Mesolow over Lake Superior

January 15th, 2013 |
GOES-13 0.63 µm visible channel images (click image to play animation)

GOES-13 0.63 µm visible channel images (click image to play animation)

A Mesolow developed over Lake Superior today and moved rapidly northeast towards Ontario. As the system moved near Pukaskwa, ON (48.6 N, 86.3 W), winds there shifted from northwest at 3 knots at 1800 UTC to northeast at 5 knots at 1900 UTC to west at 7 knots, gusting to 16 knots at 2000 UTC. (An animation of surface plots overlain on the satellite imagery is here). The mesolow seems to have developed as an interaction with the topography on Isle Royale. Lake Surface temperatures are in the mid-30s, as is typical this time of year, and 850-mb temperatures (as measured at International Falls at 1200 UTC) were around -18 C.

GOES-15 0.62 µm visible channel images (click image to play animation)

GOES-15 0.62 µm visible channel images (click image to play animation)

GOES-West provided an oblique view of the system development, shown above.

Hat tip to the National Weather Service in Marquette Michigan for first alerting us to this system’s presence!

Blowing dust in Colorado and Kansas

January 11th, 2013 |
GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images (click image to play animation)

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images (click image to play animation)

McIDAS images of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation) showed the development of a large area of blowing dust that formed in response to high winds along and in the wake of a strong cold frontal boundary (18 UTC surface analysis) that was moving from eastern Colorado into western Kansas on 11 January 2013. Winds gusted to 56 mph in Burlington, Colorado and gusted to 49 mph in Goodland, Kansas (where the surface visibility was reduced to 1.75 miles by the blowing dust).

A closer view using 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel and the corresponding false-color Red/Green/Blue (RGB) image at 19:23 UTC or 12:23 PM local time (below) revealed the banded structure of the blowing dust cloud,  which was verified by a photo taken around 19:17 UTC from an aircraft over eastern Colorado by William Straka (CIMSS). Also evident on the VIIRS images was  the presence of a number of aircraft dissipation trails (or “distrails”) and “hole punch clouds” across parts of central and eastern Kansas. The brighter pink color enhancement within the distrails and hole punch clouds indicated the glaciation of supercooled water droplets in those portions of the cloud deck that were penetrated by aircraft.

Suomi NPP VIIRS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) image

Suomi NPP VIIRS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) image

In a comparison of a 20:33 UTC (or 1:33 PM local time) MODIS 0.65 µm visible image with the corresponding MODIS 11-12 µm IR brightness temperature difference (below), the most dense areas of blowing dust were highlighted by the lighter cyan colors.

MODIS 0.65 µm visible channel and 11-12 µm IR brightness temperature difference product

MODIS 0.65 µm visible channel and 11-12 µm IR brightness temperature difference product

 

Vog plume streaming off the island of Hawaii

January 10th, 2013 |
Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel data (above) showed a broad “vog” plume streaming westward off the Big Island of Hawaii on 10 January 2013. The primary source of this vog plume was likely the active Kilauea volcano — and the 3.64 µm shortwave IR image revealed a small “hot spot” at the summit of the volcano, which exhibited a brightness temperature value of 49.5º C (orange color enhancement).

The VIIRS 0.64 µm visible channel image with an overlay of 1-hour interval MADIS atmospheric motion vectors (or “satellite cloud-tracked winds”) showed the typical easterly trade wind flow regime that usually transports the vog plume westward away from the Hawaiian Islands (below). However, synoptic-scale disturbances that disrupt this trade wind flow can cause the vog plume to move over inhabitied portions of the islands, causing air quality problems.

Suomi NPP VIIRS 0.64 µm visible channel image + MADIS 1-hour interval atmospheric motion vectors

Suomi NPP VIIRS 0.64 µm visible channel image + MADIS 1-hour interval atmospheric motion vectors

Other examples of Hawaiian vog plumes can be found here on the CIMSS Satellite Blog.

Features of interest seen on VIIRS Day/Night Band imagery

January 9th, 2013 |
Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR images

A comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel data at 08:36 UTC (or 2:36 AM local time) on 09 January 2013 (above) showed a few items of interest on the DNB “visible image at night”:

  1. Even though there was deep convection with very cold (-70 to -75º C, black to light gray enhancement) cloud tops covering much of the eastern half of Texas, the diffuse glow of city lights could still be seen through the clouds
  2. Two elongated bright streaks off the southern tip of Texas: signatures of cloud-top illumination by lightning
  3. The relatively sparsely-populated area of far southeastern New Mexico and the adjacent New Mexico/Texas border region exhibited a pronounced signature of bright illumination
  4. In central New Mexico, where it was relatively cloud-free, portions of the Interstate highways — especially Interstate 40 that ran west-to-east between Albuquerque KABQ and Amarillo KAMA — appeared to be nearly continuously illuminated (presumably by a combination of small towns, truck stops, etc. and the headlights of vehicle traffic along the route)
POES AVHRR Cloud Top Height product

POES AVHRR Cloud Top Height product

Regarding point number 1 with the city light signatures, let’s attempt to explore how thick the clouds were over eastern Texas. An AWIPS image of the POES AVHRR Cloud Top Height product about an hour later at 09:50 UTC (above) indicated that the vast majority of the cloud tops were in the 11-13 km or 36,000-43,000 feet range. The VIIRS IR cloud top brightness temperatures as cold as -70 to -75 C agreed well with the temperature of the tropopause on the 12 UTC Fort Worth, Texas rawinsonde report (the tropopause height on that sounding was around 43,000 feet).

Surface station cloud ceiling and visibility data plotted on the VIIRS IR image (below) showed that overcast cloud bases nearest to the area of the coldest IR cloud top temperatures were 3500 feet above ground level at Temple KTPL and 5500 feet above ground level at Waco KACT. Outside of the main convective updraft cores the cloudiness was likely distributed within a number of discrete layers, but the fact that such a bright (albeit diffuse) signature of city lights could be seen through 30,000-40,000 feet of cloud layers is rather remarkable.

Suomi NPP VIIRS 11.45 µm IR image with surface reports of cloud ceiling and visibility

Suomi NPP VIIRS 11.45 µm IR image with surface reports of cloud ceiling and visibility

Regarding point number 3 with the bright lights seen across far southeastern New Mexico and the adjacent New Mexico/Texas border region, that is due to widespread drilling activity in the Avalon / Bone Spring oil shale region. While some natural gas flares might be present, the vast majority of the bright signatures are likely due to illuminated “man camps” that house the drilling support crews. Similar night-time illumination signatures are seen in the Eagle Ford and Bakken oil shale drilling regions.

===== 10 January Update =====

Suomi NPP VIIRS 0.7 µm Day/Night Band image

Suomi NPP VIIRS 0.7 µm Day/Night Band image

The deep convection persisted off the coast of Texas into 10 January — a Suomi NPP VIIRS 0.7 µm Day/Night Band image at 08:17 UTC or 2:17 AM local time (above) displayed a large number of elongated bright streaks as the sensor detected lightning-illuminated clouds.