Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 200438
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1138 PM CDT Sun Mar 19 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 200 PM CDT Sun Mar 19 2017

Decent low level warm air advection and a north-south running weak
frontal boundary moving across the region this afternoon/tonight.
Not a lot of RH to play to with though, per time/height x-sections
and bufkit soundings. What`s out there is mostly mid level. A little
instability across the far south, but that too is elevated. Lack of
better saturation/forcing keeping pcpn chances low to none for most
of the forecast area. The main kicker for shower/storm chances
should be just south, with the low level jet impinging on the on the
southern tail of the front. That looks like a decent area for
convection (and thunder chances) and short term/meso models agree.
Will hold small pops across the far south for the better part of
tonight.

.LONG TERM...(Thursday through Sunday)
Issued at 200 PM CDT Sun Mar 19 2017

Models have been in good agreement over the past few days with
bringing pcpn into the area Thursday into Friday. Upper level trough
pushes from the desert southwest northeast into the upper
mississippi river valley on friday. GFS hints at a shortwave riding
in the northern flow, dropping into the mean trough across the
region fri. The EC has this feature, but keeps it north. Differences
do continue in placement/timing of the main features, but they all
agree that pcpn is likely...with rain the featured pcpn type.
Time/height x-sections via the GFS and EC point to a good amount of
sfc/near sfc warming, not suggesting colder air until the system is
departing fri night. Along with the colder air could come an eroding
of the depth of the cloud, removing ice and keeping any pcpn type as
liquid. GFS bufkit soundings point to this. Could be a short period
of freezing drizzle in this scenario - if sfc temps can cool enough.

Of note is that NAEFS pw anomalies are +1 to +2 in this time frame,
with GEFS ensemble means around 1 inch. Rainfall of an inch
(potentially 2?) seems like a good bet at this time. Depending on
where it falls, and rates, much of this would runoff into the river
systems, resulting in rises. Could be some hydro concerns for
next weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1138 PM CDT Sun Mar 19 2017

An area of low pressure was over southeast Nebraska late this
evening and will move east/southeast through the night into Monday
morning. This will allow a trough of low pressure to work across
the region. Other than some mid to high level clouds, this trough
should come through quietly with a wind shift to the north behind
it. Any showers and storms tonight are expected to stay well south
of both airports so should have VFR conditions through the
period.

&&

.FIRE WEATHER...Monday through Wednesday
Issued at 225 AM CDT Sun Mar 19 2017

Dry Canadian high pressure builds into the region Monday through
Wednesday bringing low relative humidity values to the area. Winds
look to be fairly light through this period so not expecting Red
Flag conditions at this time. Monday: Areas north of Interstate 90
across much of western into northern Wisconsin will have the lowest
relative humidity values in the 20 to 30 percent range. Tuesday:
Much of western into central Wisconsin will see afternoon relative
humidity values fall into the 20 to 30 percent range again. It`s
possible they will go even lower across central Wisconsin. Tuesday
will have a little more wind to contend with. Expect northwest winds
of 12 to 13 mph with gusts up to 20 mph possible during peak
heating. Wednesday looks to have the lowest relative humidity
values, ranging from 20 to 30 percent for areas along and east of
the Mississippi River, including central Wisconsin. Again central
Wisconsin could see values drop into the teens. Winds will be fairly
light on Wednesday as the high settles overhead.

&&

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

$$

SHORT TERM.....Rieck
LONG TERM......Rieck
AVIATION...04
FIRE WEATHER...Wetenkamp



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