Dry Spell Continues With Frosts

Dry Spell Continues With Frosts:

After a record-setting warm and dry month of September, October has begun warm and dry as well, with zero rainfall reported across 95 percent of the state.

Speaking of rainfall, September was the driest in history for several long-term climate stations in Minnesota, including:

Minneota (Lyon County) with 0”
Canby (Yellow Medicine County0 with a Trace
Alexandria (Douglas County) with .03”
Melrose (Stearns County) and Elk River (Sherburne County) with .05”
MSP with .06”
Park Rapids (Hubbard County), Red Wing (Goodhue County), Windom (Cottonwood County) with .10”
Brainerd (Crow Wing County) with .11”
Marshall (Lyon County) with .15”
Jordan (Scott County) with .16”
Two Harbors 7NW (Lake County) with .17”
Madison (Lac Qui Parle County) and St Peter (Nicollet County) with .18”
Ottertail (Otter Tail County) with .19”

Overall, the statewide average rainfall was 0.55 inches for September, a record low amount. The consequence of this prolonged dry spell continues to show up in the weekly Drought Montor (released October 3rd which shows 94 percent of the state abnormally dry, and 43 percent of the state in Moderate Drought. Another consequence of the prolonged dry spell has shown up in the afternoon relative humidity readings around the state, many of which have ranged from just 16 percent to 24 percent this week, as the National Weather Service has had to issue Red Flag Warnings in some areas for fire danger. Lastly, the dryness has contributed to the National Weather Service issuing frost advisories and freeze warnings for parts of central and northern Minnesota on Thursday night of this week. Friday morning (October 4) brought the most widespread frosts of the autumn season to many parts of central and northern Minnesota, with low temperatures ranging from 24°F to 32°F.

Weekly Weather Potpourri:

As opposed to our very dry September in Minnesota, the BBC Weather Center reported this week that the month was the wettest since 1918 for ten counites in southern England. Many climate stations reported 3 times their normal September rainfall, and the station in Woburn (Bedfordshire) reported 9.80 inches of rain for the month, more than 4 times normal. The rain produced a good deal of flooding in many watersheds.

NOAA reported this week that some of their web services provided by the National Centers for Environmental Information, including the National Climate Data Center in Asheville, NC were down due to impacts from Helene. Some products provided by Climate.gov and Drought.gov are note available. There was not estimate about when they might be restored. Portions of North Carolina, including Asheville reported 14 to 20 inches of rainfall associated with Helene.

An article in Scientific America this week elaborated on the historic and widespread flooding brought by Helene to the Appalachia Region of North Carolina, This flooding was not only the results of 14 to 20 inches of rain from Helene, but also because the previous week had brought widespread rains that had saturated the soils ahead of time causing most of the rain from Helene to runoff and produce extreme flooding.

MPR listener question:

I farm in Southern Minnesota (Austin) and wonder when our first frost will occur. A second question is how frequently do we get late frosts and has this changed?

Answer:

For the most recent three decades (1991-2020), the 50 percent probability date for an autumn frost in the Austin, MN area (Mower County) is September 29. In the 60 years prior to 1990 the 50 percent probability date for a frost was September 26, three days earlier. In terms of more recent trends, the 50 percent probability date for a season ending frost in the Austin area since 2009 has been October 11, or 12 days later. So you are indeed more frequently seeing later and later autumn frosts in your area. This is undoubtedly a climate change signal.

Twin Cities Almanac for October 4th:

The average MSP high temperature for this date is 65 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 46 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for October 4th:

MSP records for this date: highest daily maximum temperature of 89 degrees F in 1922; lowest daily maximum temperature of 41 degrees F in 1885; lowest daily minimum temperature of 24 degrees F in 1935; highest daily minimum temperature of 68 degrees F in 1922, and record precipitation of 4.61 inches in 2005. There was a trace of snow in 1935.

Average dew point for October 4th is 42°F; the maximum dew point on this date is 69°F in 2005 and the minimum dew point on this date is 13 degrees F in 1952.

All-time state records for October 4th:

The state record high temperature for this date is 94 degrees F at Albert Lea (Freeborn County) in 1997. The state record low temperature for this date is 10 degrees F at Ada (Norman County) in 1935. The state record precipitation for this date is 4.61 inches at MSP Airport (Hennepin County) in 2005. The statewide snowfall record for this date is 3.2 inches at Ada (Norman County) in 2012.

Past Weather:

Widespread record-setting low temperatures occurred around the state on October 4 of 1935. Many areas of the state reported morning lows in the twenties F, while observers in 35 central and northern counties reported minimum temperatures in the teens F. The afternoon high temperature only reached 36°F at Brainerd, and at least seven counties reported a trace of snow.

October 4 of 1997 was the warmest in state history with most areas of Minnesota reporting afternoon high temperatures in the 70s and 80s F. Eighteen southern counties reported temperatures of 90°F or greater.

Strong thunderstorms brought heavy and record-setting rainfalls to central and east-central counties over October 4-5 of 2002. There was widespread flash-flooding which closed many roads for days. Many climate stations reported 4-6 inches of rainfall. Wild River State Park in Chisago County reported over 7 inches, while an observer in Rush City (also in Chisago County) reported 8.98 inches.

A very early season snowstorm blanketed north central and northwestern Minnesota over October 4-5 of 2012. Many areas of the state reported a total snowfall of 3-6 inches, while Warroad reported 7 inches, a record amount for so early in the autumn. Temperatures bounced back into the 40s and 50s F over the next two days, so the snow was short-lived.

Outlook:

Warm, sunny, and windy on Saturday with a chance for showers in the far north, but dry elsewhere. Continued warmer than normal next week with little chance for rainfall. Mostly sunny skies.