Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 301149

Area Forecast Discussion
National Weather Service La Crosse WI
649 AM CDT Fri Sep 30 2016

.SHORT TERM...(Today through Saturday)
Issued at 230 AM CDT Fri Sep 30 2016

Main forecast focus in the short term is the pesky upper low and
its journey back north-northwest toward the area. It will spread
plenty of clouds across the region for today and Saturday, along
with the risk for some light showers. The highest likelihood for
any rain will be primarily across WI, with chances diminishing
greatly west of the Mississippi River. Model solutions have been
very similar and consistent for the last several days on this
scenario, but have differed somewhat on just how much rain will
actually manifest as the system battles the drier air in the ridge
axis. Overall only minor adjustments have been made to the
previous forecast, with perhaps just a bit lower rain chances, and
maybe not quite as far to the west. With the clouds and rain,
expect temperatures to be rather fall-like, with the mercury
struggling to make it into the middle 60s.

.LONG TERM...(Saturday Night through Thursday)
Issued at 230 AM CDT Fri Sep 30 2016

The closed upper system will wobble far enough east by Saturday
night that the rain chances should end, and expect cloud cover to
slowly diminish as well. By Sunday, the ridge axis will be allowed
to build in and clouds should begin to diminish. With cool temps,
light winds, and clearing skies, fog could be an issue Monday
morning. Plenty of time to add that to the grids.

All eyes then shift to the west coast trough that is advancing
across the CONUS on Monday. A broad fetch of southerly winds will
being increasing temperatures and humidity to the Upper Midwest
Monday into Tuesday, and thunderstorms appear to be a good bet
from Tuesday night through Wednesday evening as the occluded front
wrapping around the large closed circulation sweeps through. I
suppose there is some risk for isolated severe storms, but it is
hard to fully diagnose this early. Will bear some watching. After
highs in the 70-75 range Mon/Tue, models are indicating some
pretty chilly air wrapping in behind the dynamic fall system.
ECMWF has 850mb temperatures dropping below zero C by Friday
morning (zero to -4 C). GFS is a bit warmer, but not by much
(2-4 C). Will bear watching...


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 645 AM CDT Fri Sep 30 2016

MVFR ceilings, associated with a retrograding low over the Ohio
Valley, will gradually overspread the area through this evening.
These clouds will reach KLSE by 30.15z and KRST by 01.00z.

There are hints in the guidance that the visibilities may also
become MVFR due to BR tonight. Confidence was not high enough to
include them at this time.




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