Various topics for May 29, 2009

Tropical Depression One
T.D. 1 is headed out to sea after exiting the Gulf Stream overnight with no further intensification. It poses no threat to land and should become extratropical by Saturday. An early arrival of the first depression of the year means nothing as far as what the hurricane season will bring; however, new evidence of El Nino conditions appearing over the eastern Pacific could have an effect, according to Weather Underground's Dr. Jeff Masters.

Heat returns
After flirting with the 90 degree mark earlier in the week, and then remaining in the mid 70s yesterday (what a great day!), we'll again make a run at 90 just in time for the start of "meteorological summer" (defined as June-July-August) as upper-level high pressure moves in this weekend. We could reach 90+ on Monday and Tuesday, and we'll be pretty close Saturday and Sunday! Average highs for this time of year are in the mid 80s. Check the "most accurate Memphis forecast" at MemphisWeather.net for more details.

New Memphis ATCT Rising over the Airport
Since my second big interest behind weather is aviation, I've been keeping an eye on this site with a webcam showing the FAA's new Air Traffic Control Tower being constructed at Memphis International Airport. (There is even a time-lapse feature that is cool to watch.) I drive by the tower every day on the way to work, so I've gotten to see the new landmark as it rises into the sky. It's now almost as tall as the old control tower and still rising! The new tower will boast double the space for controllers in the tower cab (the room at the top of the tower) and will be well over 100 feet TALLER than the existing tower when commissioned in 2011. At 336' tall, it will be the third tallest control tower in the south. The radar control room at the base of the tower is also part of the new construction, as well as administration offices and training areas. For more on the new tower, check out this archived article from the Commercial Appeal.

Yes, but did your hair stand on end?
Check out this amazing video on AccuWeather of a guy that was filming a thunderstorm and ended up filming a lightning strike less than 0.4 mile away!

Poll on wall-to-wall severe weather coverage
You've got until Sunday night at midnight to take this week's MWN Blog poll on wall-to-wall severe weather coverage. Is it too much, not enough, or just right? Cast your vote, then check out my previous blog on the subject.

MWN on social media sites
Be sure to check out MemphisWeather.net on Facebook (and become a fan!) and follow me on Twitter for micro-blogging on current weather and other weather-related topics. You'll also get Shelby County warnings via my Twitter feed. Amazing what you can do these days with the Internet...

T.D. One forms in the Atlantic - no threat to land

According to the National Hurricane Center, the 2009 Hurricane Season has begun (4 days early) with the formation of Tropical Depression 1 about 225 miles offshore from the NC/VA coastline. Wind has reached 35 mph and the storm is moving over the warm Gulf Stream waters under little wind shear, so a minor increase in strength is forecast and the storm is expected to become Tropical Storm Ana later today. Thereafter, the storm will weaken as it moves swiftly into the open Atlantic. I'll be keeping an eye on Stormpulse.com for tracking hurricanes this season. Check it out if you have an interest in tropical weather. MemphisWeather.net also has a tropical page that will be updated throughout the season as well.

Has BK started serving lunch meat?

Or do fast food chains have their own team of climate scientists now? Here's a related article from the oft-offbeat Memphis Flyer.

Pics of cumulus at sunset

Taken 5/27/09 just after dusk, around 8:30pm, in north Bartlett looking west. Thunderstorms were south of the area. Notice the crescent moon in the first picture at upper-left.

Tropical low spins over Mid-South

It's not all that often that the Mid-South gets to see a remnant low from a former "almost tropical" system over the area, but that's exactly what is happening today. The low that everyone was watching over the Gulf this past week didn't quite make it to a tropical depression (although another day over water and it might have) and came ashore near the AL/MS state line on Saturday. Over the past 24 hours the system has moved northwest around the periphery of high pressure ridging to the east. With abundant moisture in place (note the humidity levels this weekend), the low has tapped into daytime heating to produce scattered showers and a few thunderstorms this afternoon.

Satellite and radar imagery tells the whole story as these showers rotate counter-clockwise around the low, which as of this writing is positioned over east-central AR. The radar image above shows the banding of the rain showers typical in this type of system. The embedded movie loop of visible satellite shows the characteristic "spin" of the low pressure. The pictures above show the cumulus cloud field over the area and the darker clouds containing showers. Being on the east side of the low for the next couple of days will mean a wind component from the south and residual moisture that will combine to produce mainly daytime and evening showers and thunderstorms until a cold front later in the week can push all of it out of here. See more radar and satellite, as well as the MWN Forecast for Memphis, at MemphisWeather.net.

Memorial Day weekend could be a wet one

With the holiday weekend upon us, you're probably wondering if those outdoor activities will be rained out.  Unfortunately, the overall news is not that good, though the whole weekend will not be a washout.  After a beautiful week dominated by high pressure, we can thank the low pressure system over the Gulf of Mexico that has drenched much of Florida and portions of the Caribbean for our increased rain chances.  The low will approach the Gulf Coast near the LA/MS border tomorrow, but ahead of it, mainly daytime showers and a few t'storms will be scattered over the region today.  Most of this activity will die out this evening so Friday night activities should be fine for the most part.

By Saturday, chances of rain go up again, primarily after noon.  Scattered thunderstorms, about a 50% chance, will be around Saturday and Saturday evening for the end of the Memphis in May activities and the Sunset Symphony.  Rain chances actually increase overnight Saturday and continue on Sunday, with the possibility of some areas seeing heavy rain.  In addition, thunderstorms will be likely on Sunday as the low moves closer to the region.  Rain chances continue on Monday, but should once again be primarily driven by daytime heating, so the best chance will be afternoon and evening hours.

The wet forecast continues through much of next week, with daytime thunderstorms and warm and muggy conditions, until a cold front tries to move it all out of here by the end of next week. The graphic above shows the expected total rainfall from now through Wednesday morning, with Memphis on the edge of as much as 3" of rain.  For a complete forecast and MWN Interactive StormView Radar, visit MemphisWeather.net.

Tornado hunting and early tropical weather

Since there is no weather of particular interest here in the Mid-South (how much can you say about beautiful conditions under broad high pressure?), I decided to devote some ink (or pixels) to a couple of other interesting topics in the weather world: VORTEX2 and the start of the Atlantic hurricane season.

The National Hurricane Center continues to monitor two areas of low pressure near Florida.  One, an investigative system until this morning, is weakening over the Bahamas and southern Florida, while the other could still have some potential over central Florida.  That system is expected to emerge off the west coast of FL and into the Gulf of Mexico later this week.  Models are still having a little trouble with it's eventual track, but indications are it could move north into the northern Gulf of Mexico by late in the week and could bring afternoon showers and thunderstorms to the Mid-South beginning this weekend.  Though it's very unlikely to become a "named" system, it is generating some interest, especially in FL where it could prove to be a drought-buster.  It is still a couple of weeks prior to the official start of hurricane season (June 1), though I've not heard of Mother Nature waiting on a calendar date for anything!  Stay tuned to the MemphisWeather.net forecast to see how this affects Mid-South weather.

On the other extreme, scientists from multiple institutions and universities have banded together this spring to try and learn more about tornadoes.  This operation, dubbed VORTEX2, is "the largest and most ambitious effort ever made to understand tornadoes."  It involves over 100 personnel and as many as 40 vehicles loaded with the latest in high-tech gadgetry and instrumentation, including 10 mobile Doppler radars, unmanned aircraft, and weather balloon launchers.  The goal is to get a better handle on the formation and evolution of tornadoes and the storms that cause them.  Questions they hope to answer are:

- How, when, and why do tornadoes form? Why some are violent and long lasting while others are weak and short lived? 

- What is the structure of tornadoes? How strong are the winds near the ground? How exactly do they do damage?

- How can we learn to forecast tornadoes better? Current warnings have an only 13 minute average lead time and a 70% false alarm rate. Can we make warnings more accurate? Can we warn 30, 45, 60 minutes ahead?

The experiments began May 10 and run through mid-June and will be conducted again in 2010.  For more information on this vast project, see Vortex2.org or this page from the National Severe Storms Lab.

New poll posted on the MWN Blog

A new poll has been posted on the MemphisWeather.net blog asking about your opinion of severe weather coverage by Memphis-area TV stations.  So what do you think?  Too much hype, not enough, or just right?  Cast your vote, then check out my opinion from a previous blog post by clicking here.  You comments are welcome there. Results will be posted May 25 so be sure to check back.

Don't forget, you can also find MemphisWeather.net on Facebook and Twitter (memphisweather1), besides the original website at www.MemphisWeather.net.

I'll also be tracking the development of a potential subtropical or extratropical low in the Gulf of Mexico this week that will provide plenty of rain to Florida and the Bahamas this week and the possibility of rain for the Mid-South next weekend.  Stay tuned!

Weekend outlook and a peek at the week ahead

A strong late spring cold front is moving through the region today and has sparked thunderstorms, mainly to the east of the Memphis metro area over the past hour.  Some scattered showers trail the front over northeast AR.  For the rest of today, I think the thunderstorm chances for the metro are slim, though a few of those showers could affect the region through about the dinner hour.  I certainly am not expecting a washout today for the Memphis in May World Championship BBQ Cooking Contest or other outdoor events.

By this evening, drier and cooler air will be filtering into the Mid-South on gusty northerly wind.  Strong, seasonally cool, high pressure behind the front will make for a very nice week ahead.  Temperatures will fall to below normal levels - even a few cool nights early in the week.  Temps will moderate to near normal levels as the week goes on and rain chances re-appear late in the week.  Get your complete Memphis area forecast at MemphisWeather.net.

This is also post #300 for the MWN Blog.  Thanks to all of you who read and comment!

Forecast for the Memphis in May BBQ Cooking Contest

A cold front will work it's way into the Mid-South today. Ahead of the front, remnants from last night's severe weather have moved into the metro region early this morning, bringing a fairly strong gust front, followed by a broken line of t'storms and an area of rain and embedded thunder trailing the line. Expect this rain to last through late morning, with scattered showers and thunderstorms continuing this afternoon. Highs should still reach near 80 by late afternoon.

Tonight, the front lifts back to the north and takes most rain chances with it. Low chances are again in order for Friday's opening to the Memphis in May World Championship BBQ Cooking Contest. Then, that front makes one more run at us Saturday, bringing more rain and thunderstorms. Everything moves out by Sunday morning with a pleasant day for the most part and a good start to next week. Overall, chances for severe weather are low, but not negligible the next few days. For a complete forecast, visit MemphisWeather.net and the MWN Forecast.

April 2009 climate stats and forecast accuracy

April 2009 was a dry month, but temperatures averaged right at normal. Following are climate summaries for Memphis International Airport and Bartlett, TN.

Memphis International Airport
At the official recording station for Memphis, the average temperature was 62.0 degrees, which was 0.1 degrees below normal. The highest temp for the month was 85 degrees, recorded three times during the last week in the month, and the lowest was 36 on the 7th. Precipitation totaled 3.63", which was over 2" below the normal of 5.79". There were 9 days with measurable rainfall recorded and one day with more than an inch of rain. Five days had recorded thunder. The peak wind gust was 40 mph on the 19th. Click here for the NWS recap.

WXLIVE! in Bartlett
In Bartlett, WXLIVE! recorded an average temperature was 61.4 degrees, with a max of 87.4 on the 23rd and a min of 34.4 degrees on the 15th. Precipitation totaled 3.46". The peak wind gust was 33 mph on 4/5. Click here for the WXLIVE! recap.

April Accuracy
The MWN Forecast accuracy statistics are finalized as well. For the month of April, the MWN forecast beat out the computer models and the NWS forecast in the temperature and dewpoint categories. Average MWN temperature error for April was 2.38 degrees, followed by the NAM model at 2.44 degrees, the NWS at 2.48 degrees, and the GFS model at 2.56 degrees. As you can see, all model's performance was very similar for the month, but once again MWN takes the cake!

A note on climate: year-to-date precipitation

After running behind in the precipitation category for much of the year, this month's rains have caught the area back up to normal. As of this afternoon, Memphis Int'l Airport is now about a qurater-inch above normal for precipitation year-to-date with a total of 21.79". For the month of May, however, you will not be surprised to know that we are WAY above normal, with 5.71" in the past 9 days, which is 4"+ above normal. Our average rain for the ENTIRE month is 4.98", so we have exceeded our monthly total barely a third of the way into the month! Unfortunately, the MWN forecast is calling for more of the same, with chances well into next week.

On a separate note, the official low temperature in Memphis for Friday, May 8, was 74 degrees, which is the warmest low temperature on record, beating the previous record of 72 set last in 2003.

Derecho moving through Ozarks and effects on Memphis weather

A very strong convective system called a derecho (learn more) is moving rapidly east-southeast this morning through the Ozarks. Wind gusts of over 80 mph have occurred with this system and tornado warnings are posted for many locations as it moves through. A movie loop of Springfield, MO radar from 8:00-8:45am is shown above. Memphis is in the lower right corner of the map.

This is the same type of system that came through Memphis on July 22, 2003 and became known as"Hurricane Elvis." It will continue moving rapidly east-southeast towards the Mid-South as the morning progresses. Another convective system moved through middle TN earlier this morning and put down an outflow boundary across portions of west TN as well. With a cold front seeping into the area from the north, the groundwork is being laid for scattered thunderstorms beginning around the lunch hour and throughout the afternoon. Whether the derecho comes through this area, especially in it's current form, is in doubt, but the threat exists. In fact, a Tornado Watch has just been posted for most of west TN, except the counties bordering MS, including Tipton County. Stay with MemphisWeather.net and interactive StormView Radar as this weather system approaches. Updates will also be posted as necessary on my Twitter feed.

Recap of Wednesday AM storms (5/6/09)

Storm aftermath

The image above from MWN StormView Radar was snapped during the height of the storms overnight last night (early Wednesday, 3:14am).  The northern end of a line of storms associated with a mesoscale convective complex (MCS) grazed southern Shelby County between 2:30-3:30am.  About 30-40 miles south of the MS-TN line, the NWS was issuing Tornado Warnings for this supercell.  The image shows that StormView Radar picked up on a TVS (Tornado Vortex Signature - inverted magneta triangle above) associated with the tornado warning (box in magenta).  Severe Thunderstorm Warnings were also in effect (red boxes), as well as Flash Flood Warnings (green boxes).  The leading edge of the MCS extended from southern Shelby County westward through central AR at this time and the area was under a Severe Thunderstorm Watch and Flash Flood Watch.  Definitely a busy night for the NWS!  Locations across Shelby County reported 1.50-2.00" of rain overnight according to CoCoRaHS observers and NWS climate stations.

Storm Surveys

The TVS was tracked all the way from west of Tunica in east-central AR to north-central MS. According to Local Storm Reports, NWS storm surveys were done earlier today and indicate that the parent storm produced EF-1 tornado damage in Marvell, AR (Phillips County, across the river from Tunica) with trees and power lines down and damage to a retail establishment at about 2am.  Wind was estimated at 95-100 mph and the tornado had a path length of 100 yards and was 25 yards wide.

Further downstream, the storms spawned another brief twister of EF-1 intensity near Clarksdale, MS (Marshall County) at about 3:30am.  The tornado had similar characteristics (105 mph, 25 yards wide, 100 yard path length) to the Phillips County tornado and produced roof damage to some homes and snapped trees.  In addition to the tornado damage, trees and powerlines were downed all across north Mississippi due to the saturated ground and high wind.

What's in store?

So, is more of this violent weather in the offing?  Unfortunately, possibly.  I do believe most areas will get a reprieve through Thursday evening, though the Storm Prediction Center has the area highlighted in a SLIGHT RISK for Thursday.  I am forecasting storms to be few and far-between, though with plenty of moisture and temps soaring into the 80s with some sunshine, any storm that gets going could be strong Thursday afternoon. 

A frontal system that has been lingering around the area will make another push towards the metro Friday into the weekend (we are in a SLIGHT RISK again on Friday).  With upper-level impulses expected to move along that front, and with daytime heating creating instability in the afternoons, I expect thunderstorm chances to increase each day Friday into Sunday.  Another one of these MCS's can not be ruled out either.  If the formation and track of one of them is more certain, and it looks like the Mid-South is in the bulls-eye, obviously thunderstorm chances would increase a great deal.  All in all, I think most of us will get more rain before the end of the weekend.  Stay with MemphisWeather.net and the MWN forecast for the latest on this dynamic scenario.

Commentary: "wall-to-wall" severe weather coverage

An excellent post on Bamawx.com's blog (which I encourage you to read), and the responses posted therein, have prompted me to comment here on the practice of "wall-to-wall," or "long-form," severe weather coverage. Mike Wilhelm, who does an exceptional job at Bamawx.com, took some heat for his commentary supporting the practice of long-form coverage when portions of a TV station's coverage area area under Tornado Warnings. His post was prompted by a sports radio talk show host in Birmingham who dedicated an entire show to, basically, slamming OCM's (on-camera Meteorologists) for keeping the public informed when threatening weather approaches. I know only a little about the nature of wall-to-wall coverage in Alabama, but I do know that due to their propensity for severe weather, and past weather events that have affected highly-populated areas, they have a history of long-form severe weather coverage that may be second to none, at least in this part of the country.


With respect to wall-to-wall coverage in the Memphis DMA (viewing area), a couple of the main players have embraced this form of broadcasting when a Tornado Warning is in effect within their DMA. At least one has gone "no-hype" and will use crawls and other graphical methods of displaying the information, up to the point where a fairly significant population center is under direct threat, at which point they break-in to regular programming. Wall-to-wall coverage has always been a hot button issue - there are very few people that do NOT have an opinion on the matter. I would guess that it is a little more accepted right now in the Memphis metro area after the tornadoes struck Shelby County last February, though heightened awareness and acceptance of the practice will certainly decline with time, unless another unfortunate event were to occur.

The problem with this form of coverage, as I see it, is that generally a very small percentage of the viewing audience is under direct, or indirect, threat from the storm(s) being covered. This tends to upset or even anger the rest of the audience. However, to those people whose lives are at risk, the coverage could be a vital and life-saving necessity. I like to equate it to the guy who is walking down the beach littered with starfish and is throwing them back one by one. He'll never save the lives of every starfish, but to the ones that he throws back in the water, his act was vitally important. It is a tough choice to make - when to interrupt programming and risk many frustrated viewers, in order to get life-saving information to the few. (I don't think it's nearly as tough a choice, and I would guess the hate mail goes down precipitously, when a tornado is bearing down on Memphis and TV stations go wall-to-wall.)

So, my opinion on the matter is this, and it may be unpopular: Long-form severe weather coverage should be employed when a particularly dangerous situation is imminent that directly threatens the lives of the people who reside or work in the area affected. I am in favor of split-screen graphics that continue to show regular programming in a small window, but the audio belongs to the OCM. As soon as the threat diminishes, return to regular programming. Naturally, a Tornado Warning falls within my definition above, as would a "very severe" thunderstorm (one known or highly suspected to contain life-threatening wind like Hurricane Elvis, for example) impacting a population center. I also believe that as the threat and risk to life increases, so does the likelihood of moving from split-screen to full-screen coverage. In this day of high-tech internet-driven media, I also firmly believe that the internet should be a prime source of weather information that is CURRENT, TOPICAL, and ACCURATE. MemphisWeather.net is a prime example and the TV stations should be on that leading edge as well (and many are). I hope that you will continue to see the value in what MemphisWeather.net provides in this regard.

So what do you think? Is it too much? Not enough? What factors should be taken into account? Feel free to agree or disagree with me - it's how we as providers learn what the public wants and needs.

More rain on the way

After a brief respite, another round of rain and thunderstorms will arrive tonight with the potential for flash flooding once again a reality. A stationary front positioned to our south will lift north tonight, while an upper-level impulse rides that front from west to east into the Mid-South. I expect most rain to hold off until after 10pm, possibly as late as midnight, in the metro area, and then last through much of the night and early Wednesday. Widespread rainfall totals of 1-2" are possible, with locally high amounts possible. The chance of rain lingers into Wednesday before tapering off. The next potential round moves in Thursday afternoon with chances unfortunately continuing through the weekend once again. Check the MWN forecast for more.

Threat switches to flooding

It appears as though the severe weather threat is becoming more of a flood threat for this weekend as the effective cold front has moved over the metro area and moderate to heavy rain trains across the region from west to east.  The entire region is under a Flash Flood Watch until Monday morning and Flash Flood Warnings are being posted as necessary for heavier areas of rain.  The potential for 4-6" of rain exists from last night through Monday morning (see the graphic above).  Be alert if you come across standing water - remember that 6" of moving water is enough to pick up a car!  Unfortunately, the situation does not bode well for Beale Street Music Fest (which goes on rain or shine) and other outdoor activities on this first weekend in May.  Stay with MemphisWeather.net for the latest on the potential flooding threat.

Thunderstorms, some possibly severe, throughout the weekend

The Storm Prediction Center has placed the Memphis metro area under a SLIGHT RISK of severe weather all the way through Monday morning. I expect most thunderstorms to be diurnally-driven, which means they will occur during maximum heating - afternoon and evening hours - today and tomorrow, as a cold front sags south and stall over the region. Some of these storms could be strong enough to produce a damaging wind gust or large hail.

The situation changes a little on Sunday. By then, a potent upper-level shortwave will be sweeping across the southern Plains, dragging a cold front with it. The severe weather threat will be mainly confined to this feature, which will move through the Mid-South sometime between late afternoon and the overnight hours Sunday. I expect we will see a squall line with potentially high wind, some large hail, and maybe the threat of tornadoes. Stay in touch with MemphisWeather.net and the MWN forecast for the latest.