Joplin, Revisited

The NWS put out their final assessment of the infamous EF-5 Joplin tornado that occurred on May 22.

The report didn't touch much on the final death toll. 159 people lost their lives in the tragedy, the most from a single tornado since 1953. The report also didn't cover the damages caused.

What the report did cover, in great detail, was the processes that lead up to the warnings being issued ahead of the tornado and the response the citizens took to protect themselves. The findings of the report are somewhat surprising!

The NWS Assessment team took an ethnographic approach to conducting some of it's research. The report stated that ethnographic techniques were used to, "Understand residents points of view regarding the process of warning receptions to warning responses and how decisions were made."

I am big fan of this approach. It definitely helps to know your target audience, in any situation! Understanding the thought process of the citizens is a huge first step to improving warning timing and distribution. Over 100 people were interviewed for the report. One of the more important findings was how the people in the path of the twister processed the warning information.

In this day and age, social networking is huge. Facebook, Twitter and text messaging are huge communication tools. These are great ways to get information out. Meteorologist James Spann, who covers the Birmingham, Alabama market, has utilized these tools about as well as anyone can. He sends out tweets and posts that pertain to weather watches and warnings in any part of his television viewing market. There is great potential in social networking when it comes to severe weather. The problem with it is two-fold. First, not everyone uses social media. Those who don't would then have to find their warning information elsewhere. The second problem to this is validity. Not everyone who is posting about a tornado or thunderstorms are trained experts. So there could be a lot of false information flying around out there.

Social media can be one method of risk awareness. What are others? Many towns in Tornado and Dixie alley have tornado sirens. Weather radios are common as well in these parts. T.V. weather reports are the best way to get access to severe weather information. In Joplin, it is "community policy to sound sirens when a tornado is moving towards Joplin OR a severe thunderstorm with expected winds to exceed 75 m.p.h." This causes a big problem.


When the sirens go off, what are they warning for?!?! There is a large difference between a severe thunderstorm with damaging winds and a tornado. While both can be destructive, a tornado is far more deadly than strong winds. There needs to be clarification between the two events. The people in Joplin on May 22nd had to process two different blasts of the siren. This should have been all it took for people to act. However, the report found out that people acted, "after processing a variable number of risk signals...". In a deadly, EF-5 tornado situation, people can not afford to take time and contemplate a "variable number" of warnings. There were many reports that people did not act until they visibly saw the tornado! Why weren't the sirens enough?

Several people who were interviewed said that tornado sirens have lost their credibility. A few of the responses show why:

 "the sirens have gone off so many times before"

"bombarded with sirens so often that we don't pay attention"

"...[the sirens] go off for dark clouds"

These responses go to show that people who live in tornado-prone areas are probably desensitized to the sirens. Folks would point to data to prove why they treat the sirens with such complacency. In all tornado warnings issued by the NWS nationally, it was found that over 75% of the warnings were false alarms. That information was averaged over roughly the last 4 years. So it is easy to see why people assume that a tornado siren is just someone crying wolf! But here is the bottom line, every environment is different. On this particular day, the environment was primed and ready to fire off dangerous, long-track storms. So you just don't mess with weather, even if it means you have to take to safety for 20 minuets or so.

What needs to be done to prevent this confusion and complacency again? It is critical that the NWS, media members and community officials are on the same page when it comes to warnings and stressing immediate action. Sirens need to be blasted for one type of event only. A reverse-911 action plan may help as well. Anything that puts emphasis on the danger of the situation and allows enough time for action to be taken.

This problem of complacency runs far past tornadoes and Joplin, Missouri. When faced with an approaching hurricane, several people disregard warnings and evacuation requests to ride out the storm because they think that the weather man is wrong, or that it would never happen to them. It is downright foolish to challenge mother nature. The minuet you don't respect it, it can take your life. 

Here is the link to the full NWS Joplin Tornado Assessment

La Nina Returns?

NOAA has put out a La Nina Advisory for the 2011 winter season. That's right folks, La Nina appears to have re-developed and is here to stay a bit longer than first thought.

What exactly does La Nina mean, you may be asking? It essentially is a cooling of Sea Surface Temperatures (SST) in the central and eastern portions of the tropical Pacific Ocean. The set up has warmer than average SST's over the western Pacific and cooler than average SST's in the central and eastern Pacific. La Nina typically occurs ever 3-5 years but consecutive episodes occur nearly 50% of the time, according to the NOAA Climate Prediction Center. While La Nina stems from the anomalies of SST's, its impacts go way beyond ocean temperatures.

Sea Surface Temperatures showing a cooler eastern Pacific which signals a La Nina return. Via NOAA CPC.

Winter of 2010 in the United States was a record-setting one. High snowfall totals lead to record Spring flooding and severe weather that was off the charts! The exceptional drought that is on-going in the South...yup, put that one on La Nina. Wichita Falls, TX became the first location with 100 days at or above 100 degrees this year! So the news that La Nina has reformed does not offer much in the way of relief.

What can we expect for winter 2011? Average La Nina winters cause wetter than normal conditions here in the Pacific Northwest and can often expect cooler than average temperatures, too. La Nina doesn't offer much drought relief during the winter months either for those in the South and Southwest,

“This means drought is likely to continue in the drought-stricken states of Texas, Oklahoma and New Mexico,” said Mike Halpert, deputy director of the Climate Prediction Center.  

 

Typical La Nina setup

Beyond the upcoming winter, it is tough to tell just how long and strong La Nina will be. Should it last into next Summer, it could mean another active hurricane season. During the 2010-11 La Nina conditions, forecasters predicted a very active tropics with 14-19 named tropical storms. As of today, we are sitting at 14 named storms this season. Pretty good, huh? With those cold waters in the Pacific, oceans try to balance out by warming up the tropical Atlantic waters to above average temperatures. So, if La Nina lingers around for another Summer, things could be active again.


With La Nina's anticipated return, records could fall again this winter. That would not be welcome news to most.

Tropical Patterns

Katia has reached major hurricane status in the Atlantic. After Irene lashed the Carolinas and skirted the Northeast, Katia has a lot of east-coasters holding their breath. As Katia formed, I had mentioned that the storm track appeared to take it out to sea and avoid being the second storm to hit the east coast in a month. So far, so good. Here are computer models for Katia's track.

All models have the storm re-curving out to sea. However, a common issue with tropical forecast is that a forecaster may wind up "riding" the models and forecasting what the computers spit out. When it comes to tropical forecasting, patterns almost work better than guidance.

Gut feelings often can be the best forecasting tool, assuming you have knowledge of the situation. Now, being from the Pacific Northwest, I obviously have little knowledge of topical histories. But having picked up a few hints along my studies have helped me to generate some opinions about the 2011 tropical season. My gut instinct was that Katia would curve out to sea. Here is why I stated that.

Take a look at Katia's actual track below.

Let's take a look at where Katia formed. Katia got tropical depression status at roughly 26 degrees West latitude and a day later was a tropical storm at roughly 33 degrees West latitude. So Katia formed rather quickly off the west coast of Africa. Through historical observations made, it has been determined that 90% of all tropical cyclones that develop EAST of 35 degrees West latitude will RE-CURVE off to sea. That is the exact situation we have with Katia. This was my first clue.

My second clue came through a process called teleconnectoins. Meteorologists use teleconnections in order to "anticipate" what may come down the road for a specific location but is used in the most general sense. The basics of this is this: what is occurring in the western Pacific (off coast of China/Japan) will occur on the U.S. east coast roughly 6-10 days later. Nothing is specific, it just assumes general trough/ridge patterns. Teleconnections can help forecast the track of a storm brewing in the Atlantic. When Katia formed, I took a look at what was occurring in the western Pacific. A trough was located just off the coast of Japan. So I inferred that this trough would generally move eastward and ultimately pull Katia out to sea when she wanders towards the U.S. coast!

I've been told it's better to go down on your own forecast than someone else's. So I decided to own my gut instinct and say what I thought; Katia will miss the U.S. and re-curve out to sea. I'm more than happy to live and die by my own forecast. That was a valuable advice given to me by one of my teachers whom I greatly respect.

Looking ahead, we have a new tropical disturbance developing in the east Pacific. Invest-95 has a high probability of becoming a tropical cyclone. Let's compare the track of Katia to that of Invest-95. 

Invest-95 has formed a little south of Katia's track, and is forecasted to track a bit north of Irene's path. Lots of time however for Invest-95 to change, so I'm not making a call on this yet.

Hello, Irene

Here we go! Hurricane Irene has taken shape and developed into a category one hurricane. Irene has already pounded Puerto Rico with strong winds and heavy rains that have left some 800,000 people without power.

At its current location, Hurricane Irene is traversing the most hostile location for a storm. The islands of Puerto Rico, Haiti, Dominican Republic and Cuba are all road-blocks for any tropical system that passes them. Their mountainous terrains threaten to rip apart the structure of any well developed storm. Just a month or so ago, Tropical Storm Emily found this out. Emily wandered into Hispaniola and was all but destroyed by Haiti and the Dominican Republic.

However, with Irene, we have a different and more dangerous situation playing out. Irene has taken a more northerly track as a tropical storm. It has just brushed Puerto Rico and during that time strengthened from a Tropical Storm into a Hurricane. What stands in Irenes' way now? Below, current National Weather Service track has it moving northwesterly, its next stop in the Bahamas.

Current models back the NWS forecast. A big blocking ridge over the central U.S. will prevent Irene from moving west in the Gulf of Mexico. A trough over the mid-Atlantic will allow Irene to cut a path along that trough and "feel" its way into making a South Carolina landfall.

This forecast track will keep Irene away from those big islands in the Caribbean and allow the hurricane to move over very warm waters. The warm waters act like fuel to the storm and will allow it to develop and intensify. In fact, the NWS is currently showing Irene making landfall as a major hurricane (in order for a storm to be classified as a "major hurricane", wind speeds must reach 110mph or greater).

A lot can happen between now and Irenes' landfall, which is sometime Saturday morning. Models are changing hourly for this storm so it will be important to keep an eye on the changing conditions. But for the first time since 2009, the United States is looking at our first serious hurricane landfall!

Emily Taking Shape in the Atlantic?

It is a long ways out (meteorologically speaking) but a great tropical system is about to take shape in the tropical Atlantic. Long range models are showing a well-developed center of low pressure forming and making landfall on the southern tip of the Florida panhandle. This storm, should it become a tropical depression/storm/hurricane will be the 5th such storm this season. Storms are named once they reach a Tropical Depression status with a distinctive closed circulation. Should this disturbance reach that stage and from all indications it will, Emily will be its name!

What kind of shot does Emily have of actually making a U.S. landfall? Let's take a look.

Here is a look at the precipitation forecast from today that is valid for this Thursday. Notice the high precipitation forecast down in the Caribbean near the Dominican Republic. By this point, Emily should be at the least a Tropical Storm. The wild card to development is whether or not the storm makes landfall on Hispaniola. If it does, Emily could be torn apart by the friction of the land. But hurricanes don't like to be on land, so sometimes a storm will shift its path to avoid land and actually just skirts right around it. If that happens, the storm will have more chances to intensify in the warm waters.
This forecast is valid for Saturday morning. Clearly the model is showing Emily making landfall in southern Florida. But is there a shot that Emily misses the Unites States entirely and just swings out to the open Atlantic? Of course, but the "steering mechanism" reinforces a U.S. landfall.
The 500mb map shows us "roughly" where systems will go. Two things to note in this map, valid for Friday. One: The high pressure over the a bulk of the South. Circulation around the high pressure is in a clockwise patter. You can visualize air moving around the central area of high pressure. Winds will "pull" Emily onshore, giving us the landfall the models have shown above.
The second point is the ridge of high pressure that is building up in the New England area. This is critical to storm intensification. Higher pressures to the north means lower pressures to the south and that helps deepen the low that enters the Caribbean/Gulf of Mexico region. These two points back up the prediction of Emily making an intense landfall.

But just a few days later, things appear to change. This map is valid for next Monday, a week out. The high pressure region over the South has disappeared, due to Emily interacting at close range with the high pressure area. Along with the weakening high pressure, a trough just off the N.E. Atlantic coast has developed. Notice the wind barbs are showing a westerly flow. Emily will "feel" this trough and hitch a ride with it. Eventually, Emily will be pulled out to the Atlantic.
The precipitation map valid for next Monday does show Emily moving back over Atlantic waters and a rapid weakening of the storm will continue. The evolution of Emily will depend on several things, most of which I have mentioned. Land and intensification play roles, but so does storm speed (fast or slow moving) and water temperature. Nearly 7 days out however, Emily may become the first named storm in nearly 2 years to make landfall in the United States!

No End In Sight

The Pacific Northwest continues to be mired in a Spring-like run of weather in the middle of Summer. Today marks the first day that average temperatures should reach 80 degrees, yet we are currently in a stretch of 8 consecutive days below 80 degrees. And then comes even worse news: there isn't an end on the horizon. Let's see why:


Above is our trusty 500mb chart. This is a set up known as the "Omega Block" because the graph resembles the Greek letter Omega. It is caused by a large ridge of high pressure over the Central U.S. and troughs on either side of the ridge. Under a ridge this big, hot air is sinking to the ground, resulting in scorching temperatures that have brought several days of triple digits. All we are stuck with is cool, gray conditions and some rain this week. That huge ridge blocks systems that typically track north into Canada but are now forced down into our backyard. This Omega Block has been set up for the better part of a week now and things aren't changing a whole lot.
This map is an anomaly chart that shows the average 500 mb lines from multiple model runs with different starting parameters. It basically gives us a an idea of where ridges and troughs will be 8-14 days in the future. Notice the big ridge over the Central U.S. has subsided a bit but the general trough in the NW/ridge in the East pattern still exists. That's not a welcoming sign for a return to Summer!
Here is a temperature probability map that correlates with the 500mb map 8-14 days out. I think this is pretty self-explanatory. Blues mean below average, red above. Yadda yadda yadda. Summer appears to be on hold until further notice. Maybe it's time to take a vacation...

Arizona Duststorm

A huge and rare weather phenomena occurred this week in Phoenix, Arizona. The storm has an odd name too, one that we LOVE to say around the station here. The event is known as a "haboob". The haboob originates from Arabic and is common in arid regions of the world like Saudi Arabia and the Sahara desert. The giant cloud of dust is rather impressive and can cause near-black out conditions with zero visibility. Check out this video time-lapse on Scott Wood's photography page:
http://www.scottwoodphotography.com/Weather/2011StormChasing/15913598_nN77g#1370278891_RDCLM67

Really incredible! But how exactly do these "haboobs" develop? The geography of the Phoenix area is set up just right for these events. During the summer seasons, a monsoon develops. People often mistake monsoon with a very intense period of heavy rainfall. In fact, the monsoon is a seasonal reversal of wind patterns. The heavy rainfall is just a result. In Arizona, the Summer monsoon winds come off the moist Gulf of California from the Southwest and push up against the Colorado Plateau, to the Northeast of Phoenix. As this moist, gulf air is forced to rise up the plateau, thunderstorms are generated over the top of the dusty plateau. These thunderstorms can be very intense and produce lots of rainfall in a short period of time. That rainfall eventually cools the center of the thunderstorm and forces cold air to rush out of the bottom of the storm, known as a downdraft. This downdraft, which acts like a mini-cold front, picks up all that dust and sand on top of the plateau and forces it down towards the Phoenix area! Thus, a resulting haboob. Here is an image of the setup for the haboob:
Following the dust storm, Phoenix was rocked with a pretty good thunderstorm. Those storms were sparked from the continued moist SW flow colliding with the rain-cooled downdraft air rushing out of the older thunderstorms over the plateau. They converge right over Phoenix and huge thunderstorms result! Again, this all results from the Summer monsoon in the Southwest! Monsoons occur all over the world, the most famous being the South Asian monsoon in India and Myanmar. Summer monsoons are critical in delivering rain for the growing seasons in that part of the world. Winter monsoons exist as well in South Asia. High pressure over the Tibetan Plateau keeps things cold and dry. All over the world, the monsoon creates unique and wild weather!