WOOF

[usedtobe]

Well, at least we have a few of the D8 analog composites on our side.

That "best" one, IMO, would be 12/22/66 which was preceded, 9 days, by 6.7" and followed by 7" on 12/24.

Then the 12/08/03 analog has a couple inches a few days before and 3.6" six days after.

The 12/31/79 analog didn't have anything just prior, but 6.9" just five days later.

12/7/50 saw 3.2" just three days later, but nada just prior to the target date.

If you look at the climo odds of getting 1.00" or greater snow at DCA during the Christmas week 12/19-12/25 inclusive, the odds are 1 about every 5 years. The chances of getting more than 4 inches is 7 in 100 years. To me the analogs suggest that the potential is somewhat higher than climo for both those thresholds but still fairly low. A one in 10 chance of getting 6 inches during the week of Christmas implied by the analogs (though 10 analogs is really not enough to draw such a conclusion) would be quite a big higher than climo.

[Ender]

I am a skeptical at this point regarding any deterministic attempt by respective models to hone in on an event -...even in an intuitive conceptual sense of it for general risk assessing I'm a tad spooked. Moreover, there isn't any clearly intriguing modalities in the teleconnector forecasts by either agency, the CDC or the CPC (and I am aware they have different methods for computing their respective values). In fact, I am seeing a lot of "dischord" more than anything else, with the CPC and CDC at odds with the NAO, and the CDC indicating more of a N/S with nearly neutral PNA at D10. It's just too incoherent in the background canvas to vest any confidence at all. That is not always true - btw - in that some times the pattern is better well behaved, intrinsically easier for the models, and teleconnector also at times having a clearly tendency then all leads to some pretty fantastic extended lead outlooks - now is not one of those times, however.

John

Yup, it's a relatively complicated, fast flow without any clear cut signals. This is not March 1993.

[PhineasC]

Wow that's a big dog!

I am a skeptical at this point regarding any deterministic attempt by respective models to hone in on an event -...even in an intuitive conceptual sense of it for general risk assessing I'm a tad spooked. Moreover, there isn't any clearly intriguing modalities in the teleconnector forecasts by either agency, the CDC or the CPC (and I am aware they have different methods for computing their respective values). In fact, I am seeing a lot of "dischord" more than anything else, with the CPC and CDC at odds with the NAO, and the CDC indicating more of a N/S with nearly neutral PNA at D10. It's just too incoherent in the background canvas to vest any confidence at all. That is not always true - btw - in that some times the pattern is better well behaved, intrinsically easier for the models, and teleconnector also at times having a clearly tendency then all leads to some pretty fantastic extended lead outlooks - now is not one of those times, however.

John

So, in summary, you are not sure if there will be a storm. Thanks for checking in.

[Ellinwood]

Meh.

[Ender]

If you look at the climo odds of getting 1.00" or greater snow at DCA during the Christmas week 12/19-12/25 inclusive, the odds are 1 about every 5 years. The chances of getting more than 4 inches is 7 in 100 years. To me the analogs suggest that the potential is somewhat higher than climo for both those thresholds but still fairly low. A one in 10 chance of getting 6 inches during the week of Christmas implied by the analogs (though 10 analogs is really not enough to draw such a conclusion) would be quite a big higher than climo.

That's funny because I did something like that just that last week. I've got all the first .1", first >.4" and first 1" events for DCA (along with the lasts) for the last 56yrs on a spreadsheet that I left on my work PC. There seem to be some favored windows for those "first measurable events". Once we get past 12/20-ish the next clear window/clustering of "firsts" isn't one I look forward to repeating.

[aldie 22]

Meh.

Good analysis

[Yeoman]

Wow that's a big dog!

I am a skeptical at this point regarding any deterministic attempt by respective models to hone in on an event -...even in an intuitive conceptual sense of it for general risk assessing I'm a tad spooked. Moreover, there isn't any clearly intriguing modalities in the teleconnector forecasts by either agency, the CDC or the CPC (and I am aware they have different methods for computing their respective values). In fact, I am seeing a lot of "dischord" more than anything else, with the CPC and CDC at odds with the NAO, and the CDC indicating more of a N/S with nearly neutral PNA at D10. It's just too incoherent in the background canvas to vest any confidence at all. That is not always true - btw - in that some times the pattern is better well behaved, intrinsically easier for the models, and teleconnector also at times having a clearly tendency then all leads to some pretty fantastic extended lead outlooks - now is not one of those times, however.

John

Was that last night's reading assignment?

[Typhoon Tip]

So, in summary, you are not sure if there will be a storm. Thanks for checking in.

No - I am stating logically why this is not an interval that carries along with it a higher degree of confidence wrt extended range forecasting.

Not sure what the purpose of your pop-off is ...

[usedtobe]

That's funny because I did something like that just that last week. I've got all the first .1", first >.4" and first 1" events for DCA (along with the lasts) for the last 56yrs on a spreadsheet that I left on my work PC. There seem to be some favored windows for those "first measurable events". Once we get past 12/20-ish the next clear window/clustering of "firsts" isn't one I look forward to repeating.

I got the data from Ian. I started to make a spread sheet with a running mean on it but then decided to just take the total number events during the week and divide it by the number of years. I then got an average frequency per day also so I could compute a smoothed climo pops for the various thresholds for xmas even and xmas. The climo pops for xmas for 1.00" was 2.9%, for 4" or more it was around 1%. All the TV shows that have been set in DC and show snow falling really strain credibility.

[Midlo Snow Maker]

ggem has something in the hr120-144

[OSUmetstud]

12z GFS ensemble has a much stronger storm signal than the OP.

[ptb127]

On the 12z GGEM, look at the high pressure over montana. In the cases I have seen, they almost all the time have a high pressure in that position.

[Guest someguy]

On the 12z GGEM, look at the high pressure over montana. In the cases I have seen, they almost all the time have a high pressure in that position.

WILD MONTANA SKIES .... QUE the john Denver music

[HM]

This is the Heather A. signal and makes sense to actually get some sort of coastal storm in this period as the block retogrades into the C. North America. The one thing that we have to watch out for is the wavelengths being too far to the east with the trough moving into the West Coast. The damn MJO is against the snow idea, but whatever. The NAO block is clearly trumping everything else.

[Typhoon Tip]

On the 12z GGEM, look at the high pressure over montana. In the cases I have seen, they almost all the time have a high pressure in that position.

This is a great point actually.. When there is a significant polar PP anomaly aligned in that way ...to extend all the way into the west Atlantic without a corresponding mass-conserved feature (lowered PP anomaly) is comparatively rarer a result.

Simply put, a big high somewhere on the map usually has a conjoined big low somewhere close by.... So in the intuitive sense you could visualize a big low somewhere in the east as a possible correction, given to a big high over MT - ND/SD areas.

Of course, this is one model run notwithstanding.

[Guest someguy]

Wawa goes as far suuth as Williamsburg, and will be in FLA soon!! : - )

thats right

Greg / analong we have WAWA the BIG fancy ones here for 8 years

the one on the coner-- in RURAL VA that means 2 miles away opended up here in the SUMmer of 2003 2 months before ISABEL came calling

for the next t 5 days they were the ONLY ones that had POWER

the Manger brought in this large board of power outlets and had then placed outside the store.... so folks could plug their cell phone chargers in for up to one hours for free to get a full charge

a very busy and popular store here in chester va

[Typhoon Tip]

This is the Heather A. signal and makes sense to actually get some sort of coastal storm in this period as the block retogrades into the C. North America. The one thing that we have to watch out for is the wavelengths being too far to the east with the trough moving into the West Coast. The damn MJO is against the snow idea, but whatever. The NAO block is clearly trumping everything else.

Interesting assertion...

The CPC has a the PNA rising toward neutral after our recent 3-4 week campage off the cliff. CDC agreement is incoherent as I was earlier outlining. Sans the latter, we may be in business with the reposition of the east Canada block as you say, but also if the former succeeds to some degree we get lowered geopotential medium in the deep S/SE, and that would open the door ( too ) for some stream phasing (polar into intermediate in a subsume event).

Buuut, let's not get ahead of ourselves

[Guest someguy]

The EUro Ensemble spaghetti plots of SLP, show much more support for a storm in the day 7-8 range.

yes they do

folks reading this thread neeed to knwo that this is real close to happening but we are NOT quite there yet

there could be a point soon where all or some of the operational Models turns very Bullish on a secs OR mecs event real soon

[Typhoon Tip]

12z GFS ensemble has a much stronger storm signal than the OP.

NICE! 999mb at 180 hours is a pretty impressively deep signal for that kind of lead.

Do you know where the spread is pointed?

[OSUmetstud]

NICE! 999mb at 180 hours is a pretty impressively deep signal for that kind of lead.

Do you know where the spread is pointed?

This just from Allan's site...I don't have access to spaghetti plots etc.

[Typhoon Tip]

This just from Allan's site...I don't have access to spaghetti plots etc.

Hm, darn it. Well, I suspect given to the SE displaced sfc depiction compared to that shading aloft, this spread may be W of that depiction. ...Speculation.

[Ender]

No - I am stating logically why this is not an interval that carries along with it a higher degree of confidence wrt extended range forecasting.

Not sure what the purpose of your pop-off is ...

I once took this awful non-Euclidean (hyperbolic) geometry class. I was a freshman at the time. It was an entirely proof based course and I was in a bit over my head. Invariably I'd receive my tests and assignments back with the note, "Correct, but inelegant". An elegant proof would have been both pithy and unique. My proofs, however, were clumsy and invariably took twice as many steps as the other student's. This was, basically, because I was stupid.

You're clearly not, but your writing can occasionally come across as a bit...complicated. Possibly to the point of requiring the reader invest operose effort in decoding your message. Perhaps even needlessly so.

[A-L-E-X]

I once took this awful non-Euclidean (hyperbolic) geometry class. I was a freshman at the time. It was an entirely proof based course and I was in a bit over my head. Invariably I'd receive my tests and assignments back with the note, "Correct, but inelegant". An elegant proof would have been both pithy and unique. My proofs, however, were clumsy and invariably took twice as many steps as the other student's. This was, basically, because I was stupid.

You're clearly not, but your writing can occasionally come across as a bit...complicated. Possibly to the point of requiring the reader invest operose effort in decoding your message. Perhaps even needlessly so.

Elegance is a good thing to have, but complicated subject matter often requires complex responses.  I think we lose quite a bit when we try to simplify.  I doubt your methods in that class had anything to do with your intelligence.  It's just how your brain works.  The problem I have with teachers of the type you mention is they are very narrowminded in what they find acceptable answers.  

[PhineasC]

Elegance is a good thing to have, but complicated subject matter often requires complex responses.  I think we lose quite a bit when we try to simplify.

Saying the models are still not in agreement and that we won't know more for a while doesn't require a complex response.

[A-L-E-X]

Saying the models are still not in agreement and that we won't know more for a while doesn't require a complex response.

Lol I know-- I wasnt talking about Tip's post in particular, but just responding to the idea that everything needs to be simplified.  I have to admit I skipped over John's post.  I'll read it now. 

[aldie 22]

yes they do

folks reading this thread neeed to knwo that this is real close to happening but we are NOT quite there yet

there could be a point soon where all or some of the operational Models turns very Bullish on a secs OR mecs event real soon

well...this was fun to read

[CoastalWx]

Some of the members are barking.

[Typhoon Tip]

Saying the models are still not in agreement and that we won't know more for a while doesn't require a complex response.

It was deeper than that - there was much more to that than a surface evaluation of model inconsistency.

No - what was really going on there is that you like nip at people and be adversarial -

[ravensrule]

Can't we all just get along before i go watch the Bungles beat the Squeelers.

[Amped]

On the 12z GGEM, look at the high pressure over montana. In the cases I have seen, they almost all the time have a high pressure in that position.

It's locked in east of the Continental Divide. It's really just dense low level arctic air causing the increase in surface pressure.