Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231718
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1218 PM CDT Fri Jun 23 2017

.SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Fri Jun 23 2017

23.08Z surface analysis shows a cold front just south and east of
the forecast area...from near Green Bay to Des Moines. A band of
showers and thunderstorms will continue to push east-southeast
with this boundary early this morning.

For today, temperatures will be a bit cooler with highs in the 70s,
but dewpoints will be noticeably drier in the wake of yesterday`s
widespread showers and storms. Partly to mostly sunny skies this
morning will give way to increasing diurnal cumulus this afternoon
as a quick moving short-wave from SD races across the region.
With roughly 500 J/kg of available MUCAPE, cannot rule out a few
isolated thunderstorms. As a result, added 20 POPs this afternoon
across the entire forecast area for a few hours to coincide with
peak heating. Today will also be a bit breezy with 25 to 30 kts in
the mixed boundary layer. Expect some afternoon northwest gusts
up to 25 mph, especially west of the MS River.

With light winds, temperatures tonight will be dependent on cloud
cover, which may hang around this evening and into the overnight,
especially across western WI. For now, lows in the lower to mid
50s seem reasonable.

.LONG TERM...(Saturday through Thursday)
Issued at 320 AM CDT Fri Jun 23 2017

Northwest flow aloft will persist through the weekend with three
distinct short-waves moving across the forecast area. Saturday`s
wave will be the strongest, followed by weaker waves Saturday
night and Sunday. This will result in shower and mainly afternoon
thunderstorm chances each day. Severe weather is not expected,
although a few storms could become a bit more energetic,
especially Saturday as deeper shear increases for a short period
with the stronger wave aloft. Afternoon MUCAPE both days will
generally remain at or below 1000 J/kg, but enough for at least a
few thunderstorms. It will be a rather cool weekend for late June
with daily highs mainly in the 60s.

Yet another short-wave drops south from Canada on Monday with
additional shower and isolated thunder chances. Temperatures will
be a bit warmer, but still well below normals with highs in the
mid to upper 60s. Short-wave ridging moves in for Tuesday with
high pressure at the surface, resulting in the only fully dry day
of the upcoming work week. Temperatures will rise into the mid
70s with winds finally shifting to the south.

Wednesday through Friday, flow becomes a bit more zonal across
the northern tier states with poor model agreement on the timing
and placement of additional waves. A more prominent cold front
looks to move across the region sometime on Wednesday, but the 00Z
GFS/ECMWF differ on timing by at least 12 hours. Will follow a
model consensus at this time, which generally results in broad
brush 30 to 60 POPs. The overall pattern, however, does support
slightly warmer temperatures with highs at least back into the
70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1218 PM CDT Fri Jun 23 2017

The 4K-6K ft stratocu deck is on track to move across the taf sites
this afternoon into early this evening. Deeper diurnal mixing ahead
of it, along with a tighter pressure gradient to result in NW winds
12-18kt G20-25kt thru the afternoon.

Scattered diurnal SHRA and isolated TSRA also still on track to
develop/move across the area this afternoon into early this evening.
These already showing up on radars NW of the area. Did carry a VCSH
at KLSE 20-24z, otherwise given the sct/isolated coverage, left
mention of the SHRA/TSRA out of the tafs for now. NW gradient winds
of 10-12kts expected to persist thru the night, keeping any BR/FG
in the 09-13z time-frame to a minimum.

&&

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

$$

SHORT TERM...Rogers
LONG TERM....Rogers
AVIATION.....RRS



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