SAVANNAH, Ga. (WSAV) – Forecasting the weather for the coming days is no easy task, especially when wintry weather is involved across the Southeast and so many ingredients need to come into play to make it happen.
These storms take multiple days of forecasting to fine-tune the details and come up with the most accurate scenarios, so let's break down how this process works.
7-10 DAYS OUT
In this stage, we analyze the overall pattern of the atmosphere to determine whether it will be favorable for winter weather over the coming days. Meteorologists will look in the upper levels of our atmosphere for dips and ridges in the polar jet stream. For winter weather across the Southeast, we need amplified southward dips in our polar jet stream to allow cold arctic air to reach our area.
5-6 DAYS OUT
As we pass the one-week threshold of an impending storm, we dig deeper into synoptic-scale models like the GFS and the EURO. At this stage, we also look into ensemble data which takes multiple runs of one specific model and shows a range of outcomes depending on the initial conditions of the atmosphere.
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The key to forecasting at this step is identifying consistent trends across the models. As each new run is issued, we are looking for shifts in where the cold air will be located as well as if there will be enough moisture for a storm to tap into. Additionally, we look to see if there is consistency in the placement of a low-pressure system and where it tracks in each run. After all, shifts of 50-100 miles make all the difference for storms of this magnitude.
The bottom line is, if we see a scenario playing out in a very similar way across multiple model runs, it shows the confidence for a storm is growing and therefore, it is becoming more likely.
3-4 DAYS OUT
A few days before a winter storm is typically when meteorologists can start to break down the timing for an event in a broader sense. Exact specifics for the start and end times will still need to be fine-tuned since small shifts can cause changes. Additionally, if there is agreement amongst the models, meteorologists can start to break down precipitation types such as snow, sleet, freezing rain and rain, and predict what different areas can expect.
1-2 DAYS OUT
At this point in the process, the next storm is knocking at our doorstep and it's time to revise the exact timing from start to finish and also detail how long a storm will last. Additionally, it's important to look into the vertical temperature profile of the atmosphere. This is because temperature changes at different levels can heavily impact the precipitation type as well as the totals that we see on the ground when the storm passes.
Speaking of which, meteorologists at this stage can get into the specifics of rain and snow amounts and how much different locations can expect. Looking into ensemble data will continue to help find trends in precipitation amounts as well as looking into shorter-range models like the North American Model (NAM) and the High-Resolution Rapid Refresh model (HRRR) since these smaller-scale models can show more precise detail.
To keep up with Storm Team 3's forecast, visit here.
