Tag Archives: temperature

News, Weather

What? It’s Always Sunny (and 87 Degrees) in Seattle

Seattle Center’s fountain, Monday, May 6, 2013 (Photo: MvB)

On Monday, Seattle tied Phoenix for the hottest temperature in a major U.S. city. (Bremerton reached a sweltering 88.) As if worn out by the attempt, today the Jet City highs are expected to fall at least ten degrees short of that mark, with a cooling marine layer pressed to Seattle’s overheated forehead. KOMO’s Scott Sistek explains how we managed to bring the Phoenix-style heat:

Seattle reached 87 due to a strong east wind aloft that warms further when it carries down the western slopes of the Cascade Mountains. It’s a thermal trough pattern that brings upper 80s and low 90s on a few occasions in the summer, but in May? Seattle hasn’t had back-to-back days over 84 in May in five years and it’s never been 87 degrees this early in May (it was May 11th as our earliest 87 before.)

The University of Washington’s Probcast is still serving up what are, for mossy-backed natives, predictions of searing heat in the upper 70s throughout the week. There’s only  a ten-percent chance of it being less than 75 the next few days — but if that ten percent rolls the other way, temperatures could exceed 80. UW meteorologist Cliff Mass can’t spot any rain on the horizon until Sunday, and if rain delays that long, Seattle will set a new record for “dry days since the start of May.”

Sports-park sidebar: the Mariners, who have had good luck locating the ball recently, have a 3-game home stand against the Oakland A’s Friday through Sunday. The Sounders have a 1 p.m. match against the Earthquakes on Saturday.

Mass has also got new data for you on how much hotter it feels on pavement when the sun is set to broil. To check for icy winter conditions, Washington’s Department of Transportation has installed temperature gauges on a multitude of roads, and they don’t turn off just because it’s sunny out. One blacktop near Southcenter hit 110 degrees yesterday.

While our rivers of asphalt are baking, warns Mass, our snow-fed rivers are freezing and running high. Late-spring snow melts quickly, giving Northwest rivers icy teeth that, each year, drag earlybird swimmers and rafters under. “May is most dangerous month for drowning in Washington,” chimes in KING 5, who found the Snoqualmie River running at a nippy 33 degrees. An involuntary gasp at the shock of falling into cold water can lead to aspiration, while hypothermia can limit the ability to climb back out of the water.

News, Science, Weather

Seattle’s Cold, Wet Spring Part of National “Extreme Spring”

(Image: United States Global Change Research Program)

Remember Seattle’s cold, wet spring? Well, it wasn’t just us.

The Weather Underground’s meteorologist Jeff Masters has posted a La Niña wrap-up  for you: “U.S. had most extreme spring on record for precipitation.”

While the driest spring on record dessicated Texas, and one of the top-ten driest springs dehydrated New Mexico and Louisiana, northwesterners in Washington and Oregon were grumbling their way through one of the top-five coldest springs the region has seen in the last century or so. Washington was one of nine states deluged by the most precipitation seen in 117 years of record-keeping.

(If you factor in both temperature and precipitation, this was the fifth most extreme spring in the past 102 years, nationally.)

In contrast, our problems (a plethora of potholes, more hydroelectricity than we know what to do with) don’t look that bad:

Nature’s fury reached new extremes in the U.S. during the spring of 2011, as a punishing series of billion-dollar disasters brought the greatest flood in recorded history to the Lower Mississippi River, an astonishingly deadly tornado season, the worst drought in Texas history, and the worst fire season in recorded history.

Even for a La Niña year, this was unusual weather, not least because La Niña just wouldn’t leave. It persisted through spring, and so the “jet stream remained farther south than usual over the Pacific Northwest and Midwest, and blew more strongly, with wind speeds more typical of winter than spring.”

Thus, the South grew cotton-mouthed, while the Midwest saw cataclysmic collisions of cold and warm air, and torrential rains. (“Since global ocean temperatures have warmed about […] 1°F over the past 40 years,” writes Masters,  “there is more moisture in the air to generate record flooding rains.”)

It’s ironic that while this kind of spring makes you suspect climate change is messing with the dials, as the image above illustrates, climate change models (at least) anticipate that the reverse would happen. The trend from from 1970 to 2000, notes Masters, has been for the jet stream to weaken and move northward (270 miles north). This spring’s jet stream, in both strength and position, was an outlier.

That said, Masters points out that this isn’t your father’s global atmospheric system any more: “recent record Arctic sea ice loss” may be causing atmospheric circulation changes in the Arctic Oscillation, pushing the jet stream southward “over Eastern North America and Western Europe during late fall and winter.” And again, it’s the warming temperature of the world’s oceans that helps increase the humidity of the air above them.

So you might call climate change, for better or worse, the wind at the back of what we’ve seen this year.