Isotherm

The MJO will certainly be an integral aspect of the entire momentum budget. As I noted pre-season, there were many variables likely to be fundamentally unfavorable for most of the season. Some of those background indicators should improve late-winter [e.g., the QBO]; however, the amelioration in the pattern may only be into a fair/mediocre one [though this would be improved versus the Dec-Jan mean pattern]. Many (not all) of the analogs I examined pre-season would tend to indicate a MJO circuit through 5-6-7, with diminution in 7+ beyond. As an aside, sometimes the background state overwhelms even a favorable MJO circuit. For example, last winter, we did have a 8-1-2 passage late winter, which improved the pattern, but not significantly so. The momentum transports have been unpropitious this winter, and we would need a quite significant vicissitude in that. All said, late winter should *improve* versus Dec-Jan as I've said.

I am uncertain whether I ever recall seeing such an expansive (or any) area of 32C coverage in that part of the world. These are 90 degree F water temperatures to the north of Australia. For such an anomaly in the deep tropics, it yields a significant impact on the energy budget as you know, and concordantly, it isn't surprising to see the modeled high amplitude in phases 4/5 of the MJO. This is akin to throwing gasoline on the proverbial fire. Ambient SST's of 32C/90F are very impressive. This will further serve to enhance the MJO in its unfavorable [from E US perspective] octants.

Here's a temperature departure composite of every January since 1990 that featured a MJO phase 4 RMM amplitude of > 2.0 in January: The ensuing February composite -- the resultant was rather mixed -- by my count, 4 warmer than normal, 3 colder than normal, and 1 near normal.

January 1978 featured a much more atmospherically engaged Nino signal than is extant presently. Pre-existing blocking over the high latitudes, in concert with a fairly coherent GWO circuit 7/8 enabled sufficient momentum induction to produce a conducive downstream synoptic. So, the MJO-4 and concomitant NPAC decay didn't totally extirpate the set-up. Finally, the southern stream/STJ was quite/more active than normal, again, reflective of much improved Nino engagement. Blocking already in place across the AO domain: STJ active: Auspicious GWO circuit:

@frd, thanks for your comments. Yes, I think the probability remains lower than normal for a SSW this season, although, if there is one, the most likely window would be February. Later winter SSW events are more prevalent in low solar/+QBO backdrop. The tropospheric structure for the next few weeks is largely unfavorable for potent wave driving/trop-strat energy transfer. However, it's possible we might be able to achieve more auspicious torque forcing and momentum uptick later in January via tropical engagement. Nonetheless, even if a SSW were to occur, that doesn't guarantee surface impacts as you know.

Hi, @psuhoffman -- regarding your inquiry. The modality of the AAM, as in, positive or negative, is not most integral - but rather - the distribution and transport of angular momentum through the hemispheres. My analyses pre-season indicated unpropitious transports, that would likely countermand the development and maintenance of significant/sustained high latitude blocking structures for much of the winter season. There's more to the entire methodology as well, so, what is stated in the outlook is only a skeleton of what I've analyzed. But, as said, the AAM distribution in concert with other variables, such as QBO timing/diminution, Hadley, Walker Cell behavior, among other factors, were all utilized. We'll see how the rest of the winter progresses. However, the present model/NWP trending in recent days largely comports with my expectations.

@40/70 Benchmark, great, detailed work as per usual. You are colder and blockier than me overall, but we concur that late season has the highest probability of inducing such action centers.

Thanks for your comments. Re November, most of them showed an amplified Pacific ridge w/ some Arctic assist, and a cooler pattern across the North/east, not too dissimilar from this year. The November amplification is quite common within a backdrop of more negative AAM.

My outlook can be read here: [also posted on the main board] http://www.lightinthestorm.com/

A strict construction of the ENSO-oceanic analysis may reveal neutral tending toward weak nino, but inclusion of the GSDM into the analysis yields a different conclusion. The total sum of momentum additions/subtractions evinces an apparent deficit/easterly momentum dominating the tropical/sub-tropical domains, and as such, retrogressive features will be the mainstay of the short to medium term. Whether the GWO neutralizes, thereby comporting more with the oceanic appearance remains to be seen.

@IrishRob17 @40/70 Benchmark, That is correct, I am not advocating for the once per day observation -- which is much different than capturing the maximum snowfall for the 24 hour period. Ray, to be clear, I am merely presenting the guidelines as they currently stand, which states that non-airport measuring should be maximum snowfall for the 24 hour period. I am not advocating that the 6-hr clearing is necessarily a bad method. I just think congruence with historical records is important and we never should have added the option for 6hr clearing in the 1998-2012 period. Per my discussion with Matt who works with the NJ climatologist, there was extensive debate among the people on the panel for this 6hr - maximum snowfall issues. Interestingly enough, the person who pushed most for the 6-hr method was the same person who reversed his thinking and signed off on the return to the maximum snowfall method. Snow measuring is an inexact science; there are arguments for both methods.

I concur with this too, I think they should have maintained the maximum depth standard.

Agree, and I'd argue the once per day observation is the least accurate of all for sure. The clearing/vs maximum depth should be fairly similar in most storms that aren't > 32F at the surface.

It's definitely a mess now. I'm not sure why there aren't clearer instructions disseminated.

Correct. This is per Matt G who works with the State Climatologist. "One final thing regarding this past event. We did receive a 31.0" storm total snow report in Kinnelon (Morris County, NJ) that no doubt got at least a little attention, as it would represent, as far as I know, the largest event total in NJ from the storm. I checked in with the observer, and he confirmed that he cleared the board 3 times mid-storm to reduce the effects of compression. Unfortunately, that makes his inflated measurement invalid, at least in the context of the current guidelines (though even with the 6 hour rule, this must have been more like 1 hour clearings), so we've nixed the value. BTW, I'll personally be working on crafting a NJ snowfall map tomorrow based on hundreds of reports received. I post it here when complete."

Prior to 1998, it was max-depth unless instructed. I think max depth would maintain more congruence w/ historical record. I've previously provided reference to the current NWS guidelines. I checked with the NJ State Climatologist, who specializes in snow cover and was very much involved in the crafting of the guidelines. What he was able to explain to me was that traditionally, the six hour option has only been available to professional observers at airports. However, back in about 1998 the NWS rules were revised and the six hour option was added for Coop observers*.

Per the NJ state climatologist: "When things were reconsidered in 2012, the 6-hour option was removed except for "when instructed." Now, I'm not sure of the frequency of this usage, but apparently the 6-hour option is not in use, only when instructed to do so by the NWS (usually airport).

They're not supposed to as per official guidelines. They should be taking intermediate depth measurements to capture maximum depth. Unfortunately, there is a ton of miscommunication on this issue. NWS airports do use it sometimes when advised (See last post).

Just as an FYI, the latest NWS/COOP guidelines for measuring snowfall are to take the maximum accumulation of new snow in a 24 hour period. The 6 hour clearing method is no longer in effect, unless specifically instructed to by a NWS office (airports sometimes). See the following: section 3.1 and onward http://www.nws.noaa.gov/os/coop/reference/Snow_Measurement_Guidelines.pdf The following is courtesy of Matt G. who operates with the New Jersey State Climatologist, regarding the official guidelines: I've previously provided reference to the current NWS guidelines. I checked with the NJ State Climatologist, who specializes in snow cover and was very much involved in the crafting of the guidelines. What he was able to explain to me was that traditionally, the six hour option has only been available to professional observers at airports. However, back in about 1998 the NWS rules were revised and the six hour option was added for Coop observers*. This was despite the protest of several people on the committee, as a higher up (I won't name names, but any snow weenie will know the name well) overrode them. When things were reconsidered in 2012, the 6-hour option was removed except for "when instructed." The same fellow who brought about the 6-hour allowance, oddly enough, signed off on the removal of the 6-hour option. All that said, the biggest debate on the committee related to the snow->melt-> snow in a single day situation, the same occurrence that has been argued about here. Ultimately, the compromise was made to simplify the guidelines and call daily snowfall the maximum accumulation achieved during a day, period. There's arguments to made both ways (and it sounds like there were among the experts on the committee), but ultimately, the guideline is objective, consistent, and most in line with historical practices. All that said, from what I've seen as a heavy user of Coop data and a state coordinator for CoCoRaHS, far and away the most common "problem" with snow measurements is that many observers (and from what I've seen, perhaps the majority of non-airport Coop) take their measurements once daily at ob time without making any attempt to capture the maximum accumulation. This is probably not a new issue, as I bet it's been relatively common through the years. But sometimes the differences between maximum accumulation and ob time measurement can be significant, so this is something I gently remind volunteers about, with the understanding that many are unable (e,g., at work or sleeping) or unwilling to take these extra measurements (some Coop sites, for instance, are businesses or municipal operations centers, thus not manned all day). It sucks, but we live with it. As for frequent board clearing, I suspect it's a relatively rare occurrence, though people still assert that the 6-hour clearing rule is the standard. I would not be surprised if even some NWS employees are not aware of the current guidelines (hopefully most are). It just won't die. One final thing regarding this past event. We did receive a 31.0" storm total snow report in Kinnelon (Morris County, NJ) that no doubt got at least a little attention, as it would represent, as far as I know, the largest event total in NJ from the storm. I checked in with the observer, and he confirmed that he cleared the board 3 times mid-storm to reduce the effects of compression. Unfortunately, that makes his inflated measurement invalid, at least in the context of the current guidelines (though even with the 6 hour rule, this must have been more like 1 hour clearings), so we've nixed the value. BTW, I'll personally be working on crafting a NJ snowfall map tomorrow based on hundreds of reports received. I post it here when complete. This is a good debate to have! Thanks for sharing your thoughts. * A note about Coop stations. There seems to be some confusion about what constitutes an "official" report, which is subjective in the first place. The airports are first-order stations that also double as Coop stations. The remainder of Coop sites are manned by volunteer observers, and their data also constitute "official" records in my mind, in that they make up the permanent climate record of the US and are quality controlled and archived in NOAA's NCEI GHCN-Daily dataset. For that matter, so now are CoCoRaHS data (if you are a CoCoRaHS observer, your data are a part of the weather/climate records archived at NCEI!).

Turned out much better than it seemed it would a couple weeks ago. Maples are mostly past peak here now, but still holding great color, and oaks are now peak. I think we'll see major leaf drop with the CAA event at the end of this week.

Still going to end up a bit high on NYC/LGA/TTN, pretty close on PHL/EWR. Happy with the call overall.

Cooling degree days have been the lowest probably since 2009 for our area. I only have 766 CDD's for year thus far, quite low comparatively after the past couple summers.

Agreed on all counts. Those numbers will almost certainly be too high. And yeah, definitely feeling much more fall like in terms of sun intensity now. Really noticing the lengthening nights.

16 here now. We're pretty much done given the upcoming pattern. Might be able to make the average of 18 for around here.

I like where I stand with my pre-season predictions; might even end up a tad aggressive for some areas: PHL: 28 EWR: 25 NYC: 16 LGA: 19 TTN: 21