Tropical cyclones « CIMSS Satellite Blog

Super Typhoon Haiyan

November 7th, 2013

COMS-1 10.8 µm IR channel images (click to play animation)

Super Typhoon Haiyan (31W) formed as a tropical depression at low latitudes in the West Pacific Ocean on 03 November 2013 — and by 18 UTC on 07 November was estimated to have peaked at an intensity of sustained 170 knot winds with gusts to 205 knots (Storm track map | ADT plot | JTWC warning text). McIDAS images of 15-minute interval 10.8 µm IR channel data from the Korean COMS-1 satellite (above; click image to play animation; a YouTube video is also available) showed the intense tropical cyclone as it moved westward and made landfall in the Philippines on 07 November. There was a large, nearly symmetric ring of very cold cloud-top IR brightness temperatures in the -80 to -90º C range (violet colors) – and at times there were a few isolated pixels colder than -90º C (yellow enhancement). For comparison, a YouTube video of MTSAT-1 10.8 µm IR imagery is also available.

As the eye was still east of the Philippines, a McIDAS-V image comparison of 375-m resolution Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel data at 16:15 UTC on 07 November (below; courtesy of William Straka, CIMSS) revealed intricate banding structures within the eyewall region on the IR image, as well as bright streaks on the DNB image due to cloud illumination by intense lightning activity.

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

The eye and eyewall of Haiyan moved over the eastern Philippine islands of Samar and Leyte (near the city of Tacloban) during the early morning hours, as can be seen in COMS-1 0.675 µm visible channel images (below; click image to play animation; a YouTube video is also available)

COMS-1 0.675 µm visible channel images (click to play animation)

DMSP SSMIS 85 GHz microwave brightness temperature image

The nearly annular structure of the eyewall at 21:08 UTC on 07 November was revealed on a DMSP SSMIS 85 GHz microwave image (above) from the CIMSS Tropical Cyclones site. In addition, a sequence of eyewall replacement cycles can be seen during the 06-07 November period using the MIMIC-TC product (below). It appears as though Super Typhoon Haiyan was in the process of undergoing another eyewall replacement cycle as it was making landfall in the Philippines.

MIMIC-TC morphed microwave imagery (click image to play animation)

Regarding the size of and very cold cloud-top IR brightness temperatures seen with Super Typhoon Haiyan, the IR images below (courtesy of Rick Kohrs, SSEC) show a side-by-side comparison with Category 5 Hurricane Katrina (Haiyan has been artifically superimposed at the same location over the Gulf of Mexico). Note the significantly colder cloud-top IR brightness temperatures associated with Haiyan (-80 to -89 C, violet colors), due to its location in the tropics (near 10 N latitude) where the tropopause was much higher and much colder.

IR image comparison of Haiyan (left) and Katrina (right)

It is interesting to note that during the previous daytime hours (on 06 November), a series of mesovortices could be seen within the eye of Haiyan on COMS-1 visible images (below; click image to play animation; a YouTube video is also available). For more discussion on these mesovortices, see the From the Lee Side blog.

COMS-1 0.675 µm visible channel images (click to play animation)

Sea Surface Temperature analysis (with track of Haiyan)

As pointed out in the Joint Typhoon Warning Center prognostic reasoning bulletin, factors that favored the intensification of Super Typhoon Haiyan included warm sea surface temperatures (above) and low values of deep layer wind shear (below).

MTSAT IR images with overlay of Deep Layer Wind Shear contours

11 November Update: A McIDAS-V image comparison of “before Haiyan” (31 October) and “after Haiyan” (09 November) night-time Suomi NPP VIIRS 0.7 µm Day/Night Band data (below; courtesy of William Straka, SSEC/CIMSS) showed the extent of the power outages in the Tacloban City area and other towns in the northern portion of Leyte province, caused by devastating damage sustained during the landfall of the powerful typhoon.

Suomi/NPP Day/Night Band Imagery before and after Haiyan

21 November update: Rick Kohrs (SSEC) created a large (72 megabyte) animation of hourly MTSAT-1 6.75 µm water vapor channel imagery — covering the life span of Haiyan during the 03-11 November period — superimposed on a Sea Surface Temperature background (below; click image to play animation; a YouTube video is also available).

MTSAT-1 6.75 µm water vapor images, superimposed on a Sea Surface Temperature background (click to play animation)

Posted in COMS, DMSP, McIDAS-V, MTSAT, Suomi NPP, Tropical cyclones, VIIRS | 6 Comments »

Super Typhoon Francisco

October 19th, 2013

MTSAT-2 10.8 µm IR channel images (click to play animation)

Super Typhoon Francisco became the third Category 5 tropical cyclone of 2013 on 19 October 2013, as it intesified over the West Pacific Ocean northwest of Guam. 4-km resolution MTSAT-2 10.8 µm IR channel images (above; click image to play animation) showed the evolution and track of the eye of Francisco during the 17-19 October period (the island of Guam is in the lower right corner of the images). Note the trochoidal motion or “wobble” that is exhibited by the eye of the tropical cyclone as it tracked northwestward – this is caused by changes within the inner core structure of the storm, such as convective asymmetries.

1-km resolution MTSAT-2 0.73 µm visible channel images (below; click image to play animation) revealed better details of the eye and eyewall structure during the daylight portion of 18-19 October. The lowering October sun angle tended to more brightly illumimate the sloped surface of the northern quadrant of the eye.

MTSAT-2 0.73 µm visible channel images (click to play animation)

A McIDAS-V comparison of 375-meter resolution Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm thermal IR channel images at 15:48 UTC on 18 October (below; images courtesy of William Straka, CIMSS) showed a good example of the so-called “stadium effect”: the eye diameter appeared larger on the VIIRS IR image than on the corresponding “visible image at night” from the VIIRS Day/Night Band, because the clouds along the edges of the eye were steeply sloping outward with height.

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

Posted in McIDAS-V, MTSAT, Suomi NPP, Tropical cyclones, VIIRS | No Comments »

Typhoon Wipha

October 15th, 2013

MTSAT-2 10.8 µm IR channel images (click to play animation)

McIDAS images of MTSAT-2 10.8 µm IR channel data (above; click image to play animation) showed the center of Typhoon Wipha moving just southeast of Japan on 15 October 2013. The asterisk at the center of the images denotes the location of Tokyo Narita International Airport — many areas in the Tokyo region received very heavy rainfall which caused flooding and mudslides. At Izu Oshima island just south of Tokyo, rainfall rates were as high as 11.8 mm (4.7 inches) per hour, with a 24-hour rainfall total of 824.9 mm (32.5 inches).

AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) revealed the large amount of tropical moisture that was transported northward toward Japan as Wipha began its poleward recurvature. At the end of the animation Wipha began its extratropical transition as it merged with a cold front that was exiting Asia and beginning to move southeastward across the North Pacific Ocean.

MIMIC Total Precipitable Water product, with surface analyses (click to play animation)

Posted in Heavy rain / flooding, MTSAT, Tropical cyclones | No Comments »

Tropical Storm Karen’s transition to an extratropical coastal low

October 9th, 2013

850-hPa relative vorticity product (click image to play animation)

A sequence of images of the satellite-wind-derived 850 hPa relative vorticity product at 6-hour intervals covering the period 04 October to 09 October 2013 (above; click image to play animation) showed that the vorticity associated with Tropical Storm Karen over the Gulf of Mexico on 04 October could be followed northeastward as the storm made the transition to an extratropical low as it movved inland and interacted with a frontal boundary, then eventually organizing into a slow-moving coastal low along the US East Coast.

A comparison of 1-km resolution MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images (below) showed the organization of the coastal low at 18:10 UTC on 09 October, which featured deep offshore convection with IR cloud-top temperatures as cold as -75º C.

MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images (09 October)

===== 10 October Update =====

A comparison of 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:59 UTC on 10 October (below) revealed that some strong convective elements had moved inland over southeastern Virginia and northeastern North Carolina, producing heavy rainfall.