Tracking Jan 7 coastal storm. Lingering compression/flow velocity has not lent to consensus, but it seems at 30 hours out.. finally?

[ORH_wxman]

Just now, CoastalWx said:

I feel like a weenie, but I just feel like this has a few tricks up its sleeve. Why do I feel like 3K NAM might have an idea?

We both feel that way because we're looking at a concentrated ball of strong vorticity rounding the base of that shortwave and then curling into E LI and the Cape. The stronger solution honestly makes meteorological sense...but we know convection-robbing of conveyors can be real, but we just don't when it is and when it's a model phantom.

[CoastalWx]

Just now, ORH_wxman said:

We both feel that way because we're looking at a concentrated ball of strong vorticity rounding the base of that shortwave and then curling into E LI and the Cape. The stronger solution honestly makes meteorological sense...but we know convection-robbing of conveyors can be real, but we just don't when it is and when it's a model phantom.

I mean how many times have we seen that and it goes from offshore to a local jack....or am 18" storm here to 6"-->rain with a jack near Albany. Maybe this one is different...but I just feel like it comes west.

[weathafella]

4 minutes ago, 8611Blizz said:

Funny he mentioned Brookline when talking a bout the 1-2" line

Well the luxury is everyone can adjust up or down tomorrow-still time for that.

[Greg]

As much as I'd love to see these models come to wishing, I always remain guarded when the amped 18Z come in like this. We all know or should know for that matter that the 00Z suite will end up keeping things reasonably in check.

[OceanStWx]

There's some good news I guess. Based on the 00z EPS, the extreme forecast index is okay for the AEMATT crowd. 

This index essentially shows how unusual the EPS forecast is based on the last 20 years of the model climate in the 5 weeks centered on the date (the climate built by many model runs, not state of the climate according to the model). Values between 0.5 and 0.8 are unusual, above 0.8 very unusual or extreme. A value of 1 means that every EPS member is more extreme than the model climate. 

The thing to keep in mind is that significant snowfall, even in the winter, is unusual. Most days it doesn't snow. But there is a signal for some significant impacts possible according to the EPS.

Also note that this index doesn't say how extreme. It could be a little more extreme than the model climate, or a lot more extreme. That's where the black lines come into play, that's the shift of tails (SOT). A value of 1 indicates that the 90th percentile of the forecast is one times the distance between the 90th and 99th percentile of the model climate. A value of 10 would be ten times. A SOT appears when at least 10% of EPS members are forecasting an event greater than the model climate extreme. Say the model climate extreme is 6 inches and the difference between the model climate 90th and 99th percentile is 1 inch, with a SOT value somewhere between 0 and 1 (call it 0.5) this 90th percentile forecast would be 6.5 inches.

Notice how the SOT values are higher and the EFI higher down around DC. That's because snow is more extreme in that area than New England, and more likely to be an extreme event based on forecasts.

[forkyfork]

3 minutes ago, CoastalWx said:

I mean how many times have we seen that and it goes from offshore to a local jack....or am 18" storm here to 6"-->rain with a jack near Albany. Maybe this one is different...but I just feel like it comes west.

i don't understand how so many people who have tracked these things for years cannot learn that models change

[NorEastermass128]

2-4/3-6 works for now.   I would broad brush 2-5+

[TauntonBlizzard2013]

1-2” in se Mass doesn’t make much sense if he has everyone else higher 

[40/70 Benchmark]

3 minutes ago, OceanStWx said:

There's some good news I guess. Based on the 00z EPS, the extreme forecast index is okay for the AEMATT crowd. 

This index essentially shows how unusual the EPS forecast is based on the last 20 years of the model climate in the 5 weeks centered on the date (the climate built by many model runs, not state of the climate according to the model). Values between 0.5 and 0.8 are unusual, above 0.8 very unusual or extreme. A value of 1 means that every EPS member is more extreme than the model climate. 

The thing to keep in mind is that significant snowfall, even in the winter, is unusual. Most days it doesn't snow. But there is a signal for some significant impacts possible according to the EPS.

Also note that this index doesn't say how extreme. It could be a little more extreme than the model climate, or a lot more extreme. That's where the black lines come into play, that's the shift of tails (SOT). A value of 1 indicates that the 90th percentile of the forecast is one times the distance between the 90th and 99th percentile of the model climate. A value of 10 would be ten times. A SOT appears when at least 10% of EPS members are forecasting an event greater than the model climate extreme. Say the model climate extreme is 6 inches and the difference between the model climate 90th and 99th percentile is 1 inch, with a SOT value somewhere between 0 and 1 (call it 0.5) this 90th percentile forecast would be 6.5 inches.

Notice how the SOT values are higher and the EFI higher down around DC. That's because snow is more extreme in that area than New England, and more likely to be an extreme event based on forecasts.

More like se MA.

[40/70 Benchmark]

2 minutes ago, forkyfork said:

i don't understand how so many people who have tracked these things for years cannot learn that models change

Emotions can be blinding.

[8611Blizz]

6 minutes ago, weathafella said:

Well the luxury is everyone can adjust up or down tomorrow-still time for that.

All three stations 5, 7, and 10 have mentioned this could all change.

These are for the most part "first call maps" .

[dryslot]

1 minute ago, 40/70 Benchmark said:

More like se MA.

SEMATT

[UnitedWx]

2 hours ago, ineedsnow said:

a watch for 4 to 6?

Issued all the time before a storm, to warn people something's approaching. Seen it many times where a watch is issued and turns into an advisory, not a warning

[OceanStWx]

As an example, here is February 1 of last winter. Northern NJ is showing an EFI around 1, meaning every EPS member was more extreme than the model climate. And with a SOT value of 2, the top 10% of EPS members were also quite extreme.

And well...

[forkyfork]

3 minutes ago, forkyfork said:

i don't understand how so many people who have tracked these things for years cannot learn that models change

like, why even bother being on a weather board? go stare at a wall and chew on glass or something

[CoastalWx]

1 minute ago, OceanStWx said:

As an example, here is February 1 of last winter. Northern NJ is showing an EFI around 1, meaning every EPS member was more extreme than the model climate. And with a SOT value of 2, the top 10% of EPS members were also quite extreme.

And well...

That hurts.

[SnowGoose69]

6 minutes ago, forkyfork said:

i don't understand how so many people who have tracked these things for years cannot learn that models change

In recent years probably due AGW and the W NATL SSTs, systems which in 1988 would drop 2-3 now drop 5-10 regularly despite same MSLP and similar H5/H7 setups.  But two factors have tended to keep coastal events in check despite 8 of 10 following the scenario I outlined...fast flow and brief separation between departing system and incoming one...in this case we basically have both at work so I feel aside from a small area of mesoscale banding this event is not gonna be a big one

[JC-CT]

baby improvement on the gfs, brings more in line with euro/3km i think

[weathafella]

When I see a surface low jump east hundreds of miles in 3 hours I become skeptical 

[40/70 Benchmark]

10 minutes ago, forkyfork said:

like, why even bother being on a weather board? go stare at a wall and chew on glass or something

Why get a meteorology degree if you're not going to be a meteorologist?

[78Blizzard]

23 minutes ago, CoastalWx said:

I feel like a weenie, but I just feel like this has a few tricks up its sleeve. Why do I feel like 3K NAM might have an idea?

I have that same gut feeling that some positive surprises lay ahead.

[Damage In Tolland]

If the  doubters Would  just literally go with 4-8” youll end up with a very good forecast . Going 1-2” in CT is going to end up looking very silly . Even Wull is being too conservative discussing EMA only 

[dryslot]

Thats a tic or two west on the 18z GFS

[OceanStWx]

11 minutes ago, CoastalWx said:

That hurts.

Sorry, should've included a trigger warning for the snow starved.

[moneypitmike]

1 minute ago, dryslot said:

'Thants a tic or two west on the 18z GFS

Need some tics and tocs.  Time running short.

[EastonSN+]

14 minutes ago, OceanStWx said:

As an example, here is February 1 of last winter. Northern NJ is showing an EFI around 1, meaning every EPS member was more extreme than the model climate. And with a SOT value of 2, the top 10% of EPS members were also quite extreme.

And well...

Phenomenal storm

[ineedsnow]

GFS increased snow amounts a bit and looked really close to being much better

[dryslot]

1 minute ago, moneypitmike said:

Need some tics and tocs.  Time running short.

You have tonight and all day tomorrow........

[CoastalWx]

Well gfs doubles amounts so that’s a start. 

[40/70 Benchmark]

Just now, ineedsnow said:

GFS increased snow amounts a bit and looked really close to being much better

Will probably jump at 00z