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).

NASA Global Hawk flight to study Tropical Storm Dolly

September 2nd, 2014
NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

The NASA Global Hawk aircraft are once again being used to study tropical cyclones during the 2014 season. As part of CIMSS participation in GOES-R Proving Ground activities, a Global Hawk flight path tool was developed to display important parameters such as ACHA Cloud Top Height, Tropical Overshooting Tops, and lightning (above; click image to play animation). Global Hawk pilots use this product to navigate the aircraft around locations of potential turbulence.

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

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

To support the Global Hawk investigation of Tropical Storm Dolly on 02 September 2014, the GOES-13 satellite was placed into Rapid Scan Operations (RSO) mode to provide images at 5-7 minute intervals. GOES-13 0.63 µm visible channel images (above; click to play animation) and 10.7 µm IR channel images (below; click to play animation) are shown which cover the 3-hour period of the Global Hawk flight segment shown above. There is evidence of overshooting tops seen in the visible imagery, with cloud-top IR brightness temperatures of -80º C and colder (purple color enhancement).

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-13 10.7 µm IR channel images (click to play animation)

Tropical Storm Dolly in the southern Gulf of Mexico

September 2nd, 2014
Suomi NPP VIIRS Day Night Band (0.70 µm) image (click to enlarge)

Suomi NPP VIIRS Day Night Band (0.70 µm) image (click to enlarge)

Tropical Storm Dolly has formed in the western Gulf of Mexico. The Suomi NPP VIIRS Day Night Band imagery, above, shows the exposed low-level swirl of the storm (then still a tropical depression). North-northwesterly shear (shown here, from this site) means the deep convection (shown below) is displaced to the east of south of the the low-level circulation (click here for a toggle between the Day Night Band and the 11.45µm imagery). Cloud-top IR brightness temperatures from VIIRS were as cold as -87º C. ASCAT winds from 0230 UTC show a region of tropical storm-force winds associated with convection east and north of the circulation center.

Suomi NPP VIIRS Infrared (11.45 µm) image (click to enlarge)

Suomi NPP VIIRS Infrared (11.45 µm) image (click to enlarge)

Early-morning visible imagery from GOES-13, below, shows the large area of convection over the southern Gulf. The NHC-reported positions of the storm at 0900 UTC and 1500 UTC (22.6º N, 94.8º W and 23.4º N, 96.5º, respectively) are indicated by the red boxes on the images. Strong convection just south of the surface circulation developed at sunrise, obscuring the low-level swirl. That strong convection is especially apparent in the GOES-13 10.7 imagery, at bottom. GOES IR Brightness Temperatures were as cold as -84º C in the animation. (For more on Dolly from the National Hurricane Center, see this link).

GOES-13 Visible Imagery (0.63 µm) (click to animate)

GOES-13 Visible Imagery (0.63 µm) (click to animate)

GOES-13 Infrared Imagery (10.7 µm) (click to animate)

GOES-13 Infrared Imagery (10.7 µm) (click to animate)

Hurricane Cristobal and the Saharan Air Layer

August 28th, 2014
Meteosat-10 Saharan Air Layer product (click to play animation)

Meteosat-10 Saharan Air Layer product (click to play animation)

The CIMSS Saharan Air Layer (SAL) product (above; click image to play animation) showed a large pocket of SAL (yellow to red color enhancement) drifting westward over the far western Atlantic Ocean and toward the Gulf of Mexico on 28 August 2014.

On GOES-13 0.63 µm visible channel images (below; click image to play animation), the hazy signature of the SAL dust could be seen surging westward, not far to the south of Category 1 intensity Hurricane Cristobal.

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

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

The SAL also exhibited a warm/dry signature (yellow to orange color enhancement) on the corresponding GOES-13 6.5 µm water vapor channel images (below; click image to play animation).

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)

At 17:16 UTC, a Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image from the SSEC RealEarth web map server (below) showed that Hurricane Cristobal had developed an eye formation.

Suomi NPP VIIRS true-color image

Suomi NPP VIIRS true-color image

A comparison of AWIPS-2 images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data (below) revealed that the coldest cloud-top IR brightness temperatures (-77º C, lighter gray color enhancement) were located within convection just southwest and southeast of the eye.

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

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