What Is Average?

Halfway through April and it is looking like another colder than average month.  December, January, February, and March have all been significantly colder than average.  April will likely make five months in a row.  Last October and November were also colder than average but only by an insignificant fraction of a degree. September was warmer than average but the summer months last year were only slightly warmer than average.  Average is only the average of the past.  There is no rule that weather has to conform to averages either by remaining near average or by swinging equally one way and then the other.  In this sense, our weather is non-linear, which means it does not converge to an average over time.  We present weather averages only as a way to roughly compare.  For most weather records, what we call, “average” is only the average of the past three full decades.  So what constitutes average weather actually changes over time as our climate goes through changes.      Meteorologist John Wheeler

Ancient Weather Record?

Two scholars at the University of Chicago’s Oriental Institute have translated an ancient Egyptian inscription on a six-foot stone block which seems to be a 3.500 year old weather report. The writing on the block refers to rain, darkness and “the sky being in storm without cessation, louder than the cries of the masses.”  This is now believed to be the oldest weather report ever found. It is possible that this terrible weather may be a result of the Minoan eruption of Thela in the Mediterranean Sea, on the island now known as Santorini.  The Thela eruption is thought to be one of the strongest and most devastating volcanic eruptions of the past several thousand years.  Climate scientists have found evidence of sudden and severe climate change throughout the Northern Hemisphere, including tree ring data in Greenland, bristlecone pines in California, and reports of crop failures in China.  Such massive volcanic eruptions can change climate by ejecting huge amounts of sulphur dioxide into the upper atmosphere where it blocks sunlight for years. Meteorologist John Wheeler

Record Record

An email arrived in the weather center asking what day of the year has the largest temperature range from the record low to the record high.   The recorded low on January 8, 1887 was -48 degrees.  Thirteen years later, on January 8, 1900, the recorded high temperature reached 50 degrees.

That difference of 98 degrees still stands as the greatest range between a record high and low for any date in Fargo Moorhead.   In second place is March 18.  On March 18, 2012 the high reached 78 degrees with the record low for that date being -19 degrees observed in both 1883 and in 1923 for a difference of 97 degrees from record high to record low.   A snow free March as we learned in 2012 can be very mild, a snow covered March like last year and so far this year, can be bitterly cold.

Those snow variations in combination with a higher sun angle this time of year make March the month with most of the extreme record differences observed in this area.

March Cold Record

By now many of you may have heard that both Fargo Moorhead and Grand Forks set a record on Saturday, March 1 for the coldest high temperature not only for that date, but also for the month of March.  The high in Grand Forks (UND/National Weather Service site) was -9 degrees and in Fargo Moorhead the high reached -8 degrees.

Of note, the high of -8 degrees in Fargo occurred just after midnight with the afternoon high reaching only -10 degrees.  Both of those highs shattered the daily record for lowest maximum for March 1 and narrowly set new monthly records.  The previous coldest March high was -7 in Fargo Moorhead set back on March 10, 1948 and in Grand Forks the previous record was -8 set on March 6, 1955.

Other cities in the region that set new March records for lowest maximum over the weekend included Sioux City and Waterloo, IA, Omaha and Lincoln, NE, and Eau Claire, WI, plus many others around the country.

December Starts Cold II

Yesterday in this space, I mentioned that no record lows have been set in the month of December since 1983.  There are two principal reasons for this.  The first is thermometer changes.  Many of the records in our cold season were set in the 1880s before what is now the National Weather Service set up standards for how all temperatures should be recorded back in 1891.

For example, the low temperature has not hit -40 degrees or lower since 1891 in Fargo Moorhead.  Another more significant reason why low temperatures records are more difficult to set is land use changes.  As Fargo Moorhead continues to grow, our heat island, the increase in air temperature caused by man-made objects replacing the natural landscape has become more significant.

Plus, the coldest temperatures are on clear, calm nights and with the official sensor very near the airport runway, dead calm air is difficult to achieve with the increase of flights at Hector Int’l keeping the air mixed up near the official sensor.

Big Jump

The low temperature on Sunday was 24 degrees at Hector Int’l.  On Monday, the sensor at the airport recorded a maximum temperature of 93 degrees.  That is a difference of 69 degrees in approximately 36 hours. That is tied for the 5th highest difference over a two day period since records started in 1881.

The record occurred in May, 1926.  On May 3, 1926 the low was 18 degrees.  The following day on May 4, the high temperature was 93 degrees for a difference of 75 degrees over the two days.  Other notable two day differences occurred on January 6/7, 1924 from -35 degrees to +36 degrees and from April 14/15, 1926 as the temperature changed from a low of 14 degrees to a high of 85 degrees, both 71 degree differences. 

It should be noted that modern electronic thermometers detect sudden rises and falls of temperature more efficiently then the old mercury or alcohol thermometers used in the past; yet, the difference from Sunday morning to Monday afternoon was striking.

Cloud Savers

The coldest temperature so far this season, through yesterday, was a 25 degree reading back on September 23.  If not for cloud cover on other mornings, we likely would have been much colder.  That has been particularly true in recent days.

This past Sunday morning for example, the low in Fargo was 30 degrees.  Much of the night was cloudy and that kept the cooling near the surface to a minimum, but where the sky cleared the temperature plummeted.  Aberdeen where it was clear, the temperatures fell to 14 degrees that morning.  Temperatures in the teens were found as far south as Iowa, with Sioux City recording 15 degrees and Spencer, 13 degrees.  All of those temperatures were records for the date.

Perhaps the most impressive low on Sunday morning was the 32 degree low in Tulsa, Oklahoma, as that was the earliest known freeze for that location.  Oklahoma City also recorded their earliest freeze on record the following day.  So although it has certainly been cold lately, thanks to cloud cover, no records have been broken.

A New Old World Record

Nearly 100 years ago, on July 10, 1913, a temperature reading of 134 degrees was recorded at the Greenland Ranch in Death Valley, California.  At the time that was the highest temperatures recorded with proper measuring techniques anywhere on earth.

Nearly a decade later on September 13, 1911 a report of a temperature of 136 degrees was allegedly taken at El Azizia, Libya to establish a new world record that still holds to this day.  That is until now.  The World Meteorological Organization recently decided to drop that particular reading from the record book.  There is always been some suspicion to that reading in Libya in 1922 and after much research it was determined that indeed that temperature was likely bogus.

Therefore, that temperature set nearly a century ago in Death Valley is now considered the warmest temperature recorded in the world.  So if you have ever had the chance to go to Death Valley, you can now officially tell your friends that you visited the hottest place on earth.

A Sticky Problem

On July 19, 2011, the sensor at the Moorhead Municipal airport was reporting a dew point of 88 degrees.  Many of us in the weather community did not give much credence to the reading as that sensor gives calculated dew point temperatures three to five degrees higher than Hector Int’l no matter the time of year (and it still does, no matter what the vegetation type if any, time of day, month or season).

That day out of curiosity, I drove to the Moorhead airport, took a reading using an old fashioned sling psychrometer, which was used for years to measure relative humidity and dew point based on the cooling of a thermometer by evaporative cooling.  I came up with an 83 degree reading on two tests, which was what the Fargo airport was reporting.  Yet, in the end that 88 degree reading, which surprised many of us, was used as a new state record for Minnesota.

I put that record in this context; although Roger Maris’ record of 61 homers in a season has technically been broken, it was done so by questionable means.  I think Roger Maris holds the true record and a humidity sensor that reads high consistently, in all seasons, perhaps should have as asterisk next to its record

March and April Record

This past March, you will likely recall, was the warmest on record.   The previous warmest March was set back in 1910.  April 1910 was also a mild month and currently ranks as the 26th warmest April on record.  The combination of an extraordinarily warm March, followed by a mild April made the period from March 1 through April 30, 1910 the warmest such period on record.

That is, until this year.  With the record breaking March and an April that finished several degrees above average, the past two months finished 1.1 degrees warmer than the same period in 1910 to set a new record.  With a record breaking March, a record breaking March and April combination, could we in turn end up with the warmest spring on record this year?  The record warmest spring occurred in 1977 with an average temperature of 49.3 degrees.

To best that record, this month would have to average 57.9 degrees, which would only be 0.8 degrees above average, meaning we do have a realistic shot of breaking the spring temperature record this year.