Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251049
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
549 AM CDT Mon Mar 25 2019

.SHORT TERM...(Today and tonight)
Issued at 303 AM CDT Mon Mar 25 2019

Main forecasts concerns for today are on afternoon relative
humidity values.

Canadian high pressure will build southeast today and tonight with a
very dry, seasonably cool airmass advecting over the area. With
diurnal mixing, dew points will fall into the single digits or even
near zero over parts of western/central WI this afternoon with RH
near or below 20 percent in some areas. As the high builds south,
remaining low-level moisture/clouds this morning will be scoured out
with mostly clear skies this afternoon through tonight. Highs today
will generally be in the upper 30s to upper 40s with lows tonight in
the mid teens to mid 20s.

.LONG TERM...(Tuesday through Sunday)
Issued at 303 AM CDT Mon Mar 25 2019

Main forecast concerns in the long term are on afternoon relative
humidity values Tuesday. Focus then turns to increasing winds on
Wednesday, and how soon does the moisture return. If its delayed
we may see some fire weather concerns due to lower relative
humidity and increasing south winds.

High pressure slides southeast of the region Tuesday into Tuesday
night with increasing south/southwest flow setting up. We will
likely see another day of lower relative humidity values especially
along and east of the Mississippi River, where values may fall into
the 15 to 25 percent range. Increasing high cloud cover could
limit how much mixing occurs especially west of the Mississippi
River. A weak front moves into the region Tuesday night into
Wednesday with warmer air pushing into the area ahead of the
front. Plan on breezy south/southwest winds across the region on
Wednesday. Fortunately the south southwest winds should usher in
higher dew point air, but will have to watch the moisture return
closely. Plan on highs on Wednesday climbing into the 50s to
around 60. A cold front is expected to slide through the region
Thursday but doesn`t appear to bring significant precipitation to
the area. A baroclinic zone then sets up across southern Nebraska
into southern Iowa into northern Illinois. A series of shortwaves
will move across this zone from Thursday into the weekend
bringing chances for rain, and perhaps some light snow at times,
to areas along and south of Interstate 90. The bulk of the
rainfall now looks like it should fall just south of the forecast
area which is good news given the ongoing flooding concerns,
especially along the Mississippi River.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 549 AM CDT Mon Mar 25 2019

Generally VFR ceilings will clear by mid morning as high pressure
builds in from the northwest. Mostly clear skies and light winds
are then expected through tonight.

&&

.FIRE WEATHER...Today through Wednesday
Issued at 303 AM CDT Mon Mar 25 2019

A very dry airmass moves into the region today with afternoon
relative humidity values falling into the 12 to 25 percent range
along and east of the Mississippi River. Winds should remain light
today, limiting fire weather concerns. The drier air is expected
to remain in place over portions of western and central Wisconsin
on Tuesday with afternoon relative humidity values falling into
the 15 to 25 percent range, with slightly more wind expected out
of the south/southwest. Will have to watch Wednesday closely for
moisture return. South to southwest winds increase with gusts of
25 to 30 mph expected. Afternoon relative humidity values are
forecast to drop to around 40 percent with the anticipated
moisture return. However, if the moisture is delayed there could
be fire weather concerns given the stronger winds.

&&

.HYDROLOGY...Through This Weekend
Issued at 303 AM CDT Mon Mar 25 2019

The Mississippi River will remain the main flooding concern through
the upcoming work week. Temperatures in the 40s and 50s across the
region will lead to plenty of snowmelt. The Mississippi
Headwaters region still has 4 to 6 inches of snow water equivalent
on the ground, so levels will continue to rise. Expect minor to
moderate flooding to develop along much of the river through the
next 7 days, with additional rises likely beyond that.

Some good news is that most of the tributaries will continue to fall
or only rise slightly as most of the snow in the local area has
melted. However, could see some additional flooding in tributaries
in Wisconsin north of Interstate 90, where 1 to 4 inches of snow
water equivalent is still on the ground.

The heaviest axis of rain for late this week into the weekend now
looks to have shifted south of the area. This is good news with
ongoing flooding concerns. Portions of northeast Iowa and
southwest Wisconsin will have the highest chances of see rainfall
amounts of 0.5 to 0.75, but the band of heaviest rain could shift.

&&

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

$$

SHORT TERM...JM
LONG TERM...Wetenkamp
AVIATION...JM
FIRE WEATHER...Wetenkamp
HYDROLOGY...CJA/Wetenkamp


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