jasonli18t Posted January 31, 2011 Share Posted January 31, 2011 Be careful with these events...sometimes the cold air hangs on longer east as the winds maintain a more northerly component at the surface longer. It happened in VD07, can be a tricky micro-climate thing to forecast but i have seen it several times the last few years. Link to comment Share on other sites More sharing options...
jm1220 Posted January 31, 2011 Share Posted January 31, 2011 Be careful with these events...sometimes the cold air hangs on longer east as the winds maintain a more northerly component at the surface longer. It happened in VD07, can be a tricky micro-climate thing to forecast but i have seen it several times the last few years. VD 2007 left probably an inch of ice even around Long Beach, and one of my trees came down from it. The wind direction overall will be key, since as long as we maintain NE wind we keep the cold advection at the surface going. Going to be a very tricky nowcasting event and given the strength of the high in Canada, whatever models are colder are likely preferable to warmer ones. Link to comment Share on other sites More sharing options...
NJwinter23 Posted January 31, 2011 Share Posted January 31, 2011 18z GFS total snow accumulation map on storm vista has the following...a good 4" increase across the board from 12z. 2-4 inches north of a line from Mercer County NJ to Sandy Hook 4-8 inches north of a line from Hunterdon County, NJ to Staten Island including all of Uptons CWA. 8-12 inches north of a line from the Sussex, Northern Passaic county border...all of SE NY..and interior Fairfield, New Haven, Litchfield (away from the CT coast). How on earth do they come up with 4-8 in those areas?? Bufkit profiles do not support that Link to comment Share on other sites More sharing options...
jm1220 Posted January 31, 2011 Share Posted January 31, 2011 How on earth do they come up with 4-8 in those areas?? Bufkit profiles do not support that I don't see how even most of Long Island gets more than maybe 2-3" of snow based on the warm air aloft that will be flooding in way before lower level warm air... those totals aren't feasible until you're maybe north of HPN. Link to comment Share on other sites More sharing options...
Bobby Posted January 31, 2011 Share Posted January 31, 2011 I don't see how even most of Long Island gets more than maybe 2-3" of snow based on the warm air aloft that will be flooding in way before lower level warm air... those totals aren't feasible until you're maybe north of HPN. With a cold base beneath that warmer air aloft wouldn't it be able to support snow for a period of time? I think most of the models are figuring a weaker cold air mass than what is there. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted January 31, 2011 Share Posted January 31, 2011 How on earth do they come up with 4-8 in those areas?? Bufkit profiles do not support that I'm pretty sure there's sleet in that algorithm. Link to comment Share on other sites More sharing options...
jasonli18t Posted January 31, 2011 Share Posted January 31, 2011 is there any variability to sleet ratios? or is it basically 2:1 always? Link to comment Share on other sites More sharing options...
NJwinter23 Posted January 31, 2011 Share Posted January 31, 2011 I'm pretty sure there's sleet in that algorithm. Yeah but in EWR for instance, 18z gfs is 0.23" snow tonight changing to 0.25" freezing rain by 1PM tmrw. The warm layer is no greater than 1-2ºC, but it is deep.. Then we get a break..Then 0.33" freezing rain tmrw night changing to rain tmrw morning (almost 0.5" rain). I wouldnt be surprised if the 0.25" freezing rain tmrw morning is actually sleet, but even then, that doesnt amount to 4-8 Link to comment Share on other sites More sharing options...
dbc Posted January 31, 2011 Share Posted January 31, 2011 I don't post much on here - much more of a reader... BUT - I was just curious if anyone has ever seen Upton split a county in a forecast like they have done to essex county in NJ. Western Essex county is now in a Winter Storm Warning and Eastern Essex county is in a Winter Storm Watch. I think it is clear to me that they have no confidence in their forecast as the models still seem to be all over the place. Any thoughts on this? They have been splitting the county for years in Bergen county probably for situations just like this. Link to comment Share on other sites More sharing options...
jconsor Posted January 31, 2011 Share Posted January 31, 2011 Even the NAM is underestimating the penetration of cold, dry air. The 12z NAM has 10F dew point line running from near Binghamton to the MA/NH border at 0z, while current obs show the 10F dew point line running from central PA through central NJ. The GFS is much closer to the truth on dew points in NY/New England. Further south, dew points on the Delmarva Peninsula are in the upper teens to mid 20s, with freezing rain falling at Wallops Island, VA (where local forecasts were calling for rain and lows in the mid 30s). The 12z NAM had dew points around 30-35F in this area. The GFS is equally as bad as the NAM on dew points from southern PA/central NJ southward to VA. Link to comment Share on other sites More sharing options...
Alpha5 Posted January 31, 2011 Share Posted January 31, 2011 Close call for the north/west burbs....a small shift will make a huge impact and mean the difference between a zr fest and rain. NAM is usually more reliable in marginal/CAD situations....but have to monitor trends as well Link to comment Share on other sites More sharing options...
Quincy Posted January 31, 2011 Share Posted January 31, 2011 {weenie} Dewpoints are well below forecast here in CT. Another point is that pressure values in upstate NY and northern New England are higher than progged, even compared to the latest RUC forecasts. {/weenie} Link to comment Share on other sites More sharing options...
Zir0b Posted January 31, 2011 Share Posted January 31, 2011 Close call for the north/west burbs....a small shift will make a huge impact and mean the difference between a zr fest and rain. NAM is usually more reliable in marginal/CAD situations....but have to monitor trends as well i'd be shocked if the NW burbs see more than a few drops of plain rain imo...the close call is in NYC itself Link to comment Share on other sites More sharing options...
Guest stormchaser Posted January 31, 2011 Share Posted January 31, 2011 Possibly signalling a stronger then progged high, quikcy? /weenie Link to comment Share on other sites More sharing options...
Quincy Posted January 31, 2011 Share Posted January 31, 2011 Possibly signalling a stronger then progged high, quikcy? /weenie the high is stronger than progged. might not be by a lot, but could make all the difference in those borderline areas. downstream actual temps look pretty much on target, but I think it will probably come down to a nowcasting event by Tuesday night to see if we're going to end up close to forecast, or well-below temperature wise, which happens in some of the most severe ice storms. Link to comment Share on other sites More sharing options...
dbc Posted January 31, 2011 Share Posted January 31, 2011 {weenie} Dewpoints are well below forecast here in CT. Another point is that pressure values in upstate NY and northern New England are higher than progged, even compared to the latest RUC forecasts. {/weenie} This is the kind of stuff I like to see. It would be quite an undertaking to compare current conditions (all aspects) to what was forecasted but I feel it is a real good way to decipher how the models are verifying. It doesn't always have to be related to a storm qpf/track, etc. Is the high pressure areas that is a key component to the evolution of this storm in the position anticipated, if not what is the error in placement and is it more or less favorable? Is the pressure center stronger than what was dpeicted at this point, can it become even stronger before showtime? It would also be beneficial to look downstream at 50/50 lows, SE Ridges, Blocking if any, etc. and see if things are positioned the way they were forecasted. These are the types of questions that give us hints on how the models are handling things and sure would shed some light on potential outcomes models are depicting. Of course the kind of effort needed to take this on would require a lot of time to spare and of course many of us are not in such a situation, meteorologist or hobbyist. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted January 31, 2011 Share Posted January 31, 2011 You don't think a cold layer of that depth (and significance - look at how cold the air is just above the surface on earthlight's sounding) would be enough to supercool a drop? Don't forget all the thermal energy goes into melting a snowflake - only once it is completely melted will the temperature of the raindrop begin to rise. I just don't think it'd be that much of an issue... I doubt the raindrop is going to warm to a full 40F or something. I assume it will be near freezing to begin with. Great post, Jake. During a phase change, the temperature of the object does not change. It only change once the phase change is completely finished. Link to comment Share on other sites More sharing options...
Alpha5 Posted January 31, 2011 Share Posted January 31, 2011 23/-4 Ice storm incoming Link to comment Share on other sites More sharing options...
Dsnowx53 Posted January 31, 2011 Share Posted January 31, 2011 23/-4 Ice storm incoming Wow, your DP is -4!? We're at 26/16 in New Brunswick. Link to comment Share on other sites More sharing options...
nzucker Posted January 31, 2011 Share Posted January 31, 2011 23/-4 Ice storm incoming I am starting to feel that way as well. 22.4/3 here... Link to comment Share on other sites More sharing options...
riverrat Posted January 31, 2011 Share Posted January 31, 2011 Yeah but in EWR for instance, 18z gfs is 0.23" snow tonight changing to 0.25" freezing rain by 1PM tmrw. The warm layer is no greater than 1-2ºC, but it is deep.. Then we get a break..Then 0.33" freezing rain tmrw night changing to rain tmrw morning (almost 0.5" rain). I wouldnt be surprised if the 0.25" freezing rain tmrw morning is actually sleet, but even then, that doesnt amount to 4-8 Is it possible that they are not basing their forecast on strict model interpretation alone? I know they have a lot of coordination between surrounding offices and HPC. Link to comment Share on other sites More sharing options...
BxEngine Posted January 31, 2011 Share Posted January 31, 2011 Wow, your DP is -4!? We're at 26/16 in New Brunswick. 25º/7º here in the lower hudson valley... Link to comment Share on other sites More sharing options...
Zir0b Posted January 31, 2011 Share Posted January 31, 2011 Wow, your DP is -4!? We're at 26/16 in New Brunswick. CAA still in progress...we should get to single digit dewpoints in a few hours before the WAA kicks in from the first wave Link to comment Share on other sites More sharing options...
Quincy Posted January 31, 2011 Share Posted January 31, 2011 23/-7 in Danbury not that it makes much of a difference, but NAM/RUC have temps dropping like a rock the next few hours. I'm skeptical. as for what happens Tue/Wed, I don't think our low temps tonight are much of a factor. (unless it somehow bottoms out very cold) Link to comment Share on other sites More sharing options...
Bobby Posted January 31, 2011 Share Posted January 31, 2011 22/2 in Kings Park. Link to comment Share on other sites More sharing options...
jm1220 Posted January 31, 2011 Share Posted January 31, 2011 Ice events are just about always nowcasting. That's mostly been my experience in central PA. Link to comment Share on other sites More sharing options...
joeydel Posted January 31, 2011 Share Posted January 31, 2011 With the low dewpoints being reported, won't that "waste" some of the coming snow as virga? If so, is that taken into account in the forecast? Link to comment Share on other sites More sharing options...
Mr Torchey Posted February 1, 2011 Share Posted February 1, 2011 23/-7 in Danbury not that it makes much of a difference, but NAM/RUC have temps dropping like a rock the next few hours. I'm skeptical. as for what happens Tue/Wed, I don't think our low temps tonight are much of a factor. (unless it somehow bottoms out very cold) Radiational cooling has nothing to do with what happens in the mid levels starting later tonight into tomorrow, hopefully precip is heavy enough tom to stay all snow, some good dynamical cooling in the column. As for round two, hopefully the primary occludes earlier and hands energy off se of ACY, that would cool the entire column enough for many areas to stay frozen, the surface IMHO has never been an issue, plenty of HP to our north with ne winds. I hope the snow/sleet scenario plays out for a multitude of reasons, as should we all. Link to comment Share on other sites More sharing options...
jasonli18t Posted February 1, 2011 Share Posted February 1, 2011 22/6 here Link to comment Share on other sites More sharing options...
Bobby Posted February 1, 2011 Share Posted February 1, 2011 22/6 here going to be interesting for us J. to see how this plays out. Link to comment Share on other sites More sharing options...
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