Meteorological Autumn Pattern Discussion - Nothing Lasts Forever, Not Even Warm November Patterns.

[ErieWX]

Some disagreements in the long range…eps starts to troff the Pacific Northwest which sends the torch in our direction. Gefs keeps torch out west while we start seeing some tropical threats hitting the SE. 

[Rainshadow]

The 00z Euro finally joined the GFS, GGEM & 12z Euro with granting us one day of autumn before rejoining our torch-er-ous pattern already in progress.  For now the latter have it as a three day reprieve. 

 

[Mitchnick]

4 hours ago, Rainshadow said:

The 00z Euro finally joined the GFS, GGEM & 12z Euro with granting us one day of autumn before rejoining our torch-er-ous pattern already in progress.  For now the latter have it as a three day reprieve. 

 

Odd how the low temps never rebound after the Friday cool shot.

[ErieWX]

14 minutes ago, Mitchnick said:

Odd how the low temps never rebound after the Friday cool shot.

Longer nights and lower dews, probably 

[Rainshadow]

00z/28th Ensemble Comparison 8/24-9/12.  Normal 850mb temp around +13C. 

Enjoy The Start Of September, Because It Is Back To August After That...

Thru 8/27 this is the warmest August on record in Philadelphia and we are one day short (not after today) in tying the greatest number of days with 90F or higher for August.  We will be either the 1st or 2nd warmest August on record after this month concludes. Please curb your enthusiasm.

First I was wrong about this weekend, we did not have a near normal day. The cool shot remained to our northeast.  At least the cool down for the end of this week remains on/close to schedule.  The EPS did not bandwagon jump on some of the 00z OP EC runs the last couple of days that went what CFP.  At anyrate, enjoy this because there does not appear much joy in Mudville after Saturday.  It takes a man sized +PNA spike to bring a cooler shot this time of year and after that the ensembles right or wrong go extremely zonal in la la land.  That Alaskan trof is still there, so there is a hope for a one day near normal in the middle of next week.  But with the +EPO within skill time chugging along at least thru Sept 7th or so it is an overall baked look.  If there are any consolations positive departures don't buy as much as they once did and all of the ensembles are passing the highest  (warmest) departures for now across southern Canada.  What could change?  The MJO could remain more active than outlooked (chances are it will to a certain extent) and looking at the September departure charts below, give us a chance.  BTW MJO Phase 2 is matching the highest torch location outlooked in the CONUS pretty well. 

Danielle should become Danielle pretty soon and the MJO is in position to get multiple named storms simultaneously. The outlook suggests we should get into a lull period (or less than normal activity period) in September after this just about starting spike in activity.  The NAO outlooked to remain negative longer is not a warm feeling  is kind of funny to say the tropics should trend more inactive when we are currently inactive.  In the nearer term, wished the NAO outlook of it turning positive on Sep 3rd would have held, every little bit helps.

 

 

GEFS Teleconnection Fcst Skill Starts At:  NAO Day 10;  PNA Day 9.5; AO Day 9

Recent Verification Tendency:  More Negative NAO. More Positive PNA & AO

GEFS: (day shorter) Above normal 850mb temp anomalies into Aug 31st, (day longer), below normal anomalies Sep 1st & Sep 2nd, above normal anomalies Sep 3rd thru Sep 12th (end of run).  Torch Maxes here on Aug 30th & Sep 12th.  Dakotas North Into Canada most torched.   

GEPS:  (day shorter) Above normal 850mb temp anomalies thru Aug 31st, (cooler trend), below normal anomalies Sep 1st & Sep 2nd, above normal anomalies Sep 4th into Sep 12th (end of run). Torch Max here Aug 30th.  Montana->Saskatchewan->Ontario most torched.

EPS: (0.5 shorter) Above normal 850mb temp anomalies thru Aug 31st, (same duration) below normal anomalies Sep 1st & Sep 2nd, above normal anomalies Sep 3rd thru Sep 11th (end of run). Torch Max here Aug 30th.   Montana->Saskatchewan->Manitoba most torched.  

 

NAEFS Week 2: Period of Sep 5th thru Sep 12th.  High confidence of above normal temperatures. Lost cooler start to September in forecast period. 

 

Teleconnections: 

GEFS:       +EPO thru 9/6 (near can kick, 3 days longer); neg 9/7-9/12

                  -PNA thru 8/28 (same); pos 8/29-9/9; neut 9/10-9/12

                  -NAO thru 9/10 (7 days longer); pos 9/11-9/12

GEPS:       +EPO thru 9/8 (3 days longer); neg 9/9-9/12

                  -PNA thru 8/28 (missed it); pos 8/29-9/5; neut 9/6-9/8; pos 9/9-9/12

                  -NAO thru 9/10 (6 days longer); neut 9/11-9/12 

EPS:         +EPO thru 9/9 (total can kick); neg 9/10-9/11

                 -PNA thru 8/28 (schooled them); pos 8/29-9/10; neg 9/11

                 -NAO (lost switch to pos after 9/6)

 WPO:       Starts negative goes pos thru 9/4ish; remains pos on GEPS

 

MJO:    Active Phases 1 thru 3

GEFS Phase 2 to COD Phase 7

EPS   Phase 2 to COD Phase 6 

GEPS Phase 2 to COD of COD (likes to do this)  (Runs all end 9/11)

MVentrice Extremely Robust Phase 2 to Active Phase 4. 

             

Strat: NASA Wave 1 30th-50th-30th Percentile. Wave 2 99th to off chart record to 90th percentile;  EC see ya next winter

SPV/NAM:  Trop cooling around 8/30, nothing helpful after that  

[irishbri74]

Seems like general consensus is a brief couple days of relief from heat and humidity, with a return by early next week, chance to touch 90’s in city proper, and dews back into the 70’s… gonna be a slow step into fall type weather probably… 

[Rainshadow]

14 hours ago, irishbri74 said:

Seems like general consensus is a brief couple days of relief from heat and humidity, with a return by early next week, chance to touch 90’s in city proper, and dews back into the 70’s… gonna be a slow step into fall type weather probably… 

The GFS is back to forecasting 100F days, so we have that going for us.

[iceman56]

4 hours ago, Rainshadow said:

The GFS is back to forecasting 100F days, so we have that going for us.

Latest 100F in PHL is on 9/7 if memory serves.   1881?

[Rainshadow]

6 hours ago, iceman56 said:

Latest 100F in PHL is on 9/7 if memory serves.   1881?

I have to look it up. 

[Mitchnick]

34 minutes ago, Rainshadow said:

I have to look it up. 

Rookie. 😛

[Rainshadow]

37 minutes ago, Rainshadow said:

I have to look it up. 

 

6 hours ago, iceman56 said:

Latest 100F in PHL is on 9/7 if memory serves.   1881?

Right you are. 102F hottest September on record.

[ErieWX]

I guess it’s the Euro’s turn now to start spitting out 600 DM ridges, in September no less. Anyhow, at least it’s out west and not over us…

[irishbri74]

21 minutes ago, ErieWX said:

I guess it’s the Euro’s turn now to start spitting out 600 DM ridges, in September no less. Anyhow, at least it’s out west and not over us…

Just gonna keep cooking up 18-22°C 850mb air masses and sending them east towards us. 

[ErieWX]

21 minutes ago, irishbri74 said:

Just gonna keep cooking up 18-22°C 850mb air masses and sending them east towards us. 

Yeah, I’m holding off on any chance of a good Barney cool shot until Astronomical fall at the very minimum, personally. Would be a miracle if we swing it with warm SSTs everywhere + Nina 

[Rainshadow]

12 hours ago, ErieWX said:

I guess it’s the Euro’s turn now to start spitting out 600 DM ridges, in September no less. Anyhow, at least it’s out west and not over us…

Still there.

[ErieWX]

4 hours ago, Rainshadow said:

Still there.

Yeah, not great for them having it within day 5. We had something similar in July but if I remember correctly it corrected down to 594 well before that. One of these summers the chickens will come home to roost and it won’t be fun 

[Rainshadow]

1 hour ago, ErieWX said:

Yeah, not great for them having it within day 5. We had something similar in July but if I remember correctly it corrected down to 594 well before that. One of these summers the chickens will come home to roost and it won’t be fun 

Yes we had 600+ I think in PA and pretty certain over the Ohio Valley and was farther into la la land.  I think they have had a couple of 600s in the Rockies the last couple of summers, not sure if it ever happened in September.

[Rainshadow]

00z/31st Ensemble Comparison 8/31-9/15.  Normal 850mb temp around +13C. 

First Half Of September Warmer Than Normal & The Sun Rises In The East...

All four major PHL climo sites will end August in the top 5. PHL has set a record for most 90 degree days in August and I think the midnight temperature tonight won't be enough to drop it out of the warmest August on record perch. Yes the PHL ASOS bias has been warm this summer, it does not take away it was yet another dreadful 2nd half of meteorological summer for the area. 

Brian & Erie stated this well.  The ridge easy bake ovens the western CONUS and then the relaxing pattern hurls torch bombs east.  This pretty much describes the state of affairs thru the weekend of 9/10-9/11.  The GEFS is torchiest farthest to the south while the EPS is torchiest farthest to the north.  Both are too close regardless.  The normal high for PHL on 9/10 & 9/11 is 81F. 

As for the particulars after our present trof lifts, the Bermuda ridge retrogrades westward (enough to give eventual Danielle an escape hatch to the east?). Simultaneously the south of Alaska PV helps pump the western Conus ridge.  I have seen 600DM 500mb forecasts on the Euro.  Not sure if this has ever happened in September. This process (coupled with a -NAO ridge over Greenland) will leave troffiness in eastern NOAM. The ensembles suggest a by-pass of a cooler shot after Labor Day.  A back door/ half baked onshore look could still bring us closer to normal for a day or two in there. An outlooked reconfiguration of the west with the EPO going negative (Alaska PV lifts north, new one goes into Bering Sea) within moderate skill time for it would eventually spell relief for the central/western CONUS.  Wavelengths may get us east, but at the least (yes this is into the la la land part) there would not be torch bombs getting manufactured out west.   

Danielle taking her time becoming Danielle. The MJO is outlooked to go into the circle of death (COD) or on Mike's site to Phase 4.  With either solution in theory there should be less MCS(s) going west across Africa from their Indian Ocean source. Again saying we should become less active than normal in September when we have yet to become active is....

 

 

GEFS Teleconnection Fcst Skill Starts At:  NAO Day 9;  PNA Day 9.5; AO Day 9.5

Recent Verification Tendency:  Neutral NAO & PNA; Negative AO

GEFS: (0.5 shorter) Below normal 850mb temp anomalies into Sep 2nd, (Yawn) above normal anomalies Sep 3rd thru Sep 15th (end of run).  Proximity Torch Max Lake Huron 9/10-9/11.  

GEPS:  (day shorter) Below normal 850mb temp anomalies thru Sep 1st, (Yawn) above normal anomalies Sep 2nd thru Sep 15th (end of run). Proximity Torch Max Lake Huron into Southern Quebec 9/9-9/11. 

EPS: (1.5 shorter) Below normal 850mb temp anomalies thru Aug 31st, above normal anomalies Sep 1st thru Sep 5th, (new) near normal anomalies night of Sep 6th, above normal anomalies Sep 7th thru Sep 14th. Proximity Torch Max Southern Ontario into Southern Quebec 9/9-9/11. 

 

NAEFS Week 2: Period of Sep 8th thru Sep 15th.  Near 100% confidence of above normal temperatures. Sigh.

 

Teleconnections: 

GEFS:       +EPO thru 9/5 (day sooner); neg 9/6-9/15

                  +PNA thru 9/6 (3 days shorter); neg, not neut 9/7-9/15

                  -NAO thru 9/13 (another can kick, 3 days longer); pos 9/14-9/15

GEPS:       +EPO thru 9/5 (3 days shorter); neg 9/6-9/15

                  +PNA thru 9/5 (same); neg, not neut then pos 9/6-9/15

                  -NAO thru 9/13 (3 days longer, can kick); pos 9/14-9/15 

EPS:         +EPO thru 9/6 (3 days sooner); neg 9/7-9/14

                 +PNA thru 9/11 (day longer); neg 9/12-9/14   (Not like GEFS/GEPS)

                 -NAO (same)

 WPO:       Now primarily positive week longer thru 9/12

 

MJO:    Active Phases 1 thru 3 (nod to Phase 3 slightly more)

GEFS Phase 2 to COD Phase 4

EPS   Phase 2 to COD Phase 4 

GEPS Phase 2 to COD Phase 6         (Runs all end 9/14)

MVentrice Extremely Robust Phase 2/3 Border to Active Phase 4/Phase 5 Border. 

             

Strat: NASA Wave 1 30th-95th Percentile. Wave 2 99th-50th-99th-50th percentile ->Late August record set;  EC see ya next winter

SPV/NAM:  Trop cooling now, another after 9/14  

 

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[ACwx]

Curious to see if the re-curving super typhoon in the West Pacific shakes up the jet stream across the hemisphere enough to dislodge us from our current warm and dry pattern. I believe these situations usually lead to East coast troughs 6-10 days afterwards.

[Rainshadow]

30 minutes ago, ACwx said:

Curious to see if the re-curving super typhoon in the West Pacific shakes up the jet stream across the hemisphere enough to dislodge us from our current warm and dry pattern. I believe these situations usually lead to East coast troughs 6-10 days afterwards.

My answer would be yes.  Doesn't mean it's right.  Doesn't mean the main effects get this far east because of wavelength considerations.

This is my subjective guess as to skill time start with the EPO.  So the ensembles are showing the EPO switch within skill time.  In winter it normally would take 5 days to get here (September 11thish).  I am not sure if this would hold as well in September.  Guess it doesn't.  But it looks like at the least it would cool off Canada and the central/west Conus so the +20C salvos stop coming east.  It may depend on how accommodating the Bermuda Ridge would be.

Regardless I am cautiously optimistic that the week (or at least more the rule than the exception) of September 11th may feel like September.

 

[ErieWX]

36 minutes ago, Rainshadow said:

My answer would be yes.  Doesn't mean it's right.  Doesn't mean the main effects get this far east because of wavelength considerations.

This is my subjective guess as to skill time start with the EPO.  So the ensembles are showing the EPO switch within skill time.  In winter it normally would take 5 days to get here (September 11thish).  I am not sure if this would hold as well in September.  Guess it doesn't.  But it looks like at the least it would cool off Canada and the central/west Conus so the +20C salvos stop coming east.  It may depend on how accommodating the Bermuda Ridge would be.

Regardless I am cautiously optimistic that the week (or at least more the rule than the exception) of September 11th may feel like September.

 

In addition to us not getting the torch bombs from the west, it should also at least reopen the door for some of those ULLs that we saw during the spring that the pac was tossing our way. Could bring some better storm chances from time to time and bring some relief in the rain department

[Rainshadow]

[iceman56]

16 minutes ago, Rainshadow said:

Hopefully the period after this can at least get back to normal which in mid-Sept is - we take!

[ErieWX]

10 minutes ago, iceman56 said:

Hopefully the period after this can at least get back to normal which in mid-Sept is - we take!

Then we better toss the fantasy EPS or just hope that it corrects within D10/EPO skill time. Nice poleward ridge over us as troffing starts to dig over the west coast 

[Rainshadow]

59 minutes ago, ErieWX said:

Then we better toss the fantasy EPS or just hope that it corrects within D10/EPO skill time. Nice poleward ridge over us as troffing starts to dig over the west coast 

I'd say this is the worst of the ensembles.  (GEPS & GEFS still have some negativity).