DOCSLIB.ORG

The Development and Motion of Typhoon "Doris," 1950

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Development and Motion of Typhoon 326 BULLETIN AMERICAN METEOROLOGICAL SOCIETY The Development and Motion of Typhoon "Doris," 1950 GEORGE P. CRESSMAN Hq.y Air Weather Service, Washington, D. C. ABSTRACT The development and motion of typhoon "Doris," which was observed during the first two weeks of May, 1950, are studied. The development of the storm is examined with respect to pre- viously published theories of storm formation. The original deepening occurred in the low latitude portion of an extended trough, after the fracture of the trough. This is in agreement with a model proposed by Riehl. The motion of the deepening storm relative to the high-level flow patterns differed from previously studied examples in that the deepening occurred as the low-level cyclone moved from under the west side of an upper anticyclone toward a position un- der an upper cyclone. The storm developed as two cyclonic vortices, which gradually merged into one, in agreement with a principle of Fujiwhara. The motion of the storm northward, as it broke through the subtropical ridge line, is shown. After examination of several possibilities, this motion is attributed to the resultant of all the Coriolis forces acting on the storm, as discussed by Rossby. The suggestion is made that this resultant force becomes prominent in determining the motion of the storm due to changes in the radial velocity profile and the increasing geographical extent of the storm. "^HE development and movement of ty- southern hemisphere and the northern hemisphere phoon "Doris," which occurred in the west easterlies. This is suggested by a west wind at Pacific in the first two weeks of May 1950, 10,000 feet at Honiara (09°S, 160°E) on 1 May, offer an opportunity for the testing of several new and is confirmed by the streamline chart of 2 May. itheorie s relating to tropical cyclones. There were By 03GCT, 2 May, the northern part of the west an unusually large number of upper-air observa- tions available for this part of the world, and a reasonably complete life history of the cyclone can be derived. THE DEVELOPMENT STAGE It is convenient to trace the development by starting with the 10,000-ft streamline chart (FIG. 1) and the 700-rnb chart (FIG. 2) for 0300 GCT, 1 May 1950. The pattern of middle latitude long waves consists of a trough over Manchuria, a ridge east of Japan and Sakhalin, a trough at about 167°E, and a ridge at about 170°W. As a result of the short wavelength from trough to trough in this pattern, the west Pacific trough was moving rapidly eastward. It was shown in a previous in- vestigation [1] that if the higher-latitude portion of an extended trough is moving rapidly east- ward, it will be unable to retain its tropical ex- FIG. 1. 10,000-ft streamlines, 0300 GCT, 1 May 1950. In this and subsequent charts winds from aircraft are in- tension. In the present example, then, the portion cluded from a total period of twelve hours, centered on of the extended trough which lies in the tropics the map time. No correction in position is made in the should break off from the middle latitude trough. plotting for aircraft wind reports computed between fixes. According to Riehl and Burgner [10] this frac- Pilot balloon reports six hours off map time are indicated ture produces a situation which is favorable for by a dashed shaft. Apparent discrepancies occasionally low-latitude cyclogenesis. An additional factor seen between winds and streamlines arise primarily be- of some importance is the existence of a line of cause the winds are off time or represent mean values shear between cross-equatorial westerlies from the between fixes. Unauthenticated | Downloaded 10/04/21 08:35 AM UTC VOL. 32, No. 9, NOVEMBER, 1951 327 ception of the one ascent on 15 GCT, 4 May, strengthening of the winds through 5 May. This interpretation of the Truk winds is supported by the cloud-distribution charts. The altostratus deck over the Marshalls on 1 May moves toward the WSW as a relatively small patch until 3 May. A large extension of the area of towering cumulus in the Carolines area can be observed on the charts for 2 and 3 May. Then from 3 to 4 May the deck of altostratus increases greatly over the Carolines and over the route from Kwajalein to Guam. At the same time, the cumulus activity over the Carolines decreases along with the in- creasing horizontal circulation. It is at 21 GCT on 3 May that a 45 knot wind is reported from Truk at 3000 feet. By 4 May continuous rain is FIG. 2. 700-mb chart, 0300 GCT, 1 May 1950. In this and subsequent charts, locations where the height of the 700-mb (or other) constant pressure surface was re- ported are indicated by heavy dots. Pacific trough had moved 13° longitude eastward. As far south as 15°N the trough moved at least 5° longitude toward the east, as shown by FIGURE 3. By 5 May (see FIG. 7) the northern part of the trough is just west of Wake and Midway, which it passes before 6 May. However, the southern end of the trough broke off from the eastward mov- ing part, beginning 2 May. FIG. 4. Time section and 24-hr pressure changes from The gradual formation of a cyclonic center near 1-6 May 1950, for Truk. Truk (07°N, 152°E) is shown by the time-section for Truk (FIG. 4) and from the cloud-distribution falling at Truk and Ponape, and a closed cyclonic charts (FIG. 5). In the time section it appears circulation is drawn near Truk on FIGURE 6. that after the weak trough passage at Truk on the On 5 May (FIG. 7) a flight from Guam to first, there is a gradual veering and, with the ex- Truk passed through a new, apparently secondary, center near 11°N, 148°E. The existence of the center is indicated by a cyclonic wind circulation and by an area of cumulonimbus and bad weather which the aircraft encountered near the center of the secondary circulation. The tendency for "troughing" in the streamlines on the Kwajalein to Guam route is particularly evident on 5 May. This suggests the beginning of a split in the anti- cyclone north of this area. Such a split was defi- nitely confirmed by a flight from Tokyo to Wake on the next day. A sudden backing of the low-level winds at Truk is observed at about 00 GCT 6 May (How- ever, the surface and 1,000-ft winds are unrepre- sentative due to terrain effects). This observation might be suspected to be an error. However, the graph of 24-hr pressure change indicates a maxi- mum of falls late in the fifth, and the first thunder- FIG. 3. 10,000-ft streamlines, 0300 GCT, 2 May 1950. storm activity at Truk occurs early in the sixth. Unauthenticated | Downloaded 10/04/21 08:35 AM UTC 328 BULLETIN AMERICAN METEOROLOGICAL SOCIETY The streamline chart for 6 May (FIG. 8) is there- fore analyzed to show the original center moving eastward past Truk as the two centers begin to rotate about each other, as described by Fuji- whara [3] [4] and Haurwitz [15]. The separate identity of these centers cannot be maintained in the analysis past the sixth, as a result of the rapidly increasing circulation and a lack of sufficiently de- FIG. 5d. Cloud distribution chart 0300 GCT, 4 May 1950. FIG. 5a. Cloud distribution chart 0300, 1 May 1950. Vertical hatching indicates areas of towering cumulus (tops above 8,000 feet). Horizontal hatching indicates areas of broken or overcast altostratus. Dots indicate observation locations. FIG. 5e. Cloud distribution chart 0300 GCT, 5 May 1950. FIG. 5b. Cloud distribution chart 0300 GCT, 2 May 1950. FIG. 6. 10,000 ft streamlines, 0300 GCT, 4 May 1950. tailed data. On the sixth the surface wind at Truk remains from S to SE, and the 24-hr pressure falls continue, although at a slower rate. From this it can be concluded that the second center is moving southward in the area west of Truk. After 6 May the only further indication of two centers comes FIG. 5C. Cloud distribution chart 0300 GCT, 3 May 1950. from the Air Weather Service reconnaissance Unauthenticated | Downloaded 10/04/21 08:35 AM UTC VOL. 32, No. 9, NOVEMBER, 1951 329 double eye might be a final remnant of the origi- nal double system of circulations which, through low-level convergence operating over a period of time, gradually merged into a single system. Other solutions are also possible, in the absence of more detailed data, but they would be more complicated than the one presented above. The conclusion however, would be the same in that a system originally containing several vortices gradually intensified into a single typhoon, with the double eye as a final indication of the original complications. The development of "Doris" to typhoon strength concurrently with the appearance and amalgama- tion of the two centers is a remarkable verification of views presented by Fujiwhara in 1923 [3] and again in 1937 [5]. In these two papers Fujiwhara FIG. 7. 10,000 ft streamlines, 0300 GCT, 5 May 1950. presented a theory proposing that small adjacent vortices with the same sense of rotation will tend flight Vulture Three Doris on 8 May. The re- to amalgamate, leading to the appearance of a port of the weather observer, CWO K. R. single large vortex. Walters,1 includes the following paragraph: Recently Riehl [11] has pointed out the impor- "It is believed that there were two eyes in tance of the high-level flow pattern for the deepen- Doris at the time of this flight, a small one lying ing of tropical cyclones.
Load more

Recommended publications
  • P1.24 a Typhoon Loss Estimation Model for China
    P1.24 A TYPHOON LOSS ESTIMATION MODEL FOR CHINA Peter J. Sousounis*, H. He, M. L. Healy, V. K. Jain, G. Ljung, Y. Qu, and B. Shen-Tu AIR Worldwide Corporation, Boston, MA 1. INTRODUCTION the two. Because of its wind intensity (135 mph maximum sustained winds), it has been Nowhere 1 else in the world do tropical compared to Hurricane Katrina 2005. But Saomai cyclones (TCs) develop more frequently than in was short lived, and although it made landfall as the Northwest Pacific Basin. Nearly thirty TCs are a strong Category 4 storm and generated heavy spawned each year, 20 of which reach hurricane precipitation, it weakened quickly. Still, economic or typhoon status (cf. Fig. 1). Five of these reach losses were ~12 B RMB (~1.5 B USD). In super typhoon status, with windspeeds over 130 contrast, Bilis, which made landfall a month kts. In contrast, the North Atlantic typically earlier just south of where Saomai hit, was generates only ten TCs, seven of which reach actually only tropical storm strength at landfall hurricane status. with max sustained winds of 70 mph. Bilis weakened further still upon landfall but turned Additionally, there is no other country in the southwest and traveled slowly over a period of world where TCs strike with more frequency than five days across Hunan, Guangdong, Guangxi in China. Nearly ten landfalling TCs occur in a and Yunnan Provinces. It generated copious typical year, with one to two additional by-passing amounts of precipitation, with large areas storms coming close enough to the coast to receiving more than 300 mm.
    [Show full text]
  • Tropical Cyclogenesis Associated with Rossby Wave Energy Dispersion of a Preexisting Typhoon
    VOLUME 63 JOURNAL OF THE ATMOSPHERIC SCIENCES MAY 2006 Tropical Cyclogenesis Associated with Rossby Wave Energy Dispersion of a Preexisting Typhoon. Part I: Satellite Data Analyses* TIM LI AND BING FU Department of Meteorology, and International Pacific Research Center, University of Hawaii at Manoa, Honolulu, Hawaii (Manuscript submitted 20 September 2004, in final form 7 June 2005) ABSTRACT The structure and evolution characteristics of Rossby wave trains induced by tropical cyclone (TC) energy dispersion are revealed based on the Quick Scatterometer (QuikSCAT) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data. Among 34 cyclogenesis cases analyzed in the western North Pacific during 2000–01 typhoon seasons, six cases are associated with the Rossby wave energy dispersion of a preexisting TC. The wave trains are oriented in a northwest–southeast direction, with alternating cyclonic and anticyclonic vorticity circulation. A typical wavelength of the wave train is about 2500 km. The TC genesis is observed in the cyclonic circulation region of the wave train, possibly through a scale contraction process. The satellite data analyses reveal that not all TCs have a Rossby wave train in their wakes. The occur- rence of the Rossby wave train depends to a certain extent on the TC intensity and the background flow. Whether or not a Rossby wave train can finally lead to cyclogenesis depends on large-scale dynamic and thermodynamic conditions related to both the change of the seasonal mean state and the phase of the tropical intraseasonal oscillation. Stronger low-level convergence and cyclonic vorticity, weaker vertical shear, and greater midtropospheric moisture are among the favorable large-scale conditions.
    [Show full text]
  • Influence of Sea Salt Aerosols on the Development of Mediterranean
    Atmos. Chem. Phys., 21, 13353–13368, 2021 https://doi.org/10.5194/acp-21-13353-2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Influence of sea salt aerosols on the development of Mediterranean tropical-like cyclones Enrique Pravia-Sarabia1, Juan José Gómez-Navarro1, Pedro Jiménez-Guerrero1,2, and Juan Pedro Montávez1 1Physics of the Earth, Regional Campus of International Excellence (CEIR) “Campus Mare Nostrum”, University of Murcia, 30100 Murcia, Spain 2Biomedical Research Institute of Murcia (IMIB-Arrixaca), 30120 Murcia, Spain Correspondence: Juan Pedro Montávez ([email protected]) Received: 23 December 2020 – Discussion started: 11 February 2021 Revised: 26 July 2021 – Accepted: 16 August 2021 – Published: 9 September 2021 Abstract. Medicanes are mesoscale tropical-like cyclones 1 Introduction that develop in the Mediterranean basin and represent a great hazard for the coastal population. The skill to accurately simulate them is of utmost importance to prevent econom- Mediterranean tropical-like cyclones, also known as medi- ical and personal damage. Medicanes are fueled by the la- canes (from mediterranean hurricanes), are mesoscale per- tent heat released in the condensation process associated turbations that exhibit tropical characteristics, such as an with convective activity, which is regulated by the pres- eye-like feature and warm core. These storms are character- ence and activation of cloud condensation nuclei, mainly ized by high wind speeds and vertically aligned geopoten- originating from sea salt aerosols (SSAs) for marine envi- tial height perturbations along different pressure levels. Just ronments. Henceforth, the purpose of this contribution is like regular tropical cyclones, medicanes represent a hazard twofold: assessing the effects of an interactive calculation of for the population of coastal areas.
    [Show full text]
  • Analysis on Typhoon Longwang Intensity Changes Over the Ocean Via Satellite Data
    Journal of MarineC.-C. Science Liu etand al .:Technology, Analysis on Vol. Typhoon 17, No. Longwang 1, pp. 23-28 Intensity (2009) Changes Over the Ocean via Satellite Data 23 ANALYSIS ON TYPHOON LONGWANG INTENSITY CHANGES OVER THE OCEAN VIA SATELLITE DATA Chung-Chih Liu*, Tian-Yow Shyu**, Chun-Chieh Chao***, and Yu-Feng Lin*** Key words: typhoon, anticyclonic divergence, radiate. I. INTRODUCTION Typhoons are one of nature’s most destructive weather sys- ABSTRACT tems. Most of them form and develop over the ocean. However, traditional observations are often not sufficient, due to the dif- The changes in the typhoon intensity are a very important ficulty and resources required for the data collection. Thus, process. In this study, we used satellite data to analyze the cloud satellite remote sensing data serves as a much better choice in structure of Typhoon Longwang. Results show that the changes terms of its spatial and temporal resolutions. The geostationary in the high level cirrus pattern seemed to have a connection to meteorological satellite has become an available tool for de- the typhoon intensity. During the time period from 0600UTC to termining the typhoon location, structure and intensity. When 1200UTC 30 September 2005, the high level cirrus clouds of geostationary satellite images were available, the identification Typhoon Longwang radiated from the inner core region. The and tracking of tropical cyclones turned into a trivial task. cloud area that Typhoon Longwang covered grew larger, and the However, many problems still exist in terms of weaker tropical pattern changed from a asymmetric to symmetric distribution cyclones. The scientists at NOAA/NESDIS led by Vern Dvorak during 0000UTC to 1200UTC 30 September 2005.
    [Show full text]
  • RMS Philippines Typhoon and Inland Flood Model Captures Risk from Typhoon Wind and Flooding, Coastal Storm Surge, and Seasonal Precipitation-Driven Flooding
    RMS Philippines Typhoon and Inland Flood Model Captures Risk From Typhoon Wind and Flooding, Coastal Storm Surge, and Seasonal Precipitation-Driven Flooding Overview KEY FEATURES Situated on the Pacific Ring of Fire and in the western North Pacific Typhoon AND BENEFITS Basin, the Philippines is one of the most disaster-prone countries in the world. Approximately 20 tropical cyclones enter the Philippine Area of Responsibility each year, with around eight making landfall. The transition of the Philippine economy Captures the risk from typhoon • from agriculture to services and manufacturing has increased the value of exposure wind and flooding plus seasonal monsoon-driven flooding at risk to typhoons and flooding. • Precipitation-driven inland flood The RMS® Philippines Typhoon and Inland Flood Model enables users to model the model and fully hydrodynamic typhoon-related risks of wind, typhoon-driven flood, and storm surge, in addition to surge model for key coastal areas seasonal and monsoon flood events. The model expands the RMS suite of climate Hazard modeled at high • modeling solutions to the Philippines. geographical resolution to accurately capture the variations in risk Complete Wind and Flood Risk Solution • Stochastic event set contains Tropical cyclones bring the associated perils of strong wind, heavy precipitation, and thousands of tropical cyclone storm surge leading to flooding. These three typhoon-related perils are captured tracks to capture the full spectrum by a set of thousands of stochastic tropical cyclone tracks representing the full of landfalling and bypassing spectrum of potential landfalling and bypassing events to affect the Philippines. storms In addition, the southwest Habagat monsoon from May to October, and northeast • Model includes almost 1,000 Amihan monsoon from November to April can bring heavy rainfall and flooding.
    [Show full text]
  • Cyclones, Hurricanes, Typhoons and Tornadoes - A.B
    NATURAL DISASTERS – Vol.II - Cyclones, Hurricanes, Typhoons and Tornadoes - A.B. Shmakin CYCLONES, HURRICANES, TYPHOONS AND TORNADOES A.B. Shmakin Institute of Geography, Russian Academy of Sciences, Moscow, Russia Keywords: atmospheric circulation, atmospheric fronts, extratropical and tropical cyclones, natural disasters, tornadoes, vortex flows. Contents 1. Atmospheric whirls of different scales and origin 1.1. Cyclones: large-scale whirls 1.2. Tornadoes: small, but terrifying 2. What are they like? 2.1. How big, how strong? 2.2. How they behave? 2.3. Disasters caused by the whirls 2.4. Forecasts of atmospheric circulation systems 3. What should we expect? Glossary Bibliography Summary The article presents a general view on atmospheric whirls of different scales: tropical and extratropical cyclones (the former group includes also hurricanes and typhoons) and tornadoes. Their main features, both qualitative and quantitative, are described. The regions visited by thesekinds of atmospheric vortices, and the seasons of their activity are presented. The main physical mechanisms governing the whirls are briefly described. Extreme meteorological observations in the circulation systems (such as strongest wind speed, lowest air pressure, heaviest rainfalls and snowfalls, highest clouds and oceanic waves) are described. The role of circulation systems in the weather variations both in tropical and extratropical zones is analyzed. Record damage brought by the atmospheric whirls is described too, along with their biggest death tolls. A short historical reviewUNESCO of studies of the circulation – systems EOLSS and their forecasting is presented. Contemporary and possible future trends in the frequency of atmospheric calamities and possible future damage, taking into account both natural and anthropogenic factors, are given.
    [Show full text]
  • Tropical Cyclone Genesis Tropical Cyclone Genesis
    , . NSF GRANT , G,A - 325 8 9 X 3 TROPICAL CYCLONE GENESIS TROPICAL CYCLONE GENESIS by William M. Gray Preparation of this report has been financially supported by National Science Foundation Grant GA-32589X3 Department of Atmospheric Science Colorado State University Fort Collins, Colorado March, 1975 Atmospheric Science Paper No. 234 ABSTRACT A new global observational and theoretical study of tropical cyclone genesis is made. This is an extension of the author's previous study (Gray, 1968) on this subject. Cyclone initial genesis locations have been stratified by season for the 20-year period of 1952-1971. Wind, temperature and moisture information are averaged by season and by 5-degree latitude-longitude Marsden squares. It is observationally shown and physical reasons are given why seasonal cyclone genesis fre- quency is related to the product of the seasonally averaged parameters of: 1) low level relative vorticity, 2) Coriolis parameter, 3) inverse of the vertical shear of the horizontal wind from lower to upper tropo- sphere, 4) ocean's thermal energy to 60 meters' depth, 5) moist stability from the surface to 500 mb, and 6) middle troposphere relative humidity. A seasonal forecast potential of cyclone genesis frequency is derived. This forecast potential very well specifies the location and frequency of global cyclone genesis. A general theory on cyclone frequency is advanced. i LIBRARIES cQtOItADO ~T ATE UN!V!'!<SITY fort (:011 ins, Coioredo 80~23 TABLE OF CONTENTS Page 1. INTRODUCTION • • • 1 Numerical Modeling • 3 Definitions. 5 Conclusion • • 7 2. CYCLONE ORIGIN STATISTICS. 9 3. PHYSICAL REQUIREMENTS OF CYCLONE GENESIS • ~ • • 17 Enthalpy Increase through Release of Latent Heat 17 Cloud Cluster Characteristics.
    [Show full text]
  • Impact of Typhoons on the Composition of the Upper Troposphere Within The
    Impact of typhoons on the composition of the upper troposphere within the Asian summer monsoon anticyclone: the SWOP campaign in Lhasa 2013 Dan Li1,2, Bärbel Vogel2, Jianchun Bian1,3, Rolf Müller2, Laura L. Pan4, Gebhard Günther2, Zhixuan Bai1,3, Qian Li1, Jinqiang Zhang1, Qiujun Fan1,3, and Holger Vömel5 1Key Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China 2Institute of Energy and Climate Research: Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, Germany 3College of Earth Science, University of Chinese Academy of Sciences, Beijing, China 4Atmospheric Chemistry Observations & Modeling, National Center for Atmospheric Research, Boulder, CO, USA 5Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, CO, USA Correspondence to: Dan Li ([email protected]) Abstract. In the frame of the SWOP (sounding water vapour, ozone, and particle) campaign during the Asian summer monsoon (ASM), ozone and water vapour profiles were measured by balloon-borne sensors launched from Lhasa (29.66◦ N, 91.14◦ E, elevation 3,650 m), China, in August 2013. In total, 24 soundings were launched, nearly half of which show strong variations in the relationship between ozone and water vapour in the tracer−tracer correlation in the upper troposphere and lower strato- 5 sphere (UTLS). 20-day backward trajectories of each sounding were calculated using the trajectory module of the Chemical Lagrangian Model of the Stratosphere (CLaMS) to analyse these variations. The trajectory calculations demonstrate that three tropical cyclones (tropical storm Jebi, typhoons Utor and Trami), which occurred over the Western Pacific Ocean during Au- gust 2013, had a considerable impact on the vertical distribution of ozone and water vapour by uplifting marine air masses to altitudes of the ASM anticyclone.
    [Show full text]
  • Peculiar Supercell Tornadoes Caused by Typhoon ‘Neoguri’
    1A.9 PECULIAR SUPERCELL TORNADOES CAUSED BY TYPHOON ‘NEOGURI’ Soichiro Yuasa and Koji Sassa* Dept. of applied Science, Kochi University 1. INTRODUCTION Two tornadoes simultaneously occurred near Typhoon is one of major source of tornadoes Kochi airport on 10 July, 2014. At this time, in Japan. Some Typhoons cause mini- Typhoon, ‘Neoguri’ located at just west of supercell tornadoes (Suzuki et al. 2000). Kyushu Island and its outer rainband passed Typical case is the Nobeoka tornado caused by through the Kochi Plain as shown in Fig. 1. Typhoon ‘Shanshan’ on 17 September 2006 Though the seashore from Kochi city to Aki city (Mashiko et al. 2009). The Nobeoka tornado is a hot spot of non-supercell tornadoes (Sassa occurred in the outer rainband of the Typhoon et al. 2011), we thought possibility that mini ‘Shanshan’. supercell may occur in the outer rainband and caused these tornadoes. The present study aims to clarify the characteristics of parent storm of these tornadoes by analyzing using the data of the JMA radar and the polarimetric radars in Kochi University. 2. ANALYSIS AND DATA We observed the parent cloud of tornedoes by two polarimetric X-band Doppler radars of Kochi University, Asakura Radar and Monobe Radar, and the Muroto C-band Doppler radar of Japan Meteorological Agency (JMA). As shown in Fig.2, observation ranges of the Monobe, Asakura and JMA-Muroto radars are 30 km, 80 km and 200 km, respectively. We obtained reflectivity and Doppler velocity from PPI scans Fig.1 JMA-Radar echo and wind field at 06:00 JST. *Corresponding author address: Kochi University, 2-5-1akebono-cho, kochi-shi, Kochi Fig.2 Observation areas of radars.
    [Show full text]
  • CHAPTER 7 Extratropical Transition of Tropical Cyclones in the North Atlantic
    CHAPTER 7 Extratropical transition of tropical cyclones in the North Atlantic J.L. Evans1 & R.E. Hart2 1Department of Meteorology, The Pennsylvania State University, Pennsylvania, USA. 2Florida State University, Florida, USA. Abstract Apart from a few early case studies that documented tropical cyclones (TCs) that tracked into the extratropics, it was generally accepted through the 1970s that TCs would decay as they moved out of the tropics. This preconception was challenged in the 1980s. Over the past two decades, a flurry of research on these extratropi- cally transitioning TCs has revealed much about their behavior. Here, we discuss extratropically transitioning TCs, beginning from their tropical formation, the con- ditions under which they evolve, and their spatial and temporal distributions. Case studies are presented and potential indicators of transition, of use to the forecast community, are introduced. Case studies demonstrate the need for research into the interactions between the evolving TC and an approaching higher latitude trough. Constructive interactions between these systems, when accompanied by a supportive remnant tropical envi- ronment, will lead to transition and possibly reintensification of the storm as an extratropical system. Key results include a late season maximum in the percentage of storms that undergo transition. This late season peak is related to the need for synoptic support for tropical development to intensify cyclones prior to transition, followed almost immediately by a strong baroclinic synoptic energy source as transition occurs. Recognition of key structural changes as the storm transitions has led to the devel- opment of a number of indicators of transition currently being tested by the forecast community.
    [Show full text]
  • NOUS41 KWBC 011445 PNSWSH Public Information Statement 21-21 National Weather Service Headquarters Silver Spring MD 1045 AM
    NOUS41 KWBC 011445 PNSWSH Public Information Statement 21-21 National Weather Service Headquarters Silver Spring MD 1045 AM EDT Thu Apr 1 2021 To: Subscribers: -NOAA Weather Wire Service -Emergency Managers Weather Information Network -NOAAPort Other NWS Partners and NWS Employees From: Allison Allen, Chief Marine, Tropical and Tsunami Services Branch Subject: Soliciting comments through April 1, 2022 on experimental Arrival of Tropical- Storm-Force Winds Graphics for the South Pacific and western North Pacific provided by the Central Pacific Hurricane Center (CPHC) based on forecasts from the Joint Typhoon Warning Center (JTWC) The NWS is soliciting public comments through April 1, 2022, on experimental graphics provided by the Central Pacific Hurricane Center (CPHC) that project the arrival time of tropical-storm- force winds for tropical cyclones in the South Pacific and western North Pacific basins based on Joint Typhoon Warning Center (JTWC) forecasts. These graphics will use the same format as graphics that are operationally provided on hurricanes.gov for the central and eastern North Pacific and the Atlantic basins based on NWS forecasts. The anticipated arrival of sustained tropical-storm-force winds from a tropical cyclone is a critical threshold for coastal and inland communities. For example, emergency managers use this information to help determine when to begin and complete coastal evacuations. Members of the public need to know when to prepare their homes or businesses in advance of hazardous weather. Once sustained tropical-storm-force winds begin, such preparations usually become too dangerous or difficult. Historically, many decision makers have inferred the arrival of sustained tropical-storm-force winds from deterministic tropical cyclone forecasts, without accounting for tropical cyclone track or size uncertainty.
    [Show full text]
  • The Air Typhoon Model for Japan
    In 2018 and 2019, four powerful The AIR Typhoon typhoons struck Japan, incurring total insured losses of more Model for Japan than USD 30 billion from wind, precipitation-induced flooding, and storm surge damage. As the number and value of properties in Japan’s risk-prone areas continues to grow, it is essential for companies operating in this market to have the tools that will help effectively manage and mitigate the financial risks from future devastating typhoons. THE AIR TYPHOON MODEL FOR JAPAN While in the context of Japan’s recent The AIR Typhoon Model for Japan—part of AIR’s Northwest Pacific Basinwide Typhoon Model—provides a realistic view typhoon history, the losses for the of potential losses from tropical cyclones with a catalog back-to-back seasons of 2018 and incorporating cutting-edge science that best reflects the current understanding of the spatial-temporal characteristics 2019 seem high, we know that if of tropical cyclones in this basin. To facilitate risk assessment Typhoon Ida (1958) and Typhoon and risk differentiation at a highly granular level, the model incorporates the latest engineering research in the resilience of Vera (1959) were to recur today, local construction to the perils of typhoon winds, precipitation- the losses would be even higher. induced flooding, and storm surge. In the stochastic catalog of the AIR Robust Catalog Leverages Data from Leading Regional Organizations Typhoon Model for Japan, there are The model features a large catalog of simulated events that 698 instances of aggregated insured appropriately characterizes the frequency, track, and other meteorological aspects of potential future storms.
    [Show full text]