December 18-20 Potential Talking Points

[A-L-E-X]

Anything beyond 84 hours on the NAM is doesn't exist range, because it doesn't run beyond 84 hours.

See above post-- Ive seen it being used to project what goes on after the 84 hour limit.  Although that is a pretty bad idea.

[A-L-E-X]

DGEX is an extension of the NAM.

DGEX...its run on the 84hr NAM grid with some input or something from the GFS

Thanks, how accurate is it that far out?

[eduggs]

Looks like the potential is there for a good track, to me at least. Trough going negative, PV split.

Yesterday's 12Z GFS for comparison:

Nice job with this. I didn't notice your post until I mentioned the same comparison... albeit with the 102hr panel since the timing is a little off.

[Kaner587]

If the Euro looks better today, wouldn't you feel better? There's still time for trending in the right direction, at least for a moderate event.

Of course, and I said to Alex before, the variables here will make your head spin, first its the southern stream too weak, then the PV doesn't retrograde far enough west or break into two pieces, then its the energy in the plains not injecting into our southern stream s/w and who knows by tonight maybe the PV retrogrades too far west and we have an inland runner (that was a joke)

[earthlight]

Probably useless to do, but an extrapolation just using general synoptics would probably have the surface low a bit west of last nights 00z GFS.

[_AR_]

Probably useless to do, but an extrapolation just using general synoptics would probably have the surface low a bit west of last nights 00z GFS.

Just a bit?

I don't know why I'm putting this effort into the 85 hour NAM. lol. Guess I'm just bored.

[Kaner587]

Just a bit?

trough axis looks at least 100 miles further west with better PV orientation, you would think more than just a "bit" but it really isn't a big deal because in 35 minutes the 12z will have a completely different solution

[A-L-E-X]

Of course, and I said to Alex before, the variables here will make your head spin, first its the southern stream too weak, then the PV doesn't retrograde far enough west or break into two pieces, then its the energy in the plains not injecting into our southern stream s/w and who knows by tonight maybe the PV retrogrades too far west and we have an inland runner (that was a joke)

I find it really interesting though, because its a lot like quantum mechanics, except in QM all the solutions verify and all at the same time!

[Kaner587]

I find it really interesting though, because its a lot like quantum mechanics, except in QM all the solutions verify and all at the same time!

Haha yes that is true, there are some pretty good physics jokes out there wrt to QM.

Also wrt to the 84hr NAM PV orientation, it looks like its about to split even further from the more easterly placed aspect of it if this were to be extended out to 90-96 hours, and allow for the western piece to drop south and west...correct?

[SnowGoose69]

I find it really interesting though, because its a lot like quantum mechanics, except in QM all the solutions verify and all at the same time!

When you consider it all, its amazing the models even get these things within 300-400 miles at Day 5.

[bmc10]

Just a bit?

I don't know why I'm putting this effort into the 85 hour NAM. lol. Guess I'm just bored.

Most important feature I see on the 84hr 12z NAM at 500mb is the energy still dropping into the trough from the backside.

[Stormlover74]

True, yet when it's a lake cutter and we are on the warm side of the storm the GFS will nail it 7 days out and not waver. Or I guess it just seems that way since it is of little interest to us snow junkies

When you consider it all, its amazing the models even get these things within 300-400 miles at Day 5.

[A-L-E-X]

True, yet when it's a lake cutter and we are on the warm side of the storm the GFS will nail it 7 days out and not waver. Or I guess it just seems that way since it is of little interest to us snow junkies

A lot more things have to go right for us to get what we want, its probably much easier for things to go wrong.  A lakes cutter is a "strong solution" easier to see in advance because it comes from a stronger signal than a lot of other possibilities (excluding the famous triple phasers of course.) 

[SnowGoose69]

The natural tendency is for these things to just zoom offshore....any significant amplification or development into either a coastal hugger/offshore track/cutter/hybrid cutter is the rarity so yeah its alot easier when we have a pattern that prevents a cutter to just have a total miss.

[Thunder Road]

True, yet when it's a lake cutter and we are on the warm side of the storm the GFS will nail it 7 days out and not waver. Or I guess it just seems that way since it is of little interest to us snow junkies

Ding ding ding correct!

Once it looks like a rain solution, we snow weenies tend to ignore further track shifts.

Last week's Lakes-Cutter was supposed to give Detroit heavy snows at one point, yet MSP ended up being the winner.

Personally I'm getting sick of this " models-are-never-wrong-on-a-Cutter-but-always-wrong-on-a-Coastal " nonsense

[hazwoper]

In other news, the GFS gives PHL and suburbs some snow with first system

[IsentropicLift]

Very preliminary but at 36 hrs the trough in the west looks much further east at 36 hrs compared to the 06z run. Not sure how thats going to affect things.

[A-L-E-X]

The natural tendency is for these things to just zoom offshore....any significant amplification or development into either a coastal hugger/offshore track/cutter/hybrid cutter is the rarity so yeah its alot easier when we have a pattern that prevents a cutter to just have a total miss.

So a cutter or a miss can both be considered "strong solutions" because they are more likely to happen since they are more stable solutions.  Unless we get an obvious case of phasing at the right time in the "special" storms that are forecasted well in advance like Feb 1978 or March 1993.  Im leaving Jan 1996 out of it since it was first forecast to be a miss.  Dont know about PD2, but PD1 wasnt originally supposed to make it up here-- and Feb 1983 wasnt either.

Could you imagine how amazing the job was back in Feb 1978 to see that a week in advance?  And just 3 weeks after the Jan 1978 debacle?

[A-L-E-X]

 Also once in awhile we get one of those special seasons -- 1960-61, 1966-67, 1977-78, 1995-96, 2002-03, 2009-10-- that seem to have the unlikely happen much more than it "should"-- I guess the atmosphere is primed for that to happen in those years as much as years like 1972-73, 1997-98 and 2001-02 are primed to screw us. 

[Allsnow]

improvements this run...out to hr 90 as the trough trys to go neg.....i still think this will be a close to miss for i95.....but LI and SNE will take a hit

edit: jersey shore snowstorm on this run

[eduggs]

OK, the center of the canadian vortex appears to be retrograding westward by 72hr on the GFS, which could be good for the height field along the coast.

Otherwise the trof axis appears slightly further east.

[am19psu]

So a cutter or a miss can both be considered "strong solutions" because they are more likely to happen since they are more stable solutions.

I wouldn't say that. I think the cutter and miss solution sets are much larger from the perspective of someone from the I-95 corridor. I'm sure buckeye has a much different opinion about misses in the OH Valley.

[tmagan]

True, yet when it's a lake cutter and we are on the warm side of the storm the GFS will nail it 7 days out and not waver. Or I guess it just seems that way since it is of little interest to us snow junkies

That is because, for most winter storms at our latitude, the axis of heavy snow is 50-100 miles wide, very hard for any model to nail down five days in advance. When it comes to heavy rain in the warm sector, the axis is much wider, so a significant shift in low pressure track may not have any appreciable change in sensible weather.

[Allsnow]

Through hr 111 its a advisory type snow for phl-nyc.....jersey shore-li get a warnning type snow...sne is the winner

[mattinpa]

Light snow over the region from system #2. 00z and 06z had none over us.

[eduggs]

Those are pretty classic mid and upper level charts on the 12z GFS.

The surface and lower level low centers take a slightly offshore track because they develop relatively late, but it's a nice look for the coast.

[RowanBrandon]

Big improvement for the coast compared to 0z and 6z.

[Zelocita Weather]

Through hr 111 its a advisory type snow for phl-nyc.....jersey shore-li get a warnning type snow...sne is the winner

Yup, looks like a 'brush' with 1-3" W NJ, 3-5" C/E NJ, 4-6" NYC, 6" - 10" for LI.

Better than the last several runs though...

[Sundog]

This looks like the total for the region. I would say this was definitely a great direction to be moving in. half an inch from the city east. I do not think anyone of us would sneeze out 4-6 inches of snow if this was the way it verified.

[A-L-E-X]

I wouldn't say that. I think the cutter and miss solution sets are much larger from the perspective of someone from the I-95 corridor. I'm sure buckeye has a much different opinion about misses in the OH Valley.

Good point, the types of tracks that give us misses is of much greater spatial extent than what is needed to give a hit.