I hope everyones garden has gotten a good drink the past few days. Ours certainly has, and our rain barrels have been replenished as well. Looks like we’ll need them starting Monday as some heat is coming just in time for the Canada Day Parade.
Didn’t sound like much… but I became more interested when it started talking about “Extratropical Cyclones”. These are what we get here in the Fall and Winter.
These storms, which occur near busy trans-oceanic shipping lanes, pose a significant threat to life and property for those on the high seas, generating high winds and waves up to 30 meters (100 feet) high. When they make landfall, in areas like Alaska, the Pacific Northwest, New England and the U.S. mid-Atlantic coast, they produce strong winds, high surf, coastal flooding, heavy rains, river flooding and even blizzard conditions.
Take the “Hanukkah Eve” extratropical cyclone of Dec. 14-15, 2006, for example. That storm viciously raked the U.S. Pacific Northwest and British Columbia with torrential rainfall and hurricane-force winds exceeding 87 knots (100 miles per hour) in spots. Dozens of people were injured and 18 people lost their lives, while thousands of trees were downed, power was knocked out for more than 1.5 million residents and structural damage topped $350 million.
I would love to know the statistics of the previous 2 storms that year as well…
NOAA defines an extratropical cyclone as “a storm system that primarily gets its energy from the horizontal temperature contrasts that exist in the atmosphere.” These low pressure systems have associated cold fronts, warm fronts and occluded fronts. Tropical cyclones, in contrast, don’t usually vary much in temperature at Earth’s surface, and their winds are generated by the energy released as clouds and rain form in warm, moist, tropical air. While a tropical cyclone’s strongest winds are near Earth’s surface, the strongest winds in extratropical cyclones are about 12 kilometers (8 miles) up, in the tropopause. Tropical cyclones can become extratropical, and vice versa.
Extratropical cyclones occur in both the North Atlantic and North Pacific year-round. Those with hurricane-force winds have been observed from September through May. Their frequency typically begins to increase in October, peaks in December and January, and tapers off sharply after March. They can range from less than 100 kilometers (62 miles) in diameter to more than 4,000 kilometers (nearly 2,500 miles) across. They typically last about five days, but their hurricane-force winds are usually short-lived–just 24 hours or less. Because they can intensify rapidly, they’re often referred to as meteorological “bombs.” Wind speeds in extratropical cyclones can vary from just 10 or 20 knots (12 to 23 miles per hour) to hurricane-force (greater than 63 knots, or 74 miles per hour). During their development, they can trek along at more than 30 knots (35 miles per hour), but they slow down as they mature. At their seasonal peak, up to eight such storms of varying intensity have been observed at once in both the North Atlantic and North Pacific.
Note the part in bold. I remember Mark Madryga talking back then about how the highest winds were being pushed down from above and how that was unusual… this lends some more information to that.
I learned something new today! 🙂
They talk about this in the context of QuickScat satellite imagery and how it helps forecasters deal with these complex cyclones. I recommend reading the rest of the article.
You can find a mosaic of North Pacific QuikScat imagery here… we’re at top-right. Lo-and-behold, there’s a Low twirling into the Gulf of Alaska right now. 🙂
I’ve added a link to the QuikScat imagery website to the “Satellites and Charts” link under “Animations/QuikScat”.