Sometime last week rumors began to fly that a monster blizzard will impact the northeast this weekend. Since that social media uproar, I have been asked repeatedly what my thoughts are and whether or not I think it has merit. In this blog, I will give you my point of view on the manner by diagnosing the overall pattern. As we all know, it is the pattern that brings us storms, not the models themselves (if so, I would take the DGEX any day of the week, twice on Sunday).
Remember two mornings ago when we woke up to find the 06z GFS model show this?
A 980mb low off the coast of NJ bringing blizzard conditions and dropping 1 to 2 feet of snow in the area. Soon after, the models suddenly lost that idea and trended to a much weaker one. The reason for this was because they have changed the way the upper level pattern comes together for the upcoming weekend.
Here is the same 06z GFS run from that morning now looking at the 500mb vorticity map. You can see the beautiful trough in the center of the country working its way eastward as it attempts to close off, with a nice +PNA ridge spike in the western US and a nicely placed 50/50 block south of Greenland. This particular run of the GFS phased both the northern and southern stream energies way back in the western U.S. as they were both coming ashore. The confluence over the northern tier of the country is preventing the phased-out storm from cutting north, so it has no choice but to reach our coastline.
Now, the upper level maps look different. But not by much!
Here is the 12z EURO height anomaly map at h5. The overall pattern is actually conducive for storm development along the east coast. There is our everlasting -EPO ridge providing Pacific blocking, the 50/50 block near Greenland that I referenced from the 06z GFS map, and a block (AGAIN) in the Bering Strait. I say "AGAIN" because this block was also there for our January 21st storm last month and it helped force a phase along the east coast to develop the storm. The ONLY thing missing from this map that was existent on the 06z GFS map is the +PNA ridge in the west US. It is much more flatter on the EURO (and every other model now).
1. The western ridge helps dig the western energy on its eastern flank and helps in amplifying the trough on the east.
2. The 50/50 block near Greenland as well as the Atlantic ridge will help hold everything downstream in place to try and get this storm to form. If a storm does develop, it would be a slow mover due to the traffic of storm in eastern Canada (something we have not really seen so far this year).
3. The piece of the Polar Vortex over the Hudson will prevent a cutter and help usher in the cold air mass.
4. The Bering Strait block is showing up, and I think in the end it could benefit us once again like it has before this season.
5. The -EPO has been there since the get-go, bringing down arctic air masses and intense short waves. This time, it could possibly help kick that northern stream energy into the CONUS and also help in ushering in the cold.
Looking deeper into the 12z EURO vort maps, we will examine the micro version of the overall pattern. By Thursday night, both energies associated with developing this potential storm are coming ashore from the Pacific Ocean. You can see I have both circled in the image above. There is a piece of our PV over the Hudson Bay, confluence from coast-to-coast, and the 50/50 block.
SO, as I bluntly state at the bottom of that image:
ALL THE PIECES ARE THERE
The big storm idea may have disappeared, but the setup has remained the SAME.
Advancing to Saturday morning, you can see both pieces of energy are well far apart. The Sub-Tropical Jet stream short wave has zipped ahead of the Polar energy, and the overall look of the image is flat. The trough is obviously not as pronounced and the western ridge is non-existent (remember the 06z GFS phased both those pieces of energy together and it had a western ridge). One thing I question is immobile Polar energy and why it just sits there. It could be because of the lack of ridging, but I would still expect it to track into the CONUS.
Continuing on into Sunday morning, we are left with a very elongated look of the short wave energies since that Polar energy continues to remain stationary over the Pacific NW. An inverted trough develops from the southern stream energy and there is some phasing from the confluence which enables light snow to overspread the area.
The 12z Canadian model also looks similar to the EURO in respect to the short wave energies and the confluence in the CONUS. You can see the phase is not that far from happening, but we need a pulse from our west to help bring down that northern stream energy out of the Polar Jet and phase it into the STJ.
My Thoughts:
1. Regardless of how latest guidance is playing out the storm, nothing has changed with the players involved to bring a large storm system together.
2. The energy is still out in the Pacific and proper sampling will not take place until 06/12z model runs FRIDAY MORNING.
3. That lead vort (southern stream energy) needs to slow down to allow the northern stream energy to catch up (even if it's not the Polar jet energy, maybe we can get a piece of the confluence to phase into it instead).
4. I want to see the ridge in the west come back (+PNA) because I think that's important for an amplified trough in the east.
5. The Bering Strait block is important because usually blocking is under-modeled and if it turns out to be stronger, it could force a phase.
6. I sincerely believe we will see a moderate snow event (at least) Sunday into Monday. I feel like the models are going through their usual games. The pieces are there and I think enough of them will come together to bring us something substantial. Will it be the full blown 2-3 foot blizzard? Probably not, but I can see another 6"-12" type of event on the table with the potential for something greater.
To be honest, the models clearly show the storm off the coast since that southern stream energy is strong to begin with. What we are looking for is a trend back to the west. The fact that they did not even totally lose the storm is encouraging in itself. You can not expect these models to show run after run of MECS/HECS's along the coast. Of course they're going to run into inconsistency. Right now, they're showing widespread 2-4 inch type of snow amounts. I think by Friday, once the energy is sampled, we will have a MUCH better idea.
Valentine's Day Storm?
I'm not just bringing this up to save my ass just in case the storm this weekend does not come to fruition. Guidance is showing a lot of short waves entering the US next week, including another potent STJ energy. Hey, somethings gotta give, right? What I want to mention briefly here is we are losing our -EPO (not sure yet whether this is permanent or temporary), but we may be heading into a -NAO period. The Stratosphere has warmed and I think (hope) we have reached our lag period and the Atlantic begins to re-invent itself from what we have seen thus far. In conjunction with the -NAO, we could also be looking at a +PNA. The two together could bring us formidable storms and I think that could be in the cards mid to late next week! If this does turn out to be the case, you can be sure I'll make everyone aware of it.
Have a great day!
Francesco Paparatto
*Follow the NJ Strong weather forum at www.njstrongweatherforum.com*
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