Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
610 PM CDT Tue Jun 13 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 302 PM CDT Tue Jun 13 2017

Potentially very active short term is in store, with severe
weather possible this evening/tonight, followed by what could be
our fourth day in a row of severe weather Wednesday.

We'll start with this afternoon. First, when looking at forecast
shear/instability parameters along with forecast soundings for
today, the first reaction we have been hearing around the office
is wow. The type of environment forecast to be over MN today is
something that we only see maybe a couple of times a decade up
here. 3000-5000 j/kg of MLCAPE, 40-50 kts of deep shear, h85 jet
increasing to between 40 and 50 kts, and effective storm relative
helicity north of the warm front forecast to get up between 300
and 600 m2/s2. That warm front shows up well on the 0.5 degree
reflectivity from MPX just into the far southern Twin Cities metro
area and by most accounts, it is forecast to get up to or a
little north of I-94.

So that leads to the next question of what's a miss to keep us
from having a major severe weather outbreak? There are three
problems. First, there is strong subsidence in the wake of the
this mornings MCS as evidence by the rapidly clearing skies and
wake low across northern MN and rising h5 heights across the
entire area. Second, we have a very warm EML overhead, with a
pronounced warm nose and capping inversion noted on forecast
soundings at h7, with temps at this level around 14C. This warm
air around h7 also shows up well on 7.34 micron GOES-16 low level
water vapor imagery, with very warm values coming up out of the
central plains. The other problem deals with the orientation of
our shear and horizontal vorticity vectors, which is pretty much
parallel to predicted storm motion. The shear vectors parallel to
storm motion diminishes the tornado threat, as this favors rapid
upscale growth to linear systems, while discrete cells end up
ingesting primarily cross-wise as opposed to stream-wise
vorticity.

SPC did nudge their 10% tornado probability east toward St. Cloud,
which was likely in response to the HRRR this morning, which had
been developing discrete cells this afternoon ahead of the warm
front in west central MN. However, since 17z, the HRRR has
abandoned that idea and instead has joined the rest of the CAMS in
saying the capping wins out today, with the MPX area awaiting the
arrival of a line of thunderstorms out of Dakotas, that will form
in response to falling heights and a weakening cap associated
with a short wave currently working out of southeast Wyoming.

For tonight, current expectations is that the greatest severe
threat will reside across the northern half of the MPX coverage
area, with storm coverage across the southern half of the area
more questionable. Moisture transport on the RAP at h85 shows the
low level jet splitting as it work across MN, with one enhanced
area going up across northeast MN and another area coming up out
of KS into central IA. The 18z HRRR follows this forcing pretty
close taking one MCS northeast across western MN toward Lake
Superior, with it's south end swinging through the Twin Cities,
while a second MCS moves into southern IA associated with the
southern LLJ enhancement.

Of course, we aren't done with this tonight as the cold front will
be slow to move east. There is still uncertainty with
if/when/where storms develop Wednesday, but we have seen a slowing
in the cold front in the models, most pronounced with the GFS.
This slowing explains the western shift in the day 2 convective
outlook. CAMs and deterministic models are all over the board with
how convection evolves tomorrow. The problem is upper forcing is
more in question with the front Wednesday. The main upper low will
be up west of the Winnipeg lakes, with a subtle short wave being
the main forcing for storms. The GFS is slowest with the wave,
bringing it through our area during the afternoon, which allows
storms to develop along the I-35 corridor. The ECMWF has this same
wave pushing into northeast WI by the afternoon, with storms
largely east of our area. The severe threat is definitely
conditional, but severe parameters would support all modes of
severe weather if we see convection, though once again, we would
like see a quick transition to a more linear convective mode.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 327 PM CDT Tue Jun 13 2017

Still some uncertainty on where the cold front will be located
Wednesday evening but current consensus suggests it being
oriented roughly along the MN/WI border, keeping thunderstorm
chances constrained to west-central WI & far-southeast MN. MLCAPE
values of 1500-2500 J/kg and deep shear values of 30-40 kts would
certainly be supportive of some strong to severe thunderstorm
segments & clusters across western WI, with damaging wind gusts
and large hail the main threats. The cold front clears the area by
Thursday morning with clearing & drying behind the front leading
to a warm but pleasant day.

Unsettled weather returns Friday & through the weekend as a 100 kt
upper level jet & deepening trough over the western Great
Lakes provides forcing for at least some scattered precip chances
each day. Instability looks to be low each day as the warm front &
greatest CAPE looks to set up further to the south over Iowa so
strong/severe thunderstorms are not expected. The heaviest rainfall
is expected Friday night into early Sunday morning where PW values
potentially over 1.5" could result in locally heavy rainfall,
primarily over southern MN. Decent rain chances will continue
through the day Saturday into Sunday morning as the strong forcing
aloft will continue to kick off scattered showers & thunderstorms,
but we will be looking at on & off showers & thunderstorms vs an all
day washout.

The upper level trough moves east of the area by Sunday afternoon
ushering in NW flow with drier weather & much cooler temperatures,
though still close to normal. Models begin to diverge towards
Tuesday with the Euro placing us in a drier pattern stuck between
the broad trough off the east coast, & a developing ridge over the
west. The GFS returns to zonal flow across the northern tier of the
US & brings another strong upper level jet into the area, which
would result in a more unsettled pattern for midweek.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 605 PM CDT Tue Jun 13 2017

Several storms developed in west central Mn over the past hour and
were moving into an environment that is conducive of rapid
development. Will include near severe wind gusts at KAXN due to
this scenario between 1-2z. KRWF will likely see the activity in
eastern South Dakota to move into the area between 3-4z, with KSTC
between 4-5z. Otherwise, most of the MPX TAF sites will see
thunderstorms overnight, it is just a timing issue based on
movement and speed. There could be additional thunderstorms in
south central/east central Minnesota by 12z Wednesday as a
secondary area of storms move northeast from Iowa. Otherwise,
after 12z, most of Minnesota will see VFR conditions with a brief
period of MVFR/IFR cigs due to ample boundary layer moisture in
the wake of the thunderstorms overnight. These lower clouds/cig
should lift and dissipate as winds shift to the southwest.

KMSP...

Showers, isolated storms in southwest Minnesota should weaken as
it moves northeast into east central Minnesota this early evening.
Thunderstorms in South Dakota will likely affect the airport
after 5z, with a period of 1-2 hrs of heavy rain, gusty winds and
a brief period of MVFR/IFR conditions. Otherwise, a few storms are
possible around 12z Wednesday. The front will move across the
state Wednesday morning, with some redevelopment possible after
18z at the airport.

/OUTLOOK FOR KMSP/

Thu...VFR. Wind W 5-10kt.
Fri...VFR. Chc MVFR/TSRA. Wind VRB05kt.
Sat...VFR. Chc MVFR/TSRA. Wind bcmg W at 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

SHORT TERM...MPG
LONG TERM...ETA
AVIATION...JLT

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
705 PM CDT Tue Jun 13 2017

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
150015-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-
Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington-
Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota-
Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth-
Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk-
St. Croix-Pierce-Dunn-Pepin-Eau Claire-
705 PM CDT Tue Jun 13 2017

This Hazardous Weather Outlook is for portions of central and
southern Minnesota...and west central Wisconsin.

.DAY ONE...Tonight

There is an Enhanced Risk of severe thunderstorms through tonight
generally west of Interstate 35 and a Slight Risk to the east
into west central Wisconsin. A line of thunderstorms is expected
to move eastward across western and into eastern Minnesota
between 7pm and midnight. Large hail and damaging winds will be
possible with this line thunderstorms as it moves east across the
area tonight. A tornado or two cannot be ruled out either.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

There is a Slight Risk of severe thunderstorms again Wednesday,
mainly along and east of Interstate 35 corridor. Large hail and
damaging winds will be possible as scattered thunderstorms develop
during the afternoon.

Thunderstorm chances return Friday night and Saturday.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation will not be needed.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
753 PM CDT TUE JUN 13 2017

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

0722 PM     HAIL             DONNELLY                45.69N 96.01W
06/13/2017  M1.25 INCH       STEVENS            MN   PUBLIC

            PHOTO SUBMITTED VIA FACEBOOK.

&&

AMK

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
812 PM CDT TUE JUN 13 2017

MNZ047-054>056-064-140200-
Chippewa-Yellow Medicine-Stevens-Lac Qui Parle-Swift-
812 PM CDT TUE JUN 13 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT LAC QUI PARLE...
NORTHWESTERN CHIPPEWA...WESTERN STEVENS...SOUTHWESTERN YELLOW
MEDICINE AND WESTERN SWIFT COUNTIES...

At 812 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Corona to 6 miles northeast of Lake
Alice to near White. Movement was northeast at 55 mph.

Winds in excess of 40 mph are possible with these storms.

These storms will be near...
  Marietta around 820 PM CDT.
  Madison and Bellingham around 835 PM CDT.
  Canby around 840 PM CDT.
  Porter around 845 PM CDT.
  Appleton, Chokio and Milan around 850 PM CDT.

Other locations impacted by these storms include Nassau, Providence,
Big Stone National Wildlife Refuge, Appleton Airport, Madison
Airport, Louisburg, Burr, St. Leo, Cerro Gordo and Florida Creek
Wildlife Management Area.

A tornado watch remains in effect until 200 AM CDT for west central
Minnesota.

LAT...LON 4517 9646 4526 9645 4527 9642 4525 9629
      4522 9627 4518 9610 4541 9612 4542 9625
      4576 9625 4576 9621 4515 9589 4463 9600
      4463 9645
TIME...MOT...LOC 0112Z 238DEG 46KT 4537 9674 4493 9653 4447 9663

BORGHOFF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
918 PM CDT TUE JUN 13 2017

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

0847 PM     TSTM WND DMG     1 W ALBERTA             45.57N 96.06W
06/13/2017                   STEVENS            MN   TRAINED SPOTTER

            TREES AND POWER-LINES DOWN.

&&

AMK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
928 PM CDT TUE JUN 13 2017

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

0922 PM     TSTM WND DMG     3 ESE BRANDON           45.95N 95.55W
06/13/2017                   DOUGLAS            MN   PUBLIC

            BRANCHES & TREE LIMBS DOWN.

&&

AMK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
934 PM CDT TUE JUN 13 2017

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

0704 PM     TORNADO          2 WSW CYRUS             45.61N 95.78W
06/13/2017                   STEVENS            MN   TRAINED SPOTTER

            VIDEO SHOWS STRONG TORNADO, AND TRUSTED
            STORM TRACKER REPORTED DAMAGE TO A
            SUB-STATION SOUTH OF HWY 28. TIME BASED ON
            SPOTTER REPORTS AND RADAR.

&&

JRB

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
958 PM CDT TUE JUN 13 2017

MNZ042-140345-
Todd-
958 PM CDT TUE JUN 13 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT TODD COUNTY...

At 958 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Wrightstown to near West Union.
Movement was north at 55 mph.

Winds in excess of 40 mph are possible with these storms.

These storms will be near...
  Bertha around 1005 PM CDT.
  Hewitt around 1010 PM CDT.
  Browerville and Clarissa around 1020 PM CDT.
  Staples around 1040 PM CDT.
  Staples Airport around 1045 PM CDT.

Other locations impacted by these storms include Philbrook, Long
Prairie Airport, Round Prairie, Little Sauk, West Union and Clotho.

A tornado watch remains in effect until 200 AM CDT for central and
west central Minnesota.

LAT...LON 4637 9474 4635 9470 4636 9467 4628 9465
      4593 9465 4577 9489 4578 9512 4594 9515
      4637 9516
TIME...MOT...LOC 0258Z 199DEG 46KT 4622 9519 4583 9502

BORGHOFF