Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1220 AM CDT Fri Jul 28 2023

.DISCUSSION...(This evening through Thursday)
Issued at 321 PM CDT Thu Jul 27 2023

Key Messages:

- Today and overnight, high impact severe weather possible across
  mainly eastern Minnesota and west central Wisconsin. Damaging wind
  greater than 75 mph, and hail larger than tennis balls are possible
  with the storms.

- Friday, additional severe storms are possible, but this depends on
  how the overnight storms play out.

- Looking ahead, temperatures will be more seasonable next week,
  with occasional chances for thunderstorms.

Discussion...

Today and tonight…There is potential for high impact severe weather
later this afternoon into early tonight. Storms that develop will
have the potential for very large hail and damaging wind. The main
driver behind this set up is extreme amounts of instability due to
the hot and humid surface conditions, together with dry mid levels of
the atmosphere. The end result is MLCAPE values of over 4000 J/kg.
In addition, deep layer shear was on the order of 40 kts, which means
organized convection with strong updrafts. However, the 0-1km shear
was less than 10 kts, and the effective helicity was around 100 kts
or less. For this reason, the main threat with these storms is very
large hail, especially once they develop. After that, HiRes models
support the idea of a cold pool developing and these storms
congealing into a line, with strong winds becoming the primary
threats. Additional development is possible into the overnight hours,
but the main concern is between now and midnight. The main takeaway
from all of this is to continue to monitor the forecast, and know
where to seek shelter if warnings are issued for your location later
today.

Friday…There is a conditional threat for severe weather across
southern Minnesota into west central Wisconsin, but a lot will depend
on how the overnight convection plays out. Current thinking is that
the atmosphere will have time to destabilize with another round of
storms developing during the afternoon and evening. Once again the
deep layer shear and CAPE profiles would support severe weather.
There is a marginal risk of severe storms, but this could get
adjusted once the first round of storms moves through. A lot will
depend on where the boundaries set up, as cold air advection will be
moving in from the north.

Saturday through Thursday…A weak cold font is forecast to move
through the region and bring a slight reprieve from the heat and
humidity. This will also bring dry conditions over the weekend. Where
this frontal boundary eventually ends up and how quickly it returns
northward will determine when and where rain chances return.
Northwest flow will bring a few weak systems across the region, and
these could spark showers and thunderstorms across the Upper Midwest,
but the majority of the precipitation will be focused along the
aforementioned boundary which should be across the Upper Missouri
River basin. No changes were made to the blended forecast, and there
are small chances for precipitation next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1220 AM CDT Fri Jul 28 2023

VFR and light winds expected for terminals that don't have some
lingering thunderstorms overnight. The best chance for thunderstorms
will be MKT which has a storm almost to the terminal at the issuance
time of this discussion. Chance for showers and an isolated
thunderstorm as well for WI terminals. Heading into Friday VFR
expected at all sites with 5 to 10 knots winds.

KMSP... Chances for thunderstorms have decreased significantly with
the immediate terminal area missing out with storms to the north and
south. VFR with shifting 5 to 10 knot winds.

/OUTLOOK FOR KMSP/
Sat...VFR. Wind N 5-10 kts.
Sun...VFR. Wind NE 10-15 kts.
Mon...VFR. Wind SE 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch until 4 AM CDT early this morning for Anoka-Carver-
     Chisago-Dakota-Hennepin-Isanti-Ramsey-Scott-Sherburne-
     Washington-Wright.

WI...Flood Watch until 4 AM CDT early this morning for Barron-Chippewa-
     Dunn-Eau Claire-Pepin-Pierce-Polk-Rusk-St. Croix.

&&

DISCUSSION...JRB
AVIATION...NDC

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
136 PM CDT Thu Jul 27 2023

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
281845-
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-
136 PM CDT Thu Jul 27 2023

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

.DAY ONE...This Afternoon and Tonight.

Excessive heat is expected today with Heat Index values of 100 to
110 degrees this afternoon.

Severe thunderstorms are possible late this afternoon through the
overnight hours. Large hail & damaging winds are the main
hazards, along with locally heavy rain. The greatest risk for
severe storms will be from central Minnesota into northwest
Wisconsin, where there is an Enhanced Risk (risk level 3 of 5) of
severe weather.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorms are possible Friday, along with the chance for
isolated severe weather.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation will likely be needed this afternoon
and evening.

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1057 PM CDT Thu Jul 27 2023

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

0730 PM     Hail             3 SE Weber              45.44N 93.08W
07/27/2023  M1.25 inch       Isanti             MN   Public

            Delayed report via Facebook, mix of quarter
            to half dollar sized hail.

&&

TDH

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1227 AM CDT Fri Jul 28 2023

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

1140 AM     Tstm Wnd Dmg     1 SE New Ulm            44.31N 94.45W
07/27/2023                   Brown              MN   Public

            Report from mPING: 3-inch tree limbs broken
            with time estimated based on radar.

&&

NDC

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1229 AM CDT Fri Jul 28 2023

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

1215 AM     Tstm Wnd Gst     1 N Skyline             44.15N 94.03W
07/28/2023  M49 MPH          Blue Earth         MN   Mesonet

            Mesonet station MN073 U.s.169 - Mankato - Mp
            52.

&&

NDC

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1234 AM CDT Fri Jul 28 2023

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

1218 AM     Hail             4 SE Oshawa             44.26N 94.05W
07/28/2023  E0.75 inch       Nicollet           MN   Public

            Report from mPING: Dime (0.75 in.) with time
            estimated based on radar.

&&

NDC

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1239 AM CDT Fri Jul 28 2023

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

1231 AM     Tstm Wnd Gst     4 NNW Eagle Lake        44.22N 93.92W
07/28/2023  M49 MPH          Blue Earth         MN   AWOS

            AWOS station KMKT Mankato AP.

&&

NDC

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1258 AM CDT Fri Jul 28 2023

MNZ084-085-093-280645-
Steele MN-Waseca MN-Freeborn MN-
1258 AM CDT Fri Jul 28 2023

...Strong thunderstorms will impact portions of northeastern
Freeborn, Steele and southeastern Waseca Counties through 145 AM
CDT...

At 1258 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Waterville to near Waseca to near Waldorf.
Movement was southeast at 35 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Strong thunderstorms will be near...
  New Richland around 110 AM CDT.
  Medford around 120 AM CDT.
  Owatonna, Ellendale and Geneva around 130 AM CDT.
  Hollandale around 140 AM CDT.
  Blooming Prairie around 145 AM CDT.

Other locations impacted by these storms include Clinton Falls,
Waseca Airport, Lemond, Merton, Steele Center, Otisco, Rice Lake
State Park, Bixby, Deerfield and Owatonna Airport.

This includes the following highways...
 Interstate 35 between mile markers 20 and 49.
 U.S. Highway 14 between mile markers 156 and 182.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4390 9373 4405 9358 4420 9353 4419 9305
      4388 9305 4374 9318
TIME...MOT...LOC 0558Z 294DEG 31KT 4418 9353 4404 9353 4395 9363

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Borghoff