Heather N. Kolich, ANR Agent, UGA Extension Forsyth County
University of Georgia Climatologist and Director of the UGA Weather Network Pam Knox recently reported in her weekly blog, Climate and Agriculture in the Southeast, that she received numerous questions related to media reports of colder temperatures predicted to arrive in the Southeast. Some reports included “ominous pictures of snowfall maps showing up to a foot of snow.”
“Just because someone shows a scary snowfall map on social media it does not mean it will happen or even that it is likely to occur,” Knox cautioned. “It might be one out of 50 or so model runs.”
The various weather model maps are a snapshot of possible conditions at one point in time. A few hours later, the same model might show a very different map.
To understand weather prediction maps, let’s look at the January 7-11, 2025 Temperature Outlook map from the National Oceanic and Atmospheric Agency (NOAA) (above), which was issued on January 1, 2025. The map shows a large area of dark blue covering the Southeast, which might make you think we’re in for a deep freeze. What the map attempts to show, however, is the likelihood that temperatures in the regions will be higher or lower than normal for these dates. The dark blue color means that NOAA is very confident (90-100% certain) that from January 7 to January 11, temperatures will be lower than normal across the states indicated. The red color means that NOAA is confident (60-70% certain) that temperatures will be higher than normal along the west coast for those same dates. The map does not predict what the actual temperature will be, nor does it indicate how much they will vary from the normal temperatures.
The high confidence comes from the fact that all the weather models agreed that a pattern shift would start on New Year’s Eve, bringing in air from the Arctic. Weather models are complex mathematical calculations using data from several sources, such as satellite data, aircraft observations, weather balloons, stream gauges, and citizen scientists with personal weather stations. The output of the calculations helps develop weather forecasts or maps for the earth surface as well as conditions at different heights above it. There are many different models used to generate regional, global, short-range, and medium-range forecasts for temperature, precipitation, wind, and weather hazards, such as snow, freezing rain, and fire. Confidence in a forecast increases when multiple models and model runs generate very similar predictions.
Other types of weather outlook maps show predicted anomalies across regions, such as a temporary temperature change of -15 F. This prediction indicates the temperature might be 15 degrees cooler than the normal temperature for the region at the specified time or date. In the Atlanta area in January, the normal high temperature is 54 degrees and the normal low is 36 degrees. With a -15 F anomaly, the area would temporarily experience a high of 39 degrees and a low of 21 degrees.
For the record, the January 7 early morning temperature was 23 degrees Fahrenheit according to my personal weather station. The National Weather Service predicts overnight low temperatures will remain in the 20s through Monday, January 13. That’s as far out as the January 7 forecast goes. These temperatures are low enough to cause frozen water pipes, frostbite, hypothermia, or other cold injury to people, pets and livestock working or spending time outdoors.
But what about that deep snow?
“As far as wintry precipitation goes, most of the maps shown on social media are just clickbait,” Knox cautioned. “You cannot trust any snowfall map that is more than two days out, because the conditions for snow to occur require very specific weather conditions that include cold air to hit a spot at the same time that there is enough moisture there to form wintry precipitation.”
The reason we don’t see snow very often in the Southeast is that the specific snowfall conditions rarely occur. It’s more usual for the moist air to move east before the really cold air arrives from the northwest. We’re more likely to see freezing rain with this weekend’s weather.
But I’m writing this on January 7, and I checked that forecast a few minutes ago.
“Both the strength and timing of the temperature anomalies are going to change over time as new observations and forecast model results come in, so you need to keep monitoring forecasts for updated conditions” Knox said.
Knox recommends monitoring weather forecasts through credible, scientific sources such as the NWS, which continuously monitors conditions, updates predictions, and provides unbiased information.