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2020-21 Global Model QPF/Snowfall Evaluation For PHL. Snowfall Evaluation For The 2020-21 Season Posted.


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On 1/23/2021 at 6:39 PM, tombo82685 said:

euro

1/23 12z: .15 snow .6

1/24 0z: .25 snow .7

1/24 12z: .24 snow .3

1/25 0z: .28 snow 1"

eps

1/23 12z: .27  snow 1.8

1/24 0z: .36 snow 2.2

1/24 12z: .31 snow 1

1/25 0z: .42 snow 1.8

We can go thru 26th/00z run tonight barring something sneaking in faster.  So far GEFS not wet enough for Thursday.

 

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We can't thank everyone enough about all the views we get for this thread. This past season the over 33,700 views was the most ever for any season and the most viewed short term thread of the entire c

Snow tab: 2020-21qpf.xlsx

euro 11/9 0z: 4 11/9 12z: 1.8 11/10 0z: 1.6 11/10 12z: 1.8 11/11 0z: 2.03 11/11 12z: 1.78 eps 11/9 0z: 2.15 11/9 12z: 1.85 11/10 0z: 1.9 11/10 12

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46 minutes ago, Rainshadow5.8 said:

We can go thru 26th/00z run tonight barring something sneaking in faster.  So far GEFS not wet enough for Thursday.

 

lets keep it that way for the wefs 

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For one event we have returned to the winter of 2019-20 as the GFS did the best of all the evaluated guidance and the EPS flopped to last place.  Way too much emphasis on the fgen band along the warm front and it never corrected for it.  If we were still evaluating the NAM it would have saved it from a last place finish.

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snowy.JPG.6dbff06ce20bb88846952123ca3c0c10.JPG

If ever wonder why Tom & I have stopped evaluating the NAM beside the fact that no new upgrades are planned for it as EMC transitions away from it.  It just got the decimal point wrong in Delmarva:

nam.JPG.2a69c3a6dc5e0fbfeb2eb8ab46ab3712.JPG

dc.JPG.9d0c23117e6f4577b321bf08b60e8c00.JPG

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. 1/26 Ledge Event. The GFS Came In 1st; The EPS Pulled A Rock. Ever Wonder Why No NAM, Take A Look.

euro

1/29 0z: .42  snow 4.2

1/29 12z: .92  snow 9.2

1/30 0z: 1.41 snow  13.8

1/30 12z: 1.2 snow  11.8

1/31 0z: 1.31  snow 12.7

1/31 12z: 1.38  snow 13.6

eps

1/29 0z: .66  snow  6.3

1/29 12z: .79 snow 7.6

1/30 0z: .98  snow 8.2

1/30 12z:  1.08 snow 9.2

1/31 0z: 1.24 snow 10.8

1/31 12z: 1.05  snow 9.7

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On 1/29/2021 at 9:00 PM, tombo82685 said:

euro

1/29 0z: .42  snow 4.2

1/29 12z: .92  snow 9.2

1/30 0z: 1.41 snow  13.8

1/30 12z: 1.2 snow  11.8

1/31 0z: 1.31  snow 12.7

1/31 12z: 1.38  snow 13.6

eps

1/29 0z: .66  snow  6.3

1/29 12z: .79 snow 7.6

1/30 0z: .98  snow 8.2

1/30 12z:  1.08 snow 9.2

1/31 0z: 1.24 snow 10.8

1/31 12z: 1.05  snow 9.7

We can start the CFP Thu ngtish precip with 12z today. (2nd)

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euro

2/2 12z: .21 snow .1

2/3 0z: .06 snow .2

2/3 12z: .1 snow  .8

2/4 0z: .07 snow .5

2/4 12z: .1 snow .8

2/5 0z: .05 snow .4

eps

2/2 12z: .2 snow .1

2/3 0z: .12 snow .4

2/3 12z: .11 snow .6

2/4 0z: .08 snow .5

2/4 12z: .1 snow .7

2/5 0z: .06 snow .4

 

 

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Well it stopped snowing and here are the results.

First about the PHL w/e.  It does seem like the ASOS runs low when it snows and it has been common practice for us to average the w/e of all reporting CocoRahs and ASOS sites in the city when the ASOS seems low (judgment call).  That being said whether we used the actual ASOS: 0.68" or the PHL aggregate average: 1.08" it did not change the ranking.

Drum roll please. Once again when it mattered the most the EPS came in first with the most accurate (and also lowest) snowfall prediction for PHL.  The GGEM which you can say had the right idea of banded >2 ft snows (EPS won't catch that), but covered a too wide and too southwest area came in last.  In the interesting to note its forecasts (like the GFS) became worse as we came closer to the start time. 

QPF sort of goes hand in hand with this and the EPS came in first place too (using either amount). The GFS with its I don't know what to say 6-12" snowfall forecast for the Sunday night phase was the wettest and most inaccurate beating the GGEM.  It is tried and true, if you are wetter than the GEFS, you are in trouble....

snow.JPG.a2a98838dc1aee27b2291bff9fb47cc2.JPG

rain.JPG.aea8a44f6a511e3d9bc19a1edf9b3ebb.JPG

144487118_4018637914836243_3834021091279091214_n.png.d14c9a31321119964c162e2718285fdb.pngpast72.png.c246f2aaac8d530facd4a9cb4afaebb8.png

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. 1/31-2/2 HeimBo Storm. EPS Takes No Prisoners Again & GGEM/GFS Brings Up The Rear.
On 2/2/2021 at 8:27 PM, tombo82685 said:

euro

2/2 12z: .21 snow .1

2/3 0z: .06 snow .2

2/3 12z: .1 snow  .8

eps

2/2 12z: .2 snow .1

2/3 0z: .12 snow .4

2/3 12z: .11 snow .6

 

 

I know you love double headers.  We can start the Sunday event with the 12z run today (4th). We can make the 00z tonight the last one for Friday's event.

 

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euro

2/4 12z: .22  snow 2

2/5 0z:  .35 snow 3.5

2/5 12z: .49  snow 4.9

2/6 0z: .55  snow 5.4

2/6 12z: .51  snow 5.1

2/7 0z: .33  snow 3.2

eps

2/4 12z: .31 snow 2.8

2/5 0z: .41   snow 4.1

2/5 12z: .52  snow 4.7

2/6 0z: .63 snow 5.9

2/6 12z: .43 snow 4.2

2/7 0z: .33 snow 2.8

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I don't know if its the algorithms or the model, but either way the EC Family does not handle marginal/light snowfall events well. 

Otherwise another too wet model performance in which the least wet model (OP ECMWF) came in 1st and the perennially wet GEFS came in last.  You are wetter than the GEFS, not accurate.  The GFS's poor thermal resolution did it a favor with the snow as it correctly forecast no snow for PHL. 

 

past24.png

rain.JPG

snow.JPG

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. 2/5 CFP. OP ECMWF Good With Rain, Last With (Too) Snow. GEFS Came In Last With QPF.
On 2/4/2021 at 8:14 PM, tombo82685 said:

euro

2/4 12z: .22  snow 2

2/5 0z:  .35 snow 3.5

2/5 12z: .49  snow 4.9

2/6 0z: .55  snow 5.4

eps

2/4 12z: .31 snow 2.8

2/5 0z: .41   snow 4.1

2/5 12z: .52  snow 4.7

2/6 0z: .63 snow 5.9

2/7/00z run will be last with this one.

GFS lulled me to sleep.  Need to start Tuesday with the 12z run on Saturday (6th).

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euro

2/6 12z: .24 snow .3

2/7 0z: .11 snow .3

2/7 12z: .03 snow snow .1

2/8 0z: .06 snow .1

2/8 12z: .03  

2/9 0z:  .01

eps

2/6 12z: .12 snow .3

2/7 0z: .12 snow .4

2/7 12z: .11 snow .5

2/8 0z: .1 snow .4

2/8 12z: .07  snow .2

2/9 0z: .04

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On 2/4/2021 at 8:14 PM, tombo82685 said:

euro

2/4 12z: .22  snow 2

2/5 0z:  .35 snow 3.5

2/5 12z: .49  snow 4.9

2/6 0z: .55  snow 5.4

2/6 12z: .51  snow 5.1

2/7 0z: .33  snow 3.2

eps

2/4 12z: .31 snow 2.8

2/5 0z: .41   snow 4.1

2/5 12z: .52  snow 4.7

2/6 0z: .63 snow 5.9

2/6 12z: .43 snow 4.2

2/7 0z: .33 snow 2.8

BTW I saved the NAM’s numbers for this event. Four forecasts of 9-10” for PHL.

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This Super Bowl event there was no clear runaway win by the EPS.  EPS might have won the qpf, UKMET might have won the snow. 

I will tell you who came in last place at PHL if we evaluated seven models/ensembles.  The NAM.

PHL pcpn amount was 0.51" and snowfall 1.7".

The NAM forecasted 1.10"/9.0" ; 1.35"/9.9" ; 1.10"/9.3" ; 1.04"/9.0" ; .59"/ 5.5" ; .49" / 4.2".  About 36 hrs before onset, the NAM correctly cut its qpf in half, earlier runs, well....

 

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14 minutes ago, Rainshadow6.1 said:

This Super Bowl event there was no clear runaway win by the EPS.  EPS might have won the qpf, UKMET might have won the snow. 

I will tell you who came in last place at PHL if we evaluated seven models/ensembles.  The NAM.

PHL pcpn amount was 0.51" and snowfall 1.7".

The NAM forecasted 1.10"/9.0" ; 1.35"/9.9" ; 1.10"/9.3" ; 1.04"/9.0" ; .59"/ 5.5" ; .49" / 4.2".  About 36 hrs before onset, the NAM correctly cut its qpf in half, earlier runs, well....

 

Yup....most of the time this is what it means to get NAM’ed around here.

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Well for at sea level verification site, this event had a very March effect.  Snowing at 33F-34F during the daytime.  The w/e of pure snow "falling" at PHL was 0.42".  So in one regard one can't blame the models completely on this one for overforecasting snow at PHL as about 4" fell from the sky.  It was more of what happened to the snow at  ground level.

As far as the qpf went, this was the first event since November 15th  in which all of the models/ensembles averaged too dry.   This does not include the NAM (more on that below).  Something to be said about lows coming from the Gulf Of Mexico and while (I thought) the jet was a bit closer to the coast than one would want, we were in the correct quadrant.

So the qpf side, the OP ECMWF pulled out a win.  The GGEM that went from total suppression to NAMesque QPF came in last.  Part of this dry bias too was partially due to solutions that started too far to the southeast.  Snow-wise the GEFS pulled a rare win by being lower (even if right for wrong reason), while the GGEM pulled a double last place finish.

Onto the NAM: these were the forecasts for PHL (closest to go time last): 1.10"/9.0" ; 1.35"/9.9" ; 1.10"/9.3" ; 1.04"/9.0" ; .59"/ 5.5" ; .49" / 4.2".   So if one would have applied the proper micropyshics ratios (all that omega in the dgz that was correct north and west), one would have been forecasting 12-18" of snow (some ARW members had this forecast). 

 

past48.png

rain.JPG

snow.JPG

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. 2/7 Super Bowl Event. GEFS & Op EC Split 1st Finishes; GGEM Came In Last. NAM Would Have Come In Dead Last On Both Sides.

euro

2/8 12z: .4 snow 4

2/9 0z: .24 snow 2.4

2/9 12z:  .12 snow  1.2

2/10 0z: .12 snow 1.2

2/10 12z: .5 snow 5

2/11 0z: .4 snow 4

eps

2/8 12z: .49 snow 4.8

2/9 0z: .44 snow 4.1

2/9 12z: .22 snow 2.2

2/10 0z: .24 snow 2.4

2/10 12z: .45 snow 4.5

2/11 0z: .35 snow 3.5

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On 2/7/2021 at 8:08 AM, tombo82685 said:

euro

2/6 12z: .24 snow .3

2/7 0z: .11 snow .3

2/7 12z: .03 snow snow .1

2/8 0z: .06 snow .1

2/8 12z: .03  

eps

2/6 12z: .12 snow .3

2/7 0z: .12 snow .4

2/7 12z: .11 snow .5

2/8 0z: .1 snow .4

2/8 12z: .07  snow .2

2/9/00z run can be the last with this one.

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Well another wagons north (and farther east) system that totally bypassed PHL.  So the model that did the best (UKMET) managed to correctly thread the needle for PHL while the one that did the worst (GGEM) cranked up the offshore low too quickly.  The drips and drabs of snow for PHL were for all intents and purposes a tie.

past24.png.4e7a3cef5320adcb6e3807e4cc6b2340.png

 

 

rain.JPG

snow.JPG

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. 2/9 Non Event. UKMET Came In First. Too Wet GGEM Came In Last.
On 2/8/2021 at 8:52 PM, tombo82685 said:

euro

2/8 12z: .4 snow 4

2/9 0z: .24 snow 2.4

2/9 12z:  .12 snow  1.2

eps

2/8 12z: .49 snow 4.8

2/9 0z: .44 snow 4.1

2/9 12z: .22 snow 2.2

Yeah 00z run tonight (11th) last for this one.  Weekend we probably will start tomorrow.

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On 2/8/2021 at 8:52 PM, tombo82685 said:

euro

2/8 12z: .4 snow 4

2/9 0z: .24 snow 2.4

2/9 12z:  .12 snow  1.2

2/10 0z: .12 snow 1.2

2/10 12z: .5 snow 5

eps

2/8 12z: .49 snow 4.8

2/9 0z: .44 snow 4.1

2/9 12z: .22 snow 2.2

2/10 0z: .24 snow 2.4

2/10 12z: .45 snow 4.5

We can start the weekend one with the 00z run this morning (2/11).  Given that this looks like only sleet and freezing rain at this point, hopefully the "snowfall" algorithms are not going triple espresso with it.

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euro

2/11 0z: .5 snow .6

2/11 12z: .25

2/12 0z: .12 

2/12 12z: .23 

2/13 0z: .25 snow .4

2/13 12z: .15 snow .5

eps

2/11 0z: .4  snow 1.1

2/11 12z: .24 snow .2

2/12 0z: .12 snow .2

2/12 12z: .29 snow .2

2/13 0z: .19  snow .4

2/13 12z: .16 snow .5

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  • Rainshadow6.6 changed the title to 2020-21 Global Model QPF/Snowfall Evaluation For PHL. Snowfall Evaluation For The 2020-21 Season Posted.

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