“Industrial-enhanced” snow in Texas

February 10th, 2014

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

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

Examples of “industrial-enhanced snow” were seen in the Texas Panhandle region on 10 February 2014. In the overnight hours, areas downwind of agricultural plants near Borger (KBGD) received anywhere from 3.0 to 4.3 inches of snowfall. During the following morning and early afternoon hours, the particles contained within the hot, moist plume emanating from a factory located just northeast of Amarillo (KAMA) acted to glaciate the supercooled water droplets within the surrounding stratus deck — as the ice particles fell out of the cloud as snow, the cloud deck began to partially dissipate as seen in McIDAS images of 1-km resolution GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation).

A similar comparison of 4-km resolution GOES-15 and GOES-13 3.9 µm shortwave IR images (below; click image to play animation) confirmed that the plume streaming southward from the Amarillo area was indeed glaciated — the plume appeared significantly colder (brighter white) compared to the surrounding supercooled water droplet stratus cloud deck, which appeared warmer (darker gray) due to the shortwave IR channel’s sensitivity to the reflection of solar radiation off the liquid droplet cloud tops.

GOES-15 (left) and GOES-13 (right) 3.9 µm shortwave IR channel images [click to play animation]

GOES-15 (left) and GOES-13 (right) 3.9 µm shortwave IR channel images [click to play animation]

A comparison of AWIPS images of 1-km resolution Terra MODIS 0.65 µm visible channel, 3.7 µm shortwave IR channel, and 11.0 µm IR window channel images (below) provided a slightly sharper view than the GOES images. Again, the glaciated plume south of Amarillo appeared colder (brighter white) than the surrounding supercooled water droplet clouds; on the IR window channel image, the slightly warmer (darker gray) signature was due to the satellite sensing radiation from the warmer ground surface through the thinner glaciated areas of the cloud plume.

Terra MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR window channel images

Terra MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR window channel images

A 250-meter resolution Terrra MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; visualized using Google Earth) showed that the plume was drifting southward over parts of Interstate 27; one inch of snowfall was reported as far south as Happy, in the far northern part of Swisher county.

Terra MODIS true-color Red/Green/Blue (RGB) image

Terra MODIS true-color Red/Green/Blue (RGB) image

===== 11 February Update =====

On the folllowing day, a Terra MODIS true-color image at 17:44 UTC (below; visualized using Google Earth) provided a fantastic view of the mesoscale patch of snow cover southwest of Borger, Texas.

Terra MODIS true-color image (visualized using Google Earth)

Terra MODIS true-color image (visualized using Google Earth)

Blowing dust in Nebraska, Kansas, and Colorado

January 16th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

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

McIDAS images of 1-km resolution GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation) showed the development of widespread plumes of blowing dust across parts of southwestern Nebraska, northwestern Kansas, and eastern Colorado on 16 January 2014. Strong northerly to northwesterly winds in the wake of a morning cold frontal passage were  gusting over 40 knots across the entire region, with a peak wind gust of 64 knots in Broken Bow, Nebraska. These strong winds easily lofted the dry soils (the area was experiencing extreme drought conditions), which reduced surface visibilities and caused multiple vehicle accidents in Colorado and Kansas.

A closer view of the blowing dust using a 250-meter resolution Aqua MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below) clearly showed the source region of many of the dust plumes in southwestern Nebraska. The blowing dust plumes in eastern Colorado are not easily seen, due to patchy middle and high level clouds drifting over the region at that time.

Aqua MODIS true-color RGB image

Aqua MODIS true-color RGB image

A larger-scale view of the MODIS true-color image can be seen below, visualized using Google Earth.

Aqua MODIS true-color RGB image (viewed using Google Earth)

Aqua MODIS true-color RGB image (viewed using Google Earth)

For additional information and imagery of this blowing dust event, see the RAMMB GOES-R Proving Ground blog.

Severe thunderstorms over northeastern Montana

July 8th, 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)

Severe thunderstorms developed during the afternoon hours across parts of northeastern Montana on 08 July 2013. A comparison of McIDAS images of 1-km resolution GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation) showed the early stages of development of the storm that went on to produce large hail (up to 3 inches in diameter) and straightline winds from a macroburst gusting as high as an estimated 95 mph (SPC storm reports | NWS Glasgow public information statement).Some locations also received heavy rain (as much as 1.87 inches in a 1 hour period) that produced flash flooding. One interesting feature seen on the visible imagery was a region of inflow feeder bands along the southern flank of the developing thunderstorm as it was northwest of Jordan (station identifier KJDN).

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data with overlays of SPC storm reports (below; click image to play animation) revealed the formation of an “enhanced-V” storm top signature with the storm as it was north of Jordan, which is usually an indicator that a storm is or is about to produce severe weather in the form of large hail, tornadoes, or damaging winds.

GOES-13 10.7 µm IR channel images with hail and severe wind gust reports (click image to play animation)

GOES-13 10.7 µm IR channel images with hail and severe wind gust reports (click image to play animation)

A closer view using 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 20:30 UTC (below) showed a textbook example of a well-defined enhanced-V signature on the IR image. The coldest cloud-top IR brightness temperature in the overshooting top region was -69º C (black color enhancement), while the IR brightness temperature in the nearby upstream “warm wake” region was -44º C (darker green color enhancement), making for an impressively large 25º C “delta-T” value. About 1 hour later this storm began to produce 1.75 inch diameter hail in Garfield county (north of Jordan).

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

A comparison of the VIIRS IR image with the corresponding GOES-13 IR image (below) demonstrated the advanrages of using polar-orbiter satellite date for severe storm identification: (1) with higher spatial resolution, severe storm signatures suchas the “enhanced-V” are much better defined, and (2) there is no “parallax shift” associated with the large viewing angle from geostationary satellites located at the Equator.

Suomi NPP VIIRS 11.45 µm IR channel and GOES-13 10.7 µm IR channel images

Suomi NPP VIIRS 11.45 µm IR channel and GOES-13 10.7 µm IR channel images

===== 10 July Update =====

A comparison of before (04 July) and after (10 July) 250-meter resolution MODIS true-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below; displayed using Google Earth) revealed the extensive hail damage swath that was located from the north and northeast to the east and southeast  of Jordan, Montana (yellow arrows). At its widest point in far southern McCone county, the hail swath appeared to be at least 10-12 km (6-7 miles) wide.

Before (04 July) and after (10 July) MODIS true-color RGB images showing the hail damage swath

Before (04 July) and after (10 July) MODIS true-color RGB images showing the hail damage swath

Severe weather in the Oklahoma City area

May 31st, 2013
GOES-14 sounder Convective Available Potential Energy (CAPE) product (click image to play animation)

GOES-14 sounder Convective Available Potential Energy (CAPE) product (click image to play animation)

Only 11 days after the devastating EF-5 tornado that struck Moore, Oklahoma, another round of severe weather brought tornadoes (including the EF-5 El Reno tornado) large hail (up to 2.5 inches in diameter), damaging winds (gusts as high as 87 mph), and heavy rain that led to flash flooding to the Oklahoma City area on 31 May 2013 (SPC storm reports| NWS Norman summary). AWIPS images of the 10-km resolution GOES-14 sounder Convective Available Potential Energy (CAPE) derived product (above; click image to play animation) showed the trend of rapid destabilization across the region during the hours leading up to convective initiation — widespread CAPE values in the 5000-6000 J/kg range were seen (lighter purple color enhancement).

Once convective initiation began the storm growth was explosive, as revealed by McIDAS images of 1-km resolution GOES-14 0.63 µm visible channel data (below; click image to play animation; also available as a QuickTime movie). The GOES-14 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes. Complex storm-top structures were evident in the visible imagery, including numerous overshooting tops and anvil gravity waves. In addition, later in the animation a smoke plume can be seen approaching from the west (originating from a large fire that was burning in New Mexico). OKC denotes the location of Oklahoma City.

GOES-14 0.63 µm visible channel images (click image to play animation)

GOES-14 0.63 µm visible channel images (click image to play animation)

Not long after the first large thunderstorms began to develop west of Oklahoma City, a 1-km resolution POES AVHRR 12.0 µm IR channel image (below) displayed cloud-top IR brightness temperatures as cold as -78º C at 21:51 UTC or 4:51 PM local time (shortly before the first report of 1.25-inch diameter hail at 21:59 UTC). A 1-km resolution AVHRR vs 4-km resolution GOES-14 IR image comparison demonstrated two important advantages of polar-orbiter satellite imagery: (1) more accurate depiction of the coldest overshooting tops (-78º C on AVHRR, vs -64º C on with GOES-14), and (2) limited parallax error, helping to more accurately determine the true location of the overshooting tops.

POES AVHRR 12.0 µm IR channel image

POES AVHRR 12.0 µm IR channel image

AWIPS image combinations of GOES-14 10.7 µm IR channel data with overlays of Cloud Top Cooling (CTC) Rate and Overstooting Top (OT) Detection products (below; click image to play animation) showed the following: (1) the first region of significant CTC that was flagged with the newly-developing Oklahoma City storm was at 21:15 UTC, with a CTC rate of -8.8º C compared to the previous GOES-14 IR image; (2) the CTC rate increased to -26.9º C for the following 21:25 UTC IR image; (3) the CTC rate jumped to a remarkable -60.2º C for the following 21:32 UTC IR image (an indicator of the explosive rate of storm development); (4) OT detection icons began to appear once GOES-14 IR images exhibited IR brightness temperature values of -60º C and colder (beginning at 21:55 UTC).

GOES-14 10.7 µm IR image + Cloud Top Cooling Rate and Overshooting Top Detection products (click image to play animation)

GOES-14 10.7 µm IR image + Cloud Top Cooling Rate and Overshooting Top Detection products (click image to play animation)

===== 02 June Update =====

A comparison of before/after (14 May/02 June) 250-meter resolution true-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) showed the damage path from the 31 May El Reno, Oklahoma tornado. The lakes and rivers appear brighter on the 02 June image due to sun glint off the bodies of water (the sun-satellite geometry was different than it was on 14 May).

Before/after (14 May/02 June) MODIS true-color Red/Green/Blue (RGB) images

Before/after (14 May/02 June) MODIS true-color Red/Green/Blue (RGB) images

The tornado damage path is also highlighted on the 02 June MODIS true-color RGB image, viewed using Google Earth (below).

MODIS true-color RGB image (viewed using Google Earth)

MODIS true-color RGB image (viewed using Google Earth)