Weather Blog

Coldest winter in a generation (but not here…)

Coldest winter in a generation (but not here…)
Icicles cling to Florida oranges in a grove Monday, Jan. 11, 2010 in Dover, Fla.

You'll continue to see a lot of national news attention placed on the extremely cold weather back east.

There are two reasons for this: There's always a national news bias that favors East Coast stories, but the other reason is that it is really darn cold.

How cold? How about -30 degrees in Iowa. Wind chills below zero in Louisiana. Single-digit overnight low temperatures in North Florida. A killing freeze for the Sunshine State's citrus crop. Even parts of South Florida woke up to frosty cars this morning.

What's even more striking is how mild we have been in Western Washington compared to the rest of the nation. Relative to "normal" in early January, Seattle is the warmest place in the country right now.

Check out these stats:

Average Low Temperature This Month:
 - Atlanta, GA: 19 degrees
 - Orlando, FL: 34 degrees
 - Seattle, WA: 43 degrees

Snowfall So Far This Winter:
 - Ft. Lauderdale, FL: Trace
 - Seattle, WA: Trace

Here's the best stat I can find:  Earlier this morning, Key West (the southernmost city in the Continental U.S.) had its second-coldest morning ever at 42 degrees. At that same time (4 a.m. PST), Bellingham was 61 degrees. That's crazy!

So what's going on?  We're warmer than Florida? Right now, we are… and it's all due to the jet stream.

The jet stream is literally a "river of air" that flows across the country from west to east, and ripples, or kinks, in the jet stream are usually the reason why our weather gets much warmer (like us) - or cooler (like back east) - than normal.

Take a look at this map from this morning:



This weather map shows the flow of air at the 300 millibar level - up where commercial planes fly - and where the strongest winds of the jet stream are found. Two things stand out to me:

 - First, look at where our weather is coming from. Given that the jet stream moves from west to east, you'll easily see that our weather is coming up from the south. We're literally tapping into the tropics and that modified tropical air is giving us the warm and wet conditions outside today.

 - Now look at what happens after the jet stream moves over the Northwest. It flows all the way north into the upper reaches of Canada, then dives down all the way to the Southeast. So, the air over Orlando this morning literally came from the Arctic.

These two jet stream features go hand-in-hand. There needed to be a ridge of high pressure somewhere to kick the jet far enough north to tap into the Arctic Air. No ridge, no cold… it would all still be in Canada.

So if you have any friends back east - and they're complaining about the cold - let 'em know that not only are we warmer here, but we're (kind of) the reason why they are so cold!