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631
FXUS63 KARX 160939
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
439 AM CDT Sun Jun 16 2024

.KEY MESSAGES...

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- Storms continue this morning. A few strong storms with periods
  of heavy rain downpours and lightning. Gusty winds and storms
  with small hail could develop before exiting the area.

- Very warm to hot and humid today through Tuesday. Highs in the
  80s to lower 90s.

- Storms re-develop tonight. Highest chances appear north of I90
  where severe storms (15% chance) will be possible along with
  locally heavy rain.
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&&

.DISCUSSION...
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Issued at 400 AM CDT Sun Jun 16 2024

Overview:

Water vapor satellite imagery, 500mb heights, and lightning showed
several areas of convection at 07Z.  A 500mb ridge was over the
southeast U.S. with the shortwave trough from MN/IA toward
Kansas City. A stronger closed low was noted over Saskatchewan.
Three convective complexes were noted with the first shortwave
trough and another well-organized MCS was noted over Alberta
into North Dakota. Taking a look at the WSR-88D mosaic loop,
things were fairly quiet with a large area of rain over the
Upper Mississippi Valley at 21Z. Through 03Z, convection lit up
over the Missouri River Valley into southern Minnesota with more
scattered convection farther east. The convection has continued
with three different areas over MN, IA, and northeast KS. A
north to south narrow line of convection extended from western
WI into east Iowa developed from 06-07Z. The 16.00Z MPX sounding
was quite moist with 1.59" of precipitable water (PWAT). The
latest subjective surface analysis had a double- front with a
surface warm from in the pressure/temperature pattern from
southern MN int southwest WI. The deep moisture with mid-60s to
lower 70s dewpoints axis was over western Missouri with the main
warm front there. These fronts trailed northwest to a cold
front over central North Dakota. With the strong moisture
transport and forcing the heavier rains have been just west of
the forecast area. Some local spots per the radar picked up 2.5
to 5" of rain.

Through Monday:

The shortwave trough will continue to lift northeast and push across
WI this morning.  Strong moisture transport continues this morning
and shifts toward the Great Lakes by 18Z. The ARX VAD wind
profiler showed a southwest wind at 50kts at 4000ft at 0743Z.
The 900mb wind progs have another area of strong low level winds
over western Iowa (45 to 60kts) which is forecast to continue
through 15Z then weaken. The mesoscale vorticity center (MCV)
over Iowa is forecast to continue to lift northeast across the
forecast area with the shortwave. Meanwhile, the surface warm
front pushes east across Wisconsin through 00Z with the cold
front working into Minnesota. The thermal ridge with very warm
temperatures at 700mb builds in and shuts down the bulk of the
precipitation over the local area with decreasing clouds and
warming temperatures in the 80s to lower 90s. Southwest winds
strengthen with gusts 15 to 30 mph. The PWAT maximum around 2"
should be over the local area, but shifts toward GRB`s area by
18Z. Will continue to carry high pops this morning with
precipitation ending from west to east. Have not seen much in
the way of severe weather with this area of storms. With the
limited instability would think the heavy downpours of rain and
lightning would be the main hazards.  Additional rainfall
through 18Z could range from less than a tenth of an inch from
west of RST to .25 to 1" for parts of WI. The MCV over Missouri
will likely track northeast as well. For now, this feature looks
to remain generally south of the area. Possibly per the 16.07Z
HRRR tracking across IL.

The questions for this afternoon and tonight will revolve around how
warm temperatures will get and how storms will re-develop/where
the surface boundary will lay up/where will elevated storms
develop/how far south? The CAMs handle the weather tonight
differently with most on the dry side except for the RAP through
01Z. The FV3 has isolated storms developing. Through 06Z,
several of the CAMs develop a west to east line of convection
with the HRRR more toward northern WI and the ARW/NAMNest
farther south toward I90. There is uncertainty in how far south
the storms will develop and due to the Moderate to High
instability of 3000-5000J/kg of MUCAPE and sufficient shear,
severe storms will be possible. Moisture transport increases
across Nebraska and shift into the forecast area, with the
northern forecast area generally near the axis of instability.
The low level jet is forecast to strengthen 45 to 50kts across
Nebraska and Iowa, thus storms could develop farther south into
southern MN. The HRRR neural network for severe storms is
generally north of the forecast area. Tonight will continue to
place highest pops across our northern counties adjacent to
MPX`s area.

The Extended:

The front lifts north Monday as the West Coast trough deepens.  The
cold front moves southeast into the forecast area Tuesday into
Wednesday. Temperatures are forecast to remain very warm to hot
in the 80s to lower 90s and continued muggy in the 60s to lower
70s. The Day 3 SPC outlook is mostly northwest for the SLIGHT
risk of severe weather, however this may shift south in the
future with instability and strong moisture transport ahead of
the front. In addition, additional rainfall is expected, with
already moist soils. Will continue to monitor heavy rain
potential.

The upper level flow is flatter Wed-Sat, thus prone to shower and
storm chances for the end of the week with more seasonably
temperatures in the 70s and 80s.

&

.HYDROLOGY...
Issued at 4 AM CDT Sun Jun 16 2024

Due to the repeated storms, we`ll need to assess the flood
potential with each shift. The 3hr FFG remains around 2 to 3
inches. Although heavy rain fell northwest of the local area
Saturday night, locally, amounts were generally less than an
inch. Some areas could see another inch this morning before
this wave exits the area. We`ll need to monitor the rainfall
rates due to the high efficiency. The storms continue lifting
northeast at a pretty good clip, thus heavy rain should be
localized. Tonight the heavier rainfall is again forecast north
of the local area with more rain Tuesday night. With each rain
event over MN, the probabilities for flooding increase for the
Mississippi River. The Mississippi River should remain elevated
for the next couple of weeks. There is a 30% chance that the
Mississippi River reaches Minor Flood Stage over the next 10
days through Winona (and 50% chance at Wabasha).
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&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1025 PM CDT Sat Jun 15 2024

CIGS: RAP and NAM still favoring a period of MVFR at the TAF sites
moving through the overnight, mostly tied to areas of shra/ts. GFS
and HRRR not as suggestive. Not much support from downstream obs,
but rain and increasing low saturation favor the low cigs and will
trend both TAF sites this way. Expect a scattering of the deck as a
warm front pushes north of the TAF sites later Sun afternoon.

WX/vsby: widespread shra/ts kicked off a few hours earlier than prev
forecast as low level jet worked on various sfc boundaries. The pcpn
will persist through the overnight night, with some consensus in the
CAMS for clearing the pcpn east between 12-14z Sun.

Warm front lifts north of the TAF sites Sunday afternoon, and where
it ultimately lays up will be key for where further shra/ts are more
likely - namely along/north of it. South of the boundary the
atmosphere will be capped. Mixed messages in the models keeping
forecast confidence on the low-end for how this plays out. For the
moment, will keep the rain north of the TAF sites, adjusting based
on later model runs/trends.

WINDS: southeast becoming more southerly for Sunday. Expect to stay
10+ kts sustained through the period with gusts mostly in the
low/mid 20 kts. Increasing low level jet will bring LLWS into the
picture at KLSE for a few hours after 06z tonight.

&&

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

&&

$$

DISCUSSION...Zapotocny
AVIATION...Rieck