Air Mass Motion Forecasting Technique

Where do you think temperature advection will tend to be stronger?

1. Within an air mass.
2. Within a front.

Within a front is correct. Fronts are regions in which temperature changes rapidly. Winds also tend to be strong near the front. The combination of strong winds and strong temperature gradients produces strong temperature advection. Within an air mass, temperature variations are much weaker, and advections are correspondingly weaker too.

In the modules on the diurnal cycle of temperature, we discussed the way that things like clouds, moisture, land surface, and wind can alter the maximum and minimum temperature. With a little practice, you can take a forecast of clouds and wind and estimate the next day's temperatures, given the temperatures today under similar or different conditions.

For example, if the wind in College Station is shifting to the south, and yesterday's high was 80 with a low of 50, you might expect the following change: with a south wind, the moisture should increase. That 30 degree spread between the max and the min implies fairly dry conditions. As the dew point rises into the 60s and 70s, the minimum temperature will move into the 60s and 70s too. By contrast, the max probably won't be much different. My forecast based on the above minimal information, would be for a high of 82 and a low of 60.

Consider a similar example: the same high of 80 and low of 50, but now the change is that lots of high clouds will be moving into the area. We know that high clouds don't influence the temperature as much as low clouds, but they still ought to reduce the max and raise the min a bit. So my forecast would be for a high of 76 and a low of 55.

Try one yourself: At College Station, there was a high of 80 and a low of 65 under windy conditions. The next day, winds will be calm or light. What is most likely?