Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 292325

Area Forecast Discussion
National Weather Service La Crosse WI
625 PM CDT Thu Sep 29 2016

.SHORT TERM...(This evening through Friday)
Issued at 242 PM CDT Thu Sep 29 2016

Latest water vapor satellite imagery indicates closed upper level
low over the Ohio River Valley and upper level ridge over Northern
and High Plains. Latest 19z surface analysis shows dry
northeasterly flow over much of Wisconsin and eastern Minnesota
and is producing mostly sunny skies across the forecast area per
latest visible satellite imagery.

Tonight into Friday...The 29.12z GFS/NAM are in decent agreement in
lifting upper level closed low northward and wraps low level
moisture into the eastern areas of the forecast area after 06z
Friday. The deterministic models indicate increasing lift/moisture
in association with the first impulse wrapping around the upper
level closed low and to impact the eastern to southeast parts of
the forecast area after 18z Friday. Scattered showers are
expected across this part of the forecast area Friday afternoon.
Have kept chance of showers over the eastern and southeast parts
of the forecast area.

.LONG TERM...(Friday night through Thursday)
Issued at 242 PM CDT Thu Sep 29 2016

Scattered shower chances increase mainly east of the forecast
area Friday night into the upper level closed low
wraps a series of shortwaves into the forecast area. The 29.12z
GFS/NAM/ECMWF show slight differences in how far west
precipitation/moisture will be Friday night into
models differ on placement of the upper level closed low.
However...there is a good chance of showers east of the
Mississippi River late Friday night into Saturday morning.

Upper level closed low moves into the eastern Great Lakes Region
and upper level/surface ridge builds into the Upper Midwest
Saturday night into Sunday. Clouds are expected to diminish
across the forecast area and dry weather will prevail.

Main forecast concerns are precipitation chances Tuesday night
through Thursday. The 29.12z GFS/ECMWF/GEM are in good agreement in
building upper level ridge into the Upper Midwest and Great Lakes
Region through 00z Wednesday. However...significant differences
occur between the deterministic models with the strength of the
upper level ridge Monday into Tuesday and the upper level
trough/closed low ejecting out into the central United States
Wednesday into Thursday. This will have impacts on timing of
shower/thunderstorm chances Tuesday night into Thursday. The
forecast area will remain dry Sunday night through Tuesday.
Then... shower/thunderstorm chances increase Tuesday night through
Thursday with increasing moisture and forcing/lift across the
forecast area. Temperatures through the forecast period will be
slightly above the 29.12z GFS/ECMWF/GEM show decent
warm air advection under upper level ridge.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 625 PM CDT Thu Sep 29 2016

High pressure remains in control tonight with clear skies and
perhaps a little fog, particularly in the river valleys. Given our
warmer start out at RST today, not sure they will tank below 1/2
mile as they did last night, but can still envision a period of
MVFR or even IFR visibility in some fog from 08-13Z while winds
aloft remain just too strong for LSE to fog in. Otherwise it
appears lower clouds off to our east associated with a slow-
moving cutoff low will meander back westward late tonight into
Friday, with initial VFR ceilings likely dipping into MVFR range
through the day, latest at RST. Any showers associated with that
system look to hold off until late Friday night or even Saturday
at the terminal sites.




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