MTSAT-2 10.8 µm infrared imagery (click image to animate)

When two tropical cyclones are within close proximity to each other, they will typically start a rotation around a common center. This interaction, called the Fujiwhara Effect, may be occurring in the image loop above. Typhoon Bolaven approaches Typhoon Tembin, and the distance between the two reaches a minimum on 23 August, after which time Tembin moves west and Bolaven moves northwest. Subsequent to Bolaven’s recurvature over the Korean peninsula, Tembin moves northward into midlatitudes as well.

850-mb vorticity maps from CIMSS Tropical Weather Website (click image to animate)

The CIMSS Tropical Website includes 850-mb vorticity analyses. A 10-day loop that shows the motion of Tembin and Bolaven is shown above.

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Suomi/NPP VIIRS Day-Night Band and 11.45 µm infrared channel (click image to toggle between images)

The Day-Night Band on VIIRS, flying on the Suomi/NPP satellite gave an excellent view of Isaac at strong tropical storm strength in the northern Gulf of Mexico shortly after midnight on August 28 2012. VIIRS is providing something unique to forecasters: Visible imagery at night that allows easy identification of overshooting tops and cirrus blow-off, and cumulus fields in the Gulf of Mexico. The infrared window channel on VIIRS showed coldest cloud-top temperatures of -84 C, and also the effects of dry air on the tropical system. Convection is suppressed in the northern half of the storm. A zoomed-in annotated version of the above VIIRS image comparison is available here.

VIIRS data used to produce these images was acquired by the X/L band antenna here at CIMSS in Wisconsin, and was processed using the Community Satellite Processing Package (CSPP).

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

During the first few hours after sunrise, GOES-14 Super Rapid Scan Operations for GOES-R (SRSOR) visible imagery at 1-minute intervals (above; click image to play animation) showed the development of a number of  convective elements around the center of Isaac’s circulation. After about 14 UTC, the rotation of the low-level circulation of Isaac could be seen as a “clear slot” opened up between areas of convection.

More information on Isaac is available at the National Hurricane Center website, and at the CIMSS Tropical Cyclones site. One-minute imagery of the storm from GOES-14 can downloaded in real time from this website.

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GOES-14 0.63 µm visible channel and 10.7 µm infrared channel (click image to play animation)

Tropical Storm Isaac continues a track towards the central Gulf Coast of the United States (See the National Hurricane Center for further information). The GOES-14 animation above, with images shown every 5 minutes over the course of 5 hours, suggests that intensification has not occurred despite the presence of very warm waters (and low shear) over the Gulf of Mexico. The lack convective clouds over the eastern Gulf suggest the presence of relatively dry air that will inhibit development. Water Vapor imagery from this morning does suggest that any moisture between Isaac and south Florida is relatively shallow in the atmosphere (as evidenced by the warmer temperatures in the Water Vapor channel east and south of Isaac).

VIIRS 11.45 µm brightness temperature

Convection associated with Isaac does have very cold cloud tops. The 11.45 µm imagery, above, from VIIRS on board Suomi/NPP shows a large area of cloud tops near -80 C.

GOES-14 0.63 µm visible channel at full resolution (click image to play animation)

GOES-14 continues SRSOR operations (as detailed here). The loop above covers a little more than an hour over Isaac on August 27. The region of white that does not move around the Florida Keys is turbid water that has resulted from storm winds. Clouds in the relatively dry air in that region are streaming north. Ongoing deep convection persists near the storm center. A loop from later in the day (below), continues to show dry air east of and very close to the storm center, but improved storm organization nevertheless.

GOES-14 0.63 µm visible channel at full resolution (click image to play animation)

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

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the smoke plumes emanting from a number of large wildfires that were burning in parts of Idaho on 24 August 2012. Note that some of the low-altitude smoke was being channeled southward through valleys by strong northerly winds. The surface visibility at Salmon, Idaho (surface identifier KSMN) was reduced to 2 miles due to smoke, and at Dillon, Montana (station identifier KDLN) the surface visibility dropped to 1.25 miles.

The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes (as opposed to the standard 15-minute image interval).

MODIS true color image (viewed using Google Earth)

A 250-meter resolution Aqua MODIS true color image from the SSEC MODIS Today site (above; viewed using Google Earth) showed a detailed view of the smoke plumes at 20:13 UTC.

Suomi NPP VIIRS 3.74 µm shortwave IR + 0.8 µm Day/Night Band images

During the following night-time hours, a comparison of AWIPS images of Suomi NPP VIIRS 3.74 µm shortwave IR and 0.8 µm Day/Night Band (DNB) data (above) demonstrated how the DNB imagery can detect the glow of the actively-burning fires (co-located with the black to yellow to red color enhanced “hot spots” on the shortwave IR image) in addition to the city lights across the region. Stray light contamination was affecting the far northeastern portion of the DNB image.

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