Become a registered storm spotter this weekend

February 18th, 2015 at 7:18 am by under Weather

Saturday / 21 February 2015 – 815am to 330pm
24th Annual Lou Withrow SkyWarn Training Session (Basic and Advanced Training)
ACC Eastview Campus, Building 8500
3400 Webberville Road, Austin, TX 78702

— PLEASE PARK IN LOTS B, C, D or F ONLY —
— DO NOT PARK IN FACULTY/STAFF LOTS —

SkyWarn trainer:  Paul Yura, NWS/Austin-San Antonio Warning Coordination Meteorologist

Keynote speaker:  Dr. Kevin Kloesel from the University of Oklahoma

SkyWarn web info page (including parking lot map)

Updated South Central Texas SkyWarn Spotters Guide (pdf)

This day of training is free and open to the public and recommended for…
. storm spotters
. amateur radio operators
. law enforcement and first responders (PDs, FDs, EMS, etc)
. news media (reporters, photographers)
. governmental agencies (EMs, etc)
. anyone with an interest in learning more about severe and inclement weather


Do recent global precipitation anomalies resemble those of El Niño?

February 17th, 2015 at 8:15 pm by under Weather
(Climate.gov)

Since October 2014, sea surface temperatures (SST) across the tropical Pacific have exceeded the thresholds of weak El Niño (1), but the atmosphere has failed to really participate. Otherwise, we’d have seen above-average convection (thunderstorm activity) in the central tropical Pacific Ocean, a weakening of the surface trade winds, and a lowering of the Southern Oscillation Index and the Equatorial Southern Oscillation Index (2)—none of which showed up consistently.

However, how much does the atmosphere matter? Can the warm SSTs alone have global climate impacts? While the answer may vary depending on location and type of impact (3), here we ask whether the most recent season (the November 2014-January 2015 average) showed global precipitation responses that resemble those expected during El Niño.

What was the global precipitation pattern during November 2014 to January 2015?

Figure 1 shows the pattern of the deviations from average (or “anomalies”) of precipitation across much of the globe for the November to January average. The brown color shows regions receiving below average rain and/or snow, and green shows above average.

Figure 1. Observed precipitation from November 2014–January 2015, compared to the long-term average (in mm). Below-average rainfall is shown in brown; above-average rainfall is green. Data from CAMS_OPI, produced at NOAA/Climate Prediction Center.

Over the United States, much of the Ohio and Mississippi valleys were somewhat drier than average, while southern Texas and part of Florida were wetter than average. In South America, most of Brazil had below average rainfall. How do these patterns, and the many other features shown in Fig. 1, compare with the historically expected patterns during El Niño?

What should it have looked like?

Figure 2 shows the expected pattern of El Niño precipitation anomalies for November-January, based on an analysis of the historical data from 1981 to the present (4). At first glance, the historical El Niño pattern does not look much like what happened this year. For example, in the United States during El Niño, above average rainfall would be expected across a wider range of the southern United States. The area of below average precipitation in the Ohio and Mississippi valleys in the recent observations is broader than seen in the historical El Niño pattern (See footnote 5 for more detail for the United States).

Figure 2. Geographic pattern of deviation from average precipitation expected for November-January during El Niño, based on a statistical analysis of data from 1981 to present. The “classic” El Niño rainfall signal in this season is above-average rainfall (green) in the east-central tropical Pacific, the southern United States and Mexico, and the Horn of Africa, with below-average rainfall (brown) around Indonesia, over the Caribbean and northern South America, and across southern Africa. Units are relative, not physical. Map based on analysis by Dr. Brad Lyon at IRI, Columbia University.

Outside of the United States, the most obvious disagreement between the typical El Niño pattern and what occurred this year is in the central and east-central tropical Pacific Ocean itself, where the observed rainfall was below average while during El Niño it would nearly always be above average. El Niño normally is associated with below average rainfall over Indonesia and northern Australia, which was generally not observed this year. The same can also be said about southern Africa. In South America, on the other hand, there is moderate (but far from perfect) agreement with the expected El Niño anomalies. So, overall, how did the observations stack up?

And now the math…

Read the rest of this entry »


Did Austin Marathon, Half Marathon runners go faster because of the weather?

February 15th, 2015 at 11:49 am by under Weather

The question isn’t a new one, but it arose this morning when discussing the feats of the Austin Marathon and Half Marathon runners. The forecast was a muggy one, with AM patchy fog in the area:

2-15 Marathon

Fog itself is not a sort of precipitation, as most people think: it’s actually a type of atmospheric suspension, which is created by water vapor condensing into tiny water droplets that are light enough to remain in the air. Fog is most likely when there are fewer than 4 degrees that separate the air temperature and the dew point temperature. Note the places where fog exists when air and dew point temperatures are compared (as an example from this morning):

002 0021 0023

Where the dew points are generally within 4 degrees of the air temperature, you can see that visibility is reduced, due to fog formation. This example demonstrates that fog, made from water vapor, was present this morning. Water vapor is the real item we’re after.

A good blog on all things weather comes to us from Meteorologist Jeff Haby, who produces TheWeatherPrediction.com. Here is an interesting read on the ways that an object traveling on the Earth can be affected by the weather. Haby notes air pressure, air temperature, wind direction/speed and humidity, using the example of a baseball that has been hit and is traveling away from home plate.

Kacy Clemens

 

(“Texas’ Kacy Clemens hits an RBI single against Houston in the fourth inning of an NCAA college baseball tournament super regional game in Austin, Texas, Friday, June 6, 2014. (AP Photo/Michael Thomas)”)

The chemical composition of a molecule of air allows for anywhere between 0.01% – 4.24% of breathable air be made up of water vapor. Check that out here. Below is a table of what air molecules are made from, but the gist is that Oxygen (O2) and Nitrogen (N2) are “heavy” at a molecular level, while water vapor is “light.”

Untitled

 

(This image is from Wikipedia, which certainly doesn’t know everything, but usually gets its tables right!)

Combined, O2 and N2 make up about 99% of an air molecule. If there’s more water vapor in the air, it forces a displacement of N2 and O2 from the area (of equal pressure, temperature and volume) around it. Thanks to Avogadro’s number (it’s nerdy: check out the definition here), the number of molecules has to be the same. So lighter ones (water vapor) push the heavier ones (dry O2 and N2 molecules) out.

That means that, regardless of the way moist air FEELS sticky and sluggish, it is actually LIGHTER than dry air. If the air is lighter, there is less friction to force an object to slow down, like baseballs … or, in the case of today, humans.

The Austin Marathon and Half Marathon were also helped by a relatively mild air mass. Warmer air = lower air density. Higher temperatures force a parcel of air to expand, which increases volume and lowers density. We like to think about it like this: if you heat up plastic, sealed package of, say, broccoli (gross!) in the microwave, that package will expand ( = increased volume). If you were then to take that puffy package and measure how many pieces of broccoli were in each cubic inch of space, you’d find that they were fewer broccoli bits than when the package was cold and small. The density of air molecules works the same way!

BOTTOM LINE: with all other things being equal, a mild, moist air mass over Austin today may have helped propel the Austin Marathon and Half Marathon runners just a little bit faster. (Congratulations to all the finishers and winners of the race!)


Snow flurries in Central Texas? The risk explained

February 13th, 2015 at 10:50 am by under Weather
Snow in Harper (Brenda Blair/Jan. 2015)

Snow in Harper, NW of Fredericksburg (Brenda Blair/Jan. 2015)

An Arctic cold front with attendant storm system may join forces to create a few snow flurries in Central Texas during the early part of next week.

We’re tracking a significant cold front poised to sweep through Texas early Monday morning, dropping temperatures 30+ degrees from weekend 70s to near-freezing work week readings. At the same time, a “cut off” upper-level low pressure system is sitting over NW Mexico today through the weekend, forecast to rejoin the atmospheric flow and sweep over Texas late Sunday through early Tuesday.

Read the rest of this entry »


Why does sound carry farther on cold, calm mornings?

February 13th, 2015 at 8:07 am by under Weather

As I was getting ready for work early this morning, I heard the distinct, extended blast of a train horn coming from the tracks that run alongside Mopac (Loop 1) through Central Austin.

But that train is miles away from my home–and furthermore–I can’t hear it every time a train runs through. Why?

The answer has to do with how temperature inversions affect sound waves.

Typically, the atmosphere is warmer down low and colder up high (think of how comfortable it is at the surface, but how cold it is outside of your airplane window).

temperature inversion is when a layer of cold air is sandwiched between the ground and warmer air above it–the opposite of the normal temperature profile.  Temperature inversions often set up at night when skies are clear and winds are calm.

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Austin Marathon and Half Marathon forecast

February 12th, 2015 at 4:03 pm by under Weather

marathon logo

SUNDAY RACE FORECAST

See the table below for very specific hourly forecast details, beginning at 5 a.m. Sunday morning. Here are the highlights:

Sunday Morning:

Mostly cloudy, with patchy fog around sunrise.  Look for a few breaks in the clouds around noon.

South winds 5-10 mph.

7 AM: 54º

8AM: 55º

9AM: 58º

10AM: 61º

11AM: 64º

Noon: 66º

Date 02/15 02/16
Hour (CST) 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00 01 02 03 04
Temperature (°F) 54 54 54 55 58 61 64 66 68 70 71 71 70 68 65 62 59 57 56 54 53 52 51 50
Dewpoint (°F) 53 53 53 55 55 56 57 58 58 59 59 59 58 58 57 57 56 56 55 54 53 48 46 47
Wind Chill (°F) 48
Surface Wind (mph) 3 2 3 3 6 7 9 10 10 10 9 9 8 8 8 8 8 6 5 5 5 7 8 7
Wind Dir S S S S S S S S S S S S SSE SSE SSE SSE SSE SSE SSE S SE NE N N
Gust
Sky Cover (%) 78 84 89 89 93 91 91 89 94 94 98 97 97 96 96 96 95 97 97 98 97 97 96 97
Precipitation Potential (%) 5 20 20 20 20 20 20 20 20 20 20 20 20 40 40 40 40 40 40 40 40 40 40 40
Relative Humidity (%) 95 97 97 97 92 83 79 74 70 69 66 66 66 69 77 83 91 95 98 100 98 87 83 87

 


Report: Decade of drought has little effect on Texans’ water knowledge

February 12th, 2015 at 10:50 am by under Weather

TWF Logo A Decade of Drought Has Little Effect on Texans’ Water Knowledge, New Research Shows

A new statewide poll commissioned by the Texas Water Foundation (TWF) shows only 28 percent of Texans indicate they “definitely know” the natural source of their drinking water — the same percentage as 10 years ago.

This result is troubling — especially after a period of record drought — because research shows a direct correlation between knowing where one’s water comes from and one’s willingness to conserve.

“You’d think that a decade of drought would get people to pay attention to where their water comes from,” said TWF Executive Director Carole Baker. “Maybe we shouldn’t be surprised that nearly three-quarters of Texans don’t know where their water comes from since the state of Texas has not invested in conservation education. But in North Texas, they’ve proven how increased knowledge can dramatically curb water consumption despite tremendous population growth and lingering drought.”

Read the rest of this entry »


Austin Marathon and Half Marathon Hourly Forecast

February 11th, 2015 at 2:53 pm by under Weather

marathon logo

It’s just a few days away.  Weeks and months of training, hopefully has prepared  contestants, for the long road ahead:

Venue:  The beautiful city of Austin, TX

When:  Sunday, February 15, 2015

Who:  Athletes, running enthusiasts, men, women, and children from all over the world

What:  A grueling 26.5 mile (13.25 mile for half marathon) journey to test body, mind, and soul.

 

*For all information reguarding the 2015 Austin Marathon and Half Marathon click here:  http://youraustinmarathon.com/

 

maration 1

 

Here is your First Warning Weather Hourly Forecast for the race!!  Good luck everyone!!

TIME

EVENT

TEMP

RELATIVE

HUMIDITY

WINDS

SKY

CONDITIONS

4:00 AM

Light

Breakfast

48

87%

South –

Light

Partly/Mostly

Clear

5:30 AM

Gear Check

Opens

47

89%

South –

Light

Partly/Mostly

Clear

7:00 AM

All Races

Start

47

90%

South –

Light

Partly Cloudy

11:00 AM

Half Marathon

Closes

59

75%

South

5-10mph

Partly Cloudy

2:00 PM

Marathon Course

Closes

67

58%

SSE

~10mph

Partly to Mainly Cloudy

5:00 PM

Dinner/

Naptime

68

57%

SSE

~10mph

Partly to Mainly Cloudy


Brief history of lightning detection technology

February 11th, 2015 at 9:11 am by under Weather

(Courtesy: SciJinks)

Photo of lightning over Atlanta
Credit: David Selby

A Multipurpose Invention

The first lightning detector made the invention of the radio possible. Lightning and radio may sound like unrelated concepts, but they are more similar than you might think.

Have you ever put a cell phone or other electronic device near a radio? You may have heard weird crackles and pops. That’s because electricity generated by the phone makes radio waves that mess with the radio.

Lightning, too, creates radio waves. Radio waves—just like light and heat—are part of the electromagnetic spectrum. It makes sense that lightning would generate them. That’s what Alexander Popov was thinking when he set out to build a long-range radio wave receiver to detect lightning back in 1895.

Read the rest of this entry »


Climate calculator lets you create a new world

February 10th, 2015 at 2:55 pm by under Weather

(Climate Central)

Have you always wanted to wield the power of a world leader but been unable find a suitable in? Well, your search may finally be over.

The U.K. government has released its Global Calculator, a climate model hitherto only available to world governments to understand how their actions work in concert to reduce global warming. Now the public can crunch the numbers to see how to keep the planet from warming more than 2°C (3.6°F), a politically agreed upon climate target.

A specific look at how energy supply and demand change under the different IPCC pathways.
Credit: Global Calculator

The key drivers of climate change are all available for the tweaking from energy sources, investment in carbon capture and storage, land-use change, transportation and even lifestyle choices like the amount of meat consumed globally. You can adjust each slider on your own to try to reach 2°C.

But if the paradox of choice leaves you too stunned to do anything, there are a number of pre-loaded pathways from a variety of sources. Some of those sources are ones you’d expect, such as one from the International Energy Agency and the Intergovernmental Panel on Climate Change, both at the forefront of climate and energy modeling. Others might be more surprising, such as the Vegan Society, which is exactly what it sounds like, and Shell, the world’s second-largest oil company.

What the different IPCC scenarios mean for energy use, greenhouse gas emissions and meeting the 2°C climate goal.
Credit: Global Calculator

Shell’s contribution is particularly timely as a portion of its shareholders and the company itself are planning to see if its business plan is compatible with the 2°C climate goal.

Meat consumption is a major driver of climate change. The graphic shows minimal meat consumption and raising fewer ruminants vs. heavy meat consumption and raising more ruminants.
Credit: Global Calculator

Adjusting the different sliders reveals just how much certain activities weigh on the climate. Diet, specifically how much meat the world consumes, is among the starkest choices. Not only how much meat but the type matter since raising ruminant animals such as cows, sheep and goats is one of the most greenhouse gas-intensive activities humans currently undertake. Reducing meat consumption would make a huge impact on global greenhouse gas emissions and increase the feasibility of reaching climate goals.

Land management is another area where huge gains (or losses) can be made. More efficiently managing croplands and forest can send greenhouse emissions plummeting.

What the scenarios all show is that the current pathway the world is on is not sustainable, nor are we close to meeting the climate goals. But there are pathways forward. It’s just a choice of which one and when the world decides to start walking down it. Or moving the sliders.

Author:

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