No Indian Summer

I have been asked on more than one occasion in the past week if we will be experiencing any “Indian Summer” this autumn.  By definition “Indian Summer” is an extended period of above average temperatures in mid to late autumn.  Plus, most individuals only consider true “Indian Summer” to occur only after the first killing frost of the season.

If we use the second part of the definition it is highly unlikely this area will experience another extended period of warm weather before winter as such weather is unusual in this area this late in the year.  But if you only consider “Indian Summer” to be period of warm weather in autumn, then we did have a nice stretch during the first half of October.  Such weather does not occur every year and such conditions should never be expected.

Yet, when it does occur, those are the days that nearly everyone agrees are the some of the most pleasant weather we experience.

Dry Autumn

September 2012 was the driest on record in Fargo Moorhead.  Only 0.12 inches of rain was recorded that month at Hector Int’l which was 0.01 inches less than in September 1974 which was the previous driest September on record.  Those extremely dry conditions that month were not only confined to our area.

Bismarck for example, recorded only 0.05 inches of rain in September.  That, by the way, was not a record for them, as a meager 0.02 inches of rain fell on the state capital of North Dakota in September 1948.  Although precipitation was more plentiful in October and November, the past three months ended up finishing well below average locally.  In Bismarck, even with a slightly wetter November than average, the past three months ended up being the driest autumn on record for that city, with only 2.14 inches being recorded during the season.

The old record of 2.37 inches was recorded just last year meaning two straight extremely dry autumns for that area.

Autumn 2012

September, October and November comprise climatological autumn.  This past autumn the average temperature in Fargo Moorhead was 44.5 degrees, which happens to be right at our current 30 year average for the season.  November finished slightly above average, October slightly below and September right at the average giving us our very average autumn season.

One thing that was not average this past autumn was the precipitation.  During the past three months only 2.93 inches of rain and melted snow was recorded locally. That is 2.79 inches below the average of 5.72 inches.  Although the past three were quite dry, Autumn 2012 only finished as the 31st driest fall on record.

For the year, through November 30, 14.15 inches of rain and melted snow has been official recorded in Fargo Moorhead this year.  That ranks the first 11 months of the year as the 10th driest since 1881.

Time is Running Out

The record high temperature for today is 86 degrees set back in 1963.  Our daily record highs will gradually diminish the rest of the month, yet remain above 70 degrees through the first week of November. This means that although it has been quite chilly lately, there is still potential for the area to squeeze in a few more warm days before the cold air becomes permanent.

The keyword in that sentence was potential, because although our record highs give us hints to what a pattern change could bring, the reality is our average last 70 degree day is October 17, just a few days from now.  Plus, even with a recent string of warmer than average autumns, Fargo Moorhead has not recorded a high temperature of 70 degrees or higher later than October 15 since 2006.

This all means that any temperature in the 60s should now be considered mild and if by chance we hit 70 again (Tuesday?), that would be a significant bonus.

The Unique Autumn

The autumn of 2009 was one of the most unique on record.  September that year was the 2nd warmest on record.  After a very cold summer, September 2009 was a very welcomed extension of the warm season.

But that all changed on October 1 when two inches of cold rain fell behind a powerful cold front that quickly turned the area from warm to cold.  During the first two weeks of that month the temperature never exceeded 54 degrees; in fact, there were more days with highs in the 30s than the 50s during that stretch.  October 2009 finished as the 9th coldest on record.

Then on November 1, the temperature climbed well above average and stayed there for the entire month.  It was so mild that November 2009 finished as the 2nd warmest on record.  So the area experienced two almost record breaking warm months with a very cold month sandwiched in between.

It makes going from 80 degrees to snow last week seem not so strange after all.

The Last Hurrah?

In the spring, we are often looking forward to recording our first 60, 70 or 80 degree day of the year. In the autumn on the other hand, it is difficult to know when we have experienced the last such day of the year.

This past Saturday, the official high temperature was 88 degrees and based on a few conversations, many of you probably felt that was the last hurrah of the season.  The average last 80 degree day is September 29, yet, historically an 80 degree high temperature has been recorded approximately every other year during the month of October.  Plus, the last day with a record high in the 80s is on October 25.

Although we have cool off in recent days, considering how dry the top soil continues to be, plus the overall warmth we have experienced much of the year, another day or two in the 80s will likely not surprise any of us.

A Generational Autumn

Climatological autumn runs from September 1 through November 30.  The past three months of weather was notable for both temperature and precipitation.   If you have spent your entire life in this area, this past fall could have been the warmest you have ever experienced as the last time temperatures were this mild was back in 1963.

Although, we have experienced several above normal autumns in the past decade, none were warm enough to crack into the top 10 until this year.  The past three months ranked as the 9th warmest such period on record.  Previous to this year the warmest 10 autumns occurred before 1964.

Not only has it been mild lately, but also very dry.  Autumn 2011 recorded only 1.43 inches of rain and melted snow which ranked as the 4th driest since 1881. Fargo Moorhead averages 5.72 inches of precipitation in autumn and this year was our first year significantly below that average since 2003.

The Autumn Forecast

Three months ago in this space, I wrote about what I thought the general weather would be in the upcoming autumn season.  I mentioned that based on similar setups in the past, that the season would likely finish with above average temperatures.

In the end, all three months finished with above average temperatures and when the official statistics become available this fall will easily finish as one of the Top 10 warmest on record.  At the same time, I mentioned that there were several signs pointing toward the autumn finishing drier than average, but, I also wrote that considering how wet this area has been lately, my confidence in that forecast was lower than with the temperature projection.  Locally, the past three months were not only dry, but remarkably dry.

So, in the end, I was happy not that my forecasts verified, but that the weather patterns, even in this wet phase, finally left the area dry going into winter instead of saturated like the past few years.

The Last Leaf

Many of the elm trees around Fargo Moorhead are still hanging onto their leaves, at least for the moment.  Walking down the street under a canopy of brilliant yellow is uplifting whether the weather is sunny or cloudy.  Maple trees, the iconic sex symbol of autumn, have mostly passed their prime, as sex symbols inevitably do.

In a way, the so-called “peak” of fall colors is often something of a let down, being so short and weather-dependent.  There is a lot of color left in this fall season.  The brightest oranges have mostly fallen.

But look closely at a field of grasses and natural prairie and you will see a richness of more muted tones than were noticeable a month ago.  Look deeply into what at first glance is just brown and you will see subtle shades of red and purple, and colors that have no name at all, but manage to burn sharply like an aurora on the northern horizon.

October Jinx is Over

Although recent years have recorded some very mild autumns, the month of October has often been an exception.  An example of this occurred just two years ago when the fall of 2009 ranked as the 9th warmest on record, yet, October 2009 finished as the 9th coldest since 1881.

That same autumn both September and November finished as the 2nd warmest such months on record.  In fact, all of the Top 10 warmest Octobers occurred before 1964.  The warmest October on record was in 1963 and following that year none of the next 47 Octobers finished anywhere near the Top 10.  That has now changed.  Last month finished with an average temperature of 52.7 degrees which ranked as the 6th warmest October.

Combined with September the last two months have ranked as the 9th warmest such period in the past 131 years and like October, the warmest such stretch since the fall of 1963.