Just wanted to add onto the blog from yesterday about the pattern shifting to colder and stormier in late December/ early January for our area
We learned that things are beginning to fall into place, the Gulf of Alaska low is gone, and is being replaced with ridging, we have warm stratospheric anomalies spreading into North America and the MJO is heading into more favorable territory, tonight I just want to illustrate exactly wat I think will happen over the next few weeks
We see the warm anomalies entering the US BUT they are entering the western US first , where you get warm stratospheric anomalies is where troughs are more likely, so if the warm anomalies are entering the west first, that means its likely that a trough will develop in the western US first, and the cold air bottled up in Canada will spill into the western US first , the fact that the EPO is positive and ridging is setting up a bit too far west supports this theory
So with a trough and cold air spilling into the west , it is likely that the eastern US will have to do deal with the Southeast ridge on and off , although the negative NAO should be enough to suppress the SE ridge somewhat , prevent it from being dominant and keep us from getting real toasty .
But still, with a deep trough over the western US and western Plains , storms are likely to track into the Great Lakes region, more so than the east coast. I this type of pattern, phasing of the polar and sub tropical jets are likely to occur in the southern Plains rather than the eastern seaboard , this will pump up ridges over the east when this occurs, and that is when the SE ridge will rear its head , a perfect example is tomorrow (Monday)
As I said , the pattern change will be slow and steady. I expect that this cold will SLOWLY make its way east through the remainder of December and reaching our area late December and early January .
The positive EPO , and Polar Vortex too far north still, tell me that the mid month expectations are too early , but with stratospheric warming occurring, the Polar vortex which is currently over Siberia, a very unfavorable area, will be forced to weaken and come south SLOWLY . If you’re expecting the pattern change by mid December you will likely be disappointed or happy depending on whether you like warmth or cold
Expected weather pattern through December 20th-25th
I illustrated my thoughts above, cold air begins to spill into the west and central US (which is occurring now) and will slowly spread east with every storm system , these are big changes occurring from what we saw earlier this month but the east still has to wait a bit longer as there is still a lot to change, and its going to take a little bit of time
This regime of trough in the west, and zonal/ridge in the east will last through December 20th – 25th I believe. Each storm system (which I believe will track west of us) will help to bring down the Polar vortex as well, but this is a slow process that will not occur by December 15th, im almost positive of that.
We have the MJO which will be moving into phase 1 around December 15th , add a 7-10 day lag period and I believe this cold will be spreading into our area around Christmas time, most likely in between Christmas and New Year is when we will truly begin to notice changes , assuming all goes as planned. hats not to say there will not be any cold between now and late December, we will have shots of cold air behind storm systems and cold fronts, but they will be transient, and quick-moving.
To sum things up, the pattern is SLOWLY changing, cold air from Canada is beginning to spill into the west and central US , and will slowly come east , in the mean time , a trough in the west will counter act to a ridge over the east , which will force our storm systems to track west of us, most likely through the Great Lakes region through December 20-25th, I believe based on MJO and stratospheric data, the cold will invade the east between December 25th- January 1st as of now. I will continue to track this pattern change, if things change you will know but so far things are falling into place for the ate December / early January change I hav been harping on about. So if you like cold and snow , patience is a virture, you you enjoy warm December weather and rainstorms, enjoy it while you can!!