Storm System To Move Across US Next Week to Initiate Pattern Change

Lead Forecaster Daniel Crawley

Good Friday morning to everyone. We talked yesterday on the blog about the current weather setup here across the Carolinas and a large part of the Eastern US. We are stuck between a pair of ridges and the prevailing flow is blocked out of the west and southwest. That is leading to a showery, cool, cloudy weather pattern.

Some quite significant changes are coming in the next 7-10 Days that will lead to us “potentially” evolving into a more winter-like pattern for the last 10 days of December.

We have a Greenland Block that is really forcing changes at the 500mb level here across North America. Meanwhile along the west coast of North America is a broad trough that will eject east this weekend and become a significant weather maker for the country.

Once we get to the middle part of next week, a powerful storm system will be moving east across the Plains States. To the north the Greenland Block remains and will slow down the feature somewhat and could keep the upper low from cutting up through the Great Lakes.

Model guidance is catching up to a southerly trend in the placement of the features at 500mb. Some further adjustment is likely to occur as we go through the upcoming weekend.

For the Southeast US we are looking at another rain and severe weather producer starting on Tuesday and lasting through Thursday of next week. The loop below shows how the upper dynamics will pull up abundant Gulf Moisture and send it eastward.

Heavy rain and a severe weather threat looks to exist next week…

Moisture Loop

This storm system appears to be the catalyst to a pattern change at the very end of the current 7-Day forecast and could be one to watch for later this month.

By the end of next week, a true “split-flow” undercutting pattern begins as heights shift toward the West Coast of North America. We have seen this pattern show up during he months of October and November and on both occasions it led to significant cold weather across a large part of the country, including here in the Carolinas.

This should serve to deliver cold air back into the Eastern US next weekend (17th). The good news if you are a winter weather fan is that the pattern may hold on for several days. The 500 mb anomalies continue to show the West Coast/Alaska Ridge with lower heights across the southern tier of the country leading up to Christmas week.

This is the kind of synoptic setup that could lead to winter weather opportunities at some point in the last 10 days of the month. Stay Tuned!

The temperature anomalies definitely fit the look at 500mb, a cold look for a good part of the country. Probably not brutal cold but cold enough to make things interesting should any shortwaves amplify.

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