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Meteorological Autumn Pattern Discussion


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On 10/14/2021 at 5:48 PM, Rainshadow23.0 said:

This is not about the pattern turning cooler (which is agreed upon), it is about....

 

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The more things change, the more they remain the same...

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phillywx crew watching Tom's live cam from Lowville

I know a few people on here that wouldn't want 12 months of this (maybe 9 months of this), but at my age I'll take it.

Look ma, hardly any 80s...

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On 10/20/2021 at 8:01 AM, Rainshadow23.0 said:

Thankfully these night/day solutions are becoming rarer, but someone is going to be pretty wrong next week.

 

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Yes this is 12 hours later, score one for the GGEM & GFS for having the general forecast trend in their direction.

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6 minutes ago, Rainshadow23.0 said:

Yes this is 12 hours later, score one for the GGEM & GFS for having the general forecast trend in their direction.

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Nothing but clear skies and sunshine right? 🙄

 

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4 hours ago, Colin said:

GFS has 2-4”+ of rain the next week while CMC has less than a half inch.  Should be a fun winter 

Euro agrees with gfs. Wet week if true 

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1 hour ago, Parsley said:

Looks rain, more rain and the frost-freeze potential/cold shot in early November.

First week event has gained more teeth. Can’t stay dry for long, even in October.

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4 minutes ago, Rainshadow23.0 said:

First week event has gained more teeth. Can’t stay dry for long, even in October.

Yeah, always a balancing act. It's been very dry for the past 3 weeks around here. I've been getting as much done around the yard in prep. for mud season #2 (since spring gets #1)

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12 hours ago, tombo82685 said:

Euro agrees with gfs. Wet week if true 

Yup.  Looks like the first event is more for New England, but the second one will get us

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1 hour ago, Colin said:

Yup.  Looks like the first event is more for New England, but the second one will get us

While true on first system, immediate Philly area on east will probably see an inch or more 

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1 minute ago, tombo82685 said:

While true on first system, immediate Philly area on east will probably see an inch or more 

Hoping for a Miller B screwjob on this one.

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I have noted this several times over the years.  Not sure if it has any actual significance.

A precursor to pattern flips is an area of closed h5 energy that diverts from the prevailing flow.  

This closed h5 eminating from an area of low heights that has been pinwheeling for weeks.  This area has fed the recurring low heights in the Gulf of Alaska.  

As this closed h5 energy swims upstream east to west, it appears to alter the flow downstream leading to PNA/EPO ridging, and a more meridonal Pac flow.  

Should help unlock some arctic air.

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1 hour ago, susqushawn said:

I have noted this several times over the years.  Not sure if it has any actual significance.

A precursor to pattern flips is an area of closed h5 energy that diverts from the prevailing flow.  

This closed h5 eminating from an area of low heights that has been pinwheeling for weeks.  This area has fed the recurring low heights in the Gulf of Alaska.  

As this closed h5 energy swims upstream east to west, it appears to alter the flow downstream leading to PNA/EPO ridging, and a more meridonal Pac flow.  

Should help unlock some arctic air.

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Jet extension ->CWB which then leads to the ridge popping out west and Alaska. 

 

gfs-deterministic-npac_wide-z250_speed-1635055200-1635184800-1636113600-10.gif

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26 minutes ago, tombo82685 said:

Jet extension ->CWB which then leads to the ridge popping out west and Alaska. 

 

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Awesome conveyor belt animation!  All you see is the circulations and the moisture riding like a conveyor belt across the rollers!

 

 

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2 hours ago, tombo82685 said:

Jet extension ->CWB which then leads to the ridge popping out west and Alaska. 

 

gfs-deterministic-npac_wide-z250_speed-1635055200-1635184800-1636113600-10.gif

I take the lazy Gigi approach, I just look for the WPO going negative or weakening.

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4 minutes ago, Rainshadow23.0 said:

I take the lazy Gigi approach, I just look for the WPO going negative or weakening.

Can you please stop being lazy 

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16 hours ago, Parsley said:

Yeah, always a balancing act. It's been very dry for the past 3 weeks around here. I've been getting as much done around the yard in prep. for mud season #2 (since spring gets #1)

That is what I am going to go do after this post. The GFS is back to fujiwaraing a system SE of Delmarva and keeping E wetter and heavier longer.

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Cold push 1st week of Nov losing steam.  Trough undercuts the PNA ridge that in part pumps heights ahead of it keeping below normal anomalies at bay.  SE ridge showing up a bit.  

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2 hours ago, susqushawn said:

Cold push 1st week of Nov losing steam.  Trough undercuts the PNA ridge that in part pumps heights ahead of it keeping below normal anomalies at bay.  SE ridge showing up a bit.  

Still a solid cold push on eps for first week, but doesn't last long as we again go towards goa low which brings pac puke into Canada and US 

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14 minutes ago, tombo82685 said:

Still a solid cold push on eps for first week, but doesn't last long as we again go towards goa low which brings pac puke into Canada and US 

No record warmth is a step in the right direction. Negative departures would be another accomplishment.

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8 hours ago, Parsley said:

No record warmth is a step in the right direction. Negative departures would be another accomplishment.

Yeah first week of November still looks not above normal.

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00z/27th Ensemble Comparison 10/27-11/11. Normal 850mb temp around +5C. 

First 10 Days Of Nov Not Warm

It is prospective. Shawn brought up good point about Canada being warmer than normal.  This likely assisted by its snow coverage as of today being below average. On the other hand flow from Canada is still flow from Canada even if there is no man high involved. The Halloween cool (or normal) shot is more home grown based on the continuing +PNA.  The one later in the first week of November has the -EPO/+PNA coupling.  Yes EPS angle of the cold with the first +PNA is more west and yes there is a can kick look at we are at the edge of skill looking beyond Nov 4th-5th.  But one has to have confidence in something and that bleeding from the stratosphere look is still there in the first week of Nov.  After that and in la la land conflicting signals.  Phases 3-5 MJO have that warm Canada inference with Phase 5 the warmest of the three phases for us.  This is not the end of the conflict.  Wave 1,2 strong hits by NASA projections, but SPV still strengthens?  CPC has the NAO as negative but Wxbell has it as positive?  CPC's formula looks more at Greenland point south than others and the Rex Block look would induce the neg NAO index number.  I wouldn't call this one a classic -NAO.      

 

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 9;  PNA Day 10+; AO Day 9.5

Recent Verification Tendency:  neutral NAO, more positive AO & PNA

GEFS: (longer) predominately above normal 850mb temp anomalies into Nov 1st, (longer also) below normal anomalies Nov 1st thru Nov 7th, above normal anomalies Nov 8th & Nov 9th, below normal anomalies Nov 10th, above normal anomalies Nov 11th. (end of run).

GEPS: (longer) predominately above normal 850mb temp anomalies into Nov 1st, (colder and longer), below normal anomalies Nov 1st thru Nov 8th, above normal anomalies Nov 9th thru Nov 11th (end of run).

EPS: (2 days delayed, from 5 days ago) predominately above 850mb temp anomalies into Nov 1st, (more consistent than the other two) below normal anomalies Nov 1st into Nov 3rd, near normal anomalies Nov 4th, below normal anomalies Nov 5th thru Nov 9th, above normal anomalies Nov 10th (end of run).  

NAEFS Week 2: Period of Nov 4th-Nov 11th. Weak Confidence of near normal temperatures. Last cold season this mean below. Below normal confidence does not make this far east.     

 

Teleconnections: 

GEFS:     +EPO thru 10/29; (new) neg 10/20-11/3; pos 11/4-11/11 

                +PNA thru 11/9 (longer); neut 11/10 & 11/11

                +NAO thru 11/9 (much longer); neg 11/10-11/11

GEPS:     +EPO thru 10/29; (had it) neg 10/30-11/4;  pos 11/5-11/10, neg 11/11

               +PNA thru 11/8; neut 11/9-11/11    

               +NAO thru 11/10; neut 11/11

EPS:       +EPO thru 10/29; (more neg) neg 10/30-11/5; pos 11/6-11/10

               +PNA

                +NAO touches neut 11/1

 
WPO:   Positive becomes negative 11/1 or 11/3 and stays negative 

 

MJO:    (WH Sectors) Strongest Convection & Vel potential Phase 2

GEFS It is alive Phase 2 to Phase 5; EPS Phase 2 to Phase 5 (runs ends 11/9 or 11/10). 

MVentrice Strong Phase 8 to Phase 1 at end. This just looks like it is stuck in Phases 8/1, makes no sense again.    

 

                    

Strat: NASA 90th-99th percentile Wave 1 hit continues;  Wave 2 joins part with 90th percentile hit at end.  

NAM/SPV:  (GEFS) Zonal winds strongly recover from 1SD below to 1SD above

                    Strat hit still there and works its way down first week of November. 

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