earthlight Posted January 5, 2011 Share Posted January 5, 2011 Nothing historic beforehand, but after we get past a week or so... What's your over/under on NYC getting below 0? I think we'll still have a great snowpack, especially if the next event comes through, but I'd still say there's only a 20% chance. I'd give it around a 5% chance. It's just a very, very far reach for a great number of reasons. Link to comment Share on other sites More sharing options...
Yes_Probably_Maybe_No Posted January 5, 2011 Share Posted January 5, 2011 There's actually some higher heights over Eastern Canada which may force the PV westward a bit instead of southeast into the Central and Eastern US Ah...nothing like having winter actually feel like winter even with a La-Nina. Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 One thing is for sure, the region depicted for the hit on the norlun feature is not a climatologically favored area at all...LI/CT as well as parts of NJ to the south of NYC are typically more favored in the PHL-Toms River corridor or a bit north...the zone across NYC-ISP-MSV is not a region historically favored for that setup which is why we could see the end result be more northeast of there...I don't think it will be further SW as of now. SG, why would Philly be more favored for them than NYC? I thought the further north and east you were, the better. Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 I'd give it around a 5% chance. It's just a very, very far reach for a great number of reasons. What do you think the chances are that NYC gets at least 10" of snow in January? Link to comment Share on other sites More sharing options...
ORH_wxman Posted January 5, 2011 Share Posted January 5, 2011 Nate, I think we can throw climatology out the window in patterns like this. Remember Feb 09 lol? The inverted trough was down by Philly.... also a la nina and also with nice blocking. Inverted troughs are by far the most poorly modeled "storms" I have found....having forecasted up here for 6-7 years now. I've seen a model consensus perfect at 48 hours to hit SE NH or Portland ME and then I'm getting 6 inches of snow that was only supposed to be 1-2"...on the flip side I've seen us get 12" of snow on the modeled Norlun by most models at 48 hours and then its totally gone 100 miles away the next run. They are extremely fickle and require an exact distribution of LL convergence and vort max enhancement. They are nasty events to forecast. This event can give anywhere from 10" to flurries in your BY at this point, and that is probably the best way to approach it. Link to comment Share on other sites More sharing options...
earthlight Posted January 5, 2011 Share Posted January 5, 2011 The storm that misses us out to sea earlier in the run is trying to redevelop the blocking, but for the most part it's a complete blocking breakdown for the first time in a while. Link to comment Share on other sites More sharing options...
nzucker Posted January 5, 2011 Share Posted January 5, 2011 I'd give it around a 5% chance. It's just a very, very far reach for a great number of reasons. Agree...you have to have a fresh snowpack, due north (not NW) yet light winds, maybe even some ice on the Hudson to do this. Getting NYC below 0F also requires 850s of at least -25C...those are unlikely to begin with. Remember, we had 850s of around -24C in January 2009 and Central Park only got down to 6F despite people predicting they might break the barrier. Link to comment Share on other sites More sharing options...
Chris L Posted January 5, 2011 Share Posted January 5, 2011 Nothing historic beforehand, but after we get past a week or so... What's your over/under on NYC getting below 0? I think we'll still have a great snowpack, especially if the next event comes through, but I'd still say there's only a 20% chance. You need -35 at H850 to get NYC at below zero, (JAN 1994 was like that, and this coming outbreak will not come close to that one.... I mean it was TWO degrees in Wilmington DE at 12 PM on JAN 19 1994). Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 It seemingly is but my feeling is some of this is being generated due to strong PVA from the 500 low, especially the snow further inland. Goldberg was saying that most of our snow comes from the intense ULL over upstate NY Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 The storm that misses us out to sea earlier in the run is trying to redevelop the blocking, but for the most part it's a complete blocking breakdown for the first time in a while. Isnt a block breakdown what we need to build up more arctic air, though? Link to comment Share on other sites More sharing options...
Nikolai Posted January 5, 2011 Share Posted January 5, 2011 The storm that misses us out to sea earlier in the run is trying to redevelop the blocking, but for the most part it's a complete blocking breakdown for the first time in a while. I wouldn't say it's a breakdown, more of a relaxation... I haven't seen the 00z but it sounds like a continuation of 12z, where the massive block over AK is still there while the -NAO begins to resurge towards the end of the run (as you mentioned, higher heights in Eastern Canada). Models, to me, seem to be indicating that the -NAO/Baffin Block will make another extended cameo in the 1/20+ period... Link to comment Share on other sites More sharing options...
earthlight Posted January 5, 2011 Share Posted January 5, 2011 Isnt a block breakdown what we need to build up more arctic air, though? To a certain extent..but this is still a nina..never hope for a blocking breakdown. Link to comment Share on other sites More sharing options...
nzucker Posted January 5, 2011 Share Posted January 5, 2011 I wouldn't say it's a breakdown, more of a relaxation... I haven't seen the 00z but it sounds like a continuation of 12z, where the massive block over AK is still there while the -NAO begins to resurge towards the end of the run (as you mentioned, higher heights in Eastern Canada). Models, to me, seem to be indicating that the -NAO/Baffin Block will make another extended cameo in the 1/20+ period... We really want the NAO to get out of there though if we want NYC to get below 0F....need to have a clean path for the PV to come down and not have Canada stuffed with high heights. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 5, 2011 Share Posted January 5, 2011 Inverted troughs are by far the most poorly modeled "storms" I have found....having forecasted up here for 6-7 years now. I've seen a model consensus perfect at 48 hours to hit SE NH or Portland ME and then I'm getting 6 inches of snow that was only supposed to be 1-2"...on the flip side I've seen us get 12" of snow on the modeled Norlun by most models at 48 hours and then its totally gone 100 miles away the next run. They are extremely fickle and require an exact distribution of LL convergence and vort max enhancement. They are nasty events to forecast. This event can give anywhere from 10" to flurries in your BY at this point, and that is probably the best way to approach it. You can see on the 00Z GFS that the vort lobe seems to rotate over NYC exactly as the surface low is forming, if that timing is off by 8 or 10 hours then the trough probably forms elsewhere. Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 To a certain extent..but this is still a nina..never hope for a blocking breakdown. Hoping its temporary lol-- 5 days or less! Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 Inverted troughs are by far the most poorly modeled "storms" I have found....having forecasted up here for 6-7 years now. I've seen a model consensus perfect at 48 hours to hit SE NH or Portland ME and then I'm getting 6 inches of snow that was only supposed to be 1-2"...on the flip side I've seen us get 12" of snow on the modeled Norlun by most models at 48 hours and then its totally gone 100 miles away the next run. They are extremely fickle and require an exact distribution of LL convergence and vort max enhancement. They are nasty events to forecast. This event can give anywhere from 10" to flurries in your BY at this point, and that is probably the best way to approach it. It almost sounds like trying to forecast where the heaviest rain will be in a severe wx outbreak, Will. The problem with snowfall is that errors are magnified ten fold because of the provisional 10:1 ratio.... so, while 0.5 inches of liquid compared to 0.2 inches doesnt seem like much-- that's 5 vs 2 inches right there-- and with higher ratios, the difference is even greater. Link to comment Share on other sites More sharing options...
nzucker Posted January 5, 2011 Share Posted January 5, 2011 Can someone describe the rest of the ECM? How cold do we get? Any more storm threats? Link to comment Share on other sites More sharing options...
Nikolai Posted January 5, 2011 Share Posted January 5, 2011 We really want the NAO to get out of there though if we want NYC to get below 0F....need to have a clean path for the PV to come down and not have Canada stuffed with high heights. The NAO is roughly neutral or only slightly negative through d10, the 12z EURO would have likely brought it back stronger afterwards (when the cold air is already locked into the US). Perhaps we could end up with a 78-79 situation, where the East is still cold but the brunt of the cold is in the Midwest? It appears likelier than the core negative anomalies being in the East this month... Link to comment Share on other sites More sharing options...
ORH_wxman Posted January 5, 2011 Share Posted January 5, 2011 You can see on the 00Z GFS that the vort lobe seems to rotate over NYC exactly as the surface low is forming, if that timing is off by 8 or 10 hours then the trough probably forms elsewhere. Yes, the 00z suite all caught onto this feature and produced the inverted trough pretty much over NYC. But its easy to for it to shift a large amount in either direction when they sample this same feature on the next suite. I've always hated norlun type events from forecasting standpoint, but froma meteorological standpoint they are pretty fascinating. I've never really seen one well modeled more than 48 hours out...and most of them are terrible until about 24h out. The Dec 19-20, 2007 event here was pretty well forecast at 48h, but thats the last one I can remember that was good at that lead time. We had an awful bust on Feb 22, 2007...it was supposed to be in Maine and I forecasted 1-2" here and I knew I was deep crap by 10pm that night...we ended up with 6" of fluff. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 5, 2011 Share Posted January 5, 2011 SG, why would Philly be more favored for them than NYC? I thought the further north and east you were, the better. I'm not sure why, but I can recall 3 semi-norlun events in C-SNJ the last 15-20 years or so, one was as recently as 2 years ago which I had forgotten about til just now...it may have something to do with the coastal orientation...you have a more right angle or straight distribution on the NJ coast and event LI/CT....you have a very raggedy outline once you get near the NYC metro...that may have something to do with it. Link to comment Share on other sites More sharing options...
tombo82685 Posted January 5, 2011 Share Posted January 5, 2011 -30 to -35 highs hr 234 on the euro in central canada under the fat pig ov Link to comment Share on other sites More sharing options...
earthlight Posted January 5, 2011 Share Posted January 5, 2011 You can see on the 00Z GFS that the vort lobe seems to rotate over NYC exactly as the surface low is forming, if that timing is off by 8 or 10 hours then the trough probably forms elsewhere. Yup, you've got that right, which is why I am urging everyone to be extremely cautious. I refuse to forecast snowfall amounts at this juncture--it's not worth it. Here's the GFS which you were speaking of- you can see the shortwave/increased vorticity in alignment with the inverted trough which gives you the enhanced dynamics and QPF spike. It's not likely to happen this way, and if it does, it's also not likely to be perfectly forecast at this juncture as far as placement goes. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 5, 2011 Share Posted January 5, 2011 Yup, you've got that right, which is why I am urging everyone to be extremely cautious. I refuse to forecast snowfall amounts at this juncture--it's not worth it. Here's the GFS which you were speaking of- you can see the shortwave/increased vorticity in alignment with the inverted trough which gives you the enhanced dynamics and QPF spike. It's not likely to happen this way, and if it does, it's also not likely to be perfectly forecast at this juncture as far as placement goes. Regardless though, that 500 lobe whether it times it right for a norlun or not could do some damage over the area...I posted before the 12/26 event became a major event that the massive 500 low would hit someone hard in the N MA and mentioned the 12/27/04 event over NYC where some spots saw 4 inches, the 12/93, 12/92, and 12/95 event behind the storm which produced a lot of snow with strong 500 vorts. Link to comment Share on other sites More sharing options...
earthlight Posted January 5, 2011 Share Posted January 5, 2011 The 00z Nogaps still has a nice hit from the coastal storm at 180 hours, time for everybody to begin talking about how it's a giant red flag that it's coming back west. Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 The 00z Nogaps still has a nice hit from the coastal storm at 180 hours, time for everybody to begin talking about how it's a giant red flag that it's coming back west. Sounds like a good reason for us to stay up for the 6z runs Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 5, 2011 Share Posted January 5, 2011 http://www.meteo.psu...1995/us1220.php Check Ray's page and the radar over NYC/NJ/LI from 12Z-20Z on the 20th of Dec 1995...notice that pronounced lobe at 500 and see what it did then. http://www.njfreeways.com/weather/1996/19-Dec-95-FortDixDopplerRadarImagery.html Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 5, 2011 Share Posted January 5, 2011 http://www.meteo.psu...1995/us1220.php Check Ray's page and the radar over NYC/NJ/LI from 12Z-20Z on the 20th of Dec 1995...notice that pronounced lobe at 500 and see what it did then. http://www.njfreeway...darImagery.html Remember this well, SG. Was this the second day of the storm, when that plane slipped off the runway at JFK and landed in Jamaica Bay? Believe it or not, the forecasts for that storm were for like 15-20 inches of snow and we got 8-14, with most of the area on the lower end of the scale, and LGA recording the 14. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 5, 2011 Share Posted January 5, 2011 Remember this well, SG. Was this the second day of the storm, when that plane slipped off the runway at JFK and landed in Jamaica Bay? Believe it or not, the forecasts for that storm were for like 15-20 inches of snow and we got 8-14, with most of the area on the lower end of the scale, and LGA recording the 14. The sleet was a problem for LI and coastal NJ I think...LGA the belief is there was LI Sound enhancement...the snow on the 20th was generally not forecast...as you see the surface low was well NE by that morning but that 500 vort had a surprise as often happens. Link to comment Share on other sites More sharing options...
nzucker Posted January 5, 2011 Share Posted January 5, 2011 To a certain extent..but this is still a nina..never hope for a blocking breakdown. The blocking is not breaking down...there is an absurd ridge over the North Pole, Bering Strait, and Siberia....monster -EPO opening the floodgates for some absurd cold beyond Day 10. Also, I see another high pressure building into Greenland. Nothing on the ECM indicates the blocking is breaking down IMO. Link to comment Share on other sites More sharing options...
NittanyWx Posted January 5, 2011 Share Posted January 5, 2011 TBH Norlun troughs are handled significantly better than they used to be. Part of the "mystiqu"e (for lack of a better word) with them used to be how poorly the NGM recognized the setup. One of the earlier Norlun papers ('92 IIRC) discussed this at length. Link to comment Share on other sites More sharing options...
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