Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 250855
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
355 AM CDT Mon Mar 25 2024

.KEY MESSAGES...

- Much warmer with highs in the 40s and 50s.

- Periodic showers and a few storms with 0.5"(60 to
  100%) to 1" (10 to 30%) through tonight.

- Areas of fog possible where winds are lightest.

- Increasing east to southeast winds. Stronger 25 to 40mph gusts
  across parts of northeast Iowa and southwest Wisconsin today
  and tonight.  Some stronger winds near storms.

- Light snow Tuesday for some; If snow falls; 80% chance less
  than an inch.

&&

.DISCUSSION...
Issued at 345 AM CDT Mon Mar 25 2024

Overview:

The 25.00Z MPX sounding was saturated with 0.58" of
precipitable water and steep mid level lapse rates above 700mb.
Latest water vapor satellite imagery, heights, and lightning
showed a broad trough encompassing much of the U.S. The center
of the 500mb low at 06Z was located over western Kansas with
lightning over parts of northern Kansas and across parts of
Oklahoma and Texas with a cold front. At 08Z...thunderstorms had
moved into southeast Nebraska with the strong moisture transport
ahead of the mid-tropospheric trough. At the surface, a 987mb
low was over southwest Kansas with and inverted trough cold
front/trough northeast through eastern Nebraska into western
Iowa and the warm front into south central Iowa. A strong
pressure gradient was noted across the region with a wide
variety of precipitation due to the thermal profiles. 850mb
temperatures likely ranged from -1 or -2 in the north part of
the forecast area to +5 or 6 in the south. Recent WSR-88D mosaic
and metars showed the snow lifting north out of the area with
rain being reported at Rochester with the warmer temperatures
aloft. It was still lightly snowing at Medford. Temperatures
warmed as you head south with 30s, 40s and 50s.

More snow reports will be coming in during the morning hours,
however reports so far, 4 to 6.5" reports were coming in and
around the Rochester and La Crosse areas, with reports of 7 to
9"+ from Wabasha north toward Dorchester and Stetsonville.

Today through Tuesday:

The upper level trough remains to the west of the forecast area
today with strong moisture transport. 850mb dewpoints around 6
deg C. in southeast Nebraska advect northeast into northeast
Iowa and southwest Wisconsin through 15Z, overspreading most of
the forecast area by 18Z before shifting east. The bulk of the
elevated instability appears to be over western Iowa, however
will need to watch for thunderstorms as some instability (50-120
J/kg) tries to head toward the forecast area with increasing
deep layer shear this morning. Periods of light rain early this
morning should increase with showers becoming more widespread
during the morning as shortwave trough energy lifts north/upper
level jet support continues. Additional showers/storms during
the afternoon and overnight as the next area of upper level
support rotates through. The bulk of the MUCAPE remains south of
the forecast area tonight, but again will need to monitor for
any storms within the high deep layer shear environment.

The rain transitions to a wintry mix/snow Tuesday morning.
Steep low level lapse rates could support some increased pockets
of snow. At this time, due to low confidence on where the
greater chances would be, most amounts are an inch or less.
Temperatures today are forecast to rise into the 40s and 50s
with dewpoints in the 50s heading toward parts of northeast
Iowa. East to southeast winds strengthen with some 25 to 40 mph
wind gusts across parts of eastern Iowa and southwest Wisconsin.
The stronger 40+ mph wind gusts look to remain just south of
the local area today and could clip parts of Grant Co. overnight
should storms be nearby. Farther northwest, the winds will be
lighter later tonight, thus areas of fog may try to develop. Non-
diurnal temperatures for Tuesday as colder air works in from
the west, thus morning highs for many spots as temperatures fall
west to east during the day.

Rainfall amounts are projected to range from .5 to 1.25 inches,
with higher amounts in the west and north, however with
convection, some of these could be locally higher.

Wednesday through Friday:

Surface high pressure will cover much of the region Wednesday and
Thursday with ridging building in for Friday. A warm front will try
to lift toward the forecast area with with a shortwave trough
topping the ridge. The sun will try to come out Wednesday, however
convective temperatures are in the 20s, thus with some shallow
moisture, the clouds will try to fill back in. Wednesday appears to
be the coldest day with below normal highs in the 30s to lower 40s.
Generally dry conditions will prevail Wednesday and Thursday,
however showers will return to the forecast Friday and Friday night
with that shortwave. Highs in the 30s and 40s Thursday are forecast
to warm into the 40s and 50s Friday with the above normal
temperatures lasting into the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1047 PM CDT Sun Mar 24 2024

Variety of flight conditions with larger storm system impacting
region at the moment. Where snow continues to fall, widespread IFR
to LIFR conditions prevail but VFR conditions were sweeping in from
the south as warmer air continues to advect in. This was not only
improving visibilities south of warm front but raising ceilings
up.

Expecting general MVFR to VFR conditions for part of the night as
waves of precipitation move through but as entire wave approaches
and broad lift continues, expect ceilings to drop going through the
day Monday along with areas of fog as surface temperatures continue
to warm and snow melt adds moisture. Difficult forecast for sure
with so many variables but guidance certainly suggests higher
probabilities for IFR conditions at least later Monday.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning until 7 AM CDT this morning for WIZ017-
     029.
MN...None.
IA...None.

&&

$$

DISCUSSION...Zapotocny
AVIATION...Shea


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