Oct.-Nov Pattern Discussion

[jaxjagman]

 

 

Robert just doubled down, talking of a pattern flip back to cold and interesting toward the end of November after a brief warm up. He thinks each month from December to March has the chance to deliver winter storms. Fascinating write up on his website.

I am really rooting for some warmth around Thanksgiving and into December. Maybe, just maybe.

 

[tnweathernut]

It is beginning to look like we have mets vs. models coming up toward the period just after Thanksgiving.  Models have backed away today from showing another sustained attack of colder air, but certainly aren't being consistent toward the end of the period.  The Euro weeklies paint a lot of ridging and only brief troughing in the eastern US for the next month. 

 

Time will tell where this leads and whether the mets will be right or the models will score a win.  Just watching it play out will be fascinating.  At some point it will flip, and I am just guessing it will be before Christmas.  Certainly not a boring pattern as we head toward December.

[John1122]

I don't really follow the weeklies all that closely, just due to the nature of models having trouble a few days in advance, let alone a few weeks in advance. How accurate have they been for November vs what was shown by them in October?

 

Robert seems to be on board for a repeating pattern of West coast/Alaska ridging with the cold air being dumped into the East fairly often. Pretty much a repeat pattern of what has been happening for most of the past 10-12 months. While we we assuredly get warm ups, he expects them to generally be fairly short lived. 

 

As of now, the CPC is onboard with Western/Alaska ridging to close out November with troughing progressing into the East.

[jaxjagman]

I don't really follow the weeklies all that closely, just due to the nature of models having trouble a few days in advance, let alone a few weeks in advance. How accurate have they been for November vs what was shown by them in October?

 

Robert seems to be on board for a repeating pattern of West coast/Alaska ridging with the cold air being dumped into the East fairly often. Pretty much a repeat pattern of what has been happening for most of the past 10-12 months. While we we assuredly get warm ups, he expects them to generally be fairly short lived. 

 

As of now, the CPC is onboard with Western/Alaska ridging to close out November with troughing progressing into the East.

 

Ridge is starting to look nice

[nrgjeff]

Strato warming vs MJO signal smack-down: Movie at 11. Well, maybe that is at the end of the 11-15 day period. Last week models picked up on thunderstorms increasing across the Indian Ocean. In theory that MJO signal builds a ridge over Northeast Asia, trough over Alaska, and mild over the Lower 48. At the same time a stratospheric warming (not sudden but sig) is creeping up toward the Pole from Eurasia. That is a cold signal. Who wins? History shows 50/50; sometimes the blocking blocks the MJO induced Kelvin wave. Other times the Kelvin wave makes it across along with milder temps.

 

First I want to see how the weekend plays out. Look for a nice warm-up and then some strong thunderstorms. In the wake of that system two scenarios could hint at Thanksgiving and the following week. If another trough is entrenched, GFS cold bias would verify. If the weekend system is a pattern changer, and the following one digs into the West like the Euro shows, then winter may take a break for a bit.

[tnweathernut]

Good post Jeff, I agree there are conflicting signals. The MJO winning would have me happy.....I want some enjoyable outside time before we go cold again!

[jaxjagman]

Strato warming vs MJO signal smack-down: Movie at 11. Well, maybe that is at the end of the 11-15 day period. Last week models picked up on thunderstorms increasing across the Indian Ocean. In theory that MJO signal builds a ridge over Northeast Asia, trough over Alaska, and mild over the Lower 48. At the same time a stratospheric warming (not sudden but sig) is creeping up toward the Pole from Eurasia. That is a cold signal. Who wins? History shows 50/50; sometimes the blocking blocks the MJO induced Kelvin wave. Other times the Kelvin wave makes it across along with milder temps.

 

First I want to see how the weekend plays out. Look for a nice warm-up and then some strong thunderstorms. In the wake of that system two scenarios could hint at Thanksgiving and the following week. If another trough is entrenched, GFS cold bias would verify. If the weekend system is a pattern changer, and the following one digs into the West like the Euro shows, then winter may take a break for a bit.

Thanks Jeff

[LithiaWx]

Strato warming vs MJO signal smack-down: Movie at 11. Well, maybe that is at the end of the 11-15 day period. Last week models picked up on thunderstorms increasing across the Indian Ocean. In theory that MJO signal builds a ridge over Northeast Asia, trough over Alaska, and mild over the Lower 48. At the same time a stratospheric warming (not sudden but sig) is creeping up toward the Pole from Eurasia. That is a cold signal. Who wins? History shows 50/50; sometimes the blocking blocks the MJO induced Kelvin wave. Other times the Kelvin wave makes it across along with milder temps.

 

First I want to see how the weekend plays out. Look for a nice warm-up and then some strong thunderstorms. In the wake of that system two scenarios could hint at Thanksgiving and the following week. If another trough is entrenched, GFS cold bias would verify. If the weekend system is a pattern changer, and the following one digs into the West like the Euro shows, then winter may take a break for a bit.

 

Great post as usual, thank you.

[1234snow]

Thanksgiving is looking a little snowy on the 12z GFS.

[1234snow]

Just a little snowy with a clipper like system that dives in on the backside on the broader trough next week on the 12z GFS.

[nrgjeff]

Thanksgiving I like thunderstorms more than snow. Just kidding storms would be a day or two later iff the slower warmer Euro is right. Euro digs a trough in the Plains first. Thank you to those above with the props.

 

That said the GFS insists on a colder pattern later next week. In the past 48 hours it has shown cold short waves Tuesday, Wednesday or now Thursday. The period of conflict between the GFS and Euro bears watching. In the 11-15 day 12Z GFS tries to go warmer while Euro ensembles finally bring in cold after the Thanksgiving weekend system. MJO vs Strato warming UFC match next week!

 

Just completed 12Z GFS ensembles echo the warm 11-15, in the face of coolish Euro and Canadian ensembles, but those are 00Z. I don't normally dissect model runs every 12 hours but this is kind of important for work, lol.

 

And the 12Z Euro now echos the GFS, somewhat. As Bill Self said, I wish this water was vodka!

[jaxjagman]

Thanksgiving I like thunderstorms more than snow. Just kidding storms would be a day or two later iff the slower warmer Euro is right. Euro digs a trough in the Plains first. Thank you to those above with the props.

 

That said the GFS insists on a colder pattern later next week. In the past 48 hours it has shown cold short waves Tuesday, Wednesday or now Thursday. The period of conflict between the GFS and Euro bears watching. In the 11-15 day 12Z GFS tries to go warmer while Euro ensembles finally bring in cold after the Thanksgiving weekend system. MJO vs Strato warming UFC match next week!

 

Just completed 12Z GFS ensembles echo the warm 11-15, in the face of coolish Euro and Canadian ensembles, but those are 00Z. I don't normally dissect model runs every 12 hours but this is kind of important for work, lol.

 

And the 12Z Euro now echos the GFS, somewhat. As Bill Self said, I wish this water was vodka!

Thanks Jeff.Black Friday looks interesting on the Euro

[tnweathernut]

That's a major cold shot on the 12z Euro for the period around Thanksgiving.  Very impressive to see, but is it real?  I really thought we'd have a re-shuffle period (2-3 weeks) where we diddy bopped between below and above normal temps.  It seems we are only going to be diddy bopping from average to below average, maybe squeaking in a day or so above as the result strong southwesterly winds from a cutter. I really didn't think I'd see modeling show another arctic outbreak before the month of November was finished.  Will be interesting to see if the models can lock in on another big high coming down or more fully throw the trough into the west and central plains as has also been showed on recent modeling.

 

What I don't see anywhere in the modeling is a legit setup for a snow. (i.e cool to cold, brief warming toward average with rain and showers, followed by more cool/cold, but dry)....... It's only November, so I am not really even thinking about that at this moment.  I'd like to see the atmosphere respond to some of the stratospheric warming by presenting blocking as we head later into the month of December.  With all the big highs last year, and now again this year, it's only a matter of time before blocking develops and we lock in some of this cold.  With what should be an active undercutting jet, courtesy of our El Nino, I think we will have multiple chances of wintry weather from either mid to late December, right through the month of February.

 

Fun times are ahead...... I think.  If not, we will need to re-think our entire set of key indicators (or find the new one that screwed us).

[Carvers Gap]

Great discussion the past two days. Still up to my eyeballs with work and responsibilities at home. Just have enough time to take a glance each morning at the Euro and click on NWS local forecast. Nice to be able to sit down and read some great discussion. I will not even venture a guess on the upcoming pattern. It does seem the models are having trouble early this season, much like January 2014, with recognizing shifts to a colder pattern.

[jaxjagman]

Maybe the 12z Euro is on to something?Who knows.

 

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1153 PM EST THU NOV 20 2014

VALID 12Z MON NOV 24 2014 - 12Z FRI NOV 28 2014

USED THE 12Z/20 EUROPEAN CENTRE ENSEMBLE MEAN AS A SYNOPTIC BASE
FOR THIS FORECAST PERIOD. THAT VERSION OF THE ECENS MEAN WAS
MARKED BY QUITE A BIT MORE NORTHERN STREAM DOMINANCE THAN THE
00Z/20 VERSION--AS WELL AS THE 00Z/20 AND 12Z/20 OPERATIONAL ECMWF
MODELS. THE DELIVERY OF CONTINENTAL POLAR AND ARCTIC AIR INTO THE
CONTIGUOUS UNITED STATES HAS CERTAINLY RELENTED AT TIMES DURING
THE LAST COUPLE WEEKS; BUT, BY AND LARGE, THE COLD AIR SEEMS TO BE
DIGGING IN ITS HEELS. INDEED, THE 00Z/21 OPERATIONAL GFS SHARES
MANY ASPECTS IN COMMON WITH THE ECENS MEAN FROM THE PREVIOUS MAJOR
DATA CYCLE. WITH COLD AIR SPREAD ACROSS SO MUCH OF THE NATION EAST
OF THE ROCKIES, WILL NEED TO WATCH THE SOUTHERN STREAM FOR WAVE
DEVELOPMENT THAT COULD LEAD TO SIGNIFICANT SNOW AND ICE.

CISCO

[jaxjagman]

http://earth.nullschool.net/#2014/11/25/0000Z/wind/isobaric/10hPa/overlay=temp/orthographic=-310.92,66.21,512

 

Strats getting beat up

[tnweathernut]

Snowfall forecast from the para GFS at 12z. Shows at least the chance for a white Thanksgiving. It would be incredible to see more snow in the air in November. It would make the FOURTH time in parts of northeast TN!. Map from DT's Facebook page.

[tnweathernut]

Euro 12z clown map gives 1-2 inches of snow in a fairly widespread area of southern middle TN on Thanksgiving.

[jaxjagman]

Euro 12z clown map gives 1-2 inches of snow in a fairly widespread area of southern middle TN on Thanksgiving.

GFS 18z shows almost the same thing,2"in SMT,also some flurries all the way to B'ham,not sure if that's snow though looking at the soundings,No matter what happens if we get sn. here during this time frame this will be our 3rd event for Nov.,we would almost equal last seasons overall and it's only Nov., not even met winter. yet

[jaxjagman]

Still looks like anything is on the table.Both the Euro and GFS shows three troughs Wed,one in the Atlantic off shore,one going through the Valley and one out west that right now that will fizzle out by both models in our area.Like Jeff would say though,showtime 0Z models

 

[1234snow]

The para GFS has been very inconsistent today. Virtually nothing on the 18z run. The backside energy and how it interacts with the broader trough will be key around next Wednesday into Thanksgiving.

[jaxjagman]

The para GFS has been very inconsistent today. Virtually nothing on the 18z run. The backside energy and how it interacts with the broader trough will be key around next Wednesday into Thanksgiving.

what are you using?Pay site?GFSP

[1234snow]

I've been using WxBell the last few days but that is a free trial. Before that I was using Tropical tidbits. Neither one has detailed 500 mb maps so it is hard to compare the two models at that level.

[jaxjagman]

 

Really funny basing off the 0z run when it looks we our temps would be well above normal somewhat  around Nashville we are actually well below based on the anomolies

[jaxjagman]

http://www.aer.com/science-research/climate-weather/arctic-oscillation

[Carvers Gap]

Models are sniffing out a Noreaster event the day of Thanksgiving.  Looks east of us, but something to keep an eye on if it jogs west.  And if it winds-up...it will jog west.  Looks like some blocking that will push it up the coast.  Any how...on w/ your regularly scheduled fall weather. 

 

I might also add, while the snow in my area has been a no-show.  The mtns have experienced some nice snows for late fall.  Not out of the norm, but out of the norm for the past couple of decades, not counting the past three years counting this year.   However, I need to clarify and correct on my part, the COLD has been record setting for November and way out of the ordinary.  Maybe once in a lifetime cold for November.  I had downplayed the November cold earlier.  It is absolutely amazing to looke at the numbers being put down...not necessarily the daily records but the departures from normal on a daily basis.  I think we have a -24 day here at KTRI.  Just consistent below normal temps for the entire month....Go Vols!

[jaxjagman]

 

[jaxjagman]

Models are sniffing out a Noreaster event the day of Thanksgiving.  Looks east of us, but something to keep an eye on if it jogs west.  And if it winds-up...it will jog west.  Looks like some blocking that will push it up the coast.  Any how...on w/ your regularly scheduled fall weather. 

 

I might also add, while the snow in my area has been a no-show.  The mtns have experienced some nice snows for late fall.  Not out of the norm, but out of the norm for the past couple of decades, not counting the past three years counting this year.   However, I need to clarify and correct on my part, the COLD has been record setting for November and way out of the ordinary.  Maybe once in a lifetime cold for November.  I had downplayed the November cold earlier.  It is absolutely amazing to looke at the numbers being put down...not necessarily the daily records but the departures from normal on a daily basis.  I think we have a -24 day here at KTRI.  Just consistent below normal temps for the entire month....Go Vols!

Euro shows a little bit for guys in the east and if your on the KY/TN line.But like Jeff said a couple days ago we need to see what this storm coming up does

[jaxjagman]

[valkhorn]

This is exactly where we want the potential storm on Friday - because chances are it is too far southeast and will gradually move northwest over time - especially after the next storm.

 

Of course I'll be out of town on Friday so I'll miss it if it happens. Oh well.