Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 282325
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
530 PM CST Mon Nov 28 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 235 PM CST Mon Nov 28 2016

Primary forecast concerns are on rain chances tonight with the
potential for an isolated thunderstorm. Focus then turns to chances
for rain and snow Wednesday into Wednesday night.

Periods of rain showers and perhaps an isolated thunderstorm will
continue across the area late this afternoon into this evening. The
main hazards from any thunderstorms will be lightning and perhaps of
small hail. An upper low, currently positioned along the North
Dakota/Minnesota border, will meander east over the next few days
and will be the key weather feature to watch. A cold front will
edge eastward across southeast Minnesota and northeast Iowa late
this afternoon into this evening with scattered showers and
thunderstorms along it. Much of this activity will diminish after
sunset. However, further to the east, across western into central
Wisconsin, 850 mb moisture transport will help to keep periods of
showers and perhaps an isolated thunderstorm going at least
through the mid evening hours. The shower activity will taper off
after midnight as drier air aloft starts to edge in from the west.
Areas south of Interstate 90 should see some clearing skies late
tonight into Tuesday morning, but most areas across southeast
Minnesota through north central Wisconsin will remain cloudy.

.LONG TERM...(Tuesday night through Monday)
Issued at 235 PM CST Mon Nov 28 2016

The upper low will continue to influence the weather across the
Upper Mississippi Rive Valley Tuesday night through Wednesday. A lobe
of vorticity moves in late Tuesday night into Wednesday bringing
some light rain and snow chances to the area. The cooling trend
will continue with high temperatures falling into the upper 30s to
around 40 on Wednesday. Light rain and snow chances continue into
Wednesday night and Thursday as the low continues to meander east
across the Great Lakes.

For Thursday night into Friday we will still be under the influence
of the pesky stacked low, which by this time should be located over
Quebec. Wouldn`t be surprised to see a few sprinkles or flurries
continuing into Friday with the last pieces of energy rotating
through, but will keep the forecast dry for now. Models continue to
hint at a brief period of ridging late Friday into Saturday. From
there, model consistency breaks down drastically. The big question
will be what happens with a closed upper-level low over the Desert
Southwest. Both the ECMWF and GFS place the low at the base of a
positively-tilted longwave trough at 12Z Saturday. The ECMWF keeps
the low within the main flow of the longwave trough, pushing it over
Texas by 12Z Sunday and towards the Upper Midwest by 12Z Monday. In
contrast, the GFS cuts the low off and parks it over northern Mexico
through Sunday and brings a shortwave trough through our area late
Saturday, followed by a period of ridging through Monday. This
results in a difference between a potential snowstorm vs. high and
dry for Sunday night into Monday. Will go with low chances for
precipitation to account for both the GFS shortwave late Saturday
into Sunday and the ECMWF low late Sunday into Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 530 PM CST Mon Nov 28 2016

Cigs/WX: sfc front marching through the area, still sparking a few -
shra into the early evening hours. Meanwhile the main mass of rain
has already shifted east of the taf sites. Will hold some -shra
threat into early/mid evening at both sites.

Cigs the bigger concern through Tuesday. Narrow "dry slot" just post
the approaching sfc - resulting a brief period of skc/sct
conditions. Sfc obs and rh fields then slide vfr cigs back
in...eventually dropping to mvfr at krst. These low cigs currently
look to stay just north-west of klse during the forecast period.
Confidence not overly high, but looks the most likely right now.

Winds: look for a quick shift to more southwest with the passage of
the front this evening. Speeds will stay close to 10 kts through Tue
afternoon.

&&

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

$$

SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp/MAH
AVIATION...Rieck



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