The Sub-regional Focal Point, Jamaica which is the lead for the North-western sub-region has been contacted for advancing arrangements for launching any support if necessary. Arrangements for a reconnaissance aircraft are being advanced for deployment if necessary. CDEMA will continue to monitor the situation and provide updates as warranted. Regional Response Mechanism. News Centre.
Press Releases. Rainfall totals in the Leeward Islands were generally 25—50 mm. Maria produced storm surge values of 0. Croix, St. The highest observed storm tide was 0. As Maria passed west of Bermuda on 15 September, sustained winds of 34 kt were reported at L. Wade International airport, along with a peak wind gust of 43 kt. The estimated landfall intensity of 60 kt is based on subjective Dvorak intensity estimates and a min-average wind of 52 kt from Environment Canada buoy at UTC, which suggests a peak 1-min wind of 57 kt when applying an adjustment factor of 1.
Rainfall amounts in the Burin Peninsula and the south coast of Newfoundland were around 60 mm, with a total of 63 mm observed at St. Nate originated from the frontal trough that was responsible for the extratropical transition of Tropical Storm Lee. The front moved through the western half of the Gulf of Mexico on 5 September and became stationary from the south-central Gulf of Mexico to the Bay of Campeche later that day.
An area of low pressure formed along the southern end of the front around UTC 6 September about n mi northwest of Ciudad del Carmen, Mexico. The circulation of the low separated from the front on 7 September, while convection increased but remained disorganized. Scatterometer data indicated that the low had gale-force winds by this time, but these winds were at least partially associated with a strong low-level pressure gradient behind the weakening cold front.
A curved convective band formed over the western semicircle of the circulation later that day, marking the formation of a tropical storm around UTC 7 September about n mi north of Villahermosa, Mexico. Embedded within a weak steering flow, Nate drifted southeastward and gradually strengthened. Data from a reconnaissance aircraft and a nearby oil rig indicated that Nate reached hurricane strength around UTC that day when it was located about 70 n mi north-northwest of Ciudad del Carmen.
The broad wind field and slow forward motion of the cyclone over the shallow waters of the Bay of Campeche caused significant upwelling of the oceanic mixed layer, which resulted in a large area of significantly cooler waters under Nate.
The combination of dry air and a lower oceanic heat content caused the intensity and coverage of deep convection in the cyclone to decrease considerably early on 9 September, resulting in weakening. As Nate moved westward away from the upwelled waters on 10 September, convection around the circulation became reinvigorated.
A brief reintensification of the cyclone began around UTC that day, despite the still relatively dry air in the near-storm environment. The midlevel ridge over Mexico strengthened around this time, and Nate responded by moving more quickly toward the west. Some weakening occurred and the low- and midlevel centers became detached; the midlevel center moved inland north of Veracruz while the low-level center of the weakening tropical storm crossed the coast of northeastern Mexico near Barra de Tecolutla at UTC 11 September.
Rapid weakening occurred after landfall, and Nate dissipated by the next day. Air Force Reserve Hurricane Hunter aircraft flew a total of six missions in Nate and obtained 16 fixes.
The maximum observed flight-level wind mb in Nate was 82 kt southeast of the center at UTC 8 September. This occurred several hours after the time of the peak winds measured by the aircraft, also to the southeast of the center.
An adjustment of the oil rig observation to the standard m height, using the mean hurricane dropwindsonde profile, yields a peak sustained surface wind estimate of 67 kt. These data and the earlier reconnaissance measurements support the estimate of Nate's peak intensity of hurricane strength. There were four direct deaths associated with Nate.
Ten workers were forced to abandon their lifeboat on 8 September after evacuating the Trinity II oil rig and only seven survived. Lightning killed a 9-yr-old child in the state of Veracruz. No serious damage was reported in association with Nate's landfall in eastern Mexico. Press reports indicate that about homes were damaged in Veracruz. A surface low developed from the interaction of a tropical wave and the intertropical convergence zone ITCZ about n mi west-southwest of the Cape Verde Islands.
Ophelia intensified slowly in an environment of moderate southwesterly shear during the next 24—36 h as it moved westward over the tropical Atlantic. Southwesterly shear increased later on 22 September, causing the cyclone to weaken over the next couple of days as it approached the northern Leeward Islands and Ophelia degenerated into a remnant low pressure system about UTC 25 September.
Conventional satellite and microwave data indicate that the remnant circulation dissipated by UTC 26 September. Although the low-level center of the tropical cyclone had dissipated, the associated deep convection lingered along with a well-defined midlevel circulation. An elongated surface circulation redeveloped within the convection around UTC 27 September, and the circulation developed sufficient definition by UTC that day for the system to be considered a tropical depression when it was n mi east of the northern Leeward Islands.
Ophelia moved slowly northwestward over the next day or so, becoming a tropical storm again around UTC 28 September about n mi east of the northern Leeward Islands. Ophelia strengthened steadily as it turned northward and became a hurricane around UTC 29 September. It then reached major hurricane status when it was centered almost midway between the northern Leeward Islands and Bermuda. As Ophelia approached Bermuda, the eye became more distinct and deep convection gained symmetry.
The buoy reported a maximum 1-min wind of 84 kt with a gust to kt in the northern eyewall and a minimum pressure of It is estimated that Ophelia reached its peak intensity of kt around UTC 2 October, when it was located about n mi east-northeast of Bermuda.
The wind field associated with the major hurricane was compact, however, such that winds on Bermuda did not even reach tropical storm force. Ophelia accelerated north-northeastward after reaching its peak intensity and weakened rapidly when it encountered strong southwesterly shear and much cooler waters. Ophelia lost its tropical characteristics just before it made landfall over southern Newfoundland around UTC 3 October.
The extratropical low turned east-northeastward and weakened over the North Atlantic. An area of low pressure with deep organized convection formed around UTC 23 September as a tropical wave crossed the west coast of Africa.
The overall organization increased and a tropical depression formed at UTC 24 September about n mi south of the southernmost Cape Verde Islands. The depression strengthened to a tropical storm 6 h later. During the next few days, Philippe wobbled westward with slight fluctuations in intensity and became a kt hurricane at UTC 4 October about n mi northeast of the Leeward Islands.
The cyclone weakened to a tropical storm by UTC that day and made a slow but sharp turn toward the northwest and north over the western Atlantic on 5 October. The cyclone reintensified again and became a hurricane about n mi south-southeast of Bermuda at UTC 6 October, reaching its maximum intensity of 80 kt around UTC. Philippe began to weaken on 7 October and became an extratropical cyclone 12 h later when it merged with a cold front. A relatively low-latitude tropical wave left the west coast of Africa on 9 October and moved westward, accompanied by weak thunderstorm activity.
The wave moved through the Windward Islands four days later, with thunderstorms increasing at that time aided by a diffluent upper-level wind field. On 19 October, the wave showed some signs of additional organization, but easterly shear was too strong for tropical cyclone development.
A cold front entering the northwestern Caribbean Sea might have contributed some low-level vorticity to the system, but the wave appears to have been the main focus for genesis. Convection intensified near the wave axis on 21 October, which resulted in the formation of a nearly stationary broad surface low in the western Caribbean. The next day, surface observations indicated falling pressures in the area and a better-defined low-level circulation.
Thunderstorms increased markedly near and to the west of the center, and a tropical depression formed by UTC 23 October about 55 n mi north of Providencia Island, east of Nicaragua. A broad midlevel trough over the southeastern United States caused a weakness in a ridge near Florida and, as a result, the depression moved northward. The system became a tropical storm and then rapidly intensified over the deep warm waters of the western Caribbean, becoming a hurricane by UTC 24 October and a major hurricane 24 h later.
During that time, mid- to upper-level ridging rebuilt over the Gulf of Mexico, and the hurricane slowed down, gradually turning toward the west. Rina reached a peak intensity of kt and a minimum pressure of mb around UTC 26 October, when the tropical cyclone was n mi east-southeast of Chetumal, Mexico.
The conducive upper-level winds did not last very long, however, and Rina dropped below major hurricane strength 12 h later. Increasing southeasterly and southerly shear caused Rina to weaken further for the next couple of days. The cyclone moved generally toward the west-northwest and northwest on 26—27 October, becoming a tropical storm near UTC 27 October about 75 n mi south-southeast of Tulum, Mexico.
Rina turned northward and strong southerly shear caused additional weakening. The tropical storm made landfall near Paamul, Mexico, about 10 n mi southwest of Playa del Carmen, with an intensity of 50 kt near UTC 28 October. The center of Rina remained over land for about 9 h before emerging into the Yucatan Channel.
Strong southerly shear caused all convection near the center to dissipate, and Rina degenerated into a remnant low in the Yucatan Channel by UTC 28 October. The remnant low moved toward the east-northeast and east within the low-level flow ahead of a cold front, and dissipated early the next day just southeast of the western tip of Cuba. The origin of Sean from an extratropical low was unusual but not unprecedented.
On 3 November, a low pressure system formed along a frontal zone over the central United States and moved off the U. Earlier, this frontal system produced heavy snow in Colorado. The extratropical low became nearly stationary between Bermuda and the Bahamas during 6—7 November, after it separated from an eastward-moving midlatitude frontal trough.
Cloudiness and showers gradually increased around the low while a surface circulation became better defined by UTC 6 November, with a large field of tropical storm—force winds to the east of the center. Over the next 36 h, both the distribution of the wind field and convection became more symmetric, and it is estimated that a subtropical storm formed at UTC 8 November about n mi southwest of Bermuda.
At this time, the surface center was collocated with an upper-level low that developed in the same area; hence, the subtropical classification. Sean moved erratically and quickly transitioned into a tropical storm by UTC that day when the cyclone separated from the upper-level low, the convection became concentrated near the center, and the system developed upper-level outflow.
Sean gradually intensified within an environment of light to moderate vertical wind shear. A weak midlevel ridge of high pressure to the northeast of the cyclone forced Sean to move slowly west-northwestward and then northward for the next 24—36 h.
During that time, Sean intensified a little more when a ring of convection developed around an eyelike feature, and the cyclone reached its peak intensity of 55 kt with a mb minimum pressure at UTC 10 November. By then, Sean had turned toward the north-northeast ahead of an approaching trough and accelerated.
An increase in shear induced by the approaching trough, along with cooler waters, resulted in Sean's weakening early on 11 November. The center of Sean passed about 75 n mi to the west-northwest of Bermuda at UTC 11 November while the circulation was becoming elongated ahead of the frontal system.
By UTC 12 November, Sean lost its tropical characteristics, and it dissipated 24 h later when it merged with a cold front in the northeastern Atlantic.
The Marine Operations Center in Bermuda reported sustained surface winds of 37 kt and a wind gust to 54 kt near UTC 11 November as the center of Sean passed close to the island. Although visible satellite imagery showed an eyelike feature during most of the day on 9 November, which is typical of cyclones of hurricane intensity, the surrounding convection was not strong enough to classify the system as a hurricane using the Dvorak technique.
A lower intensity estimate was also supported by data from a concurrent reconnaissance aircraft flight, which reported maximum surface winds of only 52 kt. A well-defined tropical wave crossed the west coast of Africa on 22 August and continued westward across the tropical Atlantic. By UTC 25 August the deep convection became organized into curved bands, indicating the formation of a tropical depression about n mi west-southwest of the southernmost Cape Verde Islands.
The tropical cyclone was best organized right around the time of genesis and was closest to becoming a tropical storm at that time.
Thereafter, moderate to strong northeasterly shear prevented the system from strengthening as it moved west-northwestward.
By UTC 27 August, practically all of the associated thunderstorms vanished and the low-level circulation opened up into a northeast—southwest-oriented trough. The system dissipated over the far eastern tropical Atlantic. For all operationally designated tropical or subtropical cyclones in the Atlantic and eastern North Pacific basins, the NHC issues an official forecast of the cyclone's center location and maximum 1-min surface wind speed.
Forecasts are issued every 6 h, and contain projections valid at 12, 24, 36, 48, 72, 96, and h after the forecast's nominal initial time , , , or UTC. A forecast is included in the verification only if the system is classified in the final best track as a tropical or subtropical 3 cyclone at both the forecast's initial time and at the projection's valid time.
All other stages of development [e. Track forecast error is defined as the great-circle distance between a cyclone's forecast position and the best-track position at the forecast verification time, while track forecast skill represents a normalization of forecast error against some standard or baseline, and is positive when the forecast error is smaller than the error from the baseline.
To assess the degree of skill in a set of track forecasts, the track forecast error can be compared with the error from Climatology and Persistence, version 5 CLIPER5 , a climatology and persistence model that contains no information about the current state of the atmosphere Neumann ; Aberson If CLIPER5 errors are unusually low during a given season, for example, it indicates that the year's storms were inherently easier to forecast than normal, or otherwise unusually well behaved.
Table 2 presents the results of the NHC official track forecast verification for the season, along with results averaged for the previous 5-yr period, — In , the NHC issued Atlantic basin tropical cyclone forecasts, 6 a number well above the average over the previous 5 years Mean track errors ranged from 28 n mi at 12 h to n mi at h.
It is seen that mean official track forecast errors in were smaller than the previous 5-yr mean at all forecast times except h. In addition, the official track forecast errors set a record for accuracy at the , , , and h forecast times.
Vector biases were consistently north-northwestward in i. An examination of the track errors shows that the biases were primarily along track and fast, but there was a cross-track bias as well. Homogenous comparison of official and CLIPER5 track forecast errors in the Atlantic basin for the season for all tropical cyclones. Averages for the previous 5-yr period are shown for comparison.
Forecast intensity error is defined as the absolute value of the difference between the forecast and best-track intensity at the forecast verifying time. Mean forecast errors in ranged from about 6 kt at 12 h to about 17 kt at 72 and h.
Official forecasts had little bias in DSHIFOR5 errors were also below their 5-yr means at all forecast times, indicating the season's storms were easier than normal to forecast.
There has been virtually no net change in error over the past 15—20 years, although forecasts during the current decade, on average, have been more skillful than those from the previous one. A hurricane or tropical storm warning is a notice that 1-min sustained winds of hurricane or tropical storm force are expected within a specified coastal area within the next 36 h. Table 4 shows the watch and warning lead times for cyclones that affected or had the potential to affect the United States in Because observations are generally inadequate to determine when hurricane or tropical storm conditions first reach the coastline, lead time is defined here as the time between the issuance of the watch or warning and the time of landfall or the closest point of approach of the cyclone center to the coastline.
This definition will usually result in an overestimation of lead times for preparedness actions, particularly for hurricanes, since tropical storm conditions can arrive several hours prior to the onset of hurricane conditions.
Watch and warning lead times defined as the time between the issuance of the watch or warning and the time of landfall or closest approach of the center to the coastline for tropical cyclones affecting the United States in If multiple watch or warning types TS or H were issued, the type corresponding to the most severe conditions experienced over land is given.
Much of the local impact information contained in the individual storm summaries was provided by the meteorological services of the affected countries. These reports contain storm information omitted here because of limitations of space, including additional surface observations and a forecast and warning critique. The nominal initial time represents the beginning of the forecast process. The actual advisory package is not released until 3 h after the nominal initial time i. Possible classifications in the best track are as follows: tropical depression, tropical storm, hurricane, subtropical depression, subtropical storm, extratropical, disturbance, wave, and low.
Special advisories are issued whenever an unexpected significant change has occurred or when watches or warnings are to be issued between regularly scheduled advisories. The treatment of special advisories in forecast databases changed in to the current practice of retaining and verifying the original advisory forecast. This count does not include forecasts issued for systems later classified to have been something other than a tropical cyclone at the forecast time.
NHC extended its watch and warning lead times by 12 h starting in the season, such that a hurricane or tropical storm warning signifies that 1-min sustained tropical storm—force winds are expected to begin within the next 36 h.
A watch now means those conditions are possible within the next 48 h. Sign in Sign up. Advanced Search Help. Monthly Weather Review. Sections Abstract 1. Introduction 2. Individual storm summaries a. Tropical Storm Arlene, 28 June—1 July b. Tropical Storm Bret, 17—22 July c. Tropical Storm Cindy, 20—22 July d. Thus far in the hurricane season, Hurricanes Emily and Irene have had the greatest impact in their trajectories through the Caribbean and United States.
Hurricane Irene affected various islands of the Caribbean causing severe flooding in the Bahamas, Turks and Caicos Islands, and along the east coast of the United States.
A specialist in dengue and another in vector control assisted in these activities. National Actions. CDEMA has also been working with Sub-regional Focal Point, Jamaica who is the lead for the North-western sub-region to advance arrangements for launching any support if necessary. Regional Response Mechanism. News Centre.
0コメント