Everyone has been waiting to see the detailed flood maps which would show which areas would flood if the Wolf Creek Dam in Kentucky catastrophically failed. Wilson County emergency planners released some of the maps of Wilson County to The Tennessean. Some of these maps also included parts of Eastern Davidson County parts and Sumner County. I have spent all day looking at them and wanted to share a few close ups of the Lakewood area along Old Hickory Blvd leading to Old Hickory. The areas in green are where the water would be under the worst case scenario, while the blue areas are for a lesser case scenario. I have a call into officials to clarify the exact definition of the two. The levels are plus or minus 15 ft.

Notice that the water comes up over Old Hickory Blvd. (St. Route 45) in Lakewood. The Hermitage Golf Course and many of the neighborhoods on both sides of Old Hickory Blvd. would be underwater. The Cumberland River bends around Lakewood and Old Hickory to the west, so the river is on both sides of them.

Remember, The Corps of Engineers have lowered Lake Cumberland in Kentucky, so if it failed now, the levels would be much lower than the worst case scenario (in green). However, if we had a week of heavy spring rains in Kentucky, Lake Cumberland could end up rising to dangerous levels.

I’ll be studying all ofthe flood maps as they are released, and will be ocassionally writing entries on nashvillewx.com showing you familiar areas that could be underwater much like I did when I studied the flooding maps from New Orleans after Katrina.

To see all of the maps released by Wilson County to the Tennessean, CLICK HERE.

I’ll post more on the winter storm in the Central United States this morning, but wanted to write a quick post about the difference between sleet and freezing rain. Explanations and pictures after the jump…
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Every August for at least the last 2000 years (accounts go back perhaps since 69 B.C.) earth’s orbit takes us through the tail of Swift-Tuttle comet (NOT forecasted to strike Earth by the way). When our atmosphere interacts with the dust it produces a streak of light across the sky, a “shooting star”.

Go out early Sunday morning and look to the northeast. The waning gibbous with 85% of a full moon (four days past full) should be just to your right with the Perseus constellation straight ahead and about 40 degrees off the horizon appearing to be the origination point for the meteor shower. Basically you’ll need to stare at this point and wait; you could go 30 minutes and see nothing and suddenly see several in a row. Bring a chair!

The graphic (and much of this information) is from “The Star Hustler” Jack Horkheimer out of Miami. He’s a great ambassador from Astronomy and runs one of the country’s best Plantariums.

No! Its a man-made object! The space shuttle Discovery docks with the Space Station around 10am today. Tonight we are forecasting clear skies and low humidity, visibility should be great (especially for summer). With the two linked up you’ll be able to see the duo move across the sky. It’ll be brighter than the brightest star in the sky (Sirius at a magnitude of -1.4, Mars registers usually around -3 or -4 so is much brighter since it is a nearby planet). It’ll be moving fast, the ISS circles the earth every 1.5 hours (that’s moving over 17,000mph) about 210 miles overhead (about the distance from Nashville to Memphis) so it’ll only be in our portion of the night sky about 2 minutes.

According to the NASA viewing table, look about 38 degrees above the horizon to the west and watch a white “star” move to the southeast. It is quite a sight!

I thought I’d offer a behind the scenes look at my forecast to give you a better understanding of our storm chances for the next several days. Did you know that the thickness of the atmosphere relative to the Earth is comparable to the skin of an apple? Meteorologists break the sky down to many different levels for observational and forecasting purposes. We focus on conditions at the surface (we live there, after all) all the way up to 30,000 feet around the level of the jet stream. The weather maps in the extended entry depict forecast conditions around 18,000 feet (roughly the half-way point) and offer a good glimpse of the overall predicted weather pattern. The solid black lines are contours of equal height and indicate the presence of a ridge of high pressure or a trough of low pressure. The areas of red are upper air disturbances (shortwaves). With heat and humidity in place (i.e., summer in Tennessee) a small upper air disturbance is usually enough to encourage upward air motion and trigger a few thunderstorms. I don’t know why, but it feels good to boil four years of calculus-based meteorology into a couple of sentences! Now to the computer maps and the misty distant future.
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Dry weather is in today’s forecast. Why in the world does the NWS Radar Loop show doughnut-shaped radar echoes? I dug through the blog archives and found this pertinent post that explains it all.

If we had 1 rainbow Thursday evening we must’ve had 100.

These beautiful shots were taken by an aspiriing photographer:
“I thought you might like the rainbow that God put over our house today!!
I am graduating this year and hope to be a weather photographer!
Thanks,
Kaytlen Lebens
Fairview, TN”

This one shows all the colors of the rainbow clearly. Roy G. Biv is the acronym that helps us remember the order:
Red, Orange, Yellow, Green, Blue, Indigo, Violet

Here’s an interesting article about cloud seeding efforts in China, where lack of rain and poor air quality have been big problems lately. Whenever the topic of weather modification comes up I get to mention one of my favorite bits of trivia: the atmospheric scientist who discovered silver iodide and its role in cloud seeding is Bernard Vonnegut, brother of American novelist Kurt Vonnegut. Kurt later used some of the ideas in his novel Cat’s Cradle.

No severe threat today, but this sure is the time of year for it. On this date in weather history:

On May 5, 1999…Severe weather outbreak produces widespread wind damage (at least $4.7 million) across Middle Tennessee. Linden is hit by an F4 tornado, killing 3. FAA wind equipment at Nashville International Airport clocks a 99 mph wind gust. Seventy planes are damaged, and 2 hangars are destroyed. Debris and jet fuel are scattered across the runway, closing the airport for several hours. A total of 6 tornadoes strike, the 9th largest tornado outbreak in mid state history.
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