Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 182335
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
635 PM CDT Sun Jun 18 2017

.SHORT TERM...(This evening through Monday)
Issued at 236 PM CDT Sun Jun 18 2017

Diurnally driven scattered showers and isolated thunderstorms
within northwest flow aloft this afternoon into the early evening
will dissipate soon after sunset. Mostly cloudy skies and light
westerly wind will allow temperatures to drop into the mid 50s.

Monday will be very similar to today. Steepening low level lapse
rates in the afternoon will result in roughly 500 J/kg of
available CAPE. Some scattered showers/thunderstorms are again
possible region-wide. Otherwise, skies will be partly to mostly
cloudy with highs in the upper 60s to mid 70s. Northwest winds
will continue with some afternoon gusts nearing 25 mph given
roughly 20 to 30 kts within the mixed boundary layer.

.LONG TERM...(Monday night through Sunday)
Issued at 236 PM CDT Sun Jun 18 2017

Shower chances continue Monday night into Tuesday morning as a
Canadian short-wave drops south across the area. Thunder is not
expected with little to no instability in the overnight hours.
A northwest to southeast oriented surface ridge then moves across
the forecast area Tuesday afternoon into Tuesday night, resulting
clearing skies and dry conditions. Cooler conditions with
northwest breezes will continue Tuesday with highs generally in
the 70s.

Fast zonal flow aloft develops across then northern tier states by
mid-week with the majority of short-wave energy near or north of
the Canadian border. That said, one of these waves will push a
warm front across the forecast area on Wednesday, followed by a
cold front Wednesday night into Thursday. Return southerly flow
across the central/northern Plains results in a plume of higher
instability somewhere across the eastern Dakotas/western MN, but
this appears mostly displaced from the warm advective convection
farther east on Wednesday. Instability axis then folds over
across the forecast area Wednesday night ahead of the advancing
cold front. When combined with increasing deep layer shear and mid
level moisture transport, could see some stronger (possibly
severe) storms. Overall, confidence is still low given timing/
location differences between model guidance, but something to
watch over the next couple of days. Wednesday does appear to be
one of the warmer days of the week, with highs topping out in the
mid 70s to near 80 degrees.

Thursday into next weekend, the synoptic pattern shifts again to a
broad trough across much of the central/eastern CONUS. This
pattern will allow for multiple short waves to pass across the
region, although model consensus concerning the timing,
placement, and strength of each wave is poor at this time. Will
stick with consensus POPs, resulting in periodic shower and
thunderstorm chances. For any particular spot, would expect more
dry periods than wet, although temperatures look to be on the
cooler side for late June.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 635 PM CDT Sun Jun 18 2017

VFR conditions are expected through the TAF period. Isolated
showers and thunderstorms will taper off around sunset with the
loss of daytime heating. Isolated to perhaps scattered showers and
possibly a thunderstorm are expected again on Monday. Brief MVFR
conditions are possible near any steadier shower or thunderstorm.

&&

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

$$

SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...Wetenkamp



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