frd

This recent cool to cold period in our area is even more impressive when you consider it bucks the trend of the last 10 years, and also counters what in our area is the month with the most warming compared to normal during the past 30 years. Indeed, as mentioned before, the warm Atlantic has extended the summer well into October many times here recently. Many locations have set record highs late in the warm season on the periphery of the warm Western Atlantic waters/ WAR .

Any comment regarding the IOD being totally opposite last year ? Long range models seem to indicate it goes more so negative as the year ends. Nothing like last year with the extreme positive values in December and continuing into Jan.

Been watching the satellite animation and it is making progress my way. Just took my Greyhound for a mid day walk, very breezy and cooler. I admit, I do miss the blue sky look, has been a week with only haze, smoke or simply cloudy. Have a great weekend mappy !

We have new records.

I believe Ninas may tend to have colder Decembers versus Jan. and Feb. Means nothing, and I am not endorsing a cold December at this point. However, exposed waters above Alasaka and general SST forcing way up North may have a role in our sensible early winter weather before the most powerful and direct pattern weather drivers take hold for the East.

Does make sense. The exact location of anomalies and how strong in mid to late Fall will be very important in attempting a December forecast.

Yummy.... the Holly Grail

BAMWX put together a very detailed and research based presentation rich with relevant data and analogs for the winter outlook of 19-20. The presentation was over 30 minutes long, given in November of 2019 for the winter of 19-20. Guess what, they blew it, they had to back pedal until stating they were wrong. They were very confident in a cold winter. Going too cold and too snowy overall. Of course they spin it, by stating they adjusted their winter forecast to counter their early seasonal forecast. In my opinion, that is still a fail. No one really knows what is going to happen. After two years of incredible busts regarding winter outlooks by everyone, the bottom line is that you should never put faith in a winter seasonal forecast that depends on cold air intrusions. It is a different climate now, with new evolving drivers on a global scale. You can even share the insights and opinion of tip over in the New England forum, whom states that regardless of Nina or Nino it does not matter at all, because a small area of the Pacific cannot counter the global warmth and the corresponding accelerating global warmth drivers.

In the short term yes. As in today, temps in this region will average 2 to 5 degrees lower versus without the smoke effect on solar energy. However, this is an interesting thread below discussing the effects of Western fires on the stratosphere. As Anthony points out some interesting outcomes on the winter AO and even the development of the early season PV. The thing that interests me the most is that in the Nature. com abstract below it discusses the 2017 " Pacific Northwest event " . Keep in mind that the current fires on the West Coast and other areas are far more impressive in terms of release. Also, keep in mind the similarities , as mentioned in the abstract of volcanic intrusions. Also there is this literature https://www.nature.com/articles/s41612-018-0039-3 Abstract Intense heating by wildfires can generate deep, smoke-infused thunderstorms, known as pyrocumulonimbus (pyroCb), which can release a large quantity of smoke particles above jet aircraft cruising altitudes. Injections of pyroCb smoke into the lower stratosphere have gained increasing attention over the past 15 years due to the rapid proliferation of satellite remote sensing tools. Impacts from volcanic eruptions and other troposphere-to-stratosphere exchange processes on stratospheric radiative and chemical equilibrium are well recognized and monitored. However, the role of pyroCb smoke in the climate system has yet to be acknowledged. Here, we show that the mass of smoke aerosol particles injected into the lower stratosphere from five near-simultaneous intense pyroCbs occurring in western North America on 12 August 2017 was comparable to that of a moderate volcanic eruption, and an order of magnitude larger than previous benchmarks for extreme pyroCb activity. The resulting stratospheric plume encircled the Northern Hemisphere over several months. By characterizing this event, we conclude that pyroCb activity, considered as either large singular events, or a full fire season inventory, significantly perturb the lower stratosphere in a manner comparable with infrequent volcanic intrusions.

Fascinating smoke effect on temps today, as discussed by Mount Holly in the near term update: NEAR TERM /UNTIL 6 PM THIS EVENING/... Smoke from the western wildfires continues to have an impact on the region and is expected to remain over the forecast area today. The SO2 GOES RGB product highlights the thickest concentration generally from around central PA/NJ northwards. With the lack of in person observers overnight many of the ASOS`s are now indicating clear skies but expect that to change with day break. In coordination with surrounding offices, we`ve increased the forecast sky cover to reflect that conditions this afternoon will be rather hazy although not "cloudy". The net effect on the weather will be that temperature will not warm quite as much as they would under typical clear sky days. So I`ve undercut temperature guidance by around 3-5 degrees suggesting highs this afternoon should be around 70. Normal for mid September should have highs in the mid to upper 70s so with the smoke aloft we`ll be below normal with relative ease even under southerly warm air advection.

Actually it is deary outside, beyond the temps. With the lower sun angle will take some time to get some real sunlight to filter through. Forecasts should do away with sunny and replace with haze and or smoke. Heard tomorrow may be worse as the smoke is closer to ground level.

Surreal look at sunrise with crisp Fall like air, yet a milky, smoky sky above. Temp at a remarkable 47 degrees here at 630 AM. What a quick turn around from just a couple weeks ago.

Where have we seen this before. Will be interesting to observe and speculate on the late Fall implications, in conjunction with SST forcing.

Seems like a bottom 2 percentile - EPO is possibly within reach, if so, very remarkable for September post 1948 dataset. .

JMA for next 3 months. If the Nina's most significant measured drop occurs in the period late October to early December, with a possible lag effect , December could indeed be a cold month in the East. Followed by the real winter pattern of warmth dependent on other factors of course. Still feel the positioning on the High pressure in the Pacific will be the driver, and any appearence of HL blocking. GLoSea mean may indeed be skewed. Also as HM stated the model may have sniffed out the extreme + IOD last winter as the driver to little if any NAO and HL blocking during the 19=20 winter. This year is the IOD is opposite, so what to expect is uncertain in my opinion. As mentioned previously, the poleward High and positioning, in a Nina with a + QBO as Griteater mentioned may have a role in our weather. The sample size has to be considered.

I have seen neutral, Nino and Nina comparison snowfall scatter plots for December through February in the Northern Mid Atlantic which shows we tend to achieve the highest snowfall in a moderate to even skewed stronger Nino. Possibly, as you mentioned, in a Northern stream dominated Nina and dependent on where the cool anomalies are located in the Pacific the temp profile in our area versus a Nino may be colder. The image itself lends to confusion and has little value if you ask me. Just as all Ninos are not the same, the same can be said of Ninas. Of course, as mentioned here previously you really need the establishment of NAO and HL blocking for true winter block buster events in a Nina background state.

Upcoming time period might possibly be the best in recent memory to over seed cool season lawns in this area . Diminishing competition from weeds, lowering dew point with reduced disease risk, combined with ideal decreasing soil temps. Target for fescue and other cool season grass seeds are soil temps between 50 and 65 degrees F. , and your corresponding air temps between 60 and 75 degrees F.

ALL IN

I have mentioned this before, along with various posts by bluewave. Anthony has an entire series of posts on this. And without a doubt this trend continues. The focus, well the enhanced area of higher heights near the East Coast between May and October during the most recent 10 year period.

Nice work by HM and cool animation

A little more detail From MH AFD .NEAR TERM /UNTIL 6 PM THIS EVENING/... The band of showers associated with the frontal wave, which has lingered over central Delmarva and far southern NJ the last few hours, should push offshore shortly. The cold front which has only made slow southward progress (as these weaker fronts often do) overnight will accelerate southward this morning away from the area. High Pressure building in behind the front over the Great Lakes will foster a dry N-NE flow over the area with dewpoints steadily dropping N-S through the day. Can`t rule out a few showers over the far south this morning (closer to the convergence zone and the better moisture) but guidance has trended more aggressive in drying us out, so confined mentionable PoPs to southern NJ and southern Delmarva.

As the day progresses according to the AFD from Mount Holly . Your area first then me later .

The GloSea5 did well last year. However, to me that means little for this winter.

The morning Mount Holly AFD commented there was better agreement between the Euro and the GFS overnight, and that the front washes away as it nears us Sunday, and the threat of excessive rainfall on Sunday has diminished. Sunday may indeed be dry.

As many here already know, the QBO is currently positive and looks to continue to become more so in the months ahead. There is some research that points out a tendency for a more poleward based and oriented North Pacific Ridge during +QBO winters. HM mentioned that, along with a couple other mets as well. @griteater recently mentioned it too in a detailed and revealing post. I found it so interesting as to share it here. Nice job with this ! Here is the post below : . The QBO is utilized in various ways with respect to seasonal forecasting, but IMO, it's best use with winter forecasting is not so much with the AO/NAO, but rather, with the configuration of the North Pacific High/Ridge that is common during La Nina winters. A North Pacific ridge is almost certain to be present in the mean pattern during Cool ENSO / La Nina winters when the Jul-Oct averaged AAM is negative (which has been the case thus far for Jul-early Sep). Anthony Masiello's findings from 2012 showed that more poleward north pacific ridges were favored during +QBO winters, while north pacific ridges that were suppressed to the south were more favored during -QBO winters. A key element here is that the designation of the QBO for this purpose was in the lower stratosphere (roughly Nov-Feb averaged at 45mb) as opposed to the typical level used with QBO analysis which is at 30mb. While the QBO began to behave much more erratic than normal at the first part of 2020, it appears to have resumed with a more typical progression as the positive QBO has more firmly established itself in recent months in the middle stratosphere and descending into the lower stratosphere. For the upcoming winter, I would anticipate the QBO to average positive for Nov-Feb averaged at 45mb - most similar to the winter of 2010-2011 when compared to other cool ENSO winters. See QBO Charts: NASA QBO Chart Free Univ of Berlin QBO Chart Below is a list of what I have for the last 11 La Nina winters that followed El Nino, along with the Nov-Feb avg 45mb QBO, then the placement of the north pacific ridge averaged for Dec-Mar. La Nina Winter That Followed El Nino Winter / Jan-Feb avg QBO at 45mb / Placement of North Pacific Ridge avg for Dec-Mar 2010-2011 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW) 2007-2008 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW) 2005-2006 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW) 1998-1999 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW) 1995-1996 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW) 1988-1989 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NE) 1983-1984 / Neutral QBO / no clear distinction overall in the north pacific 1973-1974 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW) 1970-1971 / Negative QBO / north/poleward north pacific ridge (specifically, displaced to the NW) 1964-1965 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW) 1954-1955 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW) Of the 11 winters, the only one that didn't follow the QBO/North Pacific Ridge placement theory was the winter of 1970-1971. Here are 500mb Height / U.S. Temperature composites of the Positive QBO winters from the list: And here are 500mb Height / U.S. Temperature composites of the Negative QBO winters from the list (I left off the 70-71 winter): Clearly, the Positive QBO composite with the more poleward north pacific ridge offers more potential for cold air intrusion into the lower 48 east of the Rockies compared with the Negative QBO composite. One other thing to look for is the Oct-Nov 500mb pattern over the NE Pacific / Alaska / NW Canada. Winters with a more poleward north pacific ridge tend to be absent of negative height anomalies in the Bering Sea, Alaska, and NW Canada during Oct-Nov....while, winters with a more southward displaced north pacific ridge tend to contain solid negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada. Bottom Line: I would expect the upcoming winter to exhibit a more poleward north pacific ridge in the mean pattern as long as: 1) the QBO progression continues in a more typical manner as seen in the past few months, and 2) the Oct-Nov averaged 500mb pattern doesn't contain negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada