psuhoffman

It's hard to get h5 right and mess up the surface over and over. But...they score those things on a larger scale so if the UKMET has an issue with under and over amplifying discreet SWs it might not effect its overall score as much as it effects its ability to get details on a synoptic system correct.

I would think yea... guidance today has trended back towards a healthy wave coming across...that's what I wanted to see. Some of these runs are starting to align with my expectations for this setup. That GFS run might have been overkill but thats the kind of max potential we have if the upper low amplifies enough to our west.

It's hit or miss...sometimes its crazy amped. It had a few runs where it gave DC a blizzard before that costal scraper storm in 2018. And other times its way suppressed compared to other guidance...last winter it kept giving me 15" of snow from a storm that ended up way north long after all other guidance shifted.

Your really want to tempt fate with 120 hours left to go??? But isn't this a double edge sword...its partially the lack of cold press in front that allows the primary to amplify north and ends up with that bomb over southeast VA. The GGEM is colder but also a much less intense and "fun" storm...especially for us north of the DC area. I guess this is location specific...if I lived south of DC I probably don't want to chance "playing with that fire" and would take the less intense but more sure thing snow. Again..120 hours to go...we want to tempt the snow gods on this?

It would really really really suck...so this is not minimizing it...but sometimes I do think we overplay ice a wee bit...considering we survived like 2" of it in 1994 and yea it sucked but we made it. We are all here to tell the tale.

@leesburg 04 @H2O He is already at DCA for Thursday!!!

You know...its really frustrating when the long range tracking never pays off like lately...and then it makes the mid and short range tracking stressful because were so desperate to get snow that when things go wrong its gut wrenching. In a way the long range pattern tracking is less stressful. There is less pain run to run if a little detail goes one way or the other. Even this pattern...its gone EXACTLY the way I thought from weeks ago...but now some really subtle discreet details that you can't possibly see or worry about from 2 weeks away will determine if the foot of snow ends up being in PA or DC or Richmond. And now those details start to matter a lot and drive us crazy every run.

I suppose if I must... I can live with this solution

@stormtracker nevermind you can suffer a few hours of rain if it means we all get that ending HOLY P(*U#RPWIJASPOFJISA

Again...I think we are very possibly in the very very narrow "sweet spot" for this one. But this illustrates my point...we needed a north adjustment...but if you payed attention to the whole setup we really didnt have a lot of wiggle room with the thermal boundary to begin with. So we get a north adjustment and suddenly rain becomes an issue again. No margin for error either way. Luckly I think we might be in the razor thin "win" zone for this one. But damnit it can't keep being this difficult or we are rarely ever going to win.

I am soooo sorry...it was my last "double bind" post I did this.

I agree but I was pointing out that even though we need a "north" trend...we really barely have a cold enough profile to begin with. That's indicative of a larger scale issue then just this specific event.

Winchester was such a nice place...shame...real shame.

yea I actually have something REALLY important to do that day...and I have no problem driving in snow. I have driven through actual blizzards out west where I could only see 10 feet in front of the car. I have absolutely no issue with snow. But ICE....no thank you.

The 0z NAM is painful up here...I get almost no snow but 20 miles north of me gets 10" lol. Probably too much to ask to get that to start to shift south when the overall bleed is the other way the last 72 hours.

The secondary yes...but its ALL about the primary to our west...we need that to hold on longer...and this ICON run kills the primary a little quicker further south then the 12z run. That is the key because the flow becomes more compressed the further east you get. Once the storm transfers I expect absolutely no northward component and the precip will actually likely start to sink southeast from there. We need the primary to hold on and create that "inverted" trough feature to train moisture along from as the secondary forms. That inverted trough banking up against the compressed flow to the northeast creates a really strong focus for lift. That is the mechanism to get the precip NW. If the primary dies too soon the secondary will wrap up like that ICON run did to our south. Ideally we want to get the primary to hold on into WV or southern Ohio. Yes I know that sounds like blasphemy to some who equate a west track to rain...but once the transfer happens there is likely to be no further northward component to the precip shield so we need the primary to hold until AFTER we get the inverted trough up through our area and the heavy precip is overhead. Then it can make the jump. If it jumps to our south...we get that icon solution.

Before I say this let me preface that I am still optimistic for this storm. I think we are in a pretty good spot. I think this will work out. But I wanted to highlight the double bind we are in right now and why we keep failing despite what has been one of the better longwave patterns we have had in many years all winter long. Look at this from the 18z EPS. Now...that was a pretty good run...but we still need a north adjustment. The target was still just a little south of DC on that run. There were some nice hits but too many misses still. So we need a little more ridging or relaxing of the suppressive flow over the northeast to get the storm to trend north some...but look at where the "cold" boundary is as the storm approaches there! How much can we even afford to "give"? And yes the temps crash after once the storm secondary's and bombs to our southeast...but because of the suppressive flow to our north we need to get the primary up into southern Ohio or WV before it transfers to get heavy snow here. But what if that ridging does shift north say 50/100 miles? How much further before that primary maybe holds on into western PA and the transfer ends up to off NJ instead of off VA Beach and we get a miller b jump over us solution? And about 9 members of the 18z GEFS had just that. We're walking a razor edge on EVERY possible snow solution right now because of "THIS" double bind. Right there...on that run...we have barely enough suppression to prevent warmth from surging north of us ahead of the wave...but its slightly too much suppression for a storm to amplify enough to "crush" us. We have absolutely no margin of error because the cold is so freaking pathetic that to resist warmth from surging north of us ahead of any wave we need such a suppressive flow that it prevents any storms from amplifying. If the suppression relaxes we can get a storm but its rain. I debated not posting this... but I think we can keep this from becoming an out of control debate about "you know what". I am not going to even say its all "THAT". There are some factors that maybe aren't permanent. The PV got sent to the other side of the globe, the pac torched north america all fall and early winter and so perhaps the base state is even warmer now then just due to AGW. But regardless of all that...this is the bind we are in right now trying to get snow regardless of the pattern. The same exact equation is playing out Monday also. That storm is suppressed so much it becomes a strung out mess that barely gets heavy precip to the mason dixon line...and NYC is on the northern fringes. Yet DC can't get any snow??? If the storm was suppressed much more there would be no heavy precip anyways...this keeps playing out time and again all winter long.

Me too. Thing is...it is getting suppressed. NYC is on the northeast fringe! The real heavy precip stays south of PA. But even with the suppression the cold is too pathetic to hold. Here is the scary double bind that puts us in. If the thermal base state is so warm that to get cold we need more suppression then this...well look at Thursday. It’s not even that cold. It’s barely cold enough to snow really. And it’s taking such a suppressive flow to get even that, that there is a serious risk the storm gets squashed. So what’s our path to a win if the cold is so weak that to prevent warmth from surging north in front of any wave we need such a suppressive flow that nothing can amplify?

it’s a little too soon to make definitive projections when it ends at 90. EPS goes to 144 but not out yet. the energy that will become the storm along the UT AZ border is closed and more consolidated that’s good Imo. The wave in the Ohio valley is a little more progressive creating more space. Slightly more ridging ahead. That’s good. I have no idea what to make of the TPV being further south in Canada. If the euro still rotates it north like previous runs it’s irrelevant. If it gets in behind it could help. If it comes across on top it would hurt. Overall I would take the 18z over the 12z look but it’s hard to say that early. Anyone else wanna chime in?

Another tick north on 18z euro. 12z seemed to have stopped the bleeding but 18z feels like it started again. Not sure how much more we have to give at this point.

This probability map also shows it. You had about a 45% chance of getting 3”+ at 12z and you still do at 18z. The difference was at 12z the 55% choice you didn’t was almost exclusively from a miss south. Now your equally likely for it to miss north. 18z 12z there is more spread now due to a cluster of north track members.

Not for the reason you think. Gefs shifted north quite a bit. This captures most of the event. Look where the max is centered now. Mean qpf did drop slightly in central VA but because there is slightly more spread where members place the max precip. And the nature of this setup with the extreme compressed flow to the NE but with the upper low causing the system coming west to east pretty far north means it’s a fairly narrow zone of high impact. Not like a typical climbing the coast event. But the spread increased to the north. There are now several members that get good snow north of Philly when almost none did before. And the snow mean decreased in VA for the opposite reason as the euro. RAIN lol. Its hard with timing differences to catch them all in one panel but there are a cluster of members that are so amped it in most or all of VA. There are even a couple members that give me rain. And some that come across so far north it miller b’s us and we’re pretty dry. I count 11 flush hit members for the DC area. I count 9 members that are either south or weak but I count 10 members where snow is limited because it’s too far north and rains or simply jumps over us because the upper low comes across too north to hook up with the southern wave until too late for us. So the threat of a miss to the north is now the greater probability on the gefs. So it may have decreased snow totals in VA but not for the same reason as the eps. It trended a little too amped in some members!

The euro isn’t flawless. You realize we’re still at the range when it was giving DC 20” of snow back in December. One of the storms in 2018 it was giving me 8” of snow literally 12 hours from the storm and I got NOTHING lol. What’s odd is they are both opposite their biases right now. But this isn’t a typical gulf wave to coastal setup. The upper low is coming across pretty far north and it’s interacting with the NS flow some on the way across and that’s the driver here not the southern stream wave it links up with in the southeast. I wonder if that has to do with why they are opposite their tendencies. I also wonder if the NS interaction matters more here and if that might not favor the gfs some.

Better imo

I was just thinking about that comparison earlier today.