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December 2019 Med/Long Range Disco


Bob Chill
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Hmmm...that's nice to see that the EPS is coming around to the idea of a -EPO/-NAO pattern in early December.  Should be plenty of cold air around and with the trough in the west, that should keep the boundary sort of near us, but on balance to our south, and set up some potential overrunning events.  GEFS is certainly advertising a robust STJ to keep the pattern active/wet.  

 

gfs-ens_uv250_nhem_53.png

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12z EPS has the AO and the NAO crossing neutral then heading into + territory around Dec 3-4th.

GEFS strongly disagrees.

This is obviously something to monitor considering the importance (particularly the AO) to a favorable pattern for cold and snow here. Also the weeklies/climate/seasonal guidance are almost unanimously insistent on a +AO/NAO as we move into December, so there is that. Personally I am not concerned at this point given the beating the PV has taken and is forecast to continue taking going forward.

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

Ofc it's also important to realize that the AO and NAO phases are determined by surface pressure measurements(difference in pressures in the case of the NAO) in specific regions.

The numerical calc is 1000mb pressure but we all know what a good h5 look is no matter the numerical index. 

These type of long range op looks keep happening and it's intriguing. Not that I think the gfs is right or anything but seeing these solutions are a potential clue that an extreme blocking event is possible

 

gfs_z500a_nhem_53.png

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17 minutes ago, Bob Chill said:

The numerical calc is 1000mb pressure but we all know what a good h5 look is no matter the numerical index. 

These type of long range op looks keep happening and it's intriguing. Not that I think the gfs is right or anything but seeing these solutions are a potential clue that an extreme blocking event is possible

 

gfs_z500a_nhem_53.png

I was just looking at the LR GFS from 18z just for kicks and noted how convoluted of a pattern is appeared with a massive positive SD anomaly over the Aleutians and a fairly crud PAC BUT up top and the N Atl actually allows for workable conditions. Might be venturing into a season where we see some crud looks yet miraculously they deliver? We can hope anyway and tbh I wouldnt be surprised. We are sort of due even tho I realize that isnt how science works.

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17 minutes ago, Bob Chill said:

The numerical calc is 1000mb pressure but we all know what a good h5 look is no matter the numerical index. 

These type of long range op looks keep happening and it's intriguing. Not that I think the gfs is right or anything but seeing these solutions are a potential clue that an extreme blocking event is possible

 

Absolutely. But at the same time, there is clearly a correlation, in the same way we evaluate 500 mb heights and make reasonable assumptions about the mean temperature in the column below that point, as well as using it as a general (pretty accurate) indication of surface pressures and temps.

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37 minutes ago, WxUSAF said:

As @Bob Chill posted, 18z GFS shows that December 3-4th threat window. Boundary doesn’t get dragged far enough south, but interesting. 

Yea man, I keep liking the entry into Dec more and more. The big epo ridge makes complete sense and is what I've been expecting to roll forward. The nao is even more interesting because it's in the med range and all models agree on it.

These types of features can be stubborn and models don't do well with figuring out when it's going to relax. My gut says the neg nao will likely be stubborn and it's happening at a perfect time. We need extra help through most of Dec. Get the ao,nao, and epo working in our favor and it's actually not that hard to get an event out of it. 

I'm expecting the eps to cave to the gefs with the nao. We'll have a stout neg nao in just 4-5 days...

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6 minutes ago, Ralph Wiggum said:

I feel like with the flip of a switch many posters are back to looking past 240 hours and getting their hopes up. And based on a HH op run at that. I admittedly took a peek but I urge optimistic caution lest we forget last winter.

I'm excited about the med term and what it implies down the line... in just 4-5 days we should have the strongest -nao we've seen early during season since 2010. Complete agreement the upper level ridge closes off and parks for a while.

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2 minutes ago, Bob Chill said:

I'm excited about the med term and what it implies down the line... in just 4-5 days we should have the strongest -nao we've seen early during season since 2010. Complete agreement the upper level ridge closes off and parks for a while.

If it wasn’t for the -NAO the East would burst into flames with that h5 look.. 

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4 minutes ago, Bob Chill said:

I'm excited about the med term and what it implies down the line... in just 4-5 days we should have the strongest -nao we've seen early during season since 2010. Complete agreement the upper level ridge closes off and parks for a while.

That is the best and most significant development so far. The high latitudes seem to want to cycle between ok and great so far. Let’s keep that going. 

The only thing I’m paying attention to long range is how the forecasted puke pattern of the seasonals continues to get pushed back. A week ago we were saying how it continues to be just outside ensemble range.  Another week later and it’s still outside realistic guidance range.  Let’s keep that going too.  Ive been skeptical but I’m about another week from firmly believing that look is just another seasonal guidance mirage. 

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2 minutes ago, BristowWx said:

If it wasn’t for the -NAO the East would burst into flames with that h5 look.. 

Yep, the whole atmosphere is full of good and bad features upstream and down. Normally a tendency for a -pna is a dagger in our area with one exception... add in a -nao. 

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14 minutes ago, Bob Chill said:

I'm excited about the med term and what it implies down the line... in just 4-5 days we should have the strongest -nao we've seen early during season since 2010. Complete agreement the upper level ridge closes off and parks for a while.

It was noted yesterday on some of the ens that those looks.may have legs as you could see some of the transition by days 8ish. So I'm with you and when u r optimistic that's not a bad thing. Just urging caution for some on any specific surface solutions at 384hrs+ lol.

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3 minutes ago, psuhoffman said:

That is the best and most significant development so far. The high latitudes seem to want to cycle between ok and great so far. Let’s keep that going. 

The only thing I’m paying attention to long range is how the forecasted puke pattern of the seasonals continues to get pushed back. A week ago we were saying how it continues to be just outside ensemble range.  Another week later and it’s still outside realistic guidance range.  Let’s keep that going too.  Ive been skeptical but I’m about another week from firmly believing that look is just another seasonal guidance mirage. 

Yea, we seem to be getting played similar to last year except this time it's breaking in our favor. 

Cfs weeklies have been a total dog turd lately. Here's week 2 from a week ago:

cfs-avg_z500aMean_nhem_2.png

 

A week later week 1 looks like this:

cfs-avg_z500aMean_nhem_1.png

 

Completely missed the -nao from just 2 weeks out. Lol. Anyone who worries about the crappy look on the cfs for weeks 3+ needs to look at these panels and ignore weekly/seasonal guidance. 

My skepticism of Dec being good is slowly becoming confidence that we kick off met winter tracking threats in the med term.

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9 minutes ago, psuhoffman said:

You mean we would have almost every December pattern the last 5 years?  

Yes.  You are correct sir.  It’s been a painful run.  Last year nearly killed me.  Actually my tombstone says died in 2019...so not nearly..just dead

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12 minutes ago, Ralph Wiggum said:

It was noted yesterday on some of the ens that those looks.may have legs as you could see some of the transition by days 8ish. So I'm with you and when u r optimistic that's not a bad thing. Just urging caution for some on any specific surface solutions at 384hrs+ lol.

18z gefs is loaded with members showing height patterns that make me think snowstorms are possible in early Dec. Looks like an active pattern with plenty of cold near or overhead. STJ would be juiced on most of these solutions too

f384.gif

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