John1122

How to keep the Gulf of Alaska low from flooding pacific air into the NA continent. Pac jet pumps the Alaskan ridge into steroid range, and sends snow level cold to Florida.

As soon as I say suppression isn't an issue, the Euro has snow on the beaches.

78 would tie the record high in Chattanooga set in December 1951. It was 78 at Tri that same day, 77 in Knoxville, 73 here. 9 days later it was 23 here with a half inch of snow. Otherwise a really warm December. Unfortunately, that's one of the all time warmest winters in Tennessee history. Jan and Feb were both well AN.

Keeping in mind that it just snowed constantly in the 1960s, December 23-24th 1966 saw a widespread 4-8 inch snow event from Nashville to Tri-Cities and points N in Sw Va and SE Kentucky, 2-4 inches along 40, 1-3 inches around Memphis, and unfortunately for Chattanooga, more rain with a back end dusting. Temps around zero for lows on Christmas morning imby. January of 56, by a day preceeded a 4-6+ inch event that went from Memphis to just north of Chattanooga and points north. Jan of '58 was a brief cold shot around the 15th-19th with around 1 inch of snow. The 1995 analog, it got coldish, 30s and 20s for highs and lows with a 1 inch snow here.

Positives. The AH dies. There's a bit of a -NAO. There's no SE ridge. The STJ is waking up a bit, maybe. The cold isn't so suppressive that we are seeing Florida beaches getting buried. The polar vortex may get stretched again in January. For the next two weeks we will have a pattern more conducive for snow than our current pattern of sunbathing weather. The two weeks after that, may, (stress may as always here) be even more conducive. Especially if we get the +PNA to show up, timed with a wave. @GaWx noted that even for areas East of the Apps, the +PNA was the most frequent teleconnection for decent snow events. I'm hoping we also continue the trend he noted of +PNA January conditions that follow -PNA Decembers.

It's wild how scoured out the cold gets on the Euro AI. The entire NA continent is AN to much AN as soon as the Aleutian ridge breaks down. It's like it's the only thing delivering cold to our source region, but as soon as it leaves, all cold goes with it and Pacific air floods everywhere.

I really wish the models didn't just keep reloading the -pna. You can see in the brief positive periods we get very cold, but it quickly flips to - and we warm way up. The AR breaking down is a positive but getting to the +pna will really really help if we can get there and get any staying power with it. The GGEM/GEPS is best at the +pna and is therefore by far the coldest.

Merry Christmas to all as well. I started a January thread, as we are now looking into there for the changes.

We are looking into early January now on modeling. With a potentially potent cold shot coming for the first few days of the year. With any luck, the Pac jet extends towards the polar regions, and then drops back towards the equator, which should get rid of the Aleutian ridge and help get a +PNA look. The GEFS wants nothing to do with that, it keeps the AR and hooks the NAO with Atlantic ridging. The GFS gets rid of the AR but has no -NAO at all, and no +PNA. The GEPS has a PNA ridge and -NAO with an eastern trough. The AIGFS gets rid of the AR and has the -NAO with a small eastern trough and looks like it's starting a +pna at the end. The Euro AI builds a tall PNA ridge by the end but it's scoured out the cold over Canada with much AN temps, but we are slightly BN here by the end. The EPS has a slight +PNA at the end, and a slight trough east and the AR was gone. So, outside of the GFS/GEFS we could be building towards a good pattern for us around Jan 8th-10th. The heart of winter is Jan 15th to Feb 15th. If we get to peak climo with the +PNA/-NAO look that's about all you can ask for.

We are creeping towards a possible -NAO/+PNA pattern. It still may not snow, because you just never know here, but that's as good as it gets for the chance of a winter storm here as far as blocking goes.

The GFS is mostly ugly with a capital UGH in the long range. +NAO/-PNA/Aleutian Ridge rock solid. Who knows if it verifies, as it's been flopping back and forth so much lately.

The Canadian keeps the subzero cold. The GFS lays down some anafrontal snow on Monday now with that cold front passage.

Mammoth has gotten 28 inches as of 4pm local time. The forecast through Friday. "Tonight Snow. Steady temperature around 20. Wind chill values as low as -1. Windy, with a south southwest wind 30 to 35 mph, with gusts as high as 55 mph. Chance of precipitation is 100%. Total nighttime snow accumulation of 26 to 32 inches possible. Christmas Day Snow. High near 20. Wind chill values as low as -3. Windy, with a south southwest wind around 30 mph, with gusts as high as 60 mph. Chance of precipitation is 100%. New snow accumulation of 33 to 39 inches possible. Thursday Night Snow showers. The snow could be heavy at times. Some thunder is also possible. Steady temperature around 20. Wind chill values as low as -1. Windy, with a south southwest wind around 35 mph, with gusts as high as 60 mph. Chance of precipitation is 100%. New snow accumulation of 23 to 29 inches possible. Friday Snow showers before 1pm, then snow, mainly after 1pm. The snow could be heavy at times. Some thunder is also possible. High near 18. Wind chill values as low as -4. Windy, with a southwest wind 25 to 30 mph decreasing to 20 to 25 mph in the afternoon. Winds could gust as high as 55 mph. Chance of precipitation is 100%. New snow accumulation of 9 to 13 inches possible."

Mammoth got over a foot of snow in a couple of hours overnight. Up to 100 inches expected in the area. I like to watch it, but when they're getting buried, we usually are waiting on the pattern to change.

A true PNA will basically always work for cold here. It means drier weather in our area but as Jeff has noted, below normal precip doesn't mean it's not good for snow. Above normal precip here usually means the warm flow from the Pac or Gulf is coming, and all the issues they cause.