Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 172020
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
322 PM CDT Tue Apr 17 2018

..SHORT TERM...(Tonight through Wednesday Night)
Issued at 322 PM CDT Tue Apr 17 2018

Focus is on incoming storm system which will bring snow to the area
from Wednesday morning through Wednesday evening. GOES-East water
vapor imagery shows the incoming storm currently crossing the MT/WY
Rockies. This wave will continue to chug east through the Plains
tonight and then along the IL/WI border during the day Wednesday.

Model diagnostics bring a potent lobe of PV-advection and increasing
upper level difluence into the area early to mid-morning along with
NAM showing a respectable 2-5km MUCAPE axis nosing into northeast
IA/far southwest WI. This will lead to a few thunderstorms down
across that area with perhaps some sleet mixing in with moderate to
heavy snow rates. This forcing shifts east of the area by afternoon
with the area slipping into the deformation area of the mid-level
low in the afternoon/evening.

Current total snowfall amount thinking is for 3 to 8 inches with the
highest amounts extending from northeast IA into central WI. As a
result, Winter Storm Warnings and Winter Weather Advisories have
been posted. See the Warnings, Watches, and Advisories section below
or see our internet homepage at www.weather.gov/lacrosse for latest
headline details.

.LONG TERM...(Thursday through Tuesday)
Issued at 322 PM CDT Tue Apr 17 2018

Things are looking up in the extended as a strong ridge of high
pressure builds across the region. Daytime temperatures warm from
the 40s on Thursday to well into the middle 50s/near 60 by Monday.
Nighttime lows look to be in the 20s/30s. With these warming
temperatures, look for significant melting of the snowpack in place
across the area. This will have an impact on runoff and hydrology
concerns. More detail on this is highlighted below in the Hydrology
section. A chance of rain enters the picture Monday night into
Tuesday as a mid-level trough and surface cold front push
southeastward into the region.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1236 PM CDT Tue Apr 17 2018

VFR conditions expected through tonight as high pressure remains in
control across the area. Low pressure will then move in Wednesday
morning, spreading snow/IFR conditions into KRST by 14z and
snow/MVFR conditions into KLSE by 16z. Northwest winds will be less
than 10 kt through this afternoon, becoming northeast at 5 to 10 kt
overnight.

&&

.Hydrology...
Issued at 322 PM CDT Tue Apr 17 2018

Warming temperatures will produce significant melting of the
snowpack in place across the area, leading to a good amount of
runoff into area streams and rivers. Besides the Trempealeau River
Dodge possibly exceeding flood stage this weekend, the rest of the
area streams and rivers are expected to just see significant within-
bank rises. Those with interests or property close to streams and
rivers will want to stay up to date on latest river forecasts.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 7 AM Wednesday to 1 AM CDT Thursday
     for WIZ032>034-041-042-053>055-061.

     Winter Weather Advisory from 10 AM Wednesday to 1 AM CDT
     Thursday for WIZ043-044.

MN...Winter Storm Warning from 7 AM Wednesday to 1 AM CDT Thursday
     for MNZ086-087-094-095.

     Winter Weather Advisory from 7 AM Wednesday to 1 AM CDT Thursday
     for MNZ079-088-096.

IA...Winter Storm Warning from 7 AM Wednesday to 1 AM CDT Thursday
     for IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....DAS


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