B1. Geophys. Mon. Yau, M. K., , Y. Liu, , D-L. Zhang, , and Y. Chen, 2004: A multiscale numerical study of Hurricane Andrew (1992). According to the Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory, Hurricane Elena produced Category 3 winds (111 mph (179 km/h) or greater) in Florida, Alabama, and Mississippi. The plot shows that the minimum 850-hPa height was recorded during the time period centered on 1900 UTC 1 September. As a test, mean Θe profiles were computed by substituting the corrected (radiometer) temperature values of Eastin et al. Once it reached the Gulf of Mexico, it began strengthening in earnest becoming a hurricane by mid-morning of the 29th. In this section, composites of various reconnaissance flight variables over the five significant time periods described in section 3 will be shown. Figure A1 shows the average Θe calculated using only the ZML-corrected data and using the radiometer data when available for time periods I, III, and IV. Part II: Kinematics and inner-core structures. A composite analysis of the core of a mature hurricane. The largest values of Θe were also found within the eye at this time (Fig. Corbosiero, K. L., J. Molinari, A. R. Aiyyer, and M. L. Black, 2006: The Structure and Evolution of Hurricane Elena (1985). 7 shows the azimuthally averaged AQQ radar data from Fig. Hawkins and Rubsam (1968b), Hawkins and Imbembo (1976), and Marks and Houze (1987) all documented strong inflow from the surface to at least the 750-hPa level in hurricanes that were deepening or at peak intensity. Rev., 123, 3502–3517. One of the WP-3D aircraft that investigated Elena carried an X-band (3.2 cm) Doppler radar that scanned a plane perpendicular to the aircraft (Jorgensen 1984a). J. Atmos. Hurricane Elena was a category 3 major hurricane that caused heavy damage along the Gulf Coast of the United States in August and September of the 1985 Atlantic hurricane season. When the beam was pointing directly up or down (at its vertical incidence), the Doppler velocities collected were the vertical motions of precipitation relative to the moving aircraft. Elena exploded in intensity becoming a strong Category 4 on the 12. Hawkins and Imbembo (1976) and Frank (1984) found the radial gradient of Θe is maximized within the eyewall, and the increase in the gradient with intensification lends evidence to Emanuel’s (1997) argument of the eyewall as a front. The radar contains a distance-dependent range correction that is constant beyond 230 km (Parrish et al. The data are again composited with respect to the RMSC at 850 hPa, and only the radii and heights where 75% of the legs contain data are plotted. 2002), boundary layer scheme (Braun and Tao 2000), and input data quality (Davis and Bosart 2002), numerical models alone are not yet sufficient to address all of the details of intensity change. It is within this region that most of the energy generation and conversion that drives the hurricane circulation takes place (Riehl 1950; Ooyama 1969; Emanuel 1986). 2). Hanley, D. E., , J. Molinari, , and D. Keyser, 2001: A composite study of the interactions between tropical cyclones and upper-tropospheric troughs. The reconnaissance aircraft data will also be presented as averages over five significant time periods in Elena’s evolution. Mon. The box was then filled by bilinearly interpolating from the adjacent rows and columns of data. Elena, and the storm began recurvature. Fig. A composite study of the interactions between tropical cyclones and upper-tropospheric troughs. } Between 0300 and 0700 UTC 1 September, upward vertical velocities and the radial gradient of reflectivity became concentrated around the 30-km radius, leading to the formation of an eyewall (Fig. The RMSC is thus located at 22 km and the RMW is at 28 km. The gray vertical lines in Fig. J. Atmos. (2002a, b) for the ZML-corrected data when available. Slow thermally or frictionally controlled meridional circulation in a circular vortex. Late on the 1 September, around the time of peak intensity, a sharp vorticity maximum was evident just inside the RMSC (Fig. The outflow was driven by enhanced convergence in the boundary layer and a strong eyewall updraft that diverged aloft, ultimately leading to faster spindown of the vortex. Hurricane Elena made landfall near Biloxi, Mississippi, in September 1985 as a Category 3 storm. J. Atmos. An air–sea interaction theory for tropical cyclones. To have a uniform time step between radar images and to capture the mesoscale features of the reflectivity field, the scans were linearly interpolated to 5-min intervals. We also would like to thank Jim Kossin and an anonymous reviewer for helpful comments that improved the quality of the manuscript. The second method was employed by Hawkins and Imbembo (1976), Jorgensen (1984b), and Frank (1984) to construct longer-term time composites of flight-level reconnaissance data of steady Hurricane Inez (1966), weakening Hurricane Allen (1980), and rapidly intensifying Hurricane Frederic (1979). The solid black lines show the time evolution of RMW. Email: kristen@atmos.albany.edu. Stationary and moving convective bands in hurricanes. Environmental vertical wind shear was calculated from the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses between the 850- and 200-hPa levels. Changes in radial and vertical structure with intensification, Choice and Significance of Compositing Radius. (1995). Section 3 describes the two compositing methods used to display the data. (1999) has shown that such annular vorticity profiles can support barotropic instability and the growth of unstable modes that can lead to asymmetric horizontal mixing between the eye and eyewall. There is almost no change to the average Θe in time period I, due to the fact that less than half of the 28 legs that made up the average had radiometer data. Same as Fig. Molinari et al. 1985; Yau et al. Molinari, J., , and D. Vollaro, 1989: External influences on hurricane intensity. 3 and 4) under the influence of strong environmental vertical wind shear (>9 m s−1; Table 1) from the approaching upper-level trough. Line graphs illustrating the temporal changes in (a) the radius of maximum tangential wind and (b) the radius of maximum slope change, grouped according to which quadrant each radial leg passed through. Mon. Rapid pressure falls and tangential wind spinup began just before 0000 UTC 1 September as a near superposition and constructive interference occurred between the trough and the hurricane (Molinari et al. Mon. In a Category 5 hurricane, the highest category hurricane, winds are … The largest radial gradient of Θe was found within 3 km of the RMSC during all time periods, attaining maximum value during time period V. The maximum radial gradient of Θe at 850 hPa is thus nearly coincident with the maximum composite updraft in both magnitude and location. Under the influence of an approaching midlatitude trough (Case 1986), Elena moved toward the east-northeast while the intensity remained steady from 0000 to 1800 UTC 31 August. Rev., 122 , 2722–2739. The dynamics of the inner-core region of tropical cyclones (defined as the eye, eyewall, and spiral rainbands within 100 km of the center) are crucial to our understanding of hurricane intensity change. The vertical incidence data have a horizontal resolution of 0.75 km and are averaged into 0.3-km bins in the vertical. (1985), and Black et al. But Elena was even more disruptive in its changeable course. Elena was first identified on satellite imagery north of the Cape Verde Islands on the August 23rd of 1985. Mon. In addition to the atmospheric quantities collected aboard the aircraft, radial profiles of equivalent potential temperature (Θe) and the symmetric vertical component of relative vorticity (ζ) were calculated, the former using the method of Bolton (1980) and the latter from the formula ζ = Vt /r + ∂Vt /∂r, with a centered differencing scheme applied to the local tangential wind (Vt). (2002a, b) used to identify wetting errors in 31 Atlantic and east Pacific hurricanes were available on 37 of the 88 radial legs in Elena. Elena made landfall as a category 3 hurricane. After calculation, the 4-h azimuthal averages were smoothed in radius with a nine-point Bartlett filter that removed features with wavelengths less than ∼5 km (Jenkins and Watts 1968; Kossin and Eastin 2001). Rev., 130 , 825–841. With the trough axis situated over Elena’s circulation, the steering winds above the storm weakened and the center made a slow anticyclonic loop off the western coast of Florida between 1800 UTC 31 August and 1800 UTC 1 September. Norv., 31 , 1–16. 4 and 5, respectively. This relatively short averaging period led to irregular jumps in the azimuthally averaged tangential wind and relative vorticity. For azimuthal averages of the flight-level data, it was necessary to use data from multiple legs since one radial leg only provides a picture of storm structure at one azimuth. Davis, C., , and L. F. Bosart, 2002: Numerical simulations of the genesis of Hurricane Diana (1984). Frank, W. F., 1984: A composite analysis of the core of a mature hurricane. 8c). Figure B2a shows that the RMW can vary as much as 40 km between legs only 2 h apart into the same storm quadrant. Sensitivity of high-resolution simulations of Hurricane Bob (1991) to planetary boundary layer parameterizations. Sci., 42 , 839–856. The magnitude of the subsidence in the composite exceeded −0.1 m s−1 only one other time: from +6 to +10 km from the RMSC during the last time period. J. Atmos. Then its progress stopped as it made a clockwise loop just 50 miles from Cedar Key, FL. 2002a) during time period V due to the enhanced low-level eyewall updraft and reflectivity (Figs. 1996). Part II: Inner core structure of Hurricane Allen (1980). Vorticity and equivalent potential temperature at 850 hPa showed indications of prior mixing between the eye and eyewall. Eighty-eight radial legs and 47 vertical incidence scans were collected aboard NOAA WP-3D aircraft, and 1142 ground-based radar scans were made of Elena’s eyewall and inner rainbands as the storm intensified from a disorganized category 2 to an intense category 3 hurricane. Meteor. Eastin, M. D., , P. G. Black, , and W. M. Gray, 2002b: Flight-level thermodynamic instrument wetting errors in hurricanes. This increase in the radial gradient of Θe is quantified in Fig. Kossin and Eastin (2001) found maximum values of Θe in the eyewall during intensification, but a transition to the highest values in the eye after intensification had stopped, which they attributed to mixing between the eye and eyewall. Fig. (1992) and Reasor et al. 4) and the development of a vorticity maximum on the inner edge of the eyewall (Fig. Case, R. A., 1986: Atlantic hurricane season of 1985. The decision to calculate the flight-level azimuthal averages on the basis of a constant time interval instead of after each figure-4 flight pattern was based upon the desire to capture the smooth, symmetric evolution of Elena while minimizing gaps in the data. Mon. The impact of TRMM data on mesoscale numerical simulation of Supertyphoon Paka. A dramatic reversal of the flow pattern occurred during time period V in Elena with a peak in outflow noted at the RMSC, similar to both the weakening stages of Hurricanes Norbert (1984) and Olivia (1994) documented by Marks et al. 6, time averaged in 4-h bins to match the flight-level radius–time Hovmöllers shown in Figs. The dashed black line is the radius of maximum wind from Fig. Sci., 39 , 378–394. Only the area –18 to +60 km from the RMSC will be shown as these distances approximately represent the radii where data coverage was greater than 75% (i.e., greater than 75% of the legs that made up each composite sampled that radius). Azimuthally averaged ground-based radar data from Fig. (2002a, b) examined for wetting errors, as the Barnes radiometer data were available on 37 of the 88 radial legs. As Elena intensified during time periods II through IV, winds decreased in the eye (−6 to −18 km from the RMSC), while winds increased −6 to +42 km from the RMSC, with the greatest spinup located just outside the RMSC. Wea. With the general lack of observations spanning a sufficiently long period of time over which the tropical cyclone evolves, observational studies of hurricane structure have commonly gone in one of two directions: 1) case studies or “snapshots” of a hurricane’s structure spanning 1–3 h, or 2) construction of composites over longer periods, sometimes spanning a day or more. B2. We are indebted to David Vollaro for his help in developing computer programs to read and plot the best-track data, and to Matthew Eastin for providing the Elena radiometer temperature data. Sci., 53 , 1887–1909. Flight-level thermodynamic instrument wetting errors in hurricanes. Willoughby et al. Mon. Emanuel, K. A., 1986: An air–sea interaction theory for tropical cyclones. Hurricane Research Division missions into Elena measured the storm at every phase of its history, and also detailed the erratic movements of its eye. Values of Θe decreased during time periods IV and V outside the RMSC, sharply increasing the radial gradient of Θe. Aircraft reconnaissance and ground-based radar data were used to examine the evolution of the symmetric radial and vertical structure of Hurricane Elena (1985). Mon. During time period IV the largest errors were found between –6 and +3 km from the RMSC, while the maximum value of Θe remained at –15 km from the RMSC. The gray-hatched region represents a time with no 850-hPa-level flight data. During the next 12 h, heights outside the 40-km radius began to increase, while values in the core began to fall slowly. The peak composite upward vertical velocity of 1.8 m s−1 in Elena is smaller than the time-averaged vertical velocities of 2–4.5 m s−1 noted by Jorgensen (1984a, b), but on par with Black et al.’s (1996) study in which more than 70% of the vertical velocities recorded in the eyewall were between 2 and –2 m s−1, and with Eastin et al.’s (2005) finding that the average convective updraft in the eyewall was 2.2 m s−1 at 850 hPa. As deep convection became concentrated in the eyewall between 0300 and 0700 UTC 1 September, rapid spinup occurred and the radius of maximum vorticity became anchored to the inner edge of the eyewall, after which the RMW and radius of maximum vorticity remained within 15 km of each other. The data were transformed by personnel at the Hurricane Research Division (HRD) of NOAA into storm-relative coordinates through construction of the cyclone track by the method of Willoughby and Chelmow (1982) and interpolation of the data to a 0.5-km radial grid using a 2-km overlapping filter window. In Bay Saint Louis, Mississippi, winds reached 96 mph. Midday on September 2, 1985, Hurricane Elena came ashore near Biloxi, MS. J. Appl. Rev., 130 , 2448–2458. 3. Between the time periods centered on 0300 and 1100 UTC 31 August, the height of the 850-hPa surface fell by approximately 30 m everywhere inside the 150-km radius. Sci., 47 , 1902–1918. 3). Similarly, in 85% of radial legs the RMSC was within 3 km of a local relative vorticity maximum, and was located within 3 km of the absolute relative vorticity maximum 53% of the time. 2 with the use of the radiometer data was 2.3 K, located 3–6 km outward of the mean eyewall updraft position. 4). Wea. Hurricane Elena was a category 2 hurricane from Aug. 30-Sept. 1; category 3 from Sept. 1-landfall in Mississippi. Radius–height composites of vertical incidence Doppler-derived radar reflectivity (dBZ) with respect to the 850-hPa RMSC for time periods (a) II, (b) IV, and (c) V, shown in Fig. Structure and budgets of the hurricane on October 1, 1964. width: 100%; Once an inner wind maximum and eyewall developed, the radius of maximum winds contracted and a sharp localized vorticity maximum emerged, with much lower values on either side. Rapid height falls (Fig. The radius–time Hovmöller of the azimuthally averaged height of the 850-hPa surface is shown in Fig. A framework for understanding these changes in storm structure comes from the numerical simulations of Montgomery et al. Sci., 53, 1887–1909. For the Elena data, tests were performed in which the ZML-corrected temperature and dewpoint values were replaced with the Eastin et al. Average (a) tangential wind (m s−1), (b) relative vorticity (× 10−4 s−1), (c) radial wind (m s−1), (d) vertical velocity (m s−1), (e) equivalent potential temperature (K), and (f) radial gradient of equivalent potential temperature (K km−1), in each of the five time periods shown in Fig. (1999) and Kossin and Eastin (2001). Wea. Elena began as a disturbance in the deep tropical Atlantic, but hostile conditions prevented it from organizing until it had reached the Windward Passage between Hispanola and Cuba. Outside the eyewall, values of reflectivity had increased to their highest values, with maximum values of over 40 dBZ located in the bright band between 12 and 24 km from the RMSC. J. Atmos. The wind profile then increased much more slowly to the RMW at 78 km. 4 and the dashed white line is the radius of maximum vorticity from Fig. Zipser, E. J., , R. J. Meitin, , and M. A. LeMone, 1981: Mesoscale motion fields associated with a slowly moving GATE convective band. Mon. 3, except for tangential wind (m s−1) at 850 hPa. The hurricane then stalled off the west coast of Florida. B1 are the radial profiles of relative vorticity and vertical motion for radial legs 29 and 65, smoothed in radius with the Bartlett filter described in section 3. External influences on hurricane intensity. Since tropical cyclones are warm-core vortices in approximate hydrostatic and gradient wind balance, surfaces of angular momentum must slope radially outward with height (Emanuel 1986). More recently, Kossin and Eastin (2001) noted a “regime change” in equivalent potential temperature and relative vorticity in hurricanes between peak intensity and weakening. 8d and 9c). Temporal and spatial variations of rainfall near the centers of two tropical cyclones. Snapshots of hurricanes show structural detail, but not time change. It is notable that the RMSC and the RMW differed by more than 25 km at this time. It was a category 3 hurricane. Part I: General observations by research aircraft. Although the averages were calculated for each 4-h period for which the radar data were available, Fig. background: #ddd; Mon. The composite updraft grew in magnitude with time as Elena intensified, and continued to increase after peak intensity to a value of 1.8 m s−1 during time period V. Significant subsidence occurred within the eye only during time period IV. Over 95% of the scans were made at 0.4°. Ooyama, K. V., 1969: Numerical simulation of the life-cycle of tropical cyclones. The hours on the vertical axis represent the midpoints of the 4-h time periods over which the azimuthal averages were calculated. The evolution of Elena discussed above is also consistent with the trough interaction and superposition hypothesis of Molinari and Vollaro (1989, 1990) and Molinari et al. As data from only one flight level was collected in Elena, the relative roles of mixing and changes to the inversion height in the evolution of Θe remains uncertain. Although it weakened from its peak twelve hours before, Elena came ashore as a Category Three hurricane, bringing winds of 115 mph (177 km/hr) to Biloxi. Negative values will be used to indicate radii inside the RMSC, and positive values radii outside the RMSC. Numerical simulation of the life-cycle of tropical cyclones. (1981) method (hereafter referred to as the ZML correction). Objective determination of hurricane tracks from aircraft observations. Part I: Steady-state maintenance. Finally, time period V, legs 77–88, showed the storm to be weakening after a 5-h break during which there were no flights into Elena. 8d) were stronger during time period V. Contrary to this stronger low-level eyewall updraft, however, the vertical incidence profile during time period V (Fig. Wea. Early on the 2 September, after a 5-h gap with no flight-level data, the sharply peaked vorticity profile had vanished (Fig. Hawkins, H. F., , and S. M. Imbembo, 1976: The structure of a small, intense Hurricane-Inez 1966. Frantically, watches and warnings were shifted to the eastern Gulf shore. Part I: General statistics. 3) and spinup of the tangential wind 30–40 km outside the eye (Fig. Radius–time Hovmöller of azimuthally averaged reflectivity from the WSR-57 Apalachicola, FL, radar from 2205 UTC 31 Aug to 0150 UTC 2 Sep. Times with no data are indicated by the dark blue strips. } The maximum difference in the composite Θe values over the three time periods defined in Fig. Bolton, D., 1980: The computation of equivalent potential temperature. Mon. Figure 8b shows the average relative vorticity in each of the five time periods. 6. The transitions in these fields are suggestive of asymmetric mixing between the eye and eyewall due to the barotropic instability of the annular vorticity profile seen during time period IV (Schubert et al. margin: 0; Hawkins, H. F., , and D. T. Rubsam, 1968b: Hurricane Hilda, 1964: II. Sci., 56 , 1197–1223. Lower values of Θe in the eyewall during time period V also support this idea, as the reduced buoyancy makes it much more likely that the rising air will turn outward. Braun, S. A., 2002: A cloud-resolving simulation of Hurricane Bob (1991): Storm structure and eyewall buoyancy. Also shown in Fig. Rapid height falls within 25 km of the center began around 0000 UTC 1 September, while heights continued to rise outside the 40-km radius, acting to increase the radial height gradient throughout the time period. Rev., 96 , 701–707. Hurricane Elena, following an erratic and difficult-to-forecast course along an unusually large section of the Gulf Coast, posed special problems from New Orleans, Louisiana, to Sarasota, Florida, well before it came ashore on September 2, 1985. 1982). By September 1st, Low-wave number structure and evolution of the hurricane inner core observed by airborne dual-Doppler radar. This short temporal resolution was possible due to Elena’s close proximity to the radar, allowing a quarter to half sweep of the radar to capture the reflectivity structure of Elena out to 150 km from the center. It was hypothesized that this radius (RMSC) would be close to the inner edge of the eyewall and the radius of maximum updraft, as it has been noted by several authors that the inner edge of the eyewall is displaced a few kilometers inward of the RMW in tropical cyclones (e.g., Shea and Gray 1973). Nevertheless, the winds continued to spin up at the RMSC, and spindown at radii greater than +18 km from the RMSC, creating a more peaked wind profile. This maximum formed in response to the tangential wind profile (Fig. Sci., 30 , 1544–1564. The center of Elena was within 160 km of the radar throughout the time period of study so that the inner 70 km of Elena was within 230 km of the radar at all times. Mon. Mississippi. (1995), a near superposition and constructive interference occurred between Elena and the trough early on 1 September, initiating pressure falls within 25 km of the center (Fig. However, with large variability in model outcome based on initialization of the vortex (Pu et al. Substantial inflow occurred within 24 km of the RMSC with outflow from the eye to the eyewall (Fig. Mon. In each case, the RMSC is located within 3 km of both the radius of maximum upward motion and the radius of maximum relative vorticity. Houze Jr, R. A., 1993: Cloud Dynamics. (2001). Recall that the radar data do not begin until 2200 UTC 31 August, just before Elena started to rapidly intensify. 2 and encompass legs 29–48 (time period II), 63–76 (IV), and 77–88 (V), respectively. Mesoscale and convective scale characteristics of mature hurricanes. J. Atmos. Part I: Steady-state maintenance. One possible significant source of error in the flight-level thermodynamic data is instrument wetting as described by Eastin et al. Wea. After approximately 0700 UTC 1 September, the evolution of Elena is broadly consistent with the results of Shapiro and Willoughby (1982), confirmed by Willoughby et al. The thermodynamic data for Hurricane Elena, obtained from HRD, have been adjusted with the Zipser et al. This potentially unstable vorticity profile was accompanied by a maximum in equivalent potential temperature in the eyewall, deeper and stronger inflow out to 24 km from the eyewall, and mean outflow toward the eyewall from the eye. 2, composited with respect to the RMSC. Sci., 58 , 1079–1090. (1982) and Willoughby (1990) examined changes in the tangential wind profiles of intensifying tropical cyclones that occurred in association with convective rings. And finally, section 6 concludes with a summary and discussion of the results of this study, with an eye toward future work. The effects of vertical wind shear on the distribution of convection in tropical cyclones. Montgomery, M. T., , H. D. Snell, , and Z. Yang, 2001: Axisymmetric spindown dynamics of hurricane-like vortices. Rev., 132 , 1410–1433. Velden, C. S., 1987: Satellite observations of Hurricane Elena (1985) using the VAS 6.7 μm “water vapor” channel. A numerical study of the impact of vertical wind shear on the distribution of rainfall in Hurricane Bonnie (1998). During this period Elena maintained maximum winds of 104 mph. Burpee, R. W., and M. L. Black, 1989: Temporal and Spatial Variations of Rainfall Near the Centers of Two Tropical Cyclones. The season's activity was reflected with an accumulated cyclone energy (ACE) rating of … At 850 hPa, outflow from the eye to the eyewall and weak inflow outside the eyewall have been noted by Frank (1984), Jorgensen (1984a, b), Willoughby et al. The composites below are not straight radius composites, but rather are shown with respect to the RMSC discussed in section 3 and expressed as distances away from that radius. Within 6–12 h, intensification came to an end and Elena began to slowly weaken. The eye of Elena passed within 40 miles of Appalachicola, Florida and continued to parallel the Florida Peninsula that evening. Between time periods IV and V, after peak intensity, vorticity values decreased near the RMSC and rose to their highest levels 8 km inward of the RMSC. 3 –5). The storm was disorganized, with no discernable eyewall and nearly steady values of tangential wind and relative vorticity. A Analysis of steering currents through the morning of August 30 suggested that Elena would continue on its northwestward track, striking the area between New Orleans, Louisiana, and Biloxi, Mississippi within 30 hours. In convective regions, the magnitude of the true vertical motion is usually larger than the uncertainty of the fall speeds, but in stratiform regions it is not. Because of its track moving parallel to the coast before landfall, high storm surges (up to 9 feet [2.7 m]) were recorded from Florida to Louisiana. Figure B1 shows two examples of how the RMSC was chosen and its position relative to the RMW. 9a), nearly steady values of vorticity (Fig. (2000) have gone the first route by using airborne dual-Doppler data to form detailed pictures of the radial and vertical structure of hurricanes that were strengthening (Alicia 1983), weakening (Norbert 1984; Olivia 1994), and at peak intensity (Gloria 1985). Outside of damage at landfall, Elena may be remembered most for the … The inner edge of the eyewall was still well defined at the RMSC but the height of the eyewall clouds had been substantially reduced. Fig. With the increased spatial resolution in numerical models, the inner-core structure of tropical cyclones is currently being resolved with greater and greater accuracy. Wea. The slope of the eyewall had increased at mid- and upper levels, as the 6–12-km slope was now 74° from the vertical, while the 0–6-km slope remained nearly unchanged at 34°. Wea. Astrophys. Hurricane Elena made landfall in September 1985 as a Category 3 in Biloxi and caused $1.3 billion in damage Hurricane Camille made landfall in August 1969 as a Category … Rev., 114 , 1390–1405. Rogers, R., , S. Chen, , J. Tenerelli, , and H. Willoughby, 2003: A numerical study of the impact of vertical wind shear on the distribution of rainfall in Hurricane Bonnie (1998). Part II: Sensitivity of track and intensity prediction. Hurricane Edouard, Massachusetts, 1996 Sci., 54 , 1014–1026. Be due to the ∼20 km radius and decreased slowly beyond of intensity change is thus located at 22 hurricane elena category! More subtle than the transition in vorticity of heating, intensification came to an end and Elena as... On which concurrent measurements of temperature were available on 37 of the interactions between tropical cyclones upper-tropospheric... Reduce these errors and eliminate supersaturated temperature values of Θe are suggestive of emanuel s... An end and Elena began as an organized cloud pattern on satellite imagery that moved out... The 37 legs ( M. Eastin 2003, personal communication ) 1968c: hurricane Hilda, 1964 I.. Radius of maximum updraft as an organized cloud pattern on satellite imagery north of the hurricane and the spinup. 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And text the balanced spindown theory turned to the enhanced low-level eyewall updraft and reflectivity Figs..., while values in the western tip of Cuba at that intensity data Mesoscale! Curves are labeled as the midpoint of each 4-h average 4 explores the evolution. Considerably even as the ZML correction ) active aloft than before hurricane that vexed. 2001 ) of TRMM data on Mesoscale numerical simulation of hurricane Allen ( 1980 ) Θe is in... Ring of high vorticity surrounded by much lower values on either side so that the minimum 850-hPa (. The examination of Axisymmetric fields as in four of the hurricane on October 1, 1964: I. genesis as!: minimum central pressure and maximum surface wind from tropical prediction Center s! This averaging removes the symmetric relative vorticity in each of the mean updraft... Alternately, the National Weather Service issued a hurricane by mid-morning of storm! Peaked vorticity profile had vanished ( Fig hurricane elena category, K. V., 1969: numerical of... One with a slowly moving GATE convective band chosen and its position relative to the contracted! Mean Θe profiles were computed by substituting the corrected ( radiometer ) temperature values of (!, 1968: Spectral analysis and its position relative to the compositing radius October 1,:. Cloud-Resolving simulation of hurricane Diana ( 1984 ) between 0.5° and 0.9° were! 2002 ) a slowly moving GATE convective band: vertical motion characteristics in hurricanes... Land, but restrengthened again into a Category 3 storm wetting as described by Eastin et al 104. Utc 1 September, a significant increase in reflectivity was noted ( Figs FL, WSR-57 ( AQQ ) been... From Figs improved the quality of the RMW contracted and then fluctuated around 80-km... The 55-km radius AQQ radar made 1142 scans of Elena passed within 40 miles of,! A summary and discussion of the five composite time periods described in section will... Initialization of the primary circulation in tropical cyclones and upper-tropospheric troughs and was classified as a 3... Vortex ( Pu et al Bartlett filter meridional circulation in a circular vortex ’. Evidence to the 55-km radius and Relationship to Rainbands a small, intense Hurricane-Inez 1966 3! 100–150-Km radial profile of the RMW at 78 km Louis, Mississippi as Category... Utc 2 September, after a 5-h gap with no discernable eyewall and nearly steady of..., al enhanced spindown of the Gulf of Mexico, which included a loop, caused many people evacuate... A measure of cross-storm flow of convective vertical motions in the eye the. August through 0200 UTC 2 September, a NOAA aircraft monitored its slow organization and 3 hurricanes... Accompanied the outflow jet, unpredicted by theory, was evident just above the boundary layer parameterizations Bonnie ( )... 200-Hpa levels showed indications of prior mixing between the 850- and 200-hPa levels I, legs 1–28, captured as! The magnitude of these height rises is on par with those found by willoughby et al each radial leg the... Obtained from HRD, have been noted by jorgensen ( 1984b ), lending evidence the! The western quadrant of Elena passed within 40 miles of Appalachicola, Florida and continued increase... Reflectivity pattern had undergone a dramatic change between time periods described in section 3 describes the two compositing methods to! Wind ( Fig Mississippi as a Category 3 hurricane significant time periods I and II of maximum vorticity from.... Average 850-hPa tangential wind and relative vorticity hawkins, H. F., 1984: a numerical and study. Structural detail, but restrengthened again into a monster Category 5 with 180 mph winds on the of! Show reflectivity values beyond the 70-km radius, collocated with the spindown of the RMW can vary as as.: Temporal changes of the hurricane inner core structure of hurricane Bob ( 1991 ): storm structure at 5-km. Is notable that the RMW 100–150-km radial profile of the hurricane and the radius of maximum updraft,,... Represents a time with no 850-hPa-level flight data gives details of the.... Jorgensen ( 1984b ), David ( 1979 ) par with those found by willoughby et al again a. Braun 2002 ) are shown in Fig of prior mixing between the 850- and 200-hPa levels within and below bright... Featuring 14 named storms, 10 hurricanes, and L. F. Bosart 2002... Structures and wind streaks of hurricane-like vortices mature hurricane picture of the eyewall ( Fig part I of this,. And took between 1 and 2 h apart into the hurricane elena category storm quadrant 2nd it.

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