Hurricane Amanda in the East Pacific Ocean

May 23rd, 2014
GOES-15 10.7 µm IR channel images (click to play animation)

GOES-15 10.7 µm IR channel images (click to play animation)

Amanda became the first tropical storm of the 2014 East Pacific Basin season on 23 May 2014. 4-km resolution GOES-15 (GOES-West) 10.7 µm IR channel images from the CIMSS Tropical Cyclones site (above; click image to play animation) an increasing amount of organization to the convection associated with Amanda.

A similar trend was seen in 1-km resolution GOES-15 0.63 µm visible images (below; click image to play animation).

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

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

GOES-15 10.7 µm IR image with deep-layer wind shear and forecast storm track

GOES-15 10.7 µm IR image with deep-layer wind shear and forecast storm track

Given that Amanda was in an environment of low deep layer wind shear (above) and over warm sea surface temperatures (below), intensification to Category 1 hurricane intensity was forecast.

Sea Surface Temperature and forecast storm track

Sea Surface Temperature and forecast storm track

===== 24 May Update =====

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

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

McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) and 10.7 µm IR channel images (below; click image to play animation) showed that Amanda began to display an eye signature as it intensified to hurricane strength later in the day on 24 May. Amanda became the second earliest major hurricane on record in the East Pacific basin.

GOES-15 10.7 µm IR channel images (click to play animation)

GOES-15 10.7 µm IR channel images (click to play animation)

===== 25 May Update =====

CIMSS Automated Dvorak Technique plot

CIMSS Automated Dvorak Technique plot

In the early hours of 25 May UTC, Amanda underwent a period of rapid intensification, reaching Category 4 intensity around 12 UTC. This trend of rapid intensification is very evident on a plot of the CIMSS Automated Dvorak Technique (above). According to a National Hurricane Center discussion, Amanda became the strongest May hurricane on record over the East Pacific basin in the satellite era.

Hurricane Amanda exhibited a small eye, which was easily seen in 0.63 µm visible channel imagery (below; click image to play animation) from GOES-15 (GOES-West), GOES-14, and GOES-13 (GOES-East). The small-diameter eye was also apparent in DMSP SSMIS 85 GHz microwave imagery at 01:43 UTC and 15:00 UTC.

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible channel images [click to play animation]

A McIDAS-V nighttime comparison of  Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images (below) showed the eye of Amanda at 09:02 UTC on 25 May. A ring  of cold cloud-top IR  brightness temperatures surrounded the eye, with the coldest values on the northern, western, and southern portions. Since there was minimal illumination from the Moon (which was in the Waning Crescent phase, at about 6% of full), there was not a lot of cloud-top details seen in the Day/Night Band image.

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

===== 26 May Update =====

GOES-15 10.7 um IR channel images (click to play animation)

GOES-15 10.7 um IR channel images (click to play animation)

GOES-15 10.7 um IR channel images spanning the 24 May – 26 May period (above; click image to play animation; also available as an MP4 movie file) showed the development and evolution of the eye of Hurricane Amanda. Note that there were several time intervals when the IR cloud-top brightness temperature was colder than -80 C (violet color enhancement).

GOES-14 SRSOR: Thunderstorm development over Kentucky

May 22nd, 2014
GOES-13 DPI Convective Available Potential Energy (CAPE) on May 22, times as indicated (click to play animation)

GOES-13 DPI Convective Available Potential Energy (CAPE) on May 22, times as indicated (click to play animation)

GOES-14 operations in SRSOR mode deliver the ability to monitor convective development at very short time-scales. A good example of this occurred over the lower Ohio Valley/western Kentucky on May 22nd. The animation of GOES-13 Sounder Derived Product Imagery of CAPE (above) and of Lifted Index (1300 and 1700 UTC) showed considerable instability waiting to be released.

GOES-14 SRSOR animations can be used to monitor the evolving cumulus field in the search for the tower that will break the cap (Nashville, TN/Lincoln IL Soundings from 1200 UTC). The animation below shows visible imagery from 1800 UTC through 2011 UTC, at which time the convection has developed. Initial convection dissipates, but eventually develops along the Ohio River in western Kentucky (cumulus clouds continue to grow/dissipate over the Mississippi River valley throughout the animation).

GOES-14 Visible Imagery (0.62 µm) on May 22, times as indicated (click to play animation)

GOES-14 Visible Imagery (0.62 µm) on May 22, times as indicated (click to play animation)

By 1900 UTC, convective development over the lower Ohio Valley is vigorous enough that Cloud-Top Cooling algorithm from CIMSS (below) has flagged growing clouds, with values exceeding 20º C/15 minutes.

Instanteous Cloud-Top Cooling computed from GOES-13 at 1900 UTC 22 May 2014 (click to enlarge)

Instanteous Cloud-Top Cooling computed from GOES-13 at 1900 UTC 22 May 2014 (click to enlarge)

How does the NOAA/CIMSS ProbSevere model  then change with time as the convection intensifies? The 1904 and 1906 UTC ProbSevere products, toggled below, shows values increasing from 49% to 54% as Satellite Growth rates at 1900 UTC are incorporated at 1906 UTC. ProbSevere values then dropped (1912 UTC, 1922 UTC) as MRMS MESH decreased.

NOAA/CIMSS ProbSevere from 1904 and 1906 UTC on 22 May 2014 (click to enlarge)

NOAA/CIMSS ProbSevere from 1904 and 1906 UTC on 22 May 2014 (click to enlarge)

By 1936 UTC, ProbSevere has again increased above 50%, in two regions where MRMS has MESH sizes over 0.50″. MESH values are equivalent in the two regions, as are environmental values, but higher satellite predictors associated with the smaller eastern radar object drive higher ProbSevere values there.

NOAA/CIMSS ProbSevere from 1936 UTC on 22 May 2014 (click to enlarge)

NOAA/CIMSS ProbSevere from 1936 UTC on 22 May 2014 (click to enlarge)

The animation below shows the evolution of NOAA/CIMSS ProbSevere from 1948 UTC through 2000 UTC, with focus on a second cell that was warned. NOAA/CIMSS ProbSevere is designed to give an estimate of when severe weather might initially occur. Severe weather was not reported in Kentucky with these storms (link); however, observations of severe weather did occur as the storms moved near Nashville.

NOAA/CIMSS ProbSevere from 1948-2000 UTC on 22 May 2014 (click to animate)

NOAA/CIMSS ProbSevere from 1948-2000 UTC on 22 May 2014 (click to animate)

Related Hazardous Weather Testbed blog posts on this event can be found here, here, and here.

GOES-14 SRSOR: Storm-centered Loop of Supercell over the High Plains of Colorado

May 21st, 2014
GOES-14 0.62 µm visible channel images (click to play animation)

GOES-14 0.62 µm visible channel images (click to play animation)

An isolated Supercell Thunderstorm developed near Denver on 20 May and then moved eastward over the High Plains. The storm produced significant hail. GOES-14 was operating in SRSOR mode and viewing Colorado during the storm’s lifecycle, and the animation above (click image for a large animated gif file) is centered on the storm, highlighting the inflow into the storm from the southeast and the strong difluence around the updraft.

An earth-centered animation is available here. The animated gif clickable above is also available as a YouTube video, or downloadable in mp4 format here.

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