Medium/Long Range thread

[Mike.Ventrice]

Cool. Is that index based on the EOFs of the 500 hPa height field? If you used an EOF analysis, I'm curious to know what the EOFs look like and how much variance they explain.

 

It's based off 1000 hPa geoheights using a box 20N-90N, all longitudes. It's built slightly different that CPC, I'm using daily averaged fields, and normalizing based off the daily fields standard deviation.

 

Here's the leading EOF:

[am19psu]

let me know your thoughts...

March sucked.

[fsu_wxgirl]

What, no grumpy cat? 

March sucked.

[tombo82685]

Cool. Is that index based on the EOFs of the 500 hPa height field? If you used an EOF analysis, I'm curious to know what the EOFs look like and how much variance they explain.

Mike, great diagram, i have a question though. Those phases are they like the mjo where each month correlates to a different phase for cold vs warm?

[ptb127]

I am not sure what the diagram even shows?

[am19psu]

Hi guys,

 

Been pretty busy as of late but I managed to find some time to try something new... let me know your thoughts...

 

So this looks pretty cool, Mike. Have you created monthly composites for the phases? Obviously, without some accompanying images, I can't really comment on the applicability to short or medium range forecasting.

[Mike.Ventrice]

Mike, great diagram, i have a question though. Those phases are they like the mjo where each month correlates to a different phase for cold vs warm?

 

 

I am not sure what the diagram even shows?

 

So the only thing I know right now is if the line is in the top part of the diagram, it's a positive AO. The bottom = negative AO.  The different phases I'm not sure what they mean physically yet... Will do after I make some composites

[Mike.Ventrice]

So this looks pretty cool, Mike. Have you created monthly composites for the phases? Obviously, without some accompanying images, I can't really comment on the applicability to short or medium range forecasting.

 

Thanks Adam. I haven't created the composites yet... in process of doing so.  I'll probably do a comp for each month and share the links here once I get them worked up.

[Mike.Ventrice]

Looks like another period of mid 70s to 80s for PHL is possible between 4/16-4/19. 

[Mike.Ventrice]

Just popped out an archive of AO phase space diagrams back to 1980. I just did two months at a time so the figures wouldn't get too busy: http://www.atmos.albany.edu/student/ventrice/AO/

[tombo82685]

Just popped out an archive of AO phase space diagrams back to 1980. I just did two months at a time so the figures wouldn't get too busy: http://www.atmos.albany.edu/student/ventrice/AO/

mike, in reading those diagrams would phases 1,2,5,6 be -ao?

[Mike.Ventrice]

mike, in reading those diagrams would phases 1,2,5,6 be -ao?

 

I believe phases 1,2,3,4 all represent a -AO, where 5,6,7,8 represent a +AO. The zero line on the y-axis is the barrier for +AO/-AO

[tombo82685]

I believe phases 1,2,3,4 all represent a -AO, where 5,6,7,8 represent a +AO. The zero line on the y-axis is the barrier for +AO/-AO

i see, are these diagrams just going to be composites or actual forecasts out in time?

[Mike.Ventrice]

i see, are these diagrams just going to be composites or actual forecasts out in time?

 

The AO phase space diagram on my webpage is of the past two months with a 7 day GFS op forecast (take it for what it's worth...) I haven't made composites yet... will do sometime probably next week.

[NJwinter23]

So the only thing I know right now is if the line is in the top part of the diagram, it's a positive AO. The bottom = negative AO.  The different phases I'm not sure what they mean physically yet... Will do after I make some composites

 

lol ok I thought i was missing something! This is a cool idea mike, looking forward to seeing composites.

[Voyager]

Looks like another period of mid 70s to 80s for PHL is possible between 4/16-4/19. 

 

I'll admit to not paying attention to models and such since I have a bad work schedule right now, but I saw on TV this morning that after this upcoming warm spell this week, next week (4/20 - 4/26) is forecasted to be below normal.

[Rainshadow]

Yeah the NAEFS has 4/21 to 4/28 below normal.

[am19psu]

All of the modeling during that period is dependent on the MJO dying... Just fyi, something to watch for bust potential

[Mike.Ventrice]

All of the modeling during that period is dependent on the MJO dying... Just fyi, something to watch for bust potential

Agreed... Taking a look at the European ensemble spread using hindcast forecasts, just for Bismarck, the spread between the daily highs for 4/23-4/26 is massive! It shows the coldest members with highs sub 35F and the warmest members with highs warmer than 70F. You can see similar spread for cities in the East as well... for PHL alone there are members with highs in the upper 50s where the warmest members are above 90!! We are entering a period of low model predictability and is likely a result of the models stuggling with tropical convection forcing associated with the MJO traversing the Pacific. This is a time where MJO will accelerate in eastward phase speed from its normal 5-6 m/s to anywhere from 8-20 m/s, taking the shape of a convectively coupled atmospheric Kelvin wave.. which is kind of hinted in the below time-long plots of space-time filtered MJO (dashed contours upper-level divergent phase), and likewise for the CCKW

 

 

 

 

 

 

Note the center points in these figures are different,the MJO plot is centered about the dateline, the CCKW plot is centered about the Prime Meridian.

 

So in my opinion in the plot above, the MJO has already sped up a bit already in the last week. Just for fun, the CCKW that currently is driving the main active core of convection associated wtih the MJO spawned a series of southern hemisphere tropical cyclones in the wake of its passage.

 

Now something that I am finding odd is that during times where the MJO transitions from the Maritime Continent to the West Pacific is often preceded by a strong Global Wind Oscillation signal starting in phase 4-5, and circuiting around to phase 7-8. However it appears the the GWO is moving down into the "Warm" eastern two thirds of the U.S. phases 1-2. 

 

 

 

Just thinking out loud here but I wonder if we'll see the two indices act more as of pair when the MJO-CCKW signal radiates across the Western Hemisphere and back into the IO probably sometime around three weeks. Nevertheless, like Adam, I could see a solution warmer than average over the eastern two thirds of the nation during week 2... this could very well be a big BUST for the dyn models. I love using the Ensembles for week 2 and if you take alook at them, they pretty much just show weak anomalies for the East as I'm sure members are cancelling out one another where some are hot and some are cold.

 

The AO phase space diagram would suggest we are in a "warm" state, or a positive AO state...

 

 

The question remains whether you can still get very cold air outbreaks during times when the AO index is positive, but trends negative. I'm not sure... but I could see a mini loop in the next week and a trend upward thereafter in week 2 to increasing AO values.

[Mitchell Gaines]

Friday looks like a classic low CAPE high shear squall line event. 

[Mitchell Gaines]

Friday looks like a classic low CAPE high shear squall line event. 

LLJ not as strong as modeled yesturday. I'd like to see the LLJ closer to 70-80 kts, perhpas a bit to bullish with this.

[ptb127]

thank you guys for keeping this updated..

 

hoping for a "suddenly its summer" pattern..

[Mike.Ventrice]

Hi guys, made some temp comps for that AO index I shared earlier.. here's the link: http://www.atmos.albany.edu/student/ventrice/real_time/maps/AO_comps/AO_comp.html

[am19psu]

Wow, those aren't quite the wintertime loading patterns I was expecting, particularly P6.

[Mike.Ventrice]

Wow, those aren't quite the wintertime loading patterns I was expecting, particularly P6.

 

Yeah I wasn't expecting cold in p6 either... hopefully 500 mb height patterns will shed some more light.

[Quakertown needs snow]

Geeze, a little trough late next week ?

[HM]

 

Yeah I wasn't expecting cold in p6 either... hopefully 500 mb height patterns will shed some more light.

Looking forward to the 500mb / NH graphics. I noticed p6 had the lowest n so perhaps this is just noise (with cold years during the +PDO era screwing up the correlation).

[ptb127]

Is the -NAO pattern starting to break down in a more permanent fashion?  Stratospheric support is waning.. and what impact would the recent solar flare have on stratospheric cooling? I remember in the past a flare caused cooling. significantly at that.

[Mike.Ventrice]

Hi guys, I found a bug in my code where the phases were being plotted in the wrong location in the panel. Here is the updated 925 hPa temperature anomaly composites for the AO phase space diagram: http://www.atmos.albany.edu/student/ventrice/real_time/maps/AO_comps/AO_comp.html

 

 

Also, have constructed 500 hPa geopotential height anomalies here:

http://www.atmos.albany.edu/student/ventrice/real_time/maps/AO_comps/AO_height_500.html

 

Definitely looks much better and understandable now

[HM]

Last night's ECMWF has the final warming finally at 1 hpa towards 4/25 (early averaged wind at 60N). It is predicted to lead 10 hpa, which has implications on how this may manifest (there are some FW that start at 10 hpa or have no clear pattern). How the stratospheric "tornado" breaks down can help us predict the AO/NAO to some extent. There have been correlations shown for 10 hpa zonal wind and the AO/NAO relationship.

Based on what's going on with the AO/NAO now and the ECMWF stratospheric forecasts, my guess is 10hpa zonal winds go negative around 5/5-10. This means the potential for a -AO/NAO regime developing then and peaking mid-May. Depending on how that manifests, which has a lot to do with intraseasonal oscillations (current projections would lack robust Indonesian/W. PAc forcing during first half of May, possibly supporting a colder picture for us), will determine if we can put a lid on the S-C US anticyclone from hell.