Heavy rain / flooding « CIMSS Satellite Blog

Tropical Storm Washi (27W) strikes the Philippines

December 17th, 2011

MTSAT-1R 10.8 µm IR images (click image to play animation)

MTSAT-1R 10.8 µm IR images from the CIMSS Tropical Cyclones site (above; click image to play animation) showed a fairly compact cluster of cold convective cloud tops associated with Tropical Storm Washi as it moved westward toward the Philippines during the 15-16 December 2011 period.

A closer view using MIMIC microwave imagery (below) also showed a relatively small area of enhanced brightness temperatures (representing heavy precipitation) crossing Mindanao Island in the southern Philippines on 16 December.

MIMIC microwave imagery

However, AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) revealed that Tropical Storm Washi was embedded within a long fetch of very rich tropical moisture, with TPW values in excess of 60 mm or 2.4 inches (darker red color enhancement). This abundance of moisture helped to fuel over 10 hours of heavy rainfall, which resulted in widespread flash flooding and reports of over 900 deaths in the Philippines.

MIMIC Total Precipitable Water product (click image to play animation)

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

Hydrological impacts of Hurricane Irene

August 29th, 2011

MODIS true color images: 16 August and 28 August 2011

Heavy rainfall associated with Hurricane Irene included 20.40 inches at Virginia beach, Virginia and 20.00 inches at Jacksonville, North Carolina (HPC summary). Winds gusted as high as 115 mph at Cedar Island, North Carolina. The effects of the heavy rain and strong winds can be seen in a before/after comparison of 250-meter resolution MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above). On the “before” image (16 August 2011), there was a large smoke plume seen from a fire that was burning in the Great Dismal Swamp area in far southeastern Virginia; on the “after” image (28 August 2011), water turbidity was significantly enhanced due to suspended sediment across the Outer Banks region of North Carolina — and a narrow filament of sediment was being actually being entrained into the flow of the Gulf Stream.

AWIPS images of the corresponding MODIS 0.65 µm visible channel data and the MODIS Sea Surface Temperature (SST) product (below) showed that the enhanced turbidity features seen on the MODIS true color image generally exhibited slightly cooler SST values (in the middle to upper 70s F, blue color enhancement) compares to the waters located closer to the Gulf Stream (SST values in the lower 80s F, darker red color enhancement).

MODIS 0.65 µm visible channel image + MODIS Sea Surface Temperature image

Farther to the north, another before/after MODIS true color image comparison revealed additional areas of sediment being carried off the coast of the Northeast US (below). Also note that there was a great deal of sediment in the Hudson River (perhaps better seen in this 20 August / 29 August comparison).

MODIS true color images: 26 August and 29 August 2011

Posted in General interpretation, Heavy rain / flooding, Hydrology, MODIS, Red/Green/Blue (RGB) images | No Comments »

Flooding along the Souris River and Missouri River in North Dakota

June 23rd, 2011

MODIS 0.65 µm visible channel and 2.1 µm near-IR "snow/ice channel" images

AWIPS images of 1-km resolution MODIS 0.65 µm visible channel and MODIS 2.1 µm near-IR “snow/ice channel” data on 23 June 2011 (above) demonstrated the utility of the snow/ice channel to help highlight areas of potential flooding — because water is a strong absorber at the 2.1 µm wavelength, it appears very dark in the snow.ice images. The Souris River located in north-central North Dakota stands out in the images, along with the Missouri River to the southwest.

A comparison of 250-meter resolution MODIS true color and false color images (below) showed greater detail of the flooded areas on the false color image, as well as the fact that a great deal of sediment was flowing into the Missouri River and even into the western portion of Lake Sakakawea.

MODIS true color and false color Red/Green/Blue (RGB) images

A comparison between MODIS false color images on 29 June 2010 and 23 June 2011 (below) showed the dramatic change in the Souris River, as well as in the Missouri River southwest of Williston, North Dakota. In June 2011 historic flooding was occurring in the city of Minot along the Souris River.