After a few days of impressive cold, particularly at night all the way to Texas, as expected, this cold is now weakening as it tries going east, in fact it fails and this cold will weaken on the spot as heights rise. The culprit for the lack of cold in the East is the negative PNA.
The pattern is much like what we here in the UK are experiencing, yes a cold pattern for sure in the heart of the country (not East) but, even this is transient! No real lockdown cold pattern despite a negative NAO. There is no good setup at the moment. If the NAO is negative the PNA too is negative, not good for getting the cold to slide east and even with a negative NAO, the position of the block isn’t particularly great for the Lower 48. A lot of the focus of arctic cold these days is centred over Europe and Asia.
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The trouble is the positive heights associated with a negative NAO has the high more over northeast Greenland stretching across to northern European Russia. A weaker block is evident up over northeast Canada but there is no real cold air reaching the East Coast.
The block is seen to breakdown as the NAO appears to go towards neutral. One could argue a more zonal pattern is evolving for the Atlantic, directing much more of a mild westerly into the British Isles.
However as for the US, the pattern turns stormier, less cold and the East Coast’s first system next week looks to take a due north track up the coast. Without any real cold to tap, this would be mostly a rainmaker even for interior areas.
Here’s the GFS Operational scenario for next Wednesday!
As it stands right now, according to the models, a cold high is present up over eastern Canada but too far north. With a system riding up the coast, you really want that high to be nearer New England with cold air already in place and in a position where the system can tap this cold and wrap it into the circulation. At least so the interior can get snow and perhaps a rain, changeover to snow type event for the Big Cities.
With the pattern next week, it’s not like there won’t be any cold at all, the trouble is, it’s focusing out West. California looks to see the strongest, deepest trough yet drop out of western Canada and this will bring low snow levels etc but because the PNA is persistently negative, the cold diving south and into the West cannot go east. Stronger than normal heights will develop over the Plains, so if you’ve been shivering of late, don’t worry, 60s, perhaps 70s will replace the nighttime teens, single digits and for some, sub-zero lows..
There is a hint at another downward trend in the NAO in the week running up to Christmas, so that’s the week after next. The good news in all this is, while there is no real solid hint at the PNA going positive in which a high can really build up the west coast and drag down dome real cold down into the East, Canada has plenty of untapped arctic air, so it’s waiting there and waiting for the right setup to evolve.
As for the system in the days leading to Christmas, it’s too far out to even hazard a guess as to possible scenarios but here’s hoping that the PNA and NAO is more favourable and we may get a surprise white Christmas in the East.
Check out the GFS temp anomaly for the next 7 days… Note the warmth..
Courtesy/Owned by Weatherbell Models
Now take a look at the 8-16 day. Note the return of cold and even the cooling in the Northeast. I honestly think the other shoe must drop eventually.
Courtesy/Owned by Weatherbell Models
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