This is a week-long weather study I did back in February 2001. I received a 94% on it!
INTRODUCTION & DATA METHODS
The Blacksburg Weather Study is a personal explanation as to why the weather behaved as it did during the time that data was collected. Data was collected roughly four times a day for eight days (only three reports the first day). The samples were to be taken at least four hours apart, though several of mine were a little under do to class times and such.
The data collected was as follows: Temperature, cloud type, cloud cover, dew point, pressure, wind speed, wind direction, precipitation (rough estimates) and relative humidity.
Precipitation was a rough estimate of what we received. Obviously the type of precipitation was easily determined. Cloud type and cloud cover were based on estimates on looking out a window, which is why night time cloud data is not available. The remaining data came from http://weather.noaa.gov/weather/current/KBCB.html. This site is the National Weather Service's weather report for the Virginia Tech Airport in Blacksburg, VA. The site is updates about every hour.
EXPLANATION OF WEATHER EVENTS
February 19, 2001
Today, a high-pressure system was moving over our area. This is evident because the wind was high in the early afternoon, the sky was 20% covered with fair-weather cumulus clouds, and the pressure was fairly high. As the day progressed, the wind calmed down (as we approached the center of the high, there was less of a pressure gradient). The pressure hit a maximum somewhere around 20:00, and the winds calmed.
February 20, 2001
The high-pressure system passed through our area during the early hours of the
morning. The wind shifted direction about 60o in a few hours, and the wind speed picked up as the pressure gradient increased. The pressure dropped as well. By late afternoon, the cloud had become overcast with stratus clouds and the pressure hit a minimum, as a low pressure driven cold front moved into the area.
February 21, 2001
During the early morning hours, the wind speed picked up considerably, indicating that the low was moving through the area. By midday, a stronger high- pressure system had pushed the low out to sea. This is evident because the wind slowed and switched directions by another 50o-60o. The pressure rose and the sky had some cumulus clouds, indicating fair weather for a little while longer. The pressure hit a maximum sometime in the late evening, as the wind died off completely.
February 22, 2001
Overnight, the pressure decreased rapidly. We woke up to a dreary, snowy, overcast morning. The temperature had dropped twenty degrees since the day before, the wind picked up, and switched direction by about 200o. The wind, combined with the low temperatures, caused the National Weather Service to issue windchill warnings. We also received 4" of snow, which began early morning and continued til right after the sun went down. All of these indicate that the high-pressure system had been displaced by a powerful low-pressure system. In fact, upon examining the frontal map for 2/22, one can see the mid-latitude wave cyclone centered over western Alabama.
February 23, 2001
The wave cyclone dissipated by morning today, and it was like someone flipped a switch. Yesterday, we were buried in snow, and today we wear short-sleeved shirts. In fact, the temperature had rose 30oF from where it was yesterday. Though the data says we had relatively high humidity, this was due to the fact that the snow mostly disappeared through sublimination, as the snow disappeared without leaving a wet, muddy, mess on the ground. The wind had picked up considerably, also aiding in the sublimination. The direction of the wind had shifted about 200oF, indicating the passage of the mid-latitude cyclone. The sky was clear all day, with the exception of a few fair-weather cumulus clouds.
February 24, 2001
Today is the definition of a high-pressure system. The highest pressure in all the observations this week was recorded at 10:22 this morning, at a whopping 30.45" Hg (1031.5mb). The wind speed dropped off by midday, but began to pick up in the late evening due to an approaching warm front. This warm front was the leading edge to a mid-latitude wave cyclone centered over the middle of Kansas.
February 25, 2001
We never hit the center of the mid-latitude wave cyclone. It moved through to the west of us. However, this meant that today we experienced a warm front followed by a cold front. This is evident in the data because the wind direction shifted about 150o, and the sky became covered with threatening stratus clouds. The pressure dropped by the afternoon, to the lowest pressure recorded during the week: 29.95" Hg (1014.3mb). After the warm front had passed, the temperature jumped up into the 60's around early afternoon. The sky even cleared long enough for us to enjoy the comfortable temperatures.
February 26, 2001
Today was another textbook definition of a high-pressure system. On the frontal map, there is an "H" centered almost over Blacksburg. The temperature was a bit cooler than the day before, but that is due to the fact that we didn't have a layer of clouds reflecting radiation back to the surface. Instead, we had clear skies, rising pressure, and falling wind speed throughout the entire day.
OTHER OBSERVATIONS
For fun, I plotted the relative humidity, temperature and dew point temperature on the same graph. Ignore the Y-axis values (as they compare a percentage to a temperature, which has no value), and just focus on the relationship between how close the dew point is to the dew point temperature. The closer the two are together, the higher the relative humidity, which is what I expected, but now it's in graphical form.
Two mid-latitude wave cyclones passed through our area this week. They have the characteristic shape of a cold front extending south from the low, and a warm front extending east in front of the low. Though neither of these fully developed, it leads me to wonder why all of our books refer to "the" wave cyclone of 1971. If we had two this week, why is "the" one of '71 such an important focus? It must have been severe. Upon further research, the pressure was considerably lower- 996mb in comparison to 1014mb. So then were the two we had "weak" wave cyclones? One of them dropped 4" of snow on us, it's hard to imagine what a severe one would do.
CONCLUSIONS
Before I left for Virginia Tech my freshman year, I talked to some students and former students at Virginia Tech. All of them, in the first few sentences about Virginia Tech, warned me about it having its own weather system. Now I believe them.
Analytically, we see that this whole week consisted of alternating between a heavy winter coat and short sleeve shorts. I had a snowball fight one day, and the very next threw a Frisbee on dry land in shorts and a short sleeve shirt. Everyday, my reports say, "x pressure system was pushed out by y pressure system." The weather is constantly changing.
Scientifically, these unbelievable changes are possible, and when considering the data, explained. Because Blacksburg is nestled in the mountains, the wind we get is filtered around and over mountains, which can cause changes in directions rapidly. This also explains why we will go from almost no surface wind to a high wind in a different direction later. Also, we are not near a significant body of water, so temperature does not behave like it does at home (we live near the where the Potomac River enters the Chesapeake Bay, hence why everyone at home says VT has such strange weather).
