Monday, January 6, 2014

The Meteorologist Rants...

Yes, I agree... we need to get a good ground-covering, snow angel-making snowfall!  Not because I like to throw snowballs (though I do), or my kids like to play in it (they do), or because snow days rock (hey, most of you are getting out tomorrow anyway!) - but to get some of you off our backs.  "Our," as in your local meteorologists (and yes, I'm speaking on behalf of a small, fairly tight-knit industry without their permission).

You know we're in Sales, not Production, right?  We don't make the stuff that falls from the sky, and contrary to what some of you think we don't have a direct line to the Creator, or Mother Nature, to "dial up" a snow storm (even though we occasionally pretend like we do). Trust me, if we did, we wouldn't be spending hours agonizing over computer model data and trying to figure out the influence of the bluffs, the Pyramid, and I-40 (I kid...).

Technical explanation for Sunday's lack of snow

In the case of this past weekend, I knew several days in advance that Sunday was going to bear watching. I saw model data that predicted up to a couple of inches of snow 2-3 days in advance of the storm and tried to balance that with the local knowledge (something the national personality and some app with millions of downloads doesn't have) that the particular setup doesn't favor a couple of inches of snow in these parts. When a massive cold front sweeps through the South in winter, it's very typical for the cold air to chase the moisture.  If it catches up with it, which occasionally happens, we get a little snow. More often that not, we get what we saw Sunday - light snow that didn't accumulate.

This event was a little different in that a low pressure system was going to move northeast along the front and right through our area. Personally, I thought the models might have been on to something when all agreed 2 days in advance that the low would move by just east of Memphis, thereby bringing in the cold air (sufficient for snow) by about noon. Precip after that time looked sufficient for minor accumulations, perhaps up to an inch. By Saturday, models were back-pedaling, showing the low going by to our WEST. This meant a 2-4 hours delay in the arrival of the cold-enough-to-snow air.

Sure enough, as models continued on that trend, I reduced our snow accumulation forecast. In fact, I showed the graphic below on Facebook and Twitter Saturday with the comment that the snow total in that model (the NAM) was "potential" and that we thought it was a "high end estimate." By Sunday morning, the MWN Forecast was down to "possibly 1/2 inch" accumulation.  We ended up not even getting that.

So the problem on Sunday was not the amount of moisture or the timing of it, but the delay in arrival of cold air.  For instance, MWN in Bartlett received 0.43" of rain Sunday prior to a change to snow at about 3:00pm.  The amount of rain that fell between noon and 3pm was 0.20".  If the change to snow had occurred at noon, as we thought a couple of days earlier, we would have been making snow angels in 1.5"-2" of snow late Sunday afternoon.

The rant

Despite big gains in recent years, the science (more like art, really) of meteorology is not advanced enough to pinpoint exact snow totals or where tornadoes will hit days in advance. It's like predicting the top 10 finishers in a NASCAR race with 43 drivers.  Possible, but highly unlikely. We (most in the industry) work hard to give the BEST information possible given the knowns and unknowns and using our local knowledge and experience.

Having said that, I feel it's ALWAYS better to be prepared and NOT have disaster happen, than to miss a high-impact event. However, this doesn't mean we forecast worst-case. While I personally am always looking to improve based on additional experience, I will not apologize for doing my best to tell you what I expect to happen, my confidence in that forecast, the impacts that could occur, and how you should be prepared. The information we as meteorologists have to examine is getting better (and more voluminous) all the time and our experience and knowledge grow with each event, but we are NOT perfect and never will be. I do promise to give you the facts, NOT hype, and help you to "be prepared, not scared." If disaster doesn't happen, count your blessings.

To end, here's the best suggested response I have seen to someone who wants to throw the first stone, courtesy of Jon Acuff, author of "The Hater Handbook":

Thanks to so many of you for your encouraging words. But I don't do this for praise, I do it because it's what I love. Now to go check the latest data on that freezing rain potential Thursday morning... :-)

Erik Proseus
MWN Meteorologist

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