Wow. Cold air like this is another great reason to live in Alabama…we only get it once a year or so! As of 100 am, many spots around north and central Alabama are below 20 degrees…including 19 in Auburn and Anniston, and 15 in Birmingham and Gadsden. This will be the coldest morning in about 5 years. Several locations north of Cullman are below 15, so we’ll likely see some single digits by morning. Area rivers and lakes, with water temperatures still much warmer than the air, show up nicely on infrared satellite tonight.
1-Tennessee River 2-Lake Guntersville 3-Warrior River 4-Weiss Lake 5-Lake Martin
With the heavy, cold air, pressures are also about as high as they get around here. The pressure at BHM is 1043.1 mb (30.78 in.). The air is also very dense. With a temperature of 15 degrees, the density is 1.37 kg/m3. On a normal summer day with a pressure of 29.92 in. and a temperature of 90, the air density is only 1.16 kg/m3. There is a lot more air in any enclosed space outside now than usual. But, it is also very dry, and the amount of moisture is almost zero. With a dewpoint of 8 degrees, the amount of water vapor in the air is only 1.8 g/m3, compared to a summer day with a dewpoint of 70, there is 18.2 g/m3, ten times as much humidity!
This cold air extends all the way into the Gulf and the Florida peninsula. It is currently 29 in Panama City Beach, 28 in Gainesville, 33 at Tampa and Orlando, and 35 at Sarasota. It is even 32 degrees as far south as Airglades, near Lake Okechobee.
The surf temperature at Panama City is in the 50s, but at NOAA buoy 42039, about 100 miles out in the Gulf, the water temperature is 71, while the air temperature is 42. This makes the air very unstable and condensation produces clouds quickly. Take a look at this afternoon’s visible satellite image. One can see clouds, in bands called convective rolls, over most of the Gulf and Atlantic starting about 50 miles offshore.
Stay warm.
