December 2022

[LibertyBell]

1 minute ago, eduggs said:

Well stated. As far as I know, CPC keeps things very general with broad brushed AN and BN for temp and precipitation. They avoid talking about specific patterns.

What's the longest timeframe that you feel that a specific storm can be forecasted.  2-3 days out?  Maybe up to 5 days if there's a really strong signal?

 

[LibertyBell]

1 minute ago, jm1220 said:

I was a toddler then. My focus was throwing spaghetti on the walls lol. I remember 93-94 as a cold snowy winter but 95-96 really got me into weather. 

Yeah those two winters are the ones when I finally started to measure snowfall lol.

 

[LibertyBell]

6 minutes ago, eduggs said:

I don't agree. The climate indices are a snapshot representation of the atmosphere, not a driver of its state. The driver is global temperature gradients.

Those global temperature gradients would then also include the extreme SST we see in the NW Atlantic.

 

[jm1220]

Just now, LibertyBell said:

Did Suffolk County do so well because they have more of an SNE kind of climate?  That storm and the middle storm in January 2011 would be proof of that.

 

Maybe in part but that death band sat over central Suffolk which made it cold enough. Up where I live now it's usually 2-3 degrees colder than NYC all else being equal which made it cold enough to flip to snow sooner. In Long Beach where I lived then it was infuriating watching the wasted heavy rain and sleet for hours. I remember seeing posts where it was heavy snow down to Sunrise Highway but still sleet at my house. It of course did snow hard eventually but 2 degrees colder and there would've been 20" instead of 10-11". 

[eduggs]

6 minutes ago, LibertyBell said:

No not indices.  I mean that events in one part of the world impact what happens in other parts of the world.  On a wholistic level, not reducing everything to indices.

 

I think of it more like tugging on a buckled string. The impacts are continuous and simultaneous in all directions.

[LibertyBell]

Just now, jm1220 said:

Maybe in part but that death band sat over central Suffolk which made it cold enough. Up where I live now it's usually 2-3 degrees colder than NYC all else being equal which made it cold enough to flip to snow sooner. In Long Beach where I lived then it was infuriating watching the wasted heavy rain and sleet for hours. I remember seeing posts where it was heavy snow down to Sunrise Highway but still sleet at my house. It of course did snow hard eventually but 2 degrees colder and there would've been 20" instead of 10-11". 

I remember!  There was this one time in 2011 I think it was where it was snowing in Oceanside and Valley Stream and raining in Long Beach.  Couldn't figure out how that happened lol.

Long Beach does its best in strong el ninos when it will probably do better than Huntington.  Imagine February 1983, PD2 or January 2016.

 

[winterwx21]

I think long range forecasting is pretty useful when it comes to temperature trends. Usually we can get a pretty good idea of warmer or colder patterns in the long range. The problem is storm threats. The model skill is just way too poor to have a good idea on anything beyond a week, so I think some people make a mistake in getting hopes up for winter storm threats beyond a week. It's why I never get excited until a legitimate threat gets to the more realistic day 5 range. 

[LibertyBell]

1 minute ago, eduggs said:

I think of it more like tugging on a buckled string. The impacts are continuous and simultaneous in all directions.

I see so the causes are also effects and the effects lead to the causes too, so it's like a symbiotic relationship.

 

[eduggs]

5 minutes ago, LibertyBell said:

What's the longest timeframe that you feel that a specific storm can be forecasted.  2-3 days out?  Maybe up to 5 days if there's a really strong signal?

 

Specific local impacts - 1-2 days. General signal for storm vs dry - 7-10 days. But obviously with increasing uncertainty as you move out in time. Other regions may have other characteristic lead times for reliable forecasts.

[eduggs]

5 minutes ago, LibertyBell said:

I see so the causes are also effects and the effects lead to the causes too, so it's like a symbiotic relationship.

 

That's how I see it.  

[eduggs]

So by now it seems likely that we'll be dealing with a cutter next week. But we can't forget the obvious lesson of uncertainty, which cuts both ways. The final outcome is still highly sensitive to the height field in key regions. Especially with an amplifying and anomalous trof, guidance could come storming back towards an east coast low. Chances have dwindled as we've used up lead time, but useful uncertainty remains.

[bluewave]

18 minutes ago, LibertyBell said:

What's the longest timeframe that you feel that a specific storm can be forecasted.  2-3 days out?  Maybe up to 5 days if there's a really strong signal?

 

I believe the record was 8 days on the EPS with Hurricane Sandy.

 

https://www.ecmwf.int/sites/default/files/elibrary/2013/10913-evaluation-forecasts-hurricane-sandy.pdf

 

In this report, we have discussed the predictability for the landfall of hurricane Sandy, affecting the New York City area on October 30th 2012. The cyclone made an unusual turn toward the west before making landfall. The westward movement and rapid deepening from the 29th was most likely due to an interaction with a trough over the U.S. Therefore both the prediction of the tropical cyclone and the U.S trough were of importance. The results show that ECMWF operational forecasts 8 days before landfall gave a strong and accurate indication of what was to happen. From 7 days before the landfall the high-resolution forecasts were consistent in its prediction of the landfall. The results from the ensemble forecasts allowed a significant degree of confidence to be attached to these forecasts but also showed signs of a too slow movement of the cyclone, which led to a timing error of the landfall.
The TIGGE archive has been used to compare predictions from different forecasting centres. The results shows that the ensembles from NCEP and UKMO started to pick up the risk for a deep cyclone making landfall 7 days (+168h) before the landfall and the ECMWF ensemble one day earlier (+8 days). Com- paring the performance between the centres, ECMWF had the highest probability for the cyclone landfall for most initial forecast times in the medium range. We also found that UKMO seemed to under-predict the depth of the cyclone compared ECMWF and NCEP and that the CMC ensemble had a large spread among the members. To evaluate whether the ensemble spread is reliable, the ensemble spread of trop- ical cyclone tracks needs to be evaluated over many cases. Comparisons between different forecasting centres for tropical cyclones can be found in e.g. Hamill et al. (2011); Yamaguchi et al. (2012).

[jm1220]

Euro a strong cutter at 12z but seems more meh with the frontal passage than CMC. Low occludes over Michigan and it's breezy/windy here but not 70+ gusts like the CMC. We get into the mid teens in the city, around 10 NW on Christmas Eve AM. Seems like the determining factor between roaring frontal passage and more meh like the Euro is if we can get a wave/secondary low develop closer to us. 

[HeadInTheClouds]

56 minutes ago, winterwx21 said:

This is another example of the CMC being a much better model than GFS. I think it even picked up on next week's storm being a cutter before the Euro. The CMC has done pretty well with winter storm threats the last couple years. It's a pretty good model. 

Even worse than next week's storm not working out is the pattern really breaking down in late December. It looks like a big warmup going into New Year's weekend. The great pattern that we were supposed to have is likely going to be a big bust. 

I agree about the CMC. It's been very good and often is the first to recognize things before other models and it's generally consistent run to run. I look at the CMC/RGEM before any other models.  

[Rjay]

1 hour ago, bluewave said:

So using that statistic, how many 970s mb or lower Great Lakes cutters have we had a few days after a -4 AO and +1 PNA in December? 

[White Gorilla]

We never learn the lesson to not give any psychological weight, any emotional investment into forecasts beyond 5 days, no matter how loud the hype or how strong the signal.  

[jm1220]

1 minute ago, White Gorilla said:

We never learn the lesson to not give any psychological weight, any emotional investment into forecasts beyond 5 days, no matter how loud the hype or how strong the signal.  

Unfortunately many have to get burned enough times to finally learn. That was me when I was younger lol.

[NorthShoreWx]

26 minutes ago, jm1220 said:

Maybe in part but that death band sat over central Suffolk which made it cold enough. Up where I live now it's usually 2-3 degrees colder than NYC all else being equal which made it cold enough to flip to snow sooner. In Long Beach where I lived then it was infuriating watching the wasted heavy rain and sleet for hours. I remember seeing posts where it was heavy snow down to Sunrise Highway but still sleet at my house. It of course did snow hard eventually but 2 degrees colder and there would've been 20" instead of 10-11". 

Not to dredge up old trauma, but the mix line was super close...right over LI for the first part of that storm.  We barely had any rain here at all, less than  0.2" of rain/sleet out of about 3.87" LE for the storm.  We had a mix, then some light rain for a short period late morning then slowly accumulating light snow for a few hours before it went nuke late afternoon.  There was also a short period of sleet mix a little after dark, but not much.  South and southwest areas of the island did get a bit screwed, especially since it was such a close call.

[bluewave]

7 minutes ago, Rjay said:

1 hour ago, bluewave said:

So using that statistic, how many 970s mb or lower Great Lakes cutters have we had a few days after a -4 AO and +1 PNA in December? 

12-28-68 would probably be the closest -4 -AO match. But the PNA was negative with a deep Western Trough instead of ridge. So this could be the deepest cutter following a -4 AO and +1 PNA combo.

 

[donsutherland1]

23 minutes ago, HeadInTheClouds said:

I agree about the CMC. It's been very good and often is the first to recognize things before other models and it's generally consistent run to run. I look at the CMC/RGEM before any other models.  

All the major models, except for the GFS, use the 4D-Var initialization scheme. NCEP decided to use something different rather than what remains the best-in-class approach. The growing gap in skill scores with two successive upgrades having slightly reduced scores over the versions they replaced are glaring red flags. Unfortunately, sunk cost fallacy seems to prevail and an inferior scheme is being retained.

[bkviking]

Isotherm was on such a hot streak for years and hit a lot of issues - like everyone - the past few years - and I  wonder if that’s why he gave up long range forecast its attempts. Or even showing up anymore. 

[forkyfork]

shit happens. what's really shocking to me is that the coast can't even get a moderate event with the ao this negative 

[brooklynwx99]

yeah, the monster storm did materialize, just a matter of 300 miles is the difference between a screaming cutter and a KU

frustrating, but it is what it is. hopefully we can get a follow up wave behind it

[bluewave]

The AO and the PNA improved from from forecasts 10 days ago but the big ridge east of New England also got stronger. So people aren’t going to want to hear about teleconnections anymore. This would have been more of a coastal storm with similar teleconnections in a earlier era.

New Run 

Old Run

 

[forkyfork]

2 minutes ago, bluewave said:

The AO and the PNA improved from from forecasts 10 days ago but the big ridge east of New England also got stronger. So people aren’t going to want to hear about teleconnections anymore. This would have been more of a coastal storm with similar teleconnections in a earlier era.

New Run 

Old Run

 

i wonder if the overall smaller polar vortex and hemispheric cold pool is playing a role

[SnoSki14]

9 minutes ago, bluewave said:

The AO and the PNA improved from from forecasts 10 days ago but the big ridge east of New England also got stronger. So people aren’t going to want to hear about teleconnections anymore. This would have been more of a coastal storm with similar teleconnections in a earlier era.

New Run 

Old Run

 

The shortwave does come in while the PNA is going up. The PNA ridge isn't very established until a couple days after

A stronger, established PNA probably could've counteracted the ridge east of New England. 

At the very least the very cold airmass post cutter should help cool off some of those warm waters

[Tatamy]

5 hours ago, LibertyBell said:

It would be absolutely shocking to get to 8 degrees after a high of 62 like that graphic was showing.  That gradient would produce 70+ mph winds!

What you just described did actually happen in the area on 2/2/76.  SLP bombed out on an arctic front just east of ACY that morning.  There are few here that are old enough to remember that one however it was quite spectacular while it lasted.  The pressure at my location on the north shore fell to 966 mb with heavy rain going to freezing rain, sleet, and ultimately blizzard conditions for a time with continuous lightning and thunder.  

[Rjay]

4 minutes ago, SnoSki14 said:

The shortwave does come in while the PNA is going up. The PNA ridge isn't very established until a couple days after

A stronger, established PNA probably could've counteracted the ridge east of New England. 

At the very least the very cold airmass post cutter should help cool off some of those warm waters

This set up wasn't about having a perfect ridge out west. 

[bluewave]

24 minutes ago, forkyfork said:

i wonder if the overall smaller polar vortex and hemispheric cold pool is playing a role

The last time we had a December La Niña combined with a near +1 PNA and -4AO was 12-30-00. But notice how the usual 50/50 low east of New England has been replaced by a ridge. This used to be a decent KU signal for us this time of year. 

PNA

2000 12 26  0.921
2000 12 27  0.928
2000 12 28  0.963
2000 12 29  1.081
2000 12 30  1.075
2000 12 31  0.895

AO

2000 12 25 -4.343
2000 12 26 -4.208
2000 12 27 -4.239
2000 12 28 -4.635
2000 12 29 -4.688
2000 12 30 -4.115
2000 12 31 -3.606

 

 

[SnowGoose69]

3 minutes ago, bluewave said:

The last time we had a December La Niña combined with a near +1 PNA and -4AO was 12-30-00. But notice how the usual 50/50 low east of New England has been replaced by a ridge. This used to be a decent KU signal for us this time of year. 
 

 

I had not payed much attention to the lack of the 50/50.  I was noticing more the ridge was too far west a few days ago....we have seen some big ones with the ridge further west but usually there are one of 3 other factors in place...the 50/50, the PV is really large and extends back west into MB/W Ontario, or the pattern is breaking down and progressing so while the ridge may have been off the W Coast when the development began in the Rockies/Plains, its quickly moving east.  I think the 96 and 03 Blizzards occurred that way, ridge was pretty far west but pattern was about to snap and the Pac was gonna bust everything open soon after both events