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December 2019 Med/Long Range Disco


Bob Chill
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Several notable Decembers show up in the top 10 analogs from the GEFS superensembles today.

December 1963 is the top analog.  Dec 2002, 2009 also show up.  1989 is in there, I know that was a somewhat frustrating month snowfall wise but it certainly was cold!  Of course the problem with the long range analogs is they are only valid assuming the advertised pattern on the GEFS is correct.  

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13 minutes ago, psuhoffman said:

Several notable Decembers show up in the top 10 analogs from the GEFS superensembles today.

December 1963 is the top analog.  Dec 2002, 2009 also show up.  1989 is in there, I know that was a somewhat frustrating month snowfall wise but it certainly was cold!  Of course the problem with the long range analogs is they are only valid assuming the advertised pattern on the GEFS is correct.  

4 seasons style?

Seriously though, I cringe at a mention of 89. Of course a repeat of December 1989 wouldn’t necessarily lead to a Jan/Feb 1990, but still ..

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11 minutes ago, WinterWxLuvr said:

4 seasons style?

Seriously though, I cringe at a mention of 89. Of course a repeat of December 1989 wouldn’t necessarily lead to a Jan/Feb 1990, but still ..

Yea the flip sucked but that’s looking way too far out to use analogs that way. Also our area did manage a couple more snowfalls even during the crappy warm Jan/Feb. 

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10 hours ago, Bob Chill said:

This post is for @leesburg 04

Seems we now have unanimous agreement for an amplified -epo/+nao pattern during the first week of December. Should deliver some sig cold but that type of pattern can easily shuffle around to a disasterous pattern. Don't be surprised if meltdowns begin within a week. 

lol funny sht. And at the risk of (further) inducing panic, there is a decent chance the pattern is ultimately heading in an unfavorable direction. The EPS especially in the LR has a look of almost every index being in the "wrong" phase lol. At this point it looks like we are gonna see lots of blue in the HL regions, so we really need the PNA/EPO to work for us. Reality is, December in the MA almost always features some warmth, and ofc Nino and MJO impacts. My advice for those predisposed to panic to is to stay focused on the next 10 days or so. Looks active and generally cold.

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

lol funny sht. And at the risk of (further) inducing panic, there is a decent chance the pattern is heading in an unfavorable direction. The EPS especially in the LR has a look of almost every index being in the "wrong" phase lol. At this point it looks like we are gonna to see lots of blue in the HL regions, so we really need the PNA/EPO to work for us. Reality is, December in the MA almost always features some warmth, and ofc Nino and MJO impacts. My advice for those predisposed to panic to is to stay focused on the next 10 days. Looks active and generally cold.

I really won't be sweating the details of anything beyond 10 days at this point myself. Day 10 or so is where we see the 500 mb PV probably begins its migration over the pole onto our side of the globe (looking more and more likely) and where it eventually lands will have a huge impact as far as our weather here in the east. And the details on that are still to be decided especially when I see what is occurring in the strat. As far as I am concerned it is a flip of the coin as to whether we see a reload with a massive dump into the west or we see the arctic express set up for a time or anything in between for that matter. Me being a :weenie: I favor the cold and possibly snowy scenario. At least until I don't. :whistle:

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9 minutes ago, showmethesnow said:

I really won't be sweating the details of anything beyond 10 days at this point myself. Day 10 or so is where we see the 500 mb PV probably begins its migration over the pole onto our side of the globe (looking more and more likely) and where it eventually lands will have a huge impact as far as our weather here in the east. And the details on that are still to be decided especially when I see what is occurring in the strat. As far as I am concerned it is a flip of the coin as to whether we see a reload with a massive dump into the west or we see the arctic express set up for a time or anything in between for that matter. Me being a :weenie: I favor the cold and possibly snowy scenario. At least until I don't. :whistle:

Yeah worrying about what might happen beyond D15 is not productive given what looks like a favorable period upcoming. The Dec 3-8 time frame continues to look pretty interesting. Plenty of NS energy and  pieces of energy in the SS as well, with cold air in the east. Hopefully something comes together. Otherwise we can enjoy cold and dry followed by a warmup.;)

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Yeah I still really like the 3rd-4th period. Eps looks tasty for that time. Ensembles have moved toward more +PNA in that time as well. Might also be worth keeping a small eye on the big December 1 cutter. That airmass is trending colder ahead of the storm and if a piece can break off, the flow will carry it to our south. Overnight gfs and GGEM have a threat of front end frozen/freezing precip. 

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Hadn't really been paying too much attention to what we were see upstairs as far as the strat pv the last week or two. Decided to take a glance this morning because it looks as if the 500 mb pv is crossing onto our side of the globe.

Pulled these up initially and thought this is pretty good. Applying good pressure to the 10 mb pv at day 3.

day310mbtemps.gif.553880c14690c5cbe351a408023041b3.gif

 

day310mbheights.gif.f78989185d46194eaa05218c7cc90838.gif

 

 

Then I came across this at day 16. Now I don't know how this rates historically as far as warming but the fact that it is off the scale gives me the impression that this is fairly impressive warmth. Add in the fact that this is centered squarely over the pole with both the warmth and the positive height anomalies and you just know the 10 mb pv is taking a major beating. 

day1610mbtemps.gif.0d0094ca924c6836e415d79854c47a80.gif

 

day1610mbheights.gif.4d8df4ba839ae1dd3a4aa3c864101bd0.gif

 

Not surprisingly if we look at the 10 mb zonal winds (shows strength of pv) through this period of time we are seeing a steep dip with the latest GEFS run within the members. In fact we see several that are actually showing a reversal (black circle).

zonaldip.gif.02e4de76e54393c912d7dbb143ace8a9.gif

 

And this is not an aberration as we have seen this on the last day of runs though not quite as extreme.

lastdayrunszonaldip.gif.d858edc5411fac67490daa70c6b110f5.gif 

As far as whether the Euro agrees it is hard to say as I have limited access to maps for the strat and they only are available with the op up to 240 hr before we see this occur. I will say though that the precursor to this event is showing up by hour 240.

One last comment, this warming is occurring initially at the extreme upper levels of the atmosphere and not warmth propagating upper wards from the lower levels. And if I recall correctly this has far more impact on the pv then the other evolution.

 

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8 minutes ago, showmethesnow said:

Hadn't really been paying too much attention to what we were see upstairs as far as the strat pv the last week or two. Decided to take a glance this morning because it looks as if the 500 mb pv is crossing onto our side of the globe.

 

 

 

I have been watching it and the advertised temps in the upper strat have been on fire. Funny you made this post as I was just looking at the latests GEFS Strat stuff. I like looking at the 50 mb panels as well as it would seem to me to be more representative of how it will couple to the troposphere. This is way out there but would probably provide some serious cold in the east if it verified.

1575849600-qADDptpmeg8.png

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Proof that really locking onto any one particular ens mean solution past day 10 even day 7 is dangerous territory. Where we were once seeing ridging in the NAO region across the board is now being replaced medium range with the shortest-lived -NAO ever and going 180 replaced by an anchoring PV potentially. Not the worst look.....think quick hits/progressive. EPO ridge should help with the cold. Of course this is purely speculation post 180 hours. But I think the SPV battering (which has been forecast relatively well actually) is starting to throw fits at the trop. Going to be interesting to see how it plays out...a SSWE can be linked to a reshuffle of the 500mb hemispheric pattern....not clear where we will end up. I hope the look of lots of blues up top and oranges down at ML doesnt verify personally, but we've seen worse. I guess cold is better than warmth right?

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

 

I have been watching it and the advertised temps in the upper strat have been on fire. Funny you made this post as I was just looking at the latests GEFS Strat stuff. I like looking at the 50 mb panels as well as it would seem to me to be more representative of how it will couple to the troposphere. This is way out there but would probably provide some serious cold in the east if it verified.

1575849600-qADDptpmeg8.png

Pretty much what I use the 50 mb for as well though I do like to get an idea of where the warmth is originating as well. If I had my choice though I would rather like to see the 100 mb and especially the 200 mb (where the tropopause is located), think these regions would give you a much clearer idea on the coupling between the strat and trop. Thought @frdhad provided a link to a site for that that I bookmarked but after looking I am guessing not.

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3 minutes ago, showmethesnow said:

Pretty much what I use the 50 mb for as well though I do like to get an idea of where the warmth is originating as well. If I had my choice though I would rather like to see the 100 mb and especially the 200 mb (where the tropopause is located), think these regions would give you a much clearer idea on the coupling between the strat and trop. Thought @frdhad provided a link to a site for that that I bookmarked but after looking I am guessing not.

This one? :D

https://simonleewx.com/polar-vortex-forecasts/

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

 

Just started glancing over this site and just read something and went DUH!!! I had totally forgotten that the GFS and the GEFS are not really the same models. GFS is the new FV3 dynamical core whereas the GEFS won't be upgraded until sometime in 2020. Pretty much gives us a disconnect especially when we get to the longer leads on the forecasts.

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1 minute ago, showmethesnow said:

 

Just started glancing over this site and just read something and went DUH!!! I had totally forgotten that the GFS and the GEFS are not really the same models. GFS is the new FV3 dynamical core whereas the GEFS won't be upgraded until sometime in 2020. Pretty much gives us a disconnect especially when we get to the longer leads on the forecasts.

Yeah it's odd. It will be "fun" when we have a real threat in range and are trying to glean something useful- like from the snowfall means on the ensembles.

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10 minutes ago, Wonderdog said:

gfs-ens_z500a_us_44.png

 

Is this close to the kind of look we want at h5?

Not so much. It's the time period a couple of days before this that is of some interest. This is pretty much a suppressive look where we are locked in the cold. Can score some NS energy dropping down (clippers) but that would probably pretty much be it. 

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51 minutes ago, showmethesnow said:

. Thought @frdhad provided a link to a site for that that I bookmarked but after looking I am guessing not.

Sorry for the delay, but glad to see CAPE could help you . Kids back for the week from college,  had to make an early food run .  

You might be interested showme that according to to Simon, during the month of November so far,  the GFS has been doing a good job in verification involving the strat forecasts in the 11 day time period.    

Will be interesting to see how things play out, enjoyed your post above. 

 

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1 hour ago, WxUSAF said:

Yeah I still really like the 3rd-4th period. Eps looks tasty for that time. Ensembles have moved toward more +PNA in that time as well. Might also be worth keeping a small eye on the big December 1 cutter. That airmass is trending colder ahead of the storm and if a piece can break off, the flow will carry it to our south. Overnight gfs and GGEM have a threat of front end frozen/freezing precip. 

GEFS is really starting to pick up on the DEC 1 possibilities the last few runs. Saw the 18z yesterday evening and thought there might be possibilities and the following runs have been improving on it. 

ETA: Actually the GEFS is more so centered on the 2nd then the 1'st. 

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