Saturday, June 4, 2011

Calm Before The Storms


The recent severe weather in the southeast and midwest has subsided, at least for now. Here in Colorado, we have not seen many violent storms so far in 2011. What is the reason for this? One probable culprit is La Nina. While most of us meteorologists caution against blaming local weather patterns on global phenomena, in this case I feel the need to point to La Nina for our unusually calm and cool May.

NOAA and the National Weather Service do an amazing job of tracking the El Nino/La Nina pattern. The latest data shows that La Nina is continuing to weaken, and sea surface temperatures in the eastern Pacific are rising. For most of the early spring 2011, the Jet Stream was draped across California and on through the southern parts of the USA. This gave Colorado some much-needed moisture, and cool temperatures. All that is about to change.

As La Nina continues to weaken, we can expect the Jet Stream to be pushed farther north, with expanding high pressure over the Great Basin. For Colorado, this has several important implications. First, we should see temperatures begin to warm rapidly. This will melt the significant snowpack in the mountains, and could cause river flooding. Second, weather disturbances may dip across northeast Colorado from the Pacific Northwest, causing an increase in thunderstorms over the plains. This means wind, rain, hail and possibly tornadoes.

Colorado's peak severe weather season is late May through the end of June, however we can experience severe thunderstorms all the way into October. Most of the latest data on La Nina points to more precipitation over Colorado as we head into June.

This is good news for storm chasers, such as myself. Those of us who venture out onto the plains in the spring and summer to photograph and video severe weather are looking forward to the month of June. One important caveat to this is my personal hope for the safety of everyone on the plains. Most storm chasers do not want to see people hurt or killed, or property destroyed. I even worry about livestock exposed to hail and lightning.

If you've been intrigued about this year's EF-5 tornadoes in the south and midwest, you may be thinking about going out on your own to chase thunderstorms this summer. I'm going to repeat some information I posted here in 2009 about "Safe Chasing":

1.) Learn all you can about severe weather before you go out.
2.) Chase with an experienced partner.
3.) Do not stop on the road. Slow down and pull way off to the side.
4.) Use your flashers when stopped on the roadside.
5.) Do not speed through small towns. Besides the possibility of running over a
small child, local law enforcement is usually wary of storm chasers and they will bust you.
6.) Avoid eating while driving. This is an unnecessary distraction.
7.) Do not text or blog while driving. Yes, I have seen chasers doing this!
8.) Get a hands-free cell phone headset or earpiece. You need both hands to drive.
9.) Don't core punch your first time out.
10.) Save your camera and video recorder for when you stop.
11.) Watch the other chasers and drivers around you.
12.) If someone is driving recklessly, report them.

Those of us who have years of storm chasing experience are not trying to discourage new chasers. What we are trying to do is keep you, and everyone else, safe.

Whether you are interested in chasing storms or not, you should be very aware how fast Colorado's weather can change. If you check the forecast once a week, you are going to miss some important information. We at Channel 7 keep a very close eye on changing weather, and we encourage you to watch our weathercasts, and check our website every day for the very latest information and safety tips. I can be reached at steve.hamilton@mac.com if you have any questions at all.

Thanks!