Good Tuesday to everyone. I hope your week is off to a smooth start.
Low clouds have been more stubborn to erode today than I thought they would yesterday at this time. A weak piece of energy is now moving East of the area taking its clouds with it. High pressure is centered over Akron Ohio and driving damp and cool air down the East slopes of the mountains. It’s placed for an ideal setup of cold air damming. That high is transient though and isn’t anchored in place. Goes-East indicates clear skies from Asheville West with the exception being isolated areas along The French Broad where low stratus fog continues to hang tough as of 1:00pm. Goes-East also indicating brightening skies across McDowell and Rutherford Counties but not totally clearing and that trend spreading Northeast. We should see a few peaks of sun this afternoon in most, if not all our forecast counties. Sunset is at 5:21pm this afternoon. The days continue to get shorter as we head into now, mid to late Fall, marching closer and closer to the Winter Solstice (December 21stat 11:28am).
Today highs will only muster back to around 50° thanks to the lingering cloud cover. Tonight low clouds and more fog is likey to redevelop. Fog may be dense in a couple locations. We will watch that trend and monitor with now casting through the night. Temps should be able to drop into the upper 30’s to around 40° for most areas but Burke, Caldwell, McDowell, and Rutherford could have trouble dropping much lower than 40° due to near 100% saturation.
Wednesday looks to be another day with a lot of clouds now. We start off with low clouds and fog, as stated above. Temps start out in the upper 30’s to low 40’s depending on how socked in the fog/low stratus becomes. Another cold front will approach from the Northwest spreading more high clouds into the area. I will keep rain out of the forecast Wednesday though. There will likey still be a few peaks of sun from time to time, albeit brief when it does appear. A line of light showers will approach the mountains during the early nighttime hours Wednesday into Thursday. The mountains will break most of these showers up but one or two could make it into our forecast area late Wednesday Night.
Futurecast Radar 10:00pm Wednesday Night
Thursday Morning skies will begin to clear out with the exception being the mountains where wrap around preipitation will linger behind the front. Thursday will feature a blustery day as the low deepens over Maine and moves up to Greenland. Winds will gust 15-20mph Thursday and in the mountains may gust to 25mph. High temps will be in the low 60’s with mostly clear skies.
High Temps Thursday Afternoon
Friday looks to be a calm collective day with lots of sunshine and high temps in the mid and upper 50’s. High clouds will be streaming in ahead of our next cold front, and this one means business. Clouds start to arrive Friday Afternoon. Low temps Friday Night should bottom out and 40°. Right now it doesn’t look like any rain will affect the area for those Friday Night Football Playoff Games but this could change still. We will narrow that down in later forecast packages. Here come the changes though.
Sauesday should start of dry and mostly cloudy. Breezy conditions will already be present from the SW. The powerhouse cold front approaches our area and spreads light scattered showers into the area by Saturday Evening. I expect the front will stall for a couple hours before it pushes over the Appalachains with the cold air behind it. Winds will have already picked up with gusts up to 50mph outside the mountains. A few gusts may reach 60mph in the higher terrain Saturday Afternoon.
Wind gusts 1:00pm Saturday
What’s driving this cold push of air into our area so early in the cold season? It’s the teleconnections. Basically the global teleconnections drive the weather around the globe. While the teleconnections are a long distance apart from each other they still have a meteorological connection. I like to watch three teleconnections for our weather, especially in the colder months. These phenomenons are part of what drives the polar jet south into The USA. The larger the swing the more affects they will have on our weather.
The first of the three I will discuss is the Pacific North American (PNA). The PNA is one of the most recognized climate patterns that drive/influence weather in The Northern Hemesphere other than of course the tropics. The PNA is normally influenced by the Southern Oscillation, which is the second of the three Imlike to watch. The Southern Oscillation (ENSO) is the Oscillation we hear so much about in our part of the world. That is the oscillation that we hear called El Niño and La Niña. Deep research has been done and the correlation between the two phenomena’s and the influences between them are definitely there. With a La Niña ENSO the Pacific Waters near the Equator are cooler than normal because the trade winds push the warmer water further West. This means less storminess because of less bouyancy (atmospheric lift) over the Pacific. Moisture isn’t lifted and spread into the atmosphere downwind. Yes, you got it correct! That is why we are normally dryer in the Southeast USA during La Niña years. The PNA is observed in the geopotential 750- 500 millibar (9,800ft - 18,000ft) height fields in the Western and Eastern United States. Here you should see where this is all linked together. A ridge builds over the Western United States when we get a positive PNA. That in turn deepens a trough in The Eastern United States opening the door for cold air to rush in from Siberia. Here is a graphic showing a positive PNA:
Positive PNA (Source: Almanac.com)
La Niña Weather Winter Months (Source: NOAA)
The third teleconnections that I like to watch is the North Atlantic Oscillation (NAO). This phenomenon consists of two pressure centers. The first is low pressure and normally it is centered somewhere near Iceland. The second part of this oscillation is the high pressure which is normally centered near the Azores. These pressure centers though, they are forever changing depending on the seasons. They have been measured at other locations in the North Atlantic. The NAO place a huge role into how the weather plays out along The East Coast. When the NAO becomes negative it buckles the jet stream over the Eastern United States, sending cold air south. When the NAO is positive it does the opposite. It allows warmth to spread North. Here is a graphic illustrating a negative NAO pattern:
Blocking ridge causing a negative NAO (Source: NOAA)
Now that you hopefully have a little better understanding of the teleconnections let me dive into the upcoming pattern that is evolving. The PNA is forecast to go positive. At the same time a blocking pattern is developing in The North Atlantic that is going to take the NAO into a negative phase. Both of the oscillations are evolving into what will be a cold end to November across the Eastern United States. Here are the current phases of the NAO, PNA, and ENSO:
NAO currently positive but forecast negative by Nov 17th (European Model)
PNA is currently negative but is forecast to go positive between 17th and 23rd of November. (European Model)
NAO currently positive but forecast to be negative by November 17th (Global Forecast System Model)
PNA Currently negative forecast to go positive by November 19th. (Global Forecast System Model)
These are just two models indicating this but all of the global models are picking up on what will be a cold end to November and a cold start to December. We will have to wait and see if we get a storm system to develop. It is certainly possible in this type of pattern. If you plan to travel next week there will be a cold front move through the Eastern US reestablishing the cold air across the area. Low pressure could affect travel in the Northeast but there is a lot to work out with that forecast yet. Stay tuned.
Potential cold front with rain on Thanksgiving Day across the Eastern US.
Temperatures as compared to average for this time of year. This nap shot is of this coming Monday Nove bet 20th.
Brief one day warm up ahead of the front Wednesday before Thanksgiving. (Timing could change) Temperatures compared to average for this time of year.
Another big cold snap in the days following Thanksgiving. (Temps compared to normal)
Another warm up around November 27th. (Temps compared to normal)
Potentially the coldest air of the Fall yet arrives around the last few days of November. (Temps compared to normal)