Special Weather Statement, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
1251 PM CDT FRI JUN 3 2016

.UPDATE...
Issued at 944 AM CDT Fri Jun 3 2016

Forecast updated to increase wind gusts this afternoon,
especially across the open areas of southeast Minnesota and
northeast Iowa. Considerable uncertainty remains on severe
thunderstorm potential this afternoon. Deeper mixing is now
suggested in the latest RAP and NAM forecast soundings, which will
limit the amount of CAPE available. Moisture and weakening shear
this afternoon will be a problem for the storms. Latest thinking
is that we could see some stronger wind gusts out of the high
based showers and storms, in the range of 40 to 50 mph. Will
continue to monitor moisture and wind shear trends closely today.

&&

.SHORT TERM...(Today and tonight)
Issued at 347 AM CDT Fri Jun 3 2016

Timing, coverage, and strength of thunderstorms today and tonight
still in question as a vigorous Pacific trough drops south across
the Upper MS River Valley. 03.08Z analysis shows the primary
vorticity lobe aloft along the Canadian/MT border with the
surface low along the western SD/NE border and the warm front from
south of Sioux Falls, SD to Des Moines, IA.

A few high based showers/isolated thunderstorms are possible
this morning along northward advancing 850 hPa warm air advection
wing. The surface warm front will also lift northward through the
day, aligned along the MS River Valley by noon and then north of
the forecast area early this evening. Primary limiting factor
today/tonight for stronger (severe) storms will be instability.
Surface dew points only expected to rise into the mid to upper 50s
behind the front, resulting in MLCAPE values generally from 500
to 1000 J/kg. Good veering wind profile in the lowest 3 km in the
vicinity of the front, but deep layer shear (0 to 6 km) needed for
supercells is also rather weak (less than 30 kts) and disorganized.

Cannot completely rule out an isolated supercell/tornado near the
warm front, but think primary convective mode will be multi-
cellular with roughly 30 to 40 kts of 0-3 km bulk shear in the
warm sector. Primary threat will be damaging downburst wind given
DCAPE values up to 1500 J/kg and inverted-V soundings with steep
low-level lapse rates. Overall, skinny CAPE profiles should limit
hail size to below severe limits. A broken line of showers and
storms is expected to develop this afternoon and advance eastward
across the forecast area through this evening (3-10 pm). Highest
severe threat is mainly south and west of the forecast area,
coincident with best CAPE pool and highlighted by SPC Day 1
slight risk. However, higher severe potential locally appears to
be focused across northern WI. It is here where 0-3 km shear
vectors are perpendicular to the advancing convective line and in
the vicinity of the highest mid-level moisture transport. This
idea is supported by several of the convection-allowing models,
including the latest HRRR-CR and NAMNest.

.LONG TERM...(Saturday through Thursday)
Issued at 347 AM CDT Fri Jun 3 2016

Slow moving cold front on Saturday will allow for additional
showers and thunderstorms, some of which may become strong in the
late morning and early afternoon east of the MS River. Otherwise,
expect a gradual drying trend Saturday with cooler temperatures in
the lower to mid 70s with a breezy west-northwest wind.

Additional rain chances Sunday into Monday mainly along and
northeast of the MS River as short-waves rotate around deepening
trough across the northern Great Lakes. Cool temperatures with
breezy northwest wind.

Tuesday/Wednesday look dry as surface ridge axis takes up
residence across the region. Chance POPs to end the week seem
reasonable as additional ill-resolved short-waves drop south in
northwest flow aloft. At the same time, 500 hpa ridge over the
Rockies nudges eastward, allowing temperatures to rise slightly
into the upper 70s to lower 80s by Thursday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1251 PM CDT Fri Jun 3 2016

Scattered showers and isolated thunderstorms will continue across
the area through the afternoon hours and become more numerous this
evening. A few stronger storms are possible this evening with the
potential for gusty winds and perhaps small hail. Periods of MVFR
to IFR conditions are possible near any stronger storms. A cold
front pushes through the area late tonight into Saturday with
winds switching to the west. A few showers may linger into
Saturday, especially east of the Mississippi River.

&&

.ARX Watches/Warnings/Advisories...
WI...None.
MN...None.
IA...None.
&&

UPDATE...WETENKAMP
SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...WETENKAMP

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LA CROSSE WI
704 AM CDT FRI JUN 3 2016

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-041100-
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-
704 AM CDT FRI JUN 3 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS NORTHEAST IOWA...
SOUTHEAST MINNESOTA...AND SOUTHWEST INTO CENTRAL WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE LIKELY THIS AFTERNOON AND EVENING ACROSS
SOUTHEAST MINNESOTA...NORTHEAST IOWA AND SOUTHWEST WISCONSIN. SOME
THUNDERSTORMS MAY BECOME STRONG TO SEVERE. DAMAGING WINDS AND HAIL
ARE THE PRIMARY THREATS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE LIKELY AGAIN SATURDAY MAINLY EAST OF THE
MISSISSIPPI RIVER. A FEW OF THESE STORMS MAY BECOME STRONG BY
AFTERNOON WITH SMALL HAIL BEING THE MAIN THREAT. THUNDERSTORMS
REMAIN POSSIBLE SUNDAY...AND ARE AGAIN IN THE FORECAST FROM
WEDNESDAY NIGHT INTO THURSDAY. THE RISK FOR SEVERE WEATHER LOOKS
TO BE LOW WITH ANY OF THESE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER GROUPS SHOULD BE ALERT FOR POSSIBLE ACTIVATION THIS
AFTERNOON AND EVENING.

.EMERGENCY MANAGEMENT COORDINATION...

NO WEBINAR IS SCHEDULED.

DAS/ROGERS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
303 PM CDT FRI JUN 3 2016

MNZ079-087-088-095-WIZ032-032030-
WINONA-WABASHA-FILLMORE-OLMSTED-BUFFALO-
303 PM CDT FRI JUN 3 2016

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WESTERN WINONA...
NORTHERN FILLMORE...WABASHA...EASTERN OLMSTED AND WESTERN BUFFALO
COUNTIES...

AT 302 PM CDT...RADAR INDICATED STRONG THUNDERSTORMS WERE LOCATED
ALONG A LINE EXTENDING FROM NEAR PEPIN TO NEAR SPRING VALLEY.
MOVEMENT WAS EAST AT 30 MPH.

WINDS IN EXCESS OF 40 MPH ARE POSSIBLE WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
WABASHA...ALMA...BUFFALO...ST. CHARLES...PLAINVIEW...CHATFIELD...EYOTA...
LEWISTON...ELGIN...BUFFALO CITY...DOVER...STOCKTON...ROLLINGSTONE..

SEEK A SAFE SHELTER INSIDE A STURDY BUILDING UNTIL THE STORMS PASS.

LAT...LON 4441 9227 4443 9216 4441 9208 4444 9207
      4449 9178 4374 9180 4376 9240
TIME...MOT...LOC 2002Z 249DEG 28KT 4440 9212 4376 9235

WETENKAMP