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).

Hurricane Odile

September 15th, 2014
Advanced Dvorak Technique (ADT) plot for Hurricane Odile

Advanced Dvorak Technique (ADT) plot for Hurricane Odile

A time series plot of the Advanced Dvorak Technique (ADT) intensity estimate for Hurricane Odile (above) showed that the tropical cyclone went through a period of rapid intensification on 14 September 2014, reaching Category 4 on the Saffir-Simpson hurricane scale as it moved northwestward toward the southern tip of Baja California (Odile track map).

McIDAS images of GOES-15 10.7 µm IR channel data covering the 13-15 September period (below; click image to play animated GIF; also available as an MP4 movie file) showed Odile from the period of rapid intensification on the 14th to landfall on the 15th. Odile made landfall near Cabo San Lucas around 04:45 UTC on 15 September, with an estimated intensity of 110 knots — this ties with Hurricane Olivia (1967) as the strongest hurricane to make landfall in Baja California Sur during the modern satellite era.

GOES-15 10.7 µm IR channel images (click to play animated GIF)

GOES-15 10.7 µm IR channel images (click to play animated GIF)

Several hours prior to landfall, a comparison of GOES-15 10.7 µm IR and DMSP SSMIS 85 GHz microwave images from the CIMSS Tropical Cyclones site (below) indicated that Odile had a large outer eyewall at that particular point in time.

GOES-14 10.7 µm IR channel image and DMSP SSMIS 85 GHz microwave image

GOES-14 10.7 µm IR channel image and DMSP SSMIS 85 GHz microwave image

Even after several hours of traversing the rugged terrain of the Baja California peninsula, Odile continued to maintain hurricane intensity; the faint signature of an eye could still be seen on AWIPS II images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 22:34 UTC on 15 September (below).

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

GOES-14 SRSOR: Flash flooding in the Las Vegas, Nevada region

August 14th, 2014
GOES-14 0.63 µm visible channel images (click to play animation)

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

The GOES-14 satellite was placed into Super Rapid Scan Operations for GOES-R (SRSOR) mode on 14 August 2014, providing imagery at 1-minute intervals with the goal of monitoring the western US for convection and/or wildfire activity. McIDAS images of 0.63 µm visible channel data (above; click image to play animation; also available as an MP4 movie file) showed the development of clusters of slow-moving thunderstorms in the Las Vegas, Nevada region. These storms produced strong winds (gusts estimated at 60 mph) and heavy rainfall which caused flash flooding: Boulder City in far southern Nevada (located just east of Henderson, station identifier KHND) received 0.75 inch of rain in only 30 minutes. In addition to the state boundaries and yellow station identifiers, Interstate highways are drawn in red and State highways are cyan.

Another item of interest to note on the GOES-14 visible images: Lake Mead located to the east of Las Vegas was at an all-time record low level (1080.19 feet on 12 August) since it was filled back in the 1930s. The dark blue map outline represents the boundary of the lake as recently as the mid-1990s; the current area occupied by the darker water in Lake Mead’s Overton Arm (which extends northward) is drastically smaller in size, a result of the long-term severe to extreme drought.

AWIPS-2 images of the GOES-15 sounder Total Precipitable Water (TPW) derived product (below; click image to play animation) showed that these thunderstorms developed along a very sharp moisture boundary that was oriented roughly southwest to northeast across the area — TPW values of 30-40 mm (1.2-1.6 inches, yellow to red color enhancement) were seen east of the boundary, with TPW values of 10-20 mm (0.4-0.8 inch, shades of blue) west of the boundary.

GOES-15 sounder Total Precipitable Water derived product images (click to play animation)

GOES-15 sounder Total Precipitable Water derived product images (click to play animation)

Severe thunderstorm strikes Virginia campground

July 24th, 2014
GOES-13 10.7 µm IR channel images (click to play animation)

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

A supercell thunderstorm intensified as it moved eastward across the Chesapeake Bay (just ahead of an approaching surface cold front) on the morning of 24 July 2014 — as it reached the Virginia shore of the Delmarva Peninsula, it produced an EF-1 tornado and damaging straight line winds that were responsible for 2 fatalities and 36 injuries at the Cherrystone Family Camping Resort (located at the * symbol on the images). The storm also produced golf ball to baseball size hail (NWS damage survey | SPC storm reports). McIDAS images of GOES-13 10.7 µm IR channel data (above; click image to play animation; also available as an MP4 movie file) showed that the cloud-top IR brightness temperatures associated with the storm cooled quickly, from -45º C at 11:15 UTC to -64º C at 12:30 UTC. The temperature value was close to that of the tropopause (at a height of 15.4 km) on the 12 UTC rawinsonde data from Wallops Island, Virginia.

The corresponding GOES-13 0.63 µm visible channel images (below; click image to play animation; also available as an MP4 movie file) revealed the presence of an overshooting top at 12:30 UTC  (the time that the IR cloud-top brightness temperature values reached their minimum), which was also flagged by the automated Overshooting Tops detection algorithm.

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

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

AWIPS-II images of the NOAA/CIMSS ProbSevere product (below) followed the radar feature associated with the supercell thunderstorm. Around 11:30 UTC, the ProbSevere value was low, around 5-10%, a result of weak satellite-detected growth (and moderate glaciation) early in the storm’s life, along with low values of MRMS Maximum Expected Size of Hail (MESH). Environmental parameters from the Rapid Refresh model that were supportive of convection: MUCAPE exceeded 2200 J Kg and Shear values were greater than 30 m/s. As the cell tracked to the east and began to move over Chesapeake Bay, both MUCAPE and Shear gradually increased, to values near 2400 J/kg and 35 m/s, respectively. MRMS MESH was oscillating as the cell approached Chesapeake Bay, from 0.44 inches at 11:42 UTC (ProbSevere value of 10%) to 0.37 inches at 11:46 UTC (ProbSevere of 7%) to 0.65 inches at 11:48 UTC (ProbSevere of 29%) to 0.56 inches at 12:00 UTC (ProbSevere of 18%). As the storm moved over the Bay, MESH sizes jumped, to 0.86″ at 12:04 UTC (ProbSevere of 58%, the first crossing of the 50% threshold), to 1.02″ at 12:06 UTC (ProbSevere of 71%), to 1.86″ at 12:12 UTC (ProbSevere of 92% , the first crossing of the 90% threshold), and to 3.09″ (!) at 12:16 UTC (ProbSevere of 91%). At 12:20 UTC, when the Tornado Warning was issued, MRMS MESH was 3.51″ and ProbSevere remained at 91%. Thus, the warning was issued 16 minutes after ProbSevere exceeded 50%, and 8 minutes after ProbSevere was greater than 90%. The NWS storm survey indicated that the campsite fatalities occurred around 12:33 UTC, or 13 minutes after the issuance of the tornado warning.

NOAA/CIMSS ProbSevere product

NOAA/CIMSS ProbSevere product

The rapid intensification of the system as it moved over the Chesapeake begs the question: was instability diagnosed? In the animation below, GOES-13 sounder Derived Product Images (DPI) of Lifted Index (top panel) and CAPE (bottom panel) showed a rich source of instability just south of the cloud-obscuring convection (and ahead of the southward-moving cold front). Lifted Index values derived at 1147 UTC were around -6 at the mouth of the Chesapeake Bay (bright yellow enhancement); CAPE values were around 2500 J/kg (yellow and red enhancements).

GOES-13 Sounder DPI estimates of Lifted Index (top) and CAPE (bottom) [click to play animation]

GOES-13 Sounder DPI estimates of Lifted Index (top) and CAPE (bottom) [click to play animation]