Jump to content
  • Member Statistics

    17,605
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

February Medium/Long Range Discussion


WinterWxLuvr
 Share

Recommended Posts

40 minutes ago, showmethesnow said:

But it did go back to dumping fairly aggressively into the SW at the end of the extended. Had been moving away from that so I was somewhat disappointed to see that.

Yea that’s why I said it looks ok not good. Lol. But we absolutely need to get some changes up top to have any chance. And analogs suggest the pac is a lost cause. We need some NAO help. The fact the eps went that way was more good than bad regardless of the western dump. 

Link to comment
Share on other sites

19 minutes ago, cbmclean said:

Anyone able to give a quick explanation of what a "wave breaking" is?  Seen it mentioned several times this winter.

Planetary waves (Rossby waves) break when they gain enough amplitude that their potential vorticity gradient is overturned. This leads to mixing of their pv. When it happens in a favorable way it can aid in the transport of heat into the HL and weaken or displace the tpv.  

Link to comment
Share on other sites

21 minutes ago, psuhoffman said:

Planetary waves (Rossby waves) break when they gain enough amplitude that their potential vorticity gradient is overturned. This leads to mixing of their pv. When it happens in a favorable way it can aid in the transport of heat into the HL and weaken or displace the tpv.  

Speaking of which, might be seeing just the beginning of a bit of warming from the Atlantic side at the end of the Euro op run today. 50 mb is as low as we have on WB, but might be fairly indicative of whats happening in the upper troposphere. It is becoming more elongated/tilted here than the previous panels. Still, look at that beast. What an absolute monster the PV has been this winter.

1582372800-xzpinMJbnC8.png

 

Link to comment
Share on other sites

1 minute ago, C.A.P.E. said:

Speaking of which, might be seeing just the beginning of a bit of warming from the Atlantic side at the end of the Euro op run today. 50 mb is as low as we have on WB, but might be fairly indicative of whats happening in the upper troposphere. It is becoming more elongated/tilted here than the previous panels. Still, look at that beast. What an absolute monster the PV has been this winter.

1582372800-xzpinMJbnC8.png

 

Does the +++++AO (yuck...gotta wash my mouth out with soap) correlate to the strong PV?

Link to comment
Share on other sites

4 minutes ago, Maestrobjwa said:

Does the +++++AO (yuck...gotta wash my mouth out with soap) correlate to the strong PV?

I think the +++++AO and the strong PV are different names for the same phenomenon.  In other words, the AO index is a measure of the strength of the PV.  Please someone chime in if I am misinformed.

Link to comment
Share on other sites

39 minutes ago, psuhoffman said:

Planetary waves (Rossby waves) break when they gain enough amplitude that their potential vorticity gradient is overturned. This leads to mixing of their pv. When it happens in a favorable way it can aid in the transport of heat into the HL and weaken or displace the tpv.  

Thanks!  I find this stuff really interesting.

Link to comment
Share on other sites

13 minutes ago, cbmclean said:

I think the +++++AO and the strong PV are different names for the same phenomenon.  In other words, the AO index is a measure of the strength of the PV.  Please someone chime in if I am misinformed.

There is a strong correlation. The AO index actually is a measure of surface pressure near the pole. We want to see higher pressure there. (-AO)

The SPV does not always couple to the TPV, but it has this winter.

Generally speaking, a strong PV tends to keep the cold air locked up in the HL regions, and outside of a big EPO ridge, it becomes very difficult to get legit cold air delivery into the mid-latitudes.

Link to comment
Share on other sites

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

There is a strong correlation. The AO index actually is a measure of surface pressure near the pole.We want to see higher pressure there. (-AO)

The SPV does not always couple to the TPV, but it has this winter.

Generally speaking, a strong PV tends to keep the cold air locked up in the HL regions, and outside of a big EPO ridge, it becomes very difficult to get legit cold air delivery into the mid-latitudes.

CPC page gives this definition.  I am trying to make heads or tails of it.

" The daily AO index is constructed by projecting the daily (00Z) 1000mb height anomalies poleward of 20°N onto the loading pattern of the AO. "

So I understand the concept of geopotential height anomaly, although I am not used to see it at 1000 MB.  What does it mean to "project it on the loading pattern".

Link to comment
Share on other sites

I had a feeling it was headed there looking at the 0z run. It has not been as enthusiastic about building a PNA ridge- it flirts with neutral then wants to build heights further west again. GEFS and at times the GEPS seem to like the idea of a more favorable western ridge position. Maybe the EPS is on to something and we get a nice HL block for March to counter the crappy Pacific. :rolleyes:
Enjoy the .01 the eps gives you thru 15
  • Sad 1
Link to comment
Share on other sites

8 minutes ago, cbmclean said:

CPC page gives this definition.  I am trying to make heads or tails of it.

" The daily AO index is constructed by projecting the daily (00Z) 1000mb height anomalies poleward of 20°N onto the loading pattern of the AO. "

So I understand the concept of geopotential height anomaly, although I am not used to see it at 1000 MB.  What does it mean to "project it on the loading pattern".

I think it means based on observations of the surface pressures observed in that area over a specific period of time, in order to arrive at a mean.

eta- I think I am pretty close. This is from the CPC: The loading pattern of the AO is defined as the leading mode of Empirical Orthogonal Function (EOF) analysis of monthly mean 1000mb height during 1979-2000 period.

Link to comment
Share on other sites

1 minute ago, NorthArlington101 said:

 


That’s a pretty weenie run for this far out given what we’ve seen this winter. I’m gonna go down sinking with this ship.

 

Agree. It is the GFS/GEFS though. I started getting an oddly "good" feeling about this after the 6z run this morning.

  • Like 1
Link to comment
Share on other sites

Agree. It is the GFS/GEFS though. I started getting an oddly "good" feeling about this after the 6z run this morning.

Agreed. I hopped on this train yesterday... something about this one seems right for some reason. No idea why.

I was hoping the 12z EPS would’ve been good enough to share today, but it wasn’t. Like two good storms in the whole suite. Had a bit of a southern max though, which is always nice to see.
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...