First Synoptic Breakdown of 1/24-1/26
Alright, let's do this. Overall I will try to break down the H5 vort and height maps so all posters can understand what we are looking for on future runs. I will start from the most suppressed solutions before progressing onwards to our most amped solutions. Additionally, I will be adding my own insight into how I think the scenario might play out. Especially important parts will be bolded and I will conclude with my personal thoughts at the end. Oh and disclaimer this is all based on the 12z model suites.
Scenario 1: The missed 1st phase (GFS and ICON)
Starting off with our two bad apples in the bunch are the GFS and ICON as they both have the same progression with the initial southern stream energy (SW energy) missing the phase with a bit of northern stream (NS) vorticity. This vorticity then goes on to block the SW from gaining any latitude causing a moisture source with no way to amplify. Here is the 12z GFS progression which illustrates this failure.
This is a snapshot at hour 96. As we can see the southern vorticity is ejecting moisture east and seems to be in a decent position to eject easterward and give us our hard earned snowstorm… that is until the NS blocks it.
Now at hour 114 we can see that vorticity is better defined as it forms a ribbon that blocks the SW from even providing moisture transport across the country. In particular notice the angle of the vorticity as it aids in blocking the SW. Another way to see the disconnect in H5 height anomalies which shows how the SW is completely off on its own with no ability to enter the wider picture
A day later at hour 138 we can see the effect this has on our system as the SW remains firmly stuck in place. The ICON more or less follows a similar progression but with a hostile blocking of moisture which allows a light snow event area wide.
One note of the GFS is that it still manages a good snowstorm for the Carolinas due to the NS trough providing enough energy for surface cyclogenesis. If (god forbid) the GFS is right and the low remains cut off our hopes of a snowstorm are not totally over, just dependent fully on the NS digging enough…
Scenario 2: First phase complete… and then no NS interaction (Ai GFS Ai Euro)
I’m going to be honest this scenario seems weird to me. It consists of the AI models and frankly I think it might be caused by a lack of training data. However, it is still worth an analysis. We will use the AI Euro for this just because they are similar enough in progression and I generally trust the Euro more.
Firstly, we get the phase that the physics based GFS and ICON misses in the SW. The AI Euro clearly shows at hour 108 a nice phase of the SW and the 1st NS vorticity cluster that suppresses the whole show in situation 1.
After this initial phase I think we are pretty dead set to get a solid storm across the MA (though it might be too amplified as future scenarios will highlight). It is also with scenario two that we get to talk about the second big synoptic feature this storm will face; that being the second lobe off the NS.
The Euro AI at 126 shows this well as we have our phased SW energy and a solid NS chunk off to its north. Both AI models are unique where they have next to no interaction (constructive or destructive) between the SW and the NS past hour 120. Instead the storm simply slides east while obviously not cutting due to the bear of the NS bearing down on it.
Honestly, this is a complete win to me. While it isn’t our max situation we get if we phase the streams (see scenario 4) its a near guaranteed all snow storm that is still strong thanks to a potent ejected southern stream.
Scenario 3: Close to Greatness (Euro)
Euro has a rather unique solution that all revolves around our critical first phase out west.
As we can see the NS that dives into our SW is way more potent on the Euro than any other guidance. This causes some interesting downstream ramifications. Firstly, we get an extremely powerful southern stream ejecting eastward.
I mean look at all that vorticity it is throwing from Mexico to near the Ohio Valley. Just an absolute beast that looks like it will completely maul us… but it doesn’t (at least relatively). This is caused by that pesky NS dropping across Canada which acts to split our southern vorticity in two
As we can see there is a large amount of energy left in the SW, I frankly cannot imagine the storm we could’ve gotten if the NS got out of its way. Instead we a respectable snowstorm thanks to the moisture transport and enhanced help from that NS wave
But… could you imagine what would happen if we could phase the NS with our SW?
Scenario 4: Greatness (UKMET)
You know it, you love it, our 30 inch snowstorm solution resides in the UKMET. Starting out we get the initial phase that the GFS thinks doesn’t exist. Then our SW starts traveling east
This is where the UKMET differs from our past comparisons. It involves the NS constructively. Notice how it acts to sharpen the vorticity out East while not cutting it off from the southern transport of moisture.
As we can see the energy in the plains is being amplified by our NS dropping in which results in an upper wind map that looks like this
Talk about a Right Entrance Quadrant. We have moisture transport from the Pacific combined with the NS amplifying our disturbance into a textbook coastal snowstorm. Could not ask for anything better than this. Of course, it is also extremely precarious as if you tilt even one variable you'll end up with a completely different storm.
Scenario 5: Overamplified (CMC and improved CMC)
It starts out the same as our last 3; that being a successful boot of our SW eastward thanks to NS interaction.
However, unlike our past scenarios it goes all in on the NS phase and we end up with an absolute monster in the plains.
This is what I am personally worried about, not because it's likely, but because it would suck to have such an amazing setup and then ruin it through too much phasing.
Progress this forward a couple hours and we get a NS storm that is working with the entire moisture fetch of two oceans and one (contestably named) Gulf.
Needless to say we mix quite bad, though that is partially due to less confluence out east as well.
As of now I don't think we need to be sweating this scenario too badly as it relies on a phase. TLDR:
We are watching for two (plus) phases to occur for this storm. The first one happens around hours 95-110 and involves our initial SW with a small bit of NS vorticity that gives it a boost east. Currently only the GFS and ICON miss this phase which leads to their meager snow amounts. Additionally, this phase should be resolved soon as its closing in on only four days away.
If we get past that phase I feel confident in saying there will be a major east coast snowstorm this weekend. The only question is where and how much… The AI models keep it all southern stream based. The Euro OP gets close to an absolute dumping but the NS interferes with the SW to some extent. The UKMET shows a perfect balance of SW and NS interaction and the Canadians go ham which leads to over amplification. All of these subsequent models are all based on the interactions with our SW in the plains and the NS to its north... will just have to wait and see. If I had to personally pick as of now I'm terrified of the GFS or ICON being right because it would just suck so bad to miss this window. Other than that I think something like the Euro OP is most likely with a bunch of messy wave interactions preventing a clean phase.
Thank you for reading and happy tracking.
