Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 132325

Area Forecast Discussion
National Weather Service La Crosse WI
625 PM CDT Tue Mar 13 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 202 PM CDT Tue Mar 13 2018

Early this afternoon, surface high pressure was centered across
eastern South Dakota with clear skies from western Wisconsin
westward into the northern plains. Widespread cloud cover along with
some snow shower/flurry activity remained across central and eastern
Wisconsin under colder mid-level temps with steep low-level lapse

For tonight, surface high pressure will drift southeastward.
Although residual cloud cover over central Wisconsin will erode,
some increase in mid/high cloud cover will occur with strengthening
warm advection ahead of a shortwave trough diving towards the
western Great Lakes.

The associated cold front will swing through on Wednesday.
Moderating 925 mb temps ahead of the front and plenty of sunshine
should help temps climb into the 40s in most areas, with some low
50s possible.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 202 PM CDT Tue Mar 13 2018

The medium range models are starting to show better agreement on
the evolution of the upper air pattern heading into the upcoming
weekend. Once the short wave trough rotating around the eastern
upper level low moves past the region, the upper level ridge axis
currently over the Rockies will slide east and be the dominant
feature through Thursday night. The models are still showing a
short wave trough to get ejected out of the large system over the
eastern Pacific and are now in much better agreement with the
handling of this system. An upper level low is expected to form
over Colorado or Kansas as the short wave trough emerges from the
central Rockies. This system is then expected to cut through the
Ridge as it eventually gets drawn in the southern portion of the
large eastern trough. The upper level ridge will then temporarily
re-establish itself over the the Midwest for the weekend. Another
piece of the Pacific system is then expected to emerge from the
Rockies, but farther to the north coming across Nebraska or South
Dakota. Just how far east this system will make it before turning
to the southeast is still not handled well by the models. The
13.00Z ECMWF continues to show a strong northern stream system
rotating around the low in the eastern trough that deflects the
Pacific system and takes it south of the area. The 13.12Z GFS
continues to not show this northern stream system which allows the
Pacific system to move across at least the western sections of
the before dropping to the southeast as it gets absorbed in the
long wave trough over the east.

With this current pattern evolution, the precipitation from the
first Pacific short wave trough is now expected to stay south of
the area Friday and Friday night. However, it will not be that far
south and any subsequent northward shift on the track could bring
these chances back into the southern sections of the forecast
area. Saturday and Sunday also look to be dry before the
precipitation chances from the second Pacific system start to
arrive Sunday night and then continue into Monday night.
Temperatures through the period should be near the seasonable
values but maybe not quite as warm as previously expected. Highs
now look to generally be in the 30s and 40s through Friday,
warming a bit into the 40s for the weekend before dropping back
into the 30s and 40s for the start of next week. With this
temperature regime, the precipitation type for next week looks to
be a rain/snow mix during the day going back to all light snow at


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM CDT Tue Mar 13 2018

High pressure will drift south and west of the forecast area
through tonight, allowing northwest wind this evening to become
light from the southwest or variable overnight. Southwest wind
will then become a bit stronger Wednesday with some gusts into
the lower 20 kt range at KRST. A dry cold frontal passage late in
the period will result in a wind shift back to the northwest.
Besides some cirrus this evening and overnight, expect mostly
clear skies through Wednesday morning. There then could be some
scattered cumulus Wednesday afternoon in the 2000 to 4000 ft agl




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