Page 26 - February 2016

A Winter StormWhen Flying In The Winter, Cold Temperatures are Frequently the Least of Our ProblemsFrom late November through April, fierce winter storms often assault the continental United States and southern Canada. The effects can be devastating in their cumulative effect because some of these storms are not particularly fast movers, while others, such as a Nor’easter, can develop very rapidly and catch pilots unawares. Either way, they can be very dangerous to aviators.Winter storms typically follow templates depending on where they originate. Knowing what kind of beastie you’re dealing with can help you cope with many of them, provided you have the necessary equipment on board and a workable plan for diversion. Watching the weather maps and knowing where to look for storm genesis a few days ahead of actual departure will usually allow you to anticipate what kinds of winter operations problems you’ll likely have.West Coast Winter StormsWinter Gulf of Alaska storms typically exhibit winds in excess of 50 mph and occasionally will24 • TWIN & TURBINErival the strength of hurricanes with winds as high as 100 mph. When these storms hit the west coast, they interact with the high mountain ranges that run down the coast from the Pacific Northwest to California. The mountains cause the storms to disgorge enormous quantities of rain and snow and the amounts are measured in yards annually, particularly at the higher elevations. For instance, snowfall on Mount Baker in Washington measured 1,140 inches in the winter of 1998-99.Fortunately, spotting upcoming West Coast storms isn’t particularly difficult.Let’s say you have a trip to the Great Northwest in two days. Generally, if you see the semi-permanent Aleutian Low wound up tight in the Gulf of Alaska on the current synopsis chart (if it has a very low central pressure, in other words), you should look at the prog chart for +24 hours and see if the weather guessers show a progeny of the big boy developing just to its east/east-southeast (or if they expect the Aleutian Low itself to temporarily move to the east).If there’s a deep low on the move, things are going to get interesting from British Columbia south in +48 hours and you should plan accordingly. Look at where the low is predicted to come ashore and expect a large area to be affected, stretching from the low down the coast about 500 miles. Rain, ice, snow and low IFR conditions aren’t the only problems with these guys. Turbulence is likely to be moderate to severe.Even if you aren’t headed to the Northwest, check out the situation with the Aleutian Low anyway, since, as we shall see, it’s involved in the creation of a fair amount of the storms that plague the rest of the country.Mid-Continent Winter StormsMid-continent storms are generally known by names that relate to their location of origin: the Alberta Clipper, The Colorado Low or the Panhandle Hook. Let’s take a look at the four most common types; where they typically track and their hazards to aviation.Alberta ClippersNot usually related to the Aleutian Low, Albert Clippers originate in the Canadian province of Alberta (surprise). The storm then typically tracks along the upper tier of prairie states until hanging a left and moving back into Canada around Quebec or the Maritimes. Alternatively, it oftenFEBRUARY 2016