Brett Anderson

Share |

Possible Clues Into the Summer

March 17, 2014; 3:06 PM ET

As I mentioned in the previous blog, I wanted to show you what the general long-range computer model forecast consensus indicates in terms of weather patterns each month through August.

A few things to keep in mind.....

1. My interpretation is strictly based on the latest combined multi-model ensemble forecast system (National/International), which is still experimental but has shown increased skill over individual models. These are not AccuWeather. com forecasts.

2. Model skill declines steadily beyond April, so do not take these as gospel. Model skill is usually higher with temperature compared to precipitation.

3. Due to a lack of signal (neutral ENSO for instance), these forecasts are heavily influenced by current conditions such as ocean water temperatures and ice coverage. The forecast for cooler temperatures around the Great Lakes in May is likely a reflection of the much higher-than-normal ice cover, which may lead to colder-than-normal waters in April/May, which has a localized cooling influence.

3b. Also, when there is a lack of signal I have noticed that the model ensemble tends to lean much more toward warmer anomalies versus cooler anomalies. Part of this may be due to the fact that the Canadian normals are still too low and need to be adjusted upward due to longer term climate change.

4. There continue to be growing signs that we are headed for overdue El Nino conditions in the equatorial Pacific, perhaps as early as the summer, though I lean more toward the early fall. If El Nino does return, we could start to see some impacts perhaps as early as this winter in the northern U.S. and Canada. With an El Nino, the good news is that the extended long-range models will have a stronger climate signal to latch onto, which could lead to improved forecast skill next winter and the following spring.

5. There appears to be solid consensus for a stronger-than-normal monsoon in the southern U.S. Rockies this summer.

6. Models are also projecting drier-than-normal conditions (less tropical storms/hurricanes) in the tropical breeding grounds of the Atlantic late this summer and into the fall, which may be a reflection of cooler waters, dry air and the start of El Nino.

7. Areas that are not shaded in the maps below either indicate near-normal temperatures/precipitation or are an indication of high uncertainty.

Projected average pattern for April

May

June

July

August

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

Comments

Comments left here should adhere to the AccuWeather.com Community Guidelines. Profanity, personal attacks, and spam will not be tolerated.

More Canadian Weather Blog

  • Storm Snowfall Map

    December 16, 2014; 10:34 AM ET

    Storms will target the East and the West once again this week.

  • Forecast Model Update into January

    December 11, 2014; 10:50 PM ET

    Incredible weather over the past couple of days in the West and East. So what do the next few weeks look like?

About This Blog

Brett Anderson
Brett Anderson covers both short-term and long-term weather and storm forecasts for Canada in this blog for AccuWeather.com.