Whenever I go to Japan, my father-in-law always brings me some place interesting.  He knows that I love earth science, so this year he took me to Mt. Bandai, the scene of a horrific volcanic eruption in 1888.  This was similar to Mt. St. Helens because it was a huge explosion, followed by mud and ash flows.  In the picture below, you can see the missing part of the mountain (lighter brown with missing vegetation).  It used to be a “conical” mountain much like Mt. Fuji.  Because of this, they called it Aizu-Fuji.  After the explosion, it didn’t look like Fuji anymore. 

This type of eruption is called a “phreatic” eruption, meaning the mountain exploded due to pressure from steam supplied from underground magma and/or heated groundwater.  The eruption also produced heated blasts of steam and gases, thickly mixed with ashes and rock fragments.  This is similar to what happened at Mt. St. Helens in 1980.  The 1888 eruption of Mt. Bandai produced a debris avalanche of 2 billion tons and the summit area rapidly collapsed down into nearby rivers to form mudflows which destroyed 5 villages killing many people.   

The mudflows and avalanches dammed up several rivers forming about 300 lakes and ponds.  Today, these lakes and ponds are a popular tourist hiking destination, as the different minerals in each lake give them different colors.  I saw one lake which was a brilliant light blue color that must have had plenty of magnesium in it.

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From the National Weather Service:

It is essential to measure snowfall (and snow depth) in locations where the effects of blowing and drifting are minimized. Finding a good location where snow accumulates uniformly simplifies all other aspects of the observation and reduces the numerous opportunities for error. In open areas where windblown snow cannot be avoided, several measurements may often be necessary to obtain an average depth and they should not include the largest drifts. In heavily forested locations, try and find an exposed clearing in the trees. Measurements beneath trees are inaccurate since large amounts of snow can accumulate on trees and never reach the ground.

If your daily schedule permits, you may wish to make a snowfall observation every 6-hours, beginning with your regularly scheduled time of observation. This is the procedure followed by National Weather Service Forecast Offices. Follow the same rules for a once-a-day observation, but the snow accumulation reported will be the greatest for the previous six hours instead of 24 hours. If you take your observations at this frequency, make sure that you clear your snowboard (or other measuring surface) no more than once every 6 hours. Record the frequency of observations during the day in the comments section of your report. Never sum more than four, six-hourly observations to determine your 24-hour snowfall total. If you use more than four observations, it would falsely increase snowfall totals.

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We’ve had a few e-mails reporting thundersnow. You’re not hearing things - thundersnow can and does happen!

From Wikipedia:

Thundersnow…is a particularly rare meteorological phenomenon that includes the typical behavior of a thunderstorm, but with snow falling as the primary precipitation instead of rain. It commonly falls in regions of strong upward motion within the cold sector of extratropical cyclones between autumn and spring when surface temperatures are most likely to be near or below freezing. Variations exist, such as thundersleet, where the precipitation consists of sleet rather than snow.

One unique aspect of thundersnow is that the snowfall acts as an acoustic suppressor of the thunder. The thunder from a typical thunderstorm can be heard many kilometers away, while the thunder from thundersnow can usually only be heard within a two to three kilometer radius from the lightning. In the United States, March is their peak month of formation, and on average, only three events are reported per year.

More from theweatherprediction.com.

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The Geo Jobe blog found this awesome geo-map of the deadly storms from a couple of days ago. Click the points, drag the map around, or switch to satellite view.

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We weather geeks keep tabs on lots of weather variables, both at the surface and aloft (the upper air information comes from weather balloons that are released every morning and evening). Even though the values below won’t mean much to most folks, there’s such a stark contrast between the atmosphere yesterday evening and this morning that I had to share.

850 millibar temperature (about 5,000 feet aloft):

7:00 pm Friday = 58 degrees F

7:00 am Saturday = 49 degrees F

1000 millibar to 850 millibar thickness:

7:00 pm Friday = 1409 meters

7:00 am Saturday = 1351 meters

Precipitable water:

7:00 pm Friday = 31.9 millimeters

7:00 am Saturday = 7.5 millimeters

Surface dewpoint:

7:00 pm Friday = 60 degrees F

7:00 am Saturday = 38 degrees F

The 1000 mb to 850 mb thickness is a good proxy for temperature; higher values correlate to warmer temperatures. We use that variable a lot during the summer months to pinpoint afternoon highs.

Precipitable water measures the moisture content of the entire atmosphere.

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The computer models are moving toward an interesting solution through next week. Long story short: there’s a fighting chance that temperatures will stay below 90 degrees from now through next week. That seems like a tall order for the end of July, but here’s how the models suggest it happens…

A big trough is over the Northeast United States today. That trough helped drive the cold front through Middle Tennessee this morning. Meanwhile, a big ridge of high pressure is building in the Central U.S. and will bring 100+ degree heat to the Upper Plains over the next several days.

Over the next few days, that East Coast trough will “cut-off” and become detached from the jet stream. Without the jet stream to steer the trough eastward, it is forecast to slowly move westward! An unusual pattern, but one that happens from time to time in the summer as the jet stream retreats northward into Canada.

The map below is valid next Wednesday. If the model verifies and that cut-off low is over the Mid-South on Wednesday, our high temperatures would only be in the 80s and there would be some clouds as well as the chance of a few showers. We’ll have to wait and see if the models can duplicate this solution over the next few runs, but it would be nice to put-off the inevitable summer heat wave for another week.

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The map below plots upper air data from around 5,000 feet. There’s a weak low pressure down to our southwest, hovering over the area between Arkansas, Louisiana and Mississippi. Winds blow counter-clockwise around low pressure, so we should see southwest breezes aloft the next couple of days. That will increase the amount of moisture available for thundershowers on Tuesday and Wednesday afternoon. No shortage of mild nights, muggy days and afternoon thundershowers over the next couple of days, but we think less humid weather could arrive just in time for the weekend. We’ll watch that through the week and keep you posted.

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June 24-30 is Lightning Safety Week. In 2006 there were 47 lightning fatalities in the United States, and 246 lightning-related injuries. Over the last 30 years, the U.S. averaged 66 lightning fatalities annually. You might be surprised to know that lightning kills more people each year than tornadoes; flash flooding is actually the number one weather-related killer.

Tennessee is no stranger to thunderstorms with vivid lightning, especially each afternoon this time of year. A bolt of lightning is only the width of a pencil, but can be four times hotter than the surface of the sun (each bolt can approach 50,000 degrees Fahrenheit). If you can hear thunder, you’re close enough to be struck by lightning…even if it’s not raining overhead. During a thunderstorm it’s best to head indoors, and stay there for 30 minutes after the last rumble of thunder.

Tennessee is high on the list of lightning strikes per square mile (according to the National Lightning Detection Network, courtesy alabamawx.com):

1. Florida 26.3

2. Louisiana 21.1

3. Mississippi 18.4

4. Alabama 16.5

5. South Carolina 14.8

6. Tennessee 14.4

7. Indiana 14.3

8. Georgia 14.2

9. Oklahoma 13.8

10. Missouri 13.7

Click here to view national lightning strikes over the last two hours.

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Davis talking to Santa Maria School in Tokyo.

First of all, I’m glad to see that some of you have gotten some rain Tuesday afternoon and evening and over the weekend. Not everyone got some, and we need more. As Lisa says below, get ready for “More Dry, More Heat”.

While In Tokyo for part of the summer, my daughter has been able to enroll in the summer session at Santa Maria, an English speaking school. While they were studying weather in science class, she told everyone that her daddy is a weatherman back in Nashville. The teacher asked me to come talk to her class. We especially talked about typhoons (hurricanes in the west Pacific) and earthquakes. They are quite prepared for earthquakes. The building is re-enforced with steel beams and each child has a helmet under his or her desk and rigid instructions on what to do. I want to send out a special thanks to Mrs. Graczyk and Ms. Ilx for inviting me.

That was quite a long distance school visit. Think I can hand in the mileage on that one?

Click to enlarge.

Another interesting tid bit. Last week we went south to an area called Gifu to see an ancient form of fishing called Ukai where the fisherman use birds (cormorants) on leashes to catch the fish. They dive underwater, catch fish in their mouths and are pulled back to the boat where the fisherman retrieve the catch. This started 1300 years ago, and today is only used to show the tourists the ancient tradition. Read about it by CLICKING HERE.

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Justin talked about some of the smoke from the Georgia/Florida wildfires reaching as far north as middle Tennessee in a blog post earlier this week.

The Huntsville National Weather Service office has issued an in depth look at the smokey smell and haze which has made it this far north. It is worth the read!

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