Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 010403

Area Forecast Discussion
National Weather Service La Crosse WI
1103 PM CDT Fri Sep 30 2016

.SHORT TERM...(This evening through Saturday)
Issued at 251 PM CDT Fri Sep 30 2016

Latest water vapor imagery indicating upper level cut-off/closed
low over the Ohio River Valley and shortwave ridge over the
Northern and High Plains. Pieces of energy rotating around the
upper level cut-off low is producing isolated/scattered showers
over parts of eastern Wisconsin and Illinois per latest mosaic

The 30.12z GFS/NAM/ECMWF are in good agreement in lifting upper
level closed/cut-off low into the Great Lakes Region tonight into
Saturday. A series of impulses wrapping around the upper level
cut-off low will continue to advect moisture into the area. Weak
lift in association with the impulses and dry air over much of
the forecast area...will inhibit the potential for showers across
the forecast area. With the better chances mainly east of the
Mississippi River and occurring late tonight into Saturday

.LONG TERM...(Saturday night through Friday)
Issued at 251 PM CDT Fri Sep 30 2016

Upper level cut-off/closed low tracks into the eastern Great
Lakes Region Saturday night and allows any isolated/scattered
showers to be east of the forecast area. Then...upper level ridge
amplifies/builds over the central United States/Great Lakes region
and provides dry weather across the forecast area Sunday into
Monday. Temperatures should warm into the 60s to around 70 degrees
Monday. If skies clear over the forecast area Sunday
night...there is the potential for fog formation in river the 30.12z GFS/NAM bufkit soundings show inversion
developing and deep layer light winds. At this time...have left
mention of fog out of the forecast.

Main forecast concerns are precipitation chances Tuesday night into
Thursday. Considerable differences occur between the deterministic
30.12z GFS/ECMWF/GEM through the the models differ on
strength of the upper level ridge amplifying over the central
United States Monday night/Tuesday and placement/timing of the
upper level closed low/trough slowly moving into the Upper Midwest
Tuesday night into Thursday. This will have impacts on timing of
the shower/thunderstorm chances and how widespread the
showers/thunderstorms will be across the forecast area Tuesday
night into Thursday. The 30.12z GFS/ECMWF/GEM continue to show
strong warm air advection out ahead of the upper level closed
low/trough Tuesday and will provide above normal temperatures
across the forecast area Tuesday. Slightly below normal
temperatures are expected later in the cooler air
filters into the forecast area behind surface front/upper level


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1103 PM CDT Fri Sep 30 2016

VFR stratus remains over the TAF sites. However, easterly flow around
low pressure in Indiana continued to bring moisture westward, with
IFR ceilings at Viroqua and MVFR at Sparta. These lower ceilings
will move into the TAF sites during the early morning hours as the
easterly flow persists. Additionally we could see some MVFR BR
impact the sites around sunrise. Cannot rule out a few light
showers/drizzle as well during the BR time period, especially at
KLSE. Daytime heating should help to mix out the BR and bring
ceilings up to MVFR. Further increase to VFR is expected in the
evening as dry air begins to flow in from the northeast.




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