Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
248 PM CDT Fri Aug 24 2018

.SHORT TERM...(This evening through Saturday)
Issued at 248 PM CDT Fri Aug 24 2018

Scattered thunderstorms are developing across western MN near the
upper low. The system will continue progressing eastward tonight,
spreading the showers and thunderstorms eastward through mid
evening. The atmosphere just ahead of the upper low has become
moderately unstable with MLCAPE values around 2000J/kg, but
effective shear is quite weak and confined to along the Iowa
border. This should keep thunderstorm activity largely weak, but a
few cells could briefly reach severe limits with a hail threat.
The loss of daytime instability will allow for a gradual weakening
after early-mid evening.

Winds will become light and skies will clear some following the
passage of the upper low center. This will allow widespread dense
fog to form over much of the region overnight. Models are quite
pessimistic with visibilities and will probably need a Dense Fog
Advisory into Saturday morning.

Fog will burn off and stratus will gradually lift late Saturday
morning with skies breaking up by early afternoon. Temperatures
should respond quickly rising into the mid 80s in most locations
for highs.

.LONG TERM...(Saturday night through Friday)
Issued at 248 PM CDT Fri Aug 24 2018

Strong to severe thunderstorms are possible Sunday and through
Tuesday morning. A few tornadoes, large hail, and damaging wind
are possible, along with heavy rain. Cooler weather will settle in
for Tuesday, and Wednesday as high pressure builds across the
region, but southerly winds will return Wednesday night with rain
chances increasing from west to east through Thursday. Looking
ahead, active weather could continue into next weekend as well.

A fairly persistent southwest jet will be in place across the Upper
Midwest for most of next week. There is a subtropical component and
a poler component to this jet. This will create deep layer wind
shear that is favorable for organized thunderstorms, including
supercells. Meanwhile at the surface, southerly flow with bring
dewpoints in the lower 70s by early next week. Couple this with an
elevated mixed layer originating from the Central Rockies, and the
ingredients are in place for the development of 2000-4000 J/kg of
MLCAPE together with deep layer shear of 40-50 kts. This should
support multiple rounds of strong to severe thunderstorms next week.
This set up is pretty consistent among the various forecast model
runs, so confidence is increasing in active weather across parts
of Minnesota and Wisconsin.

There is still uncertainty in the details, such as where the CAPE
gradient will set up, and what types of boundaries will be in place,
as well as the timing of the shortwaves within the aforementioned
southwest flow, but the bottom line is the potential is there for
severe weather Sunday through early Tuesday, and again later in the
week. High temperatures will depend heavily on cloud cover and
convection, so continued with a blended model approach.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 106 PM CDT Fri Aug 24 2018

IFR conditions are in place across most of MN and WI, but
conditions are improving to VFR across western MN. Improving cigs
should reach I-94 and south this afternoon, but IFR cigs will
likely persist through the period at RNH and EAU. Scattered
showers and a few thunderstorms are already developing again near
the upper low to the west and this activity will become more
widespread later this afternoon. Convection will diminish mid
evening. Widespread dense fog will likely develop overnight at all
TAF sites.

KMSP...Should be free of TS for the next couple/few hours until
mid afternoon, then chances increase again into mid evening. IFR
CIGS should improve some this afternoon before deteriorating again
overnight.

/OUTLOOK FOR KMSP/
Sun...MVFR possible in scattered SHRA/TSRA. Winds S 5-15 kt
becoming SW.
Mon...MVFR possible early in scattered SHRA/TSRA. Wind SW 10-20
kt.

&&

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

SHORT TERM...BORGHOFF
LONG TERM...JRB
AVIATION...BORGHOFF

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
208 PM CDT Fri Aug 24 2018

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
251915-
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-
208 PM CDT Fri Aug 24 2018

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

.DAY ONE...This Afternoon and Tonight

There is a chance for thunderstorms across the entire coverage
area through this evening. There is a slight to marginal risk of
severe weather mainly south of I-94.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

There are several chances for strong to severe storms and heavy
rain next week. At this point the highest chance is late Sunday
through Tuesday morning along and north of I-94.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation will not be needed.

jrb

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
945 AM CDT FRI AUG 24 2018

MNZ060>062-241515-
Anoka-Hennepin-Ramsey-
945 AM CDT FRI AUG 24 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN
HENNEPIN...ANOKA AND RAMSEY COUNTIES...

At 944 AM CDT, radar indicated strong thunderstorms were located
along a line extending from near Stacy to Minnetonka. Movement was
east at 25 mph.

Dime size hail and heavy rain are possible with these storms.

Locations impacted include...
Minnesota State Fair, Minneapolis, St. Paul, Brooklyn Park,
Plymouth, Maple Grove, Coon Rapids, Blaine, Minnetonka, Edina, St.
Louis Park, Maplewood and Roseville.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 4513 9302 4512 9299 4492 9305 4492 9313
      4491 9314 4490 9354 4541 9324 4541 9302
TIME...MOT...LOC 1444Z 257DEG 20KT 4542 9308 4491 9346

JRB

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1037 AM CDT FRI AUG 24 2018

MNZ060>063-241615-
Anoka-Washington-Hennepin-Ramsey-
1037 AM CDT FRI AUG 24 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT EAST CENTRAL
HENNEPIN...SOUTHEASTERN ANOKA...NORTHWESTERN WASHINGTON AND RAMSEY
COUNTIES...

At 1036 AM CDT, radar indicated strong thunderstorms were located
along a line extending from Mounds View to MSP International Airport.
Movement was east at 25 mph.

Nickel size hail and heavy rain are possible with these storms.

Locations impacted include...
Minnesota State Fair, Minneapolis, St. Paul, Brooklyn Park,
Woodbury, Coon Rapids, Blaine, Maplewood, Richfield, Roseville,
Brooklyn Center, Oakdale and Fridley.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 4491 9289 4490 9303 4492 9305 4492 9313
      4489 9316 4488 9318 4487 9329 4513 9329
      4525 9287
TIME...MOT...LOC 1536Z 255DEG 23KT 4512 9321 4491 9323

JRB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1058 AM CDT FRI AUG 24 2018

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

1057 AM     HAIL             SHOREVIEW               45.08N 93.14W
08/24/2018  E0.88 INCH       RAMSEY             MN   TRAINED SPOTTER

&&

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1208 PM CDT FRI AUG 24 2018

MNZ078-241745-
Goodhue-
1208 PM CDT FRI AUG 24 2018

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL GOODHUE COUNTY...

At 1207 PM CDT, a strong thunderstorm was located near Goodhue, or
near Red Wing, moving northeast at 50 mph.

Nickel size hail is possible with this storm.

Locations impacted include...
Red Wing, Goodhue, Welch, Vasa, Wacouta and Frontenac State Park.

This includes U.S. Highway 61 between mile markers 83 and 100.

LAT...LON 4441 9277 4466 9266 4464 9262 4461 9261
      4460 9256 4457 9255 4457 9251 4455 9234
      4435 9264
TIME...MOT...LOC 1707Z 217DEG 43KT 4447 9263

JRB

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
212 PM CDT FRI AUG 24 2018

MNZ065-242000-
Renville-
212 PM CDT FRI AUG 24 2018

...A SLOW MOVING THUNDERSTORM WITH HEAVY RAIN WILL AFFECT
NORTHWESTERN RENVILLE COUNTY...

At 211 PM CDT, a strong thunderstorm was located over Sacred Heart,
or 20 miles northwest of Redwood Falls, moving east at 5 mph.

Locations impacted include...
Renville and Sacred Heart.

This includes U.S. Highway 212 between mile markers 57 and 67.

Torrential rainfall is occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 4477 9540 4486 9539 4489 9517 4472 9518
TIME...MOT...LOC 1911Z 275DEG 6KT 4478 9534

JRB

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
330 PM CDT FRI AUG 24 2018

MNZ083-084-242130-
Waseca-Blue Earth-
330 PM CDT FRI AUG 24 2018

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN BLUE EARTH AND
SOUTHERN WASECA COUNTIES...

At 329 PM CDT, a strong thunderstorm was located near Minnesota Lake,
or 21 miles southeast of Mankato, moving northeast at 20 mph.

Winds in excess of 30 mph and dime size hail are possible with this
storm.

Locations impacted include...
Waseca, New Richland, Waldorf and Otisco.

This includes U.S. Highway 14 between mile markers 157 and 165.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4391 9391 4414 9341 4390 9341 4384 9355
      4385 9388
TIME...MOT...LOC 2029Z 242DEG 17KT 4389 9378