Newman

Temps are warm, but I definitely do think parts of SE PA can pick up 1-2" tomorrow especially if rates are heavy enough. I definitely wouldn't take the GFS 10:1 snow map seriously (well you never should), but take it as where the heaviest snows could likely fall tomorrow evening. As the secondary forms off the coast, you'll see the radar collapse likely and the QPF will dry out. There will definitely be a shadow effect when the transfer occurs. Here's hoping we can hold onto the small but potent primary long enough...

18z NAM QPF is juicy

Yep an uptick in QPF from 0z to 12z on the Euro

Little over a half inch. Puts me at a whopping 2.3" on the season...

Could not agree more. I'm very active on other NYC centered forums but it's tough with the clear bias. Here many of us experience the same weather and it would be great to talk more but it's not worth my time if there's only like 5 or 6 total members that post here lol.

Snow showers tonight

You bet

Snowing very nicely in Millersville. Roads are wet but decent coatings on grassy surfaces.

I think many here would take this and run with it for Tuesday. An inch or 2 followed by frigid cold to keep it around.

Just a heads up, Pivotal Weather now has free Hi-res ECMWF weather maps, including snowfall, precip type, etc. And it goes in 6 hour intervals, not 24 hours.

August PDO data: 2019-01-01T00:00:00Z 0.66 2019-02-01T00:00:00Z 0.46 2019-03-01T00:00:00Z 0.37 2019-04-01T00:00:00Z 1.07 2019-05-01T00:00:00Z 1.03 2019-06-01T00:00:00Z 1.09 2019-07-01T00:00:00Z 1.03 2019-08-01T00:00:00Z 0.38 August AMO data: 2017 0.222 0.224 0.164 0.280 0.311 0.305 0.299 0.307 0.347 0.430 0.349 0.361 2018 0.170 0.059 0.129 0.061 -0.004 -0.014 0.015 0.110 0.159 0.141 -0.124 -0.063 2019 -0.018 0.078 0.118 0.121 0.085 0.171 0.349 0.335

ENSO 3.4 continues to dive: ENSO 4 is as well with plenty of easterly wind bursts nearing 180W:

From 2009, talking about changing global circulations including Hadley Cell/Mid-Latitude Cell disruptions, etc.: http://www.inscc.utah.edu/~reichler/publications/papers/Reichler_09_Widening.pdf

Courtesy to Isotherm, he and I had a small conversation on the disruption of the global jet stream patterns due to the emergence of changing Hadley Cell and Mid-Latitude Cell circulations. As SSTs continue to warm poleward due to the background state and changing climate, we see more convection which acts to disrupt the typical Hadley Cell circulations we know. Typically we see rising air at the ITCZ which spreads poleward and subsides around 30N which creates the Horse Latitudes. With convection being able to fire further north, the Hadley Cell circulations expand which create stronger gradients and subsequently strengthen the mid-Latitude cells. For the United States, that means the Pacific Jet stream becomes stronger. What I mean as "this isn't new" is the warmth of the Pacific and overall global oceans. We've seen warmth of our oceans for awhile now. However, are we finally entering the critical time where we truly do start to see global jet stream changes? Are winters going to be the same again? Or will we see more variability resulting in bigger and more extreme winter events? Have we already seen those changes? I don't know the answers to those questions, but I do know that in theory the global jet stream patterns should be or have already changed in the changing climate.

The PAC jet is still raging due to Pacific Warmth spreading poleward and subsequently expanding Hadley Cells and strengthening the mid-Latitude cell (Pacific Jet). This isn't new, though. The Pacific overall has been warm for the past couple years to a decade. The question is how will the strong Pacific jet trend and/or affect the upcoming winter. Last year the Pacific was so hostile. Could we see a repeat?

ENSO region 4 has cooled in the past week and is at its coolest since a month ago: Likely due to a strong burst of easterly wind stress. The GFS forecast of a burst of westerly wind stress could help to bring the temperatures back up again:

Here's a look at how the SST's have changed since June:

1993-94 anyone? The ONI progression looks similar to what we could see this winter. Perhaps this winter is a touch warmer. Lets say we throw in 1993-94 for a similar west based warmish Neutral regime with its warm PDO and a cool 1+2, 2013-14 for its warm blob south of Alaska (I'm not sold on that blob going away just yet. 2013-14 had a cool Neutral/weak Nina), and 2005 just for its warmer and positive Atlantic/AMO.

New IRI/CPC ENSO probabilities have been posted: El Nino has ended: Here is what the July SST's looked like: The July AMO value finished at 0.350, up from 0.171 in June and the most positive AMO value since Dec 2017.

The current look, featuring cooling in the east based regions of the ENSO with western regions remaining warmer. The PDO is positive with a warm pool south of Alaska, but not to the extent of 2013-14 obviously. A cold pool east of Newfoundland in the Atlantic with warm waters immediately south of Greenland.

I've just started to look towards what this winter may deliver, and 2003-04 seems like a strong analog. It was coming off a prior El Nino winter, it was mainly weak Nino/Neutral during the winter, it had a positive PDO, positive AMO, and low solar activity. However, the summer of 2003 transitioned into a neutral phase much quicker than what is currently forecasted for this summer/fall/winter. I would throw in 2004-05 in case we remain more El Nino, rather than completely neutral. I like 2004's QBO transition into winter as well. It's much better than 2003 and it's close to what I think we could see this winter. A later transition of the QBO could yield later stratospheric impacts deep into winter (February and March, but things like that are fickle and require other variables to look at). 2004-05 also had a warm Atlantic and low solar, but not as warm of a Pacific. 1966-67 is a solid analog with regards to the positive ONI values maintaining closer toward fall/winter. And in case we go more Nina/neutral, it's even greater. That's what I see right now at least.

HRRR agrees with the WWA issued as well.

WWA across SE PA for 2-4". 18z NAM agrees.

Euro: