Rib Posted January 6, 2011 Share Posted January 6, 2011 Post discussion and obs for tomorrows event for the NYC area here. Link to comment Share on other sites More sharing options...
earthlight Posted January 6, 2011 Share Posted January 6, 2011 12z SPC WRF almost makes tomorrows band look convective. It's interesting, given the upper air dynamics, how this has turned into somewhat less of a norlun trough for many, any more of an arctic squall line. This is going to be a fun event to track. Regardless of who gets the most snow, I think the potential is there for a very heavy snow squall tomorrow. Originally we were talking about mainly light snow with the potential for more under the norlun, but these are very high reflectivities (35-40+dbz) being depicted by a very good short to near term mesoscale model. This could get fun, even if it's only for an hour or two. Link to comment Share on other sites More sharing options...
eduggs Posted January 6, 2011 Share Posted January 6, 2011 Perhaps a silly question from an amateur - everything I have read about this type of system is that it is unstable and relatively hard to forecast. The primer that someone had posted a few dozen pages back about the events in Maine and the Cape mentioned that the systems caught everyone totally unaware. Now, I understand that the models have improved since then, and more attention is being paid to this type of system. Is there any remaining sense, however, that the QPF amounts, and the relative strength of the system, are still going to be poorly-modeled? So, would it be fair to say that the more important feature on the models is the existence of "a storm," while all of the details, including QPF, the set-up of the strongest band, etc., are really going to be beyond the ability of the models to accurate forecast? Yes I believe this is a fair assessment. In my opinion forecasting the position, duration, and intensity of snowfall bands for this upcoming scenario is somewhat analogous to predicting mesoscale banding imbedded in a general precip shield. Link to comment Share on other sites More sharing options...
am19psu Posted January 6, 2011 Share Posted January 6, 2011 As I was saying, the WRF-NMM and WRF-ARW cores show a big difference west of NYC for this threat. NMM Clown Map: ARW Clown Map: Link to comment Share on other sites More sharing options...
eduggs Posted January 6, 2011 Share Posted January 6, 2011 12z SPC WRF almost makes tomorrows band look convective. It's interesting, given the upper air dynamics, how this has turned into somewhat less of a norlun trough for many, any more of an arctic squall line. This is going to be a fun event to track. Regardless of who gets the most snow, I think the potential is there for a very heavy snow squall tomorrow. Originally we were talking about mainly light snow with the potential for more under the norlun, but these are very high reflectivities (35-40+dbz) being depicted by a very good short to near term mesoscale model. This could get fun, even if it's only for an hour or two. Yeah I think it's basically an arctic or rather polar front. Great low level convergence and a moisture stream right off the Atlantic. Eventually hints of a surface low center may even develop along this boundary. Link to comment Share on other sites More sharing options...
NittanyWx Posted January 6, 2011 Share Posted January 6, 2011 As I was saying, the WRF-NMM and WRF-ARW cores show a big difference west of NYC for this threat. NMM Clown Map: Any idea how these two handle Norlun events? I've always used the MM5 to look for banding within 24-36 hours of an event. In theory, though..I'd suspect this is one of the reasons the ARW was designed with convective capabilities. Link to comment Share on other sites More sharing options...
snywx Posted January 6, 2011 Share Posted January 6, 2011 NMM & ARW look to be focusing hard on elevation dependent snowfall.. In Orange county you can see the higher elevation areas recieving a good amount in comparison to low lying areas. Link to comment Share on other sites More sharing options...
gravitylover Posted January 6, 2011 Share Posted January 6, 2011 NMM & ARW look to be focusing hard on elevation dependent snowfall.. In Orange county you can see the higher elevation areas receiving a good amount in comparison to low lying areas. I'm hoping for a similar effect in Putnam county but I'm not seeing it showing up on these maps. Link to comment Share on other sites More sharing options...
NEXtreme Posted January 6, 2011 Share Posted January 6, 2011 Steve D's final snow map is up: http://www.nynjpaweather.com/public-forecasts/ The focus should be on Mesoscale data. Link to comment Share on other sites More sharing options...
Nikolai Posted January 6, 2011 Share Posted January 6, 2011 Steve D's final snow map is up: http://www.nynjpawea...blic-forecasts/ The focus should be on Mesoscale data. That map is LOLworthy Anyone broadbrushing anything over 3-4" is out of their mind, the area of highest (aka 4"+) accumulations is going to be very limited and almost definitely not coastal CT/LI. Link to comment Share on other sites More sharing options...
jasonli18t Posted January 6, 2011 Share Posted January 6, 2011 Steve D's final snow map is up: http://www.nynjpawea...blic-forecasts/ The focus should be on Mesoscale data. Wow that looks terrible to me, even though it jackpots me. It is terrible once you get north of NYC, what is he looking at? Link to comment Share on other sites More sharing options...
Stormlover74 Posted January 6, 2011 Share Posted January 6, 2011 I feel lke we are trying to forecast where thunderstorms might pop up in the summer. I mean I could just as easily see 1" or 6" at this point 24-30 hours from now Any idea how these two handle Norlun events? I've always used the MM5 to look for banding within 24-36 hours of an event. In theory, though..I'd suspect this is one of the reasons the ARW was designed with convective capabilities. Link to comment Share on other sites More sharing options...
ag3 Posted January 6, 2011 Share Posted January 6, 2011 New Srefs's: Link to comment Share on other sites More sharing options...
eduggs Posted January 6, 2011 Share Posted January 6, 2011 Steve D's final snow map is up: http://www.nynjpawea...blic-forecasts/ The focus should be on Mesoscale data. Not in love with that forecast. Interesting concepts however. I think that's too high a baseline for NYC and WLI in particular. If the banding goes crazy, which it might, and he verifies in the tri-state, I think inland areas will bust low. Link to comment Share on other sites More sharing options...
CTNoreaster Posted January 6, 2011 Share Posted January 6, 2011 For what its worth. This might change as it was created early this morning. Link to comment Share on other sites More sharing options...
dtk Posted January 6, 2011 Share Posted January 6, 2011 Any idea how these two handle Norlun events? I've always used the MM5 to look for banding within 24-36 hours of an event. In theory, though..I'd suspect this is one of the reasons the ARW was designed with convective capabilities. This is one of the problems with WRF (and MM5, and any type of modeling that uses common infrastructure). The ARW and NMM components of the WRF are actually in how the dynamics are modeled (i.e. the grid used, and solvers used for the main dynamical/thermodynamical equations). Both versions of the WRF dynamics have "convective capabilities", though I'm not even sure what that means, since it depends on the spatial resolution and parameterizations chosen to model the sub-grid scale processes. In fact, I'm almost certain you can run in either mode with any combination of physics packages (I say almost certain since I don't do regional/mesoscale modeling anymore, but that was the intent originally). Having said all that, I believe that the ARW and NMM aren't being run in compatible fashions, so it's comparing apples to oranges in some regards. I have no idea how either versions of the model performs for these types of events Link to comment Share on other sites More sharing options...
Guest Patrick Posted January 6, 2011 Share Posted January 6, 2011 There have been several attempts to compare neighborhood-based verification of the short term hi res models such as the ARW and NMM components, but they specifically pertain to warm season events. Indeed there are entire books and journals available on that topic, but very little to nothing during the winter season. Tomorrow's event (or non-event, depending on your neighborhood) is not likely to become clear until it happens. I see the Sref s are out, showing not more than .25 in the NY metro area. This is one of the problems with WRF (and MM5, and any type of modeling that uses common infrastructure). The ARW and NMM components of the WRF are actually in how the dynamics are modeled (i.e. the grid used, and solvers used for the main dynamical/thermodynamical equations). Both versions of the WRF dynamics have "convective capabilities", though I'm not even sure what that means, since it depends on the spatial resolution and parameterizations chosen to model the sub-grid scale processes. In fact, I'm almost certain you can run in either mode with any combination of physics packages (I say almost certain since I don't do regional/mesoscale modeling anymore, but that was the intent originally). Having said all that, I believe that the ARW and NMM aren't being run in compatible fashions, so it's comparing apples to oranges in some regards. I have no idea how either versions of the model performs for these types of events Link to comment Share on other sites More sharing options...
snywx Posted January 6, 2011 Share Posted January 6, 2011 Steve D's final snow map is up: http://www.nynjpawea...blic-forecasts/ The focus should be on Mesoscale data. I like Steve D but this map is wayy out to lunch.. I have no idea what model he is looking at let alone his thinking.. If anything DT first guess map makes more sense then this... Not the amounts but his area of concentration.. Link to comment Share on other sites More sharing options...
dtk Posted January 6, 2011 Share Posted January 6, 2011 There have been several attempts to compare neighborhood-based verification of the short term hi res models such as the ARW and NMM components, but they specifically pertain to warm season events. Indeed there are entire books and journals available on that topic, but very little to nothing during the winter season. Tomorrow's event (or non-event, depending on your neighborhood) is not likely to become clear until it happens. I see the Sref s are out, showing not more than .25 in the NY metro area. The SREF members are run at quite a bit lower resolution, just something to keep in mind. Link to comment Share on other sites More sharing options...
Brian5671 Posted January 6, 2011 Share Posted January 6, 2011 I like Steve D but this map is wayy out to lunch.. I have no idea what model he is looking at let alone his thinking.. If anything DT first guess map makes more sense then this... Not the amounts but his area of concentration.. Honestly though, both seem way over-done. Link to comment Share on other sites More sharing options...
NittanyWx Posted January 6, 2011 Share Posted January 6, 2011 This is one of the problems with WRF (and MM5, and any type of modeling that uses common infrastructure). The ARW and NMM components of the WRF are actually in how the dynamics are modeled (i.e. the grid used, and solvers used for the main dynamical/thermodynamical equations). Both versions of the WRF dynamics have "convective capabilities", though I'm not even sure what that means, since it depends on the spatial resolution and parameterizations chosen to model the sub-grid scale processes. In fact, I'm almost certain you can run in either mode with any combination of physics packages (I say almost certain since I don't do regional/mesoscale modeling anymore, but that was the intent originally). Having said all that, I believe that the ARW and NMM aren't being run in compatible fashions, so it's comparing apples to oranges in some regards. I have no idea how either versions of the model performs for these types of events When the WRF model update 3.0 occurred I was still an undergraduate at PSU. Part of that adjustment meant fine-tuning a few of the metrics they were using to identify convective parcels (i.e. "looking" for the most unstable parcel in the lowest 40% of the atmosphere vs. lowest 20%, in that same vein, not eliminating parcels that do not have the highest theta-e..but rather determine if those parcels become positively buoyant in the higher atmospheric levels once it reaches the LCL, only triggering deep/shallow convection for parcels at specific grid points which have positive CAPE and a whole bunch more that are written down in one of my notebooks somewhere). I know those updates were specific to the NMM, but wasn't sure what fine tuning was done to the ARW. The perks of a higher resolution for the WRF is (in theory) being able to pinpoint specific convective events and adjust precipitation forecasts accordingly. I'm just thinking out loud here, but I recall (or think I do) that WRF researchers were using the ARW as a test-phase modeling program where they were still adjusting the parameterizations to try and pinpoint convective events, and the NMM was designed to be the operational WRF model (not that convective parameterizations were specific to either model). I may be wrong on that...it's been a couple of years since I've done research on mesoscale modeling. Link to comment Share on other sites More sharing options...
dtk Posted January 6, 2011 Share Posted January 6, 2011 When the WRF model update 3.0 occurred I was still and undergraduate at PSU. Part of that adjustment meant fine-tuning a few of the metrics they were using to determine buoyancy (i.e. "looking" for the most unstable parcel in the lowest 40% of the atmosphere vs. lowest 20%, in that same vein, not eliminating parcels that do not have the highest theta-e..but rather determine if those parcels become positively buoyant in the higher atmospheric levels once it reaches the LCL, only triggering deep/shallow convection for parcels at specific grid points which have positive CAPE and a whole bunch more that are written down in one of my notebooks somewhere). I know those updates were specific to the NMM, but wasn't sure what fine tuning was done to the ARW. But this sounds like something specific to one of the parameterization schemes.... I don't know the details, but it is possible that they have slight variants of the convective schemes for the NMM and ARW models respectively (I only know the contents of what is being run/developed at/by NCEP). Link to comment Share on other sites More sharing options...
snywx Posted January 6, 2011 Share Posted January 6, 2011 Honestly though, both seem way over-done. Thats why I said this... I like Steve D but this map is wayy out to lunch.. I have no idea what model he is looking at let alone his thinking.. If anything DT first guess map makes more sense then this... Not the amounts but his area of concentration.. Link to comment Share on other sites More sharing options...
NEXtreme Posted January 6, 2011 Share Posted January 6, 2011 That map is LOLworthy Anyone broadbrushing anything over 3-4" is out of their mind, the area of highest (aka 4"+) accumulations is going to be very limited and almost definitely not coastal CT/LI. He gives his expertise in meteorology as to why he issued that snowfall map. Now you give your reasoning as to why you believe in what you are saying besides saying some models says so. I would rather take the word of a met then some amateurs who flip flop over each model run and live and die from them every day. Besides he's not the only one calling for high snow totals. Will he be right? IDK..Will he be wrong? IDK... The event hasn't taken place yet so lets see what happens before issuing LOL's . Link to comment Share on other sites More sharing options...
jasonli18t Posted January 6, 2011 Share Posted January 6, 2011 He gives his expertise in meteorology as to why he issued that snowfall map. Now you give your reasoning as to why you believe in what you are saying besides saying some models says so. I would rather take the word of a met then some amateurs who flip flop over each model run and live and die from them every day. Besides he's not the only one calling for high snow totals. Will he be right? IDK..Will he be wrong? IDK... The event hasn't taken place yet so lets see what happens before issuing LOL's . it's his alignment that is more absurd than the totals. it is much easier to defend his map being ridiculous than defending the legitimacy of it, so i'm not sure what you want here. every computer model says his map is wrong is some major way or another...every single one. That's my defense, and it's a pretty strong one. Link to comment Share on other sites More sharing options...
gkrangers Posted January 6, 2011 Share Posted January 6, 2011 At least this'll be pretty easy to measure. Link to comment Share on other sites More sharing options...
Nikolai Posted January 6, 2011 Share Posted January 6, 2011 He gives his expertise in meteorology as to why he issued that snowfall map. Now you give your reasoning as to why you believe in what you are saying besides saying some models says so. I would rather take the word of a met then some amateurs who flip flop over each model run and live and die from them every day. Besides he's not the only one calling for high snow totals. Will he be right? IDK..Will he be wrong? IDK... The event hasn't taken place yet so lets see what happens before issuing LOL's . He's one of the only ones, and the only one with the highest area over Long Island. My thoughts and opinions are fairly irrelevant, but I've never flip flopped and have said the NY area will see a general light event with the potential for isolated areas to see 6"+, potentially up to a foot in the heaviest spots. It's naive to think that someone could pinpoint the exact area of heaviest snows though, and his "expertise" has been shown to be extremely faulty in the past. Anyone recall Vday '07? Link to comment Share on other sites More sharing options...
Snowshack Posted January 6, 2011 Share Posted January 6, 2011 He's one of the only ones, and the only one with the highest area over Long Island. My thoughts and opinions are fairly irrelevant, but I've never flip flopped and have said the NY area will see a general light event with the potential for isolated areas to see 6"+, potentially up to a foot in the heaviest spots. It's naive to think that someone could pinpoint the exact area of heaviest snows though, and his "expertise" has been shown to be extremely faulty in the past. Anyone recall Vday '07? It is VERY easy to point to blown calls for ANYONE in this field. Link to comment Share on other sites More sharing options...
Nikolai Posted January 6, 2011 Share Posted January 6, 2011 It is VERY easy to point to blown calls for ANYONE in this field. Steve has a history of being overly aggressive when it comes to extreme weather (particularly snow), not just for the NYC metro but for I-95 in general. Personally I'd rank him alongside Analog96 as one of the region's unrealistically optimistic mets when it comes to snow which is fine when we have a large event, but in general, I wouldn't rely on him to forecast a snowstorm. We'll see come verification time on Saturday whether I'm right or wrong in this case. Link to comment Share on other sites More sharing options...
ace0927 Posted January 6, 2011 Share Posted January 6, 2011 Honestly though, both seem way over-done. way overdone...divide most areas around NYC by 3 (or more) Link to comment Share on other sites More sharing options...
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