Friday, May 29, 2015

The Spring and Summertime Thunder Cell

So I first have to start out by saying I've absolutely fallen in love with the Tri-Cities. Some of my friends felt sorry for me when they learned I was soon going to move across the state to this desert region. They instilled this dread about moving to a smaller town so I was sure I would have to make treks back to the big city if I needed to go shopping or wanted to hit a young bar scene. But boy was I wrong about everything (maybe except the bar scene). I still have much to explore here but I have been blown away by what’s offered. Everything is within a 15 mile radius of me and I was fortunate enough to pick an apartment in the heart of Richland where a running trail to an overhauled park, fresh food market, department stores and the mall, and a quick hike through the rolling hills are all but a quick 3 minute drive from me.

A thunderstorm over west Richland around 7pm on Memorial Day
The main reason why this place is my favorite, however, is because of the climate. Yeah, I lived in Seattle my entire life, where it’s been awarded the cloudiest large city in the US. I’m used to grey skies, that mild weather, and a lot of moisture. It is another world of blue sky over here in the Tri-Cities and recently it’s gotten close to 90 degrees. I’ve been told it’s “not even hot out, Kelley…” Good, lord. I’m a fan of it all though because I’m able to take runs down my trail with the beautiful blue skies and a sunset in the distance every night if I want to. The other awesome weather phenomena here are the abundance of isolated thunderstorms. I mean, holy crap!!! We’ve been getting a ton lately and they’ve been making me shake my first at the sky because they are so freaking hard to forecast.

Captured on the big screen!

I had my first weather broadcast over Memorial Day weekend and I was really shaken up about forecasting thunderstorms correctly. I realized that if you can notice any chance of thunderstorm activity, you can really only talk about it's probability of occurring. It's so hard to pinpoint down to the minute when and where they may occur like you can model with precipitation these days.

UW WRF CAPE 15hr forecast valid 5/29 @8pm

A common indicator used by meteorologists for thunderstorms can come from a calculated number called the Lifted Index (LI). The LI is pretty simple and basically compares the temperatures of two different parcels of air at different levels in the atmosphere which help to describe instability. Another good indicator of thunderstorms can come from the Convective Available Potential Energy (CAPE) forecast. This value basically describes the amount of energy that a buoyant parcel of air has as it's convected up. A lot of energy means potential for thunderstorms. To the left is the 12km UW-WRF model that has forecasted CAPE over Washington tonight at 8pm. Just look at our area, all the pink and darker blue, so much energy is available there.

I pulled the radar just now to see what our current weather looks like. There are storms out there, look at that nice isolated thunderstorm right outside of Pasco now. Also the high reflectivity (the red spot) means there is a lot of large rain flying around inside the cell. There's probably lightning going off over there  and around the region. A few showers near Yakima are out there as well and on their way to Ellensburg. Some active weather and heavy thunder cells up north nearing on Spokane too.

The Yakima area tends to get a lot more thunderstorms around them because they will see that cold air off of the Cascades immediately. However, that doesn't mean we in the Tri don't get these thunderstorms too. Specifically, these are called air mass thunderstorms and are common in the late spring and summer time in an area where the surface of the earth gets incredibly hot. As cold air moves over the hot surface, the atmosphere becomes unstable and convection occurs which saturates the air (creates clouds) and revs up into small scale, highly powered, thunder, lightning, and hail producing storms. The incredible thing about them is that they are only about 5-10 km wide, so you can look to the right and see blue skies and look to the left and see a dark cloud with lighting in it. These storms are often isolated, as in they roam alone. And..! The will only last about 30 minutes or so. These storms tend to die out at night since they loose their fuel which was the warm earth surface via daytime heating. Late afternoon to the evening is an ideal time to spot these guys. In the weather center, all we can do is track these storms once they're out there and do the best to warn those of any hazards, like a flash flood occurring as a result of the heavy rains. I'm back this weekend in the weather center so lookout for my forecasts where I'll try to elaborate on thunderstorms! Thanks to everyone for all the support, it has been so great to hear.

Until next time, I'm Meteorologist and Storm Tracker Kelley Bayern for KEPR Action News. 

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