Dan's Wild Wild Science Journal

Devin Bowling took this shot (in Albertville, Al.) of a wall cloud (upper left). A tail cloud is the center, pointing toward the rain. Tail clouds are often mistaken for tornadoes.

As forecasters expected, violent storms tracked across Alabama and Tennessee on Tuesday. Tornadoes then hit South Carolina in the early morning hours of Wednesday. I was on air for nearly 8 hours straight. My voice is yet to recover.

Wall clouds are the parent clouds of a tornado. Not every wall cloud will produce a twister but if you see one, go the other way. Fast. Better yet, get under something sturdy. DO NOT head for a nearby overpass. Winds are accelerated under them and taking shelter under one can be a deadly mistake.

On the Great Lakes, it was the second strongest storm on record. Winds gusted to 80 mph. The waves on Lake Superior reached 9 meters!! (For the metrically challenged that’s over 26 feet!!)

The pressure at the center of the storm dropped to 955.2 millibars. That’s the lowest pressure ever recorded in Minnesota. Only the storm of January 1978 was stronger.

The 1978 storm is referred to as the great Ohio Blizzard. The pressure dropped to an incredible 950 millibars in that storm. Almost everyone older than 35 in Ohio can tell you stories of that event.

The Great Lakes Storm on Tuesday. It passed over Duluth and now holds the record for the lowest pressure ever recorded in Minnesota. Image courtesy NWS Duluth.

The storm in 5th place is rather famous. On November 10, 1975, (thirty-five years ago next month) a surprise storm produced a low pressure of 980 millibars. That storm hit Lake Superior hard and resulted in the sinking of an iron ore carrier called the Edmund Fitzgerald.

Canadian Gordon Lightfoot made the gale famous by his song about the doomed freighter. One line in particular has stayed with me.

“Does anyone know where the love of God goes, when the waves turn the minutes to hours.”

Update Oct. 29,2010: It now appears that the Minnesota storm missed the the non tropical storm record for the mainland U.S. by 0.01 inches of mercury!

Numerical weather prediction model forecast valid at 8 PM U.S. East Coast time Tuesday. This storm will spread tornadoes across the U.S. Midwest and near hurricane force winds on the Great Lakes.

When most folks think of tornadoes they imagine a warm spring afternoon suddenly turning stormy. More often than not this is true but there are glaring exceptions. Last night was one and Tuesday will be another.

A powerful storm system has been winding up  in the Plains. Last night a band of storms from Texas to Alabama brought tornadoes and large hail. Here in North Alabama, I was up for much of the night watching radar.

Winds going toward the radar right next to winds going away from the radar. This is what a tornado looks like on a Doppler radar. Image from Penn. State NEXRAD Archive. Click for larger version.

Large super-cell tornadoes are the easiest to spot and we had only one of those up in Tennessee. The ones you have to really watch for are the smaller more short lived twisters that are embedded in a squall line.

Around 4 AM CDT Monday morning, the Doppler radars indicated a strong circulation in the line over NE Alabama. The little town of Ider, near Fort Payne, was struck with a twister around 4:15.

The tornado looks to be an EF-1 or perhaps briefly an EF-2. An EF-1 tornado has winds of 32-50 meters per second (73-113 mph). That’s the equivalent of up to a category two hurricane on the Saffir-Simpson scale.

The Storm Prediction Center  (SPC) in Norman Oklahoma issues the tornado watches for all of the U.S. They’ve notified Meteorologists like myself and at the local NWS forecast offices that they believe there is a rare “high risk” of tornadoes over Indiana and Ohio on Tuesday. A high risk is rare anytime.

It’s exceedingly rare in autumn.

SPC does only one thing. Forecast severe weather. Meteorologists like myself give high credibility to their forecasts.

The Enhanced Fujita Scale- courtesy of the Storm Prediction Center (NOAA)

There’s been  an amazing technological revolution in forecasting over the last 30 years. In the 1970′s most tornado watches had no reports of tornadoes. Now it is rare for a watch not to verify.

When I was an undergrad meteorology student, I worked on a project at Okla. University in 1980 called SESAME. That stands for Severe Environmental Storms and Mesoscale Experiment. It was a fancy name for trying to correlate what severe storms were doing with what the new Doppler radars were indicating.

I remember being laughed at by people who called it a waste of money. It was anything but.

Doppler radars cover most of the nation now and make it possible for forecasters to give incredibly accurate warnings. An accuaracy I could not have imagined back in 1980.

At 4:15am Monday, the Doppler radar here in North Alabama showed a srong rotation and a tornado warning was issued. We had it on the air in less than 15 seconds from the time the NWS pushed the button. Unfortunately, most people in the little town of Ider were asleep.

The ones who has NOAA weather radios were awake because a loud alarm had gone off. If you live in area where severe weather is likely, you should have one. They only cost about 30$.

It might save your life one night.

You cannot imagine how frustrating it is to break into programming and give a warning while knowing that most people are asleep and will never hear it.

Until it’s too late that is.

Be safe,

Dan

Image form the Climate Prediction Center NOAA. Click to make BIG.

The strong and developing La Nina means that a decent long range forecast of the winter is possible. La Nina, and it’s cousin El Nino, tend to produce predictable weather patterns over the winter months.

Something to keep in mind. The forecast is for the average of the winter months. An above average temperature does not rule out some brief severe cold outbreaks. A drier than normal winter does not mean a certain region will not get a big snow storm.

Image from NOAA.

That said, here is what we can say with the La Nina. The South and Southeast USA will likely be warmer and drier than normal. The Tennessee and Ohio Valleys may see some heavy rains and floods.

Here in North Alabama we could go either way. We are right on the line. 65% of the time we have a milder than normal winter with a La Nina.

La Nina’s tend to bring cold and snowy winters to the NW corner of North America. If you live in Vancouver BC, watch out! It might be a winter to remember!

Kentucky and Ohio look likely to be cool but quite wet.

You can check out the maps but remember this is an average for the winter months!

I took this shot of Ann Posegate in Antarctica.

Ann Posegate, my travel partner to the Pole last January, has a fantastic piece in Weatherwise magazine this month.

It’s all about the difficulties of taking weather observations and forecasting in Antarctica.

Highly Recommended!

Click to read Ann's story.

I never look at an ob from down there without thinking of the people who are there..

Later,

Dan

Pressure pattern at around 18,000 feet (in colour bands) and at the surface (in black lines) for today. The the big high pressure ridge over the East is clearly visible.

For those of you in the Midwestern and Southern parts of America you are likely wondering what the heck happened to fall! Temperatures here in Huntsville in Alabama are running 15 degrees above normal in the afternoon!

This heat wave actually stretches from Oklahoma all the way into Illinois, into Virginia and deep into Old Dixie. It’s really the same heat wave that existed June through August and brought many cities the hottest summer on record.

Same Old Heat Wave

The only difference now is that the days are over an hour shorter and the sun is not as high in the sky. So instead of 106° we see 96°F. Instead of a dew point of 77° we are getting some drier air lingering behind the very weak cool fronts that have managed to break through the upper level ridge. The dew point her ein Huntsville  now is 59°F.

By early next week the pattern changes dramatically with a trough in the east. This means much cooler air and even some desperately needed rain. (Courtesy Unisys weather ECM Model.)

Good news is coming.

The long range numerical weather models are all signaling a pattern change to cooler weather starting this weekend. The strong upper level (heat) ridge will shift to the West and allow the Pacific NW to dry out and see some sun. The East will finally feel some real fall weather.

Right On cue

Click image to read the NRDC report on summer temp. records. Some amazing numbers here.

Meteorological Autumn began back on September first, but most people still use the equinox to denote fall. That occurs at 3:09 GMT Thursday morning. That’s 10:09 PM Wednesday evening (Central U.S. summer time.)

The NRDC has compiled some incredible statistics of the summer heat that are worth taking a look at. You cannot blame any one event or even a brutally hot summer on climate change, but this past summer had some very suspicious patterns to the heat. Patterns that are exactly what you would expect as a result of increasing greenhouse gases.

You can certainly rule out the sun. It has been unusually quiet (see the previous post). You can also rule out  El Nino, since the La Nina has been rapidly developing and this acts to cool the planet.