18z Model Guidance 12/8

[tombo82685]

FWIW the GFS @ 12z was less amplified at 500 and less potent with the mid level vort than the Euro. It also was more progressive with the energy and the movement of the storm, which is why the GFS track is along I-95 for the most part. The northern flow is pushing this along and preventing the dig that the Euro uses to fire up a bigger storm.

I'm not going to get into specific nits about this run of the GFS but I think it's important to note that the GFS was good in '08-'09 at picking up the northern stream features sooner. It may ultimately trend back a bit in the end but I don't think things will be as warm or windswept on the front end...still a rain event but probably a much colder rain and not 60 like the Euro suggests.

yea the differences between the euro and gfs are remarkable. Esp with the strength of the shortwave coming out of the west. I think wes mentioned that the euro has a problem of over amplifying the pattern. Im not sure if this is the case or what not but the euro phases that s/w very fast thus the track and right now we are in the euros bread and butter timeframe. It seems like though, the stronger the s/w the further north it is and faster ability to phase with the pv, while its the other way around for a weaker s/w.

[mattinpa]

FWIW the GFS @ 12z was less amplified at 500 and less potent with the mid level vort than the Euro. It also was more progressive with the energy and the movement of the storm, which is why the GFS track is along I-95 for the most part. The northern flow is pushing this along and preventing the dig that the Euro uses to fire up a bigger storm.

I'm not going to get into specific nits about this run of the GFS but I think it's important to note that the GFS was good in '08-'09 at picking up the northern stream features sooner. It may ultimately trend back a bit in the end but I don't think things will be as warm or windswept on the front end...still a rain event but probably a much colder rain and not 60 like the Euro suggests.

I'd lean towards some or even mostly rain in it, but I think all rain is less certain now - depends on that coastal. Tonight's Euro will be telling.

[gkrangers]

I'd lean towards some or even mostly rain in it, but I think all rain is less certain now - depends on that coastal. Tonight's Euro will be telling.

The Return of Dr. No.

[SnowGoose69]

I'd lean towards some or even mostly rain in it, but I think all rain is less certain now - depends on that coastal. Tonight's Euro will be telling.

If the 00Z GFS also is east or similar to the 18Z its a big step in the right direction...it seems the last few years these gross model differences, sometimes within as little as 3-4 days are becoming increasingly common.

[tombo82685]

If the 00Z GFS also is east or similar to the 18Z its a big step in the right direction...it seems the last few years these gross model differences, sometimes within as little as 3-4 days are becoming increasingly common.

i really want to believe this run of the 18z as credible, but something tells me its 90 percent wrong and by 0z we may be back to a depressing solution. I dunno its just you are in the euros wheel house right now, i hope im wrong, but it does help to know the ukmet is on our side.

[atownwxwatcher]

The Euro I think is having a very difficult time with the pattern. The UKMET has essentially been steady as a ship and not really changed its solutions so I think it has more credibility. So perhaps the GFS is starting to get to that UKMET type solution and this 18 Z run was the start of it...

[phlwx]

I'd lean towards some or even mostly rain in it, but I think all rain is less certain now - depends on that coastal. Tonight's Euro will be telling.

Sleet and/or Freezing rain has been in play for the front end of this event for a while. Odds don't favor a rain-to-snow scenario in SE PA based on past climo...it has happened (3/05 is one example) but more often than not when the cold air hits the rain stops. SE PA could certainly get snow showers/squalls on Monday as cold air moves in but a transition within the main shield is highly unlikely around here.

The only way to get an ideal solution would be for this thing to take a NOGAPS (or just east of that) track...good luck with that.

The Euro I think is having a very difficult time with the pattern. The UKMET has essentially been steady as a ship and not really changed its solutions so I think it has more credibility. So perhaps the GFS is starting to get to that UKMET type solution and this 18 Z run was the start of it...

It's not really having a difficult time per se...one of the causes of the Euro holding a west of everyone else track is traditional biases (energy held back, slower dip in the jet) that's causing amplification. It's been remarkably consistent the last few runs...it may very well be right but given past history and the northern stream dominance I tend to lean towards the GFS (although not specifically the 18z) side of the fence of a slower phasing and slower bombing of the low...and a track on the eastern side of the mountains.

[tombo82685]

here is the 18z dgex snowfall map, not sure how to make it smaller

[Kaner587]

Sleet and/or Freezing rain has been in play for the front end of this event for a while. Odds don't favor a rain-to-snow scenario in SE PA based on past climo...it has happened (3/05 is one example) but more often than not when the cold air hits the rain stops. SE PA could certainly get snow showers/squalls on Monday as cold air moves in but a transition within the main shield is highly unlikely around here.

The only way to get an ideal solution would be for this thing to take a NOGAPS (or just east of that) track...good luck with that.

It's not really having a difficult time per se...one of the causes of the Euro holding a west of everyone else track is traditional biases (energy held back, slower dip in the jet) that's causing amplification. It's been remarkably consistent the last few runs...it may very well be right but given past history and the northern stream dominance I tend to lean towards the GFS (although not specifically the 18z) side of the fence of a slower phasing and slower bombing of the low...and a track on the eastern side of the mountains.

thats not true...0z was way east

[phlwx]

thats not true...0z was way east

the primary was not though...it bombed a secondary much more aggressively. It wasn't "way east" with the main frontal boundary.

[tombo82685]

didnt see this posted in 12z thread but here is the ggem ens mean

[Kaner587]

the primary was not though...it bombed a secondary much more aggressively. It wasn't "way east" with the main frontal boundary.

true but the end result was drastically different...that we can agree on

[SnoSki14]

It looks like we could see a later phase which could be a lot better for us, but then again, the Euro is hundreds of miles further to the NW. We'll see what happens tonight. I'm going to assume the latest gfs is more or less a fluke, but we'll see what happens, still 4 days to go.

[Kaner587]

didnt see this posted in 12z thread but here is the ggem ens mean

another red flag for the more western solutions

[Ericjcrash]

thats not true...0z was way east

I think he meant the UK

[LetItSnowInPhilly]

With a spread this large the ENS. mean is useless for anything other than seeing just how big the spread is...

The individual members are split east and west with only a scattered couple showing anything close to the mean.

[mattinpa]

Sleet and/or Freezing rain has been in play for the front end of this event for a while. Odds don't favor a rain-to-snow scenario in SE PA based on past climo...it has happened (3/05 is one example) but more often than not when the cold air hits the rain stops. SE PA could certainly get snow showers/squalls on Monday as cold air moves in but a transition within the main shield is highly unlikely around here.

The only way to get an ideal solution would be for this thing to take a NOGAPS (or just east of that) track...good luck with that.

It's not really having a difficult time per se...one of the causes of the Euro holding a west of everyone else track is traditional biases (energy held back, slower dip in the jet) that's causing amplification. It's been remarkably consistent the last few runs...it may very well be right but given past history and the northern stream dominance I tend to lean towards the GFS (although not specifically the 18z) side of the fence of a slower phasing and slower bombing of the low...and a track on the eastern side of the mountains.

We've gotten snow in less favorable patterns than this. I still think things are up for grabs.

[Manny]

That de-amplifying of the trough is quite new, and should not be thrown out, it could be a start to finding out some new developments or differences that earlier model runs didn't take into account.

[SnoSki14]

What did the gfs ensemble means show? Does anyone have the maps for them?

[SnowGoose69]

That de-amplifying of the trough is quite new, and should not be thrown out, it could be a start to finding out some new developments or differences that earlier model runs didn't take into account.

We ultimately won't know for sure til the main disturbance which will be responsible for all that gets to the West Coast...once that happens the models solutions will probably come to some sort of agreement...be prepared, even if we see a strong consensus east tonight its possible that when that disturbance moves ashore we could see a shift back inland by all the models....one of the storms last winter did that...we saw a consensus one way at around the 72-96 hour mark and then suddenly a shift right back to the consensus seen beyond 96-120 hours...I believe it was the first February event.

[Ericjcrash]

What did the gfs ensemble means show? Does anyone have the maps for them?

Coastal.

[Manny]

We ultimately won't know for sure til the main disturbance which will be responsible for all that gets to the West Coast...once that happens the models solutions will probably come to some sort of agreement...be prepared, even if we see a strong consensus east tonight its possible that when that disturbance moves ashore we could see a shift back inland by all the models.

Yeah, definitely. I didn't mention that, as Earthlight also said, once the disturbance enters a good area for data then the models will have a better take.

[Edge Weather]

I think this will happen on Friday, right? What run do you anticipate that data will be available, 12z Friday?

We ultimately won't know for sure til the main disturbance which will be responsible for all that gets to the West Coast...once that happens the models solutions will probably come to some sort of agreement...be prepared, even if we see a strong consensus east tonight its possible that when that disturbance moves ashore we could see a shift back inland by all the models....one of the storms last winter did that...we saw a consensus one way at around the 72-96 hour mark and then suddenly a shift right back to the consensus seen beyond 96-120 hours...I believe it was the first February event.

[Sundog]

We need to disperse a few thousand buoys into the Pacific. This lack of data argument is getting tiresome.

[SnowGoose69]

I think this will happen on Friday, right? What run do you anticipate that data will be available, 12z Friday?

Yes, although it could be close enough on the 00Z Friday (Thursday night) run that it gets sampled somewhat.

[Edge Weather]

Thank you for the information.

Yes, although it could be close enough on the 00Z Friday (Thursday night) run that it gets sampled somewhat.

[hudsonvalley21]

We ultimately won't know for sure til the main disturbance which will be responsible for all that gets to the West Coast...once that happens the models solutions will probably come to some sort of agreement...be prepared, even if we see a strong consensus east tonight its possible that when that disturbance moves ashore we could see a shift back inland by all the models....one of the storms last winter did that...we saw a consensus one way at around the 72-96 hour mark and then suddenly a shift right back to the consensus seen beyond 96-120 hours...I believe it was the first February event.

I remember they were going to drop some sondes in the unreported areas in the southwest.