Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 260738

Area Forecast Discussion
National Weather Service La Crosse WI
238 AM CDT Fri May 26 2017

.SHORT TERM...(Today and tonight)
Issued at 238 AM CDT Fri May 26 2017

Main impactful weather concerns are on shower and thunderstorm
chances through the Memorial Day Weekend.

Rain showers will exit the area early this morning as a weak
shortwave trough pushes east of the region. Two shortwaves to keep
an an eye on today as they push through the Upper Mississippi
River Valley. The forecast area may actually end up split between
the two, but we will probably see some rain shower activity with
weak forcing overhead. The northern wave tracks mainly across
central Minnesota into northwest Wisconsin while the southern wave
moves across Iowa into northern Illinois. MUCAPE values may climb
into the 250 to 500 J/kg range by this afternoon as a weak cold
front edges in from the west so we may see some isolated to scattered
thunderstorms during the afternoon hours. The front then stalls
across the area tonight. With light to calm winds across much of
the area tonight into early Saturday morning we will have to watch
for fog potential. Looking at the forecast soundings, it appears
that locations along and east of the Mississippi River stand the
best chances of seeing fog. Will include patchy fog in the
forecast but if skies go clear for an extended time tonight the
fog may become locally dense.

.LONG TERM...(Saturday through Thursday)
Issued at 238 AM CDT Fri May 26 2017

Higher chances for showers and thunderstorms Saturday afternoon
across southeastern 1/2 of the forecast area. Showers and
thunderstorms look to develop along the front Saturday afternoon,
especially across portions of northeast Iowa through southwest
Wisconsin. Afternoon MUCAPE values climb to around 1000 J/kg with 0-
6 km Bulk Shear values right around 30 kts. So a couple of stronger
storms are possible if these CAPE values are realized.  Small hail
and possibly some gusty winds would be the main concerns with any
storms.  A broad trough then dives into the region Sunday into
Monday with continued chances for showers and some thunderstorms.
Chances for thunderstorms will mainly be confined to the afternoon
hours of Sunday and Monday when weak CAPE is present to support the
storms.  The broad trough then persists across the Upper Mississippi
River Valley for much of next week. Weak waves moving through the
northwest flow aloft will bring periodic chances for rain showers
and perhaps a few thunderstorms.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1150 PM CDT Thu May 25 2017

A band of showers continues to make steady progress across the
area late this evening. It has already passed by KRST and looks
like it will miss KLSE to the north. With these moving out, will
keep the forecasts dry and the ceilings VFR. Another round of
showers possibly Friday afternoon. A short wave trough rotating
around the upper level low moving into Saskatchewan will track
across northern Minnesota. Another short wave trough coming out of
Colorado will move across Iowa. The showers should be most
concentrated ahead of these waves with the possibility that they
could split the two airports to the north and south. Will keep the
forecasts dry for now with lowering VFR ceilings.


Issued at 238 AM CDT Fri May 26 2017

Elevated river levels continue along the Mississippi River where
flood warnings are in effect for minor flooding. Those with
interests along the Mississippi River should monitor the latest
river forecasts and statements closely. Also, if you are planning
any recreational activities be aware of these elevated river
levels and watch out for objects in the water that may pose a
threat to watercraft.




SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp
HYDROLOGY...Wetenkamp is the U.S. government's official web portal to all federal, state and local government web resources and services.