ImpactWeather’s resident space weather expert StormWatch Manager Fred Schmude weighs in on the current solar flare situation.

AR1476. Photo: spaceweather.com

As we continue to trend toward the peak of Solar Cycle 24 (expected to occur around mid 2013) we’re seeing an expected increase in frequency of sunspot activity on the surface of the sun.   Solar scientists pay particular attention to sunspots since some of the larger ones can produce large solar flares and if directed toward Earth can cause significant interruption to satellite and radio signals and even to the power system, which can in extreme cases lead to blackouts and potential damage to the electrical grid.  Some of these large solar flares are also followed by another solar phenomena called a Coronal Mass Ejection (CME) which is a hyper-concentrated burst of electrons and protons associated with the solar wind.  It’s this concentrated burst of energy that causes the problems.

During the past few days, solar scientists have been monitoring a new sunspot group called AR (Active Region) 1476 on the sun’s northeast quadrant.  The sunspot group is not only quite large but has a magnetic field dubbed a “beta gamma” which typically are quite dangerous and harbingers of potential large solar flares.   We expect AR 1476 to rotate toward the Earth-facing side of the sun over the next 5-7 days bringing a threat of solar flares.  It’s still too early to tell if we’ll run the risk of seeing any super large flares, but some of the top solar scientists will be anxiously watching AR1476 over the next several days.  More of these solar flare alarms are forecast over the next 6-12 months followed by a gradual decline from 2014-2015 as SC24 gradually weakens.

Click for more information and to register.

Two great events of astronomical proportions occur this weekend. Unfortunately, one will almost wash out the other.

First up: The Eta Aquarids Meteor Shower. The Eta Aquaids are a minor shower when compared to the bigger Leonids, but a meteor shower is a meteor shower and I know I’m not the only one who enjoys a quiet evening away from the screens (remember when you could just say “TV”?). Actually, the Aquarids are not a minor shower with estimates of 10 to 60 meteors per hour at its peak which occurs this weekend.

Meteors of the Eta Aquarids Meteor Shower originate from the debris trail of Halley's Comet. Photo: Wikipedia

The Eta Aquarids are associated with the constellation Aquarius as it appears their origin lies within Aquarius — one of the oldest and most recognized constellations along the zodiac. These meteors are actually the cast-offs of Halley’s Comet and can be seen each April and May as Earth passes through the trailing debris field of the famous comet (Halley’s is the only short-period comet visible with the naked eye from Earth and the only one viewable potentially twice in a human’s lifetime). Aquarius is not particularly bright, but it is large and prominent. Interestingly, recent research has revealed several stars within its borders that contain planetary systems.

It’s best to view the Aquarids in the pre-dawn hours to the east. If you can pick a place for viewing that will limit the light pollution from nearby cities you’ll be a step ahead of those who must attempt to overcome stray light from parking lots, interstates, billboards, airports and other unavoidable urban light sources. Unfortunately, the largest source of light pollution will be impossible to overcome and it’s the second astronomical feature of this weekend.

Full moons are the Joker to any meteor showers’ Batman and this weekend’s full moon coincides precisely with the peak viewing of the Eta Aquarids. Worse, this weekend’s full moon will be the popularly named “supermoon” as the moon’s elliptical orbit brings it closest to Earth. Meaning, of course, a moon larger in appearance and reflecting more of the sun’s light across the sky. This should effectively wash out the weaker Aquarids, leaving only the brightest to power through the moonlight.

Last year's supermoon over Germany. Photo: Wikipedia

You won’t find the term supermoon in any astrophysicist’s textbook. Coined in 1979 by astronomer Richard Nolle, it’s proved popular among non-professionals because, well, it fits. More importantly, it’s much easier to roll off the tongue than its proper name: perigee-syzygy of the Earth-Moon-Sun system (perigee: closest approach of an object to Earth; syzygy: referring to a new moon). The moon, without fail, indeed draws nearest to Earth at some point during its 27-day journey around Earth. However, it’s when it happens to occur during the full moon phase that it draws so much attention and trades in its merely larger status for super. As such, this supermoon will appear 14% larger and 30% brighter than the typical full moon of 2012. The last supermoon was in March of last year; it was classified as the largest and brightest supermoon of the past 18 years (great supermoon photos from last year).

As viewed from Earth, this is a comparison of the biggest and brightest supermoon in the past 18 years (March 19, 2011) and a more average full moon. Image: Wikipedia

Much has been made of the mystical effects of the supermoon but science has yet to draw any conclusions that lead to a connection between the closest Earth approach of the moon and earthquakes, tsunamis or volcanoes. Though the gravitational pull of the moon is strongest when the moon is closest to Earth, the increase is minimal. In short, the Earth is in no danger and residents of the fifth largest planet in the solar system can go about their lives as usual (until at least December 21st…ha, ha).

Is all lost if you’re a fan of meteor showers? Not at all! The biggest and brightest streaks across the sky will number only a few per hour, but that’s still a thrill each time it happens.

Next meteor shower: Southern Delta Aquarids, July 28-29, 2012. Dark skies are on deck.

ImpactWeather Meteorologist Andrew Artzer was home visiting his parents last week in Kansas. Ever the geeky meteorologist (his words, not mine), he recapped his visit with a detailed email description of the heat. Yes, the heat.

Andrew's Kansas thermometer - without all the digital whatnot. Photo: Artzer

Record high temperatures were set in Kansas last week and in other places too (Texas recorded highs above 100). The heat, however, was not the result of warm air mass streaming north from Texas or Mexico. Nor was it the result of an oppressive summertime high pressure system. Also off the hook: A convective heat burst which can rapidly heat the air near a thunderstorm. So what was to blame? Compressional, or adiabatic heating. Air rushing downhill, like from Colorado to Kansas, will compress and compression brings about heating.  Andrew’s email to his colleagues included regional weather observations indicating the heat wave across Kansas, plus a picture of his backyard thermometer which he “set up several years ago; it’s exactly 2m off the ground, is mostly shaded, and also well ventilated, so it’s set up just like [an official] reporting station, just minus the digital equipment and whatnot.”

Is it just me, or is it waaaay too early to be thinking about summer-like temperatures in the mid-to-upper 90s, let alone 100-plus? Trust me, it is! Those temperatures will be commonplace soon enough and I would prefer a few more cold fronts before jumping into the oven.

Can you imagine living in the pre-HVAC days? That would be a looong time ago, by the way, as even the Ancient Romans had a way of circulating water through the walls of houses which brought about a type of evaporation cooling. Even in the 1300s, evaporative coolers — affectionately known as swamp coolers — were a popular purchase in Iran. Air conditioning, the type based on compressing, liquefying then evaporating ammonia, didn’t come around until the early/middle 1800s when inventors discovered how to chill air and make ice. In 1902, electricity and Willis Carrier brought about the age of modern air conditioning. Life as we know it was born.

Mid-90s in Kansas, 100s in Texas. Image: Artzer

It’s possible to beat the heat, hard as it is to believe, without the benefit of electricity and ammonia. An article on Straight Dope from more than 10 years ago was resurrected by i09.com a couple of days ago stating, seemingly against common sense, that wearing black clothing can keep you cooler than wearing white clothing. The theory is simple: the color white reflects sunlight — radiant heat bombarding the surface of the Earth and all of us standing upon it. This is a good thing and this is a true good thing. However, and this is where physics, Straight Dope and io9 challenge convention, radiant heat is not only coming from the sun — it’s coming from you, specifically your body. Meaning, though the outside of your white T-shirt is reflecting sunshine away from you, the inside of your white T-shirt is reflecting your own heat back to you. Not good. The solution is to wear black, not white.

And you thought the nomadic Tuaregs of the Sahara wear black only as a fashion statement? Photo: Wikipedia

The color black absorbs light and radiant energy. Again, seemingly and most definitely against common sense, if black absorbs heat, why the heck wear it? As usual, there’s more to this than meets the eye (or skin). The trick is to combine the black clothing with a light breeze. Stay with me. Without a breeze, your black T-shirt is a heat magnet and you’ll feel hotter for sure than when wearing white. A breeze however, whisks the heat away while keeping you cooler under your black T. Black is the new white. Who’d have guessed?

But wait — there’s more!

Clothing is key to moderating your temperature outside. But there are also other strategies. It’s no accident so many people around the world live near the coast. Commerce and travel are certainly main reasons for coastal populations, but it is indeed cooler at the coast — sometimes up to 20 degrees cooler. Gentle breezes near the coast help sweep the heat inland (aided in no small way by convective heating inland), while evaporative cooling keeps the thermometer lower than regions even as close as 15 or 20 miles inland. The coast can also be home to more clouds than inland locations which can help absorb and diffuse solar radiation.

What about what you put in your body? It’s 2012 so you know by now that drinking alcoholic beverages on a hot day leads to dehydration. Certainly not a desirable condition while enduring temperatures on the upper end of the comfort (and discomfort!) scale. Instead of a cold beer after cutting the grass, hydrate with plenty of water (save the beer for later). Just this past Tuesday the Thai government issued warnings about the approach of the extreme heat season. Among many other tips, they suggested herbal drinks to reduce the body’s heat, including bael, pandan, Asiatic pennywort, sappan, chrysanthemum, and “Tre-Pala” drink formula (a combination of three herbs: Myrabolan Wood, Beleric myrobalan and Indian gooseberry). You probably won’t find that list of ingredients in many places here in the States, but all your body really needs is water — and plenty of it. Even most casual or moderate physical activity doesn’t bring about the need to consume those popular sports and energy drinks that claim to replenish your body’s electrolytes. Water is the key to staying healthy in the extreme heat of summertime that for most of us is right around the corner but for some of us is already here (right, Andrew?).

There are more ways to beat the heat, of course. Limit your time outside and your exposure to the sun. Use sunscreen. Work at night. Get a good night’s sleep to help your body prepare for and then endure the stress of being outside in the heat. Relax and limit your exertion. Jump in a pool, lake or river (never dive into unknown waters). An old Russian remedy suggests putting sour cream on a sunburn. Maybe that’s putting the cart before the horse for this article, but file it away for future reference just the same.

Sweat - your own personal HVAC system. Enable it by drinking lots of water. Photo: Wikipedia

Lastly, we’ve been talking about evaporative cooling, both mechanical in the form of evaporative/swamp coolers as well as compressing/liquefying/evaporating ammonia, but let’s not forget sweating. This is your personal, biological air-conditioning system that cools your skin as your perspiration evaporates. If it’s a hot day and you’re exerting yourself outside and you notice you’re not sweating, you’re in serious trouble and likely on the way to dehydration, heat exhaustion and even heat stroke. Take immediate steps to hydrate yourself and to seek shelter from the heat. Seeking medical attention is likely a good idea, as well.

It’s April. I’m already counting the days to October (156, as of today).

Two of the nation’s foremost emergency authorities have joined forces to raise public awareness, which is a phrase that’s so overused these days that it’s almost an invitation to go look at something else.  But this time the awareness is about something that affects each and every one of us – severe weather.  See below for the full version of the official announcement.

Response at Your Weather Department to the campaign’s tagline – “know your risk, take action, and be a force of nature” – has been spirited and not everyone’s reaction has been positive.  What we do all genuinely agree on, however, is that it’s a great idea to keep the need to prepare for severe weather as a top-of-mind issue.  We don’t believe in alarmism and we’re not in the fear business.  But we do know that the more prepared and knowledgeable you are, the less afraid you are and the smarter your decisions are when they matter most.

ImpactWeather doesn’t benefit either directly or indirectly from the sale of weather radios or MREs but when it comes to severe weather, each and every one of us is dedicated to helping keep people as safe as possible.  Nothing beats an email or a call from a client who wants us to know how we helped them keep a bad situation from being much, much worse.  There aren’t too many other professions that offer this type of job satisfaction.

If you’re not prepared, start with a few simple ideas.  Commit to them and then start building your plan.

• You already own a bicycle helmet.  Keep it handy for when tornado warnings are issued.
• Never, ever, ever, ever, ever drive through high water on a roadway.
• Photograph everything in your home.

The idea of a Severe Weather Week is nothing new – many individual states have been doing it for years.  But this is the first national effort to get the public to take heed and pay a little more attention to both the options and the threats in order to save lives.  Maybe even your own.

FEMA, NOAA launche first National Severe Weather Preparedness Week April 22 – 28

As the nation marks the first anniversary of one of the largest tornado outbreaks in U.S. history, the National Oceanic and Atmospheric Administration and the Federal Emergency Management Agency are teaming up this week to save lives from severe weather.

The two agencies encourage the public to “know your risk, take action, and be a force of nature” by taking proactive preparedness measures and inspiring others to do the same.

Last April, tornadoes raked the central and southern United States, spawning more than 300 tornadoes and claiming hundreds of lives. That devastating, historic outbreak was only one of many weather-related tragedies in 2011, which now holds the record for the greatest number of multi-billion dollar weather disasters in the nation’s history.

The country has already experienced early and destructive tornado outbreaks in the Midwest and South this year over the last two months, including a significant number of tornadoes last weekend. May is the peak season for tornadoes, so it is important to take action now.

“The damaging tornadoes that struck this year, causing widespread devastation as well as loss of life, also spurred many amazing and heroic survival stories,” said NOAA Administrator Jane Lubchenco, Ph.D. “In every one of these stories, people heard the warning, understood a weather hazard was imminent and took immediate action. We can build a Weather-Ready Nation by empowering people with the information they need to take preparedness actions across the country.”

“One of the lessons we can take away from the recent tornado outbreaks is that severe weather can happen anytime, anywhere,” said FEMA Administrator Craig Fugate. “While we can’t control where or when it might hit, we can take steps in advance to prepare and that’s why we are asking people to pledge to prepare, and share with others so they will do the same.”

To “be a force of nature,” FEMA and NOAA encourage citizens to prepare for extreme weather by following these guidelines:

• Know your risk: The first step to becoming weather-ready is to understand the type of hazardous weather that can affect where you live and work, and how the weather could impact you and your family. Check the weather forecast regularly and sign up for alerts from your local emergency management officials. Severe weather comes in many forms and your shelter plan should include all types of local hazards.
• Take action: Pledge to develop an emergency plan based on your local weather hazards and practice how and where to take shelter. Create or refresh an emergency kit for needed food, supplies and medication. Post your plan where visitors can see it. Learn what you can do to strengthen your home or business against severe weather. Obtain a NOAA Weather Radio. Download FEMA’s mobile app so you can access important safety tips on what to do before and during severe weather. Understand the weather warning system and become a certified storm spotter through the National Weather Service.
• Be a force of nature: Once you have taken action, tell your family, friends, school staff and co-workers about how they can prepare. Share the resources and alert systems you discovered with your social media network. Studies show individuals need to receive messages a number of ways before acting – and you can be one of those sources. When you go to shelter during a warning, send a text, tweet or post a status update so your friends and family know. You might just save their lives, too. For more information on how you can participate, visit www.ready.gov/severeweather

Click to play.

As I’m starting to write this, I just realized that this year marks my 20^th anniversary of involvement in producing ImpactWeather’s Hurricane Seminar for Business and Industry.  Every year I say that this next one will be our best ever but trust me – it’s not like we set lower goals each year.  In fact, each year we’ve worked to make it even bolder and more comfortable, at nicer facilities with better food, more entertaining yet a genuinely productive use of your time . . . and always with top educational content the most important goal.

To say we have an impressive lineup this year is an understatement.   Simply put, this will be the most valuable gathering of business professionals in the entire U.S. who are concerned about the potential effects that a hurricane or tropical storm could have on their organizations . . . and exactly how they can better prepare for, manage and recover from such a threat.

This year it’s all about business case studies and lessons learned.  Go find out more and register.  We’ll see you May 23^rd.

For many years beginning in 1992, I rode the MS150 from Houston to Austin (‘150’ being a shinier way of concealing the fact that back then it was actually the MS178) and eventually I became part of the event management staff and, for six or seven years, the T-shirt designer.  Officially now known as the BPMS150 Houston to Austin, each year I’d also produce the rider maps and I even wrangled a sweet spot as manager the tour Expo, which is on the Friday night before the tour, so that I could not only help out planning the event but then actually ride the entire thing each year, too.

It’s been several years since I was involved at any level and most years, when April rolls around and the tour weekend looms, I miss being a part of it.  But thanks to this weekend’s regional weather forecast, this might not be one of those years.

For those riding in the event this year, here’s the . . . challenging regional weather outlook for the weekend courtesy of StormWatch Manager Fred Schmude:

“The [current] weather pattern is expected to take a dramatic turn by Friday as a strong upper-level storm system and cold front makes progress toward the area.   Yesterday it appeared this system would move out of the area by Saturday morning in time for the MS150; however, new forecast data indicates this system will likely come in stronger and unfortunately move out slower resulting in breezy and much cooler air for Saturday with a chance of light rain and heavier showers, mainly during the morning.

“The forecast calls for showers and thunderstorms to increase in coverage and intensity Friday afternoon and evening as the storm system moves by the area. Be advised that some of these storms could be strong with gusty winds, small hail and lightning.   Breezy and much cooler air is expected for Saturday morning with a chance of lingering light rain and heavier showers.   Decreasing clouds and breezy conditions Saturday afternoon will be followed by mostly sunny and milder weather on Sunday with slightly lower northerly winds.   Temperatures on Saturday morning are forecast to fall into the mid to upper 50s across the area and may struggle to make 70 degrees during the day depending on how much cloud cover lingers over the region.  Temperatures by Sunday morning are forecast to fall into the upper 40s to lower 50s and rebound back into the lower to mid 70s during the day.   Low-level winds behind the cold front on Saturday morning (including La Grange) and afternoon are forecast to average out of the NW at 12-17 gusting 25 mph, decreasing NNW-N at 10-15 gusting 20 mph for Saturday night into Sunday.

“Please note there’s still some uncertainty on the exact timing of this weather system and we could even see areas of light rain and heavier showers linger into Saturday afternoon over the Houston and La Grange areas.   For now it appears most of the rain will move out of the area Saturday morning  with the main concern for the MS150 being a gusty NW headwind from Houston to La Grange all day Saturday as low pressure strengthens over the Lower Mississippi Valley.”

I’ll never forget one year forever ago (in the mid ‘90’s) when two friends rode the tour with me – two guys who’d never ridden it before.  After the first 103 miles on Day 1, we were enjoying the huge, delicious meal provided by MS Society and volunteers on a ridge overlooking the valley floor at the overnight campsite in La Grange.  That’s when we saw it.  A front.  A big, nasty front that announced its presence by bending trees to its will as it approached.  That night, as our tent walls rocked against our feet, heads and sides, I literally had a dream about scaling Everest.  And the next day, heading NW towards Austin – very much into the wind – was . . . challenging.

Had I signed up to ride this year, knowing what I know now about this weekend’s weather would I still make the ride?  In a heartbeat.  Of all the charities I’ve ever been involved with, the MS Society is by far the most efficiently run, economically driven fundraising machine and because of that, the tangible progress in treatment over the last ten years of the different types of MS has been astonishing.

A hearty salute to all the riders, volunteers and organizers this weekend and especially to BP, longtime sponsor of the largest bike tour in the world.  Go and ride this one.  It won’t be that much more difficult than usual.  But you might remember it for a much longer time.

Regular readers of YourWeatherBlog are aware of the severe weather event beginning to take shape in the Plains. If you’re just tuning in, read the two previous severe weather entries.

Today’s post is not to bring you up to speed on these meteorological events from the beginning but rather to update the warning about the potentially deadly weather situation beginning to form across the infamous Tornado Alley over the coming 72 hours.

The StormWatch-identified area most at risk for severe thunderstorms and potentially numerous strong and long-track tornadoes. Valid April 13-15. In the course of the typical year, it's not often we identify a high risk of such severe weather. Image: ImpactWeather StormWatch

As of now there are no watches or warnings from the National Weather Service in effect for any regions in the Plains. However, they’re looking at the same situation that our ImpactWeather StormWatch team is looking at and since they expect much of the activity to begin later this afternoon and tonight, their bulletins are likely not far off. StormWatch has continued to refine the areas most at risk this weekend and the confidence level in this significant weather event remains high. See graphic at left.

Whether the weather situation is a hurricane, an ice storm, a tornado outbreak or a heat wave, our advice remains the same: Active preparation, no matter the forecast. As the event draws near it is imperative to stay informed by your weather information source of choice. Be aware of the advisories in place and have your emergency plan ready. As for the potential tornado outbreak in the coming hours, it’s probably too late to prepare an emergency kit and it’s too late to practice your emergency procedures. It’s not too late, however, to brief your family on the weather situation, what to do and where to go, and who to call if it all goes wrong.  NOAA has a full list of tornado safety tips here. A quick internet search will yield numerous sites devoted to tornado safety, such as TorndaoProject and Ready.gov.

As the event begins to unfold, it remains imperative to monitor the weather situation. An eye on the sky and an ear to the radio are good places to start. Smart phones can bring you the latest radar images and automated alerts from your favorite TV stations and other sources. If time allows, check in with your family who, like most Americans, may be scattered across the county in school, at work or on the road. Make sure they are aware of the situation and that they know the family emergency plan may need to be activated. Be aware that severe weather often takes cell towers offline and that cell phones should not be your first or only means of communication.

Lastly, when the weather situation is over it’s time to assess damages and injuries (if any) while establishing contact with those unable to reach your safe place. Continue listening to your sources of weather information as additional severe weather may be threatening. When the dust settles and time allows, it’s time to reassess your emergency procedures to ensure that what worked is reinforced and that what didn’t is refined so that it works properly if/when there is a next time.

The 23rd Annual Hurricane Seminar for Business and Industry is on Wednesday, May 23rd at the Houston Hobby Airport Hilton. Click for more information and to register.

In Tuesday’s YourWeatherBlog, I wrote that a significant severe weather threat is beginning to take shape for the southern and central Plains this coming weekend and early next week. With this update, I’m confirming that the severe weather is still on track and still on target.

The I-35 Corridor is where the severe weather is expected initially. The area will then move eastward. The area indicated in red is valid April 13-15. Image: ImpactWeather StormWatch

Every weather event comes more into focus as the time to the actual event draws closer. Tuesday was a first-look/heads-up sort of notice but there were still many uncertainties. So far away from the expected arrival of the severe weather, questions such as timing, location and severity were very much at the top of our concerns. 48 hours have now passed and though those same questions of timing, location and severity remain, the event as a whole is becoming more focused. Of note, there aren’t many differences between what we see today, and what we saw on Tuesday.

As the system moves east, widespread heavy rainfall will result in 2-3 inches of rain across eastern Texas and Arkansas by next Wednesday. Multi-day totals of training storms will likely exceed that amount significantly.

We continue to identify this as a significant outbreak of severe weather across the Plains for the “late weekend / early next week” time frame. However, increased focus suggests the event may now be a Saturday evening event, as well as on Sunday and Monday as the line of severe weather moves eastward. We’re also identifying the I-35 corridor from Oklahoma City to Tulsa to Wichita to Kansas City as particularly at risk, perhaps as early as Saturday afternoon. We’re also indicating the possibility of long-track tornadoes.

Why does the severe weather wait until the Plains to develop? This type of weather will feed upon the warm, unstable air that’s been trucked up the I-35 corridor since yesterday. This wind flow, at times quite breezy, is already evident in the form of showers across eastern and central Texas this morning, as well as farther north into Nebraska and even South Dakota.  Additionally, as the next cool air mass rushes over the Rocky Mountains and descends into the Plains, it drys and warms adiabatically adding to the instability of the region. For this part of the United States, this severe weather scenario is not unique. In fact, it’s been named Tornado Alley for this very reason.

North Texas was on the receiving end of severe weather yesterday afternoon. Reports of two to four feet of hail, plus heavy and fast rainfall turned normally cry creek beds and runoffs into raging torrents. Click image for YouTube video. Video: KVII ProNews7

Heat, humidity, a strong southerly flow in the lower atmosphere, and a soon-to-be strong southwesterly flow in the upper atmosphere are early indicators of the significant severe weather to come. This is definitely time to stay aware of the severe weather watches and warnings in your area that are sure to be posted as we head into the weekend and early next week.

Iceland’s Katla Volcano is, once again, displaying signs of an imminent eruption. Are volcanologists crying wolf? It’s impossible to say, but given the current situation — and with so much at risk — how could they not?

By my count, this is my fifth YourWeatherBlog piece about the Katla volcano since the summer of 2010 (read previous entries here, here, here and — oh yes — here ). Remember, it was April of 2010 when Katla’s neighbor Eyjafjallajökull erupted and brought trans-Atlantic and western European air traffic to a near standstill. The underlying thought was (and is), If Eyjafjallajökull could do that (shut down air traffic), imagine what the larger Katla could do!

The Katla volcano is partially covered by the Mýrdalsjökull glacier. Photo: Wikipedia

And it is larger. By some estimates much larger. Experts cite the last major eruption of Katla in 1918 as being five times larger than 2010′s Eyjafjallajökull which threw volcanic ash miles into the atmosphere and grounded vast amounts of air traffic for six days. Might a major Katla eruption ground air traffic for a longer period and might the ash cloud spread much farther from Iceland? Most experts agree yes and yes. Those experts include ImpactWeather’s in-house geologist Fred Schmude who comments that the next Katla eruption will likely be a VEI (Volcanic Explosivity Index) 5, Plinian-type eruption as compared to the 1918 Katla eruption which was classified as a VEI 4 or perhaps a VEI 5. Eyjafjallajökull’s 2010 eruption was classified as VEI 4.

What does history tell us? It’s not good. Katla, since 930, has erupted 16 times at intervals of 13-95 years. It’s been 94 years since the VEI4/5 eruption of 1918. Presently, this is one of the longest periods of dormancy in its history. One way or another, it seems Katla is about to go into the record books.

The chambers of Katla and its neighbor, Eyjafjallajökull. Image: Wikipedia

What’s the latest? Based on precise GPS measurements, the surface of the volcano is moving erratically. This is an indication that magma is not only pooling in the caldera, but that magma is rising to the surface — both signs that an eruption is imminent. If you’ve browsed the previous Katla postings from YourWeatherBlog, you know another sign of a potentially imminent eruption is an increasingly high frequency of earthquake activity and that, too, is accompanying the rising magma. Interestingly, Katla’s chambers are interconnected to neighboring volcanoes and seismic activity not directly under Katla can sometimes be misdiagnosed as a precursor to a Katla eruption when, in fact, it’s the under-Katla eruptions that must be monitored. I don’t mean to downplay the role of neighboring earthquakes — they are certainly key to the overall instability of the region. However, only two of the under-Katla earthquakes have been recorded in the last 48 hours. “Significant,” says Fred, “but not overly alarming.” At least not yet.

What’s the take-away? Active preparation, no matter the forecast. That’s exactly what I wrote yesterday in an article for YourWeatherBlog concerning the potential for a significant outbreak of severe weather here in the States this weekend and/or early next week. One can’t reroute or delay a hurricane, an ice storm, a tornado or even a volcano. These things happen when they happen. We can, however, be as prepared as possible. Icelandic residents have seen this over and over: Iceland sits at the northern extent of the Mid-Atlantic Ridge which is the tectonic plate boundary of the Eurasian and North American Plates; the visible representation of this ridge is Reykjanes Ridge which dominates Iceland’s landscape. Geology 101 tells us that where plates collide, earthquakes, volcanoes and mountain ranges have a way of popping up on a more or less geologically frequent schedule. I’m very curious to know what steps the residents of Iceland and, more specifically, the residents of Vik have taken to prepare for the imminent eruption. Have they made significant preparations? Or are they like most Americans, even those in so-called risky areas, who haven’t even made basic preparations?

The unanswered eruption question remains: When? (When, not if.)

I’ll keep you posted.

The ImpactWeather StormWatch team has identified a significant threat of severe weather beginning late this weekend and into early next week. Keyword: Significant.

This, on the heels of last week’s webinar on the spring severe weather outlook which included our forecast of a record-breaking year of severe weather. Read last week’s YourWeatherBlog entry here, which includes a link to the recorded webinar.

April is typically ripe with severe weather. Nearly every frontal system plowing across the Plains or the South is capable of producing a severe thunderstorm. And because it’s April the last of the winter storm systems can kick up their heels in a fantastic way as the beginning of the summer pattern seeds the eastern half of the country with warm, humid and unstable air. Combine these ingredients with a brisk stir to yield severe thunderstorms.

The jet stream on April 3, 1974 was a significant contributing factor to the Super Outbreak of tornadoes. Image: Wikipedia

However not all severe thunderstorms are created equal. Last week’s severe thunderstorms in Dallas had all the ingredients on hand to produce tremendous storms and tornadoes, but as the system moved east the ingredients lost some of their punch and the storms became less frequent and less severe. More often than not, last week’s type of mega-storms are the exception rather than the rule as it takes many ingredients to align in an exact way to produce such violence.

Indications are good that next week's surface analysis will look very similar to this analysis from April 3, 1974. Image: Wikipedia

It looks like next week all the ingredients will be in exactly the right place. So impressive is the initial data, that we’re seeing similarities to the April 3rd, 1974 Super Outbreak that produced the second largest tornado outbreak within a 24-hour period in the U.S. (the largest 24-hour outbreak is last year’s April 25-28 outbreak which produced 208 tornadoes on April 27).

Meteorologists, students of meteorology and even serious hobbyists know that severe weather is about much more than just a cold air mass slamming into a warm air mass. Severe weather is as much about what’s happening in the upper atmosphere as what’s happening on the surface. Key upper ingredients include a massive upper-level trough of low pressure. These troughs will often be reflected on pressure charts above 30,000 feet. Also needed, cold air aloft. In elementary school we learned that warm air rises, but if that warm air is suddenly surrounded by cold air it will rise faster, sometimes explosively so. Finally, our short lesson of severe weather criteria includes one more main ingredient: strong upper-level winds. These winds act like an exhaust fan at the top of a hot stove, helping air already moving up to continue moving up and even accelerate.

Valid early Monday morning, April 16 this mid-altitude chart shows a mature low pressure trough over the Rockies with the most active and strongest section of the jet stream over the Plains. Image: WSI

What’s the big deal about air moving up? After all, it’s the air moving downward that causes all the damage on the ground and even helps initiate a tornado. Upward-moving air cools and condenses as it rises. This action forms clouds and eventually precipitation. Fast-moving air takes that scenario ever higher into the atmosphere where the conditions between warm/cold and moist/dry become even more extreme. With these conditions, what would otherwise be an ordinary thunderstorm crosses over into the realm of severe.

Next week begins with all of these ingredients in place. Early on Sunday a large upper-level trough moves across the desert Southwest and Great Basin of the United States. This trough reflects downward to a strong surface cold front moving into the Plains. Already in the Plains: an unstable air mass that begins to take shape tomorrow with a pronounced southerly wind from the Gulf of Mexico and Texas. Five days of that kind of wind is like filling an Olympic-sized swimming pool with gasoline, then just waiting for a spark. That spark arrives with the cold front and then continues to fire as the upper-level trough swings through during the following couple of days.

By this coming Saturday, the strong cold front is oriented from the western Great Lakes to western Texas and northern Mexico. North Texas, Oklahoma and Missouri may experience severe weather as this cold front moves through the region. How similar is this panel to the one from April 3, 1974? Image: ImpactWeather StormWatch

Where exactly will the outbreak be? Too early to say as our confidence in a forecast more than five days out is low. However, the central Plains, even the northern regions of the southern Plains, seem most at risk initially. As the system moves east, the threat should move east with it.

ImpactWeather stresses active preparation with respect to severe weather. Hurricanes, ice storms and tornadoes all produce threats to life, business and property but waiting until the tornado is on the ground or the ice storm has robbed you of power or the storm surge is lapping at your door step is, by then, too late. Active preparation means preparing now for a storm that may not come tomorrow or may not come next week or even next month, but for the storm that looms — eventually and inevitably — on the horizon for almost every person and business in the United States and so many other countries around the world. Many of you are already prepared, no matter what the weather forecast indicates. For the rest of you, now is the time.