Wednesday, December 22, 2010

December 21st - Urban Wildlife & Full Lunar Eclipse

I was hanging out with Skinner last night and our plan was to go check out the lunar eclipse. I picked him up in Aurora and on our way out of the parking lot, he says to me: "Dann, is that a deer?"

"It's probably some Christmas decoration," I assured him.

"No really, I think it's a deer."

I look over to my left and sure enough, there is a mule deer on the grass median between the road and sidewalk. Of course, we had to investigate. I flipped the car around and Skinner got out, ready to stalk the deer. In my head, it seemed like one of Santa's elves was trying to break a reindeer. The picture speaks for itself:

The doe walked through a few trees and we decided to pull into the parking lot behind her and see if we could get a good picture. Finally, we spotted her again and she didn't seem too alarmed. I actually set up my tripod and approached her for this picture. If I recall correctly, I wasn't zoomed in. I was only about twenty feet from her.

While I was watching her, I felt like I was being watched and not by Skinner! I turned to my right to see at least six more deer standing in the shadows, about twenty five feet away. Keep in mind that we are in the middle of Aurora and not on the outskirts or in the foothills.

I tried to get a good photo, but they were on the move; not cooperating with my longer exposures. I fell in behind them as they slowly moved and found it interesting that I could *smell* them. There were also two bucks in the group, one of which was an 8-10 point! Finally, they stopped and posed for a while.

Ghost deer.

Buck in the center.

The herd crossed the street and since the moon was already being darkened by the shadow of the earth, we headed out on I-70 to Airpark to meet up with Hambone. It felt good to be eastbound on I-70 again, even if it was only an eclipse chase. When we arrived at Airpark and met Scott, there was a thin veil of cirrus over the area but it soon dissipated and by totality, we were in the clear. We tried to get some good shots, but I felt limited with my point-and-shoot. I did end up happy with the results though. We also posed for a few shots and observed a very fast moving plane leave a contrail over the sky. It was pretty cool! Actually, it was pretty cold. I would take a few pictures and then go warm up my hands. The light, biting wind in combination with my aluminum tripod legs kept my fingertips a-sting. As soon as totality rolled around, we snapped a couple of pictures and rolled out.

Here are a few shots from Airpark:

Crop of the moon near half-eclipse.


Skinner and Hambone taking in the view.

Group shot... wish I had a wide-angle to get the moon too!

Best shot I got of totality. Zoomed but not cropped. This is the full image.

This is a crop of another image, but a nice, close look at totality.

Between the deer and the eclipse, it was quite the eventful night... and it's always good to meet up with friends.


Monday, December 20, 2010

Weather-Related: December 20th, 2010

We haven't exactly been in a benign pattern across the United States so far in December. In fact, we've seen a few interesting events... most of which have been as far away from Denver as possible!

Yazoo: The Third Act
-Yazoo City, Mississippi can't seem to catch a break. The city had already endured two tornado strikes over the course of the year when it had another scare on December 11th. I was watching this storm closely as it moved through the area. It exhibited rapid rotation on radar (as seen below) and the couplet moved just south of the city. While no actual tornado was reported, there was some decent wind damage just south of town. Take a look at the storm relative velocities!

Ice In Havre
-On December 12th, Havre, Montana experienced some freezing rain. I thought this would be a good opportunity to demonstrate how this happens. Take a look at the image below. It is of a model (RUC) forecast sounding for the time period that Havre experienced the freezing rain. On the image, the red trace shows the air temperature as we move up in the atmosphere; the green trace shows the dewpoint. On the left side of the chart, the numbers show millibars (mb) or a measure of atmospheric pressure. Pressure recedes predictably for the most part as you move from the earth's surface upward. The most important thing to look at here are the diagonal lines. These show temperature in degrees Celsius. Obviously, the 0ºC line is the freezing point. You can see on the chart that from 870mb to 780mb, the temperature is above the freezing point. As we move lower than 870mb, or closer to the ground, the temperature is below the freezing point. Also notice that the atmosphere is saturated (or the dewpoint is the same as the temperature) up to 850mb. In this example, a warm, Pacific airmass has made it over the Rockies and is overrunning the very cold, dense continental polar air mass already in place. It is hard for this warm air to mix down into the dense, cold air, so the cold air can effectively pool below it. When precipitation forms in the above-freezing layer and falls into the shallow cold, sub-freezing pool, it freezes, thus freezing rain. Kind of cool, eh?

Denver Doldrums
-The pattern hasn't changed much locally. It has been warm and dry and we are still in wave cloud season. (Wave clouds at sunset pictured from my bedroom below). The metro area did receive a dusting of snow on the 17th, but it is all gone already!

-Took a trip out on the night of the 12th to Barr Lake to see the Geminids. This was actually the night prior to the peak, but I was near the edge of the metro area and my cousin and his friend were game to head out. Unfortunately, there was a wave cloud directly overhead which only gave us a few gaps to see through. We were there for about an hour and I saw 9... many less than others out the next night, but I considered it a successful trip. I took a couple shots at capturing one in frame, but struck out.

Radio towers and planes taking off from Denver International.

My cousin Brian laying out on several folding chairs, surveying the sky.

Aumsville Tornado
-Tuesday (the 14th) kept my attention all day as a rare tornado struck the town of Aumsville, Oregon. The tornado was spawned by a small supercell which formed in a favorably sheared environment in the eastern stretches of the Willamette Valley in Oregon. Fortunately, no one was injured by this tornado but there was quite a bit of damage. It was rated an EF-2 by the NWS (more info can be found here.

Side-by-side views of the 0.5º Base Velocity and Storm-Relative Velocity images. Rotation is evident in both images.

Of The West
-I took a trip west of the divide on Wednesday (the 15th) where there actually is some weather! Of course, the mountains have been doing a fantastic job of keeping the weather out west and not along the Front Range. It is still rather dry on the West Slope, however, so most of the precipitation impacts the mountains and leaves the valleys relatively unscathed. Let's just say that the drive back to Denver that night was a bit more interesting as Vail Pass closed in front of me. As I was exploring the town of Minturn, it reopened and I was on my way.

Evening light graces the sides of Grand Mesa as seen from Palisade, Colorado, while it's flat top is dusted with snow.

The interaction between the ascending air mass and the topography causes some interesting cloud structure, tinted pink by the setting sun.

In closing, I'm heading home to Montana for Christmas and to see my family. I'm very excited to see everyone and spend a couple days in my home town. Plans get a little more sketchy when I get back as I will likely be packing up and moving from Centennial! Don't worry, this is a good thing... but you will have to wait a while for details. See you on the other side.


Wednesday, December 08, 2010

Sunset Chasing in Denver, December 8th

We had another warm day here in the Denver-metro area. My thermometer in Centennial reached 57ºF and a couple observation stations in the region topped 60ºF. All day, a thick wave cloud loomed overhead and I figured we would have a stunning sunset.

I pushed my luck a bit as I had some things to accomplish this afternoon, but after running another demo to the post office (talented meteorologist will work for food/storms), I was actually a little disappointed that some cloudcover out west might steal the show. This disappointment worsened when the wave seemed to break up into a row of stacked-plate lenticulars.

Luckily, traffic wasn't too bad and the line at the post office moved quickly. When I got home, I figured I would head out to the open space east of my complex. I brought my tripod and saw a little color beginning to show on the plates. This got me excited.

Not two minutes later, the entire row lit up. It was breathtaking!

Look at all the stacks of plates!

It's been almost two months since I've heard thunder, but I do love wave cloud season here along the Front Range!


Saturday, December 04, 2010

Weather-Related: December 4th, 2010

Occasionally, I have a few news bits and notes that I want to talk about but don't necessarily warrant a full post, so I've decided to condense a few into one and just call it "weather-related". So, let's talk about the weather.

Unseasonably Warm!
- The Denver area experienced unseasonably warm temperatures yesterday, December 3rd. The airport (KDEN) tied a 100+ year record high of 69ºF thanks to the chinook winds which kept us warm. At my apartment in Centennial, the thermometer reached a high of 67.8ºF. You can bet I had my windows open in the mid afternoon, letting the dry but fresh air through my place. Some mesonet stations across the metro reached into the lower 70s at times, which was quite impressive. The normal high temperature at this time of the year is in the low to mid 40s.

What a Difference a Year Makes!
- I've only been taking obs at my current residence since September of 2009, so there is no use in keeping records for any specific date, but I think the monthly averages this year, compared to last are interesting. October was quite average (*compared with climatology for KDEN) this year with high temperatures averaging 66.7ºF. Compare this with last year's average of 54.0ºF. The lows followed a similar pattern with 45.2ºF and 32.7º respectively. In both instances, we are looking at a greater than 12ºF temperature contrast between years. That is significantly different, weather-wise. How does November add up? Well, we were actually a bit cooler this year than last. The high temperatures were 52.3ºF (2010) and 55.2ºF (2009) and low temperatures were 30.6ºF (2010) and 33.7ºF (2009). The high temperatures for both years were close to normal*, but the lows were a little on the warm side. It should be noted also that my thermometer is relatively close to the building, so it is likely thermally influenced, especially on colder nights. In this case, the most interesting data comes from comparing it to that of the previous year and not with other observations in the area.

Ron Santo
- Chicago Cubs player, broadcaster, and possibly the team's biggest fan, Ron Santo, died on the night of December 2nd. What does Ron Santo have to do with weather? Well, I spent many storm chases this spring and summer listening to his call on WGN radio, which Hambone would stream over his phone. Listening to Cubs games and especially his animated commentary was an integral part of chasing this year and it will be missed. Also, as a Cubs fan, his presence in general with the organization throughout the years will be missed also. Scott and I have decided that our first chase together next spring will be "Ron Santo Day."

I think that gets us caught up for now. It's much colder today in the Denver area as a cold front passed through late last night. No more highs close to 70ºF for us! It barely got above 40ºF today and it is still dry. Aside from a few dustings, it has been a long time since we've had any significant precipitation.