Severe thunderstorm over West Texas, as viewed from 3 GOES satellites

May 19th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.62 µm visible channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.62 µm visible channel images [click to play animation]

Thunderstorms began to develop across West Texas during the afternoon hours on 19 May 2015, along and ahead of an eastward-moving dryline. One of the storms went on to produce a few brief tornadoes, and hail as large as 3.0 inches in diameter (SPC storm reports). Different views of this storm were provided by GOES-15 (GOES-West), GOES-14 (in SRSO-R mode), and GOES-13 (GOES-East) 0.62 µm visible channel images (above; click image to play 190 MB animated GIF; also available as an MP4 movie file, or on YouTube). This comparison highlights the advantages of 1-minute interval Super Rapid Scan images (which will be available from GOES-R) compared to the standard 15-minute interval Routine Scan images provided by the current generation of GOES.

One interesting feature seen on the visible channel images above was the apparent merger of the large dominant dryline storm and a smaller northward-moving storm that had formed in Mexico (radar animation). In GOES-13 10.7 µm IR imagery with an overlay of SPC storm reports (below; click image to play animation), one report of 2.0-inch diameter hail was seen around or shortly after the time of the storm merger.

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

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

With higher spatial resolution IR imagery from MODIS (1-km), VIIRS (375-meter), and AVHRR (1-km), much colder cloud-top IR brightness temperatures were seen (below) compared to the corresponding 4-km resolution GOES IR imagery at those times — especially during the early formative stages of the thunderstorms captured with MODIS and VIIRS. The coldest cloud-top IR brightness temperature on the 2128 UTC AVHHRR image was -80º C, compared to -67º C on the 2130 UTC GOES image.

Terra and Aqua MODIS 11.0 µm, Suomi NPP VIIRS 11.45 µm, and POES AVHRR 12.0 µm IR channel images

Terra and Aqua MODIS 11.0 µm, Suomi NPP VIIRS 11.45 µm, and POES AVHRR 12.0 µm IR channel images

A more detailed discussion of this event can be found on the RAMMB GOES-R Proving Ground Blog.

GOES-14 in SRSO-R Scanning

May 18th, 2015

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 is producing imagery at 1-minute intervals as part of Super-Rapid Scan Operations for GOES-R (SRSO-R). Sectors that are scanned change each day and are determined by likely weather events. The animation above, in the southwest corner of the Monday May 18 sector shows strong convection over northern Louisiana. (A similar animation in mp4 format is available here (YouTube)) A benefit of 1-minute imagery is that it can capture the entire lifecycle of overshooting tops, cloud-top features that typically form and decay in less than 10 minutes.

GOES-R is scheduled to launch in March 2016. It will have the capability to provide routine 1-minute imagery over mesoscale-sized domains such as those sampled in the next three weeks by GOES-14. Real-time GOES-14 SRSO imagery is available through the SSEC RealEarth web map server and the GOES-14 SRSOR Imagery site.

Rapid Scan Operations allow the eye to distinguish between upper- and lower-level clouds that typically move at different speeds or in different directions. In the animation below (similar mp4 available here), high clouds over western Pennsylvania are moving over dissipating river fog in the central part of the state. Upper level clouds over southern New York are moving southward; low clouds are moving westward behind a back-door cold front: winds at White Plains, Newark, Trenton (and other stations) have all switched to easterly.

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 0.62 µm visible imagery [click to play animation]

Another feature of interest was a thin layer of lake fog that was streaming northward across Lake Michigan during the morning hours, as seen in the animation below (also available as an mp4 movie file). Note the appearance of an undular bore propagating southeastward through the northern portion of the fog at the end of the animation; this may have been caused by an internal reflection of the strong southerly flow impinging upon the rugged southern coastline of the Upper Peninsula of Michigan. According to buoy data and the Terra MODIS Sea Surface Temperature product, Lake Michigan waters were still in the upper 30s to low 40s F — it was the pre-cold-frontal southerly flow of much warmer air with dew point values in the 50s and 60s F that led to the formation of the lake fog.

GOES-14 0.62 um visible channel images (click to play animation)

GOES-14 0.62 um visible channel images [click to play animation]

Rounds of deep convection persisted over parts of the Gulf Coast states during the day, which can be seen in the sunrise-to-sunset animation of GOES-14 visible images below (also available as an MP4 movie file). In Louisiana, some of these storms produced heavy rainfall and flash flooding, with a few water rescues necessary.

GOES-14 0.62 µm visible channel images (click to play YouTube animation)

GOES-14 0.62 µm visible channel images (click to play YouTube animation)

A mid-tropospheric atmospheric bore viewed by GOES-15, GOES-14, and GOES-13

May 16th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

An elongated north-to-south oriented atmospheric bore was observed on GOES-15 (GOES-West), GOES-14, and GOES-13 (GOES-East) 6.5 µm water vapor channel images (above; click to play animation; also available as an MP4 movie file) on the morning of 16 May 2015. This bore feature was located in the area where strong westerly to southwesterly mid-tropospheric winds were impinging upon a consolidating dryline — this dryline later moved eastward and acted as the focus for severe thunderstorms across Texas (SPC storm reports). GOES-14 had been activated to perform Super Rapid Scan Operations for GOES-R (SRSOR) duties beginning on 18 May.

Note that there were no parallel cloud rolls present on the corresponding GOES-15/14/13 0.63 µm visible channel imagery (below) — so this gravity wave bore feature was forming in clear air.

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

A comparison of 12 UTC El Paso, Texas (yellow) and Midland, Texas (cyan) rawinsonde data (below) showed the differences in vertical moisture profile to the west and to the east of the bore feature — especially in the 500-600 hPa layer, where a good deal of the signal contributing to the overall water vapor brightness temperature was originating from.

El Paso and Midland, Texas rawinsonde data profiles

El Paso and Midland, Texas rawinsonde data profiles

GOES-14 SRSOR: Mesovortices in the eye of Hurricane Marie

August 25th, 2014
GOES-14 0.63 µm visible channel images (click to play YouTube video)

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

The GOES-14 satellite was in Super Rapid Scan Operations for GOES-R (SRSOR) mode, providing 1-minute interval images of Category 4 intensity Hurricane Marie over the East Pacific Ocean on 25 August 2014. Even though the eye was cloudy, the 1-minute imagery revealed a number of mesovortices circulating within the eye of Hurricane Marie (above; click image to play YouTube video). Note: the YouTube video is best viewed in Full Screen mode, and clicking on the “Gear” icon to select “1080p HD”.

On the previous day, the eye was less cloudy and mesovortices were more easily seen on GOES-15 0.63 µm visible channel images (below; click to play Animated GIF); however, the GOES-15 images were only available at the routine 15-minute interval, which made tracking the evolution and motion of the mesovortices more difficult. On this day (24 August) Hurricane Marie had rapidly intensified to a Category 5 storm (plot of CIMSS ADT).

GOES-15 0.63 µm visible channel images (click to play Animated GIF)

GOES-15 0.63 µm visible channel images (click to play Animated GIF)