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Bob Chill

December 2019 Med/Long Range Disco

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1 hour ago, nj2va said:

If the AO is forecasted to be so abnormally +, question for the pros...why do we have this map?  Slightly +PNA driving that? 

E05551A9-F175-4AB7-A50B-25CB434A3DB5.png

That is truly fascination, how in the world could that 2m anomaly map coincide with that H5 look, unless the GEFS ensemble mean is way different than the OP?

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15 minutes ago, jaydreb said:

0z GFS comes close to giving us our 12/5 snow.  This time period still bears watching (before we break out the flip flops shorts).  

Wait a minute...How are we back on that exact date as our snow miss (and subsequent warm-up) last year? Can someone please turn off the atmospheric tape recorder? Lol (different setup, I know...but I'm wondering if the result repeats itself just to troll us, lol)

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EPS has been muting the +AO/NAO look in recent runs, and is now suggesting it will indeed be short lived.  Showmethesnow highlighted this in his write up yesterday morning. And just like that, we have this advertised look 10 days into December.

1575936000-8UuINjJHyt4.png

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Just a few small changes on the overnight EPS. Good ones @MDstorm so you can keep reading the post. Maybe they will get some to back off the ledge... until the next run. :D

As I mentioned yesterday for various reasons I look at 500's to get a read on the AO state on the surface. I find the 500's tend to give me a more accurate read on what to expect then just looking at surface pressures especially when we are beyond the short and mid ranges (7+ days out).

Now admittedly I cringed a little when I got a chance to look over the mid day runs early yesterday evening. Spent some time earlier in the day trying to calm some fears only to come across this. Not what I really wanted to see. Consolidated PV where the EPS was now downplaying the possibility of a portion of the pv migrating over to our side which I feel is key. The only positives I see here, if you want to call them that, are the fact that the pv is displaced a little bit off the pole, the stronger neg anomalies are not centered over the pv and that we aren't seeing extreme neg departures with those anomalies. To me this look suggests a strong 2 or even possibly a 3 SD +AO. Now we have had some projected 4/5 SD +AO thrown out over the last few days. This look isn't close and I have yet to see a look that comes close over these last few days. Believe me, when you see it you will know it. A huge deep purple blob and circular pv located squarely over the pole. It is a look that has left me whimpering, lying on the floor in a fetal position on occasion over the years.

 

1373764617_AO.gif.a65e60515353dadef427489a01f70f12.gif

 

Okay now lets look at the overnight run. Notice some changes? We are now seeing the ridging into Greenland I had mentioned the possibility of yesterday. The EPO is once again there. We are seeing height builds up to and over the pole. The EPS is once again hitting on a piece of pv rotating over to our side and now is throwing in one over towards the Aleutians as well. Note also that the neg anomalies are now situated off of the pvs to their south. This look here suggests to me that we would see a nuetralish looking AO on the surface.

 

NeutAO.gif.faa1b204a23ffb24a4397c3ebbefa795.gif

 

Let's look at the surface of the above. Yesterday 12 Z is looking pretty rough. Lower pressures are consolidated and located squarely under the PV depicted at 500's. Only somewhat saving grace is that are displaced off the pole somewhat. And when you look at the AO index we are seeing 2 SD that is suggested from the 500's.

756013012_AOsurface.gif.a1334ee03a508f06eed1b3239756eb2a.gif

 

Now look at the latest run. We now are seeing a split of the low pressure anomalies with the departures not as strong as the previous. Just eyeballing this I would say this is probably a weak positive. Looking at the index though has this as a weak neg. Looking at the AO progression we see a brief spike (3/4 days) to a +3 SD before it drops again into the -AO category.  And I think this spike is the result of the migration over the pole of a piece of PV.

 

AOsurface.gif.26197a064628af217a8760dc8f5788f6.gif

 

One other thing I would like to show. Notice the configuration of the pv and where the pieces of  the pv are located as well as the ridging shaping it?

pv.gif.5d5c1e4515b9844db08e28de9f7c838d.gif

 

Now look at what had believed was a rough idea of a possibility yesterday knowing the tendencies/ bias' of the models so far this year as well what the tendencies with actual verification were. Not too shabby. We are seeing the EPO ridging as well as the Greenland ridging. Seeing a portion of the pv on the other side of the globe. Even seeing a piece of the PV towards the Aleutians that I thought was possible. The one thing we aren't seeing as of yet is the pv dropping much farther south that I believe is a possibility.

possibility.gif.a78f52dc1e30a7d6024dbae6a7e8054d.gif

 

 

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

The 0z GEFS also has a notable lack of blue up top at the end of its run, with hints of ridging building back into the NAO space.

Like the EPS better but at the very end of the GEFS is very promising.

eta: In regards to the AO/NAO. Haven't really looked into other areas as of yet.

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Looking over the Dec 2nd time period and you couldn't tell it by just looking at the surface but the EPS did improved. Saw an improvement at 500's. Still having the same issues as before though. Ns energy is still dropping down on top of the storm breaking down the heights. As long as we continue to see this occur this period of time is pretty much dead in the water. GEFS was pretty much a wash. Some improvements, some not so good. Same issue though, the NS energy drop.

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Great analysis, showme....good morning coffee reading material. Interesting looping the GEFS and watching the low heights contract to the HL and then dissolve toward the end of the run and lower heights appear to be on their way back to the Mid Lats.

Another positive result of that vortex potentially splitting is the ridging response in the Kara sea region.  Muted now but combined with an epo ridge can send the AO downhill in a hurry and would be obviously a very cold signal....just in time for the holiday run up!

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35 minutes ago, showmethesnow said:

Looking over the Dec 2nd time period and you couldn't tell it by just looking at the surface but the EPS did improved. Saw an improvement at 500's. Still having the same issues as before though. Ns energy is still dropping down on top of the storm breaking down the heights. As long as we continue to see this occur this period of time is pretty much dead in the water. GEFS was pretty much a wash. Some improvements, some not so good. Same issue though, the NS energy drop.

OP Euro was a little improvement.  Ukmet actually is a bit weaker with the  sw energy ejecting and doesn't have near as strong as a primary low . That definitely helps not to pump hieghts up out ahead . Here's the UK day 7.  I know most are looking past this timeframe but this is still long range centered on day 7 or so . Lots can change for sure as u know . 

 

 

 

PhotoPictureResizer_191125_063514588_crop_1440x1940.jpg

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18 minutes ago, poolz1 said:

Great analysis, showme....good morning coffee reading material. Interesting looping the GEFS and watching the low heights contract to the HL and then dissolve toward the end of the run and lower heights appear to be on their way back to the Mid Lats.

Another positive result of that vortex potentially splitting is the ridging response in the Kara sea region.  Muted now but combined with an epo ridge can send the AO downhill in a hurry and would be obviously a very cold signal....just in time for the holiday run up!

If you look at the very end of the run you see the possibility of ridge bridging across the pole between the EPO/NAO, EPO/Central Russia, NAO/Russia or even possibly all three. Not a bad place to be for our winter chances. Of course this look will probably be gone the next run. :lol:

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6 minutes ago, anotherman said:

Just my opinion, but anyone who uses the models to make any sort of forecast over 7 days must be out of their minds.  The swings have been wild.

Who is doing that?

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I'm suggesting we move talks of Webb to banter. 

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2 hours ago, anotherman said:

No one in particular here, but I just have to laugh when people get into arguments about the long range, like this guy everyone keeps posting about (Webb).  It changes drastically every 6 hours.

Sensible wx (more specifically individual threats) has no skill out in time. Where the line of believable vs unbelievable is drawn is up to the individual. If you want to believe a d7+ op with a snow event then do it. Do it enough and you'll stop doing it. lol. However, large scale hemispheric pattern drivers like the pac jet, AO, EPO, and other major drivers can be predicted with some skill way out in time. Sometimes 2 weeks and beyond. Sometimes months at a time. I think it's completely fine (and healthy) to discuss the big picture and what it generally means. I'm sure most agree there. When I post about long range stuff I'm seeing it from only 1 perspective... is it a shutout or not and why. Right now I'm looking for a real threat window to emerge and I'll certainly post about it if/when I see something. Even if it's 2 weeks away. 

I'll agree that the real disasterous look is backing off but I still don't like the overall big picture for snow chances in these parts on any piece of guidance right now. If the +AO is in fact temporary and things start to shuffle back to something decent then it will happen at a time when it's not extremely hard to snow here. Outside of a flukey flawed lucky event, I don't expect much tracking for a while. The first week of Dec could offer something flukey/flawed but overall it's not a good looking period. Beyond that looks worse. Beyond that is starting to look less worse but not close.

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Starting to think we should be paying less attention to the WAA front end of next weekends storm and more attention to squeezing some snow out of the ULL as it moves past overnight Sunday into Monday. 

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9 minutes ago, WxUSAF said:

Starting to think we should be paying less attention to the WAA front end of next weekends storm and more attention to squeezing some snow out of the ULL as it moves past overnight Sunday into Monday. 

Def agree... don't bother looking to the NE either for next weekend on the 12z GFS

12z GFS has the mountains eat up any chance at some ULL love though

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42 minutes ago, WxUSAF said:

Starting to think we should be paying less attention to the WAA front end of next weekends storm and more attention to squeezing some snow out of the ULL as it moves past overnight Sunday into Monday. 

Yea, it's a pretty powerful ULL as it crosses the region but taking an unusual course SE as it moves from OH to off the coast. Move the center of this bowling ball 150-200 mi south somewhere around ROA and the best dynamics/instability will cross by in a pretty sweet spot. Convective style snow from a closed ULL is one of my personal faves. Big omegas = big dendrites = high ratio pounding = weenie party. Even if short lived. 

gfs_z500_vort_us_26.png

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3 minutes ago, Bob Chill said:

Yea, it's a pretty powerful ULL as it crosses the region but taking an unusual course SE as it moves from OH to off the coast. Move the center of this bowling ball 150-200 mi south somewhere around ROA and the best dynamics/instability will cross by in a pretty sweet spot. Convective style snow from a closed ULL is one of my personal faves. Big omegas = big dendrites = high ratio pounding = weenie party. Even if short lived. 

gfs_z500_vort_us_26.png

Problem this go around is the mountains per the 12z GFS eat up all the precip and barely gets even flurries over to us... not sure it would happen that way but its what it shows even with the powerful ULL moving through us

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1 minute ago, Bob Chill said:

Yea, it's a pretty powerful ULL as it crosses the region but taking an unusual course SE as it moves from OH to off the coast. Move the center of this bowling ball 150-200 mi south somewhere around ROA and the best dynamics/instability will cross by in a pretty sweet spot. Convective style snow from a closed ULL is one of my personal faves. Big omegas = big dendrites = high ratio pounding = weenie party. Even if short lived.

Bob, if the Atlantic side improves, in terms of the positioning of the block,  do you think we see the ULL in future runs dive further South and Southeast? 

Looks like the Pac is OK in a general sense, but the Atlantic is lacking.  Move the block further South and a bit West and could see some improvements. 

So far ahead to have any confidence I would imagine at this point.  There seems to be a lot of chaos going on up  North, lots of moving parts you could say. 

The funniest thing of all is this entire concept is built upon the concept the GFS at 150 hours, has any clue at 500 mb. :lol:    

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For the Dec 1-2 storm .A couple nice hits on the Gefs esp northern areas.  12z Ukmet is slower and further south with the primary ...again . (A good 12-18 hrs slower the Gfs). Extraping could be workable for the transfer local .

 

GZ_D5_PN_144_0000.gif

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20 minutes ago, frd said:

Bob, if the Atlantic side improves, in terms of the positioning of the block,  do you think we see the ULL in future runs dive further South and Southeast? 

Looks like the Pac is OK in a general sense, but the Atlantic is lacking.  Move the block further South and a bit West and could see some improvements. 

So far ahead to have any confidence I would imagine at this point.  There seems to be a lot of chaos going on up  North, lots of moving parts you could say. 

The funniest thing of all is this entire concept is built upon the concept the GFS at 150 hours, has any clue at 500 mb. :lol:    

It's all about ridging above the closed ULL and the spacing with the 50/50. It's certainly possible for a further south track but even as is the track is defying the atmosphere. Closed ULLs that track over Des Moines rarely work out here and the typical trend is north for these features as leads shorten. This is d5 so plenty can change. Just root for the bowling ball to be weaker and further south through the midwest. Faster would be better too. 

gfs_z500a_namer_24.png

 

It's an interesting setup for sure and I'm def watching it. I just don't like the odds here. The ULL is very strong in the midwest and it's going to try it's hardest to push against ridging and confluence. I remember the Feb 2015 storm (superbowl weekend?) that models all had a good track in the med range but guidance kept ticking north as leads shortened and it ended up being a whiff. IIRC, that ULL tracked right over Indianapolis. This one is further north as is. But there's also a blocking ridge to the north and pretty strong confluence to the east. The faster the ull tracks across the conus the better. 

 

 

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The trend for the LR to look far from catastrophic continues on the 12z GEFS. The super positive AO is gone, with it probably neutral or weakly positive by the 3rd or so. Still looks to me like there’s a lot of spread after the 3rd or 4th.

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