The weekend shaped up to be a nice one with plenty of sun, cool mornings, and comfortable afternoons. Super Bowl Sunday, the clouds will be on the increase as a shortwave (a cool pocket of air aloft that often produces clouds and rain) approaches from the Gulf and a cold front moves in from the north. The shortwave may help enhance the showers and storms expected ahead of the front so strong storms and even a few isolated severe storms are not out of the question. But right now it looks like the strongest storms will remain just offshore and near the immediate coast.
It’s been brought to my attention Power Doppler 3000 has shown some very strong returns the past couple of nights.
Even though it looks ominous, what is being picked up is actually not rain. We have a very stable atmosphere in place and as the radar beam scans Acadiana the angle of the beam increases the further it goes out. It’s hitting a layer of the atmosphere that is actually warmer than the ground (an inversion) and the beam is refracted downward to the surface. It’s picking up on trees, buildings, and everything on the ground. We call it ground clutter or a more technical term, anomalous propagation. The best way to tell if it’s ground clutter is if the returns on the radar are extremely bright and appear in a circle, it’s likely not rain. This usually happens at night or early in the morning when the ground cools faster than the air aloft. Once we get warmer air under cool air the radar returns to normal and any returns we see will likely be showers.
The cold front is still on track for Sunday night into Monday morning and rain looks very likely for most of Acadiana. Groundhog Day is Monday at sunrise and with the clouds and possible rain, I don’t think Pierre will “C.” his Shadeaux. That could mean a longer winter and a short spring.