Chilly high pressure has settled in for Saturday, return flow aloft could impact late weekend weather

Good Saturday to everyone across the Foothills and Western Piedmont…

 

High pressure at the surface is in place across the region but aloft we continue to have a fast westerly flow moving through the Southeast US. This combination of factors at differing layers of the atmosphere is going to lead to a changeable forecast over the next 48 hours. The first half of the weekend looks to be pretty cut-and dry. Strong high pressure over Southern Ontario has dug itself southward into the Carolinas bringing initially a (dry) cold air damming episode to the area. The result is a chilly Saturday for everyone.

 

 After starting the morning in the upper 20’s and low 30’s we will struggle to make a up a whole lot of ground today as afternoon temperatures will only reach the mid to upper 40’s under mostly sunny conditions.


Computer Model Projected high temperatures (today)

Computer Model Projected high temperatures (today)

 

With few clouds and low dewpoints in place temperatures will crash pretty fast after sunset getting back down at or below the freezing mark for low’s. Infact those low temps could occur at or just after midnight.

 

As we get into the overnight hours the flow in the mid levels will begin to override the surface cold pool with some moisture and by Sunday daybreak a rapid increase in clouds and shallow moisture is expected.

 

Its at this point where the Sunday forecast begins to have a few question marks. First off, just how much moisture will be streaming in at the mid levels? Computer model guidance over the past 24+ hours have increased its moisture output now to the point that the models are spitting out light rainfall amounts across the Western Carolinas by morning and lasting through the afternoon hours.


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This development in the guidance is very significant in that with cold dry air established, our “dry wedge” may evolve into an “in-situ wedge” and that could mean a damp and chilly Sunday  for the region. We are currently forecasting mid/upper 40’s for Sunday’s high temperatures but that could end up being conservative at this point if the recent guidance trends hold firm. We will definitely keep an eye on this development through the rest of the day.

 

The good thing is that any possible in-situ wedge should break down either late Sunday night or Monday morning yielding milder conditions for early next week.

 

Daytime highs Monday and Tuesday will be in the upper 50’s to around 60 for both afternoons with 40’s at night. By the middle part of next week a zonal flow will take over a majority of the Continental US meaning a return to milder conditions with temperatures jumping back up into the 60’s for everyone with partly cloudy skies.

Have a great day!

 

Daniel Crawley

Foothills Weather Network