Lead Forecaster Daniel Crawley
Good Monday morning to everyone, fall weather has definitely locked in here on the 10th day of October and it appears that Mother Nature will kick it up a couple levels during the next week or more.
The Western Pacific Hurricane Season has been active in recent weeks, a few typhoons have been pulled up into the mid latitudes and the result has been an increasingly amplified jet stream across the Pacific which ultimately influences the weather across North America.
You have probably noticed the cool weather here in the Eastern US due to the amplitude, that will continue and likely intensify this week.
As you can see on the map above a trough will be making its way across the middle part of the nation later this week. This trough and associated cold front will scoop up some moisture late Wednesday and could deliver some rain showers Wednesday night and into the first half of Thursday across the Carolinas and the rest of the Southeast US.
Precipitation amounts at this time do not look particularly heavy as both the Euro and GFS ensembles are showing amounts less than a half-inch through Thursday.
Blocking Pattern Emerges This Weekend and Beyond
Once the rain chances pass, we will have another surge of cold air coming into the United States for the upcoming weekend. We go into a full double block in the northern latitudes as we have a combination of +PNA and – NAO.
Looking at the map above ☝️ you can see the ridge planted along the Pacific North American Coastline by Saturday morning while another blocking high sets up near Greenland. This all creates a roadblock to where the trough across the US cannot escape. Meanwhile you can also see the cross-polar flow in the height pattern, that allows a significant dislodge of cold air into the trough axis.
This blocking pattern looks to have staying power beyond the current 7-Day forecast. By the middle of next week, the +PNA will relax itself but the expansive Greenland Block continues to trap everything and the trough just spins in place centered over the Northeast US.
The result will be continued cold air across the Eastern US.
With this upcoming pattern it raises the opportunity for a widespread frost outside of the mountains. The meteograms for Morganton and Shelby show the potential of that happening.
This is the kind of pattern that in the heart of winter would be quite cold and supportive of winter weather opportunities across the East.