Lead Forecaster Daniel Crawley
Good Monday morning to everyone, it was a mild weekend across the western Carolinas as high-pressure remains firmly entrenched across the southeast US. We are going to turn up the heat a little bit over the next three or four days before some major changes come just in time for next weekend.
High pressure at 500mb is centered over the Arklatex Region and encompasses the entire Southern tier of the nation. That will grow in intensity over the next couple days. The end result will be some quite warm conditions for most of the work week across Western North Carolina. Average high temperatures this time of the year are around 80 degrees during the day and upper 50’s at night.
Today will feature some mid to upper 80’s but by Wednesday all locations east of the mountains will flirt with the 90 degree mark, so we are looking at temps a good 10 degrees above normal.
Once we get toward mid week you can begin to see changes aloft and how they will evolve into a much cooler pattern across the Eastern US. Our 500mb Ridge weakens and retrogrades toward West Texas. That will allow shortwave energy over South-Central Canada an opportunity to dig down into the Northeast US. This will ultimately carve out a trough for New England. This not only brings cooler weather to the East but it also scoops up Hurricane Fiona and sends it into the open Atlantic.
By Friday a deep trough is centered over New England and that will help push significantly cooler air down the east coast into the Carolinas. Thursday will be our last above normal day in terms of temperatures. As you can see on the image below there is another short wave across North Dakota that will follow the same path and help carve out another trough past the current seven day forecast.
With it being late September any developing trough has the potential to drag down some cold air from the northern latitudes and that looks to be the case for next weekend. A rather significant cooldown is coming! Friday and Saturday will feature temperatures in the 70’s for everyone, 60’s in the mountains with crisp night time lows (40’s?) on at least one or two mornings.
Looking at the teleconnections it appears that a positive phase of the Pacific-North American Oscillation will develop for the end of this month and will last into the first part of October. In more simple terms that relates to tall ridges in Western North America dislodging air into the Central and Eastern US.
Just on a sidenote I think it’s very encouraging that we are seeing this Teleconnection occurring in the early part of October. Could this possibly be giving us hints of what the teleconnections may naturally try to revert to this winter? Hmmm… 🤔 🥶❄️
Anyway…the other big takeaway is that we will remain dry as well. We are now pushing close to a full week since the region has seen rainfall. We may easily duplicate that during this current seven day forecast period. The tranquil weather is nice to have but with the southeast coming up on the driest part of the entire year (October-November) it could help onset a flash drought down the road.