Wednesday, January 23, 2008

Some Interesting Weather Observations

The cold, cP air that covered the region last weekend presented some pretty interesting opportunities to explore some of the atmospheric phenomena we study in earth science classes. When a colleague in New Hampshire sent the image of Mt. Washington ("Home of the World's Worst Weather), I began looking at data from the area where the photo was taken, and from the summit of Mt. Washington. What I soon realized was that in this fairly uniform and stable air mass, I could predict the temperature at the summit based on observations at the location where the photo was taken. That night, temperatures on the summit dropped to -31°C - cold to be sure, but not as cold as it might have been.
The two exercises below will help you understand what was going on.
Mt Washington, NH Weather Part 1 and Part 2 (solution to Part 1)
See the solution to Part 1 only if you are stuck (or want to check your answers). You can email if you want an explanation of Part 2.

Tomorrow, I'll post another quick exercise involving the heating and cooling of descending and rising air.

Monday, January 14, 2008

False Alarm on the Big Snow?

Kind of a false alarm on the snow, eh? Look at this weather map from Sunday night into Monday morning (Click the map if you can't see the animation). Subtract 5 hours from the time displayed at the lower left for NY time, and notice that the storm center stayed well out to sea, "wasting" a lot of good snow on the ocean!
A small change in the track of the storm can make a huge difference in the weather a particular area experiences.
Oh well, you got your 2 hour delay in SE NY this morning, right?

Sunday, January 13, 2008

Nor'easter for us this week!

It's been a while since I've posted anything here - so here's wishing you all a belated Happy and Healthy New Year. I've enjoyed seeing some of you during my brief visits to Fox Lane, and hope to see more of you when I'm there again.

A strong low pressure system is developing off the coast of the SE US as I write this, and by this evening it will have moved northward toward the NY area. It is predicted to remain off-shore, so we will be in the easterly and then northeasterly* flow of moist air circling counterclockwise and in off the Altlantic around the low.

Check out the current and forecast weather maps at Accuweather.

That relatively warmer and moist maritime air will override the cooler air already in place over us (remember, warmer and moist air is less dense than cooler, dry air), and as it rises, expands, and cools the moisture in it will condense and fall as snow through the cooler air below. As of noon today (Sunday), the national weather service is predicting 8 to 12 inches of snow in our area.

As the low moves northeastward out to sea tomorrow afternoon, we'll experience a shift in the wind to the northwest, ushering in a little cP from Canada, and another low that's currently spinning around the Great Lakes.
Read more about the developing storm at the Accuweather web site, and check for school closings or delays at your school web page or, in SE New York here
*That's why it's called a nor'easter!