ORH_wxman

The bolded is very concerning IMHO. That is the model for taking out local wx knowledge and replacing it with cookie-cutter forecasting.....and winter wx is probably the best example of forecast skill degradation when not knowing local climo and terrain effects. I know we've talked in the past about how you see people who aren't familiar with ice storm climo in New England applying the plains idealized model and it usually will cause you to get the forecast exactly backwards here. But even on snow/sleet events not knowing local climo hurts a lot. Esp WRT cold air damming in New England.

Yes on both I think....though who knows for sure on the 2nd question because previously that Dec 9-10 system has been getting crushed below us....more troughing out west might push it north into us. But that's only on the current iteration of the pattern/threat. The shortwave could look different on future runs.

To me, the "less hostile" phase is the 12/12-12/15 period and then it looks like it actually gets favorable post-12/15....but of course, "less hostile" PAC with that NAO block is still pretty good. The "less hostile" PAC allows the SE ridge to weaken/retrograde.

Again, the developing pattern had 3 phases to it: 1. The block actually evolving and setting up shop....that is Dec 3-7. We see a couple milder systems during this time. 2. Block is established, but we are fighting the SE ridge before it retrogrades. This is Dec 8-12....we can sneak a wintry system in this period but it requires good timing and it's dealing with the gradient between the block and the SE ridge. 3. Block fully established but it has peaked in strength and SE ridge has retrograded further west allowing for more potential amplification of systems over the east. This is like 12/13 and beyond. This is the period that looks most favorable for larger systems.

I don't think that is totally true....we initially said post-Dec 5th....and then it was more like post Dec 7th.....I still think the latter is mostly true. Dec 9-10 is def still on the table. But we're fighting the SE ridge maybe 2-4 days longer than initially progged. We did say recently that it looks much better after 12/12 and that is still true. EPS might look better a day or two sooner than GEFS, but these are trivial details at the moment.

If there's one thing that is proving to be very true of what we said days ago, it's the model volatility on individual threats. It's going to be quite frustrating from a forecasting standpoint....you'll get all sorts of weirdo solutions...esp beyond D6, but I wouldn't be surprised at volatility even inside of 6 days.

Yeah the GEFS seem to be leading the EPS a bit, though the EPS caught onto the NAO block better and earlier. GEFS seems to be doing a little better in the PAC recently. But we'll see if that continues or just a random occurrence. I don't think the differences matter a ton though for now....both still have a shot at something around Dec 9. GEFS prob have a better chance of us seeing something ugly like a cutter pre-12/13 (and post 12/7) than the EPS does. I noticed the EPS retrogrades the NAO block further west than the GEFS does, so that could also be affecting the pattern too.

Biggest disagreement on ensembles right now is around that Dec 11-12 period....EPS are better looking than GEFS. GEFS don't have the ridging out near Rockies that EPS have....GEFS eventually do look very good, but they wait a little longer.

Maybe we actually avoid the grinch this year.

We fight the western troughing until around 12/12….which is what helps keep the SE ridging stout. The Dec 7-8 system though gets pinned under the block and provides enough confluence to give us a shot for Dec 9-10 if it can amplify enough. One good trend in the past 24h is pretty good agreement that the PAC gets a lot more favorable beyond 12/12. Our best period might be 12/15-12/25 with the combo of decaying NAO block and a vastly improved N PAC.

Dec 9-10 I think is our best shot until post-12/12 when the southern ridge starts retrograding.

Happy birthday old man winter. Keep them coming.

I remember when we had a massive cutter on 12/12/10 in the middle of that monster block and the meltdowns were just epic. Stuff like “the cutter should be impossible because there’s a -NAO”. Lol.

The first thing I always looked at when forecasting for the monadnocks and ORH hills in Decembers was to pull up the SST anomaly map

The most hilarious part of the reasoning going with the anomaly map is that the lowest anomalies were over New England from interior New Hampshire to interior MA….. You can tell instantly that person has had almost no experience forecasting in New England.

The Pacific is definitely the biggest difference between the GFS suite and the ECMWF suite. GFS has been screwing around with the troughs out west more aggressively than the Euro.

18z gfs digs a western trough in Mexico….shades of Dec 2021

Pattern change set in during early Dec 2010....here's what it looked like for 16 days Dec 5-20, 2010.....BOS, ORH, and PVD all had zero measurable snow during this 16 day stretch. BDL had 0.3" from a squall I think. This isn't trying to scare anyone, but it reiterates that great patterns can sometimes not produce, or take a while to produce. WE know it eventually went gangbusters, but it didn't happen right away. OTher years like 1995 it happens almost right away.

I still think we need to watch the follow up wave (Dec 9…maybe as early as Dec 8 or late as Dec 10) for something. It wouldn’t be huge but it could be one of those fast movers if things align.

People want clown maps that show good snow. That’s really what the anxiety is all about. Deep down many won’t admit that it’s the OP runs not showing blizzards is what is concerning to them….it’s not the ensemble mean they are concerned about. You’d think it wouldn’t be that way since most posters here have been on these forums for years (if not decades).

The control run was more for me and Tip

Ray ran P16 member from his basement

The Pacific look keeps changing in that Dec 8-13 time range. Most of the storm threats are going to be from the pacific as shortwave eject out and underneath the block....and there's the added complexity of the central/southeastern ridge in the process of retrograding westward which also mucks up the ability for guidance to show a lot of continuity in handling shortwave traversing the flow. So basically we get: Atlantic ---> Stable on guidance Pacific ---> Volatile on guidance CONUS ---> Semi-volatile on guidance Not a good recipe for getting consistent storm threats showing up on model guidance.

PAC almost looking slightly El-Ninoish at the end. Subtle drop in heights SW of Aleutians and pumping of heights over AK and PNA ridge region.

This is prob not far from the truth. Not uncommon at all for models to be all over the place until much closer on individual storm threats. Esp in a high blocking pattern.