Potential winter threats

[SnoSki14]

what i like about the next 10 days, with the vortexs floating arounnd the northeast all it takes is one storm, which was shown by the 12z euro to phase with it and produce a big storm for someone. The pattern has a lot of potential, especailly with the hostoric blocking, you can get crazy outcomes.

I'm not so sure about a lot of potential. Yes I think we will see some snow, but probably a couple of minor to at most a moderate event. This winter will be completely different from last winter. We don't have a crazy STJ this season that could lead to huge snow events, we have a less favorable Pacific. With those differences, there's only potential for smaller events (1-3, 2-4, 3-5" snows), but I'll take what I can get.

[Dark Energy]

It should be almost exactly the same next week as it's been this past week, including the lows. Actually the lows will be warmer next week because we may not experience ideal radiating conditions. Not even the suburbs of the city are forecast to reach the teens anymore. Coldest day will probably be Tuesday, it should still be below freezing for many places.

oh yea, there will be many places over the interior in the 20s for highs this week. ULL's at night are tricky concerning ovn lows. What you have to watch for is the individual vorts rotating around the gyre. If your under one, then you got clouds, flurries and no radiating. in between there is always clearing pockets, or sucker holes as sometimes they are called. But, timing of said vorts at any distance, even in the short term is very difficult.

[mattinpa]

I'm not so sure about a lot of potential. Yes I think we will see some snow, but probably a couple of minor to at most a moderate event. This winter will be completely different from last winter. We don't have a crazy STJ this season that could lead to huge snow events, we have a less favorable Pacific. With those differences, there's only potential for smaller events (1-3, 2-4, 3-5" snows), but I'll take what I can get.

I'd never say there's potential ONLY for small-medium storms. With the blocking pattern, if things go right, we can get a major storm.

[SnoSki14]

I'd neverr say there's ONLY potential. With the blocking pattern, if things go right, we can get a major storm.

How many major storms have there been in a La Nina of this kind of strength in the past. I would bet that there probably haven't been too many.

[Riptide]

Here is the 18z GFS ensemble mean at 120 hr.

[mattinpa]

How many major storms have there been in a La Nina of this kind of strength in the past. I would bet that there probably haven't been too many.

We got one in Jan. 1996. It's stronger this year, but it can happen.

[mattinpa]

Here is the 18z ensemble mean at 120 hr.

Definitely a red flag when ensembles are north.

[Riptide]

Definitely a red flag when ensembles are north.

And moreso than 12z ensembles, it's rather interesting. The UKMET and GGEM might be on to something.

[Thunder Road]

We got one in Jan. 1996. It's stronger this year, but it can happen.

Actually all Mod and Strong Ninas back to 1950 have yielded 0 storms of 10" of greater at PHL.

But there is definitely something to be said that this winter is not like any other past Strong Nina because of the excessive -NAO/-AO

[Kaner587]

jetski-how many times has the AO been this low in a mod-strong La nina? Oh wait ....never. Don't proclaim the severity of threats based on enso status your going to get burned at some point. Not saying that KU's are likely in a mod-strong La Nina, but you have to realize how anomalous a pattern we are in

[atownwxwatcher]

Actually all Mod and Strong Ninas back to 1950 have yielded 0 storms of 10" of greater at PHL.

But there is definitely something to be said that this winter is not like any other past Strong Nina because of the excessive -NAO/-AO

And how many winters since 1950 have been a moderate -strong La Nina?

[mattinpa]

jetski-how many times has the AO been this low in a mod-strong La nina? Oh wait ....never. Don't proclaim the severity of threats based on enso status your going to get burned at some point. Not saying that KU's are likely in a mod-strong La Nina, but you have to realize how anomalous a pattern we are in

Very reasonable post, IMO.

[Alpha5]

This is NOT correct... the trough going negative does NOT bring the system up the coast.

Given the way the pattern is set for the DEC 16-17 event that wave cannot come up the coast

Reasoning behind this? What part of the pattern prevents the storm coming up the coast?

[SnowGoose69]

i know its hr 384, and will likely be gone, but has anyone ever seen sub -40 850s?

Yes, and believe it or not it was on a regular basis during the 01-02 winter in Canada....there was one of the most impressive cold air supplies up in Canada as I can ever recall on the models during that winter but because of the enhanced zonal flow and extremely small PV it could never get into the U.S.

[Kaner587]

Reasoning behind this? What part of the pattern prevents the storm coming up the coast?

The gigantic west based -NAO combined with a horribly placed 50/50(too far south)...also not this this matters as much but the lack of a formidable western ridge (+PNA) prevents digging of the s/w

[Thunder Road]

And how many winters since 1950 have been a moderate -strong La Nina?

I thought I saw the report on NWS PHI somewhere. In fact I think it might have been Tony who compiled the list. I'm not poo-pooing the chances for the next weeks, just saying that using the '96 analog all the time since we're in a Nina is not a good idea

[Kaner587]

Yes, and believe it or not it was on a regular basis during the 01-02 winter in Canada....there was one of the most impressive cold air supplies up in Canada as I can ever recall on the models during that winter but because of the enhanced zonal flow and extremely small PV it could never get into the U.S.

ew...but i think its obvious at this point that this winter will have much different weather than that winter featured (lack of a -NAO and -AO)

[Rainshadow]

And how many winters since 1950 have been a moderate -strong La Nina?

13.

[atownwxwatcher]

13.

http://www.americanw...winter-analogs/

Thanks. Where did you compile this list from or what method because using the CPC historical enso data it does not appear that there would be all that many? And what do you consider as the beginning threshold of moderate?

[Rainshadow]

Thanks. Where did you compile this list from or what method because using the CPC historical enso data it does not appear that there would be all that many? And what do you consider as the beginning threshold of moderate?

Its a personal list. I used -1.0C.

[tombo82685]

gfs, isn't doing it this run with the potential for the first part, although it did come further north from 18z. Weakened the vortex a good bit and rose hgts better, but the placement of the vortex is still hurting it.

[Alpha5]

H5 changes, nothing on the surface...remains the SE/Weak outliner

[Colin]

H5 changes, nothing on the surface...remains the SE/Weak outliner

euro had nothing, ukmet was pretty similar to the gfs...only model that impacted the area whatsoever was the ggem and it was with very minimal qpf. not much support for this 'storm' at the moment.

[tombo82685]

euro had nothing, ukmet was pretty similar to the gfs...only model that impacted the area whatsoever was the ggem and it was with very minimal qpf. not much support for this 'storm' at the moment.

read dt's statement, ukmet looks like the gem.

[CooL]

Lets see what the gfs does with storm # 2 , last run it was supressed and never really got its act together...

[SnoSki14]

Lets see what the gfs does with storm # 2 , last run it was supressed and never really got its act together...

I didn't even know the gfs showed Storm #2, I didn't see anything.

[CooL]

I didn't even know the gfs showed Storm #2, I didn't see anything.

it did on 18z but it was ots..but im not even sure if it originated at the same place as the euro, but it was the same timeframe

[isnice]

I love how people were bashing me earlier for comparing this to the clipper that completely missed us to our south.

#1: We're talking about a terribly placed 50/50 low. Look at the maps, I don't have to explain. A 50/50 over Maine is not condusive of a storm hitting anywhere north of Richmond. Sorry.

#2: The massive west-based -NAO. It's the curse: we have the NAO when we don't want it, and we don't have it when we need it.

#3: Even though there are ridges in the southeast, they are nowhere near strong enough to combat the 50/50 lows.

I'm not saying this won't happen, I'm just simply laying everything out onto the playing field.

[Ji]

worst run of the GFS of the winter

[SnoSki14]

worst run of the GFS of the winter

Just wait until January, then you'll be getting some bad runs.

Generally we don't want to have a SE ridge but in this case, it wouldn't hurt. At least it would buckle the jet possibly giving us something. The SE ridge can become a huge asset if there is some blocking involved, but too much blocking will kill the SE ridge and if you have a graveyard STJ, it's a bad pattern for snow.