AutoPenalti Posted September 8, 2013 Share Posted September 8, 2013 This season has been nothing but fail at failing. Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 8, 2013 Share Posted September 8, 2013 What is the deal with this 98L? Wish it was something cause a lot of the paths would be putting it in good position. Link to comment Share on other sites More sharing options...
Sunny and Warm Posted September 8, 2013 Share Posted September 8, 2013 The early guidance continues to back off somewhat on the timing and intensity of 91L. 3rd straight run of lower expectations further out into time. Link to comment Share on other sites More sharing options...
Natester Posted September 8, 2013 Share Posted September 8, 2013 This season has been nothing but fail at failing. Indeed. This season has been downright strange. Link to comment Share on other sites More sharing options...
phlwx Posted September 8, 2013 Share Posted September 8, 2013 This season has been nothing but fail at failing. Wouldn't it be "winning" at failing given how much fail there's been? Link to comment Share on other sites More sharing options...
Eyewall2005 Posted September 8, 2013 Share Posted September 8, 2013 Link to comment Share on other sites More sharing options...
WxFreak11 Posted September 8, 2013 Share Posted September 8, 2013 What is the deal with this 98L? Wish it was something cause a lot of the paths would be putting it in good position. Quite a few of the models do put 98L in a good position but I think condtions aren't that favorable right now. Nobody is talking about this storm because again..we've all been burned one too many times this season. This season is just one big cluster! Link to comment Share on other sites More sharing options...
wxtrackercody Posted September 8, 2013 Share Posted September 8, 2013 Maybe someone here knows since I've asked around and nobody else seems to... All I keep hearing is that the LGEM and SHIPS should be used only after a tropical cyclone develops because they're run as if one already exists...but what are the specifics behind that? Are they initialized with a false circulation or something along those lines? Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 8, 2013 Share Posted September 8, 2013 Looks like we may have a TD here soon. Going to be a race vs. the record clock for a hurricane. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 Maybe someone here knows since I've asked around and nobody else seems to... All I keep hearing is that the LGEM and SHIPS should be used only after a tropical cyclone develops because they're run as if one already exists...but what are the specifics behind that? Are they initialized with a false circulation or something along those lines? Simpler than that, really. From the NHC page... I know the difference between statistical, statistical-dynamic and dynamic models, but not so well I can explain them really well. But SHIPS is fairly simple compared to the dynamic models. SHIPS does not model the actual storm, whether it is a real storm or depression, its predictions are based on several factors that favor or not favor the storm reaching its MPI, it doesn't model an actual storm. Statistical Hurricane Intensity Prediction Scheme (SHIPS) The SHIPS model is a statistical-dynamical intensity model based on statistical relationships between storm behavior and environmental conditions estimated from dynamical model forecasts as well as on climatology and persistence predictors. Due to the use of the dynamical predictors, the average intensity errors from SHIPS are typically 10%-15% less than those from SHIFOR5. SHIPS has historically outperformed most of the dynamical models, including the GFDL, and SHIPS has traditionally been one of the most skillful sources of intensity guidance for NHC. SHIPS is based on standard multiple regression techniques. The predictors for SHIPS include climatology and persistence, atmospheric environmental parameters (e.g., vertical wind shear, stability, etc.), and oceanic input such as sea surface temperature (SST) and upper-oceanic heat content. Many of the predictors are obtained from the GFS and are averaged over the entire forecast period. The developmental data from which the regression equations are derived include open ocean TCs from 1982 through the present. Each year the regression equations are re-derived based upon the inclusion of the previous year.s data. Therefore, the weighting of the predictors can change from year to year. The predictors currently found to be most statistically significant are: the difference between the current intensity and the estimated maximum potential intensity (MPI), vertical wind shear, persistence, and the upper-tropospheric temperature. SHIPS also includes predictors from satellite data such as the strength and symmetry of convection as measured from infrared satellite imagery and the heat content of the upper ocean determined from satellite altimetry observations. DeMaria M., and J. Kaplan, 1994: Sea surface temperature and the maximum intensity of Atlantic tropical cyclones. J. Climate, 7, 1324.1334. DeMaria, M., M. Mainelli, L.K. Shay, J.A. Knaff, and J. Kaplan, 2005: Further Improvements to the Statistical Hurricane Intensity Prediction Scheme (SHIPS). Wea. Forecasting, 20, 531.543. Link to comment Share on other sites More sharing options...
MJO812 Posted September 8, 2013 Share Posted September 8, 2013 It looks like we will have a TD soon http://www.nhc.noaa.gov/gtwo_atl.shtml 1. SHOWERS AND THUNDERSTORMS ARE GRADUALLY BECOMING BETTER ORGANIZED NEAR A LOW PRESSURE SYSTEM CENTERED ABOUT 325 MILES EAST-SOUTHEAST OF THE SOUTHERN CAPE VERDE ISLANDS. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR FURTHER DEVELOPMENT...AND A TROPICAL DEPRESSION COULD FORM DURING THE NEXT DAY OR SO WHILE THE DISTURBANCE MOVES WEST-NORTHWESTWARD AT ABOUT 10 MPH TOWARD THE CAPE VERDE ISLANDS. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT... OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH CHANCE...90 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. INTERESTS IN THE CAPE VERDE ISLANDS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM...AND TROPICAL STORM WATCHES OR WARNINGS COULD BE REQUIRED IF A DEPRESSION FORMS. REGARDLESS OF TROPICAL CYCLONE FORMATION...HEAVY RAINFALL AND GUSTY WINDS ARE POSSIBLE IN THE CAPE VERDE ISLANDS BY LATER TODAY. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 The GFS per NHC just relocates the vortex to best track, it doesn't create a fake (bogus) one. Note also why 98L may not be in a hurry to develop. The GFS makes a special accommodation for TCs in its initial fields by relocating the globally analyzed TC vortex in the first-guess field to the official NHC position. An assimilation of the available data is then performed to create the initial state. The globally analyzed vortex is, however, often an incomplete representation of the true TC structure. For this reason, the GFS is typically more suited to producing track and outer wind structure forecasts than to producing intensity forecasts. http://www.nhc.noaa.gov/modelsummary.shtml Beta and Advection Model (BAM) The Beta and Advection Model (BAM) refers to a class of simple trajectory models that utilize vertically averaged horizontal winds from the GFS to compute TC trajectories. These trajectories include a correction term to account for the impact of the earth.s rotation. The BAM is based upon the concept of a simple relationship between storm intensity/depth and steering levels. Strong cyclones typically extend through the entire depth of the troposphere and are steered by deeper layer-average winds, while weaker cyclones are steered by shallower layer-average winds. The BAM is run in three versions corresponding to the different depths used in the trajectory calculation: BAM shallow (850-700 mb), BAM medium (850-400 mb), and BAM deep (850-200 mb), known as BAMS, BAMM and BAMD, respectively. The performance of the BAM is strongly dependent on the dynamical input from the GFS. A divergence of the three versions of the BAM indicates varying steering flow within the parent GFS model. Hence, spread among the three versions of the BAM also serves as a rough estimate of the vertical shear as well as the complexity and uncertainty in the track forecast. Link to comment Share on other sites More sharing options...
Derecho! Posted September 8, 2013 Share Posted September 8, 2013 Maybe someone here knows since I've asked around and nobody else seems to... All I keep hearing is that the LGEM and SHIPS should be used only after a tropical cyclone develops because they're run as if one already exists...but what are the specifics behind that? Are they initialized with a false circulation or something along those lines? They are quite simple statistical models (that still are as or more more accurate than far more complex dynamic models like the GFDL and HWRF). Actually, all intensity models used for INVESTS are pretty much garbage. The GFDL and HWRF do even worse for INVESTS. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 They are quite simple statistical models (that still are as or more more accurate than far more complex dynamic models like the GFDL and HWRF). Actually, all intensity models used for INVESTS are pretty much garbage. The GFDL and HWRF do even worse for INVESTS. My observation with GFDL and invests, whether the GFDL can track a vortex over the entire run is a useful predictor as to whether the invest will develop. Not perfect, but useful. Link to comment Share on other sites More sharing options...
AutoPenalti Posted September 8, 2013 Share Posted September 8, 2013 Wouldn't it be "winning" at failing given how much fail there's been?It's been so bad, that it should be a "failure" at failing. Link to comment Share on other sites More sharing options...
phil882 Posted September 8, 2013 Share Posted September 8, 2013 Looks like things are a go for 91L... TD likely by 5pm or 11pm tonight. Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 8, 2013 Share Posted September 8, 2013 It appears that a tropical depression is forming east of the Cape Verde islands. Three stations there are already reporting 15-19 knot NNE winds Tropical storm watches could be posted for the islands later today Link to comment Share on other sites More sharing options...
wxtrackercody Posted September 8, 2013 Share Posted September 8, 2013 The 12z GFS is the most bullish run so far regarding development in the Bay of Campeche in a few days. Genesis appears to be related to the surface trough already positioned there with maybe some added energy from the northern portion of the tropical wave axis in the Gulf of Honduras. EDIT: And thanks for the responses above guys. Link to comment Share on other sites More sharing options...
phil882 Posted September 8, 2013 Share Posted September 8, 2013 The 12z GFS is the most bullish run so far regarding development in the Bay of Campeche in a few days. Genesis appears to be related to the surface trough already positioned there with maybe some added energy from the northern portion of the tropical wave axis in the Gulf of Honduras. EDIT: And thanks for the responses above guys. Don't expect much out of the GOM system, its a very gyre like configuration where multiple meosvorticies are fighting for dominance in a much larger scale cyclonic circulation. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 Don't expect much out of the GOM system, its a very gyre like configuration where multiple meosvorticies are fighting for dominance in a much larger scale cyclonic circulation. And a lot of it is over either Central America or the Eastern Pacific per the GFS. Link to comment Share on other sites More sharing options...
phil882 Posted September 8, 2013 Share Posted September 8, 2013 And a lot of it is over either Central America or the Eastern Pacific per the GFS. Correct... which is typical for CA gyres. There are instances that CA gyres spin up into formidable TCs, but thats rare, and happens most often when the gyre circulation becomes established far enough away from CA and the vorticity can become focused in one particular region (ex. Roxanne 1995, Wilma 2005, Sandy 2012) A good analog for the best case scenario (in terms of TC intensity) for this possible gyre to TC evolution is likely what happened with Stan (2005). The storm was rapidly intensifying in the BOC before it made landfall in Mexico. http://www.atmos.albany.edu/student/ppapin/lb13_img/special/20130908/gyre_05.html Note that the gyre circulation axis (blue TC symbol) is south of TC Stan though most of its lifespan. Since Stan is embedded in a larger circulation, the general rule of thumb is that it should rotate cyclonically around this larger circulation, which is why you see Stan dive southward (which was unexpected at the time) The two graphs at the bottom are used to diagnose if you have a CA gyre. The two necessary criteria in this case are whether or not the circulation is closed (arc averaged tangential wind must exceed 1 ms^-1) and the maximum azimuthally averaged tangential wind must exceed 5 ms^-1 while also occurring greater than 500 km from the gyre center. This filters out TC like disturbances where the radius of maximum wind would likely be within 500 km. Link to comment Share on other sites More sharing options...
Srain Posted September 8, 2013 Share Posted September 8, 2013 Slop gyre ftw.... Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 91L SHIPS now using double secret probation NHC track guidance instead of BAMM, I smell an upgrade. Unofficially, of course Really close per SHIPS on making 2013 a magically unexciting season. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 91L failing at a recurve and then menacing the Canadian Maritimes beyond 10 day ala Euro would be interesting. Not for the purists, obviously... Link to comment Share on other sites More sharing options...
phil882 Posted September 8, 2013 Share Posted September 8, 2013 91L failing at a recurve and then menacing the Canadian Maritimes beyond 10 day ala Euro would be interesting. Not for the purists, obviously... 91L gets ripped apart by shear long before it has a chance to threaten any land mass in the long range. Part of reason why 91L recurves so early is due to the anomalosly deep and upper-level trough. Link to comment Share on other sites More sharing options...
wxtrackercody Posted September 8, 2013 Share Posted September 8, 2013 BEGINNHC_ATCFinvest_RENUMBER_al912013_al092013.renFSTDARU0400100000201309081925NONENOTIFY=ATRPEND Link to comment Share on other sites More sharing options...
tmagan Posted September 8, 2013 Share Posted September 8, 2013 How many Category Five hurricanes have hit Mexico, from either the Atlantic or Pacific Ocean? Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 91L gets ripped apart by shear long before it has a chance to threaten any land mass in the long range. Part of reason why 91L recurves so early is due to the anomalosly deep and upper-level trough. The Euro weakens it dramatically, but keeps a closed low the entire 10 days for 09L. Starts intensifying again at the end of the run, I assume as it begins transition to a post-tropical low. Weenie speculation, the low off New England is obviously frontal per Euro 850 mb temps, but pretty intense, and over 20 to 25C water temps, and looking like the Euro wants to cut it off and drift it Southward in the mid-levels. So far, every weenie speculation I have had about Euro Day 9 or 10 cutoff lows have resulted in fail this season. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 8, 2013 Share Posted September 8, 2013 How many Category Five hurricanes have hit Mexico, from either the Atlantic or Pacific Ocean? At least one. I know of this one only because Josh mentioned it on the Pacific thread... http://en.wikipedia.org/wiki/1959_Mexico_Hurricane Edit to add- Internet fu says 1 on the Atlantic side (Janet), or two total, by my amateur account Edit 2 Wiki, the source of all knowledge suggests Tampico 1933 could have still been a Cat 5 when it hit the Yucatan, but the tree fell in the forest, and officially is a Cat 4. Interesting, Josh territory, if US landfalls may have had a high bias in the pre-satellite/recon era, perhaps non-US landfalls with limited observations could have a low bias. http://en.wikipedia.org/wiki/List_of_Category_5_Atlantic_hurricanes I also wonder if there is a positive land bias, almost all Atlantic Cat 5s have made landfall at some strength, per the article. Link to comment Share on other sites More sharing options...
Amped Posted September 8, 2013 Share Posted September 8, 2013 GFDL shows 992mb but only 46kts at 72 hrs. This storm does have pretty good water temps a moist environment and low shear for the next 4 days. On the other hand models don't really take it below 990mb and it has a broad circulation, so it may require a lower pressure to become a hurricane. I give it about a 30% chance of becoming a hurricane withing 72 hrs and a 60% chance of becoming one at some point. If it were a normal year, I'd say CAT 2 before 12z on the 11th. Link to comment Share on other sites More sharing options...
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