369
FXUS63 KARX 291917
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
217 PM CDT Sat Jun 29 2024

.KEY MESSAGES...

- A couple of rounds of convection expected Monday night into
  Tuesday. This could bring another round of heavy rain across
  the area. Some severe storms could occur Tuesday afternoon
  and evening.

- Additional shower/storm chances occur Thursday into Friday.

&&

.DISCUSSION...
Issued at 217 PM CDT Sat Jun 29 2024

Latest water vapor satellite imagery shows shortwave trough moving
across the Upper great Lakes Region and producing light rain showers
or sprinkles over the region per mosaic radar. The shortwave trough
exits the area Sunday and upper level ridge builds into the forecast
area. Subsidence underneath the upper level ridge will allow for dry
weather Sunday into Monday.

Focus turns to Monday night into Tuesday...Upper level trough digs
over the northern Rocky Mountains and southwesterly flow develops
aloft over the Northern Plains/Upper Mississippi River Valley.
Southerly flow returns near the surface/aloft across the forecast
area and advects moisture into the Upper Mississippi River Valley.
Latest deterministic/ensembles show precipitable water values
increasing to around two inches Monday night/Tuesday across the
forecast area. Combined with decent moisture transport/convergence
and vertical motion associated with impulses embedded in the
southwesterly flow aloft. The showers/storms will be efficient rain
producers and could produce heavy rain across the area. Total
rainfall amounts of 1 to 3 inches is possible Monday night into
Tuesday evening. With antecedent conditions across the area...the
possibility of flash flooding and river flooding is possible.

As far as severe potential...instability does increase across the
southern parts of the forecast area Tuesday afternoon and the latest
29.12z GFS/NAM show 30 to 40 knots of 0-3km shear across the
forecast area. However...the deterministic models show clouds from
Monday night convection linger across the forecast area into
Tuesday. This would inhibit building instability and lower the
severe potential across much of the forecast area. At this
time...depending on how much instability builds across the
area...will determine the severe potential...though it is looking
the better chances for severe potential to be over the southern
parts of the forecast area.

Main forecast concerns Tuesday night into Saturday are periodic
showers/storms through much of the taf period. Upper level flow
remains west to southwesterly across the northern tier United States
through the forecast period. Pieces of energy embedded in the flow
aloft will continue an active weather pattern across the Northern
Plains States/Upper Great Lakes Region. Main difference between the
latest ensembles/deterministic models is timing of upper level closed
low moving across the Northern Plains/Upper Great Lakes July fourth
through Saturday. The upper level closed low has decent
lift/moisture convergence and spread another round of showers/storms
into the forecast area. However...with the timing issues...will
continue with shower/storm chances from July fourth through Saturday
across the forecast area. With clouds/periodic convection through
much of the period...high temperatures will remain near or slightly
below normal in the middle 70s to lower 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1115 AM CDT Sat Jun 29 2024

CIGS: upper level shortwave trough/cold air advection producing a
broad area of clouds across MN, advancing east/southeast. SFC OBS
point to a fair amount of MVFR with 2.5kft. However, the RAP/HRRR
Bufkit soundings continue to suggest mixing with raise those cigs to
VFR as the clouds shift across the TAF sites. KRST could be an
exception for a few hours of MVFR early this afternoon. Skies look
to clear this evening with SKC conditions into Sunday.

WX/vsby: a few light showers/sprinkles coming with the shortwave, but
this light-spotty pcpn looks to hold north of the TAF sites.

WINDS: northwest and gusty this afternoon (mid 20 kts), dropping off
this evening with the loss of daytime heating. Lighter northerly
winds Sunday as the area comes under the influence of high pressure.

&&

.HYDROLOGY...
Issued at 217 PM CDT Sat Jun 29 2024

Minor to moderate flooding continues along the Mississippi River
and will continue into next week. Additional rainfall is
expected Monday night into Tuesday evening. Rainfall amounts of
1 to 3 inches is possible across the area during this time.
River flooding and flash flooding is possible due to antecedent
conditions across the area. Interests along rivers and creeks
should monitor the latest forecast and trends Monday night into
Tuesday.

&&

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

&&

$$

DISCUSSION...DTJ
AVIATION...Rieck
HYDROLOGY...DTJ