StormView Radar to be unavailable December 1-15 due to radar upgrade

Beginning Thursday morning, December 1, MemphisWeather.net's StormView Radar will be unavailable for two weeks.  It is expected to return to service on December 15.  Alternate radar links will be provided on the StormView Radar webpages, as well as on our mobile site (m.memphisweather.net).  On the MWN Android and iPhone apps, radar data will NOT be available during the outage due to programming constraints.

The reason for the outage is a significant upgrade to the National Weather Service (NWS) Doppler radar in Millington, TN.  The Millington radar (KNQA) provides the raw data to power StormView Radar. The upgrade, known as "dual polarization" (or dual-pol), was described in a previous blog post and represents the largest advancement in technology applied to the nationwide Doppler radar network since it's initial installment in the 1990s.  There are many benefits that meteorologists with access to the radar data (especially those who provide warning services to the public from the NWS) will reap.  Those are also described in the previous post linked above.

We apologize in advance for the inconvenience this will likely cause, though we ask you to understand that this is completely beyond our control and is a necessary and highly beneficial upgrade to the weather community.

To learn more about dual polarization, or to take online training designed for non-meteorologists on the changes, visit this MWN blog post or the NWS-Memphis dual-pol overview page.

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What caused rapid storm intensification over Memphis on the evening of May 16, 2010?

On the evening of May 16, 2010, a mesoscale convective system (MCS) moved into the Mid-South from the west. The quasi-linear complex of thunderstorms, followed by an area of rain, reached the metro area around 7pm. As it approached, the strongest storms were a bowing segment of thunderstorms south of the city over northwest Mississippi and strong/severe storms well north, with a relative dearth of strong storms directly west of the bridge. It appeared the city would miss the strongest activity.

As evidenced by the StormView Radar loop shown below, while no severe storms struck the city, there was a definite "explosion" of heavier precipitation along a north-south line (basically right along the Midtown stretch of I-240 north into Shelby Forest) just after the outflow boundary ahead of the area of precipitation reached the city. The very heavy precipitation didn't continue across Shelby County, but preceded several miles before weakening again (after the time of this loop).

So what caused the sudden explosion of precipitation intensities? Could it have been an urban heat island effect, which could have easily provided extra convective potential? Perhaps another atmospheric boundary of some sort existed across that region? These types of systems are certainly not steady-state either, so it could have been a natural progression of the convective system. I didn't get a good chance to examine the data in real-time; I'll take a closer look and let you know if I find anything. In any case, it made for an interesting radar loop worth sharing.



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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.

Freezing precip just north of Memphis

A look at MWN StormView Radar at 6:30am shows freezing rain just north of Memphis, though parts of Tipton County, while sleet and some snow is farther north, roughly north of a line from Paris to Dyersburg to Harrisburg, AR. Temps have pretty well leveled out and are only very slowly falling. It's 32.9 degrees in Bartlett at 6:35am with moderate rain.

Power outage affecting MWN

WXLIVE! data and MWN StormView radar is currently out of service due to a power outage. We apologize for the inconvenience. There is no estimated return to service at this time. See above for a snapshot of the outage summary for Memphis as of 2:50pm or the link to the right which provides the current outage information.

UPDATE: Power was restored at about 4:20pm - the outage lasted right at 3 hours. Seems there was a large tree that came down a couple of miles away that took out a main power line and caused ~1000 customers to lose power.

6:30am - Narrow squall line crossing the river

At 6:30am, MWN StormView Radar (shown above) is depicting a fast-moving but narrow squall line crossing the river into downtown Memphis and Shelby Forest and also approaching the airport in south Memphis. This line will move across the metro area over the next hour, bringing brief torrential rain and wind gusts as high as 40-50 mph. Behind this line, showers and isolated thunderstorms will continue for a couple of hours, but I expect most precipitation to be east of the city by 9:00-9:30. Wind will shift to the southwest but remain very gusty through the morning and early afternoon.

Have any damage reports? Things being blown around that usually aren't? Leave me a comment below!

First bit of freezing rain falls on metro Memphis

As depicted in the image from MWN StormView Radar in winter mode on the metro view at 8:09pm, freezing rain was falling in Shelby County thanks to a passing shower. It passed right over the WXLIVE! sensors in Bartlett, where it immediately froze due to a surface temperature of 29F. StormView nailed the precip type and appears to be doing a great job of picking up the areas of freezing rain and sleet. To the northwest of the city where cold air is a bit deeper, it is showing sleet. Jonesboro has just over 1/2" of sleet on the ground. If you experience winter weather, feel free to drop a comment on this post! I'd love to hear from you.

I've also added some links to the top right of this blog for area road conditions, school closings, and the latest storm reports from the National Weather Service. The scenario appears to be unfolding as forecast so far. Please exercise caution if you must be on the roads from now until noon tomorrow.

Today's balmy weather to end this evening

Taking a look at StormView radar at 4:00pm, isolated light showers are beginning to pop up in northeast AR ahead of a strong winter cold front. Along the front, stretching from north-central to west-central AR, Little Rock NEXRAD is detecting a narrow band of rain, with some embedded heavy downpours. These showers will increase in intensity and coverage over the next several hours as the front sweeps east. Look for the front to pass through the metro region between 9-11pm this evening, with some showers ahead of it, moderate to heavy rain right along the front, and continuous light to moderate rainfall for a couple of hours after the front passes. Rain totals of 0.75"-1.00" are possible tonight.

In addition, the passage of the front will signal an end to today's "balmy" 60+ degree weather, with temps dropping up to 15 degrees in the hour or two after the front passes and bottoming out in the morning in the mid to upper 30s! Very little recovery will take place tomorrow with highs in the 40-45 degree range.

StormView Radar detects first snow flurries!

Looks like the snow flurries missed most of Memphis proper as temps hung out near 36-37, but according to StormView radar, light snow flurries were falling at 6:20 this morning across a decent portion of West TN and extreme northeast MS. The airport in Jackson, TN was reporting snow flurries and 34 degrees at the time this radar shot was taken. Notice the greens (drizzle/light rain) in the warmer metro area vs. the grays (light snow) farther out from the city. Sorry kids - no snowmen this time!

MWN StormView Radar is now live!

StormView Radar has two "flavors" - a regional view and a metro Memphis view. Fully-interactive and driven by the latest Flash technology, you'll find it easy to use and packed with features! Make sure you visit MemphisWeather.net and select StormView from the Radar menu. Its first images (one of which is shown above) are of cold air advection showers over portions of the metro area, which are moving quickly southeast in the wake of a strong cold front that passed through last evening.

As a side note, if you operate a small or medium-sized business in the Memphis area and want to have your banner ad on both StormView pages, you can sponsor MWN StormView Radar. Send me an email or click the banner on the StormView page.

T-minus 1 day and counting...

COMING TOMORROW -- SATURDAY NOV. 15!!

Just another reason MWN is "all the weather you need for Memphis and the Mid-South..."

It's coming... MWN StormView Radar

It's right around the corner! Coming in a matter of days...

The next big addition to MWN will be a Flash-based interactive radar - where YOU have control over what you see. Zoom in to your area, add storm tracks and severe weather warnings, overlay radar-based severe weather indicators, see how much rain has fallen across the area, even see where winter precip is falling!

"All the Weather You Need for Memphis and the Mid-South"
-- MemphisWeather.net, soon with MWN StormView Radar --

Another upgrade to MWN!

Coming soon to MemphisWeather.net...

MWN StormView Interactive Radar

The next big addition to MWN will be interactive radar - where YOU have control over what you see. Zoom in to your area, add storm tracks and severe weather warnings, overlay radar-based severe weather indicators, see how much rain has fallen across the area, even see where winter precip is falling!

"All the Weather You Need for Memphis and the Mid-South" - MemphisWeather.net, soon with StormView Interactive Radar