Brian5671 Posted January 18, 2012 Share Posted January 18, 2012 Not wishcasting .Think back to the past 2 Sundays when the models were beaten by the low level cold air . The models are notorious for not seeing low level dense air til inside 24- 48 hrs The numbers at the surface get beat with direct arcitc air for a reason , the model bias is to quickly warm the boundary layer and is usually right when its polar pacific air ( WHICH OVERWHELMED THE PATTERN IN NYC SINCE DEC ) , but it really has a hard time in low level air ( AND THIS TIME THE AIR IS ARCTIC IN NATURE and has been the last 2 weeks when the models missed those past wknd temps ive seen this happen a lot in my life following the weather here in NYC so i think we trend colder as the models start to see the temp busts in the midwest that will occur over the next 2 days Good point Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 I'm still concerned that the mid level centers will trend warmer. Usually in situations like this, with a southwest flow event, the mid level warm air advection occurs faster than forecast. With a high pressure to the north of our area keeping at least a moderately favorable synoptic setup for low level cold air to hold on for a few hours...I could easily see this develop into a situation similar to a few days ago, albeit a bit colder. The mid level warm air advection would cause more sleet than snow before a changeover to rain, despite a colder surface. I guess we will see. But carefully watch the trends on the H85 and H925 hpa lows and 0c "line". Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 I disagree that the UKIE is similar to the NAM at hour 72. In fact, the UKIE is COLDER then the GFS and the precip is just entering NYC, just like the gfs. 12z ukie @ hour 72 has the 850 line in Southern Jersey, while the GFS and NAM have it in central Jersey: Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 And the precip is just about to enter NYC at hour 72, just like the GFS: Link to comment Share on other sites More sharing options...
Stormlover74 Posted January 18, 2012 Share Posted January 18, 2012 Different setup of course but that was something I remember about VD07. We started as snow but it quickly went over to sleet and remained that way. I think there was supposed to be more snow on the front end, at least 1 to 2" but I remember having less than an hour of snow before hearing those ice pellets hitting the window. I'm still concerned that the mid level centers will trend warmer. Usually in situations like this, with a southwest flow event, the mid level warm air advection occurs faster than forecast. With a high pressure to the north of our area keeping at least a moderately favorable synoptic setup for low level cold air to hold on for a few hours...I could easily see this develop into a situation similar to a few days ago, albeit a bit colder. The mid level warm air advection would cause more sleet than snow before a changeover to rain, despite a colder surface. I guess we will see. But carefully watch the trends on the H85 and H925 hpa lows and 0c "line". Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 Different setup of course but that was something I remember about VD07. We started as snow but it quickly went over to sleet and remained that way. I think there was supposed to be more snow on the front end, at least 1 to 2" but I remember having less than an hour of snow before hearing those ice pellets hitting the window. It's the case with almost every southwest flow event. Obviously not to the dramatic extent of VD07---but for the most part the forecast models typically are too slow with their forecast for the mid level warm air advection. I find that typically the southwest flow events begin quicker, and changeover quicker than forecast. In this situation..the cold air source to the north is actually half decent for such a crappy pattern. But the shortwave is embedded in an amplifying mean flow. So it could still bump the mid level centers to the north as we approach the event. I think there is room for an adjustment either way, really. We will see. Link to comment Share on other sites More sharing options...
Metsfan Posted January 18, 2012 Share Posted January 18, 2012 The 12Z GFS shows a good CAD signature for the storm to start off as snow, and how long this cold air at the surface can hold on will determine how much snow falls before the changeover to fzra/ip, as WAA warm the surface and 850s to sligtly above freezing. Areas N and W stay all snow. Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 12z GGEM is fairly similar to the GFS (A touch warmer). Drops .25"-.30" while its cold enough. 850 line is just north of NYC at hour 78, while .25"-.30" has already fallen. Looks like a solid 2"-3". Link to comment Share on other sites More sharing options...
blizzardof09 Posted January 18, 2012 Share Posted January 18, 2012 PB GFI your statement does hold some merit being that the air that will be entrenched in the northeast would be true arctic air and not of pacific origin which the models may be forecasting it as or factoring it as. This system js for sure our first real true threat and certainly looks to produce frozen precip nyc north and east but the temps as far as rising above or staying below freezing for coastal areas still needs to be watched very carefully Link to comment Share on other sites More sharing options...
jiksports Posted January 18, 2012 Share Posted January 18, 2012 12z GGEM is fairly similar to the GFS. Drops .25"-.30" while its cold enough. 850 line is just north of NYC at hour 78, while .25"-.30" has already fallen. Looks like a solid 2"-3". Surface temps are so closely tied to 850's that the snow might actually stick. Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 The 12z GEFS were cooler than the OP at 84 hours by a good margin (relatively speaking for our forecast area). The mean 850 0c line only gets as far north as Sandy Hook NJ. The 1000-500hpa thicknesses are a bit cooler compared to last nights 00z runs. So that is a good sign if you're worried about the mid level trends as I mentioned above. Link to comment Share on other sites More sharing options...
Weathergun Posted January 18, 2012 Share Posted January 18, 2012 I'm still concerned that the mid level centers will trend warmer. Usually in situations like this, with a southwest flow event, the mid level warm air advection occurs faster than forecast. With a high pressure to the north of our area keeping at least a moderately favorable synoptic setup for low level cold air to hold on for a few hours...I could easily see this develop into a situation similar to a few days ago, albeit a bit colder. The mid level warm air advection would cause more sleet than snow before a changeover to rain, despite a colder surface. I guess we will see. But carefully watch the trends on the H85 and H925 hpa lows and 0c "line". I'm concerned about the mid-level warmth trending warmer too. But as that increases, the precip might also increase farther out ahead of the storm. Link to comment Share on other sites More sharing options...
TheTrials Posted January 18, 2012 Share Posted January 18, 2012 The 12z GEFS were cooler than the OP at 84 hours by a good margin (relatively speaking for our forecast area). The mean 850 0c line only gets as far north as Sandy Hook NJ. The 1000-500hpa thicknesses are a bit cooler compared to last nights 00z runs. So that is a good sign if you're worried about the mid level trends as I mentioned above. It's way over by 84. What does it show before that. Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 It's way over by 84. What does it show before that. Colder then the operational at hour 72 and 84. NCEP will update soon and we'll know hour 78: Link to comment Share on other sites More sharing options...
jiksports Posted January 18, 2012 Share Posted January 18, 2012 The 12z GEFS were cooler than the OP at 84 hours by a good margin (relatively speaking for our forecast area). The mean 850 0c line only gets as far north as Sandy Hook NJ. The 1000-500hpa thicknesses are a bit cooler compared to last nights 00z runs. So that is a good sign if you're worried about the mid level trends as I mentioned above. Looks to be a bit north of that, depending on whether you measure at the top of the line or at the bottom: Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 NMM for the clipper: http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/hrw-nmm/20120118/12/hrw-nmm_eus_042_sim_radar.gif http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/hrw-nmm/20120118/12/hrw-nmm_eus_045_sim_radar.gif Link to comment Share on other sites More sharing options...
ace0927 Posted January 18, 2012 Share Posted January 18, 2012 nice!! yeah, that's def. still snow. Good for them. do you not see the thickness chart and graph on the lower left? Its not all snow... Link to comment Share on other sites More sharing options...
ag3 Posted January 18, 2012 Share Posted January 18, 2012 JMA was very warm until the 12z run. It's now the coldest by far and has the 850 line south of DC at hour 72: Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 It's way over by 84. What does it show before that. 84 is the warmest point. Most of the precipitation has fallen by then...but there is still some falling. It's not "way over". It's an ensemble mean, so some members are slower than others. But it is definitely a good bit cooler than the operational for sure. Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 Looks to be a bit north of that, depending on whether you measure at the top of the line or at the bottom: I'm using the stormvista maps. Maybe 5 miles north of Sandy hook. Link to comment Share on other sites More sharing options...
TheTrials Posted January 18, 2012 Share Posted January 18, 2012 do you not see the thickness chart and graph on the lower left? Its not all snow... Lol. I can read a sounding. It's snow still all layers below 0 unless I'm going blind. Link to comment Share on other sites More sharing options...
TheTrials Posted January 18, 2012 Share Posted January 18, 2012 well go back and look at the thicknesses Dude the plot is snow regardless of the thickneses. Warmest level is surface a smidge above 0 and there is room to wet bulb. It's mid January it snows even with your thickness with a sounding like that. Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 Well...we'll hopefully get a better idea of what's in store with the Euro in a few moments. Out to 36 hr. Biggest Euro run of the winter? Link to comment Share on other sites More sharing options...
Chris L Posted January 18, 2012 Share Posted January 18, 2012 Different setup of course but that was something I remember about VD07. We started as snow but it quickly went over to sleet and remained that way. I think there was supposed to be more snow on the front end, at least 1 to 2" but I remember having less than an hour of snow before hearing those ice pellets hitting the window. VD 2007 was going to be 1 to 2 feet of snow for us all...It really was. Of course, NAM-GFS-ECMWF did not see the warm layer at mid level. Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2012 Share Posted January 18, 2012 Of course, NAM-GFS-ECMWF did not see the warm layer at mid level. No..they did...they were screaming for sleet. Link to comment Share on other sites More sharing options...
SBUWX23 Posted January 18, 2012 Share Posted January 18, 2012 Dude the plot is snow regardless of the thickneses. Warmest level is surface a smidge above 0 and there is room to wet bulb. It's mid January it snows even with your thickness with a sounding like that. Just like it did Monday night! Link to comment Share on other sites More sharing options...
Stormlover74 Posted January 18, 2012 Share Posted January 18, 2012 Yeah 3 days out, I'm talking about hours before the storm started. I remember expecting several inches of snow and instead it quickly went to sleet. Once inside 48 hours most of the crazy snow totals went out the window for us. VD 2007 was going to be 1 to 2 feet of snow for us all...It really was. Of course, NAM-GFS-ECMWF did not see the warm layer at mid level. Link to comment Share on other sites More sharing options...
jiksports Posted January 18, 2012 Share Posted January 18, 2012 No..they did...they were screaming for sleet. Then we have to deal with all those people running around screaming "it's hailing, it's hailing!" Link to comment Share on other sites More sharing options...
NEG NAO Posted January 18, 2012 Share Posted January 18, 2012 The 12z GEFS were cooler than the OP at 84 hours by a good margin (relatively speaking for our forecast area). The mean 850 0c line only gets as far north as Sandy Hook NJ. The 1000-500hpa thicknesses are a bit cooler compared to last nights 00z runs. So that is a good sign if you're worried about the mid level trends as I mentioned above. This setting up to be one of those situations where the raritan river in NJ is going to end up being the snow/rain line for a good part of the storm - we have seen this countless times in the past seems to be a natural dividing line because many areas south and east of there are going to be exposed to the warmer then normal ocean temps especially if there is an easterly component to the flow - we last saw this back in the october storm ................ Link to comment Share on other sites More sharing options...
Chris L Posted January 18, 2012 Share Posted January 18, 2012 No..they did...they were screaming for sleet. Thanks John for correcting me. I know the NAM was too cold at mid levels, but I wasn't sure of the others. Link to comment Share on other sites More sharing options...
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