The Difference Between Meteorological and Astronomical Winter

"Sorry but it's still fall NOT winter!"

We get tons of notes from viewers like this each year after we tell everyone that meteorological winter just began on the first of December.

So what is the difference between Meteorological Winter and Astronomical Winter, the one that starts around December 21st?  NOAA--National Oceanic Atmospheric Administration--has a great explanation:

...The astronomical seasons are based on the position of the Earth in relation to the sun, whereas the meteorological seasons are based on the annual temperature cycle. The natural rotation of the Earth around the sun forms the basis for the astronomical calendar, in which seasons are defined by two solstices and two equinoxes. Both the solstices and equinoxes are determined based on the Earth’s tilt and the sun’s alignment over the equator. The solstices mark the times when the sun’s annual path is farthest, north or south, from the Earth’s equator. The equinoxes mark the times when the sun passes directly above the equator. In the Northern Hemisphere, the summer solstice falls on or around June 21, the winter solstice on or around December 22...

Because the Earth actually travels around the sun in 365.24 days, an extra day is needed every fourth year, creating what we know as Leap Year. This also causes the exact date of the solstices and equinoxes to vary. Additionally, the elliptical shape of the Earth’s orbit around the sun causes the lengths of the astronomical seasons to vary between 89 and 93 days. These variations in season length and season start would make it very difficult to consistently compare climatological statistics for a particular season from one year to the next. Thus, the meteorological seasons were born.

Meteorologists and climatologists break the seasons down into groupings of three months based on the annual temperature cycle as well as our calendar. We generally think of winter as the coldest time of the year and summer as the warmest time of the year, with spring and fall being the transition seasons, and that is what the meteorological seasons are based on. Meteorological spring includes March, April, and May; meteorological summer includes June, July, and August; meteorological fall includes September, October, and November; and meteorological winter includes December, January, and February. These seasons were created for meteorological observing and forecasting purposes, and they are more closely tied to our monthly civil calendar than the astronomical seasons are. The length of the seasons is also more consistent for the meteorological seasons, ranging from 90 days for winter of a non-leap year to 92 days for spring and summer. By following the civil calendar and having less variation in season length and season start, it becomes much easier to calculate seasonal statistics from the monthly statistics, both of which are very useful for agriculture, commerce, and a variety of other purposes.

You can read the entire explanation HERE  (courtesy: NOAA)

Does Our Early Winter Warmth Mean An Above Normal January & February?

JEFFERSON, OHIO

Someone today mentioned that it had been a LONG TIME since we had such a mild late fall/early December in northern Ohio. So I checked the temperatures to see if this was true.  Sure enough. He was right.

WARMEST YEARS - NOVEMBER 1 to DECEMBER 7

1st    2001              
2nd   1931  
3rd    2015 (thru December 3rd)
4th    1994   
5th    1982 
6th    1998 
7th    2011 
8th    1902 
9th    1948 
10th  1909

That's great but what are the January-February periods like in these years? The final numbers are below:

• ALL BUT ONE WAS SIGNIFICANTLY ABOVE NORMAL

• 4 OF THE TOP 10 YEARS STAYED IN THE TOP 10 IN JANUARY AND FEBRUARY

WARMEST YEARS        JANUARY-FEBRUARY 
NOV 1 to DEC 7            TEMPERATURE RANKS  (DEPARTURE - 30 YR RUNNING AVG)

1st    2001                9th warmest            +6.4    
2nd   1931              1st warmest          +10.5  
3rd    2015              ???
4th    1994              64th warmest          +2.1   
5th    1982                19th warmest          +6.2
6th    1998              34th warmest          +3.5 
7th    2011              10th warmest          +4.7 
8th    1902              81st warmest          +0.1  
9th    1948              8th warmest            +5.8  
10th  1909              102nd warmest       -1.0  


Unless something changes significantly, our winter outlook which featured near or slightly above normal temperatures with slightly below average snowfall should hold up.

How Much El Nino Warm Water Is Out There?

Often times, weather maps are hard to conceptualize unless you use them everyday. Since the summer, my El Nino posts have been filled with colorful maps analyzing ocean water temperatures, air pressure, possible winter storm tracks and air temperature. These maps are pretty basic for meteorologists and atmospheric scientists who view these everyday. For the non-scientific viewer, the colors can be as convoluted as a Rorschach diagram if not properly put into perspective.

Below is a picture of the Pacific Ocean temperatures relative to average.  Warmer and cooler pockets are easily visible. The El Nino is the band of warmer colors in the middle along the equator.

Just how large is this area of warmth?  How much water are we talking about?

Consider that the length of Lake Erie is approximately 240 miles. The distance across the main ENSO region in the yellow box below where the core of the warmth is located is roughly 5000 miles. The depth of this warmth is roughly 100 meters or slightly more than 300 feet.

The area boxed in yellow is roughly equivalent to 75% of the contiguous United States.

Performing a quick volume calculation (area times depth), we come up a HUGE volume of relative warm water in the El Nino region using these parameters: 

The VOLUME water in the equatorial Pacific Ocean where water temps are running at least 3 degrees Celsius (~5 deg Fahrenheit) above normal is more than 25 TIMES GREATER than volume of ALL the Great Lakes! WOW!

Do Warm Novembers Lead To Warm Decembers?

Our November forecast was for above normal temperatures.  Through the 16th (eventually through the 18th) it will verify quite nicely.  But do these warm temperatures across much of the US mean that december will be warmer than normal?  Not necessarily. I found the warmest FIRST HALF NOVEMBERS in northern Ohio and charted below the Decembers that followed.

Notice that each December is a bit different.

The bottom line is you cannot use a few weeks in early November as the only predictor of the month or winter ahead. 

Look what happened last winter. Each box shows the temperature across the country for each month left to right starting in November and ending in February.  I guarantee that most people were thinking these thoughts after each month:

I Need Your Input/Ideas

It's been almost 10 years since I started my weather blog SCOTT'S WORLD OF WEATHER. Back in late 2005, it was a more general blog about my observations of the world as a new father coupled with some random science and weather. About 5 years into it, my focus shifted to the technical side of weather, atmospheric science, forecasting and our perceptions/biases of both. It slowly became a diary of my thoughts about these technical subjects which, by their nature can, and have become self-indulgent to a certain degree. The last thing I want is to be so far drawn into a subject technically that the narrative I'm trying to convey becomes thickly bloated with esoteric terms and convoluted analysis. The last thing I want to do is lose people.

As a result, I believe many posts have lost sight of what the reader really wants.  So I'm asking everyone who reads my blog what they would like me to cover and how they would like it done. Let me know what you like, what you don't. Let me know what was too hard to understand.  Please let me know in the comment section below. Do you want more explanations,less explanations? Pictures? While I can't promise that each blog post will be clean and simplified for every one's taste (after all, the world of science is a very complex place), I will work on explaining each element a bit better.

Send me your comments at the bottom of this page or at the following locations:

Via email:  scott.sabol@fox8.com
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YOUR FEEDBACK IS WELCOME.

In advance, thank you!

El Nino Update: 1997 vs 2015

I plotted the weekly sea surface temperature anomalies starting in early June for the ENSO 1.2 region (closest to the South American coastline).

 Notice how 2015 is running cooler versus the 1997 event. Another component into our winter weather outlook which airs this Thursday at 6PM on FOX8!

Winter Temperature Trends in Ohio (Midwest)

The National Climate Data Center has a great site for graphing the many climate divisions and climate regions across the U.S. So I plotted the winter (December through February) average temperature trends for various regions around northern Ohio since 1940. I chose 1940 because prior to the late 1930s, the official NWS temperature reading was taken at various locations throughout the Cleveland area. Since 1940, Hopkins Airport has served as the official NWS temperature location.

Notice the very cold winters of the early 1960s, late 1970s, highly variable winters of the 1990s and early 2000s and the last two cold winters at the far right side of the graph.

Overall, the trends are similar with each graph showing winter temperatures more consistently above average since the early 1980s. The overall warming trend however amounts to a tenth to a few tenths of a degree per decade in Cleveland and surrounding climate divisions and outside regions.

Note: My only aim is to show the past winter temperatures (December through February) with NCDC data. Nothing more. Nothing less.

ENTIRE STATE OF OHIO

 Ohio climate divisions:

NORTHEAST OHIO

NORTH CENTRAL OHIO

 

MANSFIELD, ASHLAND REGION

CORNBELT

OHIO VALLEY: OH, IN, IL, MO, KY, TN, WV

Precipitation and El Ninos: West Coast Rains Not Always A Lock

Not all El Ninos are alike. We've heard this time and time again. Sea surface temperatures are never exactly alike. Jet stream position varies. Overall winter temperatures vary too as does the location of above and below normal precipitation. We remember the El Nino of 1997-98 that produced heavy rains out west.  But that's not always the case.

We examine the top El Ninos according to the ONI Index from this site. We only examined the El Ninos that are ranked MODERATE, STRONG AND VERY STRONG.

THE STRONGEST EL NINOS (1997-98 and 1982-83)  

Storm track kept heaviest precipitation along the west coast and in the southeast.  At or below normal precipitation around the Great Lakes.

STRONG EL NINOS - RANK #3, #4 AND #5

Storm track is still strong in the deep south with a southerly shift out over the Gulf of Mexico with above normal precipitation.  Aside from the winter of 1957-58, precipitation along the west coast is less in these years. Still below normal precipitation across much of the Great Lakes.

MODERATE EL NINOS

Southern storm track is still strong but weaker during the winters of 1986-87 and 1963-64. Storm track shifted much further north into the Ohio Valley and Mid-Atlantic during the winters of 2002-03 and 2009-10 with heavy wet snows. During many of these winter, well below normal precipitation was observed along the west coast especially during the winter of 1963-64

Contrary to what you hear, its not a guarantee that El Ninos always produce heavy precipitation events across the west coast and the Pacific Northwest. It does appear that the chances are greater with stronger El Ninos per the ONI Index.  The southern storm track seems to be more consistent--with varying intensities--in each of top El Ninos. 

============================================

A few side notes:

* Another modulator of the El Nino and storm track is the mode of the PDO (Pacific Multidecadal Oscillation). The winters of 1957-58, 86-87, 87-88, 97-98, 2002-03 and this year so far all have PDO values strongly positive.

* Yet another area of the Pacific that may have ties to the evolution of El Nino is the Pacific Meridional Mode located between the equator and Baja California. The link between the two is being studied. Here is a paper published in 2014.  Looking at the data from late summer through fall during early El Ninos, late 1957, 1986, 2009, 2015 (and partly 1982 although it was trending cooler) all had positive values (above normal water temperatures).

Do we see some matches above for this winter?  Hmmmm.

Northern Most Hurricane EVER!

Hurricane Joaquin is still churning out in the open Atlantic more than 14 days since it become a tropical depression on September 28th in the Caribbean.

The official track from the NHC has it sustaining tropical characteristics through the upcoming weekend as it tracks as it approaches Europe.

This had me wondering what the furthest NORTH any hurricane has traveled. The award goes to Hurricane Faith in 1966. This system started out off the coast of western Africa, headed toward the Caribbean then north off the coast of the U.S. then out to sea. It lasted 26 days and traveled more than 6800 miles. 

What I find fascinating is that according to the official track data (wind, position and date) it held hurricane strength over incredibly cold water. The hurricane crossed into water below 20 degrees Celsius off the coast of Nova Scotia yet it stayed at category 2 strength for another two and a half days.

WATER TEMPERATURE IN CELSIUS

The storm didn't officially weaken until it reached the north of Great Britain where the water temperatures dropped to between 10 and 12 degrees Celsius. The "X" marks the approximate location where Hurricane faith was downgraded to a tropical storm....yet it continued as an extra tropical storm/low into Scandinavia for another week!

The National Hurricane Center has a great summary on the hurricane season that year. They show a  map of Faith denoting its movement into the arctic north of the Arctic Circle into the Soviet Union then north into the Barents Sea where water temperatures were barely above freezing.

Air temperatures were in the 30s and 40s.

It finally ended its journey over an uninhabited island chain north of the Arctic Circle around 600 miles from the North Pole.