To: WeatherTalk for MPR's Morning Edition From: Mark Seeley Re: Topics for MPR's Morning Edition, Friday, May 27, 2005 Headlines: - Record rainfalls this week - Preliminary May Climate Summary - Construction Weather - Caught in a rut - Almanac for May 27th - Words to describe this May - Outlook Topic: Record rainfalls on May 25th.... A slow moving low pressure system passed across the state on May 25th bringing prolonged periods of rain across central counties. Many communites reported new record rainfall amounts for the date, including... International Falls 2.21" Cook 1.86" Tower 1.60" Little Fork 2.64" Marcell 1.87" Isle 1.29" Grand Rapids 2.42" Itasca State Park 1.95" Wadena 1.57" Leech Lake 2.16" Blackduck 2.30" Babbitt 2.17" This time of year, record rainfall amounts tend to fall from shortlived thunderstorms. However, this rainfall had very little lightning and thunder, but great persistence. Some areas reported rain for up to 19 consecutive hours. Topic: Preliminary Climate Summary for May Talk about a cloudy, rainy month....good riddance as we say goodbye to the month of May next week. According to solar radiation measurements at the University of Minnesota St Paul Campus, the amount of solar energy this May will be the lowest measured for the month since records began in 1960. At the University Research and Outreach Center in Waseca, the solar radiation for May is likewise very low, nearly 23 percent below average. In addition, the long term average percent possible sunshine during May in the Twin Cities area is 61 percent..that is 61 percent of the daylight hours are typically sunny. However, according to the National Weather Service in Chanhassen, so far this month the average is only 34 percent, indicating why May of 2005 will go down as one of the gloomiest in recent memory (see jargon section below). Overall, the month has been wetter and cooler than normal. Average monthly temperature departures from around the state range from 1 to 4 degrees F cooler than normal, marking the 4th consecutive cool May across Minnesota. Temperature extremes for the month ranged from just 8 degrees F at Embarrass on the 3rd to a high of 85 degrees F at Browns Valley on the 22nd. Minnesota reported the lowest temperature in the 48 contiguous states on three dates during the month: 8 F and 12 F at Embarrass on the 3rd and 4th, respectively, and 25 F at Bigfork on the 16th. Many record cold temperatures occurred on May 2nd as snowfall was observed across the state. Bruno in Pine County reported 0.8 inches of snow, while Spring Valley in the southeast reported 0.4 inches, and Grand Rapids 0.3 inches. Most places reported either no measurable snow or a trace. Soil temperatures for the month have averaged from 3 to 5 degrees F cooler than normal and resulted in slow germination and emergence of crops. Most communities have reported rainfall on nearly half the days of the month, an above normal frequency. Resulting total amounts for the month are above normal by 1 to 2 inches. Several communities have reported totals that range between 5 and 7 inches, amounts that have saturated soils. This is the third consecutive May with above normal rainfall statewide. It was a windy month as well. Overall average wind speeds were higher than normal and maximum gusts on both the 21st and 22nd of the month exceeded 40 mph in several areas. Topic: Weather and the Construction Industry We are in the midst of the peak construction season for Minnesota. Weather and climate information are used a great deal by the construction industry. Climatic data are used to estimate probable working days for construction projects, including likelihood of rainfall disruptions. Downtime or lost working days due to weather are often the basis for amending contracts, particularly time schedules for the completion of various construction phases. Many specific activities are weather sensitive: pouring and curing of concrete, roofing (shingles or tiles), brickwork, paving, excavating, painting, and of course re-landscaping denuded work sites. In addition to rainfall climatology and precipitation forecasting, wind forecasting can be very important, particularly to sites where tall structures are being erected and they are storing or moving around materials like sheeting, shingles, duct work, insulation, tiles, sheet rock and other things which can be caught up by the wind. In Minnesota, like most other states, private meteorologists often provide construction companies with custom forecasts for specific sites and projects. These generally prove to be a valuable investment, especially for long projects which require several months to complete. MPR listener question: Is it just me, or are we caught in a rut of wet, cool Mays over the past several years? Answer: Indeed, the data support your conclusion. Seven of the past eight Mays both in the Twin Cities and statewide have been wetter than normal, while four of the past five have been cooler than normal. On a positive note, this type of weather has certainly been good for starting new grass seed. Twin Cities Almanac for May 27th: 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 52 degrees F (plus or minus 8 degrees F standard deviation). MSP Local Records for May 27th: MSP weather records for this date include: highest daily maximum temperature of 95 degrees F in 1969; lowest daily maximum temperature of 44 degrees F in 1965; lowest daily minimum temperature of 34 degrees F in 1907; highest daily minimum temperature of 70 degrees F in 1969; record precipitation of 2.17 inches in 1978; and a trace of snowfall on this date in 1965. Average dew point for May 27th is 48 degrees F, with a maximum of 69 degrees F in 1969 and a minimum of 25 degrees F in 1917. All-time state records for May 27th Scanning the state climatic data base: the all-time high for this date is 104 degrees F at Hallock (Kittson County) in 1934. The all-time low for this date is 19 degrees F at Blackduck in 1907, at Roseau in 1917, and at Alborn in 1947. The heaviest snowfall statewide on this date occurred in 1932 at Virginia (St Louis County) where they recorded 5.0 inches. The all-time state record for precipitation on this date (expressed as liquid equivalent) is 3.90 inches at Mahnomen in 1963 Words of the Week: gloomy, dreary, glum, dull, or dingy These are all words that have been used to describe my personality at times, but aside from that they are all terms used by forecasters to refer to persistent cloudy periods, particularly during the seasons when more sun is expected. Thick vertical clouds or very low stratoform clouds casts a gray tinge over everything, and some would argue dull the senses and even bring on depression. We are more tolerant of this when it occurs in February, March, or November, than when it occurs in the month of May. Outlook: Cooler than normal over the weekend most places, with scattered showers. This pattern will linger into Memorial Day on Monday as well. Sunday has historically seen the most cloudiness over the Memorial weekend and it looks like that historical pattern will prevail again. A warming trend will begin on Tuesday, bringing temperatures back up to normal levels for this time of year. A chance for thunderstorms by Thursday, with closer to normal daytime high temperatures to usher in the month of June.