I was posed the question: Do broadcast meteorologists do any calculations? The answer to this particular question 98% of the time, for me, is: No, I do not do any calculations. Most of the calculations I would potentially do are already done for me by computer programs so I take advantage of that. Yes, I will admit, if I want it 100% accurate and done correctly, I should do them every morning. I just don't have time in my everyday activities to sit there and do them.
The next question, "What exactly do you do to forecast?" That my friend, is a little more involved.
Before the advent of computers, meteorologists, on-air or off-air, got data streamed into them, over phone lines if I'm not mistaken, from the National Weather Service. They printed this data off on LONG sheets of paper, you know the good ole printer paper with the perforated edges. They then PLOTTED all of the points by hand like so:
The meteorologists analyzed the data (maybe not as nice or as colorful but you get the idea):
and put together their forecast. It was immensely time consuming and took about 4 hours to complete every day.
That was the old days. Fast-forward 40 years and you have a brand new world of forecasting. No longer do many meteorologists print out data sheets and plot them individually. No longer do we have to wait for data to become available to us. The advent of the internet cured this. Granted, I should note that there ARE some meteorologists who still do plot weather maps by hand from radiosonde data.
Now that we got some of the background of old-school meteorologists, let's get back to the original topic: What I do every morning.
I walk into the station at around 3 AM and log into my computer. I then go over to our weather computers and bring up this map:
This is a water vapor map, I usually view it in motion, showing where the dry/moist air is in the mid to upper levels of the atmosphere. The reds indicate dry air and the whites, purples, blues and greens indicated more moisture, in that order. It tell me if there is a chance for mid-upper level clouds, frontal systems, areas of high pressure, shortwaves embedded within a long-wave trough which could lead to rain (or drier air) for particular areas downstream among other things. Water Vapor Imagery is a great tool to have that is garnered by geostationary satellites high above the earth.
The next piece of data I look at:
The visible satellite! This was taken over the Deep South on September 6, 2011 at 1806Z (or 2:06 PM EDT). Visible satellites, also in space ;), capture the light being reflected off cloud tops. Clouds can wreck HAVOC on a meteorologist's forecast if he doesn't predict their motion or rate of dissipation correctly. For instance, this morning when I forecasted, I didn't properly forecast the cloud cover. As a result, my forecast high temperature busted by about 8/9 degrees. Not the greatest forecast, I know, but you learn from it and move on.
The next few pieces of data I look at are the latest soundings, or temperature and dew point profiles (vertically from one point) of the atmosphere at certain locations around the US:
The first sounding is from Peachtree City, GA and the second is from Birmingham, AL. The red line is the temperature and the green line is dew point. A LOT of calculations can be done from just one of these soundings; e.g. CAPE, Lifted Index (LI), Convective Temperature, CIN, Level of Free Convection (LFC), Lifted Condensation Level (LCL), Precipitable Water (PW), Equilibrium Level (EL), etc...We don't have to calculate these every day because we have computers and programs to speed the process along. I did a TON of these calculations, by hand, in school. All those computations are important for severe weather days (CAPE, CIN, LFC, EL, LI, PW) , forecasting clouds (LCL), forecasting rain (PW), chance of thunderstorms... That's all calculated from just the temperature and dew point lines! Look on the right hand side of the diagrams, the official name is Skew-T diagrams), Notice the wind bards changing direction as you get higher in the sky and different notches or flags. This is important in telling if cold or warm air is moving in.
Now look at these next plots:
These are station plots from around the Deep South. Notice the same wind barbs found on the Skew-T diagrams are also found here. The wind barbs depicted here are surface winds and can also tell me if colder or warmer air is on its way. The first one is from September 5, 2011 at 2PM, while the second is from September 6, 2011. Notice how the top one shows temperatures in the 60s in northern MS and AL and the winds blowing from the north to northwest. Now, look at the second image. The colder temperatures have shifted to the east with the area of low pressure. Upper-level winds, about 30,000+ feet in the air, blow from west to east across the US, meaning most weather systems will track from California to New York. It should be noted that this is HARDLY ever the case, but I can explain that later if you ask me.
All I have done is figure out what has ALREADY happened! In order to FORECAST the weather, I need to look at sophisticated computer models. Here are a links to a fraction of the models I use:
OSU MOS and
Mean Sea Level Pressure GFS (there are MANY other maps to look at on this site, but just wanted to give you a feel for what I look at on the surface). These are tools for me to be able to forecast 2+ days out! I can do alright within 24 hours with the stuff mentioned above, but I need these guidance models to help me get a sense of what's going to happen the next seven days. Each model has its own biases and has to be taken into account. I also have to sit there and tell myself, "Does this make sense!?" I ask that question a lot each morning and is what makes my job fun! And no, in case you were wondering, it doesn't always make sense. Hence the fun part ;)
This should give you a general sense of what I do every morning when I step into the station. I hope you enjoyed reading through it all and if you have any questions, don't hesitate to ask!
David Reese
Morning Meteorologist
WRBL TV-3
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