May 22: Memorial Day Weekend, daily links


After a downright chilly start this morning, a nice warming trend today will lead us right into the Memorial Day weekend…

Summing up each day in GIF form, beginning with Saturday…”bravo”:

Sunday…”approving nod”:

Monday…”tepid applause”:

Saturday looks pretty much flawless — just a few clouds, and warm temperatures with low humidity.  Sunday’s very slight storm chance will mostly take shape near the Tennessee River, and even there the storms will be more “miss” than “hit.”  Futurecast for Sunday afternoon isn’t overly impressed with our rain chances:

Monday will bring higher humidity and a better chance of midday and afternoon scattered storms — once again, the highest chance will be in the southern and western portions of the Midstate.  As I’ve said all week, don’t cancel any outdoor plans…just plan on being flexible and ready to adjust if the need arises.



A little nerdy reading material to hold you over this weekend…

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May 21: Cloudy and Cool, Warmer Weekend, Links


Not much to say about today’s weather, other than…[yawn]

Clouds will linger most of the day, keeping a lid on any potential warm-up today.  If we get a little sun to peek through the clouds late this afternoon or this evening, we’ll warm up to the upper half of the 60s.  In general, I’ll be fighting to not do this at my desk:

But hey, the holiday weekend is almost here, so:

We’ll start warming up tomorrow, with highs in the upper 70s.  That warm-up will continue into the weekend, but our midday and afternoon storm chances will gradually increase as well:

I’ll repeat what I’ve been saying on the air: don’t cancel any outdoor plans based on those rain chances.  It will be our typical summertime pattern of some hit-and-miss storms during the warmest part of the day, which usually doesn’t add up to a washout.  Just be flexible and ready to adjust based on whatever Mother Nature throws at you.



We’ll start with a non-science link before diving into some nerdiness…

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May 20: Afternoon Storms, Daily Links


We had a beautiful sunrise this morning…if you weren’t up that early, here’s what the pre-dawn hours looked like over downtown Nashville:

However, the weather won’t be ideal all day — we’ll see increasing clouds by noon, and increasing rain chances this afternoon into this evening.  As I usually do, I’ll show you some Futurecast snapshots of what we expect the radar to look like this afternoon, but first a little background…as I’ve mentioned before, we have a few different versions of the computer models we can feed into Futurecast.  One of the ways we evaluate which one to use is based on how well they initialize — that is, how well they depict what’s already happening.  This morning’s version of the RPM model initialized very well — check out what it showed for 7am, compared to the regional radar view just after 7am:

That kind of agreement between model and reality makes me reasonably confident that this version of Futurecast has a pretty good handle on how things will shape up this afternoon and this evening.  By noon, we expect showers and thunderstorms to approach the Tennessee River, with increasing clouds across the rest of the Midstate:

That first wave of showers and storms will be running headlong into the dry air that moved into our area yesterday.  That will help to weaken and dissolve the first round of showers through mid-afternoon…maybe.  If those storms fall apart, another area of thunderstorms will develop and head in by late afternoon; if the first round holds together, the rain chances will arrive a little earlier than what Futurecast depicts here:

The second round of storms is the wild card — if it forms, it could be a little stronger, especially south of I-40 and west of I-65.  Keep in mind, even when we’re pretty confident in how the computers are depicting things, there’s always some difference between expectation and reality, so this isn’t a guarantee of when and where storms will be strongest and most widespread…just a good estimate:

By late evening and overnight, the second round of storms will diminish to showers as it moves into eastern Middle Tennessee:

The strongest storms this afternoon and before sunset this evening could prompt a couple of severe thunderstorm warnings, but overall our severe weather potential is very low.  The Storm Prediction Center has included southwestern Middle Tennessee in a “Marginal Risk” for severe weather, the lowest rung on the severe-weather ladder:

Specifically, they means they estimate a 5% chance of 60mph winds or 1″ diameter hail within 25 miles of any point within the Marginal Risk area:

It’s always a good idea to stay weather-aware during the spring and early summer around here, but at this point I’m minimally concerned about our severe weather potential today.  IF any watches are issued I’ll post them on social media.  ALL severe thunderstorm and tornado warnings for every county in our viewing area are posted to my Twitter feed — do NOT rely on Facebook for time-sensitive weather information.  Social media links are at the bottom of this post.

Quickly looking ahead to the holiday weekend, it’s looking like Saturday will be the ideal day for outdoor activities.  Sunday and Monday will still be warm, but will also bring increased humidity.  That mugginess will be the fuel for scattered midday and afternoon thunderstorms — only a 30-40% chance, but that’s still high enough that I’d recommend being flexible with any outdoor plans.



Lots of weather-related stuff today, plus some other space- and science-related tidbits…

  • Since there are storms in today’s forecast, this seems relevant: the five different ways lightning strikes people.
  • Despite an early start to the 2015 Atlantic hurricane season (tropical storm Ana a couple of weeks ago), don’t expect a busy season overall.
  • Can those seasonal hurricane outlooks be trusted?  Well…kind of.
  • 20 things you may not have known about clouds.
  • The drought in the western United States is having widespread impacts, including on the Colorado River.
  • The stated goal of climate-change mitigation effort is to limit total warming to a global average increase of 2 degrees Celsius.  But a more reasonable estimate is that we can expect twice that much by 2100.  (Incidentally, 3 degrees is thought to be the tipping point where climate change becomes a runaway effect.)
  • Space news: an innovative new spacecraft is hitching a ride into orbit today.
  • Laboratories around the world are beginning the search for evidence of gravity waves.
  • A new study finds that concussed NFL players actually exhibit entirely different brain structure later in life.

Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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May 19: Lower Humidity, Wednesday Storms, Daily Links


We had some dense fog out there this morning, but the drier air working its way into the Midstate helped to disperse that…that drier air is also pushing the slight shower chances farther off to our southeast.  No interference from Mother Nature if you have outdoor plans this afternoon or this evening, and you’ll be able to open up the windows for some free air conditioning tonight:
DT 4 RPM 12KM Temperature

The calm weather won’t last long — scattered showers and thunderstorms will start working their way in from the west on Wednesday.  Arrival times for the best chance of storms are still debatable…one of our Futurecast models paints this picture by late Wednesday afternoon:

…while the NAM model says the scattered storms will hold off until after sunset:

My best advice for Wednesday is to be flexible regarding any outdoor plans after about 3pm — you might still be okay, but be ready to adjust.  I’m really not concerned about severe weather at this point, but we are still in that time of year when any storm that develops could briefly produce gusty winds or large hail.  The Storm Prediction Center has included areas to the south of I-40 in a “Marginal Risk” of severe weather (which equates to just a 5% risk of 60mph winds or 1″ hail within 25 miles):

Looking ahead to the Memorial Day weekend, Saturday is looking like the most worry-free day.  Sunday and Monday don’t look like washouts, but we’ll have our typical late-spring/early-summer chance of midday and afternoon scattered thunderstorms.  Again, the best advice is to be flexible regarding outdoor plans.



Just one weather-related article today, but plenty of other nerdiness…

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May 18: scattered storms, early look at Memorial Day, daily links


Scattered showers and thunderstorms will be possible the rest of the day…it’s the same weather pattern we saw over the weekend, so expect more of the same — hit and miss storms, with breaks in between allowing temperatures to warm up to the low 80s.  A weak cold front will work its way through tonight, pushing the rain chances down to our south on Tuesday…but more importantly, that front will bring lower humidity levels to the Midstate.

Dew points will remain in the 60s today, which equates to “noticeable and unpleasant” in real-world terms.  But check out the change in dew points from this afternoon to tomorrow afternoon:

It will still be warm Tuesday and Wednesday, but “pleasantly warm” for this time of year.  Even folks along the Tennessee-Alabama state line should be able to feel a difference in the mugginess by late Tuesday afternoon.

Looking ahead to Memorial Day weekend, it looks like we’ll be transitioning back into the warm-and-muggy pattern, which also leads to at least a chance of storms each day.  Right now I think Saturday will be mostly dry, with just a very slight shower/storm chance.  A slightly higher chance Sunday, but at this point you still have good odds of doing outdoor stuff without much interference from Mother Nature.  At this point, Memorial Day itself is looking like the most unsettled day, with a pretty good chance of scattered storms:

The usual extended forecast caveats apply — the weekend is still a long way off, there’s time for the weather pattern to change, yada yada yada.  We’ll keep you updated as the unofficial beginning of summer gets closer.



A few weather-related stories today, plus some other science nerdiness…

  • Big storms through the middle of the country again over the weekend.  Straight-line winds even knocked a train off the tracks in Iowa.
  • In one of the driest places in the world, they don’t rely on rain for moisture — instead, they trap the moisture out of fog banks.
  • In Europe, they’re testing out a “solar road“.  I wonder: does it get potholes?
  • The internet might be running out of space.  I blame cat videos.
  • An interesting bit of mind candy for a Monday: the sometimes-fuzzy dividing line between physics and philosophy.
  • Some physicists haven’t given up hope of finding a unifying “theory of everything.”
  • The search for the oldest stars in the cosmos, plus a compelling profile of one of the astronomers involved in that search.
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May 15: Weekend Storm Chances, Daily Links


An unsettled forecast shaping up as we head into the weekend…we could use the rain, but of course the weekend timing isn’t ideal.  Here’s the 7-day forecast…
7 Day PM

We would love to be able to tell you exactly where and exactly when it’s going to rain, but with this type of weather pattern it just isn’t possible to do that.  Yes, it’s annoying…but it’s annoying for forecasters too!  A few things to remember regarding the weather today through Monday:

  • the driest time of day will likely be in the mornings, but even then a few showers will be possible
  • the best chance of scattered storms each day will be from midday through early evening
  • even on the highest-rain-chance days, there will still be dry periods and gaps in between the storms, so the weekend shouldn’t be a washout
  • while a storm or two could become strong, widespread severe weather isn’t likely
  • it will be warm and muggy in between the scattered storms

If all of that confuses you…
…here’s the bottom line: if you have outdoor plans, be ready to adjust — if you’re planning something that is absolutely contingent on dry weather, find an indoor alternative.  Otherwise, just be flexible and roll with whatever Mother Nature sends your way.

If you’re someone who likes to keep an eye on the national weather, tomorrow is looking like an active day.  An “Enhanced Risk” of severe weather has already been outlined by the Storm Prediction Center for the Tornado Alley states…I wouldn’t be terribly surprised if a “Moderate Risk” is eventually included along I-35 in Oklahoma and Kansas:

The analog forecasts (comparing tomorrow’s pattern to similar patterns in the past) shows an 80+% chance of at least one severe report in Oklahoma:



A couple of weather-related links, and some other interesting nuggets from the internet mines today…

  • Another consequence of the strengthening El Nino even in the Pacific Ocean…it increases the chances of 2015 becoming the warmest year on record globally.
  • NASA says that one of the Antarctic ice shelves could disintegrate completely in the next couple of years.
  • I linked to an article about Jupiter’s moon Europa earlier this week…a team of engineers is designing an aquatic robot to explore Europa’s subsurface seas (provided we can find a way to drill through the thick crust of ice on top).
  • A look at some of the biggest unanswered questions in physics, by one of the most well-known theoretical physicists in the country (don’t worry, it’s readable!).
  • I’ll be adding this to the reading list: “To Explain the World: The Discovery of Modern Science.”  Here’s an interesting Q&A with the author.
  • Simple question, complicated answer: why do we sleep?
  • I can’t wait for this to be a standard option on cars: heads-up-display GPS navigation utilizing holograms.  My fiancee will still find a way to ignore the directions and call me for help.  (Her response when I said that to her: “You’re not wrong.”)
  • More sociology than physical science here, but I found it interesting: why you should start doing more things alone.
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May 14: Unsettled Weather Ahead, Daily Links


Today will likely be the 19th consecutive day without measurable rain in Nashville…that’s not a record, and it’s not even close — September and October of 1923 brought 36 straight days of rain-free weather.  (Tip o’ the nerd cap to NWS-Nashville for that tidbit.)  It’s still unusual for this time of year, and we’re not slightly below-average for our year-to-date rainfall.  We’ll start to put a dent in that deficit with an unsettled forecast the next several days, beginning with scattered thunderstorms on Friday.  Futurecast depicts the radar simulation for Friday afternoon like this:

Unfortunately, this type of weather pattern does not allow us to guarantee the specific timing or placement of those scattered storms, so what you see represents an estimate.  I’ve fielded several emails, tweets and Facebook messages from teachers who are trying to plan “field day” activities for Friday, and my answer all week has been: “don’t cancel anything outside, but be flexible because scattered showers and storms will be possible everywhere.”  The same advice holds as we head into the weekend:
7 Day PM

The highest rain chances will arrive Saturday and again Monday, but even on those days I’m not willing to call it more than a 50% chance of seeing rain at any one particular time in any one particular location.  I’m well aware of how annoying that is if you’re trying to plan outdoor activities…if you have to have dry weather this weekend, make indoor plans instead.  Otherwise, be flexible and ready to adjust for what Mother Nature throws your way.  The good news is that our severe weather potential will remain quite low over the weekend.

However, other parts of the country are under the gun for more severe weather the next few days, especially Tornado Alley.  The Storm Prediction Center has outlined that part of the country for an “Enhanced Risk” of severe weather both tomorrow and again on Saturday:

By the time that system swings our way on Monday, it should be much less of a threat.  I don’t anticipate the Midstate being included in anything more than a “Marginal” threat of severe weather for Monday.



Tons of interesting stuff around the interwebs today…

  • We showed this video this morning on the air, but it’s worth showing again — video clips of various weather phenomena from the International Space Station, including thunderstorms, a typhoon, and Tropical Storm Ana.  (I’m such a weather nerd, if I went to space, I’d probably come back with roughly 20,000 such video clips.)
  • Anti-matter is a pretty rare thing, but one of the biggest sources might be pretty common — thunderstorms!
  • I’ve linked to a few articles about the weather extremes on exo-planets (outside our solar system)…but how do we know what the weather is like there in the first place?
  • Forecasting the weather is hard enough on our own planet…but imagine trying to do it on this one, orbiting between two different stars?
  • As astronomers search for exoplanets favorable for harboring life, they’re drawn to a class of stars called M-Dwarfs.
  • Within our own solar system, the New Horizons spacecraft is now close enough to Pluto to have spotted all five of the dwarf planet’s known moons…anything else it sees will be new and scientifically exciting.
  • Back on our planet: we typically only see the tops of icebergs…but occasionally they flip, allowing a rare and striking glimpse of a different perspective.
  • For the first time in over four decades, no one will climb Mount Everest this year.  It’s a touchy subject to begin with — HBO’s Real Sports did a fantastic piece about “tourist climbing” back in March, which I highly recommend watching if you’re a subscriber.
  • The Large Hadron Collider is still ramping up to its full energy potential, but it’s already allowing for new particles to be observed.
  • If you’re at all interested in the LHC and particle physics stuff, allow me to recommend the book “Knocking On Heaven’s Door” — it’s a little bit brain-bending, but it’s really interesting!
  • Finally…do you have any idea how much energy it takes to power the internet?  The numbers are mind-boggling.
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