Ramblings of a Graduate Student

Tomorrow I am giving a weather briefing at the National Severe Weather Workshop.  The map above is essentially what I’ll have to talk about…a closed 500mb low over Colorado.  After the active pattern we’ve had the past few weeks and the active pattern we’ll probably have next week, it’s kind of boring.  Oh well, at least I get to do something!

PS…The image above is from the North American Model (NAM) and was creating from this evening’s model simulation.  It is valid at 18 UTC tomorrow, or 12 PM CST – about an hour and a half after the briefing.

Above is a visible satellite image from 2045 UTC (2:45 PM CST) today (3 March).  A visible satellite image is the equivalent of a photo – it is what a human would “see” if he or she were located where the satellite was located.  One issue with visible satellite imagery is that it is hard to distinguish between “high” clouds and “low” clouds.   Also, any snow on the ground will show up as white in the satellite “photo” making it hard to identify what might be clouds and what might be snow in places where there is a lot of snow on the ground (i.e. Iowa!).  Take the image above, there are several areas where the predominant cloud type is actually low clouds and fog.  Can you identify where they are?  Can you distinguish between what is snow cover and what might be clouds?

To help aid meteorologists distinguish between areas of low clouds and high clouds, researchers developed ways of using satellites to “see” clouds in ways that humans can’t.  This is done in a variety of ways by “looking” at the various different forms of radiation that are emitted from the earth.  Without going into a whole lot of details, objects at different temperatures emit radiation at different wavelengths.  This means that if a satellite “looks” at these different wavelengths, it can determine the temperature of the cloud.  From this, meteorologists can determine if a cloud is low (typically warmer) or high (typically colder).  By combining different wavelengths, meteorologists can get an even better idea of where the clouds are located.  Also, using combination techniques it is possible to differentiate between snow cover and clouds.

The image above uses a combination of radiation wavelengths to help forecasters determine if a cloud is a low cloud or a high cloud.  Low clouds tend to be bright white and smooth where as higher clouds tend to be “bumpy” and have variations in color.  Based on that, can you identify several areas of low clouds?  The image below has three such areas highlighted.  Also, notice anything different about Iowa?

Not much time to blog tonight as today got away from me.  (I spent about an hour and a half with reporters from South Korea doing stories on meteorology in the United States).  However, I thought a nice view of the western hemisphere from the Geostationary Operational Environmental Satellites (GOES) 12.  This image is valid 8:45 PM CST 2 March 2010.  The white (clouds) along the east coast of the United States are associated with the storm that brought snow to northern Georgia and portions of the Carolina’s today.  The good news for the northeast United States is that this storm should remain south and east of them, giving them a reprieve from all the snow of late!  (The storm that brought all the snow to the northeast last weekend is located to the northeast of the east coast cyclone.  It is the white speckled comma looking shape that extends westward toward the east coast cyclone.

This week continues to be a busy one for me, but hopefully in the coming days I’ll find the time in the next few days to discuss the possibility of late weekend or early next week thunderstorms in the central plains.  It is still a ways off, but severe weather cannot be entirely ruled out.  (I should also add that is cannot be entirely ruled “in” either!)

Today marks the beginning of meteorological spring and with that, most meteorologists begin to think more about the spring severe thunderstorm and tornado season.  One of the necessary ingredients for severe thunderstorms and tornadoes is warm, moist air at low-levels.  This early in the severe weather season, the source of this warm, moist air is often the western Gulf of Mexico.  (Later in the season, moisture is drawn north from the Gulf of Mexico after it has originated in the Caribbean Sea.)

The image above displays the current sea-surface temperatures for the Gulf of Mexico.  The warmer the sea-surface temperatures, the warmer and more moist the air near the surface tends to be.  However, near the Texas coast, the water temperatures are very cold (~60F).  This means that air originating over these points tends to be cooler and drier than air located over the southeast Gulf of Mexico.

Lastly, often times when hurricanes are moving through the Gulf of Mexico, they will rapidly intensity.  This rapid intensification often occurs when the hurricane moves over what is known as the Loop Current.  The Loop Current is part of the Gulf Stream Current that is located in the Gulf of Mexico.  It’s an eddy of warmer water in the Gulf.  This warm water often acts to provide more fuel for hurricanes allowing them to strengthen more rapidly than they otherwise might if the Loop Current were not there.  The Loop Current is not stationary and will move around in the Gulf of Mexico.  Currently, the “peninsula” of warmer waters extending northward between Cuba and the Yucatan Peninsula into the Gulf of Mexico is the Loop Current.

For help with converting the Celsius temperatures above into Fahrenheit temperatures, use the following scale:

• 0C = 32F
• 5C = 41F
• 10C = 50F
• 15C = 59F
• 20C = 68F
• 25C = 77F
• 30C = 86F

Today marks the end of what is often referred to as “meteorological winter”.  Typically seasons begin and end on the solstices and equinoxes, but meteorologists tend to break our seasons based on calendar months.  Below are the months contained in each “meteorological season”.

• Winter: December, January, and February
• Spring: March, April, and May
• Summer: June, July, and August
• Autumn: September, October, and November

The United States will end a very active meteorological winter that saw numerous blizzards, at least one ice storm (in Oklahoma), and snow in all 50 states.  Two mid-level lows (shortwave troughs) are moving through the southern plains (yellow x’s) as well as a strong mid-to-upper-level jet stream (cyan color to the southwest of the southernmost x).  Also, the strong nor’easter that has affected New England for the past few days is slowly moving east, out to sea.

These mid-level lows are aiding in the development of precipitation in the central plains and western Texas as indicated by the radar images below.  There is a chance that portions of western and central Oklahoma will see some snow mix in with the rain, but little-to-no accumulation is expected.

I know the above image is not a “meteorological image”, but it was too rare of an event not to use it as today’s blog post.

Overnight a magnitude 8.8 earthquake decimated parts of Chile.  Shortly after the earthquake, a tsunami began affecting portions of the South American coast along with several islands off the coast of Chile.  The Pacific Tsunami Warning Center issued a basin-wide tsunami warning.  (There have been reports of tsunami damage along the coast of California.)

I spent a good deal of the afternoon watching live streaming video from television stations in Hawaii in anticipation of the tsunami’s arrival.  While watching Hilo Bay, HI empty and refill during the tsunami, my chair lurched forward as if someone or something hit me coincident with a distant thud sound.  I was stunned.  I then started to ask my friend, Kiel Ortega, if he felt the shake at his house, but before I could ask him if he felt it, he asked if I felt something.  I then went and asked Sarah if she felt something (which she had).  I quickly learned, via Facebook and Twitter, that it was not an isolated incident and people all around me (and not so nearby) had felt it.  It was a little after that when I learned it had been a 4.4 magnitude earthquake northeast of Oklahoma City.

I’ve always wanted to experience an earthquake.  Now, I can check that off my to-do list…

Educational Note: Just so everyone is aware, the Richter Scale, which is used to gauge the intensity of an earthquake, is a logarithmic scale – not a linear one.  I have heard several news outlets report that the 8.8 magnitude earthquake in Chile today was 1.8 times stronger than the 7.0 earthquake that hit Haiti recently. This is flat wrong.  The Chilean earthquake is actually 10^1.8= ~63 times stronger than the Hatian earthquake.  The Chilean earthquake was 10^4.4=~25,118.8 times stronger than the central Oklahoma earthquake

Above is this morning (12 UTC; 6 AM CST) surface pressure chart, as analyzed the by the Storm Prediction Center’s surface objective analysis dataset. (Essentially, what this means is that this is a model generated field that is “tugged” back toward truth through the use of observations.)  A couple of things stand out 1) the very strong low pressure centered over the New York City, NY area and 2) the strong high pressure located over the central Rocky Mountains.  The brown dashed lines indicate “troughs” or low pressure, or areas of lower pressure that are not completely closed off.  You’ll notice a trough to the northwest of the strong northeast surface low (this is indicative of strong warm aid advection aloft).  There is also a trough in the southern plains.  This trough is associated with a small, but potent, mid-level shortwave trough / closed low that brought rain (and some snow) to central Oklahoma over night.