earthlight Posted March 22, 2013 Share Posted March 22, 2013 The NAM is usually too overamplified late in its range. Canadian was probably wrong too given how much its ensembles disagreed with it. We really need to see a north trend soon in other guidance for us to have a shot. Well even if we assume the ECMWF is more correct in handling the main players within the mean trough out west...I still think there will be a small window for the coastal low to amplify at the last minute. You can see some of the SREF members individually picking up on this. There is a small vort max ahead of the main trough that gets captured as the gyre heads east through the Mid Atlantic states on most of these SREF members. It may be high resolution model crap...or it may be legitimate. The Euro was close to amplifying the secondary low at the last moment, but didn't quite pull it off. You can loop through the SREF's here (most of them are amplified and hits) http://www.meteo.psu.edu/~fxg1/SREF21500NE_9z/srefloop.html Link to comment Share on other sites More sharing options...
Snow_Miser Posted March 22, 2013 Share Posted March 22, 2013 The NAM should look very similar to its 6z run. Seems to have recovered in the latest frames. Link to comment Share on other sites More sharing options...
earthlight Posted March 22, 2013 Share Posted March 22, 2013 The NAM is leaning towards the ECMWF with the lead vort that runs out ahead of the primary PVA back over the OH Valley. That vort max is already over OBX at 57 hours ...we need the main vort to move east and catch up with it. If this doesn't happen...like the ECMWF shows...the entire system becomes very disjointed and compressed underneath the confluence. Which by the way is 50-100 miles farther south on this run. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 The NAM should look very similar to its 6z run. Seems to have recovered in the latest frames. When you look at the precip fields at hour 60 it's going to need to come way north. From hour 57-63 the coastal slides ENE. Actually not that different than previous runs. It amplifies and recovers very late just in time to tug it up the coast on previous runs. May do the same here. Link to comment Share on other sites More sharing options...
MJO812 Posted March 22, 2013 Share Posted March 22, 2013 Secondary and primary are south of the 6z run through 63. Doesn't look like a big difference though. Link to comment Share on other sites More sharing options...
Snow_Miser Posted March 22, 2013 Share Posted March 22, 2013 I was going to say that, the ULL looks like it's way out of the way this run, but when you look at the precip fields at hour 60 it's going to need to come way north. From hour 57-63 the coastal slides ENE. It's still less amplified than the 6z run and will likely be a bit south, but I don't think dramatic changes will occur this run. Link to comment Share on other sites More sharing options...
Snow_Miser Posted March 22, 2013 Share Posted March 22, 2013 This run will produce. Great look at hour 66. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 The NAM pulled it off, pretty big hit starting at hr 72. Combined moisture from the primary and the coastal. Link to comment Share on other sites More sharing options...
MJO812 Posted March 22, 2013 Share Posted March 22, 2013 Nice hit at hour 72 for D.C - NYC http://mag.ncep.noaa.gov/Image.php?model=nam&area=namer¶m=sim_radar&cycle=12ℑ=nam%2F12%2Fnam_namer_072_sim_radar.gif Link to comment Share on other sites More sharing options...
JSantanaNYC Posted March 22, 2013 Share Posted March 22, 2013 Wow every post you read about the nam is like a roller coaster. Some say the same.. (good) other say bad (euro). Damn Link to comment Share on other sites More sharing options...
CooL Posted March 22, 2013 Share Posted March 22, 2013 Looking good at 75. There were some changes but the storm is still there Link to comment Share on other sites More sharing options...
Snow_Miser Posted March 22, 2013 Share Posted March 22, 2013 Great VVs now at hour 72 from Philly into New Jersey working their way north and east. Link to comment Share on other sites More sharing options...
earthlight Posted March 22, 2013 Share Posted March 22, 2013 The NAM is leaning towards the ECMWF with the lead vort that runs out ahead of the primary PVA back over the OH Valley. That vort max is already over OBX at 57 hours ...we need the main vort to move east and catch up with it. If this doesn't happen...like the ECMWF shows...the entire system becomes very disjointed and compressed underneath the confluence. Which by the way is 50-100 miles farther south on this run. You can literally watch this occur at 72 hours..the NAM interacts the main trough with the lead vort max and is able to tug the secondary low a little closer to the coast than the Euro and GFS. But this run definitely was a nod towards the global models which are farther southeast. Link to comment Share on other sites More sharing options...
earthlight Posted March 22, 2013 Share Posted March 22, 2013 Wow every post you read about the nam is like a roller coaster. Some say the same.. (good) other say bad (euro). Damn Whoever is saying the NAM is the same as the last run either isn't looking at the correct model run or doesn't know how to interpret model guidance. Link to comment Share on other sites More sharing options...
jm1220 Posted March 22, 2013 Share Posted March 22, 2013 The NAM is leaning towards the ECMWF with the lead vort that runs out ahead of the primary PVA back over the OH Valley. That vort max is already over OBX at 57 hours ...we need the main vort to move east and catch up with it. If this doesn't happen...like the ECMWF shows...the entire system becomes very disjointed and compressed underneath the confluence. Which by the way is 50-100 miles farther south on this run. Good to know we still have a number of ways to produce with this storm. We definitely want a phase with some additional vort energy to force a slight rise in heights and faster development of the coastal low. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 By hour 78 it's sitting south of the benchmark. We get the benefit of the late transfer because we get good over running before the coastal arrives. The precip shield begins to die off as the coastal takes over. By hour 81 it's starting to slide OTS. QPF ends up being pretty much in line with most of the other guidance. Link to comment Share on other sites More sharing options...
WintersGrasp Posted March 22, 2013 Share Posted March 22, 2013 Hmm...to me it doesn't look at all like its last run. To see it easy, just look at the total QPF in the end. Western extent in PA is cut in half and our areas are almost cut in half too....big big change and seems to be trending to the other models Link to comment Share on other sites More sharing options...
MJO812 Posted March 22, 2013 Share Posted March 22, 2013 Nam's low position is similiar to the GGEM, maybe a little south. I am not sure who was talking about the sharp northern cutoff but that might be the case with this storm. Link to comment Share on other sites More sharing options...
jm1220 Posted March 22, 2013 Share Posted March 22, 2013 By hour 78 it's sitting south of the benchmark. We get the benefit of the late transfer because we get good over running before the coastal arrives. The precip shield begins to die off as the coastal takes over. By hour 81 it's starting to slide OTS. QPF ends up being pretty much in line with most of the other guidance. The confluence needs to be a little more cooperative-the low can only get so far north with that mammoth a block north of here. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 Hmm...to me it doesn't look at all like its last run. To see it easy, just look at the total QPF in the end. Western extent in PA is cut in half and our areas are almost cut in half too....big big change and seems to be trending to the other models This run is significantly drier for everyone. Looking at the zoomed in maps NYC gets into moderate precip for about 10-12 hours. Link to comment Share on other sites More sharing options...
MJO812 Posted March 22, 2013 Share Posted March 22, 2013 This run is significantly drier for everyone. Looking at the zoomed in maps NYC gets into moderate precip for about 10-12 hours. Yes it is. A lot more models to go with this. With the AO rising, I think this will come more north but not too much further north due to the insane blocking. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 If it wasn't for the last minute pull northward this would have exited stage right off the NC coast. The vort passes right over DC and the whole thing deamplifies. We were very close this run to a miss. The confluence needs to be a little more cooperative-the low can only get so far north with that mammoth a block north of here. Link to comment Share on other sites More sharing options...
WintersGrasp Posted March 22, 2013 Share Posted March 22, 2013 The last NAM run, IF all snow was 7-10" for the NYC area. This run 2-4". Last run all of CT 5"+ and the state of MA almost all got 2-4". This run CT gets an inch or so and MA stays bone dry Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 Snow maps are in the 2-4" range for western sections and 1-2" range for the city and NE NJ. Nothing really for Long Island through hr 84. Maybe a coating for western Nassau. 00z and 06z had low end warning criteria for everyone. Link to comment Share on other sites More sharing options...
JERSEYSNOWROB Posted March 22, 2013 Share Posted March 22, 2013 Snow maps are in the 2-4" range for western sections and 1-2" range for the city and NE NJ. Nothing really for Long Island through hr 84. Maybe a coating for western Nassau. 00z and 06z had low end warning criteria for everyone. There's life outside of NW Jersey too. Looks ok for us folks south of the city. (And yes I'm being sarcastic because of all of your pro NW burbs posts) Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 There's life outside of NW Jersey too. Looks ok for us folks south of the city. (And yes I'm being sarcastic because of all of your pro NW burbs posts) Is there really a difference between 2-4 and 1-3? The majority of the precip falls from 12z Monday till 21z Monday which means if the NAM is correct this will be mostly a day time event. There is a 3-6 hour period this run where the snow could be considered heavy. That's likely when we'll most of our accumulations. We have an eternity to go with this one in terms of modeling. Only 12 more NAM runs between now and 12z Monday. Link to comment Share on other sites More sharing options...
forkyfork Posted March 22, 2013 Share Posted March 22, 2013 the consensus is for this to stay to our south. the nam and ggem are outliers. Link to comment Share on other sites More sharing options...
dbc Posted March 22, 2013 Share Posted March 22, 2013 the consensus is for this to stay to our south. the nam and ggem are outliers. I have been doing this long enough to know that some consensus at 84-90 hours doesn't mean anything and what is depicted now will not verify, book it. Link to comment Share on other sites More sharing options...
MJO812 Posted March 22, 2013 Share Posted March 22, 2013 Gfs looks pretty bad. Going to kick se. Primary is more west Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 22, 2013 Share Posted March 22, 2013 I have been doing this long enough to know that some consensus at 84-90 hours doesn't mean anything and what is depicted now will not verify, book it. Yeah I agree, the overall performance of the models in the medium range has been awful this year. Whenever we seem to be getting close to a consenus something happens to throw things off. It's not a knock at the models themselves. Some of the setups this season, this event included have been very complex with small differences in timing and position making large differences in the overall outcome. Link to comment Share on other sites More sharing options...
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