Weather Changes, Eclipse & Space Station

A mix of clouds, sun and rain today.  The afternoon temperatures hovered near 78 this afternoon.  But some cooler air is on the way.  There will be a few showers this evening, but overnight toward dawn more widespread rain moves in.  This will hold temperatures down to near 70 degrees.  The rain will make the rush hour a little tricky.  a few thunderstorms are possible, but we’re not expecting anything severe.

With an upper lever low dropping in from the Ohio Valley a chance of rain sticks around through at least early Thursday.

An area of high pressure moves in Friday. It will be partly cloudy with a high near 85 but there is a slight chance of rain.

The holiday weekend will be unsettled with scattered rain and thunderstorms.  Each day will also be warm and humid with highs in the mid 80s. Monday, Memorial Day will likely the driest day of the three.

WSMV 4DAY FORECAST.png

On a Monday afternoon in August, the sky over Nashville will go black, the stars will shine bright.  Monday, Aug. 21, 2017 Nashville and areas in northern Middle Tennessee and Kentucky will bear witness to one of the biggest astronomical events in U.S. history – a total solar eclipse.  It will be the first total solar eclipse to hit what is now Nashville since July 29, 1478; and the first time since 1918, a total solar eclipse will sweep across the entire country from Oregon to South Carolina.

LS Eclipe 1

Channel 4 is joining up with the Adventure Science Center for a big event including a once in a lifetime wedding for a special couple at the eclipse viewing party. On the morning of the eclipse, Music City’s Eclipse Wedding Couple will tie the knot in a ceremony in ASC’s new Galactic Gardens with their closest friends or family in attendance. ASC will provide the flowers, music, photographer, a catered lunch, and a VIP eclipse-viewing experience at Nashville’s premier science center. The couple will have the opportunity to garner national and international attention as all eyes turn to Nashville during the total solar eclipse. If you are interested in being that couple click here.

On another space note…If the clouds don’t block our view the International Space Station will fly by tonight at 9:53 PM, It will be viisible: 6 min, Max Height: 49°, Appears: 10° above WSW, Disappears: 10° above N.

DT_Spacestation3

Give it a try the run back in and catch the weather update on the 10pm news.

Lisa Spencer

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About Lisa Spencer

Lisa Spencer is the chief meteorologist at WSMV Channel 4 Nashville. You can catch her weathercasts weekdays at 5pm, 6pm and 10pm.
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10 Responses to Weather Changes, Eclipse & Space Station

  1. Fred says:

    Should be quite a spectacle. Stats are in our favor, as around that date, on August 23, to be precise, skies over Nashville are typically at their clearest, with 69% of the time being clear, mostly clear, or partly cloudy, and mostly cloudy or overcast for the remaining 31%. The timing, also, looks favorable. The data is based on the averages from observations between 1980 and last year. The last solar eclipse (partial) visible in Nashville occurred on October 23, 2014, not long before sunset. The last spectacular one was the annular eclipse of May 10, 1994, with the maximum coverage just before noon.

  2. Lisa Spencer says:

    I like those odds for a clear sky for the eclipse. Thanks for the information.

  3. Fred says:

    Me too, but I still keep my fingers crossed. A once-in-a-lifetime event, Nashville being the only large city in the US in the path of totality, it’s just too special to be ruined by visible manifestations of condensed water vapor. If you would like, I could provide some historical sky cover data, apparently there’s been a pronounced change in the local sky conditions since 2000.

  4. Lisa Spencer says:

    Sure, that would be great.

    • Fred says:

      Ok, finally, I was able to locate my papers, and in high spirits despite the gray day (due to witnessing the exemplary thrashing administered to the Pens by the home team last night) it feels appropriate to do a post on the historical cloud cover data for Nashville.
      While the concept of global warming (whether agreeing with it or not) is familiar to just about everyone nowadays and various hypotheses have been proposed to account for it, one of the contributing factors that is not often mentioned and, consequently, is less well known to the general public is the cloud cover. Clouds impact the climate in both negative (heavy sky cover during the daytime typically keeps temperature lower, especially in warm season) and positive fashion (keeping temperature warmer at night by limiting radiative cooling, particularly during the cold season) . Yet, looking for the relevant data for Nashville, I was unable to find any research dealing with sky cover and whether any significant changes have been observed since the record-keeping began. The only readily available info on the subject are the averages of fair, partly cloudy and cloudy days based on the data from the local National Weather Service, which are given below (rounding off to nearest integer) .

      Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
      Fair 6 7 8 8 8 8 8 10 11 13 9 7 103

      Partly Cloudy 6 6 7 9 10 12 13 12 9 8 7 7 106

      Cloudy 19 15/16 16 13 13 10 10 9 10 10 14 17 156/157

      Therefore, I decided to test the validity of those figures, limiting my research mostly to the period from 2000 onward, but as a historical backdrop providing an overview of the sky cover properties starting with 1970s. The average figures from that decade were as follows: Fair 103, Partly Cloudy 99, Cloudy 163. As can be seen, partly cloudy days were the minority during the 1970s and in 1976 (the clearest year of the decade) there were only 79 of those, the lowest yearly total from the entire period of my research. The peculiar feature of the disco era 🙂 was the unusual clarity of the months that are not known for an abundance of fair-weather days, e.g. April ’71 and ’76, January ’76, February ’77 (the clearest on record for Nashville with 16 fair days), November ’76, December ’76 (the clearest in modern history) and ’79.
      1980s were, overall, a brighter decade, but the figures didn’t change much: Fair 109, Partly Cloudy 98, Cloudy 158. This is rather surprising given how different, weather-wise, they were. The ’70s were the only decade when no triple digit days were officially registered in Nashville, with many cold and snowy winters (especially the last three, 1977-78 being the coldest ever), typically cooler summers (summer of ’76 is the coolest on record) and most years being wet (only 1971 was considerably drier than normal) with 1979 producing the all-time record of 70.12″ of precipitation. The ’80s, on the other hand, were defined by extreme drought, with the top four driest years following in succession between ’85 and ’88, with 1980 being the 7th-driest on record. Half the years produced days with sub-zero temps (1982-1985, tying the longest such streak from 1880s, and also ’89) and four had triple-digit days (’80, ’83, ’86, ’88 all of those, except ’86, featuring brutally hot summers ) and both extremes generally came in bunches. 1988 was the clearest year in modern history with 148 fair days, every month, except January, March and July was remarkably clear and bright. Yet, for all their differences, none of the years from those decades were among the hottest on record, 1973 and 1987, the top candidates, good only for a tie for 33rd and 38th place, respectively. Starting with the 90s, the picture began to change: fair days became the minority, while partly cloudy increased significantly, viz. Fair 86, Partly Cloudy 120, Cloudy 159. The averages are based on the data from 1990-95, as in July of 1996, Nashville weather station switched to automation and the cloud cover data in the numerical format was no longer submitted in the final report to the NCDC. Hence, the data from June ’96 through December ’99 is a notable omission from my research, however, circumstantial evidence points to the fact that those years were hardly very different from the pattern established earlier in that decade. The ’90s were notable for the general lack of extended fair-weather spells, only the unusually sunny and pleasant 2-week stretch, lasting from late January to February of ’93, and November of ’99 stand out in that regard, while the summers were noted for overall cloudiness and much below-normal levels of sunshine, particularly the final years of the century. Dubious records were set for July 1990 with only 37 % of sunshine (at the time the lowest ever for July, eclipsing 41% from that of 1979), May ’91 (the cloudiest May on record, May from the previous year also being markedly gloomy), August ’92 (the cloudiest August ever), June ’97 (first half dominated by overcast skies, in fact, from May 24th until June 14th, Nashville experienced mostly cloudy to overcast conditions, a remarkable streak for that time of year), July ’98 (rivaling July of 1979 for shear cloudiness and setting the all-time record for the lack of sunlight, not only for July but for any summer month- a miserable one third of available sunshine). The summer of 1998 was the most sun-starved on record, as the sunshine percentages attest: June 53, July 34, August 41. 1998 could, likely, challenge 1957 as the cloudiest year ever in Nashville.
      As the new millennium dawned, fair days gradually increased in number and sunshine made a welcome return. In 2005, notable for the two lengthy dry streaks, fair days outnumbered the cloudy ones for the first time since 1988: 114 vs 105. 2006 brought the total for cloudy days below 100 for the first time since 1925 and their total (96) was the lowest since 1904, which also had the same number of cloudy days. That benchmark would not survive for long, as the very next year would smash it with ease. 2007, characterized by probably the most extreme drought in the history of Middle Tennessee (it, actually, started in November 2006 and continued for most of October) established what, likely, was the fewest number of cloudy days until then: a meager 84, eclipsing 87 from 1898 (!), with no single cloudy days recorded between June 30 and August 29, – one of the longest, if not the longest such streak. That record would be bested in 2012, which dropped it to 83, and until the markedly cloudy December, that year was notable for the lack of persistent cloudiness, and remains our last mostly bright year so far, while 2010 yielded the greatest number of fair days since 1988, namely 119. The months that stood out for unusual clarity since 2000 were November 2001, 2009, 2012, February 2002 (clearest since 1977), September 2005 (clearest since 1953) and 2016 (identical in sky cover value of 99 to 2005, but having 3 fewer fair [15] and 2 more cloudy days [3]), December 2006 (clearest since 1988), August 2007 (clearest since 1988), October 2010 (clearest October and month overall since 1974), June 2012 (clearest since 1988). Exceptionally cloudy were May 2000 (cloudiest since 1991), October 2002 (the cloudiest month of its name) as well as October 2004 and 2009, February 2003 (the gloomiest ever February that concluded with 15 straight overcast days, with 2 more to spill over into March, the longest streak of overcast days known), December 2000 and especially 2014 (the cloudiest December on record), January 2017 (the cloudiest since 1980). But the principle change was the dramatic increase in the amount of partly cloudy days, which became the majority, at the expense of the cloudy days, as the averages from 2000-2016 clearly indicate: Fair 95, Partly cloudy 157, Cloudy 113. Every month was affected by this dynamic and produced individual records for the most partly cloudy days observed in a calendar month, namely January- 17 (2008), February- 14 (most recently in 2017), March- 20 (2012), April- 17 (2007), May- 20 (2016), June- 22 (2010 and 2013), July- 28 (2007) which is the most ever for any month, August- 25 (2016), September- 20 (2013), October 17 (2000) among others. Once again, these are not just outliers, but a well-established pattern. The adjusted table, reflecting this trend, would now look like this:

      Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
      Fair 6 5 6 8 6 9 7 10 11 11 10 6

      Partly Cloudy 12 10/11 13 13 15 15 18 17 12 12 10 10

      Cloudy 13 13 12 9 10 6 6 4 7 8 10 15

      As evident, some of the months actually benefitted from the trend, most noticeably June and November, while most saw a decline in both fair and cloudy days. December has overtaken January for the dubious distinction as the cloudiest month in Nashville. Interestingly, since this development first manifested itself in the 1990s, a dramatic increase in very warm years has taken place alongside. Our top 12 is populated by 8(!) years since the start of the ’90s: 1990, 1991, 1998, 2006, 2007, 2012, 2015 with last year being the warmest ever (so far) while only 1921, 1931, 1933 and 1938 represent the times of long ago. Unsurprisingly, 2016 also produced the highest ever total of partly cloudy days, a bloated figure of 184 (cloudy days numbered only 88, among the lowest totals on record), 66 of which comprised the relentlessly hot summer, yet another record value. I seriously doubt that these findings are just a statistical phantom, but would be glad to hear meteorologists’ remarks about the phenomenon.

  5. Fred says:

    Some corrections/revisions:
    May 2000 was the cloudiest May since 1995, not 1991. The sky cover figures are: 235 (May ’90), 246 (’91), 233 (’95), 217 (2000). Very cloudy were also June ’91 (215) and June and July of ’94 (218 and 211, respectively, all figures reflect sunrise-to-sunset cloudiness). Besides 1998, other summers were notable for abnormally low amounts of sunshine, e.g. 1990: June-57%, July-37%, August-47% (for comparison, normal values for those months in Nashville are as follows: 65%, 63%, 63%). When you consider that in May of that year sun, typically, was also conspicuous by its absence, with just 36% of available sunshine vs the average of 60% for May, let’s just say, I wouldn’t envy local meteorologists of the time. I don’t have the figures for the summer of 1996, but, likely, it also had above-average cloudiness. The percentages for 1997 were 44 for June, 61 for July and 52 for August. In 1999: 45, 45, 61, respectively. That’s, definitely, way more than a fair share of lame Mays and bummer-of- a-summer’s for one decade.
    Finally, since the monthly and yearly figures in the above post were somewhat illegible, here’s, hopefully, an easier to decipher table, displaying averages since 2000 vs the official stats (provided in parentheses)

    Fair/Partly Cloudy/Cloudy

    January 6/12/13 (6/6/19)

    February 5/10/13 (7/6/15)

    March 6/13/12 (8/7/16)

    April 8/13/9 (8/9/13)

    May 6/15/10 (8/10/13)

    June 9/15/6 (8/12/10)

    July 7/18/6 (8/13/10)

    August 10/17/4 (10/12/9)

    September 11/12/7 (11/9/10)

    October 11/12/8 (13/8/10)

    November 10/10/10 (9/7/14)

    December 6/10/15 (7/7/17)

    Year 95/157/113 (103/106/156)

    Since August, our least cloudy month, has gotten considerably less so, this bodes well for the upcoming eclipse spectacle.

    • paulheggen33 says:

      That is certainly good news (potentially) for the eclipse! I’ve been worried about that — even though worrying about it obviously doesn’t do any good. Interesting data overall, especially regarding the summer sun/winter clouds combining to push average temperatures consistently higher.

      • Fred says:

        Odds are in our favor, but given the importance of the occasion, could we assist Mother Nature by cloud seeding, should the weather be in non-cooperative mood? As for the unusually cloudy 1990’s, perhaps, too much “Seattle” in the air 😉 (there was a LOT of that on the airwaves at the time, for sure).

  6. Lisa Spencer says:

    A lot of great information. Thank you for sharing it.

  7. Fred says:

    I’m honored by your evaluation of my work, Lisa.

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