Warm Start to September Coming to an End

 

Warm Start to September Coming to an End:

Through the first 10 days of the month, temperatures have been averaging from 5°F to 10°F above normal in most areas of Minnesota. In fact, temperatures of 90°F or higher have been reported in 33 counties. Within the state climate stations network there have been 9 reports of new daily record high temperatures, including 94°F a Theilman (Wabasha County) on the 5th, and 15 reports of record warm overnight temperatures, including 72°F at Pipestone on the 6th.

The warmer than normal temperature pattern will end this weekend and a period of cooler than normal temperatures will begin. Starting on Saturday and running through most of next week much cooler air will blanket the state, bringing overnight low temperatures in the 40s F and 50s F, even some upper 30s F in northern counties. Though cooler, these temperatures are no where near record lows for this time of year.

Some fairly widespread rain over the past week was very welcome across the state. Many northern and southern areas reported over 1 inch of rain, and up to 3 inches in some areas. There were even a few record-setting daily amounts, including:

For September 7th:

1.82 inches at OtterTail
1.93 inches at Pipestone
1.97 inches at Fergus Falls
2.29 inches at Worthington
4.11 inches at Lake Bronson

for September 8th:

1.41 inches at Cambridge

These rains were not factored into the weekly U.S. Drought report which showed that Minnesota has 25 percent of the landscape in Moderate Drought, 42 percent in Severe Drought, and 4 percent in Extreme Drought. As crop harvest gets underway, only 58 percent of the corn is reported by the USDA to be in good to excellent condition, while 56 percent of the soybeans are in good to excellent condition.

Weekly Weather Potpourri:

The BBC Weather Center this week reports on climate change impacts that convective thunderstorm activity during the northern hemisphere summer has been more disruptive to commercial air traffic over the United Kingdom and northern Europe. Further, this is a trend that is likely to continue as climate change brings more convective thunderstorms to higher latitude cities in Europe. When transcontinental flights arrive over Europe, they are usually low on fuel and therefore have more limited geographic options to seek alternative airports if thunderstorms change their routes and destination. Air traffic controllers hope that scientists will study this type of climate change impact more in the future.

Science Daily reported earlier this month that an extremely large iceberg (29 square miles in size) broke away from Greenland’s Petermann Glacier and drifted into Nares Strait where it collided with Joe Island. But the iceberg survived. It was the largest calving event in Greenland since 2020.

MPR listener question:

We have heard you lecture about climate change in Minnesota over the past many years and wanted to know what has been the change in average temperature across the state by season?

Answer:

According to the latest NOAA climate statistics which go back to 1895 on a statewide basis here are the seasonal mean temperature changes in Minnesota:

Autumn (Sep-Nov) +2.6°F
Winter (Dec-Feb) +5.2°F
Spring (Mar-May) +2.6°F
Summer (Jun-Aug) +2.6°F

The overall change in annual temperature since 1895 has been +3.5°F

Twin Cities Almanac for September 11th:

The average MSP high temperature for this date is 75 degrees F (plus or minus 10 degrees F standard deviation), while the average low is.56 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 11th:

MSP records for this date include: highest daily maximum temperature of 96 degrees F in 1931; lowest daily maximum temperature of 51 degrees F in 1924; lowest daily minimum temperature of 35 degrees F in 1962; highest daily minimum temperature of 75 degrees F in 1931; record precipitation of 3.11 inches in 1900. No snowfall has been reported on this date.

Average dew point for September 11th is 55°F; the maximum dew point on this date is 74°F in 1960; and the minimum dew point on this date is 35°F in 1974.

All-time statewide records for September 11th:

The state record high temperature for this date is 111 degrees F at Beardsley (Big Stone County) in 1931. The state record low temperature for this date is 22 degrees F at Ada (Norman County) in 1955. The state record precipitation for this date is 5.50 inches at Pleasant Mound (Blue Earth County) in 1900. No snowfall has been reported on this date.

Past Weather:

By far the hottest ever September 11th was in 1931 when every place in the state saw afternoon temperatures climb into the 90s F, except for Two Harbors, Moose Lake, and Grand Marais. Ten climate stations hit the century mark in temperature.

A hard freeze in the north and widespread frosts in the central and southern counties were in the weather headlines for September 11, 1955. The growing season across Minnesota abruptly ended. Temperatures were as low as 22-26 degrees F in the Red River Valley of northwestern Minnesota.

This past Tuesday marked the 126th anniversary of the most lethal hurricane disaster in U.S. history. Galveston, TX was hit by 120 mph winds and a 20 foot storm surge on September 8, 1900. More than 6,000 people drowned and over 3600 homes were destroyed. This hurricane tracked north over Texas and the southern plains to merge with a cold front over Iowa by September 10th. The storm then produced a period of very heavy rain over Minnesota.

In fact, the record Twin Cities rainfall for today's date of 3.11 inches is a direct result of this storm. Other parts of southern Minnesota reported 4 to 6 inches of rainfall as a result of this storm.

Outlook:

Cooler over the weekend with an increasing chance for showers and thunderstorms on Sunday, and a greater chance on Monday. Temperatures will generally run cooler than normal for this time of year over much of next week, with a chance for showers by Wednesday and Thursday.