Pattern Change To Begin Overnight

Lead Forecaster Daniel Crawley

Good Saturday evening to everyone. We have been in the grip of a hot, sultry airmass this week with daily thunderstorm opportunities. Today’s storm coverage hasn’t been as extensive as compared to previous days We are starting to undergo a pattern change here in North Carolina as 500mb ridging has given way to an east coast shortwave trough.

By tomorrow morning surface winds will shift around to the northeast across Western North Carolina. That is going to do two things…

  1. It will help take a little edge off the excessive humidity that we have seen. Instead of sultry dewpoints in the low to mid 70’s we will see a reduction down into the upper 60’s. While still humid its not excessive in nature.
  2. We will have a reduction in temperatures with the lower heights, going below normal for Sunday/Monday and then returning back to near normal for middle of next week.

A weak surface high (approx. 1020 mb) will be located across the Midwest and that will help veer the winds at the surface over to northeast. Low clouds will fill-in after dark tonight and will persist for a 24-36 hour period.

Model Surface Map (Sun 8 am)

Looking at what is happening from the surface up to around 850mb, there will be a fairly long easterly fetch off the Atlantic Ocean. This at the very least is going to keep clouds in tact with periods of mist and drizzle especially as the easterly winds hit up against the Blue Ridge.

Model 850 mb flow (Sunday 8 pm)

The amount of precipitation being generated for Sunday on short range guidance varies quite a bit. Therefor its a medium confidence forecast. Regardless it will be quite cooler compared to earlier in the week.

This will be a fairly short lived pattern as we see things change again as soon as late Monday and into Tuesday. The Jet stream will be quite far to the north, meanwhile the entire southeast has a slight weakness in the upper atmosphere. An upper low may develop in the Gulf of Mexico while ridging will be south of Bermuda. That is going to allowed the flow to veer back to south and southwest by Tuesday. That brings the dewpoints back into the 70’s but with the lower heights, the air temperatures will be in the 80’s with little capping in the atmosphere to prevent storm development.

Full 7-Day Forecast details can be found by clicking on the button below…

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