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99L likely to develop over the Caribbean; 90L over the Atlantic
By: Civicane49, 2:02 AM GMT on October 21, 2012
A low pressure system associated with a tropical wave is over the central Caribbean Sea, well south of Haiti. It has been classified as Invest 99L. Recent satellite image reveals that the disturbance has an appearance of a developing tropical cyclone. 99L has a well-organized cloud structure; however, it is lacking deep thunderstorm activity in the center due to diurnal minimum. Nevertheless, diurnal maximum and favorable conditions should allow it to increase by early tomorrow. Surface observations near the system report decreasing surface pressures. Moreover, satellite and surface data are also indicating that a surface circulation is becoming better defined. UW-CIMSS analysis depicts that wind shear is low and an upper-level anticyclone develops over the tropical disturbance. 99L will likely become a tropical cyclone by the next day or sooner. Reconnaissance aircraft is scheduled to investigate this system tomorrow to obtain detailed information of the tropical disturbance.
Figure 1. Evening infrared satellite image of Invest 99L. Image credit: NOAA/RAMMB.
Forecast for 99L
99L is expected to become a tropical cyclone by tomorrow or so. There are many model supports for further development. Environmental conditions are expected to remain very favorable for 99L over the next several days. The system is forecasted to remain over warm sea surface temperatures and high Tropical Cyclone Heat Potential (TCHP) values. Wind shear is forecasted to remain in low to moderate range through 72 hours. The atmospheric environment is forecasted to remain moist over the next several days. Given the fact that 99L will be in very favorable conditions, I would not be surprised if the system eventually becomes a hurricane. Based on the current trends, I give this system a 70% chance of becoming a tropical cyclone in the next two days. The system is anticipated to move westward slowly over the next couple of days. Thereafter, the system may meander over the Caribbean Sea for few days before a strong trough of low pressure allows it to turn northward over Cuba and the Bahamas. However, there is some uncertainty of the forecast path of 99L in several days and beyond.
Interests in Hispaniola, Jamaica, the Cayman Islands, Cuba, and the Bahamas should monitor the system very closely over the next several days as it is forecasted to bring some very heavy rain and gusty winds. These heavy rains could produce deadly floods and mudslides.
Figure 2. Latest Tropical Cyclone Heat Potential (TCHP) in the Caribbean Sea. Notice that red colors represent areas of extremely high TCHP, which indicates that warm waters extend with great depth in the ocean. These features are usually beneficial for tropical cyclones to rapidly strengthen. Image credit: NOAA/AOML.
90L over the Atlantic
Over the open Atlantic, there is another tropical wave situating about 1000 miles east-northeast of the northernmost Lesser Antilles. The system has been classified as Invest 90L. The wave is associated with an upper-level low, which is slowing development of 90L. Latest satellite image depicts that shower and thunderstorm activity has diminished. 90L is forecasted to move northwestward over the next few days and later turn northward and eventually northeastward. It is not anticipated to threaten any land areas. Environmental conditions are forecasted to become slightly more favorable for further development. Although wind shear is currently high over 20 knots, it is forecasted to decrease below 20 knots through 48 hours before increasing again. Sea surface temperatures are expected to remain warm. However, many models are showing little to no development of the disturbance. I give this system a 30% chance of developing into a tropical or subtropical cyclone in the next 48 hours.
Figure 3. Evening infrared satellite image of Invest 90L. Image credit: NOAA/RAMMB.
Over the eastern Pacific, an area of disturbed weather is concentrated just south of the Gulf of Tehuantepec. Recent satellite image shows that it remains fairly disorganized. Environmental conditions appear relatively favorable for further development in the next few days. Some global models, including the CMC and the GFS, are forecasting it to develop into a tropical cyclone by the next four to five days. I give this system a 10% chance of becoming a tropical cyclone in the next two days. The system is forecasted to move westward over the next several days before recurving towards Mexico. The remnants of it are forecasted to move into the Gulf of Mexico. At this time, it is unknown that it will redevelop over the Gulf.
Updated: 4:03 AM GMT on October 21, 2012
TD 15-E forms; 97L a little threat to develop
By: Civicane49, 7:12 PM GMT on October 06, 2012
Tropical Depression Fifteen-E has formed earlier today after maintaining sufficient organization. Recent satellite image and microwave data reveal that the incipient depression is well-organized with an eye-like feature, organized deep convection, and good spiral bands. These indicate that the cyclone is intensifying. I expect this system to become Tropical Storm Olivia later today if current organization continues. As of the latest National Hurricane Center (NHC) advisory, the tropical depression has maximum sustained winds of 35 mph and minimum central pressure of 1006 mb. The system is situated roughly 845 miles southwest of the southern tip of Baja California. It is moving west at 10 mph.
Forecast for 15-E
The depression will have a limited time to strengthen before weakening in hostile conditions. Environmental conditions are currently relatively favorable for further intensification of the cyclone. Sea surface temperatures are expected to remain warm above 26°C through 48 hours. Wind shear is forecasted to remain light to moderate range through 48 hours. However, water vapor satellite imagery depicts a large area of dry air present to the north and west of the cyclone. Dry air may be a problem for the system to further strengthen. However, I believe the cyclone will intensify slowly over the next couple of days. After 48 hours, the system is anticipated to weaken gradually as it will enter into unfavorable conditions with cooler waters, higher shear, and drier airmass. Many models are forecasting the system to become a moderate tropical storm and shows slow weakening thereafter. The cyclone will likely dissipate by the next four days.
The tropical depression is forecasted to move slowly west-northwestward over the next few days. The subtropical ridge over the Pacific Ocean is anticipated to weaken. As a result, the depression would be in weak steering currents. The cyclone is not expected to threaten any land areas.
Figure 1. Visible satellite image of Tropical Depression Fifteen-E. Image credit: NOAA/RAMMB.
97L a little threat to develop
An elongated area of low pressure has been designated as Invest 97L earlier today. It is situated about 250 miles east of the southeastern Bahamas. Recent satellite image suggests that the disturbance is producing somewhat disorganized shower and thunderstorm activity. However, ASCAT pass reveals that the tropical disturbance has a low-level circulation. The disturbance is expected to move westward and then turn northeastward. The system is forecasted to remain over warm sea surface temperatures during the next several days. However, both moderate wind shear and some dry air may slow development. Many global models show little or no development of 97L. I give the tropical disturbance a 20% chance of becoming a tropical cyclone in the next 48 hours. Regardless of development, the system will bring some rain to parts of Bahamas during the next few days.
Figure 2. Infrared satellite image of Invest 97L. Image credit: NOAA/RAMMB.
The GFS model is predicting a tropical cyclone developing in the Caribbean Sea by the next fourteen days. The GFS model is also forecasting a tropical cyclone development to occur south of the Pacific coast of Mexico by the next eight days.
Updated: 8:09 PM GMT on October 06, 2012
96E has a potential to develop
By: Civicane49, 2:04 AM GMT on October 06, 2012
Invest 96E has suddenly become organized earlier today and is remained organized on recent satellite image. However, shower and thunderstorm activity has somewhat diminished, likely due to diurnal minimum and some dry air. 96E is situated about 750 miles south-southwest of the southern tip of Baja California. The system is moving west-northwestward at roughly 15 mph. The tropical disturbance is in an area of relatively favorable conditions, and it should continue to organize.
Forecast for 96E
96E appears to have a chance to develop before encountering hostile conditions. The SHIPS model shows that the system is forecasted to remain in relatively favorable conditions over the next 48 hours with warm sea surface temperature and low to moderate wind shear. UW-CIMSS analysis shows that an anticyclone is building over 96E. However, water vapor satellite loop depicts that the large area of dry air is present to the north and west of the disturbance. Dry air may hinder some further development of 96E. Therefore, I expect slow development of 96E over the next couple of days. After 48 hours, however, 96E is anticipated to enter into unfavorable conditions with cool sea surface temperatures, high wind shear, and more stable airmass. Weakening should be gradual. Many models are forecasting little or no development of 96E. I give this system a 60% chance of developing into a tropical cyclone in the next 48 hours. 96E is forecasted to move generally west-northwestward over the next several days by the high pressure ridge over the Pacific Ocean. 96E is highly unlikely to threaten any land areas.
Figure 1. Evening infrared satellite image of Invest 96E. Image credit: Mauna Kea Weather Center (MKWC).
Elsewhere in the tropics
None of the global models are forecasting tropical cyclone development in the Atlantic over the next seven days. However, the GFS model is forecasting a tropical cyclone developing over the Caribbean Sea by the next fourteen days. The month of October is a time when tropical cyclones develop closer to home in the Atlantic basin. In the eastern Pacific, the GFS model is predicting a possible development just south of the border of Guatemala and Mexico by the next six days.
Long-lived Nadine finally dissipates; Oscar remains a weak tropical storm
By: Civicane49, 11:10 PM GMT on October 04, 2012
Tenacious Tropical Storm Nadine has finally dissipated after lasting 21.75 days as a tropical or subtropical cyclone, which makes it the fifth longest-lived Atlantic tropical cyclone on record. The longest-lived Atlantic tropical cyclone was the San Ciriaco Hurricane of 1899, which lasted 28 days. Recent satellite image suggests that Nadine no longer has tropical characteristics. Nadine has affected the Azores Islands twice by bringing tropical storm conditions. Nadine is not forecasted to threaten any more land areas over the next several days.
Figure 1. 2km Natural Color Imagery of Hurricane Nadine at peak intensity with winds of 90 mph on September 30, 2012 at 1530 UTC. Image credit: NOAA/RAMMB.
Tropical Storm Oscar remains disorganized
Tropical Storm Oscar remains a highly sheared cyclone as seen on satellite images. The closed circulation remains exposed while the shower and thunderstorm activity remains to the east of the center due to strong wind shear. UW-CIMSS analysis reveals that the storm is affected by 20 knots of northwesterly shear. As of the latest National Hurricane Center (NHC) advisory, the cyclone has maximum sustained winds of 45 mph and minimum central pressure of 1000 mb. Oscar is situated about 1170 miles west-northwest of the Cape Verde Islands. The storm is moving northeastward at 15 mph. Oscar has formed yesterday, which makes it the fifteenth named storm of 2012 Atlantic season.
Forecast for Oscar
Oscar is forecasted to continue moving northeastward and accelerate as it becomes further embedded within the flow of a digging deep-layer low pressure trough over the Atlantic Ocean. The cyclone is not expected to be a significant threat to any land areas over the next several days. Many computer models are in excellent agreement with this forecast track. Little change in strength is anticipated for Oscar as strong vertical wind shear is forecasted to affect the cyclone in the next couple of days. Moreover, the storm is anticipated to enter into cooler sea surface temperatures, which are unfavorable for tropical cyclones. In the next 36 hours or so, Oscar is expected to be absorbed by the approaching cold front, which is attached to a large and powerful extratropical cyclone.
Figure 2. 2km Natural Color Imagery of Tropical Storm Oscar on October 4, 2012 at 1335 UTC. Notice that the surface circulation of Oscar is exposed while the shower and thunderstorm activity is pushed away from the center to the east due to high wind shear. Image credit: NOAA/RAMMB.
Elsewhere in the tropics
In the eastern Pacific, there is an area of low pressure located roughly 600 miles southwest of Manzanillo, Mexico. Latest satellite image depicts that the system is producing disorganized shower and thunderstorm activity. The disturbance is expected to move westward at about 15 mph, and it is not forecasted to develop due to unfavorable environmental conditions. I give this system a near 0% chance of becoming a tropical cyclone in the next 48 hours.
None of the global models are forecasting significant tropical cyclone development in the Atlantic over the next seven days. However, the GFS model forecasts possible tropical cyclone development well south of Guatemala’s Pacific coast beyond the next seven days.