Let’s talk about Long waves and Short waves…. Thanksgiving Forecast….
Hello Weather Watchers!
Many of you have noticed and commented that it seems as though precipitation develops East of Kansas.
You are exactly correct and the reason for this is the placement of Longterm Long waves known also as Rossby waves.
Rossby waves help to transfer heat from the tropics toward the poles and cold air toward the tropics trying to return the atmosphere to balance. They also help locate the jet stream and mark out the track of surface low pressure systems. The number of long waves at any one time varies from three to seven though it is typically four or five.
Their slow motion often results in fairly long persistent weather patterns. For example, locations between the trough and the downstream ridge can experience extended periods with rain or snow while at the same time 1,500 – 2,000 miles (3,000 – 4,000 km) upwind and/or downwind the weather is very dry.
This often can lead to a misconception where one assumes the weather he or she experiences is typical everywhere. That is simply not true. If one place is receiving cooler weather and/or flooding rains over a period of several days to weeks, then there are some other places where the weather is warm and dry for about the same period. It all depends upon the location of the long waves relative to the observer.
The current location of the Long Waves that affect the US weather appear to be in the Pacific, West of California, and the other over the US Midwest.
This is the reason why storm systems intensify just to our East.
Additionally there are short waves or pieces of energy” that move in between and through these Long waves.
A “piece of energy”, “vort max” (or “vorticity maximum”), “pocket of cold air” (or “pocket of energy”), “upper level disturbance”, “upper level energy”, or just “shortwave” are some of the slang terms for waves with a length of less than 3,700 miles (6,000 km).
They are embedded within the long waves and move much faster and through the long waves. Unlike the slow movement of long waves, short waves move east (down stream) on average of 23 mph (20 kts, 37 km/h) in summer and 35 mph (30 kts, 55 km/h) in winter. This motion causes long waves to distort and change shape such as deepening long wave troughs and flattening long wave ridges.
Hopefully this gives you a better idea about how our atmosphere works- It’s all connected!
BIG WARM-UP then a cool down and Windy…
Friday we warm up BIG with highs approaching 80 in South Central KS. A piece of energy dives SE Friday from the intermountain West which drags with it a Strong but dry Cold front. NNW Winds will gust to 45mph late Friday night into Saturday as Strong High Pressure moves into the area placing us in a very chilly position by Saturday night early Sunday.
Thanksgiving looks PERFECT with highs in the mid 60s West to mid 50s East with very light winds.
We do think that after the Thanksgiving Holiday we should begin to see a favorable pattern change which might bring us some needed moisture….we are looking at. 10-17 day active run that should begin around the week after Thanksgiving. WE SHALL SEE….
Questions, please ask!!