EasternLI Posted December 27, 2012 Share Posted December 27, 2012 Almost every GEFS member is wetter than the OP, especially from SEPA through CNJ, SENY, SCT, and LI. A few members have >.5 liquid from coastal NJ through E LI and to me that QPF looks quite reasonable based on the synoptic evolution. The SLP into the Ohio Valley appears to get a little more dominant with each run, and with it, the QPF field expands slightly further N and the low center consolidates slightly closer to the coast and stronger. The SREF snow probs are still too low IMO, especially from the City east towards LI. But they are usually too sensitive to surface temps near freezing. It looks cold enough to me, even to the coast and on LI. The snow probs were way too low for the Xmas snow and up the HV for last nights's storm. 1" probs should be at least 50% and 4" around 10% in my opinion for the tristate area (based on current data). And I believe those probs are actually still too low considering historical analogies and recents trends. We would be helped out by a slightly cooler BL, but midlevels are plenty cold. I'm still feeling good about this one. I see the warm 2m temps, but I believe that they're too high, just like they were for yesterday and for christmas eve. Link to comment Share on other sites More sharing options...
TWCCraig Posted December 27, 2012 Share Posted December 27, 2012 SREF snow probs are pretty low. I do expect some areas especially here on the island to see over 4". I see accumalations 1-6" from this. The SREF snow probs are especially very low near the coast, not once does the snow prob go above 50% for 1" near the coast. Link to comment Share on other sites More sharing options...
bluewave Posted December 27, 2012 Share Posted December 27, 2012 It looks like the BL will be warm enough so that places near the coast will probably only accumulate on the colder surfaces like grass and cars. Link to comment Share on other sites More sharing options...
PB GFI Posted December 28, 2012 Share Posted December 28, 2012 It looks like the BL will be warm enough so that places near the coast will probably only accumulate on the colder surfaces like grass and cars. I have a hard time believing that a system deepening from the NC coast to cape cod with 850`s strung from Montauk to AC will have boundary layer issues . First this is not a warm air mass we are under , theres nothing but snow cover off to our north and west and this air mass doesnt modify as it comes east. Our wind direction is from the North Fri nite and it brings in lower level cold air that the models dont usually pick up well . The models love to warm the coast , they do it with every storm Tues the NAM 24 hours out progged a 40 number for NYC as the precip started . WAY off . This a deepening system to the BM or east , not a SWFE , so I have to believe with winds from the NE theres no mid level warming . Not to mention deeping systems love to pull cold air into there center and the rates cool the column The models treat every storm the same on the coast , lets warm the BL and paint the coast WET . When was the last time u saw Upper saddle river at 30 and ISLIP at 50 . it doesnt happen . Its a glaring weakness in the model , The model doesnt see land it sees OCEAN . So I dont buy it this time around - mayb im wrong , but in NOV with a slightly worse air mass than this with 55 Degree water most of us snowed with a very similar set up . Yesterday was energy transfer close to the coast and mid levels warmed quick due to easterlies Saturdays winds are from the Notheast , from an area thats colder due to snow cover . So if it rains on the coast then Im an ass,( not the 1 st time ) , but this is my reasoning and this what im betting . Link to comment Share on other sites More sharing options...
Isotherm Posted December 28, 2012 Share Posted December 28, 2012 It looks like the BL will be warm enough so that places near the coast will probably only accumulate on the colder surfaces like grass and cars. Mid levels are plenty cold; it depends on precip intensity. A stronger low will result in more evaporational cooling and thus more sticking. I think it's too early to make a call on snow amounts. Need to monitor trends in handling of s/w energy as it rounds the base of the trough. Link to comment Share on other sites More sharing options...
uncle W Posted December 28, 2012 Share Posted December 28, 2012 unless the storm is stronger than progged or tracks near the coast it should be an all snow event...The 3.5" NYC got on 12/19/1979 could be a good analog for now... Link to comment Share on other sites More sharing options...
WeatherFox Posted December 28, 2012 Share Posted December 28, 2012 It looks like the BL will be warm enough so that places near the coast will probably only accumulate on the colder surfaces like grass and cars. Also need among other things to consider are the surface temperatures prior to the event that get the ground cold: Upper 20's tonight, around 40 tomorrow and down to 30 tomorrow night.. Link to comment Share on other sites More sharing options...
Ericjcrash Posted December 28, 2012 Share Posted December 28, 2012 Also need among other things to consider are the surface temperatures prior to the event that get the ground cold: Upper 20's tonight, around 40 tomorrow and down to 30 tomorrow night.. Yeah, I don't see any issues. Link to comment Share on other sites More sharing options...
EasternLI Posted December 28, 2012 Share Posted December 28, 2012 I don't know much, but come on guys this has a 90% chance of being a 2-4" storm that's it. It's pretty late in the game for anything drastic. I'd say if 0z runs don't have a big bump on qpf then this is not going to improve before its game time. Crazy things happen but not Saturday. Agree or disagree? Sorry, you're wrong. Very small changes can still have large impacts wrt final outcome Link to comment Share on other sites More sharing options...
RUNNAWAYICEBERG Posted December 28, 2012 Share Posted December 28, 2012 Sorry, you're wrong. Very small changes can still have large impacts wrt final outcome small changes can have an impact but your talking about advisory level snows turning into just inside a warning criteria event, if everything goes right..there is nothing to slow it down, even if it bombs out at our latitude, to create a widespread MECS . Link to comment Share on other sites More sharing options...
EasternLI Posted December 28, 2012 Share Posted December 28, 2012 small changes can have an impact but your talking about advisory level snows turning into just inside a warning criteria event, if everything goes right..there is nothing to slow it down, even if it bombs out at our latitude, to create a widespread MECS . But I never said that did I? All I said is that the final outcome could vary greatly with some minor changes in the way features are being portrayed by the models. Nothing about bombs or warnings. It could also be a less amped wave in the end. Link to comment Share on other sites More sharing options...
RUNNAWAYICEBERG Posted December 28, 2012 Share Posted December 28, 2012 But I never said that did I? All I said is that the final outcome could vary greatly with some minor changes in the way features are being portrayed by the models. Nothing about bombs or warnings. It could also be a less amped wave in the end. but there is nothing there to suggest a minor change could vary the outcome GREATLY, as you say. that is my point. a change can vary the outcome to some extent, but nothing GREAT or MAJOR. Link to comment Share on other sites More sharing options...
ag3 Posted December 28, 2012 Share Posted December 28, 2012 Spc acknowledges the precip type issues and the snow probability issues: SREF - Precipitation Type Problem A recent fix to the instantaneous precipitation rates in the SREF (in order to fix errors in the ceiling and visibility) has inadvertently caused erroneous precipitation type fields in the ARW members. The error has resulted in no precipiation type being assigned to the vast majority of freezing or frozen precipitation areas in the ARW members. This will cause the following ensemble products related to precipiation type to be too low in magnitude: [MAX]:3hr_Snowfall(inches) [MN]:3hr_Snowfall(inches) [MN]:6hr_Snowfall(inches) [MN]:12hr_Snowfall(inches) [MN]:Snowfall_Ratio(Snow:Liquid_Eqv) [PR]:Snowfall_Rate_>=1in(perhr) [PR]:Snowfall_Rate_>=2in(perhr) [PR]:Snowfall_Rate_>=3in(perhr) [PR]:Freezing_Rain_Rate_>=0.05_in(per3hr) [PR]:Freezing_Rain_lasting_>=3hrs [PR]:Rain_Change_to_Freezing_Rain [PR]:Freezing_Rain_Change_to_Rain [PR]:Probability_Snow(All_members) [PR]:Probability_Ice_Pellets(All_members) [PR]:Probability_Freezing_Rain(All_members) Until the problem is fixed, users are referred to the SREF plumes page, which provides QPF and snow amount data from each member of the SREF: SREF Plumes page (clicking this link will open a new window) While the ARW data in the plumes will be incorrect, the NMM and NMM-B data can be used to provide better ensemble forecast data compared to what is in the adversely affected fields listed above. The source of the problem has been identified and a fix is expected to be applied sometime in January 2013. http://www.spc.noaa.gov/exper/sref/help/ptypeerror.html Link to comment Share on other sites More sharing options...
ag3 Posted December 28, 2012 Share Posted December 28, 2012 That answers why the srefs are showing low probability of snow amounts lately. Link to comment Share on other sites More sharing options...
WeatherFox Posted December 28, 2012 Share Posted December 28, 2012 HPC progs about a quarter of an inch of QPF for the Saturday event. I'd love to see the low come west and a little closer to the 40/70 benchmark. Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 00z NAM has a much better look to it at 24 hours compared to the 12z run from this afternoon...but it remains to be seen if that really will make much of a difference. Link to comment Share on other sites More sharing options...
EasternLI Posted December 28, 2012 Share Posted December 28, 2012 but there is nothing there to suggest a minor change could vary the outcome GREATLY, as you say. that is my point. a change can vary the outcome to some extent, but nothing GREAT or MAJOR. The difference between 6" of snow or a few flurries wouldn't be a major change in sensible wx conditions to you then. At my location both of these outcomes are still possible. Even a mix for a time is possible. A slight shift in track is all it takes for me 50 mi. sometimes 25 makes all the difference in the overseas country of long island. Link to comment Share on other sites More sharing options...
WeatherFox Posted December 28, 2012 Share Posted December 28, 2012 00z NAM has a much better look to it at 24 hours compared to the 12z run from this afternoon...but it remains to be seen if that really will make much of a difference. earthlight, What are your concerns? Thanks! Link to comment Share on other sites More sharing options...
96blizz Posted December 28, 2012 Share Posted December 28, 2012 NAM is WAY different so far early... in a good way. Hate how much we can't trust it at all --- let alone long range... Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 NAM is WAY different so far early... in a good way. Hate how much we can't trust it at all --- let alone long range... It's not way different from the 18z run. Small changes in the amplitude of the trough and positioning of the shortwave. Since the 06 and 12z runs it has trended much better. Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 earthlight, What are your concerns? Thanks! My only concern would be shadowing as the initial lift weakens and transfer to the coastal low. That could really screw us badly if it happens overhead. Otherwise I think we're locking in on a 2-3" event areawide. Link to comment Share on other sites More sharing options...
eduggs Posted December 28, 2012 Share Posted December 28, 2012 Spc acknowledges the precip type issues and the snow probability issues: SREF - Precipitation Type Problem A recent fix to the instantaneous precipitation rates in the SREF (in order to fix errors in the ceiling and visibility) has inadvertently caused erroneous precipitation type fields in the ARW members. The error has resulted in no precipiation type being assigned to the vast majority of freezing or frozen precipitation areas in the ARW members. This will cause the following ensemble products related to precipiation type to be too low in magnitude: [MAX]:3hr_Snowfall(inches) [MN]:3hr_Snowfall(inches) Good catch! I thought the snowfall products looked off lately. Link to comment Share on other sites More sharing options...
96blizz Posted December 28, 2012 Share Posted December 28, 2012 It's not way different from the 18z run. Small changes in the amplitude of the trough and positioning of the shortwave. Since the 06 and 12z runs it has trended much better. Sorry if I jumped the gun, but I did a comparison and seems much more amped early on --- even now up to 30. I'll back off and let the pros analyze. Link to comment Share on other sites More sharing options...
jm1220 Posted December 28, 2012 Share Posted December 28, 2012 NAM is WAY different so far early... in a good way. Hate how much we can't trust it at all --- let alone long range... I certainly wouldn't say "way better". A ton would have to change to make this a big deal for us. If anything, a modestly better upper air pattern could screw us by causing a faster developing offshore low that destroys lift and snow for our area (sinking air well away from that low). Link to comment Share on other sites More sharing options...
WeatherFox Posted December 28, 2012 Share Posted December 28, 2012 My only concern would be shadowing as the initial lift weakens and transfer to the coastal low. That could really screw us badly if it happens overhead. Otherwise I think we're locking in on a 2-3" event areawide. K, lets hope not.. Similarly, I don't want to see it form and track further OTS. Link to comment Share on other sites More sharing options...
eduggs Posted December 28, 2012 Share Posted December 28, 2012 Good catch! I thought the snowfall products looked off lately. All across NYS and SNE, locations greatly exceeded the very short range SREF <5% snowfall probs (e.g., progged at <5% chance of 4" and then received 6), which wouldn't make any sense considering that this past storm was "relatively" well behaved. Good to know the SREF is still viable. Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 This is pretty maddening to watch, to be honest. The lead vort is 6 hours too fast. If it were situated farther west at 33 hours, maybe over AK instead of TN/KY, we'd be in business with the northern stream dropping down. But there is just barely enough disconnect between the two. Link to comment Share on other sites More sharing options...
jm1220 Posted December 28, 2012 Share Posted December 28, 2012 FWIW (not much), the ARW at 21z had a 0.5-0.75" QPF for most of our area. Link to comment Share on other sites More sharing options...
Ericjcrash Posted December 28, 2012 Share Posted December 28, 2012 FWIW (not much), the ARW at 21z had a 0.5-0.75" QPF for most of our area. Really? Coastal within the Benchmark? Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 With the lead vort 6 hours too fast and the northern stream still trying to dig in...it almost has a negative effect on the pattern and the entire trough becomes a progressive piece of crap. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.