psuhoffman

ICON was slightly more amplified...and exact same track until it got to the outer banks...and it looked about to be a better run....but then 18z the low took a more N jog from there and this run it went northeast and out despite the fact it was several MB more amplified.

ICON looks slightly more amplified then 18z through 46 hours fwiw.

I would think more amplified in this setup but the NAM's did trend less at 0z no denying that and the RGEM was pretty flat. Just a lot less amplified with the wave. The flow can be conducive but if the wave is a weak strung out POS it wont matter.

That is a danger...but its also a path to a big hit. The northern stream isn't progressing east its pinwheeling in the upper great lakes. So it does get out "ahead" briefly this run which is why the wave starts out more suppressed initially. But because the NS isn't progressing east the SS wave will eventually get out in front of the flow and once that happens it turns north and should gain latitude fairly easily. There is NOTHING in the flow to stop it. The only issue would be if the wave gets squashed so much it can't recover but I don't necessarily see that here yet. But that NS preventing this from amplifying and gaining latitude UNTIL it is over the southeast saves us because this would cut to the north pole otherwise in this flow. We need it to be shunted into the southeast before amplifying and gaining latitude...and yes its a thread the needle because if it gets shunted too far then it can't recover but we have to dance with that devil here if we want to have a shot at a frozen and not wet solution.

Look at the SLP track on the 3k...even starting out as far southeast it comes NNE up the coast...from off SC to just east of the VA capes. It's good that this doesn't start to amplify until its over the southeast because we would be in trouble otherwise...but I really think this is coming up not escaping east.

yea despite the late start and weaker SW its still trying to climb the coast. But just looking at the whole way the jet and the NS is oriented gives me the vibe this would really amp up and go nuts up the coast if that SS SW ends up slightly more amplified. There is a LOT of room for this to amplify up the coast looking at the flow. The thing that could save us from too north of a trend is that it starts out pretty far SE before it begins to gain latitude. I know it trended SE but this run didn't give me a "its getting suppressed" vibe. If anything it furthered my opinion this is likely to amp up more as we get closer.

interestingly...the issue was a weaker southern vort this run...but there were some improvements in other ways...the northern stream is actually oriented more favorably imo and could even really amp this up had there not been such a weaker SW this run. In the end the weaker SW offset the improvements in other places...but if that SW were to trend more amplified again this could really go nuts given the trend for the NS to dig and go negative sooner and further west.

yea but the SS vort looks weaker and that is the one that does most of the work for us so I dunno.

I was looking at the MSLP and it was a significant trend more amplified and slightly closer to the coast with the track. The precip was also more expansive to the west. But there was a reduction in the max precip stripe to the SE of 95...and there was a significant decrease is snow to the SE of 95. Not sure why the decrease is precip given the more amplified mean on the MSLP. Probably divergent camps. If one camp trended more west it could explain why the reduction east of 95...there may be a camp that drops more significant precip to their west and dryslots that area. There may have been a few members skewing the qpf way high there that are not this run. Hard to say but those kinds of details are unreliable on the SREF. The track was a little west and the mean slp was deeper and the precip extended further west. Those were the main takeaways I got from it. And that was probably too much to take from the SREF lol

SREF have a crazy wet bias (or at least they did back when I paid more attention) within some members so you cant use their output as is...but they do tend to show trends. They were with the NAM in predicting the shift north early on back in December and started showing the deform shifting towards eastern PA and north NJ before the globals last week.

WAY more amplified this run. BTW we know the SREF has crazy biases but it is somewhat useful with trends just as a curiosity in between model runs. It does tend to trend with the other guidance in general. @high risk @MillvilleWx do you happen to know if anyone still even looks at the SREF? And also...the idea of a short range meso scale ensemble is a great idea imo. The meso models are needed to pick out features the globals cannot but they are very susceptible to being jumpy which is probably unavoidable when you make them sensitive enough to pick up on meso features. An ensemble to help eliminate that issue is a great idea...but it seemed the SREF just suffered from having members with crazy biases that skewed them. Why wasnt there, or is there, an effort to develop a more useful short range ensemble system? Thanks for any info.

I didn’t jackpot either of the storms this year. I got 10 and 12” and Both times some places north of me got ~40!

Not sure we want more of a jump in one run this early... She did him a favor actually.

Also reminds me of boundary waves in April 2018, Feb 2017 and early Feb 2014. They all trended north the final 48-72 hours. There are examples of ones that didn’t but unfortunately when they don’t it’s usually because the wave got squashed somehow and we don’t remember those. We got some of these waves to work in 2014 and 2015 but if I recall the move north didn’t start until 48 hours. I remember from 72 they all looked south. It’s not 100%. Sometimes something happens the guidance didn’t see to suppress but the trend historically with these kinds of boundary waves is north the last 72 hours. Even up here often it goes from south of me to north of me the final 72 hours. One red flag is that the temps aren’t really that cold. The flow isn’t suppressive either. If this continues to amp there isn’t much to prevent further north adjustment. Even up here I might be more worried about north then south. Before people jump it’s not set. I’m mostly going off historical model bias but it’s like 80% not 100%. If it does go north at least I REALLY like the look next week for the whole area. It’s a look we usually score in.

It not only trended more amped but colder too! So long as it doesn’t shift north more amped is good in a marginal temp setup. Of course it’s a tightrope because more amped can pump ridging in front and shift the boundary north. However, there is a window of opportunity here for both more amped but not north which the NAM just highlighted. That’s to get the wave to start to amp far enough east that it can’t pump too much ridging in front. It’s a thread the needle timing wise but it’s possible.

Come on I need about 8” more base to be able to ski the goat trail down the 350 feet of vertical behind my house.

My thought on the Nam through 54

EPS can’t decide which wave to key on but the 5 day period day 7-12 looks very promising.

This...the Arctic cold scenario greatly reduces our chances of a big snowstorm.

For the record I NEVER said suppression was a problem for these boundary waves coming up lol. The flow to our north is not suppressive at all.

@WxUSAF that Feb 2 thing didn’t get much attention because it wasn’t even on the radar until like 36 hours out. It was a weak wave buried between the two big storms that guidance didn’t see. Then even when it popped up it was a 3-6” snow 2 days before 2-3 feet was showing on guidance so it was an afterthought to everyone. No tracking and by the time it was snowing we were already under a watch for a HECS.

Not really. Yes in terms of the boundary but there is nothing to stop that from shifting and the typical bias on these progressive frontal waves the final 72 hours is more amplified and north. Even the euro. Think of those waves in Feb 2017 and 2018 that looked good for us at 48-100 hours and ended up a big snow for central PA.

Sometimes it’s just bad luck. 2018 was the reverse. Your area did a lot better wrt climo then DC or even my area. You got clipped by the coastals in early January and March that totally missed further west and you still did ok with the late March storm that did get DC. Sometimes there are screw zones in a given year and it’s more due to random chaos then anything else.

Didn’t DC just get it’s biggest snowstorm in over 2 years and 2nd biggest in 6 years?! But I will, and have, admitted the “we” I speak of is more DC/Balt metro and points west centric. I guess I do kind of ignore the eastern shore and lower MD and VA northern neck south. There are 2 reasons. 1. There are only a few posters here from there. 95% of the people here are DC/Balt or places west/north since there are more population centers west of the 95 metros then southeast. 2. The combination of low elevation, further south, and proximity to the ocean makes the snow climo there REALLY difficult. Frankly those areas need a different look and yes you probably do want arctic air because big snow is even more an anomaly so while a big Arctic airmass might still not work out it does increase the chances of an southern slider Arctic boundary wave that gains just enough latitude to clip those areas. The kinds of coastals that crush DC northwest are not really good for those areas. To get heavy precip DC to Hagerstown we need a low tucked into the Delmarva and that’s a rain track for you. You want a southern slider that clips you and me to be smoking cirrus. Look at the gfs ensembles. There are very few where we both get good snow. The members that give you a flush hit are pretty pathetic DC NW. the members that give DC area to me 10”+ are rain for you. it’s not impossible to get a storm that crushes both but it’s rare and walking a tightrope. You do want a colder antecedent airmass because to get an all snow hit you either need a progressive wave suppressed south of most of this forum or if it’s an amplified system the rare setup where there is so much cold that you get crushed during WAA before the warm layer can get in. But those are 1-2 times a decade type storms.

If the PV dumps west initially it could. But models are going to struggle with this pattern. A lot of extreme gradients and potential energy for them to resolve.