0Z Guidance Discussion 12/21/2010

[Blizzard-on-GFS]

You can never forecast blizzard conditions five and a half days out.

But it is certainly possibly. ACY appears to get hit hardest at the moment.

[Confuzzled]

Thanks for the responses to my question! I appreciate it!

I have one more:

144 hr Euro from meteocentre has a 984mb L but the image I posted from Allan's site from the 144hr Euro had the storm bombing out much more:

Why the difference? (aka what am I doing wrong?)

The only difference I notice in the descriptions on the maps is the second one does not say "mean SLP".

[A-L-E-X]

Beautiful eclipse here on the NC coast.

The moon is dark creamy white/orange/red.

Thanks for the reminder!

Yes-- t0tality lasts 72 min so enjoy this til about 4 am!

First winter solstice total lunar eclipse in 400 years.

It's also live on this site:

http://www.huffingtonpost.com/2010/12/21/lunar-eclipse-2010-live-s_n_799517.html

[SnowGoose69]

I seriously think the ECM is paltry on QPF compared to the strength of this system....with the low pressure and captured H5 trough, we're probably talking about 2" QPF for PHL/NYC/SE NY/LI/CT/NJ....I think this is basically a January 1996 solution with huge QPF and amazing ratios due to the 1036mb high pressing in from the Midwest. Finally a true blizzard if this comes close to verifying.

It always is, its QPF amounts for the December 09 event were low as well...this QPF amounts on models I think are best in the 2-3 day range from an event, outside of that they tend to run too low, especially on the larger gridded models and inside of 36-48 hours they often become grossly overdone, especially on the NAM. I almost always look back at the 36-42 hour runs to see what the most likely QPF is, assuming the general track was the same at that range, generally you don't have too much deviation.

[winter_warlock]

from hpc this morning...

THE ECMWF TRACK OF THE EAST COAST CYCLONE WOULD HAVE HIGH IMPACT

OVER THE HOLIDAY WEEKEND ALONG AND EAST OF THE INTERSTATE 95

CORRIDOR FROM WASHINGTON TO BOSTON. OF PARTICULAR CONCERN IS THE

SLOW CRAWL OF THE MATURE STORM TOWARD THE ATLANTIC BENCHMARK SOUTH

OF LONG ISLAND THE DAY OR TWO AFTER CHRISTMAS. THIS PHASE OF THE

STORM WOULD COME ABOUT ONLY IF THE MID LEVEL TROUGH IS ABLE TO

CLOSE OFF...WHICH IS ENTIRELY POSSIBLE IN THE STRONG BLOCKING

REGIME. WILL MANUALLY MOVE THE CENTER ALONG SLIGHTLY FASTER LATE

DAY 6 INTO DAY 7 THAN THE RAW ECMWF RUN WOULD INDICATE...BASED ON

THE WEIGHT OF THE ENSEMBLES AND OTHER DETERMINISTIC MODELS

[Voyager]

Not me, I'd be pretty upset if it happened while folks who didn't get dryslotted get 2 ft plus.

That's not a whole lot different than having a tight gradient and getting 2-4 inches while places 75 miles away get 15-20.

[brooklynwx]

Just got done looking at the 00z GFS ensembles. There are 12 members 5 have a hit for New England, 3 have a glancing blow and 4 have a complete miss with just an impressive ocean storm. This disparity should be expected on a model run 132 hours out but before I jump into the deep end feet first and go shouting from the roof tops that a Nor'easter is coming on one of the busiest travel days of the year I need a little more agreement. I know the EURO operational and ensemble mean also show a hit. I just don't have access to the 50 member of the Euro ensembles to compare. Wish I did!

[U_Thant]

Most of SE, excluding FL and southern GA likes this run, as the 12z one, and last nights 0z cause the Euro has been the hammer on down south

Actually, if you're in FL, like me, and you like SVR, then you also like this run of the ECM since it's surface low position is far enough south to result in a decent low/mid level wind/shear profile. This could bring a squall line passage (unusual for a Nina of this strength) if there is enough low level moisture return ahead of the system - a HUGE if considering the unusually cold SSTs and dry land surface.

[ptb127]

Not much easterly component from the Atlantic at 500mb to drive moisture inland initially, and the whole storm not being a true mature Noreaster until it's up past the Delmarva.

Tombo's QPF map has .75-1" for a large area... not too bad considering the ratios will be higher.

[winter_warlock]

Just got done looking at the 00z GFS ensembles. There are 12 members 5 have a hit for New England, 3 have a glancing blow and 4 have a complete miss with just an impressive ocean storm. This disparity should be expected on a model run 132 hours out but before I jump into the deep end feet first and go shouting from the roof tops that a Nor'easter is coming on one of the busiest travel days of the year I need a little more agreement. I know the EURO operational and ensemble mean also show a hit. I just don't have access to the 50 member of the Euro ensembles to compare. Wish I did!

heres the euro ensemble mean...

[mdsnowlover]

Just got done looking at the 00z GFS ensembles. There are 12 members 5 have a hit for New England, 3 have a glancing blow and 4 have a complete miss with just an impressive ocean storm. This disparity should be expected on a model run 132 hours out but before I jump into the deep end feet first and go shouting from the roof tops that a Nor'easter is coming on one of the busiest travel days of the year I need a little more agreement. I know the EURO operational and ensemble mean also show a hit. I just don't have access to the 50 member of the Euro ensembles to compare. Wish I did!

honestly, If I were in your shoes, I wouldn't either!!If this holds, thru tomorrow morning, I would expect the local tv and radio stations to start advertising this storm to the general public by wed pm or thursday am. Dont you think so??

[SteveB]

Maybe it's just me, but we still have some models as well as individual ens members from both the GFS and EURO suggesting this could sit just far enough off the coast to be more of a glancing blow than a major hit.

With each successive run seeming to come in farther South with the SLP, this is putting up a big red flag. Until we start to hone in on something closer to the coast, we can't automatically assume because the 0Z EURO / 0Z GGEM say big hit that this will in fact verify.

Hoping for more model support today, but we're 0 for 1 so far with the GFS being far enough OTS to be a glancing blow for most (save extreme coastal areas). For sake of sanity, it's only the 6Z GFS so wouldn't woory 'too' much yet.

[SteveB]

I agree that there'd be a sharp cut-off to the precip field as a very intense low pressure tends to have banding pretty tight to the low center. But I still think the QPF within the deformation band will increase if the models hold this solution...there's definitely going to be more areas with 1.5"-2.0" than shown verbatim with a low bombing from 980s to 960s very close to the coast. I think NYC would approach 2 feet of snow if the ECM verified.

Also, I think the Atlantic low is acting like a 50/50 and giving us the blocking we need...it doesn't look suppressive to me. My biggest worry with this storm is that the surface low will move slightly more quickly from west to east, allowing it to escape before the potent northern stream energy phases in completely and allows for the H5 capture.

BINGO!

[brooklynwx]

honestly, If I were in your shoes, I wouldn't either!!If this holds, thru tomorrow morning, I would expect the local tv and radio stations to start advertising this storm to the general public by wed pm or thursday am. Dont you think so??

The biggest problem for TV mets with this storm isn't talking about "what could happen", Its trying to get the producers of the shows not to buy into the hype machine that is already moving full speeed ahead. The week before x-mas is notoriously slow in the news world and just the chance of a big storm during a slow news cycle gives the producers a big lead story. Its a battle that tv mets play all the time. The NBC Today Show just did a special map on it 5 days in advance and I'm sure the Weather Channel will be right behind. When the national news does this it doesn't give the local mets much of choice. You have to start talking about something that could easily burn you in the end.

[bates]

The biggest problem for TV mets with this storm isn't talking about "what could happen", Its trying to get the producers of the shows not to buy into the hype machine that is already moving full speeed ahead. The week before x-mas is notoriously slow in the news world and just the chance of a big storm during a slow news cycle gives the producers a big lead story. Its a battle that tv mets play all the time. The NBC Today Show just did a special map on it 5 days in advance and I'm sure the Weather Channel will be right behind. When the national news does this it doesn't give the local mets much of choice. You have to start talking about something that could easily burn you in the end.

Hence, the reason that the general public wrongly believes the forecasts repeatedly bust. A storm on modeling 5+ days out is no forecast, yet the discussion mill and hype by some goes into full swing, gets to the gereral public either by way of some private concerns or the media, and when the real forecasts eventually say no storm and none happens, it's too late as people say "forecast bust again". Tough to win in this game.

[Analog96]

Maybe it's just me, but we still have some models as well as individual ens members from both the GFS and EURO suggesting this could sit just far enough off the coast to be more of a glancing blow than a major hit.

With each successive run seeming to come in farther South with the SLP, this is putting up a big red flag. Until we start to hone in on something closer to the coast, we can't automatically assume because the 0Z EURO / 0Z GGEM say big hit that this will in fact verify.

Hoping for more model support today, but we're 0 for 1 so far with the GFS being far enough OTS to be a glancing blow for most (save extreme coastal areas). For sake of sanity, it's only the 6Z GFS so wouldn't woory 'too' much yet.

What shifted south other than the 06Z GFS? The GGEM came West, the ECMWF came West, the UKMET held serve.

[KEITH L.I]

What shifted south other than the 06Z GFS? The GGEM came West, the ECMWF came West, the UKMET held serve.

I think he's worried about the members of the GFS ensembles..which most have shown an OTS solution..should we really look at these?..when I see them i get a little worried..I think only 4 out of 12 had a hit

[Analog96]

I think he's worried about the members of the GFS ensembles..which most have shown an OTS solution..should we really look at these?..when I see them i get a little worried..I think only 4 out of 12 had a hit

The GFS ensembles are basically inferior runs of the GFS model.

[A-L-E-X]

The biggest problem for TV mets with this storm isn't talking about "what could happen", Its trying to get the producers of the shows not to buy into the hype machine that is already moving full speeed ahead. The week before x-mas is notoriously slow in the news world and just the chance of a big storm during a slow news cycle gives the producers a big lead story. Its a battle that tv mets play all the time. The NBC Today Show just did a special map on it 5 days in advance and I'm sure the Weather Channel will be right behind. When the national news does this it doesn't give the local mets much of choice. You have to start talking about something that could easily burn you in the end.

yes, TWC just asked its viewers to play a game and join either "Team GFS" or "Team EURO" I kid you not-- that's exactly what they said! They even showed a wide swath of about 6-12" of snow from DC to Boston ("TEAM EURO") and 6-12" from Philly to NYC ("TEAM GFS")... and they said if youre from the south and want snow you need to join "Team Euro" -- the stupifying of weather broadcasts is getting ludicrous.

They also just issued a three month forecast (Jan-Mar) and said the south will be mild, the NW and upper MW will be cold and the MA, NE and the center of the country will be closer to average. Typical.....

[NattyBo]

yes, TWC just asked its viewers to play a game and join either "Team GFS" or "Team EURO" I kid you not-- that's exactly what they said! They even showed a wide swath of about 6-12" of snow from DC to Boston ("TEAM EURO") and 6-12" from Philly to NYC ("TEAM GFS")... and they said if youre from the south and want snow you need to join "Team Euro" -- the stupifying of weather broadcasts is getting ludicrous.

Everything aside, I find that kind of funny actually.

*goes back to lurking*

[KEITH L.I]

The GFS ensembles are basically inferior runs of the GFS model.

true,,Saturday morning about half of the members had snow on the Island from Sunday's miss, where the Op had it 300 miles off shore..and that was 24 hours away!..lol

[Analog96]

true,,Saturday morning about half of the members had snow on the Island from Sunday's miss, where the Op had it 300 miles off shore..and that was 24 hours away!..lol

If the individual ensemble members were any good, they would BE the op!

[Feb]

I think he's worried about the members of the GFS ensembles..which most have shown an OTS solution..should we really look at these?..when I see them i get a little worried..I think only 4 out of 12 had a hit

Garbage in, garbage out. As DT has already said, he doesn't look at the GFS until 84 hours when it comes to ECST.

[KEITH L.I]

I don't know..alright no big deal

[SteveB]

I think he's worried about the members of the GFS ensembles..which most have shown an OTS solution..should we really look at these?..when I see them i get a little worried..I think only 4 out of 12 had a hit

Sort of....

I saw the UKIE and the NGP as well.

[Tiburon]

The GFS ensembles are basically inferior runs of the GFS model.

Wow. THAT'S really saying something.

yes, TWC just asked its viewers to play a game and join either "Team GFS" or "Team EURO" I kid you not-- that's exactly what they said! They even showed a wide swath of about 6-12" of snow from DC to Boston ("TEAM EURO") and 6-12" from Philly to NYC ("TEAM GFS")... and they said if youre from the south and want snow you need to join "Team Euro" -- the stupifying of weather broadcasts is getting ludicrous.

They also just issued a three month forecast (Jan-Mar) and said the south will be mild, the NW and upper MW will be cold and the MA, NE and the center of the country will be closer to average. Typical.....

If it wasn't for Stephanie Abrams and Cantore, TWC would NEVER be worth watching.

But I'm team EURO all the way...

[Analog96]

Sort of....

I saw the UKIE and the NGP as well.

NGP should not be on ANY list of models, PERIOD! The UKMET was the ONLY model consistently showing our area getting some snow/ice on 12/13. We all know how well that one turned out.

[OSUmetstud]

NGP should not be on ANY list of models, PERIOD! The UKMET was the ONLY model consistently showing our area getting some snow/ice on 12/13. We all know how well that one turned out.

It's second in verification...sorry dude.

[ohleary]

The GFS ensembles are basically inferior runs of the GFS model.

Dismissing the GFS ensembles as "inferior runs of the GFS model" is incorrect, and doing a disservice to members who don't know any better. Furthermore, looking at details of individual members of ensembles isn't really the point, from my understanding. In any ensemble run, you can find a member whose solution you like and one you don't like. My understanding is that ensembles are most useful to judge the uncertainty in the control/op forecast, and to look for model consensus within one model itself. Not to say this member is right, this one is wrong, etc. A good starter for understanding ensemble modeling:

http://www.hpc.ncep.noaa.gov/ensembletraining/

[A-L-E-X]

Dismissing the GFS ensembles as "inferior runs of the GFS model" is incorrect, and doing a disservice to members who don't know any better. Furthermore, looking at details of individual members of ensembles isn't really the point, from my understanding. In any ensemble run, you can find a member whose solution you like and one you don't like. My understanding is that ensembles are most useful to judge the uncertainty in the control/op forecast, and to look for model consensus within one model itself. Not to say this member is right, this one is wrong, etc. A good starter for understanding ensemble modeling:

http://www.hpc.ncep....sembletraining/

The best thing about ensembles is that (as a collection, not individually) they do a fair representation of the variability of the atmosphere, something that any single model cannot match. Isolating them individually really isnt the point of using them-- basically (as you said) their primary function is to see where future runs of the model might go, as well as testing the self consistency of the OP. In short, the "fragility" of a given OP run can be tested by the consensus of the ensembles. I find them fascinating because they offer an "inside look" at how the model works and what a little change in a given short wave or polar vortex (for example) will have in terms of downstream implications. As I have said before, I look at them like a very abridged version of a quantum probability chart

I hope when we incorporate parallel processing to a greater degree that we'll be able to add many more ensembles and thus refine our forecasting methods even further.