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April/May Meteorological Pattern Discussion


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00z/24th Ensemble Comparison 3/24-4/8.  Normal 850mb temp around +1C. 

 Cold start to April.

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 10;  PNA Day 14+; AO Day 12

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

GEFS:  (same)  Above normal 850mb temp anomalies thru Mar 28th, (day shorter) below normal anomalies Mar 29th into Mar 30th, (warmer) above normal anomalies later Mar 30th thru Mar 31st, below normal anomalies Apr 1st into Apr 4th, near normal anomalies Apr 5th, above normal anomalies Apr 6th thru Apr 8th.  (end of run) 

GEPS: (day shorter) Above normal 850mb temp anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (shorter) above normal anomalies Mar 30th & Mar 31st, (new, colder) below normal anomalies Apr 1st thru Apr 3rd, above normal anomalies Apr 4th & 5th, near normal anomalies Apr 6th & 7th, above normal anomalies Apr. 8th. (end of run)

EPS: (day shorter) Above normal anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (warmer, but shorter) above normal anomalies Mar 30th & Mar 31st, (new) below normal anomalies Apr 1st thru Apr 4th, above normal anomalies Apr 5th thru 7th. (end of run)

NAEFS Week 2: Week of April 1st-April 8th.  Low confidence of above normal temps. Been bouncing around this and "I don't know" last couple of days.

 

Teleconnections:  They suffer outlooking the EPO

EPS:     -EPO thru 3/25, pos 3/26-3/28, (new) neutral 3/29-3/30, pos 3/31-4/7

             -PNA

             +NAO thru 3/30, neg 3/31-4/7

GEPS:   -EPO thru 3/25, pos 3/26-3/28, neut 3/29, pos 3/30-4/8  (was just positive last time)

              -PNA 

              +NAO thru 3/30, neg 3/31-4/8

GEFS:   -EPO thru 3/26; pos 3/27 & 3/28, neg 3/29 & 3/30, pos 3/31-4/5, neg 4/6-4/8

             -PNA

             +NAO thru 3/30, neg 3/31-4/8.

WPO neutral to slightly neg thru Apr 1st, then positive thru 4/7 & 4/8. 

 

MJO:  (WH Sectors) vel potential and convection strung out phase 8 thru 3.  

GEFS Phase 2 to Phase 6; EPS Phase 2 to Phase 7 (closer to COD) (run ends 4/7). 

MVentrice Strong Phase 2; Phase 7 still strong looking at end.    

MJO phases Poor April correlations other than Phase 6 warm.

 

 

Strat: NASA Wave 1 at trof rising/peaking to 80th percentile at end. Wave 2 80th percentile peak now, oscillating between 40th & 70th percentile. EC stronger/sooner peak on Wave 1; Still shows weaker Wave 2 similar pattern. 

NAM/SPV:  For end of season GFS SPV showing decay now falling along 1SD above normal trend line.remains very strong (near 2SD), not much weakening this run. Ensembles show slight (less than climo) weakening.  Trop induced cold on GFS remains first week of April.

 

Trend from five days ago about first cool down is no it won't be a GEFS longer duration event. That being said, the second leg (coming from current -EPO) of a colder shot at the start of April is gaining traction and is in confidence range.  The second half of la la land, we should have a thermal recovery (aided by MJO going thru Phase 6?). Again this is within the start of skill, a switch in the NAO to negative would help stall or prolong colder air masses in April. Question is will the Pacific cooperate?  If the PNA skill is as good as it says it is thru day 14, the initial shots would come in west of us and then shift eastward. 

 

00z/19th Ensemble Comparison 3/19-4/3.  Normal 850mb temp around +1C. 

GEFS:  (1.5 days shorter)  Below normal 850mb temp anomalies thru today, near normal anomalies Mar 20th, (same) above normal anomalies Mar 21st thru Mar 28th, (colder) below normal anomalies Mar 29th into Mar 31st, near normal anomalies Mar 31st & Apr 1st, below normal anomalies Apr 2nd & 3rd.  (end of run) 

GEPS: (colder) Below normal 850mb temp anomalies Mar 19th, (day shorter) above normal anomalies Mar 20th thru Mar 29th, below normal anomalies Mar 30th, above normal anomalies Mar 31st thru Apr 3rd. (end of run)

EPS: (0.5 day shorter) Below normal anomalies Mar 19th, (same)  above normal anomalies later Mar 20th thru Mar 29th, below normal anomalies Mar 30th, above to near normal anomalies Mar 31st thru Apr 2nd. (end of run)

NAEFS Week 2: Week of March 26th-April 3rd.  High confidence of above normal temps.

 

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East based -NAO gaining traction as Tony said to start April across all ensemble guidance.  Gefs here as an example.  Could cutoff a low and keep a NW flow in place for a bit.

653764ce-e28d-455e-94cf-278a8f275ade.thumb.gif.7abe5363e3b8636986b8aa15d5ac69e1.gif

And maybe give Heisi a parting 3' snowpocalypse 🤣

Screenshot_20210325-035237_Chrome.jpg.ccf47932dfb0a1dfd2d642e8ca5c6ff8.jpg

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2 hours ago, susqushawn said:

East based -NAO gaining traction as Tony said to start April across all ensemble guidance.  Gefs here as an example.  Could cutoff a low and keep a NW flow in place for a bit.

 

And maybe give Heisi a parting 3' snowpocalypse 🤣

 

as long as we get a May freeze I'm game for everything 

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3 hours ago, susqushawn said:

East based -NAO gaining traction as Tony said to start April across all ensemble guidance.  Gefs here as an example.  Could cutoff a low and keep a NW flow in place for a bit.

653764ce-e28d-455e-94cf-278a8f275ade.thumb.gif.7abe5363e3b8636986b8aa15d5ac69e1.gif

And maybe give Heisi a parting 3' snowpocalypse 🤣

Screenshot_20210325-035237_Chrome.jpg.ccf47932dfb0a1dfd2d642e8ca5c6ff8.jpg

I think you forgot to change April 2 to April 1?

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38 minutes ago, Qtown Snow said:

presenting our new gfs 0z extended thoughts 

gfs-deterministic-conus-z500_anom-1616630400-1617310800-1618012800-20.gif

Was just gonna post that, there are actually some EPS members that have snow Day 8-10. 00z Icon was about to have snow at the end of its run. heh. 

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00z/26th Ensemble Comparison 3/26-4/10.  Normal 850mb temp around +2C. 

Cold start to April, Are You Willing To Buy The Longer, Colder GEFS?

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 11;  PNA Day 14+; AO Day 13

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

GEFS:  (same)  Above normal 850mb temp anomalies thru Mar 28th, (0.5 day shorter) below normal anomalies Mar 29th, (1.5 days longer) above normal anomalies Mar 30th into Apr 1st, (3 days longer) below normal anomalies later Apr 1st thru Apr 7th, (perfect 2 day can kick) near normal anomalies Apr 8th thru Apr 10th.  (end of run) 

GEPS: (same) Above normal 850mb temp anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (same) above normal anomalies Mar 30th & Mar 31st, (0.5 day longer) below normal anomalies Apr 1st into Apr 4th, (warmer and longer) above normal anomalies later Apr 4th thru Apr 10th. (end of run)

EPS: (same) Above normal anomalies thru Mar 28th, (shorter) below normal anomalies most of Mar 29th, (same) above normal anomalies Mar 30th & Mar 31st, (day shorter) below normal anomalies Apr 1st thru Apr 3rd, above normal anomalies Apr 4th thru Apr 9th. (end of run)

NAEFS Week 2: Week of April 3rd-April 10th.  Moderate confidence of above normal temps. Jump up losing Apr 1st & 2nd.

 

Teleconnections:  They suffer outlooking the EPO, within 7 days changed from two days ago to GEFS

EPS:     +EPO into 3/28, (new) neg 3/28-3/30, pos 3/31-4/4, neu 4/5, neg 4/6-4/9

             -PNA

             +NAO thru 3/30, neg 3/31-4/9

GEPS:   +EPO into 3/28, (new) neg 3/28-3/30, (shorter) pos 3/31-4/4, neg 4/5-4/10

              -PNA 

              +NAO thru 3/30, neg 3/31-4/9, neu 4/10

GEFS:   +EPO into 3/28, neg 3/29 & 3/30, pos 3/31-4/4, (higher) neu 4/5-4/7, neg 4/8-4/10

             -PNA

             +NAO into 3/30, neg 3/30-4/10.

WPO neutral to slightly neg thru Apr 1st or 2nd, then positive thru 4/9 & 4/10. 

 

MJO:  Strongest looking oscillation in a while  (WH Sectors) vel potential and convection strongest Phase 1 & 2  

GEFS Phase 3 to Phase 7; EPS Phase 3 to Phase 7 (stronger) (run ends 4/9). 

MVentrice Strong Phase 2/3; Phase 7/8 still strong looking at end.    

MJO phases Poor April correlations other than Phase 6 warm.

 

 

Strat: NASA Wave 1  75th percentile crest around 3/31, decreasing to below 50th percentile at day 10. Wave 2 30th to 70th percentile oscillation peaking around 3/31 also. EC stronger peak on Wave 1 (NASA went with its timing); Still shows weaker Wave 2 similar pattern. 

NAM/SPV:  For end of season GFS SPV showing decay bouncing along 1SD above normal trend line. Ensembles show slight (less than climo) weakening.  Trop induced cold on GFS remains first week of April, slower than guidance.

 

Confidence continues to increase about that cold shot to begin April.  The question then becomes how long it lasts, with the GEFS having the most -NAO cold blocking while the other ensembles not as much.  The warmth west of us looks legit based on the MJO and if one can have confidence in the EPO.  Is it sooner than later getting here?  Beyond the warmer look the week of Easter, a continued -NAO, if it has skill -EPO and "not confidently warm" MJO phases all point to an April that looks choppy and not torchy at this point. The SPV demise is going along smoothly.  First season at looking at this, so we will see how this progresses in April.

 

00z/24th Ensemble Comparison 3/24-4/8.  Normal 850mb temp around +1C. 

GEFS:  (same)  Above normal 850mb temp anomalies thru Mar 28th, (day shorter) below normal anomalies Mar 29th into Mar 30th, (warmer) above normal anomalies later Mar 30th thru Mar 31st, below normal anomalies Apr 1st into Apr 4th, near normal anomalies Apr 5th, above normal anomalies Apr 6th thru Apr 8th.  (end of run) 

GEPS: (day shorter) Above normal 850mb temp anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (shorter) above normal anomalies Mar 30th & Mar 31st, (new, colder) below normal anomalies Apr 1st thru Apr 3rd, above normal anomalies Apr 4th & 5th, near normal anomalies Apr 6th & 7th, above normal anomalies Apr. 8th. (end of run)

EPS: (day shorter) Above normal anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (warmer, but shorter) above normal anomalies Mar 30th & Mar 31st, (new) below normal anomalies Apr 1st thru Apr 4th, above normal anomalies Apr 5th thru 7th. (end of run)

 

 

 

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00z/29th Ensemble Comparison 3/29-4/13.  Normal 850mb temp around +2C. 

 Cold start to April, NON BREAKING NEWS....GEFS trended toward warmer GEFS & EPS

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 13;  PNA Day 14+; AO Day 13.5

Recent Verification Tendency: more positive NAO & AO, more negative PNA (all warmer trends)

GEFS:  (0.5 day shorter)  Above normal 850mb temp anomalies ending Mar 31st,  (4 days longer) below normal anomalies later Apr 1st thru Apr 3rd, near normal anomalies Apr 4th & Apr 5th, (warmer & longer) above normal anomalies Apr 6th thru Apr 13th.  (end of run) 

GEPS: (same) Above normal 850mb temp anomalies ending Mar 31st,  (day shorter) below normal anomalies Apr 1st thru Apr 3rd, (same) above normal anomalies later Apr 4th thru Apr 11th, near normal anomalies Apr 12th & 13th. (end of run)

EPS: (same) Above normal anomalies ending Mar 31st, (same) below normal anomalies Apr 1st thru Apr 3rd, (same) above normal anomalies Apr 4th thru Apr 9th, near normal anomalies Apr 10th, above normal anomalies Apr 11th & 12th. (end of run)

NAEFS Week 2: Week of April 6th-April 13th.  Moderate confidence of above normal temps. Trending more confident. 

Teleconnections: 

EPS:     +EPO  3/30-4/6 (one day neut 4/2), neg 4/7-4/10; neut 4/11-4/12

             -PNA

             +NAO thru 3/30, neg 3/31-4/10,neut 4/11-4/12

GEPS:   +EPO 3/30-4/6, (shorter) neg 4/7-4/10, neut 4/11-4/13

              -PNA thru 4/10, neut 4/11-4/13

              +NAO thru 3/30, neg 3/31-4/8, pos 4/9-4/13

GEFS:   +EPO 3/30/4-1, neg 4/2-4/3, (now) pos 4/4-4/12, neut 4/13

             -PNA

             +NAO thru 3/30, neg 3/31-4/13 (close to neut at end).

WPO neg thru Apr 2nd or 3rd, then trending more positive after that 

 

MJO:    (WH Sectors) convection strongest Phase 4  

GEFS Phase 4 to Phase 6; EPS Phase 4 to Phase 8 (run ends 4/12). 

MVentrice Very Strong Phase 3; Phase 8 still strong looking at end.    

MJO phases Poor April correlations other than Phase 6 warm.

 

Strat: NASA Wave 1  80th percentile crest now, decreasing to 30th percentile near day 10. Wave 2 75th percentile crest now, really crashing to below 10th percentile after that.  EC similar, more of a Wave 1 crash. 

NAM/SPV:  For end of season GFS SPV showing decay bouncing along 1SD above normal trend line. Ensembles show slight (less than climo) weakening.  Trop induced cold on GFS 4/3-4/11.

 

Cold shot starting April and then confidence higher than normal that milder Pacific air wins over -NAO Easter Week.  The seeds are being sowed about colder weather returning beyond that with the (predicted) EPO switch and also the MJO Phase progression.  EPO skill has been v skanky, so we will see if this colder signal progresses.  For now I am neither more or less confident than normal than I would typically be for the end of la la land.  SPV demise seems like a non issue at this point.  We are saving it for May for Tom. 

 

00z/26th Ensemble Comparison 3/26-4/10.  Normal 850mb temp around +2C. 

GEFS:  (same)  Above normal 850mb temp anomalies thru Mar 28th, (0.5 day shorter) below normal anomalies Mar 29th, (1.5 days longer) above normal anomalies Mar 30th into Apr 1st, (3 days longer) below normal anomalies later Apr 1st thru Apr 7th, (perfect 2 day can kick) near normal anomalies Apr 8th thru Apr 10th.  (end of run) 

GEPS: (same) Above normal 850mb temp anomalies thru Mar 28th, (same) below normal anomalies Mar 29th, (same) above normal anomalies Mar 30th & Mar 31st, (0.5 day longer) below normal anomalies Apr 1st into Apr 4th, (warmer and longer) above normal anomalies later Apr 4th thru Apr 10th. (end of run)

EPS: (same) Above normal anomalies thru Mar 28th, (shorter) below normal anomalies most of Mar 29th, (same) above normal anomalies Mar 30th & Mar 31st, (day shorter) below normal anomalies Apr 1st thru Apr 3rd, above normal anomalies Apr 4th thru Apr 9th. (end of run)

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00z/2nd Ensemble Comparison 4/2-4/17.  Normal 850mb temp around +3C. 

 April is the cruelest month.

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 12;  PNA Day 13; AO Day 13

Recent Verification Tendency: more positive AO; okay NAO; more negative PNA

GEFS:  (2 days longer)  Below normal 850mb temp anomalies thru Apr 5th, (much shorter) above normal anomalies Apr 6th thru Apr 9th, below normal anomalies Apr 10th thru Apr 16th, near normal anomalies Apr 17th. (end of run) 

GEPS: (2 days longer) Below normal 850mb temp anomalies thru Apr 5th, (shorter) above normal anomalies later Apr 6th thru Apr 12th, below normal anomalies Apr 13th & Apr 14th, near normal anomalies Apr 15th, below normal anomalies Apr 16th & Apr 17th. (end of run)

EPS: (1.5 days longer) Below normal anomalies ending Apr 5th, (net 0.5 days shorter) above normal anomalies Apr 5th into Apr 10th, (much longer, colder) below normal anomalies later Apr 10th thru Apr 16th. (end of run)

NAEFS Week 2: Week of April 10th-April 17th.  Just went from some above normal confidence to "We don't know".

 

Teleconnections: 

EPS:     -EPO  thru 4/5; pos 4/6-4/9; neut 4/10-4/16

             -PNA thru 4/11; weak pos 4/12-4/16

             -NAO  (not very consistent from four days ago)

GEPS:    -EPO thru 4/4; pos 4/5-4/17

              -PNA thru 4/11 (day longer), neut 4/12-4/17

              -NAO thru 4/11 (3 days longer), pos 4/12-4/17

GEFS:   -EPO thru 4/5 (2 days longer), pos 4/6-4/15 (neut 4/11), neg 4/16-4/17

             -PNA thru 4/11, neutral 4/12-4/17

             -NAO thru 4/15, neutral 4/16-4/17

WPO neg thru Apr 9th (that was extended), then trending more positive after that 

 

MJO:    (WH Sectors) very active Phase 5  

GEFS Phase 5 to Phase 6; EPS Phase 5 to Phase 8 (run ends 4/15). 

MVentrice Very Strong Phase 4/5; Phase 8/1 still strong looking at end.    

MJO phases Poor April correlations other than Phase 6 warm.  Phase 8 strongest correlation is warm in the Upper Plains.

 

Strat: NASA Wave 1 & Wave 2 80th percentile peak now (hello cold air) and then collapse to next to nothing (near 0 percentile) thru day 10.  EC similar. 

NAM/SPV:  For end of season GFS SPV showing decay bouncing along between 1SD & 2SD above normal trend line. Ensembles show slight (less than climo) weakening.  Trop induced cold on GFS 4/2-4/9.

 

A series of Rex Blocks next two weeks.  The first one is here and it has slowed our progression to warmer next week, so I give GEFS some due as the EPS & GEPS trended toward its earlier idea.  Then becomes complicated again around next weekend as another predicted Rex Block is expected to form farther west in our neighborhood. EPS full boar on this while the GEPS is what block?  GEFS between. Just looking at the Pacific (EPO lag), it is not going to be helpful for colder entering NOAM really thrut.  But, not much skill past day 7 or 8, so take that into consideration.  So our cold is more "home grown and stuck".  We will see how this plays out, but at the least this won't be torchy and at the worst it will be a typical cruel April stretch.

 

00z/29th Ensemble Comparison 3/29-4/13.  Normal 850mb temp around +2C. 

GEFS:  (0.5 day shorter)  Above normal 850mb temp anomalies ending Mar 31st,  (4 days longer) below normal anomalies later Apr 1st thru Apr 3rd, near normal anomalies Apr 4th & Apr 5th, (warmer & longer) above normal anomalies Apr 6th thru Apr 13th.  (end of run) 

GEPS: (same) Above normal 850mb temp anomalies ending Mar 31st,  (day shorter) below normal anomalies Apr 1st thru Apr 3rd, (same) above normal anomalies later Apr 4th thru Apr 11th, near normal anomalies Apr 12th & 13th. (end of run)

EPS: (same) Above normal anomalies ending Mar 31st, (same) below normal anomalies Apr 1st thru Apr 3rd, (same) above normal anomalies Apr 4th thru Apr 9th, near normal anomalies Apr 10th, above normal anomalies Apr 11th & 12th. (end of run)

 

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00z/10th Ensemble Comparison 4/10-4/25.  Normal 850mb temp around +4C. 

 April is still the cruelest month. Nothing to see here, move on. Apologies for the big gap between postings.

GEFS Start Of Teleconnection Fcst Skill:  NAO Day 13;  PNA Day 12; AO Day 14

Recent Verification Tendency: neutral NAO & AO; more negative PNA

GEFS: Above normal 850mb temp anomalies thru Apr 13th, below normal anomalies Apr 14th thru Apr 25th. (end of run) 

GEPS: Above normal 850mb temp anomalies thru Apr 13th, near normal anomalies Apr 14th thru Apr 25th. (end of run)

EPS: Above normal anomalies thru Apr 12th, below normal anomalies Apr 13th, near normal anomalies Apr 14th, below normal anomalies Apr 15th thru Apr 24th. (end of run)

NAEFS Week 2: Week of April 18th-April 25th.  Low confidence of near normal temperatures, confidence of below normal temperatures southwest of us.

 

Teleconnections: 

EPS:     -EPO 

             +PNA 4/12-4/24

             -NAO thru 4/18; neut 4/19-4/24

GEPS:   -EPO thru 4/21; pos 4/22-4/25

              +PNA 4/12-4/25

              -NAO thru 4/18; pos 4/19-4/25

GEFS:   -EPO

             +PNA 4/12-4/25

             -NAO thru 4/18, neutral 4/19-4/25

WPO neg 4/14-4/25 

 

MJO:    (WH Sectors) very strong Phase 5  

GEFS Phase 6 to Phase 7; EPS Phase 6 to Phase 8 (run ends 4/24). 

MVentrice Very Strong Phase 5; Phase 8/1 still strong looking at end.    

MJO phases Poor April correlations other than Phase 6 warm.  Phase 8 strongest correlation is warm in the Upper Plains.

 

Strat: NASA Wave 1 & Wave 2 activity rising to 90th percentile. EC similar. 

NAM/SPV:  End of season GFS SPV showing decay bouncing along between 1SD & 2SD above normal trend line. Ensembles Crosses 0 kts at end of month. Ensembles show slight (less than climo) weakening.  Trop induced cold ad nauseum on GFS.  Strat collapse in May?

 

Anyone wanting a warm April, stop reading now. Nothing warm to hang one's hat on. Even with the EPO poorer skill beyond day 7, we are likely talking about a colder Pacific look thru at least April 20th. +PNA outlook means angle of cold will be closer to us too. The next in a series of Rex Blocks is predicted to occur in the northeast Pacific. It is close to skill time being there.  The NAO  predicted transition to neutral or positive (that current Rex Block unravels) would give the cold an exit strategy.  I never looked at the unraveling of the SPV before and this happens every spring. If any colder than normal is going to come from that, we are in May.

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