Outside shot at seasons first synoptic snow, D4-6

[Typhoon Tip]

It's nice as a weather forecast to know that the canvas for particular event types (teleconnector spread) actually supports the operational model types, and this time .. .they most certainly do! 

 

Caveat emptor:  It is before November 1st ... could be a "cat's paw" event for most below 1,000 or so feet.   I would also like to note that we have seen/encountered reports of snowfall in October 8 or 9 times out of the last 12 years.  That, in its self, is pretty impressive statistical anomaly, with roots/discussion suited for another time; but sufficed it is to say, it is no longer unworldly to discuss the S word prior to Hallow's Eve.     This is an outside chance for wider spread ... but it is more likely that an interval of harshness takes place with at least the elevations have flakes in the air.

 

Pattern:  We are about to enter a positive pulse in the +PNAP pattern.  This does appear to be a PNAP construct that is keyed into the positive phase of the PNA.  It really is on a hemispheric scale a favored outcome, to having the AA phase of the Pacific being usurped along by huge latent heat dosing from multiple west Pacific TC entering the westerlies NE of Japan.  There is even some suggestion of an EPO ridge hinted for down the road ... but let's not get ahead of our self.  

 

The NAO domain is interesting.. It is predicted to slip into a nadir over the next 7 to 10 days, and we see in some of the more dependable operational guidance types ... a tendency to cool the 850mb medium over the E and SE Canadian shield prior to the happening.  That kind of time is intriguing as it loads available, albeit marginal as modeled at this time, eventually down into the OV and NE states, upon the exit of the next trough amplitude scheduled post the one we are encountering now... 850mb temperature go beneath 0C by late D4, and with the +PNAP in place immediatley thereafter, this is not appearing to be a jolt modifier scenario where it's back up to 70 two days later, either. 

 

Low and behold, every operational model upon the 00z run depicts a Clipper impulse cutting SE out of Alberta/Manitoba entering D4 .. This feature and it's slowly intensifying SFC wave is forecast to eventually pass S of us as a weak to moderate NJ model low... There after, it get's interesting as most guidance also agree on some sort of closure aloft... capturing the low and throwing back some CCB or Cold Conveyor activity into the area (whether depicted outright, that interpretation is valid given the synoptic appeal.)  

 

Outside shot due to the time of year and thermal constraints.  If this were a month from now, I'd be willing to up the stakes and call for a actual storm.   Trend isn't finished... 

[Typhoon Tip]

12z GFS even more impressive with this signal, but not yet cold enough outside of the Mt.  It's showing a very robust jet wind max cutting SE out of the lower Lakes early D5  ... closing off a couple of contours in the mid levels into D6 though, so a Nor'easter would result there.

 

As is ... 850mb temperatures cold plume moderates through the period ... but this far out details from dynamical feed-backs and other aspect of actual baroclinic tapestry probably not hugely refined...  

 

Still banking on a cold rain but outside shot still in the cards. 

[Damage In Tolland]

Johnny,, I advise you to be careful. I discussed possible snow in new Eng yesterday and was laughed at, chastised and asked by a mod to "Please Stop"

[CoastalWx]

It looks like it's just too warm below 825mb  or so. Just as it closes off, it injects warmer 850 air.

[powderfreak]

Where's my Cirrus T-shirt....60-hour precip total on the 12z GFS.

 

[ORH_wxman]

I don't see it...unless we cool 2-3C in the mid-levels.

[Typhoon Tip]

Where's my Cirrus T-shirt....60-hour precip total on the 12z GFS.

 

gfs_namer_192_precip_p60.gif

 

Pretty goodly nor-easter there, one way or the other  ... and we once up at UML noted coastal correlation exist between October/November and DJF.  Like- able trend for winter enthusiasts...? perhaps -

 

Also, the title of "outside chance"   ... tho imho the chance is not zero; and I would not have bothered to start this if there were not governing signals in support, which there are.  Obviously "as is" it is too warm in critical thickness depths -- that would need to be modified in future runs...  The operational Euro has been cooler than the GFS for this interval of time.  So has the GGEM (tho that model is kind of dead to me at this time)

[Typhoon Tip]

And so as it were an "outside" shot appears reduced to "no shot" ... though I'd argue that with a such a large gyre now modeled, NW fringes at elevation may seem some kind of mixing prior to the column normalizing.   

 

A month from now this set up produces.  Though this particular go of it will be a mere cool, very wet Nor Easter for most (should it all go down as depicted by the mean), it's a winter construct nonetheless.   Trough amplitude delivers a cold insert, which takes place over the next 24 to 36 hours, then the next S/W amplifies up underneath. It is a reasonable comparison to the Kocin/Ucellini model.