Snow In Houston Part 1

In a two part series, I will explore snowfall in Houston. In the first part, I will look at what atmospheric conditions allow snow to fall in Houston, specifically +1 inch snowfall. The second part I will look at what climatological patterns are favorable for snowfall in Houston.

Here is the history of Houston snowfall from 1895 to this year. Some records could be missing, so this may not be a complete data.

Snowfall in Houston is a relatively rare event. Going back to 1895, there have been 43 snowfall events up to 2010. Fourteen of them had +1 inches of snowfall. Here is the overall probability of seeing snowfall in Houston by amount.
Any Snowfall = Every 2.7 years
+1” Snowfall = Every 8.2 years

Compare this to tropical storms and hurricanes making landfall on the Upper Texas Coast from 1870 to 2010.
Any Tropical Storm = Every 1.9 years
Hurricane = Every 3.6 years
Major Hurricane = Every 10.8 years

In many ways, Houston has a better chance of seeing a tropical storm and hurricane affecting Houston than snow falling. On the other hand, Houston has a better chance of seeing +1 inches of snow than a major hurricane making landfall. Keep in mind, snowfall record dates back to 1895 and tropical cyclone landfalls are dated back to 1870.

The most snowfall ever recorded in Houston was on February 14-15, 1895, where 20 inches of snow fell! That exceeds the 24 hour snowfall record in Chicago. Some areas got up to 31 inches of snow. This type of even is incredibly rare, likely happens every 150 to 300 years. It snowed on Christmas Eve 2004, in which areas southwest of Houston saw up to 13 inches of snow, which came close to 1895. Now, if the 1895 snow event was to happen today, it would shut down the Houston area and bring it to a standstill, since Houston is not used to snow.

I used the NOAA-Daily Composites, which generate maps. Unfortunately, it only goes up to 1948. There is nothing before 1948. It would be interesting to see what it was like in the 1895 snow event. Here is the atmospheric air temperature anomaly during the snow event. Bold indicated date it snowed.

January 30, 1949
The earliest +1 inch snow fall I can find at the Daily Composites.

The layer of cold air was deep from the surface to up to 30,000 feet (300 millibar level).

1/29/1949-33/25
1/30/1949-28/18
1/31/1949-42/14
2/1/1949-42/29

Here is the geopotential height map at 18,000 feet (500 millibars). More on geopotential height.

There was a major freeze that hit Southeast Texas in late January 1949. A deep trough forms and allows cold air from the Arctic. A upper level low pressure system from the west comes and draws in moisture from the Gulf of Mexico and Pacific.

February 12, 1960
The heaviest snowfall recorded officially since the February 14-15, 1895 snowfall event.

The air up to 18,000 feet (500 millibar level) is unusually cold. At 30,000 feet, it is normal.

2/11/1960-58/44
2/12/1960-49/30
2/13/1960-47/37
2/14/1960-58/37

Here is the geopotential height map.

Despite the snowfall total, Houston was not really cold. Usually, when it snows, it is not that cold. From the maps, the February 1960 snow event looks similar to the December 2008 snow.

January 11, 1973
The first of the three snowfall to hit Houston in Winter 1972-1973. Some parts of Houston saw up to 8 inches of snow.

Cold air all the way up to 30,000 feet.

1/8/1973-38/32
1/9/1973-34/31
1/10/1973-33/31
1/11/1973-33/25
1/12/1973-38/19
1/13/1973-58/20

Here is the geopotential height map.

It was quite cold when it snowed and it got colder once the snow passed. Prior to the snow, there was glazing of ice. A low pressure system from the west is the culprit. Also, there is a deep trough that brings in cold air from the north.

February 9-10, 1973
The second of the three snowfall in 1973.

The air anomalously cold in the February 9-10, 1973 snow event.

2/7/1973-75/62
2/8/1973-65/32
2/9/1973-38/30
2/10/1973-52/22
2/11/1973-60/24
2/12/1973-67/48
2/13/1973-70/53
2/14/1973-58/39

Here is the geopotential height map.

Just two days before it snowed, it was warm in Houston. There is a upper level low pressure to the west and is pushing sub-tropical Pacific moisture over Texas.

February 17-18, 1973
Eight days later, Houston sees snow again and it at least 1 inch, which is amazing in 1973. Talk about a really unusual winter. By the way, 1972-1973 winter was El Nino.

Here is an interesting one. It is cold up to 18,000 feet, but at 30,000 feet, it abnormally warm.

2/15/1973-60/31
2/16/1973-53/31
2/17/1973-45/33
2/18/1973-54/35
2/19/1973-64/45

Here is the geopotential height map.

Unlike the previous snow storm, it was not as cold.

February 2, 1980
It is unusually cold up to 5,000 feet. However, at 18,000 feet it is normally, than at 30,000 feet, it is unusually cold again.

1/31/1980-44/34
2/1/1980-47/28
2/2/1980-42/32
2/3/1980-55/37

Here is the geopotential height map.

There was a freeze that time when it snowed in February 1980. The freeze is not a strong one.

December 22, 1989
I remember this one well. The driest snow to fall in Houston. Officially, 1.7 inches of snow fell, which was 0.14 inches of rain. It came before Houston hit single digit, a rarity in Houston.

It is unusually cold up to 18,000 feet. However, at 30,000 feet it is normal temperature.

12/20/1989-46/33
12/21/1989-46/30
12/22/1989-34/13
12/23/1989-28/7
12/24/1989-43/11
12/25/1989-61/20

Here is the geopotential height map.

It was a unusually cold December even before the big freeze came on December 22, 1989. The snow was unusually dry and powdery. The December 1989 freeze was really cold that hit single digit! The last time that happened was in January 1930 and February 1899. Notice the deep trough is east of the Rocky Mountains. Areas east of the Rockies were bitterly cold that time.

December 24, 2004
The first time it snowed on Christmas Eve. Areas around Victoria saw up to 13 inches of snow! Talk about a Christmas miracle right there! Believe it or not, computer models pick up on this event 16 days before it happened.

The Christmas Eve Miracle snow is cold up to 18,000 feet. At 30,000 feet, it is unusually warm.

12/22/2004-61/35
12/23/2004-43/31
12/24/2004-37/31
12/25/2004-49/32
12/26/2004-59/28

Here is the geopotential height map.

Two days before it snowed, it hit a high in the mid-60s. From there, it gets colder, not bitterly cold, even by Houston standards.

December 10, 2008
It came just several months after Hurricane Ike ravaged Southeast Texas. It was dubbed as the “surprise snow” because computer models did not pick until just days before it snowed.

The layer of cold air in the December 10, 2008 snow event is very deep. It is even unusually cold at the 30,000 feet level. Interesting to note that the abnormally cold air over Texas is surrounded by unusually warm air, especially starting at the 5,000 feet level. When it snows in Houston, it is usually cold nationwide, with the exception of this one.

12/8/2008-72/45
12/9/2008-78/43
12/10/2008-43/32
12/11/2008-56/33
12/12/2008-64/32

Here is the geopotential height map.

Just two days before  and after it snowed, it was warm. In fact, it almost hit 80 just the day before it snowed. The low pressure system that gave Houston snow had a deep layer of cold air. Also unusual, Houston was one of the only location that had snow on that day! Strange.

December 4, 2009
The earliest snowfall to be recorded in Houston history.

The layer of cold air for the December 4, 2009 is deep. It is unusually colder than other snowfall events in Houston.

12/2/2009-52/46
12/3/2009-56/39
12/4/2009-46/31
12/5/2009-49/26
12/6/2009-59/36

Here is the geopotential height map.

February 14-15. 1895
There is no temperature map and 500 millibar level geopotential height map from February 1895. However, I did find these weather maps and shows there was a high pressure over the Canada/American border centered in Montana.

A upper low pressure system from the west, likely a powerful one draws moisture from the Pacific and Gulf of Mexico. The low pressure system is likely a large one since, snow fell in a large area from Mexico, Texas, Louisiana, and Alabama. I would imagine that the layer of cold air was deep. Here is the temperature result from before, during, and after the snow. Just a week before it snowed, there another powerful Arctic blast. Everything was just right, a deep layer of cold air and a potent upper level low pressure system.

2/7/1895-21/11
2/8/1895-33/10
2/9/1895-40/23
2/12/1895-37/25
2/13/1895-37/25
2/14/1895-28/25
2/15/1895-33/24
2/16/1895-36/13
2/17/1895-45/16

What does this tell you? It does not have to be bitterly cold for Houston to see snow. The cold air has to be deep, not shallow, which often hits Houston. Most cold air masses that hit Houston are the shallow air masses, which is cold up to at least 5,000 feet. For snow to fall in Houston, the air has to be cold from 5,000 feet and above. Also, for snow to happen, there has to be moisture and often they are caused by upper level disturbances that come from the west. They originate in the Pacific Ocean. The timing has to be right, deep layer of cold air and moisture and something to lift it up. Also, a major Arctic blasts is not necessary to have snow falling in Houston.

Next time, I will look at climate patterns that allow snowfall in Houston.

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3 thoughts on “Snow In Houston Part 1

  1. I have pictures of my family’s house in Bellaire with several inches of snow in early March of either 1959 or ’60. I remember it because my mother’s birthday was March 5 and she kept commenting that she never thought she would see snow on her birthday in Houston.

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