Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 052351

Area Forecast Discussion
National Weather Service La Crosse WI
651 PM CDT Mon Jun 5 2023

.DISCUSSION...(This evening through Monday)
Issued at 225 PM CDT Mon Jun 5 2023

Key Messages:

 - Isolated to scattered showers/storms mainly near/north of I-90
   through this evening and farther south/west into Tuesday.
   Isolated locally heavy rain possible, but other areas will
   remain dry.

 - A very dry, seasonable period of weather expected for mid-week.

 - Additional showers/storms possible late week (40-60% chance),
   especially Saturday, but widespread impactful rain or severe
   storm chances look low.

This evening-Tuesday:

Hazy skies persist due to smoke from wildfires across eastern
Canada today with stagnant, weak low-level flow. With little CIN
and some boundary layer moisture/destabilization (500-1000 J/kg
MLCAPE) behind a weak surface boundary, especially near/north of
I-90, expect scattered diurnally driven showers/storms this
afternoon/evening. Given weak deep layer wind shear beneath
ridging aloft, storm organization will be limited with the risk
for organized strong/severe storms very low. However, given slow
storm motions, rain amounts could locally exceed 1" in spots, but
many areas will also see little or no rain given the scattered,
pulsy nature of the storms.

Additional scattered showers/storms will remain possible into
Tuesday, especially from southeast MN/northeast IA into southwest
WI. A similar environment to today will exist in these areas on
Tuesday with weak shear, modest destabilization and weak capping.
This environment is not supportive for any organized strong/severe
storms, but locally heavy rain could occur with any slow-moving
storms. The RAP shows the lower-level smoke decreasing later
Tuesday/Tuesday night in the post-frontal easterly flow, although
some haziness could persist from smoke aloft.


A very dry, seasonable airmass will overspread the area for mid-week
as surface ridging centered across eastern Canada noses into the
Upper Midwest. NAEFS precipitable water values are forecast to fall
below the 10th percentile relative to climo during this time with RH
likely to fall near or even below 20% in spots with diurnal
mixing. While winds will remain light, the dry conditions may
lead to somewhat elevated fire weather conditions. Due to the dry
airmass, cooler overnight lows in the 40s and 50s are likely.


Northwest flow aloft will persist late this week across the area
downstream from northern stream ridging centered across the Rockies.
A few embedded shortwave troughs will impact the region late this
week with a cold front expected to slide south around Saturday.
Scattered showers/storms are possible (40-60% chance) later Friday
and especially into Saturday. With modest deep layer shear and
moisture return ahead of the northern stream trough, the risk for
strong/severe storms looks low at this time. High pressure is
forecast to build back south from the northern plains early next
week with seasonable temps and dry conditions returning.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 651 PM CDT Mon Jun 5 2023

MVFR visibilities at KLSE look to improve to VFR after 03z later
this evening with VFR conditions expected to persist thereafter
with KRST anticipated to remain in VFR category.

Chances for pop up showers/storms increase over the region
heading into tomorrow morning and afternoon as a cold front edges
closer to the airports. Confidence is high that there will be
precipitation somewhere in the area, but the isolated to
scattered coverage of the showers keeps confidence low on whether
the airports become directly impacted. So have decided to hold
with the vicinity shower mention.




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