Breezy, Cool Weather Ahead
The combination of a landfalling hurricane on the East Coast and a strong, cold surface high over the Northern Plains will create a large pressure gradient over the entire eastern United States this weekend and early next week. A pressure gradient is akin to the slope of a hill. The closer the lines are to each other, the faster air will flow across them…like water flowing down a steep hill.
This is the GFS forecast map of 1000-500mb thickness and mean sea level pressure (MSLP) at 1 PM on Monday. The “thickness” is indicated by the colored bands; a low thickness generally shows where areas of colder air exist. The pressure contours (“isobars”) are in black. Notice how tight the gradient is over Alabama, Tennessee, Georgia and Kentucky?
That will make it breezy from now through the middle of next week! An average wind speed of 15 to 20 MPH during the day will be common; if that wind can settle down some at night, then some scattered frost will be able to develop on Monday and Tuesday mornings. In fact, if it settles enough on Tuesday morning, low temperatures could be as cold as 27-32º around the entire Tennessee Valley leading to the first “freeze” of the season!
On our Seven Day Forecast at WHNT.com/Weather, you’ll see forecast lows in the lower 30s early next week. If the wind can’t settle down at all, the numbers may need to be bumped up a little. Check back with us this weekend for updates on the potential for a frost or freeze early next week.
Here’s the latest ensemble probability from the NOMADS site; it shows about a 60% chance that temperatures could drop below freezing by Monday and Tuesday mornings: