From NOAA:

April 25, 2013

The radar receiving dish inside the protective cover. Dual-pol is both a hardware and software upgrade to the radar. Courtesy: NOAA

This week, the National Weather Service completed the dual-polarization technology update in Brownsville, Texas – concluding the 122 NWS radar site upgrades throughout the country. This new advanced technology is helping federal weather forecasters more accurately track, assess and warn the public of approaching high-impact weather.

Dual-polarization is the most significant enhancement made to the nation’s federal weather radar system since Doppler technology was first installed in the early 1990s. Dual-pol radar sends and receives both horizontal and vertical pulses, which produces a much more informative picture of the size and shape of the objects in the sky. This provides meteorologists the ability to distinguish between rain, snow, hail and non-weather items like wildfire smoke plumes, birds and insects. Conventional Doppler radar only has a one-dimensional view making it difficult to tell the type of precipitation or object in the sky.

“This achievement is the result of years of research, development and continued investment that’s helping us become a more weather-ready nation,” said Dr. Louis Uccellini, director, NOAA’s National Weather Service. “It is amazing what we can see with dual-pol technology. This game-changing technology has already helped forecasters issue more accurate and timely warnings to the public and has saved lives.”

Dual-pol is credited with providing improved detection of heavy rainfall, which can increase warning time for flash floods. During winter storms, forecasters use dual-pol information to monitor a transition from snow to sleet and freezing rain, which allows for a more accurate forecast. Dual-pol can also spot airborne debris giving forecasters the ability to confirm a tornado on the ground, even in the dark or when hidden by heavy rain. The new technology has also been used to help detect hazards to aircraft, such as volcanic ash plumes, icing conditions and birds.

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The Storm Prediction Center places all of central Texas in the “slight risk” area for severe thunderstorms late this evening through the overnight hours

Tonight, a weak cool front drifting southward from north Texas will stall across our area – providing a focal point for shower and thunderstorm development.

Due to the unstable springtime airmass and convergence along the cool front, the Storm Prediction Center has placed all of central Texas in a “slight risk” area for severe weather late this evening through the overnight hours.

The main threat from these storms will be large hail – potentially larger than golfball-sized.

That cool front will sag south of our area by late Sunday morning, taking any significant rain chances along with it. Showers will likely wrap up by late Sunday morning, with clearing skies expected late Sunday afternoon.

Rainfall should be heaviest south of Highway 290, with some totals of 1″ – 1.5″ possible.

Forecast rainfall totals through Sunday afternoon from the KXAN First Warning Weather Center

I’ve emceed a lot of events over the years, but never a toilet flushing–until this weekend! All of you who enjoy the Hike and Bike Trail on Lady Bird Lake should join us Saturday morning! Details below.

Join us on April 27th from 8am-noon for the new Johnson Creek Restroom First Flush!

Ribbon Cutting at 10am

Free GoodPops, Elixer coffee, Longhorn Bars, dog tags and chances to win a limited-edition TTF t-shirt!

CPC Seasonal Drought Outlook

Latest Seasonal Assessment - The drought outlook for April 18 – July 31, 2013 is based primarily on short-, medium-, and long-range forecasts, initial conditions, and climatology. During the past two months, major improvement occurred across Georgia and South Carolina where additional improvement is expected. Improvement is also forecast for the Florida peninsula. The duration of the drought across south Florida is expected to be short-lived as the rainy season typically begins by the end of May. A repeat of last summer’s “flash drought” (both in spatial coverage and duration) across the Corn Belt is not expected at this time. However, rapidly developing flash droughts are notoriously difficult to predict well in advance. Improvement is forecast across eastern Kansas, eastern Oklahoma, and northeast Texas, but prospects for drought improvement decrease farther southwest across the southern High Plains and south Texas. Some improvement is expected across the intense drought areas of the northern/central Plains, while improvement is more likely across the upper Mississippi Valley. Drought is forecast to persist for much of the West and expand across northern California and southern Oregon. Some improvement is expected for the drought area across northern Alaska, while areas of persistence and development of drought are anticipated for the Hawaiian Islands.

Here is some info the CPC has out on droughts:

What is the U.S. Seasonal Drought Outlook?

The U.S. Seasonal Drought Outlook shows predicted trends
for areas experiencing drought depicted in the U.S. Drought
Monitor, as well as indicating areas where new droughts may
develop. The NOAA Climate Prediction Center issues this monthly
product in conjunction with their long-lead temperature and
precipitation outlooks on the first and third Thursday of each
month and when weather events warrant an interim update.
The general large-scale trends depicted are based on numerous
indicators, including short and long-range forecasts. A discussion
detailing the atmospheric, hydrologic, and climatic conditions
affecting the drought trends is included.

Why is Drought Important?

The United States is vulnerable to the social, economic, and
environmental impacts of drought. More than 100 years of U.S.
weather records indicate that there have been three or four major
drought events during that period. Two of these, the 1930s Dust
Bowl drought and the 1950s drought, each lasted five to seven
years and covered large areas of the continental United States.
Droughts are among the most costly weather related events.
According to the National Climatic Data Center (NCDC), the United
States has sustained 114 weather/climate disasters over the past
31+ years (up to 2011) in which overall damages/costs reached
or exceeded $1 billion. The total standardized losses for the 114
events exceed $800 billion.
During this period, there have been 16 billion-dollar droughts,
totaling $195 billion in losses, which amounts to approximately
$12 billion for each billion-dollar drought event that has occurred.

Common Types Of Drought

Meteorological Drought
Meteorological Drought is based on the degree
of dryness (rainfall deficit) and the length of
the dry period.

Hydrological Drought
Hydrological Drought is based on the impact of rainfall deficits
on the water supply such as stream flow, reservoir and lake
levels, and ground water table decline.

Socioeconomic Drought
Socioeconomic drought is based on the impact of
drought conditions (meteorological, agricultural,
or hydrological drought) on supply and demand
of some economic goods. Socioeconomic drought
occurs when the demand for an economic good
exceeds supply as a result of a weather-related
deficit in water supply.

Agricultural Drought
Agricultural Drought is based on the impacts to agriculture by
factors such as rainfall deficits, soil water deficits, reduced ground
water, or reservoir levels needed for irrigation.

What to Watch For in May

 Here is the Central Texas bird forecast for the month of May, courtesy of Travis Audubon. Learn more about Central Texas birds and bird-related events for all ages at www.travisaudubon.org or call 512-300-BIRD. Travis Audubon can be followed at Twitter@TravisAudubon or on Facebook at www.facebook.com/travisaudubon.

Yellow Warbler – Photo by Aaron E. Giroux

Eye-dazzling Warblers

Having left the tropics, warblers are on their way to nesting grounds up north and many will pass through Austin in May. This month’s strong southern breezes are like a conveyor belt. They can carry these small songbirds, which normally fly 10-30 mph, at ground speeds approaching 90 mph across the Gulf of Mexico, according to research. This significantly reduces the energy required to make the 600-mile trans-Gulf journey.

If these nighttime migrants don’t collide with oil rigs or cruise ships, they have a good chance of making it to the coast or further inland before stopping to rest and feed. Late cold fronts, however, play havoc with migration by causing “fallouts,” in which exhausted birds literally fall out of the sky onto coastal lands or into the Gulf.

American Redstart – Photo by William H. Majoros via Creative Commons

Warblers including the American Redstart, Magnolia, Blackburnian, Chestnut-sided, Bay-breasted and Yellow will be arriving through mid-May from as far away as Brazil and Peru. These birds don’t announce themselves, so it’s necessary to look for them. The Blackburnian and American Redstart forage high in the canopy, while the Yellow, Magnolia, Chestnut-sided and Bay-breasted are more easily seen in mid-story trees and shrubs—eye level or higher.

Chestnut-sided Warbler – Photo by William H. Majoros via Creative Commons

Search along wooded creeks and greenbelts where native trees like oaks and hackberries grow, and listen for unfamiliar songs like the “sweet, sweet, sweet I’m so sweet” of the Yellow Warbler. (Visit Cornell Lab of Ornithology’s “All About Birds” website to hear recordings of each species.)

Get outdoors to enjoy and wonder at these amazing little birds, traveling on a wing and a prayer.

Upcoming Events

Travis Audubon May Meeting

“Wildlife conservation Issues in Texas: What does the future hold?”

Thursday, May 16, 2013; 7 p.m. (doors open 6:30 p.m.) at First Presbyterian Church, 8001 Mesa Dr.

John Davis, wildlife diversity program director for the Texas Parks and Wildlife Department, highlights the amazing array of habitats and species found throughout Texas. Preserving these natural treasures means overcoming serious challenges. Davis discusses possible ways to secure a solid future for Texas wildlife.

May is Bird-a-Thon Month

Support teams of birders and help Travis Audubon raise funds for classes and conservation programs. Each team competes to locate as many bird species as possible, with prizes going to the winners. To participate or make a pledge, visit http://travisaudubon.org/events/bird-a-thon-2013.

Travis Audubon Field Trips (beginning birders welcome)

Since May is the season for bird migration, all field trips may not be listed here. For more information, see http://travisaudubon.org/get-outdoors/field-trips.

Beginners Bird Walk at Riata Pond

Saturday, May 4; 7:30am to 9:30am

Laguna Gloria with Sam Fason

Sunday, May 5; 8:45am to 10:45am

Commons Ford Bird Walk with Diane Sherill

Sunday, May 5; 7:30am to 11:30am

Super Tuesday! at Berry Springs Park, led by Dan Callaway

Tuesday, May 7; 7am to 11:30am

Monthly Bird Count at Hornsby Bend

Saturday, May 11; 7am & 4pm

Balcones Canyonlands National Wildlife Refuge

Sunday, May 12; 7:15am to 11:30am

Copperfield Nature Trails

Sunday, May 12; 7am to 11:30am

Super Tuesday! in Bastrop County, led by Terry Banks

Tuesday, May 14; 5:45am to early afternoon

Hornsby Bend Monthly Bird Walk

Saturday, May 18; 7:30am to 11am

Travis County East Metro Park

Saturday, May 18; 7am to 11am

Balcones Canyonlands National Wildlife Refuge: Native Plant Walk

Sunday, May 19; 9am to 1pm

Walnut Bluffs

Sunday, May 19; 7am to10:30am

Super Tuesday! at Commons Ford Ranch Park, led by Deb and Lee Wallace

Tuesday, May 21; 6:30am to 10am

Compiled by Travis Audubon volunteers Jane Tillman and Jorjanna Price

Later this year, Comet ISON is expected to become a naked-eye object when it skims through the atmosphere of the sun.  The Hubble Space Telescope has just obtained a sneak preview.

Hubble photographed ISON on April 10th.  At the time, the comet was 386 million miles from the sun (394 million miles from Earth), just inside the orbit of Jupiter. Even at that great distance the comet is already active as sunlight warms the surface and causes frozen gases to vaporize. A detailed analysis of the image reveals a strong jet blasting dust particles off the sunward-facing side of the comet’s nucleus.

Hubble’s view of Comet ISON (C/2012 S1) on April 10, 2013. This image was taken in visible light. The blue false color was added to bring out details in the comet structure. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team

Astronomers are using Hubble images to measure the activity level of the comet and constrain the size of its icy nucleus. Preliminary measurements  suggest that the ISON’s nucleus is no larger than three or four miles (~5 to 6 km) across. This is remarkably small considering the high level of activity observed in the comet so far, said researchers.

The comet’s dusty atmosphere, or “coma”, is approximately 3,100 miles across, or 1.2 times the width of Australia. A dust tail extends more than 57,000 miles, far beyond Hubble’s field of view.

A more careful analysis is  underway to improve these measurements and to predict the comet’s activity when it skims 700,000 miles above the sun’s roiling surface on November 28.

For updates, stay tuned to Science@NASA.

Credits:

Production editor: Dr. Tony Phillips | Credit: Science@NASA

More information:

Comet ISON Meteor Shower  — a video from Science@NASA

Comet of the Century?  — experts discuss how bright Comet ISON might become when it skims the sun in late 2013.

ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences.

Current temperatures as of 12:15pm.  This really tells the story of the temperature difference between the air masses on either side of the front.

What is interesting is that even with the impressive difference in temperatures, and the amount of moisture pumping in from the Gulf, a strong cap in the atmosphere will keep an abundance of storms from erupting today and tonight.  We may still see a light shower or two, and maybe even an isolated thunderstorm overnight, but no major threats are anticipated.

SPC severe weather outlook for today

Notice no slight risk area from the SPC forecasted today.

Tomorrow’s numbers will be very unusual for late April.  Here area the record lowest high temperatures for April 24th:

Camp Mabry – 58 in 1982

ABIA – 64 in 1982

Here are our forecasted high temps for the next few days:

The unseasonably cold weather central Texas has been subjected to for the last 48 hours was made very apparent in southeastern Travis County early Saturday morning.

ABIA did not just set a new record low – they smashed the old record by an unprecedented 12 degrees!

Check out the record event report from the National Weather Service below:

RECORD EVENT REPORT 
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO, TX
720 AM CDT SAT APR 20 2013

...RECORD LOW TEMPERATURE WAS SET AT AUSTIN BERGSTROM...

A RECORD LOW TEMPERATURE OF 33 DEGREES WAS SET AT THE AUSTIN 
BERGSTROM AIRPORT THIS MORNING. THIS BREAKS THE OLD RECORD
OF 45 DEGREES SET IN 2008.

From NOAA NCDC:

Climate Highlights — March

• The March average temperature for the contiguous U.S. was 40.8°F, which was 0.9°F below the 20^th century average. This was in stark contrast to temperatures from one year prior when March 2012 was the warmest such month on record for the nation. 2013 marked the coolest March since 2002, when the monthly nationally-averaged temperature was 2.2°F below average.

• Much of the eastern U.S. was cooler than average during March, with the exception of New England, which was slightly warmer than average. Eleven states in the Ohio Valley, along the Gulf Coast, and in the Southeast had March temperatures that were among their ten coolest. In fact, Florida, Georgia, Alabama, South Carolina, and North Carolina had March 2013 temperatures that were cooler than January 2013.
• The Arctic Oscillation (AO) is a measure of pressure patterns across the Arctic and can relate to temperatures in the middle-latitudes, including the U.S., during the winter and spring months. The AO was in a strongly negative phase during most of the month. The monthly-averaged AO index was the most negative value on record for March and was associated with the prolonged cold air outbreak that impacted states from the Canadian border to the Southeast.
• Temperatures were above average for parts of the West. Arizona, California, and Nevada each had March temperatures ranking among their ten warmest. Above-average temperatures were also observed in Washington, Oregon, Idaho,Utah, and New Mexico.
• The March average precipitation for the contiguous U.S. was 1.68 inches, 0.72 inch below average, and the fifth driest March on record. This marked the driest March since 1966, when the nationally-averaged precipitation total was 1.51 inches.
• A large area of the contiguous U.S. had near- to below-average precipitation totals during March. The West, Southern Plains, Gulf Coast, and Northeast were particularly dry. Louisiana had its fourth driest March, with 31 percent of average precipitation for the month. Wyoming tied its fifth driest March, with 47 percent of average precipitation. Minnesota was the only state with above-average March precipitation.
• Several storms impacted the U.S. bringing late-season snowfall to the eastern two-thirds of the country. According to data from the Rutgers Global Snow Lab, the March snow cover extent for the contiguous U.S. was nearly 1.0 million square miles, 239,000 square miles above the 1981-2010 average, and the 10^th largest March snow cover extent in the 47-year period of record. However, snowpack, an important water resource in the West, was below-normal in the Sierra Nevada Mountains as well as the Central and Southern Rockies.
• Based on NOAA’s Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand was 127 percent of average during March and the 31^st highest value in the 119-year period of record. This was the highest REDTI value for March since 1996.
• According to the April 2 U.S. Drought Monitor report, 51.9 percent of the contiguous U.S. was experiencing moderate-to-exceptional drought, smaller than the 54.2 percent at the end of February. Drought conditions improved in parts of the Southeast, as well as the eastern edge of the core drought areas in the Central and Southern Plains, due to increased precipitation over the past three to six months. Drought remained entrenched across the rest of the Great Plains and interior western states.
• Climate Highlights — year-to-date (January — March)
• The average temperature for the contiguous U.S. for the year-to-date period was 35.8°F, 0.5°F above average. Much of the nation had near-average January–March temperatures. The Northeast and parts of the Northern Rockies were warmer than average, while the interior western states and parts of the Mid-South were cooler than average.
• The nationally-averaged precipitation total for the year-to-date period was 6.04 inches, 0.60 inch below average.
• The West, Northeast, and Florida were drier than average for the three-month period. California had its driest January-March on record with a precipitation total 8.53 inches below the long-term average of 11.48 inches. Oregon, Idaho, Nevada, Utah, and Wyoming also had one of their ten driest year-to-date periods on record.
• Wetter-than-average conditions were present for parts of the Midwest and Southeast. Michigan had its tenth wettest January-March with precipitation 136 percent of average.

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