The accuracy of the first day of a forecast is between 80 and 90 percent. Today was one of those "10 or 20 percent" days (much to my chagrin).
I thought there would be at least a few breaks in the cloud cover, but that never happened. The evening balloon launch from Tallahassee is showing a very thick layer of saturated air between the earth's surface and about 5,000 feet above that. That's the reason why we have the extensive cloud cover. There is decent directional wind shear near the top of the cloud deck and increasing warm advection aloft, which is leading to a heavy mist or drizzle in many places. I expect this trend to continue overnight. A cold front is producing of line of strong storms over Mississippi and the Louisiana Delta region. The front is expected to reach the Apalachicola/Chattahoochee Rivers late Sunday morning, on its way to clearing the Suwannee River Valley by late afternoon. The main atmospheric dynamics that are maintaining the squall line to our west will quickly lift out toward the Ohio Valley and Northeastern United States. Thus, I am confident that the line will weaken considerably by the time it reaches us. We can expect a broken line of light rain showers to accompany the front with no one area receiving more than a tenth of an inch. Skies should clear from west to east behind the front just before or as the sun sets, along with a brisk northwest wind.
Noticeably cooler air will follow the front on Christmas Eve and Christmas Day. High temperatures will probably not get much past 60 degrees both days. The morning lows are going to be a little trickier. The winds will probably stay up much of Sunday night, but could drop below 5 mph after midnight. Normally this would favor good radiational cooling conditions, but satellite imagery shows a long trail of high-level moisture stretching from South Texas into the Tropical Pacific Ocean. Some of the models are forecasting some of these cirrus clouds to arrive, so it's unlikely we'll see a widespread freeze (even though the statistical models say otherwise). We'll keep an eye on this, but we think lows will get no colder than the mid 30s. The only exception could be the far western Big Bend and southwest Georgia, where a light freeze could occur for a short period of time. A similar scenario will probably play out on Christmas morning.
We'll see a couple of vigorous atmospheric disturbances move across the South on Tuesday and Wednesday, but moisture through a deep column of the atmosphere will not be present. Therefore, rain chances are no greater than 20 percent. A warming trend appears likely to begin on Thursday as an upper air ridge begins poking northwestward from the Bahamas toward Florida and South Georgia.