|ECMWF (left), GFS (center) and CMC Long Range 500mb anomaly forecast|
Long Range Discussion
January 1 2014
Multi-model guidance above for the 8-10 day period shown is in average agreement, with highest disagreement area over northern Canada into Greenland, leading to additional disagreement over the Northeast United States. Model confusion revolves around whether to allow development of strong low pressure over Greenland, which would then help chances for ridging out towards the Northeast and East Coast. ECMWF and GFS are in the "best" agreement of the three model suite, with the ECMWF centering the anomalous low pressure west of Greenland and the GFS strengthening said low pressure system and placing it south and east of Greenland. The difference in location will affect the large-scale weather pattern, with a more compact solution with that upper-latitude low pressure system as exhibited by the ECMWF leading to stronger ridging along the East Coast. On the other hand, if the system is to be placed east of Greenland, the low pressure would be elongated from the Bering Sea out to the waters east of that land mass, and that would temper ridging prospects in the East US.
Model guidance is in good agreement on ridging keeping a chokehold on the Arctic Circle, which will prohibit reformation of the polar vortex across that area, and thus will keep the risk for cold weather across lower latitudes rather high. All modeling systems are also in agreement on ridging appearing over the southern Gulf of Alaska and into the north central Pacific, and we also find a consensus among the guidance with deep low pressure over the Bering Sea into Alaska. Now, for the long range that we are watching over for this time period (8-10 days out), this means we will be seeing a pattern that will most likely keep out extreme cold weather like we will see to kick off the upcoming workweek. In the long-long range, this somewhat-anti-cold pattern will flip over.
I began discussing earlier today.
To summarize, I anticipate some warmer weather arriving in the wake of brutal cold for the second week of January, before we see a trend towards colder conditions in time for the end of that second week and into the third week of January.