Southern California wildfires

May 15th, 2014 |
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

With an ongoing extreme to exceptional drought, hot temperatures (daily high temperatures along the coastal areas as high as 106º F at John Wayne Airport) combined with strong offshore Santa Ana winds (gusting as high as 87 mph at Big Black Mountain) conspired to create an environment favorable for wildfires across southern California and northern Baja California on 14 May 2014. McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) showed a number of smoke plumes streaming off the coast during the day. Note the brief appearance of a cluster of bright white pixels on the 18:00 UTC image, just north of the California/Baja California border — this a signal of sunlight being reflected off of large solar panel arrays in that area.

The side-by-side comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (below) showed that with a lowering sun angle at the end of the day, the smoke plumes began to become more difficult to identify on GOES-15 images (left); on the other hand, thanks to the benefit of a favorable forward scattering angle, the areal coverage of the smoke plumes stood out very well on GOES-13 images (right). The enhancements are the same on both sets of images.

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images

A 375-meter resolution Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using the SSEC RealEarth web map server (below) showed these smoke plumes with great clarity at 20:25 UTC or 1:25 PM local time.

Suomi NPP VIIRS true-color RGB image

Suomi NPP VIIRS true-color RGB image

As the larger fires continued to burn into the subsequent overnight hours, their hot thermal signature could be detected on AWIPS images of 4-km resolution GOES-15 3.9 µm shortwave IR channel data (below; click image to play animation).

GOES-15 3.9 µm shortwave IR images (click to play animation)

GOES-15 3.9 µm shortwave IR images (click to play animation)

A nighttime comparison of a 375-meter resolution Suomi NPP VIIRS 3.74 µm shortwave IR image with the corresponding 750-meter resolution VIIRS Day/Night Band image (below) showed a prominent fire hot spot (yellow to red pixels) on the shortwave IR image between San Diego (KSAN) and Camp Pendleton (KNFG), along with light gray signature of the narrow, fresh smoke plume that was being blown off the coast from that fire on the Day/Night Band image. At the time of the image, smoke was restricting the surface visibility to 5 miles at Camp Pendleton. Farther offshore, reflected moonlight was helping to show the location of smoke that had spread out over the adjacent waters of the Pacific Ocean from the previous day of burning.

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Finally, a demonstration of the importance of higher spatial resolution for accurate fire hot spot detection: on the comparison of 375-meter resolution Suomi NPP VIIRS 3.74 µm and 4-km resolution GOES-15 3.9 µm shortwave IR images (below), note that although the size of the fire “hot spot” was smaller on the VIIRS image, the highest IR brightness temperature was 54.5º C (compared to 48.0º C on the GOES-15 image). In addition, the two smaller fires burning in northern Baja California were not detected on the GOES-15 image.

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images

GOES-14 SRSOR: from morning fog/stratus to afternoon convection

May 13th, 2014 |
Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference

Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference “fog/stratus product” images

An AWIPS comparison of nighttime Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference “fog/stratus product” images (above) exhibited signals of fog and/or stratus forming in river valleys straddling the West Virginia and Virginia border on 13 May 2014.

The GOES-14 satellite continued to be operated in Super Rapid Scan Operations for GOES-R (SRSOR) mode, providing images at 1-minute intervals. Early morning 0.63 µm visible channel images (below; click image to play an MP4 animation; also available as a QuickTime movie) showed the narrow fingers of river valley fog/stratus, which began to burn off as heating and mixing increased during the morning hours. There was then a rapid transition to the formation of cumulus clouds across the region, some of which became organized areas of deep convection that produced hail and damaging winds (SPC storm reports).

GOES-14 0.63 µm visible channel images (click to play MP4 animation)

GOES-14 0.63 µm visible channel images (click to play MP4 animation)

A 3-panel comparison showing the difference between standard or routine 15-minute interval, 5-7 minute interval Rapid Scan Operations (RSO), and 1-minute interval SRSO GOES-14 0.63 µm visible channel images (below; click image to play an MP4 animation; also available as a very large Animated GIF) demonstrated the clear advantage of higher temporal resolution for monitoring the rate of dissipation of river valley fog/stratus features, as well as subsequent convective initiation and development.

GOES-14 0.63 µm visible channel images: Standard, RSO, and SRSOR scan strategies (click to play MP4 animation)

GOES-14 0.63 µm visible channel images: Standard, RSO, and SRSOR scan strategies (click to play MP4 animation)

Consecutive overpasses of the Suomi NPP satellite provided a look at the rapid rate of convective cloud development on VIIRS 0.64 µm visible channel images (below).

Suomi NPP VIIRS 0.64 µm visible channel images, with surface observations and frontal boundaries

Suomi NPP VIIRS 0.64 µm visible channel images, with surface observations and frontal boundaries

On a 18:59 UTC MODIS 11.0 µm IR channel image (below), the coldest cloud-top IR brightness temperature was -78º C near the West Virginia/Virginia border.

MODIS 11.0 µm IR channel image

MODIS 11.0 µm IR channel image

GOES-14 SRSOR: Automated Detection of Overshooting Tops

May 12th, 2014 |
Automated detection of Overshooting Tops (Blue symbols) from GOES-14 during SRSO Operations, 1400-1545 UTC on 12 May 2014

Automated detection of Overshooting Tops (blue symbols) from GOES-14 during SRSO Operations, 1400-1545 UTC on 12 May 2014

Detection of overshooting tops is important because the overshoot occurs with very strong updrafts that can punch through the tropopause. These strong updrafts can suspend large hydrometeors, and overshooting tops are associated with heavy rain and severe weather (principally hail and high winds, but also tornadoes). See this link for more information, and this link for other case studies. On Monday May 12th, eastward-moving morning convection over southern Wisconsin produced many overshooting tops as shown in the animation above (SPC Storm Reports are here). The overshooting tops were detected using an Automated Detection Algorithm developed for GOES-R by scientists at NASA Langley and UW-CIMSS. The steadiness of the OT production reflects the persistent strength of the thunderstorm complex. What did this storm look like in visible and infrared imagery from GOES-14, which was operating in SRSO mode? The animations below, from 1345 through 1545 UTC, shows GOES-14 in SRSO mode (left — 1-minute imagery), RSO mode (center — images every 7-15 minutes), and standard mode (right — images usually every 15 minutes) using visible images (top animation) and infrared images (bottom animation). Click on the images to see the animations as YouTube videos. The 1-minute imagery alone captures the very dynamic and rapidly-evolving cloud-top structures associated with the strong convection.

GOES14_1345_8May2014_Center_KMLI

GOES-14 Visible Imagery (0.62 µm) Animations from 12 May 2014. SRSO (Left), RSO (Center) and Standard (right) Scan Strategies are presented. Click to Animate

GOES14_1345_8May2014_Center_KMLI_IR

GOES-14 IR Imagery (10.7 µm) Animations from 12 May 2014. SRSO (Left), RSO (Center) and Standard (right) Scan Strategies are presented. Click to Animate

In both of the animations above, note how well the OTs observed in the satellite imagery match the auto-detected OTs. Auto-detection can miss detecting some tops, but the false alarm rate is low. Both image animations are also available as mp4 downloads (Visible, Infrared) and as YouTube videos (Visible and Infrared).

GOES-14 SRSOR: severe thunderstorms over the central Plains

May 11th, 2014 |
GOES-14 0.63 µm visible channel images (click to play animation)

GOES-14 0.63 µm visible channel images (click to play animation)

The GOES-14 satellite continued to be in Super Rapid Scan Operations for GOES-R (SRSOR) mode on 11 May 2014, capturing the development of thunderstorms along a dryline that stretched from the Texas Panhandle into far southwestern Kansas. As a southward-moving cold front intersected this dryline, McIDAS images of 1-minute interval GOES-14 0.63 µm visible channel data (above; click image to play animation; also available as an MP4 movie file) showed that the narrow line of storms later developed into large discrete supercell thunderstorms over Kansas, with widespread reports of tornadoes, large hail, and damaging winds (SPC storm reports).

Farther to the northeast, other large supercell thunderstorms could be seen growing over eastern Nebraska along a warm frontal boundary — these storms exhibited numerous signatures of vigorous overshooting tops. Near the end of the animation, winds gusted to 82 mph at Omaha, Nebraska at 00:51 UTC.

GOES-13 sounder Convective Available Potential Energy (CAPE) derived product imagery (click to play animation)

GOES-13 sounder Convective Available Potential Energy (CAPE) derived product imagery (click to play animation)

AWIPS images of GOES-13 sounder Convective Available Potential Energy or CAPE (above; click image to play animation) and Total Precipitable Water or TPW (below; click image to play animation) with surface frontal analyses revealed the sharp gradient of both instability and moisture across the dryline — just to the east of the dryline, CAPE values exceeded 4000 J per kg (darker purple color enhancement), while TPW values were generally in the 30-40 mm or 1.2-1.6 inch range (shades of yellow). In addition, GOES-13 sounder Lifted Index values were in the -8 to -10º C range across parts of Kansas into southeastern Nebraska prior to convective initiation.

GOES-13 sounder Total Precipitable Water (TPW) derived product imagery (click to play animation)

GOES-13 sounder Total Precipitable Water (TPW) derived product imagery (click to play animation)

A 19:36 UTC Suomi NPP VIIRS 11.45 µm IR channel image (below) showed the early stages of convective development along the dryline in far southwestern Kansas; the coldest cloud-top IR brightness temperature value at that time was -80º C, just west of Dodge City, Kansas KDDC (corresponding GOES-14 visible image).

Suomi NPP VIIRS 11.45 µm IR channel image, with METAR surface reports

Suomi NPP VIIRS 11.45 µm IR channel image, with METAR surface reports

A comparison of POES AVHRRR 12.0 µm IR channel images (below) showed the explosive convective growth over Kansas and Nebraska in the 3-hour period between 19:56 UTC and 22:53 UTC.

POES AVHRR 12.0 µm IR channel images

POES AVHRR 12.0 µm IR channel images

Additional details on this event can be found on the RAMMB GOES-R Proving Ground Blog.