Good morning everyone, let’s talk about the two storm systems on tap over the next 7-10 days.
December 29th Event
The models have come into pretty good agreement now with this event. A piece of energy in the southern branch will eject out and form a relatively weak surface low along the western Gulf Coast. The track of this surface low will be across southern Alabama and Georgia and then just off the Southeast coast. IT looks to head NNE from there and strengthen as more northern energy phases with the system.
Since there is not a significant area of high pressure across the Northeast, we will be lacking a mechanism to cool the surface temperatures for this event over much of NC. Therefore as the system moves in, warm advection at all levels will erode the current cold air and it appears most areas outside the higher elevations will see rain.
The event looks light to moderate across most of NC, with probably a 0.25 to 0.5 inch of liquid QPF east of the mountains some higher QPF amounts in the mountains. I think there will be some snow in the mountains although it will probably not be a strictly snow event, except for the highest elevations. I do think 1-4 inches of snow are possible in the NC mountains Friday night into Saturday morning (especially over 2500-3000ft) with locally higher amounts over the highest elevations. For areas east of the mountains it looks to be all rain.
The big winners look to be the central and northern Appalachians and interior Northeast where the latest Euro puts out 12-18 inches of snow for eastern NY and interior New England.
January 1st-4th Event
There continue to be some disagreement on this event even though it is now getting into the day 5-8 time frame. The main energy is a trough in the Gulf of Alaska and this trough will not be onshore until Saturday on the west coast. So we could continue to see some model disagreement and oscillations for another 1-2 days. As this trough rotates onshore it appears it will progress out into the southern plains by early next week. Another s/w in the northern branch will move into the NE US early next week bringing a re-enforcing shot of cool air. Therefore it appears as this system moves out, there will be a bit more cold air to play with. A track of a weak surface low along the Gulf Coast to off the Southeast coast looks like the most likely track at this time.
However, this isn’t set in stone. If the northern stream is slower and digs a bit further south, we could see a much stronger storm take a further west track. If the northern stream is too fast and too strong then the system could get majorly suppressed with little activity north of AL/GA/SC. If the timing is right, I would say the areas that would stand the best chance to see snow or a wintry mix would be TN/SE KY/WV/VA/northern NC. But again there are a lot of ways this could play out so we will just have to keep watching it.
As I have been mentioning once we are past this event, the pattern looks to turn warmer as the models are in good agreement on a +AO/NAO/EPO which is typically a very warm signal for much of the US. This is supported by the MJO which is in phase 3 and if it stays coherent will pass through warm phase 4,5,6 over the next 10-15 days at least. So it seems like there is support for this warmer turn.
The question will be how long does it last? The CFS weeklies turn cold again by mid to late January and if the MJO progresses it will hit the colder phases of 7,8, and 1 by mid to late January. But it is unclear if that MJO pulse will survive. I will say that the 6z GFS Ensemble already shows a colder pattern developing by 1/12 and the Canadian Ensembles are cooler as well, with the Euro Ensemble the warmest. The Euro Ensemble is typically the most dependable, but I think the rest of the winter will be volatile with no cold or warm pattern locking in for extended periods.