Feeds:
Posts
Comments

Archive for the ‘Lightning Mapping Array’ Category

We have a long history of usage of total lightning data via the North Alabama Lightning Mapping Array (LMA) data here at the National Weather Service office in Huntsville, AL. LMA data began flowing here way back in the spring of 2003.  There have been minor interruptions of data at times, mainly during and shortly after the implementation of AWIPS II, but total lightning data have been an integral, consistent part of operations here for over 10 years.  These data have been used most often for detecting the initiation of electrical activity in developing convection.  This is important because studies show that intra-cloud lightning often precedes cloud-to-ground lightning by about 5 to 10 minutes.  Thus, total lightning data can serve as an early warning signal of the more dangerous cloud-to-ground component.  We’ve also used the data to help identify thunderstorms that may experience rapid intensification, since total lightning activity is directly related to strengthening updrafts.  I’ve even posted about an event in March 2012 where I used the LMA data as supplemental evidence that helped prompt a severe thunderstorm warning.  This past Sunday evening (August 10th) I had the opportunity to use the data in a unique way (at least for me)…to help with a flash flood warning decision.

The first image below is a loop of KHTX WSR-88D 0.5 Reflectivity from this afternoon.  Notice the cell that developed and persisted over northwestern portions of Morgan County.  This cell developed directly along the Tennessee River and over the city of Decatur, AL.

Image 1.  KHTX 0.5 deg reflectivity 1920-2112 UTC 10 August 2014

Image 1. KHTX 0.5 deg reflectivity 1920-2112 UTC 10 August 2014

The cell was producing heavy rainfall, and the other operational forecaster and I were watching it closely.  One-hour rainfall amounts shortly after 2100 UTC were approaching 2 inches according to KHTX and nearby ground stations, which was near flash flood guidance for basins in this area.  Of course, we were also dealing with data latency from these various sources, which is generally anywhere from about 5 to 20 minutes or more depending on the source. In a flash flooding situation, just as any other warning situation, things can evolve quickly and data updates as fast as possible are desired.

Perhaps most concerning however, was the fact that this cell was back-building and showing signs of little movement during the period, while some of this rain was falling over the city of Decatur. True, Decatur is a relatively small city, but still has sufficient urban land cover, and is bordered to the north and east by terrain that slopes gently toward the Tennessee River. So, drainage of water can be slow in the city, especially once adjacent backwaters and wetlands associated with the Tennessee River fill with water. While considering a flash flood warning, I still wanted some idea of the potential longevity of the cell over the Decatur area.  The area could have handled this much rainfall if the cell dissipated and/or moved off as most others were prone to do in the low shear environment that day. However, looking at the LMA data really helped with my decision.  Beginning at approximately 2104 UTC, source (image 2) and flash data (not shown) from the LMA showed the beginning of an enormous increase in total lightning activity with this cell.  Also, the increase was taking place directly over the city of Decatur.

Image 2.  KHTX 0.5 degree reflectivity overlaid with North Alabama LMA source density 2104-2134 UTC 11 August 2014

Image 2. KHTX 0.5 degree reflectivity overlaid with North Alabama LMA source density 2104-2134 UTC 10 August 2014

This trend in total lightning continued over the next several minutes.  With the knowledge that this cell was likely undergoing intensification and moisture-laden updrafts were strengthening directly over the city of Decatur, I decided to issue the flash flood warning, which was officially disseminated at 2115 UTC.  We received the first reports of flash flooding at 2145 UTC.  The next image below shows the location of the warning issuance.

KHTX 0.5 degree reflectivity with Flash Flood Warning polygon (green box) 2117 UTC 10 August 2014

KHTX 0.5 degree reflectivity with Flash Flood Warning polygon (green box) 2117 UTC 10 August 2014

The total lightning data in this case served as a very valuable severe weather application tool.  By providing the warning forecaster with knowledge of the location and likelihood of future deep convection, a flash flood warning was issued in a more timely and effective manner than would have been possible without these data.  When used in conjunction with other information and applied properly, these types of data can help to save lives and property.

Read Full Post »

In late April,  NASA SPoRT and the Albuquerque NWS met with scientists at New Mexico Tech to coordinate the integration of the Langmuir Lab lightning mapping array data into our operations.  According to Bill Rison, Paul Krehbiel, and Ron Thomas, New Mexico Tech’s Lightning Mapping Array (LMA) is a 3-dimensional total lightning location system. The system is patterned after the LDAR (Lightning Detection and Ranging) system developed at NASA’s Kennedy Space Center by Carl Lennon, Launa Maier and colleagues. The LMA measures the time of arrival of 60 MHz RF radiation from a lightning discharge at multiple stations, and locates the sources of the radiation to produce a three-dimensional map of total lightning activity.  The time-of-arrival technique for studying lightning was pioneered by Dave Proctor in South Africa.  The NASA SPoRT core project site details that operationally, total lightning data provide several advantages to forecasters.  First, total lightning data often give a 3-5 minute lead time ahead of the first cloud-to-ground lightning strike.  This improves lightning safety for the National Weather Service’s Terminal Aerodrome Forecasts (TAFs) and Airport Weather Warnings (AWWs).  This safety feature also can be used for incident support of special events. In addition, the total lightning data provides information about the spatial extent of lightning that is not available in the traditional cloud-to-ground data (http://weather.msfc.nasa.gov/sport/lma/).  This data may also be used to evaluate the degree of lightning activity within active wildfire smoke plumes.  The image below is an example of an LMA station at Briggsdale, Colorado taken by New Mexico Tech.  These stations are solar-powered and communications are operated via cell technology.

LMA stations at Briggsdale, Colorado.  Photo available from NM Tech.

Figure 1.  LMA station at Briggsdale, Colorado. Photo available from NM Tech.

After the first collaboration between NWS Albuquerque and NM Tech, forecaster Jennifer Palucki met with Harald Edens in June to install the xLMA and Live LMA software onto our office outreach laptop.  The LMA data that forecasters are evaluating at Albuquerque consists of source densities.  The imagery is available as a contour shaded product and describes the overall extent of sources from a particular thunderstorm or complex of thunderstorms.  The Live LMA software provides the actual point source information that make up the densities available in AWIPS.  The forecaster can actually see the structure of the point sources making up a flash on a 1-minute temporal resolution.  Figure 2 below shows the composite radar reflectivity valid at 0200 UTC July 23, 2014 for a complex of thunderstorms developing southward into the Albuquerque Metro Area.  The associated LMA source density product at 0202 UTC in Figure 3 illustrates the structure of the shaded point sources for the lightning flash.  The graphic shown in Figure 4 details the point sources available with the Live LMA software.  The source densities making up the flash during this 1-minute period stretched as far as 30-km from north to south and 20-km from east to west.  The altitude of the main source region was near 10-km.  The data available in AWIPS also allows the forecaster to slice and dice the data by elevation angle.  Forecasters at the Albuquerque NWS will continue evaluating the LMA products through summer 2014 to offer feedback to NASA SPoRT and NM Tech on its operational application.

 

Figure 2.  Mosaic Composite Reflectivity valid at 0200 UTC July 23, 2014.

Figure 2. Mosaic Composite Reflectivity valid at 0200 UTC July 23, 2014.

 

Figure 3.  Langmuir Lab LMA Source Density product valid at 0202 UTC July 23, 2014.

Figure 3. Langmuir Lab LMA Source Density product valid at 0202 UTC July 23, 2014.

Figure 4.  Live LMA 1-minute point sources valid at 0202 UTC July 23, 2014.

Figure 4. Live LMA 1-minute point sources valid at 0202 UTC July 23, 2014.

Read Full Post »

I wanted to point out a couple of operational advantages of total lightning data offered by current LMA networks scattered across parts of the CONUS, but also the advantages forthcoming with the GLM in the future GOES-R era.  While viewing the data today in conjunction with radar and NLDN data, two great examples were noticed.  First, let’s consider the situation where a cell becomes electrically active (intracloud lightning), but never produces a cloud-to-ground strike.  The first image below shows KHTX 0.5 reflectivity overlaid with LMA Flash Extent Density.

Image 1.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density valid 1735/1736 UTC 25 June 2014

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

 

Notice the small area of lightning detected by the North Alabama LMA in the central part of the image.  This cell never actually produced a ground strike.  So, using NLDN data alone, a forecaster would not have known that this cell was electrically active, and capable of producing lightning/thunder.  True, CG lightning was never observed by the NLDN network, but this is rather rare.

Next, let’s look at a situation where intra-cloud lightning preceded a CG strike as a cell was approaching an airport location.  Image 2 below, shows a cell that has just become electrically active as it was approaching the Tuscumbia/Muscle Shoals area around 1750 UTC.

Hi

Image 2.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1749/1750 UTC 25 June 2014

Notice in the image above that the first lightning detection by the LMA was during the 1749-1750 two-minute interval.  Now, we’ll take a look at an image just a little later, which shows the first incident of cloud to ground lightning as detected by the NLDN.

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

Image 3. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area), including CG strike (small cyan line) as indicated by NLDN  valid 1757/1758 UTC 25 June 2014

The image above (Image 3) shows the first CG strike, indicated by the small cyan line, which was about 7-8 minutes after the first intra-cloud flash.  Notice also that this cell was approaching the Muscle Shoals ASOS to the east, for which the HUN office has airport weather warning responsibilities.  These responsibilities include the issuance of warnings for CG lightning with 5 SM of the airport. So, not only do the total lightning data alert to the presence of lightning when a cell never even produces a CG strike, but intra-cloud flashes will often precede CG strikes.  In fact, research has shown this to be by about 5 to 10 minutes.  Forecasters here at the HUN WFO have been privileged to use these data in operations for over 10 years now.  These and future GLM data will be a boon to operations, allowing for earlier lead times in some warning and forecast situations.

 

Read Full Post »

Shortly after arriving for my evening shift today, I was called by a representative from an organization hosting an outdoor event in downtown Huntsville.  She was inquiring about the chances for shower or thunderstorm development into the early evening hours during the outdoor event (movie in the park night).  As I have grown quite accustomed to loading the GOES-R CI and total lightning products to be used for situational awareness, especially during the convective season, I referred to those to help with my assessment…in addition to radar data of course.  The image below shows GOES Visible channel imagery overlaid with GOES-R CI, total lightning data, and NLDN (the latter of which may be hard to see).  The location of Huntsville is labeled, and cloud motion is analyzed in the image.  Notice that the GOES-R CI product indicates generally low probabilities of convection in the area of clouds to the northwest (and upstream) of Huntsville.  The blue colors indicated CI probabilities of around 10-40%.

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

The next image shows lightning data overlaying the GOES Vis imagery…

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

 

Notice that only a few showers were located to the NW of Huntsville, but the GOES-R CI suggested further development was not likely and the total lightning (available from the North Alabama LMA) suggested these were only showers and thus not electrically active (I had looked over the previous ~20-30 mins).   Notice that lightning activity was relegated mainly to the South and East of the area.  This was a situation in which the GOES-R CI and total lightning data both served to provide a more complete assessment of the situation, allowing for a better forecast for one of our customers.

By the way…my forecast to her?  Well, based on the evidence from the observational imagery/data…I said very small chances for any shower activity, so let the show go on!  No showers ended up impacting the downtown area.

Read Full Post »

Total lightning is often useful for situational awareness heading into the heart of the Southeast convective season.  Typically, by late May, nearly all echoes on radar are producing lightning, and data from the North Alabama Lightning Mapping Array (NALMA) help to assess which of the cells require further attention.

This year was a little different.

On several days during the last week of May, a subtle warm layer and large dry layer aloft helped to cap the atmosphere, or at least limit vertical growth, across northern Alabama and southern middle Tennessee.  We observed scattered “thunderstorm” development with 50 dBZ echoes at 0.5 degree elevation–but higher radar tilts yielded very limited vertical structure with these cells (very low reflectivity beyond about 2.4 degrees).  While reviewing data from the NALMA, we realized that total lightning was giving us a clue–few, if any of these cells had any total lightning at all, as you’d expect with such shallow convection.  The stronger cells with greater vertical depth (warranting further interrogation) were the only ones producing any total lightning whatsoever.

So, in this situation, total lightning data still provided situational awareness–but in a slightly different way.  Instead of looking for the storms with the greatest flash rates or source densities (or changes thereof), we were looking for storms with ANY flashes or sources.  However, since then, we’ve been aboard the Mesoscale Convective System train, and we’ve returned to our traditional uses of NALMA data.)

KHTX Radar and North Alabama Lightning Mapping Array (NALMA) Data, valid 2140 UTC 28 May

KHTX Radar and North Alabama Lightning Mapping Array (NALMA) Flash Extent Density Data, valid 2140 UTC 28 May. The image indicates just a handful of cells producing any cloud-to-ground lightning or total lightning, despite appearances of 0.5-degree radar reflectivity.

Read Full Post »

Last year, NASA SPoRT submitted a proposal to collaborate with the Operations Proving Ground in Kansas City, Missouri.  The effort is focused on evaluating the Meteogram Moving Trace Tool developed by the Meteorological Development Laboratory (MDL) with support from NASA SPoRT to include total lightning.  One of the top requests from forecasters has been to create a time series plot of total lightning in real-time.  SPoRT first began to develop the total lightning tracking tool for use in AWIPS II to use with total lightning observations from the ground-based lightning mapping arrays.  The effort has now expanded to SPoRT coordinating with MDL’s meteogram tool for AWIPS II.  The advantage of the MDL tool is that it can create time series trends for multiple data sets beyond total lightning (e.g., radar, satellite, models).

This week, the Operations Proving Ground has brought together forecasters, developers, and trainers from multiple organizations to evaluate the use of this tool in several scenarios.  The opportunity for face-to-face discussions, training, and evaluation has been invaluable for the MDL and SPoRT developers to assess how the tool may be used in operations and to fix bugs that are found.  The face-to-face nature has allowed for bugs or requests for new features to be addressed throughout the day and to test the fixes the following day.  The week long evaluation facilitated by the Operations Proving Ground will lead to several improvements to the meteogram trace tool in preparation for its deployment in AWIPS II later this year.

Forecasters evaluating the meteogram trace tool at the Operations Proving Ground in Kansas City, Missouri.

Forecasters evaluating the meteogram trace tool at the Operations Proving Ground in Kansas City, Missouri.

Read Full Post »

SPoRT is planning an assessment of Total Lightning products with several existing and new collaborators from WFOs, CWSUs, and National Centers, ranging in locations from southern Florida to New Mexico and Colorado.  From May 15 – July 15, 2014 operational forecasters will evaluate the application of total lightning to support severe storm, public safety, and aviation weather warning responsibilities.  To prepare, SPoRT is holding tele-training sessions with collaborators during the week of April 21 and has provided users several training modules as well as a Total Lightning Quick Guide.  These can be found via SPoRT’s Training Page and on the NOAA LMS.  Experience with total lightning data will prepare users for the GOES-R GLM as well as provide feedback from operations to researchers regarding the types of products users desire.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level.  Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level. Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation. This image is from the NASA/SPoRT Quick Guide Training.

Read Full Post »

Older Posts »

Follow

Get every new post delivered to your Inbox.

Join 93 other followers