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Upstate Tiger

Mid to Long Term Discussion 2019

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6 minutes ago, mackerel_sky said:

GFS 18z all rain, even for N.C., I’m shocked! 

I thought you said frozen north of 40?  I’m shocked!

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38 minutes ago, mackerel_sky said:

GFS 18z all rain, even for N.C., I’m shocked! 

 

31 minutes ago, RT1980 said:

I thought you said frozen north of 40?  I’m shocked!

18z Canadian is still ice ice baby! I would lend more credence to depiction of high from Canadian. Not the easiest to dislodge low 1040s HP.

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12 minutes ago, superjames1992 said:

I think the GGEM typically overdoes low level cold.  Or at least it used to.

And I'm 100% sure it is this time also, or moving precip in way to fast...................  Unless THE KING and Goofus really change their tune! 

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22 hours ago, BIG FROSTY said:

Yes it does!

gfs_mslp_pcpn_frzn_seus_18.png

Cold rain central part of NC and looking like an ZR/IP event for WNC...we'll have to see how the models rollout this week, but that's my current prediction...but usually I'm wrong :)

 

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The latest conclusions from my North American long term outlook:

  1. After the New Year, we should see deeper cold risks per the GWO cycle for the Central and Eastern North American regions.
  2. The short term good pattern over the Eastern US will dissipate into ridging in the latter half of December. It might get more interesting in the days prior to January, with the aforementioned colder risk in Jan. This doesn’t mean there is no chance of snowfall, rather it is more limited.
  3. After the current short term Southern US snowfall risk, chances will be lower until January, or at least the last week of December.

More details here:

https://longrangesnowcenter.net/2019/12/09/north-america-on-the-long-term-9th-december/

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Looking ahead to Christmas week, the 06z GFS is currently showing a rainy (2.16") period from 12/23 through early 12/25. Another cold chasing the rain as depicted.

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For this late-week storm, I think we are seeing a general consensus forming in the models where there will be, at least during the onset, so freezing/frozen precip especially in the favored CAD areas (NW of 85). With the HP moving out to sea and limited blocking, there will not be sufficient cold air transport to sustain sub freezing temps for very long. This system, to me, looks entirely dependent on how low DP's get the evening before precip arrives and whether evap cooling can take place before the HP scoots out, losing the cold/dry source. These systems are extremely frequent here and can lead to WWA being issued. I do not see any reason to expect more than that as the colder Canadian seems to be an outlier at this time. Without a continued NE flow of cold air I do not see how sub 32 temps hang on long outside of the absolute most favored CAD regions. Even the Canadian switches wind to the NNW rather quickly.

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52 minutes ago, burrel2 said:

84hr NAM appears to be setting up a crippling ice storm. 

Nam and Canadian a dangerous combo when they show this. I put zero stock into the GFS at this juncture as it "sucks" calling a spade a spade at depicting low level cold. Friday becoming more ominous in my opinion. Yea I know its 84 hr nam but hard to discount when both computer models that have a superiority in that department spit out some of the freezing rain output. Time will tell 

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43 minutes ago, burrel2 said:

84hr NAM appears to be setting up a crippling ice storm. 

Be careful... it's really easy to be NAM'd!!  Lol   But yes, that's something to keep an eye on. Looking at the 12z NAM run, the Dew Points Thursday evening are in the mid to upper teens in NC and the Upstate of SC.  For comparison the GFS on the 6z run had dew points in the upper 20's, low 30's Thursday evening.  The 12z NAM is actually colder dew point wise than the 00z CMC at the same time frame.   

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59 minutes ago, Buddy1987 said:

Nam and Canadian a dangerous combo when they show this. I put zero stock into the GFS at this juncture as it "sucks" calling a spade a spade at depicting low level cold. Friday becoming more ominous in my opinion. Yea I know its 84 hr nam but hard to discount when both computer models that have a superiority in that department spit out some of the freezing rain output. Time will tell 

Yes but not the NAM at 84hrs I suspect.  Get it under 48hrs and in agreement with the Canadian then you might have something

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1 hour ago, burrel2 said:

84hr NAM appears to be setting up a crippling ice storm. 

Hard to tell what its going to do. Since its past 84.

But nam already looks different(GFS,CMC) from 48hrs to 84hours @ 500mb.

Almost like nam wants to phase those two pieces instead of the northern stream out running the southern piece. Like what gfs and cmc shows.nam_z500_vort_us_29.pnggfs_z500_vort_us_15.pnggem_z500_vort_us_15.png

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I'm not drinking the cool aid on this one.  I'd anticipate a cold rain based on few other models showing it.  As for the NAM, the hp looks to be sliding out to me.  One other thing, models tend to over sensationalize big ZR events from the standpoint that such heavy rates are very difficult to freeze on contact.

Just my 2 cents.

TW

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FZRA is a self-limited process anyway, so those extreme amounts are not to be taken literally..   However, the signal is something to watch for.  Doesn't take much FZRA to be a big problem.

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Timing is going to be big as usual with this type of setup. The past few days, most models were delaying the onset of precipitation till during the day Friday, and into Saturday. 

 

Just noting the early 12z data today, has shifted back to an earlier onset, Thursday evening, leading to a colder/drier airmass, and allowing for a slightly better signal for some icy concerns by Friday morning. 

 

Also, the GFS seems to become quite amped up with an inland tracking surface low up closer to the Apps, while the other guidance is indicating a low tracking further east along the coast. 

In the end, this may not matter much as the high slides out during the day, Friday leading to a narrow window of opportunity. 

Just a few thoughts to monitor in the future trends. 

B0C6CF7A-D8FA-45F6-8018-D3F49B488366.png

39C9BC8F-F6DB-46EF-802C-AFF5AFB9462D.png

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10 minutes ago, ams30721us said:

Timing is going to be big as usual with this type of setup. The past few days, most models were delaying the onset of precipitation till during the day Friday, and into Saturday. 

 

Just noting the early 12z data today, has shifted back to an earlier onset, Thursday evening, leading to a colder/drier airmass, and allowing for a slightly better signal for some icy concerns by Friday morning. 

 

Also, the GFS seems to become quite amped up with an inland tracking surface low up closer to the Apps, while the other guidance is indicating a low tracking further east along the coast. 

In the end, this may not matter much as the high slides out during the day, Friday leading to a narrow window of opportunity. 

Just a few thoughts to monitor in the future trends. 

B0C6CF7A-D8FA-45F6-8018-D3F49B488366.png

39C9BC8F-F6DB-46EF-802C-AFF5AFB9462D.png

Appreciate your input. My concern is I'm in a rock and a hard place because I could qualify per say for both SE forum and Mid Atlantic with my geography. A lot of times more of the concern in this sub forum is for Raleigh/Charlotte and I-40 and south. Dewpoints up my way are single numbers to low teens signaling this could be more than a nuisance or minor as you cross the NC/VA border with potential for prolonged icing. 

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18 minutes ago, Buddy1987 said:

Appreciate your input. My concern is I'm in a rock and a hard place because I could qualify per say for both SE forum and Mid Atlantic with my geography. A lot of times more of the concern in this sub forum is for Raleigh/Charlotte and I-40 and south. Dewpoints up my way are single numbers to low teens signaling this could be more than a nuisance or minor as you cross the NC/VA border with potential for prolonged icing. 

I would agree with you there. Salem looks to be one area I'd flag as still having the potential for a significant event here. Just because it may be more localized and fewer posters on this forum will see much of anything, it does not mean some areas could receive a significant storm. 

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10 minutes ago, NorthHillsWx said:

I would agree with you there. Salem looks to be one area I'd flag as still having the potential for a significant event here. Just because it may be more localized and fewer posters on this forum will see much of anything, it does not mean some areas could receive a significant storm. 

12z gfs trended faster and also more in line with low trajectory closer to coast then a cutter so there's that..

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ZR is self limiting without a steady CAA source. If the parent high is too transient you will see a quick end to the icing. The high in this case seems to want to move out fairly quickly.

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