E PA/NJ/DE Autumn 2026 Obs/Discussion

[PhiEaglesfan712]

With yesterday's beach storm out of the way and football season officially beginning, it's now time to start the fall thread.

[JTA66]

Met fall...we made it! 

Now if we can get the weather to cooperate. 74/F/DP 73F at 9am.

[Hurricane Agnes]

Did remember to start up in this thread. Ended up with 8.06" of rain for August.

And as an obs for yesterday, I did manage to hit 90 after a 72 low. Last evening was an almost continuous lighting show and the precip blobs were impressive but I only got a whopping 0.02" from that.   i noticed the line was moving fast so that might have cut down on the totals here.

My sis, BIL, and nephew were at the Linc at a Bruno Mars concert last night.  They initially had an hour rain/lightning delay and resumed just before 8:30 pm per her text, but then they were apparently forced to shelter in place and the show didn't resume until almost 10 pm per this -  https://www.fox29.com/news/bruno-mars-raye-concert-philly-paused-due-severe-weather

Currently 69 with dp 69.

[Hurricane Agnes]

The storm a couple of days ago was a light show with little rain for me but this one is a definite and almost continuous sound and light show for the past 3 hours.

Currently have 0.83" total after an initial round 1 of 0.67".  Temp dp both 69.

[Hurricane Agnes]

Finished up with 0.96" this morning.  More possible this afternoon once the temp cranks up.

Currently overcast with temp/dp 71.

[BBasile]

Picked up 0.61" this morning.  Up to 1.82" on the month.  Not bad for 3 days.  

[Hurricane Agnes]

1 minute ago, BBasile said:

Picked up 0.61" this morning.  Up to 1.82" on the month.  Not bad for 3 days.  

I missed out on the more significant rains the past couple of days (just 0.05 total over 2 days), so this time I got nailed. Have 1.01" for the month so far.

[JTA66]

Ended up with 0.50” overnight. Safe bet to say I’ll tack on to that in the next 24hrs.

[Birds~69]

71F/DP 71F w/the sun breaking out. This air mass sucks.

BUT < 20 days.... 

[Newman]

I've honestly not taken much of a long look into the upcoming 2026-27 winter prospects but did take a quick peek at it just now.

First of all, as of right now, it seems like the tropical Pacific and North Pacific *appear* to be out of sync and not quite coupled. Obviously we have a super Nino ongoing and expected to peak this fall. We're coming off a very negative SOI in July, I think the lowest since the 1980s. When taking a seasonal correlation of DJF 500mb heights to ASO SOI, you get a pretty canonical look. Positive correlations between SOI and 500mb heights in the SE US, meaning the negative SOI usually correlates to negative heights across the southern US, and then positive heights across the northern tier.

However, we may have a competing signal given there is (currently) a lag in response of the PDO to the developing Nino. August PDO is still negative, which is counterintuitive to what you'd expect during a strong Nino. In fact, I simply can't find any year at all that followed a typical ENSO progression to this year (strong to super Nino developing, peaking in the fall, then waning and eventually switching to Nina the following year) and also had a negative PDO. We still have time before winter for the North Pacific to respond, but for posterity, here is the correlation map between ASO PDO and DJF 500mb heights.

It's actually a very impressive negative correlation in the SE US, one that is more statistically significant than the SOI signal. The negative PDO usually correlates to positive heights in the SE US (big ridge in the eastern US), and that is opposite to the map above.

So that begs the question here... IF the PDO continues to lag into the winter and we have a Nina like North Pacific but Nino tropical Pacific, how will the winter turn out? I'm under the opinion that we will see a North Pacific "coupling" this fall with the tropics, but I'm cautious about it until I see it. We've seen this persistent negative PDO for so long, aided by the marine heat wave off Japan, so idk.

Just for further posterity, here is the 500mb height anomalies of 4 super Nino winters we've seen recently, which looks like a pretty canonical Nino pattern in the mean. But with Nina effects lingering, will we see a similar pattern this year?

 

Long winded thoughts, but my idea this winter is a pretty torchy start into December and early January. We might see some brief negative NAO spikes by late Jan and Feb which is when we'll need to time an active STJ storm with an arctic front that's pressed off the coast. Even if not, probably some chances for cold spells. I'm also not a long range forecaster so take everything with a grain of salt LOL

 @GaWx What are you thinking/seeing for this winter in the East?

[GaWx]

2 hours ago, Newman said:

I've honestly not taken much of a long look into the upcoming 2026-27 winter prospects but did take a quick peek at it just now.

First of all, as of right now, it seems like the tropical Pacific and North Pacific *appear* to be out of sync and not quite coupled. Obviously we have a super Nino ongoing and expected to peak this fall. We're coming off a very negative SOI in July, I think the lowest since the 1980s. When taking a seasonal correlation of DJF 500mb heights to ASO SOI, you get a pretty canonical look. Positive correlations between SOI and 500mb heights in the SE US, meaning the negative SOI usually correlates to negative heights across the southern US, and then positive heights across the northern tier.

However, we may have a competing signal given there is (currently) a lag in response of the PDO to the developing Nino. August PDO is still negative, which is counterintuitive to what you'd expect during a strong Nino. In fact, I simply can't find any year at all that followed a typical ENSO progression to this year (strong to super Nino developing, peaking in the fall, then waning and eventually switching to Nina the following year) and also had a negative PDO. We still have time before winter for the North Pacific to respond, but for posterity, here is the correlation map between ASO PDO and DJF 500mb heights.

It's actually a very impressive negative correlation in the SE US, one that is more statistically significant than the SOI signal. The negative PDO usually correlates to positive heights in the SE US (big ridge in the eastern US), and that is opposite to the map above.

So that begs the question here... IF the PDO continues to lag into the winter and we have a Nina like North Pacific but Nino tropical Pacific, how will the winter turn out? I'm under the opinion that we will see a North Pacific "coupling" this fall with the tropics, but I'm cautious about it until I see it. We've seen this persistent negative PDO for so long, aided by the marine heat wave off Japan, so idk.

Just for further posterity, here is the 500mb height anomalies of 4 super Nino winters we've seen recently, which looks like a pretty canonical Nino pattern in the mean. But with Nina effects lingering, will we see a similar pattern this year?

 

Long winded thoughts, but my idea this winter is a pretty torchy start into December and early January. We might see some brief negative NAO spikes by late Jan and Feb which is when we'll need to time an active STJ storm with an arctic front that's pressed off the coast. Even if not, probably some chances for cold spells. I'm also not a long range forecaster so take everything with a grain of salt LOL

 @GaWx What are you thinking/seeing for this winter in the East?

 Hello Newman, 

 For this winter, I’m thinking (none of this should be surprising based on super Nino analogs/models):

-above normal precip (up to 3” above) within a couple hundred miles of the NE coast with highest anomalies near the coast and closer to normal well inland

-above to MA normal precip SE with the largest anomalies in the deep SE/FL, where 4-8” will be common

-anomalies tending to get colder as one goes further SE

-New England/NE US likely to average 3-5F warmer than normal with warmest in N New England

-Mid-Atlantic will likely average ~1-3F warmer than normal with closest to normal near coast

-SE likely averaging near normal to slightly colder than normal with coldest anomalies deep SE/FL

-Regarding wintry precip overall, the SE tends to do best anomalywise in moderate or stronger El Niño winters. But even so, much of the SE, especially deep, is unforecastable since it takes only 1-2 winter storms (often just 1) to make it a very wintry winter there. But that chance tends to be best with El Niño winters vs other winters averaged out. Strong+ Nino winters have tended to have the best chance though moderate may be close.

[GaWx]

Oops, I forgot to break down by months. I think Dec/Feb will have the best chance to have the warmest/coldest anomalies among DJF, which is consistent with strong Nino analogs and model consensus for the E US. In the SE when we’ve had 1-2 big winter storms, they’ve tended to be mainly between the 2nd half of Jan and March. A major exception was the SE major winter storm of early Dec of 1896! So, of course, one never knows.

@Newman

[Newman]

2 hours ago, GaWx said:

 Hello Newman, 

 For this winter, I’m thinking (none of this should be surprising based on super Nino analogs/models):

-above normal precip (up to 3” above) within a couple hundred miles of the NE coast with highest anomalies near the coast and closer to normal well inland

-above to MA normal precip SE with the largest anomalies in the deep SE/FL, where 4-8” will be common

-anomalies tending to get colder as one goes further SE

-New England/NE US likely to average 3-5F warmer than normal with warmest in N New England

-Mid-Atlantic will likely average ~1-3F warmer than normal with closest to normal near coast

-SE likely averaging near normal to slightly colder than normal with coldest anomalies deep SE/FL

-Regarding wintry precip overall, the SE tends to do best anomalywise in moderate or stronger El Niño winters. But even so, much of the SE, especially deep, is unforecastable since it takes only 1-2 winter storms (often just 1) to make it a very wintry winter there. But that chance tends to be best with El Niño winters vs other winters averaged out. Strong+ Nino winters have tended to have the best chance though moderate may be close.

 

1 hour ago, GaWx said:

Oops, I forgot to break down by months. I think Dec/Feb will have the best chance to have the warmest/coldest anomalies amomg DJF, which is consistent with strong Nino analogs and model consensus for the E US. In the SE when we’ve had 1-2 big winter storms, they’ve tended to be mainly between the 2nd half of Jan and March. A major exception was the SE major winter storm of early Dec of 1896! So, of course, one never knows.

@Newman

I think we're on the same page regarding temps and precip and the overall distribution of positive/negative anomalies. I have some reservations regarding some of the climate long range model outputs, at least what they are predicting verbatim right now. The CanSips literally follows a climo Nino winter almost to a T, and I just don't know if I want to throw all my eggs into that basket right now. I guess it's why we don't write winter forecasts in September haha, the atmosphere still has almost 3 months to respond to the current Nino + things will become more clear once wavelengths shorten and the larger Rossby wave train settles into place heading into the late fall. 

Unfortunately the general public doesn't care if we nail temperature and precip departure forecasts... they care about snow. And that is just so hard, almost impossible, to predict with long lead time accurately without just getting lucky. However, in general, I wouldn't be surprised if the central Appalachians, up through interior portions of the Mid-Atlantic and Northeast, finish above average in snowfall. Coastal plain, NC piedmont, etc could get close to normal once the cold gets more established into late Jan and Feb nearer to the coast.