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Central PA - Jan/Feb 2019 Obs and Discussion


MAG5035

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Wow LWX already tossing up watches over a majority of their coverage region starting 10p on Tues. CTP noting high uncertainty. 

Quote

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Uncertainty is very high at this point as to the evolution of
precip type and the QPF over PA on Wed. GEFS and SREF plumes
play out a QPF range from just a tenth or so to many inches.
The temps also range wildly. The GFS warms everyone in Central
PA up to plain rain during the day, while the NAM and EC keep it
much colder. Will keep mentioning the storm in the HWO, but not
enough confidence in many aspects to post a watch. Most likely
place to get the worst impacts will be along and S of the PA
Turnpike.

I'd imagine if CTP were to have issued any watch headlines they would be residing roughly the bottom two tiers of counties. I have a pretty decent amount of confidence in this being a high impact predominantly winter p-type event in our region. The model positions they mention above in the quoted portion of the disco were the positions for last week's storm. The GFS was definitely not the winner of that with respect to the thermal column. The Euro/NAM handled that storm the best and I don't really see any reason to deviate from that with this one given the similar setup. My biggest concern with this event right now is QPF.  It may not impact I-80 north significantly, certainly at least from the standpoint of headlines greater than that of an eventual advisory. A bump north with stuff puts the axis of heaviest potential snow/ice right in the heart of central and LSV, a bump south/more progressive could have the significant impacts along and south of the mason-dixon. 

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5 minutes ago, MAG5035 said:

Wow LWX already tossing up watches over a majority of their coverage region starting 10p on Tues. CTP noting high uncertainty. 

I'd imagine if CTP were to have issued any watch headlines they would be residing roughly the bottom two tiers of counties. I have a pretty decent amount of confidence in this being a high impact predominantly winter p-type event in our region. The model positions they mention above in the quoted portion of the disco were the positions for last week's storm. The GFS was definitely not the winner of that with respect to the thermal column. The Euro/NAM handled that storm the best and I don't really see any reason to deviate from that with this one given the similar setup. My biggest concern with this event right now is QPF.  It may not impact I-80 north significantly, certainly at least from the standpoint of headlines greater than that of an eventual advisory. A bump north with stuff puts the axis of heaviest potential snow/ice right in the heart of central and LSV, a bump south/more progressive could have the significant impacts along and south of the mason-dixon. 

Thanks for your thoughts. Looks like today and tomorrow will fun.

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Took a look at the NAM and GFS it appears we lose the column around hour 63 which is after most of the precip has come...and both models are forecasting 1" or so along the southern tier of PA so without any more ado, here is the first call with a wide berth on this one until a final call of snow (not sleet or frz included in this call...that would be extra).

Blizz, Canderson, Sauss, Carlisle, Voyager-4-8"

Nut, Dax, Wmstpwx-3-6"

Mag, Cashtown, Bubbler-6-10"

 

Hour 60 full column temps on the NAM

image.png.96d34adb86a27b0fdb3f76b6204df862.png

 

 

 

 

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1 minute ago, canderson said:

Might be my mind doing tricks - and I don’t know where verification scores are - but hasn’t the old school GFS kicked the tail of the other models this season? 

If I had to rank the models from some light verification and memory I would do these as such...just my opinion

 

LR and MR-

Icon

Euro

GFS

CMC

UK

FV3

 

SR-

Euro

NAM

Icon

GFS

FV3

CMC

UK

 

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3 minutes ago, bubbler86 said:

6Z Euro Snow Depth.  Not the same as 0 but still a major hit for many. 

 

image.png.24b4ee5c896a0e753a083312fe9c0e66.png

When a model depicts an hour of sleet as snowfall it is doing so at 10:1 frozen to liquid ratio when sleet is ideally around a 3:1 ratio. Therefore the model starts to bomb unrealistic snowfall rates of 4" or greater over those final hours when you're not going to be snowing at all. That is why they suddenly leap up dramatically into unreasonable territory.

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27 minutes ago, pawatch said:

When a model depicts an hour of sleet as snowfall it is doing so at 10:1 frozen to liquid ratio when sleet is ideally around a 3:1 ratio. Therefore the model starts to bomb unrealistic snowfall rates of 4" or greater over those final hours when you're not going to be snowing at all. That is why they suddenly leap up dramatically into unreasonable territory.

Yea, that is the reason behind those crazy NAM maps.  I do not think the Euro map is including sleet.   Otherwise we would all be hugging this!  LOL.

 

image.png.c11583670aadd96b8f782adf27299408.png

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1 hour ago, canderson said:

Might be my mind doing tricks - and I don’t know where verification scores are - but hasn’t the old school GFS kicked the tail of the other models this season? 

I tend to agree.  While we often like the looks of what Junior G throws at us, Pappa G seems to verify better.

cor_day5_HGT_P500_G2NHX.png

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also looking at longer leads as I've been taking a mental break for the last couple weeks, Im hugging the EPS, cause GEFS says hello spring.  GEPS was a little better, but I can only hope the MJO stays favorable, or the WAR will win and were toast.  EPS was a beaut though. Look at that flow straight outta da pole.  Although it would be modified, that still could be quite a window of opportunity for us.

ecmwf-ens_z500a_namer_11.png

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8 minutes ago, Atomixwx said:

We're punching above our weight this winter, given the overall setup. If the Euro hits this one right, we have to consider the winter a success even if that's where it shuts down. 

Yeah, that's a very true statement.  We've been fortunate to make the most of many opps that have come at us in the craptastic pattern (even though I nare saw a flake, or hear a pinger in my latest WWA (overnigh/this AM).  

I'm skeptical at best for wednesday, but we do have a well timed press of cold in addition to the HP being close enough that it will likely take more time to dislodge, and the QPF seems pretty nice for the southern tier, although I seem to miss the good stuff once again.  Cashtown...you friggin snow hog :P

 

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48 minutes ago, pasnownut said:

I tend to agree.  While we often like the looks of what Junior G throws at us, Pappa G seems to verify better.

cor_day5_HGT_P500_G2NHX.png

The subject of verification scores interests me and I was always under the impression that the first number was the actual score re: GFS did worse than FV3 in that plot.  I believe these scores focus mostly on evolution of 500MB features vs. apparent weather so while the UK may have done ok with big picture stuff the actual results on the UK have been terrible this winter.  I stopped looking at it as it was rarely sending cutters west of us, which is what has happened almost every time, until the last minute.

Edit-I found what I believe is confirmation that the numerical value is the number to look at here...not the order they are in.  This plot shows

EC-UK-CMC-FV3-GFS-FNG-CFS in that order. 

 

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13 minutes ago, bubbler86 said:

The subject of verification scores interests me and I was always under the impression that the first number was the actual score re: GFS did worse than FV3 in that plot.  I believe these scores focus mostly on evolution of 500MB features vs. apparent weather so while the UK may have done ok with big picture stuff the actual results on the UK have been terrible this winter.  I stopped looked at it as it was rarely sending cutters west of us, which is what has happened almost every time, until the last minute.

 

 

Actually, you have it backwards, the lower the number, the better the verification, as it is an anomaly chart, so the lower the better.....the higher, the worse.

Pappa G .874

Junior G .880                   

Pappa wins

and you can pick verification of whatever youd like here.

https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

 

 

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Just now, pasnownut said:

Actually, you have it backwards, the lower the number, the better the verification, as it is an anomaly chart, so the lower the better.....the higher, the worse.

Pappa G .874

Junior G .880

 

Pappa wins

 

We need to check into that...this article suggests it is the other way around.

 

https://arstechnica.com/science/2016/06/the-us-weather-model-is-now-the-fourth-best-in-the-world/

 

 

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16 minutes ago, bubbler86 said:

We need to check into that...this article suggests it is the other way around.

 

https://arstechnica.com/science/2016/06/the-us-weather-model-is-now-the-fourth-best-in-the-world/

 

 

yeah i see that.  another read.  A rather misleading way to do it as its called an anomaly chart, but bases 1 as best when in acutallity, 0 should be (based on title).

https://www.emc.ncep.noaa.gov/gmb/wx24fy/doc/RMSE_decomposition.pdf

ok, back to the weather.  Its gonna snow somewhere...then its gonna rain.  I'm just not feeling it down here.

Seen this tooooooo many times to get jacked up.  Good Lord knows I want it, but Im 75 miles away from the goods on this one.  As it stands it wont stick around for very long either.

I used to say Voyager had a voodo doll.  Now I think there are a whole gaggle of warmies that have them and they need  to be found and burned. 

 

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Mainly two distinct camps of progs right now....all based on how far north the best forcing (conveyor belt) gets.  

6Z EC, 12Z Nam  focus the prceip up into PA with Wide Spread 5-10" amounts though much of the state

 

12Z GFS, 12Z Icon, 12Z FV3 favor more of a cut off north of I80 and the GFS especially has max snows south of the DC area but still 6-10" into south central PA.  Here is the 12Z GFS.   GFS is the outlier right now as to the area of max snows. 

snku_acc.us_ne.png

 

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21 minutes ago, Wmsptwx said:

Not me buddy, I'm rooting for you. This crap is awkward though....warm system with suppressed precip....wtf lol.

to your point, the 12z GooFuS just popped a max in central MD.  Not sure there is enough time to get it up this way (speaking GFS specific, cause I actually like the model for track, but thermals sometimes make me wonder.

 

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