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December 1989 Freeze
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DoctorMu
Location: College Station
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Re: December 1989 Freeze
Post by DoctorMu » Fri Dec 11, 2020 4:30 pm
MontgomeryCoWx wrote: ↑
tropiKal wrote: ↑
KHOU BLake wrote: ↑
No, a freeze of that extent may NOT happen again in your life.
Already in the past 30 years, temps citywide have largely been struggling to dip below 20F. And things will only get milder overall as climate change continues. I'm not saying that there won't be cold snaps in the future, but I just can't see such 1989 level of deep freeze ever returning.
I'm in my very early 20s, so there's ample time to see that it will all be correct.
With the changing climate, the jet is becoming more erratic which tells me we may see more arctic outbreaks and more chances for snow.
But that would only matter if the northern source regions remain cold enough to begin with. There's still (infinitesimal) wiggle-room in the near term, but that rapidly shuts out going further into the future - the deep freezes of yesteryear become the cool breezes of tomorrow.
Even the erratic jet behavior itself could only be temporary. With time going on, the differences in change start leveling out, allowing more relaxation of the jet stream. Ultimately, it all could even encourage a completely barotropic setup with the extinction of frontal boundaries.
Houston has a long history of extremely cold temperatures for our latitude.
We've hit the single digits four times in the last 150 years. It nearly happened twice within 7 years. In 1983, IAH hit 11 degrees and then 7 degrees in 1989. If you count all the times we've hit 5, 6, 7, 10, 11, 12, 13 or 14 degrees, it's quite a few. Memory is short. In 2018, I believe Tomball got to 14 degrees. Crockett dropped to 10 degrees! On January 17th, Conroe dropped to 14 degrees and on the 18th (the next day) dropped to 15 degrees! So I wouldn't say it'll never happen again. It nearly did just three years ago. I'm not quite sure why IAH "only" got to 19 degrees but everybody to its east and west were 3 to 5 degrees colder than that that morning.
Sometimes we forget but we do live at 30 degrees north latitude. Historic freezes like that leave a lasting impression because they are so superlative. By their nature, they happen twice or three times a life time.
Yes, I already mentioned in a previous post the occurrence of such cold temps throughout the city's history. But since 1990, IAH only saw three instances of winter temperatures below 20F, with HOU seeing only one such instance. Rural areas in northern/inland parts of the metro would have been a bit colder, but it's all still a general warming trend across the board.
The last decade has been colder overall than the 2000s and 1990s. You have to go back to the 1980s to find a colder decade.
And absolutist predictions have happened since the 1950s. In the 70s, a new ice age was coming. In the late 90s the polar ice caps would be long gone by 2015. Turns out neither were right.
People who speak in absolutes are almost never right. They also don't take into account how solar affects our weather.
Blake hit the nail on the head.
There's no question that overall the troposphere is warming as CO2 levels rise. CO2 absorbs infrared spectrum radiation. About 1-1.5°C in the last Century as we've gone from 280 ppm to 420 ppm.
1. Distribution of CO2 in the troposphere is homogenous: latitude and altitude
2. CO2 in the troposphere has a long half-life - years
3. The CO2 molecule cares not about personal and political opinions
4. Solar forcings have been taken into consideration.
5. However, climate and weather are not synonymous
6. The EFFECTS of rising CO2 on average temperature are HETEROGENOUS. Much higher in North Dakota, especially in the winter. No change in Houston. Trending higher since the 60s in Dallas.
https://www.currentresults.com/Weather- ... dallas.php
7. VARIATION in weather has become greater (including wintry mischief in SETX)
8. Severe Season is a little earlier and trending farther South - not good news for LA, MS, AL
9. Hurricanes on average are no more numerous, but risk of Atlantic Basin major hurricanes is substantially elevated.
10. Sea Level is slowly rising.
11. However, PREDICTIONS of future trends, especially are VERY Difficult, because
a. the effects of increased water vapor (as temps rise) is difficult to take into account because water vapor in the troposphere is very heterogeneous and has a very short half-life (days)
b. adiabatic contributions form unpredictable feedback loops
c. We have a robust sunspot cycle (could accelerate heating) followed by a nadir in sunspots that *could* slow down warming.
12. Due to long term (60M years worth) of global cooling and drying we have a far more unstable Earth climatewise, especially over the past 2M years...and ice cap advancement and retreat are robust and rapid. The Noah's Ark mythology/story is probably related to massive rains, flooding, rise of sea level by 100s of feet at the end of the last ice age...possibly as flood waters filled the Persian Gulf.
Hopefully, the Doomsday Glacier in Antarctica will give us 400 years rather than 4 or 40 to ease towards renewable and CO2 neutral energy. This was a fast growing sector of the US economy...but the transition will take decades.
Post by tropiKal » Fri Dec 11, 2020 9:28 pm
The 2010s did feature colder absolute minimums than the 1990s and the 2000s, but that still preserves an overall warming trend in winter temps across the board. There's still healthy chance of cold snaps like the one of Jan 2007 (at least in the near term). But deep freezes to the extent seen in 89' will just remain pure history.
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