National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KARX 210830
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
330 AM CDT Sun Apr 21 2024

.KEY MESSAGES...

- More sunshine and warmer today and Monday with low relative
humidity. Combined with the winds, these conditions may lead to
elevated fire weather conditions.

- Shower chances (some embedded thunder) continues for later Monday
into Tuesday.  Amounts still light; 30-70% greater than 0.10".

- Confidence increasing for freezing temperatures again Wednesday
morning.

- Unsettled weather later the week into early next week.

&&

.DISCUSSION...
Issued at 315 AM CDT Sun Apr 21 2024

Overview:

With all the clouds Saturday, temperatures were held to the 30s
for a good portion of the day, however, once the clouds broke
up, several locations recovered into the 40s. Rochester and La
Crosse both topped out at 43; a few degrees above the normal low
for this time of year. A little light snow occurred in the
morning, however the sprinkles/flurries did not develop later in
the day.

Water vapor satellite imagery and heights early this morning showed
a broad trough encompassing much for the U.S.  This had pushed a
cold front southward with convection along the front from Texas
to Georgia and into the Carolinas. 500mb ridging was over the
Rockies with another trough moving into Washington State.
Surface high pressure was centered over the western High Plain,
and by 03Z, the wind were decoupled and many locations calm.
Temperatures at 08Z, many locations were below freezing with a
few high clouds.

Warmer with elevated fire weather conditions possible today and
Monday; shower chances return Monday:

A cold front passes northeast of the local area as mid-level
ridging builds in for today. More sunshine and warmer
temperatures are forecast for today and Monday with low relative
humidity. Combined with the winds, these conditions may lead to
elevated fire weather conditions each day. See fire weather
discussion. Highs are forecast to top out in the 50s to lower
60s today with 60s for Tuesday. Northwest breezes today gust 15
to 25 mph with southwest breezes Monday ahead of a cold front with
gusts 25 to 30 mph.

The shortwave trough moving into British Columbia and Washington
State will track eastward across southern Canada and into the
northern Rockies today and tonight.  Meanwhile, surface low pressure
will develop along the cold front over the western High Plains.
Moisture transport across the Plains shifts toward the Upper
Mississippi Valley Monday afternoon and Monday night ahead of the
approaching 500mb trough.  Hi-res model simulated reflectivity show
slightly better shower organization north of I90 and also south as
the front swings through while the deterministic models are more
general. Embedded thunder is possible, thus left a slight
chance in Monday evening. The first area of showers moves
through by midnight with a break early Tuesday morning with
additional shower/ thunderstorm activity Tuesday as the storm
system moves through. We continue to see light rainfall amounts
with an 25-70% chance for amounts more than 0.10".

Frost/Freeze Potential:

Monday morning with light winds, generally clear skies, and lows
from the mid 20s in the cold favored areas and mid 30s elsewhere
some frost possible outside of the areas with freezing temperatures.
Freezing temperatures are currently forecast for Wednesday
morning. The EC/GFS/Canadian ensembles depicting at 60 to 100%
probability for 32 degrees or colder low for all but parts of
northeast.

Potential for an active weather pattern setting up for the end of
the week into early next week:

A mid-level ridge dominates Wednesday into early Thursday.
Later Thursday, the next area of closed low pressure is forecast
to move into the Plains Thursday night and Friday/Saturday.
Additional rounds of showers and thunderstorms may occur Sunday
into next week. The current 7-day rainfall trends are for above
normal amounts, especially across Iowa into southern
MN/southwest WI with above normal temperatures. The GFS/EC
ensembles show the potential for 2-3"+ rain amounts through
early next week. We`ll be able to provide more details related
to rainfall and severe weather potential as we get closer.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1045 PM CDT Sat Apr 20 2024

VFR conditions will continue as trough exits to the east and high
pressure builds in from the west. A return to steady northwest wind
on Sunday but very light flow the rest of tonight and again Sunday
night.

&&

.FIRE WEATHER...
Issued at 310 AM CDT Sun Apr 21 2024

Elevated fire weather condition are possible this afternoon as
northwest winds strengthen with gusts 15 to 25 mph with deeper
mixing to nearly 700 mb.  A relatively dry airmass is in place with
precipitable water values are 50 to 75% of normal.  Lowest
relatively humidities lower to 20 to 30% as temperatures warm into
the 50s to lower 60s. East of the Mississippi river Monday, it will
be dry again with similar RH values. Southwest winds strengthen area-
wide with gusts 25 to 35 mph. Dewpoints gradually increase west
of the Mississippi River. Highs Monday top out in the 60s with
rain chances increasing during the afternoon. Should winds be
stronger than expected, RH values could be lower. There has been
some green-up, however dries tall grasses remain. Caution should
be exercised if burning.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Freeze Warning until 8 AM CDT this morning for WIZ032-033-041-
     053>055-061.
MN...Freeze Warning until 8 AM CDT this morning for MNZ079-086>088-
     094>096.
IA...Freeze Warning until 8 AM CDT this morning for IAZ008>011-018-
     019-029-030.

&&

$$

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