An end to our dry streak and the answer to a weather question.

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SUMMARY

The streak of pretty, dry days will come to end for some folks today, and for all of us tomorrow. The activity that pops up this evening will be very isolated and many of us should stay dry. However, all of us should see some rain by the time Saturday comes to an end. Most of it will be hit and miss and it will be similar to those days in the summertime when you spend the day dodging showers and storms. One minute it’ll rain, maybe even come a downpour, followed by a peak of sun, rain, repeat. The front responsible for this is very slow moving but it is just enough to kick off showers and storms in what will be a very humid airmass in place around here on Saturday. Some of the storms that develop could become a bit strong, but widespread severe weather is not expected. The front clears out on Sunday and models now show a drier day in store for us. More disturbances begin moving back in here Sunday night and into the beginning of next week, bringing more shower and storm chances.

Temps look to say very mild for the next week to ten days and there continues to be no indication of widespread severe weather.

DISCUSSION

If you have outdoor plans this weekend, make sure you have a place to seek shelter from lightning. We are expecting t-storms around the area tomorrow, so lightning will be a threat. Remember, if the storm is close enough for to hear thunder, you’re close enough to get struck.

One of our WeatherTAP Facebook Followers shared a photo he took while storm chasing in Oklahoma a couple of days ago. Chasers in Oklahoma have been rather disappointed in the tornadoes this season, but that hasn’t stopped them from getting some good pictures of lightning and clouds, etc.  Lightning carries one of two charges; positive and negative. Negative strikes are the most common and are usually what you see. Positive strikes are more rare and much more destructive and powerful than negative strikes.  The photo below of a positive strike was taken by Zach Roberts. (Zach has all kinds of cool weather photography at http://mrtwister.us/).

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Back in 2013, I and some other chasers from Mississippi State were caught under a supercell that was producing numerous positive strikes. That’s unusual, but it can happen. Positive strikes are different and you know it when they’re happening. A strike would come down and, I’m not sure this makes sense, but you could hear it split the air, followed by what sounded like a cannon that would echo across the landscape. It was so bizarre! Just as we noticed a beautiful funnel cloud coming down to the ground….BOOM!!!! A lightning strike hit so close to us that it shut my cell phone off. Yeah, I’ve never gotten back into a car so fast in my life!

Lightning is a chasers greatest danger. You want to get out and take pictures but you always stand the risk of getting lightning struck, especially if you’re surrounded by flatter terrain and you’re the tallest object around (esp if you’re 6’3″ like me! ha).

Speaking of storms, we’ve not had a lot of those this spring. I mentioned in yesterday’s blog that it’s due to the unusually cool spring we had.

Back in the middle of April we saw a very unusual pattern develop that led to remarkable warming. The warming sparked some questions that I’ve gotten from folks wondering why we get storms when temps go from warm to cold, but we rarely get storms when temps go from cold to warm. That led to me writing an article for the Fentress Courier. You’ll find it below.

But before I give you the article I’ll share a bit of a Friday Funny I found, in all places, in the weather records this morning. Normally the records just state what happened and details of the event but someone got a bit clever when documenting a severe weather event in 1989 in Mineral Wells, Texas. Winds there gusted to 100 mph on this day in ’89 and “unroofed a nightclub, turning it into a “topless club.”” Clever, Mr. Record Man, very clever. haha

You all have a great weekend!

A Record-Level Warming

It is not unusual to see big temperature changes this time of year, and we know to expect storms along those frontal boundaries.

On April 17th, the temperature in Nashville soared from a morning low of 30 degrees, to an afternoon high of 80 degrees. This 50-degree temperature rise was likely the greatest one-day temperature rise in the city’s history. Here on the plateau, morning lows that day were in the upper 20s, while afternoon highs soared into the upper 60s. That is a temperature rise of 40 degrees!

With such a temperature change one might expect storms, but we only had sunny skies.

In this case, we warmed up due to dry air. Dry air warms up quickly. That’s why desserts are so hot. Clouds cannot form in dry air masses, so storms cannot form with this type of warming.

Warm-ups in the spring are often due to a warm front.  Warm air is light in weight, so the warm air with a warm front rides up and over heavier cold air here at the surface. The warm air gradually moves in, working its way from the top of the cold air, down to the surface. This is a lengthy, gradual process that gives the atmosphere time to adjust to the changes.

The cold air of a cold front, in contrast, moves in more abruptly, like a bulldozer blade, plowing into the warm air in place and forcing it to quickly rise up, where it cools in the cold atmosphere above us and forms clouds and storms. The atmosphere has to quickly adjust, and that can give us severe weather.

Soon, the battle of the seasons will be over and the victory will ultimately be summer’s. Then, we will be begging for the cool relief of a cold front.

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