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The Upcoming Winter Weather (2015-16) MIGHT Look like This

North Country Public Radio

I'm thinking out loud today so bare with me.

Over the last few days, I was playing around with the constructed analogs of similar winter years. Using a set of 6 best fit years and weighting them equally, I constructed a blend for each month starting in November and ending with February showing the upper level pattern across the North American Continent. The color colors show where the storm system would develop (Low pressure). The warmer colors show where High Pressure systems reside.

The first burst of colder air occurs in November, the pattern relaxes in December then reloads after the first of the year. Can you see how the southern jet stream becomes very active, dominant force in the second half of the winter. February shows the much higher frequency and strength of low pressure systems from the southwest. This indicates a higher propensity for wetter snows from northern Texas, northeast into the Mid Atlantic states and Ohio Valley similar to 2010.


UPPER AIR PRESSURE (500 mB)

NOVEMBER BLEND

DECEMBER BLEND

JANUARY BLEND

FEBRUARY BLEND

SURFACE TEMPERATURES


Last winter's actual temperatures versus our Winter Outlook issued in October.  Not bad.

The overall temperatures for this winter according to the best matches are not as cold across the eastern 2/3rds of the US when compared to the winters of 2014-15 (recap of last winter at this link) or 2013-14.

NOVEMBER BLEND

DECEMBER BLEND

JANUARY BLEND

FEBRUARY BLEND

Snowfall departures (above or below average) are much higher in January and February during moderate to strong El Ninos especially when these El Ninos are more central based (Modoki, using the EMI Index). 

Will this strong El Nino have some central based signature tendencies? Maybe more eastern El Nino characteristics thus a warmer winter overall with little snow? 

The Constructive Analog from Huug van den Dool's page on the CPC site shows the core of the ENSO warmth in the ENSO 3.4 region with a slow drift WEST toward the Dateline by late winter.

Will this verify?  Only time will tell. 

Many meteorologists in the private sector don't like using the Analog Method too literally because the probability of finding an exact match over such a large area is incredibly small. I get that. However, I have found that analogs give a glimpse into how the atmosphere responds to the various drivers in closely matched years. This group of "best fits" for this winter has stayed consistent over the last several months.  Several notes: Analogs are only one of several tools that I use in assessing seasonal outlooks. El Nino is only one of the many factors that will play a role in our winter weather. I did not include any ENSO dynamic model guidance in this post. That is a story for another time.

Huge Rainfall Differences: Summer 2014 vs 2015

After the record setting rains of late spring early summer, conditions have dried out considerably for much of Ohio.  Look at the differences between last summer and this summer as we compare rainfall from June 1st through July 4th.

2014

2015

Who thought the deficit would this large two week from Labor Day given the overall pattern

A Deeper Look At The Top 10 El Ninos Since 1870

As this current El Nino continues to evolve, it helps to visualize how these changes in the tropical Pacific ocean temperatures drive the changes in the hemispheric circulation which impact our winter weather across the US.

How do we define an El Nino? The Climate Prediction Center uses the ONI (Oceanic Nino Index) to define El Nino and La Nina events. Their definition for El Nino/La Nina using the ONI is as follows:

An El Nino event is defined when the three month running mean of (ERSST.v4) sea surface temperature anomalies in the Niño 3.4 region climb above the threshold of 0.5^o for five consecutive overlapping three month periods.

In other words, we take the average ocean temperature anomaly in the 3.4 region over a 3 month period, say September through January.  Take the next five month overlapping periods--October through December and November through January--(the first two for example) and find these averages. That is your five consecutive, 3 month running mean. If this period's average is at or above +0.5 degrees, we classify this as an El Nino. The ERSST.v4 dataset goes back to 1850.  Using this methodology, the top 10 strongest E Ninos are easy to find. Hat tip to Eric Webb for compiling the ERSSTv4 data.

The top ten El Ninos are as follows:
1877-78, 1888-89, 1982-83, 1997-98, 1896-97, 1902-03, 1905-06, 1940-41, 1957-58, 1972-73
What do the sea surface temperatures for each of these El Ninos look like? I created an animation of each El Nino's six, three month overlapping period starting with the September-November period ending with the February-April period.  Each El Nino evolves differently. The position of the equatorial warm water, position and strength of the warm/cool pools in the PDO region are different with some, similar to others. Here is each sea surface temperature anomaly animation from the list above.

1877-78 El Nino

1888-89 El Nino

1982-83

1997-98

1896-97

1902-03

1905-06

1940-41

1957-58

1972-73

How does the atmosphere respond in each of these cases at the 300mB level?  More on this later.

What were the winter temperatures like in each of these strong (both eastern and central) El Ninos?


One glaring similarity is that each of these El Nino events (1888-89, 1940-41 and 1957-58) average temperatures across the eastern US stayed close or slightly above average in December and in January. Then in February, the bottom falls out and temperatures drop significantly below average across a large area of the east. If you look at the Pacific sea surface temperature configuration of these winters (eyeballing the ENSO region, Eastern Pacific/west coast/Gulf of Alaska regions and Pacific Meridional Mode area), they closely resemble this year!

 

Yes, Big El Nino Brewing But Not All El Ninos Are Alike: 2015 vs 1997

You have probably heard about the BIG EL NINO or SUPER EL NINO or some phrase like that. If not then you will soon enough. Eventually EL NINO will trend on social media by the end of September. You heard it here first.

But hold on. Doesn't Big El Nino mean mild winter?  Not necessarily. See the differences between the last BIG El Nino in July 1997 and July 2015.  Also, notice the differences in the North Atlantic ocean temperatures? This is why the winter 2015-16 outlook is not an "El Nino shoo-in". Not all El Ninos are alike. (See my post on the different El Ninos and what they mean for our weather)

When will we know enough to make an educated assessment on the upcoming winter?  Probably by the end of September. Stay tuned...

Record Setting June Rainfall

The persistent pattern featuring frequent rain across the Ohio Valley ramped up into high gear the second half of June. Most points from Columbia, Missouri east into the Mid Atlantic states received between 100 and 400% MORE rainfall than normal this last month.

Parts of northern Ohio had between 10 and 15 inches as a stalled front oscillated back and forth triggering clusters of rain and storms. Cleveland's monthly total was 3rd most in 145 years, most since 1972.  Ft Wayne, Indiana set their all-time June rainfall record with 11.98". It broke the record for the wettest month set in July of 1986! 

Last summer's wet region was centered in the heart of the corn belt.

This summer's wet areas have shifted east into the Ohio Valley including Pennsylvania, Maryland and portions of New Jersey.

 

Compare the past two summer to the very warm summer of 2012. Dry conditions prevailed with the development of a flash drought across parts of the US. I gave a talk at the Ohio State Weather Symposium on the causes and the conditions that feed that summer's dry pattern.

My POWER POINT from the symposium is here. Check it out.

The average temperatures for July and August in 2012 were certainly influenced by the lack of rainfall. Notice the location of the temperature anomalies.

Temperature anomalies in 2014 were noticeably cooler over the wetter ground in the Corn Belt.

I emphasize that the rainfall or lack thereof was not the primary driver of the patterns in either 2012 or 2014.  It was an enhancer. June temperatures were at or slightly below normal.

Record high temperatures across the Midwest were markedly lower in 2014 vs 2012.

Big question, how will the June rainfall in the Ohio Valley influence the temperatures in the upcoming weeks?

More than likely, we should see a dampening of long stretches of heat in the mid-west, corn belt and Ohio Valley.  July could end up with temperatures at or below average from St. Louis to Cleveland.

Early Summer El Nino Update

More geeky weather talk ahead >>>

The newest updated from the MEI (Multivariate Index) website run by Klaus Wolter shows a significant increase over the last month of +0.61 to +1.57 as of April/May which rates the El Nino in the strong category using a ranking method.  If we look at the top April/May rankings according to Mr. Wolter then then take away the El Nino events that were weakening as of April/May, we are left with the 5 years below. ALL OF THESE YEARS STAYED AT EL NINO LEVELS THROUGH THE END OF THE YEAR.

One important note: Only 1998, 1993, 1992, 1987 and 1983 had HIGHER MEI levels in April/May. 1987 was a only building El Nino. The rest were fading or close to it.

The El Nino is very apparent in the current sea surface temperature anomaly map in the last week of May.

The 2014 El Nino (although not official using the ONI) was considered weak by many meteorologists including myself.  If you assume a weak El Nino for a time last year, this year's much stronger event would be a 2nd year El Nino. Expanding the possible El Nino matches using the MEI TIME SERIES for "double El Nino events" we found two such events:  Late 1991 through 1993 and 1986/87.  A 2nd year El Nino has the advantage of an ocean already primed from the previous one.

It's not an exact match but comparing these two years to 2014-15 gives us an idea of a possible El Nino outcome.  Remember that this year's El Nino is developing much earlier. Most El Nino's develop in late summer and fall.

By examining the MEI, assuming a building El Nino, a double El Nino event (last year was weak) and a very high April/May MEI, a good match so far is the 1986-87 event.

What were the bi-monthly overlapping sea surface temperature anomalies starting in April through the end of 1987?  Notice the cooler water in the western Pacific near Australia which is necessary for the development of a strong El Nino according to the Australian Bureau of Meteorology.

Watch how the lower temperature areas warm by the end of the year (lower two maps below) and the warmest regions start to cool a bit as the El Nino started to fade by year's end.

How about this year's event?  The water off the coast of Australia (circled in red) is starting to cool comparing April 1st to may 27th but not at the level of the 1986-87 event...yet.

This El Nino continues to strengthen much earlier than other El Ninos. We continue to watch the water temperatures in the western Pacific near Australia as they cool.  How cool will they get? Will the El Nino peak in late Fall then taper off?

Models are strongly hinting at this...

Our summer outlook took much of this into account. Check it out here on my weather blog post from early May. 

BIGGER QUESTION, how will this El Nino impact winter?  Too early to call. More on this in August!