NASA rainfall observing satellite out of fuel, but continues to provide data

September 1st, 2014 at 7:58 pm by under Weather

Rani Gran, NASA’s Goddard Space Flight Center

Pressure readings from the Tropical Rainfall Measuring Mission‘s (TRMM) fuel tank on July 8 indicated that the satellite was nearly at the end of its fuel supply. As a result, NASA has ceased maneuvers to keep the satellite at its operating altitude of 402 kilometers (~250 miles). With its speed decreasing, TRMM has begun to drift downward. A small amount of fuel remains to conduct debris avoidance maneuvers to ensure the satellite remains safe.

TRMM’s slow descent will continue over the next 2 to 3 years. It will continue to collect useful data as its orbit descends to about 350 (217.5 miles) over the next 18 months. Once TRMM reaches an altitude of 150 to 120 kilometers (93 to 75 miles), it will re-enter the atmosphere.

The TRMM satellite, a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA), was launched in 1997 to measure precipitation over the tropics, carrying the first precipitation radar into space.

“TRMM has met and exceeded its original goal of advancing our understanding of the distribution of tropical rainfall and its relation to the global water and energy cycles,” said Scott Braun, the mission’s project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Its planned three-year mission has already lasted 17 years and provided researchers with an unprecedented data set that combined more traditional radiometer measurements with 3-dimensional radar scans across the tropical ocean and into the lower mid-latitudes from 35N to 35S latitude. Also unique to TRMM is its inclined orbit that allows it to cut across the paths of polar orbiting satellites and revisit locations at different times of day, which is important for understanding how rainfall evolves with the day/night cycle. TRMM provided the first measurements of this type over the tropical ocean.

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Developing tropical system may bring rain next week

August 31st, 2014 at 8:35 pm by under Weather

nhc image

Sunday night, the National Hurricane Center is keeping a close eye on an “invest” crossing the Yucatan Peninsula set to emerge over the southwestern Gulf of Mexico waters on Labor Day.

NHC’s prescribed odds of development have been steadily increasing over the past 48 hours, as forecast tracks are shifting slowly northward.

inv99

As of Sunday night, most computer forecasts still steer the storm west-northwestward into the Mexican coast mid week. But compared to previous model runs, some of the computer’s tracks are shifting northward.

If this developing storm takes one of the more northerly options, coming onshore near the TX/Mexico border, Central Texas could see increased rain chances Tuesday and Wednesday.

Stay tuned to KXAN and KXAN.com for the latest as this situation develops.


Dangerous heat in some areas Labor Day weekend

August 31st, 2014 at 3:26 pm by under Weather

heat index

 

With heat index values as high as 109 degrees Sunday and Monday afternoons in some areas, be sure to exercise extreme caution while spending time outdoors.

Follow the tips below, courtesy of NOAA:

  • Slow down. Reduce, eliminate or reschedule strenuous activities until the coolest time of the day. Children, seniors and anyone with health problems should stay in the coolest available place, not necessarily indoors.
  • Dress for summer. Wear lightweight, light-colored clothing to reflect heat and sunlight.
  • Put less fuel on your inner fires. Foods, like meat and other proteins that increase metabolic heat production also increase water loss.
  • Drink plenty of water, non-alcoholic and decaffeinated fluids. Your body needs water to keep cool. Drink plenty of fluids even if you don’t feel thirsty. Persons who have epilepsy or heart, kidney or liver disease, are on fluid restrictive diets or have a problem with fluid retention should consult a physician before increasing their consumption of fluids. Do not drink alcoholic beverages and limit caffeinated beverages.
  • During excessive heat periods, spend more time in air-conditioned places. Air conditioning in homes and other buildings markedly reduces danger from the heat. If you cannot afford an air conditioner, go to a library, store or other location with air conditioning for part of the day.
  • Don’t get too much sun. Sunburn reduces your body’s ability to dissipate heat.
  • Do not take salt tablets unless specified by a physician.

Isolated flash flood impacts Gillespie County

August 30th, 2014 at 9:51 pm by under Weather

gillespiee

Between approximately 6:30 – 9 PM Saturday evening, a large thunderstorm sat nearly stationary over western Gillespie County in the Hill Country.

The local Sheriff’s office reported that RR 783 between Doss and Harper was flooded — with 1.5 feet of water over the roadway.

Radar-indicated rainfall estimates were over 4″ in one isolated rural location nearby, but unfortunately we do not have any rain gauges in that spot.

Here are some actual rainfall totals from the LCRA Hydromet network of rain gauges, which you can always find on KXAN.com under the Weather tab.

8-30 RAIN

 


Texas Longhorns season opener forecast

August 30th, 2014 at 7:06 am by under Weather

8-30 game day

 

An area of low pressure is still spinning off the South Texas coast Saturday–close enough to provide a few showers and thunderstorms locally Saturday afternoon and evening.

Most of us are forecast to remain dry for tailgating and game time Saturday, but if these isolated storms do impact the area, they may contain brief heavy rain and dangerous lightning.

Remember, “When Thunder Roars, Go Indoors!” and of course, Hook ‘Em!


Southwest may face ‘megadrought’ this century

August 28th, 2014 at 5:41 pm by under Weather

Megadrought risk

Due to global warming, scientists say, the chances of the southwestern United States experiencing a decade long drought is at least 50 percent, and the chances of a “megadrought” – one that lasts over 30 years – ranges from 20 to 50 percent over the next century.

The study by Cornell University, University of Arizona and U.S. Geological Survey researchers will be published in a forthcoming issue of the American Meteorological Society’s Journal of Climate.

“For the southwestern U.S., I’m not optimistic about avoiding real megadroughts,” said Toby Ault, Cornell assistant professor of earth and atmospheric sciences and lead author of the paper. “As we add greenhouse gases into the atmosphere – and we haven’t put the brakes on stopping this – we are weighting the dice for megadrought conditions.”

As of mid-August, most of California sits in a D4 “exceptional drought,” which is in the most severe category. Oregon, Arizona, New Mexico, Oklahoma and Texas also loiter between moderate and exceptional drought. Ault says climatologists don’t know whether the severe western and southwestern drought will continue, but he said, “With ongoing climate change, this is a glimpse of things to come. It’s a preview of our future.”

Ault said that the West and Southwest must look for mitigation strategies to cope with looming long-drought scenarios. “This will be worse than anything seen during the last 2,000 years and would pose unprecedented challenges to water resources in the region,” he said.

In computer models, while California, Arizona and New Mexico will likely face drought, the researchers show the chances for drought in parts of Washington, Montana and Idaho may decrease.

Beyond the United States, southern Africa, Australia and the Amazon basin are also vulnerable to the possibility of a megadrought. With increases in temperatures, drought severity will likely worsen, “implying that our results should be viewed as conservative,” the study reports.

“These results help us take the long view of future drought risk in the Southwest – and the picture is not pretty. We hope this opens up new discussions about how to best use and conserve the precious water that we have,” said Julia Cole, UA professor of geosciences and of atmospheric sciences.

The study, “Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data,” was also co-authored by Julia E. Cole, David M. Meko and Jonathan T. Overpeck of University of Arizona; and Gregory T. Pederson of the U.S. Geological Survey.

The National Science Foundation, National Center for Atmospheric Research, the U.S. Geological Survey and the National Oceanic and Atmospheric Administration funded the research.


Lightning Tips & Safety

August 27th, 2014 at 12:01 pm by under Weather

lion lightning

Lightning: What You Need to Know

  • NO PLACE outside is safe when thunderstorms are in the area!!
  • If you hear thunder, lightning is close enough to strike you.
  • When you hear thunder, immediately move to safe shelter: a substantial building with electricity or plumbing or an enclosed, metal-topped vehicle with windows up.
  • Stay in safe shelter at least 30 minutes after you hear the last sound of thunder.

Indoor Lightning Safety

  • Stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity.
  • Avoid plumbing, including sinks, baths and faucets.
  • Stay away from windows and doors, and stay off porches.
  • Do not lie on concrete floors, and do not lean against concrete walls.

Last Resort Outdoor Risk Reduction Tips

If you are caught outside with no safe shelter anywhere nearby the following actions mayreduce your risk:

  • Immediately get off elevated areas such as hills, mountain ridges or peaks
  • Never lie flat on the ground
  • Never shelter under an isolated tree
  • Never use a cliff or rocky overhang for shelter
  • Immediately get out and away from ponds, lakes and other bodies of water
  • Stay away from objects that conduct electricity (barbed wire fences, power lines, windmills, etc.)

noaa_logo

 LIGHTNING MYTHS AND FACTS

LIGHTNING AND CARS

Do the rubber tires on your car protect you if you are OUTside the car and you’re leaning on it? NO! Like trees, houses, and people, anything outside is at risk of being struck by lightning when thunderstorms are in the area, including cars. The good news though is that the outer metal shell of hard-topped metal vehicles does provide protection to those inside a vehicle with the windows closed. Unfortunately though, the vehicle doesn’t always fare so well.

A typical cloud-to-ground, actually cloud-to-vehicle, lightning strike will either strike the antenna of the vehicle or along the roofline. The lightning will then pass through the vehicle’s outer metal shell, then through the tires to the ground.

Although every lightning strike is different, damage to the antenna, electrical system, rear windshield, and tires is common. The heat from a lightning strike is sufficient to partially melt the antenna of a vehicle and can cause what seems like a small explosion of sparks as tiny fragments of metal melt and burn. A portion of the discharge may find its way into the vehicle’s electrical system and may damage or destroy electronic components, potentially leaving the car inoperable. The lightning may also find its way into the small defrosting wires that are embedded in rear windows causing the windows to shatter. Finally, it’s very common for the lightning to destroy one or more tires as it passes through the steel belts to the ground. It’s also possible for the lightning to ignite a fire which could destroy the vehicle.

 

Myth: Lightning never strikes the same place twice.
Fact: Lightning often strikes the same place repeatedly, especially if it’s a tall, pointy, isolated object. The Empire State Building is hit nearly 100 times a year.

Myth: If it’s not raining or there aren’t clouds overhead, you’re safe from lightning.
Fact: Lightning often strikes more than three miles from the center of the thunderstorm, far outside the rain or thunderstorm cloud. “Bolts from the blue” can strike 10-15 miles from the thunderstorm.

Myth: Rubber tires on a car protect you from lightning by insulating you from the ground.
Fact: Most cars are safe from lightning, but it is the metal roof and metal sides that protect you, NOT the rubber tires. Remember, convertibles, motorcycles, bicycles, open-shelled outdoor recreational vehicles and cars with fiberglass shells offer no protection from lightning. When lightning strikes a vehicle, it goes through the metal frame into the ground. Don’t lean on doors during a thunderstorm.

Myth: A lightning victim is electrified. If you touch them, you’ll be electrocuted.
Fact: The human body does not store electricity. It is perfectly safe to touch a lightning victim to give them first aid. This is the most chilling of lightning Myths. Imagine if someone died because people were afraid to give CPR!

Myth: If outside in a thunderstorm, you should seek shelter under a tree to stay dry.
Fact: Being underneath a tree is the second leading cause of lightning casualties. Better to get wet than fried!

Myth: If you are in a house, you are 100% safe from lightning.
Fact: A house is a safe place to be during a thunderstorm as long as you avoid anything that conducts electricity. This means staying off corded phones, electrical appliances, wires, TV cables, computers, plumbing, metal doors and windows. Windows are hazardous for two reasons: wind generated during a thunderstorm can blow objects into the window, breaking it and causing glass to shatter and second, in older homes, in rare instances, lightning can come in cracks in the sides of windows.

Myth: If thunderstorms threaten while you are outside playing a game, it is okay to finish it before seeking shelter.
Fact: Many lightning casualties occur because people do not seek shelter soon enough. No game is worth death or life-long injuries. Seek proper shelter immediately if you hear thunder. Adults are responsible for the safety of children.

Myth: Structures with metal, or metal on the body (jewelry, cell phones,Mp3 players, watches, etc), attract lightning.
Fact: Height, pointy shape, and isolation are the dominant factors controlling where a lightning bolt will strike. The presence of metal makes absolutely no difference on where lightning strikes. Mountains are made of stone but get struck by lightning many times a year. When lightning threatens, take proper protective action immediately by seeking a safe shelter – don’t waste time removing metal. While metal does not attract lightning, it does conduct it so stay away from metal fences, railing, bleachers, etc.

Myth: If trapped outside and lightning is about to strike, I should lie flat on the ground.
Fact: Lying flat increases your chance of being affected by potentially deadly ground current. If you are caught outside in a thunderstorm, you keep moving toward a safe shelter.

 

8-26 Bolt from the blue - noaa

 

5 Ways People Are Struck By Lightning

1.  DIRECT STRIKE - A person struck directly by lightning becomes a part of the main lightning discharge channel. Most often, direct strikes occur to victims who are in open areas. Direct strikes are not as common as the other ways people are struck by lightning, but they are potentially the most deadly. In most direct strikes, a portion of the current moves along and just over the skin surface (called flashover) and a portion of the current moves through the body-usually through the cardiovascular and/or nervous systems. The heat produced when lightning moves over the skin can produce burns, but the current moving through the body is of greatest concern. While the ability to survive any lightning strike is related to immediate medical attention, the amount of current moving through the body is also a factor.

animation of direct lightning strike

 

 

 

 

 

 

 

 

 

2.  SIDE FLASH -   -A side flash (also called a side splash) occurs when lightning strikes a taller object near the victim and a portion of the current jumps from taller object to the victim. In essence, the person acts as a “short circuit” for some of energy in the lightning discharge. Side flashes generally occur when the victim is within a foot or two of the object that is struck. Most often, side flash victims have taken shelter under a tree to avoid rain or hail.

animation of side lightning strike

 

 

 

 

 

 

 

 

3.  GROUND CURRENT –  When lightning strikes a tree or other object, much of the energy travels outward from the strike in and along the ground surface. This is known as the ground current. Anyone outside near a lightning strike is potentially a victim of ground current. In addition, ground current can travels in garage floors with conductive materials. Because the ground current affects a much larger area than the other causes of lightning casualties, the ground current causes the most lightning deaths and injuries. animation 2 of ground current direct lightning strikeGround current also kills many farm animals. Typically, the lightning enters the body at the contact point closest to the lightning strike, travels through the cardiovascular and/or nervous systems, and exits the body at the contact point farthest from the lightning. The greater the distance between contact points, the greater the potential for death or serious injury. Because large farm animals have a relatively large body-span, ground current from a nearby lightning strike is often fatal to livestock.

 

 

 

 

4.  CONDUCTION – Lightning can travel long distances in wires or other metal surfaces. Metal does not attract lightning, but it provides a path for the lightning to follow. Most indoor lightning casualties and some outdoor casualties are due to conduction. Whether inside or outside, anyone in contact with anything connected to metal wires, plumbing, or metal surfaces that extend outside is at risk. This includes anything that plugs into an electrical outlet, water faucets and showers, corded phones, and windows and doors.

animation of conduction lightning strike

 

 

 

 

 

 

 

 

 

 

5.  STREAMERS - While not as common as the other types of lightning injuries, people caught in “streamers” are at risk of being killed or injured by lightning. Streamers develop as the downward-moving leader approaches the ground. Typically, only one of the streamers makes contact with the leader as it approaches the ground and provides the path for the bright return stroke; however, when the main channel discharges, so do all the other streamers in the area. If a person is part of one of these streamers, they could be killed or injured during the streamer discharge even though the lightning channel was not completed between the cloud and the upward streamer. See Robert’s story as an example of a streamer injury.

animation of streamers lightning strike


Epic drought in West is literally moving mountains

August 26th, 2014 at 1:14 pm by under Weather

(Climate Central)

Climate change is driving the Greenland Ice Sheet to melt, which is contributing to sea level rise. But imagine that the same amount of water melting from Greenland each year is being lost in California and the rest of the West because of the epic drought there.

What happens? The land in the West begins to rise.

In fact, some parts of California’s mountains have been uplifted as much as 15 millimeters (about 0.6 inches) in the past 18 months because the massive amount of water lost in the drought is no longer weighing down the land, causing it to rise a bit like an uncoiled spring, a new study shows.


Death Valley, Calif.
Credit: QQ Li/flickr

For the first time, scientists are now able to measure how much surface and groundwater is lost during droughts by measuring how much the land rises as it dries. Those are the conclusions of the new study published Aug. 21 in the journal Science by researchers at the Scripps Institution of Oceanography at the the University of California-San Diego.

The drought that is devastating California and much of the West has dried the region so much that 240 gigatons worth of surface and groundwater have been lost, roughly the equivalent to a 3.9-inch layer of water over the entire West, or the annual loss of mass from the Greenland Ice Sheet, according to the study.

While some of California’s mountains have risen by about 0.6 inches since early 2013, the West overall has risen by an average of about 0.157 inches.

“Groundwater is a load on the Earth’s crust,” said Klaus Jacob, a seismologist at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y., who is unaffiliated with the study. “A load compresses the crust elastically, hence it subsides. When you take that load away (by the drought) the crust decompresses and the surface rises. From the amount of rising, one can estimate the amount of the water deficit.”

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The drought-related uplifting was discovered when researchers were analyzing data from GPS stations within the National Science Foundation’s Plate Boundary Observatory. One researcher noticed that all of the GPS stations moved upward since 2003, coinciding with the timing of the current drought.

But most of the movement occurred since last year as the West’s drought has become more and more extreme, said Duncan Agnew, a professor at the Institute of Geophysics and Planetary Physics at the Scripps Institution of Oceanography at UC-San Diego, and a study co-author.

“The implications of this have yet to play out,” Agnew said. “What we’ve shown is that there is a measurement technique we can use to get a total water loss — water loss in places where we have no direct measurements.”

Low levels on Lake Mead, a major source of water in California.
Credit: Raquel Baranow/flickr

He said such uplifting likely occurs in every drought, but it has never been observed before because scientists did not have the tools to detect the uplifting until now.

“That’s why this study is interesting,” Agnew said. “We can use this set of tools, which were installed for a different purpose in order to monitor water changes.”

He said the uplifting likely has no significant effect on earthquake potential in California and elsewhere even though loss of ground and surface water has added stress to major faults in the region.

“The total amount of stress that’s been added in the last 18 months from drought is the same amount of stress that’s added every week because of plate techtonics,” he said.

Jacob said the study shows that the changes in the elevation of the landscape and the stress on faults are so small the effect will be extremely minor.

But, Jacob said, the significance of the study is that it shows a new way for scientists to estimate total water loss during times of drought, which would be more difficult to estimate without being able to detect how much the land is being uplifted in dry years.


TS Cristobal update

August 24th, 2014 at 10:26 pm by under Weather

TS track

 

The latest from NHC:

BULLETIN
TROPICAL STORM CRISTOBAL ADVISORY NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014
1100 PM EDT SUN AUG 24 2014

…CRISTOBAL MOVING SLOWLY NORTHWARD WITH NO CHANGE IN STRENGTH…
SUMMARY OF 1100 PM EDT…0300 UTC…INFORMATION
———————————————–
LOCATION…24.8N 73.1W
ABOUT 105 MI…165 KM ENE OF SAN SALVADOR
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…N OR 350 DEGREES AT 5 MPH…7 KM/H
MINIMUM CENTRAL PRESSURE…998 MB…29.47 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* CENTRAL BAHAMAS…INCLUDING CAT ISLAND…THE EXUMAS…LONG
ISLAND…RUM CAY…AND SAN SALVADOR

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TS Cristobal forms in the Atlantic

August 24th, 2014 at 9:19 am by under Weather

TS track

The latest from the National Hurricane Center as of 9 AM Sunday:

…CRISTOBAL RE-FORMS A LITTLE TO THE NORTHEAST…
…STILL MOVING NORTHWESTWARD NEAR THE SOUTHEASTERN BAHAMAS…

SUMMARY OF 800 AM EDT…1200 UTC…INFORMATION
———————————————-
LOCATION…23.0N 73.0W
ABOUT 40 MI…60 KM N OF MAYAGUANA ISLAND
ABOUT 135 MI…215 KM ESE OF LONG ISLAND
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 9 MPH…15 KM/H
MINIMUM CENTRAL PRESSURE…1001 MB…29.56 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* SOUTHEASTERN BAHAMAS…INCLUDING THE ACKLINS…CROOKED
ISLAND…LONG CAY…THE INAGUAS…MAYAGUANA…AND THE RAGGED
ISLANDS…AS WELL AS FOR THE TURKS AND CAICOS ISLANDS
* CENTRAL BAHAMAS…INCLUDING CAT ISLAND…THE EXUMAS…LONG
ISLAND…RUM CAY…AND SAN SALVADOR

INTERESTS IN THE NORTHWESTERN BAHAMAS SHOULD MONITOR THE PROGRESS
OF THIS SYSTEM. A TROPICAL STORM WATCH COULD BE REQUIRED FOR
THIS AREA LATER TODAY.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA…PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE. Read the rest of this entry »