Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
109 PM CDT Fri Jul 28 2023

.UPDATE...
Issued at 1240 PM CDT Fri Jul 28 2023

Keeping tabs on the potential for convection later on this
afternoon- evening and it's a bit tricky given the multiple CAM
solutions plus the factors working for and against development. There
is a wavy quasi-stationary front draped nearly east-to-east over
northern SD through central MN and northern WI, while a secondary
warm front to the south extends northeast from western IA into
southern WI. While scattered elevated showers are showing up on KMPX
radar in far western MN, not much of this activity is hitting the
ground due to a fairly dry layer from around 3-10 kft off the ground,
thus most of the moisture is coming in the form of virga. However,
surface dewpoints are still around 70 degrees already at the noon
hour. While upper level flow is mainly zonal across the area, there
is a small low-level jet feature over ND that is expected to thrust
ESE into southern MN and northern IA as the afternoon progresses,
thus into the higher low-level moist environment. While coverage is
not expected to be all that impressive, there is the thinking that
any storms that do develop may do so in clusters that could develop
fairly quickly and rise to the level of being strong-severe. The
better environment for organized convection is just to the south of
the WFO MPX coverage area, but there is a wide enough buffer zone
that the speed max could move atop the northern front such that a
wider area of strong-severe thunderstorms in southern MN is viable.
Thus, after collab with SPC, the Slight Risk (level 2 of 5) area of
severe thunderstorms has been nudged a bit more to the north, closer
to the southern TC metro. Still obviously plenty of uncertainty here
as many areas will again receive no rain/storms, but enough
ingredients are available to potentially produce a few strong-severe
thunderstorms late this afternoon into this evening.

18z aviation discussion below.

&&

.DISCUSSION...(Today through Thursday)
Issued at 301 AM CDT Fri Jul 28 2023

Key Messages:

- Scattered showers and thunderstorms possible in southern Minnesota
Friday afternoon and evening. A few severe storms are possible.

- Quiet pattern sets up after today, with cooler temperatures and no
significant chances for precipitation through the middle of next
week.

Discussion... Radar imagery shows the last few storms within
southeastern Minnesota as well as southwestern Minnesota this
morning, with none within the bounds of the MPX CWA as of 2:40AM. A
few isolated showers and weak storms are still possible within
western Wisconsin with a bit of lingering instability, but this will
be less and less likely the further we get through the morning.
Satellite shows the decaying convection with our colder cloud
heights stemming from the supercell thunderstorm that moved through
Mankato a couple hours ago having weakened significantly, with the
best looking storms located in northern Illinois. Clouds will
continue to linger for a good a good portion of the morning, with
some scattering out by the afternoon ahead of another round of
potential showers and storms. Temperatures this afternoon in the
upper 80s to low 90s will be lower than Wednesday and Thursday, but
still above normal, which will allow for ample surface based CAPE by
the afternoon for storms to draw from with HREF ensemble mean of
around 2000-2500 J/KG in southern Minnesota. Forcing will arrive in
the form of a cold front as a weak surface low tracks into the
northern Great Lakes by the evening, with storm chances generally
following along the leading edge of the front and out of the MPX CWA
by the early morning Saturday. In terms of threats, initial
supercell storms ahead of the front could produce some severe hail,
with some larger hail possible for the southwestern portion of
Minnesota, and as activity begins to congeal into a line will
transition to more of a wind threat. There is very limited low level
shear and helicity to work with, so at the moment tornadoes do not
appear to be a significant threat.

As this front departs tomorrow morning, upper level flow transitions
out of the northwest with a weak surface high moving into the
northern plains, with weak but large scale subsidence giving us
clearer skies and a lack of sensible weather through the weekend and
into next week. We remain in this pattern of upper level
northwesterly flow and weak surface high pressure through much of
next week, with adequate moisture for a few storms but a lack of
synoptic scale forcing mechanisms. There will likely be a few days
where some isolated fair weather showers and thunderstorms would be
possible next week, however at this point confidence in timing or
strength for specific days is lacking as we likely will rely on
shortwave energy to force any showers. Most of the deterministic
global models as well as the suite of ensembles do show general
climatology rain chances for a couple days next week, so nothing
conclusive for now. Temperatures will be near normal for much of the
forecast period in the mid 80s with a few upper 80s possible.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1240 PM CDT Fri Jul 28 2023

Able to start out all TAF sites as VFR for the 28/18z TAFs but the
question again is where/when will convection develop later this
afternoon evening. Still plenty of low-level moisture available along
with an approaching cold front from the NW. However, multiple runs of
CAMs still show widely varying solutions of the development of TSRA
this afternoon-evening. Aside from scattered -SHRA at the start near
AXN, confidence is too low to include SHRA/TSRA at any of the TAF
sites for later this afternoon-evening. The best placement of
convection looks to be near KMKT-KMSP-KRNH-KEAU, so have at least
steered those TAFs in that direction by adding in a mid-level deck
(likely cumulus clouds) along with an upper level ceiling. The timing
of that window generally coincides of when convection could occur, so
that should at least make for relatively simple AMDs should that come
to fruition.

KMSP...Have kept the TAF dry at this time due to low confidence in
the placement of any isolated/scattered TSRA development later this
afternoon-evening. That said, the best timing of any development
impacting MSP looks to be in the 23z-04z window later today, hence
the addition of the mid-level clouds and the upper level ceiling.
Once reaching midnight, tranquil conditions are expected thereafter
through tomorrow and the rest of the weekend.

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

&&

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

UPDATE...JPC
DISCUSSION...TDH
AVIATION...JPC

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
1151 AM CDT Fri Jul 28 2023

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
291100-
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-
1151 AM CDT Fri Jul 28 2023

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

.DAY ONE...This Afternoon and Tonight.

Thunderstorms will be possible this afternoon and evening. A few
storms could be strong to severe, mainly along and south of a
line from Redwood Falls MN to the southern Twin Cities metro to
Eau Claire WI. The main hazards are large hail and damaging winds,
though a tornado cannot be ruled out, especially near the Iowa
border.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed late this afternoon into
this evening for southern Minnesota into western Wisconsin.

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1152 AM CDT Fri Jul 28 2023

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

0550 PM     Tstm Wnd Dmg     3 NW Rice Lake          45.52N 91.79W
07/27/2023                   Barron             WI   Trained Spotter

            Tree down, picture via social media.

&&

jrb

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1209 PM CDT Fri Jul 28 2023

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

0640 PM     Tstm Wnd Dmg     4 SW Brooklyn Park      45.09N 93.40W
07/19/2023                   Hennepin           MN   Public

            Delayed report - Image of tree down via
            social media, time estimated from radar.

&&

jrb

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1216 PM CDT Fri Jul 28 2023

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

0632 PM     Tstm Wnd Dmg     2 NE Plymouth           45.05N 93.43W
07/19/2023                   Hennepin           MN   NWS Employee

            Corrected for time to match radar - Delayed
            report of large tree branches down.

&&

jrb

Preliminary Local Storm Report
National Weather Service Twin Cities/Chanhassen MN
1217 PM CDT Fri Jul 28 2023

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

0629 PM     Tstm Wnd Dmg     2 WNW Plymouth          45.04N 93.51W
07/19/2023                   Hennepin           MN   Public

            Corrected for time to match radar - Delayed
            report of large tree down near the
            intersection of Peony Ln and Old Rockford
            Rd. Photo shared via social media.

&&

jrb

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
258 PM CDT Fri Jul 28 2023

MNZ043-044-050-282045-
Benton MN-Mille Lacs MN-Morrison MN-
258 PM CDT Fri Jul 28 2023

...A strong thunderstorm will impact portions of southwestern Mille
Lacs, northeastern Benton and southeastern Morrison Counties through
345 PM CDT...

At 258 PM CDT, Doppler radar was tracking a strong thunderstorm 12
miles north of Foley, or 22 miles southeast of Little Falls, moving
southeast at 25 mph.

HAZARD...Winds in excess of 30 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Milaca and Foreston.

This includes U.S. Highway 169 between mile markers 191 and 198.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in the Twin Cities.

&&

LAT...LON 4584 9401 4590 9396 4583 9352 4565 9376
TIME...MOT...LOC 1958Z 295DEG 20KT 4584 9394

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

CTG

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
336 PM CDT Fri Jul 28 2023

MNZ044-051-052-282115-
Isanti MN-Mille Lacs MN-Sherburne MN-
336 PM CDT Fri Jul 28 2023

...A strong thunderstorm will impact portions of southern Mille Lacs,
western Isanti and northeastern Sherburne Counties through 415 PM
CDT...

At 336 PM CDT, Doppler radar was tracking a strong thunderstorm near
Foreston, or 23 miles northwest of Cambridge, moving southeast at 35
mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Princeton around 350 PM CDT.

Other locations in the path of this storm include Cambridge.

This includes U.S. Highway 169 between mile markers 175 and 192.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4563 9314 4542 9347 4569 9376 4571 9377
      4578 9366
TIME...MOT...LOC 2036Z 303DEG 30KT 4570 9365

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

CTG