Civicane49's WunderBlog

Newly formed Dalila a threat to southwestern Mexico

By: Civicane49, 11:04 AM GMT on June 30, 2013

The fourth tropical storm of the 2013 East Pacific season has arrived. Tropical Storm Dalila has formed several hundred miles south of the Mexican Pacific coast. As of the latest National Hurricane Center (NHC) advisory, Dalila has maximum sustained winds of 40 mph and minimum barometric pressure of 1003 mb. The tropical storm is moving northward at 10 mph. It is centered about 260 miles southwest of Acapulco, Mexico or 315 miles south-southeast of Manzanillo, Mexico. Satellite imagery reveals a small but well organized tropical storm with the main area of deep convection over the center. Dalila is in a region of favorable conditions, and this should allow the cyclone to continue strengthening.


Figure 1. Morning infrared satellite image of Tropical Storm Dalila. Image credit: NOAA/RAMMB.

Forecast for Dalila
Environmental conditions appear favorable for steady, if not rapid, intensification to occur. During the next 72 hours, sea surface temperatures are expected to remain well above the 26°C threshold required for tropical cyclones to strengthen. Additionally, both relatively light wind shear and moist airmass is expected during the next several days. Because of the cyclone’s small size, rapid intensification is likely to occur once the inner core is established, which I believe it will by the next 24 hours or so. Despite the favorable conditions, SHIPS model and most of the 6z intensity guidance are not very enthusiastic with the system as they show only modest strengthening without reaching hurricane strength. Nevertheless, I believe Dalila will reach its peak strength as a minimal hurricane by 2-3 days given the seemingly favorable environment anticipated. Beyond 72 hours, it will encounter unfavorable conditions with cool water, and this should allow the cyclone to steadily weaken.

Both the upper-level low to the northwest of Dalila and a mid to upper-level ridge to the east have steered the system northward over the past several hours, and the storm currently remains in this motion. However, this will change very shortly as the large ridge of high pressure situated over the western United States will soon begin to build. This should force the cyclone to move northwestward. As the ridge continues to build, a west-northwestward turn is expected by 48-60 hours, followed by a gradual westward turn. Track guidance in the 6z run is in a better agreement than in the previous run, and majority of the models are forecasting the system to remain offshore from the southwestern Mexican coast. Regardless of whether or not it makes landfall, heavy rains, gusty winds, and hazardous sea conditions are expected for southwestern Mexico. Due to the storm’s expected proximity to the southwestern Mexican coast, tropical storm watches and warnings have been issued by the Government of Mexico for portion of this region.

Elsewhere in the tropics
Elsewhere, no tropical cyclone development is anticipated during the next 48 hours. However, the GFS and CMC are forecasting yet another tropical storm developing behind Dalila in the eastern Pacific by next weekend.

Civicane49

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Updated: 11:22 AM GMT on June 30, 2013

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Cosme weakening over the cold Pacific waters

By: Civicane49, 3:22 AM GMT on June 27, 2013

Cosme continues on a weakening trend over cold waters. As of the latest National Hurricane Center (NHC) advisory, Cosme is a tropical storm with maximum sustained winds of 50 mph and minimum barometric pressure of 998 mb. It is located about 545 miles west-southwest of Cabo San Lucas in Mexico’s Baja California peninsula. The storm is moving in a west-northwest trajectory at 14 mph. Satellite loop depicts a decaying tropical cyclone with the convection slowly decreasing in response to cold sea surface temperatures below the 26°C threshold needed for tropical cyclones to sustain.


Figure 1. Funktop infrared satellite image of Tropical Storm Cosme taken in the evening. Image credit: NOAA's Satellite Services Division.

Forecast for Cosme
Cosme is situated in the southern periphery of a broad mid-level ridge. It should continue to move in a west-northwest course during the next 36 hours or so. From here on out, the system will move westward as it will be situated in a low-level easterly flow. Slight decrease in forward speed is likely by day four as the remnants of Cosme would be in a weakness in the ridge. Model guidance remains in a good agreement with this forecast track. Although Cosme will not be a significant threat to any landmasses, it will continue to bring large swells to the southwestern Pacific coast of Mexico and Baja California during the next day or two.

Additional weakening is expected as the decaying cyclone will continue to move over cold sea surface temperatures of 21°C to 22°C. Shear is unlikely to be an additional problem as models are expecting the shear to remain light to moderate. By 24 hours, Cosme will likely degenerate into a remnant low with void of convection, if not sooner. The system should remain as a remnant low with a decent circulation and little convective activity for few days until it reaches the central Pacific and dissipates as portrayed by the global models.

Civicane49

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Cosme strengthening, expected to become a hurricane by tomorrow

By: Civicane49, 2:50 AM GMT on June 25, 2013

Tropical Storm Cosme continues to organize and intensify steadily over the eastern Pacific. Satellite and microwave imagery depict a large but well-organized tropical storm. The deep convection is wrapping around the center, which is indicating that the eyewall is developing in its formative stage. That also indicates that the storm is close to becoming a hurricane. The eastern half of the eyewall is defined, but the other half remains open. As of the latest National Hurricane Center (NHC) advisory, Cosme had maximum sustained winds of 65 mph and minimum barometric pressure of 994 mb. It is moving towards the northwest at 14 mph. The cyclone is centered about 320 miles southwest of Manzanillo, Mexico.


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

Forecast for Cosme
Cosme is anticipated to remain in favorable conditions during the next 24 hours with warm ocean temperatures above 26.5°C, light to moderate shear at 5-15 knots, and moist environment with 700-500 mb relative humidity values around 80%. I have no doubts that the storm will continue to intensify and become a minimal hurricane by tomorrow morning. University of Wisconsin CIMSS analysis shows that an upper-level anticyclone remains over the system, which is helping to keep the shear light over Cosme. Models are predicting this anticyclone to remain in place for the next few days and this should keep the shear light over the tropical cyclone. After 24 hours, Cosme will enter into more hostile conditions with cooler waters and drier airmass. Rapid weakening is expected, and it should degenerate into a remnant low by late Friday.

The storm will continue to move northwestward in the next several hours before slowly turning towards the west-northwest as the mid-level ridge builds over northern Mexico and southwestern United States. By Friday, Cosme should turn westward within the east-west low-level flow as it weakens to a remnant low. Although Cosme will not make landfall as a tropical cyclone, the outer bands of the cyclone will bring some heavy rainfall to portions of southern Mexico. High waves and rip currents are also expected for the southern Mexican coast. By the middle of next week, the remnants of Cosme could bring enhanced shower activity over portions of Hawaii, mainly over the windward and mauka areas.

Civicane49

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Tropical Storm Cosme forms over the eastern Pacific

By: Civicane49, 11:33 AM GMT on June 24, 2013

Tropical Storm Cosme has formed over the eastern Pacific after gaining sufficient organization of a tropical storm. The ASCAT passes from several hours ago supports this intensity; they revealed tropical storm force winds on the southeastern quadrant. As of the latest National Hurricane Center (NHC) advisory, Cosme was centered roughly 435 miles south of Manzanillo, Mexico. Maximum sustained winds were estimated to be 40 mph and minimum barometric pressure was 1003 mb. It is moving northwest at 10 mph. Satellite imagery reveals a large, but well-organized tropical storm with a central dense overcast-like pattern over the southern portion of the center of circulation. In addition, the cyclone features prominent spiral bands in all sides.

Forecast for Cosme
The incipient tropical cyclone is within favorable conditions for further intensification. Very warm sea surface temperatures, light to moderate shear, and very moist environment will allow the storm to continue intensifying in the next 48 hours. CIMSS wind shear analysis shows that the anticyclone aloft is slightly displaced to the west, which resulted some northerly shear over the system and limited some convection over it. However, global models are expecting this upper-level anticyclone to strengthen and expand over the center and should allow the shear to decrease. The main inhibitor I see for this system is its unusually large size. This would slow any strengthening until it establishes a solid core, which would make intensification quite rapid and could achieve minimal hurricane status or Category 1 hurricane on the Saffir-Simpson hurricane wind scale. By 48-60 hours and beyond, Cosme will enter into unfavorable conditions with cooler waters below the 26.5°C threshold. Rapid weakening is anticipated and the cyclone should become a remnant low by Friday.

Cosme will continue to move in a northwest trajectory as it will remain south of the weakness in a ridge. By 48 hours, the ridge is forecast to build and should slowly turn the system towards the west-northwest. In 96 hours, Cosme should move westward as it will be a weak, shallow cyclone and embedded within the easterly low-level flow. This motion is expected to continue until the storm dissipates over the open Pacific Ocean. Model guidance is in a good agreement with that forecast. Although Cosme will not be a significant threat to any land as a tropical cyclone, rip currents and high waves are expected for the southern Mexican coast during the next few days. In addition, the cyclone’s outer bands would bring some heavy rainfall to portions of southern Mexico. Some of its remnants could bring a slight increase in showers over portions of Hawaii, especially on the windward and mauka spots.


Figure 1. Morning infrared satellite image of Tropical Storm Cosme.

Elsewhere in the tropics
Besides Cosme, there is a weak low pressure system designated as Invest 95E continuing to produce disorganized showers and thunderstorms. Development of this system is not expected due to its proximity to Tropical Storm Cosme to the east. In addition, moderate to high shear coming from the upper-level outflow of Cosme will continue to impede development. The NHC gave this system a 10% chance of development in the next 48 hours; however, I put the odds lower: near 0%. 95E or whatever the remains of it will eventually be absorbed by Cosme.

GFS and CMC has been consistent in hinting another tropical storm developing off the southern Mexican coast by next weekend, and it seems plausible since the upward MJO pulse will remain in that basin by that time.

Civicane49

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Tropical Storm Barry forms over the Bay of Campeche

By: Civicane49, 9:59 PM GMT on June 19, 2013

Tropical Storm Barry has strengthened from a tropical depression over the Bay of Campeche based on the data from the Air Force Hurricane Hunter plane. Barry poses a threat for heavy rains and significant flooding to portions of southern Mexico in the next couple of days. The latest National Hurricane Center (NHC) advisory stated that the tropical storm has maximum sustained winds of 40 mph and minimum barometric pressure of 1005 mb. It is moving slowly westward at 6 mph. Visible satellite loop reveals that the cloud pattern of the system continues to improve considerably; well-defined curved bands are developing around the storm as well as a nice, distinct outflow on the northern semicircle of the cyclone.

Forecast for Barry
Barry should continue to move slowly westward until dissipation under the influence of the weakness in a high pressure ridge to the north of the storm. Further strengthening is likely in the next 12 hours before the storm makes landfall near Veracruz, Mexico by early tomorrow morning. Rapid weakening is expected after the system moves inland. The center of circulation will become severely disrupted by the high terrain. Barry will dissipate over the Sierra Madre Mountains in Mexico by early Friday. Heavy rain will be the primary threat of this system; this would cause significant flooding over portions of southern Mexico, especially the state of Veracruz, during the next couple of days.


Figure 1. GOES East visible satellite image of Tropical Storm Barry in the afternoon. Image credit: NASA/MSFC.

Civicane49

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TD 2 bringing a threat for heavy rain; outlook for the remainder of June

By: Civicane49, 11:06 PM GMT on June 18, 2013

Tropical Depression Two continues to bring a threat for heavy rains and significant flooding to portions of northern Guatemala and eastern Mexico in the next couple of days; radar from Sabancuy, Mexico shows rain continuing to fall in those regions. The latest National Hurricane Center (NHC) advisory stated that the tropical depression has maximum sustained winds of 30 mph and minimum barometric pressure of 1007 mb. It is moving west-northwestward at 10 mph. Satellite presentation of the tropical depression has increasingly improved since this morning as the low-level center continues to tighten, and the convective bands are redeveloping to the north of the center. The northern portion of the circulation center is over the Bay of Campeche, and the entire center will be over that region in the next hour or so.


Figure 1. Evening visible satellite image of Tropical Depression Two. Image credit: Mauna Kea Weather Center (MKWC).

Forecast for Tropical Depression Two
West-northwestward motion is expected during the next 24 hours by the influence of a weak ridge over the Gulf of Mexico. Beyond 24 hours, the system should turn westward as it will move across the southern Bay of Campeche and Mexico. Although one of the statistical models is showing the system moving north-northwestward after emerging over the Bay of Campeche, it should be discounted as the aforementioned ridge should prevent it from moving that far northward. The system would make its second landfall near Veracruz, Mexico on Thursday morning and will shortly dissipate over the Sierra Madre Oriental mountain range in Mexico by later that day.

Some brief strengthening is expected once the system moves over the Bay of Campeche within the next hour or so. However, time remains the limiting factor of this system; the cyclone will have very limited time over warm waters to strengthen greatly. Though, if the system manages to stay offshore longer than anticipated, then it is possible to become a tropical storm. Regardless, the system will continue to bring very heavy rain to portions of Guatemala and eastern Mexico for the day or two. This would cause dangerous floods over those regions.

Outlook for the remainder of June
Aside from Tropical Depression Two, no tropical cyclone development is anticipated in the next 48 hours for both the Atlantic and the eastern Pacific. After the tropical depression dissipates, the Atlantic basin will become quiet for the remainder of June as no global models are forecasting any significant tropical cyclone development later this month. The eastern Pacific is a different story, however. Global models, including the GFS, ECMWF, and CMC have been consistent in developing a tropical cyclone over the eastern Pacific by the final week of this month. Track and intensity will not be a concern for now as it remains in a long-range forecast. As we get closer, then we will have a better idea of what will likely occur. The upward Madden-Julian oscillation (MJO) is forecast to reach the Atlantic basin by the start of July and will increase convective activity across that basin. This would also increase the chances of tropical cyclone development and we should keep an eye on that.

Civicane49

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Tropical Depression Two bringing heavy rainfall to Central America and Mexico

By: Civicane49, 9:55 AM GMT on June 18, 2013

Tropical Depression Two continues to bring the threat for heavy rains and significant flooding to portions of Central America and eastern Mexico; radars from both Belize and Mexico show rain continuing to fall in those regions. The tropical depression has formed yesterday just off the northern coast of Honduras and made its first landfall near Dangriga Town, Belize. The latest National Hurricane Center (NHC) advisory stated that the tropical depression has maximum sustained winds of 30 mph and minimum barometric pressure of 1009 mb. Satellite loop reveals that the cloud structure of the cyclone remains disorganized with little thunderstorm activity and shows the system moving slower than earlier at west-northwestward.


Figure 1. Morning infrared satellite image of Tropical Depression Two. Image credit: NOAA/RAMMB.

Forecast for Tropical Depression Two
The tropical depression will continue to be steered west-northwestward at a rather slow pace in the next 24 – 36 hours under the influence of a weak ridge over the Gulf of Mexico. Beyond 36 hours, it is expected to turn westward and slow its forward speed as it will move across the extreme southern Bay of Campeche and Mexico. Although one of the statistical models is showing the system moving north-northwestward after emerging over the Bay of Campeche, it should be discounted since the ridge should prevent it from moving that far northward. The cyclone would make its second landfall near Veracruz, Mexico on Thursday afternoon and will shortly dissipate over the Sierra Madre Oriental mountain range in Mexico by early Friday morning.

Additional weakening is expected as it should remain over land in the next 36 hours. Thereafter, it would emerge over the southern Bay of Campeche. However, the system will have very limited time over the waters to intensify. Though, if the system gains a little more latitude, then it would have more time over water and strengthen. It should be noted that the system could degenerate into a remnant low or dissipate earlier before reaching the Bay of Campeche. Regardless, the system will continue to bring very heavy rain to portions of Guatemala, Belize, and eastern Mexico for the next few days. This would cause dangerous floods over those regions.

Civicane49

Hurricane Flood

Updated: 11:17 AM GMT on June 18, 2013

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93E unlikely to develop in the eastern Pacific

By: Civicane49, 2:32 AM GMT on June 12, 2013

An area of disturbed weather (Invest 93E) located about 650 miles south-southwest of Manzanillo remains poorly organized as showers and thunderstorms remain limited and disorganized on satellite imagery. Based on satellite images and scatterometer passes, I see no evidence of a well-defined and closed circulation of this disturbance. Although sea surface temperatures and shear are quite favorable for 93E to organize in the next few days, the large area of very dry, stable airmass to the northwest of the disturbance as seen on water vapor imagery will be the main inhibitor of this system; the dry air will likely halt any further development of 93E as it should prevent convection to develop or maintain over the system. Thus, I foresee no significant development of 93E in the next two days. By 72 hours, the tropical disturbance should cross over cool sea surface temperatures below 26.5°C threshold required for tropical cyclone formation. By days four or five, the disturbance should dissipate. All things considered, I give this system a 10% chance of becoming a tropical cyclone in the next 48 hours. 93E will continue to move west-northwestward in the next few days as it will remain under the influence of a ridge over northwestern Mexico. The system would then turn westward by day three and remain in that direction until it dissipates. 93E will not threaten any land areas throughout its lifetime. Model guidance is in a good agreement with the forecast path of the disturbance.


Figure 1. Evening infrared satellite image of Invest 93E. Image credit: NOAA/RAMMB.

Elsewhere in the tropics
Aside from 93E, no tropical cyclone development is anticipated for the next seven days for both the eastern Pacific and the Atlantic. However, the CMC is hinting a potential tropical storm developing in the eastern Pacific located well south of Mexico by late next week. By the last week of June, the upward Madden–Julian oscillation (MJO) pulse should be in the Atlantic as indicated by most of the global models. Since the upward MJO pulse enhances convective activity, it would help increase the chances of tropical cyclone development there. It should be noted that the GFS is forecasting a possible tropical cyclone developing over the Gulf of Mexico by the final week of June.

Civicane49

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Updated: 2:37 AM GMT on June 12, 2013

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Tropical Storm Andrea forms in the Gulf of Mexico

By: Civicane49, 10:02 AM GMT on June 06, 2013

The first named storm of the 2013 Atlantic hurricane season has arrived. Tropical Storm Andrea has formed over the eastern Gulf of Mexico after the Air Force hurricane hunter plane investigated this system and found a well-defined and closed circulation center beneath the heavy thunderstorm activity. As of the latest National Hurricane Center (NHC) advisory, Andrea possesses maximum sustained winds of 60 mph and the minimum barometric pressure of 997 mb. The cyclone is moving north-northeastward at 13 mph. Satellite imagery shows a fairly disorganized tropical storm with part of the low-level center located beneath the convection, thanks to both the persistent high southwesterly shear of 25 knots and dry air. Though, the cyclone itself is maintaining some organization.


Figure 1. Morning infrared satellite image of Tropical Storm Andrea. Image credit: NOAA/RAMMB.

Forecast for Andrea
The tropical storm is likely at its peak; conditions have been marginally favorable and will remain this way until the storm makes landfall in Florida's Big Bend later in the evening. Both the high shear and marginal sea surface temperatures should prevent any further intensification of the cyclone. Thus, I expect no significant change in strength until landfall. The tropical cyclone will interact with the upper-level trough over the eastern half of the United States and should acquire extratropical characteristics by 36 – 48 hours. Andrea should continue to move north-northeastward and increase its forward speed as the aforementioned trough amplifies over the eastern half of the United States. It is expected to make landfall in the Big Bend region in Florida by later this evening. The storm should then turn northeastward and move across the East Coast on Friday and Saturday. By Sunday, it is forecast to move over or close to Canada’s Nova Scotia and Newfoundland. Model guidance is in an excellent agreement with the expected path of Andrea.

Heavy rain remains the biggest threat from Andrea; the radar is showing widespread heavy to moderate rain over much of Florida. Heavy rain should continue for the Florida peninsula in the next day or so and rainfall is anticipated to be up to 3 – 6 inches for this region. Few isolated EF-0 tornadoes are possible in this area. Storm surge is also anticipated for the west coast of Florida. The rain should spread through parts of the East Coast in the next couple of days as the storm moves northeastward across the region.

Civicane49

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Updated: 11:10 AM GMT on June 06, 2013

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91L remains disorganized but could develop in the Gulf of Mexico

By: Civicane49, 2:49 PM GMT on June 04, 2013

The 2013 Atlantic hurricane season has just begun, and we are now discussing the potential development of the first tropical cyclone of the season in the Atlantic. There is a large area of disorganized showers and thunderstorms situating over northwestern Caribbean, western Cuba, and southeastern Gulf of Mexico. This area of disturbed weather has been tagged as “Invest 91L”. Satellite image depicts that 91L remains poorly-organized with the heavy thunderstorms remain displaced to the southeast of the low-level center; this is due to the combination of both the strong vertical wind shear and dry air over the Gulf of Mexico. CIMSS analysis reveals that the system is within high northwesterly shear of 20 – 30 knots. The shear is shifting the heavy thunderstorm activity to the east away from the center as seen on satellite loop. Water vapor imagery depicts a large area of dry, stable air situating across much of the Gulf and is preventing the convection to develop over the center.

Forecast for 91L
Shear is expected to decrease into moderate range in the next day or so, which could become more favorable for development. If dry air lingers, however, further development would likely be prevented. At this time, development will be slow to occur, and the National Hurricane Center (NHC) is giving this tropical disturbance a 30% chance of becoming a tropical cyclone in the next 48 hours, which I agree on. Regardless of development, the system will likely continue to bring heavy rain over portions of northwestern Yucatan Peninsula, portions of western Cuba, and South Florida for the next few days. The system is currently moving slowly north-northeastward and is expected to remain in that direction in the next few days. The disturbance should make landfall on Florida by around Friday. Models are in a fairly good agreement with the forecast track of 91L.


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

Elsewhere, no tropical cyclone development is anticipated in the next two days.

Civicane49

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