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684
FXUS63 KARX 221804
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
104 PM CDT Wed May 22 2024

.KEY MESSAGES...

- Small shower/storm chances (10-30%) today, highest north of
  I-94. Severe weather not expected.

- Next round of organized showers and storms likely Thursday
  night/Friday. While a few stronger storms cannot be ruled out,
  confidence for organized severe storms is low.

- Seasonable temperatures with potential for unsettled weather
  during the latter half of the holiday weekend.

&&

.DISCUSSION...
Issued at 300 AM CDT Wed May 22 2024

Today-Thursday: Quieter, small shower/storm chances today

The negatively-tilted mid-level trough associated with yesterday`s
severe weather continues to slowly pivot across northern MN
while the cold front has shifted east of the area. A tight
pressure gradient south of the strong surface cyclone and robust
low to mid-level wind fields will keep winds gusty today (25 to
35+ mph), slowly diminishing as the low begins to pull farther
north through the day. Small (10-30%) chances for showers/storms
continues today as a secondary shortwave trough rotates the
base of the broader trough within broadly cyclonic flow and
steepening lapse rates, highest chances north of I-94. Any
showers should diminish by early evening. A dry day is on tap
for Thursday beneath shortwave ridging with seasonably warm
highs well into the 70s.


Thursday night-Friday Night: Shower/storm potential

Another shortwave trough will move from the northern Rockies into
the northern plains Thursday night into Friday with its associated
cold front progressing east with it. Organized showers and storms
are expected with this system in response to mid-level warm/moist
advection ahead of the front, although the stronger synoptic
ascent with the shortwave looks to remain farther north and
west. Seasonably strong mid-level flow and increasing low-level
moisture would support some risk for strong/severe storms ahead
of the front. However, there is uncertainty with the timing of
the front and convective evolution. GEFS-based machine learning
probabilities indicate low (5-15%) severe weather chances mainly
east of the area on Friday, consistent with the past few runs.
However, some guidance is a bit slower, and SPC has included
parts of northeast IA and southwest WI in a low end (level 1 of
5) risk for severe storms on Friday. Regardless, drying is
expected by Friday night behind the front.


Saturday-Tuesday:

A series of shortwave troughs will eject from the Rockies within
quasizonal flow into the Mississippi Valley through the holiday
weekend, eventually resulting in broad mid-level troughing over
the Great Lakes by Memorial Day. This pattern favors near to
slightly below average temps heading into early next week. Given
the uncertainty in placement of the troughs, broad-brushed rain
chances (20 to 50%) persist later Sunday through Tuesday, but
these details will be refined through late week as
predictability increases with these systems. Rain chances likely
will need to be increased for some of these periods in future
updates.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
-- Changed Discussion --
Issued at 1259 PM CDT Wed May 22 2024

Increased winds at 22.18Z TAF issuance are expected to slowly
wane as the responsible upper level trough shifts off to the
east over the Great Lakes through the late afternoon and early
evening hours. Otherwise, VFR expected through the 22.18Z TAF
period. Winds increase again Friday morning albeit not as
strong, eventually turning 10kt sustained gusting 15kt into the
early afternoon out of the south-southwest.
-- End Changed Discussion --

&&

.HYDROLOGY...
Issued at 300 AM CDT Wed May 22 2024

MRMS rain estimates and station reports showed a swath of 2 to 4
inches of rain since yesterday from parts of northeast Iowa
through central Wisconsin, resulting in rises on some rivers,
including the Turkey, Kickapoo, Black, Upper Iowa, and Yellow
Rivers. Minor flooding is expected along parts of the Turkey
River, and is possible along sections of a few Wisconsin
tributaries over the next few days.

&&

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

&&

$$

DISCUSSION...JM
AVIATION...JAR
HYDROLOGY...JM