rygar Posted December 28, 2012 Share Posted December 28, 2012 I remember the NAM doing this with the big storms 2 and 3 years ago, jumping up the precip before the storm and then backing off. Very cautious here. Link to comment Share on other sites More sharing options...
TWCCraig Posted December 28, 2012 Share Posted December 28, 2012 Link to comment Share on other sites More sharing options...
winterwarlock Posted December 28, 2012 Share Posted December 28, 2012 that rain/snow line is creeping ever so close Link to comment Share on other sites More sharing options...
BL03 Posted December 28, 2012 Share Posted December 28, 2012 NAM thumps us as the low starts bombing off LI (21z-00z) ... this is the difference between 2-4" and 4-6"+. srefs are very encouraging..lets see how gfs see's it. Link to comment Share on other sites More sharing options...
IsentropicLift Posted December 28, 2012 Share Posted December 28, 2012 yea, im sure it will keep trending NW until your backyard is in the jackpot....just like the last system was trending colder and more SE. the nam was thrown out yesterday and now today, its the guidance of choice. bi-polar snow weenies! Watch who you're calling a weenie. All of the guidance is ticking further NW with each run. Why would that trend suddenly stop? It may, but that remains to be seen. I personally didn't throw out the NAM yesterday, but it didn't really have any support for what it was showing. Now the NAM might be on the wetter side of the consensus but it's the first of the 12z suite so time will tell how much of an outlier it really is. Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 I remember the NAM doing this with the big storms 2 and 3 years ago, jumping up the precip before the storm and then backing off. Very cautious here. I would be too, but having the SREFs ticking northwestward is pretty telling. We also have a very big RGEM run coming up in a few moments. It's been amplified and north/west the entire time. Link to comment Share on other sites More sharing options...
TWCCraig Posted December 28, 2012 Share Posted December 28, 2012 850's stay below freezing the entire storm for here; Southern New Jersey goes above freezing according to 12z NAM. I'm not really worried about the 850's. It's the 900-975mb is where I'm concerned. Link to comment Share on other sites More sharing options...
Stormlover74 Posted December 28, 2012 Share Posted December 28, 2012 But often it does that without a shift in the track, just a QPF bomb showing 2 to 3" of liquid and then backing off. In this case what it is showing makes sense based on the position and strength of the low. My fear is that we still see an area in between that misses out, kind of like March 09, where the initial batch moves through quickly, weakens and then the better dynamics set up east. With that said in that particular storm I was expecting 8 to 10" so 4.5 was disappointing. If I see anything over 4 tomorrow I'll be happy since yesterday I thought we'd be lucky to see 2" I remember the NAM doing this with the big storms 2 and 3 years ago, jumping up the precip before the storm and then backing off. Very cautious here. Link to comment Share on other sites More sharing options...
WintersGrasp Posted December 28, 2012 Share Posted December 28, 2012 Watch who you're calling a weenie. All of the guidance is ticking further NW with each run. Why would that trend suddenly stop? It may, but that remains to be seen. I personally didn't throw out the NAM yesterday, but it didn't really have any support for what it was showing. Now the NAM might be on the wetter side of the consensus but it's the first of the 12z suite so time will tell how much of an outlier it really is. Actually...the NAM backed off in ITSELF from that big run to line itself up with the other models. It was consensus, so yes I agree with you here Link to comment Share on other sites More sharing options...
KEITH L.I Posted December 28, 2012 Share Posted December 28, 2012 well if that happens on Long island..with this setup..I give up.Will start counting down to pitchers and catchers Link to comment Share on other sites More sharing options...
Metsfan Posted December 28, 2012 Share Posted December 28, 2012 850's stay below freezing the entire storm for here; Southern New Jersey goes above freezing according to 12z NAM. I'm not really worried about the 850's. It's the 900-975mb is where I'm concerned. That's what I'm worried about too, but as long as the precip comes down hard enough with good vv's we should have no problem evap cooling. Link to comment Share on other sites More sharing options...
TWCCraig Posted December 28, 2012 Share Posted December 28, 2012 well if that happens on Long island..with this setup..I give up.Will start counting down to pitchers and catchers We'll see if the evaporational cooling that occurs can cool the column. 850's look good for us, we just need the 900-975mb layers to cool and then we'll definitely be all snow. Link to comment Share on other sites More sharing options...
RUNNAWAYICEBERG Posted December 28, 2012 Share Posted December 28, 2012 Watch who you're calling a weenie. All of the guidance is ticking further NW with each run. Why would that trend suddenly stop? It may, but that remains to be seen. I personally didn't throw out the NAM yesterday, but it didn't really have any support for what it was showing. Now the NAM might be on the wetter side of the consensus but it's the first of the 12z suite so time will tell how much of an outlier it really is. now thats a non weenie, more logical approach...which i agree with. and give me a break with the "watch who you calling a weenie".....if you post silly stuff you will be called out on it. so watch what you post, is my suggestion. Link to comment Share on other sites More sharing options...
bluewave Posted December 28, 2012 Share Posted December 28, 2012 If these stronger NAM VVEL's verify, I would guess that the NAM P-Types are too pessimistic at the coast and it would be a heavy wet snow instead of rain. Could mix with rain before the heavier echoes arrive and evap cooling takes over. Snow fall rates would overcome initially warm BL and snow would be able to accumulate. Link to comment Share on other sites More sharing options...
Isotherm Posted December 28, 2012 Share Posted December 28, 2012 That's what I'm worried about too, but as long as the precip comes down hard enough with good vv's we should have no problem evap cooling. Agree. I think there will be an area of significant mixing within 1-2 miles of the shore in LI and NJ; however, most of the time modelling tends to overdo the inland extent of rain/mixing with sfc lows to our SE. The 12z NAM is almost as good as it gets track wise. The reason pcpn is "limited" is b/c of the progressive nature of the short wave and somewhat delayed intensification/bombogenesis. The storm doesn't get sub 995mb until much of the snow is over for us. The 12z NAM is a snowy scenario for the area as it stands, but it we want to see more snow than this, the low must bomb a bit quicker. For 90% of the region, we should be all snow given the synoptics. Link to comment Share on other sites More sharing options...
NJwinter23 Posted December 28, 2012 Share Posted December 28, 2012 If you are going to suddenly fall in love with the nam after dismissing it for days, you have to at least also consider how warm it is. "warm bias" aside, it shows a closed 850 low over pittsburgh at hr 27 and closes off the 700 low in upstate NY Link to comment Share on other sites More sharing options...
PB GFI Posted December 28, 2012 Share Posted December 28, 2012 If these stronger NAM VVEL's verify, I would guess that the NAM P-Types are too pessimistic at the coast and it would be a heavy wet snow instead of rain. Could mix with rain before the heavier echoes arrive and evap cooling takes over. Dude, I agree if the GFS sees this QPF with this rapid deepening , I think you put the mixing issue to bed for most . Link to comment Share on other sites More sharing options...
IsentropicLift Posted December 28, 2012 Share Posted December 28, 2012 now thats a non weenie, more logical approach...which i agree with. and give me a break with the "watch who you calling a weenie".....if you post silly stuff you will be called out on it. so watch what you post, is my suggestion. If I had said it will continue to tick further NW for no rhyme or reason, yes that's a weenie statement, which I didn't. The reason for the NW movement is simple. The initial wave is stronger/sharper and goes negative tilt over the TN Valley on the latest NAM which builds the heights along the coast. Link to comment Share on other sites More sharing options...
PB GFI Posted December 28, 2012 Share Posted December 28, 2012 If you are going to suddenly fall in love with the nam after dismissing it for days, you have to at least also consider how warm it is. "warm bias" aside, it shows a closed 850 low over pittsburgh at hr 27 and closes off the 700 low in upstate NY Fair point , thats why I will wait for GFS , and see if agrees withe the SREF and RGEM . You have to admit the same Errors occur in these Models almost everytime 48 hrs out on SE systems as there bias is to run them south and east - only to come back North and West . Link to comment Share on other sites More sharing options...
LocoAko Posted December 28, 2012 Share Posted December 28, 2012 12Z NAM BUFKIT accounting for compaction showing 4.3" at TTN, 5.8" at LGA, 5.4" at EWR, and 4.6" at RUTG. RUTG switches over to rain at the very tail end of the moderate precipitation, along with a light period of ZR tomorrow evening. Link to comment Share on other sites More sharing options...
Isotherm Posted December 28, 2012 Share Posted December 28, 2012 Fair point , thats why I will wait for GFS , and see if agrees withe the SREF and RGEM . You have to admit the same Errors occur in these Models almost everytime 48 hrs out on SE systems as there bias is to run them south and east - only to come back North and West . In this case the rather wimpy -NAO signal is helping to keep heights somewhat high off the East Coast, preventing an out to sea solution. A raging, strong -NAO would have probably meant no snow given the current pattern. Link to comment Share on other sites More sharing options...
LocoAko Posted December 28, 2012 Share Posted December 28, 2012 At stations like LGA, the entire column from 20Z on between the surface and 875 hPa is isothermal at 0C... would only take the smallest budge to make things pretty sloppy there. By 01Z as stated before the surface is below freezing but there's a layer centered at 925 hPa awfully close to freezing. Link to comment Share on other sites More sharing options...
bluewave Posted December 28, 2012 Share Posted December 28, 2012 Dude, I agree if the GFS sees this QPF with this rapid deepening , I think you put the mixing issue to bed for most . Yeah, we'll see if the GFS comes more into line with the SREF's and NAM. Link to comment Share on other sites More sharing options...
SnoSki14 Posted December 28, 2012 Share Posted December 28, 2012 Once the coastal is deepening offshore, it's all snow for most. Link to comment Share on other sites More sharing options...
NJwinter23 Posted December 28, 2012 Share Posted December 28, 2012 Agree. I think there will be an area of significant mixing within 1-2 miles of the shore in LI and NJ; however, most of the time modelling tends to overdo the inland extent of rain/mixing with sfc lows to our SE. The 12z NAM is almost as good as it gets track wise. The reason pcpn is "limited" is b/c of the progressive nature of the short wave and somewhat delayed intensification/bombogenesis. The storm doesn't get sub 995mb until much of the snow is over for us. The 12z NAM is a snowy scenario for the area as it stands, but it we want to see more snow than this, the low must bomb a bit quicker. For 90% of the region, we should be all snow given the synoptics. careful, verbatim it would go over to all snow for the coastal/se areas when the 850 low transfers and the coastal really intensifies, but before then this is what you have. then this would fall as snow this is all of course taking the nam verbatim Link to comment Share on other sites More sharing options...
Storm At Sea Posted December 28, 2012 Share Posted December 28, 2012 Latest SREF is also much warmer. In fact, CNJ and places south and east have some mixing issues say from Manalpan south and east. Fair point , thats why I will wait for GFS , and see if agrees withe the SREF and RGEM . You have to admit the same Errors occur in these Models almost everytime 48 hrs out on SE systems as there bias is to run them south and east - only to come back North and West . Link to comment Share on other sites More sharing options...
earthlight Posted December 28, 2012 Share Posted December 28, 2012 RGEM looks NAM-ish on precipitation type maps. Link to comment Share on other sites More sharing options...
IsentropicLift Posted December 28, 2012 Share Posted December 28, 2012 For us folks a little further NW, 2-3" seems like the best case even with the 12z NAM as you can see below. This is for KMMU 121229/1500Z 39 09004KT 30.6F SNOW 6:1| 0.1|| 0.00|| 0.00|| 0.015 6:1| 0.1|| 0.00|| 0.00|| 0.01 100| 0| 0 121229/1600Z 40 06004KT 30.8F SNOW 7:1| 0.1|| 0.00|| 0.00|| 0.021 7:1| 0.2|| 0.00|| 0.00|| 0.04 100| 0| 0 121229/1700Z 41 06003KT 31.4F SNOW 12:1| 0.3|| 0.00|| 0.00|| 0.024 9:1| 0.5|| 0.00|| 0.00|| 0.06 100| 0| 0 121229/1800Z 42 VRB02KT 31.5F SNOW 13:1| 0.5|| 0.00|| 0.00|| 0.039 10:1| 1.0|| 0.00|| 0.00|| 0.10 100| 0| 0 ----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+--- 121229/1900Z 43 02004KT 31.5F SNOW 13:1| 0.4|| 0.00|| 0.00|| 0.033 11:1| 1.5|| 0.00|| 0.00|| 0.13 100| 0| 0 121229/2000Z 44 02006KT 31.9F SNOW 17:1| 0.4|| 0.00|| 0.00|| 0.021 12:1| 1.8|| 0.00|| 0.00|| 0.15 100| 0| 0 121229/2100Z 45 02006KT 31.7F SNOW 18:1| 0.3|| 0.00|| 0.00|| 0.016 13:1| 2.1|| 0.00|| 0.00|| 0.17 100| 0| 0 121229/2200Z 46 01006KT 31.4F SNOW 15:1| 0.4|| 0.00|| 0.00|| 0.025 13:1| 2.5|| 0.00|| 0.00|| 0.19 100| 0| 0 121229/2300Z 47 01006KT 31.4F SNOW 11:1| 0.1|| 0.00|| 0.00|| 0.011 13:1| 2.6|| 0.00|| 0.00|| 0.21 100| 0| 0 Link to comment Share on other sites More sharing options...
TWCCraig Posted December 28, 2012 Share Posted December 28, 2012 Very rarely does Cape Cod stay mostly snow and get 14" of snow when we get mixed and only 6" of snow. All this according to 12z NAM snow forecast map. Most of the time it's the other way around where we stay mostly snow and the Cape has mixing issues. Link to comment Share on other sites More sharing options...
IsentropicLift Posted December 28, 2012 Share Posted December 28, 2012 Very rarely does Cape Cod stay mostly snow and get 14" of snow when we get mixed and only 6" of snow. All this according to 12z NAM snow forecast map. Most of the time it's the other way around where we stay mostly snow and the Cape has mixing issues. Simple, the low is signficiantly deeper by that latitude and track is almost perfect for the Cape. Link to comment Share on other sites More sharing options...
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