GOES-11 and GOES-14 visible channel images

A comparison of GOES-11 and GOES-14 (which was undergoing its NOAA Science Test) visible channel images (above; also available as a QuickTime animation) showed a series of standing waves to the lee of Isla Guadalupe and also to the lee of Baja California on 07 December 2009. These terrain features were acting as an obstacle to strong westerly flow within the marine boundary layer, which initiated the formation of the lee waves.

A signature of these lee waves was also evident on GOES-14 (and to a lesser extent, GOES-11) water vapor channel images (below; also available as a QuickTime animation). The spatial resolution of the 6.5 µm GOES-14 water vapor channel is 4 km, compared to the 8 km resolution of the 6.7 µm water vapor channel on GOES-11 — this allowed the wave structure to be observed with greater clarity using GOES-14.

GOES-11 and GOES-14 water vapor images

A MODIS 11.0 µm IR image with an overlay of 1-hour MADIS atmospheric motion vectors (below) showed that lower tropospheric wind speeds were as high as 50 knots over the region.

MODIS IR image + MADIS 1-hour wind vectors

AVHRR Cloud Top Height (CTH) and Cloud Top Temperature (CTT) products (below) indicated the the crests of the waves immediately downwind of Isla Guadalupe exhibited CTH values as high as to 5 km and CTT values as cold as -30º C — the surrounding marine stratoculumus clouds had CTH values near 2 km and CTT values around +2º C.

AVHRR Cloud Top Height and Cloud Top Temperature products

Farther to the north, GOES-11 and GOES-14 visible channel images (below; also available as a QuickTime animation) revealed a long cloud plume that had formed downwind of Mount Olympus in far northwestern Washington. Strong northeasterly flow had developed over the region in response to the formation of a broad trough of low pressure over the western US. Note the improvement in GOES-14 Image Navigation and Registration (INR), with much less image-to-image wobble compared to GOES-11.

GOES-11 and GOES-14 visible channel images

A MODIS fog/stratus product image (below) showed that this cloud plume was also apparent during the pre-dawn hours, before any visible channel imagery would have been available.

MODIS fog/stratus product

A MODIS 3-channel Red/Green/Blue (RGB) image (below) suggested that this cloud plume was comprised primarily of supercooled water droplets, which exhibit a brighter appearance on the RGB image — ice crystal clouds would have more of a pink-colored look on such an RGB image (like that seen with the deep snow cover over the interior mountains)

MODIS false color Red/Green/Blue (RGB) image

A MODIS visible channel image with an overlay of RUC80 850 hPa winds (below) confirmed the presence of northeasterly flow over the region. As the flow moved around the obstacle of Mount Olympus, lee-side convergence helped to aid in the formation of the cloud plume.

MODIS visible image + RUC80 850 hPa winds

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GOES-14 10.7 µm IR images

An historic snowfall event (SPC watches and warnings) impacted parts of the Gulf Coast region of the US on 04 December 2009 — this event produced the earliest snowfall on record at both Houston, Texas and Lake Charles, Louisiana, and total snowfall amounts were as high as 5.0 inches in Mississippi, 4.0 inches in Texas, and 3.0 inches in Louisiana. McIDAS images of the GOES-14 10.7 µm IR channel data (above) showed the development of the bands of elevated convection that produced the snowfall (the symbols of precipitation type are also plotted on the IR images).

AWIPS images of the GOES-12 10.7 µm IR channel data with overlays of surface METAR reports and cloud-to-ground lightning strikes (below) did indicate that there were a few lightning strikes early in the development of the bands of elevated convection over far southeast Texas (with a small number of strikes immediately offshore later in the morning), but as the snowfall event was unfolding farther north toward the Houston area there were no cloud-to-ground strikes seen. GOES-14 and GOES-12 IR cloud top brightness temperatures were in the -40 to -50º C range, which was near the tropopause on the Corpus Christi, Texas and Lake Charles, Louisiana rawinsonde data.

GOES-12 10.7 µm IR images + METARs + Cloud-to-Ground Lightning

1-km resolution MODIS visible channel, 2.1 µm near-IR “snow/ice channel”, and 11.0 µm IR channel images (below) offered a view of the event at 16:58 UTC or 10:58 AM local time. Shadows from the tall convective elements could be seen on the visible image — and since the tops of the elevated convection were glaciated, they showed up as darker features on the snow/ice image. As was seen on the GOES-12 and GOES-14 IR images above, the IR cloud top brightness temperatures were in the -40 to -50º C range.

MODIS visible, 2,1 µm near-IR "snow/ice", and 11.0 µm IR channel images

1-km resolution AVHRR cloud products at 20:11 UTC or 2:11 PM local time (below) showed that the glaciated cirrus cloud type elements (red enhancement) had cloud top heights in the 9-10 km range (cyan color enhancement), with cloud top temperatures in the -40 to -50º C range (darker blue enhancement).

AVHRR Cloud Type, Cloud Top Height, and Cloud Top Temperature products

UPDATE: On the following morning, GOES-14 visible images (below) revealed the areal extent of the resulting snow cover that had not yet melted. Note the brighter white band of deeper snow cover near the Texas coast, where Lane City and Boling had received 4.0 inches. Some of the bright features seen in southwestern Louisiana were low stratiform clouds that were burning off as daytime heating increased.

GOES-14 visible images

MODIS true color image (displayed using Google Earth)

MODIS true color images (displayed using Google Earth) showed another view of the remaining snow cover on the late morning hours on 05 December over Texas (above) and over Louisiana and Mississippi (below). The highest snowfall totals reported in each region are noted on the images.

MODIS true color image (displayed using Google Earth)

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GOES-14 Full Disk 6.5 µm water vapor images

On Day 2 (01 December 2009) of the GOES-14 NOAA Science Test, the satellite was placed into a continuous “Full Disk” scan mode, providing images of the entire hemisphere at 30 minute intervals — full disk images of the GOES-14 6.5 µm “water vapor channel” are shown above. While the current GOES operational scan schedule provides 1 full disk image every 3 hours, the ABI instrument on the upcoming GOES-R satellite will have the ability to provide full disk images every 5 minutes!

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GOES-11, GOES-14, and GOES-12 3.9 µm shortwave IR images

A comparison of GOES-11 (GOES West), GOES-14, and GOES-12 (GOES East) 3.9 µm shortwave IR images (above) indicated that there were a number of fires burning across parts of southern British Columbia, Canada on 01 December 2009, as confirmed by the NOAA Hazard Mapping System. The 3 sets of images are displayed in the native projection of their respective satellites. The fire “hotspots” showed up as warmer (darker black enhancement) pixels.

The plot below shows that the warmest 3.9 µm IR brightness temperature on the GOES-14 imagery was 325.8º K at 22:15 UTC, compared to 317.7º K on GOES-11 at 20:15 and 304.9º K on GOES-12 at 19:45 UTC. This difference in maximum fire pixel brightness temperature and time was due to such factors as different satellite viewing angles (compounded by the steep slopes of the mountainous terrain) and possible brief obscuration by clouds and/or smoke.

Plot of maximum fire pixel IR temperatures from GOES-11, GOES-12, and GOES-14

AWIPS images of the MODIS visible and 3.7 µm shortwave IR channel data from 19:46 UTC are shown below; again, a number of darker black fire hot spots can be seen on the shortwave IR image across parts of southern British Columbia (as well as to the east across southern Alberta). The visible image revealed that there was a great deal of snowpack in the mountains of the region — however, there were also a few patches of supercooled water droplet cloud and/or fog in the higher terrain, which showed up as darker gray features on the shortwave IR image (due to solar reflection off the tops of the supercooled clouds/fog).

MODIS visible and 3.7 µm shortwave IR channel images

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