GRAND RAPIDS, Mich. (WOOD) — Summer officially kicks off Monday and there is a strong chance this summer will be hotter than usual, with several 90-degree days.
The start of 2016 was cool, as expected.
“We said it was going to be a mild winter, we said we would probably get a period of cold during early April, we guessed the snow total for the winter almost exactly here,” recapped Storm Team 8 Chief Meteorologist Bill Steffen.
Now entering summer, several factors are pointing to a hot and dry summer, especially late in the season.
HOTTER THAN AVERAGE
One of the big players in this summer’s forecast is the ocean temperatures in the tropical Pacific. This past winter, the water there was much warmer than average. This led to a strong El Niño event, which impacted our jet stream and gave us a mild winter.
Now that same area of water is turning colder than average, which is expected to push us into a moderate La Niña pattern. This will likely lead to a hotter summer.
“Last summer was almost two degrees cooler than normal. I expect this summer is going to be three to four degrees warmer than normal. That’s about a five degree shift from last summer to this summer,” said Steffen.
This doesn’t just mean days are hotter; nights may be warmer than usual too.
SEVERAL 90-DEGREE DAYS
Already this June we have seen two 90-degree days. That is the first time Grand Rapids has recorded a 90-degree temperature in June since 2012.
The previous two summers, 90-degree days were scarce.
“We had a goose egg here in 2014 and then in 2015, last summer, we only had two days that reached 90-degrees,” Steffen elaborated.
While investigating previous years with similar conditions, Storm Team 8 Meteorologist Matt Kirkwood found hot days were pretty common.
“One thing we researched and found out is that we’re going from a strong El Niño to a La Niña really quickly,” Kirkwood said.
Since 1954, there have been nine years (excluding this one) that have had weather patterns flipping quickly from and an El Niño to a La Niña. All of those years included several 90-degree days.
The fewest number of 90-degree days one of those nine summers had was eight. One summer had more than 30 days that hit 90-degrees or hotter.
“The years that we go from an El Niño all the way to a La Niña you have heat, like serious heat: mid-90s, upper-90s in a couple instances a few 100-degree days,” said Kirkwood.
A heat wave is a string of at least three days where the temperature hits 90 degrees or hotter. Our last heat wave in West Michigan was in 2013 with a six-day stretch of temperatures 90-degrees or above.
The frequency of 90-degree days means we have a good chance of seeing a few stretches of 90 degree days. Don’t be surprised to see at least one, if not two heat waves this summer.
Heat is one of the biggest weather related killers each year. After two mild summers, the exposure to heat may be difficult for people to handle.
The hottest weather this summer will likely happen late in the summer season. There are a few factors that will likely delay the heat, including a very wet winter season and early spring.
“This is the second-wettest Jan. 1 through April 15 we’ve ever had,” said Steffen.
Any incoming sunshine must first evaporate that excess moisture and dry the ground before it can warm up West Michigan.
Another reason the heat may be delayed is the phase of the Pacific Decadal Oscillation. Just like the El Niño or La Niña phase, the PDO can alter the jet stream and change our weather. The start of our summer will likely be influenced by a sagging jet stream, bringing us a bit of cooler weather.
High wind events seem to be the most likely severe weather threat this upcoming summer, if history is any indication.
“The last two times we had a very strong El Niño collapsing like this, we had a line of very heavy thunderstorms come through the Great Lakes,” said Steffen.
One of the most significant lines of storms to ever sweep through Michigan happened in a year with a similar set-up to this summer.
“The big year was 1998 when we had probably the worst line of thunderstorms ever to go through Michigan. It produced winds as high as 130 mph. That pattern was similar to what we have now,” added Steffen.
This doesn’t mean we are guaranteed a severe weather event like that of 1998. That storm was a once-in-a-lifetime event.
“But we should be cautious for fast-moving thunderstorms moving west to east across the Great Lakes here this summer,” said Steffen.