Suomi NPP VIIRS 11.45 µm IR images

A sequence of three AWIPS images of 1-km resolution Suomi NPP VIIRS 11.45 µm IR data (above) showed the relatively compact cloud structure associated with Hurricane Henriette over the Eastern Pacific Ocean during the 07 August – 08 August 2013 period. Cloud-top IR brightness temperatures were as cold as -83 C (violet color enhancement) on the 08 August/11:12 UTC image. Henriette also exhibited a small eye on the 11:12 UTC and 22:26 UTC images on 08 August.

On a night-time comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band  and 11.45 µm IR images at 11:15 UTC (below), it is interesting to point out that the eye could still be faintly identified on the Day/Night Band image, even though there was only a minimal amount of illumination from airglow alone (the Moon was in its early Waxing Crescent phase, at only 1-3% of full, but was actually below the horizon for this particular image).

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

The compact eye of Henriette was well-defined on a comparison of VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 22:26 UTC (below). Henriette was near its maximum intensity of 90 knots around this time.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

A 1-km resolution GOES-15 0.63 µm visible channel image with an overlay of ASCAT surface scatterometer winds from the CIMSS Tropical Cyclones site (below) also showed a good presentation of the eye and the surface wind flow associated with the Henriette.

GOES-15 0.63 µm visible channel image with ASCAT surface scatterometer winds

An animation of GOES-15 10.7 µm IR channel images (below) revealed that the eye was becoming less obvious after about 00 UTC on 09 August.

GOES-15 10.7 µm IR channel images

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GOES-13 0.63 µm visible channel images (click image to play animation)

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the well-defined signature of a Mesoscale Convective Vortex (MCV) moving northeastward across Missouri and Illinois during the day on 08 August 2013.

A comparison of 1-km resolution MODIS 0.65 µm visible channel data at 16:16 and 19:35 UTC (below) showed that the MCV was approaching a frontal boundary over southern Illinois.

MODIS 0.64 µm visible channel images1-km resolution Suomi NPP VIIRS

1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 19:05 UTC (below) indicated that the clouds associated with the MCV were generally low-level clouds, exhibiting IR brightness temperatures in the +5 to +10º C range (lighter cyan color enhancement).

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

A comparison of 1-km resolution POES AVHRR 0.86 µm visible channel with the corresponding CLAVR-x Cloud Top Temperature (CTT), Cloud Top Height (CTH), and Cloud Type products (below) indicated the following characteristics of the MCV cloud signature over far southwestern Illinois at 19:44 UTC: CTT values in the -5 to -8 C range (light blue enhancement), CTH values in the 5-6 km range (orange to yellow enhancement), and a Cloud Type consisting of supercooled water droplets (green enhancement).

POES AVHRR visible channel, Cloud Top Temperature, Cloud Top Height, and Cloud Type products

GOES-13 Sounder DPI estimates of Total Precipitable Water (Click for animation)

Mesoscale Convective Complexes are most likely to persist in regions of abundant moisture and low shear. GOES Sounder data can give an indication of moisture in regions where clouds do not obscure the view. Clouds were abundant as the MCV formed in this case, but the animation of Total Precipitation Water (above) shows an atmosphere rich in moisture. Sounder estimate of Lifted Index, below, indicate instability. (Both animations stop at 1400 UTC, just as the MCV was seen emerging from the convective complex over southwest Missouri). The ‘blended’ Percent of Normal Total Precipitable Water product, here, shows values exceeding 100% of normal over the mid-Mississippi River Valley.

GOES-13 Sounder DPI estimates of Lifted Index (Click for animation)

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GOES-15 6.5 µm water vapor channel images (click image to play animation)

McIDAS images of 4-km resolution GOES-15 6.5 µm water vapor channel data (above; click image to play animation) showed the complex pattern of intensification of a storm over the western Gulf of Alaska on 06 August 2013. According to the NOAA NWS Ocean Prediction Center, this was the first cyclone to produce storm-force winds (greater than 47 knots) over the North Pacific Ocean since 21 June 2013.

AWIPS images of 1-km resolution Suomi NPP VIIRS 11.45 µm IR channel and 0.64 µm visible channel data with an overlay of the corresponding surface analysis (below) showed the cloud features associated with the storm system at 23:14 UTC.

Suomi NPP VIIRS 11.45 µm IR and 0.64 µm visible images (with surface analysis)

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GOES-13 0.63 µm visible channel images with overshooting top detection icons (click image to play animation)

AWIPS images of 1-km resolution GOES-13 0.63 µm visible channel images with automated overshooting top detection icons (above; click image to play animation) showed the development of a large mesoscale convective system across northwestern Kansas during the afternoon hours on 05 August 2013. Note that the surface air temperature at Goodland, Kansas (KGLD) dropped from 91º F at 19 UTC to 69º F at 20 UTC (with southeasterly winds gusting to 34 knots).

4-km resolution GOES-13 10.7 µm IR channel images with automated overshooting top detection icons (below; click image to play animation) revealed the formation of a very broad and well-defined “enhanced-V” storm top signature, with cloud-top IR brightness temperatures becoming as cold as -80º C at 23:15 UTC. Overshooting top detection began after 19:45 UTC, once GOES-13 cloud-top IR brightness temperatures became -71º C or colder.

GOES-13 10.7 µm IR channel images with overshooting top detection icons (click image to play animation)

During the early stages of convective development, GOES-13 10.7 µm IR images combined with 15-minute cloud top cooling rates (below) showed the development of significant cloud top cooling rates along the Colorado/Kansas border area at 18:15 UTC (prior to the formation of weak, brief landspout tornadoes just northeast of Goodland, Kansas during the 18:28-18:40 UTC period) — a maximum cloud top cooling rate of 35.3º C in 15 minutes was detected at 18:45 UTC.

GOES-13 10.7 µm IR channel images with Cloud Top Cooling Rates

A comparison of 1-km resolution Soumi NPP VIIRS 11.45 µm IR channel and 4.-km resolution GOES-13 10.7 µm images (below) demonstrated the ability of higher spatial resolution VIIRS data to detect much colder IR brightness temperatures associated with the more vigorous overshooting tops (-82º C on VIIRS, vs -71º C on GOES). In addition, a northwestward GOES image parallax shift was seen, due to to the large viewing angle of the GOES-13 satellite positioned at 75º W longitude. Shortly after the time of these images, this storm produced hail of 1.0 inch in diameter at 20:11, 20:21, and 20:54 UTC (SPC storm reports)

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR images

Comparisons of 1-km resolution POES AVHRR Cloud Top Temperature and Cloud Top Height products at 20:21 UTC (above) and 21:16 UTC (below) showed that the coldest cloud top temperatures (-85º C and -87º C, respectively) were seen in regions where the maximum cloud top height values were generally around 15 km. It is likely that the most vigorous overshooting tops associated with the coldest cloud top temperature values were as much as 2-3 km higher than this mean 15 km thunderstorm anvil cloud top height. Conversely, cloud top height values were around 13 km in the “warm wake” region immediately downwind of the coldest overshooting tops.

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