3 items…Your observation of the shadows not growing long as totality approached was neat to think back upon…I was not expecting my shadow to lengthen, but thinking back to the experience, this is yet another unique part of it! As to climatology, I believe a lot of the climatology was perhaps based upon ASOS data that did not have the added value of a human observer. Most ASOS observations will show clear skies if a cloud deck base is >12,000’. The USWB climate series which included Laredo Air Force Base 1956-1960 climate data of hourly temperature, dewpoint, wind speed/direction, cloud cover shows an average of a 51% cloud cover for April at 1 pm CDT, not the 30ish percent shown of the climatological maps being presented. We quite often will have a shallow layer of gulf moisture flowing north with morning stratus capped by warm dry air that perhaps stirs in, mixing away the stratus around 1 pm! This was the case on April 8 in Eagle Pass…fortunately, a solid deck of stratus/stratocumulus broke up enough, just in time for us to get a good view of the arrival of totality, much of totality itself, and the end of totality. Your remark concerning the forecasting of the totality down to the foot and fraction of a second brought an item that I still find remarkable: Before computers with just pencil and paper, mechanical adding machines and slide rules, the total eclipse of 1925 over New York City was forecast to have the edge of totality between 82nd and 83rd street on Manhattan Island. Observers were in place on every block from about 30th street to 135th street. The eclipse went total just 4 seconds late, and the edge of totality was between 96th and 97th street, just an error of 14 city blocks!
Just as an addendum, the 1956-1960 Laredo data showed 8/10 to 10/10 cloud cover 51% of the time at 1 pm CDT. ~69% of the time that clouds were observed, the cloud base was >9,500’ altitude suggesting that a METAR based cloud climatology would not be reporting a significant portion of cloud coverage, that the ~30% estimated average cloud cover is an underestimate. It would be interesting to see if a similar or not so similar METAR based cloud coverage bias would be found with cities around the nation…it could be that the cloud coverage geographical climatology would have the same general cloud coverage maximums and minimums, just with higher coverage estimates throughout!
3 items…Your observation of the shadows not growing long as totality approached was neat to think back upon…I was not expecting my shadow to lengthen, but thinking back to the experience, this is yet another unique part of it! As to climatology, I believe a lot of the climatology was perhaps based upon ASOS data that did not have the added value of a human observer. Most ASOS observations will show clear skies if a cloud deck base is >12,000’. The USWB climate series which included Laredo Air Force Base 1956-1960 climate data of hourly temperature, dewpoint, wind speed/direction, cloud cover shows an average of a 51% cloud cover for April at 1 pm CDT, not the 30ish percent shown of the climatological maps being presented. We quite often will have a shallow layer of gulf moisture flowing north with morning stratus capped by warm dry air that perhaps stirs in, mixing away the stratus around 1 pm! This was the case on April 8 in Eagle Pass…fortunately, a solid deck of stratus/stratocumulus broke up enough, just in time for us to get a good view of the arrival of totality, much of totality itself, and the end of totality. Your remark concerning the forecasting of the totality down to the foot and fraction of a second brought an item that I still find remarkable: Before computers with just pencil and paper, mechanical adding machines and slide rules, the total eclipse of 1925 over New York City was forecast to have the edge of totality between 82nd and 83rd street on Manhattan Island. Observers were in place on every block from about 30th street to 135th street. The eclipse went total just 4 seconds late, and the edge of totality was between 96th and 97th street, just an error of 14 city blocks!
Just as an addendum, the 1956-1960 Laredo data showed 8/10 to 10/10 cloud cover 51% of the time at 1 pm CDT. ~69% of the time that clouds were observed, the cloud base was >9,500’ altitude suggesting that a METAR based cloud climatology would not be reporting a significant portion of cloud coverage, that the ~30% estimated average cloud cover is an underestimate. It would be interesting to see if a similar or not so similar METAR based cloud coverage bias would be found with cities around the nation…it could be that the cloud coverage geographical climatology would have the same general cloud coverage maximums and minimums, just with higher coverage estimates throughout!