After being in and continuing to be in a generally chilly pattern through most of September so far with below average temperatures, it appears we will see a bit of shift in the pattern for the start of October which may bring some welcomed or unwelcome warmth depending on your preference.
Through the next 3-5 days or so the same theme is expected with sunshine, dry conditions and below average temperatures with highs in the mid 60s to low 70s and lows in the upper 40s to mid 50s , a weak frontal passage Monday into Tuesday with maybe a passing shower.
What we will see beyond the day 5 period is a large trough over the western US begin to push eastward, this will in turn push a ridge in the middle of the country eastward for the first week of October
We can see a very deep trough being carved out in the west and thus a nice ridge building over the Plains and another somewhat weak trough over the NE (due to the strong negative NAO block) if that wasn’t there we would already be in a very mild weather pattern. The idea is that over the next week or so the ridge over the Central US will SLOWLY build east ward as the western trough slowly comes eastward due to the pattern in the Pacific is still on the progressive side , this would lead to something we haven’t seen in quite some time, above average warmth starting mid-week next week and lasting through at least next weekend if not beyond with the continuation of dry conditions
The only thing that may prevent this is the storm developing well east of Florida, this is expected to make its way north northwest over the next several days then take a turn to the northeast (perhaps clipping coastal New England), this could enhance blocking farther and lead to similar conditions seen this week but I believe we will see the block begin to break down and shift east ward quick enough to see some perhaps summer like warmth spread in , especially as we get towards next weekend and a strong cold front will attempt to move east which will lead to a strong southwesterly flow
What I see here is not a pattern change though but more so a “reload” or relaxation period in the weather pattern, but during this break starting Tuesday or Wednesday through Sunday I expect temperatures to be in the mid 70s to lower 80s area wide and lows in the mid 50s to low 60s with dry conditions , could see some widespread upper 70s to low 80s next weekend ahead of the cold front
Here we are on Friday and we can see the nice ridge slowly building east, the negative NAO is still battling but is shifting east
By Saturday and Sunday the ridge wins out and kicks the trough east ward with very mild temperatures across the eastern US
But once that cold front comes through (most likely early the following week) it will mark the return of the same general pattern we have been seeing dominantly since August and some of the models are hinting that this push of polar air behind the front could be VERY chilly for early October standards.
A ridge returns to the western US and a nice deep trough settles over the east and the negative NAO also returns , I believe we are going to see this pattern relaxation because of the MJO , it is in phase 5-6 which would argue for something like this to happen , so the point is here , is we will continue to see below average temperatures for the rest of September and then finally a break for the first week of October with above normal warmth for 5 days I do believe after that October will end up being a below average month once again though!