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

Typhoon Tip

By Typhoon Tip,
in New England

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Baroclinic Zone
Baroclinic Zone

This should cover it.

HoarfrostHubb
HoarfrostHubb

All those cars I see in the morning must be going to the pot shops

CoastalWx
CoastalWx

You don't even need fancy fronto maps to see where pound town is below. Look at that inflow at 50-60kts slam into the s coast with lighter winds to the north. There is your front and convergence. Air

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Typhoon Tip

Typhoon Tip

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46 minutes ago, OceanStWx said:

ens_2022010512_ne_24h_sfi_SFC_60.png

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.

Chris my personal belief is that this S/W is being undermined by the poor western ridge/lax expression therein; frankly, it doesn't atone very well for a total +2 SD recovery of the PNA.  Not sure why the ridge didn't get just a wee bit more of boost.  I have been noticing over the last two days of models, ... as little as 3 dam growth has always accompanied the more robust/west strikes with this thing - it's that sensitive.

Flat tho... and fast.  Both attributes I was over sold on when starting this thread. I thought that concomitant with the western ridge being more like a g-damn +PNA arrival... the flow would also slow at least some.   Neither of those is really being modeled to do so - best laid plan. 

As is..its truer power is perhaps hidden a bit. Models have routinely been under bellied by 120 kt 500 mb flags ... to as much as 150 at 300 at times, regardless of the low arc curvature of the trough -

If that ridge in the west had done it's part, this thing would would definitely been extreme.

Agree with Will's concept that this is entirely ( for now...) mechanical forcing associated with Q-v. It seems to me that low being situated on the right exit region therein, is more because there lower trop. baroclinic gradient is probably more intense in that region ... laid in place by tomorrow's CAA.  Blah blah ..so as the jet noses over the M/A... 

But my hunch is folks need to watch the region ~ 2 deg or even 3 deg left of roughly the 534 non-hydrostatic contour. I could wonder if frontogenic forcing may bust some qpf lags

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eduggs

eduggs

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53 minutes ago, 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.

Your meteorological explanation makes sense.

But I can't help but feel that we get imprinted early on when a threat is still in the medium or long range. We categorize our initial impression of the magnitude of possibility as a kind of unconscious expectation. And I think this initial impression biases our gut feeling from then on.

It could explain why some people are dismissive of late-appearing threats that were not signaled in the LR or why they hold out hope for trivial events that were formerly modeled as monsters.

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JC-CT

JC-CT

Posted
Posted
21 minutes ago, Typhoon Tip said:

Chris my personal belief is that this S/W is being undermined by the poor western ridge/lax expression therein; frankly, it doesn't atone very well for a total +2 SD recovery of the PNA.  Not sure why the ridge didn't get just a wee bit more of boost.  I have been noticing over the last two days of models, ... as little as 3 dam growth has always accompanied the more robust/west strikes with this thing - it's that sensitive.

Flat tho... and fast.  Both attributes I was over sold on when starting this thread. I thought that concomitant with the western ridge being more like a g-damn +PNA arrival... the flow would also slow at least some.   Neither of those is really being modeled to do so - best laid plan. 

What do you think of the mid-month window

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tavwtby

tavwtby

Posted
Posted

you know people are itching when we're nearly a week and 100 pages deep on a 1-3/3-6 event for SNE... we're all praying for last minute changes I'm sure but I think we can lock this in now... although kinda had a feeling this wouldn't be the one we thought from go, but still have some time to correct west and amp some more I suppose, onward to mid month!

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