More or Fewer Tornadoes?

The round of violent tornadoes early this week across the South raises the following question. Is our changing climate affecting tornadoes? The two major forces which create favorable environments for tornadoes are atmospheric instability and wind shear. Global climate change models have always indicated that a warming atmosphere will have more instability but less wind shear, suggesting the two would balance each other out. But global climate models are generalized models and have only suggested how these two elements would change in general. New research suggests that wind shear will decrease overall but conditions of high wind shear may increase particularly on the days of high instability. In other words, we might have fewer tornado days but an increase in the number of occasions with a high concentration of tornadoes. This is actually borne out in recent years as records have been set for the most and also the fewest number of tornadoes in a year. Meteorologist John Wheeler

The Last Blog Post

Today is my last day at WDAY/WDAZ, so the following is my last blog post….

 

One of my favorite quotes is from Stephen Hawking. “Remember to look up at the stars and not down at your feet. Try to make sense of what you see and wonder about what makes the universe exist. Be curious. And however difficult life may seem, there is always something you can do and succeed at.  It matters that you don’t just give up.”

Not to downplay the rest of the quote, but my favorite part is  “to look up”.  In our modern society we tend to look down at our phones more than the sky.  With many of us living in urban areas, buildings and trees often block our view of the sky, plus at night, lights severely limit the number of stars we can see.  This region offers a full suite of weather, plus, outside of city limits, a spectacular view of the heavens.

My hope is that we all find time in our busy schedules to at least occasionally look up and enjoy the view as the sky rarely disappoints.

Winter 2013-2014 Statistics

The National Climatic Data Center (NCDC) released their analysis of the winter of 2013-2014 last week.  NCDC ranked the period from December 1 through February 28 as the 25th coldest on record for North Dakota.  You may recall locally it was the 16th coldest on record, but western North Dakota was not as cold making the average for the entire state lower in the cold rankings.

Minnesota on the other hand recorded a more evenly spread cold winter throughout that state.  Taken as a whole, NCDC ranked this past winter as the 6th coldest on record in Minnesota.   The past 119 winters are used in these rankings.  Nationally, NCDC ranked the past winter as the 34th coldest on record.

Using other datasets and analysis puts that ranking closer to the Top 10, but no matter what the ranking; most Americans east of the Rocky Mountains experienced a winter that will not soon be forgotten.

March Question of the Day

Here is a weather question to start your day.  Which first half of March, March 2013 or March 2014 was colder?  If you guessed this year, you are correct, but just by a fraction of a degree.  Last March and this one both recorded an average temperature just slightly below 18 degrees.  That is approximately 6 degrees below average.

The big difference from last year to this year was a year ago Fargo Moorhead recorded about 10 inches of snow and this month just1.8 inches of snow was recorded from March 1 through the 16.  We all remember the phenomenally warm March of 2012, but that was one of only two Marches that started with above average temperatures this century.

The other March that started mild was back in 2010, which made for an early flood that year.  This March certainly started cold, but nowhere near as extreme as 2003 when the first half of March had an average temperature of just 11 degrees.

Heat Island No Match

There were many impressive statistics from this past winter.  There are two in particular that caught my attention and these were both Chicago and the Twin Cities recording a Top 10 coldest winter on record.  Chicago recorded an average temperature of 18.8 degrees from December 1 through February 28.

That ranked as the 3rd coldest winter on record for that city with records going back to 1872.  The Twin Cities average temperature was 9.7 degrees and that ranked as the 9th coldest on record with records used to 1891.  The location of where the official temperatures and precipitation has been taken has moved through the years in both cities, but the one consistent fact through time has been the expansion of the urban heat island influence in these large metropolitan areas.  The temperature can be several degrees warmer within these cities than it is in nearby rural areas.

Yet even with that man-made heat influence these cities recorded such a cold winter.  Just imagine what the average temperature would have been in a similar winter 100 years ago.

First 50 of 2014

The average date of the first 50 degree high in Fargo Moorhead is March 18.  The high temperature this past Thursday was 58 degrees which was our first 50 (and nearly our first 60 degree) reading of the season.

One of the keys to reaching 50 degrees is snow cover.  Although within the city limits of Fargo Moorhead many areas, particularly the older parts of town there was still plenty of snow on the ground that day, outside of the metro, especially to our west there has been very little snow on the ground for the past few weeks. A west wind off that bare ground helped the temperature reach 58 degrees that afternoon.  If you are curious, the average first 60 degree high is on April 3 and the first 70 is on April 18.

Although the pattern still looks to be producing more cold days than warm ones in the short term, the lack of snow will at least keep temperatures warmer than what it would be with a whiter landscape.

The End of Negatives?

Our last below zero reading was a -1 degree temperature that occurred around 2:30 AM on March 5.  The temperature was well above zero much of that night, but the sky cleared just after midnight, the temperature briefly dropped below zero, then the clouds moved back in and the temperature rose to nearly 10 degrees before most people headed to work or school.  In other words, that below zero reading was hardly even noticed.

Yet, that -1 degree reading did push the seasonal total for days with a low below zero to an even 70 days.  Those 70 days would rank the cold season of 2013-2014 as tied for the 14th highest such total on record.  Although, another negative morning is certainly possible, historically after this point they tend to only occur with a deep snow cover, which we currently lack.

Therefore, with any luck, our next negative morning in Fargo Moorhead will be near November 28, which is the average date of our first below zero reading of our next cold season.

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.

Cold, Not Snowy

This past winter season was definitely cold, but it certainly was not snowy.  From December 1 through February 28, the official snow total from our cooperative observer in north Moorhead totaled 27.3 inches.  That is 2.1 inches below the average of 29.4 inches for that time period.  It was the second year in a row with snowfall being very close to the average during the three principal months of winter as last year 28.7 inches was recorded.

More important than the amount of snow is the water content in that snow.  The 27.3 inches of snow that fell in the past three months contained 2.09 inches of liquid, right at the average of 2.14 inches.  Meaning, this past winter was about as average as average gets for winter precipitation.  The driest of the three winter months was February as only 1.5 inches was measured last month, the 8th lowest total on record for that month.

That snow contained only 0.11 inches of liquid making February 2014 the 7th driest since records began in 1881.

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.