User:WxGopher/Sandbox

From Wikipedia, the free encyclopedia

The Climte of the Twin Cities is describes the weather events and trends of the Minneapolis - St. Paul metropolitan area in east central Minnesota. Minneapolis and St. Paul, together known as the Twin Cities form the core of the 16th largest metropolitan area in the United States. Due to its location in the northern and central portion of the U.S., the Twin Cities has the coldest average temperature of any major metropolitan areas in the nation. Winters can bitterly cold, summer is warm to hot and frequently humid, snowfall is common in the winter and severe thunderstorms with heavy rainfall occur during the spring, summer and autumn.

Contents 1 General Climatology 1.1 Temperature 1.2 Urban heat island effect 1.3 Preciptiation 2 Weather events 2.1 Tornadoes 2.2 Derechos 2.3 Blizzards 2.4 Flash flood 2.5 River flooding

[edit] General Climatology

On the Koppen climate classification scale, the Twin Cities is located in the humid continental climate ( Dfa) zone. The continental climate refers to the large amounts of land mass and abscence of large body of water that surrounds the region. The humid portions derives from the humid air masses that routinely flow northwards towards the region from the gulf of mexico. A feature of the humid continental climate in the United States is that weather can be unpredictable with extremes occuring in many phases of measurements. For example, the Twin Cites has a hotter all time record high temperature (108 F) than the entire state of Florida, despite being located nearly 1000 miles further from the equator. Conversely, temperature during the winter months are colder in the Twin Cities than in any other major metropolitan area in the United States. The Twin Cities can also experience droughts, floods and on average is windier than The Windy City, Chicago, Illinois.

[edit] Temperature

Temperatures in the Twin Cities region range from an average of __ in January to __ in July. Because of its location in the central and northern portions of the United States and with no natural barrier to block the cold air, the Twin Cities is subjected to many arctic air masses throughout the winter months. These arctic air masses bring with them very cold temperatures and sometimes strong wind, resulting in dangerous wind chill values. It's these arctic outbreaks that push the Twin Cities to the top of the list when looking at the coldest Metropolitan areas in the United States. For example, the Twin Cities' average January of temperature of 13.1 is well below Chicago's 22.0, despite the two metro areas being located only about 350 miles apart. Conversely, the Twin Cities average temperature in July is 73.2, just .1 of a degree F cooler than Chicago's. Similar trends can be noted for other metropolitan areas in regions such as Milwaukee, Wisconsin and St. Louis, Missouri.

[edit] Urban heat island effect

A significant impact on temperatures in the Twin Cities the past 50 years has been the urban heat island effect. The large amounts of concrete & asphalt coupled with numerous tall buildings (which block wind) helps to trap heat close to the surface, resulting in warmer temperates than that of the surrounding areas (even those to the south).

[edit] Preciptiation

The Twin Cities experiences a wide range of precipitation. Rain is most common during the summer months, while snow, sleet, freezing rain and rain occur during the winter.

[edit] Weather events

[edit] Tornadoes

• The first recorded tornado observed in the Twin cities metro area was at Fort Snelling in 1820.

• A destructive tornado struck St. Paul in 1891. It is the first tornado known to be photographed in Minnesota.

• The worst tornado event to affect the Twin Cities was on May 6, 1965. On that day, six tornadoes touched down in several counties in the western and northern Metro area, killing 13 people and injuring several more. Four of the tornadoes were rated F4, two of which hit Fridley, Minnesota about an hour apart. This outbreak was notable because this was the first time in Minnesota history that civil defense sirens were used to warm people of impending severe weather. The live coverage by the Twin Cities medial was also unprecidented. WCCO's continual broadcast of the weather situation is credited with warning people about the tornadoes and saving lives. This outbreak was the costiest weather disaster in the entire history of Minnesota.

• In 1981 a twister dubbed the Har-Mar tornad touched down in Minneapolis, proceeding to affecting the northern suburbs of the metro area. It killed a man near Lake Nokomis, and is the last time someone in Minneapolis or St. Paul died from a tornado.

• The last tornado to cause a fatality in the Twin Cities Metro area was on September 21, 2006 when an F2 torando hit Rogers and killed a 10 year old girl.

[edit] Derechos

Though drechos do not have as strong of winds as tornadoes, they impact larger areas and thus can easily cause just as much damage. The costiliest severe weather event in the Twin ctiies history was a derecho that occurred on May 15, 1998. Large Hail and damaging wind caused most of the $1 billion in damages that were reported.

[edit] Blizzards

• On November 11, 1940 the Armistice Day blizzard affected all of southeast Minnesota, killing 60 people in Minnesota. The Twin Cities recorded 17 inches of snow, and temperatures dropped.

• The largest snowstorm to affect most of the Twin Cities area was the Halloween Blizzard on OCtober 31 - November 2, 1991. Officially, 28.4 inches of snow was reported at the Twin Cities airport. The heaviest was in aline from there, northwards towards Duluth. Lesser amounts fell to the east and west of that line, but it was the largest early-season snowstorm for the enitre region.

[edit] Flash flood

• The largest flash flood in Twin Cities history occurred on July 24, 1987. Dubbed The Super Storm, more quantitave rain fell from this event than any other in recorded Twin Cities history.

• A smaller, yet equally intense flood occured in western Dakota County on July 7, 2000. A foot of rain fell in about 4 hours in Eagan and Apple valley, causing substantial damage and killing one person.

[edit] River flooding

The Minnesota River and Mississippi River both flow through the Twin Cities, and in turn there is some degree of River flooding almost annually. The wost floods in Twin Cities history on these rivers were in 1965. Other substantial floods occurred in 1969, 1993, 1997 and 2001.