By: Charles Roop | WCTV Eyewitness News
November 17, 2017
TALLAHASSEE, Fla. (WCTV) -- Operational meteorology, the practice of forecasting the weather, can bring frustration during certain situations; from determining where a tropical system is going to make landfall, to determining if it will rain during and around a major holiday.
We are trying to figure out the latter and the long-range models aren't helping with what could happen for the Thanksgiving weekend.
For the last few days, some meteorologists on social media have been talking about the wild shifts in the models for mid to late next week. Mike McCall and this meteorologist have been trying to figure things out, too.
So, what do we know?
The two major global models that yours truly tend to look at are the American GFS and the European (aka "the Euro"). With the latest runs (as of Friday afternoon) are still showing two different solutions.
After this weekend's cold front, the models do show a weak trough in the mid to upper levels making its way towards our region Tuesday morning. This would provide some energy aloft for rain, but the best moisture may be behind the energy. This would leave rain chances in the slight category at best Tuesday into Wednesday
The next upper-level system, based on both models, originates from the Gulf of Alaska, where a trough is in place. Based on Friday morning's upper-air maps, the Euro has a better handle of reality. But it's grip on current conditions doesn't mean it will persist. This trough will weaken as it moves into the Pacific Northwest, but both models expect this to amplify in the western Gulf of Mexico by Wednesday.
This trough, though it may not be too strong, may help develop a surface low in the Gulf of Mexico sometime Thursday. Both models differ slightly on the timing of development, but that still means a chance of rain will be in the forecast for Thanksgiving. But the models also differ on when the skies will clear (Friday morning or Saturday morning). The GFS also leaves us drier than the Euro.
There is at least one thing to consider. The difference between rainfall and dry weather around this low in the gulf is very sharp. Any change in strength and positioning of the low will determine whether or not we'll see rainfall. Also, the trough that is going to help this low develop may not be too strong as the jet could be the strongest in the northern U.S.
For now, we have rain chances heightened on Thanksgiving Day as the low develops and influences our weather. There is uncertainty for Friday and Saturday with rainfall, but we are leaving in at least a 30 percent on Friday. Because of current uncertainties, chances for rain will be less than 50 percent.
When models agree with each other, confidence in our forecast increases. But when we see continued flops and disagreements with little things, we are not as certain whether or not you'll be standing in the rain as you wait outside in line for that Black Friday sale. Keep checking back over then next few days to see what may be in store for the Thanksgiving weekend.