Wilkens Weather tracks 8 tropical cyclones in the Western Pacific this July

The West Pacific Ocean became quite active last weekend, with four concurrent storms. This tropical activity was triggered by an active Madden-Julian Oscillation (MJO) phase coupled with the seasonal positioning of the monsoon trough. There have been seven named storms since July 1, the most recent being Typhoon Nesat.

Earlier this month, Tropical Storm Nanmadol formed northeast of the Philippines and within 48 hours made landfall along the west coast of the Japanese island of Kyushu. Wilkens Weather meteorologists closely monitored this storm for customers operating in the East China Sea and commenced storm advisories 42 hours in advance of the Joint Typhoon Warning Center (JTWC).

Marine Meteorologist Bryce Link explained his decision to initiate advisories at 09UTC on June 30th, “Deep thunderstorms were centered around a developing surface low and the system was in a fantastic environment”. Bryce pulled the trigger on this storm when operational models such as the GFS and ECMWF generally showed no signs of tropical development. ECMWF ensembles showed a stronger signal for tropical development, but the operational signaled nothing at the time the first WWT advisory was issued.

20-26 July 2017 West Pacific Tropical Cyclone Development.png

Sea surface temperatures (SSTs) have been on the rise since Nanmadol tracked across the East China Sea in early July. Early in the month SSTs were in the mid-80s across a small portion of the East China Sea, where Nanmadol tracked, and generally anywhere south and east of Taiwan. The graphic above (from July 24th) shows that SSTs are now in the upper 80s to 90°F (31-32°C) across much of the same region. These above average SSTs and favorable ocean heat content have created a conducive environment for tropical development. In fact, the last two tropical cyclones to form, Roke and Nesat, developed in this very warm area near the Philippines.

Currently, Typhoon Nesat is flaring convection northeast of Luzon. Further intensification is expected prior to landfall over Central Taiwan. Nesat formed along the monsoon trough, which is active from the Gulf of Thailand through the central Philippines as depicted in the 850mb wind graphic below. Tropical cyclones will not form in the area of enhanced westerly flow due to the presence of moderate to high vertical wind shear. Nesat was the second typhoon to develop in 2017.

850mb TropicalTidbits Chart with monsoon trough manual overlay.png

Despite convective and tropical cyclone activity in this region, the first typhoon of 2017 (Noru) developed at a higher latitude (near 28°N). Noru became a tropical depression over 1,000nm east-southeast of Yokosuka, Japan on July 20th. Early on, Noru tracked westward in response to two competing ridges to the south and northeast. Then, the cyclone’s movement slowed and the steering flow pulled Tropical Storm Noru and Tropical Storm Kulap around a central point. Noru became a typhoon on July 24th and the two cyclones “danced” cyclonically around each other the following day, a phenomenon known as the Fujiwhara Effect.  The end result was Tropical Storm Kulap tracking across cooler waters and dissipating within 24 hours and Noru maintaining typhoon strength southeast of Japan. Wilkens Weather meteorologists forecast Typhoon Noru to persist over the Northwest Pacific Ocean into early August.

Author’s note: This blog was updated July 28th to reflect the latest tropical information.

 

Watch the Fujiwhara Effect in the Northwest Pacific Ocean

Meteorologists worldwide are watching two cyclones in the Northwest Pacific begin their “dance” around each other. Tropical storm Kulap and typhoon Noru are beginning to endure a weather phenomena known as the Fujiwhara Effect.

The Fujiwhara Effect occurs when two cyclones rotate or “dance” around each other in a counter-clockwise direction (for the Northern Hemisphere). The two cyclones are actually rotating around a single point, or center, on an axis that connects the cyclone centers. Binary interaction of the cyclones can occur only if the cyclone centers are separated by a distance of roughly 1400km, or nearly 870 miles. The National Weather Service defines Fujiwhara Effect as the tendency of two nearby tropical cyclones to rotate cyclonically about each other.

Fuji July 24 Noru Kulap
Typhoon Noru (26.2N, 154.9E) and Tropical Storm Kulap (33.1N, 159.1E) dancing around each other in the Northwest Pacific just after midnight local Japan time on July 24, 2017.

The Fujiwhara effect is named after Dr. Sakhuhei Fujiwhara, who was the Chief of the Central Meteorological Bureau in Tokyo, Japan after the First World War. In 1921, he performed and studied the interaction and movements of water vortices. Dr. Fujiwhara concluded that if two water vortices spinning counter-clockwise came close enough to each other, each vortex would rotate around the other. In the atmosphere, if one vortex (tropical cyclone) is stronger than the other, eventually the smaller vortex (tropical cyclone) could get caught in the circulation of the larger one.

When the Fujiwhara Effect occurs, the intensity and track of a tropical cyclone can be greatly altered, creating a complicated and difficult forecast. In the Northwest Pacific, tropical storm Kulap will weaken and dissipate as it is engulfed by typhoon Noru over the next 24 hours.

According to Dong (1983), archived data from the National Hurricane Center portrayed the western Pacific Ocean to have a higher frequency of binary interaction than the Atlantic Ocean. During a 36 year period, 1946-1981, two spatially proximate storms averaged 1.5 annually over the western Pacific compared to .33 annually over the Atlantic. This is likely due to the Pacific having an overall higher tropical cyclone frequency compared to the Atlantic Ocean. Furthermore, Dong studied the Intertropical Convergence Zone (ITCZ) over the Pacific Ocean versus the Atlantic Ocean. He concluded the ITCZ is better defined in the Pacific basin, leading to higher tropical cyclone activity, compared to the Atlantic basin. A good majority of tropical cyclones in the Atlantic spawn from tropical waves that emerge off the West African coast.

1994 Ruth
Photo, via The Merger of Two Tropical Cyclones, of Pat and Ruth orbiting each other, approaching a distance of 200 nautical miles.

Another example of a classic Fujiwhara Effect occured during the last week of September 1994 with tropical cyclone Pat and tropical storm Ruth.

WWT meteorologists increase 2017 Atlantic hurricane season forecast

Wilkens Weather’s annual spring outlook includes a forecast for the upcoming Atlantic hurricane season. This spring, our meteorologists predicted a near normal 2017 Atlantic hurricane season with 12 named storms, including five hurricanes.

One of the key parameters factored into each year’s tropical outlook is the long-range forecast of the El Niño – Southern Oscillation (ENSO). When our 2017 tropical outlook was initially released, long-range forecast models indicated a higher likelihood that an El Niño would develop than is currently being seen in recent climate models.

In late April, there was about a 50% likelihood that El Niño would develop over the tropical Pacific in the late summer months, extending into September.  However, the most recent climate model issued by the International Research Institute for Climate and Society at Columbia University now projects a 35-45% likelihood of an El Niño phase developing over the next several months. With consideration to the updated ENSO forecast, Wilkens Weather has increased their 2017 Atlantic tropical outlook from 12 to 14 named storms, and 3 major hurricanes.

Since an El Niño phase in the central Pacific Ocean can produce a harsh environment for tropical development in the Atlantic basin, a reduced probability yields an increased chance of hurricanes in the North Atlantic. There is also consideration that the time frame for El Nino developing was before the peak of Atlantic hurricane season. Therefore, a lesser chance of El Nino would give a greater chance to more favorable atmospheric conditions for hurricanes during the peak season. 

(Author’s Note: this forecast does not include Tropical Storm Arlene, which formed during the month of April before the official start of hurricane season. TS Arlene was only the second tropical storm on record during the satellite era to form during April in the Atlantic basin.)

What is the Madden Julian Oscillation (MJO)?

The Madden Julian Oscillation (MJO) is an intraseasonal fluctuation that primarily initiates over the warm waters of the Indian Ocean and western Pacific.  The MJO is comprised of regions with various atmospheric features such as deep convection and atmospheric wind anomalies that propagate eastward along the ITCZ. During a convective phase of the MJO, there is an enhanced region of tropical convection and moisture resulting in above-average rainfall. The opposite is true for a suppressed convective phase. As the MJO continues propagating eastward, the monsoon trough weakens and may shift southward. East of the MJO the easterlies are strengthened, and to the west, the easterlies are weakened. Therefore the passing of positive phase MJO can affect atmospheric wind shear, which could in turn affect tropical cyclone activity.

Phillip Klotzbach studied the relationship between the MJO and the development of tropical systems in the Atlantic Basin. In his 2010 study, Klotzbach found a direct relationship between the increase in vertical wind shear and relative humidity, and enhanced tropical cyclone activity and intensification. In the convectively enhanced phase of the MJO, upper-level easterly and low-level westerly wind anomalies act together to reduce vertical wind shear. One primary ingredient for tropical cyclone development is reduced vertical wind shear. Relative humidity throughout the atmosphere is also needed for tropical development. In Camargo’s study (2009), he found that mid-level relative humidity played the most important role, compared to low-level absolute vorticity, vertical wind shear, and potential intensity in tropical cyclogenesis by the MJO. Therefore, when an eastward moving MJO and a tropical wave meet, it is possible for the tropical wave to develop into a tropical cyclone due to the enhanced atmospheric moisture and reduced vertical wind shear created by the MJO.  If a tropical cyclone already exists, its interaction with a MJO may cause the cyclone to intensify. Kingtse C. Mo discusses an increase in tropical cyclone activity over the Atlantic Basin when the convective phase of the MJO is located the Indian Ocean rather than the Pacific Ocean.July9

 

The image above represents a forecast for Outgoing Longwave Radiation (OLR) anomalies, a key detector for active MJO regions, issued by NOAA’s Climate Prediction Center (CPC). The CPC monitors and predicts climate variability and teleconnections for government, public, and private meteorological industries. Negative OLR values indicate enhanced convection or an active MJO phase (more cloud cover indicating more convective activity). Positive OLR values represent suppressed convection (less cloud cover).

The latest forecast from the ensemble mean GFS predicts an increase in OLR, possible MJO wave, across the Indian Ocean for the next two weeks. As Kingste C. Mo found in his study, there is likely an increase in tropical activity over the Atlantic Ocean when an MJO is present over the Indian Ocean.

Although Wilkens Weather is forecasting a very low chance for tropical development in the next five days, this will be a parameter worth watching this tropical season.

Frequency of Tropical Cyclones in Trinidad

Bret 19 June
Infrared Satellite of Bret nearing Trinidad valid 2100UTC 19 June 2017

The second tropical storm of the 2017 Atlantic hurricane season, Bret, tracked unusually far south impacting the island of Trinidad. Bret is only the 6th tropical system to have tracked across Trinidad in the past 100 years. Coincidentally, the last tropical storm to make landfall over Trinidad in 1993 was named Bret.

Since 1856, 43 storms have passed within 100nm of the island, but only two of these storms were major hurricanes. Typically, Trinidad is too close to the equator to experience strong tropical systems. According to WWT Meteorological Specialist, Marshall Wickman, “most systems at that latitude don’t get the Coriolis force needed for significant intensification”. Therefore, the bulk of the stronger storms and hurricanes tend to track to the north of Trinidad and Tobago.

Major Hurricane Ivan in 2004 and Flora in 1963 tracked too close for comfort. Both storms packed winds of 105 knots when within 60nm of the northern coast of the island.

For an area surrounded by water and unaccustomed to experiencing these storms, even a weak tropical storm can be frightening. 

“Trinidad experienced torrential rainfall and heavy winds for approximately three hours, especially in southern Trinidad. It was very scary and as I looked through the windows at my home, I prayed all through this period asking for protection”. 

When we checked-in with our Trinidad customers after Bret, it was heartwarming to hear that essential staff working on offshore and onshore facilities were safe. The main threats with this storm were heavy rainfall and flash flooding.

Flooding is major threat during any tropical cyclone and is not directly related to storm intensity. To learn how to stay safe during flood events, visit the National Weather Service’s flood resource page

Review of June Tropical Cyclone Activity in the Atlantic

Since the official start of the Atlantic hurricane season, June 1, two tropical storms have formed and impacted land areas. In June, the area with the greatest risk of tropical development is the Gulf of Mexico, Bay of Campeche and western Caribbean.

Origins and Tracks of June Tropical Cyclones

Contradicting climatology, Tropical Storm Bret formed 108nm East of Trinidad on June 19th. This area is typically unfavorable in June due to the amount of dry air and wind shear in the region. Bret was the earliest storm to form this far south in the Atlantic since official records began in 1851.

Bret originated as a rather unimpressive African wave, which progressed westward across the Atlantic in a marginally favorable tropical environment. A weak tropical wave to its west moistened the atmosphere over the eastern Caribbean, assisting in making conditions more favorable for Bret to develop. Here is a look at the moisture content over the tropical Atlantic in the days leading up to Bret’s formation:

noaa-goes-wv-animated-june15-16

While Bret was causing alarm in Trinidad in northern South America, Tropical Storm Cindy began to develop over the northern Gulf of Mexico. Cindy originated as an area of disturbed weather over the western Caribbean and Central America, and became Invest 93L East of the Yucatan Peninsula on June 17th.

This broad, disorganized low became difficult to track over the next five days. The ECMWF model maintained a forecast for landfall over Mexico or southern Texas. On the other hand, the GFS model favored a landfall near the Florida Panhandle. The discrepancy between the global model tracks continued through landfall on June 22. Higher resolution, regional forecast models eventually offered a more accurate middle-ground solution near the upper-Texas coast.     

Weak steering flow in the region contributed to the poor model performances. Another complexity was the close proximity to an upper level low over the northwest Gulf of Mexico. This feature provided high wind shear, resulting in a disorganized and asymmetrical storm. As a result, Cindy appeared to be subtropical rather than purely tropical through its duration. Southwesterly upper level winds from the trough pulled dry air into Cindy, restricting deep convection to the East side of the storm. Cindy’s battle with dry air on June 20th is seen in the brown coloring in the NOAA water vapor animation below.

WV Cindy Tues

High pressure from the western U.S. eventually built eastward over Texas, forcing Cindy to move northward. Air Force Reserve reconnaissance aircraft and a nearby ship confirmed a maximum intensity of 50kts the evening of June 20. Despite being a weak tropical storm, Cindy produced a large area of gale force winds and storm force gusts across the northern Gulf of Mexico. Cindy weakened to 40kts before making landfall near Sabine Pass, Texas on June 22nd.

NASA IMERG Data Cindy 2017
Cindy Estimated Total Rainfall from NASA

Both storms were short-lived with the primary threats of heavy rainfall and flash flooding. The Trinidad & Tobago Meteorological Service forecast 2-6 inches of rain for Trinidad and Tobago, Grenada and its Dependencies during the passage of Bret. NASA’s Integrated Multi-satelliE Retrievals for GPM (IMERG) data estimated rainfall totals over the eastern Gulf of Mexico and southeastern U.S. for the duration of Cindy. Notably, rainfall in excess of 10 inches occurred well east of Cindy’s center over the northeastern Gulf of Mexico and along the Gulf coast from southeastern Louisiana to the western Florida Panhandle.

The peak of the Atlantic hurricane season is still to come, so it’s important to remain vigilant for any approaching tropical storm. Whether you are concerned with a tropical storm tracking toward the eastern Caribbean, or a major hurricane developing in the Gulf of Mexico, our meteorologists are available 24/7 to keep you ahead of the storm.

Contact us to learn more about our online and mobile interactive tracking tools.

Why we treat some Invest areas like tropical storms…

It’s critical that offshore operators are aware of tropical hazards well in advance of tropical storm development. 

Tropical Storm Bill, June 16 2015
Infrared Satellite of Tropical Storm Bill approaching the Texas coast.

Two years ago we were monitoring an area of disturbed weather near the Yucatan Peninsula. At the time, forecast models indicated that a trough of low pressure would move offshore the Yucatan within the next 24 hours and form a closed circulation as it tracked northwest toward the Texas coastal bend. Hurricane Carlos, off the southern coast of Mexico, was feeding in abundant tropical moisture from the Pacific, aiding thunderstorm development. Over the next few days, upper-level winds over the Gulf weakened, enhancing convection and improving the low-level circulation. Within 36 hours a tropical storm was designated over the northern Gulf of Mexico. About 15 hours later, Tropical Storm Bill made landfall over Matagorda Island, Texas with maximum sustained winds near 60 mph.Read More »

Tropical development in the Gulf this weekend?

With hurricane season officially underway today in the Atlantic basin, all eyes are on thunderstorms streaming northward across the Gulf of Mexico. This convection is associated with Tropical Storm Beatriz off the coast of Mexico in the East Pacific. Although Beatriz is not a direct threat to the Gulf, tropical moisture from this storm will continue to provide deep convection across the southern Gulf. This moisture will interact with an existing surface trough over the Bay of Campeche providing the potential for low pressure to develop over the weekend, but there are limiting factors for tropical development.

Regardless of tropical development, one key tropical ingredient is present: atmospheric moisture. The higher the moisture content in the atmosphere, the greater chance for deep, persistent convection which furthermore enhances development within tropical systems. Meteorologists analyze a parameter known as PWAT, Precipitable Water, to gauge atmospheric moisture content. NOAA defines PWAT as the “measure of the depth of liquid water at the surface that would result after precipitating all of the water vapor in a vertical column over a given location”. Imagine having a column of water vapor, from Earth’s surface to the top of the atmosphere, and squeezing that column of air until all the water fell out (very similar to wringing out a sponge). The resulting measure of water, calculated in inches, is a good indicator of how much rainfall a region could see.

PWAT Animated Loop
Simulation of PWAT values for the Gulf of Mexico valid June 2-4, 2017.

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Hurricane Preparedness: Offshore Operations

Tropical cyclones have significant impacts on marine operations worldwide. Prior to experiencing tropical cyclone threats, offshore facilities must secure equipment, shut-in wells, and evacuate personnel. Operations can remain shut down for extended periods in the event that an offshore platform or rig is damaged or destroyed. Damaged pipelines along the seafloor are a common cause of interruptions to oil and gas supply.

To prevent structural damage and spills, control costs, and ensure the safety of personnel, accurate weather forecasts and advanced notification of tropical hazards are paramount. Even a weak tropical cyclone can produce hazardous weather conditions and put coastal and offshore operators at risk. Be sure to determine your exposure to the risks associated with tropical cyclones before the start of this Atlantic hurricane season.

Wilkens Weather provides a suite of online and mobile tracking tools to warn our customers of these risks. To be confident that you’re prepared this hurricane season, trust in the tropical expertise and tools provided by WWT: Read More »

2016 West Pacific Tropical Season Recap

The 2016 West Pacific tropical season was near normal with 24 named storms, according to the Joint Typhoon Warning Center (JTWC). A total of 13 storms reached typhoon status and 6 became super typhoons. This fell short of the annual average of 16.5 storms reaching at least typhoon status.

Typhoon Nepartak became the first named storm of the year on July 3, breaking a 199-day streak of no named storms across the basin.This tied the 1997-1998 interval for the longest number of days to pass without a named storm. Nepartak was classified as a super typhoon on July 6 and maintained one-minute sustained winds of 152kts (175mph) for 18 hours while tracking northwest toward Taiwan.The storm weakened to 130kts (150mph) before making landfall over Taiwan on July 8 (Taiwan local time). Continued weakening occurred as Nepartak tracked across mountainous terrain, and the storm made its final landfall over China on July 9 as a tropical storm.

Super Typhoon Nepartak Radar Taiwan
Super Typhoon Nepartak’s heavy rainbands approach Taiwan

Other significant storms to impact Taiwan in 2016:

  • Super Typhoon Meranti made a nearly direct hit to Taiwan on September 14. The extended time over water promoted further intensification and a peak intensity of 165kts (190mph) over the Luzon Strait.
  • Typhoon Megi intensified over the Philippine Sea and made landfall over northeastern Taiwan on Tuesday, September 27 with maximum sustained winds near 115kts (132mph).
NOAA Satellite Super Typhoon Meranti Taiwan
Eye of Super Typhoon Meranti nearing the southern tip of Taiwan

The northern South China Sea was also an active area in 2016. Marine assets offshore Hong Kong took direct hits from two typhoons, Nida and Haima, and Typhoon Sarika passed just to their south. Here are a few details on these storms:

  • Typhoon Nida developed east of the Philippines and reached typhoon status north of Luzon. Nida intensified to 80kts (92mph) before making landfall east of Hong Kong in Dapeng Peninsula on August 2. Storm photos can be found here.
  • Typhoon Sarika began as a tropical wave southeast of the Philippines. Sarika reached its peak intensity of 115kts (132mph) before making its first landfall in Luzon. The cyclone moved quickly across the Philippines and the South China Sea, and made a second landfall across Hainan Island. The storm continued to weaken as it made its third and final landfall near the Vietnam/China border.
  • Super Typhoon Haima caused mass destruction across the Philippines just days after Sarika. Photos and video footage from the devastating storm can be viewed here. Haima ranked as the third strongest typhoon of the season with maximum sustained winds of 145 kts (167mph). The storm weakened to 122kts (140mph) before making landfall over Luzon on October 19.

UW-Madison CIMSS Twitter Typhoon Haima

While around half of 2016 West Pacific typhoons followed a general East to West track, the other half were able to find a weakness in the steering ridge and curve northward. Mainland Japan would be directly impacted by four of these typhoons (Nepartak, Mindulle, Lionrock, and Malakas); however, the majority of these weakened significantly before making landfall. Typhoon Lionrock was the most unique system of the season given its length of life and erratic track.

Track map of Typhoon Lionrock. Points represent the storm’s location at 6-hour intervals. Color scale based on Saffir-Simpson hurricane wind scale. Tracking data provided by NOAA.

Of the main cyclones to impact the mid-latitudes, Typhoon Chaba tracked the closest to offshore interests in the Korea Strait and Sea of Japan. Chaba reached super typhoon intensity upon entering the East China Sea on October 3 and then gradually weakened as it moved south of Busan, South Korea. Chaba moved across northern Japan as an extratropical cyclone.

Just as the season’s first named storm became a super typhoon, the season’s final named storm also became a super typhoon. Nock-ten developed near Yap Island on December 21st. Nock-ten would become the strongest tropical cyclone ever recorded worldwide on Christmas Day. Nock-ten made landfall across the Philippines on the evening of Christmas Day before emerging across the South China Sea the next day. Nock-ten dissipated in the Northeast Monsoon on December 28th, bringing an end to the 2016 West Pacific tropical season.

WWT tracked all of these storms for stationary assets and marine transits across the West Pacific and Southeast Asia.

WWT West Pacific Tropical Summary
You can always check the latest forecast on the WWT mobile app.

About Wilkens Weather Tropical Weather Guidance

Wilkens Weather provides a variety of tropical products to monitor potential development, forecast tracks, and anticipated intensities of tropical systems in this region. Tropical service options include tropical cyclone formation alerts (TCFAs) and tropical cyclone bulletins. Once tropical cyclone bulletins commence, clients are provided a wealth of resources to review the storm data and potential impacts on their site-specific locations. The interactive tropical tools on our website and Mobile App provide clients with the flexibility to focus on the needs of their operation.

Site-specific storm bulletins with alert areas are also available and may be customized to the needs of a current project or operation. 

 

Tropical Button

South China Sea Monsoon Low

WWT Satellite Monsoon LowOver the past several days, an area of low pressure (Invest 91W) developed within the monsoon trough/ITCZ, generating bands of showers and thunderstorms across the southern South China Sea. As a result, fresh winds extended to the Borneo coast and Malay Peninsula over the weekend. Strong to near-gale force northerly winds also occurred along the northwest side of the low when it intensified this morning. Global models often underdo monsoon winds within these lows and these systems should always be monitored closely for tropical development. Read More »

Major Hurricane Wilma, 11 years later

CIMSS NOAA Satellite Montage WilmaHurricane Wilma was the 21st named storm of the infamous 2005 Atlantic hurricane season. From her formation on October 15th to her demise on the 26th, Wilma would become one of the most memorable hurricanes in Atlantic basin history. As the 4th category 5 hurricane of the year, Wilma would become a monstrous bookend to an incredible, record-setting season.Read More »

A quick mid-year review of the 2016 Atlantic hurricane season

To this date, the 2016 Atlantic hurricane season has recorded twelve named storms and one tropical depression, including Hurricane Alex from January. By the end of September we will likely see the next storm develop as signs of strengthening continue with an active tropical wave (97L). Currently, 97L is located roughly 470 miles east-southeast of Barbados tracking to the west about 15-20 knots. The tropical wave will either intensify into Tropical Depression Fourteen or Tropical Storm Matthew. The 30-year average (1981-2010) for the Atlantic basin consists of twelve named storms. With two months left in the 2016 Atlantic hurricane season, one can conclude that an above average recording of named storms will likely occur.

midyear-review-graphic

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Remembering 2005’s Major Hurricane Rita in the Gulf of Mexico

Hurricane Rita made landfall in extreme southwestern Louisiana on September 24th, 2005 with an intensity of 100 knots (Category 3). About 48 hours earlier, Rita was a Category 5 hurricane with a minimum pressure of 895mb, the fourth-lowest central pressure on record in the Atlantic basin. Although Rita’s history was overshadowed by Katrina, which made landfall just a few weeks earlier, the storm provided a unique challenge for both forecasters and public officials.

NASA Rita Terra satellite_20050918
NASA satellite image of Tropical Depression Eighteen over the Bahamas on Sept. 18, 2005

Rita originated as a weak tropical wave off the western coast of Africa on September 7th. The Saharan Air Layer, commonly known as Saharan Dust, and high levels of wind shear prevented the wave from producing thunderstorm activity as it moved across the tropical Atlantic. Conditions became more favorable for development later in the month as the wave reached the Bahamas. A tropical depression formed on September 17th and the system was designated as Tropical Storm Rita the following afternoon.

Rita continued to strengthen as it tracked across the Florida Straits, reaching Category 2 status by the time it reached the Gulf of Mexico on the 20th. Over the next 18 hours, the storm underwent rapid intensification over the Loop Current, becoming a Category 5 storm with an intensity of 145 knots. Rita continued to intensify and recorded an incredible 70mb drop in central pressure in a 24-hour period. At maximum intensity on September 22nd, Rita’s central pressure was estimated to be 895mb with winds near 155 knots (178 mph).

NASA Aqua satellite_20050923
NASA satellite image showing Hurricane Rita approaching the Gulf coast on Sept. 23, 2005

Thankfully for the residents of the Gulf Coast, Rita did not maintain its unprecedented strength as it pushed ashore. After moving past the Loop Current the system gradually weakened to a Category 3 before making landfall near Sabine Pass as a major hurricane. Hurricane force winds spread over 150 miles from the center while tropical storm force winds stretched as far north as the Louisiana/Arkansas border. Peak storm surge of nearly 17 feet occurred on the eastern side of Rita, causing severe flooding in several parishes in southwestern Louisiana. Heavy rainfall worsened this situation, with most of southwestern Louisiana receiving 7-10 inches, with some areas receiving over 15.

Rita continued to progress northeastward after being absorbed by a front across the central United States. That accelerated movement prevented a significant flood event in the Ohio River valley, with most rainfall totals being limited to around 2-3 inches as the remnant low raced toward the Great Lakes.

Although meteorological impacts to extreme southeastern Texas and southwestern Louisiana were unforgettable, only seven direct deaths occurred as a result of Rita in the United States. Most citizens in the southwestern Louisiana coastal areas evacuated before the worst impacts arrived, likely significantly reducing the death toll in that area.

The majority of the storm’s causalities occurred during the evacuation iWWT Hurricane Rita Wind Speed Analysisn Texas, where poor planning and heightened fears, resulting from Katrina, resulted in mass gridlock around Houston. Over 100 Texans perished due to accidents, fires, and health related issues during the evacuation. Much work has since been done to streamline the evacuation process from the Houston area, including the streamlining of the contraflow process on major highways exiting the city.

 

 

Wilkens Weather tracks 8 storms in the West Pacific this August

WWT West Pacific Tropical Summary

The West Pacific Ocean was quite active last week, with 2-3 concurrent storms. This recent tropical activity, while not unprecedented, has been above average.  Over the past several weeks, an upward Madden-Julian Oscillation phase extending across the West Pacific coupled with the existing monsoon trough.  This pattern has yielded eight named storms since August 3, the most recent being Typhoon Lionrock. Read More »

Spaghetti… what? Forecast models broken down

By now I’m sure you have seen the “spaghetti plot”- ensemble of forecast models-regarding Tropical Depression Nine. If you’re not a meteorologist or everyday weather guru, then you have every right to be confused by this graphic of overwhelming lines. With a little background on the models, you’ll be sure to impress your coworkers when they begin to bring up TD Nine or soon to be Tropical Storm Nine.
Read More »

Wilkens Weather releases new tropical cyclone tracking tools for its iOS mobile app

Wilkens Weather Technologies Mobile App

Houston, USA (April 25, 2016) – Just in time for the 2016 Atlantic Hurricane season, Wilkens Weather Technologies® (WWT) has released a new version of its iOS Mobile App. The latest version contains a series of major upgrades to the app’s Interactive Weather Map, including a new Threat Profile feature which is now embedded within the global tropical cyclone tracking tools, allowing immediate threat identification of tropical systems with respect to customer assets.

“From real-time weather display to our cyclone tracking feature set, WWT effectively informs users of the impacts from an approaching tropical system,” said Ryan Fulton, program manager at Wilkens Weather Technologies. Read More »