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Severe weather threat Monday

April 20th, 2014 at 9:31 am by under Weather

4-20 SVR

 

The NOAA Storm Prediction Center places all of the Hill Country and I-35 corridor (including Metro Austin) in the threat of severe thunderstorms Monday afternoon and evening.

An unstable atmosphere is set to interact with a weak cold front sliding through the area to fire isolated severe thunderstorms – some of which could be damaging supercells with hail over 1″ in diameter. The storms are also forecast to be slow-movers, bringing about the threat of isolated flash flooding.

An important note as we prepare for a potential severe weather event…

**The NOAA transmitter that broadcasts severe weather watches/warnings to Hill Country communities is still out of service. This means that your NOAA Weather Radio will likely not sound an alarm if severe weather is approaching your area.**

The tower sustained a lightning strike weeks ago, and technicians are working hard to get the transmitter up and running again.

In the meantime, KXAN can act as your notification service when severe weather threatens.

The First Warning Weather team offers text and email alerts that are specific to your county – notifying you of impending dangerous weather, and keeping you ahead of the storm.

Signing up is easy and only takes one minute: click here for text message alerts and here for email alerts.


San Marcos enters Stage 3 water restrictions Easter Sunday

April 19th, 2014 at 5:57 am by under Weather

From the City of San Marcos:

San Marcos will go into Stage 3 effective April 20, 2014 at noon. 

Stage 3 Drought Restrictions:Wastewater Hotline

  • Waste of water is prohibited. Waste includes allowing water to puddle or run off a property, operating a sprinkler system with broken or misaligned heads, and failing to repair leaks.
  • Irrigation with sprinklers is allowed only one day every other week on the designated weekday between the hours of 6:00 a.m. to 10 a.m. and 8:00 p.m. to midnight.

    • April 21-25: Sprinklers allowed on designated day/times.
    • April 28 – May 2: No sprinklers.
    • May 5 – 9: Sprinklers allowed on designated day/times.
    • May 12 – 16: No sprinklers.

 ADDRESSES ENDING WITH:  DESIGNATED WEEKDAY IS:
 0 or 1  Monday
 2 or 3  Tuesday
 4 or 5  Wednesday
 6 or 7  Thursday
 8 or 9  Friday
  • Hand-watering using hand-held bucket or hand-held hose is allowed any day before 10:00 a.m. or after and 8:00 p.m.
  • Irrigation of landscaping with a soaker hose or drip irrigation system is allowed only one day per week on the designated weekday before 10:00 a.m. or after 8:00 p.m.
  • Irrigation of vegetable gardens with a soaker hose or drip irrigation system is allowed any day before 10:00 a.m. or after 8:00 p.m.
  • Charity car washes are prohibited unless held at a commercial car wash.
  • At-home car washing is prohibited.
  • Swimming pools should be at least partially covered when not in use to minimize evaporative losses.
  • Filling new and existing swimming pools is prohibited.
  • Using indoor and outdoor decorative water features is prohibited.
  • Washing impervious surfaces is prohibited unless required for health and safety.
  • Foundation watering is allowed only one day per week on the designated weekday before 10:00 a.m. or after 8:00 p.m.
  • Restaurants are allowed to serve water only upon specific request by the customer.
  • All other non-essential water usage is prohibited.

Drought Response Ordinance

Watering Day Variance Request

To report violations, please call the Water Waster Hotline at 512.393.8360.
If you have any questions, contact Jan Klein, Conservation Coordinator,
via e-mail or at 512-393-8310.


Storms over S. Texas trigger unusual atmospheric phenomenon

April 6th, 2014 at 9:35 am by under Weather

Storms several days ago south of Central Texas triggered an incredible – and very unusual – phenomenon in the atmosphere above us.

An explosively-intensifying thunderstorm overshot the tropopause, the boundary of warmer air nearly 50,000 feet high, sending cloud tops well into the stratosphere.

The penetration of the thunderstorm top into the typically “weather-free” stratosphere/mesosphere was akin to letting one drop of water drip onto a quiet swimming pool more than 160,000 feet above the ground.

Check out the technical article below (and the incredible photos of the “ripple effect”), courtesy of the University of Wisconsin-Madison meteorology department:

Convectively-generated mesospheric airglow waves over Texas

April 4th, 2014

GOES-13 10.7 µm IR channel images (click to play animation)GOES-13 10.7 µm IR channel images (click to play animation)

AWIPS images of 4-km resolution GOES-13 (GOES-East) 10.7 µm IR channel images with overlays of cloud-to-ground lightning strikes and surface frontal positions (above; click image to play animation) showed the explosive development of a thunderstorm just ahead of a cold frontal boundary that was moving southeastward across southern Texas during the overnight hours on 04 April 2014 (06 UTC surface analysis). This relatively small thunderstorm was very active in terms of lightning production, and eventually produced hail of 1.0 to 1.75 inches in diameter and damaging winds (SPC storm reports) as it approached the coast of Texas. Cloud-top IR temperatures were as cold as -75º C on the GOES-13 images.

A 1-km resolution POES AVHRR 12.0 µm IR image at 08:41 UTC or 3:41 AM local time (below)exhibited cloud-top IR brightness temperatures as cold as -79º C. Overlays on the IR image include cloud-to-ground lightning strikes around the time of the IR image, along with the eventual reports of hail that this storm produced about an hour later. South of the thunderstorm, the banded signatre of a pre-frontal lower-tropospheric undular bore could also be seen across deep south Texas.

POES AVHRR 12.0 µm IR channel image, with cloud-to-ground lightning strikes and hail reportsPOES AVHRR 12.0 µm IR channel image, with cloud-to-ground lightning strikes and hail reports

A comparison of 1-km resolution Suomi NPP 11.45 µm IR and 0.7 µm Day/Night Band images at 08:05 UTC or 3:05 AM local time (below) showed an “enhanced-V” signature associated with the thunderstorm, with very cold IR brightness temperatures of -86º C at the vertex of the enhanced-V. The Day/Night Band (DNB) image also showed a number of very bright “streaks” near McMullen, Texas (station identifier KNMT), a signature of portions of the cloud which were illuminated by intense lightning activity. The blurred signatures of bright city lights could even be seen through the clouds. Also, note on the DNB image the presence of curved bands off the Texas coast, over the Gulf of Mexico: what could those be?

Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images, with overlays of positive and negative cloud-to-ground lightning strikesSuomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images, with overlays of positive and negative cloud-to-ground lightning strikes.A larger-scale view of the VIIRS IR and Day/Night Band images (below) revealed a remarkably large pattern of concentric mesospheric airglow waves (reference) propagating radially outward away from the region where the thunderstorm had explosively developed and penetrated the tropopause about an hour earlier.
Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Signs of an underground ocean found on Saturn

April 5th, 2014 at 9:24 am by under Weather
Image courtesy NASA/JPL/Discovery News

Image courtesy NASA/JPL/Discovery News

The article below is courtesy of Discovery News:

Gravity measurements made with the Saturn-orbiting Cassini spacecraft indicate the small moon Enceladus has an ocean sandwiched between its rocky core and icy shell, a finding that raises the prospects of a niche for life beyond Earth.

The Cassini data shows the body of water, which is in the moon’s southern hemisphere, must be as large or larger than Lake Superior and sitting on top of the moon’s rocky core at a depth of about 31 miles.

“The ocean may extend halfway or more toward the equator in every direction,” said planetary scientist David Stevenson, with the California Institute of Technology in Pasadena.

ANALYSIS: Could Saturn’s Moon Enceladus Nurture Alien Life?

Scientists infer the ocean is salty because water plumes shooting out of cracks in Enceladus’ southern pole and sampled by Cassini contain salts, as well as organic molecules. That would happen if minerals from underlying rock were leaching into water, a chemistry that bodes well for the development and evolution of life.

“It was not a surprise to find a water reservoir certainly, because we knew that there are plumes, there is liquid water,” said planetary scientist Luciano Iess with the Sapienza University of Rome.

“There have been clues all along,” added Candice Hansen-Koharcheck, senior scientist with the Tucson, Ariz.-based Planetary Science Institute.

“But until you actually get this gravity data, it’s still kind of a circumstantial evidence-story. This is proof of the pudding,” Hansen-Koharcheck told Discovery News.

ANALYSIS: Saturn’s Tidal Tugs Energize Enceladus’ Icy Plumes

The measurements were painstakingly taken as Cassini flew close to Enceladus three times between 2010 and 2012. Two flybys were over the moon’s south pole, at distances of 65 miles and 44 miles above the surface. One flyby was 31 miles above the North Pole.

(more…)


Anniversary of first official tornado forecast

March 29th, 2014 at 9:21 am by under Weather

Last Tuesday marked the anniversary of the first official tornado forecast.

On March 25, 1948, following a devastating tornado several days prior, two Air Force forecasters made the first mention of a tornado before it actually happened – a thing that had been outlawed before then due to fear of public panic, or complacency if it didn’t materialize.

That bold move set the stage for modern-day tornado forecasting. Read more in the article below, courtesy of BlogOklahoma:

March 25, 1948

This memorial is dedicated to the first operational tornado forecast issued on March 25, 1948 by Major Ernest J. Fawbush and Captain Robert C. Miller at Tinker air force base, Oklahoma.

Issued several hours before a tornado struck Tinker air force base, this first forecast proved severe weather could be anticipated with a reasonable degree of accuracy. This focused national attention on forecasting tornadoes and warning the public of their potential danger.

Severe weather pioneers, Major Fawbush and Captain Miller, developed tornado forecasting techniques still in use today. The 1948 tornado forecast was the forerunner of today’s national severe weather forecasting and research program that protects lives and serves the American people.

Dedicated march 25, 1998

Pictures
Photo (c)
Directions

Located at Heritage Airpark on Tinker Air Base, Oklahoma City, Oklahoma

Google Map
35.43338, -97.40599
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Report rain, hail and snow to help meteorologists!

March 25th, 2014 at 11:08 am by under Weather

cocorahs

CoCoRaHS is a community network of volunteer weather observers who report daily rain, hail and snow data online in order to aid National Weather Service meteorologists, hydrologists, and water planning experts.

It only takes five minutes per day, and is a great way to get involved in the weather community and learn something while you’re at it.

Join CoCoRaHS today during March Madness – a competition between states to see who can sign up more new volunteers during the month of March.

Texas won last year – let’s do it again!

Sign up here: http://www.cocorahs.org/


New study shows accelerated ice melt, sea level rise

March 24th, 2014 at 10:21 am by under Weather

Increasing air and ocean temperatures accelerated by anthropogenic climate change are increasing the rate of ice melt in Greenland. Even though that seems like a far-away problem, the ice melt could shorten the timeline of noticeable sea level rise over the next decades. Read more in the article below from Climate Central:

By 

Stability in the rapidly changing Arctic is a rarity. Yet for years researchers believed the glaciers in the frigid northeast section of Greenland, which connect to the interior of the country’s massive ice sheet, were resilient to the effects of climate change that have affected so much of the Arctic.

But new data published Sunday in Nature Climate Change reveals that over the past decade, the region has started rapidly losing ice due to a rise in air and ocean temperatures caused in part by climate change. The increased melt raises grave concerns that sea level rise could accelerate even faster than projected, threatening even more coastal communities worldwide.

Helheim glacier in southeast Greenland.
Credit: Henrik Egede-Lassen

“North Greenland is very cold and dry, and believed to be a very stable area,” said Shfaqat Khan, a senior researcher at the Technical University of Denmark who led the new study. “It is surprisingly to see ice loss in one of the coldest regions on the planet.”

The stability of the region is particularly important because it has much deeper ties to the interior ice sheet than other glaciers on the island. If the entire ice sheet were to melt –which would take thousands of years in most climate change scenarios — sea levels would rise up to 23 feet, catastrophically altering coastlines around the world.

Sea levels have risen 8 inches globally since the start of the 1900s, and current projections show that figure could rise another 3 feet by the end of this century.

Some recent research has suggested that Greenland’s ice loss may slow, but not all researchers agree. Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland, said the new study presented a novel analysis of the region and that other factors such as soot could contribute to even more rapid melt in Greenland and other parts of the Arctic.

“These new measurements show that the sleeping giant is awakening and suggest — given likely continued Arctic warming — that it’s not going back to bed,” Box said in an email.

(more…)


Where are all of the tornadoes?

March 23rd, 2014 at 10:00 am by under Weather

It’s been an unusually slow start to tornado season. Climate Central examines the statistics, possible explanations, and if we can expect an increase through the rest of March and April:

By 

In terms of sheer numbers, the past two years have been one of the quietest periods for tornadoes in the U.S. since the late 1980s, that despite some terribly destructive storms.

March represents a major weather transition period. As spring spreads from north to south, snow melts, leaves unfurl, and heat returns to much of the U.S. The odds for tornadoes also increase as an influx of warm, moist air generally starts to push up from the Gulf of Mexico while cold, dry air drops down from the northwest. Those differences in winds and air temperatures are some of the large-scale factors that can give rise to severe storms that produce rain, hail and tornadoes.

An animation showing every tornado recorded from 1950-2012 by month. Data via NOAA Storm Prediction Center.

While tornadoes can happen any time of year and in any state, the Southeast is historically the first bullseye with most March tornadoes occurring in that region. From there, tornado-friendly conditions become widespread in the Southern Plains in April through June and in the Northern Plains in June and July.

This March has started relatively quiet. On average, there are 80 tornadoes reported around the country during March, but so far only four tornadoes have been reported this month as a winter chill has lingered longer than usual over the eastern half of the country and cold weather tends to dampen the conditions tornadoes need to form. Average temperatures have been 3°-6°F below normal since the start of March for Mississippi, Alabama, and Georgia, the historical epicenter for March tornado activity.

RELATED Oklahoma Tornado Shows Progress in Weather Warnings
U.S. Sees Record-Low Tornadoes and Tornado Deaths

Making Sense of the Moore Tornado in a Climate Context
East Greets Winter’s End; West Braces for Drought, Fire 

Cold weather played a role in suppressing the number of tornadoes in 2013. Persistent cool temperatures in March, followed by a finicky jet stream, helped keep tornado activity low in March and April. The year ended with 908 reported tornadoes, about 25 percent below the annual average of 1,200.

(more…)


Amazing shots of last week’s “haboob”

March 22nd, 2014 at 10:15 am by under Weather

Remember when a cold front last week brought 50+mph winds to the Texas panhandle, sending clouds of dust from the parched soil airborne?

Check out this amazing compilation of pictures, and analysis of the “haboob” (dust storm often brought on by thunderstorm winds) in the Discover Magazine article below:

By Tom Yulsman | March 13, 2014 7:45 pm

High Plains Haboob blows

NASA’s Terra satellite spied these streams of dust blowing south across Colorado, Kansas, Oklahoma, Texas and New Mexico on March 11, 2014. (Source: NASA)

As a cold front blew across parts of the High Plains on Tuesday, winds kicked up a huge and intense dust storm. You can see it in the image above, captured by NASA’s Terra satellite.

The dust is streaming south out of Colorado and Kansas into Oklahoma, Texas and New Mexico. (Look for the streamers of pale, sand-colored stuff south of the big cloud bank.)

With winds gusting to nearly 60 miles per hour, visibility in southwestern Kansas was reduced to zero, according to the Cooperative Institute for Meteorological Satellite Studies. CIMSS also describes a pilot report of severe turbulence at 45,000 feet in the region, possibly the result of the passing cold front.

On the ground, a towering wall of dust known as a haboob rushed across a vast swath of the High Plains, enveloping towns and cities in a brown pall.

haboob tweet 1

The photo above, posted to Twitter, was taken from an airplane flying near Amarillo, Texas, apparently at 38,000 feet. And here’s the High Plains haboob enveloping Clovis, New Mexico:

haboob tweet 2

(more…)


High fire danger today

March 18th, 2014 at 10:55 am by under Weather

Very dry air, gusty winds and warm temperatures are combining to create a HIGH FIRE DANGER Tuesday across Central TX.

Check out the following Special Weather Statement, courtesy of our local National Weather Service office:

nws

...DRY AND WARM TODAY WITH HUMIDITIES IN THE TEENS AND EVEN SINGLE
DIGITS LATE THIS AFTERNOON...

A DRY AND WARM DAY IS IN STORE ACROSS SOUTH CENTRAL TEXAS WITH
HIGHS NEAR 90 ACROSS THE RIO GRANDE PLAINS AND EDWARDS PLATEAU
WITH LOWER TO MID 80S ELSEWHERE. 
A DRY-LINE WILL PUSH EASTWARD OVER THE RIO GRANDE PLAINS LATE THIS MORNING 
AND SITS ACROSS THE
WEST SECTION OF THE HILL COUNTRY FROM MOUNTAIN HOME SOUTHWESTWARD
TO JUST NORTH OF EAGLE PASS. HUMIDITIES WILL SIGNIFICANTLY DROP
TO THE TEENS WITH SINGLE DIGITS EXPECTED ACROSS WESTERN EDWARDS
AND THE ENTIRE VAL VERDE COUNTY FOR FEW HOURS LATE THIS AFTERNOON.
WINDS WILL BE INCREASING THIS MORNING TO ABOUT 15 MPH.
HOWEVER...WINDS ARE EXPECTED TO DECREASE IN THE AFTERNOON TO ABOUT
10 MPH WHEN HUMIDITIES WILL BE LOWER OUT WEST. 
NEAR CRITICAL FIRE
WEATHER CONDITIONS ARE EXPECTED FROM LATE THIS MORNING TO EARLY
THIS EVENING MAINLY ALONG AND WEST OF A LLANO TO UVALDE TO CARRIZO
SPRINGS LINE...BUT ESPECIALLY OVER WESTERN EDWARDS AND VAL VERDE
COUNTIES. WE WILL BE MONITORING THIS SITUATION CLOSELY FOR FURTHER
ACTIONS SUCH AS THE POSSIBLE ISSUANCE OF A RED FLAG WARNING FOR
PORTIONS OF THIS AREA LATE TODAY.