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.

A couple of articles caught my eye over the past few days. The first was posted last Thursday, “New Icelandic Volcano Eruption Could Have Global Impact.” The second followed almost immediately on Friday, “Katla Volcano Eruption Fears Played Down by Icelandic Scientists and Tourism Officials.”

You see where I’m going, right? A potentially imminent, global impact-type of volcanic eruption in Iceland is being downplayed by Icelandic scientists and tourism officials. Who do you believe? Who wants your money? Who stands the most to gain (or lose)? Who is right? What do you do?

The Katla volcano erupting in 1918. Photo: Iceland Volcano and Earthquake Blog

Who do you believe? Indeed. On the one hand, scientists are saying (and have been saying) that a huge, likely catastrophic eruption is imminent. YourWeatherBlog has written here and here about the volatility of the Katla situation. On the other hand, the experts in-country are saying it’s no big deal. Are you a person of science or are you a chance-taker? I don’t think anybody is denying the potential for a major eruption. Most agree a major eruption is coming and many experts claim it’s well overdue. But what does that mean? The argument may come from the definition of imminent and what that definition means to different people. For example, what exactly is imminent in geological terms (years, decades, centuries?)? If you’re a person of science or one with faith in science you’re not likely in the midst of planning a trip to Iceland. Gamblers, however, know that the house doesn’t win every hand.

Who wants your money? The root of all evil is perhaps not money per se, but the lengths to which some people will go to separate you from your money. In fact, because we’re dealing with Iceland I’m reminded of the report, Financial Stability in Iceland, that — in 2006, just before the global financial crisis — lauded the rock-solid stability of the Icelandic financial system. It was later revealed that Frederic Mishkin was paid a consulting fee of nearly $134,000 by the Icelandic Chamber of Commerce to author the report. Was the report fair and unbiased? It certainly has all the trappings of a one-sided report posing as truthful and — on the surface — unbiased. What about now? Might you raise an eyebrow knowing that tourist officials from Iceland are downplaying the potential of a catastrophic eruption in Iceland? Wouldn’t it make sense for them to lure you (and your money) to Iceland. Really, now more than ever, how could they not?

Who stands the most to gain (or lose)? As always, a subjective question but one with compelling arguments on either side. On the one hand, if you go to Iceland and there’s an eruption, you may die. There will be an eruption, but as Dirty Harry snarled, “Do you feel lucky, punk?” Yet even the experts aren’t sure when the eruption will occur. Many tourists will visit Iceland and nearly all of them will return unscathed. Tourism officials have no choice but to downplay the risk or their country may not host another tourist until the volcano eventually blows and they can put all this nonsense behind them.

Is that .45 Magnum filled with lava and toxic gas? It might as well be, but when will Katla pull the trigger? Photo: WarnerBros

Who’s right? If Katla erupts tomorrow, the geologists are right. If it erupts next year, are they wrong? And what about the tourism officials? They are right until the very moment Katla (or any other Icelandic volcano) erupts.

What do you do? Decisions, decisions. Once again, do you feel lucky? If you don’t feel lucky, stay home — but you might stay home for a few years — or more. Feeling lucky? Then by all means, pack your bags and visit Iceland. You’re betting that you can win a few hands before the house cleans up. Before you go: Buy travel insurance. Since Katla hasn’t erupted, insurance bought now should pay off for any volcano- or ash-related incidents like flight delays and additional nights in hotels. Read the fine print on your airfare. Though most airlines will rebook you or refund your ticket, make sure you know the details before you purchase as many travelers have yet to resolve their issues from the 2010 Eyjafjallajokull eruption, and some insurers are still debating if they should cover stranded passengers. You have medical insurance, right? Want to return to the U.S. immediately if you’re injured? Make sure your insurance covers an air ambulance.

What about me? I tend to side with the geologists. And since I haven’t been planning a vacation to Iceland I’m okay sitting on the sidelines and waiting it out. Someday however, I would indeed like to visit Iceland.

The entire point of ever-improving scientific prognosis is to minimize exposure and risk. Still, if you’re going to go storm chasing you better be prepared to run into a storm (hail video). If you’re going to the coast to see a great hurricane, you better be ready to get wet (Geraldo Rivera). And if you’re going to go to a place on the verge of a major, potentially catastrophic volcanic eruption, you better be prepared for the worst (eruption video).

Just a few hours ago (0948 UTC), 13 stories worth of Delta II rocket lifted [video] the newest weather research satellite into polar orbit on a mission to provide the beginnings of the next generation of Earth observing and monitoring from space.

Artists' conception of NPP orbiting 512 miles above Earth. Image: NASA

This new NPP (NPOESS Preparatory Project) satellite combines weather monitoring and climate observing in the same platform. It’s also a crucial step in building the next generation weather system. From its monitoring station 512 miles above Earth, the new satellite will be able to observe everything from the ozone layer to land cover, from atmospheric temperatures to ice cover and even vegetative productivity. All told, there will be more than 30 variables observed and measured. The five instruments aboard the satellite are the Advanced Technology Microwave Sounder (ATMS), the Cross-track Infrared Sounder (CrIS), the Clouds and the Earth’s Radiant Energy System (CERES), the Visible Infrared Imager Radiometer Suite (VIIRS) and the Ozone Mapping and Profiler Suite (OMPS). NPOESS will have the ability to send 800 DVDs’ worth (about 4 terabytes) of data home each day. It’s service life is expected to continue through 2016 though as we’ve seen with many previous Earth science satellites, it may very well continue beyond that time frame.

Almost flight ready: The NPP in January of this year. Click to enlarge. Photo: NASA

James Gleason, NPP project scientist said, “NPP is a continuation of existing Earth Orbiting Satellites. For monitoring purposes, you need to have continuous observations. NPP continues the data record started by NASA satellites and improves on the instruments that are used for numerical weather forecasting.”

Delivering even more bang for the buck, today’s launch included six CubeSats — tiny satellites measuring just 4 or so inches (10 centimeters) across. The CubeSats were designed by students from several different universities and flew as part of NASA’s Educational Launch of Nanosatellites program.

Delta Dawn: This morning's early launch in total darkness made for some spectacular video, but this daytime shot of a Delta II lifting off the launch pad with the Dawn spacecraft* payload at Cape Canaveral, FL shows the D-II at its finest. Click to enlarge. Photo: NASA

Despite being nearly scrubbed in favor of the Space Shuttle program, the Delta II rocket persevered and has been instrumental in its 20+ year history. Now, with the end of the Shuttle program, the Delta II rocket has become the rising star in NASA’s space program for the near future. The first Delta II launched in 1989; to date there have been 146 launches and they’re considered the world’s most reliable launch vehicles currently in service. This morning’s ride on the Delta II of the first of the next generation of weather satellites was preceded by the Mars Lander in 2007, the Mars Rovers in 2003, and the Mars Climate Orbiter in 1998 among many others.

It was 54 years ago this month (October 4, 1954) when Russia launched the first artificial satellite into Earth orbit.

* Dawn spacecraft (as mentioned in Delta II photo at left).

[Video: Manifest integration of all five components.]

I’ve been working on a “change of seasons” post for YourWeatherBlog which will be completed and posted tomorrow. For now, I wanted to post a quickie on today’s temperatures because unless you’re living in Minnesota, you might not be aware of how cold it is there. It’s cold!

This ImpactWeather iMap graphic shows temperatures in the 90s across the Gulf Coast and temperatures in the low 50s along the Canadian border. Counties of northern Wisconsin and Michigan (highlighted in green) are now under NWS freeze and frost advisories for tomorrow morning. Image: ImpactWeather iMap

Did you know Minnesota’s International Falls was in the teens this morning? 19.9F was officially recorded at the INL airport just before 7 AM CDT. Temperatures throughout the region were below freezing and more (though not as many) freeze and frost advisories are in effect for tomorrow morning. This morning’s low of 19, by the way, is the lowest September temperature ever recorded for International Falls. A bit further to the south, Duluth recorded snowfall yesterday — another record for the earliest snowfall ever recorded in Duluth.

If you’re up north and are concerned that winter has arrived way too early, not to worry. This is the time of year for rebounds and, true to form, afternoons will once again be in the 70s by Saturday.

Yesterday's StormWatch Today video presented by ImpactWeather meteorologist Lauren Whisenhunt indicated the potential for record-breaking temperatures across the Upper Mississippi River Valley. Image: ImpactWeather

Does it already seem like Tropical Storm Don was years ago? Last week’s storm sure generated lots of excitement for coastal (and even inland) residents of Texas as the prospect of drought relief seemed so close. The storm also generated excitement — and not the good kind — for its evaporation at landfall — it almost disappeared as it reached the coast. So close, yet so far.

And now Tropical Storm Emily has been dismissed out to sea, staying just far enough east of Florida. Probably a good thing, that. Most of the Florida peninsula is caught up in the drought plaguing the southern U.S., but their drought is practically a pool party compared to other areas. Unlike Texas, I don’t think peninsula residents are begging for a soaking at the hands of a tropical storm or hurricane.

Is it any wonder Texas residents are begging for a tropical storm? All images are clickable for a larger size. Image: U.S. Drought Monitor/NOAA

What’s next? Already Disturbance 24 has been identified and though its chances for development over the next couple of days are slim, we don’t expect it to fade away into nothing — at least, not yet. We’re also keeping an eye on the western coast of Africa. At the moment, a swirl of clouds can be spotted and this area is infamous for hatching disturbances into the warm tropical waters of the Atlantic.

This sky-eye view of the entire Atlantic Basin reveals things aren't quite as quiet as you may think. Image: ImpactWeather

And let’s not forget the eastern Pacific. Two storms there, Hurricane Eugene and Disturbance 18E, are not expected to strike any land areas but it certainly goes to show an active eastern Pacific. In fact, we may find 18E upgraded to depression status later today as further strengthening is likely.

Neither Eugene or 18E are expected to impact any land areas. Image: ImpactWeather

Though it seems quiet, the ImpactWeather TropicsWatch team is keeping a watchful eye on four active disturbances and one suspect area on Africa’s West Coast. Additionally, areas like the eastern Caribbean, the western Tropical Atlantic and the Gulf of Mexico are climatological hot spots for development, while the peak of hurricane season draws closer every day — still more than a month away.

Historical storm formation points for the first ten days of August. Image: NHC/NOAA

Check out this video from ImpactWeather’s Chris Hebert talking about how the perceived lack of hurricane activity is actually right inline with our active season forecast.

Plenty of daily, and seasonal snow and cold records have been set the past few days but as the Northeast and Midwest catch a short break today under sunny (but cold!) high pressure, it’s now coastal Texas that will deal with wintry precipitation. In fact, flurries (northern Metro Houston) and sleet (coastal areas near Galveston) have already been reported this morning. This afternoon though is when the precipitation should begin in earnest with accumulations in some areas nearing five inches of snow by tomorrow morning and other areas accumulating 1/4-inch of ice or perhaps even more.

The ImpactWeather StormWatch video is now online and you can view it here, or for all of our videos you can skate over to the ImpactWeather YouTube channel.

Image: ImpactWeather StormWatch. Image: ImpactWeather StormWatch.Today. Strong high pressure allows sunshine, but with frigid temperatures in places like Tulsa, Des Moines and Indianapolis (highs in the mid-teens), Pittsburgh and Newark (highs in the 20s). Image: ImpactWeather StormWatch.

Tomorrow. Accumulating snow from coastal Texas to Kentucky; thunderstorms are likely in many Gulf Coast locations. Image: ImpactWeather StormWatch.

Saturday. As the prolonged cold in the South begins to wane, focus turns to the Northern Plains and Great Lakes as the next winter storm brings more snow and cold to the region. Additionally, broadsnow returns to the Northeast. Image: ImpactWeather StormWatch.

Sunday. The Great Lakes along with the central and northern Plains accumulate more snow. Image: ImpactWeather StormWatch.

Monday. Warmer winds from the Atlantic allow a brief warming from the Northeast before even more snow arrives on Tuesday. Strong winds and heavy snow create blizzard conditions for the Upper Mississippi River Valley and Midwest while another surge of cold air reaches the Gulf Coast. Image: ImpactWeather StormWatch.

Rolling blackouts are what we awoke to this morning in Houston. The outdoor thermometer read 26° and the power companies are struggling to keep pace with demand. The house was still warm and it certainly wasn’t the end of the world — this New England Yankee can handle some cold! But my cats seemed to know something was different (lots of pacing and meowing)…and it was. Southeast Texas hasn’t been this cold in quite some time. But perhaps even more unusual is the coming 60-72 hours: only briefly will this part of Texas be above freezing through Saturday. We’ve had freezing temperatures before of course, but this type of prolonged cold is quite unusual. Add the snow and sleet expected to begin later tomorrow and this will be the beginning of many “I remember the February snow of 2011″ stories. And by the way, not just Houstonians will be telling those stories — this Arctic outbreak is reaching across two-thirds of the country.

The latest graphics from ImpactWeather’s StormWatch team are posted below and don’t forget to watch our latest video with ImpactWeather’s Chris Hebert.

Image: ImpactWeather StormWatch.

Image: ImpactWeather StormWatch.

Image: ImpactWeather StormWatch.

Image: ImpactWeather StormWatch.

It’s all coming together in dramatic fashion today as record snowfall threatens not only such places as Chicago (where they’re accustomed to heavy snowfall), but places like Houston and perhaps even Corpus Christi where measurable snowfall is a rarity. Accompanying the snow are strong winds and frigid temperatures where in the South especially, temperatures will not just dip low, they’ll dip low and stay there for several days. Wind chill readings of -20 and colder will be common across the Plains today. Over the next several days, three low pressure systems will combine to bring serious winter from the Plains, to the Gulf Coast, to the Mid-Atlantic to New England.

Our ImpactWeather StormWatch video is now online and, on the subject,  just a reminder that we’ll be hosting a free 20-minute webinar next Tuesday the 8^th, our last Winter Weather Outlook Update.  This will be a quick but thorough look at what we expect the remainder of the 2010-2011 winter season to bring.  Get more information and register here. And another reminder: you can read (or re-read) our winter weather safety tips here.

Onto the weather! The phrase, “a picture is worth a thousand words” comes to mind so let’s take a look at today’s StormWatch graphics “pictures”:

Though there will likely be some sun across the South tomorrow, mid- and high-level clouds will move in later and, combined with cold northerly wind prevent any significant warming for most areas during the second half of the week. Image: ImpactWeather StormWatch.

The snow expected from Texas to Pennsylvania depicted here will arrive courtesy of a low pressure area taking shape in Mexico tomorrow then move into the Gulf of Mexico Thursday. Image: ImpactWeather StormWatch.

Today's low is moving across the Middle Mississippi River Valley on its way to New England by tomorrow evening. Image: ImpactWeather StormWatch.

Midday Tuesday: High pressure over the Northern Plains pumps frigid air southward, all the way to Mexico. The packed yellow lines (isobars) between the low over eastern Arkansas and the high over western Nebraska indicate very strong winds of 30-35mph with higher gusts. Blizzard conditions and numbing wind chills are the result. Image: ImpactWeather StormWatch.

Midday Wednesday. The low pressure center is making rapid progress northeastward with heavy snow pushing into New England. "Phase Two" is taking shape in Mexico - the next low pressure center that will continue to draw cold air southward while tapping warm, moist Gulf of Mexico air over the next few days. This is the perfect scenario for South Texas and Coastal Texas snow. Image: ImpactWeather StormWatch.

Midday Thursday. Mid- and high-level clouds return to many southern areas by Thursday, keeping the sun at bay while cold air (and some snow) continues to dominate. Image: ImpactWeather StormWatch.

Midday Friday. Yet another low pressure area moves onto the StormWatch map, this time sweeping across the Canadian border. More snow, more wind, more cold. Regarding the low in the Gulf, confidence is growing in a significant snow event for Coastal Texas. Image: ImpactWeather StormWatch.

Midday Saturday. The Gulf low quickly moves to the Mid-Atlantic coastal region (taking on nor'easter characteristics) and pumps abundant Atlantic moisture into the the Northeast where it combines with the Canadian low over the Great Lakes. Significant snowfall is expected for many areas that have thus far been too far west of the tracks of the previous nor'easter storm systems. Places like Upstate New York, Vermont and northern New Hampshire should finally get their due. Additionally, the usual snow belts of the Great Lakes' lake-effect system should expect significant snow. Image: ImpactWeather StormWatch.

When does winter begin? On the calendar it’s December 21 but it has many unofficial start times: the first freeze, the first snow, when it gets dark so early in the evening, the first “snow day,” the first day to wear the winter jacket, the first day to use the heater in the car. This winter of 2010-2011 has had many different start times to many different people and many different regions of the country. I think it’s safe to say that, by now, winter has truly begun. However, like an engine spinning up its turbo for additional horsepower this winter is about to really begin for many outside traditional northern snow and cold regions of the U.S.

At the morning MetCon (meteorological conference) nine of ImpactWeather's managers and supervisors discuss the developing winter storm situation. Not only are the technical details of the storm itself evaluated, but also what it means to the businesses who are ImpactWeather clients. Photo: Fred Rogers, ImpactWeather.

Snow, ice, wind, cold, prolonged cold. It’s all in the near future for many areas not used to seeing such weather extremes. Brownsville, Texas — one of the southernmost places in the U.S. — will likely see freezing temperatures later this week. For the Gulf Coast of Texas and Louisiana, a freeze is not a regular occurrence but it’s not infrequent, either. What is infrequent is a prolonged freeze that lasts more than just a couple of hours around sunrise. And that looks likely this week. Also infrequent is Gulf Coast snow and that, too, is likely (or, at least possible) this week. And as the cold, Arctic air undercuts the warm, humid air now in place over much of the South (73F expected in Houston today) a broad area of ice and freezing rain is expected. Then as the warm air is gradually displaced by the colder air, the ice threat will diminish and the snow threat will increase.

Key for southern areas such as the Rio Grande Valley and Gulf Coast of Texas will be the prolonged cold and extended periods of at- or below-freezing temperatures. It’s been many, many years since this sort of extended cold has pushed so far south. Strong winds and wind chill will exacerbate an already cold situation. Preparation, as with any severe weather situation, should begin now.

We’ll continue to blog about this winter storm and prolonged cold event each day this week. In addition, you can visit the ImpactWeather YouTube channel for all our latest videos. Today’s video, produced by ImpactWeather’s Chris Hebert, is now ready for viewing.

If you listen, you can hear the whine of the turbine blades now.

Not only will this be an impressive winter storm for the Central Plains through Wednesday, but it looks likely these conditions will extend much farther south by the end of the week.

Valid for western areas through Wednesday; northeastern areas through Thursday. Table: ImpactWeather StormWatch.

Image: ImpactWeather StormWatch.

Without preparation, this coming winter storm could wreak havok amongst homeownsers, travelers and businesses. Calvin and Hobbes strip from GoComics.com.

There are still lots of questions about what will happen when next week’s Arctic air mass pushes south across the Plains (when, how cold, where). And because substantial overrunning of warm, humid Gulf air is expected, additional questions muddy the situation (rain, snow, freezing rain, when, where).

As warm, moist, less dense air collides with cold, dry, more dense air, it is forced aloft where it condenses into clouds and then precipitation. The vertical temperature structure within this region will determine the type of precipitation: liquid, freezing, frozen or a mixture. Image: Wikipedia.

ImpactWeather’s Chris Hebert attempts to remove at least some of the question marks with today’s StormWatch “Arctic Outbreak” video.