Newman

Fv3 has snow on the 7th and an IVT for the Jersey coast on the 10th

I'm still sticking with around Jan 10th as when we see the pattern change and the 15th as when the show begins. The SSWE is already underway and will yield the AO/NAO blocking that we need. Then we wait for the MJO to cycle into favorable phases 7-8-and possibly 1. But if we can get the MJO to reach phase 8 and then enter the COD, that's so much better than having it enter in, lets say phase 5, because in that situation the unfavorable lag is even longer. I know we're all impatient but really there's nothing we can do. Personally, I think this stratospheric warming event is screwing this winter up, at least so far. We were heading towards the right direction until the MJO stalled in the unfavorable phases, possibly a result of the SSWE as Isotherm has alluded to in other sub forums. The cooler tropospheric temperatures in the tropics correlated to the SSWE likely induced a much better environment for the MJO convection to thrive, notably increasing lapse rates and increasing the convection. Stalling and enhancing the MJO in the unfavorable phases just eliminated a huge chunk of late December and early January due to an enhanced NP jet extension. Then we wait until mid January for any lag to wear off and the PAC jet to relax and what do you know we have a 1 to 1 1/2 months left of winter. Of course, we can still produce in the month of winter we have. Look at February 2010 for the upper Mid-Atlantic. You had the Feb 5-7th storm followed by the Feb 10-12th storm. Parts of southern PA picked up nearly 50" in that week alone.

You see the Euro? And I agree that around the 10th is our next shot. The 6z GFS almost looked like 2/5/10.

Flurries coming down. At least I know it can still snow.

Nice phasing from northern and southern stream on GFS.

The MJO RMM charts are likely not picking up on rossby wave interference. Here is a better look at the MJO progression. We should be in favorable phase 7 by Jan 4th or 5th based on this forecast. With lag taken into account, Jan 8-10th should be a good time frame for better eastern troughing to take shape. A jet extension could also help instead of hinder us here with increasing AAM, helping to pump the PNA ridge poleward. We want to see that Alaskan vortex retrograde to around the Aleutians which would ensure a better PNA orientation.

I still don't see anything that would make me nervous yet about this winter. Last year the MJO stalled in p7 for Feb (a warm phase in February) and likely aided in the SSW we saw that gave us the cold and snowy pattern in March and April. With the enhanced convection in the tropics, it likely resulted in more heat transport into the upper atmosphere and resulted in a perturbed polar vortex. The same has occurred this year except this year in December and in p5 (a warm phase for December). Now the enhanced MJO convection isn't highhandedly the only factor, but you can't ignore the similarities between a stuck MJO last winter to this winter and a SSW that followed. A SSW is on its way similar to last winter and will likely aid in giving us our core snow and cold from January 10th-March 1st. Our ENSO phase typically argues for a back loaded winter to begin with. No need to panic everyone, patience is needed. It's coming. Hopefully.

FV3 GFS for Jan 3rd

I guess our next "threat" is going to be around Jan 3rd-4th. Once the New Years rainstorm comes through, it'll leave cold air in it's wake and drop a boundary along the coast where a wave will likely form along it. Anafrontal systems typically favor coastal areas but we'll see how things trend as we get closer.

Check out the MJO RMM charts. Models completely underdid the amplification into phase 5. We now have to wait for the MJO to cycle into cold phases 8-1-2 but that will take longer due to the extreme amplification into p5. Not only that but we need the SOI to take on a -7 or lower value. That ensures a more El Nino central PAC jet. We're stuck in a La Niña type atmosphere due to the Pacific Ocean temps not fully coupling with the atmosphere. The past couple weeks have been nothing but a disappointment. We'll have to wait until Jan 10th and on, perhaps later, for the MJO to fully cycle around.

The GEFS show plenty of potential for the New Years time frame.

GEFS members for the 24th. Quite a few bring snow to the region, especially NW

Not everywhere is going to get 4", but some localized areas likely will with the convective thunderstorm potential. The 3k NAM shows the localized nature. Parts of Lancaster/Berks get only 0.5-1" of rain yet Carbon/Monroe counties get 3-4". How much rain one receives will be highly determined on the localized training thunderstorm potential.

Philadelphia averages 2.5" through November and December. The November storm this year dropped around 3.5". Even if no snow falls the rest of December, Philly will still be above average heading into January. The same goes for Allentown area. If I use ABE averages for my area, I should average 5.3" through November and December. I am at 8" for the season.

Actual snowfall on the NAM: However, north and west will definitely experience a bit of freezing rain and sleet if this is right:

If you are taking that map verbatim I wish you all the best. I'm not even going to waste my time trying to explain.

We went from 65 and torch this weekend to now sleet/snow mixing in for north and west:

Just to play around with, Member 18 on the GEFS shows 3 straight snowstorms around the Christmas time frame. First storm on the 23rd: 2nd storm on Christmas (biggest one): 3rd storm on the 28th:

A lot of models have the bias of holding back the trough in the west around the Rockies, but the EPS is notorious for it. Lowering thicknesses because of naturally colder temperatures due to high elevation correlate to lower average virtual temperatures, which lower thicknesses again, lowering average virtual temperatures again, creating a bias toward amplifying a trough over the Rocky Mountains. However, all you have to see is the AK ridging that correlates to a trough in the lakes/east. The 23rd to 31st time period will feature a storm for most of the Philly area IMO, likely west of 95. This look will produce a storm on the east coast. Wet or white TBD as we get closer.

The AK ridging will continue to grow in merit as we enter the latter half of December. The Aleutian low, however, will determine how it sets up. If it retrogrades far enough west we will have a much better look than if it stays put in the GOAK. Looking at the EPS, you can clearly see it correcting it's bias of dumping the negatives into the west coast and forcing a SE Ridge to pop. This isn't me wishcasting or anything. Do your own research and look back at this entire winter so far (and other winters for that matter) and you can clearly see how the EPS corrects over time from a trough out west to a trough in the east. The GEFS, and the GEPS to a lesser degree, have been schooling the EPS the past couple of weeks with regards to this pattern. The EPS was arguing for a 5-10 day period of warmth and now, what do you know, we're looking at a transient 3 day mild period, if that. Blocking will likely grow more likely as we get closer to Christmas as well with a SSWE likely. However, we're not going to see a huge 4-SD block, but rather a block just strong enough to hold down the SE ridge. I really like what I'm seeing after the 23rd. BTW, I wouldn't put too much stock into the MJO phases we're going to be going through. Although a phase 5 would argue for warmer east coast conditions, the MJO will be rather weak and the ENSO phase will likely override that. A P5 MJO in the current ENSO phase (Region 3.4 at .5C or higher) actually results in N to BN conditions in the east.

Thursday possibly some snow showers.

The Christmas time period is really intriguing me. Let's see how this looks a week from now. IMO we don't need high latitude blocking. In fact I'd much rather ride with a -EPO and +PNA. The key piece once we get towards the 20th is how the vortex in the NP acts. If it continues to sit in the GOAK then warmer temperatures will be much more likely than if it retrogrades west into the Bering Strait. Also, I'm hearing plenty of talk about the possible SSW that may take place towards the end of December and January. I'd like to caution that, if the SSW event does indeed come to fruition, it may not be a good thing. If the vortex gets displaced towards the Asian side of the pole, we may be wondering why we were jumping up and down for the event to take place in the first place. Also, the SSW may interrupt the entire evolution of our winter. I feel we are entering winter with plenty of upside already without a SSW. I'd take my chances rolling through winter without any stratospheric warming. Of course it could always help but, like I said, I'd rather hedge on the side of caution.

The trough is back in the east by the 23rd. The GOAK trough will retrograde west to the Aleutians, build the ridge west with it, and dump the trough into the east, aided by the MJO, AAM, and a more favorable NP Jet.

These snow showers are pretty nice right now. Snow sticking to everything with how cold it is: