Special Weather Statement, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
703 PM CDT Sun Jun 17 2018

.UPDATE...
Issued at 700 PM CDT Sun Jun 17 2018

Seems with steep low-level lapse rates and DCAPE values near 1000
J/Kg, any stronger core has the potential to cause wind damage.
Seems the main threat area is I-90 and north as deeper shear
increases in that direction.

About the rest of the night, RAP/NAM have been consistent since
last evening with a surge of low-level moisture transport
convergence emanating out of south-central MN as the evening
progresses. This is fairly impressive convergence and expect to
see a large ramp up in the storm coverage as that occurs over the
next several hours. It should occur to the west and shift into
the area, with a strong focus into I-90 corridor and north. Flash
flood watch area looks good as it depicts the recent rain area and
wetter soils. BUT, I-90 is expected to be in on the storms as
well and heavy rain potential. Would expect the 9pm-3am rough
window for storms and increasing flood potential.

&&

.SHORT TERM...(Tonight through Tuesday)
Issued at 235 PM CDT Sun Jun 17 2018

Heavy rain, strong (severe?) storm threat tonight. Cooler come
Tuesday.

Storms: while models remain at odds with strength of the various
shortwaves/low level jet/etc, they have remained fairly consistent
with painting showers and storms generally north of I-90 tonight,
slipping those south of I-90 come Monday night.

A warm front currently lies from central MN through the arrowhead
with broad upper level ridging across the great lakes. This ridging
is expected to break down/shift southeast starting tonight as a west
coast trough pushes into the southern rockies. The front will
gradually sink southeast as a result, more as a cold front.
Expectation is for the front to make the I-90 corridor by Mon
morning, dropping into central IA/northern IL Mon evening. Various
bits of shortwave energy spit out of the westward trough over the
next couple days, with the low level jet/sizable moisture transport
funneling along the front (generally leading it across the area).
Showers and storms will fire in response. Expect some break in
coverage, intensity later Monday morning into the afternoon as the
influence of the low level jet wanes - but refire as it
reestablishes itself in the evening.

As for strong to severe chances, plenty of instability with MUCAPES
in excess of 3-4K J/kg this afternoon into the evening. Fair amount
of capping in the warm sector though (southeast of the front) and
deep layer shear remains weak or well displaced into the cooler air
post the front. There is about 30 kts of 0-3 km shear though, which
would aid storm development and provide support for a strong to
damaging wind threat - in addition to hail. Mostly though, think the
main concern locally will be the heavy rain/flash flooding
potential. More on that in the HYDROLOGY section below.

See some strong (severe?) threat for Monday afternoon/evening, but
same shear limitations and less expected instability (more debris
clouds). Threat shifts south into Iowa/southern WI.

Temps: the passage of the cold front on Monday will usher in much
cooler, less humid air starting Tuesday. 925 mb temps slated to drop
from around 26 C this afternoon, to 16-18C Tue afternoon. Highs in
the 70s should result, and with dew points dropping off into the
50s, a lot more comfortable humidities can also be expected.

.LONG TERM...(Wednesday through Sunday)
Issued at 235 PM CDT Sun Jun 17 2018

The 17.12z GFS/NAM/ECMWF are decent agreement in slowly moving
surface front north to south across forecast area Monday night into
Tuesday. Moisture convergence and vertical motion along the front
will continue to linger showers and thunderstorms mainly Monday
night across northeast Iowa and southwest Wisconsin. As surface
front tracks south into central Iowa and surface ridge builds into
northern Wisconsin...showers and thunderstorms will diminish across
northeast Iowa and southwest Wisconsin during the day Tuesday.

Main forecast concerns from Tuesday night into Sunday are
precipitation chances Thursday through Sunday. The 17.12z
GFS/ECMWF/GEM are in good agreement in building shortwave ridge into
the Upper Great Lakes Region Wednesday and lifting weak upper level
closed low/trough into the Northern Plains/Great Lakes Region
Thursday into Sunday. The main difference between the deterministic
models is timing/strength of weak upper level closed low/trough
moving into the Northern Plains/Great Lakes Region. This will have
impacts on timing of shower/thunderstorm chances Thursday into
Sunday across the forecast area. Shortwave ridge entrenched over the
Great Lakes Region Wednesday will allow for mainly dry weather
across much of the forecast area. Next concern are precipitation
chances Thursday into Sunday...as weak upper level closed low/trough
slowly tracks into the Great Lakes Region/Northern Plains. Due to
differences in timing/strength of upper level closed low/trough
confidence on precipitation chances in southern/western forecast
area Thursday is low...as upper level closed low/trough moves
closer/over forecast area shower/thunderstorm chances increase
especially Thursday afternoon into Friday and small chance of
showers/thunderstorms continue into next weekend. The 17.12z
GFS/ECMWF show 925mb mainly in the plus 15 to plus 20 degrees
celsius range through the period and allow for highs to climb into
the 70s to lower 80s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 700 PM CDT Sun Jun 17 2018

Storms to be increasing across the area this evening with a fairly
active period expected from 06-09Z at KLSE/KRST. Have included a
TEMPO for storms and a 1SM vsby due to heavy rainfall rates. The
storms should then shift east and the cold front sags in with a
wind shift and lower ceilings. Confidence is not high on MVFR cigs
Monday morning, it could be higher.
&&

.HYDROLOGY...
Issued at 235 PM CDT Sun Jun 17 2018

Very conducive atmosphere for efficient, heavy rain producers
tonight into Monday with warm cloud depths around 4.5 km and PWs in
excess of 2 inches. Any storm will produce heavy rain. Rainfall of 2
or more inches could fall in a short amount of time. High potential
for urban flooding, and If storms repeat/train across the same areas
- flash flooding could/would result. Greater threat for heavy rain
later tonight north of I-90, and have issued a Flash Flood Watch to
account for they heavy rain/flooding potential.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory until 7 PM CDT this evening for WIZ032>034-041>044-
     053>055-061.

     Flash Flood Watch through Monday morning for WIZ017-029-032>034.

MN...Heat Advisory until 7 PM CDT this evening for MNZ079-086>088-
     094>096.

     Flash Flood Watch through Monday morning for MNZ079.

IA...Heat Advisory until 7 PM CDT this evening for IAZ008>011-018-019-
     029-030.

&&

UPDATE...Baumgardt
SHORT TERM...Rieck
LONG TERM....DTJ
AVIATION...Baumgardt
HYDROLOGY...Rieck

Hazardous Weather Outlook
National Weather Service La Crosse WI
914 PM CDT Sun Jun 17 2018

IAZ008>011-018-019-029-030-MNZ086>088-094>096-WIZ041>044-053>055-
061-181200-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-La Crosse-
Monroe-Juneau-Adams-Vernon-Crawford-Richland-Grant-
914 PM CDT Sun Jun 17 2018

This Hazardous Weather Outlook is for portions of northeast
Iowa...southeast Minnesota...and southwest into central Wisconsin

.DAY ONE...Rest of Tonight

Thunderstorms tonight will be capable of heavy rain which could
result in localized flooding. In addition, a few could be strong,
potentially severe this evening, capable of damaging winds. This
risk is mainly near and north of I-90.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Periodic thunderstorm chances through the new week. A few storms
may be strong to severe south of Interstate 90 on Monday with
heavy rain, hail, and strong winds. It is too early to discern
any potential severe weather risk beyond Monday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed overnight. Reports of damage
and rainfall amounts are appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

MNZ079-WIZ017-029-032>034-181200-
Wabasha-Taylor-Clark-Buffalo-Trempealeau-Jackson-
914 PM CDT Sun Jun 17 2018

This Hazardous Weather Outlook is for portions of southeast
Minnesota into north-central Wisconsin.

.DAY ONE...Rest of tonight

Flash Flood Watch tonight.

Thunderstorms tonight will be capable of heavy rain. With much of
the grounds having received rainfall recently, additional heavy
rain could result in flash flooding. In addition, a few of the
storms could be strong to severe this evening, capable of strong
to damaging winds and hail.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Periodic thunderstorm chances through the new week. Severe
weather is not expected Monday. It is too early to discern any
potential severe weather risk beyond then.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed overnight. Reports of damage
and rainfall amounts are appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Baumgardt

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
733 PM CDT SUN JUN 17 2018

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

0730 PM     TSTM WND GST     6 N CHILI               44.71N 90.34W
06/17/2018  E60 MPH          CLARK              WI   TRAINED SPOTTER

            SMALL BRANCHES DOWN.

&&

CA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
747 PM CDT SUN JUN 17 2018

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

0736 PM     TSTM WND GST     3 SW SPENCER            44.71N 90.34W
06/17/2018  E70 MPH          CLARK              WI   TRAINED SPOTTER

&&

CA

Special Weather Statement
National Weather Service La Crosse WI
811 PM CDT Sun Jun 17 2018

IAZ008>011-018-019-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053-180315-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Wabasha-
Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark-Buffalo-
Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon-
Including the cities of Osage, Cresco, Decorah, Waukon,
Charles City, New Hampton, Wabasha, Dodge Center, Rochester,
Winona, Austin, Preston, Caledonia, Medford, Neillsville, Alma,
Arcadia, Whitehall, Black River Falls, La Crosse, Sparta, Tomah,
Mauston, Friendship, and Viroqua
811 PM CDT Sun Jun 17 2018

...Storms Through The Evening...Heavy Rain...Strong Gusts...

Storms continue to develop across the area, and will gradually
form into a west to east line roughly along the Interstate 90
corridor late tonight. Through 10 pm wind gusts up to 40 mph are
possible with the stronger storms.

Heavy rain is likely with the storms tonight, and due to the
training nature of the storms, flash flooding could result where
the storms repeat. The higher threat for this where recent rains
have already soaked the ground - generally north of Interstate 90.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
823 PM CDT SUN JUN 17 2018

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

0716 PM     TSTM WND DMG     NEILLSVILLE 4NNE        44.61N 90.56W
06/17/2018                   CLARK              WI   CO-OP OBSERVER

            DELAYED REPORT. SEVERAL TREES DOWN,
            INCLUDING ONE ON POWER LINES. TIME ESTIMATED
            FROM RADAR.

&&

CA

Special Weather Statement
National Weather Service La Crosse WI
1032 PM CDT Sun Jun 17 2018

IAZ008>011-018-019-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053-180600-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Wabasha-
Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark-Buffalo-
Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon-
Including the cities of Osage, Cresco, Decorah, Waukon,
Charles City, New Hampton, Wabasha, Dodge Center, Rochester,
Winona, Austin, Preston, Caledonia, Medford, Neillsville, Alma,
Arcadia, Whitehall, Black River Falls, La Crosse, Sparta, Tomah,
Mauston, Friendship, and Viroqua
1032 PM CDT Sun Jun 17 2018

...Storms Into The Overnight...Heavy Rain Possible...

Thunderstorms will continue to track across the area into the
overnight hours. The storms will produce occasional lightning and
periods of heavy rainfall. If storms repeat over areas, flooding
could become a concern. Monitor forecasts closely tonight and be
ready to move to higher ground should heavy rains develop over
your area. Those outdoors, such as those camping, should keep an
extra close eye on the weather tonight.

Wetenkamp

Special Weather Statement
National Weather Service La Crosse WI
1139 PM CDT SUN JUN 17 2018

WIZ034-042-043-180515-
Juneau-Jackson-Monroe-
1139 PM CDT SUN JUN 17 2018

...THUNDERSTORMS WITH FREQUENT LIGHTNING AND BRIEF HEAVY RAIN
IMPACTING SOUTHERN JACKSON... NORTHWESTERN JUNEAU AND NORTHERN
MONROE COUNTIES...

At 1134 PM CDT, radar indicated strong thunderstorms were located
along a line extending from 11 miles east of Millston to near
Cataract. These storms are producing frequent lightning and a quick
1/2 to 1 inch of rainfall. Movement was east at 40 to 50 mph.

Torrential rainfall is occurring with these storms, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

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.

LAT...LON 4422 8993 4420 8991 4419 8993 4419 8990
      4418 8993 4416 8992 4417 8997 4413 8999
      4413 8997 4412 9001 4409 9003 4402 9000
      4407 9115 4422 9115 4425 9019 4425 8991
      4423 8989
TIME...MOT...LOC 0434Z 239DEG 42KT 4423 9041 4412 9088

Wetenkamp