psuhoffman

Another detail that went wrong that globals won’t be able to pin down at range was the exact trajectory of the SE flow and associated waa precip. It ended up aimed more to our SW until after we lose the mid levels. More e to w v s to n. That’s a worse angle to maximize the WAA before we lose the mid levels.

@Bob Chilland @MillvilleWxdId a great job explaining but I get why many casual observers are confused. This isn’t a typical setup. The physics make sense but to those that just observe and base expectations on typical synoptic progressions this is odd. This was actually a really good longwave setup but a lot of details had to go wrong to get this outcome. First we’re on the backside of a trough in a NW flow and there is confluence over the top right now. That’s why the SW is diving SSE down the Miss valley and digging to to gulf coast. To get that there has to be a NW flow. And so normally there is no way that leads to rain. And I can understand the superficial confusion. But then everything goes wrong in a very rare combination. The upper low is way too amplified and cuts off way too early. That alone would be odd but we could survive that except that for the another very energetic NS SW digs in and phases at exactly the wrong time which manages to turn the whole trough on its axis in a very tight window. We go from being on the backside in a suppressive flow today to a neg tilt trough to our west in 24 hours. That’s special in a bad luck way. That NS SW had to be exactly where it was on the exact trajectory and amplitude to pull that. Faster and it would have been pulled east over the top by the current suppression and would have helped resist the SE flow ahead of the anomalous closed low. Slower and it doesn’t pull off the phase in time and the upper low gets further East before it turns north. But no it was exactly where and how it needed to be to screw up an otherwise good longwave setup. Oh well. Look at the mslp plots without the L. There is no defined closed surface circulation. There is no classic surface low. This is all mid and upper level driven. There is a strung out negatively tilted trough of low pressure along the convection associated with the SE flow ahead of the mid and upper low. Where the L shows each panel is just a function of where the lowest pressure by 1mb happens the be along that trough at any given moment likely convection induced. It’s irrelevant whether it’s over Hagerstown or DC or the bay at any given moment. That feature isn’t driving the bus here anyways.

We’re just having fun. Regardless of the NAM this has changed quite a bit. Look at where the axis of heaviest snow was on the Gfs 24 hours ago and now.

Just have to lol. This is where the actual snowstorm ended up.

That’s how you have to roll. Take no prisoners.

Scranton…it rains to northern VT on this run.

@stormtracker fire up the bus we need to go to Binghamton for their 3 tenths of on inch!!!

Gonna be congrats Alaska in a few more runs

Buffalo changes over

Naw busy packing and this isn’t looking promising. Nothings changed synoptically but the models are seeing that screaming SE flow and obliterating any cold pretty fast.

My 2” call for Binghamton might have been too high. I don’t think they get any snow on the 0z NAM. It pretty much starts as sleet and freezing rain even up there.

I'll see if I can find them on my way to snowshoe

no zoom tonight, I have too much to do to get ready for the weekend. Hopefully by next week we will have something more promising to track.

We should drive 5 hours so we can get 2” of snow and ice changing to rain?

Except its not just the NAM. Check out the RGEM. Changes to sleet and freezing rain all the way to Erie!

I know the storm you're talking about and it was a different setup. Models missed a higher mid level warm layer around 700 mb. I am only bringing this up because I am very familiar with central PA climo from my years at PSU. For them a perfect setup is a cut off amplified H5 moving through around DC with a surface low tracking up inland but east of the blue ridge. In winter with a cold airmass in place that should be a setup for a big snowstorm in places like Deep Creek, Altoona, State college, not a change to ice and dry slot! It doesn't matter for us...just saying its kinda ridiculous to have a H5 and surface track near DC and a flip to non snow all the way to extreme northwestern PA. Put that in perspective...thats the equivalent of a H5 tracking across southern NC and Cape Hatteras and a surface low tracking off the NC coast and 100 miles east of Ocean City and us flipping over!

It did...but that storm the low tracked up into the delmarva and the warm layer blasted some sleet and a dry slot into south central PA to places like Harrisburg. That was significantly further NW than thinking...but I've seen that before, especially with a bad upper level track in that case. But here the upper and mid level track is through VA just south of DC. The surface track is up just west of the bay. And the NAM is mixing with sleet and freezing rain all the way to Lake Erie. That seems a bit off. Ive never seen THAT!

I have no doubts the warm layer will blast through this area with no trouble...but I have to think the NAM is way overdone overall. It's really indicating not much snow anywhere...flipping everyone to ice even to the NW edges of the storm. I have never seen that before when a cold airmass in place in January and a surface track east of the blue ridge. To change over all the way into western PA?

It didnt make much difference for us yet, but this was the first run of the NAM where it went the other way and had a less aggressive push of the warm layer. Also a slightly better h5 and surface initially. Baby step...we would need a couple more adjustments like this to see much benefit though.

NAM coming in less amplified, slightly south, with less riding and lower heights over the top through 42. Let's see if it matters at all.

The euro is trying for another NS phase job with a gulf system next weekend. Might not pull it off this run but interesting and somewhat similar to this. We were discussing this in the last few zoom chats... JB is right about one thing...this is the kind of pattern where you can get the NS to dig far enough south to get these amplified systems coming up out of the gulf coast. But they aren't going to be 1993...even for a triple phased system that was a once in a lifetime thing. We've had several other triple phased storms but they usually phase and bomb further north like the November 51 and January 66 storms. So he isn't wrong that this is the kind of pattern to get the NS to dig down and phase and get amplified storms but he goes full over the top hype mode as usual. Also its not necessarily what we want as were seeing now these types of storms can cut if we dont have enough confluence to our north. The key is to either have something blocking the flow, a well timed 50/50 or wave coming over the top in front of it... and it would also help not to have another NS wave diving in and phasing right behind it!

The euro had another decent upper level low track and improved the surface a bit. SLP tracks from ORF right up the bay then into eastern PA. If we were to continue to get these minor adjustments and the upper low were to track another 30-50 miles southeast and the surface low were to track up just east of the bay, it would cut down on the low level warmth quite a bit...might increase the WAA thump some although I think the angle the WAA precipitation is coming in at has more to do with that then anything else at this point...but it would increase our chances of some snowfall Monday morning with the upper low pass also. On the WAA snowfall...We want the trajectory to be more south to north and less east to west with the angle of that WAA precipitation. The more negative tilt that banding is the longer it will take to progress northeast and we will lose the column faster. A further east track of the mid level and surface features could help with that some also. There was a minor improvement in that regard this run over the previous one.

At long range the key is to identify the opportunities for amplification near the east coast according to the longwave pattern. The guidance will struggle with the details like phasing, which SW to amplify, track. I don't bother with the surface maps at all past 5 days.