Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 202311

Area Forecast Discussion
National Weather Service La Crosse WI
611 PM CDT SAT AUG 20 2016

.SHORT TERM...(Tonight through Tuesday)
Issued at 250 PM CDT Sat Aug 20 2016

Bands of showers continue across the region, associated with an
upper level shortwave and inverted sfc trough. The system/s
associated sfc low was busy lifting northeast out of eastern WI. No
instability to speak of, so thunder not a concern locally. The
showers will lift northeast with the system tonight, likely keeping
the I-94 and north corridor wet til closer to sunup on Sunday.

Clearing skies for Sunday will bring some welcome sunshine, along
with the a drier day. Temperatures aren/t going to be much better
compared with today...staying cool for late August. Look for highs
in the low/mid 70s Sunday.

A ridge of high pressure builds in for the start of the new work
week, and warmer temps look to return with it. While it looks mostly
dry until a shower/storm threat moves in Tue night (see extended
discussion), warm air advection will mix with the low level
jet/moisture transport across northern parts of the region Monday
night. Scattered showers/storms could spark as a result. Will keep
small pops across the north for now, but these made need to be
increased/expanded if signals remain steady.

In addition, see some threat for fog in the river valleys Monday
morning. Clearing skies and light sfc winds sets the stage for a
good night for radiational cooling. However, the GFS/NAM bufkit
soundings hold onto some 10+ kt breezes just off the surface, which
can halt the spread of fog off the main channel of the Mississippi.
Tribs the better bet for fog at this time.

.LONG TERM...(Tuesday night through Saturday)
Issued at 250 PM CDT Sat Aug 20 2016

Upper level shortwave ridging will lead a shortwave trough into the
area for Tue/Wed. Tue likely the warmest day of the upcoming week as
a result. This warmer, more moist airmass will be tapped into by the
shortwave trough/accompanying sfc cold front on Wed. GFS shows a
decent slug of low level moisture transport ahead of the front,
along with an instability axis and some 0-3km shear. Granted, way too
early to discern a severe risk, but if the system comes in a bit
later on Wed rather than early, the strong/severe threat would be on
the rise. As it stands, Wed is shaping up to be a wet day.

Post the Wed system, cooler air returns for the rest of the week
with highs looking to hold in the 70s - a few degrees below the late
August normals.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 611 PM CDT Sat Aug 20 2016

Still have some lingering showers over the area as the mean long
wave trough moves across the region. The 20.22Z HRRR run continues
to suggest some of these showers could hand on until about 21.02Z
or so with them most prevalent over southeast Minnesota into
northern Wisconsin. Based on this, will include a VCSH for a
couple hour at KRST. The surface low associated with the long wave
trough was over the eastern sections of Michigan U.P. As this
continues to move northeast away from the region, the deeper wrap
around moisture will pull away to the northeast as well. This
should allow the clouds to scatter out this evening and then
remain mostly clear for the remainder of the period.


.ARX Watches/Warnings/Advisories...


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