Carr Fire
July 27th, 2018 by Jorel TorresIt has been a very active fire season in California. Another fire burning in the state, is the Carr Fire, located in Shasta County, just west of Redding, CA. Over 44,000+ acres have burned with only 3% containment as of 27 July 2018. According to sources, the mechanical failure of a vehicle is presumed to be the cause of the fire.
The Carr Fire was observed by the Near-Constant Contrast (NCC) product, derived from the Day/Night Band (DNB, 0.7um) sensor, apart of the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on-board the Suomi-National Polar-orbiting Partnership (S-NPP) satellite. The NCC produces ‘nighttime visible’ satellite imagery, and in this case (see NCC image below, at 0909Z, 27 July 2018), observes emitted city lights, emitted lights from the fires, reflected light from fog and low stratus clouds, along with the reflected light from nearby smoke.
Additionally, a comparison between NCC (bottom-left) and the GOES-16 infrared imagery (3.9um, bottom-right) at ~1050Z, 27 July 2018, is seen below. The NCC highlights the emitted lights from cities and towns, emitted lights from the Carr Fire, along with atmospheric features described earlier.
However, how do users clearly discriminate between emitted lights produced from fire to emitted lights exhibited by cities and towns? This is where GOES-16 3.9um imagery complements NCC. GOES-16 3.9um can be used to identify ‘fire hotspots’, that emanate high brightness temperature values, near the surface. In the infrared imagery, the ‘fire hotspots’ are clearly discerned, and are seen embedded within the black ellipse.
For more updates on the Carr Fire, click on the following link.
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Typhoon Jongdari
July 26th, 2018 by Jorel TorresBy late weekend, Typhoon Jongdari is forecasted to make landfall along Japan’s southern islands. Typhoon Jongdari is expected to strengthen, with an initial northeast storm motion, then elicit a circuitous path, moving westward, within the next 24-hours. The typhoon is anticipated to be at Category 1 hurricane strength (74-95 miles per hour), just before landfall. Heavy rain, strong winds, storm surge and flooding is to be expected.
This morning, Near-Constant Contrast (NCC) data, derived from the Suomi National Polar-orbiting Partnership (S-NPP) satellite observed Typhoon Jongdari at 1617Z, 26 July 2018 (0117, 27 July 2018, local time in Japan). The NCC, a derived product of the Day/Night Band (DNB) utilizes a sun/moon reflectance model to illuminate and sense emitted (i.e. city lights) and reflected (i.e. clouds) light sources during the nighttime.
The first NCC image (below) is a large scale view of the storm, while the second NCC image, is a small scale perspective of Typhoon Jongdari, highlighting the convective cloud tops (areas of heavy precipitation), near and around Jongdari’s circulation. Notice the magnitude of Typhoon Jongdari, and how close the typhoon is to the country of Japan. Emitted lights from Japan, and ambient cloud cover can be seen in the following images.
Large Scale
Small Scale
For the latest updates on Typhoon Jongdari, click on the following link.
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Ferguson Fire, CA
July 20th, 2018 by Jorel TorresThe Ferguson Fire erupted last Friday, 13 July 2018 at ~2030 local time. The fire is near Yosemite National Park, burned 22,000+ acres, and is only 7% contained, as of 20 July 2018. The cause of the fire is unknown and under investigation, while several communities have been evacuated from the area, and one fatality has been confirmed. Expected 3-5 day forecast for Central California is to be hot, hazy, with light and variable winds, that could potentially enhance the fire.
The Suomi National Polar-orbiting Partnership (S-NPP) satellite and the Geostationary Operational Environmental Satellite – 16 (GOES-16) observed the wildfire event, identifying the areal extent of the fire (emitted lights from the fire, seen via Near-Constant Contrast (NCC)) and associated fire ‘hotspots’ (GOES-16 3.9um). NCC and GOES-16 3.9um observed the Ferguson Fire at 0941Z (0241 local time), 20 July 2018.
NCC
Note the areal extent of the fire (embedded in the white ellipse) but additionally, emitted lights from nearby towns/cities can be seen via NCC.
To discern emitted lights that are from cities/towns to emitted lights from the fire, that is where GOES-16 3.9um complements NCC. GOES-16 3.9um, not only shows the fire location, but indicates the relatively cool brightness temperatures of the fire. See the brightness temperature (degrees Celsius), sampled, in the following satellite image.
GOES-16 3.9um
As the day progressed through late morning, fire temperatures increased significantly, due to increasingly hot, ambient temperatures and dry conditions. See the brightness temperature (degrees Celsius), sampled, in the following satellite image.
GOES-16 3.9um of Ferguson Fire at 1622Z (0922 local time), 20 July 2018. 
For more updates on the Ferguson Fire, click the following link.
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Pawnee Fire, CA
June 26th, 2018 by Jorel TorresIn the late afternoon on 23 June 2018, the Pawnee Fire in Northern California initiated and has now spread to 11,000+ acres. As of this morning 26 June 2018, the fire is located a few miles north of Clearlake, CA and has forced thousands of people to evacuate the area, where 20+ structures have been destroyed. The fire is currently 5% contained and the cause of the fire is still under investigation. Additionally, Northern California is currently experiencing ‘D-0’ drought conditions (abnormally dry conditions), according to the US Drought Monitor. The latest California drought conditions can be seen below.
Polar-orbiting satellite imagery observed the Pawnee Fire, along with the Lions Fire, nearby. One of the polar-orbiting satellite products, the Near-Constant Contrast (NCC), illuminates atmospheric features and senses emitted and reflected light sources during the nighttime. The following two NCC images show the ‘Morning Before’ and the ‘Morning After’ the Pawnee Fire started. The first NCC image (shown below) is taken at 0948Z (0248 local time), 23 June 2018. Notice the emitted city lights along Northern California, and no discernible fires in the area.
Morning Before – 23 June 2018
The second NCC image is taken at 0928Z (0228 local time), 24 June 2018. Notice the emitted lights produced from the two fires, seen within the two red circles. The Pawnee Fire is located in the top-left part of the image, and the Lions Fire in the bottom-right part of the image. Areal extent of both fires can be inferred from the satellite imagery, wherein thousands of acres have been burned. Also notice the uniform, fog and low stratus clouds, along the California coast.
Morning After – 24 June 2018
The 3-5 day forecast for the area, is projected to be in the upper 80’s (air temperature), sunny, dry, with light to moderate winds, that could amplify the fire even further. More details on the Pawnee Fire can be accessed via the following link and via Inciweb website.
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GOES-16 Split Window Difference Precursor to Convective Initiation
June 12th, 2018 by Dan BikosThere are two GOES-16 products related to convective activity. One is related to convective initiation; that is, this product will identify new cumulus that will further develop into mature thunderstorms. The second product identifies which mature thunderstorms have a high probability of producing severe weather. However, both GOES-16 products require active cumulus development. We seek to fill a void by providing a product that aids in the identification of future convective initiation in a clear sky scene. The purpose of this blog entry has 3 parts: 1) training, 2) two case studies, and 3) both color and gray-scale enhancement tables, applied to GOES-16 split window difference product.
A common goal of the both VISIT and SHyMet programs is to provide training to WFO, CWSU, and National Center forecasters. One way to provide training information to these users is through the use of readily accessible information that appears on this training blog. Previous blog training has focused on a variety of weather events; for example, winter weather, severe convection, tropical cyclones, aviation applications, and fire weather. In this blog entry two case studies that focus on precursors to convective initiation are discussed.
Although there has been somewhat of a lack of severe convection during spring of 2018, two cases have been identified to highlight the use of the split window difference product in the identification of precursors to convective initiation. They occurred on 15 and 29 May 2018 both in the Texas panhandle. On 15 May 2018 a slowly moving outflow from previous convection interacted with a low-level convergence boundary. In contrast, 29 May 2018 focuses on a dryline / cold front interaction event. As a reminder to the reader, the split window difference product aids in the identification of where cumulus may first develop within clear sky conditions. We urge the reader to exercise caution in that the use of this product is inappropriate for the identification of severe thunderstorms. One significant challenge is the development of a satellite enhancement table to highlight features of interest.
To begin with, the 15 May 2018 case will be used to illustrate modification of satellite enhancement tables. Even though a default color table exists for the split window difference product in AWIPS, we will demonstrate the usefulness of modifying satellite enhancement tables. An example image is taken at 1607 UTC, see image below:
A black oval is used to denote the clear sky precursor signature in both images on the left side. Within the gray-scale image, two arrows are used to denote the western and eastern edges of the signature. An oval was not used due to variations in visual perception, i.e., the precursor may not be apparent to some people if a black oval is used. Note in particular the lack of clouds within the oval in the visible image located in the top right panel.
To illustrate the utility of the 3 types of enhancements, the following GOES-16 animation is provided:
Top Left panel: Split Window Difference (10.3 – 12.3 micron) product in the range of -10 to +10 Celsius with the CIRA SLIDER enhancement (http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=conus&x=5000&y=5000&z=0&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=35&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider) overlaid with METARs.
Top right: Visible (0.64 micron)
Bottom left: Split Window Difference (10.3 – 12.3 micron) product with the default AWIPS color table, in the range of -15 to +15 Celsius.
Bottom right: Split Window Difference (10.3 – 12.3 micron) product with the gray-scale linear enhancement on AWIPS in the range from -10 to 10 Celsius.
The point of the animation is to provide the reader an opportunity to view different enhancements at once. Of importance are the variations in both the ranges and colors / gray-scale used for each split difference produce panel. To some, the top left may be preferred while others may prefer the bottom right and yet some will show preference to the bottom left. One key aspect to keep in mind is that the precursor signature corresponds to clear skies in the visible imagery prior to approximately 1700 UTC.
For completeness, a brief physical explanation of the split window difference signature now follows. Water vapor in the boundary layer is an absorbing gas to energy at 10.3 and 12.3 microns that is emitted from the earth’s surface. Water vapor absorbs more energy at 12.3 compared to 10.3 microns; therefore, when the temperature decreases with height the brightness temperature at 12.3 microns is less than the brightness temperature at 10.3 microns, hence the difference is positive. Along convergence zones, water vapor is transported upwards, making the moist air relatively deeper compared to its surroundings and thus amplifying the channel difference.
Another example of a gray-scale enhancement highlights the usefulness of modifying the range of the split window difference product. For clarity, the gray-scale loop on the bottom right in the previous animation is repeated along with a modified range (from 1.7 to 10 Celsius):
This example illustrates the use of changing the scale from -10 to 10 Celsius (top) to 1.7 to 10 Celsius (bottom) while preserving the same enhancement table (linear). One consequence of decreasing the range of 1.7 to 10 C is to increase the contrast. The motivation is to provide the reader with another example of how the data can be displayed. That is, some may prefer the top loop while others may prefer the bottom.
Finally, a larger version of the upper left loop of the 4 panel animation above is shown here as another way to view the data:
The 29 May 2018 case focuses on convective initiation in the northeast Texas panhandle as shown in this animation:
Top Left panel: Split Window Difference (10.3 – 12.3 micron) product in the range of -10 to +10 Celsius with the CIRA SLIDER enhancement (http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=conus&x=5000&y=5000&z=0&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=35&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider) overlaid with METARs.
Top right: Visible (0.64 micron)
Bottom left: Same as top left, except the range has been changed to -5.1 to +10 Celsius.
Bottom right: Split Window Difference (10.3 – 12.3 micron) product with the gray-scale linear enhancement on AWIPS, except the range has been modified to 0.9 to 10 Celsius.
In general, upper level cirrus clouds are seen stream from west to east from eastern New Mexico over the Texas panhandle into southwest Oklahoma. The moisture gradient associated with the dryline is shown with red colors on the moist side and green/yellow/blue colors on the dry side (note the eastward movement of the moisture gradient just south of the cirrus in the southern Texas panhandle). Followed by convective initiation in the northeast Texas panhandle around 2000 UTC.
The technique for modifying the range on the bottom 2 panels in AWIPS is as follows:
Hold down the right mouse button on the split window difference product, choose colormap.
A GUI will appear titled “Set Color Table Range”, scroll the Min bar until the contrast on the imagery is to your preference.
The above technique applies in general in modifying the enhancement and/or data range.
Further information:
FDTD GOES-16 Applications webinar on the Split Window Difference
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