Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 241135
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
635 AM CDT Mon Jul 24 2017

.SHORT TERM...(Today through Wednesday Night)
Issued at 234 AM CDT Mon Jul 24 2017

High Impact Weather Potential: Nothing at all through Tuesday, but
thunderstorm chances increase Tuesday night through Wednesday
evening. Lots of questions about storm evolution, but there may be
some lower end risk for a few severe storms, and possibly some
localized heavier rains.

Just a perfect end to the weekend weather-wise yesterday, and if you
enjoyed Sunday`s cooler and less humid conditions, we have another
treat for you today with more of the same. Early this morning,
expansive low level ridging continues to build from James Bay
southward into the local area, with a push of much drier air as
evidenced by dew points in the 50s for many areas at the moment. Per
satellite trends, we have realized some pesky stratus across parts
of the area, blossoming westward the past few hours as the low level
flow has shifted easterly beneath a sharper inversion. Per trends,
we should see that stuff hang around in at least a scattered form
through early afternoon, increasingly shoved over southern portions
of the area as the core of the ridge works through eastern Wisconsin
this afternoon. Further west push of much lower PWAT air strongly
suggests skies will clear generally north/east of La Crosse through
the afternoon, but with a "ring" of cumulus/stratocu perhaps
lingering across southern parts of the area.

Not much to talk about into tonight and Tuesday, but better return
flow does get going Tuesday afternoon mainly west of the
Mississippi. Stronger moisture transport developing into central
Minnesota suggests we may see some convection try to develop out
that way by midday Tuesday along a developing frontal boundary.
Closer to home, just not ready to buy the GFS progs of elevated
convection working into western areas Tuesday morning as it is a
strong outlier for the moment.

Better confidence in convective chances here lies in the Tuesday
night/Wednesday time frame with the approach of a weaker shortwave
or two from the central High Plains. Those features for days now
have been progged to interact with the front and much better
instability building north to deliver increasing chances for
convective developing just to our north Tuesday evening, with that
activity potentially laying over in our direction Tuesday night into
maybe Wednesday as the front also is pushed south. To be honest,
confidence in exact convective evolution remains quite low, as does
the overall risk for severe storms as the best shear the past 36
hours has been modeled to our north, weakening quickly with southern
extent into the local area. However, if something can get a little
more organized to the north, can`t rule out a few broken line
segments perhaps containing a wind risk with better 0-3km shear
north of I-90. PWAT values spiking up around 2 inches or better also
promotes the idea that some heavier rains could set up, though
thankfully the whole pattern looks quite progressive with a nice
push of low level ridging from the north keeping the boundary on a
southward advance.

.LONG TERM...(Thursday through Sunday)
Issued at 234 AM CDT Mon Jul 24 2017

Nothing much to see here...feel free to move on. In all seriousness,
another stretch of fantastic weather appears very likely as we wrap
up the month of July, courtesy of broad low level ridging and a
return to northwest flow aloft. Notable boundary layer drying (read:
low dew points) and a lack of much forcing should keep us dry,
though I suppose a rogue sprinkle or brief shower could
materialize at some point beneath cooler air aloft if a weaker
shortwave migrates through the flow. Regardless, it`s doubtful
anyone will complain about our late week/weekend weather.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 629 AM CDT Mon Jul 24 2017

The only concern is whether the MVFR clouds will move into KLSE.
The HRRR seems to have a good handle with them and it keeps them
just east of KLSE. However, they are not far away and they bear
watching. For now just added a scatted scattered 2K deck and will
watch how they progress during the next hour or two. If they do
not come into the KLSE area by then there will be no issues with
them. If they move in, we will likely have to contend with a 2-3K
deck of clouds through much of the morning.

Meanwhile, KRST will see generally clear skies and light winds.

&&

.HYDROLOGY...
Issued at 234 AM CDT Mon Jul 24 2017

Flooding continues along portions of the Kickapoo, Turkey, La
Crosse, and Trempealeau Rivers, though water levels continue to
fall for most locations. No additional rainfall is expected
through Tuesday, but one or two rounds of thunderstorms are
forecast later Tuesday night into Wednesday. There remains some
potential for localized heavy rainfall during this period, which
could lead to some minor additional flooding. Thankfully, the
midweek weather system remains progressive, allowing high pressure
and dry weather to return quickly Thursday and stick around
through the weekend.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...Boyne
HYDROLOGY...Lawrence


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