Nikolai Posted October 28, 2012 Share Posted October 28, 2012 Wow lots of discussion over weather its a hurricane or noreaster. No discussion at all about how we're going to survive the next 5 days. What would you expect the impacts to be in NYC (wind and surge wise)? Link to comment Share on other sites More sharing options...
David Reimer Posted October 28, 2012 Share Posted October 28, 2012 What would you expect the impacts to be in NYC (wind and surge wise)? NWS Upton increased the surge levels about 90 minutes ago. For now, lets stick with a general estimate of 50-70 MPH sustained with gusts up to 90 MPH with a surge up to 10 feet. That's if the models are right in showing a 100 knot jet at 900 MB. If Sandy ends up making landfall at 950 MB, 900 MB will be about 1,000 feet ASL. Link to comment Share on other sites More sharing options...
mike2010 Posted October 28, 2012 Share Posted October 28, 2012 NWS Upton increased the surge levels about 90 minutes ago. doesn't matter. Bloomberg still needs a hurricane warning for evacs.. Link to comment Share on other sites More sharing options...
David Reimer Posted October 28, 2012 Share Posted October 28, 2012 doesn't matter. Bloomberg still needs a hurricane warning for evacs.. I wasn't really talking about Bloomberg. Time will tell if he is right or wrong. Link to comment Share on other sites More sharing options...
Dark Energy Posted October 28, 2012 Share Posted October 28, 2012 I am sad that this storm is being treated as Tropical vice baroclinic. The former is what NYC is going with and the reason they are not telling people to get out. They will find out that this storm means bidness and is nothing like Irene. nothing at all. What an f-up by them. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted October 28, 2012 Share Posted October 28, 2012 NWS Upton increased the surge levels about 90 minutes ago. For now, lets stick with a general estimate of 50-70 MPH sustained with gusts up to 90 MPH with a surge up to 10 feet. That's if the models are right in showing a 100 knot jet at 900 MB. If Sandy ends up making landfall at 950 MB, 900 MB will be about 1,000 feet ASL. You're predicting these effects for NYC? Sustained winds of 60 kt with gusts to 80 kt in the city? Huh. We'll have data from JFK, LGA, and Central Park to review. Will be interesting to see! Link to comment Share on other sites More sharing options...
Tiburon Posted October 28, 2012 Share Posted October 28, 2012 I am sad that this storm is being treated as Tropical vice baroclinic. The former is what NYC is going with and the reason they are not telling people to get out. They will find out that this storm means bidness and is nothing like Irene. nothing at all. What an f-up by them. This is why I posted in the PHL thread that NHC was making a mistake with their nomenclature and warnings. People don't take noreaster's seriously around here. We get 4-5 of them a year. This is a once-in-50-year storm. People need to be aware. Link to comment Share on other sites More sharing options...
Srain Posted October 28, 2012 Share Posted October 28, 2012 12Z Tracks & Intensity: Link to comment Share on other sites More sharing options...
usedtobe Posted October 28, 2012 Share Posted October 28, 2012 Steve, those southern tracks actually decrease the winds somewhat over dca and the best winds spread out from the center a little. Instead we get a little lower gusts but heavier rain. Of course the heavier showers may do a better job of transporting the winds to the surface than being deeper in the cold air so who knows. Link to comment Share on other sites More sharing options...
Srain Posted October 28, 2012 Share Posted October 28, 2012 Link to comment Share on other sites More sharing options...
N. OF PIKE Posted October 28, 2012 Share Posted October 28, 2012 is sandy's warm core transitioning yet or has there been enuf convection to maintain the strength of her "warm core" the reason i ask is because of all the AFD's ....speaking about the initial resistance of a tropical entity crossing 5h heights and 1000-500 mb thickness and models perhaps not having great handle on this, and rushing a phase. any mets care to comment on this Link to comment Share on other sites More sharing options...
Mike.Ventrice Posted October 28, 2012 Share Posted October 28, 2012 is sandy's warm core transitioning yet or has there been enuf convection to maintain the strength of her "warm core" the reason i ask is because of all the AFD's ....speaking about the initial resistance of a tropical entity crossing 5h heights and 1000-500 mb thickness and models perhaps not having great handle on this, and rushing a phase. any mets care to comment on this The GFS indicates this system is still a warm core disturbance. The GFS does not predict a transition until after landfall somewhere over northern PA or southern NY. Link to comment Share on other sites More sharing options...
Srain Posted October 28, 2012 Share Posted October 28, 2012 12Z GFS...surge and coastal flooding potential are very concerning for this storm, IMO. Link to comment Share on other sites More sharing options...
Ridingtime Posted October 28, 2012 Share Posted October 28, 2012 I feel like the track of Sandy vs. Irene shows just why this is a much more dangerous beast in terms of surge. Irene basically came up from the south and went north grazing NC and then hitting NYC in the same basic direction. In that case, the surge had a chance to escape eastward and therefore was not the biggest deal. Sandy on the other hand has one of the craziest tracks: first going out east a bit, only to curve west directly straight pushing tons of ocean water into the "corner" that is part of MD, DE, NJ, and LI. In this case, the water can't escape and spills directly over land. Why Bloomberg played this one down is absolutely beyond me. Link to comment Share on other sites More sharing options...
uncle W Posted October 28, 2012 Share Posted October 28, 2012 Irene's flooding was mostly inland...Sandy's should be mostly along the coast if it doesn't stall...If it does there will be flooding in the usual spots everywhere...Wind speed records could fall as well around the NYC area... Link to comment Share on other sites More sharing options...
phil882 Posted October 28, 2012 Share Posted October 28, 2012 Here is a really nice illustration of the 12z High Resolution NAM depicting the thermal transition of Sandy as it makes landfall. While I typically don't endorse the NAM for tropical cyclones, it does seem to be representing a fairly accurate rapid transition of the central core of Sandy, which is acting more akin to an extratropical cyclone at this time. A 25C decrease in the core temperature in 24 hours. Not too shabby. Link to comment Share on other sites More sharing options...
BlizzardWx Posted October 28, 2012 Share Posted October 28, 2012 I feel like the track of Sandy vs. Irene shows just why this is a much more dangerous beast in terms of surge. Irene basically came up from the south and went north grazing NC and then hitting NYC in the same basic direction. In that case, the surge had a chance to escape eastward and therefore was not the biggest deal. Sandy on the other hand has one of the craziest tracks: first going out east a bit, only to curve west directly straight pushing tons of ocean water into the "corner" that is part of MD, DE, NJ, and LI. In this case, the water can't escape and spills directly over land. Why Bloomberg played this one down is absolutely beyond me. I think we can all agree its a stupid decision, but I still question the decision to not put up hurricane warnings. Maybe if they had then he would be taking it more seriously. But maybe not. Link to comment Share on other sites More sharing options...
wxsniss Posted October 28, 2012 Share Posted October 28, 2012 Any Mets here have answers to questions about the SLP discrepancies: 12z Euro init was at 961.5mb for 12z this morning 12z GFS init was at 965.7 mb for 12z this morning vs. 951-2mb actual (EDIT: add to this 12z HWRF which initializes at correct pressures and makes landfall in mid 930s.) (1) How do we expect this discrepancy to extrapolate through to landfall? All models predict another 10mb+ drop from init pressures. (2) Tracking typical nor'easters, a 10-15mb discrepancy would be a gross error. Are these differences less significant when we are dealing with such a low range? Appreciate any thoughts. Link to comment Share on other sites More sharing options...
QVectorman Posted October 28, 2012 Share Posted October 28, 2012 Storm surge and SWAN wave height model showing approx. 10 ft max storm surge around NYC in yellow shade. It has been pretty consistent with this forecasted ss height over the past 48 hrs. Link to comment Share on other sites More sharing options...
Derecho! Posted October 28, 2012 Share Posted October 28, 2012 Storm surge and SWAN wave height model showing approx. 10 ft max storm surge around NYC in yellow shade. It has been pretty consistent with this forecasted ss height over the past 48 hrs. Upton NWS is going higher, actually; LI Sound surge levels are beyond belief (well above 1938): ...NY HARBOR WATER LEVELS FOR MONDAY EVENING... COASTAL............TIME OF......FORECAST TOTAL.....FLOOD..... LOCATION...........HIGH TIDE.....WATER LEVEL.......CATEGORY.. ...................................(MLLW).................... THE BATTERY NYC.....813 PM.........11.7.............MAJOR.... BERGEN POINT NY.....814 PM.........12.3.............MAJOR.... ...WESTERN L.I. SOUND WATER LEVELS FOR MON EVENING... COASTAL............TIME OF......FORECAST TOTAL.....FLOOD..... LOCATION...........HIGH TIDE.....WATER LEVEL.......CATEGORY.. ...................................(MLLW).................... KINGS POINT NY......1227 AM........16.6.............MAJOR.... LATTINGTOWN NY......1205 AM........16.7.............MAJOR.... STAMFORD CT.........1201 AM........16.4.............MAJOR.... BRIDGEPORT CT.......1158 PM........15.9.............MAJOR.... NEW HAVEN CT........1157 PM........15.3.............MAJOR.... ...EASTERN L.I. SOUND WATER LEVELS FOR MON EVENING... COASTAL............TIME OF......FORECAST TOTAL.....FLOOD..... LOCATION...........HIGH TIDE.....WATER LEVEL.......CATEGORY.. ...................................(MLLW).................... NEW LONDON CT.......952 PM.........10.0.............MAJOR.... ...SOUTH SHORE BAYS WATER LEVELS FOR MON EVENING... COASTAL............TIME OF......FORECAST TOTAL.....FLOOD..... LOCATION...........HIGH TIDE.....WATER LEVEL.......CATEGORY.. ...................................(MLLW).................... E ROCKAWAY INLET NY..814 PM.........11.3/9.8.........MAJOR... FREEPORT GAGE NY.....858 PM.........10.6/9.8.........MAJOR... JAMAICA BAY NY.......900 PM.........11.6/9.4.........MAJOR... POINT LOOKOUT........801 PM.........11.0/7.0.........MAJOR... ...OCEAN WATER LEVELS FOR MON EVENING... COASTAL............TIME OF......FORECAST TOTAL.....FLOOD..... LOCATION...........HIGH TIDE.....WATER LEVEL.......CATEGORY.. ...................................(MLLW).................... MONTAUK POINT NY....102 AM.........8.5...............MAJOR... $$ Link to comment Share on other sites More sharing options...
Srain Posted October 28, 2012 Share Posted October 28, 2012 18Z Tracks & Intensity: Link to comment Share on other sites More sharing options...
phil882 Posted October 28, 2012 Share Posted October 28, 2012 Any Mets here have answers to questions about the SLP discrepancies: 12z Euro init was at 961.5mb for 12z this morning 12z GFS init was at 965.7 mb for 12z this morning vs. 951-2mb actual (EDIT: add to this 12z HWRF which initializes at correct pressures and makes landfall in mid 930s.) (1) How do we expect this discrepancy to extrapolate through to landfall? All models predict another 10mb+ drop from init pressures. (2) Tracking typical nor'easters, a 10-15mb discrepancy would be a gross error. Are these differences less significant when we are dealing with such a low range? Appreciate any thoughts. Some responses to your questions: 1) Global models almost always under analyze the minimum sea level pressure of tropical cyclones. In fact, they are doing better with Sandy mainly because its a much larger than normal storm. The models are forecasting some amount of deepening, but that will essentially depend on how the convection over Sandy orients itself over the next 24-36 hours. If we can get convection to build over the center, the inner core can become re-established and more deepening can occur. If the focus continues to be on the outer bands, deepening will likely be slower. 2) Such an error in the central pressure becomes less egregious the deeper the storm is. If the storm is only forecasted to be 990 hPa and verifies 10-15 hPa lower, that would be an egregious error because compared to the average mean sea level pressure (~1013 hPa) thats a 50-70% error! With very deep systems such as Sandy, a 10 hPa error is only around a ~15% error considering how deep it already is in comparison to mean sea level pressure. Thus, all this alarmist sediment for having the models incorrectly analyzing the central pressure is not really warranted. The overall consensus is that the models seem to have a decent handle on the current systems strength, and the storm may strengthen a little bit more prior to landfall. As is though, the storm is certainly capable of producing a near record storm surge, and evacuation orders near the most prone coastline in the northeast needs to be taking the necessary action! 3) The HWRF model has an absolutely dreadful track record this year and should not be your primary model of choice for this event. Link to comment Share on other sites More sharing options...
QVectorman Posted October 28, 2012 Share Posted October 28, 2012 Upton NWS is going higher, actually; LI Sound surge levels are beyond belief (well above 1938): Looks about right. I would take their forecast over the model since it is a model and they know the area better. But if you look at the scale those forecasts fit in. The model has a smoothed gradient scale so I just eyeballed it but 10-12 ft. surge fits the "yellow" color. Of course 15-17 ft. surge isn't predicted for Western LI which would be red. But as I said I would go with their forecast since they know the coastline. Link to comment Share on other sites More sharing options...
dtk Posted October 28, 2012 Share Posted October 28, 2012 Any Mets here have answers to questions about the SLP discrepancies: 12z Euro init was at 961.5mb for 12z this morning 12z GFS init was at 965.7 mb for 12z this morning vs. 951-2mb actual (EDIT: add to this 12z HWRF which initializes at correct pressures and makes landfall in mid 930s.) (1) How do we expect this discrepancy to extrapolate through to landfall? All models predict another 10mb+ drop from init pressures. (2) Tracking typical nor'easters, a 10-15mb discrepancy would be a gross error. Are these differences less significant when we are dealing with such a low range? Appreciate any thoughts. Phil already summed it up pretty nicely...but I'll try to add some to it. It really comes down to a matter of representativeness, i.e., what the numerical model can actually "resolve". For a model like the GFS (i.e. ~27km horizontal resolution), it simply cannot resolve the structure (gradients) of an intense tropical cyclone. If we were to simply drop the real cyclone with real gradients, the model would have a serious spin down issue (huge amounts of gravity waves would be generated, and the model would have to spin down to something it could actually resolve). Furthermore, what you are looking at when you see graphics is not truly representative of the actual model minimum pressure, since the graphics are generated from post-process files (i.e. taken the model fields at their native resolution in model coordinates, transforming them to a regular grid, in a specific format [grib], for visualization). Often times, this post-processing procedure can lead to a discrepency, as there can be upscaling (to coarser resolution) and/or smoothing operators applied. This is especially true for sea level pressure in the GFS (I do not believe that people are really aware, but we have multipile versions of "SLP" in our GFS post-processed files, some with less smoothing/more noise, and therefore more representative of what the actual model is producing). Link to comment Share on other sites More sharing options...
wxsniss Posted October 28, 2012 Share Posted October 28, 2012 Thanks all to these replies about SLP discrepancies. I'll quote your replies in subforums where several others have had the same question. Link to comment Share on other sites More sharing options...
Cheeznado Posted October 28, 2012 Share Posted October 28, 2012 I think this may come in faster than the current NHC forecast- 18Z GFS has landfall at 0Z, the 18Z WSI RPM even earlier than that. Pressure on the GFS 951. Link to comment Share on other sites More sharing options...
Thrasher Fan Posted October 28, 2012 Share Posted October 28, 2012 Snow accumulation projection through 72 hours… 18Z RPM Link to comment Share on other sites More sharing options...
Mallow Posted October 28, 2012 Share Posted October 28, 2012 Snow accumulation projection through 72 hours… 18Z RPM Looks similar to the Euro and hi-res NAM Link to comment Share on other sites More sharing options...
BlizzardWx Posted October 28, 2012 Share Posted October 28, 2012 Looks similar to the Euro and hi-res NAM That is a lot of snow. I see the local NWS is saying 1-2 feet so I am guessing this is somewhat overdone. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted October 29, 2012 Share Posted October 29, 2012 02z RUC has Sandy deepening rapidly tomorrow morning as it starts to track to the Northwest. Link to comment Share on other sites More sharing options...
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