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Extension > Mark Seeley's WeatherTalk > Wet week

Friday, May 24, 2013

Wet week

Wet week

Many Minnesota observers, especially those in southern counties, have reported 6 to 7 consecutive days with rain over the past week. Over the period from May 17 to May 21 a number of observers reported new daily record rainfall amounts. Dozens of daily records were set, too many to list here. But some examples are:
May 17: 1.51" at Sherburn
May 18: 1.87" at Dodge Center, 1.78" at Spring Valley, 1.51" at Long Prairie, and 1.43" at Milaca
May 19: 1.46" at Jordan, 2.07" at Rochester, and 1.31" at Rothsay
May 20: 4.47" at Spring Valley, 4.01" at Thief River Falls, 2.75" at Grand Meadow, 2.21" at Grand Portage, and 2.01" at Roseau
May 21: 1.40" at Wadena and 1.15" at Walker

The wet week was dominated by high dewpoints. Just before 5:00 pm on Sunday, May 19th, the Twin Cities (MSP Airport) reported a dewpoint of 66 degrees F, tying the all-time highest value for the date set in 2004. Other observation sites reported dewpoints in the low to mid 60s F as well, very high values for this time of year.

Wet month

The month of May has brought measurable rainfall on many days. Of the first 24 days of the month many observers report rainfall on 15 or 16 days, a very high frequency. Accumulated rainfall for the month is already record-setting at many southern Minnesota locations, with a week to go in the month. Some of those already reporting record rainfall amounts for the month include:
12.13 inches at Grand Meadow, 9.16 inches at Spring Valley, 9.03 inches at Austin, and 8.63 inches at Rochester. The all-time maximum rainfall for the month of May in Minnesota is 15.79 inches at St Francis (Anoka County) in 2012. If Grand Meadow (Mower County) has a wet last week of May, they may threaten that state record this month.

For southeastern Minnesota counties May of 2013 already ranks as the 5th wettest May in history, averaging nearly 7 inches of rainfall. This number is likely to increase over the next week before the month concludes next Friday.

Wet spring

Since March 1st, the area of the Minnesota landscape designated to be in severe to extreme drought has shrunk from 70 percent to less than 7 percent. This is the result of abundant precipitation. The period since March 1st (meteorological spring) has been one of the wettest in history for many areas of the state. Across southern Minnesota many communities have reported over 12 inches of precipitation since March 1st. Some southeastern observers like Preston, Rochester, Winona, Spring Valley, and Lanesboro have reported over 15 inches, while Grand Meadow has reported nearly 22 inches of precipitation this spring. In fact southeastern Minnesota counties have already reported their wettest spring in history, with one week to go in May. Lakes, rivers, and streams have seen a great deal of recharge. In addition dry soils have been recharged and in some cases saturated so that tile lines have been running this month to discharge the surplus moisture.

The pattern of wetness for the year 2013 is expected to continue into the first week of June, with more frequent and sometimes heavy showers, especially in southern Minnesota.

Weekly Weather potpourri

In its 2013 Atlantic hurricane season outlook issued Thursday (May 23), NOAA's Climate Prediction Center forecasted an active or extremely active Atlantic hurricane season this year. For the six-month hurricane season, which begins June 1, NOAA's Atlantic Hurricane Season Outlook says there is a 70 percent likelihood of 13 to 20 named storms (winds of 39 mph or higher), of which 7 to 11 could become hurricanes (winds of 74 mph or higher), including 3 to 6 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher). These ranges are well above the seasonal average of 12 named storms, 6 hurricanes and 3 major hurricanes. You can read more about this outlook here.

The powerful tornado (EF-5) that hit Moore, OK (near Oklahoma City) was the 7th such storm since 1950 to hit that state. The only other state to report 7 EF-5 level tornadoes since 1950 is Alabama. Minnesota has reported just 2 EF-5 tornadoes over the same period (June 13, 1968 at Tracy, and June 16, 1992 at Chandler). Paul Huttner, MPR chief meteorologist posted a good deal of information about the Oklahoma tornado on his Updraft blog this week. You can read more here.

The United Kingdom Meteorological Office reported this week that their country has experienced the coldest meteorological spring (March-May) since 1979, and the 6th coldest of all-time. Cold spells and widespread frosts were evident in many places. You can read more here.

For auto racing fans, the Indianapolis Office of the National Weather Service has posted on their web site the history of environmental conditions for the Indianapolis 500 event, scheduled this year for Sunday, May 26th. This year race day is expected to see temperatures in the 60s F with a chance for showers. The wettest race in history was in 2004 when nearly 4 inches of rain fell. You can read more about the past climate for the race here.

MPR listener questions

Has it ever snowed on Memorial Day in Minnesota?

Answer: Yes, our state climate database shows this has happened at least twice. Memorial Day prior to 1967 was always observed on May 30th, then it became the last Monday in the month of May. On May 30, 1897 it snowed at Bemidji (0.1 inches), and on May 25, 1992 it snowed in New Ulm (1.3 inches). It was also cold on Memorial Day in 1992 with many observers reporting morning lows in the 20s F.

I farm in Redwood County (southwestern Minnesota) where soil moisture values were extremely depleted last fall (2012). How much have conditions improved lately relative to stored soil moisture?

Answer: Stored soil moisture values have improved significantly this month. The University of Minnesota Research and Outreach Center at Lamberton reported a stored soil moisture value of 5.33 inches in the top 5 feet of soil on May 15th. This is the highest measured stored soil moisture there since mid-June of last year. It is still below normal for this time of year, but showing improvement.

Twin Cities Almanac for May 24th

The average MSP high temperature for this date is 71 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 51 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for May 24th

MSP weather records for this date include: highest daily maximum temperature of 95 degrees F in 2010; lowest daily maximum temperature of 49 degrees F in 1893; lowest daily minimum temperature of 32 F in 1925; highest daily minimum temperature of 72 F in 2010; and record precipitation of 1.27 inches in 1937; There was a trace of snow on this date in 1924.

Average dew point for May 24th is 48 degrees F, with a maximum of 71 degrees F in 1989 and a minimum of 20 degrees F in 1934.

All-time state records for May 24th

The state record high temperature for this date is 98 degrees F at Beardsley (Big Stone County) in 1928. The state record low temperature for this date is 18 degrees F at Mora (Kanabec County) in 1988. State record precipitation for this date is 3.60 inches at Long Prairie (Todd County) in 1939; and the state record snowfall for this date is 1.0 inches at Pigeon River Bridge (Cook County) in 1930.

Past Weather Features:

Between 4:00 and 4:30 pm on May 24, 1908 F-2 (winds 113-157 mph) tornadoes touched down in Martin and Blue Earth Counties of southern Minnesota. The first tornado was east of Fairmont and on the ground for 3 miles, destroying a number of farm buildings and a farmhouse. Five people were injured and a horse was killed. The second tornado was on the ground for 20 miles and passed north of Mapleton and over Lake Ballentine, where it became a waterspout for a brief period. It destroyed one home and many farm buildings.

May 24, 1925 was probably the coldest in Minnesota history with over 30 communities reporting frost. It was unexpected as two days before temperatures had soared into the 90s F. On May 22, 1925 Fairmont reported an afternoon high of 100 degrees F, then 36 hours later on the morning of the 24th they reported 33 degrees F. There was frost as far south as Zumbrota (Goodhue County). In many areas morning temperatures fell into the 20s F. Corn fields showed signs of severe frost damage and many fields had to be replanted.

May 24, 1928 brought temperatures in the 90s F to a dozen Minnesota counties, setting daily record highs in many communities. The warm spell was short-lived as the last week of the month brought cooler than normal temperatures in the 50s and 60s F.

May 24-28, 1939 brought a very wet spell of weather to Minnesota. Many observers reported 2 to 5 inches of rainfall, during one of the wettest periods of the Dust Bowl Era.

Of the 113 tornado reports in Minnesota in 2010 (an all-time record number), two occurred on May 24th. A tornado touched down in Marshall County just before 3:00 pm and carved a 4-mile path through the rural countryside without inflicting any damage. Then just before 4:00 pm a second tornado touched down briefly near Halstad in Norman County, again not causing any serious damage. These were the first two tornadoes in the state during the one year that Minnesota reported the most tornadoes in the nation.

Outlook

A mostly cloudy and unsettled Memorial Weekend with temperatures a bit cooler than normal and daily chances for showers and thunderstorms. Showery conditions will prevail well into next week, adding to already high rainfall totals for the month. Temperatures will warm closer to normal by Wednesday and Thursday.

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