CIMSS Satellite Blog

AWIPS images of geostationary satellite water vapor channel data

AWIPS images of geostationary satellite water vapor channel data (above) showed a long moisture plume moving across the Pacific Ocean toward the west coast of the US on 02-03 October 2008. A comparison of GOES-11 water vapor channel data with POES (AMSU) and SSM/I Total Precipitable Water (TPW) products (below) revealed that TPW values were as high as 50-60 mm (2.0-2.4 inches) within this moisture plume. The MIMIC TPW product suggested that this moisture plume originated over the western Pacific Ocean, southeast of Japan.

AWIPS images of POES TPW products and GOES water vapor channel

This moisture plume was associated with a strong polar jet stream, as seen by an overlay of hourly MADIS atmospheric motion vectors on GOES water vapor channel imagery (below).

GOES water vapor images + MADIS winds

The 18 UTC GFS model fields were forecasting maximum winds in the core of the jet to reach 170 knots (below) — there were a few MADIS wind vectors with speeds of 177-181 knots around that time (and a MADIS wind vector with a speed of 191 knots was seen at 21 UTC).

GFS winds + MADIS winds

GOES-12 IR image + SSM/IS microwave image

Hurricane Ike intensified into a  Category 4 storm late in the day on 03 September 2008. A comparison of GOES-12 10.7 µm IR and SSM/IS 85 GHz microwave images from the CIMSS Tropical Cyclones site (above) showed a well-defined eye structure around 09:15 UTC on 04 September. A period of rapid intensification was seen on the CIMSS Advanced Dvorak Technique (ADT) intensity estimate plot (below), which was noted in the National Hurricane Center discussion:

HURRICANE IKE DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL092008
1100 PM EDT WED SEP 03 2008

IKE HAS RAPIDLY INTENSIFIED THIS EVENING.  AN EYE BECAME APPARENT IN CONVENTIONAL SATELLITE IMAGERY SHORTLY AFTER 2100 UTC.  SINCE THAT TIME THE EYE HAS BECOME MORE DISTINCT WITH A RING OF VERY COLD CLOUDS TOPS SURROUNDING IT.  THE LATEST DVORAK DATA T-NUMBERS WERE T6.0 AND RAW ADT ESTIMATES FROM UW-CIMSS HAVE AVERAGED T6.2 SINCE 2045 UTC.  BASED ON THESE ESTIMATES THE INITIAL INTENSITY IS SET AT 115 KT…MAKING IKE A CATEGORY FOUR HURRICANE.

CIMSS Advanced Dvorak Technique (ADT) intensity plot

GOES-12 10.7 µm IR and GOES-12 visible images (below) showed that while Hurricane Ike maintained a well-defined eye during the morning hours on 04 September, the appearance of the eye did degrade somewhat as the day went on — and the intensity of Ike was reduced from 120 knots to 115 knots.

GOES-12 10.7 µm IR images

GOES-12 visible images

The deep layer wind shear product (below) indicated that Ike was moving into an environment of increasing  northerly shear, which may have contributed to the slight decrease in intensity noted during the day.

GOES-12 IR image + deep layer wind shear product

AWIPS images of GOES-12 10.7 µm IR channel

Hurricane Gustav underwent a period of rapid intensification during the daytime hours on 30 August 2008 (as seen on a plot of the CIMSS Advanced Dvorak Technique), reaching Category 4 intensity. AWIPS images of the GOES-12 10.7 µm IR channel (above) revealed an impressive eye structure on 30 August, which subsequently degraded in appearance on 31 August (as Gustav’s interaction with Cuba apparently took a toll on the tropical cyclone). Large-format IR animations are also available: 32 MB Animated GIF | 16MB QuickTime movie.

High-resolution atmospheric motion vectors (AMVs) produced once per hour (below) showed the well-defined upper-tropospheric outflow within the northern semi-circle of the storm as it crossed Cuba and moved into the Gulf of Mexico. The upper-tropospheric winds associated with Tropical Storm Hanna could also be seen farther to the east, over the Atlantic Ocean.

GOES-12 IR images + atmospheric motion vectors

On 31 August, early morning QuikSCAT data showed the broad wind field associated with the Category 3 storm, while a late-morning AWIPS image of the 1-km resolution MODIS 11.0 µm IR channel data (below) revealed a subtle hint of an eye structure with a ring of colder clouds at 16:34 UTC — cloud top brightness temperature values at that time were as cold as -87º C (darker purple enhancement).

AWIPS image of MODIS 11.0 µm IR channel data

During the remainder of the day on 31 August, there was some evidence of an eye structure on polar-orbiting satellite (POES) microwave imagery, even though no eye was obvious on conventional geostationary satellite (GOES) visible or IR imagery (below, courtesy of the CIMSS Tropical Cyclones site).

POES microwave image + GOES-12 IR image

Gustav eventually made landfall in Louisiana as a strong Category 2 hurricane on 01 September 2008 (below).

GOES-12 IR montage of Gustav