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Meteorological Winter Pattern Discussion - It Is Here.


Heisenberg
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00z/23rd Ensemble Comparison 11/23-12/8.  Normal 850mb temp around 0C. 

Please Buckle Your Seat Belts & Put The Trays In The Upright Position. 

 So what I think is confident is that after the Thanksgiving moderation, the -EPO/+PNA couplet should send another colder shot the ensuing weekend. This can trend colder based on the PNA  strength/bias correction. Wrong!!!!!!!!!

I can disagree with the ensembles, but this was really a gaffe.  Remember the day 9 snow the day after Thanksgiving on the Euro?  Pepperidge Farm remembers.  Yes I need new material.  The Pacific has taken a huge overhaul and the -PNA bias did not matter because the PNA trended more negative and had wiggle room to be negative.  So basically with the Pacific forecast skill in a dumpster fire, are you better off seeing a +EPO pattern in week 2?  Maybe, maybe not.  If the MJO is once again a pattern contributor, the current phase matches perfectly with our thermal pattern and the GEFS looks like the MVentrice Phase 1 outlook for week 2. So basically at least for a while the EPO and a true -NAO will co-operate in making Canada cold and  slowing/shoving south the cold air exit.  It is the old angle of the cold question and how negative will the PNA be.  Yes thru the end of November we should average warmer than normal, but right now the NAEFS "I don't know" seems pretty smart for the first week of December. On face value the week 2 -EPO ridging looks too west for us to get the brunt of colder, but I have better places to lose my money than to bet on the week 2 EPO ridge position.

The SPV is outlooked to consolidate and recover to normal, slightly above normal strength as meterological winter arrives. 

    

 

GEFS Teleconnection Fcst Skill Starts At:  NAO Day 8;  PNA Day 8.5; AO Day 9

Recent Verification Tendency: Neutral NAO; More Positive PNA & AO

 

GEFS: (2 days longer) Primarily above normal 850mb temp anomalies thru Nov 27th, (3 days shorter) below normal anomalies Nov 28th, (2 days shorter) above normal anomalies Nov 29th thru Dec 1st, below normal anomalies Dec 2nd & Dec 3rd, above normal anomalies night of Dec 3rd, below normal anomalies Dec 4th thru Dec 8th (end of run).  

GEPS: (3.5 days longer) Above normal 850mb temp anomalies into Nov 28th, (BN gone) near normal anomalies night of Nov 28th, (same duration) above normal anomalies later Nov 29th Into Dec 1st, (1.5 days shorter) below normal anomalies Dec 1st into Dec 3rd, above normal anomalies later Dec 3rd thru Dec 7th, near normal anomalies Dec 8th (end of run).  

EPS: (close) Primarily Above normal 850mb temp anomalies into Nov 25th, (2.5 days shorter) below normal anomalies night of Nov 25th, (thermal flip) above normal anomalies Nov 26th & Nov 27th, below normal anomalies Nov 28th,  Nov 28th, (day shorter) above normal anomalies Nov 29th thru Dec 1st, near normal anomalies night of Dec 1st, above normal anomalies Dec 2nd & Dec 3rd, below normal anomalies Dec 4th thru Dec 6th, near normal anomalies Dec 7th (end of run).   There will be a quiz on all of these thermal flips this afternoon.

  

NAEFS Week 2: Period of Dec 1st thru Dec 8th.  I don't know. trending increasing confidence of colder west of us. 

 

Teleconnections: 

GEFS:         +EPO thru 11/26; neg 11/27-12/8 (not even close to 4 days ago)   

                   +PNA thru 11/24 (2 days shorter); neg 11/25-12/8

                   -NAO (same) 

GEPS:        +EPO thru 11/26 neg 11/27-12/8 (not even close) 

                   +PNA thru 11/24 (2 days longer); neg 11/25-12/8

                  -NAO thru 11/25; (new) pos 11/26 & 11/27; neg 11/28-12/8 

EPS:          +EPO thru 11/26; neg 11/27-12/8 (not even close, all 3 dropped pos(s). )

                  +PNA thru 11/24 (2 days shorter); neg 11/25-12/8

                  -NAO thru 11/26; (new); neut 11/27; neg 11/28-12/8 

 WPO:        Pos / Neg / Pos configuration.  You guessed it, not even close. 

 

MJO:       Active Conv & Vel Ptnl Phase 5 

GEFS:     Phase 6 to COD Phase 6

EPS:       Phase 6 to COD Phase 6 

GEPS:    Phase 6 to COD Phase 6      (Runs all end 12/7)

MVentrice: Bifurcated Phases 5 & 8 to Phase 1

             

Strat: NASA Wave 1: 20th -> 60th -> 30th Percentile.

                     Wave 2: 95th-> 99.99th (700 gpm)-> 5th percentile

                     EC on FU site, another stratospheric causality for this winter? 

SPV/NAM:  SPV consolidation thru Day 10. SPV dip to 20 m/s strengthening to 35-45m/s on 12/8 (near to above normal) 

                    Trop hit 11/30 & weaker 12/2 

****** December centered ************

image.png.bc2877d9bed710488d702d48c8fafe1a.png

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20 minutes ago, susqushawn said:

@Rainshadow remind me, why is the MVentrice version of the MJO outlook often in different phases than the model MJO outlooks?

Because that one is VP while the other outlooks are based off other factors. Like there are the rmm, VP, and OLR, OLR is the most accurate imo. 

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SE ridge locked in on long range ensembles overnight.  For instance, 850s never go below normal on EPS from 11/29 on.  -PNA maintains the angle of cold dilemma as it dumps it west, reinforcing the SE ridging.  

-NAO looks solid so maybe this forces a storm or two to drag some colder air our way on occasion, but mean storm flow favors to our NW despite the -NAO given the persistent west coast troughing.

Still evolving...we'll see...

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24 minutes ago, susqushawn said:

SE ridge locked in on long range ensembles overnight.  For instance, 850s never go below normal on EPS from 11/29 on.  -PNA maintains the angle of cold dilemma as it dumps it west, reinforcing the SE ridging.  

-NAO looks solid so maybe this forces a storm or two to drag some colder air our way on occasion, but mean storm flow favors to our NW despite the -NAO given the persistent west coast troughing.

Still evolving...we'll see...

Agree 100%. The trough in the east that prevailed over the couple of days on essentially all 3 ensembles is gone with only the Geps holding on to normal heights. Early December looks like a model head (or should I  say "mind") fake. Well, if at least mid-late December produces something that will beat most of the last Decembers since 12/13 save the 12/20 event. Happy Thanksgiving to all.

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To stay within Tony's confidence range, here we see the EPS d8 trend over time.  SE ridge has no choice but to flex.  -NAO isn't well established here yet so that's still not a lock quite yet.

On the bright side, Canada will be darn cold.  At least we don't have Canada half baked with Pac air.

Should the -NAO materialize, especially if west based, it might force the tpv farther SE, further increasing the opportunity for storm redevelopment closer to our latitude, thus enabling a deeper cold airmass to funnel down in its wake, beating down the SE ridge, or helping nudge it west.  

The risk if the -PNA remains entrenched is a Jan 2018 repeat, with can kicks, cutters and scraps of brief fropa cold air.

I'll await an update on the projected SPV wave 1/2 hits and MJO progression as those will be indicators as well.

As Tom has said over the years, we can't have a knee jerk reaction to every long range model run.  Something will change, hopefully in our favor.

eps_z500a_namer_fh192_trend (1).gif

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1 hour ago, susqushawn said:

To stay within Tony's confidence range, here we see the EPS d8 trend over time.  SE ridge has no choice but to flex.  -NAO isn't well established here yet so that's still not a lock quite yet.

On the bright side, Canada will be darn cold.  At least we don't have Canada half baked with Pac air.

Should the -NAO materialize, especially if west based, it might force the tpv farther SE, further increasing the opportunity for storm redevelopment closer to our latitude, thus enabling a deeper cold airmass to funnel down in its wake, beating down the SE ridge, or helping nudge it west.  

The risk if the -PNA remains entrenched is a Jan 2018 repeat, with can kicks, cutters and scraps of brief fropa cold air.

I'll await an update on the projected SPV wave 1/2 hits and MJO progression as those will be indicators as well.

As Tom has said over the years, we can't have a knee jerk reaction to every long range model run.  Something will change, hopefully in our favor.

eps_z500a_namer_fh192_trend (1).gif

Personally I think any thing prior to Dec 7th is a lonnnnng shot. Would start looking after that. Hopefully we can relax the pna a bit. Forcing will get into phase 8, let’s see if it shakes things up

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3 minutes ago, tombo82685 said:

Personally I think any thing prior to Dec 7th is a lonnnnng shot. Would start looking after that. Hopefully we can relax the pna a bit. Forcing will get into phase 8, let’s see if it shakes things up

Will also admit ensembles have certainly backed off the good looks the past few runs. It’s a volatile pattern with things all fighting against each other. Until a good or bad look gets under 8 days it’s just eye candy really 

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2 hours ago, susqushawn said:

To stay within Tony's confidence range, here we see the EPS d8 trend over time.  SE ridge has no choice but to flex.  -NAO isn't well established here yet so that's still not a lock quite yet.

On the bright side, Canada will be darn cold.  At least we don't have Canada half baked with Pac air.

Should the -NAO materialize, especially if west based, it might force the tpv farther SE, further increasing the opportunity for storm redevelopment closer to our latitude, thus enabling a deeper cold airmass to funnel down in its wake, beating down the SE ridge, or helping nudge it west.  

The risk if the -PNA remains entrenched is a Jan 2018 repeat, with can kicks, cutters and scraps of brief fropa cold air.

I'll await an update on the projected SPV wave 1/2 hits and MJO progression as those will be indicators as well.

As Tom has said over the years, we can't have a knee jerk reaction to every long range model run.  Something will change, hopefully in our favor.

eps_z500a_namer_fh192_trend (1).gif

That is a fairly man-sized positive anomaly over the Aleutians to show up at day 8.  With wavelengths lengthening, not where you want it to be to have cold dump first in the eastern Conus.  

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18 minutes ago, tombo82685 said:

Will also admit ensembles have certainly backed off the good looks the past few runs. It’s a volatile pattern with things all fighting against each other. Until a good or bad look gets under 8 days it’s just eye candy really 

One may be better off seeing the opposite of one wants past day 8 for the time being, a better chance of the opposite verifying.

Have a Happy Thanksgiving everyone!

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27 minutes ago, tombo82685 said:

Personally I think any thing prior to Dec 7th is a lonnnnng shot. Would start looking after that. Hopefully we can relax the pna a bit. Forcing will get into phase 8, let’s see if it shakes things up

If we could choose the timing, the second half of December would be better from a climatology perspective.  A frustrating period with snows N+W wouldn't be that unusual before we start getting threats.

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22 minutes ago, Rainshadow said:

One may be better off seeing the opposite of one wants past day 8 for the time being, a better chance of the opposite verifying.

Have a Happy Thanksgiving everyone!

Yea, like I said there are multiple things competing here. Standard nina look off Aleutian ridge. Then you have some high lat blocking, then throw in a favorable mjo pass for dec

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22 hours ago, susqushawn said:

@Rainshadow remind me, why is the MVentrice version of the MJO outlook often in different phases than the model MJO outlooks?

What Tom said.  The MVentrice outlook takes away some of the squirrelly noise you see with the WH diagrams.  But it is just the VP.  Favorable VP without resulting convection doesn't mean as much.  Kind of like our thunderstorm potential an nearly any given day in the summer.  Even though the sounding is essentially unstable, you still need a triggering mechanism.  

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1 hour ago, tombo82685 said:

Well yea it is, in February it’s a strong signal but the Aleutian ridge is a nina type feature. That is what we have going on now that is promoting the -pna 

Thanks. Improvements today on the gefs and geps but lots of back and forth. Looks like the southeast ridge will flex next weekend in terms of warmth 

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