Heavy rainfall over the Hawaiian island of Kauai

April 15th, 2018 |

GOES-15 Water Vapor (6.5 µm, left) and Infrared Window (10.7 µm, right) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-15 Water Vapor (6.5 µm, left) and Infrared Window (10.7 µm, right) images, with hourly plots of surface reports [click to play MP4 animation]

A series of back-building thunderstorms produced very heavy rainfall and flash flooding (Public Information Statement | Local Storm Reports) over the northern and eastern portion of Kauai on 14-15 April 2018. GOES-15 (GOES-West) Water Vapor (6.5 µm) and Infrared Window (10.7 µm) images (above) showed these deep convective storms, which exhibited cloud-top infrared brightness temperatures in the -60 to -70 ºC range (red to black enhancement).

Even though the JMA Himawari-8 AHI instrument provides more frequent Water Vapor and Infrared Window images (every 10 minutes, compared to every 15-30 minutes with GOES-15) at a higher spatial resolution (2-km at satellite sub-point, vs 4-km with GOES-15),  Hawai’i is located near the limb of the Himawari-8 view — so parallax was playing a major role in the apparent location of the important convective features. Note how the primary thunderstorms were displayed to the east of Kauai on the Himawari-8 images, in contrast to directly over the island on GOES-15 images.

Himawari-8 Water Vapor (6.9 µm, left) and Infrared Window (10.4 µm, right) images, with hourly plots of surface reports [click to play MP4 animation]

Himawari-8 Water Vapor (6.9 µm, left) and Infrared Window (10.4 µm, right) images, with hourly plots of surface reports [click to play MP4 animation]

The MIMIC Total Precipitable Water product (below) showed that high amounts of tropical moisture were drawn northward across Hawai’i by the circulation of an upper-level trough that was situated west of the islands.

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

Final Full Disk images from GOES-13

January 8th, 2018 |

As discussed in this blog post, GOES-13 — launched in May 2006, with a Post Launch Test in December 2006 — served as GOES-East from 2010 to 2017. Image dissemination was terminated on 08 January 2018; the satellite will then begin drifting on 10 January to its storage location at 60º  West longitude. Shown below are the final Full Disk Visible (0.63 µm), Water Vapor (6.5 µm) and Infrared Window (10.7 µm) images broadcast by GOES-13 at 1445 UTC.

GOES-13 Visible (0.63 µm) image [click to enlarge]

GOES-13 Visible (0.63 µm) image [click to enlarge]

GOES-13 Water Vapor (6.5 µm) image [click to enlarge]

GOES-13 Water Vapor (6.5 µm) image [click to enlarge]

GOES-13 Infrared Window (10.7 µm) image [click to enlarge]

GOES-13 Infrared Window (10.7 µm) image [click to enlarge]

Ice floes in Chesapeake Bay

January 7th, 2018 |

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

In the wake of the explosive cyclogenesis off the East Coast of the US on 04 January 2018, very cold air began to spread across much of the eastern half of the Lower 48 states. Focusing on the Hampton Roads area of southeastern Virginia, satellite imagery began to show the formation of ice in the rivers and bays. On 06 January, a 30-meter resolution Landsat-8 false-color Red-Green-Blue (RGB) image viewed using RealEarth (above) revealed some of this ice — in particular, long narrow ice floes (snow and ice appear as shades of cyan) that likely emerged from the Back River (northeast of Hampton) and were drifting northward and southward just off the coast of the Virginia Peninsula.

On the following day (07 January), 250-meter resolution Terra MODIS true-color and false-color RGB images from the MODIS Today site (below) showed that a larger V-shaped ice floe was located just southeast of the Peninsula, with its vertex pointed toward the Hampton Roads Bridge-Tunnel (HRBT). Snow and ice also appear as shades of cyan in the MODIS false-color image.

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

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

07 January also happened to be the last full day of imagery to be broadcast by the GOES-13 satellite — a comparison of 1-minute Mesoscale Sector GOES-16 (GOES-East) Visible (0.64 µm) and 15-30 minute interval GOES-13 Visible (0.63 µm) images (below) showed that the V-shaped ice floe continued to drift southwestward toward the HRBT. However, it was difficult to tell whether the ice feature made it over and past the tunnel; even with the improved GOES-16 Visible spatial resolution (0.5 km at satellite sub-point, compared to 1.0 km for GOES-13) and the 1-minute rapid image scans, the ice floe became harder to track during the afternoon hours before high clouds began to overspread the region.

"GOES-16

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

However, a close examination of Suomi NPP VIIRS true-color and false-color images at 1826 UTC (below) indicated that some of the ice had indeed moved westward past Fort Monroe (on the far southeastern tip of the Peninsula) and over/past the HRBT.

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

On the topic of cold temperatures in southeastern Virginia, a new daily record low of -3 ºF was set at Richmond on the morning of 07 January, and at Norfolk new daily record low and record low maximum temperatures were set (10 ºF and 23 ºF, respectively).

Satellite signatures of a “sting jet”

January 4th, 2018 |

GOES-16 Lower-level (7.3 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

GOES-16 Lower-level (7.3 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

Satellite signatures of a phenomenon known as a “sting jet” have been shown previously on this blog here, here and here. GOES-16 (GOES-East) Lower-level (7.3 µm) Water Vapor images (above) revealed another classic example of the “scorpion tail” signature of a sting jet associated with the rapidly-intensifying storm off the coast of North Carolina on 04 January 2018.

The passenger cruise ship Norwegian Breakaway was en route to New York City from the Bahamas when it experienced very strong winds and rough seas early in the morning on 04 January (media story) — it appears as though the ship may have been in the general vicinity of this sting jet feature (ship data), where intense winds were descending to the surface from higher levels of the atmosphere:

A comparison of GOES-16 (GOES-East) and GOES-13 Water Vapor images (below) demonstrated how the GOES-16 improvement in spatial resolution  (2 km at satellite sub-point, vs 4 km for GOES-13) and more frequent imaging (routinely every 5 minutes over the CONUS domain, vs 15-30 minutes for GOES-13) helped to better follow the evolution of the sting jet feature. The 2 known locations of the Norwegian Breakaway around the time period of the image animation are plotted in red.

"Water

Water Vapor images from GOES-16 (6.9 µm, left) and GOES-13 (6.5 µm, right), with the 2 known locations of the Norwegian Breakaway plotted in red [click to play MP4 animation]

The sting jet signature was also apparent on GOES-16 Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below).

GOES-16 Mid-level (6.9 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

GOES-16 Mid-level (6.9 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

GOES-16 Upper-level (6.2 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

GOES-16 Upper-level (6.2 µm) images, with hourly plots of buoy and ship reports [click to play MP4 animation]

In addition, the sting jet signature was evident in a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0614 UTC or 1:14 AM Eastern time (below). Through the clouds, the faint glow of city lights in far eastern North Carolina could be seen along the left edge of the image. The cloud features shown using the “visible image at night” VIIRS Day/Night Band were brightly-illuminated by the Moon, which was in the Waning Gibbous phase at 92% of Full. A VIIRS instrument is aboard the JPSS series of satellites, such as the recently-launched NOAA-20.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Another view of the sting jet signature was seen in a 250-meter resolution Aqua MODIS Infrared Window (11.0 µm) image at 0725 UTC (below).

Aqua MODIS Infrared Window (11.0 µm) image [click to enlarge]

Aqua MODIS Infrared Window (11.0 µm) image [click to enlarge]