MRLE, part 2: the good, the bad, and the….potentially ugly?

Put on your thinking caps and put your flamethrowers away: this new radar scanning strategy could pose issues for the NWS and emergency managers! Image courtesy; SPC

Before you read this article, read Part 1, here:

Do you MRLE?

So, having said that, what does this mean for you? As a National Weather Service (NWS) meteorologist? As an Emergency Manager? As a storm chaser or spotter?

First, for ice and snow, and for just plain old rain showers, this scanning option generally won’t be used. MRLE is going to be used for severe thunderstorm events, and probably most commonly used for higher-end events, or events that involve a large area (think Mesoscale Convective Systems, or MCS’s, or Quasi-Linear Convective Systems, or QLC’s, or lines of thunderstorms).

Now, here comes some speculation based on facts, and my experiences with the dual-pole radar, and the SAILS2 scanning strategy. I think I’m right on this, but I would love feedback, either yea or nay.

We are going to see 34 second updates for 4 low-level scans in this mode. You’ll see them back-to-back halfway through the volume scan. What I think we’re going to see happen, as a result, is this: we are going to “see”, or catch, a lot more of these EF-0, very short-lived (2 minutes or less, most under a minute) tornadoes in QLCS’s, MCS’s, and derechoes (and even in weak or imbedded supercells). For all of the hype TV stations have with their own doppler radars, including those getting scans every 30-60 seconds, some of them MAY have had a case for saying that we can see tornadoes when the NWS couldn’t…but only for the very small ones, I realize with the SAILS2 scanning strategy, we’re seeing things the NWS couldn’t possibly have seen before, because up until recently, they could only get imagery updated once every 5-6 minutes. With SAILS2 and 2-3 minute updates to the lowest tilts, we now know some of the things the NWS was missing before. I assert that the new MRLE scanning strategy will allow us to see more miso-circulations (and other things) we couldn’t see before, that last a minute or less. And this is going to be a problem in some situations. Why? I see at least two issues:

1. Damage that was classified as microbursts in the past now might be understood to be an EF-0 tornado. These things may have only been on the ground for 10-60 seconds, and they might have only taken down some large branches for less than a block, or they could cause more damage because of lower quality construction of newer buildings (more on that in a moment). We used to just shrug and call them microbursts. Many of them are, but some of them may be brief tornadoes. In the grand scheme of things, this is a very small event that affects a relatively few people. But those people will be mad that a tornado hit their tree and dropped a branch on their car and there were no sirens, and the dreaded “there was no warning” phrase will be uttered in the media.

2. If you are an emergency manager, what do you do if you are not under a tornado warning, but suddenly get reports of damage on 2-3 blocks of your city, you can’t segment out the sirens, so you have to blow them for the entire city, or none at all, knowing that only a small portion of the city will have a shot at one of these weak tornadoes…if that’s what it is?

Now you’re saying…wait. If almost all tornadoes are supercellular in nature, then these are going to be rare events, right? Well, thanks to population growth and technology growth in our country, we’re seeing a lot more tornadoes, even the real small ones, and they are hitting a lot more buildings and things that weren’t there 40, 30, 20 10 or even 5 years ago. Furthermore, in 2017, 77% of Americans had smart phones per the Pew Research Center, and that number, I think, will only increase, albeit at a slower pace than previous years. But that means that if there’s a tornado, and there’s someone who can see it, it’s likely that a smart phone or dash-camera video will wind up on social media very quickly. And the armchair/social media “meteorologists” and the general public will howl when you didn’t blow the sirens, or issue a tornado warning.

There are other new things I think we will see, but I think this one is most obvious, and when we see these leading-edge rotations in squall lines/QLCS/derecho situations, we still have a responsibility to warn of these effectively, when possible. Here’s how I think we should do it:

1. There should be little pressure on the NWS to issue tornado warnings on these. Trying to do this is like playing “Whack-A-Mole”. I don’t care if you are a NWS Warngen god and can fly a warning out in 20 seconds with your nimble fingers, by the time it hits Jon Q. public, it’s either gone or just about to lift. I say this: do not penalize NWS skill scores for short-lived tornadoes (see #2 below in a moment) or are in QLCS/lines of thunderstorms. I’m not talking about “comma head” tornadoes in a squall line, I mean within the line itself. But if you MUST verify all tornadoes, then…

1B. A severe thunderstorm warning should have an option in Warngen to have, in the “Hazards…” section, a line which reads something like: “these thunderstorms are capable of producing very brief tornadoes”. If that line is added, a WEA alert gets sent out with this message: “Severe thunderstorm warning with XX MPH winds and/or large hail likely, and very brief tornadoes possible.”

2. In tandem with #1, NO tornado warnings on QLCS tornadoes unless you are seeing a persistent, significant, longer-lived rotation of over 5 minutes.

Why am I making a relatively big deal about this? Here’s why. In June of 2018, two weak EF-0 tornadoes hit Champaign, IL. There was a tornado warning in effect. No sirens were sounded because the EMA didn’t get any reports of tornadoes. Now, I would have sounded the sirens, but what if they were just under a severe thunderstorm warning? Would you blow the sirens if you have a block where a lot of branches are down, even if large? Maybe…maybe not. But it got EMA into trouble, and the public, which now has access to this data in real time, will be yelling as well. Finally, there’s one more thing. In the case of one of the two Champaign tornadoes, a roof was completely blown off and caused damage downstream as it broke up. It was learned that the roof was not physically attached to the beams of the house, as the nails to attach it all missed the beam when the house was built. That means that the roof was just laying on the house, and that’s why the tornado only got an EF-0 rating (should the EF scale be changed for newer construction? Hoo boy, that could be another blogpost for another day). That happened in one of the houses I purchased, and I made the manufacturer go in and re-nail it. They still missed the beams with quite a few nails, but they did at least hit the beams a lot of times. The problem is, if I jerk my head up close to the ceiling in my attic, I may get nails in my head! But, that’s another story. The point is, construction standards since the 1960 and 1970s have gone down at the expense of quality, so that homes and businesses can be built quickly. Thus, in a new subdivision, you could conceivably get a lot more damage from an EF-0 tornado, than, say, an older subdivision built with brick and a roof where it was attached meticulously. Now, most builders just air gun the nails in, using a lot more nails than needed, knowing some (hopefully) will catch on the beam, and knowing nails are cheap. Furthermore, we have seen many cases where only 4 bolts, one on each side, anchor the house to the foundation. Thus, weaker tornadoes hitting these houses can cause substantially more damage than on older homes. These 2 (or 2.5) suggestions I made above can handle these scenarios, along with public education of these brief spin-ups.

So, welcome MRLE, for better, and possibly, for worse for the National Weather Service and EM’s, not to mention, the general public. What do you think? Feel free to leave a comment!

Do you MRLE? Part 1

A doppler radar sits scanning the skies with a developing thunderstorm nearby. A new scan strategy is being tested by the National Weather Service to help us see what’s going on at the lowest parts of the storm more accurately with additional scans. Image courtesy: SPC

As the National Weather Service continues to improve upon doppler radar scanning strategies during severe weather events, there is a new one for you to know about and understand. SAILS was introduced a few years ago and was a great help in rapidly changing conditions. But now, MRLE is coming, and is being tested at 15 radar sites around the country.

What is MRLE? MRLE stands for Mid-Volume Rescan of Low-Level Elevations. If you are aware of SAILS, you know how that works. The radar scan starts at the lowest tilt, or level, and progressively scans tilts at higher and higher angles, giving you a 3-D view of a shower or thunderstorm. Halfway through the volume scan, the radar comes back down and rescans the lowest level, so you can see what’s going on as close to the base of the showers and thunderstorms as possible. This data is what people commonly use, and what is seen on AllisonHouse Maps and AllisonHouse-supported radar software, as well as on TV. However, MRLE allows for up to four low elevation scans, instead of just one extra, in any volume scan. This lets us see what’s happening at the lowest part of the storm more accurately with more frequent updates, to see how, for example, a rotating thunderstorm called a supercell is developing or evolving, and how ground threats are potentially changing.

So how does the new MRLE scan strategy work? It goes like this: the radar scans the lowest 8 tilts (up to approximately 5.1 degrees at tilt 8). Then, the radar goes back down to roughly .5 degrees (or, more accurately, tilt 1), and scans the lowest 4 elevation angles one more time, in 30 second intervals, depending on how the radar operator configures it. After that, it continues to scan with the remaining 6 upper tilts as usual, ending at 18.5 degrees.

If you are like “this is just like SAILS, but I get additional lower level scans halfway through the volume scan every 30 seconds”, you are correct!

Now, a person may ask, “why don’t you have a mode that just sticks to doing lowest level scans?”. If you do that, you don’t get a 3-D view of the storm, you don’t get products like digital VIL, for detection of hail and hail size, and you don’t see how a mesocyclone (the rotating updraft portion of the storm) is behaving at mid-levels (or to see if there is one present or forming). As it is, the total number of scan tilts is reduced to handle the additional low-level scans.

More details on MRLE is available on the Radar Operations Center’s website:

https://www.roc.noaa.gov/WSR88D/NewRadarTechnology/NewTechDefault.aspx

The test is expected to run approximately one year on these 15 sites:

KAMA – Amarillo, TX
KDGX – Jackson, MS
KJKL – Jackson, KY
KLSX – St. Louis, MO
KEMX – Tucson, AZ
KLRX – Elko, NV
KICT – Wichita, KS
KIND – Indianapolis, IN
KDVN – Quad Cities, IA
KILN – Wilmington, OH
KPUX – Pueblo, CO
KEWX – Austin/San Antonio, TX
KENX – Albany, NY
KRAX – Raleigh, NC
KUDX – Rapid City, SD

If proven successful, this scan option will be adopted in 2019 nationwide. Some software may require updates to handle this new scanning strategy properly; an update is coming for GR2Analyst to get the extra scan updates to you more quickly.

Not good news concerning GOES-17

GOES-S Logo

GOES-17, the future GOES-West satellite, has a major issue, according to a statement issued by NOAA this morning.

AllisonHouse has received this memo from NOAA today about the status of GOES-17:

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May 23, 2018

The GOES-R Program is currently addressing a performance issue with the cooling system encountered during commissioning of the GOES-17 Advanced Baseline Imager (ABI) instrument. The cooling system is an integral part of the ABI and did not start up properly during the on-orbit checkout.

A team of experts from NOAA, NASA, the ABI contractor team and industry are investigating the issue and pursuing multiple courses of possible corrective actions. The issue affects the infrared and near-infrared channels on the instrument. The visible channels of the ABI are not impacted.

NOAA’s operational geostationary constellation — GOES-16, operating as GOES-East, GOES-15, operating as GOES-West and GOES-14, operating as the on-orbit spare — is healthy and monitoring weather across the nation each day, so there is no immediate impact from this performance issue.

If efforts to restore the cooling system are unsuccessful, alternative concepts and modes will be considered to maximize the operational utility of the ABI for NOAA’s National Weather Service and other customers. An update will be provided as new information becomes available.

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Gilbert’s note: in English, this means that the new, soon-to-be GOES-West, GOES-17 satellite would only provide visible imagery, lightning mapper imagery, magnetic readings from the sun, along with a few other products, and that’s it. Infrared, near-infrared and water vapor imagery would not be produced; therefore, some major effects would include that most imagery during nighttime hours would not be available, along with moisture content in the air, which helps us see where systems are in the atmosphere that can produce weather on Earth. Infrared imagery is very useful around the clock, and is a temperature “map”, if you will, which allows us to view clouds at any time, day or night. The GOES-17 infrared channel of the ABI is sensitive enough to even see fog well at night! Water vapor imagery helps us to see disturbances in the jet stream that can assist in the production of snow in winter, and rain/thunderstorms in the warmer seasons. As a result, not having these capabilities severely reduces the functionality of the satellite. We’ll have updates on this situation once more information becomes available…but clearly, if this issue cannot be corrected, then this will be a major blow to the new satellite, and NOAA’s weather satellite program.