Special Weather Statement, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
233 PM CDT Tue Apr 16 2024

.KEY MESSAGES...

- Severe weather potential continues into early evening. A
  tornado watch remains in effect for parts of northeast Iowa
  and southern Wisconsin.

- Potential for storm total rainfall of 1 to 2" continues. Even
  outside of storms, strong and gusty east winds 35 to 50 mph
  possible through this evening. Northwest gusts 25 to 35 mph
  Wednesday. A wind advisory continues for much of the area into
  the evening.

- Turning colder to end the week. Still have the potential for
  frost and freeze conditions Saturday morning. Some wind is
  expected, temperatures should get as cold as they could.

&&

.MESOSCALE...
Issued at 1253 PM CDT Tue Apr 16 2024

Environment is ramping up across Iowa for  increased severe
storms over the next hours. The main players are the warm front
moving northward that is near of Interstate 80 marked well by
the 60F dewpoint line. There is currently a 15F dewpoint
increase from Dubuque IA to that front. SB/MLCAPES are growing
south of the warm front as it moves north, now up to about 1500
J/Kg. Otherwise, elevated instability exists off to the
southwest in central IA of about 1000 J/KG, all north of the
warm front with little capping. However values are reduced over
northeast Iowa.

As the afternoon progresses, the warm front will try to shift
into northeast Iowa and southwest WI, possibly to Highway 18.
This provides a surface-based storm threat with tornadoes
possible. Otherwise, north of the front storms should remain
elevated, which would limit the threats to hail and wind. Storm
mode is a challenge, with linear structures suggested in the
CAMS over the area. This would mean a more QLCS tornado threat
vs supercells.

These very initial waves of storms through about 230-3pm should
be north of the warm front and somewhat limited by instability
and thus hold less probability of becoming severe. As the warm
front moves north, the CAPE will increase areawide, fueling
enhanced probabilities for severe storms and vigorous updrafts
/4-7 pm/. With pressure falls of 5mb/3hr over northeast IA, it
would favor almost a more easterly surface low direction...which
may limit the northern extent of the warm front /e.g., low
travels along the warm front instead of the low lifting the warm
front synoptic field north/. So, confidence is lower on how far
north the tornado threat reaches beyond the current tornado
watch along and south of Highway 18.

&&

.DISCUSSION...
Issued at 225 PM CDT Tue Apr 16 2024

Short term:

Latest water vapor satellite imagery shows upper level closed low
over eastern Nebraska. Pieces of energy wrapping around upper level
closed low is producing showers/storms mainly along and west of the
Mississippi River per latest mosaic radar. Ongoing showers/storms
will continue to pivot around the upper level closed low into the
forecast area this evening into tonight. Severe threat with the
storms will begin to diminish early this evening...as instability
diminishes across southern parts of the forecast area. Precipitable
water values of 0.75 of an inch to 1.25 will allow for some of the
showers/storms to produce an inch per hour rates through early this
evening. However...with strong low level flow and
aloft...showers/storms will track quickly over the region. Rainfall
amounts through Wednesday morning will be 1.25 to around 1.50
inches across the forecast area.

Upper level closed low lifts northward over the Upper Great Lakes
region tonight into Wednesday. Showers and a few storms will linger
over much of the forecast area. Colder air advects into the forecast
area on backside of the upper level closed low. Temperatures remain
nearly steady or slowly fall into the lower to middle 50s Wednesday
afternoon.

Extended:

Behind the storm system today, a large area of 500mb low pressure
will push across Manitoba and Ontario.  A shortwave trough with move
through the Plains into the Mid-Mississippi Valley.   Scattered
showers will push through with the precipitation ending before the
much colder air arrived.  Precipitation chances increase as you move
south of I90 toward DBQ and amounts increase as well from dry to a
wetting rain. Cold advection through the day Friday continues into
the weekend. The winds will remain elevated for Saturday morning, so
this should help mitigate temperatures pitting out. Frost/freeze
conditions still look possible for Saturday morning with lows in the
20s to lower 30s with some mid 30s. The GEFS/Canadian/EPS ensembles
show a  30 to 90% probability of 32 degrees or colder by 7am
Saturday. Cooler than normal temperatures are expected for Saturday
with seasonable temperatures forecast into early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 100 PM CDT Tue Apr 16 2024

Main taf concerns are periods of showers/storms and the potential
for IFR/MVFR conditions at both RST/LSE taf sites through the taf
period. Low pressure will move into northern Wisconsin through the
taf period and spread showers/storms into the area. With the low
pressure tracking into northern Wisconsin and the showers/storms
moving over the taf sites...ceilings/visibility will lower into
MVFR/IFR through much of the taf period. There could be brief
periods of VFR conditions with any breaks of
showers/storms...however timing of VFR conditions is low at taf
sites. Have kept periods of MVFR/IFR conditions at both taf sites
through taf period. In addition...tight pressure gradient across the
area will produce wind gusts of 30 to 40 knots through this
evening.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Advisory until 10 PM CDT this evening for WIZ017-029-
     032>034-041>044.
MN...Wind Advisory until 7 PM CDT this evening for MNZ079-086-087-
     094-095.
     Wind Advisory until 10 PM CDT this evening for MNZ088-096.
IA...Wind Advisory until 7 PM CDT this evening for IAZ008>010-018-
     019-029.

&&

MESOSCALE...Baumgardt
DISCUSSION...DTJ/Zapotocny
AVIATION...DTJ

Hazardous Weather Outlook
National Weather Service La Crosse WI
334 AM CDT Tue Apr 16 2024

MNZ079-086>088-094>096-WIZ017-029-032>034-041>044-053-171200-
Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark-
Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon-
334 AM CDT Tue Apr 16 2024

This Hazardous Weather Outlook is for portions of southeast
Minnesota...western and north central Wisconsin.

.DAY ONE...Today and Tonight

Widespread showers and scattered storms this afternoon into
tonight. A few strong to potentially severe storms are possible,
mostly along and south of I-90. The main severe threat is hail.

In addition, east winds will gust as high as 45 mph today into
this evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Rainfall, wind, and any severe reports are appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

IAZ008>011-018-019-029-030-WIZ054-055-061-171200-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Crawford-Richland-Grant-
334 AM CDT Tue Apr 16 2024

This Hazardous Weather Outlook is for portions of northeast Iowa
and southwest Wisconsin.

.DAY ONE...Today and Tonight

Numerous storms this afternoon into the evening. Some will be
strong to severe with a large hail threat. A few tornadoes are
also possible.

In addition, east winds will gust as high as 45 mph today into
this evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Rainfall, wind, and any severe reports are appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Rieck

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Special Weather Statement
National Weather Service La Crosse WI
353 PM CDT Tue Apr 16 2024

IAZ010-011-029-030-162115-
Clayton IA-Winneshiek IA-Fayette IA-Allamakee IA-
353 PM CDT Tue Apr 16 2024

...A STRONG THUNDERSTORM WILL IMPACT PARTS OF NORTHEAST IOWA THROUGH
415 PM CDT...

At 350 PM CDT, Doppler radar was tracking a strong thunderstorm near
Elgin, or 11 miles northwest of Elkader, moving north at 65 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

This strong thunderstorm will be near...
  Postville around 355 PM CDT.
  Waukon around 405 PM CDT.

Other locations impacted by this storm include Volney, Spook Cave
Campground, County Roads A 52 And W 60, Waterville, State Road 76 And
County X 16, Elon, Giard, Ludlow, Watson, and County Roads X 16 And W
48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Tornado Watch remains in effect until 800 PM CDT for northeastern
Iowa.

&&

LAT...LON 4284 9175 4333 9165 4330 9141 4325 9108
      4321 9111 4320 9112 4319 9112 4317 9114
      4315 9115 4313 9118 4310 9117 4277 9138
TIME...MOT...LOC 2050Z 195DEG 58KT 4299 9154

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Cecava

Preliminary Local Storm Report
National Weather Service La Crosse WI
354 PM CDT Tue Apr 16 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0328 PM     Tstm Wnd Gst     Spring Valley           43.69N 92.39W
04/16/2024  M51 MPH          Fillmore           MN   Emergency Mngr

            Spring Valley EOC reports 51mph wind gust.

&&

JAW

Special Weather Statement
National Weather Service La Crosse WI
413 PM CDT Tue Apr 16 2024

IAZ011-030-WIZ054-061-162200-
Clayton IA-Allamakee IA-Crawford WI-Grant WI-
413 PM CDT Tue Apr 16 2024

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL CLAYTON...SOUTHEASTERN
ALLAMAKEE...NORTHWESTERN GRANT AND CENTRAL CRAWFORD COUNTIES THROUGH
500 PM CDT...

At 413 PM CDT, Doppler radar was tracking a strong thunderstorm near
Guttenberg, moving north at 65 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

This strong thunderstorm will be near...
  Garnavillo around 420 PM CDT.
  Prairie Du Chien and McGregor around 425 PM CDT.
  Marquette around 430 PM CDT.

Other locations impacted by this storm include Eastman, Giard,
Watson, Turkey River, Bridgeport, Petersburg, Nelson Dewey State
Park, National, Effigy Mounds, and Millville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Tornado Watch remains in effect until 800 PM CDT for northeastern
Iowa...and southwestern Wisconsin.

&&

LAT...LON 4265 9091 4275 9140 4336 9129 4331 9082
TIME...MOT...LOC 2113Z 196DEG 54KT 4277 9123

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

Cecava