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Extension > Mark Seeley's WeatherTalk > June frosts in the north country

Friday, June 10, 2016

June frosts in the north country



June frosts in the north country:

June 7 and 8 brought cold morning temperatures to many parts of the state, especially northeastern counties. Many climate observers reported morning lows in the 30s F, and several reported frost. A number of climate stations also reported new record daily low temperatures. These included:
June 7th 37F at Kabetogama and Littlefork
June 8th: 28F at Crane Lake; 29F at Hibbing and Orr; 30F at International Falls and Babbitt; and 37F at Sandstone.

Actually frosts this time of year are not all that unusual in northern Minnesota counties, with a 10 to 20 percent historical frequency during the 2nd week of June.

Heavy rains on June 9th:

The heaviest rains of the month so far occurred on June 9th. Dew points climbed from 40F the previous day into the low 60sF just before the rains occurred. Many observers reported over 1 inch of rainfall, and a few southern Metro observers reported over 2 inches, including a record daily value of 2.52 inches at the National Weather Service Forecast Office in Chanhassen. A couple of spots in Chaska reported over 3 inches.

The Urban Heat Island Explored by Bicycle:

A number of years ago an article in Weather magazine described the urban heat island of Reading, England as measured by a bicyclist who used a simple digital thermometer
with a 10 second response time. He repeatedly cycled 5 mile long transects through the city center near sunset and recorded temperatures along the way about every 1 km. His
measurements showed a mean urban heat island effect of about 3 to 4 degrees F, that is the city center tended to be that much warmer than the perimeter areas around the city.
Under some conditions, he measured a maximum temperature difference of over 12 degrees F.

These temperature data are similar in magnitude to some of those being measured by the "Islands in the Sun" project of Dr. Snyder and Dr. Twine here in the Twin Cities Metro Area, where the frost-free season can vary in length by as much as 8 to 12 days.

I would be interested to hear from any listeners or readers who routinely bicycle around the Twin Cities area and have found highly perceptible differences in temperature along
the routes they take. I would suspect that some city parks and/or city lakes may have some noticeable cooling effects on air temperature, especially in the summer months.

Weekly Weather Potpourri:

NOAA scientists this week offer a more detailed discussion of the 2016 North Atlantic Hurricane Season Outlook. They particularly spend time describing why the outlook is so uncertain this year.

A recent paper in Nature Communications discusses Arctic warming and how it is affecting the melting rate of Greenland's ice sheet as well as the polar jet stream. The authors suggest we will witness mote surprising changes in the behavior of the Arctic climate system in coming years.

AGU published an interesting retrospective on the Mt Pinatubo eruption 25 years ago, and the scientific knowledge accrued since that time. It is very interesting reading.

MPR listener question:

What are the records for most single day rainfall and most monthly rainfall in June?

Answer:

The single day record is 10.40 inches at Two Harbors on June 20, 2012 (Duluth Flood), while the monthly record is 15.63 inches at Delano in June of 2002.

Twin Cities Almanac for June 10th:

The average MSP high temperature for this date is 77 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 57 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for June 3rd:

MSP weather records for this date include: highest daily maximum temperature of 99 degrees F in 1956; lowest daily maximum temperature of 55 degrees F in 1945; lowest daily minimum temperature is 40 degrees F in 1877; highest daily minimum temperature of 73 degrees F in 1973; record precipitation of 1.77 inches in 1874; and no snowfall has occurred on this date.

Average dew point for June 3rd is 53 degrees F, with a maximum of 73 degrees F in 2002 and a minimum of 20 degrees F in 1972.

All-time state records for June 10th:

The state record high temperature for this date is 106 degrees F at Fairmont (Martin County) in 1933. The state record low temperature for this date is 22 degrees F at Remer (Cass County) in 1985. State record precipitation for this date is 6.05 inches at Agassiz Refuge (Marshall County) in 2002; and no measurable snowfall has occurred on this date.

Word of the Week: "Sheep's Cold"

This expression comes courtesy of Jo Farrow of the BBC Weather Centre. In Austria a late spring or early summer cold spell that comes close to June 11 is referred to as "sheep's cold" weather (or schafskalte). It brings a bit of a shock to the sheep as they have typically just been sheared for the impending summer season and are therefore more susceptible to the cold. So I guess you could call the cold mornings in northern Minnesota this week, when temperatures dipped into the 20s F, "sheep's cold."

Past Weather Features:

The hottest June 10th in state history occurred in 1933. Nearly every part of the state reached 90F or greater that day with 10 climate stations reporting 100F or greater. It was a trend that lasted all month,as June of 1933 was the hottest in state history.

Many areas of the state reported frost on June 10, 1972. Several climate stations in northeastern Minnesota reported low temperatures in the 20s F, and frost was reported as far south as Zumbrota (Goodhue County), where some soybean fields had to be replanted.

Strong thunderstorms brought record-setting rains and flash floods to many parts of the state over June 9-10, 2002. Portions of Lake of the Woods and Roseau Counties saw 12 to 14 inches of rain, sending a record flood crest down the Roseau River. More details can be found from the Minnesota State Climatology Office.

Outlook:

Warm weekend coming up with chances for showers and thunderstorms by Sunday. Continued chance for showers into Monday and Tuesday, but with cooler temperatures that are closer to normal.

 






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