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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Subtropical Storm Ana More Organized; Philippines' Cat 3 Noul Intensifying
Tropical storm warnings are flying along much of the South Carolina and North Carolina coasts as a nearly stationary Subtropical Storm Ana spins away about 180 miles south of Myrtle Beach, South Carolina. Ana gained enough organization and heavy thunderstorms last night to be classified as a subtropical storm; its formation date of May 7 is the earliest appearance of a named storm in the Atlantic since a previous incarnation of Subtropical Storm Ana was recognized on April 20, 2003.
Long-range radar out of Wilmington, North Carolina Friday afternoon showed only a small amount of heavy rains associated with the storm were reaching the coast, and satellite loops showed that the main area of heavy thunderstorms were on the southeast side of the storm, farthest from the coast, and about 100 miles from the center of circulation. This is a typical appearance for a subtropical cyclone. As explained in wunderground's subtropical storm tutorial, a subtropical cyclone has characteristics of both tropical and extratropical cyclones. The difference between a subtropical storm and a tropical storm is not that important as far as the winds they can generate, but tropical storms generate more rain, and tropical storms have the potential to rapidly intensify into hurricanes, while subtropical storms do not. The area of heavy thunderstorms was expanding in areal coverage and a tight circulation center fully exposed to view was apparent on Friday afternoon, indicating that Ana was growing more organized; Ana will likely be a tropical storm and not a subtropical storm by Friday night. Wind shear over Ana was a light 5 - 10 knots, which was aiding development. Ocean temperatures were near 25°C (77°F), which is just at the limit of where a tropical storm can form. Cold air aloft associated with an upper level low was increasing the instability of the atmosphere, though, allowing Ana's heavy thunderstorms to grow more than usual for ocean temperatures of 25°C. This upper-level low was also bringing dry air into Ana's core, though, which has been slowing the storm's development.
Figure 1. Latest satellite image of Ana.
Figure 2. Radar image of Ana taken at 2:16 pm EDT Friday May 8, 2015, from the Long-range radar out of Wilmington, North Carolina. A few modest rainbands were affecting the coasts of South Carolina and North Carolina.
Forecast for Ana
The 8 am EDT Friday run of the SHIPS model predicted that wind shear over Ana would be in the light to moderate range, 5 - 20 knots, until the storm makes landfall on Sunday. Steering currents are weak over the waters off the Southeast U.S. coast, so expect a slow motion for the storm. The 12Z Friday morning runs of our two top models for predicting tropical cyclone tracks, the European and GFS models, both showed the system making landfall on Sunday between 8 am - 5 pm EDT near the North Carolina/South Carolina border. Given the relatively marginal environmental conditions for intensification, the cooler waters Ana will encounter as it nears the coast, and the fact the storm has only about two days until landfall, I expect that the worst Ana will be able to do is intensify to a 65-mph tropical storm that brings 4 - 6" of rain to the coasts of South Carolina and North Carolina on Saturday and Sunday. My expectation is that the storm will have 55 mph winds at landfall. In their 11 am EDT Friday forecast, NHC called for 50 mph winds at landfall.
Wunderground member Levi Cowan has been putting together some nice video discussions of Ana; you can check out his 11 am EDT Friday version here.
Figure 3. MODIS satellite image of Typhoon Noul taken from NASA's Aqua satellite at 04:55 UTC May 8, 2015. At the time, Noul was a Category 3 storm with 115 mph winds. Image credit: NASA.
Category 3 Typhoon Noul headed for the northern Philippines
Category 3 Typhoon Noul (called Dodong in the Philippines’ naming system) continued a slow intensification process on Friday morning, with winds estimated at 120 mph winds as of 8 am EDT Friday. WIth plenty of deep, water water before it and wind shear a light 5 - 10 knots, continued intensification into a Category 4 storm appears likely as the storm heads towards the northern Philippines. Satellite loops on Friday afternoon showed that Noul was a medium-sized storm with a 16-mile diameter eye and a modest area of heavy thunderstorms. The storm didn't have much in the way of outer spiral bands, and had taken on the shape of a large donut. This sort of configuration may qualify Noul as an uncommon class of tropical cyclone called an "annular" storm. Annular storms are more able to resist weakening, and I expect Noul will remain at least a Category 3 storm with 115 mph winds within six hours of landfall, despite the increasing levels of wind shear and weakening effects of land interaction that will be occurring. The outer reaches of Noul are already affecting the Philippines, and landfall of the center is expected to occur in northeastern Luzon Island near 11 pm EDT Saturday (03 UTC Sunday), according to the 12Z Friday run of the GFS model. Noul will encounter a trough of low pressure as it approaches the Philippines, which is expected to induce a more northwesterly track. This may cause the storm's eye to miss or barely graze the Philippines, as predicted by the 12Z Friday run of the European model. In either case, Luzon will be on the weaker left front side of Noul, which will make heavy rains the main threat from the storm. The 06Z Friday run of the GFDL model predicted that heavy rains in excess of 8 inches would be confined to a very small portion of the northeast coast of Luzon. I do not expect this to be a major disaster for the Philippines; loss of life should be limited and damage in the tens of millions of dollars if Noul makes a grazing landfall as a Category 3 or 4 storm.
Noul will be the second tropical cyclone to affect the Philippines so far in 2015. The first was Tropical Storm Maysak, which hit the Philippines exceptionally early in the season--during Easter weekend, April 4 - 5. Fortunately, Maysak was weakening rapidly as it made landfall, and no deaths or significant damage were reported (though four people were injured after huge waves generated by Maysak hit them while they were taking selfies along the shoreline of Dipaculao town in Aurora province on April 4.)
Record early activity for the 2015 typhoon season
On the heels of Noul comes Tropical Storm Seven, which is organizing to the east of Noul over Micronesia. TS 7 should pass within 300 miles of Guam next week as an intensifying typhoon, and may pose a long-range threat to the Philippines. Satellite loops show that TS 7 is not yet well-organized, but it does have a large area of heavy thunderstorms. The Japan Meteorological Agency (JMA) was still classifying TS 7 as a tropical depression on Friday afternoon, but when JMA gives TS 7 a name, it will break the record set on May 19, 1971 for the earliest formation of the Northwest Pacific's seventh named storm of the year, according to statistics of the Japan Meteorological Agency's database from 1951 - 2015 maintained by Digital Typhoon. The early start to 2015 typhoon season is due, in part, to exceptionally warm ocean temperatures in the typhoon breeding region between 5 - 10°N near the Date Line. These temperatures have been over 2°C (3.6°F) above average in recent months, due to a strengthening El Niño event.
All-time May heat record for Europe falls--in the first week of May!
Extreme heat roasted Italy this week, where the city of Catenanuova hit 41.9°C (107.4°F) on Wednesday, May 6. According to weather records researcher Maximiliano Herrera, this is the hottest May temperature ever recorded in Europe. The previous record was 41.7°C (107.1°F), set on May 17, 2006 in Andujar, Spain. The new European May heat record comes just one day after the earliest 40°C temperature ever recorded in Europe--a 40.4°C (104.7°F) reading at San Priamo in southeastern Sardinia, according to Herrera's stats.
A major severe weather outbreak is expected across the Central U.S. on both Friday and Saturday afternoon, as discussed by Bob Henson in this morning's blog post. Check out our Severe Weather Page to follow the storms, and our live blog on Saturday.
Jeff Masters
Long-range radar out of Wilmington, North Carolina Friday afternoon showed only a small amount of heavy rains associated with the storm were reaching the coast, and satellite loops showed that the main area of heavy thunderstorms were on the southeast side of the storm, farthest from the coast, and about 100 miles from the center of circulation. This is a typical appearance for a subtropical cyclone. As explained in wunderground's subtropical storm tutorial, a subtropical cyclone has characteristics of both tropical and extratropical cyclones. The difference between a subtropical storm and a tropical storm is not that important as far as the winds they can generate, but tropical storms generate more rain, and tropical storms have the potential to rapidly intensify into hurricanes, while subtropical storms do not. The area of heavy thunderstorms was expanding in areal coverage and a tight circulation center fully exposed to view was apparent on Friday afternoon, indicating that Ana was growing more organized; Ana will likely be a tropical storm and not a subtropical storm by Friday night. Wind shear over Ana was a light 5 - 10 knots, which was aiding development. Ocean temperatures were near 25°C (77°F), which is just at the limit of where a tropical storm can form. Cold air aloft associated with an upper level low was increasing the instability of the atmosphere, though, allowing Ana's heavy thunderstorms to grow more than usual for ocean temperatures of 25°C. This upper-level low was also bringing dry air into Ana's core, though, which has been slowing the storm's development.
Figure 1. Latest satellite image of Ana.
Figure 2. Radar image of Ana taken at 2:16 pm EDT Friday May 8, 2015, from the Long-range radar out of Wilmington, North Carolina. A few modest rainbands were affecting the coasts of South Carolina and North Carolina.
Forecast for Ana
The 8 am EDT Friday run of the SHIPS model predicted that wind shear over Ana would be in the light to moderate range, 5 - 20 knots, until the storm makes landfall on Sunday. Steering currents are weak over the waters off the Southeast U.S. coast, so expect a slow motion for the storm. The 12Z Friday morning runs of our two top models for predicting tropical cyclone tracks, the European and GFS models, both showed the system making landfall on Sunday between 8 am - 5 pm EDT near the North Carolina/South Carolina border. Given the relatively marginal environmental conditions for intensification, the cooler waters Ana will encounter as it nears the coast, and the fact the storm has only about two days until landfall, I expect that the worst Ana will be able to do is intensify to a 65-mph tropical storm that brings 4 - 6" of rain to the coasts of South Carolina and North Carolina on Saturday and Sunday. My expectation is that the storm will have 55 mph winds at landfall. In their 11 am EDT Friday forecast, NHC called for 50 mph winds at landfall.
Wunderground member Levi Cowan has been putting together some nice video discussions of Ana; you can check out his 11 am EDT Friday version here.
Figure 3. MODIS satellite image of Typhoon Noul taken from NASA's Aqua satellite at 04:55 UTC May 8, 2015. At the time, Noul was a Category 3 storm with 115 mph winds. Image credit: NASA.
Category 3 Typhoon Noul headed for the northern Philippines
Category 3 Typhoon Noul (called Dodong in the Philippines’ naming system) continued a slow intensification process on Friday morning, with winds estimated at 120 mph winds as of 8 am EDT Friday. WIth plenty of deep, water water before it and wind shear a light 5 - 10 knots, continued intensification into a Category 4 storm appears likely as the storm heads towards the northern Philippines. Satellite loops on Friday afternoon showed that Noul was a medium-sized storm with a 16-mile diameter eye and a modest area of heavy thunderstorms. The storm didn't have much in the way of outer spiral bands, and had taken on the shape of a large donut. This sort of configuration may qualify Noul as an uncommon class of tropical cyclone called an "annular" storm. Annular storms are more able to resist weakening, and I expect Noul will remain at least a Category 3 storm with 115 mph winds within six hours of landfall, despite the increasing levels of wind shear and weakening effects of land interaction that will be occurring. The outer reaches of Noul are already affecting the Philippines, and landfall of the center is expected to occur in northeastern Luzon Island near 11 pm EDT Saturday (03 UTC Sunday), according to the 12Z Friday run of the GFS model. Noul will encounter a trough of low pressure as it approaches the Philippines, which is expected to induce a more northwesterly track. This may cause the storm's eye to miss or barely graze the Philippines, as predicted by the 12Z Friday run of the European model. In either case, Luzon will be on the weaker left front side of Noul, which will make heavy rains the main threat from the storm. The 06Z Friday run of the GFDL model predicted that heavy rains in excess of 8 inches would be confined to a very small portion of the northeast coast of Luzon. I do not expect this to be a major disaster for the Philippines; loss of life should be limited and damage in the tens of millions of dollars if Noul makes a grazing landfall as a Category 3 or 4 storm.
Noul will be the second tropical cyclone to affect the Philippines so far in 2015. The first was Tropical Storm Maysak, which hit the Philippines exceptionally early in the season--during Easter weekend, April 4 - 5. Fortunately, Maysak was weakening rapidly as it made landfall, and no deaths or significant damage were reported (though four people were injured after huge waves generated by Maysak hit them while they were taking selfies along the shoreline of Dipaculao town in Aurora province on April 4.)
Record early activity for the 2015 typhoon season
On the heels of Noul comes Tropical Storm Seven, which is organizing to the east of Noul over Micronesia. TS 7 should pass within 300 miles of Guam next week as an intensifying typhoon, and may pose a long-range threat to the Philippines. Satellite loops show that TS 7 is not yet well-organized, but it does have a large area of heavy thunderstorms. The Japan Meteorological Agency (JMA) was still classifying TS 7 as a tropical depression on Friday afternoon, but when JMA gives TS 7 a name, it will break the record set on May 19, 1971 for the earliest formation of the Northwest Pacific's seventh named storm of the year, according to statistics of the Japan Meteorological Agency's database from 1951 - 2015 maintained by Digital Typhoon. The early start to 2015 typhoon season is due, in part, to exceptionally warm ocean temperatures in the typhoon breeding region between 5 - 10°N near the Date Line. These temperatures have been over 2°C (3.6°F) above average in recent months, due to a strengthening El Niño event.
All-time May heat record for Europe falls--in the first week of May!
Extreme heat roasted Italy this week, where the city of Catenanuova hit 41.9°C (107.4°F) on Wednesday, May 6. According to weather records researcher Maximiliano Herrera, this is the hottest May temperature ever recorded in Europe. The previous record was 41.7°C (107.1°F), set on May 17, 2006 in Andujar, Spain. The new European May heat record comes just one day after the earliest 40°C temperature ever recorded in Europe--a 40.4°C (104.7°F) reading at San Priamo in southeastern Sardinia, according to Herrera's stats.
A major severe weather outbreak is expected across the Central U.S. on both Friday and Saturday afternoon, as discussed by Bob Henson in this morning's blog post. Check out our Severe Weather Page to follow the storms, and our live blog on Saturday.
Jeff Masters
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.