.  Moisture transport across the
Plains increases across western Iowa this morning and toward the
Mississippi river through 00Z, then shifts east of the area by 06z
with wrap-around moisture Tuesday.  A strengthening low level jet
ahead of the cold front across Iowa will transport warm air
northeastward with temperatures warming into the 60s. Meanwhile, a
strong 100kt jet will push into the Rockies and Plains. With the
ascent, warm air advection, and moisture transport, clouds will be
on the increase with some showers developing. Initially,
precipitable water is 25 to 50% of normal, however by 23.00Z
increases to 125 to 150% of normal.

Initially the dry low levels and approach of the storm system will
favor deeper mixing, however with the increasing clouds, this will
work against optimizing mixing.  Seeing some differences in how
strong the southwest winds will be.  The 35 to 45kt low level jet
over western Iowa/central MN around 18Z shifts eastward during the
afternoon and increases to 40-50kts as it moves into southwest WI
during the evening.  The HREF probabilities of 26kts winds are only
10 to 20%, however the HRRR/CONSShort forecasts have 23-25kts
across our western counties with the ADJLAV/GLAMP data in the
25-30kt range. Some mixed signals on the winds, but there will
be a strong cross-wind component along I90 and potential for
additional gustiness with the virga and light precipitation in
the area. In coordination with MPX/DMX included parts of
southeast MN and northeast IA in a wind advisory for later this
morning and much of the afternoon. The wind vectors become less
unidirectional as the stronger winds aloft shift into Wisconsin,
so we`ll need to monitor how effective the stronger winds are
mixing down during the day and as they shift east this evening.

Virga and a few showers increase through the day with the warm
advection and moisture with showers becoming more likely along and
north of I94 this evening.  Rainfall amounts should be light with
the greater probabilities of 0.05" or more north of I94 (50-80%). We
should see a break overnight with the re-enforcing cold front
and upper level trough swinging through later morning into the
afternoon. Some instability 50 to 250J/kg attends the upper
level trough Tuesday, thus have thunder mentioned. Again
precipitation amounts should be on the light side with 30-60%
probabilities of 0.10" across parts of WI.

See Fire Weather section for elevated fire weather details.

Frost/Freeze Potential Wednesday morning:

Skies clear for Wednesday morning with diminishing winds.  The cold
airmass shows the potential for temperatures to drop back into the
20s and lower 30s for much of the forecast area again.
EC/Canadian/GFS ensembles show a 30 to 90% probability for a low of
32 or colder with the higher probabilities north (MDZ) and lower
probabilities toward DBQ.

Thursday night into early next week:

We continue to see trends of a pattern change and active weather
setting up from Thursday night into early next week.  A series of
troughs are forecast to move into the Plains and head toward the Mid
and Upper Mississippi Valleys.  The first area of 500mb low pressure
tracks across the Central Plains and heads toward MN/Upper MI.  This
pattern lifts a warm front into our region with periods of showers
and thunderstorms Friday into Saturday. The location of strong
to severe storms will depend on how the track evolves. We
currently have highs in the 60s Friday with 60s and 70s forecast
for Saturday. The next storm system Sunday into Monday again
affects a large portion of the Midwest, but there are some large
differences in strength. Strong winds are currently forecast to
accompany the storm system Friday. Over the course of these two
storms, widespread rains are expected and some initial
estimates have 1.5"+ over a large area of the Midwest.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1057 PM CDT Sun Apr 21 2024

VFR conditions will prevail through this TAF period. Look for
light winds and clear skies through the overnight period;
however, as a wave shifts west to east across the area on
Monday, southerly winds will increase with gusts in the 25-30kt
range across much of the area. As this wave traverses the area,
a mid-level (5000-6000ft) VFR ceiling will move in. While dry
air will limit precipitation potential Monday, there is a 20-30%
chance for rain showers through Monday afternoon.

&&

.FIRE WEATHER...
Issued at 400 AM CDT Mon Apr 22 2024

Ahead of a cold front today, a dry airmass is in place with
strengthening southwest winds and warming temperatures into the
60s. Lowest relative humidity values drop to 20 to 30 percent
through mid afternoon, then improve with increasing rain
chances. Fuels have increased with some drying over the last
couple of days and the warmer temperatures today. Due to the
strong winds developing from the southwest with gusts 30 to 40
mph, burning should be avoided due to the elevated fire weather
conditions.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Advisory from 11 AM this morning to 5 PM CDT this
     afternoon for MNZ086-087-094-095.
IA...Wind Advisory from 11 AM this morning to 5 PM CDT this
     afternoon for IAZ008>010-018-019-029.

&&

$$

DISCUSSION...Zapotocny
AVIATION...JAW
FIRE WEATHER...Zapotocny