Snow in March? Sure, in Minnesota! As many of you know, we were graced with the sight of snow on Friday morning...something we thought only fell somewhere north of Texas. Now, snow anytime of the year in southeast Texas is rare; but in March? It can happen. There have been times in years past where we have had snow in March. The last time we've had snow/sleet this late in the year was well....last year....the night before Easter as of a matter of fact, on April 7, 2007. But again, snow in southeast Texas is rare. In fact it is so rare that the last time Bryan/College Station had an inch or more of snow on the ground, anybody who was born after January 3, 1985 has never seen it. That's because the last recorded snowfall of 1" or more was on January 3rd, 1985. We have had trace amounts since then. What's ironic about the whole thing is that Houston has had more snow in recent years than we have. Let's look at the situation a bit closer.
In order for it to snow, you need two things--moisture and cold air at all levels of the atmosphere. That's easier said than done thanks to the Gulf of Mexico. So in order for it to snow here, the timing must be perfect. Most snow events happen the same way. What has to happen is a strong cold front will bring very deep cold air into the state. As seen on Friday, the temperatures do NOT have to be below freezing at the surface to snow as long as the atmosphere itself is below freezing at all layers. Confused? Let's look at it this way. In December and January, many mornings we have frost on the ground and the roofs even though the temperature being reported may be 35 or 36 degrees. That's because there is a very tight temperature gradient next to the surface. That means that temperatures right at the ground may be below freezing and then quickly warms just a foot or two above the ground. If this is the case in the atmosphere where the surface is cold and the above levels are above freezing then you get a cold rain, sleet, or the worst of the three...freezing rain. This is normally what our precipitation consists of thanks to that warm layer.
Back to the snow...now once we have the deep cold air (extending above 5,000 ft.), then you need the moisture. Well, here in southeast Texas we hit another problem. By the time it gets cold enough to snow, the air is either too dry or the moisture is well east of here. What needs to happen, as in the case of Friday, we need a low to develop and move into the cold air. Last Friday, a low did in fact develop out in west Texas and proceeded to move in a east-southeasterly direction. As it closed in on southeast Texas, it began to interact with the gulf moisture and the snow bands began to form. Up to an inch of snow was reported in Centerville, Hilltop Lakes, Waco, and several other locations. Officially here in B/CS, only a trace was picked up. That basically means a couple of snowflakes managed to find their way into the measuring bucket.
The situation above is exactly what happend on Christmas 2004, when Brownsville picked up its first snowfall in 105 years! 13" was reported in Victoria, TX, Galveston reported 5" with some reports of 8", and Houston recorded its first white Christmas on record. So why didn't we get any? After all, we're further north! Though we were cold enough, our dewpoints were down in the teens and twenties. That is very dry air and any snow that would have fallen evaporated before it reached the surface. Not to mention, we were away from the moisture source. Though it looks like Ol' Man Winter has paid his last visit to the Brazos Valley this year, after what happened last year in April, you learn to NEVER say never. Best of luck with the snow next year!
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