A potentially significant winter storm continues to take shape over the next 24-48 hours. A Winter Storm Watch has been issued for everyone in the Shoals and the Metro Area. This Watch does NOT include Sand Mountain. For Morgan and Madison Counties, the watch begins at 3 PM Monday. For everyone else, the watch begins at 6 PM Sunday night. Winter Storm WARNINGS have been issued for Mississippi and west Tennessee.
This winter storm will come in two rounds. Here's a breakdown.
Round 1: Arrives Sunday evening. The main concern with Round 1 will be for areas along and west of I-65. In these areas (the Shoals, Moulton, Athens, maybe Decatur) we expect light freezing rain that lasts through the overnight hours. With this round, anywhere between 0.10" and 0.25" of ice accretion will be possible. Slick spots will begin to develop west of I-65 Sunday night, especially on bridges and overpasses. Areas east of I-65 (Huntsville, Sand Mountain) will see just plain rain and little impacts. See below. We should see a break in the precipitation Monday morning before round 2 arrives.
Round 2: Arrives Monday afternoon. The second round will be the main show with this winter storm. Temperatures will remain just below freezing in the Shoals throughout the day Monday. This will allow for additional freezing rain to mix in with sleet as some cooler air tries to work its way into northwest Alabama. Even so, an additional 0.10" of ice combined with 1"-2" of sleet will cause extremely hazardous travel conditions and increase the likelihood for power outages west of I-65.
For the Huntsville metro, temperatures will begin to dip near or below freezing Monday afternoon. This is when we expect to start seeing freezing rain in Huntsville and the rest of the I-65 corridor. We expect little in the way of sleet here in Huntsville, meaning icy roads will be an even greater concern here compared to the Shoals. Up to 0.25" of ice will be possible for the I-65 corridor, including Huntsville. Power outages will be possible.
For Sand Mountain, we expect to see mostly plain rain. Some light freezing rain can't be ruled out along the ridge tops and higher elevations, producing a light glaze in these locations. While a few slick spots can't be entirely ruled out in Sand Mountain, most roads should remain wet. See below for the Round 2 impact breakdown.
Much of the precipitation will end after Midnight Monday night. Icy roads will remain a concern into Tuesday morning, as temperatures fall to the upper teens for many spots. Bottom line: a high impact winter storm is on the way. Widespread power outages and icy roads will be possible, especially over northwest Alabama.