The pre-tornadic RFD occlusion signature, which commonly occurred about five minutes prior to the tornado start time. This signature is an indication that the RFD occlusion has matured and occurs about two-thirds of the way through tornadogenesis.
Supercell Schematic with Violent Tornado over Farmland Including Tornadogenes...JohnChrisBroyles
This is the first supplementary graphic that came from work done for the Tornadogenesis papers of Part 1, Part 2 and Part 3. This hypothetical schematic shows a violent tornado, along with the different features of a supercell including the rear flank downdraft, forward flank downdraft, RFD boundary, FFD boundary, inflow, inflow channel, descending reflectivity core, occlusion downdraft, streamwise vorticity current, overshooting top and back anvil.
Supercell Schematic with Violent Tornado Near Trees and Lakes Including Torna...JohnChrisBroyles
This is the second supplementary graphic that came from work done for the Tornadogenesis papers of Part 1, Part 2 and Part 3. This hypothetical schematic shows a violent tornado, along with the different features of a supercell including the rear flank downdraft, forward flank downdraft, RFD boundary, FFD boundary, inflow, inflow channel, descending reflectivity core, occlusion downdraft, streamwise vorticity current, overshooting top and back anvil.
In order to put together the puzzle pieces of high-end tornadogenesis, we determined that a relatively large sample of supercells with high-end tornadoes would be needed. High-resolution radar would be analyzed for measuring as many characteristics of these supercells as possible. An archive
of WSR-88D high-resolution radar, at the Storm Prediction
Center, would be used to satisfy most requirements for data collection. Other data, including surface observations and soundings, would be used to analyze environmental information. It was determined that about a decade of radar data would be sufficient for the needs of this project. The period in the archive from May 22, 2008 to December 31, 2019 was examined. Before a tornado event was added to the study, seven criteria must be met. They are listed in this graphic.
4) Data Gathered For Seven Key Elements of Tornadogenesis.pdfJohnChrisBroyles
After analyzing the RFD occlusion, each storm was examined in detail to identify as many characteristics as possible for the 208 high-end tornadic supercells.
By the end of the project, the total amount of time to analyze the 208 supercells was about 1,500 hours. The following seven categories were considered the most important for each supercell, although much more data was collected.
5) Schematic of Supercell at Violent Tornado Stage (Adapted From Lemon 1979).pdfJohnChrisBroyles
Schematic of a supercell at the violent tornado stage (adapted from Lemon and Doswell 1979). The rear flank downdraft is red, forward flank downdraft is blue, updraft is brown and tornado is purple. The inflow channel is the narrow corridor (brown) north and west of the tornado. The inflection point (blue to red) is located north of the inflow channel. Streamlines are at 300 meters above ground level.
6) Salyersville, KY Tornadic Supercell on March 2, 2012 - FFD, RFD, Tornado, ...JohnChrisBroyles
The supercell that produced the EF3 at Salyersville, Kentucky on March 2, 2012. The RFD boundary is purple and occlusion downdraft is encircled in maroon just southeast of the tornado. The nose of the occlusion downdraft is circled in blue just east-northeast of the tornado. Davies-Jones 2006, Markowski 2002, Lee et al. 2011, 2012 explain more about the occlusion downdraft.
6a) RFD-FFD Boundary Locations For Six Well-organized HIgh-end Supercells.pdfJohnChrisBroyles
Estimated locations for the RFD boundary (blue) and FFD boundary (purple) for six notable high-end tornadic supercells. These supercells were at peak organization with the inflection point washed out.
Supercell Schematic with Violent Tornado over Farmland Including Tornadogenes...JohnChrisBroyles
This is the first supplementary graphic that came from work done for the Tornadogenesis papers of Part 1, Part 2 and Part 3. This hypothetical schematic shows a violent tornado, along with the different features of a supercell including the rear flank downdraft, forward flank downdraft, RFD boundary, FFD boundary, inflow, inflow channel, descending reflectivity core, occlusion downdraft, streamwise vorticity current, overshooting top and back anvil.
Supercell Schematic with Violent Tornado Near Trees and Lakes Including Torna...JohnChrisBroyles
This is the second supplementary graphic that came from work done for the Tornadogenesis papers of Part 1, Part 2 and Part 3. This hypothetical schematic shows a violent tornado, along with the different features of a supercell including the rear flank downdraft, forward flank downdraft, RFD boundary, FFD boundary, inflow, inflow channel, descending reflectivity core, occlusion downdraft, streamwise vorticity current, overshooting top and back anvil.
In order to put together the puzzle pieces of high-end tornadogenesis, we determined that a relatively large sample of supercells with high-end tornadoes would be needed. High-resolution radar would be analyzed for measuring as many characteristics of these supercells as possible. An archive
of WSR-88D high-resolution radar, at the Storm Prediction
Center, would be used to satisfy most requirements for data collection. Other data, including surface observations and soundings, would be used to analyze environmental information. It was determined that about a decade of radar data would be sufficient for the needs of this project. The period in the archive from May 22, 2008 to December 31, 2019 was examined. Before a tornado event was added to the study, seven criteria must be met. They are listed in this graphic.
4) Data Gathered For Seven Key Elements of Tornadogenesis.pdfJohnChrisBroyles
After analyzing the RFD occlusion, each storm was examined in detail to identify as many characteristics as possible for the 208 high-end tornadic supercells.
By the end of the project, the total amount of time to analyze the 208 supercells was about 1,500 hours. The following seven categories were considered the most important for each supercell, although much more data was collected.
5) Schematic of Supercell at Violent Tornado Stage (Adapted From Lemon 1979).pdfJohnChrisBroyles
Schematic of a supercell at the violent tornado stage (adapted from Lemon and Doswell 1979). The rear flank downdraft is red, forward flank downdraft is blue, updraft is brown and tornado is purple. The inflow channel is the narrow corridor (brown) north and west of the tornado. The inflection point (blue to red) is located north of the inflow channel. Streamlines are at 300 meters above ground level.
6) Salyersville, KY Tornadic Supercell on March 2, 2012 - FFD, RFD, Tornado, ...JohnChrisBroyles
The supercell that produced the EF3 at Salyersville, Kentucky on March 2, 2012. The RFD boundary is purple and occlusion downdraft is encircled in maroon just southeast of the tornado. The nose of the occlusion downdraft is circled in blue just east-northeast of the tornado. Davies-Jones 2006, Markowski 2002, Lee et al. 2011, 2012 explain more about the occlusion downdraft.
6a) RFD-FFD Boundary Locations For Six Well-organized HIgh-end Supercells.pdfJohnChrisBroyles
Estimated locations for the RFD boundary (blue) and FFD boundary (purple) for six notable high-end tornadic supercells. These supercells were at peak organization with the inflection point washed out.
Estimate of RFD boundary position (black) using the reflectivity image for Moore, Oklahoma on May 10, 2010. For every RFD boundary estimate, both reflectivity and base velocity were used together, but one was chosen as primary.
6c) Schematic of a Classic Rear Flank Downdraft.pdfJohnChrisBroyles
A schematic showing the rear flank downdraft of a tornadic supercell. The RFD occlusion or tornado is at the center of rotational convergence within the RFD. The curved dashed line is the outline of the hook echo. The white area is inflow to the updraft. Gray indicates relatively warm downdraft outflow. An unstable RFD is favorable for tornadogenesis. A couple hundred meters above the surface, winds generally turn south-southwest or southwesterly in the area south of the hook. Graphic obtained from Markowski et al. 2002.
6d) Base Velocity Estimate Overlaid on Reflectivity Base Velocity RFD Boundar...JohnChrisBroyles
An example showing the location of the RFD occlusion associated with the Moore, Oklahoma EF5 tornado on May 20, 2013. Base velocity (right) was used as primary to draw the RFD boundary. This location in black was super-imposed onto reflectivity (left). Even though base velocity was the primary indicator for the estimate, reflectivity also shows the RFD boundary well.
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...JohnChrisBroyles
The distribution of tornadoes relative to the RFD boundary near the tornado start time. 201 of the 208 tornado start locations (96.6%) were more than a quarter nautical mile to the west of the RFD boundary. Seven of the 208 cases (3.4%) were located near the RFD boundary, with three of the seven (1.4%) located on the RFD boundary itself.
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...JohnChrisBroyles
Contoured estimate of tornado start location relative to the position of the RFD boundary for 208 high-end tornadic supercells. The highest tornado incidence occurred 1.65 nautical miles west and 1.07 nautical miles south of the RFD boundary.
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...JohnChrisBroyles
Estimated tornado start locations relative to the RFD boundary for the first and second half of the dataset (left), and east and west of the Mississippi River (middle). The distribution of points is shown for the reflectivity and base velocity scans (right), depending upon which one was used as the primary indicator.
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...JohnChrisBroyles
A schematic showing the process of tornadogenesis involving an RFD surge beginning just over 13 minutes before the tornado start time. The RFD surge creates the inflow channel, as the RFD surge impinges on the inflow sector. This likely induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. The tornado forms after the RFD occlusion matures beneath the low-level mesocyclone, most often in the RFD’s northeast quadrant.
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...JohnChrisBroyles
RFD boundary surges northeastward toward the forward flank. As the RFD boundary impinges on the supercell’s inflow sector, an inflow channel is created. This induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. Also, restriction within the inflow channel causes the RFD occlusion to rapidly deepen as air is evacuated upward through the mesocyclone at a faster rate than can be replaced below. The tornado forms after the RFD occlusion matures beneath the low-level meso, most often in the RFD’s northeast quadrant. The descending reflectivity core (DRC) is in dark gray, which wraps around the RFD occlusion near the tornado start time (see Part 2).
An RFD surge was found for all 208 cases. The following method was used to identify the start and end points of the RFD surge, and to measure the RFD surge’s speed relative to the supercell’s speed.
First, the case was loaded and studied for about 15 minutes. The tornado start location was marked. Then, the RFD boundary location was estimated at high confidence times before and after the tornado start time. The examination paid close attention to the movement of precipitation behind the RFD boundary. Four questions listed below, were asked in order to determine when the RFD surge started and ended.
1) When did the precipitation gradient, just behind the RFD boundary, begin to accelerate relative to the storm’s movement?
2) When did the precipitation gradient, just behind the RFD boundary, obtain a bowed or curved appearance?
3) When did the precipitation gradient, just behind the RFD boundary, reach the forward flank?
4) When did the precipitation gradient, just behind the RFD boundary, decelerate relative to the storm’s movement?
Reflectivity data were used exclusively to determine when the RFD surge began and ended. The RFD surge was considered a time period when the leading edge of precipitation, just behind the RFD boundary, moved at a speed faster than the supercell’s speed. This involved an acceleration and then deceleration of the leading edge of precipitation.
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdfJohnChrisBroyles
RFD surge analysis for the Sibley, Iowa EF4 tornado on June 25, 2010. A cell merger ongoing in panel 1, instigates the RFD surge. The RFD surge starting point (panel 2) and ending point (panel 6), are marked. During the RFD surge, the reflectivity structure bulges and rapidly expands (panel 3 and 4). A bowing shape develops in panel 5. The RFD surge ends when it reaches the forward flank (panel 6).
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...JohnChrisBroyles
Sorted distribution of RFD surge storm relative speed for all 208 supercells. The average RFD surge storm relative speed ranged from just under two knots to just over 20 knots. The RFD’s primary role during tornadogenesis is to move the RFD boundary toward the FFD boundary, in order to create an inflow channel. A fast storm relative speed is not necessary to accomplish this task.
Type 1 RFD surge (at right), in which the low-level mesocyclone is initially above the RFD. During the RFD surge, the RFD boundary moves toward the supercell’s forward flank. The RFD occlusion develops and matures, which is followed by tornado formation in the RFD occlusion. The tornado most often forms in the northeast quadrant of the RFD.
For the Rozel, Kansas EF4 tornado on May 19, 2013 (at right), a prominent cell merger started the RFD surge. The mesocyclone was located to the west of the RFD boundary (panel 1). The cell merger caused an enhanced downdraft to move southeast, creating a long pendant (panel 2). The RFD occlusion developed at the pendant’s southeast end. The tornado formed as the RFD boundary surged northeastward toward the forward flank. This created a narrow inflow channel (panel 3 and 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdfJohnChrisBroyles
Type 2 RFD surge (at right), in which the RFD surge is initially ahead of the RFD boundary. The RFD boundary moves underneath the low-level mesocyclone and then away toward the forward flank. The RFD occlusion develops and matures after the low-level mesocyclone has been undercut. This is followed by tornado formation within the RFD occlusion.
For the Fackler, Alabama EF4 tornado on April 27, 2011 (to right), the RFD surge was instigated by cell mergers to the southwest of the RFD boundary. The RFD surge was very strong, with a 117 knot max outbound noted in panel two. The inflow channel became narrow as the RFD boundary pushed toward the forward flank (panel 3). Reflectors quickly disappear around the new tornado (panel 4), likely due to absorption by the rapidly strengthening tornado. 300 meter ground-relative flow is estimated based on cell movement and outflow.
Type 3 RFD surge (at right), in which the low-level mesocyclone is initially ahead of the RFD boundary. The RFD boundary surges toward the supercell’s forward flank, and to the center of the low-level mesocyclone. An RFD occlusion forms on the RFD boundary, underneath the low-level mesocyclone. The tornado develops within the RFD occlusion, on the RFD boundary, eventually moving southwestward into the RFD.
For the Ravanna, Kansas EF3 tornado on May 24, 2016 (at right), the mesocyclone was initially to the east of the RFD boundary. The RFD surge was instigated by outflow associated with cell mergers west of the boundary (panel 2). As the RFD surged toward the forward flank, the RFD occlusion developed on the RFD boundary (panel 2 and 3). Then, the tornado formed in the RFD occlusion (panel 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
16) Northward-moving Wave Disrupts RFD and EF4 Tornado near Goldsby, OK on Ma...JohnChrisBroyles
An example showing the Goldsby, Oklahoma EF4 tornado on May 24, 2011, in which the RFD was disrupted by a northward-moving wave. First, a left-moving supercell from north Texas approached the Goldsby supercell at near 65 nautical miles per hour. Outflow associated with the cell merger enhances vertical vorticity, causing the tornado to strengthen and reach peak intensity (panel 2). After the cell merger, a northward-moving wave associated with the left-mover, hit the Goldsby supercell’s RFD. The back edge of the RFD retreated northward (panels 4, 5 and 6), and eventually the backed flow associated with the northward-moving wave pushed the flanking line precipitation away from the mesocyclone (panels 7 and 8). This disrupted the RFD causing the tornado to dissipate.
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...JohnChrisBroyles
An example showing the Hillsboro, North Dakota EF3 tornadic supercell on August 27, 2016, in which there were two RFD surges. The first RFD surge did not produce a tornado, while the second did. The first RFD surge pushed southward and did not undercut the low-level mesocyclone. Veered flow at 700 mb and a lack of cell mergers were limiting factors, keeping the first RFD surge to the west of the low-level meso. The second RFD surge pushed eastward, undercutting the low-level meso. The second RFD surge was aided by cell outflow and cell mergers during the 15 minutes preceding the tornado. Veered low to mid-level flow, associated with northwest flow aloft, can contribute to a problem in which a supercell’s RFD surge takes place too far west. When this happens, it can be difficult for the RFD to undercut the low-level mesocyclone. This problem makes tornadogenesis more unlikely in summer.
18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...JohnChrisBroyles
During the cell merger analysis, all 208 cases were examined twice. The first examination pass identified cell mergers that occurred closer to the tornado start time. Within this first pass, clustering within the distribution was found at two time periods. The first was found to occur just a few minutes prior to the tornado start time. A second was found further out in time, generally between five and ten minutes prior to the tornado. During the first examination, it was observed that another cell merger was commonly occurring more than 10 minutes prior to the tornado start time. And this cell merger was often happening just before the start of the RFD surge. As a result, a second pass through the 208 cases was completed to identify cell mergers further out before the tornado start time. The cell merger that was identified during the second pass was called cell merger one, while the two cell mergers that were identified during the first pass were called cell merger two and three. After all the analysis was done, a cell merger two was found in more cases than a cell merger one. This is because a cell merger midway through the tornadogenesis process was slightly more common than a cell merger near the beginning of the tornadogenesis process. The first and second examinations were completely independent of each other, which revealed more detail concerning the distribution.
Using the three periods of cell merger clustering, average times prior to the tornado start time were computed. The 208 case average of those times are listed below, with the number of cases identified for each time, and the percent of occurrence listed in Table 1.
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...JohnChrisBroyles
The locations of cell merger one for 77 cell mergers relative to the pendant, that likely instigated RFD surges prior to high-end tornadogenesis from June 5, 2010 to March 15, 2012.
19a) Cell Merger Instigating RFD Surge for Canton, Oklahoma EF3 on May 24, 20...JohnChrisBroyles
The cell merger that instigated the RFD surge prior to the EF3 tornado at Canton, OK on May 24, 2011. In this case, the merging cell was less than 20 DBZ (upper left and upper middle). But the cell rapidly intensified just before the merger. We found some cases where a weak cell (<= 35 DBZ) was involved with a cell merger likely important to tornadogenesis.
Estimate of RFD boundary position (black) using the reflectivity image for Moore, Oklahoma on May 10, 2010. For every RFD boundary estimate, both reflectivity and base velocity were used together, but one was chosen as primary.
6c) Schematic of a Classic Rear Flank Downdraft.pdfJohnChrisBroyles
A schematic showing the rear flank downdraft of a tornadic supercell. The RFD occlusion or tornado is at the center of rotational convergence within the RFD. The curved dashed line is the outline of the hook echo. The white area is inflow to the updraft. Gray indicates relatively warm downdraft outflow. An unstable RFD is favorable for tornadogenesis. A couple hundred meters above the surface, winds generally turn south-southwest or southwesterly in the area south of the hook. Graphic obtained from Markowski et al. 2002.
6d) Base Velocity Estimate Overlaid on Reflectivity Base Velocity RFD Boundar...JohnChrisBroyles
An example showing the location of the RFD occlusion associated with the Moore, Oklahoma EF5 tornado on May 20, 2013. Base velocity (right) was used as primary to draw the RFD boundary. This location in black was super-imposed onto reflectivity (left). Even though base velocity was the primary indicator for the estimate, reflectivity also shows the RFD boundary well.
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...JohnChrisBroyles
The distribution of tornadoes relative to the RFD boundary near the tornado start time. 201 of the 208 tornado start locations (96.6%) were more than a quarter nautical mile to the west of the RFD boundary. Seven of the 208 cases (3.4%) were located near the RFD boundary, with three of the seven (1.4%) located on the RFD boundary itself.
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...JohnChrisBroyles
Contoured estimate of tornado start location relative to the position of the RFD boundary for 208 high-end tornadic supercells. The highest tornado incidence occurred 1.65 nautical miles west and 1.07 nautical miles south of the RFD boundary.
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...JohnChrisBroyles
Estimated tornado start locations relative to the RFD boundary for the first and second half of the dataset (left), and east and west of the Mississippi River (middle). The distribution of points is shown for the reflectivity and base velocity scans (right), depending upon which one was used as the primary indicator.
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...JohnChrisBroyles
A schematic showing the process of tornadogenesis involving an RFD surge beginning just over 13 minutes before the tornado start time. The RFD surge creates the inflow channel, as the RFD surge impinges on the inflow sector. This likely induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. The tornado forms after the RFD occlusion matures beneath the low-level mesocyclone, most often in the RFD’s northeast quadrant.
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...JohnChrisBroyles
RFD boundary surges northeastward toward the forward flank. As the RFD boundary impinges on the supercell’s inflow sector, an inflow channel is created. This induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. Also, restriction within the inflow channel causes the RFD occlusion to rapidly deepen as air is evacuated upward through the mesocyclone at a faster rate than can be replaced below. The tornado forms after the RFD occlusion matures beneath the low-level meso, most often in the RFD’s northeast quadrant. The descending reflectivity core (DRC) is in dark gray, which wraps around the RFD occlusion near the tornado start time (see Part 2).
An RFD surge was found for all 208 cases. The following method was used to identify the start and end points of the RFD surge, and to measure the RFD surge’s speed relative to the supercell’s speed.
First, the case was loaded and studied for about 15 minutes. The tornado start location was marked. Then, the RFD boundary location was estimated at high confidence times before and after the tornado start time. The examination paid close attention to the movement of precipitation behind the RFD boundary. Four questions listed below, were asked in order to determine when the RFD surge started and ended.
1) When did the precipitation gradient, just behind the RFD boundary, begin to accelerate relative to the storm’s movement?
2) When did the precipitation gradient, just behind the RFD boundary, obtain a bowed or curved appearance?
3) When did the precipitation gradient, just behind the RFD boundary, reach the forward flank?
4) When did the precipitation gradient, just behind the RFD boundary, decelerate relative to the storm’s movement?
Reflectivity data were used exclusively to determine when the RFD surge began and ended. The RFD surge was considered a time period when the leading edge of precipitation, just behind the RFD boundary, moved at a speed faster than the supercell’s speed. This involved an acceleration and then deceleration of the leading edge of precipitation.
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdfJohnChrisBroyles
RFD surge analysis for the Sibley, Iowa EF4 tornado on June 25, 2010. A cell merger ongoing in panel 1, instigates the RFD surge. The RFD surge starting point (panel 2) and ending point (panel 6), are marked. During the RFD surge, the reflectivity structure bulges and rapidly expands (panel 3 and 4). A bowing shape develops in panel 5. The RFD surge ends when it reaches the forward flank (panel 6).
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...JohnChrisBroyles
Sorted distribution of RFD surge storm relative speed for all 208 supercells. The average RFD surge storm relative speed ranged from just under two knots to just over 20 knots. The RFD’s primary role during tornadogenesis is to move the RFD boundary toward the FFD boundary, in order to create an inflow channel. A fast storm relative speed is not necessary to accomplish this task.
Type 1 RFD surge (at right), in which the low-level mesocyclone is initially above the RFD. During the RFD surge, the RFD boundary moves toward the supercell’s forward flank. The RFD occlusion develops and matures, which is followed by tornado formation in the RFD occlusion. The tornado most often forms in the northeast quadrant of the RFD.
For the Rozel, Kansas EF4 tornado on May 19, 2013 (at right), a prominent cell merger started the RFD surge. The mesocyclone was located to the west of the RFD boundary (panel 1). The cell merger caused an enhanced downdraft to move southeast, creating a long pendant (panel 2). The RFD occlusion developed at the pendant’s southeast end. The tornado formed as the RFD boundary surged northeastward toward the forward flank. This created a narrow inflow channel (panel 3 and 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdfJohnChrisBroyles
Type 2 RFD surge (at right), in which the RFD surge is initially ahead of the RFD boundary. The RFD boundary moves underneath the low-level mesocyclone and then away toward the forward flank. The RFD occlusion develops and matures after the low-level mesocyclone has been undercut. This is followed by tornado formation within the RFD occlusion.
For the Fackler, Alabama EF4 tornado on April 27, 2011 (to right), the RFD surge was instigated by cell mergers to the southwest of the RFD boundary. The RFD surge was very strong, with a 117 knot max outbound noted in panel two. The inflow channel became narrow as the RFD boundary pushed toward the forward flank (panel 3). Reflectors quickly disappear around the new tornado (panel 4), likely due to absorption by the rapidly strengthening tornado. 300 meter ground-relative flow is estimated based on cell movement and outflow.
Type 3 RFD surge (at right), in which the low-level mesocyclone is initially ahead of the RFD boundary. The RFD boundary surges toward the supercell’s forward flank, and to the center of the low-level mesocyclone. An RFD occlusion forms on the RFD boundary, underneath the low-level mesocyclone. The tornado develops within the RFD occlusion, on the RFD boundary, eventually moving southwestward into the RFD.
For the Ravanna, Kansas EF3 tornado on May 24, 2016 (at right), the mesocyclone was initially to the east of the RFD boundary. The RFD surge was instigated by outflow associated with cell mergers west of the boundary (panel 2). As the RFD surged toward the forward flank, the RFD occlusion developed on the RFD boundary (panel 2 and 3). Then, the tornado formed in the RFD occlusion (panel 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
16) Northward-moving Wave Disrupts RFD and EF4 Tornado near Goldsby, OK on Ma...JohnChrisBroyles
An example showing the Goldsby, Oklahoma EF4 tornado on May 24, 2011, in which the RFD was disrupted by a northward-moving wave. First, a left-moving supercell from north Texas approached the Goldsby supercell at near 65 nautical miles per hour. Outflow associated with the cell merger enhances vertical vorticity, causing the tornado to strengthen and reach peak intensity (panel 2). After the cell merger, a northward-moving wave associated with the left-mover, hit the Goldsby supercell’s RFD. The back edge of the RFD retreated northward (panels 4, 5 and 6), and eventually the backed flow associated with the northward-moving wave pushed the flanking line precipitation away from the mesocyclone (panels 7 and 8). This disrupted the RFD causing the tornado to dissipate.
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...JohnChrisBroyles
An example showing the Hillsboro, North Dakota EF3 tornadic supercell on August 27, 2016, in which there were two RFD surges. The first RFD surge did not produce a tornado, while the second did. The first RFD surge pushed southward and did not undercut the low-level mesocyclone. Veered flow at 700 mb and a lack of cell mergers were limiting factors, keeping the first RFD surge to the west of the low-level meso. The second RFD surge pushed eastward, undercutting the low-level meso. The second RFD surge was aided by cell outflow and cell mergers during the 15 minutes preceding the tornado. Veered low to mid-level flow, associated with northwest flow aloft, can contribute to a problem in which a supercell’s RFD surge takes place too far west. When this happens, it can be difficult for the RFD to undercut the low-level mesocyclone. This problem makes tornadogenesis more unlikely in summer.
18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...JohnChrisBroyles
During the cell merger analysis, all 208 cases were examined twice. The first examination pass identified cell mergers that occurred closer to the tornado start time. Within this first pass, clustering within the distribution was found at two time periods. The first was found to occur just a few minutes prior to the tornado start time. A second was found further out in time, generally between five and ten minutes prior to the tornado. During the first examination, it was observed that another cell merger was commonly occurring more than 10 minutes prior to the tornado start time. And this cell merger was often happening just before the start of the RFD surge. As a result, a second pass through the 208 cases was completed to identify cell mergers further out before the tornado start time. The cell merger that was identified during the second pass was called cell merger one, while the two cell mergers that were identified during the first pass were called cell merger two and three. After all the analysis was done, a cell merger two was found in more cases than a cell merger one. This is because a cell merger midway through the tornadogenesis process was slightly more common than a cell merger near the beginning of the tornadogenesis process. The first and second examinations were completely independent of each other, which revealed more detail concerning the distribution.
Using the three periods of cell merger clustering, average times prior to the tornado start time were computed. The 208 case average of those times are listed below, with the number of cases identified for each time, and the percent of occurrence listed in Table 1.
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...JohnChrisBroyles
The locations of cell merger one for 77 cell mergers relative to the pendant, that likely instigated RFD surges prior to high-end tornadogenesis from June 5, 2010 to March 15, 2012.
19a) Cell Merger Instigating RFD Surge for Canton, Oklahoma EF3 on May 24, 20...JohnChrisBroyles
The cell merger that instigated the RFD surge prior to the EF3 tornado at Canton, OK on May 24, 2011. In this case, the merging cell was less than 20 DBZ (upper left and upper middle). But the cell rapidly intensified just before the merger. We found some cases where a weak cell (<= 35 DBZ) was involved with a cell merger likely important to tornadogenesis.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
