Team Evaluates Possible Lightning Strike Near Pad

The space shuttle launch team is evaluating a possible lightning strike within one third of a mile from Launch Pad 39A at NASA's Kennedy Space Center. Engineers will review data to determine if the lightning affected space shuttle Atlantis or any of the pad's ground support equipment. A continuing band of thunderstorms has prevented teams from conducting a detailed pad inspection, which must be performed before the Rotating Service Structure can be rolled back from the shuttle.

After the rollback, the teams will continue work that must be performed before fueling Atlantis' external tank early tomorrow morning. The rollback originally was planned for 2 p.m. EDT.

At this morning's briefing, Shuttle Weather Officer Kathy Winters reported that the launch weather forecast remains unchanged, with a 30 percent chance of favorable weather for the 11:26 a.m. liftoff. The forecast is a more favorable 80 percent when the filling of the huge external fuel tank is set to begin.

At 5 a.m. this morning, the countdown entered a planned hold at the T-11 hour mark, and will resume at 7:01 p.m. tonight.

The astronauts had an early wakeup call as they continue to prepare for tomorrow's launch of Atlantis on the STS-135 mission to the International Space Station.

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Hurricane Season 2011: Tropical Depression 3E (Eastern Pacific)

NASA's TRMM Satellite Sees Third Tropical Depression Form in E. Pacific

The Tropical Rainfall Measuring Mission (TRMM) satellite passed over an area of low pressure in the eastern Pacific Ocean south of Mexico on July 7, 2011 at 0234 UTC (July 6 at 10:34 EDT) and captured rainfall in the newly formed third tropical depression of the hurricane season.

The National Hurricane Center (NHC) in Miami, Florida upgraded this area of low pressure to a tropical depression at 1500 UTC (8:00 a.m. PDT). At that time, maximum sustained winds were near 35 mph (55 km/h) and the center was located near 14.8 North and 101.2 West, which is about 355 miles (570 km) southeast of Manzanillo, Mexico. Tropical Depression 3E is moving to the west-northwest near 13 mph (20 km/h) and has a minimum central pressure of 1005 millibars.

The rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data was overlaid on an infrared image from TRMM's Visible and InfraRed Scanner (VIRS) by Hal Pierce of SSAI at NASA's Goddard Space Flight Center in Greenbelt, Md. The analysis showed that there were only a few areas of moderate to heavy rainfall associated with the developing tropical depression at the time of this TRMM orbit.

The strongest rainfall (about 2 inches/50 mm per hour) appeared in isolated areas south of the center of circulation. The moderate rainfall was falling at a rate between .78 and 1.57 inches (20 and 40 mm) per hour.

Conditions are expected to be favorable for the depression to become a tropical storm within the next couple days, and when it does, it would be renamed "Calvin." The storm is expected to remain over open waters well south of the coast of southwestern Mexico.

Text credit:Hal Pierce, SSAI/NASA's Goddard Space Flight Center, Greenbelt, Md.

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La Niña's Exit Leaves Climate Forecasts in Limbo

It's what Bill Patzert, a climatologist and oceanographer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., likes to call a "La Nada" – that puzzling period between cycles of the El Niño-Southern Oscillation climate pattern in the Pacific Ocean when sea surface heights in the equatorial Pacific are near average.

The comings and goings of El Niño and La Niña are part of a long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator. For the past three months, since last year's strong La Niña event dissipated, data collected by the U.S.-French Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite have shown that the equatorial Pacific sea surface heights have been stable and near average. Elsewhere, however, the northeastern Pacific Ocean remains quite cool, with sea levels much lower than normal. The presence of cool ocean waters off the U.S. West Coast has also been a factor in this year's cool and foggy spring there.

The current state of the Pacific is shown in this OSTM/Jason-2 image, based on the average of 10 days of data centered on June 18, 2011. The image depicts places where Pacific sea surface height is higher (warmer) than normal as yellow and red, while places where the sea surface is lower (cooler) than normal are shown in blue and purple. Green indicates near-normal conditions. Sea surface height is an indicator of how much of the sun's heat is stored in the upper ocean.

For oceanographers and climate scientists like Patzert, "La Nada" conditions can bring with them a high degree of uncertainty. While some forecasters (targeting the next couple of seasons) have suggested La Nada will bring about "normal" weather conditions, Patzert cautions previous protracted La Nadas have often delivered unruly jet stream patterns and wild weather swings.

In addition, some climatologists are pondering whether a warm El Niño pattern (which often follows La Niña) may be lurking over the horizon. Patzert says that would be perfectly fine for the United States.

"For the United States, there would be some positives to the appearance of El Niño this summer," Patzert said. "The parched and fire-ravaged southern tier of the country would certainly benefit from a good El Niño soaking. Looking ahead to late August and September, El Niño would also tend to dampen the 2011 hurricane season in the United States. We've had enough wild and punishing weather this year. Relief from the drought across the southern United States and a mild hurricane season would be very welcome."

Jason-2 scientists will continue to monitor Pacific Ocean sea surface heights for signs of El Niño, La Niña or prolonged neutral conditions.

JPL manages the U.S. portion of the OSTM/Jason-2 mission for NASA's Science Mission Directorate, Washington, D.C.

For more information on NASA's ocean surface topography missions, visit: http://sealevel.jpl.nasa.gov/missions/.

To view the latest Jason-1 and OSTM/Jason-2 data, visit http://sealevel.jpl.nasa.gov/science/elninopdo/latestdata/.

Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

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Hurricane Season 2011: Tropical Storm Arlene (Atlantic Ocean/Caribbean Sea)

NASA Satellites See Strong Thunderstorms, Heavy Rain as Arlene Nears Landfall

Two different NASA satellites provided valuable information about the hundreds of thunderstorms that make up Tropical Storm Arlene as it nears landfall in northeastern Mexico. NASA's Aqua satellite measured cloud top temperatures giving clues about the strength of storms, while the TRMM satellite measured rainfall rates and cloud heights. All of this data is useful to forecasters in predicting Arlene's next moves.

The Tropical Rainfall Measuring Mission (TRMM) satellite had a good look at Arlene when it passed above on June 29, 2011 at 0502 UTC (0:02 AM CDT). At that time Arlene's winds were estimated to be about 34 knots (~39 mph) indicating that it was barely a tropical storm.

TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data showed that Arlene was getting better organized and contained scattered heavy thunderstorms dropping rain at a rate of over 50 mm/hr (~2 inches). Some of the heaviest rainfall was not near the center of Arlene's circulation but was in feeder bands over land along the southwestern Gulf of Mexico. A 3-D analysis of Arlene's vertical structure using TRMM PR revealed that very powerful thunderstorms in a feeder band over the southeastern Yucatan Peninsula reached to heights of 17 km (~10.6 miles).

NASA's Aqua satellite passed over Tropical Storm Arlene on June 29, 2011 at 08:05 UTC (4:05 a.m. EDT). At that time, the Atmospheric Infrared Sounder (AIRS) instrument showed that most of Arlene's heaviest thunderstorms and coldest cloud top temperatures (-63F/-52C) were over the waters of the Gulf of Mexico. That data matched with the TRMM data that showed the heaviest rainfall was over open water.

At 1 p.m. EDT on June 29, Arlene's maximum sustained winds had increased to 50 mph (85 kmh). It was located just 95 miles (155 km) east of Tuxpan, Mexico and 150 miles east-southeast of Tampico. That put Arlene's center near 21.1 North and 95.9 West. It was moving west near 8 mph (13 kmh) and had a minimum central pressure of 1000 millibars. A hurricane watch is in effect for the coast of eastern Mexico from Barra De Nautla Northward to La Cruz and a tropical storm watch extends farther along the coast. For updates, visit: www.nhc.noaa.gov.

Residents in the area of the watches should prepare for gusty winds, heavy rainfall and rough surf.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.

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What's to Blame for Wild Weather? "La Nada"

Such sheets of fire, such bursts of horrid thunder,

Such groans of roaring wind and rain, I never

Remember to have heard; man's nature cannot carry

The affliction nor the fear … from Shakespeare's Tragedy of King Lear

June 21, 2011: Record snowfall, killer tornadoes, devastating floods: There’s no doubt about it. Since Dec. 2010, the weather in the USA has been positively wild. But why?

Some recent news reports have attributed the phenomenon to an extreme "La Niña," a band of cold water stretching across the Pacific Ocean with global repercussions for climate and weather. But NASA climatologist Bill Patzert names a different suspect: "La Nada."

"La Niña was strong in December," he says. "But back in January it pulled a disappearing act and left us with nothing – La Nada – to constrain the jet stream. Like an unruly teenager, the jet stream took advantage of the newfound freedom--and the results were disastrous."

La Niña and El Niño are opposite extremes of a great Pacific oscillation. Every 2 to 7 years, surface waters across the equatorial Pacific warm up (El Niño) and then they cool down again (La Niña). Each condition has its own distinct effects on weather.

The winter of 2010 began with La Niña conditions taking hold. A "normal" La Niña would have pushed the jet stream northward, pushing cold arctic air (one of the ingredients of severe weather) away from the lower US. But this La Niña petered out quickly, and no El Niño rose up to replace it. The jet stream was free to misbehave.

"By mid-January 2011, La Niña weakened rapidly and by mid-February it was 'adios La Niña,' allowing the jet stream to meander wildly around the US. Consequently the weather pattern became dominated by strong outbreaks of frigid polar air, producing blizzards across the West, Upper Midwest, and northeast US."1

The situation lingered into spring -- and things got ugly. Russell Schneider, Director of the NOAA-NWS Storm Prediction Center, explains:

"First, very strong winds out of the south carrying warm, moist air from the Gulf of Mexico met cold jet stream winds racing in from the west. Stacking these two air masses on top of each other created the degree of instability that fuels intense thunderstorms."

Extreme contrasts in wind speeds and directions of the upper and lower atmosphere transformed ordinary thunderstorms into long-lived rotating supercells capable of producing violent tornadoes.2

In Patzert's words, "The jet stream -- on steroids -- acted as an atmospheric mix master, causing tornadoes to explode across Dixie and Tornado Alleys, and even into Massachusetts."

All this because of a flaky La Niña?

"La Niña and El Niño affect the atmosphere's energy balance because they determine the location of warm water in the Pacific, and that in turn determines where huge clusters of tropical thunderstorms form," explains Schneider. "These storms are the main energy source from the tropics influencing the large scale pattern of the jet stream that flows through the US."

In agreement with Patzert, he notes that the very strong and active jet stream across the lower US in April "may have been related to the weakening La Niña conditions observed over the tropical Pacific."

And of course there's this million dollar question: "Does any research point to climate change as a cause of this wild weather?"

"Global warming is certainly happening," asserts Patzert, "but we can't discount global warming or blame it for the 2011 tornado season. We just don't know ... Yet."3

What will happen next? And please don't say, "La Nada."

Author: Dauna Coulter | Editor: Dr. Tony Phillips | Credit: Science@NASA

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NASA Chat: Striking Up a Conversation About Lightning

June is Lightning Safety Awareness Month. Lightning is the number two killer of severe weather. Flooding is number one. A lot of people think if it is sunny or maybe just a few clouds around and you hear thunder, it is okay to stay outside until you actually see the lightning. That is not true. If you hear thunder when you are outside, that means that lightning is close enough to strike you!

On Thursday, June 23, from 7-8 p.m. EDT, Dr. Richard Blakeslee, atmospheric research scientist at NASA's Marshall Space Flight Center in Huntsville, Ala., will answer your questions about lightning safety, the global distribution and frequency of lightning occurrence as well as some of its physical characteristic, the relationship of lightning to severe storms and weather (e.g., lightning rate changes may serve as a "pre-cursor" or advanced indicator to later severe weather at the ground such as tornadoes), and other lightning research topics such as lightning-hurricane relationships and terrestrial gamma ray burst.

Joining the chat is easy. Simply visit this page on Thursday, June 23 a few minutes before the start of the chat. The chat window will be open at the bottom of this page: http://www.nasa.gov/connect/chat/lightning_chat.html. Simply log in and be ready to ask questions at 7 p.m. EDT.

See you in chat!

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Hurricane Season 2011: System 93L (Atlantic Ocean)

Atlantic Hurricane Season Sticks to the Calendar: System 93L

Hurricane season starts today, June 1, in the Atlantic Ocean and the tropics are paying attention to the calendar. The GOES-13 satellite has been capturing images of a low pressure area that formed off the North Carolina coast yesterday and is now located off of the northeastern Florida coast.

The low pressure area, also known as System 93L appears somewhat elongated, almost rounded area of clouds on the satellite imagery today, stretching from southwest to northeast. The Geostationary Operational Environmental Satellite called GOES-13 has been capturing imagery of the low since it formed. The visible image from June 1 at 1445 UTC (10:45 a.m. EDT) has some shadows in the middle of the storm, which indicate that there are some towering, strong thunderstorms near the circulation center that are casting shadows onto the lower thunderstorms.

NASA's GOES Project, located at NASA's Goddard Space Flight Center, Greenbelt, Md. creates imagery and animations of GOES satellite data. The GOES series of satellites are operated by the National Oceanic and Atmospheric Administration. To see the latest animation of the GOES satellite imagery in "Hurricane Alley" in the Atlantic Ocean visit: http://goes.gsfc.nasa.gov and click on "Hurricane Alley HDTV" on the top right side of the NASA GOES webpage.

At 8 a.m. EDT, the center of the low was about 200 miles east of Jacksonville, Florida and was moving west-southwest near 20 mph. It is forecast to move over northern Florida later today toward the Florida Panhandle. It has a medium chance of becoming the Atlantic hurricane season's first tropical depression in the next 24 hours.

The low does mean some scattered strong thunderstorms are in the forecast for northeastern Florida and isolated thunderstorms in southeastern Georgia today. The National Weather Service noted that some of the thunderstorms could contain wind gusts to 50 mph, small hail, frequent cloud to ground lightning and heavy rainfall.

In addition to the threat of severe thunderstorms, the low is also creating rip currents and building swells along the eastern Florida beaches. For updates, visit NASA's Hurricane Web Page at: www.nasa.gov/hurricane.

If the low does intensify into a tropical storm it would receive the name Arlene. However, it must first reach tropical depression status. Even if it doesn't become a depression it still means severe weather for northeastern Florida and southeastern Georgia today.

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Tornado Challenges Satellite Damage Track Detection Techniques

The Short-term Prediction Research and Transition, or SPoRT, team has used satellite data from the North Alabama region to identify tornado damage from the April 27th super storm outbreak.

NASA's Terra satellite, part of the Earth Observing System of satellites, captured images of the damage path. An instrument aboard Terra called the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER, was used to discern vegetation contrasts over the region.

"This is the first time ASTER data has been applied to such a massive outbreak of storms," said Gary Jedlovec, atmospheric scientist at Marshall Space Flight Center. "The usefulness of satellite information in providing improved accuracy along with damage assessment in severe weather events continues to evolve."

The tornado track signature observed by ASTER is seen as a disruption in the vegetation or other reflective surfaces over a region caused by tornado winds. Uprooted trees quickly stop the process of photosynthesis and change color -- this is easily detected by satellite.

However, detecting damage in areas outside of heavy forestland is challenging.

In Madison and Limestone counties much of the area scarred by the tornadoes are agricultural in nature. Fields are either pasture land or row crops -- therefore the effect of tornado winds is minimal and the mark on satellite imagery is suppressed.

While this indicates a limitation to the use of this particular image analysis for tornado track detection over primarily agricultural land use, the SPoRT team is exploring the use of temperature channels from ASTER to better identify damage marks on Earth's surface. Terra/ASTER is a joint activity between NASA's Science Mission Directorate Earth Science Division and Japan's Ministry of Economy, Trade and Industry. Terra is one of 14 NASA satellites that look at the Earth to study and understand changes in the Earth system and provide societal benefits.

The NASA image created by the Short-term Prediction and Research Transition or SPoRT project at the Marshall Space Flight Center in Huntsville, using data provided courtesy of NASA Goddard Space Flight Center, the Land Processes Distributed Active Archive Center, Japan’s Earth Remote Sensing Data Analysis Center, the Ministry of Economy, Trade and Industry, along with the Japan Research Observation System Organization.

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Countdown to Endeavour: Lightning Protection Is a Must

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

As launch day approaches, we are expecting thunderstorms to impact the Florida East Coast, some which could produce severe weather. When meteorologists use the word “severe weather,” we aren’t talking about the everyday, afternoon thunderstorms. Severe weather indicates thunderstorms could produce winds 50 knots or greater, hail, and/or tornadic activity.  If severe weather occurs, the Shuttle team inspects the vehicle to ensure weather has not caused any damage. Also, if we have close lightning strikes, we provide detailed lightning data to ensure the team knows if the strike potentially caused damage to the shuttle or any launch pad ground systems.

Lightning protection for launch complexes is a must, and the Kennedy Space Center and Cape Canaveral Air Force Station launch pads have a significant amount of lightning protection to protect vehicles and launch pad structures from damage due to lightning strikes. For the Shuttle launch pad, a 1-inch thick grounded wire stretches 1000 feet each direction from the 80-foot fiberglass mast at the top of the structure. A 4-foot lightning rod extends from the mast. All structures on the pad are grounded, including the Mobile Launch Platform. The hydrogen, oxygen, and water storage tanks provide their own ground, and a gridwire system protects hypergolic fuel storage areas. Overall, the area is well protected to minimize damage from lightning.

To learn more about lightning, check out the National Severe Storms Laboratory.

Luckily, by launch day, the weather should be off to our east, and our main concerns are a low-cloud ceiling and a crosswind at the Shuttle Landing Facility for abort landing weather. Wish us luck!

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Flooding From Mississippi River Levee Breach

The U.S. Army Corps of Engineers detonated explosives at the Birds Point levee near Wyatt, Missouri, at 10:02 p.m. on May 2, 2011. Water from the intentional breach flooded a 130,000-acre stretch of land. Two more breaches were detonated on May 3 and 5. This image from the Advanced Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft shows the resultant flooding of farmland west of the Mississippi 20 miles (32 kilometers) south of the levee breach. On the image, vegetation is displayed in red, bare fields in gray and water in blue. The image covers an area of 30.7 by 39 miles (49.5 by 63 kilometers), and is located near 36.5 degrees north latitude, 89.4 degrees west longitude.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet, or about 15 to 90 meters, ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and, measuring surface heat balance.

Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

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Hurricane Season 2011: Tropical Storm Aere (Western North Pacific Ocean)

NASA Satellite Sees Tropical Storm Aere Leave Deadly Path in Philippines

NASA's Aqua satellite flew over what has grown into Tropical Storm Aere every day this past weekend, as it dropped heavy rainfall, created mudslides and took lives in the eastern Philippines. Infrared satellite imagery from Aqua revealed the strong thunderstorms responsible for the heavy rainfall.

In a time series of imagery from NASA's Aqua satellite, the Atmospheric Infrared Sounder (AIRS) instrument showed Tropical Storm Aere's progress over the weekend on May 6 at 16:59 UTC, May 7 at 05:29 UTC, and Monday, May 9 at 05:17 UTC. Infrared data basically takes the temperature of a tropical cyclone's clouds and the coldest areas indicate the strongest thunderstorms and areas of heaviest rainfall. Those coldest cloud temperatures (highest, strongest thunderstorms) and are as cold as or colder than -63F/-52C.

On May 6, when Aere was a tropical depression (03W) it appeared to be more concentrated with the heaviest rainfall and strongest thunderstorms over open ocean. By Saturday, May 7, those heavy rains overspread land areas. On Monday, May 9, the circulation seemed to become weaker and convection (rapidly rising air that forms the thunderstorms) seemed to appear more scattered and has decreased in AIRS imagery.

Warnings are still in effect in the Philippines as Aere continues to move north. Public storm warning signal #1 is in effect in the following provinces: Luzon: Quirino, Ifugao, Mt. Province, Kalinga, Apayao and Batanes. Public storm warning signal #2 is in effect for: Luzon: Cagayan, Babuya and Calayan.

The four fatalities caused by Tropical Storm Aere occurred in Balatan, Camarines Sur where a landslide took three lives, and another person drowned in floodwaters in Leyte. Radio reports also noted that nine people at the Manila airport were injured when lightning struck a plane on the tarmac on May 7.

On May 9 at 1500 UTC (11:00 a.m. EDT), Tropical Storm Aere, formerly known as Tropical Depression 03W continued to bring rainfall to the Philippines. Its center was about 215 miles (346 km) north-northeast of Manila near 18.0 North and 122.3 East. It was moving north near 9 knots and had maximum sustained winds near 40 knots (46 mph/74 kmh). Aere, known locally in the Philippines as "Bebing," was creating rough waves on eastern-facing shores, as wave heights were reaching up to 13 feet (4 meters).

Aere is now moving along the east coast of Luzon Island and the Joint Typhoon Warning Center forecasts the tropical storm to soon move into the open waters south of Taiwan and then move northeast through the Northwestern Pacific Ocean. Aere is expected to become extratropical south of Japan.

Text Credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, MD

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Hurricane Season 2011: System 93W (Western North Pacific Ocean)

Tropically-Speaking - NASA Satellite Imagery Shows Big System 93W Developing

System 93W is a large low pressure area in the Western North Pacific Ocean that appears poised for tropical development in NASA satellite imagery. Improved circulation and warm sea surface temperatures provide some hints of a strengthening storm.

The Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite captured both an infrared and visible image of System 93W on May 4 at 01:53 UTC (May 3 at 9:53 p.m. EDT). The width of the AIRS image track is 1056 miles (1700 km), the width of System 93W appears to be approximately 800 miles (1,287 km) from west to east.

The AIRS imagery showed an improved low-level circulation center and unorganized, but deep convection. Convection is rapidly rising air that forms the thunderstorms that power a tropical cyclone.

The strongest convection appeared around the center of System 93W's circulation where cloud-top temperatures were measured to be as cold as or colder than -63F/-52C. Cloud-top temperatures are important because they tell forecasters how high thunderstorms are, and the higher the thunderstorm, the colder the cloud tops and the more powerful the thunderstorms.

Today, May 4, the low pressure area was located about 180 nautical miles east of Mindanao, the Philippines today, near 9.4 North and 129.0 East. Its surface winds are estimated between 15 and 20 knots. The system is moving west-northwestward at 11 knots (~12 mph/20 kmh).

The Joint Typhoon Warning Center (JTWC) noted that a buoy about 100 nautical miles to away reported a minimum central pressure of 1005 millibars. With sea surface temperatures near 84F (29C), the waters are warm enough to support development into a tropical storm. Wind shear is also low, which will help with development. The JTWC gives System 93W a good chance for development into a tropical storm over the next 24 hours.

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Countdown To Endeavour: Brush Fire at Kennedy Space Center

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

Wednesday was a busy day. The day started with issuing the Ice Team Forecast update and the L-2 Day launch forecast. Then I briefed weather at the L-2 day Shuttle Mission Management Team (MMT) meeting. Following the MMT meeting, it was off to the press site for a press conference with Mike Moses, the Launch Integration Manager, and Mike Leinbach, the Launch Director. I am always surprised I get invited to this press briefing, but since weather causes approximately 50% of launch scrubs, NASA public affairs asks me to brief the weather and be available for any questions.

After the press briefing Wednesday, I saw this fire at Kennedy Space Center about 3 nautical miles from the Shuttle launch pad. When fires like this occur, the 45th Weather Squadron gets calls from Kennedy Space Center personnel for current and forecast weather information, particularly wind speed and direction, so actions can be taken to protect personnel and resources. Also, cumulus clouds formed above the fire which had our launch team thinking about our smoke plume rule in the lightning launch commit criteria.  On launch day, if a cumulus cloud formed from a fire and moved into the path of the launch, weather would be RED for the Smoke Plume rule until 60 minutes after the cloud detached from the smoke plume. As you can imagine, sometimes it can be difficult to tell when a cumulus cloud detaches from the smoke plume, and unless we are clearly convinced a lightning launch commit criteria (PDF) is not violated, weather is RED for launch.

A Solid Rocket Booster Recovery operation in process

Thursday, we meet with the Solid Rocket Booster (SRB) recovery team to give them a weather outlook before they depart. It takes the ships, the Freedom Star and Liberty Star, about 24 hours to reach the SRB Recovery area. Weather is going to be a bit rough for their trip Thursday as a cold front moves through, but nothing that would prevent them from getting to the area on time. On launch day, winds will be from the north in the SRB recovery area, and seas 5 to 6 feet—not a smooth day, but well within their weather constraints.

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Countdown to Endeavour: Rockets Can Trigger Lightning Strikes

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

I took a picture of this cumulus cloud from the press site on Tuesday morning after the countdown status briefing. Clouds like this formed along the sea breeze due to our moist atmosphere. Although these clouds are normally harmless, on launch day the 45th Weather Squadron Launch Weather Team actually pays close attention to the height of any cumulus clouds like these that develop within 10 nautical miles of the launch pad. If a cumulus cloud gets tall enough, it may violate our cumulus cloud rule, one of the many rules in our Launch Commit Criteria. The purpose of the cumulus cloud rule is to prevent the threat of triggering a lightning strike when launching into elevated electric fields in the atmosphere. Fortunately, we do not expect significant cumulus clouds to be in the area this Friday.

Did you know a rocket can trigger a lightning strike when there is no natural lightning occurring? The Lightning Launch Commit Criteria protect the Shuttle and other rockets from the threat of triggered lightning. See how scientists at the University of Florida study triggered lightning by launching rockets into elevated electrical fields.

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STS-134 Prelaunch Update

At today's pre-launch countdown status briefing held at NASA's Kennedy Space Center in Florida, managers reported space shuttle Endeavour, its payload and crew are ready for launch at 3:47 p.m. EDT Friday.

NASA Test Director Jeremy Graeber reported everything is progressing on schedule for the 25th and final launch of space shuttle Endeavour.

"Our teams here at Kennedy Space Center, and at NASA centers around the country, have been working for over a year to get Endeavour ready for the STS-134 mission," said Graeber. "We're not working any issues at this time … and over the past ten days have completed some major milestones."

Joe Delai, STS-134 payload manager gave a brief overview of the payload and will have more details during Thursday's launch countdown briefing. "The payloads are closed for flight, we're not working any issues and ready to support launch," said Delai.

Shuttle Weather Officer Kathy Winters reported weather is looking good for launch day and for the loading of propellants into Endeavour's external fuel tank although there may be possibility for a storm during the rollback of the rotating service structure, or RSS, scheduled for 7 p.m. Thursday.

At this time there's only a 20 percent chance of weather hindering a successful launch on Friday, due to possible windy conditions, reported Winters.

Endeavour's six astronauts departed Ellington Field, Texas, shortly before 10 a.m. EDT. They are expected to arrive in their T-38 jets at NASA Kennedy Space Center's Shuttle Landing Facility at 12:15 p.m. Their arrival will be aired on NASA TV (www.nasa.gov/ntv).

Today at 2 p.m. NASA's official launch countdown clock begins counting backward toward Friday's liftoff.

Tomorrow's pre-launch news conference will be aired at 11 a.m. on NASA TV (www.nasa.gov/ntv).

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Hurricane Season 2011: System 91L (Atlantic Ocean)

Fizzled Tropical Prospects: The Atlantic Low

That low pressure system known as System 91L that caught a lot of attention in the North Atlantic last week is now history. System 91L sparked the interest of forecasters because it had a small chance to develop into a subtropical or tropical storm last week. Now that chance is zero.

On Saturday, April 23, 2011, the showers associated with System 91L diminished. At that time, the low was centered about 360 miles north of San Juan, Puerto Rico. Wind shear had taken its toll on the low and weakened it . As a result, the National Hurricane Center issued their final notice about the system on Saturday.

Currently there are no tropical cyclones expected elsewhere in the Atlantic Ocean, and the official hurricane season doesn't start until June 1.

Text Credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.

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Countdown to Endeavour: Moving the External Tank Barge

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

When the External Tank Barge “Pegasus” is not transporting external tanks from the Michoud Assembly Facility in New Orleans to Kennedy Space Center, it resides in the Vehicle Assembly Building basin between the Kennedy Space Center Press Site and the Shuttle launch pad. Due to this location and its size, the barge blocks the view of the launch from the press site; therefore, the United Space Alliance Marine Operations team must move the barge out of the way by launch day. 

The team uses small motor boats to move the barge, but needs winds 5 knots or less so the boats can move the barge, not vice-versa. Because of this low wind constraint, weather is the main factor when scheduling the move. We’ve been looking for a window of opportunity for this barge move for over a week, and we finally decided that Thursday, April 21 was the best day. Forecasting such light winds on spring mornings can be challenging. I hoped our wind forecast was correct and was touching base with the marine operations team every morning with updates. Luckily, the winds cooperated, and the team moved the barge across the basin. The press site now has a perfect view of the launch to relay to the world.

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Countdown to Endeavour: How to Move a Solid Rocket Booster Segment

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

Example of a segment move photo from the Kennedy Space Center Multimedia Web Site - http://go.usa.gov/TJC

On April 13, 2011, we had our last Solid Rocket Booster “segment move” for the final Shuttle mission launching in June. The solid fuel segments arrive on rail from the ATK solid rocket booster plant in Promontory, Utah, to the Rotation Processing Surge Facility at Kennedy Space Center, just north of the Vehicle Assembly Building (VAB). The segments are then transported to the VAB for stacking.

The transport to the VAB requires no more than a 25% chance of lightning during the hour it takes to move the segment. Luckily, the weather was favorable that morning, and the team completed the transport successfully.

This operation is an example of how the 45th Weather Squadron provides time and location-specific forecasts. During the summertime thunderstorm season, breaking down the forecast into hourly increments is imperative to providing the team with a safe window of opportunity to complete the operation.

The 45th Weather Squadron provides the forecast, and the Shuttle team determines whether the operation is a “Go” or “No-Go” given their specific weather constraints.

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Countdown to Endeavour: When the Weatherwoman Can’t Be Wrong

By Carla Voorhees

Kathy Winters is an Air Force Civilian Meteorologist at the 45th Weather Squadron at Cape Canaveral Air Force Station. She is the Space Shuttle Launch Weather Officer providing weather support to the Space Shuttle Program at Kennedy Space Center as the Launch Team prepares for the 29 April 2011 launch of Endeavour. You can find out more about the 45th Space Wing at their Facebook page.

Shuttle Launch Weather Predictions:

Shuttle launch preparations continue and we are providing both general information about launch weather as well as specific information to the Space Shuttle team. I provide a weather briefing to the Launch Director every morning, and we are already looking ahead at next week’s launch weather. For predictions beyond seven days, we review the Global Forecast System (GFS) long-range model outputs which are updated every six  hours. The meteorological model predictions for time periods beyond five days toggle around quite a bit. On Tuesday weather predictions for April 29th looked bad, but on Wednesday the 00Z and 06Z GFS model runs trended to a more favorable launch day weather prediction. Still, it’s too early to tell. Over the next week, we will watch each model run noting the consistency of the models as we approach launch.  Our first launch forecast will be issued on April 26, three days prior to launch.

Temperature Prediction assists ATK in Determining Solid Rocket Motor Performance:

Nine days before launch, we provide the Marshall Space Flight Center Natural Environments Branch with forecast high and low temperatures for each day up through launch day. This temperature forecast is used by ATK Aerospace Systems to predict the propellant mean bulk temperature, a critical parameter in predicting the solid rocket motor performance during launch. Forecasting temperatures at 60 feet at the Shuttle launch pad is a lot different than forecasting temperatures at the surface away from the coast. Over the next week, we are expecting a lot of southeast winds, and onshore flow means the temperatures will be moderate at the launch pad and will average very close to the coastal water temperature. The high temperature will be several degrees lower than the inland temperatures in this type of situation, and the low temperatures will be several degrees higher. This is why I was wearing a leather jacket during our launch pad tour a couple weeks ago—it gets cool at the launch pad with onshore winds!

For a further explanation of why coastal temperatures are more moderate than inland temperatures, particularly with onshore flow, visit the National Oceanic and Atmospheric Administration.

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NASA's TRMM Satellite Estimates Australia's Cyclone Season Rainfall

Australia has been hit with a number of cyclones this season, and some of them left behind a legacy of extraordinary amounts of rainfall. NASA's TRMM satellite measures rainfall from space and data from it was used to create a map of total cyclone rainfall. The TRMM satellite is managed by both NASA and the Japanese Space Agency, JAXA.

At NASA's Goddard Space Flight Center in Greenbelt, Md. data from the Tropical Rainfall Measuring Mission (TRMM) satellite was used to create the cyclone rain maps. TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA), data were used in an analysis to show rainfall contributed by tropical cyclones that have affected Australia in 2011. Hal Pierce of the NASA TRMM team created the image and included the tracks of tropical cyclones on the image.

"The largest tropical cyclone rainfall contribution was over the coast of northwestern Australia with estimated totals of over 600 millimeters (~23.6 inches)," Pierce said. "Cyclones Bianca, Carlos, Twenty, Errol and their remnants were close enough to the northwestern coast of Australia to add to these rainfall totals."

Cyclones Anthony and Yasi compounded flooding from record breaking heavy rainfall over northeastern Australia. This analysis shows that the remnants of Yasi dropped heavy rainfall over the center of Australia after devastating Queensland's northern coast. Size, rainfall intensity and speed of movement are some of the factors that affect the amount of rainfall from tropical cyclones. Deadly tropical cyclone Yasi affected a very large area of Australia while Errol was relatively small and added little rain to seasonal totals as it recently brushed northwestern Australia.

Text Credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.

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