GOES Cloud Top Cooling Rate product used for SPC Mesoscale Discussion

September 17th, 2014
Storm Prediction Center Mesoscale Discussion #1724

Storm Prediction Center Mesoscale Discussion #1724

Using the GOES-R Cloud Top Cooling Rate product (applied to GOES-13 data), the Storm Prediction Center issued a Mesoscale Discussion (above) highlighting the risk of strong thunderstorms producing hail and/or strong wind gusts over parts of the Georgia/South Carolina border region on 17 September 2014. According to the SPC storm reports, there was hail up to 1.0 inch in diameter in addition to some tree and power line damage in southern South Carolina.

AWIPS II image combinations of the Cloud Top Cooling (CTC) rate product (colors) and the GOES-13 10.7 µm IR channel gray-scale images  (below; click image to play animation) showed that CTC rate values for the storm north of Augusta, Georgia (KAGS) at 19:00 UTC were as high as -16º C per 15 minutes; at 19:15 UTC, the CTC rate value for that storm was as high as -39º C per 15 minutes. The first Severe Thunderstorm Warning for this storm was later issued at 19:34 UTC.

Cloud Top Cooling Rate (colors) and GOES-13 10.7 µm IR (grayscale) images [click to play animation]

Cloud Top Cooling Rate (colors) and GOES-13 10.7 µm IR (grayscale) images [click to play animation]

GOES-13 10.7 µm IR channel images (below; click image to play animation) showed the rapidly cooling cloud-top IR brightness temperatures associated with these thunderstorms as they moved southeastward and intensified: the coldest value for the aforementioned thunderstorm was -40º C at 19:00 UTC, dropping to -62º C by 20:45 UTC.

GOES-13 10.7 µm IR channel images [click to play animation]

GOES-13 10.7 µm IR channel images [click to play animation]

About an hour later, another Severe Thunderstorm Warning was issued at 20:30 UTC for a storm near and south of Orangeburg, South Carolina (KOGB).

Powerful early October storm: blizzard conditions, and severe thunderstorms

October 5th, 2013
GOES-13 6.5 µm water vapor channel images (click to play animation)

GOES-13 6.5 µm water vapor channel images (click to play animation)

An unusually intense (by early October standards) mid-latitude cyclone produced a variety of weather extremes across the parts of the north-central US during the 04 October to 05 October 2013 period. In the cold sector of the storm system, western South Dakota received record-breaking snowfall and prolonged blizzard conditions (NWS Rapid City news story), with widespread power outages and livestock losses being two of the major impacts. The early evolution of the storm could be seen on 4-km resolution GOES-13 6.5 µm water vapor channel images (above; click image to play animation). Surface weather symbols (including precipitation type) are also plotted on the water vapor images. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode during much of this time, providing images as frequently as every 5-10 minutes.

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)

In the warm sector of the storm system, severe thunderstorms produced numerous tornadoes and hail as large as 2.75 inches in diameter (SPC storm reports), primarily across eastern Nebraska into Iowa. A very large tornado produced EF-4 damage in the Wayne, Nebraska area — the development of this storm could be seen on 1-km resolution 0.63 µm visible channel images (above; click image to play animation) and 4-km resolution 10.7 µm IR channel images (below; click image to play animation) from the GOES-15 (GOES-West) and GOES-13 (GOES-East) satellite perspectives. Wayne (station identifier KLCG) is located in the center of the visible and IR images; note that the hourly plotted weather observations for Wayne disappeared after 22 UTC, due to the fact that the airport weather instruments were damaged by the tornado (NWS Omaha news story).

GOES-15 (left) and GOES-13 (right) 10.7 µm IR channel images (click to play animation)

GOES-15 (left) and GOES-13 (right) 10.7 µm IR channel images (click to play animation)

GOES-13 0.63 µm visible channel images with overlays of the corresponding University of Wisconsin GOES-13 IR Cloud Top Cooling Rate (CTCR) product (below; click image to play animation) indicated that CTCR values exceeded 30 degrees Kelvin per 15 minutes (darker blue color enhancement) at 20:45 UTC as the thunderstorm that produced the Wayne tornado was rapidly developing in northeastern Nebraska.

GOES-13 0.63 µm visible images + IR Cloud Top Cooling Rate (click to play animation)

GOES-13 0.63 µm visible images + IR Cloud Top Cooling Rate (click to play animation)

===== 07 October Update =====

High spatial resolution imagery from low Earth orbit (LEO) or “polar-orbiting” satellites can be useful for post-case analysis — with this particular storm, helping to determine the areal coverage of the resulting snowfall, and identifying a tornado damage path.

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

Once the large cloud shield associated with the storm system moved eastward, a comparison of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) images from 06 October (above) showed the widespread area of snow cover (which appeared as darker shades of red on the RGB image) over the western third of South Dakota as well as adjacent portions of Wyoming, Nebraska, North Dakota, and Montana. Terrain had an important influence in both the amount and the coverage of snowfall — it is especially interesting to note the areas of bare ground (shades of cyan in the RGB image) immediately downwind (south and southwest) of the Black Hills, where downsloping winds helped keep the precipitation type as rain (AWIPS-2 animation including topography). Aided by upslope flow, as much as 58 inches of snowfall was reported in the northern Black Hills of South Dakota. Note that much of the Black Hills appear darker on the visible and false-color images, due to the high density of coniferous trees — but there was still significant snow cover on the ground.

In addition, a comparison of before (28 September) and after (07 October) 250-meter resolution MODIS true-color RGB images from the SSEC MODIS Today site (below) revealed the southwest-to-northeast oriented damage path from the large tornado which produced EF-4 damage in the Wayne, Nebraska area (NWS Omaha news story).

MODIS true-color RGB images

MODIS true-color RGB images

Severe thunderstorms in northwestern Kansas

August 5th, 2013
GOES-13 0.63 µm visible channel images with overshooting top detection icons (click image to play animation)

GOES-13 0.63 µm visible channel images with overshooting top detection icons (click image to play animation)

 

AWIPS images of 1-km resolution GOES-13 0.63 µm visible channel images with automated overshooting top detection icons (above; click image to play animation) showed the development of a large mesoscale convective system across northwestern Kansas during the afternoon hours on 05 August 2013. Note that the surface air temperature at Goodland, Kansas (KGLD) dropped from 91º F at 19 UTC to 69º F at 20 UTC (with southeasterly winds gusting to 34 knots).

4-km resolution GOES-13 10.7 µm IR channel images with automated overshooting top detection icons (below; click image to play animation) revealed the formation of a very broad and well-defined “enhanced-V” storm top signature, with cloud-top IR brightness temperatures becoming as cold as -80º C at 23:15 UTC. Overshooting top detection began after 19:45 UTC, once GOES-13 cloud-top IR brightness temperatures became -71º C or colder.

GOES-13 10.7 µm IR channel images with overshooting top detection icons (click image to play animation)

GOES-13 10.7 µm IR channel images with overshooting top detection icons (click image to play animation)

During the early stages of convective development, GOES-13 10.7 µm IR images combined with 15-minute cloud top cooling rates (below) showed the development of significant cloud top cooling rates along the Colorado/Kansas border area at 18:15 UTC (prior to the formation of weak, brief landspout tornadoes just northeast of Goodland, Kansas during the 18:28-18:40 UTC period) — a maximum cloud top cooling rate of 35.3º C in 15 minutes was detected at 18:45 UTC.

GOES-13 10.7 µm IR channel images with Cloud Top Cooling Rates

GOES-13 10.7 µm IR channel images with Cloud Top Cooling Rates

A comparison of 1-km resolution Soumi NPP VIIRS 11.45 µm IR channel and 4.-km resolution GOES-13 10.7 µm images (below) demonstrated the ability of higher spatial resolution VIIRS data to detect much colder IR brightness temperatures associated with the more vigorous overshooting tops (-82º C on VIIRS, vs -71º C on GOES). In addition, a northwestward GOES image parallax shift was seen, due to to the large viewing angle of the GOES-13 satellite positioned at 75º W longitude. Shortly after the time of these images, this storm produced hail of 1.0 inch in diameter at 20:11, 20:21, and 20:54 UTC (SPC storm reports)

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

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

Comparisons of 1-km resolution POES AVHRR Cloud Top Temperature and Cloud Top Height products at 20:21 UTC (above) and 21:16 UTC (below) showed that the coldest cloud top temperatures (-85º C and -87º C, respectively) were seen in regions where the maximum cloud top height values were generally around 15 km. It is likely that the most vigorous overshooting tops associated with the coldest cloud top temperature values were as much as 2-3 km higher than this mean 15 km thunderstorm anvil cloud top height. Conversely, cloud top height values were around 13 km in the “warm wake” region immediately downwind of the coldest overshooting tops.

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)