psuhoffman

All guidance is having a hard time with all the discreet NS waves. But the euro and gfs are now both keying on that more significant SW diving into the central US and amplifying. The euro developed a monster coastal in back to back runs from that only oddly using 2 different progressions. One by phasing it with the southern SW. Last nights run the spacing was too great and so it washed the southern wave out then developed a whole new surface system behind it. The details are going to keep changing because there are too many SWs to resolve details at this range but I think the key lies with that energy diving down into the plains. We want that to stay stronger. If that is as healthy as guidance suggests the chances something works out are better.

It’s getting kinda ridiculous. Maybe they programmed the DC snow hole into the algorithms.

Much better. It phased but then it left a piece behind which stretched out the trough positively tilted and prevented the system from amplifying. The kicker diving into ND didn’t help either. The pattern has huge upside but all these NS SWs flying around are making it difficult.

I assume you mean p17.

You are 100% correct about what our best scenario was 3 days ago when that NS vort was diving down over Lake Erie. If that had trended west and come in through Michigan we were golden. But that ship sailed and at this point, while its very very very slim, it’s trended so far the other way that perhaps there is a slight crack open for this to come north some. That NS SW trended so far east it has allowed the upper low to trend back north. It’s actually taking a perfect track for us again after it looked to be squashed down into the Carolinas the last couple days. But there are 2 problems. Without the NS phase there isn’t much cold and so a very limited precip shield to the north of the low. That ship has sailed so moving on. But the other issue is the NS SW up near Maine now instead of NY starts to absorb the system and it’s opening up and washing out by the time it gets here. This is very unlikely at this range but not impossible that if the spacing can increase just a bit more that the h5 low could hold on an extra 12 hours or so and that could pull the storm up the coast and additional 50 miles or so but also increase the moisture flow off the Atlantic for a while. Get “this” adjustment to the look and suddenly a surprise is possible. Again not likely but not crazy impossible. If the adjustments to the NS continue at the same rate it would probably would happen but those adjustments become less likely as leads shorten so at some point I suspect they stop and we do see further north nudges but not to the degree we need.

The end of week 3 after a SSW is when the cold really starts to correlate but some have suggested that timeline can speed up some when the TPV was already weak. So seeing the cold appear towards day 15 on guidance isn’t out of line with normal progression.

There is split flow out west actually but the blocking forces the NS to rip across the northern CONUS and there are 8,000 vorts flying across acting as a shred factory for anything that tries to come from the south.

It was a little odd how it didn’t phase the initial wave and instead had it wash out in favor of the wave behind. But the h5 evolution of that second wave was just classic. It was a nice ending to a very good night. Cheers.

It washed the initial wave out because of the monster wave amplifying right behind it. The evolution at h5 of that system was very similar to Jan 1996. Beautiful monster closed h5 low with a perfect track. That solution didn’t even maximize potential. The storm got a late start because of the initial wave running the baroclinic zone and deep moisture feed off the coast ahead of it but the upper level pattern was so perfect another storm exploded behind it anyways as the upper low got close enough to tap whatever gulf and Atlantic moisture left.

So far the Mjo hasn’t been a major influencer this year. Could it become more dominant and could it shift back to the MC....lots of could there and that’s a long way out. I won’t pretend to know.

The block is 12 hours old and already there is a chorus line ready to declare bust.

say it again for the people in the back ... @Ji

I stayed at a holiday inn express once

Question, if you like digital snow more then real how come you complain so much when guidance takes it away at the last minute. Seems it served its purpose already at that point.

A general pattern observation...most guidance has a similar pattern evolution the next 2 weeks. This initial block is centered south of Greenland into northern Quebec. That’s a bit “extra”. It weakens around day 5 then reorganizes in the next heat flux more towards central Greenland to Baffin. That’s a more ideal location. The window would be during the relax then again after that block reforms further north.

Fwiw Icon at 120 looks like the euro and is amplifying the trough in the Miss Valley

My gut does feel like in the end if this phases rain is a bigger risk then suppressed. The blocking is relaxed there and not nearly as much confluence. Luckily the ridge/trough axis looks really good though and the antecedent airmass is decent. Still not good for January but not the rotting dumpster fire it’s been.

so long as we're still chasing ghosts at 180 hours away who cares...but once things start to get "real" and we have a real storm thread that's when we need him to behave

You're looking at the wrong thing for "support" at that range. This looks VERY supportive.

Giddy up

There is much less of a suppressive flow in the way of that wave. But it’s also more complicated then the fairly simple bowling bowl system this week. Need multiple parts to phase. If they do it will come north though. It’s always something lol.

I’ve kinda felt it was forked when all the guidance shifted the H5 track from across VA to across NC a while ago. The N trend we often observe the final 72 hours is not typically from a huge shift in the major synoptic features like the h5 track. It’s mostly due to the fact that globals tend to underestimate the north extent of mid level warm air intrusion and thus they also underestimate the NW expanse of moisture transport and WAA lift in the commahead. They tend to expand that significantly in the end and that mid level warm intrusion also shifts the mix area north. But this isn’t the right setup for that without any deep cold around. There is “some” typical last minute latitude gain of the surface low but it’s not usually that significant. Based on these observed model biases our sweet spot at 72-144 hours out is to have the heavy snow centered just south of us. Like central VA and lighter snows up into our area. Something where a 50 mile shift matters. Once we start seeing the action shift into NC inside 144 hours it’s usually over recently. That’s felt like the way these play out the last decade or so.

I do think suppression is a legit risk until we see the blocking relax some. It’s a beast and centered pretty far south. That panel at the end of the GFS with a closed Rex block centered over Baffin is more where we want a strong block configured and located. That big elongated w-e block centered all the way down into Quebec could set up a shred factory flow over the US for a while. It won’t last forever though and as it relaxes we have a window and if it does reform further north we could have an extended window later.

GFS op recycles the blocking...this second iteration is actually more ideally located and configured. It’s fantasy land but I do agree with the idea the blocking likely recycles several times before breaking down.

There is always that risk in a blocking regime but you have to remember we are too far south for most patterns to work. Absent blocking to suppress the flow we are usually south of the storm track. But take Friday for example. The issue is the blocking is a bit too strong and centered too far south. The ensuing trough in the east gets centered south of ideal. You can see on the means this week the west to east “blue” is a bit south of that “big snow” plot I posted. But if the track was further north we would be just fine. The few runs that did show snow for us were mostly west to east systems too...just they came west to east just under us instead of way down in the Deep South. But it’s unlikely the blocking stays at the current really ridiculous levels. It will wax and wane and during those relaxations we could get a system to gain a bit more latitude or come west to east at a higher latitude. Take that storm that fringed us on the long range GFS last night. That gained no latitude at all. It moved straight west to east but if it comes across 50 miles more north we get a HECS. PD2 was like that. It moved straight w-e until it hit the coast then gained some latitude but not much. PD1 1979 also. We also could get a storm that gains some latitude with a temporary relax that won’t show on a 7 day mean. The slight one day ridging ahead of the storm is washed out on means by the N flow behind the storm. We don’t need a lot of latitude gain. Our ideal track is a primary to TN then jump to NC coast and a latitude gain to about Ocean City. From there ideally we want it to move east. That said the building positively tilted western PNA EPO ridge later in the period does add more threat of suppression. January 1977 featured that look and it was arctic cold but bone dry. That’s going to flood cold into the CONUS and suppress the baroclinic zone way south. So yea that’s a threat. But now I’m honestly getting frustrated and here is why. A week ago when the blocking showed but there was still a N PAC trough and not a lot of PNA and no EPO all the debs were saying “but it’s not cold enough in that look we would need a perfect track”. And now that the EPO/PNA ridge goes up it’s “but that could be suppressive”. Ok well what do you freaking want? Those two things are mutually exclusive. You have to dance with one of those devils. Our HECS look actually has less PNA EPO for the very reason you just said. But it’s not a cold pattern and sometimes it’s not cold enough and we get a perfect track cold rain. The epo ridge -NAO is a cold pattern but dryer and sometimes we don’t get any big juiced up coastals. No pattern is 100% fool proof guaranteed to snow.