We have had an active pattern with volatile temperatures but overall average to below average, that’s all about to change. While the true step up to spring is more delayed than originally I expected there are glaring signs of it occurring within the next 10 days.
The reason for the delay was due to the stratospheric warming events we saw in January , a very strong blocking pattern set up and it put up a good fight but as this new pattern takes over, which is starting now the blocks will break down
It all stats in the Pacific, the pattern over the past month and a half as featured a very large ridge across the eastern Pacific , which lead to a dominant dip in the jet stream east of the Rocky Mountains , and forced polar and arctic air masses down into the Midwest and Northeastern US , and we had a very active sub tropical jet stream which lead to plenty of storms for areas along and east of the Mississippi River,recently 2 back to back winter storms across the Plains, the east coast had a few close calls with New England getting nice dumps of snow and of course the Blizzard that struck the northeast February 8-9th .
But we see in the satellite image above, due to the MJO getting into Phase 5 , convection around the dateline is basically gone which is breaking down the east Pacific ridge and we see a strong disturbance / trough coming east, helping to break it down , we also see a storm spinning in the Gulf of Alaska instead around the Aleutians like we have been seeing , and if you remember back to the start of winter we dealt with this a lot and it leads to a zonal pattern across the US with a flood of Pacific air which modifies and warms greatly east of the Rockies.
Also the disturbance in the Pacific is associated with a strong jet streak obviously tilted from west to east, as it moves east it will destroy the blocking (-NAO,-AO)
Now over the next 5-7 days or so the upper level low over southeastern Canada will be e main influence , which is leading to a deep trough over the east, even with the deep trough we are seeing lack of true cold air due to arctic air being bottled up north where it should be , but we see that strong jet streak/disturbance entering western Canada, that will come east and push and upper level low out of here by late week.
With this trough will come temperatures around average Friday into Saturday than below average (but nothing too cold) through Wednesday ( highs in the mid 30s NE PA to low 40s along the coast, lows in the upper 10s to low 20s NE PA to mid 20s to low 30s along the coast.
We start off with a deep trough in the east but you can see the Pacific trough moving east, breaking down and replacing the ridge the east Pacific with a trough , we can see this already happening on current satellite.
And by Friday we see a trough really establishing itself in the gulf of Alaska which is leading to a trough along the west coast and a zonal flow across most of the country , which is flooding the country with Pacific warmth
All this going on could lead to a very warm and spring like weekend next week
And of course with a trough digging into the west, we start to see development of a southeast ridge , based on whats going on in the atmosphere as we speak development of such a pattern makes sense and has full model support
The MJO has been in “warm” phases for a while now an it’s finally starting to impact the weather pattern
Above are the typical temperature anomalies for different MJO phases and the forecast shows it stalling in phase 6 which is clearly a very warm one , so over the next 10 days we should gradually shift into a phase 6 type pattern
And we can see the PNA is going to crash from strongly positive to negative in response to the pattern change, which means the ridge in the east Pacific is breaking down and will be replaced by lower than normal heights and a trough in the east Pacific and along the west coast potentally to the Rockies which of course correlates to above normal heights and thus warmth east of the Rockies
So basically what I expected is seasonable cold to below average temperatures with dry conditions through Wednesday, than we begin to moderate Thursday and Friday with a warm weather pattern taking complete hold by the weekend , overall im thinking a zonal flow pattern through mid March with temperatures moderating to above average then potential development of a dominant Southeast Ridge and temperatures well above normal by later in March