Fog/stratus in the Strait of Juan de Fuca

May 20th, 2017 |

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

As seen in a Tweet from NWS Seattle/Tacoma (above), a plume of fog/stratus moved rapidly eastward through the Strait of Juan de Fuca on 20 May 2017. A closer view of GOES-16 Visible (0.64 µm) images (below; also available as an MP4 animation) shows the formation of “bow shock waves” as the leading edge of the low-level fog/stratus plume encountered the sharply-angled land surface of Whidbey Island at the far eastern end of the Strait near sunset — surface observations indicated that the visibility at Naval Air Station Whidbey Island was reduced to 0.5 mile just after the time of the final 0327 UTC image in the animation.

GOES-16 Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation]

GOES-16 Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation]

A Suomi NPP VIIRS Visible (0.6 µm) image with RTMA surface winds (below) indicated that westerly/northwesterly wind speeds were generally around 15 knots at 21 UTC (just after the primary fog/stratus plume began to move into the western end of the Strait). Four hours later, there was a northwesterly wind gust of 27 knots at Sheringham, British Columbia (CWSP).

Suomi NPP VIIRS Visible (0.64 µm) images, with RTMA surface winds plotted in cyan [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) images, with RTMA surface winds plotted in cyan [click to enlarge]

During the following nighttime hours, a Suomi NPP VIIRS infrared Brightness Temperature Difference (11.45 – 3.74 µm) “Fog/Stratus Product” image at 0910 UTC (below) revealed that the fog/stratus plume covered much of the Strait (especially along the Washington coast), and that the leading edge had begun to spread both northward and southward from Whidbey Island. In addition, note the presence of a linear ship track (darker red enhancement) extending southwestward from Cape Flattery.

Suomi NPP VIIRS Infrared brightness temperature difference (11.45 - 3.74 µm)

Suomi NPP VIIRS infrared Brightness Temperature Difference (11.45 – 3.74 µm) “Fog/Stratus Product” image, with RTMA surface winds plotted in cyan [click to enlarge]

Bill Line (NWS Pueblo) showed the nighttime fog/stratus monitoring capability of a GOES-16 infrared Brightness Temperature Difference product:


On a side note, in the upper right portion of the GOES-16 (as well as the VIIRS) visible images one can also see the hazy signature of glacial sediment  flowing from the Fraser River westward into the Strait of Georgia. Longer-term changes in the pattern of this glacial sediment are also apparent in a comparison of Terra MODIS true-color Red/Green/Blue (RGB) images (source) from 20 April, 07 May and 20 May 2017 (below).

 

Terra MODIS true-color RGB images [click to enlarge]

Terra MODIS true-color RGB images [click to enlarge]

Large hail in eastern Colorado

May 8th, 2017 |

GOES-16 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with surface station identifiers in yellow and SPC reports of hail size in cyan [click to play MP4 animation]

GOES-16 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with surface station identifiers plotted in yellow and SPC reports of hail size plotted in cyan [click to play MP4 animation]

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

Severe thunderstorms developed over eastern Colorado on 08 May 2017, producing large hail (especially in the Denver area: SPC storm reports | NWS Boulder summary). Both GOES-16 Mesoscale Sectors were positioned over that region, providing 30-second interval images — Visible (0.64 µm) and Infrared Window (10.35 µm) images (above; also available as a 161 Mbyte animated GIF) showed the convection in great detail, with parallax-corrected SPC storm reports of hail size (inches; H275 = 2.75 inches in diameter) plotted in cyan. Several of the storms exhibited well-defined overshooting tops in the Visible imagery, as well as “enhanced-V” and/or cold-warm “thermal couplet” signatures on the Infrared imagery.



A comparison of 30-second interval GOES-16 Mesoscale Sector and 15-minute interval GOES-13 (GOES-East) Routine Scan visible images (below; also available as a 179 Mbyte animated GIF) demonstrated the clear advantage of rapid-scan imagery for monitoring convective development. Also note the degradation of GOES-13 visible imagery (the cloud features do not appear as bright), due to the age of that satellite — the GOES-R series ABI instrument features on-board visible detector calibration, so this type of visible image degradation over time will not occur.

GOES-16 Visible (0.64 µm, left) and GOES-13 Visible (0.63 µm, right) images, with surface station identifiers in yellow [click to play MP4 animation]

GOES-16 Visible (0.64 µm, left) and GOES-13 Visible (0.63 µm, right) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below; actual satellite overpass time 1943 UTC) provided a high-resolution (375 meter) view of the developing thunderstorms, about 17 minutes before the first report of hail northeast of Trinidad (KTAD) at 2000 UTC — a number of these storms exhibited cloud-top infrared brightness temperatures of -70 to -73º C (black enhancement). The VIIRS instrument will also be on the JPSS series of satellites, the first of which is scheduled to be launched in the 4th quarter of 2017.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface station identifiers plotted in cyan [click to enlarge]

Small Eddy and coastal jet off the coast of Northern California

May 4th, 2017 |

GOES-16 Visible (0.64 µm) from 1245 through 2200 UTC on 4 May 2017 (Click to play mp4 animation)

GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.

One of the two GOES-16 Mesoscale Sectors was moved from its default position over the eastern United States and placed over the west coast of the United States on 4 May 2017. This allowed 1-minute imagery of a small-scale coastal eddy between Cape Mendocino and Pt. St. George near Crescent City, above, and an associated coastal jet. (Click here to play 300-meg Animated Gif; alternatively, this animation shows the eddy from 1600-1900 UTC as displayed in AWIPS (courtesy Dan Miller, WFO DLH))

A zoomed-in Visible animation of the coastal eddy is shown below; NWS Eureka described it as “one of the best examples of these coastal eddies seen in quite a while”.

GOES-16 Visible (0.64 µm) images, with hourly surface reports plotted in yellow (Click to animate)

GOES-16 Visible (0.64 µm) images, with hourly surface reports plotted in yellow (Click to animate)

GOES-16 Visible 0.64 µm imagery is able to capture not only the eddy, but also the northerly low-level jet that develops off the coast of Cape Mendocino, swiftly moving clouds southward around that feature. A small eddy also develops south of Cape Mendocino. Note also the abundance of cirrus clouds flowing northward along the coast.

The dimensions of this eddy are approximately 70 km in the along-shore direction and 55 km perpendicular to the shore, yet GOES-16 is able to capture and resolve many small-scale cloud bands. The small cloud band streaming south around Cape Mendocino, for example, is only about 6 km wide and is well-resolved; if GOES-16 becomes GOES-East at 75 W Longitude, this is the type of resolution that can be expected in Salt Lake City.

It should be noted that none of the models (including the hourly RTMA, below) resolved this eddy feature.

Suomi NPP VIIRS Visible (0.64 µm) image, with RTMA surface winds {Click to enlarge)

Suomi NPP VIIRS Visible (0.64 µm) image, with RTMA surface winds {Click to enlarge)

Thanks to Dan Miller, Science and Operations Officer (SOO) in Duluth for calling this awesome feature to our attention!

Eruption of Kambalny volcano in Kamchatka, Russia

March 25th, 2017 |

Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images [Click to play animation]

Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images [Click to play animation]

The Kambalny volcano in far southern Kamchatka, Russia erupted around 2120 UTC on 24 March 2017. A Himawari-8 “Target Sector” was positioned over that region — providing rapid-scan (2.5-minute interval) imagery — as seen in a 2-panel comparison of AHI Visible (0.64 µm) and Infrared Window (10.4 µm) data covering the first 7 hours of the eruption (above). Ash plume infrared brightness temperatures quickly became -40ºC and colder (bright green enhancement).

Himarari-8 false-color RGB images [click to play animation]

Himarari-8 false-color RGB images [Click to play animation]

Himawari-8 false-color Red/Green/Blue (RGB) images from the NOAA/CIMSS Volcanic Cloud Monitoring site (above) showed the ash plume drifting south-southwestward during the subsequent nighttime hours. It is interesting to note the formation and subsequent northwestward motion of numerous contrails (darker green linear features) across the region, due to the close proximity of a major Tokyo flight corridor.

True-color RGB images from Terra MODIS, Suomi NPP VIIRS and Aqua MODIS, viewed using RealEarth (below) revealed the long ash plume during the late morning and early afternoon on 25 March. The dark signature of ash fall onto the snow-covered terrain was evident on the Terra and Aqua images, just west of the high-altitude ash plume.

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color RGB images [Click to enlarge]

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color RGB images [Click to enlarge]

26 March Update: a closer view of Terra MODIS true-color images from 25 and 26 March (below) showed that the perimeter of the darker gray surface ash fall signature had fanned out in both the west and east directions.

Terra MODIS truecolor RGB images from 25 and 26 March, with arrows indicating the perimeter of surface ash fall signatures on each day [Click to enlarge]

Terra MODIS truecolor RGB images from 25 and 26 March, with arrows indicating the perimeter of surface ash fall signatures on each day [Click to enlarge]