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/northwesteerrrly 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]

Tornadoes and large hail in Minnesota and Wisconsin

May 16th, 2017 |

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in cyan [click to play animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in cyan [click to play animation]

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

A significant outbreak of severe thunderstorms developed on 16 May 2017, producing damaging winds, large hail and tornadoes from Texas to Wisconsin (SPC storm reports). On the northern end of this outbreak, hail as large as 3.0 inches in diameter fell in northwestern Wisconsin, and a tornado resulted in 1 fatality and at least 25 injuries near Chetek (NWS Twin Cities MN summary). GOES-16 Visible (0.64 µm) and Infrared Window (10.3 µm) images (above) showed the development of the convective systems; surface-to-cloud-top parallax-corrected SPC storm reports are plotted on the images. Overshooting tops and above-anvil cloud plumes were evident on the visible images, with well-defined “enhanced-V” and “cold/warm thermal couplet” storm top signatures seen on the infrared imagery.

A closer view of the GOES-16 Visible and Infrared Window images (below) provided more detail of the supercell storm-top structure. Note that the pronounced enhanced-V Infrared signature began to develop near the Minnesota/Wisconsin border just before 2100 UTC, which was about 40 minutes before the first Wisconsin hail report of 2.5 inches, and about 90 minutes prior to the fatal Chetek tornado. Since the early 1980s (reference), the enhanced-V satellite signature has been recognized as a reliable predictor of supercell thunderstorms having a high potential to produce either damaging winds, large hail or tornadoes; an automated Enhanced-V / Overshooting Top product (reference) will be available using the ABI instrument on the GOES-R series of satellites..

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with plots of SPC storm reports and hourly surface reports [click to play animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with plots of SPC storm reports and hourly surface reports [click to play animation]

A comparison of GOES-13 (GOES-East) and GOES-16 Infrared Window images (below) demonstrated the advantage of improved spatial resolution (2-km at satellite sub-point with GOES-16, vs 4-km with GOES-13) for identifying features such as cold overshooting tops.

Infrared Window images from GOES-13 (10.7 µm, top) and GOES-16 (10.3 µm, bottom) , with SPC storm reports plotted in cyan [click to play animation]

Infrared Window images from GOES-13 (10.7 µm, top) and GOES-16 (10.3 µm, bottom) , with SPC storm reports plotted in cyan [click to play animation]

True-color Red/Green/Blue (RGB) imagery (below; courtesy of Kaba Bah, CIMSS) offered another view of the storms on a regional scale.

GOES-16 true-color RGB images [click to play animation]

GOES-16 true-color RGB images [click to play animation]


Tropical Storm Adrian

May 10th, 2017 |

GOES-16 Infrared Window (10.3 µm) images [click to play animation]

GOES-16 Infrared Window (10.3 µm) images [click to play animation]

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

East Pacific Ocean Tropical Depression 1E intensified to become Tropical Storm Adrian (at 9.5º N latitude, 92.3º W longitude) at 03 UTC on 10 May 2017 — making it the earliest tropical storm on record in the East Pacific basin during the meteorological satellite era. GOES-16 Infrared Window (10.3 µm) images (above) revealed a series of nocturnal convective bursts which exhibited cloud-top infrared brightness temperatures in the -80º to -89º C range (shades of violet color enhancement).

During the subsequent daylight hours, GOES-16 Visible (0.64 µm) images (below) showed that southeasterly deep layer wind shear (source) had decoupled the organized convection from the exposed low-level circulation center (LLCC). Due to the far southern location of Adrian, only Full Disk scan images were available, at 15-minute intervals.

GOES-16 Visible (0.64 µm) images [click to play animation]

GOES-16 Visible (0.64 µm) images [click to play animation]

However, one of the GOES-16 Mesoscale Sectors was positioned over Adrian during the 2226-2355 UTC period, providing images of the LLCC at 1-minute intervals (below).

GOES-16 Visible (0.64 µm) mesoscale sector images [click to play animation]

GOES-16 Visible (0.64 µm) mesoscale sector images [click to play animation]

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]