January 25/26 Jimbo Back Surgery Storm

[Tyler Penland]

1 minute ago, BooneWX said:

Because weather apps are based on nothing we in this group value: precedence, analogs, multiple data points and human input. It’s why I hate that any of these apps bother. All it does is mislead the public. 

The Accuweather one still had me getting 8-12" of snow yesterday evening- that hasn't been on the table for days. 

[Blue Ridge]

Nice little IP burst as I left for the office this morning. Surely if we can get IP at 42F, we can get it at 26F. Right?

 

...right?

[BooneWX]

HRRR with painfully low dews. Like -10 in the piedmont of Nc.

[Met1985]

5 minutes ago, BooneWX said:

HRRR with painfully low dews. Like -10 in the piedmont of Nc.

Cooked

[wake4est]

 

8 minutes ago, BooneWX said:

HRRR with painfully low dews. Like -10 in the piedmont of Nc.

 

[mstr4j]

Alright guys - getting into nowcasting and heavily relying on climo for our regions.  Question moving forward today - NAM vs HRRR vs RGEM vs FV3 - What do we like best in terms of verification for different aspects of their model "expertise"? 

NAM = Best Thermals of Atmosphere 18 hours away from kickoff?

RGEM = Location and movement of Lows

HRRR = Dewpoints - Those are some of the lowest Dews I have seen for the upstate of SC in a long time - and for the duration once moisture arrives - crazy

What's everyone's thought - If we could put together the best high resolution model what would we pick from each, or does anyone feel one of these is truly superior in all aspects?

[Buddy1987]

5 minutes ago, wake4est said:

 

 

I can honestly say i'm not sure since I moved to VA in 2011 i've ever seen a dew point map with readings that low. That is incredible.

[Tony Sisk]

25 minutes ago, buckeyefan1 said:

Because it’s only an app. It can’t hold all the information. It changes several times a day. It’s great for watching radar, but never ever use an app to make your plans regarding the weather. 

Agree 100%. But yet, it is shocking the number of people that will pull out a weather app and tell me to the hour what it's going to do.  Happened last night with a group I was having dinner with.

[NorthHillsWx]

To me the biggest question of the storm is now QPF. Is this in the 0.75” range (CAMs) which would no doubt cause issues but not anything like some of the 1.5-2” outputs we’d been seeing on the globals. There is a huge gap between those sets of guidance and that will dictate whether this is a memorable ice storm or just a sloppy mixed bag with moderate amounts of each precip type 

[Buddy1987]

So far with the 12Z Nam I like the trajectory of the precip inbound at 28hrs. HP in a slightly better position as well. Light returns trying to spill over the mountains. 5h also looks different in a good way as well to back up surface reflection.

[WinstonSalemArlington]

From our Mid-Atlantic neighbors, in pertinent part: 

Bob Chill

Posted just now

@Buddy1987and other swva peeps.

Trend overnight has been modest improvements in the mid levels and more snowfall pushing to even just south of the NC line…. Luckily the trend has been towards a more cohesive precip field when the getting is good. I liked the 0z&6z euro for our yards. Modest improvements where it counts the most. Globsl models are getting close to their final consensus solution and changes will prob be small going forwards

[DTP]

The dews, if they verify as modeled, are the nail in the coffin (or ice tomb in this case); sub-zero DP represents very cold, very dry air in the wedge at the surface

That type of airmass will be hard to overcome with precip, at least in the beginning.  But it will happen, given the magnitude of precip/isentropic lift over the cold dome; then evap cooling kicks in with the precip and dews rise/temps fall to meet the dews as RH increases 

Looking like a decent to strong probability of a stout period of sn/ip for a number of hours at onset in NC CAD areas, even possibly into Upstate SC......really no way around it with those type of DPs, even with the warm nose pushing in as modeled 

[BornAgain13]

12z HRRR drops around 4" up this way before the switchover. Not sure if its right

[DTP]

3 minutes ago, BornAgain13 said:

12z HRRR drops around 4" up this way before the switchover. Not sure if its right

Def possible given the low DP; how much of that is ip v sn is probably the toughest call

[Buddy1987]

NAM seemed cooler earlier on but it's really accelerating the sleet line north now by hrs 42-45

[BooneWX]

I’m trying to tread carefully here but I think GSP not coming to some agreement this morning and getting warnings hoisted is a blunder. Can’t get too ornery about exactly being 24hrs out or if it should be an ice storm or winter storm warning. It’s all in the wash. The general public doesn’t drill down that hard - missed opportunities to send out warnings while you had their attention waking up. 

[BornAgain13]

5 minutes ago, DTP said:

Def possible given the low DP; how much of that is ip v sn is probably the toughest call

Using kuchera, that normally knocks out the Ice or sleet

[wncsnow]

Nam looks weird

[NorthHillsWx]

NAM just wants to keep precip north with this system 

[Buddy1987]

Just now, wncsnow said:

Nam looks weird

Def implying a mega dry slot happens around hr 54. I still think anything outside minimum 36 hours is outside it's wheelhouse if it even has one anymore.

[NorthHillsWx]

Just now, Buddy1987 said:

Def implying a mega dry slot happens around hr 54. I still think anything outside minimum 36 hours is outside it's wheelhouse if it even has one anymore.

We will see, repercussions are massive 

[BooneWX]

NAM has a dry bias. FV3 has a more reasonable surface depiction. 

[ADB83]

NAM has big dry slot even through south central VA 

[Buddy1987]

1 minute ago, BooneWX said:

NAM has a dry bias. FV3 has a more reasonable surface depiction. 

To your point FV3 has a much more uniform precip shield entering the western mountains around 3ish tomorrow pm. Does FV3 tend to run colder though? Do you know?

[NorthHillsWx]

Huffman brought down his ice forecast. Cited less QPF and more sleet. Said further tweaks down may be needed and that areas might avoid a repeat of 2002

[UnionCountyNCWX]

23 minutes ago, NorthHillsWx said:

To me the biggest question of the storm is now QPF. Is this in the 0.75” range (CAMs) which would no doubt cause issues but not anything like some of the 1.5-2” outputs we’d been seeing on the globals. There is a huge gap between those sets of guidance and that will dictate whether this is a memorable ice storm or just a sloppy mixed bag with moderate amounts of each precip type 

Im going to disagree...slightly.... id argue the lighter QPF is a worse outcome as the heavier rates on the higher QPF solutions potentially might not freeze as fast and have more runoff, whereas the lighter solutions might include more of a "drizzle" which could freeze instantly. 

 

However thats more of like a hypothetical argument. 

[olafminesaw]

NAM actually has a band of very heavy sleet across the area. I think with the intensity of the WAA and the moisture feed it is likely that the dry slot won't be as significant factor as normally is the case with a miller B. 

[DTP]

3 minutes ago, Buddy1987 said:

NAM seemed cooler earlier on but it's really accelerating the sleet line north now by hrs 42-45

This is oddball question, and I have never really considered this: given that wind direction is SW just above the surface (and at a lower level than the Blue Ridge in many instances), wouldn't the whole CAD mechanism actually work in reverse just above the surface given this setup, at least up to the top of the Appalachians?  Obviously low levels in the wedge stay with 020 flow pretty much throughout- but I am talking about the layer between 2500'-4500' AGL- if this was the case, wouldn't it accelerate the warm nose NE-ward?

[BooneWX]

1 minute ago, Buddy1987 said:

To your point FV3 has a much more uniform precip shield entering the western mountains around 3ish tomorrow pm. Does FV3 tend to run colder though? Do you know?

I’m not sure about its thermals but the fact that it’s the eventual replacement for the NAM tells me which one I’ll be weighing 

[NorthHillsWx]

1 minute ago, UnionCountyNCWX said:

Im going to disagree...slightly.... id argue the lighter QPF is a worse outcome as the heavier rates on the higher QPF solutions potentially might not freeze as fast and have more runoff, whereas the lighter solutions might include more of a "drizzle" no. 

 

However thats more of like a hypothetical argument. 

Here’s how it helps us- the front end thump is roughly 0.30” in Raleigh. As depicted, that is all sleet. So if we only get 0.30-0.40” the rest of the event assuming runoff and maybe plain rain at the end there just isn’t enough QPF for the high end ice totals we were talking about 0.50”+