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Central PA - Winter 2020/2021


MAG5035
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15 minutes ago, pasnownut said:

Call me snakebit. Yeah it does historically do better w skill scores but GFS has been eeking  NW and has me a bit “on edge”. Seeing NAM CMC and euro SE of GFS is nice for sure. Hoping next few runs to see the GFS come SE a bit. 

Yes. Also, with large east coast storms the GFS is usually the most progressive/strung out/east of most models. I don't like that it's on the western edge of the envelope. (Though the operational run was way left of the mean)

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9 minutes ago, Itstrainingtime said:

Yes. Also, with large east coast storms the GFS is usually the most progressive/strung out/east of most models. I don't like that it's on the western edge of the envelope. (Though the operational run was way left of the mean)

Go parse over 3k and you’ll see 540 line NW of18z and best accums lift NW a bit. If that trend continues the gfs could be correct wrt r/s. Still really close down here. Will know soon. Nice to b tracking again. 

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@MAG5035 do you know what resolution the GEFS and EPS members are run at compared to the operational?  I have noticed that the ensemble members (of both the EPS and GEFS) are often warmer even with similar or further east tracks then the operational runs.  This has been a consistent correlation for several runs across both ensemble suits.  The track of the operationals has changed but the presentation of the thermal structure of the storm has remained fairly consistent...meaning where you expect the thermal boundaries to be wrt to mslp.  But that seems to be different on the ensembles.  I am wondering if they are run at a lower resolution...they may be warmer due to not modeling the meso scale features as well.  That may not be correct...just grasping at possible causality for the observation I noted.  

ETA:  I know back in the day the NAM would pick up on CAD better due to its higher resolution...one of the few things it was good for at range with a winter synoptic event.  You had to adjust for its over amplified bias...but you could get an idea what the thermal structure of the storm would look like.  

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34 minutes ago, CarlislePaWx said:

Yesterday I mentioned Larry Cosgrove's winter forecast which contains a bunch of analogs of waning Nina's through winter.  He gave double weight to several years which included 1995-96.  Back in December of '95 I still lived in northern NJ.  I distinctly remember a significant snowstorm just a week before Christmas.  Actually, it was December 19th and I measured 13" from that storm.  It was very cold and that kept a good chunk of the snowfall still around when the blockbuster January 6th storm hit.  That winter the snow started falling in November and didn't stop until the middle of April!  I measured 92" total snow for that record season which still stands for me as the greatest snow season of my life.  I just think it's interesting to watch things unfold in the coming weeks.

I was going to address ENSO and the pattern going forward in a post at some point and then all heck went loose with what were looking at this coming week. So far, I haven't seen any sustained signs of an imminent weakening of the Nina. Daily SOI values and 30 day average SOI has been firmly positive (positive indicates Nina state) and SST's have been relatively steady. ENSO 3.4 has warmed a tad in last weeks update but still -1.1ºC (moderate) and the SON three month average came in at -1.2ºC. Three month averages are lagged, so when December is over and the OND average can be tallied, it's likely on track for a similar value to the SON average. Obviously, this is something to consider and watch evolve as we work through Jan. 

Right now though, the big driver of this snowy week that appears to be incoming is the development of a solid negative AO/NAO regime. This is a great time for this to develop as we're early in the winter and we don't have the fully mature mid-winter pattern where the Nina can rear it's ugly side at times. And of course, good blocking in that realm is a good counter to an active Pac jet (+EPO). If we can hang onto the -NAO/AO for awhile and keep the MJO at bay (out of any higher magnitude phase 4-6), we can take an occasionally imperfect but workable pattern thru the holidays to the New Year. But we shall worry about that after Thursday or so. 

 

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2 minutes ago, MAG5035 said:

I was going to address ENSO and the pattern going forward in a post at some point and then all heck went loose with what were looking at this coming week. So far, I haven't seen any sustained signs of an imminent weakening of the Nina. Daily SOI values and 30 day average SOI has been firmly positive (positive indicates Nina state) and SST's have been relatively steady. ENSO 3.4 has warmed a tad in last weeks update but still -1.1ºC (moderate) and the SON three month average came in at -1.2ºC. Three month averages are lagged, so when December is over and the OND average can be tallied, it's likely on track for a similar value to the SON average. Obviously, this is something to consider and watch evolve as we work through Jan. 

Right now though, the big driver of this snowy week that appears to be incoming is the development of a solid negative AO/NAO regime. This is a great time for this to develop as we're early in the winter and we don't have the fully mature mid-winter pattern where the Nina can rear it's ugly side at times. And of course, good blocking in that realm is a good counter to an active Pac jet (+EPO). If we can hang onto the -NAO/AO for awhile and keep the MJO at bay (out of any higher magnitude phase 4-6), we can take an occasionally imperfect but workable pattern thru the holidays to the New Year. But we shall worry about that after Thursday or so. 

 

And even if we see values drop it doesn’t mean we flip on a dime and go full on winter.
Imo best we can hope for it low magnitude 4/5/6 or COD so that any AO/NAO opps down the line can do their thingy and let us play. 

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CTP tweeted this sobering news about Harrisburg’s last winter 

 

The last time @FlyHIA reported measurable snowfall (0.1"+) was January 18th. At midnight, the current streak of 329 days will be the longest in the period of record, surpassing 2/27/2006-1/21/2007 (328 days). Just in the nick of time before snow next week! #PAwx
h/t @ajukloABC27

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Just now, canderson said:

CTP tweeted this sobering news about Harrisburg’s last winter 

 

The last time @FlyHIA reported measurable snowfall (0.1"+) was January 18th. At midnight, the current streak of 329 days will be the longest in the period of record, surpassing 2/27/2006-1/21/2007 (328 days). Just in the nick of time before snow next week! #PAwx
h/t @ajukloABC27

It’s 2020...why not something else crazy like this!

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Just now, canderson said:

We get the good but my god central NJ is looking at a blizzard. 

That’s a good point. With the low pressure and high pressure should be some good winds I would think. I know it will change next few days but what’s the start time looking like. 
 

 

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