How unusually warm has the March weather been?

Posted on March 26, 2012 by Weather Guys Editor

What an amazing warm spell! March 14 was the first day of five consecutive days in which record-high temperatures were set in Madison. This matches the longest consecutive-day streak for setting record highs in our city’s history (the other two times were in the 1950s).

Had it not been for the thundershower we received on the morning of March 19, we would certainly have set the all-time record on that day as well. We then went on to shatter the record on March 20 (81 degrees when the record had been 77), followed by another record-setter on March 21 (83 degrees for the warmest March day ever in Madison). All told, seven of eight days on which an all-time record high temperature was set — and it could have been eight straight days

During this streak, Madison also doubled the number of times the temperature has reached 80 degrees or higher in March. Before March 2012, this had happened only five times, never earlier than the 29th of the month. March 2012 has seen five such days all by itself (all in one week!)

This month has also seen the warmest average daily temperature for a March day of all-time (70 degrees on March 17, a figure that comes from the average of the daily high temperature, which was 80 degrees, and the low, which was 60 degrees).

There are those who remain unconvinced of the fact that changes in the atmospheric composition have had a discernible effect on the behavior of the atmosphere and climate systems. Some of these skeptics are major party candidates for the presidency. In the face of this recent, absolutely unprecedented, prolonged extreme weather event it is hard to consider this a reasonable position.

Were there a general suspicion among college basketball experts that the NCAA tournament officiating was not honest, even those resistant to believing this might reconsider their positions if one or two or three No. 1 seeds lost (for the first time in the history of the tournament) in the first weekend. There is a reasonable analogy here to what we have recently experienced in our weather. The room for reasonable skepticism is fast disappearing.

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How unusual is this current warm spell?

Posted on March 19, 2012 by Weather Guys Editor

Our high temperature of 78 degrees Farenheit on March 14 set the all-time record for the date and established a new record for the first 78-degree F temperature of the year, breaking the standing record of March 23, 1910 — over a century ago.

The fact that daily records have not been broken every day during this warm spell testifies to the fact that such warm mid-March days are not unprecedented in Madison’s weather history. One of the unusual aspects of this particular spell of warmth, however, is the prolonged nature of it. Based upon departures from normal (normal being the 30-year average from 1981-2010), this warm spell really began on March 10 when our present streak of days with daily temperatures at least 10 degrees above normal began. It is likely that the streak will not end at least for the next seven or more days, so it will end up being nearly two weeks long.

As warm as it has been, coming so close to 80 degrees last Wednesday made us wonder when Madison’s earliest day at 80 degrees occurred. Turns out this warm spell provided a record in that category, too.

On March 15, Dane County Regional Airport, the official reporting station for Madison, recorded a high temperature of 82 degrees Farenheit — breaking the record for all-time earliest 80-degree day by two full weeks.

Prior to last week, the record was March 29 when, in 1986, the high temperature for the day was 82 degrees Farenheit (the monthly record also recorded on March 31, 1981).

Prior to last week, only five times in the last 43 years had the temperature made it to 80 F in Madison during March (1978, 1981, 1986, 1991 and 2010). In none of those cases did the warm temperatures last nearly two weeks without interruption. Thus, we are in the midst of a truly unusual warm spell.

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How do large snowflakes form?

Posted on March 5, 2012 by Weather Guys Editor

There are four basic shapes of ice crystals: the hexagonal plate, the needle, the column and the dendrite. The dendrites are hexagonal with elongated branches, or fingers, of ice; they most closely resemble what we think of as snowflakes. The temperature at which the crystal grows determines the particular shape. A snowflake is an individual ice crystal or an aggregate of ice crystals. Large snowflakes are aggregates of ice crystals.

Aggregation is the process by which ice crystals collide and form a single larger ice particle. The probability that two crystals will stick together depends on the shape of the crystals. If two dendrites collide, it is likely that their branches will become entangled and the two crystals will stick together. When two plates collide there is a good chance that they will simply bounce off one another.

Temperature also plays a role in aggregation. If the temperature of one crystal is slightly above freezing, it may be encased in a thin film of liquid water. If this particle collides with another crystal, the thin film of water may freeze at the point of contact and bond the two particles into one. (Similar physics underlies why you should never lick a cold metal flag pole.)

Snowflakes composed of aggregates can sometimes reach 3 or 4 inches in size. The record-size snowflake occurred in January 1887 in Fort Keough, Mont., when some flakes were measured at 15 inches in diameter. That is about the size of a family-sized pizza pie.

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Does the warm winter mean a warm spring and summer?

Posted on February 27, 2012 by Weather Guys Editor

We have continued to enjoy temperatures well above normal through most of February 2012, making this year’s Dec. 1–Feb. 20 the fifth-warmest on record with an average temperature of 28.3F in Madison.  Barring an exceptionally warm last week of the month (which does not appear likely), that is where we will end up — the fifth-warmest winter (defined as December, January, February) of all time in Madison.

A natural next question is what does the winter warmth portend for the coming spring and summer.  Colleagues at the National Weather Service Forecast Office in Sullivan, Wis.,  have thought about this question.  Though speculation about such a connection is derived purely from statistics, the statistics do tell an interesting story.

First, let’s define spring as March, April and May and summer as June, July and August.  Then, ranking the past 141 years of springs and summers from warmest (rank 1) to coldest (rank 141), they have calculated the average rank for the springs and summers following the 20 warmest winters in Milwaukee (results likely very similar for Madison).

It turns out that the spring following an exceptionally warm winter, on average, has been warmer than 60 percent of all springs.  Even more intriguing, the summers following exceptionally warm winters have been warmer, on average, than 69 percent of all summers.  Those are pretty good odds for a warmer-than-normal spring and summer.

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Who first suggested human activities could change our climate?

Posted on February 20, 2012 by Weather Guys Editor

Svante Arrhenius, a Swedish scientist, is probably the first scientist to propose that burning of fossil fuels could modify our global temperatures. In 1896, Arrhenius recognized that carbon dioxide, a byproduct of burning carbon substances such as natural gas, gasoline and oil, would act like a greenhouse gas.

A greenhouse gas traps heat by allowing energy from the sun to pass through the atmosphere and heat the surface, and then the atmosphere absorbs heat emitted by the ground. Carbon dioxide, water vapor and methane gases are examples of greenhouse gases.

Greenhouse gases occur naturally in the atmosphere. If we did not have greenhouse gases, Earth’s average temperature would be about 60 degrees colder than it is now.

Too much greenhouse gases, on the other hand, could lead to a hotter planet. Venus is an example of how large concentrations of greenhouse gases — carbon dioxide in its case — can lead to a very hot planet. The large concentrations of carbon dioxide on Venus result in an average surface temperature of about 600 degrees.

Arrhenius, a chemist, postulated that adding carbon dioxide through human activities could lead to a warmer Earth. He estimated that global temperatures could rise as much as 10 degrees.

Today, climate scientists estimate that by the end of the 21st century, increased human activities could result in a global warming of 3 to 7 degrees relative to the period between 1980-1990. Land areas will warm more than oceans, and winters will likely warm more than summers.

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