December/January Medium/Long Range Discussion

[Wonderdog]

13 minutes ago, showmethesnow said:

We don't want a trough over Alaska. We want that trough to the west over the Aleutians with ridging up through Alaska.

Thanks showme.

[Ji]

People say not to panic but it hasn't snowed here since Jan 2016 so any bad runs cause me to panic!

[WxUSAF]

3 hours ago, psuhoffman said:

Glad to see EPS back to what we expect for January. I’ll just assume 12z ate some bad chili.

[WxUSAF]

47 minutes ago, showmethesnow said:

We don't want a trough over Alaska. We want that trough to the west over the Aleutians with ridging up through Alaska.

Well, if you look at the 500 composite for our big storms on the day they occur, there is a trough along the west coast into AK. That’s just because of the wave spacing because the PNA ridge moves inland and lines up near Idaho for our big dogs. But the setup to get a big storm pushes things west so there’s ridging in AK. In fact a composite of a few days before big storms would look fairly similar to the overnight EPS in January...

[Ralph Wiggum]

15 minutes ago, Ji said:

People say not to panic but it hasn't snowed here since Jan 2016 so any bad runs cause me to panic!

The struggle is real. Dont forget the atmospheric memory. Mother nature plays a balancing act. Yes weather is a living gender-based entity with a brain. I read it on the internet.

[Ralph Wiggum]

6 minutes ago, WxUSAF said:

Glad to see EPS back to what we expect for January. I’ll just assume 12z ate some bad chili.

What do you make of the strongly positive AO on most ens during the same time? Just curious what role folks think this will play during peak climo? I recall reading here that the AO is perhaps the largest overall driver of the hemispheric pattern.

[CAPE]

19 minutes ago, Ji said:

People say not to panic but it hasn't snowed here since Jan 2016 so any bad runs cause me to panic!

So basically you will only be satisfied with a KU?

[WxUSAF]

4 minutes ago, Ralph Wiggum said:

What do you make of the strongly positive AO on most ens during the same time? Just curious what role folks think this will play during peak climo? I recall reading here that the AO is perhaps the largest overall driver of the hemispheric pattern.

Is it strongly positive? On which guidance? You can measure AO a couple different ways and we usually look at 500, but it’s technically measured at 1000mb. In either case, on the GEFS which I can see, it looks neutral-ish at worse. AO domain is huge and that monster NAO “counts” for the AO too mostly.

[CAPE]

9 minutes ago, Ralph Wiggum said:

What do you make of the strongly positive AO on most ens during the same time? Just curious what role folks think this will play during peak climo? I recall reading here that the AO is perhaps the largest overall driver of the hemispheric pattern.

Not necessarily. But a -AO does have the strongest correlation to winters with above normal snowfall for the DC area.

[CAPE]

3 minutes ago, WxUSAF said:

Is it strongly positive? On which guidance? You can measure AO a couple different ways and we usually look at 500, but it’s technically measured at 1000mb. In either case, on the GEFS which I can see, it looks neutral-ish at worse. AO domain is huge and that monster NAO “counts” for the AO too mostly.

It is slightly negative now. He may be looking at the advertised MSLP Anomalies in the LR and seeing lots of blue up top in the primary AO domain. With all the strat stuff going on, I would guess there is quite a bit of uncertainty currently wrt how exactly things evolve in the high latitudes. With the SPV taking a beating, it would be surprising to me if the AO goes positive and stays there in the long run.

[psuhoffman]

40 minutes ago, Ji said:

People say not to panic but it hasn't snowed here since Jan 2016 so any bad runs cause me to panic!

Didn't you just get like 4" in November and 5-6" in March?  What are you talking about?

[CAPE]

Just now, psuhoffman said:

Didn't you just get like 4" in November and 5-6" in March?  What are you talking about?

#snowinwintermonths

#KUorBUST

[Ralph Wiggum]

5 minutes ago, C.A.P.E. said:

It is slightly negative now. He may be looking at the advertised MSLP Anomalies in the LR and seeing lots of blue up top in the primary AO domain. With all the strat stuff going on, I would guess there is quite a bit of uncertainty currently wrt how exactly things evolve in the high latitudes. With the SPV taking a beating, it would be surprising to me if the AO goes positive and stays there in the long run.

Exactly what I was glancing at. Ty for explaining. 

[psuhoffman]

24 minutes ago, C.A.P.E. said:

So basically you will only be satisfied with a KU?

That's what I'm tying to figure out. Because he just had a 4" snow last month and a warning event (5-6") last march. So if he only counts HECS storms then 2 years isn't a long time. Historically we go 4 years between those kind of events. By any measure he seems off. 

[CAPE]

1 minute ago, psuhoffman said:

That's what I'm tying to figure out. Because he just had a 4" snow last month and a warning event (5-6") last march. So if he only counts HECS storms then 2 years isn't a long time. Historically we go 4 years between those kind of events. By any measure he seems off. 

This is the way you or I, or most people would evaluate it, lol.

[psuhoffman]

42 minutes ago, WxUSAF said:

Glad to see EPS back to what we expect for January. I’ll just assume 12z ate some bad chili.

But it's not meteorologly possible so...

[BristowWx]

Just now, psuhoffman said:

But it's not meteorologly possible so...

Sure it is...bad chili happens to good models

[psuhoffman]

1 minute ago, BristowWx said:

Sure it is...bad chili happens to good models

Maybe snowgoose ate some bad chili too

[CAPE]

1 minute ago, psuhoffman said:

But it's not meteorologly possible so...

 I am sure he would say the -EPO is weak and the -NAO is east based. I have a feeling the real "meteorologically impossible" look will show up in a few more runs though.

[psuhoffman]

27 minutes ago, WxUSAF said:

Is it strongly positive? On which guidance? You can measure AO a couple different ways and we usually look at 500, but it’s technically measured at 1000mb. In either case, on the GEFS which I can see, it looks neutral-ish at worse. AO domain is huge and that monster NAO “counts” for the AO too mostly.

People make too much of those values. The nao is measured at the surface too. But the h5 has way more effect on our weather. When I was doing some data digging the last 2 years for snowfalls in a Nina I found only a few outliers where we had a warning snow in a Nina without a -nao. But then when I looked at h5 composites for those events I found we really did have one. The numerical values didn't show it but there was either ridging over Greenland or some bootleg block (like a Kara block) that impacted the longwave pattern the same way. But you would never know it from the official nao numbers.  

[psuhoffman]

5 minutes ago, C.A.P.E. said:

 I am sure he would say the -EPO is weak and the -NAO is east based. I have a feeling the real "meteorologically impossible" look will show up in a few more runs though.

To be fair there was some (SOME) truth to what he said. If you get a beast epo ridge (a full latitude ridge) then it would be almost impossible to have a -nao as the natural buckling of the jet in response would favor a trough there. But nothing has shown a monster epo full latitude ridge and the run we were referencing had no epo ridge at all and so his comments made no sense in context. Maybe he had a point that I just wasn't getting. 

[poolz1]

24 minutes ago, psuhoffman said:

To be fair there was some (SOME) truth to what he said. If you get a beast epo ridge (a full latitude ridge) then it would be almost impossible to have a -nao as the natural buckling of the jet in response would favor a trough there. But nothing has shown a monster epo full latitude ridge and the run we were referencing had no epo ridge at all and so his comments made no sense in context. Maybe he had a point that I just wasn't getting. 

Agree....You almost dont want a classic cross polar set up from a -EPO.  But it is entirely possible to get a "horseshoe" of positive heights that give us a the holy grail of teles....We dont need the Arctic mother load....  

[frd]

Per Allan Huffman, the Euro has been very consistent in the time frame of 12/27 to 12/30 for the reversal, we will see. This post from griteater

 

 

[aldie 22]

2 hours ago, C.A.P.E. said:

So basically you will only be satisfied with a KU?

Not just one

[frd]

@poolz1 sorryt for delay stricken with some sort of bug. 

Interesting as well in regards to the target reversal or not, seems the models flip and flop as to when. The Euro as mentioned above more consistent , the GEFS was doing well, then seems it went to the GFS. 

Read similiar to last year during Jan and Feb  the dates keep changing as the actual SPV went through periods of weakening , then reporganized , then weakened, etc. 

You can read about that here. 

Not unusual what is happening currently. 

 Replying to @FrenchScotPilot

I agree! So now we have a new “pivot point” in the forecast, around Dec 28. The weaken-strengthen-weaken behaviour threw off a lot of models in Jan-Feb this year; interesting to see it happen again.

 

[nj2va]

Hmm, comparing StormVista and Weathermodels.com EPS total snowfall from 00z (through 360H), SV shows 6” through DC while WM.com shows 2.5”.  Weenie handbook says hug the snowier model.  Interestingly enough, SV is usually the more conservative IRT snowfall totals.  

[frd]

@psuhoffman

Cool animation and going to the -NAO

 

[nj2va]

@frd Cool animation...love seeing those reds over GL form (and subsequently the blues over the east coast).  

[jaydreb]

3 minutes ago, nj2va said:

Hmm, comparing StormVista and Weathermodels.com EPS total snowfall from 00z (through 360H), SV shows 6” through DC while WM.com shows 2.5”.  Weenie handbook says hug the snowier model.  Interestingly enough, SV is usually the more conservative IRT snowfall totals.  

WxBell snowfall mean is 3” for most of DC and 2.5” in SE DC and DCA.  

[CAPE]

1 hour ago, psuhoffman said:

To be fair there was some (SOME) truth to what he said. If you get a beast epo ridge (a full latitude ridge) then it would be almost impossible to have a -nao as the natural buckling of the jet in response would favor a trough there. But nothing has shown a monster epo full latitude ridge and the run we were referencing had no epo ridge at all and so his comments made no sense in context. Maybe he had a point that I just wasn't getting. 

Yeah who knows, but it is certainly not impossible. There are many variations and subtleties with these features. The "ridge bridge" is an extreme case and does occur- a big blocking ridge in the E/NPAC bridging with a GL ridge in the NAO region.