frd

Like clockwork

Continued downward

Watched a great webinar about the upcoming winter featured by BAMMWX I took some notes while watching - was an awesome presentation. I did the best I could writing down the most important points. Analogs temps: 77/78 79/80 03/94 95/96 04/05 Analogs precip : 95/96 77/78 79 /80 93/94 Main warmer risk is that the Eastern ENSO areas warm up from the current levels. Month with the least confidence, December. Most confidence in Jan., Feb and the shoulder month March. ( cold, active, snowier ) Last years SH SSWE caused the SA Easterly wind signal and warmed the Eastern ENSO and impacted the winter . Impacted the MJO and the Jet. There is an association with SH's weather events/ SSWE , etc. and the effects on the MJO phase and movement in the Western Pac and the Maritime continent BAMMWx expects more phasing potential this year in the East, more STJ , etc. Biggest concern here the STJ outruns the PJ but they believe that will not be the case this winter. Can't ignore the last 18 years worth of Decembers, but there are significant signals that this December could be cold ( just be aware the ENSO argues against it to a degree, versus other factors that support it ) Early Season PV formation, shape and location are conducive to the delivery of cold air masses over the US. Different than other past early season PV. Solar min very significant , Sept 2019, lowest sunspot number since 1901. QBO, during the past 7 days has descended more than the past two months. QBO phase and shear favorable for cold in the East Interesting note that this year argues against splits but a weakened more elongated PV is favored. Also, the current location over Canada may be very hard to move and may favor our side of the pole. Other thing to consider robust NH snow cover. Able to deliver fresh arctic air masses into the NE Neutral ENSO combined with a + IOD leads to a cold East ( 3 rd most + IOD at this time ) + QBO at 50 mb lessens the MJO or keeps it closer to phases 8 , 1 and 2, much different than last year. Cold winter phases are most likely . This is already happening According the BAMMWX the PDO is not the biggest driver. + PMM although not as positive recently, there is still a very strong signal for a tall North Pacific ridge and a trough in the East in December. There is also the association of a more enhanced STJ as well. Can enhance phasing as well. Overall BAMMWX going with a colder December and a generally cold and snowy winter forecast. Some other notes - ENSO set up - most important is the placement of the warmer and cooler anomalies - currently Warmer West , much cooler Easter regions. Latest data, sub surface warmth increasing in the Western areas ENSO is the main factor against a cold December in the East Kirk mentioned he expects a change in the weeklies soon, and that many times the reason the Euro weeklies and seasonal do so poorly is a poor initialization CFS HDD doing a lot better EURO with a 8 to 14 point warm bias days 9 to 14

Even areas that scored last November with snow went on to meager seasonal snowfall totals. I am stirring the pot about December. I can see this December going in several directions. It could buck the trend of recent years where November was cold and then the following December went warm or warmer. Hm's post about the period after 12/20 makes you think. Last December had the feeling it would be a more normal month until the ensembles starting painting a different picture. Several forecasters had a snowy holiday period but alas that did not work out. We very well could cycle back to a favorable pattern later in December , even if we turn milder at some point. Again for us, it would be great to get a Western based - NAO in December to increase our odds combined with a -AO.

We cold November , we roast in December , unless you wan to gamble against the new normal. Maybe a December - NAO will provide the means to a colder outcome in the East .

Sea ice recovery update from Bring Back over at 33andrain below. Nice to see this robust recovery ( off of all time lows ) and goes along with rapidly building NH Snow cover. Bring Back, ( David ) does a great job at explaining everything about sea ice. IMHO my take on this right now is a robust cryosphere is developing and this raises the possibility that in the next couple of months a severe arctic outbreak is possible in the East. from David : <<<<<< Another 250,000 sq km of new ice yesterday! Right now the record rate of 1 m increase every 4 days persists! While this incredible rate cannot be sustained much longer, I do feel that 2019 will exceed 8 m sq km by this weekend and that will put it ahead of 2012, 2018, 2007 and 2017 in that order (with 2016 passed yesterday) and not far off 2010. In other words 2019 over just 2 weeks will recover from by far the lowest extent to exceed the decadal mean. I should add (as I do in my longer posts) that this does NOT mean that the overall 2019/20 winter Arctic ice extent will end up any better than in other low extent recent years. Let's hope that the conditions remain conducive for a continued strong recovery. The express recovery rate continues: >>>>>

With all the talk about using only recent analogs and all the repeating warm Decembers periods, especially later in the month, as HM brings up post 12/20 , I found this post enlightening. Wonder if this year we buck the trends and persistence of the post 12/20 period? So, looking at the data - Nina-like is a chillier December and Nino-like warmer, makes sense. This year though we have a variety of drivers, how they interact will be very interesting.

Brrr......... having to buy several Chapsticks...... , one for the car, one for work, and one for home. A critical need for us weather weenies.... Plus, I keep losing them, then I freak out. Solution - buy a lot ! Early November looks cold with very low dew points !

Seems in the process the Hudson Bay vortex moves further South , more so than typical. Maybe an indication of an eventual discharge of very cold air down our way in early to mid December. Speaking of December -

Euro monthly interesting with a disrupted PV further into the month of Nov. Also, as mentioned by HM recently, a couple drivers are present to provide stress to the PV I like seeing the Aluetian Low - Scandinavia High combo later in November showing up. Matt Hugo is all over this. Meanwhile, we have the QBO continuing to descend, rapidly building snow cover across the entire NH and low solar min with short-term quiet condition continuing, all in our favor currently. I like what I am seeing and starting to get just a bit excited for the prospects of holiday cheer.

Some mets are saying whatever happens in the winter, whether warm or very cold will feature extreme events, with anomalous low pressure and deep troughs. Of course the areas to be hit is yet to be determined. However, based on the recent change in sensible weather in the NE, high precip, high wind events and national headlines regarding storms you think there is some fact to these ideas actually becoming reality in the period December to March. Do you think we have an active winter in the East ?

Tasty

At least we are not looking at a 2018-ish playbook.

Not bad..... as you said, steady as she goes.

Great read brought over from 33andrain The met there hits on everything we have been talking about. Enjoy <<<<< Member Meteorologist 290 54 posts Location: Hackettstown, NJ Report post Posted 1 hour ago I'm going to try to post a final outlook of sorts within the next week along with a longer commentary...no huge changes to my thoughts, though did make it a bit colder in the east. In the meantime, I do have a few general thoughts based on what I've been seeing here and on #WxTwitter. The PDO right now is very close to neutral. The September value from NCDC was 0.00. I've highlighted in blue areas that would suggest a negative PDO, and in red areas that would suggest a positive PDO. It remains very close to neutral, and the "cold" waters near the West Coast aren't particularly cold. I look at it as a neutral PDO but with a highly anomalously warm North Pacific. If anything it may trend a little more positive over the next few weeks, but not enough to really move the needle IMO. For reference, here's the JISAO plot of a negative vs positve PDO: I guess my point is that while it's not a classic +PDO, it's definitely not "tanking" and will likely be close to neutral for the winter barring some fairly substantial changes. I also want to stress that the little sliver of cooler water near the West Coast has no ability to force a pattern in the future. It's more a reflection of the pattern we've seen frequently since September. It's possible that pattern is a sign, but the SSTs themselves don't force anything (it's a small area of near average SSTs in an area where SSTs are too cold to strongly force anything). For instance, the ridge over the next 10 days doesn't seem to mind the little bit of cooler water near the coast: The 6-10 day 500mb in winter (even without longer wavelengths) would already by a pretty chilly and active pattern from the Ohio Valley into the northern Mid-Atlantic and New England. With regards to the western US trough and SE US ridge, I still think it's way too early for it to cause any concern for winter. We just had an exceptionally long-lasting and amplified phase 1 RMM (it was more of a standing wave than true MJO, but registered as a phase 1 MJO). It was in "phase 1" for nearly a month and didn't come close to the "circle of death": When the RMM is phase 1 in the fall it correlates to warmth in the eastern US and cold in the west, which is what we've seen plenty of. Wavelengths are beginning to quickly get longer as we transition to winter...this same forcing would result in a different pattern in winter. Compare the September-November phase 1 temperature correlations to the December-February ones....basically, a SE ridge is what we'd expect with the tropical forcing we've seen and it's what we've gotten. In winter the same tropical forcing on its own supports a much colder outcome for the eastern US: The ongoing and near term intensification of the stratospheric polar vortex is of some concern if it continues unchecked well into November...the upcoming pattern is literally the opposite of what we want for PV disruptions with an Aleutian Ridge and Scandinavian Trough, so it's no surprise we're seeing impressive intensification, which could well lead to a spell of milder weather around the middle of November: With some hints of a +EAMT during week 2 and some ridging developing over Scandinavia...with the CFS and EPS weeklies hinting at some Pacific tropical forcing returning during November to go along with impressive Siberian snow cover supporting a stronger Siberian high, there are ways to disrupt the PV going forward. We'll see if anything comes to fruition. The lack of a classic Aleutian low thus far is likely a part of the longer running -GWO, and if that continues then Wave 1 disruptions may be limited (a Scandinavian ridge is usually wave 2). Most of the analogs that have the most blocking have an Aleutian low by October or November which can disrupt the PV via Wave 1 forcing, so this is going to be interesting to watch and see if we can get enough disruptions elsewhere. Long story short, I still generally like where we sit, but if we don't see disruptions to the PV resume in November then the prospects of a warmer December with a +AO increase. >>>>>>

Please don't think because I put Cohen up there I endorse him, I certainly do not . But, I do endorse the potential that the PV will be put under pressure in some form or fashion as November moves on. Simple referring to the potential warming. I do not want to see a SSWE either and will be perfectly happy with a weak PV.

Hearing a lot of conflicting comments on the PV. Taken from John going very strong, of course, how strong it verifies is not certain. The GFS portrays what @C.A.P.E. mentioned. HM chimes in wisely and takes into account some things the average person doesn't focus on, as well as a previous good read. Here are some of the latest thoughts on this. Little sensational if you ask me. then from HM Anthony Masiello @antmasiello 2h Replying to @jhomenuk The shape of the polar vortex is just as, if not more so, important than u-wind strength... especially during the early season when it's normal to strengthen. John Homenuk @jhomenuk 2h Agreed 100%, and still think there is a degree of uncertainty in anomalous the u-wind gets too. But as you alluded to, many different layers to the actual impact of a strong spv including its shape and location. From a u-wind perspective, forecasts are impressive tho A nice refresher from HM

@C.A.P.E. Not very scientific, but comparing week 39 in 2019 to week 39 in 2009. Generally speaking we are doing well. No associations are being made, except the backdrop of a low solar min. If, we can get sea ice to bounce back to a degree, and it should in the next 7 to 14 days, might be interesting weather around these parts later in the year. Row Year Week N. Hemisphere Eurasia N. America N. America (no Greenland) 1 2019 39 8.91 3.52 5.39 3.24 523 2009 39 6.29 1.21 5.08 2.93

Loving the build up of snow ! Bring it on ! Nice visual and even signs of a sea ice recovery. Of note, the area North of Alaska is cooling. Implications for the late December and Jan pattern. I could speculate we are going to end the month on a high note, and only continue to build from there in early November.

Things such as ozone also factor in, as HM mentions this from time to time as well. One Fall many years ago there was chatter among some pros that focused on a sudden ramp up in solar activity near the min. This might have been the solar min prior to the 09 - 10 winter. I was looking at various factors lately and it certainly it appears no worries, we continue to move lower in many of the metrics.

BAMMwx ( good winter seasonal record ) has very high value placed on solar min this winter, while some research has the solar min effects on ocean currents take a multi year lag to manifest itself. As far as I can tell we are close to a bottom.

Well you are in good company , Benchmark thinks we get a -NAO. In 8 days I think isotherm releases his forecast and I am found of his work forecasting NAO phase. From a simply solar min perspective it tends to show up, although some research, as you know, states a lag period.

@showmethesnow good post but I can't stop having concerns for our area in the heart of winter until we see some type of change in the ongoing long duration pattern. I really didn't even notice this in a general sense, but Eric Webb posted recently that what we are seeing is the same general pattern repeating over and over, for a period of years. For the last year I have seen the same issues manifest themselves in the Pacific, the semi permanent Central Pac High, robust WAR, the Pac configuration of SSTS, the very fast Pac jet, lack of West Coast ridging , etc. The areas that are benefiting from this so far are the same as last year, Northern Plains, Rockies, and when it gets deeper into the season areas to our far North will join the list. What are your thoughts when this multi year pattern changes? showme, one caveat IMHO, if get Davis Straights blocking develops, or shift ridging out West East a bit in our favored climo period, then bang you can have a severe winter outbreak here. Here is what Webb said: Eric Webb @webberweather This pattern goes back to 2012-13* and has persisted in some way, shape, or form in every winter besides the 2015-16 Super Nino. There's very little, if any reason to believe it won't be around this year.

Back edge moving in quick here. Going to be a remarkable change from the heavy rain and darkness now to sun later afternoon.

Well now, this is a surprise, really taking off. Granted only a forecast, but still rather concerning in view of some using this data as a means to associate the seasonal models and the crap AO and NAO forecasts. Not what we want to see. courtesy 33andrain posted 3 hours ago from Snowy Hibbo <<<<<<<< Well that throws the forecast for a decent December back to the drawing board. At least: what goes up must come down. >>>>>>>