Rain, Storms Wednesday Usher in Cold Blast to End Week
Updated: Jun 25, 2021
Temperatures will hover 10 to 20 degrees below average Thursday and Friday.
-Strong cold front to deliver rain and thunderstorms to the entire region Wednesday into Wednesday night
-Threat for severe storms is MARGINAL (level 1 out of 5) across much of North and Northeast Georgia, and SLIGHT (level 2 out of 5) around the Atlanta metro area to the Southwest including areas like Carrollton, LaGrange, and Newnan
-Shot of unseasonably cold air brings frost and freeze concerns to end the week
-Warming trend on tap for the upcoming weekend
A vigorous cold front that packed a strong punch of gusty winds and a steep drop in temperatures across the Northern tier of the U.S. Monday is poised to pass through North Georgia by Wednesday night. Ahead of it, widespread showers and storms are expected across the region Wednesday, with localized severe weather and flash flooding not out of the question.
The National Weather Service's Storm Prediction Center in Norman, Oklahoma has placed much of the coverage area in a MARGINAL (level 1 out of 5) risk for severe weather Wednesday and Wednesday night. A somewhat greater risk exists in areas around and Southwest of the Atlanta metropolitan area, where a SLIGHT (level 2 out of 5) risk has been posted. The primary risk in any severe storms is strong damaging wind gusts, but isolated pockets of hail or a brief spin-up tornado cannot be ruled out. While we need to be weather-aware anytime the Storm Prediction Center outlines the region in a risk area, it is important to note that a widespread severe weather outbreak like we saw last Thursday is not anticipated.
In fact, this set-up is similar to what occurred Sunday, where some areas saw only rain, and others, like Griffin and Rome, reported multiple instances of wind damage. Because the severe risk is isolated to scattered, we cannot predict precisely where severe weather will occur, but can say a marginal risk to slight risk exists across the area.
Aside from any storms with strong wind gusts, flash flooding is the greatest potential risk across far North and Northwest Georgia, where several locations in the vicinity of Blue Ridge Lake and along the Chattooga and Conasauga Rivers are near or above flood stage from the past week's storms. Big Creek in the area of Roswell and Alpharetta is another area of concern. Rain amounts of ½ inch to 1 inch are projected for much of the region, with localized pockets of 2 inches or more possible. These amounts, if they verify, may be enough to prompt another round of flash flooding in these areas tomorrow afternoon.
Left/Top: Current river flood stages in North and Central Georgia. (NWS Southeast River Forecast Center/USGS)
Right/Bottom: Projected rainfall from Short Range Ensemble Forecasting System for site along the river North of Rome, GA, where minor river flooding is currently occurring. A most likely outcome of an additional 0.7" to 1" of rain is projected, with a range of 0.4" to over 1.5" possible. (NWS SPC)
Speaking of timing, the chance for showers and storms will exist across the region all day Wednesday into Wednesday evening, with the heaviest line moving through from Northwest to Southeast roughly between 7 AM and 6 PM.
As the rain and storms clear the area Wednesday evening, a rush of cold air and breezy conditions will overspread the area, dropping lows to around freezing in the far Northeast mountains and the mid-30s to around 40 degrees to start your Thursday morning across the rest of North Georgia. This fetch of brisk Northwesterly winds will keep its grip on the region through the end of the week, with unseasonably cool highs in the upper 40s (far North) to 50s both Thursday and Friday.
Aside from a chill in the air during the day, very cold nights with low temperatures projected in the 20s and 30s are catching the eye of University of Georgia agricultural climatologist Pam Knox, who oversees the UGA Mesonet: “With temperatures falling below freezing at many locations, frost or freeze damage is a possibility for many gardens and fields. Some crops like cabbage are cold-hardy and can take temperatures below 32 F, but most tender plants will need to be protected from the cold air.”
Knox advises that home gardeners "move potted plants inside or cover them with sheets or other coverings to keep the coldest air off the leaves. If you cover them near sunset, then that will help hold the heat from the ground near the plants overnight. Make sure to remove the coverings the next morning once temperatures rise above freezing.”
She adds that commercial producers “may need to use frost protection such as irrigation or fans to keep temperatures above or near freezing. Since peaches and blueberries are blooming now around Athens, there could be some damage to production this year, but the amount of damage will depend on how long the temperatures are below freezing and how cold it gets. Low-lying areas are often the places with the most damage since the cold, dense air tends to flow downslope into those areas."
Fortunately, a quick rebound to warmer, more Spring-like temperatures is expected over the weekend, with early indications pointing toward dry conditions. The warming trend is likely to continue into early next week.