ORH_wxman

End of EPS run going into the final week before Xmas....that is a really nice look. Hopefully we can pull off multiple threats.

A lot of members with a low nearby on that threat. Timing differs as well...a lot of members have something 12/12 but some are more like 12/13 or even 12/14.

Nice little nuke on the Euro for Dec 11....hugs a little too close for snow except interior CNE/NNE, but that type of detail is pretty irrelevant this far out. Gonna have to be patient for solutions to stabilize for Dec 9th. Prob at least another 2-3 days. And for any threats beyond that, it will take longer to get consistent solutions.

Yes that is def a possibility....Euro almost shows that to some extent....we end up rotting north of the boundary and there's ocean effect (prob synoptically enhanced) on east flow for like 36-48 hours....prob just showers on coast but maybe cold enough for snow just inland. Marginal saturation above 850 but that type of detail isn't worth looking at yet. That's just a literal train wreck in the Atlantic backing up the flow. Euro looks like it's cooking up a bigger event though for Dec 11.

Nobody should get too invested in that threat....there's a chance there, but it needs a lot of things to go right. If it shows something interesting inside of 120 hours for multiple runs, then maybe it can be taken more seriously.

That's prob gonna be a squash job on the Euro for Dec 9.

Ugh....that's really annoying. Can't wait for the forecasters to say "we're adjusting for lower frozen over the interior of New England because the super ensemble blend has temps largely above freezing by midday".....and completely ignore there's a 1035 or 1040 high N of Caribou and all those models feeding into their ensemble mean that erode the lower level cold are actually just dead wrong and most local forecasters hedge for them being wrong in those types of setups.

GGEM actually tries to retro the Dec 7-8 storm back into us

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