Roger Smith

This run is probably the start of a gradual evolution of guidance towards a blockbuster event of historic proportions. More cold air involved, better track. Have a close look at the speed of the occlusion around hours 108-114.

It digs a bit harder and is mostly coastal energy now, inland center much reduced, 500 mb low somewhat further southeast. If this is a start to a trend then it could look really good eventually.

GFS to 60h trending in a good direction, stronger high, low a touch further south, prior storm a few hours slower. Bet it's going to go back to the coast now.

CMC is the worst outcome I've seen in this time frame, while somewhat similar to GFS, there is almost no definition to the coastal and most of the energy is shown with the inland primary. It would snow a bit and then thaw. However, it is the CMC so not to worry.

Two different ways to a roughly similar outcome now, why mess with that? The ICON has a high energy coastal and the GFS has a low energy associated low with a weak inland primary tracking KY to upstate NY. The low energy keeps the Atlantic from rushing into the circulation. I suppose the best case scenario is a high energy coastal that ripples back a bit to the east of the current ICON track. But given this is the third significant snowfall in two weeks of early to mid January, this seems quite acceptable if not downright astonishing.

Here's one possible source of info https://wetterzentrale.de/reanalysis.php?map=2&model=noaa&var=1&jaar=1996&maand=1&dag=8&h=0&nmaps=24

It's a weather thread, a travelogue and a place to get spiritual counselling. I hope the GFS sees the error of its ways and repents.

I blew up my screen mag to the max and the ICON track is about 50s.e. RIC to 50e BAL to TTN to EWR. The pressure is falling steadily into the 980s by about PHL. It does not look perfect for everyone but something to hope for in terms of GFS/GEM backtracks later on, we hope. One of the moving parts that evokes less than perfect trust here is the arctic high, it is a puny thing at present, just 1020 mb over Thomson MB, and while -38F sounds frigid, that is not exceptionally cold for the location near center of high pressure at 0700h local time. Which makes me wonder if the thing can ever reach 1036 mbs let alone low 1040s. I suppose if it was really weak it might have to push down behind the vortmax instead so there is that.

12z ICON has the thermal gradient intruding for a few hours into e MD but holds the cold air in place for areas nw of DC, not ideal but similar to the last run of the ECM now. The 500 mb low tracks almost overhead and towards NYC. Would say it's 8-16" for some parts of noVA and w MD, 4-8" for DC and BAL with full transition to rain followed by wrap around flurries. Anyway there is a lot of time left, the first storm hasn't even materialized yet, let alone this one.

meteociel.fr tres rapide

12z ICON is about six hours slower than previous run and has moved slightly towards the ECM but it still looks okay for a good part of the region (at 114h). Track is now something like New Bern to SBY to TTN to NYC

Let the sorcery begin, a thousand weather wizards all chanting Quebec high coastal track max the cold confine the warmth. All hail King Euro and Prince Icon. And Baron Ukie. A plague be upon you, GEM and GFS. The wizards of wPA have a much different chant. Off with their heads.

The cold looks less extreme on more recent model runs than when I posted, so maybe the values shown will be too cold now. Reality could be closer to -2 in the east and -5 for Chicago if the cold is just mundane. We have to get the eastern locations below normal first, then see how sustained the cold trend really proves to be. Your numbers look pretty good in general, especially in terms of relative scoring. (that is by the way against the law in 37 of the 50 states and most provinces of Canada)

Arnt you suppose to call for 22-28? Might be better if I call for heavy rain.

UK OK ... coastal and good snow potential. Over to EURO but anything could happen here, we're dealing with some rather weak building blocks that all have to balance perfectly for any solution, including the bad ones.

The GGEM looks a bit better than the GFS but not much and doesn't quite catch fire. Not sure if your discussion about ICON has seen the 00z run early or still waiting to see it? I saw it on meteociel and it looks good. Track is coastal. Problem with ICON is that it tends to go to various extremes and unless the outcome is extreme that makes it unlikely to verify. But you can always hope. Bit of a blind man's bluff at this point, working with some very weak signals that have ways of producing a good storm. Would not toss at this early stage.

Get greedy. Retrograde the whole pattern and get the ocean storm too. There's no limit to optimism, pessimism has the lower bound of zero unless maybe one could visualize negative snow.

They call the 18z GFS the pub run in the UK. Apparently this one is a tavern run.

Have just edited in some second place temperature finishes for Dec 2021, weeks of 10th-16th to 12th-18th. While 2021 was unable to match 2015 for those weeks, it did move into second place for all three on mean maximum and mean daily, just the middle one of the three for mean minimum. The values can be seen in the December post back in the thread, but are basically around average highs of 58F and mean daily 50F, but in the vicinity of six degrees short of the 2015 record values, about 1-2 F above the previous second place values from years such as 1984 and 2006 (for those weekly intervals). Working on the record weekly snowfall amounts now. Will post those in about a week or so (maybe after the weekend storm does its thing).

That NAVGEM offering when applied to weighted model consensus means a 15 mile shift to the east and 0.5 mb deeper. Not a bad thing. Pros don't always go on weighted model consensus, they sometimes pick a favorite or a consensus of two that they think have the better handle. But when a lot of models are showing very similar outcomes, a weighted model consensus often outperforms any one model taken alone. A good rule for the weighting might be 30% GFS, 25% Euro, 15% UK, 15% GGEM, and when time scale permits, 15% NAM. Go with RGEM instead of GGEM whenever possible. Ignore ICON and JMA. NAVGEM differentials are probably not that significant but if you wanted to give it 5% then if it's 300 miles east, that vector is 15 miles east. If it's 10 mb deeper that's 0.5 mb.

I think any attempt to track inland will play out as a double-centered tucked storm, the 500 mb evolution does not support much inland movement of mild air, but of course the North Atlantic is remarkably warm just offshore too, whether that remains true after the earlier storm comes and goes through the Gulf of Maine remains to be seen. My numbers are based on this model consensus for rapid or explosive deepening verifying, if later model runs back off that idea then I would withdraw those numbers. Snowfall rates of 3-4" an hour are possible with that kind of explosive development. But I do anticipate a large gradient as I said, a lot of the NYC metro could see mixing so snowfalls might be around 9-15" for many, 15-24" across parts of n NJ and Yonkers-White Plains, 24-30" further north and west. It would come down for about 24h at 1-3" an hour in some places (if these early indications prove correct). Would say there is more potential for the eventual track to be east rather than west of what is now shown, a certain amount east is good in general for snow potential, especially with similar rapid development. Blizzard of Feb 1899 not that different an evolution from what I can see on historical maps, of course the depth of inland cold air greater and probably the Atlantic not as warm, but track is quite similar. That storm gave NYC 16" and DC 20" (in the city rather than at DCA location now). Some similarity to 93 storm but can't see this tracking into the Hudson valley or even New England as the 500 mb low tracks northeast rather than north-northeast or north. Anyway, exciting winter compared to how it was looking in December. Like the grips guy says on the golf commercial, feels good huh?

The larger scale picture does not fit the scenario of a strong push of mild air inland, my hunch is that in the explosive cyclogenesis phase which appears likely near the Delmarva, the eventual shape of this storm will be double-centered with a triple point near the Texas Tower moving northeast to Nantucket. It could allow a blizzard to develop in many areas and confine the mixing zone to eastern LI and perhaps right along the coast to JFK, and down the Jersey coast to ACY then into the Delmarva. Could be a very large snowfall gradient across the NYC metro as a result. Potential for 24-30 inch snowfalls with this, most likely location would be n NJ, lower Hudson valley, w CT into central MA. (and further south in parts of e PA, w MD, n VA).

With the explosive cyclogenesis factor, this would produce extreme snowfall rates over the region and the frontal boundaries might not be as far inland as feared because of the rapid development. Also would expect a correction on this westward trend as chinook signal is filtered out of the development (chinooks confuse models a bit as there is warmth that won't travel downstream). The genesis for this storm is the short wave moving inland over the Pac NW and then due to sneak through the upper level ridge out west to form a Rocky Mountain lee depression in se CO that generates low pressure in Texas. The key is the strength of the arctic high moving southeast to wedge between this storm and the previous one which would be up around Baffin Island by Sunday. As that crests ahead of the bombing east coast cyclone, cold air will be hard to push out, if the 985 mb low verifies but closer to a track up the coast and towards east half NYC metro, then sleet stays coastal - Delmarva and S+ axis is closer to I-95 although still somewhat further inland. Blizzard of 1899 followed a similar evolution and crossed n FL, came up the coast and bombed out near Delmarva. Depth of cold air not quite up to that standard and more similar to the Blizzard of 93 which also came across ne FL. Something big is in the works and the timing at full moon brings in a lot of strong analogues. This could easily top 30" somewhere in the subforum, most likely sw to nw of DC. Would say 8-12" DCA and 15-20" IAD, 10-15" BWI, mostly sleet to rain SBY, multi-phase crapfest RIC, 2" rain se VA. Thundersnow and thundersleet very likely.

How about Full Moon Freeze Fest Spectacular? I had a dream too.

You learn a lot here, I never knew there was a Buffalo in Maryland.