I personally think this is the most important forecast of the year for many, and that is the summer forecast. Summer is a season where people are and want to be outside enjoying the warmth so of course everyone wants to know what the summer is going to be like, for beach and camping trips, vacations etc.
I have been studying the weather pattern, shifts in the patterns and teleconnections for the past few months and so I think I have a pretty good handle on what we can expect this summer for the Northeast US and specifically the northern Mid Atlantic forecast area!!
I have been studying the NAO and have found interesting trends which is what much of this whole forecast is based on
We notice that since spring started and La Nina has bit the dust the NAO when from dominant positive and no blocking to on and off blocking which is slowly but surely turning dominant negative as we transitions to neutral and eventually El Nino in the pacific, which is also a big part of this forecast.
But what im getting at with the NAO is that we are heading into a dominant negative phase after being positive for so long, so that means that I expect there to be on and off blocking for much of this summer.
We got to remember though this is not winter so the NAO has slightly different effects during the summer time, it doesnt have as strong of an effect on us during the summer, so it basically just slows down the pattern and does not mean there has to be a dominant trough and cool weather in the east, if a ridge sets up in the east it will just linger around for a while, example was last summer 2011, we had blocking but a ridge set up over the east and some areas had the hottest summer on record because the heat ridge was just held in place. But im not saying that’s going to happen because I don’t think its going to.
So far this spring we have a very slow-moving pattern due to blocking and I expect that to continue through the summer.
Pacific Next I go into La Nina, El Nino etc
Theres a lot of talk out there that El Nino will make for a cool summer due to the combination of el Nino and the negative NAO but I see a factor against El Nino developing taking over quickly, and that is the fact that we are in a negative PDO pattern, which means the pattern and wind currents are such that over the northern Pacific that waters are colder than normal, and studies show that during negative PDO phases, el ninos (which are phases of above normal water temperatures off of the South America coast) are weak and form VERY SLOWLY , and that’s what we are seeing right now.
We are currently in a neutral state which means waters are around normal and we have been stuck here now for quite some time now and there’s no sign of speedy el nino development, and well summer is right around the corner. So what I expect is a neutral to positive neutral state for most of this summer.
So what does this mean? Well neutral states are usually relatively warm for the US , especially the western US as it usually means zonal to ridging in the west, which we have been seeing all spring dominantly and this in turn usually means zonal to slight troughs in the east, which again is what we have been seeing
Below is the PNA observations and forecast, positive phase means ridging in the west and negative means troughing in the west, its been DOMINANT neutral to positive and thus the dominant heat ridge
I have been studying the spring pattern and usually it is a good precursor of what summer could bring.
Many times where the most heat sets up during the spring is where it will stay though the summer, such as last year, a heat ridge set up in the eastern US during the spring and well it stayed with us all summer
So far this season the heat ridge has set up over the Rockies , it was a SE ridge we had all winter that shifted west due to the death of La Nina and a shift in the global pattern, I expect the heat ridge to remain dominantly where its been
SUMMER 2012 PATTERN
Here is the dominant pattern I expect this summer, a ridge in the west and zonal to slightly troughy in the east. I also expect a very active pattern with a lot of cold fronts coming from the WNW and a lot of shots of severe weather. I also expect there to be a dominant atlantic ridge which will lead to cold fronts stalling over the area and possibly some rather heavy rain and thunderstorm events
But this pattern will fluctuate with the NAO and PNA. While I expect dominant negative NAO and positive PNA,there will be times the NAO turns positive and PNA goes negative and when that happens and there’s no blocking I expect that heat to our west to RUSH east bound, giving us our share of heat , and the same goes vice versa, when the NAO goes strongly negative and PNA goes positive, cool and dry shots will comefrom the NW leading to stretches of below normal temperatures, so basically for our area I expect a bit of a roller coaster ride with the heat in the west trying to come east and the -NAO trying to block it and send down cooler air, and this again will lead to an active pattern and thunderstorm season!!
Temperature wise I expect it to end up around average and rainfall wise above normal this summer!!