Day 19: Riding the Wave Train
After last week was relatively quiet, albeit cold in places, this week is promising to be very active in terms of low pressures, upper-level lows, and precipitation. Just look at the 5-day precipitation forecasts from the Hydrometeorological Prediction Center posted from a few days ago! One reason for the wet, stormy weather pattern is the number of storm systems (an organized collection of low pressure/height throughout the atmosphere) that are identifiable on water vapor.
In the image below, five upper-level lows are circled – two in yellow and three in red. I’ve used two colors to distinguish between upper-level lows that have aided in the recent west coast deluge (red) and those that haven’t (yellow). (Author’s note: It is possible to identify additional upper-level lows, vorticity maximums, and/or short-wave troughs; however, I only circled those “easily identifiable” on a single image – not a loop.) When analyzed on weather maps, upper-level lows often look like waves with crests (ridges) and troughs (troughs). When several of these waves line up one after another, similar to box-cars on a train, meteorologists call it a wave train. Hence the name of this post.
The eastern (rightmost) upper-low circled in red is currently aiding the development of showers and thunderstorms across the southern plains and will affect a large portion of the central United States on Wednesday. In fact, Ice Storm Warnings are in effect for a good portion of Iowa and a chance of severe weather is possible across a large portion of the north central Gulf Coast states.
The middle of the upper-lows circled in red moved onshore in southern California this afternoon and resulted in at least three tornado reports along the California coast. The western (leftmost) upper-low circled in red also came ashore earlier today with a myriad of severe weather associated with it. I’m uncertainly, but one of these two upper-lows was responsible for a wind gust of 93 mph recorded at Newport Beach Pier.
The parent long-wave trough (giant upper-low) responsible for these short-wave troughs (smaller upper-lows) will remain off the west coast for the next several days. When this long-wave trough begins to move eastward, a decent severe thunderstorm threat will be possible across a large portion of the southern United States.
About Patrick
Patrick Marsh is a Ph.D. candidate at the University of Oklahoma's School of Meteorology. He earned a Bachelors of Science in Mathematics and Physics (cum laude) from the University of Arkansas in 2005 and a Masters of Science in Meteorology from the University of Oklahoma in 2007. In addition to working on his doctorate, Patrick serves as the National Severe Storms Laboratory Liaison to the Hazardous Weather Testbed where his research interests lie in working with operational forecasters, data mining, data visualization, and all things high-impact weather. For more about Patrick's work, check out his complete CV!
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