During the afternoon of May 20, 2013, the city of Moore, Oklahoma was struck by a large, violent tornado that caused widespread damage and numerous fatalities. Some aspects of the tornado and the resulting damage are observable from space. As with Superstorm Sandy and Hurricane Isaac, the VIIRS day-night band can be used to monitor changes in light resulting from a variety of features, such as moonlight reflection off of cloud tops or the surface, lightning from thunderstorms, fires, or human activity.
Author: Emily Berndt
Mount Pavlof, one of Alaska's most active volcanoes, has been erupting since last week. The plume has caused some disruption of flights and ash fallout in nearby communities. The Alaska Volcano Observatory has been closely monitoring it's activity (http://www.avo.alaska.edu/activity/Pavlof.php). The steam, ash, and gas plume is continually created as hot lava contacts snow and ice. The steam, ash, and gas plume has occasionally reached up to 20,000 ft and has been carried downwind as much as 100 km to the northeast, east, and southeast before dissipating.
The 05/15-05/16 TX Tornado Outbreak
The last two weeks have featured some rather remarkable weather that has ranged from morning lows around freezing, high temperatures soaring way above 100, and unfortunately, some deadly tornadoes. As part of the Satellite Proving Ground at the NOAA Center for Weather and Climate Prediction (NCWCP), we are currently demonstrating some products that will help with diagnosing and forecasting convection. The Overshooting Top Detection (OTD) is the first product that forecasters are evaluating and in the next few months, we will introduce a new lightning density product (see earlier post on the first spring MCC) that utilizes the Vaisala GLD-360 lightning feed to create a density plot of lightning strikes.
As many of you know, the evening of 05/15 brought some very severe weather to the Dallas-Fort Worth metro with at least one EF-4 and one EF-3 tornado in the southwest suburbs. These storms were part of a larger scale system that was rotating through Oklahoma and the two products mentioned above provided some very interesting and useful information about these storms.
The image above was taken approximately four minutes before the first report of this eventual EF-4 tornado touched down in Granbury, TX. The Overshooting Top Magnitude product adds more information to the overshooting top (OT) associated with this supercell thunderstorm than just the fact that it exists. The OT is approximately 9-11 degrees Celcius colder than the surrounding cirrus of the anvil. This could indicate the potential for large hail and in this case, a precursor to the tornado. Typically, the severe weather occurs between 5-30 minutes after the time of the OT detection.
This radar image compliments the satellite image above and is valid approximately 2 minutes before the tornado report was received. The two supercells highlighted are the tornado producing storms west-northwest of Fort Worth, TX. The southernmost supercell is responsible for the OT seen in the satellite image. Although I cannot say with absolute confidence that the OT Magnitude product would have given a strong indication of a potential EF-4 tornado, it did provide information on the most intense updrafts associated with these storms.
The new Vaisala GLD-360 Lightning Density product that has been developed as a coordinated effort with the Ocean Prediction Center (OPC), NESDIS STAR, and the Cooperative Institute for Climate and Satellites (CICS) did a great job of showing the highest concentration of cloud-to-ground (CG) lightning strikes associated with the thunderstorms about 9 minutes after the tornado report was received. Notice how the two lightning cores are as distinct in this image as the radar image above! This algorithm takes all of the individual CGs (positive and negative) and bins them into 2-minute, 15-minute, and 30-minute lightning density plots. The above image is a 30-minute accumulation of CGs, scaled. The purpose of this product is to simulate the capabilities of the upcoming Geostationary Lightning Mapper (GLM) that will be on GOES-R and is a compliment to the Pseudo-GLM product that is being developed and provided by NASA SPoRT and the University of Alabama-Huntsville.
Another interesting caveat of this severe weather event was this unusually strong OT Magnitude signal observed at 0232 UTC. The OT Magnitude exceeded the scale I created for the product with an OT that was greater than 18 C colder than the surrounding cirrus anvil! I’m sure there was significant hail in this area at this time!
*I created animations of the above mentioned products for this event which you can access at the bottom of this post. Just click on the images and the animation should run on a separate window.*
A Supercell Thunderstorm over the Gulf Stream?!
In the early morning hours of 05/16, another supercell formed nearly 1800 miles to the east-northeast over the Gulf Stream, east of the Mid-Atlantic. As a thunderstorm crossed the north wall of the Gulf Stream, it quickly intensified around 08 UTC into a supercell as it moved east over very warm waters. Although not a threat to anyone, the storm was located over shipping lanes and there was a ship located just northeast of the storm during maximum intensity. As you look at the images below, I want you to think about this question: If you observe similar structures and similar lightning patterns to the TX case, and have no radar, is it possible that this supercell was producing large hail, torrential rainfall, microbursts, or even a large waterspout?
The image above shows the OT Magnitude product indicating an OT that is approximately 16-17 C colder than the surrounding cirrus! This is very intense for a maritime thunderstorm and indicates this storm most likely exhibited a supercell structure. One of the OPC forecasters noted that this is the most intense thunderstorm he has witnessed over the Atlantic offshore zones in a long time.
Once again, the GLD-360 Lightning Density product shows a very intense core of CG lightning strikes co-located with the OT indicated above. It actually appears the lightning was more intense in this supercell than what was observed over TX a few hours earlier.
One of the OPC forecasters had this to say about using these product for his operations:
“I used the overshooting cooling product to help determine the intensity of the supercell, whether [it] was exhibiting a weakening or strengthening trend. In the afternoon I used the overshooting cooling product to support adding higher winds in thunderstorms to the offshore forecast in developing convection over this same offshore zone. The product also validated the very high lightning density data seen with these thunderstorms.”
Once again, I have created animations of this event below for your convenience. Think about the question above when you look at the animations and I encourage you to leave comments or questions as this could lead to interesting discussion. I think these two events provide an interesting comparison and it might be feasible to use these products for maritime convection to warn recreational boaters, military ships, and cargo vessels of potential severe maritime convection. The OPC and Tropical Analysis and Forecast Branch (TAFB) will continue to evaluate these products through the summer as part of the GOES-R Proving Ground activities.
Thank you for reading!
The Satellite Proving Ground at the NOAA Center for Weather and Climate Prediction (NCWCP) and the National Hurricane Center (NHC), has begun the next round of GOES-R proxy product demonstrations. The 2013 theme is on convective products that include the NSSL WRF and NAM simulated satellite imagery, the overshooting top detection, lightning density product, and convective initiation. The first wave of products will focus on the first two products, but I am testing and archiving the new lightning density product that has been developed by a collaborative effort with the Ocean Prediction Center (OPC), the Cooperative Institute for Climate and Satellites (CICS), and NESDIS STAR using the Vaisala GLD-360 lightning feed at the NCWCP.
After a cold end to winter and a very slow start to spring, thunderstorm season started with a bang the last few days. In particular, a cluster of thunderstorms developed over southeast TX on Tuesday night and proceeded to drop substantial hail (~3.5″ diameter) in Galveston County. The image above shows the lightning density product with the most intense convective cell that produced the large hail. Notice how the color scale does not go high enough to emphasize the intense amount of lightning (cloud-to-ground) with that cell.
The entire event is highlighted in the above animation (30-minute bins to match the 30-minute GOES-13 infrared imagery) as the clusters of thunderstorms over TX transfer energy to the Gulf of Mexico. As this new cluster of thunderstorms intensifies, it meets the qualifications to be designated a mesoscale convective complex (MCC) and even included a mid-level mesoscale convective vortex (MCV) that traveled just south of the northern Gulf coast. A wake low formed near the MS/AL coastlines and produced winds that exceeded 50-60 mph in spots. While this was going on, notice how intense (dense) the lightning activity is in the southern portion of the MCC as the complex continually evolves.
Finally, a renegade, elevated supercell thunderstorm formed over old Mexico and paralleled/straddled the Rio Grande River to a point just west of Brownsville. I created the above animation with a 2-minute increment to showcase the short-term evolution of this supercell. . .using lightning!!!
I expect to show off more lightning density cases as we move through severe weather season into hurricane season. One major advantage to having this product in operations at the NCWCP and NHC is that forecasters will be able to monitor the relative strength of convection over maritime and mountainous regions that lack convectional radar coverage. This product coupled with the OTD product (a separate post in the making) will continue to assist forecasters in the Proving Ground!
An update to the February 8-9, 2013, Blizzard from the NASA SPoRT Blog. The discussion includes the use of Suomi NPP Ozone Mapping and Profiler Suite and MODIS RGB Air Mass Imagery
As I’m sure many of you are aware, a meteor entered Earth’s atmosphere early this morning in southern Russia which has led to ~1000 injuries and widespread window and building damage due to the shockwave. This shockwave was caused by the meteor exploding upon entering the Earth’s lower atmosphere due to intense friction and the high velocity of the meteor. A couple of the RGB products that we use in the GOES-R Proving Ground captured this event near the northeast limb of the Meteosat-10 satellite.
The SEVIRI RGB Air Mass product captured the meteor explosion in the 0315 UTC image (highlighted with the white circle). Notice the streak over southern Russia as a whitish line. This color is usually seen when there is arctic air, for instance over Greenland. This would suggest that as hot as the explosion was, the smoke and any condensed moisture was very cold at a high altitude. An animation is provided in the second image, just click on the image.
The SEVIRI RGB Dust product also captured this meteor impact, but the signal was different due to the difference in infrared bands that are used to create the product. In this first image, the white circle highlights the meteor streak as a red line. This is because the signal was cold, similar to strong thunderstorms (cumulonimbus clouds) or ice clouds. The animation below this shows how the streak signal last longer in this product than in the Air Mass product.
This shows us an unusual and different approach to using RGB products in a non-meteorological setting. Thanks for reading!
The latter half of January featured a stormy North Atlantic with a number of cyclones that produced hurricane force winds. An animation of RGB air mass imagery (below) from January 18-26 shows the active pattern. The most impressive storm rapidly developed and the central pressure lowered to 930 mb approximately 1200 UTC January 26th, see surface map below. Considering the strength of the storm, the OPC 96-hour forecast was exceptionally accurate. The GFS and European models were forecasting winds greater than 80 knots (90 mph) and wave heights over 55 feet. The ASCAT passes largely missed the strongest winds (highest observed were 60 knots (70 mph), but there were reports of waves near the Portugal coast between 90 and 100 feet, nearshore! On the RGB Air Mass imagery animation, you can see the red and orange shaded colors drawn into the center of the cyclone. This area represents warm, dry stratospheric air associated with high potential vorticity near a jet streak. As this stratospheric air is drawn into the storm it can be transported downward to produce high winds at the surface.
One interesting note is the storm’s impact on the North Atlantic Oscillation (NAO). The NAO is used to characterize winter temperature and precipitation patterns in the North Atlantic through height/pressure anomalies over Greenland and the central North Atlantic. The index combines parts of the East-Atlantic and West Atlantic patterns identified by Wallace and Gutzler (1981). A positive NAO is indicative of lower heights in the North Atlantic and higher heights in the Central North Atlantic. The top panel on the image below shows the Observed daily NAO indices for the past 120 days. Notice how the NAO index has trended positive since January 24th, and became more strongly positive with time. The intense cyclone reinforced the slightly positive NAO as the lower heights and colder temperatures infiltrated Greenland and the North Atlantic. So why do we care about an active North Atlantic and positive NAO? As the NAO trends toward the positive phase, it could mean above average temperatures for the Eastern US and Northern Europe. The CPC 6-10 day and 8-14 day temperature and precipitation outlooks both predict above average temperature and precipitation for the Eastern US, see http://www.cpc.ncep.noaa.gov/.
A special thank you to Dr. Emily Berndt (post-doc at NASA SPoRT) for providing much of the material for this post and to the OPC Facebook team for the surface comparison image.
Thanks for reading!