Smoke from Canadian fires over the Great Lakes region

June 24th, 2010 |
GOES-13 0.63 µm visible images

GOES-13 0.63 µm visible images

AWIPS images of GOES-13 0.63 µm visible channel data (above) showed widespread hazy conditions over much of the Great Lakes region during the afternoon and evening hours on 24 June 2010. The thick haze became more evident during the late afternoon and early evening hours, as a more favorable sun angle for “forward scattering” helped to highlight the airborne aerosols.

The MODIS Aerosol Optical Depth (AOD) product (below) indicated that AOD values over much of the Great Lakes region were in the 0.6 to 0.8 range, with a larger area of AOD values near 1.0 over south-central Canada. A large number of wildfires had been burning across the northern Prairie Provinces of Canada during the preceding days — so could this thick haze seen over the Great Lakes be due to smoke from Canadian fires?

MODIS Aerosol Optical Depth (AOD) product

MODIS Aerosol Optical Depth (AOD) product

A comparison of 1-km resolution MODIS 0.65 µm visible and 3.7 µm shortwave IR images (below) depicted a number of smoke plumes and “hot spots” (orange to yellow color enhancement) from fires that were still burning on 24 June over northern Saskatchewan and Manitoba. However, on this day, surface winds were from the southeast, advecting the smoke plumes toward the northwest.

MODIS 0.65 µm visible channel and 3.7 µm shortwave IR images

MODIS 0.65 µm visible channel and 3.7 µm shortwave IR images

A comparison of the 1-km resolution MODIS and AVHRR 3.7 µm shortwave IR images with the corresponding 4-km resolution GOES-13 3.9 µm shortwave IR image (below) demonstrated the improvement in fire hot spot detection and geo-location using the 1-km resolution polar orbiting satellite data — note the mapping errors on the GOES-13 image due to the large viewing angle from the geostationary satellite.

MODIS 3.7 µm,  AVHRR 3.7 µm, and GOES-13 3.9 µm shortwave IR images

MODIS 3.7 µm, AVHRR 3.7 µm, and GOES-13 3.9 µm shortwave IR images

Over southern Wisconsin, the thick smoke contributed to colorful yellow to orange sunset, as seen using the AOSS rooftop camera at the University of Wisconsin – Madison (below; also available as a QuickTime animation).

AOSS rooftop camera image (facing to the west)

AOSS rooftop camera image (facing to the west)

Lidar data from the UW-Madison SSEC Lidar Group (below) showed enhanced backscatter within the 1-2 km altitude layer during the daytime hours.

Lidar backscatter data from the SSEC Lidar Group at UW-Madison

Lidar backscatter data from the SSEC Lidar Group at UW-Madison

NOAA ARL HYSPLIT back trajectories (below) confirmed that air parcels arriving over Madison, Wisconsin on 24 June had likely passed over the parts of northern Saskatchewan 2-3 days earlier, where active fires had been burning for several days.

NOAA ARL HYSPLIT backward trajectories (arriving over Madison, Wisconsin)

NOAA ARL HYSPLIT backward trajectories (arriving over Madison, Wisconsin)

Gulf of Mexico oil slick update

June 19th, 2010 |
MODIS true color and false color RGB images

MODIS true color and false color RGB images

The comparison of a 250-meter resolution MODIS true color Red/Green/Blue (RGB) image (created using Bands 1/4/3) with the corresponding MODIS false color (created using Bands 7/2/1) image from the SSEC MODIS Today site (above) showed intricate details of the surface oil slick in the far northern Gulf of Mexico on 19 June 2010. The glaciated cloud tops of deep convection appeared as darker shades of cyan on the false color image.

On the true color image, note the small black features located over the bright oil slick, toward the lower left portion of the image — this was smoke from small fires which were apparently being set to burn off some of the surface oil (the fire hot spots show up as shades of pink on the false color image). This was Day 61 following the explosion of the Deepwater Horizon offshore oil rig on 20 April.

The MODIS true color image displayed using Google Earth (below; courtesy of Liam Gumley, CIMSS) offers a different perspective and a larger-scale view of the oil slick.

MODIS true color image (displayed using Google Earth)

MODIS true color image (displayed using Google Earth)

Convective outflow boundaries: sometimes innocuous, sometimes important

June 19th, 2010 |
GOES-13 0.63 µm visible images

GOES-13 0.63 µm visible images

McIDAS images of GOES-13 0.63 µm visible channel data (above) showed the development of a distinct convective outflow boundary along the coast of North Carolina on 17 June 2010. While appearing interesting on the satellite imagery, this outflow boundary dissipated quickly and did not appear to have any major impact on sensible weather or subsequent convective development.

A NOAA-19 false color Red/Green/Blue (RGB) image created using AVHRR channels 01/02/04 (below) offered another view of the outflow boundary at 18:53 UTC.

NOAA-19 false color RGB image (using AVHRR channels 01/02/04)

NOAA-19 false color RGB image (using AVHRR channels 01/02/04)

In contrast, another series of GOES-13 0.63 µm visible images (below) showed the development of a new convective cell as 3 outflow boundaries intersected over eastern Mississippi on 19 June 2010. This new convective cell produced hail of 1.00 inch in diameter (plotted as “A100” on the image) at 20:00 UTC and strong wind gusts that downed multiple trees (plotted as “W” on the image) at 21:27 UTC.

GOES-13 0.63 µm visible images (with severe weather reports)

GOES-13 0.63 µm visible images (with severe weather reports)

AWIPS images of GOES-13 sounder Convective Available Potential Energy or CAPE product (below) indicated that the region of convective development was quite unstable during this period, with widespread CAPE values of around 6000 Joules per kilogram (darker purple color enhancement).

GOES-13 sounder CAPE derive product images

GOES-13 sounder CAPE derive product images

A MODIS false color RGB image using bands 01/07/07 (below) could be utilized to help discriminate areas of convection that were completely glaciated (darker red color enhancement) from those that were not (brighter white enhancement).

MODIS false color RGB image (using bands 01/07/07)

MODIS false color RGB image (using bands 01/07/07)

Very large hail in the Texas Panhandle region

June 12th, 2010 |
POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product

Severe thunderstorms that developed in the vicinity of a stationary frontal boundary over the northern Texas Panhandle region on 12 June 2010 produced unusually large hailstones (some as large as 5.5 to 6.0 inches in diameter) — additional details of this event can be found at the NWS Amarillo TX website. AWIPS images of the 1-km resolution POES AVHRR Cloud Top Temperature product (above) indicated that CTT values were as cold as -81º C at 19:42 UTC and -80º C at 20:07 UTC. By comparison, the coldest IR brightness temperatures seen on 4-km resolution GOES-13 10.7 µm imagery were -66º C.

The University of Wisconsin Convective Initiation product (below) flagged that particular area of developing convection at 18:40 UTC — about an hour before it produced the first report of 1.0 inch diameter hail at 19:40 UTC (and almost 2 hours before the report of 6.0 inch diameter hail at 20:32 UTC):

GOES-13 10.7 µm IR images (grayscale) + UW Convective Initiation product (colored boxes)

GOES-13 10.7 µm IR images (grayscale) + UW Convective Initiation product (colored boxes)