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Extension > Mark Seeley's WeatherTalk > Beneficial rainfall for some

Friday, August 17, 2012

Beneficial rainfall for some

Beneficial rainfall for some

The first half of August brought some significant rainfall to many areas of the state, and in somewhat heavy doses in places. Thunderstorms brought 1.56 inches to International Falls and 1.40 inches to Red Wing Dam on August 15th. Some areas south of the Twin Cities (New Prague, Farmington, Rosemount) also received over 1 inch from fast moving thunderstorms on the 15th. In addition some hail over 1 inch in diameter fell over western counties on the 15th.

Many observers have reported over 2 inches for the month so far, while some locations (Preston, Lanesboro, Caledonia, Grand Portage) have received over 3 inches, as much as 3.59 inches at Grand Portage and 3.57 inches at Caldonia. The rainfall so far this month has kept the Minnesota drought stricken area from expanding in size this month.

Temperatures are averaging from 1 to 3 degrees F cooler than normal so far this month. For six consecutive days over August 9-14 daily temperatures were cooler than normal, a stretch of cooler than normal weather not seen since June 22-28, 2011 (15 months ago). Many observers have already reported overnight lows in the 30s F this month. Meanwhile at the Amundsen-Scott Station at the South Pole (Antarctica) it was -77 degrees F this week.

Despite cooler than normal temperatures, crops are rapidly maturing well ahead of the normal calendar pace. Corn will be ready for early harvest, while sugar beets are already being lifted in some places.

Record cold in places

August 16th brought a record-tying low temperature to International Falls with a reading of 41 degrees F (tied 1958). But more significantly a strong Canadian high pressure ridge brought the coldest August 17th (Fri) since 1963 to many parts of the state. New record low temperatures were set at: Silver Bay (34 F); Hibbing (34 F); Crane Lake (36 F); Princeton (37 F); Austin (38 F); and Waseca (39 F). In addition many observers reported tying their record cold low temperatures on August 17th including, 36 degrees F at Fosston (tied 2007), 37 degrees F at Little Falls (tied 1999); 37 degrees F at Hallock (tied 1904); and 39 degrees F at Park Rapids (tied 1896). For many these were the coldest readings since May 16th last spring.

New Seasonal Climate Outlooks

The NOAA Climate Prediction Center issued new seasonal climate outlooks on Thursday (August 16th) covering the period from September to November. September is expected to be warmer than normal for much of the nation's midsection, following a trend of recent years. Over September to November Minnesota is expected to see above normal temperatures prevail, a pattern associated with a developing El Nino episode. The CPC sees equal chances for above or below normal precipitation across Minnesota during this period.

NOAA also released a new Drought Outlook this week, covering the period through November 30th. The outlook calls for drought improvement in Minnesota, northeastern Iowa, southern Wisconsin, and northern Illinois. Unfortunately the outlook favors drought persistence in southwestern Iowa, Nebraska, Missouri, and southern Illinois.

Weekly Weather potpourri

Typhoon Kai-Tak located southeast of Hong Kong was being monitored carefully this week. It packed winds up to 90 mph, producing sea waves of 25 feet. Kai-Tak is expected to bring heavy rains to areas between Hong Kong and Hanoi this weekend.

Tropical Storm Gordon formed in the North Atlantic on August 16th east of Bermuda. It is expected to strengthen slightly and perhaps become a hurricane over the weekend as it head toward the Azores. Gordon is the 7th named storm of the North Atlantic Tropical Storm season. The National Hurricane Center was also monitoring a depression in the southern Gulf of Mexico which may become a tropical storm over the weekend.

A recent study published in the journal Geology documents a 7000 year history of climate in the Nile Delta of Egypt. Based on interpretations of pollen and charcoal records from river sediments researchers have found evidence for mega-droughts in the region at 5000 years ago, 4200 years ago, and 3000 years ago. The mega-drought 4200 years ago was associated with the collapse Egypt's Old Kingdom. You can read more about this study here.

On Thursday (Aug 16) parts of Siberia reported strong thunderstorms with heavy rain and large hail, some the size of hen's eggs. Hundreds of cars were damaged by the hailstones. Following the passage of the thunderstorm the temperature dropped from 90 degrees F to just 61 degrees F.

MPR listener question

Here in the Twin Cities we recorded daytime highs of 92 F and 90 F on August 1st and 2nd, but since then we have not seen 90 degrees F. How often does August produce no 90 F days in the Twin Cities climate record, and do you think we'll see another 90 F this month?

Answer: According to the Twin Cities climate record about 1 year in 9 August brings no days with temperatures of 90s degrees F or greater. In fact just last year was such an August. Given the present forecast for the balance of the month I see a very low probability for another 90 F day in the Twin Cities. However, bear in mind that about 40 percent of the time September brings at least one 90 F day to the Twin Cities.

Twin Cities Almanac for August 17th

The average MSP high temperature for this date is 82 degrees F (plus or minus 8 degrees F standard deviation), while the average low is 61 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for August 17th

MSP weather records for this date include: highest daily maximum temperature of 100 degrees F in 1947; lowest daily maximum temperature of 63 degrees F in 1997; lowest daily minimum temperature of 42 F in 1962; highest daily minimum temperature of 73 F in 1922, 1934, and 1972; and record precipitation of 1.62 inches in 1905.
 
Average dew point for August 17th is 59 degrees F, with a maximum of 80 degrees F in 2002 and a minimum of 42 degrees F in 1947.

All-time state records for August 17th

The state record high temperature for this date is 105 degrees F at Campbell (Wilkin County) in 1988. The state record low temperature for this date is 29 degrees F at Tower (St Louis County) in 1981. State record precipitation for this date is 5.00 inches at Le Center (Le Sueur County) in 1948; and no snowfall has been reported on this date.

Past Weather Features:

August 17, 1963 brought cold temperatures to parts of northern Minnesota. Frost was reported at Cook, Virginia and Bigfork. Temperatures rebounded to the mid-80s F by the 20th.

Another cold August 17 in 1981 when several northern communities reported frost. Cotton, Hoyt Lakes, Virginia, Meadowlands, Hibbing, and Tower reported frost on that date.

The hottest August 17th in history was probably 1988 when over 20 Minnesota communities reported afternoon temperatures of 100 degrees F or greater. Actually the August heat wave lasted from the 15th to the 17th, finally breaking with the passage of a cold front on the 18th which dropped daytime highs by 25 degrees F.

Outlook

Cooler than normal weekend under mostly sunny skies. Warming trend begins on Tuesday and will push temperatures back close to normal with another chance for showers and thunderstorms by Wednesday and Thursday.

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