VIIRS « CIMSS Satellite Blog

Tornado at Denver International Airport

June 18th, 2013

Suomi NPP VIIRS 0.64 um visible image and 11.45 um IR channel image (with overlay of METAR surface reports)

A tornado touched down just east of the Denver International Airport concourses at 20:21 UTC on 18 June 2013, producing a peak wind gust of 97 mph (before the wind instrumentation was damaged). AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 20:03 UTC (above) showed the storm about 20 minutes before it produced the tornado. The minimum cloud-top IR brightness temperature was -68º C (darker red color enhancement), which was significantly colder that the tropopause temperature of -56º C on the 12 UTC Denver rawinsonde data.

The corresponding Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image (viewed using the SSEC Web Map Server) is shown below.

Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image

The series of METAR surface reports from Denver (KDEN) during the period from 20:20 to 20:37 UTC:

KDEN 182037Z 09026KT 9SM -TSRA FEW050 BKN080CB BKN180 24/04 A3002 RMK FUNNEL CLOUD B18 FUNNEL CLOUD E20 TORNADO B21 TORNADO E36 AO2 LTG DSNT NE-S RAB03 TORNADO 2 SE MOV N P0005
KDEN 182032Z 09026KT 7SM +FC -TSRA FEW050 BKN080CB BKN180 22/08 A3001 RMK FUNNEL CLOUD B18 FUNNEL CLOUD E20 TORNADO B21 AO2 LTG DSNT NE-S RAB03 TORNADO 2 SE MOV N P0005
KDEN 182022Z 06021G28KT 5SM +FC TSRA FEW050 BKN080CB BKN180 21/07 A3002 RMK FUNNEL CLOUD B18 FUNNEL CLOUD E20 TORNADO B21 AO2 PK WND 07028/2020 LTG DSNT E-S RAB03 OCNL LTGICCG VC E TS OHD MOV E VIRGA SW P0005
KDEN 182021Z 06022G28KT 5SM +FC TSRA FEW050 BKN080CB BKN180 21/06 A3003 RMK FUNNEL CLOUD B18 FUNNEL CLOUD E20 TORNADO B21 AO2 PK WND 07028/2020 LTG DSNT E-S RAB03 OCNL LTGICCG VC E TS OHD MOV E VIRGA SW P0005
KDEN 182020Z 07020G28KT 5SM FC +TSRA FEW050 BKN080CB BKN180 21/07 A3003 RMK FUNNEL CLOUD B18 AO2 PK WND 07028/2020 LTG DSNT E-S RAB03 OCNL LTGICCG VC E TS OHD MOV E VIRGA SW P000

McIDAS images of GOES-13 0.63 µm visible channel data (below; click image to play animation) showed the development of the thunderstorms over the region

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

Posted in GOES-15, Red/Green/Blue (RGB) images, Severe convection, Suomi NPP, VIIRS, Web Map Server | No Comments »

Uncharacteristically cloud-free and warm across interior Alaska

June 17th, 2013

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

McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) revealed an uncharacteristically cloud-free view of most of the interior of Alaska on 17 June 2013. A large blocking ridge of high pressure had been building across the region, which helped to set the stage for record high temperatures at a number of locations — on 16 June many sites reported daily maximum temperatures in the middle to upper 80s F, with a few sites hitting the 90º F mark (regional temperatures and precipitation). In south-central Alaska, several locations set all-time record highs on 17 June.

On the previous day, a comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 3.74 µm shortwave IR data (below) showed that the Alaska fire season was well underway, with a number of fire “hot spots” (black to yellow to red color enhancement) appearing on the shortwave IR image; some of these larger fires were producing smoke plumes that could be seen on the visible image. Again, note the unusually warm tempertures at many of the reporting sites. Smoke plumes from a couple of the larger fires could also be seen in southwestern and southeastern Alaska on the animation of GOES-15 visible images above. Closer views of pyrocumulonimbus clouds associated with the largest fires can be seen here.

Suomi NPP VIIRS 0.64 µm visible channel and 3.74 µm shortwave IR channel images

Posted in Arctic, AVHRR, Fire detection, GOES-15, POES, Suomi NPP, VIIRS | No Comments »

Hurricane Barbara

May 29th, 2013

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

McIDAS images of GOES-14 0.63 µm visible channel data (above; click image to play animation) showed Tropical Storm Barbara as it intensified to Category 1 hurricane shortly before making landfall along the coast of the Gulf of Tehuantepec in southeastern Mexico on 29 May 2013. Since reliable records began for the Eastern Pacific Basin in 1966, Hurricane Barbara was the second-earliest hurricane landfall, as well as the easternmost landfall location.

An AWIPS image of ASCAT surface scatterometer winds overlaid on a GOES IR image (below) depicted a maximum wind speed of 53 knots at 16:01 UTC (while Barbara was still at tropical storm intensity).

ASCAT surface scatterometer winds

A 375-meter resolution Suomi NPP VIIRS 11.45 µm IR image at 19:35 UTC (below) showed the very cold cloud-top IR brightness temperatures (primarily in the -80 to -90 C range, enhanced with varying shades of violet) associated with convective clusters around the center of Hurricane Barbara as the storm was making landfall along the Mexican coast.

Suomi NPP VIIRS 11.45 µm IR image

===== 30 May Update =====

GOES-14 0.63 µm visible channel images (below; click image to play animation) seem to suggest that the low-level circulation of Barbara remained intact after crossing the rugged terrain of southern Mexico, and emerged into the Gulf of Mexico on 30 May. The GOES-14 satellite had been placed into Rapid Scan Operations (RSO), providing images as frequently as every 5-10 minutes.

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

Posted in GOES-14, Other Satellites, Satellite winds, Suomi NPP, Tropical cyclones, VIIRS | No Comments »

Ice jam flooding along the Yukon River in Galena, Alaska

May 28th, 2013

Suomi NPP VIIRS 1.61 µm “snow/ice discrimination channel” images

A sequence of AWIPS images of Suomi NPP VIIRS 1.61 µm near-IR “snow/ice discrimination channel” data covering the period from 13:47 UTC on 27 May to 23:24 UTC on 28 May 2013 (above) showed the effects of ice jam flooding along the Yukon River in the vicinity of Galena, Alaska (station identifier PAGA). In addition to snow and ice, water is also a strong absorber at the 1.61 µm near-IR wavelength — so it appears darker on the images. This dark signature of water inundation can be seen increasing in areal coverage during that 1.5 day period. This flooding forced the evacuation of aruond 300 residents of Galena, as many homes were extensively damaged by the flooding.

A comparison of Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water discrimination channel”, and 1.61 µm “snow/ice discrimination channel” images at 21:43 UTC on 28 May (below) showed that the Yukon River downstream of Galena was still snow/ice covered (appearing brighter white on the 0.64 µm and 0.86 µm images). Meanwhile, the darker signature of floodwaters near and upstream of Galena was evident to some extent on the 0.86 µm image, but was even more pronounced on the 1.61 µm image. The Yukon River ice jam flooding in the Galena area occurred about a week after similar ice jam floding occurred much farther upstream in the Fort Yukon area.