Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 291942

Area Forecast Discussion
National Weather Service La Crosse WI
242 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 18Z TAFS through 18Z Friday afternoon)
Issued at 1155 AM CDT Thu Sep 29 2016

The large area of high pressure will remain over the Upper Midwest
through tonight. This will continue to provide VFR conditions and
there will be enough of a gradient between this high and the
surface low over the Ohio River Valley to keep any fog from
forming. The low to the south will start to drift back to the
north and by Friday morning it should be close enough to start
pushing some clouds back into the region. Current observations on
the north side of this low indicate MVFR ceilings and the 29.12Z
NAM forecast soundings support these moving into KLSE Friday
morning. Some potential they could also make it to KRST by late
Friday morning, but for now will just stay with a scattered layer
coming in.




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