Excessive heat watch and thunder chance for the 4th; SW Minnesota flood update
Southwestern Minnesota had a very wet June:
The last thing that they needed was more rain, but flooding rains hit parts of southwestern Minnesota early this Tuesday morning:
Marshall, Tracy and Redwood Falls were all in the heavy rain path.
Additional reports included 10.50 inches in Wabasso:
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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
451 PM CDT TUE JUL 3 2018
...RAINFALL REPORTS...
LOCATION AMOUNT PROVIDER
WABASSO 10.50 IN TRAINED SPOTTER
REDWOOD FALLS 8.20 IN GOES
3 WSW REDWOOD FALLS 7.12 IN MESONET
SEAFORTH 7.00 IN TRAINED SPOTTER
BEAVER FALLS 5.59 IN GOES
1 SW NORTH REDWOOD 5.25 IN CO-OP OBSERVER
REDWOOD FALLS 5.21 IN GOES
LUCAN 4.55 IN COCORAHS
DELHI 5NE 4.32 IN COCORAHS
OBSERVATIONS ARE COLLECTED FROM A VARIETY OF SOURCES WITH VARYING
EQUIPMENT AND EXPOSURES. WE THANK ALL VOLUNTEER WEATHER OBSERVERS
FOR THEIR DEDICATION. NOT ALL DATA LISTED ARE CONSIDERED OFFICIAL.
The Minnesota State Climatology Office's summary of the torrential rains states:
Repeated heavy thunderstorms produced flash-flooding in southwestern Minnesota during the morning of July 3, 2018.
Thunderstorms developed overnight in the Dakotas and central Minnesota, but one thunderstorm cell that formed between Marshall and Redwood Falls never seemed to go away, and ended up producing rainfall totals of over five inches.
The largest rainfall amounts fell along and southwest of the Minnesota River, in and around Redwood Falls, Marshall, Tracy, Slayton, and Walnut Grove, where rainfall totals of 3-5 inches were common. The National Weather Service Cooperative Observer at Redwood Falls reported 5.25 inches as of 7 AM. of An automated tipping bucket at a stream gaging site near Redwoods Falls unofficially tallied over seven inches.
Their summary includes a radar loop of the thunderstorms. It shows "training" thunderstorms, which means that they were moving over same areas repeatedly, like train cars moving along a rail line.
Many roads were flooded, and some roads were washed out:
Flood warnings and watches
Flood warnings continue for the light-green shaded areas on the Twin Cities NWS office watch/warning map:
Details of the flood warnings:
MNC015-127-042100-
/O.NEW.KMPX.FA.W.0009.180703T2108Z-180704T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Redwood MN-Brown MN-
408 PM CDT TUE JUL 3 2018
The National Weather Service in The Twin Cities has issued a
* Flood Warning for...
Southern Redwood County in southwestern Minnesota...
Southwestern Brown County in south central Minnesota...
* Until 400 PM CDT Wednesday.
* At 400 PM CDT, local law enforcement reported extensive flooding
across central and southern Redwood county. This was the result of
7 to 10 inches of rain that fall across much of Redwood county
during the morning hours today. Near record flooding is expected
along the Cottonwood River and Sleepy Eye Creek.
Near record flooding is currently expected along the Cottonwood
River near Lamberton and Springfield. Lamberton is expected to crest
on Wednesday night or Tuesday morning, with the crest in Springfield
Thursday night or Friday morning.
* Some locations that will experience flooding include...
Walnut Grove, Revere, Wanda, Lamberton, Springfield, and Cobden.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.
MNC127-042115-
/O.NEW.KMPX.FA.W.0010.180703T2118Z-180704T2115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Redwood MN-
418 PM CDT TUE JUL 3 2018
The National Weather Service in The Twin Cities has issued a
* Flood Warning for...
West central Redwood County in southwestern Minnesota...
* Until 415 PM CDT Wednesday.
* At 1030 AM CDT, a record flood crest was recorded on the Redwood
River in Marshall after heavy rain early this morning. This water
will head downstream toward Redwood Falls, with flooding expected
to continue along the Redwood river toward Vesta and Redwood Falls
through Wednesday.
* Some locations that will experience flooding include...
Vesta and Milroy.
MNC033-083-101-117-041800-
/O.NEW.KFSD.FA.W.0018.180703T1809Z-180704T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lyon MN-Pipestone MN-Cottonwood MN-Murray MN-
109 PM CDT TUE JUL 3 2018
The National Weather Service in Sioux Falls has issued a
* Flood Warning for...
Lyon County in southwestern Minnesota...
Northeastern Pipestone County in southwestern Minnesota...
Northwestern Cottonwood County in southwestern Minnesota...
Murray County in southwestern Minnesota...
* Until 100 PM CDT Wednesday.
* At 1258 PM CDT, emergency management reported continued flooding
across the warned area. Three to ten inches of rain fell in these
areas this morning. Even though the rains have ended, flooding
from the earlier rains continues, with numerous county and
township roads flooded or washed out.
This areal flood warning will replace the earlier issued flash flood
warnings in these areas, which will be allowed to expire between 115
PM and 130 PM CDT.
Again, the are numerous roads in the area that are still flooded or
washed out, and travel is not advised in Murray County from the
Emergency Management. Due to the extreme rainfall amounts and the
prolonged wet period, it will take some time before water levels
drop back to normal in these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don`t drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Stay away or be swept away. River banks and culverts can become
unstable and unsafe.
Please report flooding to your local law enforcement agency when you
can do so safely.
The torrential rains will lead to some higher river levels in southern Minnesota.
You can go to the Advanced Hydrologic Prediction Service page and click on a location for river level details and forecasts.
Updated weather information can be heard on the Minnesota Public Radio Network, and updates are also posted on the MPR News live weather blog.
There's a flood watch in effect until 7 p.m. Wednesday for portions of northern Minnesota:
How rare are these flooding rains?
There was an unofficial report of 7 inches of rain at Redwood Falls, and a few higher amounts elsewhere.
NOAA's Atlas14 is the most modern way to estimate how often a specific location can be expected to see a specific amount of rain.
Here's what Atlas 14 shows for Redwood Falls:
It appears that Redwood Falls was in the "500 year rainfall" range with their 7 to 8 inch total in 6 hours. Wabasso, to the southwest of Redwood Falls, was probably in their "1000 year rainfall" category with over 10 inches.
The Twin Cities metro area 10-inch rainfall on July 23-24, 1987 was in the 500 year storm category on the Atlas 14 chart, but it was only about an inch from reaching the 1000 year storm category for the metro area.
Thunderstorm chances
Scattered showers and thunderstorms are possible in northern and central Minnesota overnight this Tuesday night, and in all parts of Minnesota on the 4th of July.
Several rain-free hours are expected on Wednesday, but there's a chance that showers and thunderstorms will affect some festivities.
Some of the thunderstorms could be severe.
The Storm Prediction Center of the NWS has a large portion of Minnesota in a slight risk of severe weather Wednesday and Wednesday night:
Slight risk means that scattered severe thunderstorms are possible:
The heat
Northern Minnesota will have highs in the lower 80s on the 4th of July.
It's a different story in the south, with lower 90s on tap in many spots:
The Twin Cities metro area, and areas to the south and east, are in an excessive heat watch from 11 a.m. to 9 p.m. on the 4th of July:
Details of the excessive heat watch:
URGENT - WEATHER MESSAGE
National Weather Service Twin Cities/Chanhassen MN
349 PM CDT Tue Jul 3 2018
MNZ060>063-068>070-040500-
/O.CON.KMPX.EH.A.0003.180704T1600Z-180705T0200Z/
Hennepin-Anoka-Ramsey-Washington-Carver-Scott-Dakota-
Including the cities of Minneapolis, Blaine, St Paul, Stillwater,
Chaska, Shakopee, and Hastings
349 PM CDT Tue Jul 3 2018
...EXCESSIVE HEAT WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH WEDNESDAY EVENING...
* TEMPERATURE...High temperatures in the low to mid 90s will
combine with high humidity to yield dangerous heat indices on
Wednesday afternoon and evening. Peak afternoon heat indices
around 105 degrees are possible.
* IMPACTS...Heat illnesses are possible for those active
outdoors or those susceptible to heat illnesses, such as
children and the elderly.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
An Excessive Heat Watch means that a prolonged period of hot
temperatures is expected. The combination of hot temperatures and
high humidity will combine to create a dangerous situation in
which heat illnesses are possible. Drink plenty of fluids...stay
in an air-conditioned room...stay out of the sun...and check up
on relatives and neighbors.
Southeastern Minnesota is in a heat advisory during the afternoon and early evening of the 4th.
It'll be cooler on Thursday, and throughout the coming weekend.
Twin Cities metro area highs are expected to be in the lower 80s Thursday and Friday, followed by middle 80s this weekend.