Civicane49's WunderBlog

Barbara heading to southern Mexico; 91E over the Pacific

By: Civicane49, 6:11 AM GMT on May 29, 2013

Tropical Storm Barbara has formed and is approaching to the Mexican coast along the Gulf of Tehuantepec. With the development of this second named storm, this year is the second consecutive year for the eastern Pacific to feature two named storms in the month of May. In addition, this year is tied with 2012, 2007, 1984, and 1956 for featuring the most named storms in the eastern Pacific on May. According to the latest National Hurricane Center advisory, Barbara has winds of 50 mph and a minimum pressure of 1000 mb. It is moving slowly moving northeastward at 3 mph and is centered about 120 miles south-southwest of Salina Cruz, Mexico. The structure of Barbara is continuing to improve considerably with a more symmetric appearance, organized spiral bands around it, and a good central dense overcast (CDO) on satellite images. The Puerto Angel radar currently depicts part of the cyclone’s southern eyewall.

Forecast for Barbara
Barbara should continue to intensify before making landfall in the Mexican coast. The tropical cyclone is embedded in a highly conducive environment with very warm sea surface temperatures of near 30°C, low wind shear of 5 to 10 knots, and the relative humidity value of 70%, which is pretty moist. So, there is no reason why the system should not continue to strengthen further. Given its rather small inner core, the current structure of the storm, and the aforementioned conditions, the cyclone should intensify in a rather quick pace and reach as a high-end tropical storm before making landfall roughly in the next 18 hours; in fact, the SHIPS model gave a 71% chance of a 25 knot increase within 24 hours. However, the cyclone has very limited time to strengthen, so I have some doubts that it will briefly become a hurricane. But it is possible. After it moves over land, it will weaken rapidly and later dissipate over the mountainous terrain of Mexico.

Barbara will continue to move slowly north-northeastward through a split in the mid-level ridge. As the trough deepens over the southern United States, it should increase its forward speed by tomorrow or so. The system is expected to make landfall on the Mexican coast along the Gulf of Tehuantepec by 18 hours. It will continue to move north-northwestward through Mexico and whatever is left of it could move into the Bay of Campeche. The biggest threat of this storm is the heavy rain. Since the cyclone will move in a rather slow pace and interacting with the mountainous terrain, the heavy rain would result in life-threatening flash floods and mudslides to parts of southern Mexico and Guatemala. Interests in this area should remain monitoring the progress of this tropical storm.


Figure 1. Water vapor imagery of Tropical Storm Barbara. Image credit: Mauna Kea Weather Center (MKWC).

Invest 91E becoming better organized
A persistent area of low pressure (Invest 91E) located about 850 miles south-southwest of the southern tip of Baja California has become better organized than it was yesterday. The cloud pattern has slightly improved and the low-level center became better defined on the recent scatterometer pass. Nonetheless, the system remains fairly disorganized; satellite loop shows a moderate easterly shear continuing to shift the convection away from the partially exposed low-level center.

Forecast for 91E
Further development of 91E appears to be possible as conditions will remain marginally favorable to support it in the next several days. The shear is expected to gradually lessen over the system during the next few days, which should become less of a problem for it to develop. However, the large area of dry air to the north of the low would limit convective activity for the system and disrupt its organization. By 48 hours, the system is forecast to cross into cool sea surface temperature of below 26.5°C threshold needed for tropical cyclones. The system will likely dissipate by days four or five within unfavorable conditions combined with dry airmass and cool waters. All things considered, I give this system a 40% chance of becoming a tropical cyclone in the next 48 hours. 91E is anticipated to move slowly north or north-northeastward in the next several days as the mid-latitude trough amplifies over the southern United States. The system is unlikely to be a significant threat to land.


Figure 2. Evening infrared satellite image of Invest 91E. Image credit: NOAA/RAMMB.

Elsewhere in the tropics
Although no global models are forecasting tropical cyclone development in the Atlantic, the GFS/ECMWF/CMC ensembles have been consistent in predicting the lowering pressures across much of the western Atlantic in early June. In addition, shear is forecast to decrease gradually across the Caribbean by next week, allowing any development to occur. The upward Madden Julian Oscillation (MJO) pulse is moving into the western Atlantic and would remain in that region until early June. The upward MJO pulse helps enhance convection and lower pressure across much of the western Atlantic as seen on water vapor imagery, showing a lot of moisture in this area. Development remains a possibility there.

Civicane49

Hurricane Flood

Updated: 7:18 AM GMT on May 29, 2013

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92E nearly a tropical depression; possible development over Caribbean in June

By: Civicane49, 8:56 PM GMT on May 27, 2013

A well-defined area of low pressure (Invest 92E) located a couple of hundred miles south-southwest of the Gulf of Tehuantepec has become better organized and is on its way of becoming a tropical depression. Satellite intensity estimates from both SAB and TAFB were T1.5/30 mph. The system features a well-organized cloud pattern with organized thunderstorm activity, good outflow pattern, and good spiral bands mainly in the southern semicircle on visible satellite imagery. However, satellite imagery suggests that the low-level center is not very well-defined yet and lacks sufficient convection over it during the past several hours. In addition, it remains embedded along the monsoon trough, which would cause development slow to occur. Nevertheless, it appears that the system is in the process of detaching itself and is improving its low-level center.

Forecast for 92E
I foresee 92E becoming a tropical depression by tomorrow or so if current trends continue. Situating in an extremely conducive environment with very warm sea surface temperatures, low to nonexistent wind shear, moist atmospheric environment, and good outflow pattern, there is no reason why the system should not continue to organize and become a tropical cyclone in the near future. Although, the low-level center is not very well organized yet, it should improve in the next several hours. While the system remains attached to the monsoon trough, it is in the process of detaching itself; once it detaches, it should quickly organize and become a tropical cyclone. I feel that the system should attain at least moderate tropical storm intensity. Nearly all of the statistical and dynamical models are in a good agreement that 92E will attain moderate tropical storm intensity before landfall. Though, there is a slight chance of becoming a minimal hurricane, given the very favorable conditions ahead. Although the National Hurricane Center (NHC) gave the low an 80% chance of becoming a tropical cyclone in the next 48 hours, I believe the odds must be higher and give it a 90% chance. 92E should continue to move slowly northwestward. Then by tomorrow or Wednesday, the system should begin to move northward and make landfall on the Mexican coast near Puerto Angel on Thursday as depicted by the models. The system would bring strong winds and very heavy rain, leading to dangerous flash floods and mudslides, to that area. HWRF model foresees copious amounts of rainfall in that region. Interests along that area should monitor the progress of the low.


Figure 1. Afternoon visible satellite image of Invest 92E. Image credit: Mauna Kea Weather Center (MKWC).

Invest 91E remains disorganized
A weak area of low pressure (Invest 91E) located about 700 miles southwest of Manzanillo, Mexico remains poorly-organized. This system has not changed much in organization today as convection remains limited and disorganized on satellite images. Further development of 91E appears unlikely to occur as conditions will slowly become more hostile for development in the coming days. The shear is expected to gradually increase over the system by day three, which should prevent further organization. Moreover, dry air to the north of the low would limit convective activity. Thus, I give this system a 10% chance of becoming a tropical cyclone in the next 48 hours. 91E is anticipated to move slowly westward over the eastern Pacific before moving to the east and being absorbed by the secondary low.


Figure 2. Afternoon infrared satellite image of Invest 91E. Image credit: NOAA/RAMMB.

Potential development over northwestern Caribbean on early June
The GFS ensembles and other models have been consistent in showing the lowering pressures across much of the western Atlantic in the first week of June. The upward Madden Julian Oscillation (MJO) pulse is currently in the eastern Pacific and is beginning to move into the western Atlantic and would remain in that region until early June. The upward MJO pulse will help enhance convection across much of the western Atlantic. In addition, shear is forecast to decrease gradually across the Caribbean by early June, allowing any development to occur. Although it remains highly uncertain that we will see a tropical cyclone developing out of this, development is still not out of the question yet.

Civicane49

Hurricane Flood

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91E and 92E over the Pacific; long-range development possible over the Caribbean

By: Civicane49, 9:19 AM GMT on May 27, 2013

A weak area of low pressure (Invest 91E) that has persisted over the eastern Pacific in the past few days is currently located about 600 miles southwest of Manzanillo, Mexico. This system has not changed much in organization today as convection remains disorganized on satellite images. The latest surface analysis show 91E remaining embedded along the monsoon trough/Intertropical Convergence Zone (ITCZ). The system’s interaction with it will make it difficult to become a tropical cyclone. Moderate easterly shear is also affecting the system and has shifted the small area of deep convection away from a defined low-level center, which is now exposed.

Forecast for 91E
Further development of 91E is slim as conditions will slowly become more hostile for development in the coming days. In fact, the SHIPS model is anticipating the easterly shear to increase over 91E by day three. The attachment with the monsoon trough/ITCZ makes it hard for the low to develop and should remain embedded in the next few days. In addition, dry air to the north of the disturbance would intrude into the system and cause limited convective activity. I give this system a 10% chance of becoming a tropical cyclone in the next 48 hours. 91E is anticipated to move slowly westward over the eastern Pacific in the next several days before moving to the east and being absorbed by the secondary system.


Figure 1. Morning infrared satellite image of Invest 91E located southwest of the Mexican coast. Image credit: Mauna Kea Weather Center (MKWC).

Invest 92E continuing to organize
Another area of low pressure (Invest 92E) located south of the Gulf of Tehuantepec is continuing to show signs of organization; deep convection has maintained over the past several hours as the system continues to consolidate and moves west-northwestward. The low-level center of the system is currently beneath the main area of deep convection. Satellite imagery and surface analysis indicate that the system remains embedded along the monsoon trough. The system’s interaction with it would make development slow to occur as the low must gather strength and organization to break free from it and can then become a tropical cyclone. However, it is in the process of detaching itself as the system is gaining some latitude over the past several hours.

Forecast for 92E
I foresee 92E continuing to organize in the next couple of days and become a tropical depression by Tuesday or so. Situating in an extremely conducive environment with very warm sea surface temperatures, low vertical wind shear, moist atmospheric environment, and good outflow pattern, I see no reason why the system should not continue to organize and become a tropical cyclone in the next couple of days. Although the system remains embedded along the monsoon trough, it appears to be in the process of detaching itself. Once it separates, it will likely organize quickly. The system should become a tropical depression by the next day or two and attain at least tropical storm intensity. Though, there is a chance of it becoming a minimal hurricane, given the very favorable conditions ahead and its small size. I give 92E a 70% chance of developing into a tropical cyclone by the next 48 hours. 92E should continue to move west-northwestward and later northwestward. Then by Tuesday or Wednesday, the system should begin to move northward and make landfall on the Mexican coast near Puerto Angel around Thursday as depicted by the models. The system would bring strong winds and heavy rain, leading to life-threatening floods and mudslides, to that area. Interests along that area should monitor the progress of the low.


Figure 2. Water vapor imagery of Invest 92E. Image credit: Mauna Kea Weather Center (MKWC).

Potential development over northwestern Caribbean on early June
The GFS ensembles and other models have been consistent in showing the lowering pressures across much of the western Atlantic in the first few days of June. The upward Madden Julian Oscillation (MJO) pulse is currently in the eastern Pacific and is beginning to move into the western Atlantic and would remain in that region until early June. The upward MJO pulse will help enhance convection across much of the western Atlantic. In addition, shear is forecast to decrease gradually across the Caribbean by early June, allowing any development to occur. Although it is too early to tell that we will have a tropical cyclone developing out of this, development is still not out of the question yet.

Civicane49

Hurricane

Updated: 10:19 AM GMT on May 27, 2013

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Tropical disturbances in the East Pacific; potential development in the Caribbean

By: Civicane49, 2:33 AM GMT on May 25, 2013

There are two tropical disturbances in the eastern Pacific today. One is Invest 91E located several hundred miles south of the Pacific coast of Mexico. The other one is the low pressure system located roughly 150 miles southwest of the coast of Costa Rica. This should be tagged as “Invest 92E” soon. Both of these systems are producing disorganized showers and thunderstorms on the latest satellite imagery. While two systems remain poorly-organized, I believe that the Costa Rica disturbance will stand a better chance of becoming the second tropical storm of the season.

Forecast for the Pacific disturbances
91E is not expected to organize significantly as it would continue to interact with the monsoon trough. I give this system a 10% chance of becoming a tropical cyclone in the next 48 hours. The system should move slowly in weak steering currents. The Costa Rica disturbance should continue to organize gradually in the next several days as it is expected to remain in favorable environmental conditions. It should become a tropical cyclone by Tuesday or so, and I give this disturbance a 20% chance of developing into a tropical cyclone in the next 48 hours. The system is predicted to move westward and then move west-northwestward as it will be steered along the southern periphery of the high pressure ridge over the Gulf of Mexico. The system would then move northward to the Mexican coast as the trough will amplify over the western United States by four or five days. The disturbance would bring a threat for heavy rains and strong winds for parts of the Mexican coast by next week.


Figure 1. Evening infrared satellite image of Invest 91E and the tropical disturbance near Costa Rica. Image credit: Mauna Kea Weather Center (MKWC).

Possible development in the western Caribbean on early June
The GFS as well as its ensembles are continuing to show a large area of low pressure developing over the northwestern Caribbean in few days after hurricane season starts in the Atlantic, which is June 1. The upward Madden Julian Oscillation (MJO) pulse is currently in the eastern Pacific and should move into the western Atlantic soon and would remain in that area until early June. The upward MJO pulse will help enhance convection across much of the western Atlantic. In addition, shear is forecast to decrease gradually across the Caribbean by early June, allowing development to occur. The models are depicting this system to move northward and affect the western Caribbean islands and the southeastern United States, especially Florida. Although high uncertainty remains for tropical cyclone formation, development is still not out of the question yet.

Civicane49

Hurricane

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Invest 91E remains disorganized in the Pacific

By: Civicane49, 12:41 PM GMT on May 24, 2013

An area of low pressure (Invest 91E) centered about 550 miles south-southwest of Acapulco, Mexico remains disorganized. Shower and thunderstorm activity remains very limited and disorganized as seen on satellite imagery. The latest ASCAT pass revealed an ill-defined low-level center, which is exposed on satellite images. Although water temperatures and upper-level winds remain favorable for development, the system’s interaction with the monsoon trough would disrupt further organization.

Forecast for 91E
Despite its disorganized state, 91E has a potential to develop. Conditions appear to remain quite favorable for gradual development. It will be traveling over sea surface temperatures greater than 26.5°C threshold needed for tropical cyclone formation. Vertical wind shear is forecast to remain light over the system in the next several days. The main inhibitors I see for this system is the interaction with the monsoon trough as well as some dry air around it. All things considered, I give it a 30% chance of becoming a tropical cyclone in the next 48 hours. 91E should continue to move westward over the next several days as it will be steered along the southern periphery of the high pressure ridge over the Gulf of Mexico. The system could then move slightly poleward as the trough is forecast to amplify over the western United States by four to five days. 91E is highly unlikely to threaten land.


Figure 1. Morning infrared satellite image of Invest 91E. Image credit: NOAA/RAMMB.

Elsewhere in the tropics
There is an area of disturbed weather associated with the remains of the tropical wave located just off to the west of Costa Rica. Global models have been consistent in showing it becoming a tropical cyclone situating south of Mexico by next week. However, landfall is a possibility for the Mexican coast. The disturbance is expected to move westward and then west-northwestward in favorable conditions for development.

Civicane49

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Alvin weakening, may become post-tropical cyclone sooner than expected

By: Civicane49, 4:43 AM GMT on May 17, 2013

East Pacific’s Tropical Storm Alvin is weakening. The combination of strong west-southwesterly shear and interaction of the monsoon trough has disrupted the cyclone from organizing further. The latest National Hurricane Center (NHC) advisory stated that Alvin is barely a tropical storm with winds of 40 mph and central pressure of 1006 mb. Satellite images depict a poorly organized tropical storm with a disorganized cloud pattern. Satellite imagery also shows a cyclone interacting with the monsoon trough. The storm appears to be in the process of becoming a post-tropical cyclone or an open trough. In fact, the latest ASCAT pass suggests that the surface center has become an open circulation. If it remains that way for several hours, the NHC will likely end the advisories of this cyclone. (One of the requirements of a tropical cyclone is that it must have a closed surface circulation center).


Figure 1. Evening infrared satellite image of Tropical Storm Alvin. Image credit: NOAA/RAMMB.

Forecast for Alvin
Alvin should continue to meet its demise. An upper-level trough located just off of the western coast of Baja California has resulted strong west-southwesterly shear of 20 knots over the storm, and the shear is not expected to abate significantly in the next few days. In addition, the interaction of the monsoon trough will keep Alvin from organizing further but rather weakening it. Thus, I expect additional weakening of the storm before degenerating into an open trough by 72 hours. Though, I would not be surprised to see Alvin becoming an open trough sooner than the NHC expected. The system is currently moving west-northwestward and should remain in this motion for couple of days under the influence of a mid-level ridge over southwestern Mexico. Global models forecast the low-level and mid-level centers of the cyclone to split when the storm will degenerate. The low-level center is predicted to move westward within the easterly flow, while the mid-level center is expected to shift poleward toward the trough. Alvin is not anticipated to threaten any land masses.

Civicane49

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First East Pacific Invest (90E) has a potential to develop

By: Civicane49, 4:54 AM GMT on May 14, 2013

The first invest of the year in the eastern Pacific is here and has a chance to become the first tropical depression of the East Pacific hurricane season, which the official start will be on this Wednesday. Earlier today, the National Hurricane Center (NHC) has designated an area of low pressure in the far eastern Pacific; the NHC tagged it as “Invest 90E”. (For those unfamiliar with the term “Invest”, the information can be found on the Hurricane FAQ). Satellite imagery reveals that the overall shower and thunderstorm activity has somewhat diminished over the past few hours. Judging by the satellite images, the system appears to have no issues with dry air intrusions or the vertical wind shear.


Figure 1. Evening infrared satellite image of Invest 90E taken on May 14, 2013 at 0345 UTC. Image credit: Mauna Kea Weather Center (MKWC).

Forecast for 90E
90E appears to have an opportunity to develop in the next several days. Many global models are predicting this system to become a tropical cyclone by later this week. 90E will be transversing over warm sea surface temperatures over the 26°C threshold needed for tropical cyclone formation. Vertical wind shear appears to be rather conducive over the next 72 hours as models are predicting it to be low until in days 4 and 5. There is an uncertainty in intensity forecast, but it looks like the system would at least attain tropical storm intensity. Given the favorable conditions ahead, I expect a steady organization of the disturbance in the next few days and giving it a 20% chance of becoming a tropical cyclone in the next 48 hours. 90E is anticipated to move slowly westward and then west-northwestward across the Pacific Ocean during the next few days. The system poses no threat to any land areas.

Civicane49

Hurricane

Updated: 5:03 AM GMT on May 14, 2013

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