I would like to preface this article from NASA with a few graphs from NOAA and NSIDC:

This graph shows how the average surface temperature of the world’s oceans has changed since 1880. This graph uses the 1971 to 2000 average as a baseline for depicting change. Choosing a different baseline period would not change the shape of the data over time. The shaded band shows the range of uncertainty in the data, based on the number of measurements collected and the precision of the methods used.

This figure shows Arctic sea ice extent from 1979 through 2012 using data from September of each year, which is when the minimum extent typically occurs.

This one is the most telling of them all:

This graph shows cumulative changes in sea level for the world’s oceans since 1880, based on a combination of long-term tide gauge measurements and recent satellite measurements. This figure shows average absolute sea level change, which refers to the height of the ocean surface, regardless of whether nearby land is rising or falling. Satellite data are based solely on measured sea level, while the long-term tide gauge data include a small correction factor because the size and shape of the oceans are changing slowly over time. (On average, the ocean floor has been gradually sinking since the last Ice Age peak, 20,000 years ago.) The shaded band shows the likely range of values, based on the number of measurements collected and the precision of the methods used.

PASADENA, Calif. — Ocean waters melting the undersides of Antarctic ice shelves are responsible for most of the continent’s ice shelf mass loss, a new study by NASA and university researchers has found.

Scientists have studied the rates of basal melt, or the melting of the ice shelves from underneath, of individual ice shelves, the floating extensions of glaciers that empty into the sea. But this is the first comprehensive survey of all Antarctic ice shelves. The study found basal melt accounted for 55 percent of all Antarctic ice shelf mass loss from 2003 to 2008, an amount much higher than previously thought.

Antarctica holds about 60 percent of the planet’s fresh water locked into its massive ice sheet. Ice shelves buttress the glaciers behind them, modulating the speed at which these rivers of ice flow into the ocean. Determining how ice shelves melt will help scientists improve projections of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise. It also will improve global models of ocean circulation by providing a better estimate of the amount of fresh water ice shelf melting adds to Antarctic coastal waters.

The study uses reconstructions of ice accumulation, satellite and aircraft readings of ice thickness, and changes in elevation and ice velocity to determine how fast ice shelves melt and compare the mass lost with the amount released by the calving, or splitting, of icebergs.

“The traditional view on Antarctic mass loss is it is almost entirely controlled by iceberg calving,” said Eric Rignot of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and the University of California, Irvine. Rignot is lead author of the study to be published in the June 14 issue of the journal Science. “Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate.”

Ice shelves grow through a combination of land ice flowing to the sea and snow accumulating on their surface. To determine how much ice and snowfall enters a specific ice shelf and how much makes it to an iceberg, where it may split off, the research team used a regional climate model for snow accumulation and combined the results with ice velocity data from satellites, ice shelf thickness measurements from NASA’s Operation IceBridge — a continuing aerial survey of Earth’s poles — and a new map of Antarctica’s bedrock. Using this information, Rignot and colleagues were able to deduce whether the ice shelf was losing mass through basal melting or gaining it through the basal freezing of seawater.

In some places, basal melt exceeds iceberg calving. In other places, the opposite is true. But in total, Antarctic ice shelves lost 2,921 trillion pounds (1,325 trillion kilograms) of ice per year in 2003 to 2008 through basal melt, while iceberg formation accounted for 2,400 trillion pounds (1,089 trillion kilograms) of mass loss each year.

Basal melt can have a greater impact on ocean circulation than glacier calving. Icebergs slowly release melt water as they drift away from the continent. But strong melting near deep grounding lines, where glaciers lose their grip on the seafloor and start floating as ice shelves, discharges large quantities of fresher, lighter water near the Antarctic coastline. This lower-density water does not mix and sink as readily as colder, saltier water, and may be changing the rate of bottom water renewal.

“Changes in basal melting are helping to change the properties of Antarctic bottom water, which is one component of the ocean’s overturning circulation,” said author Stan Jacobs, an oceanographer at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y. “In some areas it also impacts ecosystems by driving coastal upwelling, which brings up micronutrients like iron that fuel persistent plankton blooms in the summer.”

The study found basal melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of the total Antarctic ice shelf area, accounted for only 15 percent of basal melting. Meanwhile, fewer than a dozen small ice shelves floating on “warm” waters (seawater only a few degrees above the freezing point) produced half of the total melt water during the same period. The scientists detected a similar high rate of basal melting under six small ice shelves along East Antarctica, a region not as well known because of a scarcity of measurements.

The researchers also compared the rates at which the ice shelves are shedding ice to the speed at which the continent itself is losing mass and found that, on average, ice shelves lost mass twice as fast as the Antarctic ice sheet did during the study period.

“Ice shelf melt doesn’t necessarily mean an ice shelf is decaying; it can be compensated by the ice flow from the continent,” Rignot said. “But in a number of places around Antarctica, ice shelves are melting too fast, and a consequence of that is glaciers and the entire continent are changing as well.”

May 2013 Weather in Review

May 2013 was more like an early fall month than a late Spring month, with regard to daily
temperature changes from cold to warm. For active weather, May 2013 was typical of the usual
occasional severe weather and heavy rain events that have come in May. May 2013 began with
temperatures much below normal. All time lows for the month were set May 4th at Austin
Bergstrom, 37, and at San Antonio, 42. Lows at Austin Mabry on May 4th was 46 and at Del Rio
47. The 47 low at Del Rio tied the daily May 4th record of 47 observed on May 4, 1954. After a brief
warming trend, it cooled off again after rains of May 9th and 10th. After a brief period of cooler
days, it warmed up quickly May 16th to May 20th. A few daily record highs were observed on
May 16th and May 17th, when highs rose to the 90s, with 100 degree days over the west part of
South Central Texas. A record daily high of 107 was observed at Del Rio on May 16th and of 105
on May 17th. The high of 97 at San Antonio on May 16th and May 17th tied the daily record high
for May 16th and May 17th. The high of 93 at Austin Bergstrom May 17th tied the record for May
17th, and the high of 95 at Austin Bergstrom May 18th broke the daily record high for May 18th.
Scattered storms returned May 21st, followed by calmer conditions on May 22nd. This ended the
23rd as the weather became more active, followed by stormy weather and flooding on May 24th to
May 25th. Scattered storms returned Sunday, May 26th. The heavy rain amount of 9.87 inches at
San Antonio on May 25th, was a record daily amount for the month of May and was the 2nd
wettest day at San Antonio after the October 17, 1998 record of 11.26 inches. Isolated showers
May 27th were followed by isolated to scattered thunderstorms, with stormy conditions over the
west part of South Central Texas, late in the day on May 28th to the early morning of May 29th.
More stable and warmer conditions developed May 30th and May 31st.

May 2013 Summary

Location         Average Temp           Average High          Average Low          Warmest/Coolest        

Camp Mabry        75.7 -0.9                     86.9 +0.4                  64.5 -2.2           96 on 18th, 44 on 3rd

ABIA                   74.3 -0.9                   86.0 -0.7                     62.6 -1.1           95 on 18th, 37 on 4th

Burnet                73.0 -1.1                    84.0 -0.4                     62.0 -1.9           94 on 18th, 40 on 4th

May 2013 Climate Records…

MAY 2013 RECORDS SET AT AUSTIN CAMP MABRY
-  THE LOW OF 44 ON MAY 3RD BROKE THE RECORD LOW FOR MAY 3RD OF 45 SET
ON MAY 3, 1929.
-  THE LOW OF 75 ON THE 17TH TIED THE RECORD HIGH MINIMUM FOR MAY 17TH
OF 75 SET IN 1995.
MAY 2013 RECORDS SET AT AUSTIN BERGSTROM
- THE LOW OF 42 ON MAY 3RD BROKE THE RECORD LOW FOR MAY 3RD OF 44 SET
ON MAY 3, 2011.
- THE LOW OF 37 ON MAY 4TH BROKE THE DAILY RECORD FOR MAY 4TH AND THE
MONTHLY RECORD LOW FOR MAY OF 38 SET ON MAY 4, 2011.
- THE LOW OF 45 ON MAY 6TH BROKE THE RECORD LOW FOR MAY 6TH OF 49 SET
ON MAY 6, 1953.
- THE LOW OF 48 ON MAY 13TH TIED THE RECORD LOW FOR MAY 13TH OF 48
SET ON MAY 13, 1960.
- THE HIGH OF 93 ON MAY 17TH TIED THE RECORD HIGH FOR MAY 17TH OF 93
SET ON MAY 17, 2003.
- THE HIGH OF 95 ON MAY 18TH BROKE THE RECORD HIGH FOR MAY 18TH OF 94
SET ON MAY 18, 2003.
- THE AVERAGE TEMPERATURE FOR THE MONTH OF MAY 2013 AT AUSTIN
BERGSTROM OF 74.3 MADE MAY 2013 THE 10TH COOLEST MAY OF RECORD
AT AUSTIN BERGSTROM SINCE OCTOBER 1942.
- THE AVERAGE LOW AT AUSTIN BERGSTROM OF 62.6 WAS THE 2ND COOLEST
AVERAGE DAILY LOW AT AUSTIN BERGSTROM SINCE OCTOBER 1942. THE
COOLEST AVERAGE LOW FOR MAY AT AUSTIN BERGSTROM WAS 61.7 IN
MAY OF 1976.

JUNE OUTLOOK

The outlook for June 2013 issued by the Climate Prediction Center on May 31st shows Equal
Chances of being cooler; near normal; or above normal for the average monthly temperature
across most of South Central Texas, except for the western edge of South Central Texas where the
Climate Prediction Center showed a 33.3 to 40 percent chance of being warmer than normal; a 33.3
percent chance of near normal temperatures; and a 26.7 percent chance of being cooler than
normal. The outlook for the rainfall in June 2013 shows Equal Chances of above; near normal; or
below normal rainfall for June 2013. The average 3 month temperature from June to August 2013
shows a 40 percent chance of being warmer than usual from June to August; a 33.3 percent chance
of being near normal; and a 26.7 percent chance of being cooler than normal. The June 2013 to
August 2013 3 month rainfall outlook over South Central Texas shows Equal Chances of above;
near normal; or below normal rainfall for June to August of 2013. Click Here to See the Latest
Outlooks from the Climate Prediction Center. The table below lists information on Climate
Normals for the month of June for Austin, Del Rio and San Antonio.

We aren’t even a full week into the season, and we are aiming to have our first tropical system US landfall.  Andrea is barreling in on the Florida Gulf Coast and will bring extensive rainfall not only to Florida but also up the eastern seaboard.  Here is the latest from the NHC and some fun history on the naming of storms….

TROPICAL STORM ANDREA INTERMEDIATE ADVISORY NUMBER   3A
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012013
700 AM CDT THU JUN 06 2013

...ANDREA MOVING CLOSER TO THE FLORIDA BIG BEND...
...POTENTIAL FOR TORNADOES ACROSS CENTRAL AND SOUTHERN FLORIDA
DURING THE MORNING...

SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...27.7N 85.1W
ABOUT 160 MI...255 KM W OF TAMPA FLORIDA
ABOUT 140 MI...225 KM S OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NNE OR 25 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES

WATCHES AND WARNINGS
--------------------
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE WEST COAST OF FLORIDA FROM BOCA GRANDE TO INDIAN PASS
* FLAGLER BEACH FLORIDA TO CAPE CHARLES LIGHT VIRGINIA
* PAMLICO AND ALBEMARLE SOUNDS
* LOWER CHESAPEAKE BAY SOUTH OF NEW POINT COMFORT

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY
YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.

DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 700 AM CDT...1200 UTC...THE CENTER OF TROPICAL STORM ANDREA WAS
LOCATED NEAR LATITUDE 27.7 NORTH...LONGITUDE 85.1 WEST. ANDREA IS
MOVING TOWARD THE NORTH-NORTHEAST NEAR 14 MPH...22 KM/H. A TURN
TOWARD THE NORTHEAST WITH AN ADDITIONAL INCREASE IN FORWARD SPEED
IS EXPECTED TODAY. ON THE FORECAST TRACK...THE CENTER OF ANDREA
WILL REACH THE COAST OF THE FLORIDA BIG BEND AREA LATER TODAY AND
THEN MOVE ACROSS SOUTHEASTERN GEORGIA...SOUTHEASTERN SOUTH CAROLINA
AND EASTERN NORTH CAROLINA BY FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH...95 KM/H...WITH HIGHER
GUSTS.  NO SIGNIFICANT CHANGE IN STRENGTH IS FORECAST BEFORE THE
CENTER REACHES THE COAST LATER TODAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
PRIMARILY TO THE EAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB...29.44 INCHES.

Full list of names for 2013 Atlantic storms:

• Andrea
• Barry
• Chantal
• Dorian
• Erin
• Fernand
• Gabrielle
• Humberto
• Ingrid
• Jerry
• Karen
• Lorenzo
• Melissa
• Nestor
• Olga
• Pablo
• Rebekah
• Sebastien
• Tanya
• Van
• Wendy

If there are more than 21 named tropical cyclones in the Atlantic basin in one season, additional storms will take names from the Greek alphabet.

Here is the latest on the chance for showers, thunderstorms, and possible flooding for later today.
  

FLOOD WATCH
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
955 AM CDT WED MAY 29 2013

...FLASH FLOOD WATCH NOW IN EFFECT UNTIL MIDNIGHT TONIGHT ALONG
AND EAST OF A LINE FROM BURNET TO BANDERA TO DERBY FOR LOCALLY
HEAVY RAINS AND FLASH FLOODING...

.THE NATIONAL WEATHER SERVICE HAS EXTENDED THE FLASH FLOOD WATCH
UNTIL MIDNIGHT TONIGHT. SOME OF OUR HIGH RESOLUTION MODELS ARE
SHOWING HEAVY CONVECTION EXTENDING INTO THE EVENING HOURS AS
DISTURBANCES ALOFT SWEEP NORTHEAST. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP OVER THE WATCH AREA LATER TODAY. A PLUME OF
ATMOSPHERIC MOISTURE ABOVE WHAT IS CONSIDERED NORMAL FOR THIS TIME
OF YEAR COUPLED WITH A LOW LEVEL JET SWEEPING DEEP GULF M0ISTURE
INLAND WILL CREATE THE CONDITIONS CONDUCIVE TO THE DEVELOPMENT OF
HEAVY RAINS AND RESULTANT FLASH FLOODING. IN ADDITION...THE STORM
PREDICTION CENTER IS FORECASTING A SLIGHT RISK OF SEVERE STORMS
ACROSS WESTERN PORTIONS OF THE FLOOD WATCH AREA INCLUDING THE I-35
CORRIDOR. WITH ALREADY SATURATED GROUND CONDITIONS...ANY FURTHER
DEVELOPMENT OF HEAVY RAINS OVER THE WATCH AREA COULD RESULT IN
RAPID RUNOFF AND RESULTANT FLASH FLOODING.

The SPC has our Metro/Hill Country areas included in the “slight risk” area for severe weather for today.  Here is the latest from their offices:

...CNTRL/SRN PLAINS TODAY AND TONIGHT...

   A CLUSTER OF ELEVATED TSTMS HAVE DEVELOPED THIS MORNING ACROSS PARTS
   OF NEB/IA/KS AHEAD OF AN MCV LIFTING NEWD THROUGH CNTRL KS.  THE 12Z
   TOP/OAX SOUNDINGS SHOWED THE PRESENCE OF AN ALREADY MODERATELY
   UNSTABLE ENVIRONMENT FOR PARCELS BASED AROUND 850 MB AND LARGE HAIL
   WILL BE POSSIBLE WITH THIS ACTIVITY AS IT PROGRESSES THROUGH THE
   MID-MO VALLEY TODAY.  OTHERWISE...12Z REGIONAL SOUNDINGS INDICATE
   THE POTENTIAL FOR STRONG AIR MASS DESTABILIZATION TODAY OWING TO
   8.0-9.0+ C/KM 700-500-MB LAPSE RATES ATOP A MOIST BOUNDARY LAYER
   WITH LOWEST-100-MB MEAN MIXING RATIOS OF GENERALLY 13.5-14.5 G/KG.

   THE ONGOING STORMS OVER THE CNTRL PLAINS/MID-MO VALLEY AND APPARENT
   EARLY EMERGENCE OF THE LOWER LATITUDE IMPULSE INTO THE SRN PLAINS
   CAST UNCERTAINTY ON SPECIFIC DETAILS REGARDING SURFACE-BASED STORM
   EVOLUTION TODAY.  IT DOES APPEAR THAT THE PRIMARY FOCUS FOR TSTM
   DEVELOPMENT WILL BE THE DRYLINE BY EARLY TO MID AFTERNOON FROM SWRN
   NEB SWD THROUGH FAR SWRN KS INTO THE CNTRL OR ERN TX PNDHL.  THE
   COMBINATION OF MODERATE TO STRONG INSTABILITY AND MODERATELY STRONG
   DEEP-LAYER SHEAR WILL SUPPORT SUPERCELLS AS THE INITIAL STORM MODE. 
   LARGE HAIL AND TORNADOES WILL BE THE PRIMARY HAZARDS WITHIN THE
   FIRST FEW HOURS OF INITIATION.  WHILE A FEW STRONG TORNADOES APPEAR
   POSSIBLE...THE TENDENCY FOR VEER-BACK SIGNATURES IN FORECAST
   HODOGRAPHS MAY RESULT IN AN EVENTUAL TRANSITION TO MIXED STORM MODES
   /I.E. SUPERCELLS EMBEDDED IN LINE SEGMENTS/ WHICH IS SUGGESTED BY
   SOME RECENT CONVECTION-ALLOWING MODEL GUIDANCE.

   THERE IS ALSO SOME SUGGESTION BY LATEST MODEL GUIDANCE THAT A SECOND
   BAND OF TSTMS DEVELOPS THIS AFTERNOON E OF THE DRYLINE FROM CNTRL KS
   SWD INTO N-CNTRL TX.  UNCERTAINTY IN THIS SCENARIO REMAINS
   HIGH...BUT SHOULD IT UNFOLD...ENVIRONMENTAL CONDITIONS WILL BE
   SUPPORTIVE OF EMBEDDED SUPERCELL STRUCTURES WITH A RISK FOR A FEW
   TORNADOES...LARGE HAIL...AND DAMAGING WINDS.  

   UPSCALE GROWTH OF STORMS INTO ONE OR MULTIPLE MCS/S IS ANTICIPATED
   TONIGHT WITH A HAIL/DAMAGING WIND THREAT SPREADING EWD ACROSS LOWER
   ELEVATIONS OF THE GREAT PLAINS.

Happy Memorial Day everyone.  It may be a holiday to remember the sacrifice soldiers have made to make this country what it is.  However, today is a day to also remember a tragic day in Central Texas history.  This Memorial Day marks the 16th anniversary of the tornado outbreak of 1997, which included the F5 tornado in Jarrell.  Here is the history of what happened on May 27,1997:

In the early morning hours of May 27, a large MCS developed over Eastern Oklahoma and Western Arkansas. A “gravity wave” or outflow boundary was generated by this system and stalled out over Central Texas. This was oriented from the northeast to the southwest, causing the movement of the supercells later on to be to the southwest, along with most of the tornadoes, which is extremely unusual. Also unusual on this day was the low wind shear and extreme instability.

That incredible instability ended up spawning multiple tornadoes across the state of Texas.  Here is a list of all of the confirmed tornadoes from that unforgettable day.

Here is a brief synopsis for 3 of the strongest tornadoes that touched down that day:

F-5 Jarrell tornado

Initially a weak pencil-like tornado near the Bell-Williamson County line, the funnel rapidly intensified into a 3/4 mile wide multi-vortex storm at around 3:45 PM CDT.

Its first damage occurred three minutes later at 3:48 PM CDT in the northwestern portion of Jarrell striking Double Creek Estates, sweeping away the entire neighborhood. It moved to the south-west, which is unusual for tornadoes in North America. It later entered a wooded area before dissipating after damaging numerous trees.  Another unusual thing about this tornado is that there was no clear “hook echo” in the radar, which is usually visible in strong tornadoes.

Grass and soil in fields near Jarrell were ripped out of the ground to a depth of 18 in (46 cm), reducing lush fields of grass into wide expanses of mud. When the tornado crossed county roads outside Jarrell, it tore a 500-foot (152 m) length of asphalt from the roads.

About 40 structures were completely destroyed by the tornado and dozens of vehicles were rendered unrecognizable after being thrown great distances, some more than half a mile. Some of the vehicles were pulverized into many pieces and strewn across fields, and others were simply never found. A steel frame recycling plant was completely obliterated, with nothing left of the structure but the foundation and a few mangled steel beams. Telephone poles in the area were snapped off at the base and splintered, and trees in the area were completely shredded and debarked. Many researchers, after reviewing aerial damage photographs of Double Creek Estates, considered the Jarrell storm to be the most violent tornado, in terms of damage intensity, that they had ever seen.  Many of the homes in the tornado’s path were well-constructed and bolted to their foundations, but the tornado left only the slab foundations, and there was no debris left in the area.  The debris from the destroyed homes was finely granulated into small fragments, and scattered for long distances across the countyside. Several entire families were killed in the tornado, including all five members of the Igo family and all four members of the Moehring family.  The tornado’s slow movement combined with the high winds is the reason why the tornado was so destructive. The tornado also picked up a lot of loose soil, giving it a sandblasting effect on the houses. Only one person was seriously injured and less than a dozen people suffered minor injuries after the tornado, a testament to the small probability of survival in the Double Creek neighborhood. 

There were 27 human fatalities in the Double Creek subdivision. In addition, about 300 cattle were killed by the storm.

About 10 minutes prior to the main event, eye-witnesses spotted additional tornadoes north and west of Jarrell

F-3 Cedar Park Tornado

Around the same time as the Jarrell Tornado, another strong tornado formed about 30 miles south in Cedar Park.  The tornado formed about 3 miles north of the city causing widespread F-0 and F-1 damage. The tornado continued south until it reached the central business district where it did extensive damage to an Albertson’s Supermarket damaging most of the store and severely injuring one person. The manager had put majority of the customers in the walk-in freezers, saving their lives. The tornado then continued south-southwest towards the Buttercup Creek subdivision where the tornado caused damage to 136 homes, all suffering between F-1 and F-3 damage. The tornado killed one person as he waited out the storm in his truck. The tornado then continued to move more southwest and finally dissipated about 1.1 miles away from the northern shore of Lake Travis. The tornado traveled 9.2 miles and had a maximum width of 250 yards

F-4 Lake Travis Tornado

About 45 minutes after the Cedar Park and Jarrell tornadoes, another strong, violent tornado formed on the southern shore of Lake Travis. The tornado rapidly intensified to a strong F-3 tornado, causing damage to a marina on shore. Then it increased to F-4 intensity, severely damaging a reinforced building containing a telephone switch center and completely destroying a stone house, only leaving the foundation slab behind. The tornado then headed south for a brief period before turning southwest then turning west-southwest, heading towards the Hazy Hills subdivision in the Pedernales Valley in western Travis County. The tornado damaged the subdivision, causing mostly F-3 damage to 45 homes with some of those completely destroyed, showing F-4 damage. This tornado killed one person as he tried to outrun the storm. The tornado then exited the subdivision and dissipating after travelling 5.6 miles with a maximum width of 440 yards.

The F5 Jarrell tornado is ranked #10 in the top ten deadliest tornadoes in Texas history.   Here is that list:

With that being said it is a perfect time to remind everyone why NOT to leave your children or pets unattended in a vehicle in the hot sun.  Here are some facts from the Safe Kids Texas Heatstroke Task Force:

It is against Texas law to leave a child under age seven unattended in a vehicle for longer than five    minutes. Last year, the Safe Kids Texas Heatstroke Task Force presented Badge of Courage Awards to a San Marcos woman and a Lubbock woman, each of whom called 911 to report an unattended child in a vehicle. In both cases, EMS arrived quickly and the children were rescued without injury.

Safe Kids Texas Heatstroke Task Force

The Safe Kids Texas Heatstroke Task Force is composed of 166 community safety professionals throughout Texas, including law enforcement officers, nurses, health educators, doctors, county extension agents, and child advocates. During Heat Awareness Day, task force members will be conducting a variety of activities to remind us of the dangers of leaving children in cars and to promote the practice of the three preventive measures of ACT.

Also, don’t forget about our 23rd annual Summer Fan Drive!!

KXAN and Family Eldercare are teaming up once again for the 23rd Annual Summer Fan Drive. With summers in Texas reaching dangerous temperatures, the Fan Drive provides needy Central Texans with relief from the life-threatening heat.

For over 20 years, the Summer Fan Drive has been serving low-income seniors, individuals with disabilities, and families with children. Funds raised during the Fan Drive go towards the purchase of fans and air conditioners to help individuals and families beat the heat.

The community is encouraged to donate to this great cause and can help in different ways. One great way to help is by donating funds online atsummerfandrive.org. A donation of $15 will be able to help someone in need with one fan.

Fan Fare Friday, the Fan Drive’s main event, is held every year at the end of June at Threadgill’s World Headquarters. It’s a day of celebration to donate fans or funds and listen to some live music. This year’s event is scheduled for Friday, June 21st.

Fans for Fans is another great way to donate to this worthy cause. Every year, KXAN and Family Eldercare team up with the Round Rock Express for the Fans for Fans event. Express fans are encouraged to bring a fan in exchange for a pair of tickets to that night’s game. The date for this year’s event is still to be determined.

Help KXAN and Family Eldercare keep Austin cool this summer.

An upper level low pressure system over northern Mexico will move into west Texas tonight, then into the southern Great Plains on Wednesday. As this upper low approaches, an increasing chance for showers and thunderstorms is expected overnight across south central Texas. A few strong storms are possible, mainly along and south of the U.S. Highway 90 corridor. The main concerns are damaging winds and hail.

Even though many areas received impressive rain totals on Friday evening, we desperately need more.  Hopefully, considering Friday’s rain soaked the ground pretty well, tonight/tomorrow’s rain will filter down into the lakes.  Lake Travis is currently 43′ below normal levels and Lake Buchanan is 23′ below.  Here are forecasted rain totals through Wednesday evening from one of our computer models we use in the First Warning Weather Center.

An unstable weather pattern will develop over the Southwestern US, leaving a series of weak disturbances aloft to pass across South Central Texas late this week. The first round of thunderstorms expected from this pattern should tap into afternoon heating on Thursday, resulting in a chance of strong to severe thunderstorms that could extend well into Thursday night. Large hail and damaging winds should be the main severe threats. The unstable pattern is expected to continue into Friday and possibly into Saturday as remnant outflow boundaries promote an additional focus for thunderstorm development. Rain chances may be further enhanced if a weak frontal boundary moves south from North Texas.

Here is the latest write-up from the Storm Prediction Center:

 SCATTERED TO LOCALLY NUMEROUS TSTMS IN CLUSTERS SHOULD DEVELOP OVER
   PORTIONS CENTRAL TX INTO SRN OK...INVOF COLD FRONT AND DRYLINE...IN
   FAVORABLE ENVIRONMENT FOR LARGE HAIL AND DAMAGING GUSTS.  A FEW
   SIGNIFICANT/DAMAGING HAIL EVENTS ALSO ARE POSSIBLE...PARTICULARLY
   RELATIVELY EARLY IN EPISODE WHEN STRONGEST /DISCRETE UPDRAFTS AND
   SUPERCELLS STRUCTURES ARE MOST PROBABLE.  STEEP/EML-RELATED MIDLEVEL
   LAPSE RATES...60S F MOIST-SECTOR SFC DEW POINTS AND AFTN DIURNAL
   HEATING WILL CONTRIBUTE TO VERY STG PRE-CONVECTIVE BUOYANCY...WITH
   FCST SOUNDINGS SUGGESTING MLCAPE COMMONLY 2000-3000 J/KG AND UP TO
   AROUND 4000 J/KG IN SOME AREAS.  

This article may not focus directly on Central Texas, however it gives us much more respect for those Meteorologists given the task of predicting floods.   There are so many variables to juggle and sort out, that it seems flood prediction is impossible.  Well it may not be “impossible” but we still do have a long way to go before the kinks get completely worked out.  Enjoy and a big thanks to our friends at the Associated Press:

FARGO, N.D. (AP) — Perched in a boat drifting slowly along the Red River, Dan Thomas kept one eye on a laptop and the other on a $60,000 piece of floating hardware that beamed sound waves deep into the flooding river. As the signal bounced off water molecules and returned, the laptop sorted it into data on the river’s depth and speed and transmitted it instantly to the National Weather Service.

Once there, the work by the U.S. Geological Survey’s water expert became part of the data stew the weather service relies upon to regularly update crest projections for rivers like the Red, which rose again this spring to briefly threaten Fargo and neighboring Moorhead, Minn. And the complexity of the science was never more evident than this year, when an early forecast of 40 feet prompted costly sandbagging only to be repeatedly revised downward until the Red barely broke a harmless 33 feet.

The apparent false alarm irritated some residents who questioned why the city spent $2 million preparing for the flood that wasn’t. And that irritated Fargo Mayor Dennis Walaker, who has sparred with the weather service himself in the past.

“They all become experts,” Walaker said. “You can’t believe how many times I get stopped throughout the day by people who tell me the water is not going to get to a certain level.”

Greg Gust, the weather service’s warning coordination meteorologist in Grand Forks, acknowledged the agency had heard criticism of its projections for Fargo. He said it is constantly studying ways to improve its performance, but will always have limitations.

“Many times the weather service is being asked to do the impossible,” Gust said. “We’re being asked to forecast an unknown situation out into the future. We don’t have a perfect knowledge what’s going on today in the system, and yet we’re supposed to be able to forecast some unknown point in the future where clearly we have no knowledge.

“That said, that’s the task of a forecaster.”

Flood fights have become routine on the Red River at Fargo, but this one came nearly a month later than ever before due to winter conditions that refused to loosen their grip.

“We don’t have anything to go on when these things go on so late,” Steve Buan, a weather service hydrologist who works on river forecasts in the region, lamented as the Red was rising.

Flood forecasting in this part of the continent starts with models for determining how much snow is on the ground. Observers record every snowfall. But it’s even more important to figure out how much water is in that snowpack, which requires melting samples. It can also be done by going airborne to measure the natural radiation coming from the soil — a factor affected by the water in the snowpack.

Next up is more modeling on what will happen when the snow melts, which includes a dizzying number of variables. Is the ground frozen? How deep? How much moisture is in the soil?

Months of drought worked in Fargo’s favor this year. So did a freeze-thaw cycle that melted snow and warmed the soil during the day — giving runoff a place to go — and then slowed or stopped the melting overnight.

Weather service hydrologists get data on snow depth, water content, frost depths and soil moisture levels from many different sources, including their network of observers. That network has been bolstered in the Red River Valley over the last couple years by several high schools and middle schools participating in the River Watch program of the Fargo-based International Water Institute.

The students melt snow samples to see how much water is in their local snowpack, institute director Chuck Fritz said. They use frost tubes placed in the ground that contain chemicals that change color to show how deep the frost goes. And they use infiltration rings to measure how fast the ground can absorb water.

Wayne Goeken, a monitoring and education specialist with the institute, explained how infiltration rings work. They drive a 10-inch ring of PVC pipe about 2 inches into the ground in the fall. Then when the ground starts to thaw in the spring, students pour 4 inches of water into the ring and use a ruler to measure at one minute, three minutes, five minutes and longer intervals whether and how fast the water soaks into the ground. Then the schools feed that data to the weather service.

Forecasters run actual and predicted rainfall through their models, Buan said. They use more modeling tools for how the water will flow downstream. And they have to take into account potential changes in how much water is held back in reservoirs, such as Lake Traverse at the southern end of the Red River watershed.

Once forecasters have an idea of how much water is coming, their models also tell them about the relationship between the projected stream flows and how high the river will be at any given flow rate, which ultimately helps them predict how high the river will rise.

Most of those broad principles hold true for most river systems, Buan said. Perhaps the biggest difference between forecasting the Red and more southerly systems like the Mississippi’s is the need to account for frost in the ground in northern states and how it affects runoff rates, he said. The different topography is also a factor. The Red River Valley has almost no slope; the Mississippi has considerably more.

Predicting flooding on the East and West Coasts is a bit different from the nation’s midsection, he said. The Mississippi River watershed drains most of the country between the Appalachians and the Rockies, so floods in it tend to last longer. Eastern watersheds tend to be smaller and steeper so the floods come up quickly and fall quickly. Western rivers are often heavily dammed.

Thomas, the USGS hydrologist who was working on the Red earlier this week, said he finds the work fascinating.

“To me, just to see how deep the river is and how fast it is flowing is interesting,” Thomas said.

And Goerken said he reminds students that what they’re doing isn’t just an academic exercise.

“Maybe you can’t be there laying sandbags in Fargo, but this is a valuable contribution to the flood fight, too, so people know what’s coming their way,” he said.