Active mid December with multiple event potential

[Typhoon Tip]

This is a problematic assessment due to inherent temporal-spatial uncertainty typically found with these kind of anomalously fast, flat flows coming off the Pacific over the North American continent.  We are endowed with neutral PNA ...tho hinting at rise, while relaying into rather uncertain PNAP and whether that will feature western continental height ridge distribution, while the whole of that flow appears to 'train wreck' should these Atlantic signals continue to emerge.

The short version:  there are presently three distinct events possible in an 8-10 day span:  Monday ... Wednesday ... over next Weekend - the usual caveat emptors apply, but are enhanced by said limitations... one must be open to the notion that given said limitations any one or all three of these are subjected to change, more so than normal for this kind of threat assessment at < 10 day leads.   Case in point:

More detailed:

Monday's wave space is just beginning to tickle the denser, more physical soundings out west... I do not ( personally ...) believe that it's sudden emergence as a mere quick hitting, low totals but plausible higher impact scenario is a coincidence ( the assimilation tech is impressive and satellite sounding are hugely useful and needed, this is not a knock..) This feature's been identifiable in the stream for a few days/cycles but, we are in a low tolerance/precision mode, where nuances take proxy on determinism ...and subtle almost unobserved variances run to run can mean nothing of or grid locking commutes by cold and flashing on streets...  This system may become crucial later on ... The Euro and GGEM phase it with Canadian/N/stream rather uniquely and barring a Euro flub- up at a mere 4.5 days in advance ( which despite any popular street cred, that model is typically still good in that time range - yes it is... stop it...), that union is destined to drill an anchored hole in the cosmos in the 50/50 location as shown in the Euro example further below... 

Then, the picture gets more complex because there is now better evidence that blocking in the northern Atlantic may be real - the stochastic nature of the NAO in the guidance ... it's the least predictable/dependable index domain spaces I know of, where predictions for winters can only be made the following spring   but here... we have multi-day/multi-ensemble derivatives with more -NAO than the operational complexions that until very recently were not as prevalent in operational run ... With that onset, getting harder to ignore for me.

That latter aspect is crucial ... heading into the Wednesday time span. As Will has bothered to put this quick annotation together ( I very much agree - so have poached it from the other thread   ... ) this Euro depiction shows how a transitive "back-logging" of features across the downstream circulation ..can have an effect on pattern morphology and systems embedded as early as succeed 100W longitude coming east of the Rockies... Namely, the MV/90 W wave over midriff CONUS, for now...the most important system of the three in question:

 

But what also leaps out to me is the ridging in west is more pronounced than earlier guidance ...and I have been waiting on that piece ( personally..). It probably isn't absolutely necessary in the R-wave distribution ...since downstream blocking may factor - so less "perfect" idealized structure is needed between the E Pac and 70 W when/if the flow is force to buckle... but, having that emerge really makes this more acutely interesting for that mid week system. It's more +PNA relay and suddenly ...teleconnectors converge     The PNA is showing a tendency to rise again next week, and with an on-going -AO and these deeper SPV migrating through the PV rampart latitudes... 

Don't let the flow slow down or watch out!   This becomes a subsume phasing orgy all over the place.  For now, we favor a stormy fast reload pattern ... and watch that retrograde of the AO/NAO... and if any western ends of SPV try to dip into these Pac waves...  It's an odd overall look, to run a depressed AO index with a downward modulating NAO... and an uncertain PNA.   
 

For now, I favor ( regional relative ) low to moderate impact events in repeat strike loading ...2.5 day (~) turn over times... But, monitor that ridge spacing in the west, because if that gets a little more while that 50/50 trundles about, we end up with slower moving menace mid/late week on the EC - also out there as possibility... 

[Typhoon Tip]

Edit ...I left the GFS out but should have mentioned - I just don't think the GFS is going to handle the 'blocking' or -NAO/-AO exertion leaving N/A due to it's discerned velocity bias - it's not the tool for that gig.. I won't bring Fender electric guitar and amp to audition for a violin quartet

[512high]

11 minutes ago, Typhoon Tip said:

This is a problematic assessment due to inherent temporal-spatial uncertainty typically found with these kind of anomalously fast, flat flows coming off the Pacific over the North American continent.  We are endowed with neutral PNA ...tho hinting at rise, while relaying into rather uncertain PNAP and whether that will feature western continental height ridge distribution, while the whole of that flow appears to 'train wreck' should these Atlantic signals continue to emerge.

The short version:  there are presently three distinct events possible in an 8-10 day span:  Monday ... Wednesday ... over next Weekend - the usual caveat emptors apply, but are enhanced by said limitations... one must be open to the notion that given said limitations any one or all three of these are subjected to change, more so than normal for this kind of threat assessment at < 10 day leads.   Case in point:

More detailed:

Monday's wave space is just beginning to tickle the denser, more physical soundings out west... I do not ( personally ...) believe that it's sudden emergence as a mere quick hitting, low totals but plausible higher impact scenario is a coincidence ( the assimilation tech is impressive and satellite sounding are hugely useful and needed, this is not a knock..) This feature's been identifiable in the stream for a few days/cycles but, we are in a low tolerance/precision mode, where nuances take proxy on determinism ...and subtle almost unobserved variances run to run can mean nothing of or grid locking commutes by cold and flashing on streets...  This system may become crucial later on ... The Euro and GGEM phase it with Canadian/N/stream rather uniquely and barring a Euro flub- up at a mere 4.5 days in advance ( which despite any popular street cred, that model is typically still good in that time range - yes it is... stop it...), that union is destined to drill an anchored hole in the cosmos in the 50/50 location as shown in the Euro example further below... 

Then, the picture gets more complex because there is now better evidence that blocking in the northern Atlantic may be real - the stochastic nature of the NAO in the guidance ... it's the least predictable/dependable index domain spaces I know of, where predictions for winters can only be made the following spring   but here... we have multi-day/multi-ensemble derivatives with more -NAO than the operational complexions until very recently ... and that sort of getting harder to ignore for me.

That latter aspect is crucial ... heading into the Wednesday time span. As Will has bothered to put this quick annotation together ( I very much agree - so have poached it from the other thread   ... ) this Euro depiction shows how a transitive "back-logging" of features across the downstream circulation ..can have an effect on pattern morphology and systems embedded as early as succeed 100W longitude coming east of the Rockies... Namely, the MV/90 W wave over midriff CONUS, for now...the most important system of the three in question:

 

But what also leaps out to me is the ridging in west is more pronounced than earlier guidance ...and I have been waiting on that piece ( personally..). It probably isn't absolutely necessary in the R-wave distribution ...since downstream blocking may factor - so less "perfect" idealized structure is needed between the E Pac and 70 W when/if the flow is force to buckle... but, having that emerge really makes this more acutely interesting for that mid week system. It's more +PNA relay and suddenly ...teleconnectors converge     The PNA is showing a tendency to rise again next week, and with an on-going -AO and these deeper SPV migrating through the PV rampart latitudes... 

Don't let the flow slow down or watch out!   This becomes a subsume phasing orgy all over the place.  For now, we favor a stormy fast reload pattern ... and watch that retrograde of the AO/NAO... and if any western ends of SPV try to dip into these Pac waves...  It's an odd overall look, to run a depressed AO index with a downward modulating NAO... and an uncertain PNA.   
 

 

Maybe it was answered in the other thread Tip, If Monday happens, will it cause the next event(Wednesday ) to slide way south and mess up that larger event, or no effect? What Im trying to say if Monday arrives quick and exits, no issues for wed.?

[Typhoon Tip]

6 minutes ago, 512high said:

Maybe it was answered in the other thread Tip, If Monday happens, will it cause the next event(Wednesday ) to slide way south and mess up that larger event, or no effect? What Im trying to say if Monday arrives quick and exits, no issues for wed.?

I just wrote about all that above  

... in short -   ... the recent guidance ( save the GFS which I'm okay with given that particular guidance's bias' ) is phasing it with N/stream and really going crazy with deep anomaly over the lower Maritimes ... we call that a 50/50 when that does that... 

Yes, and that 50/50 is "plausibly" anchoring due to overarching -NAO tendencies.. But the depth of that 50/50 is unusually deep in the Euro and actually the GGEM ain't much shallower ... And that sort of in total is the same differentials.. weird - but ... that is a 'backlog' that can slow things down.  The Euro could be too deep - it has it's own bias to over z-coordinate matters in that range too - but that is a climo spot for maturation of cyclones so ...heh

It's a precarious thing... My previous lack of enthusiasm for those paying attention, was really owing to conserving the persistence/fast flow ... But given reasons to offset?  Sure...I have no problem discussing now.  Again, this is higher uncertainty too -

[MJO812]

 

[weatherwiz]

The Euro for Monday was certainly quite intriguing. When looking at Euro preicip type just at face value and how it was configured, my initial thought was we were looking at a CAD signal here...but upon further inspection it appears this could be anafrontal generated (was this discussed in the previous thread?). The structure of the ULJ would certainly support this with some favorable large-scale lift behind the passage of the front. Anyways, very interesting euro but certainly hedging with caution with this type of setup. But that 500mb look is rather intriguing too...that's a pretty potent s/w trough digging in with an impressive southern stream vort. I would presume if we could get more phasing between the two this could be a nice event for many?

[Go Kart Mozart]

Does anyone else here suffer from busted forecast dreams?  Especially when we are down to T minus one day, I dream all night that the models hve gone bad, the sun is shining brightly when I wake up, etc.

Too often these dreams come true!

[Typhoon Tip]

Just now, weatherwiz said:

The Euro for Monday was certainly quite intriguing. When looking at Euro preicip type just at face value and how it was configured, my initial thought was we were looking at a CAD signal here...but upon further inspection it appears this could be anafrontal generated (was this discussed in the previous thread?). The structure of the ULJ would certainly support this with some favorable large-scale lift behind the passage of the front. Anyways, very interesting euro but certainly hedging with caution with this type of setup. But that 500mb look is rather intriguing too...that's a pretty potent s/w trough digging in with an impressive southern stream vort. I would presume if we could get more phasing between the two this could be a nice event for many?

ANA's take place ...they are real - but ...I have come to find over the years that a larger number of those scenarios modeled, tend to actually evolve into more proper cyclone features with typical NW arcs/CCB headed frameworks ..

It's like in order for A ( no system ) to get to C ( more significant system...) ...the model passes through a couple cycles of ANA B  ?? 

That said, I'm really less intrigued about Monday as an impact here in the upper MA/NE region...and more so for how it helps in modulating the total synopsis for mid/late week - I do think that it is interesting that it is "more involved" in that regard as it is coming over land though...  Anyway, 50/50 seed

[Typhoon Tip]

10 minutes ago, MJO812 said:

 

It's like a tri-pole signature to look for - haha, call it the "junk" configuration 

[weatherwiz]

Just now, Typhoon Tip said:

ANA's take place ...they are real - but ...I have come to find over the years that a larger number of those scenarios modeled, tend to actually evolve into more proper cyclone features with typical NW arcs/CCB headed frameworks ..

It's like in order for A ( no system ) to get to C ( more significant system...) ...the model passes through a couple cycles of ANA B  ?? 

That said, I'm really less intrigued about Monday as an impact here in the upper MA/NE region...and more so for how it helps in modulating the total synopsis for mid/late week - I do think that it is interesting that it is "more involved" in that regard as it is coming over land though...  Anyway, 50/50 seed

Agreed on everything here. In fact, I would not be surprised to see Monday sort of transition to more of a cyclogeneis deal...some hints at that within the upper-level jet structure (decent signal for cyclogenesis potential right off the coast) and this could be aided depending on how the northern/stream stream interact. 

But yeah...this could definitely have some implication on the mid-week potential, especially considering how it could impact how the pattern evolves upstream of us. But all the pieces are there for mid-week...decent high, 50/50 low, but all scenarios are certainly at play (north - stronger or south - weaker). These fast flows though that provide little assistance for stronger amplification always throw wrenches into things.

[Go Kart Mozart]

NAM says no to Monday, keeps it weak sauce.

 

Edit:  That's the 12Z dumbass!!!

[78Blizzard]

22 minutes ago, Go Kart Mozart said:

NAM says no to Monday, keeps it weak sauce.

 

Edit:  That's the 12Z dumbass!!!

The 18z 32k NAM finally came out incomplete, but enough to see it was a whiff for Monday.

[JB_Wchstr]

3 minutes ago, 78Blizzard said:

The 18z 32k NAM finally came out incomplete, but enough to see it was a whiff for Monday.

Is that good or bad ultimately?

[weatherwiz]

Looks to be a quite a bit of confluence over the region though...also a decent amount of PVA...biggest inhibiting factor could be dry air, but looks like RH increases...wouldn't be surprised to see precipitation blossom for sure but I don't think this is really much of a winter threat (accumulating wise anyways)

[PWMan]

GYX decidedly meh for snow chances up this way next week - going with cold and dry for now. Guess I'll enjoy my remaining parches of crust and see how things evolve.

[78Blizzard]

5 minutes ago, SnowEMass said:

Is that good or bad ultimately?

I wouldn't put any stock into it, since it is the NAM at 72+ hrs, and the 32K at that, lol.

[tamarack]

6 minutes ago, PWMan said:

GYX decidedly meh for snow chances up this way next week - going with cold and dry for now. Guess I'll enjoy my remaining parches of crust and see how things evolve.

Agree. Haven't seen 18z but 12z had maybe 0.2" of mess tomorrow night then nothing until a day 10 Grinch.

[SnowGoose69]

26 minutes ago, 78Blizzard said:

The 18z 32k NAM finally came out incomplete, but enough to see it was a whiff for Monday.

The ICON at 18Z moved NW.  I still think this is coming west.  Maybe not to the degree the Op Euro was though 

[78Blizzard]

RGEM closer but warm.

[WinterWolf]

8 minutes ago, SnowGoose69 said:

The ICON at 18Z moved NW.  I still think this is coming west.  Maybe not to the degree the Op Euro was though 

Ok...this is the problem with talking about multiple threats in the same thread, which threat are you talking about here? Monday? Or Wednesday? 

[MJO812]

3 minutes ago, WinterWolf said:

Ok...this is the problem with talking about multiple threats in the same thread, which threat are you talking about here? Monday? Or Wednesday? 

Monday

[MJO812]

Congrats James 

[RUNNAWAYICEBERG]

70/30 eps/gefs blend would work.

[TauntonBlizzard2013]

Pretty remarkable consistency on the gfs from 12z to 18z.... crushes Boston providence and points southeast 

[RUNNAWAYICEBERG]

I thought weenie Tip was starting the main event storm thread?

[WinterWolf]

That’s still 4-6” here on the GFS lol.and 8 for you Anthony. .I’d take that. 

[Chrisrotary12]

I like how active the GFS op run is. Slightly worried about Wednesday's drifting away from us. GEFS & EPS look like they shifted southeast (can only EPS in 24 hr intervals). Definitely need watching.

[RUNNAWAYICEBERG]

2 minutes ago, Chrisrotary12 said:

I like how active the GFS op run is. Slightly worried about Wednesday's drifting away from us. GEFS & EPS look like they shifted southeast (can only EPS in 24 hr intervals). Definitely need watching.

I agree. The SE graze is real. 

[HIPPYVALLEY]

6 minutes ago, Chrisrotary12 said:

I like how active the GFS op run is. Slightly worried about Wednesday's drifting away from us. GEFS & EPS look like they shifted southeast (can only EPS in 24 hr intervals). Definitely need watching.

The one thing we obviously don’t want is whiff, scrape, cutter but it would have to be a pretty wound up SW to cut in the 7-10 day range.  Nice looking pattern,  someone on the East Coast is getting snow It just doesn’t necessarily have to be New England.
 

[CoastalWx]

I don’t think there is much of a chance for a SE drift. That s/w on the euro is a beast. That has a good chance of tugging the low a little NW on guidance.