Good Saturday evening to everyone across the Western Carolinas, we hope that your weekend is off to a good start.
Weather-wise we are in the season of change! October is usually a big transition month in terms of going from summer heat and humidity to winter-like cold. Here in 2019 that is no exception. Remember roughly two weeks ago when the Carolinas was in the midst of a historic heat wave. High temps in the month of October well into the 90's with summer-like humidity?
Yep, things have changed in a big way over the past two weeks. One of the biggest differences is that we have been able to scour out high pressure across the Eastern US in favor for a more active and moist zonal flow with occasional buckling of the mean flow at times.
Current weather tonight, which is rainy, is a result of an upper low that buckled the flow. That in tandem with the leftovers of former Tropical Storm Nestor has delivered much needed rainfall to the Carolinas.
Here's a look at our storm system on visible satellite from earlier today just prior to sunset. This is the most widespread rainfall for the Western Carolinas going back to the month of August.
Rainfall amounts of at least 1/2 inch is expected through tonight with localized amounts of over 1 inch before the precip departs overnight.
The synoptic outlook going into next week has several different features that will drive the weather pattern...
On the image above notice the bright colors located over Greenland. Pressure aloft will be on the rise in that part of the world. In Meteorology we refer to that as a negative of the Atlantic and/or North Atlantic Oscillation (NAO). Meanwhile in the Eastern Pacific heights will rise as well leading to a positive phase of the Pacific North American (PNA) teleconnection. When those two work in tandem the result is usually a cold, active and suppressed weather pattern across the United States.
The models clearly show the large trough centered over the Mississippi River coming up this week. This image, which is a 5-Day average positioning would indicate a continued southwest flow will dominate the Southeast with different rounds of precipitation.
After tonight our next rain maker looks to be centered around Tuesday as a stout upper low will move across the Great Lakes. However, as you can see blocking over Southern Greenland will prevent the upper low from blasting through and moving up into Canada. So therefor expect that upper feature to ultimately stall out and rotate additional pieces of energy within the overall circulation. A surface boundary as a result will come through on Tuesday with decent shower chances once again.
Tuesday's cold front will usher in another cool airmass that will help keep temperatures near or just below normal for late October. By late week the next lobe of energy will dig pretty far south (the -NAO/-AO doing its dirty work) and could evolve into a major storm system as it gets cut off from the main jet. You see this a lot in the cold weather months. In the dead of winter this kind of setup can be a winter weather lover's dream...but we're still in October and for us that means additional rain is likely. And dependent on the track of low pressure a severe weather aspect can kick in due to the dynamics in play. So this is some that we will have to watch going into the Friday/Saturday time frame.
The biggest takeaway from the upcoming pattern is that multiple rounds of rainfall is possible over the next 7-Days. Note the latest precip forecast courtesy of the WPC...a couple inches is possible for most locations.
The forecast precip lines up almost perfect to those locations still under the worst drought conditions across the Southeast. It may not be a complete drought buster but at the very least will keep things from getting much worse.
Our forecast team finds it very interesting this sudden change in the pattern in late October to Greenland Blocking, Pacific-North American ridging and upper low's taking the southern route and breaking off from the mean jet configuration. These are some of the players that you would like to see in the winter time if you like winter weather. Just to think, a setup like this two months from can now can lead to determining not only who gets precip but also precip types.
Winter is not far away!