*Update #2: * **Effective immediately; all the GOES-13 (GOES-East)
sounding products are ceased to produce and stop distribution as we are
experiencing an anomaly with the sounder instrument. Engineers are
investigating the problem. We will inform you when we resume our normal
*Update #1: * GOES-13 (GOES-East) Sounder IR Data Outage
*Topic:* GOES-13 (GOES-East) Sounder IR Data Products Outage
*Date/Time**Issued:*November 20, 2015 1955Z*
*Product(s) or Data Impacted:*
GOES-13 (GOES-East) Sounder data
Blended Hydrometorological Products – Blended TPW
Microwave AWIPS Products – Blended TPW
Microwave McIDAS Products – Blended TPW
GOES Gridded Cloud Product
GOES VARiable data
AFEP/Ingestor – GOES
Single Field of View BUFR
Single Field of View SDPI for AWIPS
Single Field of View TPW
Sounding ASOS SCSP
*Date/Time of Initial Impact:*November 20, 2015 0922Z **
*Date/Time of Expected End:* TBD
*Length of Outage:* TBD
*Details/Specifics of Change:*GOES-13 (GOES-East) Sounder instrumentis experiencing an anomaly. Engineers are investigating the problem. GOES-13 Sounder IR data is not available. **Effective immediately all the GOES-13 (GOES-East) sounding products are ceased to produce and stop distribution as we are experiencing an anomaly with the sounder instrument. Engineers are investigating the problem. We will inform you when we will resume our normal operations.
The corresponding 4-km resolution GOES-15 Infrared (10.7 µm) images (below) revealed that cloud-top IR brightness temperatures quickly cooled from -23º C at 2130 UTC to -42º C at 2200 UTC.There was a 30-minute gap in GOES-15 coverage from 2100 to 2130 UTC (due to a full disk scan), but a comparison of 1-km resolution NOAA-19 AVHRR Visible (0.63 µm) and Infrared (10.8 µm) caught the very early growth of the tornado-producing storm at 2115 UTC (below). The cloud-top IR brightness temperatures were as cold as -23º C at that time, indicating a high probability that cloud glaciation had begun. A timely overpass of the Suomi NPP satellite allowed a comparison of 375-meter resolution VIIRS Visible (0.64 µm) and Infrared (11.45 µm) images during the time that the tornado was srill on the ground (below). Once again, the strong slant of the storms due to increasing wind speeds aloft allowed the western/southwestern sides of the thunderstorm clouds to be brightly illuminated on the visible image. The coldest cloud-top IR brightness temperature was -51º C (yellow color enhancement), which was just shy of the -53º C tropopause temperature reported on the Oakland rawinsonde report at 12 UTC. A VIIRS true-color image of the storm visualized using RealEarth is shown below. The actual satellite overpass time was around 2151 UTC. GOES-15 sounder Lifted Index (LI) derived product images (below) showed the pockets of post-frontal instability over central California — LI values less than -4 C were seen (yellow color enhancement).
A severe hail-producing thunderstorm moved over northeast Nebraska before noon on 22 September (SPC Storm Reports). The region hit was just south of a Marginal Risk of Severe Weather (The update at 1630 UTC included the region of severe weather). The GOES-13 visible animation, above, shows the initial development occurring along a subtle cloud line aligned mostly east-west.
The NOAA/CIMSS ProbSevere model produces a probability that a developing thunderstorm will initially produce severe weather within the next sixty minutes. It consistently supplies information with a good lead time, and the storm on 22 September was no exception. The animation below shows the product for about an hour before the first storm report at 1408 UTC. The storm out of which the hail dropped was, at 1300 UTC, flagged as having a ProbSevere under 10%; values exceeded 10% at 1314 UTC and then jumped to 60+% at 1336 UTC (the first time that the value exceeded 50%) Values fluctuated between 60 and 80% between 1336 and 1400 UTC. After 1400 UTC, values increased into the mid-80s. The first report of hail was at 1408 UTC, 32 minutes after ProbSevere jumped above 50%. A severe thunderstorm warning for hail was issued at 1412 UTC.
The GOES Sounder Lifted index product, below, (also available here) showed the instability that was present over the central Plains.
Strong thunderstorms developed over the upper midwest ahead of a cold front in the afternoon of 2 August 2015. Large Hail (up to 4.25″ diameter in Ogemaw County Michigan) fell and strong winds were observed (up to 70 mph in Portage County Wisconsin) over parts of eastern Wisconsin and lower Michigan. (SPC Storm Report). The visible animation from GOES-13, top (available here as an mp4), shows the development of the storms.
The destabilization of the atmosphere was captured well with the GOES Sounder depiction of Lifted Index, shown above. Values exceeding -10º C were common in the moist air feeding into the developing thunderstorms. The GOES-R Legacy Atmospheric Profile (LAP) Algorithm for 2 August similarly shows the strong instability around Lake Michigan. Lifted Indices also exceeded -10º C.
The GOES-R LAP Algorithm (and the GOES-Sounder) can also compute Convective Available Potential Energy. Values for the GOES Sounder are shown above (they are routinely available here); those for the GOES-R LAP Algorithm are below. The GOES-13 Sounder showed values approaching 5000 J/kg. Values from the GOES-R LAP Algorithm show values around 3000 J/kg. Note how the spatial extent of the instability in both CAPE and LI fields matches well in the Sounder and LAP fields.
The storms occurred on a day shortly after the Full Moon, so they were well-illuminated for the Suomi NPP Day Night Band imagery, shown below for 0751 UTC. The parallel lines of clouds over eastern Ohio and western Pennsylvania marks a wind-shift line as shown in this plot that includes surface observations. Those parallel lines of clouds were persistent, as they were present in the 0603 UTC Day Night Band imagery as well (Click here for a toggle between 0613 and 0751 UTC.)
The 11.45 µm Imagery from Suomi NPP shows evidence of overshooting tops persisting at night.