December 8-10, 2018 Winter Storm

[mckinnonwg]

1 minute ago, CADEffect said:

No sir, I have not. Would it be different then what the overall model predicts?

It's possible based on the algorithms used to define the contours.  The soundings will give you the exact dew temp at climbing levels and may show you something different.  But maybe not.  Just one method of verification.

[CentralNC]

Just feels to me (maybe my old bones) that this is trending south for highest amounts for snow.  The "finger" on radar seems more W-E instead of NE and it is below my latitude.

[mackerel_sky]

7 minutes ago, burgertime said:

Gut tells me the 12z suite is gonna get back to glory. 

That’s a lot of glory already in that WOW map!

[griteater]

15 minutes ago, wake4est said:

Anybody have soundings across NC from the 6z Euro? Precip looks perfect for much of the state if all snow. I wonder how much is sleet.

Can’t post the map right now but 06z precip type / temperatures didn’t really change from the one I posted late last night, but the precip shield ticked south and amounts went up across the upstate and southern foothills/piedmont where it has 2.5 to 3.0 storm total liquid

[Poimen]

SREF mean qpf is about 1.75" for GSO. Snow mean not all that impressive, but I'm thinking we might see a juicy NAM run upcoming in respects to qpf. 

[Wow]

Just now, CentralNC said:

Just feels to me (maybe my old bones) that this is trending south for highest amounts for snow.  The "finger" on radar seems more W-E instead of NE and it is below my latitude.

The "finger" means more about trajectory then amounts IMO.  I'd prefer to see it south and more west to east.  That tells me more suppressed (not necessarily weaker!) and less worry about WAA.

 

[ILMRoss]

WRAL snowfall map - seems bullish to me
 

All I’m going to say is, Fish loves ensembles, and Fish loves certainty, and the ironclad nature of 1 inch + totals on the ensembles have probably weighed on that team.

[CADEffect]

Another quick question at this point in the game do you start looking at the precipitation field more in short term models are continue to watch the op models?

[DopplerWx]

i hate it but the wsp disco about the waa being less of a factor than normal due to easterly winds vs SE winds has my hopes up a bit more for clt.  the fv3 and euro match up perfectly with the snow line below the state line but the rgem and nam continue to show it well to our north.  if we could just get them to shift south i would feel much better about the 3-5" the NWS is calling for.

[Jet Stream Rider]

Impressive amount of moisture coming in off the Pacific into the southwest and feeding into our system as it begins to get organized. Once the vortex moves east and begins to tap the GoM, it looks to be substantial. The early finger is further east and south than I anticipated this morning.

https://weather.cod.edu/satrad/exper/?parms=continental-conus-14-48-1-100-1&checked=map&colorbar=undefined

[SnowNiner]

Seems like great south/cooler trends last night.  I think it's all going to come down to that warm nose, and can the top down cooling fight it off.  That's the difference between just getting the front end thump (6 hours maybe?) and getting the whole storm mostly snow.  WPC is on record saying the warm nose shouldn't be too bad as the winds are coming from the east, not southeast.  I'm guessing that's due to the 850 low being to our south (wish it was further south).  I think the FV3 shows the best case scenerio where the top down cooling keeps the mild warm nose at bay throughout.  The other models just don't yet, but seem to do it more last night.  Hopefully today's runs makes the cooler trend.  Very interested today to see how the RGEM handles the storm.  

[Casualbrain]

Just now, CADEffect said:

Another quick question at this point in the game do you start looking at the precipitation field more in short term models are continue to watch the op models?

I start trusting the short-term operational models 48 hours before an event - but the art of forecasting is in comparing the numerical models/ensemble models, soundings (actual balloon launches), and historical events to obtain your best guess.  24 hours out is usually a "lock" with the models as there is more real/actual atmospheric data and the cone of uncertainty narrows considerably.  That said ALL models have busted at one time or another.

[CentralNC]

2 minutes ago, Jet Stream Rider said:

Impressive amount of moisture coming in off the Pacific into the southwest and feeding into our system as it begins to get organized. Once the vortex moves east and begins to tap the GoM, it looks to be substantial. The early finger is further east and south than I anticipated this morning.

https://weather.cod.edu/satrad/exper/?parms=continental-conus-14-48-1-100-1&checked=map&colorbar=undefined

Yeah I think there are going to be some hearts broken in the MA forum.

[burrel2]

I honestly can't decide what it's going to do in the northern upstate. I think the most logical outcome is mostly cold rain, but there's definitely a chance we could get buried.  I'll remain cautiously optimistic, but expect 1 inch of sleet accumulation for my storm total.

If that lead finger of precip could be mostly snow for us, we could really rack up. It appears the mid-levels will be borderline cold enough for the finger... but surface temps are around 35-37. If the mid-levels are cold enough, i imagine we could cool the surface down to 32-33 with heavy rates inside the finger.

Regardless, the mountains on the NC/SC border are going to get obliterated, both by the lead finger and the main storm. I'm calling the jackpot for the storm as somewhere around rosman/brevard with a total of 20 inches.

 

 

 

 

 

[packfan98]

14 minutes ago, griteater said:

Can’t post the map right now but 06z precip type / temperatures didn’t really change from the one I posted late last night, but the precip shield ticked south and amounts went up across the upstate and southern foothills/piedmont where it has 2.5 to 3.0 storm total liquid

Grit, I was wondering what the 6z euro looked like as far as the mixing line on Sunday afternoon.  I know that the 0z seemed to scour out the cold temps pretty fast and even showed rain as far NW as the Triad.  Did the 6z improve any?  Many thanks for your analysis and contributions for this storm!

[griteater]

Just now, packfan98 said:

Grit, I was wondering what the 6z euro looked like as far as the mixing line on Sunday afternoon.  I know that the 0z seemed to scour out the cold temps pretty fast and even showed rain as far NW as the Triad.  Did the 6z improve any?  Many thanks for your analysis and contributions for this storm!

Thank you. If looked very similar with the mid level warmth moving in / overall temps

[mckinnonwg]

11 minutes ago, CADEffect said:

Another quick question at this point in the game do you start looking at the precipitation field more in short term models are continue to watch the op models?

personally, I focus on the short term at this point.

[beanskip]

As 12z NAM gets rolling, through 15 hours, at 500mb, it's holding back the southern stream energy a bit -- and it also looks stronger. 

[ILMRoss]

Something I’d watch out for in this next suite is cyclogenesis along the Atlantic- so far not a single global has represented this well to my eye. The mesoscale models look more believable. Here’s what I mean:

Cyclogenesis is favored to occur in areas where there’s already a distinct low level vorticity axis (think: frontal boundary! “Low level vorticity axis” sounds like an intimidating weather term but it’s really just represents a wind shift!)

In CAD regimes, there’s always a super distinct axis just off the coast between the CAD Airmass and the coastal front. Thus, as that area has some lift imparted on it, you’d expect pressures to drop and cyclogenesis to initiate.

The globals don’t show this. Here’s the GFS: it has not signature along the Gulf Stream at all... and I’m not sure I buy that. Here is the nam in comparison at the same time:

In the nam, there’s a much more distinct signature of this taking affect, and this represents what “supposed” to occur in this scenario. I think this is helping toss everything more northward in the NAM.

Now, obviously, meteorology doesn’t always bend towards what’s “supposed” to happen, as any seasoned weather enthusiast knows. That being said, I wouldn’t be surprised to see a “CAM vs Global” battle emerge today as more CAMs get in range. Lastly- CAM = convection allowing model- think NAM, RGEM, HRRR, etc. They don’t have to parametize convection with their higher resolution.


.

[DopplerWx]

where can you find the 06z/18z euro runs on wxbell, I can't seem to find it?

[BornAgain13]

You guys in the Carolina's are looking good... as for me on the border in VA, the QPF keeps heading south... at this point , the storm looks very minimal here... even though the NWS has us getting 12" still

[jjwxman]

NAM definitely trended south with the higher snowfall totals since 18z yesterday. Here's Thursday's 18z and this morning's 06z run.  

[Thor]

Looks a bit colder with 850s and DPs on the 12z NAM so far

[beanskip]

Also, nice improvement in 850 temps over NC at 21 hours vs. 6z run -- sunk down over NC/SC line on the 12z -- hadn't made it that far on prior run. 

[wncsnow]

NAM is not gonna be as suppressed as some other globals

[DopplerWx]

out to 26 and nam looks colder, snow line right over clt and points west.

[CentralNC]

3 minutes ago, ILMRoss said:

Something I’d watch out for in this next suite is cyclogenesis along the Atlantic- so far not a single global has represented this well to my eye. The mesoscale models look more believable. Here’s what I mean:

Cyclogenesis is favored to occur in areas where there’s already a distinct low level vorticity axis (think: frontal boundary! “Low level vorticity axis” sounds like an intimidating weather term but it’s really just represents a wind shift!)

In CAD regimes, there’s always a super distinct axis just off the coast between the CAD Airmass and the coastal front. Thus, as that area has some lift imparted on it, you’d expect pressures to drop and cyclogenesis to initiate.

The globals don’t show this. Here’s the GFS: it has not signature along the Gulf Stream at all... and I’m not sure I buy that. Here is the nam in comparison at the same time:

In the nam, there’s a much more distinct signature of this taking affect, and this represents what “supposed” to occur in this scenario. I think this is helping toss everything more northward in the NAM.

Now, obviously, meteorology doesn’t always bend towards what’s “supposed” to happen, as any seasoned weather enthusiast knows. That being said, I wouldn’t be surprised to see a “CAM vs Global” battle emerge today as more CAMs get in range. Lastly- CAM = convection allowing model- think NAM, RGEM, HRRR, etc. They don’t have to parametize convection with their higher resolution.


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In his blog Crankywxguy talks about this being an elongated Low and less consolidated.  Interesting.  Thanks for the insights!

[Steven_1974]

36 minutes ago, SnowDawg said:

Cranky weather guy from twitter mentioned this in his blog yesterday saying that the storm was late to bloom but not late to track. Basically that what was happening out west wouldn’t translate directly to the east coast and in fact he said there might be an inverse reaction where things are wetter over here than expected. But things went south over there not because of more suppression or the low forming way south, but simply because cyclogenesis was later than initially modeled.

Just FYI, Cranky Weather Guy isn't a meteorologist so take anything they say with a grain of salt. It's been pointed out on this forum before how off base they've been.

[Thor]

Pretty amazing wall the moisture is hitting on 12z nam

[RTPGiants]

NAM also looks a bit faster in that precip in southern NC by noon tomorrow.