The weather outside is frightful, no relief in sight


While the East coast swelters in record heat, the Midwest ducks for cover, and Arizona is under fire, the West has another problem.

It’s damn cold.

In other words, no, it’s not your imagination that things out there are outright weird, weather wise, for this time of year.

Mammoth hasn’t yet hit 70 degrees once this year, something that generally happens around May 17 on average, according to Reno-based National Weather Service meteorologist Jim Wallmann. Not only that, but it’s not going to reach that mark any time soon, maybe as far out as two more weeks.

Mammoth hit its warmest day of the year so far on May 13 – 68 degrees. After that, temperatures headed back to the low 60s, then even further down to the 50s and 40s and this week, below freezing.

“You will see it gradually warming up by the middle of the month, but before that, you’ve got another snowstorm headed your way as soon as this coming weekend,” he said. “And it won’t warm up even then to the normal temperature for this time of year.”

That puts the first hope of summertime temps and weather about a month behind normal.

Even in Reno, where it’s typically in the high 80s by now, Wallmann said he woke to snow “in the middle of the day!” – when he went home for lunch.

“It kind of freaked me out,” he said with a laugh. “It’s not that we, and Mammoth, don’t get snow in June. We do. But it’s usually just a quick storm, surrounded by normal warm temperatures overall.”
Wallmann said this spring’s cold and snowy weather is definitely unusual, although not unprecedented. In 1995 and again in 1998, the Mammoth area experienced a similar spring, although both were warmer overall and both ended sooner. Even last year, May was unusually cold, almost as cold as this year. The difference again, is that it ended sooner, by the first day or two of June, Wallmann said.

The culprit this year is the jet stream, a huge mass of air about six miles above the earth’s surface and about 200 miles wide. The jet stream hangs out up there wherever the temperature gradients between the earth’s surface and the air mass above it are the strongest.

For reasons meteorologists are not quite clear about, the jet stream has remained far south of where it normally is, as far south as Southern California. Normally, it would be close to the Canadian border, Wallmann said.

“Normally, it only drops as far south as southern Oregon this time of year, if even that, not all the way down into California,” he said.
The end result is that the normal high-pressure ridge that builds up over the Southwest hasn’t taken hold yet, although Wallmann said there are finally signs that Phoenix might begins to see its normal 100 degree temperatures.

“The high pressure ridge is finally beginning to form and it will slowly move its way north and west (toward us)” he said.

The other side of the coin is that after 10 months of snow (it began snowing in September in Mammoth), when summer does come it will be very abrupt.

“It will be like hitting a switch,” Wallmann said.
That will be great for winter-weary residents. Imagine not having to wear fleece-lined boots in June, or sitting out on your porch without a down coat on.

It might not be so great for snowmelt and the flooding that could accompany rapid runoff.

“At many places were we measure snow depth, there is still as much snow as there normally is April 1 (typically the highest snow depth of the year),” he said.

Normally, the snow begins to melt off after that point, giving the mountains two good months of slow, gradual warming before the June heat hits. This year, that has not happened and if the temperatures climb abruptly, as meteorologists expect, flooding is a very real concern for the Eastern Sierra.