MM’s Fri WX Blog for Apr 16

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Temperature Experiment Update

Those of you who saw my post last night know what this is all about (ha). My thermometer that was placed on the ground and out in the open field recorded a low temperature of 30 degrees. The temperature under the trees got down to 36 degrees. My official, NWS standard, thermometer recorded a low of 34 (out in an open grassy area and 5 feet off the ground).

So, the official low at my house for last night was 34 degrees, but it was 30 degrees on the ground out in open fields. That’s why there was frost this morning in the open areas. That is the best example of frost I could have hoped for! ha

Friday Funny

Headlines 

Today is the 23rd anniversary of the one and only F-5 ever recorded in TN

Showers return Saturday

Quiet weather continues

Meteorologist Mark’s Wx Vlog 

48-Hour WX

48-Hour Precip Forecast

Five-Day Forecast

Daily Forecast Summary

Today: Partly cloudy and pleasant.

Saturday & Sunday: Partly to mostly cloudy, with a chance for showers.

Monday: Mostly sunny and pleasant.

Tuesday: Partly cloudy, with a chance for showers.

Meteorologist Mark’s 5-Day Wx Concerns

Meteorologist Mark’s Wx Discussion

The pattern continues to look quiet, with no severe storms in sight. That is a bit unusual for this time of year. I don’t even see flooding rainfall in sight. In fact, I wouldn’t even be surprised to see us drop back into the deficits for rainfall, thought that is likely to not last for long, nor is it likely to become an issue. There are indications that the pattern will become much more active in 8 – 10 days.

Almanac for Yesterday

Solar/Lunar Data 

On This Day in Wx History

1998- A major tornado outbreak spawns 13 tornadoes across Middle Tennessee, beginning early in the morning and continuing through the afternoon. A massive, nearly 1-mile wide F-4 tornado kills 3 in Wayne County, and another F-5 tornado heavily damages the Deerfield area of Lawrence County. An F-3 tornado moves through downtown Nashville, the first tornado to hit the downtown area in more than 65 years. Baseball-size hail is reported northwest of Ashland City (Cheatham County), damaging 35 to 50 homes. This is the 9th largest tornado outbreak in mid state history.

This is the one and only F-5 ever recorded in the state of Tennessee.

A Year Ago Today

65 Days until Summer

Yesterday’s National Temperature Extremes

High:  101° at Rio Grande Village, Texas

Low:   at Vernal, Utah 

Today’s National Weather Hazards

Flooding rainfall will threaten portions of eastern Texas, all of Louisiana, southern Mississippi, and southern Alabama today. Elsewhere, heavy snow will fall across the mountains of New Hampshire and Vermont. Accumulating snow is expected across the Rocky Mountains of Wyoming and Colorado.

Tomorrow’s National Weather Hazards

Accumulating snow continues across much of Colorado, as well as across northern North Dakota.

Drought Monitor

The drought monitor is updated each Thursday.

NASA Nerdology 

The Mars Insight rover tweeted, “Winters are tough on Mars and my power generation is low, as expected, but no need to panic. My energy levels will decline through late July, but as I get further into spring, they’ll improve. I’m still quite busy working to bury my seismometer cable and collecting quakes data.”

I love “earth”quakes on Mars because we get to call them Marsquakes. ha!

You all have a great day and keep lookin’ up!

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Weather Nerd Post about Frost

So, I put a thermometer out in the middle of an open field to see the temperature difference tonight. I expect it to be impressively different than my more sheltered thermometer closer to the house.

To understand frost you need to know a little about temperature. During the day, the sun heats the land and the land then heats the air above it. At night, when the sun is gone the land loses heat quickly. In fact, the land loses heat faster than the air above it does. This creates colder air nearest the surface. So, if you’re thermometer is several feet above the ground it will be several degrees warmer than the air at the ground.

Air at night tends to be damp and moisture holds on to heat. It’s like warm, humid nights in the summer. That moisture really holds on to the heat. In the desert, the dry air loses heat quickly, causing hot afternoons and cold nights. No moisture, no heat retention in the air.

Frost forms at 32 degrees. Period. Yes, your thermometer says 35 degrees but if your thermometer were at ground level it would be 32 degrees (if you have frost).

That colder air also hugs the ground and eases toward lower places. Cold air is heavy and likes to gather in the lower-lying areas of fields. That’s where you see frost on nights like tonight. For that reason, we see frost quite often around our pond out in the field (lower area).

Keep in mind that the winds must be calm for all this to take place. Wind stirs up the air and causes temperatures to be more evenly dispersed. Skies also have to be clear. Clouds hold in the day’s warmth and cause us to be warmer.

So, my thermometer out in the field is unsheltered and the heat is radiating nicely from the ground. That thermometer currently reads 38 degrees at 8:25! My thermometer under the trees reads 46 degrees. And that’s how you end up with scattered frost across the fields by morning.

Thanks for letting me be a total nerd for this post (ha!).

Frost Tonight

While widespread frost is not expected tonight, there could certainly be scattered areas of frost. This is especially true for open, unsheltered areas. If you have any especially tender vegetation that you want to protect, I’d certainly protect it tonight.

Overnight lows are expected to drop into the low to mid 30s. The dewpoint is already 29 degrees, which means temps could easily drop into the lower 30s tonight.

A frost advisory is currently not in effect for Cumberland or Fentress counties but there are advisories just to our east in Morgan and Scott counties (issued by NWS Morristown). All the counties in eastern Kentucky are under frost advisories too. I’ve often seen the Nashville NWS wait until we’re late into the night before issuing a frost advisory for us. That doesn’t help you much if you had intended to protect something before going to bed.

Dogwood winter is right on schedule! You all stay warm!

MM’s Thurs Wx Blog for Apr 15

Headlines 

Scattered frost likely tonight

Dogwood winter is here

Showers return by the weekend

Meteorologist Mark’s Wx Vlog 

48-Hour WX

48-Hour Precip Forecast

Five-Day Forecast

Daily Forecast Summary

Today & Friday: Partly cloudy and cool. Scattered frost by Friday morning.

Saturday: Scattered showers.

Sunday: A chance for showers.

Monday: Mostly sunny. Continued cool.

Meteorologist Mark’s 5-Day Wx Concerns

Meteorologist Mark’s Wx Discussion

One of the many “winters” of spring are upon us! Dogwood winter is indeed here. I’d protect any tender vegetation you may have tonight, just to be safe. The pattern we are in continues to feature cooler days and a more stable atmosphere. This means that severe weather remains out of sight.

Almanac for Yesterday

Solar/Lunar Data

On This Day in Wx History

2001- High winds topple the steel radio tower for WGNS-AM. The tower was built in 1946, and stood 328 feet tall. It was Murfreesboro’s tallest structure. Damage to the tower is estimated between $250,000 and $500,000.

A Year Ago Today

66 Days until Summer

Yesterday’s National Temperature Extremes

High:  100° at Falcon Lake, Texas

Low:   -2° at Burgess Junction, Wyoming  

Today’s National Weather Hazards

Severe thunderstorms are possible across central Texas today, with large to very large hail being the main threat with any storm. Heavy snow is expected across the mountains of southern Vermont. Heavy snow is also expected across southeast Wyoming, western Nebraska and northern Colorado. Lighter amounts of snow will fall elsewhere across the Rockies. A wildfire danger expands across much of New Mexico and eastern Arizona, thanks to low humidity and gusty winds.

Tomorrow’s National Weather Hazards

Flooding rainfall is expected across Louisiana and southern Mississippi on Friday. That threat also includes the Mobile, Alabama area. Elsewhere, accumulating snowfall continues for parts of the Rockies and Front Range.

Drought Monitor

The drought monitor is updated each Thursday. This is the latest update!

This is last week’s map, for comparison.

NASA Nerdology 

NASA’s Perseverance Mars Rover tweeted, “I’m getting ready to do some local science at the Mars’ Helicopter lookout point, while we await the first flight. I’ve been imaging some of the local rocks. Take a look for yourself!”

How cool is that pic!? To see more images, just visit https://mars.nasa.gov/mars2020/multimedia/raw-images/. The chopper is set to take flight soon, though after two delays a specific date has not been set.

You all have a great day and keep lookin’ up!

Be sure to follow the blog by finding that “Follow” button in the lower right corner of the screen. Thank you!

Please feel free to “Follow” me on Social Media!

The “Meteorologist Mark” app is coming soon! Stay tuned! 

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