February storm threat discussion

[Ji]

pretty much...there is a very weak wave of low pressure moving to our west that tries to pop a very weak coastal that misses us...the whole thing is sloppy and uninspiring and might bring some very light snow/rain Saturday night, sunday

Gfs I'm sure will fold to the euro like it always does.

[Deck Pic]

Gfs I'm sure will fold to the euro like it always does.

it isnt a very good run....neither the PAC or the Atlantic look that great by the end

[MDstorm]

Gfs I'm sure will fold to the euro like it always does.

You may be right, but the Euro has not settled into any consistent solution for next weekend. The GFS ensembles have been consistent showing a storm threat for next weekend. Now the spread on the ensembles is large, however almost all of the members have a storm somewhere along the eastern seaboard next weekend (some have stronger secondary re-development than others). Until the Euro settles down or the GFS punts on the storm idea, it will be interesting to follow.

MDstorm

[Srain]

Lots of model variability. I smell WSR on this one.

Good.

[Ji]

Gfs I'm sure will fold to the euro like it always does.

Gfs folded. The run is a disaster and winter is still over. There is not one cold day on the run

[CoastalWx]

Euro hates us

Why did you invest hope in the Friday deal. Even up this way, we are leery of anything great...well except Kevin.

[CoastalWx]

As far as the pattern down this way, I think it won't turn more favorable for anything..until maybe near the 10th or so. This is when the trough may retro enough to open the door to more widespread threats in the East. There may be enough of a ridge out west, and ridging poking into Greenland for a brief time, to allow this to happen...but this is not a certain thing at all. Of course you could always get clipped by Miller B's or maybe even overrunning, but I think the better chance comes maybe near the 10th. JMHO. Without a stout -NAO, I know it can be tough, so I don't think you can use stronger words..other than "chance" right now..but keep watching going forward.

[showmethesnow]

Gfs folded. The run is a disaster and winter is still over. There is not one cold day on the run

Not sure why you are living and dying but each run of the GFS op when it is flip flopping like a fish out of water. Not saying they are right but I think I would put more stock in the ensembles which look decent and have been far more consistant then the OP.

[Ji]

Why did you invest hope in the Friday deal. Even up this way, we are leery of anything great...well except Kevin.

I didn't invest in a Friday event...I was thinking maybe a chance late weekend

[CoastalWx]

There is still some model disagreement on timing. With this flow and changing regime, models will struggle.

[mitchnick]

There is still some model disagreement on timing. With this flow and changing regime, models weenies will struggle.

fixed

[showmethesnow]

fixed

[CoastalWx]

fixed

Well that's true too.

[Ellinwood]

Regardless of the individual storms, the models are actually progressing the cooler pattern into the 6-10 day, which is a good sign that will be a cold period in the eastern U.S. early-mid Feb. that will allow for snow chances.

The next step is trying to figure out where the longwave trough will set up within this cooler regime. (EDIT: or if there will even be one)

[usedtobe]

Right now on the ensemble means at least thru day 10 it looks to be a little east of where we'd like plus the models still seem to be showing a negative ao as they have high heights back over the azores and low heights near and just south of iceland. That implies systems probably ould be moving really fast. Still the amplitude of the pattern suggest a period of colder than normal weather and that's a start.

[clueless]

Torch this week and rain, folks, on the weekend.

Perhaps the 6-10 will verify and we have a chance.

Otherwise we will always have Paris.

[mitchnick]

to break the back of a seasonal pattern that has held strong for over 2 months is going to be a biatch, especially with global SSTA continuing to support it

as much as I want it, I am skeptical of the models

and even if we do get a "change" to sustained cold for a time, will the pattern be conducive to snow as we won't have much time to cash in

so my advice is to avoid visiting the high floors of tall building for the next 45 days

here's hoping to a better next year

[clueless]

to break the back of a seasonal pattern that has held strong for over 2 months is going to be a biatch, especially with global SSTA continuing to support it

as much as I want it, I am skeptical of the models

and even if we do get a "change" to sustained cold for a time, will the pattern be conducive to snow as we won't have much time to cash in

so my advice is to avoid visiting the high floors of tall building for the next 45 days

here's hoping to a better next year

CPD said in its note that although perhaps colder in mid-Feb, it would also be dryer pattern. FWIW.

[WinterWxLuvr]

Bits and pieces from HPC.

THE 00Z ECMWF

IN PARTICULAR COMPARES UNFAVORABLY TO OTHER MODEL/ENSEMBLE

GUIDANCE WITH ITS SHRTWV TRACKING FROM THE SRN ROCKIES INTO THE OH

VLY DURING WED THU......

THE RAPID SHARPENING/AMPLIFICATION OF THE WRN

NOAM RIDGE SEEMS TO FAVOR AT LEAST AN INTERMEDIATE TROF AXIS

VERSUS THE ERN SIDE OF THE ENVELOPE.....

A DIFFICULT AND LOW TO NO

CONFIDENCE FORECAST IN DETAILS LATE PERIOD MAINLY WITH THE ERN

CONUS TROF.....

DEPICTION BY DAY 5 FRI

OF A CENTER JUMPING SFC LOW FROM THE OH VALLEY TO THE NC COAST AND

THAN AN EXIT NEWD TO NEAR THE NEW ENG BENCH MARK BY DAY 6 SAT

SEEMS REASONABLE AT THIS TIME ALBEIT WITH CONTINUED VERY LOW

CONFIDENCE.

[Wonderdog]

I have a question about the individual ensemble members. Has there ever been a study as to which of the ensembles, as depicted on the model page, is more accurate than the others?

[chris87]

I have a question about the individual ensemble members. Has there ever been a study as to which of the ensembles, as depicted on the model page, is more accurate than the others?

I believe each individual ensemble member has no statistical relationship to that specific member from a previous cycle. The goal of ensemble forecasting is to quantify the "uncertainty" in model space, assessed by applying perturbations to the initial conditions of each ensemble member [i'm sure dtk can correct any misinformation here!].

[mitchnick]

Bits and pieces from HPC.

THE 00Z ECMWF

IN PARTICULAR COMPARES UNFAVORABLY TO OTHER MODEL/ENSEMBLE

GUIDANCE WITH ITS SHRTWV TRACKING FROM THE SRN ROCKIES INTO THE OH

VLY DURING WED THU......

THE RAPID SHARPENING/AMPLIFICATION OF THE WRN

NOAM RIDGE SEEMS TO FAVOR AT LEAST AN INTERMEDIATE TROF AXIS

VERSUS THE ERN SIDE OF THE ENVELOPE.....

A DIFFICULT AND LOW TO NO

CONFIDENCE FORECAST IN DETAILS LATE PERIOD MAINLY WITH THE ERN

CONUS TROF.....

DEPICTION BY DAY 5 FRI

OF A CENTER JUMPING SFC LOW FROM THE OH VALLEY TO THE NC COAST AND

THAN AN EXIT NEWD TO NEAR THE NEW ENG BENCH MARK BY DAY 6 SAT

SEEMS REASONABLE AT THIS TIME ALBEIT WITH CONTINUED VERY LOW

CONFIDENCE.

we don't know what's gunna' happen, so we'll put a dying slp in OH, pop a new one off the NC coast then move it to the benchmark

ya' think maybe 1 or 2 of the young weenies from Wright Wx have grown up and are now working at HPC? lol

[WinterWxLuvr]

we don't know what's gunna' happen, so we'll put a dying slp in OH, pop a new one off the NC coast then move it to the benchmark

ya' think maybe 1 or 2 of the young weenies from Wright Wx have grown up and are now working at HPC? lol

Regardless of where they came from, I think it's safe to say that they know more than either of us. They did state that it was a very low confidence forecast.

All I did was post what I thought was an interesting write up of the situation for the week ahead.

[chris87]

we don't know what's gunna' happen, so we'll put a dying slp in OH, pop a new one off the NC coast then move it to the benchmark

ya' think maybe 1 or 2 of the young weenies from Wright Wx have grown up and are now working at HPC? lol

they have to make a forecast...they note the uncertainty and present a viable, "albeit, not likely to be accurate" solution.....i'd like to see your discussion..so I can subsequently lol at it, j/k. in general, cut them a break...they seem fully aware of the issues on the table.

[usedtobe]

they have to make a forecast...they note the uncertainty and present a viable, "albeit, not likely to be accurate" solution.....i'd like to see your discussion..so I can subsequently lol at it, j/k. in general, cut them a break...they seem fully aware of the issues on the table.

And neither of the guys writing the discussion are snow weenies. One is nearing retirement and the other is a guy who really knows statistics.

[dtk]

I believe each individual ensemble member has no statistical relationship to that specific member from a previous cycle. The goal of ensemble forecasting is to quantify the "uncertainty" in model space, assessed by applying perturbations to the initial conditions of each ensemble member [i'm sure dtk can correct any misinformation here!].

You ask and you shall receive. First, you're basically correct....and from a scientific (and design) standpoint, every member should be an equally likely outcome.

However, the GEFS system does have one quirk relative to the other major operational centers that can lead to some correlative skill characteristics by "member number" (albeit with a 24 hour lag). The GEFS initial perturbations are applied using something called an ensemble transform (rescaled) method, which for all intents and purposes is a variant of breeding. For each cycle (00, 06, 12, 18), there is actually an 80 member ensemble of short (06h) forecasts. Those 80 forecast perturbations are then rescaled (shrunk) to represent initial condition perturbations (they are also reorthogonalized). From the 80 initial perturbations, only 20 are selected and integrated out as part of the EPS. The problem is that the selection process isn't random:

00 UTC : members 01-20

06 UTC : members 21-40

12 UTC : members 41-60

18 UTC : members 61-80

I guess this was was chosen to try and maintain "forecast continuity". The naming convention for the products does not actually line up with the member number within the perturbation cycling. In other words, member NN" is not the same cycled "member NN" between each of the 4 cycles/day.

I suppose then it's possible through the breeding and selection process there could be relationships between the members (with a 24h lag though, not from cycle to cycle). This has become less likely now that they have implemented stochastic noise in the ensemble model integration.

[mitchnick]

everybody jumps in on my HPC post

obviously I was kidding, but you have to admit that's on he!! of a storm track to pick from out of all the variety of possibilities the models have shown

[chris87]

You ask and you shall receive. First, you're basically correct....and from a scientific (and design) standpoint, every member should be an equally likely outcome.

However, the GEFS system does have one quirk relative to the other major operational centers that can lead to some correlative skill characteristics by "member number" (albeit with a 24 hour lag). The GEFS initial perturbations are applied using something called an ensemble transform (rescaled) method, which for all intents and purposes is a variant of breeding. For each cycle (00, 06, 12, 18), there is actually an 80 member ensemble of short (06h) forecasts. Those 80 forecast perturbations are then rescaled (shrunk) to represent initial condition perturbations (they are also reorthogonalized). From the 80 initial perturbations, only 20 are selected and integrated out as part of the EPS. The problem is that the selection process isn't random:

00 UTC : members 01-20

06 UTC : members 21-40

12 UTC : members 41-60

18 UTC : members 61-80

I guess this was was chosen to try and maintain "forecast continuity". The naming convention for the products does not actually line up with the member number within the perturbation cycling. In other words, member NN" is not the same cycled "member NN" between each of the 4 cycles/day.

I suppose then it's possible through the breeding and selection process there could be relationships between the members (with a 24h lag though, not from cycle to cycle). This has become less likely now that they have implemented stochastic noise in the ensemble model integration.

Thanks! Great description.

[usedtobe]

everybody jumps in on my HPC post

obviously I was kidding, but you have to admit that's on he!! of a storm track to pick from out of all the variety of possibilities the models have shown

I was defending two friends and didn't realize it was a joke.

[Feb]

I was defending two friends and didn't realize it was a joke.

In all honesty i didn't take it as a joke either. I would not want to be a forecaster right now. This is where we weenies should step aside and let the pro's do their job.