stormspotterlive Posted February 17, 2012 Share Posted February 17, 2012 Count down = 40 minutes till the sref very interested to see if it continues it's north shift. Got nothing to loose the model was never trashed by the HPC today. Link to comment Share on other sites More sharing options...
ChescoWx Posted February 17, 2012 Share Posted February 17, 2012 For all the JB fans...back by popular demand - his latest "As we look to the 48-72 hour period, the northward extent of the major winter storm for the mid atlantic states rests with 3 factors as I see it, which are not likely to be clear until Saturday afternoon. But now that we know a couple of the factors have fallen into place, at least we know a storm is coming. For the record, at this time, there is no change in my forecast However lets look at the 18z 60 hour and we can see what we have to watch for as far as the more northward move which in spite of a slight trend south today in modeling, I still think is more likely . In other words at least until the NC coast, its more likely the track is north of my forecast than south if there is to be a correction. First of all, there is a wonderful double jet structure here with confluence northeast of the storm and a classic snowstorm 500 mb . But factor one is what looks to be a weaker upper feature by what could be as much as 60 meters in the main trough enhancing east. Factor 2 is the feedback feature that is so common in GFS forecasts and leads to a jumping of the low to the coast south, not north of Hatteras, as I think it will and 3 the mysterious small but powerful upper feature in front. Here is my take. every 10 meters stronger the upper trough is would be worth a move north of 10 miles. In other words if the 546 height line is in there, then the storm travels in relation to the coast another 60 miles north.. That it holds together and does not jump and comes off near va beach. The weaker the northern branch, the more north it comes also. But watch this.. at 60 hours you have a storm inland looking like its marching northeast on its merry way But at 72 hours, the feedback takes over and jumps the low to the coast.. south of Hatteras My take is this is further north.. and the heavy snow has worked into pa and NJ. As it is the precip swath ending 24 hours 12z Monday ( 90 hrs) keeps heavy snow south of the Mason Dixon line Again, one has to ask oneself, given the overall pattern and the usual bias on coastal storms, what is the more likely occurrence? Until I see how this looks Saturday I think this is liable to stay as the forecast" Link to comment Share on other sites More sharing options...
Grothar Posted February 17, 2012 Share Posted February 17, 2012 This was the British Colombian Short Wave. Using the Boxing Day timing of modeling corroboration as a guide, to get to the same point when those models came together we'd be talking about the 00z run on Saturday. So its too early. Now this sounds very realistic to me- finally a good analog Thanks Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted February 17, 2012 Share Posted February 17, 2012 JB holding on..... sooner or later he will score one but when? Link to comment Share on other sites More sharing options...
GD0815 Posted February 17, 2012 Share Posted February 17, 2012 JB holding on..... sooner or later he will score one but when? i'll go with later...SREFS pretty south, btw, for what that's worth. Link to comment Share on other sites More sharing options...
dan88 Posted February 17, 2012 Share Posted February 17, 2012 Thus far though 36, regarding the Southern shortwave, it's much closer to 12z then 18z The most interesting development thus far is a piece of the northern shortwave breaks off, and gets left behind as the northern shortwave continues onward, and appears as it may be preparing to phase. Regarding the split 12z from this morning New 00z run, take note of the vorticity in Nebraska Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 yea dan, this 0z run is a good bit more amplified. should be further north than 18z, it will be interesting to see how this run turns out. Link to comment Share on other sites More sharing options...
stormspotterlive Posted February 17, 2012 Share Posted February 17, 2012 MAJOR changes through hour 45 of the Nam a brand knew piece of northern stream energy trying to phase now lets see if it does. Link to comment Share on other sites More sharing options...
ChescoWx Posted February 17, 2012 Share Posted February 17, 2012 The JB north trend begins.... yea dan, this 0z run is a good bit more amplified. should be further north than 18z, it will be interesting to see how this run turns out. Link to comment Share on other sites More sharing options...
96blizz Posted February 17, 2012 Share Posted February 17, 2012 yea dan, this 0z run is a good bit more amplified. should be further north than 18z, it will be interesting to see how this run turns out. No doubt. Each 3 hr increment is making the tease more tantalizing... That piece of energy in NE did pull this thing up and, for those who know more, did recon data help here, because this thing looks jacked... Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 No doubt. Each 3 hr increment is making the tease more tantalizing... That piece of energy in NE did pull this thing up and, for those who know more, did recon data help here, because this thing looks jacked... this could be just the nam be wacko...you gotta see other guidance., but this should be a good bit north Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 the nam is completely night and day compared to the 18z run...not sure if this is fishy or what. The low position in the south is already a good 200 miles or so further north... Link to comment Share on other sites More sharing options...
tcutter Posted February 17, 2012 Share Posted February 17, 2012 the nam is completely night and day compared to the 18z run...not sure if this is fishy or what. The low position in the south is already a good 200 miles or so further north... or just better data??? Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 hr 63 already has precip on the m/d line...primary over nw ga, secondary trying to pop over eastern nc Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 mod snow now into phl and south jersey and all of del... .25 up to pa turnpike hr 72..central and southern del cash in if temps cooperate Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 temps below freezing from 295 in jersey east, through hr 75 .25 up to ttn... .5 up to phl... central and southern del 1-1.25..s jerz .5-1... Link to comment Share on other sites More sharing options...
famartin Posted February 17, 2012 Share Posted February 17, 2012 Looking at the last 5 NAM runs its clear that the off-hours shift south and the synoptic's shift north. Yesterday's 0Z was north, 6Z was south, 12Z was north, 18Z was south, 0Z north again. Link to comment Share on other sites More sharing options...
GD0815 Posted February 17, 2012 Share Posted February 17, 2012 still a very tight gradient, and also the NAM always has one of these runs where it doubles the QPF and it never verifies.... Link to comment Share on other sites More sharing options...
mattinpa Posted February 17, 2012 Share Posted February 17, 2012 Much better run, but we'll see if it's a trend. I was thinking it looks like the GFS, only wetter. Link to comment Share on other sites More sharing options...
tcutter Posted February 17, 2012 Share Posted February 17, 2012 Looking at the last 5 NAM runs its clear that the off-hours shift south and the synoptic's shift north. Yesterday's 0Z was north, 6Z was south, 12Z was north, 18Z was south, 0Z north again. if you average them all out is there any overall shift (north or south) or does it even matter?? Link to comment Share on other sites More sharing options...
ezweather Posted February 17, 2012 Share Posted February 17, 2012 Here's my two cents worth after looking at this run. Its a pretty impressive storm with lots of moisture with it. Two things from what I see with this run. 850mb low is broad and passes just to the south and east of Philly. Thats very important if you want snow. You would want that to track a bit off to your east.. Checking the 700mb RH fields through 75.. Looks like precip cuts off sometime during the evening. Overall track of the low goes from the Gulf Coast state east northeast to North Carolina. . I can see this event being one starting with some rain and then changing over to heavy wet snow. Still lots many more model runs to see how this will pan out, but the key thing is that the low can only track so far north. I kind of think Philly is like New England where we might have the best cold air, but its marginal. Anyway, interesting run.. Link to comment Share on other sites More sharing options...
stormspotterlive Posted February 17, 2012 Share Posted February 17, 2012 Did some comparing with the GFS and serfs what is very interesting is that the 18z GFS was just a pin needle away from this solution it try's to do the same thing as the Nam at H5 but does not fully get there. as for past sref indivuall members any run that was north held back northern stream energy phased and brought it more north like the Nam. From my experiences I see 2 things here 1 Nam is the model that usually starts the North shifts and 2 this is never usually 1 and done we very well may see more models do this tonight. Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 philly just misses the good snow on this run...nam sim radar hr 66 Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 also one thing to note here..not sure if you can still follow this but they say usually best nsow rates/ratios are along the -8 850 line, which goes right through the philly area... Link to comment Share on other sites More sharing options...
famartin Posted February 17, 2012 Share Posted February 17, 2012 temps below freezing from 295 in jersey east, through hr 75 .25 up to ttn... .5 up to phl... central and southern del 1-1.25..s jerz .5-1... The gradient is very tight because here's the QPF: MPO 0.00 FWN 0.00 12N 0.00 MMU 0.00 ABE 0.01 SMQ 0.01 RDG 0.04 UKT 0.06 DYL 0.09 TTN 0.11 PTW 0.16 NXX 0.16 BLM 0.19 LOM 0.21 PNE 0.24 WRI 0.29 NEL 0.31 MQS 0.33 VAY 0.33 PHL 0.37 ILG 0.53 ACY 0.81 MIV 0.87 DOV 1.06 ESN 1.19 GED 1.25 Link to comment Share on other sites More sharing options...
famartin Posted February 17, 2012 Share Posted February 17, 2012 if you average them all out is there any overall shift (north or south) or does it even matter?? Not really much of a trend. Link to comment Share on other sites More sharing options...
tombo82685 Posted February 17, 2012 Share Posted February 17, 2012 thats a cold skew t for phl....jeez didnt see it getting this cold Link to comment Share on other sites More sharing options...
cast4 Posted February 17, 2012 Share Posted February 17, 2012 The gradient is very tight because here's the QPF: MPO 0.00 FWN 0.00 12N 0.00 MMU 0.00 ABE 0.01 SMQ 0.01 RDG 0.04 UKT 0.06 DYL 0.09 TTN 0.11 PTW 0.16 NXX 0.16 BLM 0.19 LOM 0.21 PNE 0.24 WRI 0.29 NEL 0.31 MQS 0.33 VAY 0.33 PHL 0.37 ILG 0.53 ACY 0.81 MIV 0.87 DOV 1.06 ESN 1.19 GED 1.25 Pretty much like 2/5/10 with regards to the cutoff. Link to comment Share on other sites More sharing options...
tcutter Posted February 17, 2012 Share Posted February 17, 2012 Not really much of a trend. ok.....thanks....i was just curious Link to comment Share on other sites More sharing options...
famartin Posted February 17, 2012 Share Posted February 17, 2012 Pretty much like 2/5/10 with regards to the cutoff. Main difference is lack of cold, at least as far north as TTN a bit of that at the beginning is rain (though probably not much). Further southeast, more rain. Link to comment Share on other sites More sharing options...
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