980
FXUS63 KARX 142245
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
545 PM CDT Fri Jun 14 2024

.KEY MESSAGES...

- Hot and humid Sunday into early next week with 60-90+% chances
  for 90F temps Sunday/Monday, especially south and west of
  I-94.

- Showers developing on Saturday with some storms by afternoon
  into early Sunday. A few strong storms possible Saturday
  night into Sunday with hail/heavy rain the primary threats.

- Highest shower/storm chances shift farther northwest late
  Sunday through early next week, but intermittent
  showers/storms are possible (20-50%).

&&

.DISCUSSION...
Issued at 239 PM CDT Fri Jun 14 2024

Shower/Storm Chances:

Areas of showers will begin to increase on Saturday in response
to mid-level warm advection, especially from parts of northeast
Iowa and southeast Minnesota through north-central Wisconsin.
By Saturday night, moisture transport and instability really
begin to ramp up ahead of a stronger shortwave trough. This will
result in areas of showers/elevated storms overnight into
Sunday morning. Although shear above the stable layer is weak,
the increasing instability and elevated mixed layer advecting
eastward early Sunday morning could support some hail in
stronger storms and any wind risk would be contingent on a more
organized convective system surviving eastward into the area. In
addition, precipitable water values exceeding 1.75" and warm
cloud depths over 4 km could result in localized heavy rainfall,
especially from northeast Iowa/southeast Minnesota through
northern Wisconsin.

Southwest flow aloft is expected through much of the week as the
persistent ridging holds to the east. Within this pattern, the
favored axis of heavy rainfall/higher rain chances overall currently
looks to extend from southwest Minnesota/northwest Iowa
northeastward into northwest Wisconsin with a gradient to the
southeast across the Upper MS Valley.

Late Sunday, abundant instability will be present, but the higher
chances for storms may be closer to a surface boundary across
central Minnesota. Little changes with the mean flow pattern
Monday/Tuesday so rain chances are only 10-30% for much of
northeast Iowa through central Wisconsin and 30-50% for
southeast Minnesota into north-central Wisconsin, increasing
moreso to the northwest. Confidence continues to remain low
later in the week given the uncertainty in the evolution of the
longwave pattern, including the ridge strength and surface
boundary placement. Some strong/severe storms could not be ruled
out given the thermodynamic environment through the week, but
mesoscale details will impact day-to-day trends, and overall
with the higher deep layer shear farther north and west across
western Minnesota and the Dakotas, confidence in organized
severe weather locally is low. Heavier rain may a concern,
especially in focused areas of repetitive storm clusters over
the course of the week, again favoring areas west and north.


Temps/Heat:

Mid-level ridging will amplify through early next week across the
Great Lakes/Northeast with the Upper Mississippi Valley residing on
the western periphery of the ridge. Assuming little impact from any
showers/storms, both Sunday and Monday are favored for highs near or
above 90F for much of the area. NBM probabilities for max temps at
least 90F are 75-90% for areas southwest of I-94 on Sunday and 80-
90+% for much of the area on Monday outside of parts of northern WI
and west towards I-35 in Minnesota. With favorable gusty southwest
surface flow and 925 mb temps potentially climbing near 28-29C, max
temps could climb at least into the mid 90s Sunday/Monday, closer to
the NBM`s 75th percentile values. However, again, cloud cover and
any areas of showers/storms could impact temps for some. Heat
headlines could be considered for some areas if the higher values
appear likely.

Confidence is somewhat lower by mid-week given uncertainty in the
ridge position and low-level boundary placement. Global ensembles
show some signal for modestly lower temps for Wed/Thu. There are
also indications that the ridge will retrograde west late in the
week with any respite in cooler air short-lived, but there is
considerable spread in outcomes/temps late in the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 545 PM CDT Fri Jun 14 2024

CIGS: increasing high/mid level clouds overnight into early Sat
morning, and likely holding from 8-12kft through the day into the
night.

WX/vsby: the approach of an upper level weather system and low level
warming will spark areas of showers as we near 00z Sun. Some of the
CAMS models suggest these showers could hold north of the TAF sites,
while others suggest a better chance to get wet. Vsby and accum
impacts look minimal and will leave out of the forecast for the
moment. Scattered to areas of storms become more likely moving into
Sat night as the low level jet and instability start to interact.
Some vsby impacts with any storm.

WINDS: becoming light southeasterly tonight, holding that direction
but picking up Sat morning with some 20+ kt afternoon gusts (moreso
KRST).

&&

.HYDROLOGY...
Issued at 309 AM CDT Fri Jun 14 2024

An active period of weather is expected over the next week with
chances of precipitation across the region expected virtually
every day beyond Saturday. While the best chances of heavy
precipitation remain off to our NW, there are still small
chances of heavy rainfall across our area Saturday night (best
chances along and north of an Austin, MN to Medford, WI line).

Mean precipitation amounts through Wednesday range from around
2.5 to 3.5 inches to our NW across central MN and around 0.75 to
2.0 inches across our local area. While much of this
precipitation is expected across multiple rounds, it will
eventually route into the Mississippi River, which will likely
keep the river elevated through at least the next two weeks.
There is a 10% chance that the Mississippi River reaches Minor
Flood Stage over the next 10 days through Winona (and roughly 25
to 30% chance at Wabasha).

&&

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

&&

$$

DISCUSSION...JM
AVIATION...Rieck
HYDROLOGY...JAW