March Roaring In Like A Lion - Northeast Snowstorm Early Next Week

The winter that never ends continues into March with a large snowstorm taking aim on our area once again. After taking a closer look at data this afternoon and getting a better understanding of how this storm will develop, I can confidently say another plow-able snowstorm will impact the northeast Sunday into Tuesday morning (March 2nd-4th). The worst of the storm is expected to occur throughout the day on Monday. 

One of the driving mechanisms bringing back the arctic air and the stormy weather is the MJO. This phenomena monitors convective storms that form around the world and is divided into eight phases. Phases 8-1-2 in the month of March, which is the current and foreseeable state of the MJO, bring colder than normal and stormy weather to the eastern U.S. This is one of the reasons why the drought-stricken state of California is finally able to see rain over the next few weeks. 

The MJO is not the only signal jump starting our winter pattern. The EPO, as has been the case most of this winter, is back in a negative state and trending even further negative (near -4 value) by this weekend. This means blocking in the eastern Pacific, including Alaska and western Canada has formed. Additionally, the AO is also negative which does not surprise me given the extreme negative state of the EPO and the arctic air mass we are currently dealing with and will still have to deal with for the next 10 days. 

Lets take a look at the players on the field and see how this storm is coming together. As I have already mentioned, we have blocking over Alaska and western Canada due to the -EPO. There is confluence caressing the U.S.-Canadian boarder with strong vorticity over the Great Lakes (will take a look at this later). Our southern short wave, which is progged to be on the weak side hence the flat-looking eastern trough, is in the southeast. One of the most important players, the Polar Vortex, will situate itself somewhere just east of the Hudson Bay in southeastern Canada. The question is...where does the baroclinic zone set-up? Areas north of this boundary will see precip. fall in the form of snow while areas south of it see rain. Areas located along the boundary could see freezing rain / sleet. Also notice near Greenland I say, "No Blocking?" Technically, this is true. However, there is blocking on the other side of the globe that has prevented the PV's this season from escaping northeastward which in turn would allow the southeast ridge to amplify over our area. 

It is called Scandinavian blocking (sorry for the typo in the graphic). Positive heights over Scandinavia, or a   -SCA, have helped force our PV's this winter to sink south into the lower latitudes of the globe and promote much below normal temperature departures. This feature is going to help keep the PV situated over southeast Canada for the storm early next week, though there is room for it to trend north-northeast if it wanted to. 

What are the implications of that? 

Here is the upper air anomaly graphic from the 00z EURO run last night:

The PV was modeled weaker last night than the 12z run today which allowed eastern heights to extend further north, allowing the gradient to get pretty far north as well. This is why the 00z EURO run last night showed significantly less snowfall for the I-95 cities compared to today's run. 

You can see on today's run the PV is stronger and heights are suppressed a bit more. It may not seem like it at a quick glance, but take a closer look and you will see this minor difference changes the projected track of the storm drastically. 

Another ingredient we have to consider is the vort energy located over the Great Lakes, as well as the strained out H5 energy along the east coast. Right now, the southern s/w energy is projected to be weak. But if the vort over the Great Lakes intensifies further, it could force the southern s/w to trend stronger as well which could raise QPF amounts across the board. Right now, .75-1.00 of QPF is projected to fall Sunday-Tuesday, but I could see how this gets up to 1.25+ in a widespread location. This would mean snowfall accumulations, with ratios, of 16 inches or more in some spots. 

The jet streak over Maine is also expected to be impressive Monday morning, which is when the heaviest snow is expected to move into the area. 160+ kts. could really fuel this storm some more as we try and get a better idea of where the best lift at the 700mb level develops. Area JUST north of the gradient area likely to see the heaviest snow rates (but probably not the best ratios). This is why when all is said and done, everyone should receive significant snowfall from this storm. 

The one thing we have to watch which is certainly plausible is the Polar Vortex continues to trend stronger on the models and begins to force this storm to our south, while also shearing it apart (less QPF). The GFS has remained the most consistent and has not showed such a solution, but the EURO / CMC runs today could be interpreted that way (the EURO because it took a big jump from its 00z run). 

As of now, this is the area I see getting hit the hardest with snow early next week. This is more of a EURO ENS / GFS blend with some instinctive feeling. One of the trends this winter have been for storms to make a last minute push back to the north and west, which is why Philly has seen a very nice season in terms of snowfall. Central Park, NY is only 18.5 inches away from breaking their all-time single season snowfall record and this storm could get them VERY close to that record if everything aligns itself perfectly. I also feel the lack of blocking over Greenland could bring the PV slightly further north than where the EURO / GGEM currently have it which is another reason why I like the GFS / EURO ENS solutions. 

A first call snow map will be released tomorrow afternoon around 6pm. Please follow the www.njstrongweatherforum.com for continuous coverage of this storm with the latest information!

Thanks for reading, 

Francesco Paparatto

Setting The Stage: Godzilla Snowstorm February 13th

Toward the end of my previous blog, I briefly mentioned that the period around Valentine's Day will be the next one to watch for a potential snowstorm due to the potent STJ energy entering the SW CONUS. Here we stand a few days later, tracking a major east coast storm to impact millions of people across the eastern seaboard. Although specifics of the storm for our area such as snow amounts, exact track, and timing are not set in stone yet, we should look at upper level maps and seasonal trends to try and help steer us in the right direction.

The above is the 12z EURO model run at the 500 mb level. By looking at the vort maps, we are able to see that the EURO closed off the H5 vort over central North Carolina. This model is the only model to close off H5 this early which is why it is taking a storm track right along the coast. Heights rise ahead of it and the storm tightens / strengthens much quicker. The region starts as snow, then changes to rain, to end as snow. 

In comparison, the 12z GGEM (Canadian) model does not close off H5 at the time the EURO does, but the energy at the base of the trough is much stronger which still raises heights off our coast to promote a storm track tucked in west from the benchmark. In fact, the GGEM really explodes this storm system and brings crazy amounts of both snow and rain to the area. Of the three global's, the GGEM is the strongest one. 

The GFS also does not close of H5 as early as the EURO model. However, this model has struggled greatly with the synoptics of this storm because it has been shearing energy from the west side of the trough which strings out the low level center a bit. The mid-levels fall apart and the surface maps begin to make no sense with a 980 mb low off the coast with not much precip. to show for it.  The GFS has made strides to the other models, but at this point, I think it should be disregarded until it straightens itself out. Heights are also flatter along the east coast compared to the GGEM/EURO which is why the GFS tracks this storm right on or just east of the benchmark. 

A common theme you will find in all of these models is that it does warm temperatures up enough to change snow to rain for some locations, including NYC Metro. This is where the forecast becomes tricky. 

Here is another look at the 12z GFS model. One thing you will notice is that there are two areas of High Pressure surrounding the northwest and southwest quadrants of our coastal storm. The first one is north of Maine, which could help provide us with cold air to prevent snow from changing to rain. The second is along the Gulf coast. The third piece we should pay attention to is the potent clipper in the Great Lakes region. One of the many things I am keeping an eye on is if those two anomalies are providing too much subsidence for our coastal storm to really deepen and bring moderate to heavy banding over our area. Vertical velocity at H7 (frontogenesis) is not going to be impressive if those two pieces are there to disrupt the evolution of our coastal storm and preventing it from amplifying. This could be one of the reasons why the GFS has a funky look to it and I definitely think it should be monitored. 

Another important factor to look at is to see where the 700 mb and the 850 mb low's close off. The Canadian model, for example, vertically stacks each of these low's inside the BM which is another reason why it outputs such an extreme scenario. 

For example, 

12z GGEM 700 mb

12z GGEM 850 mb

One other factor I am considering when trying to forecast this storm is the seasonal trend. We are now in mid-February and have a good idea of how the storms this season have behaved. None of them had a storm track inside of the benchmark. Most of them remain south and east of the benchmark and brought the heaviest precip. amounts along I-95 and points east. I'm only mentioning this because the GFS / NAM models are not sold on the idea of having a storm track hugging the coast. I can see why with the lack of blocking (-NAO) and areas of confluence to the west of the storm why those tracks could be justified. 

How all these factors evolve will determine how this storm plays out along the NYC Metro area. Consistency is there that a long duration event is likely to begin early Thursday morning and continue into Friday morning, possibly a 24-hour + storm. It is certainly possible Blizzard criteria is met and watches / warnings are issued for the area, but that will not be realized until the factors I mentioned above are known. 

Here is an example on the extreme side of what winds at the surface could look like for our area. This is from the latest 18z NAM:

With all that being said, here is my 1st call snow map with this storm system likely to be changed again tomorrow. But I wanted to put this out there so everyone can get an idea of how I view this storm panning out. I do think the GGEM/EURO are a little too far west right now. While they have been consistent, we cannot ignore the consistency of the GFS/NAM either. The UKIE was also a little more east today at 12z compared to its 00z run. A lot depends on when exactly H5 closes off. I think it will happen along the coast of NC or SE VA, not interior Mid-Atlantic like the EURO shows. 

My current thinking feels the models tonight into tomorrow will begin a trend with this storm system a little further east. I think a track right along the benchmark is fair to say at this time because of some of the factors I mentioned throughout this blog post. If the western most track comes to fruition, the heaviest totals will have to be pushed further west and lower amounts will occur along the immediate coast due to mixing. At this time, I do not see that scenario panning out but this is a high volatility forecast. 

Temperatures Thursday morning, the time the storm is expected to start, are only in the low to mid teens across much of the area. Couple that with a possible High to the north and evaporational cooling from our current snow pack, I think models also have a good chance of trending colder with this storm once the dynamics are realized. There is a lot to digest here. Extremely complex set-up. 

Thanks for reading, 

Francesco Paparatto 

*Please visit the www.njstrongweatherforum.com forum for continuous discussions about this impending storm*

What Happened To The 3-Foot Blizzard February 9th-10th?

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*