DECEMBER 16th 17th 2020 Snow Threat???

6z euro ensembles look fantastic. Slow moving low heading toward the BM. Coast changes from rain to snow. Remember this is a mean so don’t pay attention to the precip more so the location of the low and the H5 features (not shown)

84 hour NAM - which is useless - also is trying to kill the primary off fast enough for a secondary to take over and track a Godzilla to the BM

Long range SREFs - also useless - already have the trough tilting negative hahaha

Frank- is this a long duration event?

I got your video to work. You might be too caught up in the details. The 50/50 low is not technically in the 50/50 low position, you said, but that doesn’t mean it still doesn’t act like a 50/50 low would. It’s serving it’s purpose of anchoring a 1035mb HP to the north. Without the presence of the “50/50” that High with all the movement happening out west (rolling ridges and such) probably wouldn’t be there.





Your point about mid level low centers was a good one. If the 700, 850mb lows ends up west, we’re torched along the coast. However, again, they are also prevented from advancing too far north and end up transferring to a second low off the coast. The primary is not capable of holding on because the dynamics in the trough are hanging back a bit, likely because there is too much confluence being felt to the north.

Great video, let’s see if that’s where models trend the next couple of days. However, I’m gonna have to disagree for now!!


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Oh cool, glad you were successful, and thanks!! I agree that it helps set a high up, but it’s not locked into place because the blocking low is a bit too far north, and is not blocked from escaping east, so as the “50/50” low is allowed to drift east, the high is already going to be centered a little far east north, and then is able to start retreating in advance of the storm. As the high slides east and heights build in response, this opens a path for a warmer/further west event. But, as you said, we can agree to disagree and see how things unfold WE TRACK!!

dsix85 wrote:Frank- is this a long duration event?

Models always try to show a long duration event, then as it gets closer, they realize the blocking is not as prominent and speed everything up. I don’t believe this will be long. Under 24 hours. Maybe under 20 hours.

Frank_Wx wrote:

dsix85 wrote:Frank- is this a long duration event?

Models always try to show a long duration event, then as it gets closer, they realize the blocking is not as prominent and speed everything up. I don’t believe this will be long. Under 24 hours. Maybe under 20 hours.

So then are you saying that the current modeling is overplaying the block’s hand, and is therefore, too cold/suppressed?

rb924119 wrote:

Frank_Wx wrote:

dsix85 wrote:Frank- is this a long duration event?

Models always try to show a long duration event, then as it gets closer, they realize the blocking is not as prominent and speed everything up. I don’t believe this will be long. Under 24 hours. Maybe under 20 hours.

So then are you saying that the current modeling is overplaying the block’s hand, and is therefore, too cold/suppressed?

Depends on the model! GFS looks too suppressed. EURO/CMC are closer to what I believe will happen, which does leave room for a more WNW/warmer track

But I remain hesitant it gets too far N&W. Though, let's be honest, you're in the jackpot!

The worst case scenario for this system is still at 3 to 6 in front end thump followed by some mix or change to rain near the coast back to snow on the back end. That's if the system is one of the extreme outliers that are far west. Any responsible forecaster  would be warning their forecast area of a plowable event even if there is a mix. Forecast lows Wednesday morning are in the low twenties even down to New York City. This is not some marginal air mass we are working with

Wednesday’s energy is just coming on shore as we speak. Currently GfS coming in with subtly suppressed heights ahead of the main energy suggesting it will hold serve from 00&06z

12z GFS is very suppressed. More so than the 6z run.

Frank_Wx wrote:12z GFS is very suppressed. More so than the 6z run.  

Yup. In in a parking lot on my phone so hard to quickly scan details but need to see if blocking features to the NE are trending stronger and how ridge west is behaving. I still stand behind the line I drew for now regarding the idea that the dense cold air is almost always under estimated. al pointed that out too a few posts back

Frank_Wx wrote:12z GFS is very suppressed. More so than the 6z run.  

The biggest risk with the system is definitely suppressed we are now in mid-December with such a strong high pressure over Quebec it's going to be hard to scour out the cold air I'm just looking for some snow without any taint I'll even take 3 to 6 in of powder

Frank_Wx wrote:12z GFS is very suppressed. More so than the 6z run.  

For us that are clueless, does the GFS being very suppressed make for good news? Because that sounds like bad news.

HP stronger this run 1039 on GFS, storm comes up to Demarest and then kicks east as the HP presses and CCB explodes. Very good run.

Right now a General 6 to 12 in of snow looks very reasonable for our forecast area. Think about it how many 12 plus in snow storms have we had in December?

Irish wrote:

Frank_Wx wrote:12z GFS is very suppressed. More so than the 6z run.  

For us that are clueless, does the GFS being very suppressed make for good news?

The GFS being suppressed means the most heavy snow is I80 on southward. Cutoffs would be sharp after that. I'm not buying such a suppressed solution ATTM. I would split the difference between the GFS and Euro which means heavy snows go past the NY state border. GFS has shown too much volatility in conjunction with we are still 3+ days out.

heehaw453 wrote:

Irish wrote:

Frank_Wx wrote:12z GFS is very suppressed. More so than the 6z run.  

For us that are clueless, does the GFS being very suppressed make for good news?

The GFS being suppressed means the most heavy snow is I80 on southward.  Cutoffs would be sharp after that.  I'm not buying such a suppressed solution ATTM.  I would split the difference between the GFS and Euro which means heavy snows go past the NY state border.  GFS has shown too much volatility in conjunction with we are still 3+ days out.

Currently reminding me of days of old where GFS was always the most SE with the track; the euro with the most N&W with the end result in the middle of that cone of uncertainty created by the two but almost always leaning closer to the euro at this lead time.

I'm cautiously optimistic but in between sounds like the usual to me. And Al you bet 6 to 12!! Shoot I'll take it in heart beat anything to whiten up. Even 3 to 6 would already top last year with several months to go.

The CMC is more amp than the GFS. Takes the low right over Delaware and then once it feels the block low-level cold air jumps East to south of Long Island nice hit for the most of the area

jmanley32 wrote:I'm cautiously optimistic but in between sounds like the usual to me. And Al you bet 6 to 12!! Shoot I'll take it in heart beat anything to whiten up.

Jon we need at least four inches from the storm since almost every December with 4 inch or more of snow have gone on to have above-normal snowfall which I believe the majority over 30 in

Gfs seems yo be on its own euro tucked in cmc hadn't budged

algae888 wrote:The CMC is more amp than the GFS. Takes the low right over Delaware and then once it feels the block low-level cold air jumps East to south of Long Island nice hit for the most of the area

That actually sounds like it makes sense. If most get 6-12 inches, that would not only surpass last season's entire total in many areas but likely double or triple it, in one storm, in December, before winter even officially starts. WIN!

algae888 wrote:

jmanley32 wrote:I'm cautiously optimistic but in between sounds like the usual to me. And Al you bet 6 to 12!! Shoot I'll take it in heart beat anything to whiten up.

Jon we need at least four inches from the storm since almost every December with 4 inch or more of snow have gone on to have above-normal snowfall which I believe the majority over 30 in

yup. Let's hope we get slammed!

The latest discussion from Mt Holly. This is encouraging for the coasties (esp those of us that are both S and E) b/c it lays out several critical must-haves in order for us to have a big snow event, and then says they are all still on the table. That type of 'optimism' is very rare for Mt Holly.

00Z Guidance retains rather impressive run-to-run consistency
with respect to timing, track, and associated thermal profiles
with the low, and this is perhaps helped by the progressive
hemispheric pattern which tends to favor more predictability
than amplified blocking patterns. Consequently despite
considerable uncertainty regarding the details of this system
(more on that below) do have higher than average confidence that
at least portions of our area will see potentially significant
impacts from this system. The one thing to point out is that the
mid-lvl wave associated with this system is still over the
Pacific which does favor at least some caution in becoming too
confident although modern Data Assimilation is fairly robust
even in regions of observational sparsity.

In terms of timing, did not make many changes from the previous
forecast, and see precipitation beginning to move into our area
Wednesday morning, with precipitation increasing in coverage
and intensity Wednesday afternoon into Wednesday night as both
the sfc. low and UL jet streak approach. In general the EC and
its ensembles tend to depict the slowest progression, with
notable precip. continuing into the day on Thursday, while the
remainder of guidance has precip largely coming to an end
Wednesday night.

Unfortunately (or fortunately if you look at it from my
perspective) it is too early to get specific about ptypes and
snow amounts, as the low`s track near to the coast will almost
certainly result in some ptype transition zone. Furthermore this
transition zone will likely ebb and flow as mesoscale lift
(e.g. FGEN) results in dynamical cooling. That being said the
antecedent airmass does look primed for wintry precipitation,
with pre-storm dewpoints likely in the single digits or low-
teens which should support some fairly notable wet-bulbing with
the first batch of precip. The question then becomes can the
intensity of the precipitation and associated dynamical cooling
become enough to offset the increasing warm advection associated
with the low? The next question is how robust will
precipitation be on the back side of the low Wednesday night as
it pulls away from the area, and cold advection begins? We
should have more answers to these questions in the next couple
days we enter the Mesoscale model window.

Finally it is also worth mentioning that the latest guidance
does depict a rather tight pressure gradient between the
Canadian High and the intensifying low. This could certainly
result in gusty winds, and locations near the coast could
require wind headlines depending on the low`s track/intensity.

Thanks so much for all the hard work you guys are putting in. What a fun track this has been so far!

Here's how I see things shaping up imby (Exit 80 GSP) by probability of outcome:

No frozen precip: 10%
C-1":                  35%
1-3":                  35%
3-6":                  15%
6"+:                     5%

The Mt. Holly discussion completely disregards the Euro and CMC whichbodes well for central and southern NJ but NYC and north would not get a super big hit, and any more trend south we may be out of it completely, is that possible. It is disconcerting for us in Northern Jersey to NYC and N and West they are only buying the GFS.

Frank_Wx wrote:

dsix85 wrote:Frank- is this a long duration event?

Models always try to show a long duration event, then as it gets closer, they realize the blocking is not as prominent and speed everything up. I don’t believe this will be long. Under 24 hours. Maybe under 20 hours.

Yeah, sorry rb but I have to side with Frank, call me partial but I want a snowstorm, another rainstorm wouldn't be a surprise in 2020 though, not trying to be negative, just saying it as a possibility. My hopes are still up for now, if Frank you start to back down then I will give in lol