Weather Extremes of 2010

I enjoy reading Jeff Masters' blog. He is a co-founder of Wunderground.com, certainly the best U.S.-centric non-government weather web site. Recently, he has been quite busy due to all the extreme weather we've been having in the U.S. and around the world. Though 2011 has already brought a new wave of amazing weather events (e.g. Mississippi flooding, Japan earthquake), he took the time to put together a retrospective of the incredible weather extremes of 2010, including Snowmageddon, the hottest year on record, and the wettest year on record. It's an excellent summary of an unprecedented year. He dug up pictures for all the major events to highlight the events. As usual, it's a great read.

OMG! First Lightning Picture!

I realize this sort of thing is old-hat to some. But, it's pretty exciting to someone who has never captured lightning before. :-) We've had a moderately severe storm rolling through Massachusetts today. A tornado touched-down in Springfield and lightning has been recorded across the state. I say "moderate" because I grew up in Oklahoma and I know what the scene around a severe storm looks like---nothing is left behind. Here, a few buildings were damaged and a few people were killed. Nothing like the storm that hit Joplin, MO. Anyway, I was in the gym during the first round of the Mass. storm, but after I got home, another round of thunderstorms rolled through. We've had a Nikon D50 SLR for a number of years now and I've familiarized myself with shutter-speed and f-stop, so I decided to try my hand at capturing a lightning bolt. After futzing-around, I settled on a shutter speed of 30 seconds, manual focus, little-to-no-zoom and a 13 f-stop. After a few minutes of taking pictures out of our dining room window (which doesn't have a screen), I got one. I couldn't believe it!

FWIW, the rain was pretty strong with this storm. My weather station recorded .63 inches of rain in 20 minutes, a rate of 1.89 inches/hour.

Blizzards

It's nice to see that Wikipedia chronicles recent blizzards. We sure have had a lot of them lately! Here are the North American storms from the 2010-11 winter:

• December 2010
• January 8-13, 2011
• January 25-27, 2011
• January 31-February 2, 2011

Here are the storms from the 2009-10 winter:

• December 16-20, 2009
• December 22-28, 2009
• February 5-6, 2010
• February 9-10, 2010
• February 25-27, 2010

I recall being disappointed that the 2010 February storms missed the Boston area. Now that I know a bit more about ice dams, I really don't mind so much when big storms miss us!

North Atlantic Oscillation

The National Weather Service has a page showing the current status of major weather oscillations around North America, including the Atlantic Oscillation and North Atlantic Oscillation. The Atlantic Oscillation has been (strongly) negative from late November 2010 through late January 2011. It has recently lifted to positive territory. This has been quite noticeable around Boston as temperatures have warmed a bit and the pace of Nor'easters has slowed.

Don't Forget the Satellites

At a time when more Earth and weather observations are needed, not less, the U.S. government has been cutting back. Jeff Masters wrote about the demise of the QuikSCAT satellite. The NYTimes more recently raised the issue with the demise of the ICESat satellite. With the government in cut-back mode, we may soon lose more important weather satellites and lessen our ability to accurately predict weather phenomena, such as hurricanes. This is one area where the money is clearly worth it---weather satellites save lives by providing alerts of dangerous weather events. This is especially important since we are in a phase of heightened hurricane activity and global warming may be increasing the frequency and/or intensity of hurricane storms.

Pressure: Converting between millibars and inches mercury

The two commonly-used units for measuring atmospheric pressure are millibars and inches mercury. My Davis Vantage Pro2 weather station reports pressure in inches mercury and millibars are the typical measurement used for recording hurricane pressure. A normal millibar reading is 1000; an extreme measurement is 925. A normal inches mercury measurement is 30.0; an extreme measurement is 27.3. The Wikipedia pressure page provides a relatively easy conversion path via torrs. One millimeter mercury is equal to one torr, so one inch equals 25.4 torrs. One bar is equal to 750.06 torrs, so one millibar is equal to 0.75006 torrs.

Conversion from inches mercury to millibars simply amounts to conversion to millimeters/torrs, then conversion to millibars. The first involves multiplication by 25.4; the second involves division by 0.75006. The net scaling factor is 33.864. Conversion from millibars to inches mercury is simply the reverse calculation, so it simply involves multiplication by 0.02953.

So, 1000 millibars is equal to appx. 29.53 inches mercury. 30 inches mercury is equal to appx. 1016 millibars. A half-inch of mercury is equal to appx. 17 millibars. Here's a quick lookup table:

in Hg	mb
30.0	1016
29.5	999
29.0	982
28.5	965
28.0	948
27.5	931
27.0	914

Update (10/26/10): It's useful to note that a hecto-Pascal (10² Pa) is equal to one millibar (10^-3 bar). Equivalently, one bar is equal to 100,000 Pascals (10⁵ Pa).

Down 32 degrees in 43 hours

After watching New England weather closely for a year, I've seen some wild temperature swings. But, one thing I rarely see is wild swings in the dew point. The dew point tends to be quite a bit more steady than temperature. But, with the latest storm that rolled through, I saw an amazingly large change in dew point---30 degrees in less than 48 hours. The remains of Tropical Storm Nicole made its way to the Boston area Thursday, September 30th. This pushed the dew point up to 71.9F degrees at 12:40pm on Friday, October 1st. I had to turn the air conditioning back on even though we had seen a low temperature of 42 just a week prior! The storm dumped .64 inches of rain then departed out to sea, taking all the humidity with it! The dew point fell quickly, bottoming out at 39.6F at 7:30am on Sunday, October 3rd. So, the dew point dropped 32.3F degrees in just under 43 hours! We had to turn the heat on this morning after having the A/C on just two days ago. Phew!