Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251907

Area Forecast Discussion
National Weather Service La Crosse WI
210 PM CDT Sun Sep 25 2016

.SHORT TERM...(Tonight through Tuesday)
Issued at 210 PM CDT Sun Sep 25 2016

Surface cold front associated with an upper level trough will
continue its march eastward tonight, firing showers and a few
thunderstorms along and ahead of it. Expecting this activity to be
east of the local forecast area.

Later tonight through Tuesday...spirals of upper level energy will
sweep across the Upper Mississippi River valley as the upper level
trough/closed low meanders east/southeast...while the system`s sfc
low is progged to drop into MI Tue afternoon. With ample moisture to
tap into, expect areas of showers to spark off this forcing. Mostly
across the north tonight-Monday, but shifting to eastern parts of
the forecast area Tue as the sfc low slides across eastern WI. Not
expecting much for amounts, so should not have an impact on current
high/flooding river systems or pose a threat for more areal/flash

Back to Monday...tight pressure gradient builds in from the Northern
Plains...with bufkit soundings suggesting mixing up to 800 mb.
Should be a rather windy day. Observations across the Dakotas
indicating peak wind gusts from 35-45 mph this afternoon. A bit more
favorable setup over there today than across this area for Monday,
but gusts in the wind prone/open areas of southeast MN and northeast
IA in the mid 30s to near 40 mph certainly possible.

.LONG TERM...(Wednesday through Sunday)
Issued at 210 PM CDT Sun Sep 25 2016

GFS/ECMWF remain bullish on an extended period of dry weather...
building in an upper level ridge coupled with a high at the sfc.
Definitely needed for the region.

One point of the interest though is the trough that drops toward the
southeast U.S. after Tue. The GFS favors kicking that off the coast
and letting it go on its way. The ECMWF, however, cuts off the
closed low from the mean flow, gradually meandering it back north to
across the eastern Great Lakes for the weekend. This solution would
put Wisconsin back under some rain chances. The GEM on the otherhand
doesn`t take the trough southeast at all, rather pushes it mostly
due east to across the New England states for the weekend.
Going to lean on the drier solution and keep it dry.

As for temps, they look fairly seasonable for the later half of this
week...right around the late September normals.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1151 AM CDT Sun Sep 25 2016

Late this morning the cold front was thru the KRST area with west
winds and rising/improving cigs. Front was approaching KLSE and will
move thru around 18z. Cigs at KLSE to then improve to VFR between 19-
21z as deep westerly/drying flow spreads across the area. Would then
expect good VFR at both sites thru the rest of the TAF period,
however, area of MVFR/VFR wrap-around strato-cu spreading southeast
across MN on the back side of the sfc-700mb trough axis. these
clouds to spread into KRST around 19z then southeast across the rest
of the area thru the afternoon. Drying/mixing slowly raising the
cigs hgts in this cloud area but did linger some bkn025 clouds at
both KRST/KLSE thru 22-23z. Improvement then thru the late
afternoon/early evening as deeper drying/subsidence from the Dakotas
spreads into the region. Good VFR expected from mid evening thru Mon
as deeper layered/dry NW flow spreads across the region.

NW gradient winds 15-25KT G25-35KT at the TAF sites by later Mon
morning and for Mon afternoon. This with a tighter pressure gradient
over the region and deeper diurnal warming/mixing to around 850mb,
where winds in the top half of the mixed layer will be 30-35kts.




LONG TERM....Rieck
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