Feeds:
Posts
Comments

Archive for the ‘Uncategorized’ Category

Herein is an example of the Tracking Meteogram Tool, which was developed by NASA SPoRT, being used to track and create a time series plot of the total lightning associated with a thunderstorm at the National Weather Service forecast office in New Braunfels, TX (Austin/San Antonio – EWX). The information gleaned by the time series plot from the tracking meteogram tool assisted in the warning decision making process.

For full disclosure, I have a background in total lightning and its operational uses in severe weather operations. My Master’s thesis at the University of Alabama in Huntsville was on the utility of total lightning and the lightning jump to assist in the quasi-linear convective system (QLCS) tornado warning decision process. Also, as a CIMMS research associate at the NWS Warning Decision Training Division, I developed a four-part series on best practices for using total lightning to assist in storm interrogation for various convective modes and severe hazards. I have been an intern at the NWS forecast office in New Braunfels, TX since May 2016.

On the evening of November 1st, 2016, there were isolated thunderstorms in the forecast across the Interstate 35 corridor between San Antonio and Austin, but severe weather of any sort was not anticipated across our area. The Storm Prediction Center convective outlook highlighted the eastern half of our CWA for possible thunderstorms, but did not have even a marginal risk area outlined.

20161101-convective-outlook

Storm Prediction Center (SPC) Convective Outlook product issued at 1z on November 2nd, 2016 (8 pm CDT on November 1st, 2016).

On this particular shift, I was working the public service desk, while my colleague Nick Hampshire, a lead forecaster at EWX, was working the short-term forecast desk. Given my background in total lightning, I typically overlay the one minute 5 km by 5 km Earth Networks Total Lightning Detection Network (ENTLN) total lightning product on top of reflectivity for situational awareness purposes. Isolated showers and thunderstorms began initiating across the region around 6-7 pm that evening. These showers and storms were, as expected, fairly mundane and short lived, only producing light to moderate rainfall before the updraft was cut off and the storm dissipated. When the showers did manage to produce lightning, the lightning frequency was low and short lived.

Around 7:40 pm, a shower initiated east of Seguin, moving northward toward the cities of San Marcos and Austin. By the time it reached San Marcos around 8:20 pm, the shower began producing lightning. As the storm progressed northward toward the city of Austin, the total lightning flash rates continued to increase. To monitor the time series trend of the total flash rate, I used the Tracking Meteogram Tool and configured it to display the sum of the values, thereby plotting all the lightning being produced by the storm at any one time. I noticed a steady increase in the lightning flash rate that coincided with and even slightly preceded the strengthening of the storm as determined by radar signatures. A quick interrogation using radar and the standard environmental package from LAPS of the storm at around 8:51 pm showed 50+ dBZ echoes up to beyond the -30 degree Celsius level (~30,000 feet).

20161101 EWX Storm NASA post.png

4-panel display of reflectivity at different tilts from KEWX radar at 8:51 pm CDT on November 1st, 2016 (0151 UTC on November 2nd, 2016).

The total flash rate at this time was 46 flashes per minute, and the flash rate had increased from 34 flashes per minute at 8:47 pm to a local maximum of 47 flashes per minute at 8:52 pm. Given the radar signatures as well as the rapid increasing trend in total flash rate, Mr. Hampshire and I decided that a Significant Weather Advisory was warranted. In the text product, we mentioned pea to nickel sized hail associated with this storm. The SPS was issued around 8:52 pm. We received a few reports of pea sized hail in southwest Austin on social media shortly after 9 pm (2z).

total-lightning

1 minute ENTLN total lightning 5 km grid with tracking meteogram tool (left) and time series plot of total lightning for the storm of interest from 0133 UTC (8:33 pm CDT) to 0204 UTC (9:04 pm CDT) on November 2nd, 2016 (November 1st, 2016) 

 

20161101_nasa_storm

Radar loop from KEWX from 0054 UTC (7:54 pm CDT) to 0210 UTC (9:10 pm CDT) on November 2nd, 2016 (November 1st, 2016)

This case demonstrated the value of total lightning and the tracking meteogram tool. Given the forecast and the atmospheric environment, severe weather was not anticipated. However, it was the large, rapid increase in total lightning that initially prompted my attention to this storm and caused me to delve further into interrogating the severe potential. Had I not had the total lightning information available to me, the Significant Weather Advisory almost certainly would have come out later and perhaps not at all. Granted, this storm did not meet severe criteria, but not having any product issued for pea sized hail when hail of any size was not in the forecast would not have been an ideal situation, and the value added from the total lightning was still noteworthy.

lightning-tweet-nasa-post

Tweet posted from the NWS Austin/San Antonio twitter account shortly after the storm had passed through Austin, dropping pea sized hail.

 

Read Full Post »

November 19th has been eagerly anticipated by the meteorological community as it is the launch of the next-generation GOES-R satellite.  The satellite will carry a suite of space weather instruments as well as two Earth observing sensors.  The Advanced Baseline Imager (ABI) will provide three times more channels to view the Earth, four times greater spatial resolution, and 5 times faster coverage.  The ABI will provide new means to monitor atmospheric phenomena.  Additionally, GOES-R will carry the first ever lightning observation sensor on a geostationary platform; the Geostationary Lightning Mapper (GLM).  Numerous organizations, including NASA SPoRT, have been supporting the GOES-R Proving Ground for many years to aid the operational community in preparing for the new capabilities of GOES-R.

Specifically, NASA SPoRT has been formally involved with the Proving Ground since 2009, although much of our work prior to this point has provided relevant information with respect to GOES-R.  SPoRT has been primarily involved in two activities.  The first has been the assessment of and training for multi-spectral imagery, often called red-green-blue (RGB) composites.  The RGB composites are used to combine multiple single channels into a single image in order to help emphasize phenomena that forecasters wish to monitor.  This can range from air mass microphysics to atmospheric dust.  This work has leveraged work by Europe’s EUMETSAT organization who first developed several of these RGB composites for their Meteosat Second Generation satellite.  SPoRT has worked with NASA’s MODIS instruments from Aqua and Terra as well as the JPSS VIIRS instrument to create the respective RGBs from polar orbiting instruments.  These snapshot demonstrations provided forecasters local examples of RGB composites to allow them to investigate these products prior to GOES-R’s launch.  SPoRT has also coordinated with other product developers to help transition their early development work to National Weather Service forecasters.  This included the University of Alabama in Huntsville’s GOES-R convective initiation product and the NESDIS quantitative precipitation product.

image2

MODIS Dust RGB demonstrating a future capability of the GOES-R ABI. Dust (magenta) can be seen approaching Las Vegas, Nevada.

In additional to the ABI work, SPoRT has been integral to supporting total lightning (intra-cloud and cloud-to-ground) observations in operational applications.  This dates back to 2003 with the first transition of experimental ground-based lightning mapping arrays that evolved into the pseudo-geostationary lightning mapper (PGLM) product in 2009 to provide operational training for the GLM.  Since then, SPoRT has developed the GLM plug-in for the National Weather Service’s AWIPS system, has personnel serving as the National Weather Service liaison for the GLM, and have developed foundational training that is being provided to every forecaster in the National Weather Service.

tornado_alt_25apr10-11

Sample of the pseudo-geostationary lightning mapper demonstration product in AWIPS being used for training on the Geostationary Lightning Mapper.

SPoRT will continue to be actively engaged in GOES-R applications post launch.  This will take the form of developing an applications library, or short 3-5 focused case examples, for both the ABI RGBs and the GLM.  SPoRT will also participate in the formal applications training for RGBs and GLM that will be released to the National Weather Service.  Lastly, SPoRT will be leading an operational assessment of the GLM with National Weather Service forecasters and associated emergency managers.

goes_r_launch_19nov16

GOES-R launching on November 19, 2016!

Read Full Post »

…And GOES-R is off!

Today, the GOES-R satellite launched from Kennedy Space Center at approximately 642 EST!  As a forecaster, I am very excited about the flow of data and imagery that will be available to us in the near future.  Congratulation to all those who have invested so much time and energy into this project.

The GOES-R satellite launches aboard an Atlas-V Rocket at Kennedy Space Center, approx 642 pm EST.

The GOES-R satellite launches aboard an Atlas-V Rocket at Kennedy Space Center, approx 642 pm EST.

SPoRT would like to thank our collaborators who have worked with us to develop forecasting and other applications for this mission during recent years. And we look forward to continued collaborative projects in the future!

Read Full Post »

A number of fires have erupted in recent weeks due in part to the drought gripping parts of the Southeast U.S.  Especially hard hit are areas in and around the southern Appalachians, extending into central portions of Alabama and Georgia, where D3 (Extreme) to D4 (Exceptional) drought conditions exist, per the latest U.S. Drought Monitor (Image 1).

20161108_conus_trd

Image 1. U.S. Drought Monitor for 8 November 2016. Notice the large area of D3-D4 drought gripping parts of the Southeast.

Recently, the fires and some smoke were captured well in Shortwave IR (Image 2) and Day-Night Band imagery (Image 3) produced by the VIIRS instrument onboard the Suomi NPP satellite.

fires_swir_15nov2016

Image 2. Fires appear as small black dots in the Shortwave IR (~3.7 um) imagery taken at 0734 UTC 15 Nov 2016.

 

fires_dnbradiance_15nov2016

Image 3. In this Day-Night Band Radiance RGB, the fires (center of white circles) appear similar to city lights, however smoke plumes are evident with some of the stronger and heavier smoke-producing fires (red ovals), 0734 UTC 15 Nov 2016

Since boundary layer winds tend to shift direction at night with the loss of deep mixing, the Day-Night Band image can be used by forecasters to detect how smoke plumes change direction at night and may help with forecasts of smoke impacts.

Read Full Post »

On April 27, 2011, a severe weather outbreak occurred across the southeastern United States, resulting in 199 tornadoes across the region and over 300 fatalities (NWS 2011 Service Assessment).  Alabama was among the states hardest hit, with 68 tornadoes surveyed by the National Weather Service (NWS) Weather Forecast Offices (WFOs) in Huntsville, Birmingham, and Mobile, Alabama, and over 250 reported fatalities in the state. Huntsville, home to NASA’s Marshall Space Flight Center and the Short-term Prediction Research and Transition (SPoRT) Center, lost power along with most of Madison County after tornadoes severed major utility lines.  The power outage lasted well over a week in some areas. Once power was restored, SPoRT team members were able to provide satellite imagery to our partners in the National Weather Service to help clarify some of the high-intensity tornado damage tracks that occurred throughout the state. SPoRT provided pre- and post-event difference imagery at 250 m spatial resolution from the Moderate Resolution Imaging Spectroradiometer (MODIS) and 15 m false color composites from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). These surveys helped our NWS partners confirm their ground surveys, but also helped to correct the characteristics of several tracks (Molthan et al. 2011). Many of these products remain available through the SPoRT web page (link) and also through the USGS Earth Explorer portal (link).

CDnGGwIWIAA0MUP

The MODIS Band 1 difference image above shows some of the scars left behind by the April 27, 2011 tornado outbreak. Radar snapshots were taken from various times to identify the supercell thunderstorms associated with each track.  Reproduced from Molthan et al. 2011.

Follow-on studies examined the capability of various NASA sensors for detecting and measuring the length and width of scars visible when using the Normalized Difference Vegetation Index, or NDVI, a measurement of vegetation greenness and health commonly derived from multiple satellite imaging platforms.  SPoRT examined NDVI products from MODIS (250 m), Landsat-7 Enhanced Thematic Mapper Plus (ETM+, 30m) and ASTER (15 m) collected in May and June 2011. Possible tornado tracks were identified, mapped, and were then measured to compare against the official NWS damage surveys.  In general, many of the major tornadoes (defined here with maximum intensity EF-3 and greater) were at least partially visible at resolutions of 15-250 m, though weaker tornadoes or those that occurred in complex terrain were more difficult to detect using NDVI and a single snapshot in time. As tornadoes initiated and increased in intensity, or dissipated and decreased in intensity, some of their characteristics became more difficult to detect.  However, some weaker tornadoes were also apparent in Landsat-7 imagery (30 m) in well-vegetated areas.  A summary of the study is available as a publication in the National Weather Association’s Journal of Operational Meteorology. In 2013, SPoRT received support from NASA’s Applied Sciences: Disasters program to partner with the NWS and facilitate the delivery of satellite imagery to their Damage Assessment Toolkit (DAT).  The DAT is used by the NWS to obtain storm survey information while in the field. Satellite imagery from NASA, NOAA, and commercial sensors (acquired in collaboration with USGS and the Hazards Data Distribution System) helps to supplement the survey process by providing an additional perspective of suspected damage areas.

Many of the damage scars apparent from the April 27, 2011 outbreak exhibited signs of recovery and change in the years following the outbreak.  Other tornado events also brought additional vegetation damage and scarring to the region. With five years passing since the 27 April 2011 tornado outbreak, annual views of cloud-free imagery have been obtained from the Landsat missions, operated and managed as a collaboration between the USGS and NASA.  In the viewer linked below, SPoRT has collaborated with the USGS Earth Resources Observation Systems (EROS) Data Center to acquire 30 m true color and vegetation index information from Landsat 5, Landsat 7, and Landsat 8 during the late spring and summer months when local vegetation is at its greenest, allowing the greatest contrast between damaged and undamaged areas. Users can take a look at these images in a web viewer that allows toggling between different products and years, view some of the tornado tracks surveyed by the NWS following the April 27, 2011 event, and zoom into areas of interest to examine how some of the affected areas have evolved over time:

Tuscaloosa, AL

tusc_full_half_v2

The above animation shows the year before and years after the EF-4 tornado impacted the Tuscaloosa area. The tornado track has seen a significant recovery, but a scar still remains in 2015. In addition to seeing how the landscape as recovered from tornado, development in and around Tuscaloosa is also apparent.  Missing pixels in 2012 are due to an issue with the Landsat-7 imager.

Hackleburg-Phil Campbell

phill_full_half_v2

Similar to the Tuscaloosa animation, this animation shows the recovery of the EF-5 tornado that moved through Hackleburg and Phil Campbell, before tracking northeast across the Tennessee River.  Missing pixels in 2012 are due to an issue with the Landsat-7 imager.

Read Full Post »

On April 16th a fire was reported in the Shenandoah National Park in eastern Rockingham County, Virginia, situated roughly between the cities of Harrisonburg and Charlottesville. Estimated at about 500 acres (per latest news reports), the fire (named the Rocky Mountain Fire) is large enough and producing a sufficient amount of smoke to be seen in Geostationary satellite data from GOES-13 this afternoon (Image 1).

GOES_AfternoonLoop_18Apr2016

Image 1. GOES visible loop, 1646-1845 UTC, 18 April 2016.  A plume of smoke can be seen extending SSE of the fire in the central portion of the image.  The Charlottesville, VA observation site (in the path of the smoke) contains a report of smoke in the last couple of frames of the loop.

However, the fire can also be seen in Day-Night Band Imagery, produced by the VIIRS instrument aboard the Suomi-NPP satellite.  The first image below (image 2) shows no visible fire early on the morning of the 16th and the growth of the fire over the next couple of mornings in the next two images (images 3, 4).

DNBRadiance_0729Z16Apr2016_blog

Image 2.  VIIRS Day-Night Band Radiance RGB, 0729 UTC 16 April 2016. The circle shows the eventual location of the fire (although not evident yet in this image from the morning of April 16th).

 

DNBRadiance_0710Z17Apr2016_blog

Image 3. VIIRS Day-Night Band Radiance RGB, 0710 UTC 17 April 2016. The small white dot in the center of the circle likely represents the fire early on the morning of the 17th.

 

DNBRadiance_0651Z18Apr2016_blog

Image 4. VIIRS Day-Night Band Radiance RGB image, 0615 UTC 18 April 2016, showing the much larger “Rocky Mountain Fire” in portions of the Shenandoah Nat’l Park in eastern Rockingham County, VA.

 

Read Full Post »

On December 23, 2015, an unusual early winter season tornado outbreak struck much of the Tennessee Valley. Several tornadic supercell thunderstorms developed across northern Mississippi and western Tennessee in the afternoon hours, producing several large long-track tornadoes that unfortunately resulted in numerous fatalities and injuries. These same storms then moved rapidly east-northeastward at up to 70 mph across Middle Tennessee during the evening, spawning 4 tornadoes and causing 2 deaths and 7 injuries. Prior to this tornado outbreak, only 7 tornadoes had ever been recorded across Middle Tennessee since the 1800s, easily making this the largest and worst December tornado outbreak in Middle Tennessee history.

linden

OHX radar base reflectivity (left) & storm-relative velocity (right) at 623 pm CST on December 23, 2015 showing a supercell thunderstorm with an EF2 tornado in progress southeast of Linden, TN

NWS Nashville sent out three storm survey teams to evaluate all of the damage from these tornadoes on Christmas Eve and again on Christmas Day. Unfortunately, the affected areas were very rural and mostly inaccessible to the storm survey teams, with few roads available to evaluate damage indicators or determine beginning and end points. Thankfully, Landsat 8 imagery was available in the online Damage Survey Interface (DAT beta version) that depicted the swaths of blown down forests along the tornado paths that tracked through areas where the storm survey teams could not access. Landsat imagery allowed NWS Nashville personnel to extend two of the tornado paths by several more miles than originally estimated.

landsat

Landsat 8 panchromatic imagery (contrast enhanced) from March 22, 2016 showing the damage swath from an EF2 tornado that killed 2 people southeast of Linden, TN. The beginning point of this tornado was adjusted ~2 miles further southwest than originally estimated based on the satellite imagery.

Read Full Post »

Older Posts »