Ed Lizard Posted August 22, 2011 Author Share Posted August 22, 2011 The main thing I draw from close matches of the simple BAM models is that GFS forecast shear is pretty light along the forecast track. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted August 22, 2011 Share Posted August 22, 2011 The gfdl hurricane model is a limited area model with a 1/12 degree fine mesh, but it is certainly not a version of the gfs. The only real connection it has to the gfs is through boundary conditions. I'm on my phone, so not going to go into details....but a simple Google search will get you to their website for more (accurate) information. It is not a version of the GFS currently but it's original inception most certainly was speciated off that in th early days - perhaps the boundary layer stuff you mentioned is vestigial. Link to comment Share on other sites More sharing options...
Ed Lizard Posted August 22, 2011 Author Share Posted August 22, 2011 It is not a version of the GFS currently but it's original inception most certainly was speciated off that in th early days - perhaps the boundary layer stuff you mentioned is vestigial. I'm confused. The GFDL is a nested gridpoint model, not a spectral model, no? Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 The main thing I draw from close matches of the simple BAM models is that GFS forecast shear is pretty light along the forecast track. Exactly. This is the correct interpretation of the BAM suite lining up. Link to comment Share on other sites More sharing options...
janetjanet998 Posted August 22, 2011 Share Posted August 22, 2011 986 mb last pass 73 kts flight level Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 I'm confused. The GFDL is a nested gridpoint model, not a spectral model, no? Yes. The initial conditions are supplied by the GFS, but the GFDL has its own set of model physics. Link to comment Share on other sites More sharing options...
k*** Posted August 22, 2011 Share Posted August 22, 2011 It is not a version of the GFS currently but it's original inception most certainly was speciated off that in th early days - perhaps the boundary layer stuff you mentioned is vestigial. I think he knows more about models than you. Link to comment Share on other sites More sharing options...
Riptide Posted August 22, 2011 Share Posted August 22, 2011 When could one expect eye-wall formation? The core looks pretty well established. Link to comment Share on other sites More sharing options...
dan88 Posted August 22, 2011 Share Posted August 22, 2011 Center right at 19.0N with this pass. Roughly 1 more degree of latitude needed Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 When could one expect eye-wall formation? The core looks pretty well established. Eyewall formation is already well underway. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted August 22, 2011 Share Posted August 22, 2011 Center right at 19.0N with this pass. Roughly 1 more degree of latitude needed Irene is right of the NHC track. Was not supposed to reach 19N until 68.2W. Unless it deviates back to the left quite a bit, the center would miss Hispaniola. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted August 22, 2011 Share Posted August 22, 2011 Agreed. Given the orientation of the Atlantic ridge, and where the hurricane is now, it is very difficult to see how things could evolve to where this will not be a threat to the CONUS at some point. In fact, given how far north the westerlies are forecast to be displaced, I would not be surprised to still see a trend toward a a slower solution with the system not fully getting moved off to the north, depending on how the initial trough lifts out and the ridging builds in behind it. I think given the 500mb pattern I agree that the models just seem too far east with this overall. Its not totally unusual with tropicals to see a model consensus jog one way for a 1-2 day period and then go back, sort of like we see with winter storms, although with tropicals the waffling often occurs much closer to the short range. I always try and look at the 500mb setup and ask myself where I think the model tracks would generally be without seeing them, and in this case I'd be surprised when someone showed me where most of them currently were. Link to comment Share on other sites More sharing options...
dan88 Posted August 22, 2011 Share Posted August 22, 2011 000 URNT12 KNHC 221404 VORTEX DATA MESSAGE AL092011 A. 22/13:42:40Z B. 18 deg 59 min N 067 deg 20 min W C. 700 mb 2991 m D. 47 kt E. 237 deg 11 nm F. 326 deg 46 kt G. 237 deg 11 nm H. 989 mb I. 9 C / 3050 m J. 14 C / 3053 m K. 9 C / NA L. OPEN S M. C26 N. 12345 / 7 O. 0.02 / 1 nm P. AF302 0409A IRENE OB 07 MAX OUTBOUND AND MAX FL WIND 73 KT NE QUAD 13:48:30Z Also, recon did a drop in the NE quad. 69kt at the surface (996mb), 88kt at 982mb, max 92kt at 947mb Link to comment Share on other sites More sharing options...
DaculaWeather Posted August 22, 2011 Share Posted August 22, 2011 I'm seeing +120/-120 kts on the GRLevel3 BV .5 velocity product and +65/-105 kts on the BV 2.5 Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 I'm seeing +120/-120 kts on the GRLevel3 BV .5 velocity product and +65/-105 kts on the BV 2.5 At which level? Without knowing the elevation, this information is useless. Link to comment Share on other sites More sharing options...
phil882 Posted August 22, 2011 Share Posted August 22, 2011 I honestly can't believe the 24hr and 48hr model errors over the last two days. I didn't even think Puerto Rico was in the game on Friday. Yea the errors have been ridiculous, but its seems mainly driven by both the fact that there was a major center relocation, and also the storm is much stronger than any model had it by this point today. Since there is a significant weakness developing north of the system, its not surprising given the vertical depth of the storm right now, that its taken a much more poleward route than the modeling just 48 hours ago. Link to comment Share on other sites More sharing options...
RaleighWx Posted August 22, 2011 Share Posted August 22, 2011 Eyewall formation is already well underway. Nice. WOuldnt be suprised to see the southern part of the eyewall open till it passes Hispaniola. Link to comment Share on other sites More sharing options...
DaculaWeather Posted August 22, 2011 Share Posted August 22, 2011 Buoy just northwest of San Juan shows 69 mph winds and 7.5 meter waves every 5 seconds. THAT'S some rough water. EDIT: That's a ship that's in the wrong place at the wrong time. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted August 22, 2011 Share Posted August 22, 2011 Is the dry air thinning out on the northwestern side of the system? Just as an fyi - dry air alone is "somewhat" overrated... When we see a "ring" (of sorts) surrounding a TC that is clear and looks very dry in WV imagery, much of that is actually produced by the subsidence of the TC its self. Annualarity of dry air tends to mote TC systems as this subsidence by physical properties dries out the column(s). What we really don't want - well, speaking from the point of view of a hurricane enthusiast that is irresponsible to the welfairs of anyone in the hurricane's path ... - is to have SAL contaminant dust mass involved in said dry air. There are satellite derived products out on the web that identify Saharan Air Layer dust particulate concentrations. I just checked a couple of those channels and indeed there is some SAL related toxin in the area: http://tropic.ssec.w...od=splitEW= The reason the dust is bad - it is theorized - is because it provides an over abundance of condensation nuclei, and this super-proficiency robs the moisture too early in cloud production. I am sure there are papers out there that discuss this if interested. Having said that, I don't know if there is any critical density defined by science; it is possible that the quantities in the vicinity of Irene are lower than any said number - but that is speculation. Link to comment Share on other sites More sharing options...
PSUBlizzicane2007 Posted August 22, 2011 Share Posted August 22, 2011 I think we can all agree that the upper-air data from the G-IV and extra requested soundings will help a lot with the models' forecasting of the Bermuda High and approaching trough. We are all aware of the fact that the models... specifically the GFS... have had an issue with underforecasting the ridge (proven the other day by the 30 dm difference at Hamilton)... and this should be kept in mind when looking at these longer-term solutions. On the flip side, it is important for members unfamiliar with models and recent history to note that the current right-of-forecasted track of Irene has a lot more to do with the original reformations of the center northward, land interaction with Puerto Rico (and soon, Hispaniola), and internal physics. That said, I'm now leaning towards a conservative solution along the lower SC coast, possibly GA (as I'm not ready to buy these further east solutions for the various reasons already mentioned)... and the future path of Irene could easily be over the warmest parts of the Gulf Stream. This, combined with extremely favorable upper level conditions, will likely see the first major landfalling hurricane in the US since 2005. Link to comment Share on other sites More sharing options...
phil882 Posted August 22, 2011 Share Posted August 22, 2011 Nice. WOuldnt be suprised to see the southern part of the eyewall open till it passes Hispaniola. Given the current storm direction given by the last two recon observations, the storm is sill going to skirt the northern coast of Hispaniola. Given the high terrain on the southern side of the large island, we still could see significant weakening from Irene in the next 24 hours as it traverses the island and has its inflow cutoff. Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 Just as an fyi - dry air alone is "somewhat" overrated... When we see a "ring" (of sorts) surrounding a TC that is clear and looks very dry in WV imagery, much of that is actually produced by the subsidence of the TC its self. Annualarity of dry air tends to mote TC systems as this subsidence by physical properties dries out the column(s). What we really don't want - well, speaking from the point of view of a hurricane enthusiast that is irresponsible to the welfairs of anyone in the hurricane's path ... - is to have SAL contaminant dust mass involved in said dry air. There are satellite derived products out on the web that identify Saharan Air Layer dust particulate concentrations. I just checked a couple of those channels and indeed there is some SAL related toxin in the area: http://tropic.ssec.w...od=splitEW= The reason the dust is bad - it is theorized - is because it provides an over abundance of condensation nuclei, and this super-proficiency robs the moisture too early in cloud production. I am sure there are papers out there that discuss this if interested. Having said that, I don't know if there is any critical density defined by science; it is possible that the quantities in the vicinity of Irene are lower than any said number - but that is speculation. CUMet has posted papers recently showing the impact of Saharan dust to be unknown. Dry air entrainment is bad because it makes the atmosphere more stable. To answer the question you replied to, the atmosphere is moistening ahead of the system, but there are no microtrends noticeable in the TPW data. http://tropic.ssec.wisc.edu/real-time/mimic-tpw/natl/main.html Link to comment Share on other sites More sharing options...
OKpowdah Posted August 22, 2011 Share Posted August 22, 2011 Also dry air entrainment generally requires some level of shear, so the presence of a dry environment alone isn't everything Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 Also dry air entrainment generally requires some level of shear, so the presence of a dry environment alone isn't everything Yes, agreed. Sorry, I should have been more clear. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted August 22, 2011 Share Posted August 22, 2011 CUMet has posted papers recently showing the impact of Saharan dust to be unknown. Dry air entrainment is bad because it makes the atmosphere more stable. To answer the question you replied to, the atmosphere is moistening ahead of the system, but there are no microtrends noticeable in the TPW data. http://tropic.ssec.w.../natl/main.html I'm not saying dry air isn't bad - I'm saying that just because we see a ring of dry air around a TC does not mean it is inhibiting developement. Just need to be cognizant of the dry air source. For those unaware...the core of a TC is a SEA-AIR virtual coupled model, with subsidence surrounding the system; that is the primary source for the 'heat engine' - as it's called. If a TC bodily moves into the dry air, sure, that becomes a mass imbalance and that is when inhibition takes place. I do think, though, that there is some imbalance in the area. Lastly, I haven't seen that paper - I'll take a look.. But I'd be pretty impressed with how the authors got around clear and patently observed detrimental effects amid reels upon reels of satellite history. Link to comment Share on other sites More sharing options...
am19psu Posted August 22, 2011 Share Posted August 22, 2011 I'm not saying dry air isn't bad - I'm saying that just because we see a ring of dry air around a TC does not mean it is inhibiting developement. Just need to be cognizant of the dry air source. For those unaware...the core of a TC is a SEA-AIR virtual coupled model, with subsidence surrounding the system; that is the primary source for the 'heat engine' - as it's called. If a TC bodily moves into the dry air, sure, that becomes a mass imbalance and that is when inhibition takes place. I do think, though, that there is some imbalance in the area. What relevance is this to Irene? We're discussing the environmental dry air ahead of the system that can be clearly seen propagating ahead of Irene in the TPW loop I posted. There is little shear around right now, which is why it hasn't negatively impacted the storm today. Link to comment Share on other sites More sharing options...
dan88 Posted August 22, 2011 Share Posted August 22, 2011 HURRICANE CENTER LOCATED NEAR 19.2N 67.5W AT 22/1500Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 11 KT ESTIMATED MINIMUM CENTRAL PRESSURE 988 MB MAX SUSTAINED WINDS 70 KT WITH GUSTS TO 85 KT. 100kt now forecasted Link to comment Share on other sites More sharing options...
Juliancolton Posted August 22, 2011 Share Posted August 22, 2011 85/988 this advisory, 300 degrees at 11 kts Link to comment Share on other sites More sharing options...
Typhoon Tip Posted August 22, 2011 Share Posted August 22, 2011 I think we can all agree that the upper-air data from the G-IV and extra requested soundings will help a lot with the models' forecasting of the Bermuda High and approaching trough. We are all aware of the fact that the models... specifically the GFS... have had an issue with underforecasting the ridge (proven the other day by the 30 dm difference at Hamilton)... and this should be kept in mind when looking at these longer-term solutions. On the flip side, it is important for members unfamiliar with models and recent history to note that the current right-of-forecasted track of Irene has a lot more to do with the original reformations of the center northward, land interaction with Puerto Rico (and soon, Hispaniola), and internal physics. That said, I'm now leaning towards a conservative solution along the lower SC coast, possibly GA (as I'm not ready to buy these further east solutions for the various reasons already mentioned)... and the future path of Irene could easily be over the warmest parts of the Gulf Stream. This, combined with extremely favorable upper level conditions, will likely see the first major landfalling hurricane in the US since 2005. Absolutely! We were talking about this last evening that we were surprised there wasn't already sounding missions taking place. By the way, from what I'm looking at here there is some possiblity that more of an indirect impact could be registered along the SE/MA coasts, and that persons in New England ...eh, may want to at least be cognizant of this thing. Link to comment Share on other sites More sharing options...
free_man Posted August 22, 2011 Share Posted August 22, 2011 http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_500_084l.gif Andrew bend FTL? Link to comment Share on other sites More sharing options...
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