Summer Heat and Bad Air

Wow, what a beautiful day!  Gorgeous blue sky and low humidity. What a keeper!  Tomorrow will be about the same.  This warmer air can come with a price…bad air.  The first Air Quality Alert of the season has been issued for tomorrow.  Changes are coming later in the week to mix it up, Dan Thomas had more on that  in his earlier blog, click here.


But back to the Air Quality Alert for tomorrow. An alert is issued when the amount of ground level ozone increases.  Tomorrow is a Code Orange Day which means the air quality will be dangerous for sensitive groups. Those sensitive groups include people with lung disease including Asthma, active adults and children are most affected by ground level ozone. If this is you or a loved one, consider limiting or rescheduling strenuous outdoor activities until the air quality improves. Pollution levels tend to be lower in the morning and evening.


There are actually some things we can all do to reduce air pollution.

LEAVE THE CAR PARKED – Share a ride to work, bike  or use public transportation. Bring your lunch, or walk to lunch instead of getting in your car.

DRIVE SMART – Combine errands, skip the drive thru, limit engine idling, and avoid rush hour.

PUT A HOLD ON SOME BACKYARD ACTIVITIES – Avoid using gas-powered yard equipment, and save the grilling out for another day.

LS summer_ozone

Warm, dry air is conducive for pollutants to accumulate in the air. Air Quality Alerts are issued because of predicted high levels of ozone, fine particle pollution (PM2.5), or both.
The highest ozone levels usually occur from 2 p.m. to 7 p.m. in Middle Tennessee, so reschedule or cut back on outdoor activities, particularly during these times. But,
unhealthy levels of PM2.5 can occur at any time during the day. People with heart and lung disease, older adults and children are particularly at risk from exposure to fine particles.

Humidity levels will rise later in the week and the chance of rain will increase.  Both will help wash some of the pollutants out of the air.

Join me for a weather update tonight on Channel 4 News at 10pm.

Lisa Spencer

posted 9:20 PM

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New Week Means New Weather Pattern!

With the unofficial start to summer now just a week away, it’s appropriate we transition to more of a summery set-up!  That’s what we’ll be doing over the next 48 hours!


What that means is we’re to expect temperatures several notches above average, increasing humidity, and just isolated showers and thundershowers around the peak heat of the day.

Outdoors now, as of 3pm, our temperatures are running 3-5 degrees above what’s typical for mid-late May…


Sunshine continues to rule, with just a few high clouds rolling in over the western horizon…


If you have evening plans, there’s no concern for rain.  The effects of high pressure in our neighborhood are still too strong.  Notice the high clouds increasing by that time…

DT Skycast Evening

Tomorrow, the same system making all the clouds (and rain as well) over Kansas and Oklahoma will slide into Tennessee, so during the afternoon & evening, we’ll have just the slightest shower/storm chance.  See below for how little FUTURECAST is painting in terms of rain for us…

For the rest of the week, count on only slightly better chances for daytime heating triggered showers & thunderstorms….and more HEAT!  Coming up today on Channel 4 News, beginning at 4pm, we’ll get more specific on the rest of the week and have all you need to know for making outdoor plans for this Memorial Day weekend!



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May 23: Feeling Like Summer, Daily Links


The new work week is off to a good start, at least in terms of weather.  Abundant sunshine will help push temperatures well into the 80s this afternoon:
Those temperatures are about 5 degrees above average, but the humidity won’t be a problem…at least, not yet.

The overall weather pattern this week will bring a summer-like air mass to the Midstate — warmer temperatures and increasing humidity will be very noticeable by Wednesday:
The jet stream will mainly flow southwest-to-northeast across the middle of the country, a pattern that will lead to several consecutive days of severe weather in Tornado Alley.  As the warm and muggy air settles into our neck of the woods, our chances of spotty thunderstorms will increase — most of our rain chances will be in the typical summertime 20-30% range:
One of the forecast models tries to bring scattered showers and storms into the Midstate already tomorrow afternoon and evening…
…but I’m not convinced of that scenario.  The humidity will still be fairly low at that point, and the dry air should eat away at any rain that tries to make a run towards us.  Still, this is the kind of weather pattern that can throw some curveballs at us, so we’ll keep a close eye on things.

The best chance of showers and storms is Thursday, as a little ripple in the upper levels of the atmosphere passes overhead.  It’s a little too early to give you a specific when/where, but the regional radar simulation shows some much-needed rain:
We’re still well behind the year-to-date average rainfall, so we’ll take what we can get!

An early look ahead at the Memorial Day weekend shows a continuation of the summer-like weather pattern…which seems appropriate for the unofficial beginning of summer:
We’re still several days away from even the first day of the holiday weekend, so stay plugged into the forecast for potential changes throughout the week.



No space stuff today, but plenty of weather links and other assorted nerdiness…

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Weekend Weather and Events

This was a soggy Friday to say the least. But we did get some much needed rainfall at Nashville International, 1.25″.  We are still about 1.50″ below average for May, but that was a help.  Parts of the mid state are in a moderate drought. It’s having a big impact on the Cumberland Basin including Percy Priest Lake. Learn more here. If your weekend includes a trip to the lake you might want to check out that story.


A disturbance passing by tonight will bring a few showers, nothing significant, most locations will be rain free overnight.  Some fog will develop though. Saturday morning there could be some drizzle with that fog but things will get brighter as the day goes on. That is not to say that it will be without some rain.  Some showers are likely in the afternoon, but they will be passing.  It won’t be a washout like today.

There are many events going on tomorrow.

8 AM The Titans 5K run gets underway at Nissan Stadium

8:30 AM Tour De Nashville, the bike ride starts at Morgan Park

9 AM The Lung Force Walk will be at Public Square Park, Rudy is the emcee and Snowbird will be there shaking his tail feathers


10 AM Bellevue Picnic will be held at Red Caboose Park.  After being downtown, Snowbird will be there about 11 AM with more tail feather shaking.


With all of these events, there is a chance of a passing shower, but I think it will be dry most of the time.  Here’s a snapshot of what Futurecast is depicting.

This is also a great weekend for skywatchers.  Saturday’s full moon is the Blue Moon.  No, it’s not actually blue but it’s the third of four full moons to occur between the March equinox and the June solstice. This is an older definition of the Blue Moon, according to With this definition, the Blue Moon occurs every 2 to 3 years.

Blog blue_moon

Image from  by Robert Couse-BakerEnter a caption

In addition, this is the weekend for a conjunction that includes the moon, Mars and Saturn. The redish star Antares joins the crowd from 550 light years away as well at the heart of the constellation Scorpio. On Saturday they form a box in the eastern sky a few hours after sunset.

Blog Sunday 5 21 16 Conjunction.

Mars continues to shine big and bright ahead of opposition at 6:10 AM on Sunday morning. Oppostion is when the Earth will pass between Mars and the sun

Blog Sunday 5 22 16 Conjunction

The Red Planet will shine bigger and brighter than any other time in the past two years as it approaches the closest point in its orbit to Earth.

No fancy telescopes are needed. You’ll be able to spot the Red Planet with the naked eye. Mars and Earth travel at different speeds in their elliptical orbits around the sun. While they line up every 26 months, this will be Mars’ closest orbit to Earth since 2005! The Hubble Space Telescope will take advantage of this great viewing opportunity and turn its gaze toward Mars to capture a new, detailed snapshot of the Red Planet.

Blog Mars-2016-Hubble-e1463679260844

New image of Mars taken by the Hubble Space Telescope

By the way, Sunday’s weather should be fantastic for anything outdoors, mostly sunny with a high near 80 degrees.  That trend continues through Monday too.  Later next week we start working on the rainfall deficit again.  Rain and thunderstorms are expected especially Wednesday and Thursday with the next passing disturbance.

Happy weekend!

Lisa Spencer

Thanks to the folks at NASA and for their space information and images.



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Soggy Friday….Hope for the Weekend!

It’s been a soggy Friday north, south, east, and west!  The only exception to that is over far southeastern Middle Tennessee….where rain is approaching.  The latest view of 4WARN Live Doppler Radar shows where the rain is now (as of 3pm).


The back edge is nearing the I-65 corridor and should be through Nashville shortly.  The Cumberland Plateau will have to wait until 7pm or so for it to clear there.  Check out the latest FUTURECAST which looks good, all in all (by good I mean mostly accurate).  Notice that once the main batch of rain moves out, a stray shower or two will still be possible…

Temperatures are well below average again today because of the rain/clouds.  This is where we stand as of 3pm…


Notice from the latest cloud view (via satellite), there are some sunny breaks developing west of Nashville!


Our WeatherBug camera view from Moore Magnet Elementary in Clarksville shows how there, it’s brightening up nicely!


Over Nashville though, rain continues…but I DO expect some sunshine before sunset.  In fact, a good many of you will see some breaks in the clouds!


Tomorrow, rain looks much less likely.  BUT….it’ll still be here and there.  In the morning, expect widespread low clouds, drizzle, mist, & fog.  By late morning, the clouds should lift and begin to break up.  Some early afternoon sunshine will work together with the system I’ve encircled below (that will be nearing our area by that time) to produce a few light, brief showers.  Most of us won’t see one of those, so I kept the rain chance at just 30%.


Sunday looks so much better!  Coming up today on Channel 4 News, beginning at 4pm, we’ll tell you all you need to know about the second half of the weekend, the building heat next week, and have your first look at the Memorial Day weekend!


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May 20: Rain Today, Showers Tomorrow, Beautiful Sunday, Daily Links


A bit crunched for time this morning, so we’ll keep the weather discussion short-but-sweet.  Rain is likely through much of today.  This loop of the HRRR model had a good handle on the pre-sunrise rain, so I’m relatively confident in how it depicts the rain’s progress throughout the day:
That particular model shows the heaviest rain moving east of I-65 by mid-afternoon, and off the Cumberland Plateau just after sunset.  Total rainfall amounts look to be most substantial west of I-65 (that’s quite a change from yesterday’s forecast data):
A few stronger storms are possible this afternoon, but the Storm Prediction Center hasn’t outlooked us for anything other than “general thunderstorms.”  (That’s their way of saying, “don’t worry about it.”)

The rain will take a break tonight, but more spotty showers are possible Saturday, especially east of I-65.  As I said yesterday, don’t cancel any outdoor plans, unless the tiniest bit of rain would ruin those plans.  We’re talking about very light, very brief, splash-and-dash kind of showers:

We’ll dry out Saturday night, and Sunday looks nothing short of perfect.  Yeah, I said it: PERFECT.  You got complaints about Sunday’s weather, take ’em elsewhere:
The warming trend will continue next week, but the humidity won’t be noticeable until Wednesday, when it will be substantial enough to fuel some scattered storms which will continue into Thursday.



Last batch of nerd-links for the work week…

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Memorial Day Weekend….BEWARE!

In just over a week, grills will fire up and people will head to area lakes in droves to celebrate the Memorial Day weekend!  If you’re one of the many who will be out on a lake, BEWARE!  This is what Percy Priest Lake looked like today (courtesy of the U.S. Army Corps of Engineers)…


Lake levels are exceptionally low because of a developing drought throughout much of the Cumberland River Basin.  Here are today’s stats for Nashville International Airport.


The U.S. Drought Monitor produces a weekly drought status product for the entire country, updated each Thursday.  Below you’ll find today’s.  Notice that much of the Cumberland River’s watershed is in “Moderate Drought” status.


Here’s the drought update for the rest of our area….


SO….the Corps advises swimmers and boaters, especially, be extra careful when out on Middle Tennessee lakes next weekend!  The chance of getting snagged or running aground are higher than typically is the case for the unofficial kickoff to summer!

Some related good news is that rain IS expected tomorrow.  The timing is broken down here….


For more specifics on the timing for your area, take a look at these FUTURECAST panels.

Because of the clouds and rain tomorrow, it won’t be nearly as warm as today.  This is what we expect for highs around the region…

DT 4 RPM 12KM Temperature2

Rain totals (by Saturday) should be around an inch for most….with higher amounts right where we need it most!

DT RPM 12KM Rainfall Zooms

Isolated light showers are possible on Saturday, too, as noted above.  Be sure to tune in tonight to Channel 4 News at 10pm.  Lisa Spencer will share her latest thoughts on that.


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