A disruptive snowstorm is eyeing the I-95 corridor beginning Tuesday morning and continuing into early Wednesday morning of this week. A potent piece of energy will be ejecting out of south-central Canada Monday night with the Polar Vortex situated to our north. Along with a few other variables, including the very cold temperatures, this is setting the scene for a moderate storm to impact the area.
Lets first take a look at the players on the field and where they are positioned on each model (GFS and EURO):
00z GFS:
At hour 42 per the 00z GFS, there is a +PNA (western ridge) with positive heights extending into Alaska. Toward southeastern Canada, there is a weak Polar Vortex and a piece of its energy will be breaking off and digging into the trough in the eastern U.S. It is able to dig mainly due to the massive ridge in the west. Lastly, just like the January 3rd storm from earlier this month, there is last minute blocking, or -NAO, showing up on the models that is allowing the PV and the ULL over Newfoundland to to stay put and help slow the storm down a bit once it develops. This also helps the trough go negative since the progressive nature of the pattern is cut-off. At this point, the trough in the eastern U.S. is neutral and the energy is really digging.
By hour 51 of the 00z GFS, which is late Tuesday night or early Wednesday morning, the GFS has brought the trough negative and this is where the storm reaches its height with moderate snow falling and extremely cold temperatures in place. The arctic-like temperatures would help raise the ratios from 10:1 to at least to 15:1 and 20:1 in some cases. You can see from the above map that the blocking the GFS outputs is impressive which is why at the 00z run it came out with an impressive solution of widespread 3 to 6+ inch snowfall amounts region-wide.
00z EURO:
The EURO model caved west from its 12z run, but is still not as impressive as the GFS and a couple other short-range models in the snowfall department.
At hour 54 of the 00z EURO, you can see the trough does go negative and there is region-wide light snowfall accumulations (especially in SNJ, coastal NJ, and LI), but the storm does not have a chance to amplify and slow down. The biggest reason for this is because of the "kicker" like piece in south-central Canada circled in black on the map above. Due to the weak state of the PV, there are a lot of upper level s/w energies retrograding and spinning to our north and this one is particular is trying to kick our coastal storm out to sea. The GFS model has this piece further north and west hence why it shows a more impactful snowstorm for the area.
Taking a closer look at the h5 vort maps (GFS top, EURO bottom), at hour 48, you can see the EURO has the trough still in a mainly positive state while the GFS is already at neutral. You can also see that feature northeast of Maine on the 00z GFS that looks like an upper level low that could be helping to bring the trough toward a negative state sooner, whereas the EURO does not have such thing.
Amazingly, these are pretty big differences with two very well known global models in the upper levels. Whichever one turns out to be correct will ultimately determine how this storm will evolve.
Temperatures:
Just so you have an idea, this is what temps are expected to look like as snow is falling Tuesday night
Mainly low 20's to mid teens and colder as you head north and west (but those areas will also see less snowfall). In fact, temps are looking to remain very cold through the rest of the week. So whatever snow falls will stick around for quite awhile. This will raise snow ratios to at least 15:1 and potentially higher.
Winds:
Winds are expected to be particularly bad for coastal NJ and Long Island, especially the east end. Blizzard-like conditions are possible for central and eastern LI since the cold temperatures will cause this snow to be powdery, meaning the winds will easily kick it up and reduce visibility. There exists the chance the NWS issues blizzard watches for this area Tuesday night into Wednesday morning.
Ultimately, we have to see more model guidance to see which direction they decide to go in. The upper levels between the GFS / EURO are drastically different but both models still bring a light snowfall event to the area. Regardless, we should be looking at some accumulating snowfall beginning late Tuesday morning and lasting into Tuesday night.
A snow map will be posted this morning at 11 am on the forum. I will also detail the timing of the storm at that time.
Happy MLK Day!
-Francesco Paparatto
*Please register to the www.njstrongweatherforum.com for continuous updates on the storm*
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