February Medium/Long Range Discussion

[CAPE]

Just now, Ji said:

8 minutes ago, CAPE said:

Other thread if you are interested in seeing the 18z Euro op. I'll save you the trouble- you will like it. Rain for your yard.

I meant for the cape storm. The thur storm has always been toast. Literally

The op only goes out to hour 90 at 18z.

[CAPE]

18z EPS looks a bit further south.

[CAPE]

[Weather Will]

Agreed.  Less ridging along the East coast.  WB 18Z EPS

[WinterWxLuvr]

20 minutes ago, CAPE said:

18z EPS looks a bit further south.

When it gets far enough south to keep me high and dry you’ll know it’s locked in.

[Weather Will]

WB EURO Weekly Control has my mid March Hail Mary storm.  More realistic is that it stays cold through the first half of March on the mean weeklies with the peak around March 5.

[Ji]

Never 2 good runs in a row. So frustrating

[Maestrobjwa]

4 minutes ago, Ji said:

33 minutes ago, CAPE said:

Never 2 good runs in a row. So frustrating

In a progressive regime...frustrating but not surprising!

[WinterWxLuvr]

To understand my perspective, Winchester has had 5.6” of precip since October. 10 of the past 14 months have been below normal precip. It’s getting old. And my thoughts are and have always been that no precip is a zero chance of snow, but appreciable precip will always bring with it some chance of wintry precip in the months of Dec/Jan/Feb. Some chance is better than no chance. That’s why the only maps I care about are precip maps.

[psuhoffman]

6 minutes ago, WinterWxLuvr said:

To understand my perspective, Winchester has had 5.6” of precip since October. 10 of the past 14 months have been below normal precip. It’s getting old. And my thoughts are and have always been that no precip is a zero chance of snow, but appreciable precip will always bring with it some chance of wintry precip in the months of Dec/Jan/Feb. Some chance is better than no chance. That’s why the only maps I care about are precip maps.

You need BOTH 

[WinterWxLuvr]

35 minutes ago, psuhoffman said:

You need BOTH 

You just don’t get it do you? If my forecast for Sunday is for 0.05” of precip do I really give a shit how cold it is? I’m not an idiot. Of course I need BOTH. I’ll say it again, no precip =no chance. Precip = a non zero chance typically during winter. Places that get precip are guaranteed snow this weekend as temps are iffy, but they have a chance. Would you rather have that or a completely zero chance?

[Ji]

Awful awful trends tonight.

[Grothar of Herndon]

6 minutes ago, Ji said:

Awful awful trends tonight.

Hang in there. We still have Will’s 600 hours Euro Control storm. 

[psuhoffman]

2 hours ago, WinterWxLuvr said:

You just don’t get it do you? If my forecast for Sunday is for 0.05” of precip do I really give a shit how cold it is? I’m not an idiot. Of course I need BOTH. I’ll say it again, no precip =no chance. Precip = a non zero chance typically during winter. Places that get precip are guaranteed snow this weekend as temps are iffy, but they have a chance. Would you rather have that or a completely zero chance?

If the thermal boundary is north of us and it’s 50 we have zero chance of snow no matter how wet it is.  We need both a cold pattern AND precip. They are both equally necessary to get snow. This isn’t even a debatable thing. If it’s warm it can’t snow. If it’s dry it can’t snow. 

[psuhoffman]

1 hour ago, Ji said:

Awful awful trends tonight.

The tpv didn’t get displaced where we want. This pattern isn’t awful. We could luck into something. This threat isn’t dead. But for much of the last 5 years some have wanted the pac to cooperate and questioned the importance of the Atlantic. Well…this is what a good pac bad Atlantic looks like. It’s just as frustrating. 

[Maestrobjwa]

10 minutes ago, psuhoffman said:

The tpv didn’t get displaced where we want. This pattern isn’t awful. We could luck into something. This threat isn’t dead. But for much of the last 5 years some have wanted the pac to cooperate and questioned the importance of the Atlantic. Well…this is what a good pac bad Atlantic looks like. It’s just as frustrating. 

Dang the tpv didn't get displaced where we wanted it last year either, lol Oof!

[09-10 analogy]

10 hours ago, CAPE said:

They are pretty useless at range imo, but the masses want to see those blues and purples and pinks.

Snow maps at range are generally OK for codifying the impossible. 

[CAPE]

The 0z runs of the 3 global ensembles still have a storm, a bit further south than we want- just like previous runs. Take a breath.

As I said yesterday when the op runs looked 'good'- expect changes as the combo of the amplified ridge and the displaced TPV(and their interaction) is subject to volatility.

There were unsurprisingly some generally subtle changes at h5 on the op runs last night that influenced the ultimate(simulated) outcome. The character of the western ridge and the degree to which the TPV lobe drops south were a little different. The ridge didn't 'fold over' so the NS energy on the Euro didn't dig nearly as much and was broader- so no constructive interaction/phase with the southern wave- which was weaker overall as well. GFS was also less aggressive with the vorticity lobe- not digging it as far south or far enough west to scoop the wave ejecting from out west. Instead it drops in behind it too late and kicks it out, then the cold comes in.

On we go.

[CAPE]

18z was the last 'good' operational GFS run and this is why it worked- the NS energy drops in aggressively further west and lifts the southern wave, allowing the developing low to be further nw and gain some latitude as it moves off the coast.

The second image below is the 0z(6z looks essentially the same) and the differences are clear. If you compare the two you can see the differences in the character of the ridge (follow the height lines), which influences the the digging NS vorticity.

 

[Weather Will]

Latest ensemble runs for snow….

[Wonderdog]

1 hour ago, CAPE said:

18z was the last 'good' operational GFS run and this is why it worked- the NS energy drops in aggressively further west and lifts the southern wave, allowing the developing low to be further nw and gain some latitude as it moves off the coast.

The second image below is the 0z(6z looks essentially the same) and the differences are clear. If you compare the two you can see the differences in the character of the ridge (follow the height lines), which influences the the digging NS vorticity.

 

Those height lines out west are a little bit different but it's not like it's a game changer. I agree with you. Still five days out.

[RevWarReenactor]

It seems like the model  theme this year is to get a trend slowly to what we want around the 100hr mark and then and huge jump in the wrong direction where it stays locked in. Can’t even buy a 2 inch snowstorm around here. 

[CAPE]

36 minutes ago, Wonderdog said:

Those height lines out west are a little bit different but it's not like it's a game changer. I agree with you. Still five days out.

Subtle differences in the character of the ridge and or location of the TPV can make fairly large differences in outcome. They interact. Waves in the atmosphere behave much like waves in the ocean, so if that amplified ridge 'leans' forward or breaks over, it will result in a deeper, more westward dig of the NS energy.

The other critical aspect is timing. Again, without a block, the Rossby waves are constantly propagating (progressing), so getting the waves of interest to time up the way we need is more difficult.

[CAPE]

We desperately need a moderate Nino with persistent HL blocking next winter. ENSO predicted to go neutral by late Spring, early Summer I believe. 

[dallen7908]

1 hour ago, Weather Will said:

Latest ensemble runs for snow….

Indeed, the percent of EPS members giving the DC-area > 3" of snow during the 27 Feb - 2 Mar period has dropped to 2% after bouncing between 15 and 25% over 7 cycles (3 1/2 days).  Of course, there are only 2 possible outcomes.  So if the best you can do is 25% you're probably headed to nada in the end.  Hoping for a dead cat bounce over the next cycle or two to keep us interested.  

T-3 weeks to Hail Mary time.  Hopefully, we'll experience a few "forward breaking waves" before then.

[CAPE]

1 hour ago, Weather Will said:

Latest ensemble runs for snow….

The Sunday-Monday window is a great example of why these ens mean snow maps are utterly useless at range. The ops are all over the place on the degree of interaction between the NS energy dropping down and the southern wave ejecting eastward from the SW. These differences are reflected among the ensemble members in subsets- in general if there is no/late interaction between the NS and the southern wave, it tracks generally eastward, there is not much cold, and almost no snow anywhere. Cold comes in behind. If the NS comes in deeper/further west, there is some degree of interaction/phasing and there is more precip and more cold. At this juncture we still have a lot of uncertainty, and the snow maps just average out the divided camps among the members. It tells you nothing.

[George BM]

29 minutes ago, CAPE said:

We desperately need a moderate Nino with persistent HL blocking next winter. ENSO predicted to go neutral by late Spring, early Summer I believe. 

Good thing the CFSv2 is going to end up dead wrong and it's before the spring barrier anyway (spoiler it wants another Mod LN next winter).  

(Not that you put any trust in the CFSv2 or any climate model for that matter.) 

[dallen7908]

... Yes of course the ensemble mean adds little given how non-dispersive the members are and how skewed the precipitation distribution is at range but an ensemble of ensemble PCTLs is still useful, e.g., the 10th, 50th, and 90th percentiles of ensembles based on more than one operational model

[CAPE]

3 minutes ago, George BM said:

Good thing the CFSv2 is going to end up dead wrong and it's before the spring barrier anyway (spoiler it wants another Mod LN next winter).  

(Not that you put any trust in the CFSv2 or any climate model for that matter.) 

3 consecutive Ninas.. some here might need to consider therapy lol.

[psuhoffman]

35 minutes ago, CAPE said:

We desperately need a moderate Nino with persistent HL blocking next winter. ENSO predicted to go neutral by late Spring, early Summer I believe. 

I’m not sure enso drives the bus the same way anymore. The last Nino behaved like a Nina. Last winter and this didn’t really behave like canonical Nina’s either. There was plenty of stj this year and the pac pattern was almost dead opposite a typical Nina.   If we had any Atlantic help at all I think we would have done very well. Nina wasn’t our biggest problem a raging positive NAO was.