Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230329

Area Forecast Discussion
National Weather Service La Crosse WI
1029 PM CDT Wed Mar 22 2017

.SHORT TERM...(This evening through Thursday)
Issued at 345 PM CDT Wed Mar 22 2017

At 3 PM, a 1037 mb surface high was centered over central Lake
Michigan. East and southeast winds on the back side of this high
continues to bring very dry air into the Upper Mississippi River
Valley. Dew points ranged from 5 to 15F. Temperatures ranged from
30 to 35F north of Interstate 94 and 35 to 41F across the
remainder of the area. Meanwhile further west, weak to moderate
800 to 600 mb frontogenesis was producing some a light wintry mix
of precipitation from southwest Minnesota southeast into central

The 22.12z models continue to show that an elevated warm front
will move east across southeast Minnesota and northeast Iowa
late tonight and Thursday morning and across western Wisconsin on
Thursday afternoon. The HRRR continues to show that maybe some
elevated showers may develop across western Wisconsin overnight
ahead of this warm front. However with the low levels (sub-cloud
layer) remaining very dry, this precipitation may not make it to
the ground. As a result, kept the forecast dry for the overnight.

During the day Thursday, BUFKIT soundings show that the air mass
will gradually saturate as moisture surges ahead of an approaching
front from the northwest. This will result in the development of
rain across the region. The highest chances will be during the
afternoon. With very dry air still advecting into the area during
the morning, there may be the potential for a light wintry mix at
the onset. However this looks to be brief and should not cause any

.LONG TERM...(Thursday night through Wednesday)
Issued at 345 PM CDT Wed Mar 22 2017

From Thursday night into Sunday, a slow moving upper level low
will move from the Southern Plains into the Ohio River Valley. A
deformation band of rain on the north side of this low will slowly
move south across the forecast area. This deformation band will be
mainly along and north of Interstate 90 from Thursday night into
Friday night, and along and south of Interstate 90 from Friday
night into Sunday. It continues to look like the much of the
instability will remain south of the forecast area. As a result,
kept the mention of thunder out of the forecasts. Rainfall amounts
from this system will likely range from 1 to 1.5 inches. With this
rain spread out of over a long-period of time, only anticipating
in bank rises on area rivers.

With the potential that the southern part of the forecast area
could enter the warm sector of this system on Friday, the
temperatures forecast is rather tricky. The ECMWF ensemble is
showing standard deviations of 4 to 6. For the time being, just
staying close to the ensemble mean. However with that said there
could be potential for a large bust in the temperature forecast
for areas along and south of Interstate 90.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 1029 PM CDT Wed Mar 22 2017

Mid clouds continue to thicken and gradually lower through
sunrise, with VFR conditions transitioning to MVFR through the
afternoon and early evening hours, north of a warm front lifting
into Iowa. Ahead of that front, a smattering of showers and
perhaps even a few thunderstorms is expected, though with plenty
of questions regarding coverage, a "vicinity" mention remains
warranted. Winds will remain from the southeast the next 24 hours,
becoming gusty at both LSE and RST with some gusts to around 25
knots at times from late morning onward. Even with those gusts,
low level wind shear is expected to develop at RST after 00Z.


.HYDROLOGY...(Thursday night through Wednesday)
Issued at 345 PM CDT Wed Mar 22 2017

It continue to look like the area will be in a prolong wet period
from Thursday night into Sunday as a thin ribbon of Gulf of Mexico
moisture is brought northward into the region. Precipitable water
values continue to be 2 to 3 standard deviations above normal.
Rainfall totals will likely be in the 1 to 1.5 inch range. However
with this rain spread out of over a long-period of time, only
anticipating in bank rises on area rivers.




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