On 20 November, at 0922 UTC, the GOES-13 Sounder experienced an anomaly (the GOES-13 Sounder had Filter Wheel anomalies in 2012 as well: Link; Link). GOES Engineers determined that the Filter Wheel had stopped moving (the filter wheel aligns the infrared detectors with the incoming data) so data were not scanned. The image above shows the 13.4 µm (a CO2 channel) image before and after the anomaly. All 18 infrared channels are affected; the visible channel (band 19) continues sending usable data. GOES Engineers continue to investigate the problem. GOES Sounder derived products (such as Total Precipitable Water) are affected, and are no longer being produced or disseminated (Link). From an email from SSD: (Link)

*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
operations.

*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
N-AWIPS Ingest
Single Field of View BUFR
Single Field of View SDPI for AWIPS
Single Field of View TPW
Sounding ASOS SCSP
Web Pages

*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.

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Update 19 January 2016
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GOES-14 is scheduled to broadcast 1-minute SRSO-R data starting 1 February. GOES-14 will be activated on 25 January, with a maneuver shortly thereafter. It is likely that GOES-14 Sounder data will be broadcast from 1-25 February (GOES-14 Sounder Timing will be adjusted to match GOES-13 Sounder Timing) when the GOES-14 Imager is broadcasting SRSO-R data.

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Tropical Depression In-fa (27W) formed well south of the Marshall Islands in the West Pacific Ocean on 17 November 2015, and proceeded to track northwestward to a position south of Guam on 20 November (above). Following a brief decrease in intensity on 18 September, In-fa began another period of intensification during the 19-20 September period. Rapid-scan (2.5-minute interval) Himawari-8 Visible (0.64 µm) images (below; also available as a large 73 Mbyte animated gif) showed a series of eyewall convective bursts and the occasional appearance of a recognizable eye. (Note: the ABI instrument on the upcoming GOES-R satellite will also have a rapid-scan capability, but at 1-minute or even 30-second intervals)

A longer animation spanning the entire 19-20 September period (below; also available as a large 120 Mbyte animated gif) revealed an improving trend in the overall satellite presentation of In-fa, with the eye becoming well defined by the end of the animation as the tropical cyclone reached Category 3 intensity.  In fact, this became the the 15th Category 3 or stronger typhoon in the Northwest Pacific basin in 2015 – the most on record in any tropical cyclone season by the date of 20 November.

A comparison of Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 1547 UTC (below; courtesy of William Straka, SSEC) showed the coldest cloud-top IR brightness temperatures in the southern hemisphere of the eyewall, along with the nighttime glow of lights from the island of Guam.

A well-defined eye was evident in MTSAT-2 Infrared (10.8 µm) and DMSP SSMIS Microwave (85 GHz) images around 2230 UTC on 20 September (below).

Mesovortices within the eye were seen in rapid-scan Himawari-8 Visible (0.64 µm) images beginning late in the day on 20 November as In-fa intensified to a Category 4 typhoon. (below;  also available as a large 50 Mbyte animated GIF).

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An EF-1 tornado was on the ground for about 20 minutes near Denair (Local Storm Report | Facebook post) in central California on 15 November 2015. 1-km resolution GOES-15 Visible (0.63 µm) images (above) showed that clusters of small thunderstorms rapidly developed in an environment of instability along and just behind a fast-moving cold frontal boundary. The location of the tornado is indicated by a red “T” on the 2145, 2200, and 2211 UTC images. Very strong southwesterly winds aloft allowed the upwind portion of the highly-tilted thunderstorms to be brightly illuminated by the low sun angle of late afternoon in mid-November.

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).

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The Storm Prediction Center has revised its criteria for initiating GOES Rapid Scan Operations (RSO) calls. Previously, RSO was automatically activated when a Moderate Risk (MDT) appeared in the SPC Day 1 Convective Outlook. On October 1st that was changed per a September email from SPC:

Starting October 1, the SPC Lead Forecaster will contact the NCO/SDM to request GOES RSO whenever a Day 1 Convective Outlook includes an ENH Risk area. Data from the first six months of 2015 suggests SPC would request RSO on approximately 10-20 more days compared to the current MDT Risk criterion. Activating RSO on a more frequent basis using the ENH Risk criterion would improve NWS forecaster situational awareness on convectively active days and help prepare users for much higher temporal frequency GOES-R data.

An Enhanced Risk was issued on 11 November 2015 as a strong extratropical cyclone was developing over the midsection of the country. The image above shows the GOES-13 Water vapor imagery from 1145 UTC on 11 November. A strong jet extends from the southwestern United States northeastward. On the previous day (10 November, at 12 UTC) Albuquerque reported 135-knot winds at 300 hPa (and no winds at all at 200 hPa as the balloon was lost to the tracker); at 00 UTC on 11 November, winds were 162 knots just above the 250 hPa level. Strong veering, indicating warm advection, is apparent over the mid-Mississippi River Valley. Low-level warm advection is forecast to increase as the extratropical cyclone intensifies.

Update: GOES-East began RSO at 1545 UTC on 11 November 2015 — a few image animations are shown below.

Of particular interest on 6.5 µm water vapor imagery, above, was the tightly-wrapped signature of the middle-tropospheric vorticity center moving northeastward along the Kansas/Nebraska border.

The 10.7 µm Infrared images, above, showed the development of thunderstorms across Iowa which exhibited cloud-top IR brightness temperatures in the -50 to -60º C range (yellow to red color enhancement). Hail, damaging winds, and tornadoes were produced by these areas of deep convection (SPC storm reports).

3.9 µm Shortwave Infrared images, above, displayed numerous “hot spots” (black to yellow to red color enhancement) due to fire activity in parts of northeastern Oklahoma and southeastern Kansas.

Finally, 0.63 µm Visible channel images, above, showed the hazy signature of smoke plumes from these Kansas/Oklahoma fires (along with a separate plume of blowing dust). In addition, as clouds cleared along the western edge of the storm, swaths of fresh snow cover could be seen over portions of Wyoming, Colorado, South Dakota, Nebraska, and Kansas. As much as 12.5 inches of snow was reported in northeastern Colorado, with wind gusts of 75 mph creating blizzard conditions.

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