Sequence of MODIS false color RGB images (March 08, 20, 27, and April 01)

A series of four 250-meter resolution MODIS false color images — 08, 20, and 27 March, and 01 April 2010 — from the SSEC MODIS Today site (above) show portions of the Connecticut River (which runs north to south through the center of the images) becoming swollen and flooding the adjacent low-lying areas in central Connecticut. In these MODIS false color images, water appears as dark shades of blue, while snow cover has a cyan appearance.

A comparison of the 250-meter resolution MODIS true color and false color images from 01 April 2010 (below) reveals increased levels of turbidity along portions of some of the rivers, due to increased run-off during the series of 3 heavy precipitation events across the region during the 13-31 March 2010 period.

MODIS true color and false color images (01 April 2010)

MODIS true color images (below, viewed using Google Earth) showed that the most pronounced areas of flooding along the Connecticut River were just to the north and south of Hartford.

MODIS true color images (viewed using Google Earth)

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First TIROS-1 image (01 April 1960)

Today marks the 50th anniversary of the first image from the meteorological satellite TIROS-1, which was available on 01 April 1960 (above). While TIROS-1 was only operational for 78 days, it provided a number of images of the Earth and cloud systems (including the first image of a tropical cyclone, over the South Pacific Ocean on 10 April 1960).

To demonstrate how satellite imagery has improved over the past 50 years, one only has to examine McIDAS images of NOAA GOES-13 visible channel data (below) over the same general region as shown on the first TIROS-1 image (Maine, and the Canadian Maritime provinces). While swirling high-level clouds occupy most of the satellite scene on 01 April 2010, you can still see very good details of low cloud features, such as the stratus deck beginning to erode over parts of Maine and New Hampshire. One particular feature of interest is the bright white snow-covered peak of Mount Katahdin in north-central Maine (which remains stationary in the images, as the clouds around it erode) — this geographic feature has a peak elevation of 5,268 ft (1,605.7 m), and marks the northern point of the Appalachian Trail. Also, if you look closely, you can also see a small ice floe moving slowly westward across open waters of the Gulf of Saint Lawrence, just south of the coast of Quebec (near the upper right corner of the images) — sea ice in the Gulf of Saint Lawrence was also seen in some of the earliest TIROS-1 images.

Note that GOES-13 will replace GOES-12 as the operational GOES-East satellite on 14 April 2010.

GOES-13 visible images (01 April 2010)

Polar orbiting (POES) satellite imagery has also improved dramatically, as can be seen on a NOAA-17 AVHRR false color Red/Green/Blue (RGB) image (using AVHRR channels 01/02/04) centered over Maine on 01 April 2010 (below). Again, note the brighter white snow-covered peak of Mount Katahdin, located to the northwest of Millinocket (station identifier KMLT). The widespread low clouds appear brighter white on the false color image, while high cirrus clouds in the northwestern corner of the image take on more of a light blue tint. Bare (snow-free) ground in southwestern Maine appears as shades of green.

NOAA-17 AVHRR false color RGB image (01 April 2010)

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MODIS water vapor. IR, and visible images

AWIPS images of the 1-km resolution MODIS 6.7 µm water vapor channel, the 11.0 µm IR channel, and the 0.65 µm visible channel (above) showed a pronounced “Foehn gap” immediately downwind of the highest terrain of the Sierra Nevada mountain range on 31 March 2010.

A comparison of the 1-k resolution MODIS 6.7 µm water vapor image with the corresponding 8-km resolution 6.7 µm water vapor image from GOES-11 (below) demonstrates the ability to detect such features with better spatial resolution.

1-km resolution MODIS and 8-km resolution GOES-11 water vapor images

Strong southwesterly winds aloft with speeds of 70-110 knots were creating this Foehn gap — but the core of a very strong jet stream was located a bit farther to the south and east. According to the RUC model, the highest wind speeds at the level of maximum Wind Speed was in excess of 140 knots over far northwestern Arizona and far southwestern Utah. However, there were a number of MADIS Atmospheric Motion Vectors (AMVs) that indicated wind speeds as high as 161 knots, 167 knots, 170 knots, and 179 knots (below).

MODIS water vapor image + RUC winds speeds + MADIS AMVs

MODIS water vapor image + RUC wind speeds + MADIS AMVs

MODIS water vapor image + RUC wind speeds + MADIS AMVs

MODIS water vapor image + RUC wind speeds + MADIS AMVs

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GOES-12 10.7 µm IR images + cloud-to-ground lightning strikes

Strong convection moving eastward from Florida and across the Bahamas produced at least two tornadoes on the island of Grand Bahama on 29 March 2010 — according to media reports, there were fatalities at the Grand Bahama Container Port located at the western end of the island, where several large cranes were toppled. There were also tornadoes reported in Florida a few hours earlier. AWIPS images of GOES-12 10.7 µm IR channel data with an overlay of negative (cyan) and positive (violet) cloud-to-ground lightning strikes (above; also available as a QuickTime animation) showed several clusters of convection moving across Grand Bahama Island (located in the center of the images; station identifier MYGF is Freeport). In particular, note the storms with the highest density of negative cloud-to-ground lightning strikes moving across the island during the 15:15 – 15:45 UTC time period — this is likely the convective cell that produced the tornadoes. The coldest IR brightness temperatures over the Bahamas on the 4-km resolution GOES-12 images was -66º C (darker red color enhancement).

The Blended Total Precipitable Water (TPW) product (below) indicated that TPW values were in excess of 50 mm or 2.0 inches (darker purple color enhancement) along and ahead of a cold frontal boundary that was approaching from the west. These TPW values were 150%-200% above normal. In addition, the presence of a pre-frontal trough may have played a role in helping to enhance surface convergence in the vicinity of the Bahamas.

Blended Total Precipitable Water product

A closer view using 1-km resolution MODIS 11.0 µm IR channel data at 15:52 UTC (below) revealed greater detail in the overshooting top structure of the convection as it was moving over the eastern portion of the Grand Bahama Island. The coldest MODIS IR brightness temperatures near the island were -70º C (black color enhancement).

MODIS 11.0 µm IR image

The CLAVR-x POES AVHRR Cloud Type product (below) indicated a number of “Overshooting Top” category clouds (violet color enhancement) associated with the stronger convective clusters.

POES AVHRR Cloud Type product

The POES AVHRR Cloud Top Height product (below) showed that the highest cloud tops over the Bahamas were around 15 km or 49,000 feet (cyan color enhancement).

POES AVHRR Cloud Top Height product

A MODIS Sea Surface Temperature (SST) product from the following day (below) revealed that there was a very strong SST gradient between Florida (where SST values were primarily in the mid 60s F, green colors) and the Bahamas (where SST values were in the mid 70s F, orange colors). Perhaps the significantly warmer SST values of the Gulf Stream may have also played a role in the intensification of the convection as it approached the Bahamas?

MODIS Sea Surface Temperature product

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