Flash Flooding and Flooding in Minnesota, June 27 to 30, 2019

Area Forecast Discussion
National Weather Service La Crosse WI
659 PM CDT Thu Jun 27 2019

.SHORT TERM...(This evening through Friday)
Issued at 228 PM CDT Thu Jun 27 2019

Progressive line of storms continues to move across northeast IA
into western WI this afternoon ahead of a shortwave trough across
northern MN and along the gradient of an axis of strong instability.
Sporadic damaging wind and hail reports have been observed with the
line along with brief heavy rainfall. A lack of stronger deep layer
shear has likely somewhat limited further organization and more
significant impacts. The most intense portion of the line will exit
to the east by mid to late afternoon.

Behind the line a continued feed of low-level moisture transport
into the shortwave trough to the north will likely lead to renewed
convective activity. Based on the moisture transport signal with
support from the CAMs, this is expected across parts of southern MN
into western WI, but exact placement will depend on surface boundary
position. While surface-based instability will wane behind the
leading line, an axis of elevated instability feeding into the
boundary may support some stronger storms. Of greater concern is
potential for heavy rain given pwats of 1.5-2.0 inches and deep warm
cloud depths. Reports of around an inch of rain in 30 minutes this
afternoon suggest environment is quite favorable for intense rain
rates. Confidence is still low on exactly which areas will be
favored for the heaviest rains (and the duration), but it is
possible a short-fused flash flood watch may be needed for portions
of the area tonight.

On Friday, the shortwave to the north will continue to move east
with a very warm, humid airmass remaining in place. Large-scale lift
will be weak as mid-level ridging slowly builds in from the west,
but with potential for residual surface boundaries to be situated
over the area and SBCAPE of 2000 to 3000+ J/kg, isolated to
scattered storms are possible. While a few strong storms could not
be ruled out, the lack of deep layer shear will likely keep storms
pretty disorganized in nature. Highs will be in the mid 80s to low
90s.

.LONG TERM...(Friday night through Thursday)
Issued at 228 PM CDT Thu Jun 27 2019

Two main concerns through the upcoming weekend. The first will be
the arrival of some early summer heat. The main ridge axis looks
to remain over the eastern part of the country allowing southwest
flow to be in place from the Desert Southwest into the Upper
Midwest. Temperatures at 850 mb look to climb into the 22 to 24C
range for both Saturday and Sunday. With some partial sunshine
Saturday, surface temperatures are expected to top out in the
upper 80s to lower 90s. Temperatures Sunday look to be a couple of
degrees warmer before some clouds start to roll in ahead of an
approaching front. Dew points Saturday should be allowed 70 to
push heat indices into the middle to upper 90s. By Sunday, the dew
points could reach the lower to middle 70s ahead of the front
which would push heat indices into the 95 to 100 range. Depending
on the areal coverage of these higher heat indices, a heat
advisory may be needed Sunday.

The other concern then will be with the rain chances with the
incoming front Sunday. The upper level ridge axis will get
flattened as a short wave trough comes out the Rockies and tops
the ridge axis as it moves across the Upper Midwest. While the
wave should pass by to the north of the area, it will still be
close enough to lower the heights enough to allow for the
possibility of some convection along the incoming front. The main
moisture transport axis looks to be in place ahead of the short
wave trough and should intersect the front as it comes into the
region. Forecast soundings for Sunday afternoon show a pretty
strong low level cap should be in place with the influx of warm
air. The 27.12Z GFS suggests this cap will hold tight through the
day so that any convection that would form along the front would
be elevated. The potential for severe weather Sunday thus looks to
be rather conditional with the main forcing passing to the north
and will there be enough to break the cap. For now, will keep the
rain chances in the 30 to 50 percent range.

The front looks to then hang up over the region for a continued
threat of some convection into the middle of next week. The upper
level ridge should continue to retreat into the southeast part of
the country setting up the potential for additional short wave
troughs to move across the region. Some differences between the
GFS and 27.12Z ECMWF on this scenario though, which leads to some
lower confidence on how much rain may occur next week. The GFS
wants to bring some troughing over the region as an upper level
low moves across central Canada while the ECMWF keeps this
troughing farther north with the northern extent of the ridge
still over the region. Because of these differences, the rain
chances will be kept in the 20 to 30 percent range for the most
part. It should also be cooler next week with the front expected
to hang up south of the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 659 PM CDT Thu Jun 27 2019

Main aviation concerns are on the potential for more shower and
thunderstorms at the TAF sites tonight. While showers an a few
storms will continue this evening, there could be an
intensification of the storms by 03 to 04Z. If the storms
intensify late this evening into the overnight they will have the
potential to produce heavy rain, frequent lightning, and possibly
gusty winds. IFR conditions are possible near any storms
overnight. Then stratus could develop over the TAF sites in the 9
to 11 Z timeframe with MVFR conditions possible. We should see a
return to VFR conditions by mid to late morning at both TAF sites
as weak high pressure edges in from the northwest.

&&

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

SHORT TERM...JM
LONG TERM...04
AVIATION...Wetenkamp

Hazardous Weather Outlook
National Weather Service La Crosse WI
339 PM CDT Thu Jun 27 2019

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-281100-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-
Taylor-Clark-Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-
Adams-Vernon-Crawford-Richland-Grant-
339 PM CDT Thu Jun 27 2019

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

.DAY ONE...Tonight

More thunderstorms are expected tonight. These storms will have
the potential to produce heavy rain that could lead to some flash
flooding. Some of the stronger storms could also produce strong
winds.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

The thunderstorm chances will continue into Friday with lightning
the main threat.

There will be on and off chances for thunderstorms from Sunday
afternoon through Wednesday. At this time, it is too early to
determine if there is a threat for severe weather.

.SPOTTER INFORMATION STATEMENT...

Any reports of flooding tonight would be appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

04

Special Weather Statement
National Weather Service La Crosse WI
443 PM CDT Thu Jun 27 2019

IAZ029-272245-
Fayette-
443 PM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT FAYETTE COUNTY...

At 440 PM CDT, a strong thunderstorm was located near Tripoli, or 13
miles northwest of Oelwein, moving east at 25 mph.

Wind gusts up to 35 mph, pea size hail, and heavy downpours are
possible with this storm.

Locations impacted include...
Oelwein, Fayette, Maynard, Arlington, Wadena, Westgate, Albany, and
Brainard.

If outdoors, seek shelter inside a building.

LAT...LON 4264 9208 4290 9208 4294 9161 4264 9161
TIME...MOT...LOC 2140Z 263DEG 23KT 4275 9216

Lee

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
447 PM CDT THU JUN 27 2019

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

0200 PM     TSTM WND DMG     SPARTA                  43.94N 90.81W
06/27/2019                   MONROE             WI   PUBLIC

            RECEIVED A PICTURE OF A LARGE BRANCH SNAPPED
            FROM A TREE. TIME ESTIMATED FROM RADAR.

&&

Special Weather Statement
National Weather Service La Crosse WI
513 PM CDT Thu Jun 27 2019

IAZ030-272245-
Clayton-
513 PM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN CLAYTON COUNTY...

At 512 PM CDT, a strong thunderstorm was located near Arlington, or
14 miles southwest of Elkader, moving east at 35 mph.

Winds in excess of 40 mph and penny size hail are possible with this
storm.

Locations impacted include...
Guttenberg, Elkader, Strawberry Point, Garnavillo, Volga, North Buena
Vista, Garber, Osterdock, Elkport, Millville, and Mederville.

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.

LAT...LON 4285 9161 4288 9110 4275 9107 4269 9097
      4268 9090 4265 9090 4264 9160
TIME...MOT...LOC 2212Z 268DEG 33KT 4272 9162

CA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
749 PM CDT THU JUN 27 2019

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

0135 PM     TSTM WND DMG     WEST SALEM              43.90N 91.08W
06/27/2019                   LA CROSSE          WI   NWS EMPLOYEE

            NWS EMPLOYEE REPORTS MULTIPLE BRANCHES DOWN,
            INCLUDING A LARGE BRANCH.

&&

Special Weather Statement
National Weather Service La Crosse WI
928 PM CDT Thu Jun 27 2019

MNZ079-086>088-WIZ029-032>034-041-042-280600-
Wabasha-Dodge-Olmsted-Winona-Clark-Buffalo-Trempealeau-Jackson-
La Crosse-Monroe-
Including the cities of Wabasha, Dodge Center, Rochester, Winona,
Neillsville, Alma, Arcadia, Whitehall, Black River Falls,
La Crosse, Sparta, and Tomah
928 PM CDT Thu Jun 27 2019

...Thunderstorms With Heavy Rain And Possible Flooding Threat
Tonight...

Thunderstorms will continue to increase in coverage tonight,
especially north of Interstate 90. The storms will be capable of
producing periods of heavy rainfall and if the storms repeat over
areas, flooding may develop. In addition, the strongest storms
could produce some hail, frequent lightning, and gusty winds. Look
for the storms to taper off after 3 AM. Have a way to receive
weather alerts tonight and if you are near a flood prone area,
keep an extra close watch on the weather and be ready to move to
higher ground if heavy rains occur.

Wetenkamp