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...UPDATED
National Weather Service Twin Cities/Chanhassen MN
411 PM CDT Fri Aug 24 2018

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
252115-
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-
411 PM CDT Fri Aug 24 2018

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

.DAY ONE...Tonight

Scattered thunderstorms are expected this evening. A couple severe
storms are possible across southern Minnesota.

Widespread dense fog is expected overnight into Saturday morning.

.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 may be needed across southern Minnesota
this evening.

Borghoff

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Twin Cities/Chanhassen MN
505 PM CDT FRI AUG 24 2018

MNZ083-084-242315-
Waseca-Blue Earth-
505 PM CDT FRI AUG 24 2018

...VERY HEAVY RAIN AND LOCALIZED MINOR FLOODING EXPECTED...

VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED FLOODING WILL AFFECT
THE FOLLOWING COUNTIES...

Waseca...Blue Earth...

At 505 PM CDT...VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED
FLOODING WAS over Waldorf.

LOCATIONS IMPACTED INCLUDE...
New Richland, Waldorf and Otisco.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...AS WELL AS FARM AND COUNTRY ROADS. DO NOT
ATTEMPT TO TRAVEL ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

LAT...LON 4385 9392 4397 9392 4395 9341 4385 9341
TIME...MOT...LOC 2205Z 180DEG 0KT 4390 9362

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Twin Cities/Chanhassen MN
507 PM CDT FRI AUG 24 2018

MNZ049-242315-
Stearns-
507 PM CDT FRI AUG 24 2018

...VERY HEAVY RAIN AND LOCALIZED MINOR FLOODING EXPECTED...

VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED FLOODING WILL AFFECT
THE FOLLOWING COUNTIES...

Stearns...

At 506 PM CDT...VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED
FLOODING WAS over Padua.

LOCATIONS IMPACTED INCLUDE...
Elrosa, Spring Hill and Padua.

This includes U.S. Highway 71 between mile markers 151 and 161.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...AS WELL AS FARM AND COUNTRY ROADS. DO NOT
ATTEMPT TO TRAVEL ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

LAT...LON 4568 9502 4553 9482 4546 9492 4560 9513
TIME...MOT...LOC 2206Z 267DEG 0KT 4558 9497

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Twin Cities/Chanhassen MN
522 PM CDT FRI AUG 24 2018

WIZ014-023-024-242345-
Polk-Pierce-St. Croix-
522 PM CDT FRI AUG 24 2018

...HEAVY RAIN AND LOCALIZED MINOR FLOODING EXPECTED...

HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED FLOODING WILL AFFECT THE
FOLLOWING COUNTIES...

Polk...Pierce...St. Croix...

At 520 PM CDT...radar estimates and spotter reports indicated
localized rainfall amounts in excess of 4 inches with widespread
amounts of 1-2 inches since earlier today. Additional showers and
thunderstorms could produce another inch of rain locally.

LOCATIONS IMPACTED INCLUDE...
River Falls, Hudson, New Richmond, North Hudson, Afton, Baldwin,
Hammond, Roberts, Woodville, Clear Lake, Clayton and Lakeland.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE PONDING OF WATER IN
URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER
POOR DRAINAGE AREAS AND LOW LYING SPOTS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

IN HILLY TERRAIN THERE ARE LOW WATER CROSSINGS WHICH ARE POTENTIALLY
DANGEROUS IN HEAVY RAIN.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE.

LAT...LON 4512 9216 4481 9240 4477 9252 4483 9256
      4492 9248 4494 9257 4477 9279 4482 9277
      4490 9278 4494 9275 4500 9277 4519 9251
      4534 9216
TIME...MOT...LOC 2220Z 267DEG 0KT 4489 9242

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

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

1100 AM     HEAVY RAIN       4 N GLENWOOD CITY       45.12N 92.17W
08/24/2018  M5.92 INCH       ST. CROIX          WI   PUBLIC

            THE DURATION OF THE HEAVY RAIN EVENT WAS 4
            HOURS.

&&

CEO

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

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

1200 PM     HEAVY RAIN       RIVER FALLS             44.86N 92.62W
08/24/2018  M6.00 INCH       PIERCE             WI   PUBLIC

            START TIME ESTIMATED. THE DURATION OF THE
            HEAVY RAIN EVENT WAS 5 HOURS.

&&

CEO

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Twin Cities/Chanhassen MN
537 PM CDT FRI AUG 24 2018

WIZ023-024-250000-
Pierce-St. Croix-
537 PM CDT FRI AUG 24 2018

...VERY HEAVY RAIN AND LOCALIZED MINOR FLOODING EXPECTED...

VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED FLOODING WILL AFFECT
THE FOLLOWING COUNTIES...

Pierce...St. Croix...

At 536 PM CDT...VERY HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED
FLOODING WAS over River Falls.

LOCATIONS IMPACTED INCLUDE...
River Falls, Prescott, Ellsworth, Diamond Bluff and Beldenville.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE PONDING OF WATER IN
URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER
POOR DRAINAGE AREAS AND LOW LYING SPOTS. DO NOT ATTEMPT TO TRAVEL
ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES. IT TAKES ONLY A FEW
INCHES OF SWIFTLY FLOWING WATER TO CARRY VEHICLES AWAY.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...AS WELL AS FARM AND COUNTRY ROADS. DO NOT
ATTEMPT TO TRAVEL ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES.

LAT...LON 4472 9274 4474 9279 4476 9281 4494 9256
      4492 9248 4483 9256 4477 9252 4481 9239
      4465 9263
TIME...MOT...LOC 2236Z 267DEG 0KT 4476 9264