Is Sandy a Threat To the DMV?

Hurricane Sandy, which rapidly intensified over the past 24 hours, is currently in the Caribbean and moving north and northeast between 10-15mph. It's forecast to continue this northward movement over the next few days toward the Outer Banks of North Carolina (see graphic below), but the forecast becomes highly uncertain after that.

Facts Worth Knowing About Tropical Storms

Satellite image of Hurricane Rafael, courtesy of NOAA

Here we are in the middle of October, well past the peak of the tropical storm season. Yet, the final advisory for Hurricane Rafael, the 17th named storm of the season, was just issued yesterday. The actual peak of the season happens on September 10th, and the season officially ends on November 30th, but the number of tropical cyclones rapidly declines after the September 10th peak. Here are some other interesting facts from the Atlantic Basin:

1.There are more storms beginning with the letters "I" and "C" that have been retired than any other letter. Since 1954, when the naming convention became official, 9 "I" and "C" named storms have been retired. Of course, 2011's Irene is one of these retired names. 

Freeze Watch Tonight

The National Weather Service has posted a Freeze Watch for essentially everyone north and west of DC tonight.


Freeze Watch map, courtesy of our local
National Weather Service office

With cool, dry air in place right now, temperatures will drop quickly tonight after the sun sets. A Freeze Watch is posted whenever temperatures are predicted to dip below freezing, thereby ending the growing season.

Zonal Flow: More Than "In-Between"

Most of the time, weather forecasters focus on the placement of atmospheric troughs, which bring colder weather, and ridges, which warm us up. But what about the weather in-between? When there aren't any large synoptic (large-scale) troughs or ridges in our atmosphere, it is called a zonal flow. 

A 500mb analysis chart depicting zonal flow east of the Rockies.
From the College of DuPage Weather Site

Is the South the New Tornado Alley?

As we enter October and the severe weather season essentially shuts down, I am breathing a sigh of relief that this year's severe weather season was fairly tame in comparison to 2011. Of course, in the DC Metro area we had the devastating derecho, an event that was basically unheard of in this part of the country before this summer, but the entire country was largely spared from destructive weather in the form of severe storms and tornadoes.

2011 was the 2nd-most tornadic year on record, according to the National Oceanographic and Atmospheric Administration (NOAA). The map below shows all 1,691 confirmed tornadoes, including long-track tornadoes, from last year.

Confirmed tornado reports from 2011,
courtesy of NOAA