Anyway, as I've stated in the past, computer forecast models sometimes fail at 12 hours, let alone 300+ hours in time. Details of elements such as snowfall or accumulated precipitation on a spatial scale and time scale (even within 12 hours) are just numbers. There is NO predictability of such. If you see it, ignore it. So what this guy on Facebook shows you is nothing more than computer output that will, and often does, change dramatically every time the forecast model is run (every six hours). No doubt that once in a while the forecast model will be really good and close with those details! But that is just pure statistical luck.
In the post I did on the 17th (you can read it by clicking here) I discussed several potential storms. The first system was going to bring mostly wind to the high plains. Oh boy. Did anyone see the downburst video I posted on the NWS Facebook page that was taken in Sublette? That was a dramatic example of a downburst from an elevated thundershower (there was some lightning and thunder but hardly any rain). Click on downburst to see it.
The second system I discussed was expected Monday or Tuesday. It was right on time and brought rain to northern and eastern Kansas and some rain and snow to eastern Colorado. But for the majority of the high plains of Kansas and down into Texas....nothing (went too far north).
The next system I discussed was due around Thanksgiving or the following day. It also is on schedule (shown on the satellite image below). But it is too weak and too far north to bring anything to the high plains. It will bring a little snow to parts of the Dakotas.
Then I wrapped up that last post with the following: "Yet another system will be possible by the end of Thanksgiving weekend and perhaps the biggest threat another around the 1st or 2nd of December! Details are highly uncertain at this time. The point is the pattern is finally getting active and should stay that way into early December. Hopefully at least one of these systems will benefit the plains with decent moisture. Temperatures will be more seasonal and at times quite a bit below normal."
The one for the end of the weekend is ALSO on schedule but it looks like mostly wind as it will follow suite and track too far north. There are other possibilities by Tuesday and Wednesday. There has to be some development in the flow aloft to bring any threat and I will discuss the possible development below.
First - the west Pac.
There was (and has been) a response from convection across the western Pacific Ocean area. There still is a transfer of latent heat energy into the mid-latitudes (the green arrows pointing up and to the left). Also, some of the very cold air across Siberia has been moving east across the northern Pacific. There are other things going on but this should all point to some downstream amplification. Also, the red X is not a typhoon but is at least an organized system. Usually something in this position as it moves west and north causes amplification too!
Closer to the states:
(click for a larger image if you would like)
There was a vigorous storm across the Gulf of Alaska with upstream ridging of the upper wind flow. This storm should pound the Pacific Northwest. There was also significant ridging (moist upper flow moving north) west of Hawaii. This I find rather interesting. I'm not totally sure how that might come into play but I think it will. I'm going to watch that for a few days.
Over the conus:
(click for larger version)
The red X over southeast Minnesota is what brought some precipitation to the central part of the U.S. late Monday and yesterday. It had weakened considerably. The other red X over central California is the Thanksgiving system that will mainly impact the Dakotas. Part of the issue with that system is the HUGE blocking high (the blue H) over southern Canada.
In that post I did on the 17th, I discussed the North Atlantic Oscillation (NAO) as being one of the keys that might help the upper flow buckle and become stormy across at least the central U.S.. I was looking for the index to go negative (and it has been forecast to do so with a degree of error). Here is the latest:
It has reached a neutral index and is still expected to go slightly negative. That "might" be enough to contribute to some blocking and amplifying of the pattern but combining with the current state of the flow across the Pacific "will" make it happen. That Arctic Oscillation (AO) index continues to be negative and is expected to continue. This is in spite of an anomalously warm high latitude Arctic region:
Speaking of the Arctic. The average daily temperature in the band between 90 degrees (north pole) and 80 degrees north has been "off the chart" above normal. I've never seen it like this!
The spike in temperature about a week ago was scary! What is just as strange is that as temperatures at this latitude have been 30 to 35 degrees above normal, farther south across Siberia temperatures have been 30 to 35 degrees below normal! I've got to believe this is a pretty unstable scenario.
So for next week....
Expect dramatic changes in the weather across much of the conus. There will be a battle ground setting up across the central U.S.. It is still way too early to get specific on timing or impacts OR location. Once the changes begin to take place, then details of impacts will become clearer. I think the best course of action at this point is to prepare for a big change. Those with interests that would be impacted by winter weather, hopefully you are already prepared. Active and sometimes stormy weather should be expected for the first 1 to 2 weeks of December.
BTW, your going to see numerous graphs, maps, etc. posted during the next few days with detailed information. Keep in mind details like I discussed at the first of this post just can't be trusted this far out. I'll try and update again Monday or Tuesday.
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