jm1220 Posted September 24, 2014 Share Posted September 24, 2014 Hope this same set-up/model 'progression' pattern keeps up Dec-Mar A similar storm in the winter would be a changeover to rain or mostly rain. The flow is out of the SE around the departing high and there would be tons of mid level warm air too. Link to comment Share on other sites More sharing options...
bluewave Posted September 24, 2014 Share Posted September 24, 2014 The 9Z SREF mean moved toward the 0Z Euro idea of the heaviest rainfall east of NYC. 3z 9z Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 Once again the 12z 4k NAM has all of the heavy convection over NJ. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 The 9Z SREF mean moved toward the 0Z Euro idea of the heaviest rainfall east of NYC. 3z f87.jpg 9z f81.jpg Still a fairly large spread Link to comment Share on other sites More sharing options...
Weathergun Posted September 24, 2014 Share Posted September 24, 2014 The 12z NAM has the same issue the 0z Euro has with convective blob further east robbing us. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 The 12z NAM has the same issue the 0z Euro has with convective blob further east robbing us. I have a really hard time believing that. All of the strong verticle velocity and RH fields point towards a large commadhead feature extending into NE PA and southern NY. We're dealing with a surface low pressure here, not a blob of convection. The forcing is weak so I am skeptical. Link to comment Share on other sites More sharing options...
MJO812 Posted September 24, 2014 Share Posted September 24, 2014 12z Nam still shows a good amount of rain for NYC. Much needed rain at that. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 24, 2014 Share Posted September 24, 2014 The fact that this system is so weak makes this storm more prone to error via convection. A convective blob to the east robbing us would not surprise me at all, but some of the very wet solutions also wouldn't surprise me.Just a lot of unknowns with a weak storm system with a few hybrid tropical characteristics and some convection. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 I know this may come across as a bit of a weenie comment but the 4k version of the NAM has been incredibly stable since at least 12z yesterday. It is once again showing the heaviest rains over the greater NYC metro area. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 24, 2014 Share Posted September 24, 2014 I have a really hard time believing that. All of the strong verticle velocity and RH fields point towards a large commadhead feature extending into NE PA and southern NY. We're dealing with a surface low pressure here, not a blob of convection. The forcing is weak so I am skeptical. The 12z NAM showed plenty of upper-level divergence, which in my opinion could have led to more precipitation than what was actually modeled. That being said, look at how disjointed some of it is -- there are a lot of gaps and weaknesses in it. Gonna cause a lot of forecasting headaches. The strongest frontogenic forcing and omega did shift a bit southeast this run as well. Link to comment Share on other sites More sharing options...
CIK62 Posted September 24, 2014 Share Posted September 24, 2014 My barometer is still rising from a high reading of 30.55" a few minutes ago. This seems counter intuitive when you have a forecast of rain beginning in about 15 hours. Any technical explanation for this? A few days ago this HP was going to cause a right turn for this system at our latitude and then wind shear would rip the low apart to our east. What happened? Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 My barometer is still rising from a high reading of 30.55" a few minutes ago. This seems counter intuitive when you have a forecast of rain beginning in about 15 hours. Any technical explanation for this? A few days ago this HP was going to cause a right turn for this system at our latitude and then wind shear would rip the low apart to our east. What happened? If you read the NE forum a few of the mets have talked about this. The system is being pushed southeast not because of the high pressure, but as a result of a kicker disturbance that will be moving through SE Canada overnight. The WV loop shows quick flow over SE Canada currently which is going to aid in the right hard turn as well as shearing this apart some at it tries to come north. Link to comment Share on other sites More sharing options...
Weathergun Posted September 24, 2014 Share Posted September 24, 2014 The 12z NAM showed plenty of upper-level divergence, which in my opinion could have led to more precipitation than what was actually modeled. That being said, look at how disjointed some of it is -- there are a lot of gaps and weaknesses in it. Gonna cause a lot of forecasting headaches. The strongest frontogenic forcing and omega did shift a bit southeast this run as well. 8.gif The lower-level dynamics shifted east with the convective blob. I don't know if it's for real or not. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 Why has the 4k NAM been so much more stable than 12k version? If you loop through it has been amazingly consistent with all of the features since yesterday. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 24, 2014 Share Posted September 24, 2014 The low-level dymanics shifted east with the convective blob. I don't know if it's for real or not. I'm honestly not sure either. But with a weak storm system that does not have a lot of true synoptic forcing, the chances of a convective blob at least somewhat robbing our moisture might be higher than normal. But an error back to the other way is still possible as well. Either way, I do think there will be a heavy rain band (lift), a distinct subsidence zone, and then another area of lift further east, rather than one true consolidated area of precip. The size of the subsidence zone and where these features are is still a big question mark. Link to comment Share on other sites More sharing options...
NEG NAO Posted September 24, 2014 Share Posted September 24, 2014 What is interesting is this coastal is developing with a positive NAO - don't always need a negative NAO for coastals especially if a couple other indicies are favorable http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao_index.html Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 24, 2014 Share Posted September 24, 2014 My barometer is still rising from a high reading of 30.55" a few minutes ago. This seems counter intuitive when you have a forecast of rain beginning in about 15 hours. Any technical explanation for this? A few days ago this HP was going to cause a right turn for this system at our latitude and then wind shear would rip the low apart to our east. What happened? The high pressure will be shifting east as the day goes on, which will give us an onshore flow and help to initially squeeze the storm further west. The onshore flow from the high combined with the onshore flow from the low will be helping to pump in plenty of moisture in/near our area. Once the low gains enough latitude and gets closer to the high, the precip should then get shunted -- which is why a lot of New England may not see much rain at all. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 Almost time to start watching the HRRR. The 13z run compares closest to the 4k NAM. Link to comment Share on other sites More sharing options...
Weathergun Posted September 24, 2014 Share Posted September 24, 2014 I'm honestly not sure either. But with a weak storm system that does not have a lot of true synoptic forcing, the chances of a convective blob at least somewhat robbing our moisture might be higher than normal. But an error back to the other way is still possible as well. Either way, I do think there will be a heavy rain band (lift), a distinct subsidence zone, and then another area of lift further east, rather than one true consolidated area of precip. The size of the subsidence zone and where these features are is still a big question mark. I can see the error toward either direction as well. I'm not sure, if the models are going to properly resolve these features. It looks very messy aloft, when this system get close to us. I think we'll be nowcasting more as well. Link to comment Share on other sites More sharing options...
forkyfork Posted September 24, 2014 Share Posted September 24, 2014 when all else fails look at the 4km Link to comment Share on other sites More sharing options...
Weathergun Posted September 24, 2014 Share Posted September 24, 2014 Big blow convection off Carolina coast. Models may struggle with this. Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 The 12z RGEM looks pretty solid Link to comment Share on other sites More sharing options...
bluewave Posted September 24, 2014 Share Posted September 24, 2014 12z GFS in the heaviest rain east of NYC camp. Link to comment Share on other sites More sharing options...
SnoSki14 Posted September 24, 2014 Share Posted September 24, 2014 12z GFS in the heaviest rain east of NYC camp. Will the models finally get it right with forecasting these events? They've been so off lately that I honestly don't know what will happen until it starts to happen. It's definitely getting breezy though. Link to comment Share on other sites More sharing options...
Stormlover74 Posted September 24, 2014 Share Posted September 24, 2014 Will the models finally get it right with forecasting these events? They've been so off lately that I honestly don't know what will happen until it starts to happen. It's definitely getting breezy though. No. This happened all last winter and got worse over the summer. No reason for it to change now. Link to comment Share on other sites More sharing options...
bluewave Posted September 24, 2014 Share Posted September 24, 2014 Will the models finally get it right with forecasting these events? They've been so off lately that I honestly don't know what will happen until it starts to happen. It's definitely getting breezy though. The stronger high pressure to our north has been forcing rainfall a little further south and east recently so the models see the shift in the short term. The Islip deluge in August started out west and shifted east. The heavy rain forecast for SNJ recently shifted east under 36 hrs. Link to comment Share on other sites More sharing options...
Weathergun Posted September 24, 2014 Share Posted September 24, 2014 Buoys/marine stations off Norfolk, VA now reporting wind gusts in the low 40mph range: http://www.wrh.noaa.gov/mesowest/getobext.php?sid=CHLV2 http://www.wrh.noaa.gov/mesowest/getobext.php?sid=44064 http://www.wrh.noaa.gov/mesowest/getobext.php?sid=CBBV2 Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 Not much change with the RGEM, a tad wetter if anything. 12z 06z Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 24, 2014 Author Share Posted September 24, 2014 The 12z GEFS mean is wetter than the OP. Link to comment Share on other sites More sharing options...
Sundog Posted September 24, 2014 Share Posted September 24, 2014 The 12z GEFS mean is wetter than the OP. Do you have a good link to the ensembles? Link to comment Share on other sites More sharing options...
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