Hurricane Andres

June 23rd, 2009
GOES-11 visible images

GOES-11 visible images

Hurricane Andres (briefly) became the first hurricane of the Eastern Pacific tropical cyclone season on 23 June 2009. However, the satellite presentation of Andres was rather unremarkable: even though a low-level “eye” circulation was recognizable on GOES-11 visible images from the CIMSS Tropical Cyclones site (above), the GOES-11 IR cloud top temperatures (below) were quite warm over the center of the Category 1 hurricane due to the fact that deep convection was displaced well to the south. However, a small convective burst could be seen developing along the southern periphery of the low-level circulation center on the final visible image at 20:00 UTC.

GOES-11 10.7 µm IR images

GOES-11 10.7 µm IR images

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Lake Superior lake breeze

June 22nd, 2009
GOES-12 visible images

GOES-12 visible images

GOES-12 visible images (above) showed that a well-defined lake breeze developed along the western portion of Lake Superior during the afternoon hours on 22 June 2009. The MODIS Sea Surface Temperature (SST) product from 2 days earlier (below) indicated that SST values in the much of the middle of the lake were still in the low 40s F (blue color enhancement) — and Buoy 45006 was actually reporting a SST value of 39 F on 22 June. In northern Wisconsin, note the large surface air temperature gradient that existed between Port Wing (station identifier PNGW3) which remained in the upper 40s F and Ashland (station identifier KASX) which rose into the low 80s F!

MODIS Sea Surface Temperature product

MODIS Sea Surface Temperature product

Farther to the south, GOES-12 visible imagery also showed that a Lake Michigan lake breeze was moving inland across southeastern Wisconsin and northeastern Illinois (below).

GOES-12 visible image

GOES-12 visible image

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Mountain waves over Colorado

June 22nd, 2009
MODIS 6.7 µm and GOES-12 6.5 µm water vapor images

MODIS 6.7 µm and GOES-12 6.5 µm water vapor images

Moderate southwesterly flow aloft over the Rocky Mountains was aiding in the formation of mountain waves across much of Colorado and parts of the adjacent states on 22 June 2009. AWIPS comparisons of the 1-km resolution MODIS 6.7 µm water vapor image with the corresponding 4-km resolution GOES-12 6.5 µm water vapor image (above) and the 8-km resolution GOES-11 6.7 µm water vapor image (below) demonstrated the value of better spatial resolution for detecting such mesoscale features.

MODIS 6.7 µm and GOES-11 8-km 6.7 µm water vapor images

MODIS 6.7 µm and GOES-11 6.7 µm water vapor images

The appearance of these banded “mountain wave signatures” on water vapor imagery indicates the potential for clear air turbulence in those areas; however, there were no pilot reports of turbulence until 13:02 UTC near Fort Collins (at an altitude of 15,000 feet). An animation of the GOES-12 6.5 µm water vapor imagery (below) also showed the presence of a lee-side cold frontal gravity wave, which could be seen propagating southward across eastern Colorado and western Kansas. In fact, a small packet of waves could be seen along and behind the leading edge of this lee-side cold frontal gravity wave on the MODIS water vapor images above — surface winds behind this front had gusted to 36 knots at McCook, Nebraska (station identifier KMCK) and 20 knots at Goodland, Kansas (station identifier KGLD).

GOES-12 6.5 µm water vapor images

GOES-12 6.5 µm water vapor images

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