Welcome Rains

Welcome Rains:

Since last Friday (September 11) many climate observers have reported significant rainfall. In fact, over 150 climate stations have reported receiving between 1.50 inches and 2.50 inches of rain. Portions of Wadena and Fillmore Counties reported over 3 inches of rain over the past week. There were even a couple of reports of daily record rainfall. Hokah (Houston County) reported a record 2.05 inches on September 15th, while Delano (Wright County) a record 1.70 inches on September 17th.

Rainfall totals through the first 17 days of the month now exceed 3 inches in 20 Minnesota counties. Of further note, Friday will bring chances for significant rainfall across a wide area of the southern half of the state, and for the balance of the month, there will be more frequent chances for rainfall during the last week of the month.

Drought conditions across the state remain a concern with 38 percent of the state in Moderate Drought, 29 percent in Severe Drought (a drop of 13 percent from last week), and 4 percent in Extreme Drought. The NOAA-Climate Prediction Center released a bit more optimistic Drought Outlook on Thursday (September 17) of this week, highlighting that drought should improve or dissipate over the southern half of Minnesota by the end of December, but drought is expected to remain through the end of the year over portions of northern Minnesota.

BTW: Since last Friday, frosts have occurred in portions of St Louis, Koochiching, and Lake of the Woods Counties, with a statewide low of 27°F reported at Brimson (St Louis County) on September 14th. No sign yet of frost anywhere in the southern half of the state.

Weekly Weather Potpourri:

The AGU-EOS Bulletin this week features an interesting article about climate change and low-level ozone in major urban areas. Analysis of air pollution trends in large urban areas like Mexico City shows that major air pollutants are indeed being mitigated by reduced emissions, but continue climate warming and changes in atmospheric dynamics seem to be causing a leveling out of atmospheric ozone. It is an interesting paradox that is deserving of much more study.

In other drought news, much of the United Kingdom has been in drought this year. According to a recent assessment from the BBC Weather Center, above average rainfall is needed over the next 7 months to pull most of the country out of drought. Worst areas of drought are around Cornwell, Devon, and East Anglia. The Met Office estimates a one in four chance that half of the country will still be in drought by next spring.

The Weather Channel web site this week featured a discussion of the expected multi-day rainy period coming up that will threaten flooding across the Upper Midwest, including parts of SE Minnesota. A broad areas from southeastern Minnesota through southern Wisconsin, Northern Illinois and Easter Iowa could see total rainfall over the Friday through Sunday period from 3 inches to 5 inches, with some isolated higher amounts. This is due to a moisture-laden slow-moving frontal boundary.

MPR listener question:

We were wondering if our Minnesota climate history shows that snow has fallen on every day in September at one time or another? We have a major $5 bet riding on this.

Answer:

The answer is no. During the first half of September (1-15), snow has only been reported on two dates historically, September 14 of 1964 when 0.3 inches fell at International Falls, and September 15 of 1916 when 0.4 inches fell at Warroad. Conversely, during the second half of September 16-30), snow has been reported on every date, including 7.5 inches at Long Prairie (Todd County) on September 26 of 1942.

Twin Cities Almanac for September 18th:

The average MSP high temperature for this date is 71 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 51 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 18th:

MSP records for this date: highest daily maximum temperature of 93 degrees F in 1891; lowest daily maximum temperature of 47 degrees F in 1991; lowest daily minimum temperature of 32 degrees F in 1929; highest daily minimum temperature of 71 degrees F in 1955; record precipitation of 3.75 inches in 1905. No snowfall has been reported on this date.

Average dew point for September 18th is 52°F; the maximum dew point on this date is 73°F in 1947; and the minimum dew point on this date is 23°F in 1929.

All-time statewide records for September 18th:

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:

September 18 in 1891 brought summer heat to most parts of Minnesota with daytime temperature readings in the 90s F. Montevideo (Chippewa County) reached a high of 100 degrees F by 3pm after starting out in the morning at just 51°F.

September 18 in1929 was the coldest in history statewide with many climate stations reporting minimum temperatures in the teens and twenties. Nearly every spot in the state reported frost. The daytime high in northern Minnesota only reached the mid-40s F.

September 18 in 1991 brought snow to many parts of western and northern Minnesota. Most climate stations just reported a trace of snow, but in portions of Marshall and Saint Louis Counties measurable snowfall was reported, with up to 2.4 inches at Duluth.

Outlook:

Rain will end for most of the state early Saturday, but portions of southeastern Minnesota will see chances of rain and thunderstorms throughout the weekend and into Monday. Temperatures will generally be a few degrees cooler than normal over the weekend and much of next week. rain chances throughout the weekend. Chances for rain return by the end of next week.