Page 1 of 1

Galveston's Warming Climate - Part II

Posted: Mon Feb 18, 2008 11:20 am
by jasons2k
From what I have seen, the trend is pretty similar in Houston as well.

Since we are now in for a couple of days of tranquil weather, I thought that I would present the second part of my three-part series on local warming.

In part 1 (January 23) I analyzed local climate trends using the official data available for the city of Galveston since 1871. This data, confirms what many locals already have recognized. Temperatures in Galveston have risen overall in recent years, particularly since 1990, and now stand at the warmest levels since observations began in 1871.

In part 2, I examine our winter-time weather. Again many area residents, particularly gardeners, have noticed that winters are significantly warmer now than they were 20-30 years ago. What is especially evident is the absence of any hard freezes on the Island and the consequent changes in the types of vegetation that now flourish here.

Again, the climate statistics support these impressions. In 1903, the average winter-time (December through March) temperature was 55.0 degrees (based on observations from 1871-1903). Subsequently, the three month winter average hovered consistently around a 55 degree average. In 1940, it was 55.5 degrees, in 1980, it was 55.3 degrees. In 1990, the average was 54.9 degrees, but by 2000 the average had jumped to its highest level since observations began, with a 57.3 degree average. Since 1991, when the warming became most evident the winter-time average has been 57.4 degrees in the city. This jump of 2 degrees may not seem significant, but it is the equivalent of moving at least 125 miles further south down the coast.

Perhaps the greatest change in our winter-time weather, however, has not been the rise in the average temperature, but the virtual disappearance of hard freezes on the Island. From 1871 through 1989, the coldest temperature in Galveston by each decade on average was 16 degrees. Since 1990, the lowest ten year temperature in the city has averaged 27 degrees.

Looking at this another way, from 1872-1899, 71.4% of the years had a "hard freeze" (defined for purposes of our local vegetation as a temperature below 30 degrees) and 53.6% of the years had a "very hard freeze" (defined as a temperature of 25 degrees or lower). From 1900 through 1989, 63.7% of the years had a hard freeze and 36.6% had a very hard freeze. Since 1990, only 11.1% of the years have had a hard freeze and 11.1% have had a very hard freeze (representing the 24 degree low temperatures observed in 1990 and 1996). The city has now gone an unprecedented 11 years without a hard or very hard freeze.

You might say, as I have on occasion, "What is so bad about that? I do not like cold weather anyway". Certainly, it is nice to be able to grow the semi-tropicals and tropicals that now beautify our gardens, and the lower heating costs are more than welcome.

But, as we shall see in part 3 of this series in a few weeks. This warming trend has also dramatically affected our summer-time climate. The unpleasant side of this warming trend has been markedly warmer summer temperatures and the associated higher cooling bills.


http://galvestondailynews.com/blog.lass ... 24bb3c0ce5

Re: Galveston's Warming Climate - Part II

Posted: Mon Feb 18, 2008 11:32 am
by Ed Mahmoud
Summer time temps on the island are very dependent on wind direction.



My wife's abuelo, "Popo", has a little vacation home down on Jamaica Beach. It is a long drive, over an hour in the best of conditions, but I like getting down there, especially in hurricane season.


I remember thinking, the weekend before the weekend before (ie, about 9 days) Katrina hit LA/MS how warm the surf was.


Even with the warm water, the fish are plentiful. Spooky, to be wading, and have fish swin by inches away. Even spookier, the crabs. And double extra spooky, my wife's cousin James and her Tio Concepcion wade out to a far sandbar, through water that gets almost head deep, to fish, with their bait tied to them by a three or four foot string. But no shark bites yet.

Re: Galveston's Warming Climate - Part II

Posted: Mon Feb 18, 2008 11:45 am
by jinftl
Are both warmer daytime highs and warmer nighttime lows driving this increase in temp?

Here in Fort Lauderdale, we have had an incredible number of record max nightime (minimum) temps over the last 10 years...and this has been the main driver of overall warmer months.

Since 1998, Fort Lauderdale has had the following number of Record High Minimum Temps: January-16 dates, February-10 dates, March-21 dates. This trend is seen in the remaining months of the year as well.
(http://www.srh.noaa.gov/mfl/localdata.php)

In comparison, there has been only 1 Record High Maximum Temp in January since 1998, 3 in February, and 10 in March.

Warm nights here are something we would expect to see with an easterly/southeasterly flow off the ocean. This same flow would lead to warm days, but probably not record warm, since the seabreeze would temper the heat a bit on the coast.

Could it be we are seeing this warmth because of stronger high pressure or high pressure location off the coast leading to a more persistent easterly flow...and this may be true in Galveston as well?

Re: Galveston's Warming Climate - Part II

Posted: Tue Feb 19, 2008 9:18 pm
by MGC
Blacktop is the culprit. Years ago the streets were concrete, now they are blacktop. You just can't look at one factor to make a conclusion....MGC

Re: Galveston's Warming Climate - Part II

Posted: Thu Feb 28, 2008 4:44 pm
by r22weiss
In Katy, TX we have had quite a few frosts and one good freeze this winter. I have had to bring my plants in more this winter than in the past few. I have to admit my data is a very small sample though.

But i would expect the actual city of Houston to have similar findings to this study due to the urban heat island effect.