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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Devastating Rains in South Carolina; Joaquin Lashing Bermuda
One of the most widespread and intense multi-day rain events in the history of the Southeast is bringing misery and destruction to thousands of residents. A broad swath of deep tropical moisture extending west from Hurricane Joaquin has intercepted a preexisting frontal zone and a strong upper-level low parked over the Southeast. These factors produced a NW-to-SE band of extremely heavy rain on Saturday from the northern South Carolina coast to the Uplands at the other end of the state. Flooding is widespread, and at least four deaths have been reported.
On Sunday, the band was slowly pivoting in counterclockwise fashion to a more W-to-E orientation. This was providing some relief to Charleston, which experienced a flash flood emergency with countless water rescues at high tide late Saturday night. The worst conditions on Sunday afternoon had shifted north to the area from Columbia to Myrtle Beach, where numerous flash flood watches and warnings were in effect. “The City of Georgetown is predominantly under water,” said Georgetown (SC) fire chief Joey Tanner, at 11:30 am EDT Sunday. Extensive coastal and tidal flooding has also returned to the Virginia and North Carolina coast, where an intensification of onshore flow has produced tides around 3 feet above normal on Sunday, comparable to those observed on Friday.
FIgure 1. An American Red Cross van was stranded in floodwaters on U.S. Hwy. 17 North near Georgetown, S.C., on Sunday, October 4, 2015. Several sections of Highway 17 were shut down between Charleston and Georgetown. Image credit: AP Photo/Mic Smith.
Figure 2. NWS/NEXRAD radar imagery at 2:50 pm EDT Sunday, October 4, 2015, showed a persistent swath of rain with very heavy embedded cells, extending from west to east across much of South Carolina and far south North Carolina. Image credit: WU’s Storm app for iPad.
Sunday’s is the second round of extremely heavy rain for the SC/NC border area, which was first hammered on Thursday and Friday. Conditions will gradually improve through most of the Carolinas tonight into Monday as the upper low begins to move eastward, but the coastal border area will be the last to see the heavy rain depart. From roughly Florence, SC, to Wilmington, NC, we may end up with some truly phenomenal 3- to 5-day rain totals. According to Dr. Greg Forbes of the Weather Channel, an NWS employee 3 miles northeast of Boone Hall Plantation in Charleston County reported a storm total of 24.23” on Sunday morning. It would not be surprising to see a number of storm totals in the 15” - 25” range, and perhaps several beyond 25”. We can also expect to see significant river flooding over the next several days as runoff from the inland rains makes its way downstream.
Here are several records already set in South Carolina:
--At the Charleston airport (CHS), 14.48” fell from Thursday through Saturday, October 1-3. This beats the previous 3-day record of 11.95” set on June 9-11, 1973. Most of the rain--11.50”--fell on Saturday, October 3, beating the previous calendar-day record of 10.52” (September 21, 1998). Weather records at CHS began in 1983.
--At Downtown Charleston, where weather records began in 1870, the total of 13.80” for October 1-3 beats the previous 3-day record of 12.39”, set on June 9-11, 1973.
--At Columbia, at least 7.46” had fallen on Sunday as of 2:00 pm EDT. Combined with 0.46” on Friday and 3.57” on Saturday, this gives Columbia an unofficial three-day total of at least 11.46”, with rain still falling.
Using about a century of precipitation records, NOAA has constructed a Precipitation Frequency Data Server, which estimates how often we might expect to see extreme rainfall events recur. According to NOAA's Precipitation Frequency Data Server, these could be 1-in-1000 year rains for some locations. (Hydrologists would refer to a 1-in-1000-year rain as having a typical "recurrence interval" of 1000 years. The idea is that such events are not always separated by 1000 years; the same amount of rain could conceivably occur the very next year, or might not occur until thousands of years later.) The three-day 1-in-1000 year rainfall amounts for Charleston and Columbia are 17.1" and 14.2", respectively. The 24-hour 1-in-1000 year rainfall amounts for Charleston and Columbia are 14.8" and 12.5", respectively.
Figure 3. 24-hour recurrence intervals for rainfall from 8:00 am EDT Saturday, October 3, through Sunday, October 4. A large swath from Columbia to Charleston experienced 24-hour rainfalls that would be expected to recur less than once every 100 years. Recurrence intervals of greater than 100 years are not shown in this analysis. Multi-day rainfalls by the time this event is over may reach the 1-in-1000-year recurrence interval in some locations. MetStat computed the recurrence interval statistics based on gauge-adjusted radar precipitation and frequency estimates from NOAA Atlas 14 Volume 8, published in 2013 (http://dipper.nws.noaa.gov/hdsc/pfds/.)MetStat does not supply their precipitation recurrence interval forecasts or premium analysis products for free, but anyone can monitor the real-time analysis (observed) at: http://metstat.com/solutions/extreme-precipitation-index-analysis/ or on their Facebook page. Image credit: MetSTAT.
Adding insult to injury, the Southeast Regional Climate Center reported on Sunday that the Raleigh-Durham International Airport (RDU) had scored its 11th consecutive day of measurable rain, a mark reached seven other times since records began in the area in 1887. If it rains on Monday as predicted, RDU will tied its record-longest wet streak of 12 consecutive days, recorded from July 28 to August 8, 1887.
What’s causing the Carolina rains?
There isn’t just one culprit behind the incredible rains befalling the Carolinas--it is a multifactoral event, with several weather features coming into play. A new post by WU contributor Lee Grenci analyzes why the event is neither #Joaquin nor #NotJoaquin. Another WU blogger, Marshall Shepherd, outlines the connections between this event and the notorious “atmospheric river”--a feature behind some of the world’s heaviest mid-latitude rain events--in this article at Forbes.com. See also the Weather Channel’s comprehensive coverage of this event at weather.com, which will be frequently updated today and Monday.
Hurricane Joaquin approaching Bermuda
Conditions are rapidly deteriorating on Bermuda as Hurricane Joaquin draws closer, as seen on Bermuda radar. Now down to Category 2 strength, with top sustained winds of 105 mph as of 2:00 pm EDT Sunday, Joaquin was located about 125 miles southwest of Bermuda. Joaquin will be passing just west of the island, putting Bermuda on the more dangerous right-hand side of the storm, and the island remains in a hurricane warning. However, it appears Joaquin may move just far enough west to spare Bermuda from sustained hurricane-level conditions, as hurricane-force winds extend only about 60 miles from the center. Bermuda International Airport reported winds gusting to 55 mph around 3 pm ADT (2 pm EDT), with sustained winds near tropical storm strength (39 mph). After passing Bermuda, Joaquin should continue zipping across the Atlantic as it evolves into an extratropical storm.
Figure 4. Visible satellite image of Hurricane Joaquin at 1845Z Sunday, October 4, 2015. Bermuda is the small magenta area just northeast of Joaquin’s core. Image credit: NOAA/NESDIS.
Figure 5. Lt. Col. Keith Gibson, a pilot with the Air Force 53rd Weather Reconnaissance Squadron, pilots his C-130 hurricane hunter aircraft into Hurricane Joaquin on Saturday, October 3, 2015. On Friday, an Air Force hurricane hunter plane spiraled down from its penetration altitude of 10,000 in the eye to a altitude of 800 - 1000 feet, in order to search for the missing ship, El Faro. The ship, with a crew of 33, is still missing. Image credit: Air Force Reserve Hurricane Hunters.
Tropical Storm Oho likely to angle southeast of Hawaii
Despite unusually warm sea-surface temperatures, Tropical Storm Oho was apparently hindered from strengthening on Saturday by interaction with a large and strong band of convection extending well to its southeast. Bigger than Oho itself, this band was embedded within strong southwesterly monsoon flow, creating a setup more typical to the Northwest Pacific than the normally cooler and more stable Central Pacific. Strong wind shear also took its toll on Oho. The intense rainband has since weakened and moved further away, and Oho--now looking much more like a typical tropical storm, with a well-defined central core of convection--is projected to approach hurricane strength over the next several days as it moves mainly to the northeast. While models diverge somewhat on the particulars of Oho’s track, all dynamical and statistical models keep the storm well southeast of Hawaii. Oho’s remnant circulation could inject energy and moisture into a large, intense Pacific trough that will be approaching the Pacific Northwest more than a week from now.
Figure 6. Infrared image of Tropical Storm Oho from 1900 GMT Sunday, October 4. Image credit: NOAA/NESDIS.
In the Central Atlantic: Invest 91L
It’s late in the season for Cape Verde-type systems moving across the tropical Atlantic, but Invest 91L is trying to buck the odds. At present, 91L is little more than a large area of disorganized convection. Track models take 91L on a gradual curve north of the Lesser Antilles over the next five days. NHC gives 91L a 10% chance of development through Tuesday and a 30% chance through Friday. None of the leading long-range dynamical models develop 91L substantially during the upcoming week; this, plus climatology, suggests that 91L is unlikely to amount to much, although some models do intensify 91L toward the 4- to 5-day period.
A forecaster’s worst nightmare: Typhoon Mujigae intensifies to Cat 4 just before landfall
On Saturday, Typhoon Mujigae was forecast to hit Zhanjiang, China, about 200 miles west of Hong Kong, as a Category 1 storm. However, in the twelve hours before landfall, Mujigae surprised forecasters by rapidly intensifying from a Category 1 storm with 90 mph winds to an extremely dangerous Category 4 storm with 130 mph winds, and made landfall on the north side of the city of Zhanjiang near 1 am EDT Sunday (05 UTC.) An unexpected rapid intensification just before landfall in a heavily populated area is every hurricane forecaster's nightmare, and with Zhanjiang'a population being 7 million, there is the potential that Mujigae caused heavy loss of life and severe damage due to lack of preparedness for a Category 4 typhoon. The airport in Zhanjiang, which appears to have just missed getting hit by the weaker southern eyewall of the typhoon, recorded sustained winds of 65 mph at 2 pm Sunday local time, and rainfall of 5.20". The embedded tweet below shows Mujigae making landfall.
We’ll be back with our next update on Monday.
Bob Henson and Jeff Masters
On Sunday, the band was slowly pivoting in counterclockwise fashion to a more W-to-E orientation. This was providing some relief to Charleston, which experienced a flash flood emergency with countless water rescues at high tide late Saturday night. The worst conditions on Sunday afternoon had shifted north to the area from Columbia to Myrtle Beach, where numerous flash flood watches and warnings were in effect. “The City of Georgetown is predominantly under water,” said Georgetown (SC) fire chief Joey Tanner, at 11:30 am EDT Sunday. Extensive coastal and tidal flooding has also returned to the Virginia and North Carolina coast, where an intensification of onshore flow has produced tides around 3 feet above normal on Sunday, comparable to those observed on Friday.
FIgure 1. An American Red Cross van was stranded in floodwaters on U.S. Hwy. 17 North near Georgetown, S.C., on Sunday, October 4, 2015. Several sections of Highway 17 were shut down between Charleston and Georgetown. Image credit: AP Photo/Mic Smith.
Figure 2. NWS/NEXRAD radar imagery at 2:50 pm EDT Sunday, October 4, 2015, showed a persistent swath of rain with very heavy embedded cells, extending from west to east across much of South Carolina and far south North Carolina. Image credit: WU’s Storm app for iPad.
Sunday’s is the second round of extremely heavy rain for the SC/NC border area, which was first hammered on Thursday and Friday. Conditions will gradually improve through most of the Carolinas tonight into Monday as the upper low begins to move eastward, but the coastal border area will be the last to see the heavy rain depart. From roughly Florence, SC, to Wilmington, NC, we may end up with some truly phenomenal 3- to 5-day rain totals. According to Dr. Greg Forbes of the Weather Channel, an NWS employee 3 miles northeast of Boone Hall Plantation in Charleston County reported a storm total of 24.23” on Sunday morning. It would not be surprising to see a number of storm totals in the 15” - 25” range, and perhaps several beyond 25”. We can also expect to see significant river flooding over the next several days as runoff from the inland rains makes its way downstream.
Here are several records already set in South Carolina:
--At the Charleston airport (CHS), 14.48” fell from Thursday through Saturday, October 1-3. This beats the previous 3-day record of 11.95” set on June 9-11, 1973. Most of the rain--11.50”--fell on Saturday, October 3, beating the previous calendar-day record of 10.52” (September 21, 1998). Weather records at CHS began in 1983.
--At Downtown Charleston, where weather records began in 1870, the total of 13.80” for October 1-3 beats the previous 3-day record of 12.39”, set on June 9-11, 1973.
--At Columbia, at least 7.46” had fallen on Sunday as of 2:00 pm EDT. Combined with 0.46” on Friday and 3.57” on Saturday, this gives Columbia an unofficial three-day total of at least 11.46”, with rain still falling.
Using about a century of precipitation records, NOAA has constructed a Precipitation Frequency Data Server, which estimates how often we might expect to see extreme rainfall events recur. According to NOAA's Precipitation Frequency Data Server, these could be 1-in-1000 year rains for some locations. (Hydrologists would refer to a 1-in-1000-year rain as having a typical "recurrence interval" of 1000 years. The idea is that such events are not always separated by 1000 years; the same amount of rain could conceivably occur the very next year, or might not occur until thousands of years later.) The three-day 1-in-1000 year rainfall amounts for Charleston and Columbia are 17.1" and 14.2", respectively. The 24-hour 1-in-1000 year rainfall amounts for Charleston and Columbia are 14.8" and 12.5", respectively.
Figure 3. 24-hour recurrence intervals for rainfall from 8:00 am EDT Saturday, October 3, through Sunday, October 4. A large swath from Columbia to Charleston experienced 24-hour rainfalls that would be expected to recur less than once every 100 years. Recurrence intervals of greater than 100 years are not shown in this analysis. Multi-day rainfalls by the time this event is over may reach the 1-in-1000-year recurrence interval in some locations. MetStat computed the recurrence interval statistics based on gauge-adjusted radar precipitation and frequency estimates from NOAA Atlas 14 Volume 8, published in 2013 (http://dipper.nws.noaa.gov/hdsc/pfds/.)MetStat does not supply their precipitation recurrence interval forecasts or premium analysis products for free, but anyone can monitor the real-time analysis (observed) at: http://metstat.com/solutions/extreme-precipitation-index-analysis/ or on their Facebook page. Image credit: MetSTAT.
Adding insult to injury, the Southeast Regional Climate Center reported on Sunday that the Raleigh-Durham International Airport (RDU) had scored its 11th consecutive day of measurable rain, a mark reached seven other times since records began in the area in 1887. If it rains on Monday as predicted, RDU will tied its record-longest wet streak of 12 consecutive days, recorded from July 28 to August 8, 1887.
What’s causing the Carolina rains?
There isn’t just one culprit behind the incredible rains befalling the Carolinas--it is a multifactoral event, with several weather features coming into play. A new post by WU contributor Lee Grenci analyzes why the event is neither #Joaquin nor #NotJoaquin. Another WU blogger, Marshall Shepherd, outlines the connections between this event and the notorious “atmospheric river”--a feature behind some of the world’s heaviest mid-latitude rain events--in this article at Forbes.com. See also the Weather Channel’s comprehensive coverage of this event at weather.com, which will be frequently updated today and Monday.
Hurricane Joaquin approaching Bermuda
Conditions are rapidly deteriorating on Bermuda as Hurricane Joaquin draws closer, as seen on Bermuda radar. Now down to Category 2 strength, with top sustained winds of 105 mph as of 2:00 pm EDT Sunday, Joaquin was located about 125 miles southwest of Bermuda. Joaquin will be passing just west of the island, putting Bermuda on the more dangerous right-hand side of the storm, and the island remains in a hurricane warning. However, it appears Joaquin may move just far enough west to spare Bermuda from sustained hurricane-level conditions, as hurricane-force winds extend only about 60 miles from the center. Bermuda International Airport reported winds gusting to 55 mph around 3 pm ADT (2 pm EDT), with sustained winds near tropical storm strength (39 mph). After passing Bermuda, Joaquin should continue zipping across the Atlantic as it evolves into an extratropical storm.
Figure 4. Visible satellite image of Hurricane Joaquin at 1845Z Sunday, October 4, 2015. Bermuda is the small magenta area just northeast of Joaquin’s core. Image credit: NOAA/NESDIS.
Figure 5. Lt. Col. Keith Gibson, a pilot with the Air Force 53rd Weather Reconnaissance Squadron, pilots his C-130 hurricane hunter aircraft into Hurricane Joaquin on Saturday, October 3, 2015. On Friday, an Air Force hurricane hunter plane spiraled down from its penetration altitude of 10,000 in the eye to a altitude of 800 - 1000 feet, in order to search for the missing ship, El Faro. The ship, with a crew of 33, is still missing. Image credit: Air Force Reserve Hurricane Hunters.
Tropical Storm Oho likely to angle southeast of Hawaii
Despite unusually warm sea-surface temperatures, Tropical Storm Oho was apparently hindered from strengthening on Saturday by interaction with a large and strong band of convection extending well to its southeast. Bigger than Oho itself, this band was embedded within strong southwesterly monsoon flow, creating a setup more typical to the Northwest Pacific than the normally cooler and more stable Central Pacific. Strong wind shear also took its toll on Oho. The intense rainband has since weakened and moved further away, and Oho--now looking much more like a typical tropical storm, with a well-defined central core of convection--is projected to approach hurricane strength over the next several days as it moves mainly to the northeast. While models diverge somewhat on the particulars of Oho’s track, all dynamical and statistical models keep the storm well southeast of Hawaii. Oho’s remnant circulation could inject energy and moisture into a large, intense Pacific trough that will be approaching the Pacific Northwest more than a week from now.
Figure 6. Infrared image of Tropical Storm Oho from 1900 GMT Sunday, October 4. Image credit: NOAA/NESDIS.
In the Central Atlantic: Invest 91L
It’s late in the season for Cape Verde-type systems moving across the tropical Atlantic, but Invest 91L is trying to buck the odds. At present, 91L is little more than a large area of disorganized convection. Track models take 91L on a gradual curve north of the Lesser Antilles over the next five days. NHC gives 91L a 10% chance of development through Tuesday and a 30% chance through Friday. None of the leading long-range dynamical models develop 91L substantially during the upcoming week; this, plus climatology, suggests that 91L is unlikely to amount to much, although some models do intensify 91L toward the 4- to 5-day period.
A forecaster’s worst nightmare: Typhoon Mujigae intensifies to Cat 4 just before landfall
On Saturday, Typhoon Mujigae was forecast to hit Zhanjiang, China, about 200 miles west of Hong Kong, as a Category 1 storm. However, in the twelve hours before landfall, Mujigae surprised forecasters by rapidly intensifying from a Category 1 storm with 90 mph winds to an extremely dangerous Category 4 storm with 130 mph winds, and made landfall on the north side of the city of Zhanjiang near 1 am EDT Sunday (05 UTC.) An unexpected rapid intensification just before landfall in a heavily populated area is every hurricane forecaster's nightmare, and with Zhanjiang'a population being 7 million, there is the potential that Mujigae caused heavy loss of life and severe damage due to lack of preparedness for a Category 4 typhoon. The airport in Zhanjiang, which appears to have just missed getting hit by the weaker southern eyewall of the typhoon, recorded sustained winds of 65 mph at 2 pm Sunday local time, and rainfall of 5.20". The embedded tweet below shows Mujigae making landfall.
We’ll be back with our next update on Monday.
Bob Henson and Jeff Masters
#Himawari VIS showing Typhoon #Mujigae slam into Zhanjiang, China today pic.twitter.com/UEWGypt5mg
— Dan Lindsey (@DanLindsey77) October 4, 2015The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.