837
FXUS63 KARX 071753
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1253 PM CDT Sun Jul 7 2024

.KEY MESSAGES...

- Off and on showers and storm chances through the middle of the
  week. Minimal threat for organized severe weather is expected
  at this time.

- Temperatures remaining slightly below average through the
  middle of the week before trending warmer possibly by Friday
  and next weekend.

- The Mississippi River is near crest from Brownsville, MN to
  Guttenberg, IA with locations north noting falling river
  stages. Mississippi River locations are expected to observe
  falling river stages from southwest WI/northeast IA on north
  this week.

&&

.DISCUSSION...
Issued at 347 AM CDT Sun Jul 7 2024

Today - Tonight: Scattered Showers and Storms

The overall synoptic setup on GOES-16 water vapor imagery shows
a closed upper-level low pivoting across the Dakotas into NE
Minnesota with mid-level Q-vector convergence helping to
maintain an area of showers and storms across eastern Minnesota
and western Wisconsin. To our south, a subtle shortwave can be
noted instigating an area of more substantial rainfall and
storms where the nose of 850mb moisture transport is focused. As
a result, could expect some more meaningful rainfall across
portions of northeast Iowa and southwestern Wisconsin this
morning with the 07.00z HREF painting modest probabilities
(40-60% chance) for 0.25" or more in this area. As we continue
through the morning and afternoon, expecting both these features
to generally progress northeast as the overall broader upper-
low begins to become negatively tilted.

Eventually, the aforementioned Q-vector convergence shifts
northeastward into portions of north-central and central Wisconsin
into the afternoon and evening. Consequently, the recent runs of the
CAMs have been trying to resolve some scattered showers and storms
across this area. Some MLCAPE (1500-2000 J/kg) is present in the
07.05 RAP oriented in an axis from SE Minnesota into north-central
Wisconsin. With some effective bulk shear of around 30 kts to work
with across north-central Wisconsin and some hodograph curvature,
could not rule out a strong to severe storm with some small hail and
gusty winds. However, mid-level lapse rates struggling to push 6
C/km would make it fairly challenging for severe criteria hail.

Monday - Wednesday: Additional Chances For Showers and Storms

Heading into the upcoming work week, seasonably cooler
temperatures persist with intermittent showers and storm are
expected as a synoptic trough situated over the region. Likely
with the cyclonic flow in place many of these scattered showers
and storms will be diurnal in nature. Consequently, will keep
chance (20-50%) mention for precipitation chances through
Tuesday. Overall guidance favors light rainfall amounts during
this period as the 07.00z EC ensemble struggles to paint much in
the way of probabilities (0-30% chance) for over 0.1" for any
given round of showers and storms. Of course if storms are slow
moving or repeat, amounts may be locally higher.

As we head into Tuesday night and Wednesday, deterministic
guidance (07.00z GFS/EC/NAM) tries to push some precipitation
into southern Wisconsin overnight Tuesday and early Wednesday
morning with the extratropical low from what is left of Tropical
Storm Beryl that would be placed somewhere in the vicinity of
IL/IN/MO area. Hard to really say where the low will be situated
as there remains very large spread in various members during
this time. The GEFS family appears to be the most aggressive
with any amounts as it paints some lower probabilities (10-30%
chance) for 0.5" or greater of QPF on Wednesday. Currently,
would trend to be lighter amounts similar in southwestern
Wisconsin with guidance keeping the vast majority of the
precipitation shield to our south/east with only wrap around
cyclonic showers as it passes well to our east during the day
Wednesday.

Thursday - Saturday: Trending Warmer and Perhaps Drier

Heading into late week, guidance suggests a building ridge to the
west will help increase heights into late week which should aid in
increasing subsidence and start a warming trend. This is shown in
the 07.00z grand ensemble (GEFS/EC ensemble/Canadian ensemble) with
the inter-quartile range for highs temperatures at La Crosse
reaching between 86 to 90 with a median of 88 degrees, slightly
above average for this time of year. Guidance tries to trend for
drier conditions for Friday and the weekend, however will have to
watch for any subtle shortwaves that try to sneak their way in.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1252 PM CDT Sun Jul 7 2024

A shortwave trough will move through the region from tonight
into Monday. It will bring with it scattered showers and storms.
With little consensus in the CAMs, just went with vicinity
showers from this evening into the early overnight.

On Monday morning, there will be light winds up to 850 mb and
low level moisture up to 950 mb. This might result in some
valley fog. Due to this, added BC FG to the KLSE TAF.

&&

.HYDROLOGY...
Issued at 347 AM CDT Sun Jul 7 2024

The Mississippi River is noting falling river levels from north
of Brownsville, MN with Lake City, MN falling below flood stage.
Locations near crest from Brownsville, MN on south to
Guttenberg, IA. River stages are expected to fall into this
week from northeast Iowa and southwestern Wisconsin on northward
along the Mississippi River. Generally lighter rainfall amounts
of up to around 0.5" from now through Tuesday are expected,
with locally higher amounts possible with any storms that pass
over. May have to watch the remnants of Tropical Storm Beryl for
more substantial rainfall across southwestern WI/northeast IA
for Tuesday night and Wednesday. However, the probabilities for
heavier rainfall with this system remains low as guidance keeps
much of the heavier rainfall farther south and east of the local
area.

&&

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

&&

$$

DISCUSSION...Naylor
AVIATION...Boyne
HYDROLOGY...Naylor