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Meteorological Autumn Pattern Discussion


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1 hour ago, Allsnow said:

The pac continues to be a huge pain for us. Until that improves it will be the same end result. It’s funny how the mjo will not be the issue to start December but the Pv will. If we didn’t have bad luck currently we wouldn’t have any luck at all

One of these days (years lol) your avatar will be reality.  

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We snuck a camera in to catch the reaction of Charlie, Tony, Tom & Shawn at today's European run briefing. Tom, I think you have to do something with your hair, just sayin'....  

Nov 8th thru Feb 18th?

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2 hours ago, susqushawn said:

How do 2 different patterns (nino vs nina) and differences in ocean temp anomalies lead to the same end result of garbage for us?

So far this year is very different from last year, hopefully that continues to be the case

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2 hours ago, susqushawn said:

How do 2 different patterns (nino vs nina) and differences in ocean temp anomalies lead to the same end result of garbage for us?

It’s mid November. I get the idea that  December is typically better in ninas than weak or moderate ninos, but we are in la la land in December.

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3 hours ago, susqushawn said:

How do 2 different patterns (nino vs nina) and differences in ocean temp anomalies lead to the same end result of garbage for us?

Well as Charlie stated, this time of year compared to last year things were much different. nino vs nina, very weak PV that allowed for high latitude blocking and big cold shots. In terms of sensible weather though from end of Dec through the rest of winter and starting off this late fall it's been the same. The record breaking pv last year has carried over into this fall so far. When you have such a strong PV being coupled with the troposphere it keeps all the cold air bottled up over the pole. Doesn't allow much blocking to occur at all. With all the cold up in the northern tier all the warmth is pushed to the mid latitudes with zonal flow and depending on where the mjo is a -pna/se ridge combo. In terms of mjo last year, while we were in a nino enso, we generally had nina tropical forcing. Nino tropical forcing generally 7-1 while nina is 3-6. Nina favors cold water in the phases we want which limits convection, while nino has warm water in the phases we want to allow convection. The insanely +IOD late fall into start of winter last year IMO caused the mjo to get stuck in nina phases with all the blossoming convection in the IO then traversed 3-4-5 then rotted as it got close to Australia hence why they had all the dry weather and wildfires. All the dying convection created a lot of subsidence in phases 7 and 8 which are golden phases for December. Later in the winter we did have some nino type forcing but by that time the PV was so ridiculously strong and coupled with the troposphere it just overwhelmed everything. 

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On 11/16/2020 at 7:05 PM, tombo82685 said:

Wanted to post this for @susqushawn to bring him nightmares 

ecmwf-ensemble-avg-namer-z500_anom_5day-6824000.png

 

I'm guilty of this just as everyone else, but when talking in the 10-15 day range of any ensemble we need to realize that the ensemble mean is made up of over 21 members to as much as 51 members on the EPS. These maps are 51 member runs compiled together to give us an H5 look. So inmost cases, these maps are very smoothed out, meaning the exact trough and ridge axis may be shorter and or larger than actually depicted when we actually get to verification time. Point in case here. We went from a broad zonal flow ripping across the country with the trough along the west coast and AK. To now below normal hgts beginning to form over the east as the trough location now looks to be a bit further offshore which allows a bit more ridging into the Rockies for some meridonal flowecmwf-ensemble-avg-namer-z500_anom_5day-6824000.png.dd9dd07dd0abccdf5c51f786aec2a533.png

 

We also have this which was posted last Thursday for day after Tgiving

D9E335AC-889C-4A44-AA2B-16AD3D5E6357.png.4a362e2060be54bc78230e2ddfe0664c.png.c66f796d1a09f67aeda27d68d95b8642.png

Because it was 15 days out, ens mean smooths everything out and will hone in finer detail as we get closer exact positions of troughs and ridges. They had the trough idea correct being west, but they were to far east with it on the west coast. As we got closer and there was more agreement amongst members the trough axis sharpened off more off shore which is allowing for a possible pna spike, be it probably transient. Which brings about meridonal flow and a cool shot which wasn't seen 5 days ago due to smoothing of the ens mean. So that look has now morphed into this

ecmwf-ensemble-avg-namer-z500_anom-6478400.png.698611689947c1991e789e4c1da75945.png

ecmwf-ensemble-avg-namer-z500_anom-6629600.png.ae114f88b46573825ac45236ec31e14e.png

 

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Eric's tweet backs up Tom's post (see his feed for more detail). More nino-like US jetstream towards the end of the month. This could be favorable for storm development along the SE coast.

Screenshot_2020-11-18 Eric Webb on Twitter.png

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1 hour ago, tombo82685 said:

I'm guilty of this just as everyone else, but when talking in the 10-15 day range of any ensemble we need to realize that the ensemble mean is made up of over 21 members to as much as 51 members on the EPS. These maps are 51 member runs compiled together to give us an H5 look. So inmost cases, these maps are very smoothed out, meaning the exact trough and ridge axis may be shorter and or larger than actually depicted when we actually get to verification time. Point in case here. We went from a broad zonal flow ripping across the country with the trough along the west coast and AK. To now below normal hgts beginning to form over the east as the trough location now looks to be a bit further offshore which allows a bit more ridging into the Rockies for some meridonal flowecmwf-ensemble-avg-namer-z500_anom_5day-6824000.png.dd9dd07dd0abccdf5c51f786aec2a533.png

 

We also have this which was posted last Thursday for day after Tgiving

D9E335AC-889C-4A44-AA2B-16AD3D5E6357.png.4a362e2060be54bc78230e2ddfe0664c.png.c66f796d1a09f67aeda27d68d95b8642.png

Because it was 15 days out, ens mean smooths everything out and will hone in finer detail as we get closer exact positions of troughs and ridges. They had the trough idea correct being west, but they were to far east with it on the west coast. As we got closer and there was more agreement amongst members the trough axis sharpeend off more off shore which is allowing for a possible pna spike, be it probably transient. Which brings about transient flow and a cool shot which wasn't seen 5 days ago due to g of the ens mean So that look has now morphed into this

ecmwf-ensemble-avg-namer-z500_anom-6478400.png.698611689947c1991e789e4c1da75945.png

ecmwf-ensemble-avg-namer-z500_anom-6629600.png.ae114f88b46573825ac45236ec31e14e.png

 

Great points.  I was sensing that based on this long range gfs ensemble look, showing the PV orient much farther west than typical, a mirroring trough on the EC seems logical vs a broad ridge across the entire Conus.  Until the EPS shows wholesale changes with PV and Pac flow orientation, we're left picking up the scraps on these 2-3 day cool shots.  

image.png.d0181a58628187306b7489710cff0385.png

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2 hours ago, susqushawn said:

Great points.  I was sensing that based on this long range gfs ensemble look, showing the PV orient much farther west than typical, a mirroring trough on the EC seems logical vs a broad ridge across the entire Conus.  Until the EPS shows wholesale changes with PV and Pac flow orientation, we're left picking up the scraps on these 2-3 day cool shots.  

image.png.d0181a58628187306b7489710cff0385.png

I guess that is what has me bummed the most. The Catalyst we need for wholesale changes are non existent currently. The 2-3 day cold shots aren’t going to get us anything 

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1 hour ago, Allsnow said:

I guess that is what has me bummed the most. The Catalyst we need for wholesale changes are non existent currently. The 2-3 day cold shots aren’t going to get us anything 

For the start of winter no, but as winter progresses yes.

Since we are borderline into December at this point, I started the new thread and will lock this one.

If anyone wants me to move a post over for continuity, let me know.

 

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