Sunday, June 30, 2013

Mission #7: Scattered Convection Over Connecticut

The DREAMS Project completed another mission out in the field on Friday, June 28, 2013. Their goal was to study scattered convection (i.e. thunderstorms) that was, yet again, forecast to develop throughout the daytime hours and into the evening. The targeted location was Cedar Beach in Mount Sinai that had a clear view over the Long Island Sound into Connecticut. The students were able to measure the scattered thunderstorms that developed, gain an appreciation for the low-level marine boundary layer and possibly measure the smoke and debris from a fireworks show. A combination of interesting things being picked up by the DOW and incredible public interest kept the DOW at the beach for just under 12 hours! We had thought we were going to be kicked out of the parking lot at one point, but the Public Safety Officers were just very curious about our project.

The forecast for Friday was very similar to the forecast for Thursday regarding the uncertainty of where and when the scattered convection, or thunderstorms, would develop and how far they would travel. The ingredients (moisture, instability, and lift) looked to be most promising in Connecticut. There was a lingering convergence boundary situated there that could likely provide the lifting necessary to fire up the storms. The decision was made to target afternoon convection with Cedar Beach as the chosen location because of its great view to the north and northwest. The DOW left Stony Brook University at 12:15 PM and the pod and radar were set up by 1:30 PM. By that time there were already large, developing cumulus over CT that the DOW was able to scan. The reflectivity data showed that the clouds extended very high and were filled with large droplets and the velocity data showed that the storms were moving away from the radar towards the northeast. 

DOW at Cedar Beach in Mount Sinai for Mission #7.
SBU Student Danny C. manning the DOW.
Students set the DOW to take PPI scans, or horizontal scans (PPI stands for Plan Position Indicator), and then once they determined where a storm was they set the DOW to take RHI scans, or vertical slices (RHI stands for Radar Height Indicator). By doing that, they were able to really dissect a particular storm.

Long Island had two of the ingredients for convection (lots of moisture and a fair amount of instability or CAPE) but it was missing the lifting mechanism. Wind was blowing from the south for most of the day so the air was very moist. There were a lot of cumulus clouds that were thin and shallow, or near to the ground, that were forming due to the existence of a moist marine boundary layer, or air close to the surface that can freely rise without much help from any other atmospheric lifting mechanism (like a front). Throughout the day storms were developing over NJ that moved, very slowly, to the northeast that we were eventually able to measure.

Anvil overhead during sunset.
Mammatus observed at Cedar Beach.
The first part of the storm over NJ that came to us was the anvil cloud. The anvil cloud forms when air that is carrying a lot of moisture rises into the developing storm and reaches a level where it faces resistance to rising any more so it instead spreads out horizontally. The anvil usually spreads out downwind of the storm, which is why we could see it so far east when the storm was so far to our west. There was an interesting feature on the underside of the anvil cloud that we saw when we looked up at around 6:00 PM. It is called mammatus and it looks like the cloud has bubbles, or udders from its literal Latin translation. When there is mammatus, it means that at the level of the cloud there is a lot of unstable motion of air. That means that the temperature and moisture of the air in the cloud is not as resistant to upward and downward movement so it moves up and down to give the strange bubbling appearance.

A lot of people wanted to check out the DOW.
There was a lot of public interest in the DOW while we were parked at Cedar Beach. We really do encourage everyone to not be shy and come and ask us what we are doing! Part of the DREAMS Project is to perform public outreach by educating and sparking an interest in weather and the really interesting tool that is visiting Long Island to study it. Long Islanders know that they experience really unique and interesting weather, so all the more reason to come and say hello when you see us! Because of the large amount of interested people asking questions and the active weather to our west, we remained at Cedar Beach until about 11 PM. In doing so, we were able to see a fireworks display to our north over CT. After the display finished, some students claimed to have been able to measure some of the smoke that was created from the festive explosions because there was an area of higher reflectivity values near that location. Even though we have the 4th of July marked as a “down day” aka a day off, now we are kind of curious what the Macy’s fireworks display in NYC would look like measured with the DOW!

After a very long day of sampling some storms, the DREAMS Project members felt very satisfied because despite not having any strong storms nearby, the curiosity of the public and the eagerness of all of the students to stay out late was invigorating. Hopefully we'll catch some strong storms or a great Long Island Sea Breeze case one of these days before the DOW leaves town, but at least we are all enjoying our experience!

DOW at Cedar Beach after a long day of scanning.

For more information about mammatus clouds, please see the following websites:

1 comment:

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