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News and Information

Minnesota WeatherTalk Newsletter for Friday, February 5, 2010

To: MPR Morning Edition Crew
From: Mark Seeley, University of Minnesota Extension
Dept of Soil, Water, and Climate

Subject: Minnesota WeatherTalk Newsletter for Friday, February 5, 2010

Headlines:

-February starts with snow in the south
-Recent trends in freezing rain and freezing drizzle
-Weekly Weather Potpourri
-MPR listener question
-Almanac for February 5th
-Past weather features
-Weeping wings
-Outlook


Topic: February starts with snow for some

Many southern areas of the state were hit by a storm that moved across the state over February 1st and 2nd. Snowfall amounts mostly ranged from 2 to 3 inches, though both Red Wing and Hastings reported over 4.5 inches. The new snow on top of somewhat icy sidewalks and streets produced more than a few accidents. Some northern locations were missed by the snow, but remained very much on the cold side. Embarrass reported the coldest temperature in the 48 contiguous states on February 1st with -26 degrees F, while International Falls had the coldest temperature on February 3rd with -22 degrees F.

Additional snow developed on Thursday night into Friday, delivering another 1-2 inches across much of the state, and ushering in a snowy period that is expected to last until February 10th. After that, the NOAA Climate Prediction Center models show a drier than normal pattern across Minnesota during the middle part of the month.

Topic: Recent trends in freezing rain and freezing drizzle

A recent listener question actually prompted me to do an analysis of these data. Historically, during the months of January and February the Twin Cities Metro Area and southern Minnesota communities record freezing rain or freezing drizzle about one day every other year, or in some cases close to one day per year. However, since 1990 the frequency of occurrence for these frozen precipitation types seems to be increasing for January and February. For example, January and February of 1993, 1998, and 2006 brought 7 days with freezing rain or freezing drizzle to the Twin Cities. In 1999 there were 6 such days, while 2003 and 2005 brought 5 days with freezing rain or freezing drizzle. Further, so far in 2010, we have recorded 4 days with such weather in the Twin Cities area (including Thursday of this week). Of the past 20 years, only 1990, 2001, and 2002 brought no recorded January or February freezing rain or freezing drizzle type weather to the Twin Cities Metro Area. In fact the average frequency of such events since 2003 has been 4 days each year, or quadruple the historical frequency of occurrence.

This observation may be nothing more than random variation. On the other hand, it fits rather well with climatological evidence to suggest winters are getting warmer, dew points are getting higher, and the hydrologic result is a change in winter precipitation types. A higher frequency of freezing rain or freezing drizzle types of precipitation during Minnesota winters is not generally welcome because of the many problems it creates, most notably more traffic and pedestrian accidents.

Weekly Weather Potpourri:

In light of recent public comments about the various sources of temperature data used to assess climate change, Dr. Peter Stott from the United Kingdom Meteorological Office explains the three independent primary temperature data sets that are used to calculate year by year global temperature trends. In essence, though these data sets are independently derived from measurements, they depict very similar temperature trends for the Earth climate system. You can read more about this at...

http://www.metoffice.com/climatechange/science/explained/explained5.html

Tropical Cyclone Oli in the South Pacific Ocean was churning up the seas near Bora Bora and Tahiti with winds of over 150 mph on Wednesday and Thursday this week. These winds were producing wave heights of 20-25 feet. The storm was expected to travel poleward past 20 degrees south latitude and weaken substantially over the weekend.

The U.K. Met Office and the BBC report this week that Scotland has recorded its coldest December-January period since 1914 when detailed record keeping began. Scottish weather stations recorded a high frequency of overnight lows that were below 25 degrees F, and one reading was as cold as -8 degrees F. It was reported to be the coldest December-January period in Northern Ireland since 1962-1963 as well.

A strong winter storm was pounding the mid-Atlantic states on Friday (Feb 5) with a mixture of precipitation and high winds. Blizzard or near-blizzard conditions were expected to develop in parts of MD, DE, and NJ, along with the Washington, D.C. area. Snowfall forecasts ranged from 8-12 inches for Philadelphia to 16-24 inches for Washington, D.C. and parts of Virginia and Maryland.

MPR Listener Question: I know I am probably just dreaming of spring, but how many Minnesota communities have seen 70 degrees F in the month of February? Has the Twin Cities every made it?

Answer: Only three Minnesota climate stations have ever recorded 70 degrees F during the month of February. Pleasant Mound in Blue Earth County and Le Sueur reported 73 degrees F and 70 degrees F, respectively on February 26, 1896. Lake Wilson in Murray County reported 70 degrees F on February 23, 2000. That's it. The highest February temperature reported in the Twin Cities is 64 degrees F on February 26, 1896.

Almanac for February 5th:

The average MSP high temperature for this date is 23 degrees F (plus or minus 13 degrees standard deviation), while the average low is 6 degrees F (plus or minus 14 degrees standard deviation).

MSP Local Records for February 5th:

MSP weather records for this date include: highest daily maximum temperature of 51 degrees F in 2005; lowest daily maximum temperature of -11 degrees F in 1895 and 1936; lowest daily minimum temperature of -27 degrees F in 1979; highest daily minimum temperature of 33 degrees F in 2005; record precipitation of 0.52 inches in 1908 and record snowfall of 7.5 inches in the same storm of 1908. Maximum snow depth has been 22 inches in 1967.

Average dew point for February 5th is 6 degrees F, with a maximum of 42 degrees F in 1946 and a minimum of -36 degrees F in 1979.

All-time state records for February 5th:

Scanning the state climatic data base: the all-time high for this date is 61 degrees F at Madison (Lac Qui Parle County) and Beardsley (Big Stone County) in 1963; the all-time low is -54 degrees F at Pokegama Dam (Itasca County) and Leech Lake Dam (Cass County) in 1895. The all-time record precipitation amount for this date is 2.35 inches at Lynd (Lyon County) in 1915. The all-time record snowfall is 24.0 inches also at Lynd (Lyon County) in 1915.

Past Weather Features:

Over February 5-7, 1857 a mid-winter warm up ushered in back to back snow storms. Ft Snelling received 11 inches of new snow on top of an already deep snow cover. Further north over a foot of snow arrived, pushing the snow depth to 3 feet or greater. An arctic air mass descended across the state following the passage of the cold front and temperatures fell to -35 degrees F at Ft Snelling and -56 degrees F near Fort Ripley.

On February 5, 1963 a welcome but short duration warm spell occurred across the state. Over 20 communities reported a daytime high of 50 degrees F or greater, many in the western portions of the state. Two days later daytime temperatures were back in the 20s F, but the warm up did melt the snow cover in many parts of the Minnesota landscape.

About 2:00 pm on the afternoon of February 4, 1984 a blizzard started in NW Minnesota and spread south through the Red River Valley and into the Minnesota River Valley. Though snowfall amounts were relatively light, the storm packed powerful winds that caused "white-out" conditions on many roads and highways. The relatively sudden onset of the storm caught many Minnesota citizens off guard. Winds of 50 mph were common and some gusts as high as 80 mph were recorded. Many motorists were stranded overnight from February 4th to the 5th. At least 16 deaths were blamed on the storm.

On Groundhog Day, (Feb 2) in 1996 Tower, MN reported the all-time state record low of -60 degrees F. Less than a week later, on February 8, 1996 they reported a high of 48 degrees F, a warm-up of 108 degrees F and their highest reading for that month.

Words of the Week: Weeping wing

These words refer to an ice protection system used on aircraft. Most typically a glycol-based chemical is released through small meshed orifices on the leading edge of the wings. The fluid flows along the airstream passing across the top and bottom of the wing and leaves a thin coat of fluid that protects against surface ice formation. This system provides both anti-icing and deicing protection for aircraft. It can also be used on windshields and propeller blades.

Outlook:

Near seasonal average temperature over the weekend with chances for snow. Snow off and on early next week, then drier and cooler by Wednesday and Thursday.

Further Information:

For older versions of the "Minnesota WeatherTalk" newsletter go to

http://www.climate.umn.edu/weathertalk/

For access to other information resources go to

http://www.climate.umn.edu/Seeley/

NOTE: News releases were current as of the date of issue. If you have a question on older releases, use the news release search (upper left-hand column of the News main page) or the main Extension search (upper right of this page) to locate more recent information.

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