Prepare now for Sheppard winter weather

SHEPPARD AIR FORCE BASE, Texas -- When you found out you were coming to Sheppard the first two things people mention weather-wise are the triple-digit temperatures in the summer and the severe thunderstorms and tornadoes that happen across the area, both of which are true. However, what they often forget to mention is that Sheppard and the Wichita Falls area can also experience winter weather, specifically snow and freezing rain.

On average, Sheppard experiences about six inches of snowfall each year, with the majority of snow falling in one or two winter storms each year.  Now, if you're from the midwest like me, you're probably thinking, "a couple inches of snowfall, what's the big deal?"  The problem is since Sheppard doesn't experience winter weather very often, we don't really have the snow removal infrastructure that you would see further north; a couple of inches of snow at one time can, and has, crippled the local area.  Therefore, it is important to be prepared as we enter the winter season.
  
Speaking of winter weather, what is the weather community expecting for us this winter?   Well, most of you have probably heard your local meteorologist throw around the term "El Nino."  In a nutshell, El Nino causes warmer sea surface temperatures than normal in the Pacific Ocean, especially along the equator. This has a dramatic effect on atmospheric circulation patterns, which in turn affect our weather here in North Texas. One of these effects is that it allows winter storm systems to dip much further south.  

Currently we are experiencing a very strong  El Nino, which is being enhanced by what is known as the "Pacific Blob," a warming of the mid-latitude Pacific waters.  This phenomenon occurs right off the California coast and together gives us one of the warmest average sea surface temperatures in the Pacific on record. 

With all this going on, our experienced climatologists at the National Climatic Center are forecasting above normal precipitation for North Texas this winter, coupled with below normal temperatures.  Granted, above normal precipitation doesn't necessarily mean above normal snow; however, we do have to keep in mind that we are still a southern tier base and the difference between rain and snow here can come down to a temperature difference of 1-2 degrees. Then again, our last big winter El Nino occurred in 2009-2010 but wasn't as strong as the current one. Even then, we got hit with a snow storm on Christmas Eve in 2009 that dumped 7 to 10 inches of snow across the area.

Well, all that weather stuff is good to know, but what can we really expect here and how much warning are we going to get before a major winter event?  First of all there are a lot of variables when it comes to weather forecasting.  I know, I know, here we go, the weather guy being all wishy-washy. But in truth, there are many variables, and unfortunately we can't account for all of them.  But the good news is that with new technology and better forecasting models being developed each year we are getting more and more accurate, particularly in long-range forecasting.  Current weather forecast models now give us a pretty good idea of what's going to happen anywhere from 5 to 10 days out, keeping in mind that the closer we get to that 10-day range the greater the potential for error. The reason for this is the old "Butterfly Effect," better known as the Chaos Theory.

It's no accident Dr. Edward Lorenz, the father of modern day computer weather forecasting, is also the father of modern day Chaos Theory.  While developing the first weather prediction models he found that very slight changes in initial model inputs could bring about major differences in the potential solutions as they become amplified over time.  Essentially, weather forecast models predict future weather by first taking the known current state of the atmosphere and then using the laws of physics to predict how the atmosphere will change over time. 

The key to successful weather forecasting is being able to provide an accurate current atmospheric state to the model. Unfortunately, that's nearly impossible because there is no way for us to account for every particle of air out there.  We just don't have the computing power or sampling ability to do that, so instead we have to make certain assumptions based on the data we do have.  This then leads to a certain amount of variance, or uncertainty in the solution, especially the further out we go.  

To decrease that uncertainty somewhat we now use what's known as ensemble forecasting.  Basically, we run a model several times tweaking the inputs slightly. This allows us to get a better idea of the amount of potential variance in a solution. The less variance we have the more confidence we can have in the solution, and the inverse being true with greater variances. 

Yeah, yeah, the weather guy is already making excuses.  Well okay, maybe a little.  But in all seriousness, once we see the potential for a major snow event, between 5 and 10 days out we normally monitor the models for a couple runs each day.  This allows us to build confidence in the solution.  Once we are relatively confident in the probability of a certain event occurring, we notify base decision makers and the base populace in general, giving folks time to plan and prepare. 

Keep in mind though, things change! As new data comes in the forecast could end up changing several times. One of the big reasons is because of what I mentioned earlier:  the difference between rain and snow here sometimes comes down to just a degree or two.  In effect, this means a forecast for an inch of rain could turn rapidly into a forecast for 10 inches of snow as each tenth of inch of rain equates to about an inch of snow.

Once we're relatively confident the winter event will occur, the Sheppard weather flight, together with the 26th Operational Weather Squadron, Barksdale Air Force Base, La., will begin issuing watches and warnings for the event.  Normally the initial watch will be issued anywhere from 12 to 24 hours prior, and then will be upgraded to a warning around 2 hours prior to the event.  I know that doesn't sound like a lot of time, but remember:  once we see the possibility of an event we're already in contact with base leadership and are continually updating them. The watches and warnings are just the final icing on the cake.

So what can I do to prepare myself? Well first off, now is the time to go out and procure that snow shovel and stock up on salt, because let me tell you from personal experience, if you wait until you actually need it, you won't find a snow shovel for sale within 100 miles of here. Same can be said for the salt.

In addition to the snow shovel and salt, you also might want to consider putting together a winter survival kit for your car, which includes some warm clothes, gloves, boots, and maybe even some sand in case you get stuck. Remember, limited snow removal equipment is available, so primary roads normally get cleared, but secondary roads normally don't.

Once you start hearing about the potential for a snow event make sure you continue to monitor the local media channels.  Normally, when it comes to an event like this, we're all on the same sheet of music. You can always call us here at the Sheppard weather flight at (940) 676-2730, or stop by and visit us and take a look at all the neat tools and graphics we have.  We're located in the Air Operations Center, Bldg. 1903, right next to the air traffic control tower.

So in summary, I'm not saying we're guaranteed a major snow event this winter season, but historically the majority of big snowfalls have occurred during El Nino years, like Christmas Eve 2009, so I'd be prepared just in case.