SnowLover22 Posted October 6, 2017 Share Posted October 6, 2017 1 hour ago, Windspeed said: 18z HWRF reaches 961mb Cat 3 in north-central Gulf before weakening to 973 Cat 2 at landfall at 10 PM EDT/9 PM CDT Saturday night. That is a fast moving hurricane. We're literally around 50 hours out based on modeling. Edit: To put that in perspective, if the 18z HWRF is correct, Nate tracks 1,100 miles / 1,770 km in 50 hours at a mean of 22 MPH. But slower initially in gaining N to NW motion tonight, therefore, landfall speed would probably be somewhere around 25 MPH. Correct me if I am wrong but you add forward motion to maximum sustained winds. Meaning if nate max winds are 90 mph but moving 25 mph people could experience 115mph sustained. Link to comment Share on other sites More sharing options...
Windspeed Posted October 6, 2017 Share Posted October 6, 2017 Correct me if I am wrong but you add forward motion to maximum sustained winds. Meaning if nate max winds are 90 mph but moving 25 mph people could experience 115mph sustained.That might be okay for satellite estimates but recon just reports what is observed per quadrant. If storm motion contributes to stronger winds in a quadrant, it's already included in the wind obs. Link to comment Share on other sites More sharing options...
ncforecaster89 Posted October 6, 2017 Share Posted October 6, 2017 3 minutes ago, Philadelphia Snow said: Correct me if I am wrong but you add forward motion to maximum sustained winds. Meaning if nate max winds are 90 mph but moving 25 mph people could experience 115mph sustained. That's not how the translational speed affects the maximum sustained winds (MSW) in the NE quadrant of the storm. In your theoretical scenario, the 90 mph MSW is the maximum 1 minute average wind anywhere in the hurricane. The translational speed is the main reason the MSW is typically found in the aforementioned right-front quadrant. That said, a fast-moving hurricane will generally have a reduced MSW in the NW quad, as a result of the translational speed working against the winds moving in an opposing direction. Link to comment Share on other sites More sharing options...
raindancewx Posted October 6, 2017 Share Posted October 6, 2017 Louisiana was hit by Tropical Storm 11 in October 1932. Amazingly similar season to that year continues, with Harvey (Freeport), Irma (FL/AL hurricane), Maria (San Ciprian). https://en.wikipedia.org/wiki/1932_Atlantic_hurricane_season#/media/File:1932_Atlantic_tropical_storm_11_track.png Link to comment Share on other sites More sharing options...
Hoosier Posted October 6, 2017 Share Posted October 6, 2017 Hurricane, tropical storm, and storm surge watches issued for parts of the Gulf coast. Link to comment Share on other sites More sharing options...
NavarreDon Posted October 6, 2017 Author Share Posted October 6, 2017 2 minutes ago, Hoosier said: Hurricane, tropical storm, and storm surge watches issued for parts of the Gulf coast. WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Storm Surge Watch has been issued from Morgan City, Louisiana, eastward to the Alabama/Florida border, including the northern and western shores of Lake Pontchartrain. A Hurricane Watch has been issued from Morgan City, Louisiana, eastward to the Mississippi/Alabama border, including metropolitan New Orleans, Lake Pontchartrain, and Lake Maurepas. A Tropical Storm Watch has been issued from the Mississippi/Alabama border eastward to the Okaloosa/Walton County Line in Florida. A Tropical Storm Watch has also been issued west of Morgan City to Intracoastal City, Louisiana. Link to comment Share on other sites More sharing options...
Hoosier Posted October 6, 2017 Share Posted October 6, 2017 The 3km NAM goes nuts with deepening as this system gets into the Gulf. How reliable is that model for intensity? Link to comment Share on other sites More sharing options...
hlcater Posted October 6, 2017 Share Posted October 6, 2017 1 minute ago, Hoosier said: The 3km NAM goes nuts with deepening as this system gets into the Gulf. How reliable is that model for intensity? It's not. It had Harvey sub 900 back in august. Did pretty poorly with Irma as well, but not as poorly as Harvey. Link to comment Share on other sites More sharing options...
Windspeed Posted October 6, 2017 Share Posted October 6, 2017 Levi Cowan made an interesting point tonight about why Nate may struggle inbedded within such a fast steering flow as it races north across the GOM. The western side of the circulation will be significantly impeded against by strong southerly flow and will therefore be weaker. The northerly feeders and the western semicircle of the eyewall will not be able to obtain evaporation and heat flux from the sea surface as efficiently as a slower moving system. The core will get less 360° radial convergence at the surface. I could entertain this notion more if the circulation wasn't already closed or very broad, but I don't know how much of a negative factor is imposed upon an organized vortex when enhanced convergence on one side of the circulation would probably be sufficient enough to sustain the overall core convection. Perhaps the core doesn't receive perfect radial convergence and perfect flux to sustain maximum potential intensity required for a high end Category 5, but Nate was never going to be that with so little time to organize. The enhanced right semicircle should be adequate for a Cat 3 or 4. Hurricane Charley was imbedded in 18-20 kt steering flow when it underwent a 30 mb pressure drop. Granted, it was already a well-established hurricane. But it was still a tiny vortex. I'm just not so sure a fast steering flow is that much of an issue with a closed system. Perhaps a strong increase in speed can induce weakening on a very large-sized hurricane? Anyway, this may have jumped a tad off topic, but it was a point made by a respected (by myself and many others) individual about Nate's future intensity. I'm sure I'm not the only person on here that watches his excellent videos and heard his reasoning. And I felt the need to offer a counter point. Link to comment Share on other sites More sharing options...
Hoosier Posted October 6, 2017 Share Posted October 6, 2017 8 minutes ago, NWLinnCountyIA said: It's not. It had Harvey sub 900 back in august. Did pretty poorly with Irma as well, but not as poorly as Harvey. Thanks That was a very ominous run (would be a formidable hurricane even tacking on 30-40 mb), so was just curious. Link to comment Share on other sites More sharing options...
SeanBarg Posted October 6, 2017 Share Posted October 6, 2017 It looks like most of the G-IV and certainly the P3 recon data will be incorporated into the upcoming GFS run and all that data should be in the 00z Euro. So hopefully after all this recon we will have a more definite handle on the direction Nate will head. I still think the models and the NHS are underestimating the power of RI in the gulf (I suppose NHS can only hint at best at this point). Harvey went from open wave to Cat4 in about 48 hours in a similar position. If Nate manages to emerge from the Yucatan tip in tropical storm status he will already have jump start on a Harvey scenario. Nate will have less time due to forward speed, of course, but can't really count out a high impact event just yet. Just watching the Harvey RI IR loop is an amazing display of the power of the gulf and I'm not gonna count Nate out yet. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted October 6, 2017 Share Posted October 6, 2017 And.... the GFS goes back to weak slop, with no further organization. Link to comment Share on other sites More sharing options...
Windspeed Posted October 6, 2017 Share Posted October 6, 2017 And.... the GFS goes back to weak slop, with no further organization.If you look at the 850 and 700 mb layer, you can see why the GFS creates a gyre in the Gulf. It forms a second vortex in the Yucatan Channel, north of Nate's center. But it does not become a primary feature and a fujiwara slopgyre ensues. Link to comment Share on other sites More sharing options...
the ghost of leroy Posted October 6, 2017 Share Posted October 6, 2017 dmax time Link to comment Share on other sites More sharing options...
jbenedet Posted October 6, 2017 Share Posted October 6, 2017 After emerging off the Honduran coast about 6 hours ago, Nate already looks like he's quickly getting his act together. Latest advisory as of 4am has him at 999 mb, 45 mph, but I'd be surprised if we didn't see him dropped at least another few millibars by the 8am advisory based on improvement of satellite presentation. Link to comment Share on other sites More sharing options...
Amped Posted October 6, 2017 Share Posted October 6, 2017 Recon finds center a bit east of the track forecast. Link to comment Share on other sites More sharing options...
NavarreDon Posted October 6, 2017 Author Share Posted October 6, 2017 54 minutes ago, jbenedet said: After emerging off the Honduran coast about 6 hours ago, Nate already looks like he's quickly getting his act together. Latest advisory as of 4am has him at 999 mb, 45 mph, but I'd be surprised if we didn't see him dropped at least another few millibars by the 8am advisory based on improvement of satellite presentation. Nice call, 996 as of the 7:00am CDT advis. Link to comment Share on other sites More sharing options...
dan11295 Posted October 6, 2017 Share Posted October 6, 2017 East of current track would lessen interaction with the Yucatan, obviously. Would also put the track over the higher heat content in the Central GOM longer. Link to comment Share on other sites More sharing options...
NavarreDon Posted October 6, 2017 Author Share Posted October 6, 2017 Wasn't up for the overnight model runs but the 6Z GFS seems to have ticked east a bit. Link to comment Share on other sites More sharing options...
jbenedet Posted October 6, 2017 Share Posted October 6, 2017 57 minutes ago, NavarreDon said: Nice call, 996 as of the 7:00am CDT advis. I'm expecting 12z suite to be playing catch up with intensity guidance...Could be surprisingly stronger with Nate, from initialization to LF.... 6z Hwrf, for example is only 1000 mb for this hr and clearly a very disorganized system with more resemblance to a TD... Link to comment Share on other sites More sharing options...
NavarreDon Posted October 6, 2017 Author Share Posted October 6, 2017 This is interesting for me from my location standpoint. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted October 6, 2017 Share Posted October 6, 2017 20 minutes ago, jbenedet said: I'm expecting 12z suite to be playing catch up with intensity guidance...Could be surprisingly stronger with Nate, from initialization to LF.... 6z Hwrf, for example is only 1000 mb for this hr and clearly a very disorganized system with more resemblance to a TD... Agree....I also suspect we see a trend back east. Just a hunch. I still like a cat 2-3 LF into the panhandle. Link to comment Share on other sites More sharing options...
hlcater Posted October 6, 2017 Share Posted October 6, 2017 33 minutes ago, 40/70 Benchmark said: Agree....I also suspect we see a trend back east. Just a hunch. I still like a cat 2-3 LF into the panhandle. IF it can consolidate an organized core, if it can't it may never will because if the SEly wind acceleration progged verified, it would lopside the system. However if the system is well organized at this juncture, it seems like this affect may be somewhat alleviated. Haven't looked into this much, but this has to be one of the primary reasons the GFS and euro aren't deepening the system much. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted October 6, 2017 Share Posted October 6, 2017 6 minutes ago, NWLinnCountyIA said: IF it can consolidate an organized core, if it can't it may never will because if the SEly wind acceleration progged verified would lopsided the system, however if the system is well organized at this juncture, it seems like this affect may be somewhat alleviated. Haven't looked into this much, but this has to be one of the primary reasons the GFS and euro aren't deepening the system much. Yes, and that is an entirely plausible outcome....but late in the season, once you have a feel for seasonal tendencies, I like to incorporate them all else being equal. I do the same thing in winter, however this obviously does not always work. Hedging towards more strength may end up wrong- We will see...but I also believe the fact that it was already organizing prior to completely re emerging off of Honduras bodes well for it in the future. Link to comment Share on other sites More sharing options...
jbenedet Posted October 6, 2017 Share Posted October 6, 2017 34 minutes ago, 40/70 Benchmark said: Agree....I also suspect we see a trend back east. Just a hunch. I still like a cat 2-3 LF into the panhandle. Not sure he makes that far east. The mechanism to push him east has been weakening over time. The trough that guidance had picking him up has trended very progressive and may miss him altogether. Latest guidance seems to indicate that a second, deeper trough moving through the Rockies around hr 48 is what causes him to recurve east but by that time he's already at/near landfall. I'm more in line with 12z hurricane model consensus, with a landfall around Mobile AL. I think the recent trend east has been almost entirely due to the relocation of the the LLC, and that's being picked up at 12z.. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted October 6, 2017 Share Posted October 6, 2017 Just now, jbenedet said: Not sure he makes that far east. The mechanism to push him east has been weakening over time. The trough that guidance had picking him up has trended very progressive and may miss him altogether. Latest guidance seems to indicate that a second, deeper trough moving through the Rockies around hr 48 is what causes him to recurve east but by that time he's already at/near landfall. I'm more in line with 12z hurricane model consensus, with a landfall around Mobile AL. I think the trend east has been almost entirely due to the relocation of the the LLC, and that's being picked up at 12z.. It absolutely has. You are right that the faster trend with Nate may bring it inland to the west of the panhandle before the next trough interacts with it, and that is a small adjustment that I may have to make. However for the sake of continuity and given the fact that an inordinately large percentage of the most dangerous conditions are likely to occur to the east of the point of landfall, I'll stand pat for now in order emphasize the eastern envelop of impacts. Link to comment Share on other sites More sharing options...
Windspeed Posted October 6, 2017 Share Posted October 6, 2017 Nate clearly has a well-defined LLC on visible. Deep convection is good on the south and west side but somewhat ho-hum in coverage over top of the center, especially the eastern semicircle. There may me a temporary region of stable airmass on the eastern side of the circulation due to intense convection associated with strong mid level flow further east. At any rate, a core is still in its infancy stage and it shouldn't look like a hurricane. It does need to start ramping up / wrapping up a more intense convective band so an eyewall feature can have an opportunity to organize. Otherwise, the vortex won't tighten, gradient strengthen, and any intensification remains a slow go. We're only 40 hours from landfall. But the center is currently over the best heat potential the Atlantic has to offer right now so structure can change in a matter of a few hours. Link to comment Share on other sites More sharing options...
bluewave Posted October 6, 2017 Share Posted October 6, 2017 Nice graphic. #Nate is acting more like a mesovortex part of the larger overall #CAG. TS force winds on E side partially driven by larger circulation.pic.twitter.com/AQgb3cYcgy Link to comment Share on other sites More sharing options...
hawkeye_wx Posted October 6, 2017 Share Posted October 6, 2017 13 minutes ago, Windspeed said: There may me a temporary region of stable airmass on the eastern side of the circulation due to intense convection associated with strong mid level flow further east. I was just wondering about this. Satellite shows cirrus outflow from the east convection drifting westward into Nate, perhaps sinking and helping to prevent the firing of core convection. Link to comment Share on other sites More sharing options...
NavarreDon Posted October 6, 2017 Author Share Posted October 6, 2017 ...NATE STRENGTHENING OVER THE NORTHWESTERN CARIBBEAN SEA... ...HURRICANE AND STORM SURGE WARNINGS ISSUED FOR THE NORTHERN GULF COAST... SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...18.7N 85.0W ABOUT 175 MI...280 KM SE OF COZUMEL MEXICO ABOUT 165 MI...260 KM NNE OF ISLA GUANAJA HONDURAS MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...NNW OR 340 DEGREES AT 21 MPH...33 KM/H MINIMUM CENTRAL PRESSURE...996 MB...29.42 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Hurricane Warning is now in effect from Grand Isle Louisiana to the Alabama/Florida border. A Storm Surge Warning is now in effect from Morgan City Louisiana to the Alabama/Florida border, and for the northern and western shores of Lake Pontchartrain. A Tropical Storm Warning is now in effect for metropolitan New Orleans, Lake Pontchartrain and Lake Maurepas, and from west of Grand Isle to Morgan City Louisiana. A Hurricane Watch is now in effect east of the Alabama/Florida border to the Okaloosa/Walton County Line. A Storm Surge Watch is now in effect east of the Alabama/Florida border to Indian Pass, Florida. A Tropical Storm Watch is now in effect east of the Okaloosa/Walton County Line to Indian Pass, Florida. Link to comment Share on other sites More sharing options...
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