ORH_wxman Posted November 16, 2012 Share Posted November 16, 2012 Even for 4 inch or greater snowstorms, the ao correlates a little better for dc. I think becuase the nao allows the blocking to be pretty far east since the index uses iceland in the calculation and we really want the blocking over greenland and canada with below normal heights to the south of the block. Yeah I imagine using the CPC number for NAO will create that issue. Iceland blocks are generally not very good for snowstorms there. If we just looked at the Greenland/Davis Straight/Baffin Island area, I'd bet that would correlate the best to snow events there. The AO probably would still win for temperatures though since its hard to get very cold without some semblance of a -EPO. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 16, 2012 Share Posted November 16, 2012 I imagine 1 week out will not provide a ton of answers...you can probably create a composite for what it looked like 1 week out, but it might not be predictive since probably countless other times had similar setups 1 week out but the key synoptic players didn't solidify until a couple days before. Sometimes 1 week out you can see the writing on the wall with very stable features...ala Feb 5-6, 2010. That was about as much a slam dunk as you can have in the world of forecasting 6-7 days out for DC snow...the question was merely how much snow would there be. Those are usually the exception rather than the rule. You just saved me a lot of work. lol I'll probably take the top 10 and look hard at those anyway. Big storms have to have many things go right for us. I would think the state of the ao/nao/pna a week out along with h5 anom map would show some insight. If I don't come up with anything interesting it will still be a fun exercise. Link to comment Share on other sites More sharing options...
usedtobe Posted November 16, 2012 Share Posted November 16, 2012 How much does your winter forecast change/or at all if the warming continues and we're able to get solidly into weak Nino territory? Not an awful lot. Link to comment Share on other sites More sharing options...
ORH_wxman Posted November 16, 2012 Share Posted November 16, 2012 Not an awful lot. It might mean better news for February on the Pacific side, but given it can't really get beyond weak, the effects would probably be muted. But I suppose a last second strengthening in the western reaches of the ENSO regions can't be a bad thing. A La Nina-ish February would stink...we can probably say that much. So anything that could give it a more El Nino look would be welcome to snow lovers. Link to comment Share on other sites More sharing options...
usedtobe Posted November 17, 2012 Share Posted November 17, 2012 It might mean better news for February on the Pacific side, but given it can't really get beyond weak, the effects would probably be muted. But I suppose a last second strengthening in the western reaches of the ENSO regions can't be a bad thing. A La Nina-ish February would stink...we can probably say that much. So anything that could give it a more El Nino look would be welcome to snow lovers. Since 1950 there have been 13 seasons with the oni between plus 0.2 and plus 1 and the biggest year was 25 inches or so. The average was 12.6...about the same as the median for all years. about 1 in 3 produced more snow than normal. Matt (CWG) forecast near the median or maybe a tad below so I'd still got near his forecast even with a nino unless I knew for certain that the ao would be negative which still looks to be up in the air. 13 years certainly is not enough to be statistically significant so the stats might be misleading. Give me an oni above 1.0 and I'd be more excited. For all ninos, the probability of getting above normal snowfall is right at 50%, the old flip of a coin but that's better than a normal year or a weak enso. Let's hope the GLAAM doesn't push us towards a nina like pattern in late Jan and early Feb, that would not be fun. Link to comment Share on other sites More sharing options...
griteater Posted November 17, 2012 Share Posted November 17, 2012 Interesting take from Paul Roundy on the winter Nino - http://blog.timesunion.com/weather/did-el-nino-die/2662/ "One of the leading forcing terms for changes in the state of El Niño is the Madden Julian oscillation, an eastward-moving region of organized thunderstorms and winds. the MJO produces alternating westerly and easterly wind signals over the Pacific Ocean. When El Niño itself has not yet fully coupled to atmospheric circulations (like right now), it is highly sensitive to forcing from the MJO, and the MJO in the right background conditions can change or amplify ENSO’s phase. Presently the western Pacific MJO is in its easterly phase. This phase is frequently followed by reduction of central Pacific sea surface temperatures. The westerly wind phase is likely to move over the Pacific during late November and early December. In consequence, I anticipate that the sea surface temperature pattern is likely to become less like El Niño into early December, followed by potential for dramatic sea surface temperature increases by late December or early January. Thus, although there is no guarantee of El Niño development across this season, I think it is a mistake to write it off. At least moderately strong El Niño conditions remain possible during January and February." Link to comment Share on other sites More sharing options...
Amped Posted November 17, 2012 Share Posted November 17, 2012 GFS 360. +10c 582 over western Greenland, Polar Vortex 50/50. Posted cause I'm tired of talking about Sandy. Link to comment Share on other sites More sharing options...
WVclimo Posted November 17, 2012 Share Posted November 17, 2012 Interesting take from Paul Roundy on the winter Nino - http://blog.timesuni...-nino-die/2662/ "One of the leading forcing terms for changes in the state of El Niño is the Madden Julian oscillation, an eastward-moving region of organized thunderstorms and winds. the MJO produces alternating westerly and easterly wind signals over the Pacific Ocean. When El Niño itself has not yet fully coupled to atmospheric circulations (like right now), it is highly sensitive to forcing from the MJO, and the MJO in the right background conditions can change or amplify ENSO’s phase. Presently the western Pacific MJO is in its easterly phase. This phase is frequently followed by reduction of central Pacific sea surface temperatures. The westerly wind phase is likely to move over the Pacific during late November and early December. In consequence, I anticipate that the sea surface temperature pattern is likely to become less like El Niño into early December, followed by potential for dramatic sea surface temperature increases by late December or early January. Thus, although there is no guarantee of El Niño development across this season, I think it is a mistake to write it off. At least moderately strong El Niño conditions remain possible during January and February." That's good stuff. Thanks for sharing it. Link to comment Share on other sites More sharing options...
okie333 Posted November 17, 2012 Share Posted November 17, 2012 Stratospheric vortex is also split. Link to comment Share on other sites More sharing options...
WxUSAF Posted November 17, 2012 Share Posted November 17, 2012 Overnight GFS ensembles very supportive of a signficant -NAO in the long range. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 17, 2012 Share Posted November 17, 2012 Euro shows a strong 582dm ridge just off the cali coast and a pretty good cold outbreak breaking into the northern plains @ d10. -14 to -16 850's into MN. Ridging east of GL squeezing the flow. That type of setup would definitely let the cold and trough shift east. It's looking more and more likely that we end the month pretty chilly. Looks pretty dry but who cares. Better than warm rain. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 17, 2012 Share Posted November 17, 2012 The front comes through next weekend. Seasonal til then with peak warmth around thanksgiving. GFS/Euro on same page with low 60s Thursday. GFS mos is 62. I have a bunch of family staying at my house over tday weekend. The warmth will actually be nice. We can take the kids and cousins to the parks and let the dog run. It will make is easier on my wife because we won't be all cramped up in the house for days on end. I'm looking forward to the pleasant weather. Looks like the local ski areas can fire the guns and open up in early Dec. Good for them. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 17, 2012 Share Posted November 17, 2012 I'm living in Old Town at 10', 3 miles due south of DCA 100 yards from the river. And I have a perfect place to measure. Might even put a snow board out there. I will have a great opportunity to see how bad DCA measures. You should absolutely do it. I hate their stats. It skews everything IMO. I would use yours over DCA's every single year. Who knows about precip chances in early december. It impossible to say what happens after the first cold shot although odd seems to favor a more blocked vs progressive pattern. I really like the euro ridge out west. Hopefully we can get the hudson bay vort spinning if the atlantic cooperates. Then anything hitting pac nw and bc can ride up over and down. December 5th clipper ftw. Link to comment Share on other sites More sharing options...
Ji Posted November 17, 2012 Share Posted November 17, 2012 Euro has chilled us for Thanksgiving. 55 for the high? Link to comment Share on other sites More sharing options...
BristowWx Posted November 17, 2012 Share Posted November 17, 2012 Euro has chilled us for Thanksgiving. 55 for the high? Great. I hate a warm Thanksgiving. Can we get some clouds and wind thrown in with that 55? Link to comment Share on other sites More sharing options...
WxUSAF Posted November 18, 2012 Share Posted November 18, 2012 Hello beautiful. Link to comment Share on other sites More sharing options...
MN Transplant Posted November 18, 2012 Share Posted November 18, 2012 Hello beautiful. I'm headed to CO and then MN next week. Giggity. Link to comment Share on other sites More sharing options...
midatlanticweather Posted November 18, 2012 Share Posted November 18, 2012 DT now sharing potential storminess around the 28th! I expect snow to be well North and west, but pattern is changing! Link to comment Share on other sites More sharing options...
usedtobe Posted November 19, 2012 Share Posted November 19, 2012 DT now sharing potential storminess around the 28th! I expect snow to be well North and west, but pattern is changing! I sure don't see it not that any forecast at that range has any skill whatsoever in the dailies. The biggest potential for storminess in over the Pac NW during that time range as the big positive anomaly near the Bering Sea teleconnects to heavier than normal precipitation across that region. Link to comment Share on other sites More sharing options...
midatlanticweather Posted November 19, 2012 Share Posted November 19, 2012 I sure don't see it not that any forecast at that range has any skill whatsoever in the dailies. The biggest potential for storminess in over the Pac NW during that time range as the big positive anomaly near the Bering Sea teleconnects to heavier than normal precipitation across that region. Ya, he was basing it on a Negative tilt trough on yesterday's 12 EC Ensemble model runs. Specifically this map: Link to comment Share on other sites More sharing options...
CoastalWx Posted November 19, 2012 Share Posted November 19, 2012 So he's calling for snow from that system on the 28th? Link to comment Share on other sites More sharing options...
usedtobe Posted November 19, 2012 Share Posted November 19, 2012 Ya, he was basing it on a Negative tilt trough on yesterday's 12 EC Ensemble model runs. Specifically this map: That looks more like a lakes runner that might become a miller b north of us but basing such a forecast on one euro ens mean is pretty foolish. I think the big story in that time range will be in the pac nw. Somewhere around the end of the month or beginning of the new one someone there is likely to get a big slug of precip. In the east there is way more going on but then Dave likes going for the jugular. Link to comment Share on other sites More sharing options...
SNO Posted November 19, 2012 Share Posted November 19, 2012 That looks more like a lakes runner that might become a miller b north of us but basing such a forecast on one euro ens mean is pretty foolish. I think the big story in that time range will be in the pac nw. Somewhere around the end of the month or beginning of the new one someone there is likely to get a big slug of precip. In the east there is way more going on but then Dave likes going for the jugular. Wes, how would you rate DT as a forecaster overall? He is now quite bullish on this winter. Looking for above average snow and below normal temps. Do you agree? Link to comment Share on other sites More sharing options...
mitchnick Posted November 19, 2012 Share Posted November 19, 2012 12z GFS looking interesting through 189 hrs maybe an overrunning type thingy in the makings Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted November 19, 2012 Share Posted November 19, 2012 At the very least, the GFS is moving toward at least something of "weather" interest in the 7-10 day period. Link to comment Share on other sites More sharing options...
stormtracker Posted November 19, 2012 Share Posted November 19, 2012 12z GFS looking interesting through 189 hrs maybe an overrunning type thingy in the makings At the very least, the GFS is moving toward at least something of "weather" interest in the 7-10 day period. Does look interesting...sneaky high pressing down. Of course, it goes to crap after truncation. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 19, 2012 Share Posted November 19, 2012 I started working through the snowfall data that zwyts posted. I pulled the top 15 and bottom 15 for comparison to see if anything stood out. Much of the data points towards things we already know but it's still fun to look and compare. Here's the gridded index data: As Wes has done an excellent job explaining already, it's clear that the AO is more important than the NAO. The short story is that if the AO isn't favorable take any modeled snow with a grain of salt. The data also shows that we need the PNA to be + if we want big snow and if we don't have some sort of decent NAO then we need the PNA to do its part. Most of this has been pointed out multiple times over the years. Also, big -NAOs are not good for us. Too much negative nao and everything is pushed south. One of the trends that I saw with the AO is that more often than not the snows happen when the AO is falling leading up to the event. I pulled the H5 anom maps for the day of each group of storms. Here's the 10+" storms: And this is the group of 5-6" storms: There is a noticeable difference in heights over AK between the 2 sets of data. Not sure if it's a blip or something meaningful. It seems that higher heights over AK teleconnect to smaller storms when we have a -ao/-nao combo. I also put together animations of NH h5 anoms for the 6 days prior to the storm. Pretty cool to look at but it really doesn't show anything that we didn't already know: 10"+ 5-6" storms Link to comment Share on other sites More sharing options...
mitchnick Posted November 19, 2012 Share Posted November 19, 2012 Does look interesting...sneaky high pressing down. Of course, it goes to crap after truncation. the 18z run can't come fast enough Link to comment Share on other sites More sharing options...
ACFD FIREMAN Posted November 19, 2012 Share Posted November 19, 2012 Nice work Bob. The 11/11/87 storm is such a statistical annomaly. +AO, +NAO and climo were all against it. Yet we still got 11.5". Link to comment Share on other sites More sharing options...
clskinsfan Posted November 19, 2012 Share Posted November 19, 2012 12z GFS looking interesting through 189 hrs maybe an overrunning type thingy in the makings What am I missing? Looks like a toasty lake cutter to me? Link to comment Share on other sites More sharing options...
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