Coldest Weeks, 2 Weeks, and Months on Record.
Jan 15, 2018 23:53:39 GMT -5
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Post by nei on Jan 15, 2018 23:53:39 GMT -5
How do your recent cold snaps compare?
I posted these earlier, but wanted to collect them in one thread. I wrote a script that could calculate the top cold periods of any given length for stations that are available on the NCDC website. I added the latest data for the American stations, so the cold wave of late December and early January is included. And yea, the column headings say weekly but it may not mean "weekly", was just easier to output that way. The date is the last day of the period, and they're sorted by the mean temperature of the period but I show the average daily max and min as well. Obviously, the shorter timeperiod the colder the average temperatures. The recent coldspell broke few if any records by daily temperatures and really few days stood out as memorable; the length (2 weeks) stood out as memorable). So, it ranks highest in the "2 weeks coldest category". Since two weeks after the cold spell isn't finished yet, no fair to tell if it could make the coldest 4 weeks category; doubt it given even just a few mild days a week later. I like my ranking better than the ones usually posted on weather website (coldest month, coldest first week of January) since weather doesn't follow the calendar. Here's Raleigh. As I said, ranking went up once the period went to 2 weeks.
Raleigh 1-week. 2018 is only #3, but not far behind #1 and #2.
Raleigh 2-weeks. 2018 has the second coldest 2 week period on record for Raleigh, but it's very close to #3 and #4. Jan 1977 (remember @tarheelboi mentioning it) had a 2 week period almost 4°F colder than the 2018 one. Feb 2015 actually ranks higher by one week rather than two weeks; must have been less consitent down there and only the coldest part was able to blast down south.
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Now Amherst. 2018 makes it to the top 10 but a number of other decades are much colder. Late February 2015 makes an appearance to the list but far in the bottom; still only one of the top 20 coldest weeks that's in late February; there's one other from mid-February back all the way in 1899. There's also only two include December, 1918 and 2018 both only include a few end of December days. 1961 sticks out by very cold nights. Amherst 1 week
Amherst 2 weeks. The week after the coldest week of early 2018 was still very cold, just not cold enough to make it to the top 20 coldest. So by coldest 2 weeks, it's very cold. 1961 really stands out in the 2 week ranking, its average max is similar to other coldest 2 week periods, while by daily mins its a full 10°F colder than any other coldest 2 week periods. It had a number of nights that reached -27°F (-32°C) something hasn't before or since. A couple archived reanalsyis maps I've seen it doesn't look exceptionally cold, just "normal" arctic blast. Just a setup that allowed for lots of cold air pooling + radiational cooling? Station error?
the coldest 2 week period in Feb 2015 had similar morning temperatures to the 2018 cold; felt like a freezer followed by a warm-up to clear skies and non-brutal cold. I'd guess the higher sun of late winter helped, but other periods had similarly high diurnal range [and yes, Babu it followed the day/ night most of the time]. 2015 was more consistent, though.
Amherst 4 weeks. As I said the last one can't make it to the list yet as we need more weeks. 2015 shoots up in ranking to number 3, and its end date is in March. 2015 had few extreme days or even weeks, so the longer the periods the better its ranking. Feb 2015 is the coldest month on record, it's not quite so cold by measure; the 2 colder 4 week periods were split across two calendar months, while the 2015 almost exactly covered all of February. Feb 2014 sneaks in at the end, no extreme cold, just consistent tedious cold.
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Since Amherst isn't an "official station"; part of the National Weather Service network but as volunteer "COOP station" not used for weather readings, I decided to check the closest main airport station near me; Hartford-Bradley Airport which is actually 10 miles north of Hartford, maybe 35 miles south of me. Winter temperatures drop fast going north, so the big temperature difference is real. Hartford 1 weeks
So that cold 2 week 1961 period was 4.4°F warmer at Hartford Airport compared to Amherst. The 2018 cold spell was 3.6° warmer in Hartford than Amherst, so fits. Most of the difference is in the minimums, which makes sense, minimum seem to vary more and drop more going north. 2015 doesn't rank quite as in Hartford as Amherst, and the Amherst data goes back to the 1890s while Hartford starts at 1949. Hartford 2 weeks.
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If people want to see these tables more stations, I'll post them. I've done Miami and St. Petersburg
I posted these earlier, but wanted to collect them in one thread. I wrote a script that could calculate the top cold periods of any given length for stations that are available on the NCDC website. I added the latest data for the American stations, so the cold wave of late December and early January is included. And yea, the column headings say weekly but it may not mean "weekly", was just easier to output that way. The date is the last day of the period, and they're sorted by the mean temperature of the period but I show the average daily max and min as well. Obviously, the shorter timeperiod the colder the average temperatures. The recent coldspell broke few if any records by daily temperatures and really few days stood out as memorable; the length (2 weeks) stood out as memorable). So, it ranks highest in the "2 weeks coldest category". Since two weeks after the cold spell isn't finished yet, no fair to tell if it could make the coldest 4 weeks category; doubt it given even just a few mild days a week later. I like my ranking better than the ones usually posted on weather website (coldest month, coldest first week of January) since weather doesn't follow the calendar. Here's Raleigh. As I said, ranking went up once the period went to 2 weeks.
Raleigh 1-week. 2018 is only #3, but not far behind #1 and #2.
Raleigh 2-weeks. 2018 has the second coldest 2 week period on record for Raleigh, but it's very close to #3 and #4. Jan 1977 (remember @tarheelboi mentioning it) had a 2 week period almost 4°F colder than the 2018 one. Feb 2015 actually ranks higher by one week rather than two weeks; must have been less consitent down there and only the coldest part was able to blast down south.
==============================
Now Amherst. 2018 makes it to the top 10 but a number of other decades are much colder. Late February 2015 makes an appearance to the list but far in the bottom; still only one of the top 20 coldest weeks that's in late February; there's one other from mid-February back all the way in 1899. There's also only two include December, 1918 and 2018 both only include a few end of December days. 1961 sticks out by very cold nights. Amherst 1 week
Amherst 2 weeks. The week after the coldest week of early 2018 was still very cold, just not cold enough to make it to the top 20 coldest. So by coldest 2 weeks, it's very cold. 1961 really stands out in the 2 week ranking, its average max is similar to other coldest 2 week periods, while by daily mins its a full 10°F colder than any other coldest 2 week periods. It had a number of nights that reached -27°F (-32°C) something hasn't before or since. A couple archived reanalsyis maps I've seen it doesn't look exceptionally cold, just "normal" arctic blast. Just a setup that allowed for lots of cold air pooling + radiational cooling? Station error?
the coldest 2 week period in Feb 2015 had similar morning temperatures to the 2018 cold; felt like a freezer followed by a warm-up to clear skies and non-brutal cold. I'd guess the higher sun of late winter helped, but other periods had similarly high diurnal range [and yes, Babu it followed the day/ night most of the time]. 2015 was more consistent, though.
Amherst 4 weeks. As I said the last one can't make it to the list yet as we need more weeks. 2015 shoots up in ranking to number 3, and its end date is in March. 2015 had few extreme days or even weeks, so the longer the periods the better its ranking. Feb 2015 is the coldest month on record, it's not quite so cold by measure; the 2 colder 4 week periods were split across two calendar months, while the 2015 almost exactly covered all of February. Feb 2014 sneaks in at the end, no extreme cold, just consistent tedious cold.
================================
Since Amherst isn't an "official station"; part of the National Weather Service network but as volunteer "COOP station" not used for weather readings, I decided to check the closest main airport station near me; Hartford-Bradley Airport which is actually 10 miles north of Hartford, maybe 35 miles south of me. Winter temperatures drop fast going north, so the big temperature difference is real. Hartford 1 weeks
So that cold 2 week 1961 period was 4.4°F warmer at Hartford Airport compared to Amherst. The 2018 cold spell was 3.6° warmer in Hartford than Amherst, so fits. Most of the difference is in the minimums, which makes sense, minimum seem to vary more and drop more going north. 2015 doesn't rank quite as in Hartford as Amherst, and the Amherst data goes back to the 1890s while Hartford starts at 1949. Hartford 2 weeks.
===============================
If people want to see these tables more stations, I'll post them. I've done Miami and St. Petersburg
