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

McIDAS images of GOES-14 1-minute interval Super Rapid Scan Operations for GOES-R (SRSOR) 1-km resolution 0.63 µm visible channel images (above; click image to play animation) showed overshooting tops and cloud-top gravity waves associated with a large convective burst located just to the southwest of the center of Tropical Storm Isaac on 23 August 2012.

The corresponding 4-km resolution GOES-14 10.7 µm IR channel images (below) revealed the fluctuation of cold cloud top IR brightness temperatures in the -80 to -90º C range (light to dark purple color enhancement). The white tropical cyclone symbol denotes the 12:00 UTC position of the center of Tropical Storm Isaac according to the National Hurricane Center.

GOES-14 10.7 µm IR channel images (click image to play animation)

===== 24 August Update =====

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

A GOES-14 visible image animation from early morning on August 24th (above; click image to play animation), about 24 hours after the animation at top, continues to show active convection, although the storm itself remains poorly organized with an elongated center of circulation as seen on OSCAT scatterometer surface winds (below). The presence of increasingly organized curved convective banding is obvious, however.

GOES-13 10.7 µm IR channel images + OSCAT scatterometer surface winds

GOES-14 0.63 µm visible channel images and 10.7 µm images, 1200-1259 UTC 24 August 2012 (click image to play animation)

The animation above shows an hour of 1-minute visible (0.63 µm) and Infrared (10.7 µm) imagery starting at 1200 UTC on 24 Friday. The cold cloud tops of the active convection, and the episodic overshooting tops, are evident. Note that the slight flicker that is apparent in the 10.7 µm imagery may be due to the timing of space looks that the ‘cold end’ that is used in the IR calibration. An animation for the one hour starting 1800 UTC is below. Significant changes in the structure of the storm are apparent.

GOES-14 0.63 µm visible channel images and 10.7 µm images, 1800-1859 UTC 24 August 2012 (click image to play animation)

For more information on Isaac, refer to the CIMSS Tropical Cyclones site and the National Hurricane Center. One-minute imagery for the storm can be viewed in real time here.

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GOES-14 SRSOR 0.62 µm and 10.7 µm Imagery (click image to play animation)

GOES-14 is in SRSOR operations today and was well-positioned to monitor the flooding rains that occurred in Las Vegas (which received a daily record 1.65 inches of rainfall). The animation above shows cold cloud tops northeast of Las Vegas, with more convection moving in from the southwest. Click here for a large (85 M) animated gif file of one-minute imagery from 1415 UTC through 1859 UTC).

The Blended Total Precipitable Water product (TPW) for this afternoon shows a local maximum in TPW over the southwestern United States. A MIMIC TPW animation suggests that the moisture has originated from a surge up the Gulf of California. During the previous night-time hours, MODIS TPW values of 50-60 mm were seen across far southeastern California, far southwestern Arizona, and in the Las Vegas area as well.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with cloud-to-ground lightning strikes)

AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data (above) showed the convective cluster in southern California at 20:29 UTC (which was seen early on the GOES-14 image animation). Cloud top IR brightness temperatures were as cold as -69º C (dark red color enhancement), and a number of cloud-to-ground lightning strikes (mostly of negative polarity) were detected within a 15-minute period as this thunderstorm was growing in size and intensity.

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