For the second consecutive day, the GOES-14 satellite was placed into Super Rapid Scan Operations for GOES-R (SRSOR) mode to monitor the ongoing severe bow echo/low-end derecho event that was moving across the eastern US on 13 June 2013. GOES-14 0.63 µm visible channel images at 1-minute intervals (above; click image to play animation; also available as a QuickTime movie) revealed the emergence of a well-defined shelf cloud across Virginia and North Carolina, which marked the leading edge of the gust front moving out ahead of the line of severe thunderstorms. According to the SPC storm reports, these storms produced a wide swath of damaging winds (with gusts as high as 78 mph in Virginia), along with some large hail (up to 2.75 inches in diameter in Maryland).
The GOES-14 satellite was placed into Super Rapid Scan Operations for GOES-R (SRSOR) mode to monitor the development of severe weather over a rare SPC High Risk region on 12 June 2013. In SRSOR mode, images were available at 1-minute intervals (compared to the routine 15-minute image interval). The development of numerous large thunderstorms can be seen on GOES-14 SRSOR 0.63 µm visible channel images (above; click image to play animation; also available as a QuickTime movie). These storms produced tornadoes, large hail, and damaging winds across parts of Minnesota, Iowa, Wisconsin, and Illinois (SPC storm reports). One item of interest revealed on the 1-minute imagery was the appearance of “feeder band” clouds that were flowing into the western edge of the large thunderstorm located over northeastern Iowa during the 20:15 – 20:58 time period; without the 1-minute temporal resolution, such subtle mesoscale features would be difficult if not impossible to identify on conventional 15-minute imagery. Numerous overshooting tops could also be seen on some of the larger storms.
During the SRSOR period, there were breaks in the 1-minute interval coverage to allow for tasks such as satellite “station-keeping” – and the longest break occurred between 19:41 UTC and 20:15 UTC (below). You can see that during this particular 34-minute period, considerable convective development occurred in areas such as northwestern Illinois. With current Routine GOES scanning schedules, there is a similar 30-minute gap in coverage over the Continental US (CONUS) which occurs every 3 hours during a full disk scan of the Earth. It is important to note that with the Advanced Baseline Imager (ABI) instrument on the next-generation GOES-R satellite there will be no such long gaps in the imagery — in fact, during high-impact weather events such as this one, images will be available over special mesoscale sectors every 30 seconds.
The GOES-13 sounder Convective Available Potential Energy (CAPE) derived product (below; click image to play animation) showed that there was considerable instability (CAPE values of 4000-5000 J/kg, violet color enhancement) that developed during the afternoon hours across much of southeastern Iowa and northern Illinois, in the warm sector of the area of low pressure that was developing over northeastern Iowa.
GOES-13 became the operational GOES-East satellite once again at 15:45 UTC on 10 June 2013 (following recovery from an anomaly on 22 May) — the multi-panel image above shows all 19 bands of the GOES-13 Sounder along with all 5 bands of the GOES-13 Imager at that time.
The images below show the GOES Sounder 7.4 µm water vapor channel data using AWIPS, and the footprint change from GOES-14 at 14:46 UTC to GOES-13 at 15:46 UTC is obvious.
A comparison of all 19 bands of the Sounder instrument on GOES-14 and GOES-13 (below) shows some improvement in noise in a few of the bands (due to an “outgas” procedure being performed on the GOES-13 Sounder during recovery from the anomaly).
The transition from GOES-14 to GOES-13 is also shown above, using McIDAS images of 0.63 µm visible channel data from the Imager instrument. Once again, the image perspective is different, due to the fact that GOES-14 is positioned over the Equator at 105 W longitude, and GOES-13 is at 75 West longitude. This difference in satellite viewing perspective is very apparent when comparing the Full Disk views of 0.63 µm visible channel images from GOES-14 at 14:45 UTC and GOES-13 at 17:45 UTC (below).
Tropical Storm Andrea (the first Atlantic Basin tropical cyclone of the 2013 season) formed in the eastern Gulf of Mexico on 05 June 2013. GOES-14 10.7 µm IR images from the CIMSS Tropical Cyclones site (above) showed that the center of Andrea was located along the western edge of deep convection, which exhibited numerous Tropical Overshooting Tops. Andrea was forecast to move northeastward into an environment characterized by increasing values of deep layer wind shear, so rapid intensification was not anticipated.
Due to partial obscuration by high clouds from the deep convection, the low-level center of circulation was difficult to identify on McIDAS images of GOES-14 0.63 µm visible channel data (below; click image to play animation).
Early in the day, an AWIPS comparison of 1-km resolution MODIS 11.0 µm IR and 4-km resolution GOES-14 10.7 µm IR images (below) demonstrated that the higher spatial resolution data was able to display the small yet very cold areas of tropical overshooting tops — the coldest IR brightness temperatures seen on the MODIS image were -87º C (violet color enhancement), compared to -78º C (lighter gray color enhancement) on the corresponding GOES-14 IR image.
===== 06 June Update =====
1-km resolution POES AVHRR 12.0 µm IR channel and 0.86 µm visible channel images (above) showed Andrea off the west coast of Florida at 15:05 UTC. There was some suggestion of a closed eye beginning to form on the visible image.
1-km resolution GOES-14 0.63 µm visible channel images (below; click image to play animation) revealed that the center of circulation became more well-defined as the tropical storm made landfall around 21:40 UTC (5:40 PM local time) near Steinhatchee, Florida. Maximum sustained winds at landfall were estimated to be 65 mph.