Hoping for a mild, dry winter? You might be disappointed

El Niño gone/ La Niña here

Winter 2016-2017 is upon the Dayton region, and from the looks of things it’s likely to be very different winter than winter 2015-2016. A major reason for the change is the strong El Niño conditions which persisted throughout winter 2015-2016 are gone. La Niña conditions have taken their place. However, the current La Niña is weak, and its impact on local weather will probably not be as great as the 2015–2016 El Niño event.

La Niña winters tend to bring moisture to the Ohio Valley

La Niña conditions occur when equatorial sea surface temperatures are below average in the central and east-central Pacific Ocean. This is the exact opposite of what occurs during an El Niño. Like El Niño, La Niña impacts global weather patterns by influencing the position of the polar and Pacific jet streams. During La Niña winters, the polar jetstream tends to dive south over North America. The polar jet stream brings cold air and storm systems to northern portions of the United States.

la-nina-graphic

According to National Ocean and Atmospheric Administration, we can expect La Niña conditions to persist through February 2017. After February, its likely La Niña will transition to neutral conditions sometime during spring 2017. Neutral conditions mean that neither El Niño nor La Niña conditions are present in the equatorial Pacific Ocean.

So what does this mean for our region in terms of winter weather?

Winter 2016 – 2017 is likely to be wetter and cooler

The odds favor a wetter and cooler winter 2016 – 2017 compared to winter 2015 – 2016. Is this a guarantee? No it’s not. There are a multitude of other climatic factors at play in determining winter weather outcomes in our region. El Niño and La Niña events are just one of those factors.

El Niño 2015/16: A recap

El Niño contributed to a mild winter in the Miami Valley

By Mike Ekberg, water resources monitoring and analysis manager

If you thought the region got off easy this winter, you’d be right.  And you can thank El Niño.

El Niños  produce drier and warmer than normal winters
El Niño affects weather worldwide by changing the way air circulates in the atmosphere.

El Niño is a weakening of eastward blowing winds over the Pacific Ocean creating warmer than normal water in the eastern Pacific Ocean near the equator.El Nino graphic

El Niño tends to keep the polar jet stream—and cold arctic air—farther north and out of the Miami Valley. It also tends to shift the Pacific jet stream—and winter storm systems—to our south. Together these patterns tend to produce warmer and drier winters locally.

Above average temps and precip
Average monthly temperatures for January through March were well above normal, according to the National Oceanic and Atmospheric Administration (NOAA). Dayton saw above-normal daily average temperatures all three months. This is exactly what we expect during an El Niño winter. The 2016 winter was the 10th warmest recorded for this region, dating back to 1895.

Precipitation was near normal, with an average of 8.94 inches in the Miami Valley. That’s 0.87 inches above normal. January and February precipitation were below normal, but March was above normal. So winter 2016 brought more precipitation than expected for an El Niño winter.

It’s anyone’s guess as to why precipitation was greater than expected. Other factors besides El Niño influence local weather. Sometimes the random nature of weather is beyond our ability to predict.


La Niña on the way?
While El Niño 2015/16 was one of the strongest ever recorded, it’s weakening. Most climate forecasts predict it will end during late spring or early summer and will eventually change over to a La Niña phase. Some forecasters expect that shift this summer.

It’s too early to tell how La Niña conditions in the Pacific Ocean will shape our next winter. Stay tuned.

 

Winter 2016 and “The Mother of all El Niños”

El Niño is getting a lot of media attention these days being blamed for floods, famine, and the spread of diseases. This year’s El Niño is shaping up to be one of the stronger, if not the strongest, El Niño in history. In fact, it’s drawing comparisons to the 1997 El Niño event, which is the strongest El Niño on record and sometimes called “The Mother of all El Niños.”

According to the National Oceanic and Atmospheric Administration (NOAA), the current El Niño event in the Pacific Ocean is expected to peak in December, but the impacts of El Niño are expected to last well into the spring of 2016. These impacts are likely to influence weather in our region.

El Nino comparison

Comparison of 1997 El Niño (left) and 2015 El Niño

When it comes to Earth’s climate, weather phenomena happening in faraway places can sometimes have dramatic impacts locally. El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific Ocean. The image above shows areas of the Pacific Ocean with above-normal water temperatures colored in red in August of the 1997 El Niño event and August of 2015.

When El Niño occurs, very warm waters in the Pacific Ocean pump more moisture into the atmosphere. This impacts and changes the direction of major wind currents, steering weather systems across the United States. In other words, the typical storm paths in the United States are shifted. Typically, El Niño shifts storm tracks south during the winter months resulting in increased precipitation across the southern tier of the United States. At the same time, El Niño tends to bring warmer-than-normal temperatures to Alaska, Canada, and the northern tier of the United States. 

2016 3 month precipitation outlook

2016 3-month precipitation outlook

So what El Niño effects can our region expect
to see for the upcoming winter and spring?  According to NOAA’s climate prediction
center
, our region is likely to experience a mild winter temperature-wise with below-normal precipitation. The image on the right shows areas of the United States expected to have above-normal precipitation in green and
below-normal precipitation in brown over the next three months. Most of Ohio is colored in brown. The outlook for spring is similar, with near-normal temperatures and below-normal precipitation.

Is this forecast a sure bet? It isn’t. The Earth’s climate systems are extremely complex, and El Niño is only one of many factors influencing our weather. The temperature and precipitation outcomes we experience this winter are a result of a multitude of complex interactions among the Earth’s weather systems. We can only wait and see!

Globally, a record warm June; locally, a very wet June

By Mike Ekberg
Water Resources Manager

According to the National Oceanic and Atmospheric Administration (NOAA), June 2015 was the warmest June ever from a global perspective. The combined average temperature over global land and ocean surfaces was the highest ever measured for the 136 years in which records have been kept. The combined average temperature across the world’s land and ocean surfaces was 0.88 °F above the 20th century average.

In fact, the first six months of 2015 comprised the warmest six-month period on record across global land and ocean surfaces at 1.53°F above the 20th century average. This might seem surprising to Miami Valley residents because we experienced cooler than normal temperatures. The first six months of 2015 were cooler than normal across most of eastern North America, probably due to several southern invasions of the polar vortex which brought cold arctic air into eastern portions of Canada and the United States during the winter of 2015.

In addition to tracking temperature, NOAA also tracks precipitation globally. Precipitation in June was highly variable, but much of eastern North America received precipitation in the normal to twice-the-normal range for the month. The Ohio River Valley, the eastern portion of the Lake Erie Basin, and the Mississippi River Valley in Illinois and Iowa were particularly wet. Much of this region received 5 to more than 10 inches of precipitation in June. Flooding occurred throughout portions of northwest Ohio, northern Indiana, and Illinois.

MCD tracks precipitation in the Great Miami River Watershed. MCD’s records show June was a very wet month in the Miami Valley as well.

  • Monthly precipitation at MCD observer stations ranged from 5.60 inches at West Milton to 11.61 inches at Fort Loramie.
  • Mean precipitation for the Great Miami River Watershed was a little more than 8 inches, twice as much as we would normally expect in June.
  • Runoff for the Great Miami River measured at Hamilton was a little over 3 inches, three times the normal amount of runoff in June.
  • MCD dams stored water on two occasions in June.

Despite these numbers, June was not a record-setter locally. The wettest June on record occurred in 1958, when an average of 10.30 inches of precipitation fell across the watershed.