psuhoffman

GEFS snow mean...higher resolution map

Updated GEFS ccb trend. Last 5 runs now What’s that word???

There is a word for what it is doing....

I guess EZF is kinda my line for what is northern v Central VA. Somewhere around there is the divide for the CCB though. But south of there gets some pretty good WAA thump at the start.

CMC is very nice. from the ptype plots...very nice WAA thump then we get CCB'd pretty darn good even down into N VA. East of a IAD to Me line does mix with sleet for a time and east of 95 mixes with some rain but VERY nice front and back end.

The GFS is messing up the thermals and it’s causing the secondary to develop further north.

The GFS is massively different (warmer) with the whole thermal structure over the northeast and even the ohio valley starting at 48 hours and IMO its screwing up EVERYTHING after. The "error" IMO in the temps is driving the primary AND the coastal front further north. At 84 hours GFS has the 850 isotherm along the PA line and the NAM/RGEM/Euro has it down in central VA. Who do you trust with thermals here? That shifts EVERYTHING north. That said the GFS is still "getting there". Look at last 3 runs trend.

RGEM is even further south of the NAM but it is a little slower getting the secondary...but you can see it's going to jump to NC but it has not started to develop a closed circulation YET. But given the look at 84 the RGEM looks like it will go more the euro/nam route also. I was not looking at the last frame of the RGEM, hadn't updated DOH...now that I see it the RGEM is VERY similar to the NAM and Euro. Secondary is taking over near Greenville NC on the last frame and has begun to develop a closed circulation. That really is the key...the "worse" globals like the ICON and GFS that mostly miss us with the coastal ccb do so because they linger the primary longer and don't really begin the process of amplifying the secondary until it is off the VA capes. We need that process to start in NC.

The 12k NAM on the last frame the surface low in NC is already developing a closed circulation. The next step we would want to see is the 850 low start to jump and reorganize along with the secondary.

ICON makes the jump to the secondary off the delmarva. Yes the process "begins" down in NC but its really just in its infancy stage and the coastal front baroclinic zone starts to amplify...it doesn't really take over as the primary circulation until at our latitude. That is no good. We need the Euro solution of a clean transfer to the outer banks. That simple. ICON solution would still be a nice front end WAA snow though.

@H2O You brought up very legit points last night. Before things get crazy let me explain why suppression is my bigger concern in this situation. Partly its about hedging bets. Given the confluence to our north, the high, and the cold as the wave approaches...I see virtually no way we get totally blanked with a cutter scenario. At the least we would get a nice WAA thump snow to dry slot. Maybe that isn't the 1-2 feet some are acting like we NEED for this not to bust...but I have 2 kids that are literally asking EVERYDAY when is it going to snow and to them there is almost no difference between 4" and 12". Frankly...20" is probably TOO much for them lol. I will still take it...they can wait for it to melt some! So my first consideration is "how do we avoid the total fail" where my ground ends up bare or with some pathetic amount that precludes sledding, snow fort building and the such. And IMO that is suppressed. Rooting against suppressed may mute the chances of the 2 foot solution some...but the math in my head I separate the boom (12"+) and the bust (less then 4") scenarios. Rooting for a more squashed wave might increase the boom but it increases the bust with this. So I would take a 50/10 (boom% v bust%) type split over a 70/40 type split. Also...frankly just looking at the h5 flow over the top of us and to the NE, I think the degree to which this can go north is muted. The flow is relaxing yes but its still pretty compressed to our northeast as the system enters the midwest. The further south guidance just "feels" more realistic. I can be wrong. I've been wrong. Just my gut. Lastly...the biggest risk, as I told Ji like 3 days ago...is a split. A suppression with the WAA wave then a slow primary that meanders northwest of us causing a late secondary that misses us northeast. But that is still "suppression" imo because the WAA wave is our bread and butter less likely to fail option. The CCB of a developing secondary coastal is ALWAYS a risky proposition and better to be taken as bonus not relied on. All that said...obviously I am human and biased and the fact I live on the northern tip of our geographic region needs to be taken into consideration. But even for places like Baltimore and Frederick and Winchester...I think my thoughts are valid. If I lived south of DC I would probably have a totally different preference for how I want this to evolve.

Gefs trend with the ccb last 24 hours

Is this where the storm develops? that looks pretty good for us to me.

There are some subtle differences that would help. I only see a couple members that tuck into the Delmarva like the op. The rest are at the perfect position for us just off the Delmarva coast. That would help with the mixing and getting the ccb wrapper tighter and not blowing off the the NW like the op. the op was a northwest outlier among the ensemble members.

I like this...history says this works

Eps surface track both primary and coastal is identical. But the whole system is several mb more amplified and that does lead to a warmer profile. Stronger primary even if it’s not further north will hurt some.

At 72 the eps is SLIGHTLY south in MO with the surface low. But it’s minor. No major differences over 18z

Yea the h5 pass was great but sometimes the surface doesn’t line up perfectly. The primary held on a bit too long.

At 6 hours I don’t see any major changes on the EPS

What else is new

@MillvilleWx the h5 progression is beautiful. I have a feeling when the EPS comes out this op was a northern solution in the envelope.

We’re flirting with the coastal getting going too late that’s my only concern.

Transfer/capture happens slightly too far north to get huge totals DC south this run.

@MillvilleWx btw have you looked at what mid February looks like? We might have some fun times ahead.