080
FXUS63 KARX 060748
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
250 AM CDT Thu Jun 6 2024

.KEY MESSAGES...

- Another windy day with spotty showers. Gusts upward of 35 mph, but
could push 40-45 with any shower

- Colder today (many locations will struggle to reach 70) with cool
conditions persisting through the weekend. Warming next week

- Weekend rain chances with overnight Friday into Saturday morning
harboring higher chances (40%)


.DISCUSSION...
Issued at 250 AM CDT Thu Jun 6 2024

* OVERVIEW:

Upper level trough carving out across the eastern great lakes/new
england states today while an upper level ridge holds across the
west coast. Various shortwaves will re-enforce the mean trough
through the weekend, keeping the region locked into a cooler regime
with periodic shower chances.

The long range guidance starts to break down this blocking pattern
as we move into the new work week with shortwave ridging sliding in
for Monday, then a shift to a more zonal configuration. Heights are
also progged to be on the increase and temperatures should follow
suit - to at or above the early June normals. Bits of shortwave
energy progged to spin across/near the forecast area to provide some
rain chances, but model differences grow past the early part of the
new week, lowering forecast confidence in how those chances will
shake out.


* WINDY, A FEW SHOWERS TODAY - enhanced wind gusts from 40 to 50 mph
  possible with any shower

Bits of upper level energy set to spin southeast across the upper
mississippi valley today. Not nearly as perky as the shortwave
currently exiting east, but continued cold air advection a loft will
foster 1000:850 mb lapse rates of 8-9 C with SBCAPES around 250
J/kg. Skinny instability profiles via bufkit, but enough to aid the
upper level forcing to spark a few showers - perhaps a storm or two.
CAMS are rather spotty with their shower chances, and generally
confined to WI.

Meanwhile, what won`t be spotty is more windy conditions. Relatively
tight sfc pressure gradient persist while uni-directional winds push
well past 500 mb. Winds at the top of the mixed layer around 40 kts
in the RAP and HRRR could/should result in gusts upwards of 30 to 35
kts. Latest HREF paints 50-70% chances for 35 mph winds across
southeast MN/northeast IA, lower east of the Mississippi River.
However, HREF potential for 40 mph or greater is much much less and
mostly tied to any shower that would develop. Good agreement amongst
the suite of short term models that comprise the HREF. All in all,
short term guidance points to a windy day, but not necessarily one
that would need a Wind Advisory. With convective potential much less
today (in chance and coverage), enhanced winds gusts should also be
more spotty.


* WEEKEND RAIN CHANCES - mostly showers with low end thunder threat
  (< 20%)

Medium range guidance is in good agreement with stretching elongated
shortwave energy across the region Friday night/Sat morning, but
with some disagreements in placement. Layered Fgen response with the
shortwave, but sfc convergence doesn`t appear very robust. Not much
for instability either, although that does perk up a bit for the
afternoon with cold air a loft - but post the departing shortwave.
All said, NAM/GFS/EC all favor an area of showers tracking across
the region overnight Fri through Sat morning. Current model blend
only paints 20-40% rain chances and is on the low end of the
guidance. The bulk of the EPS and GEFS members drop at least light
QPF with solid agreement from the deterministic runs (including the
NAM). The blend likely suffers from some of those areal differences
in QPF and expect it will catch up (increase those chances) as track
of the system comes into more agreement. Will ride the blend but
expect an uptick (probably 60+% chances for some locations) if the
models persist in their current outlay.

For Sunday, cyclonic flow a loft persists and could swing weaker
ripples across WI. Coupled with the cold air a loft, weak afternoon
instability could work with the upper level lift to spark a few more
showers.


* COOL WEEKEND AHEAD - but warming for next week

Cooler air flows across the region today as an upper level trough
digs over the eastern Great Lakes. 850 mb temps set to drop from
around 13 C from Wed afternoon to 6-8 C by 00z today. Good consensus
in the models with holding onto the colder air through the weekend
as the trough holds fast in the east. Today currently looking like
the coldest of the bunch with HREF probabilities of warming above 70
only 20-30% for parts of NE IA. Roughly 5 to 10 degrees below normal
for highs expected through Sunday.

As we move into the new work temperatures will start to rebound with
the expectation of increasing heights and the exit of the trough
eastward. 50% of the GEFS and EPS members suggest highs will warm
back into the 80s as we slide into the latter half of the new week,
with the upper 10% hinting that some 90s will be possible by next
weekend.


&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1052 PM CDT Wed Jun 5 2024

As diurnal heating occurs on Thursday, a 4-6K deck of clouds will
develop during the late morning and continue into the afternoon. The
sustained winds will be in the 15 to 25 knot range and wind gusts
will range from 25 to 40 knots.

With the loss of diurnal heating on Thursday evening, the clouds
will dissipate and the winds will decrease.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION.....Boyne