Southern Idaho Weatherisms


By KMVT News


I've lived in several different regions around the U.S. and in every region I've heard locals say "If you don't like the weather right now, just wait five minutes." In the regions other than Southern Idaho people say the phrase in a sarcastic and exaggerating kind of way. However, here in Southern Idaho people are serious when they say it.. and after living here for two years I'd have to agree. A major reason for the sometimes very erratic weather around here are the variations in elevation from city to city. 


Having said that, I've noticed three weather related things that happen much more frequently here than anywhere else I've ever lived. 


The first of these three things is virga. Virga is an observable streak or shaft of precipitation that falls from a cloud but evaporates before reaching the ground. Here's an example of what virga looks like:



The reason virga happens so often around here is because this is a high desert climate that features low humidity and high temperatures in the summer. Those two things can cause rain to evaporate shortly after its release from a cloud. Virga usually happens in the summer with rain but snow virga can happen as well. Sometimes you'll see "green" on radar which (usually) indicates rain, but the ground will be mostly or even completely dry. That's a good indication that virga is taking place. 


The second weather phenomena I've noticed is called a temperatures inversion. In a normal atmosphere the temperature decreases as altitude increases. In an inversion the temperature decreases much less than normal as altitude increases.



This creates a roof or "cap" which will keep air from rising above the inversion. A temperature inversion can create very impressive morning fog. The ground cools much quicker than the air and during an inversion the cooler air is close to the ground. If the air near the ground cools to its dew point temperature fog forms. The fog is then trapped under the inversion and will not burn off until the sun comes up or the wind mixes out the inversion. This happens around here because heavy cold air is able to settle into the Magic Valley as warm air passes over the mountains above. 


Finally, the third thing I've noticed around here are Kelvin Helmholtz clouds. These clouds look like rolling waves:



When two different layers of air move at different speeds the top rolls over the bottom layer. When clouds are present the movement is visible. We see these clouds around here because this is an active wind region. 


I'm sure you already knew that Southern Idaho is a cool and unique place to live. But, now you have three more (weather related) tid bits to point out to visitors as they swing through our neck of the woods!


Meteorologist, Nick Kosir

KMVT and FOX 14



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