Medium Range-Long Range thread

[cast4]

No real difference from any other time this winter :-)

@ this point, we're going to start to battle #climo, sun angle and all that good stuff, especially along the coastal event. MArginal set ups/weak coastals wont cut it. And like you have been saying, with the PV retreated to mother russia, our cold pool will be modifying.

Yeah, and those gl lows sitting there all the time aren't helping either.

[famartin]

No real difference from any other time this winter :-)

@ this point, we're going to start to battle #climo, sun angle and all that good stuff, especially along the coastal event. MArginal set ups/weak coastals wont cut it. And like you have been saying, with the PV retreated to mother russia, our cold pool will be modifying.

Its been HM etc more than I (I tend to stay mostly quiet in this thread since I'm more of a learner than a master, unlike HM and Adam for example), but I agree with it.

[tombo82685]

I have been away all day, but great discussion in here. What is ZAPE?

[Quakertown needs snow]

Out to Mar 7

 

[am19psu]

I have been away all day, but great discussion in here. What is ZAPE?

Not actually sure what the Z stands for, but APE is available potential energy, i.e. the pole-to-equator temperature gradient, in this case measuring the total baroclinicity of the northern hemisphere.

[phlwx]

If this pattern were at the beginning and not end of February...

[tombo82685]

Not actually sure what the Z stands for, but APE is available potential energy, i.e. the pole-to-equator temperature gradient, in this case measuring the total baroclinicity of the northern hemisphere.

 

So I'm going to take a stab the more gradient the better chance for meridonal flow?

[am19psu]

So I'm going to take a stab the more gradient the better chance for meridonal flow?

The stronger the total pole to equator temperature (P2E) gradient, the stronger the zonal winds (thermal wind balance). That's why people talk about +AAM states being Nino-like (because in a Nino, the total P2E gradient is stronger). But, the stronger the zonal winds, the more likely you are to reach the criterion for baroclinic instability, which does lead to meridional flow if there is some disturbance to the flow (e.g. differential heating, mountain torque, etc).

Also, the wavelength of Rossby waves are also related to the background P2E gradient -- the larger the P2E gradient, the longer the wavelengths of the Rossby waves. That's why we talk about the wavelengths getting longer heading into winter and shorter heading into spring. That's how this whole conversation got started, because HM was talking about the shorter wavelengths in the Western Hemisphere in the upcoming pattern and I'm trying to figure out why that would be the case. It's sounding like the total global wavenumber is not any different, but due to the polar vortex being over Siberia, causing flat flow over Asia, all of the waves that are required by the P2E are being bunched up over the PNA region.

[Mike.Ventrice]

I have been away all day, but great discussion in here. What is ZAPE?

 

 

Not actually sure what the Z stands for, but APE is available potential energy, i.e. the pole-to-equator temperature gradient, in this case measuring the total baroclinicity of the northern hemisphere.

 

Z is for Zonal!

[am19psu]

duh. That was stoopid of me.

[tombo82685]

Z is for Zonal!

So mike, first off thanks for all that you add. I think i have learned a ton of new stuff this winter. How would you read that map on the zape. I remember you saying if it goes from negative to positive it teleconnects to colder air for the US. Is there a certain plateau it has to reach to be considered a good teleconnect for this? Just because it goes from negative to positive doesn't always mean colder air is there a threshhold for amplitude it has to get to before it teleconnects? 

[pazzo83]

So mike, first off thanks for all that you add. I think i have learned a ton of new stuff this winter. How would you read that map on the zape. I remember you saying if it goes from negative to positive it teleconnects to colder air for the US. Is there a certain plateau it has to reach to be considered a good teleconnect for this? Just because it goes from negative to positive doesn't always mean colder air is there a threshhold for amplitude it has to get to before it teleconnects? 

 

Isn't it the inverse of that?  ZAPE going from positive anomalies to negative anomalies can yield a cold outbreak in the lower 48, right?

[tombo82685]

Isn't it the inverse of that?  ZAPE going from positive anomalies to negative anomalies can yield a cold outbreak in the lower 48, right?

yea i got that mixed up, thanks for correcting that.

[NJwinter23]

The stronger the total pole to equator temperature (P2E) gradient, the stronger the zonal winds (thermal wind balance). That's why people talk about +AAM states being Nino-like (because in a Nino, the total P2E gradient is stronger). But, the stronger the zonal winds, the more likely you are to reach the criterion for baroclinic instability, which does lead to meridional flow if there is some disturbance to the flow (e.g. differential heating, mountain torque, etc).

Also, the wavelength of Rossby waves are also related to the background P2E gradient -- the larger the P2E gradient, the longer the wavelengths of the Rossby waves. That's why we talk about the wavelengths getting longer heading into winter and shorter heading into spring. That's how this whole conversation got started, because HM was talking about the shorter wavelengths in the Western Hemisphere in the upcoming pattern and I'm trying to figure out why that would be the case. It's sounding like the total global wavenumber is not any different, but due to the polar vortex being over Siberia, causing flat flow over Asia, all of the waves that are required by the P2E are being bunched up over the PNA region.

 

Interesting stuff. I'm really not sure the answer to any of this. The thoughts I threw out there yesterday regarding HM's shorter wavelengths idea are probably flat out wrong or too simplistic 

[HM]

Seems like today's GFS suite is signaling the March week 2 warming we were talking about at the start of the week. The ECMWF should be interesting. I know we've seen some ridiculous analogs thrown around but using straight 500mb anomalies could get you in trouble here. I think 1952, 1969, 1977, 1998 and 2007 are good overall with plenty of secondary years. They all had some early March cool shot with snow (generally not major in our area but noteworthy..please see my other thread for more analogs BTW) before the trough became focused in the West.

If the latest Roundy Guidance is correct, it is possible things turn ugly again around the beginning of spring.

[HM]

 

Seems like today's GFS suite is signaling the March week 2 warming we were talking about at the start of the week. The ECMWF should be interesting. I know we've seen some ridiculous analogs thrown around but using straight 500mb anomalies could get you in trouble here. I think 1952, 1969, 1977, 1998 and 2007 are good overall with plenty of secondary years. They all had some early March cool shot with snow (generally not major in our area but noteworthy..please see my other thread for more analogs BTW) before the trough became focused in the West.

If the latest Roundy Guidance is correct, it is possible things turn ugly again around the beginning of spring.

Regardless of snow totals, this is still goinng to be cool to watch unfold next week. The ECMWF says everyone from Texas to Greenland has the same type of air mass. Pretty freakin cool. I love convoluted setups.

[ptb127]

Seems like today's GFS suite is signaling the March week 2 warming we were talking about at the start of the week. The ECMWF should be interesting. I know we've seen some ridiculous analogs thrown around but using straight 500mb anomalies could get you in trouble here. I think 1952, 1969, 1977, 1998 and 2007 are good overall with plenty of secondary years. They all had some early March cool shot with snow (generally not major in our area but noteworthy..please see my other thread for more analogs BTW) before the trough became focused in the West.

If the latest Roundy Guidance is correct, it is possible things turn ugly again around the beginning of spring.

 

What's "Roundy Guidance"? And ugly as in cold and wet(not white)?

[HM]

 

What's "Roundy Guidance"? And ugly as in cold and wet(not white)?

 

Paul Roundy's MJO page (definitely bookmark):

http://www.atmos.albany.edu/facstaff/roundy/waves/

Ugly as in "not spring-like" ... white is a stretch so late in the season and I'm not sure we have much of a cold air source left by then; but hey, it is always possible.

[NJwinter23]

Seems like today's GFS suite is signaling the March week 2 warming we were talking about at the start of the week. The ECMWF should be interesting. I know we've seen some ridiculous analogs thrown around but using straight 500mb anomalies could get you in trouble here. I think 1952, 1969, 1977, 1998 and 2007 are good overall with plenty of secondary years. They all had some early March cool shot with snow (generally not major in our area but noteworthy..please see my other thread for more analogs BTW) before the trough became focused in the West.

If the latest Roundy Guidance is correct, it is possible things turn ugly again around the beginning of spring.

 

Was thinking the same thing watching the gfs suite the past 2 days...it seems like it is hinting the way out of the cool pattern in the current 11-15 day forecast. I would guess it is a correct signal with maybe a "rushed pattern change" caveat we often see out of the GFS, particularly some of the recent operational runs in this case...even on the euro ensembles you can see hints of troughs crashing into the west coast late in the run though.

 

I think the east coast is the last place to hold onto these worthless (for snow purposes) cool anomalies as the rest of the country warms up and canadian blocking fades..So with that being said im not sure how long the process from slight belows to normals to aboves takes after the first 7-10 days of Mar around these parts.

[NJwinter23]

And with that, there are now 4 dates from Feb-Mar 2010 on the latest CPC 6-10 day analogs, 2 from march 1981, early March 2001 and an honorary mention for early March 1993, cause I know HM loves that year. But I do agree that this is a tricky pattrn and wouldnt necessarily take the dates to heart as far as snow storm threats go

 

This is unrelated, but I'm amazed at how similar the same dates in early March 1981 were to early March 2001..1981 also looked like a failed phase for the mid-atl like 2001 was. 

 

http://www.meteo.psu.edu/~fxg1/NARR/2001/us0305j5.php

 

http://www.meteo.psu.edu/~fxg1/NARR/1981/us0306j5.php

[CoastalWx]

Was thinking the same thing watching the gfs suite the past 2 days...it seems like it is hinting the way out of the cool pattern in the current 11-15 day forecast. I would guess it is a correct signal with maybe a "rushed pattern change" caveat we often see out of the GFS, particularly some of the recent operational runs in this case...even on the euro ensembles you can see hints of troughs crashing into the west coast late in the run though.

 

I think the east coast is the last place to hold onto these worthless (for snow purposes) cool anomalies as the rest of the country warms up and canadian blocking fades..So with that being said im not sure how long the process from slight belows to normals to aboves takes after the first 7-10 days of Mar around these parts.

 

I still think the PNA may poss break down a little faster, but if you look at the EC ensembles..they are in no rush to break down. The ATL block is king and puts everything on hold.

[Heisy]

Looking at all the models there are 3 distinct shortwaves to keep an eye on. 

 

@ 126 GGEM hours you can see all 3 here. While specifics are different on each model you can see all 3 waves on each model. 

 

 

 

The EURO shows #1 farther east than any model, it then tries to create a second storm @ around Day 9-10 with wave #2, it crushes wave #3.

 

The GGEM phases #1 & #2, lifts the ULL into 50/50 position, it then keeps #3 very strong and turns it into a potential HECS (beautiful model run)

 

The GFS is pretty much like the EURO.

 

Who knows what will happen just laying it out there. 

 

 

[NaoPos]

Any word on the weeklies?

[tombo82685]

Any word on the weeklies?

Blocking right through like mon night run from what I gathered.

[NaoPos]

Maybe it's me, but the block and the +PNA look

Great, verbatim. But these ULL parked over top o us In the medium range kida scream cold & dry suppression city.

[Quakertown needs snow]

12z euro still crushes NE 3/1

[NaoPos]

12z euro still crushes NE 3/1

Actually gets a light snow event here in SEPA/EPA/NJ.

A little more digging, and quicker strengthening, we could be talking.

[Quakertown needs snow]

Actually gets a light snow event here in SEPA/EPA/NJ.

A little more digging, and quicker strengthening, we could be talking.

yeah saw that euro spitting some precip here with 850's well off shore but surface too warm?

don't care about snow as much locally when i'm not here to enjoy it

[NaoPos]

yeah saw that euro spitting some precip here with 850's well off shore but surface too warm?

don't care about snow as much locally when i'm not here to enjoy it

Well, we have sub 534 thicknesses in the area but surface temps are 40's.,

Bound to change next run anyway.

[NaoPos]

Pretty bullish analogs;