000
FXUS63 KARX 171047
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
547 AM CDT Wed Apr 17 2024

.KEY MESSAGES...

- Bands of showers today, but shifting into/north and east of
  I-94 for the afternoon. Blustery, but not as windy yesterday
  - mostly northwest gusts up to 35 mph.

- Another round of showers Thursday, higher chances NE IA/SW WI
  (60- 80%).

- Colder weekend with highs only in the 40s Fri/Sat and at or
  below freezing lows Sat/Sun. Frost and/or a freeze likely for
  many.

&&

.DISCUSSION...
Issued at 200 AM CDT Wed Apr 17 2024

* SHOWERS PERSIST TODAY - more wind, but not nearly as strong as
  yesterday

Stacked low pressure system, currently churning over southern MN, is
pinwheeling bands of showers (not much for thunder) counterclockwise
around it as lobes of shortwave energy spin around it. The low will
make steady progress east today as a 300 mb 100+ kt eastward moving
jet gives it a push. Most of the activity will be north/east of I-94
by the afternoon. Additional amounts upwards of 1/4" expected in
those areas, dropping off to a few hundreths/tenth of an inch south
of there.

After a break from the strong winds in the current overnight hours,
they will pick back up from the northwest this morning...on the
backside of the low. HREF gusts currently topping out mostly from 30
to 35 mph, but do show a 30-50% chance to top 40 mph across portions
of the southeast MN. Don`t see a need for a Wind Advisory at this
time.


* ANOTHER ROUND OF WET LATE TONIGHT/THU

Long range guidance has been in very good agreement with shuffling
an upper level shortwave trough from the PAC NW today, slipping
across the northern plains and then the upper mississippi river
valley by 12z Thu. Sfc low develops in response to the upper level
forcing, but well south - and set to move eastward across the mid
mississippi river valley Thu. Somewhat messy Fgen response, but
noticeable along the leading edge of the shortwave and the
low/attendant sfc front. Most of the low level forcing is in the
south while the initial slug of low level thermodynamics (850 mb
WAA) also suggested to stay south (shifting west-east across IA and
northern IL). 850mb moisture transport also focused southward,
moving along/ahead of the sfc front but only noses as far north as
northern IL. QPF response via the deterministic and models` ensemble
members is mostly post the front and north of the sfc low -
deformation region - where the deeper and lower saturation is
progged to lie. This trend continues to paint the higher rain
chances locally along/south of I-90, decreasing with lower QPF
moving north of there. Not much (if any) instability to play with,
thus thunder chances are minimal. As for rain amounts, LREF suggest
upwards of 1/4" across northeast IA/southwest WI with less than
1/10" north of I-90. Only a 10% chance in the south to reach 1/2".


* COLDER WEEKEND AHEAD - front/freeze for many Fri-Sun mornings

Very persistent signal in the long range models for a slug of cold,
Canadian sourced air to flow in for the latter half of the week,
post the exiting storm system. Sub zero 850 mb temps settle in by
Thu afternoon, holding through 00z Mon. Model blend has very low end
chances (10%) to warm above 50 degrees Fri/Sat while also holding
highs under 60 for Sun. Morning lows Fri in the mid 30s with at or
below freezing favored Sat and Sun mornings. Depending on cloud
cover and winds, frost/freeze adv are likely for portions of the
area. Early season planters will have to take precautions to
protect tender vegetation.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 546 AM CDT Wed Apr 17 2024

Morning showers and a few storms along and east of the
Mississippi River this morning, followed by a drier afternoon.
Ceilings fall to MVFR/IFR briefly, recovering to VFR later
today. Northwest winds build in from the west gusting 25-35
knots this afternoon. Rain chances return Thursday morning.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...KAA