Severe turbulence over Hawai’i

January 12th, 2018 |

GOES-15 Water Vapor (6.5 µm) images, with hourly pilot reports of turbulence [click to play animation]

GOES-15 Water Vapor (6.5 µm) images, with hourly pilot reports of turbulence [click to play animation]

Numerous pilot reports of moderate to severe turbulence were received over the Hawai’i area on 12 January 2018 — and GOES-15 (GOES-West) Water Vapor (6.5 µm) images (above; also available as an MP4) showed the development of a quasi-stationary gravity wave train over the northwestern portion of the island chain which appeared to be associated with many of these pilot reports.

HNL UA /OV 2115N16010W/TM 2241/FL320/TP B767/TB CONT MOD TURB

HNL UUA /OV 2115N16048W/TM 2255/FL340/TP H/B747/TB MOD-SEV TURB

HNL UUA /OV BOARD/TM 2350/FL370/TP H/B772/TB SEVERE TURB

PHNL UUA /OV 2443N 15516W /TM 2358 /FL370 /TP B737 /TB SEV 370 /RM ZOA CWSU AWC-WEB

In spite of the large satellite viewing angle, these waves were also very evident on Himawari-8 Lower-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below; also available as an MP4). The 3 Water Vapor bands on the Himawari AHI are nearly identical to the 3 Water Vapor bands on the GOES-R series ABI.

Himawari-8 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and 6.2 µm, right) Water Vapor images, with hourly pilot reports of turbulence [click to play animation]

Himawari-8 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images, with hourly pilot reports of turbulence [click to play animation]

A toggle between 1-km resolution Terra MODIS Water Vapor (6.7 µm), Infrared Window (11.0 µm) and 250-meter resolution true-color Red-Green-Blue RGB images at 2106 UTC on 12 January (below) showed that no high-altitude clouds were associated with the gravity wave features — thus, these aircraft encounters were examples of Clear Air Turbulence (CAT).

Terra MODIS Water Vapor (6.7 µm) and True-color RGB images [click to enlarge]

Terra MODIS Water Vapor (6.7 µm), Infrared Window (11.0 µm) and true-color RGB images [click to enlarge]

A color-enhanced version of the Aqua MODIS Water Vapor (6.7 µm) image at 0014 UTC on 13 January is shown below (courtesy of Jordan Gerth, CIMSS).

An AWIPS screen capture (below, courtesy of Robert Bohlin, NWS Honolulu and Jordan Gerth, CIMSS) displays a High Pass filter product along with the 3 individual Himawari-8 Water Vapor band images at 0120 UTC on 13 January.

Upper-level Water Vapor (6.2 µm, upper right), Mid-level Water Vapor (6.9 µm, lower left) and Lower-level Water Vapor (7.3 µm, lower right) images [click to enlarge]

Himawari-8 High Pass filter product (6.9 µm, upper left), Upper-level Water Vapor (6.2 µm, upper right), Mid-level Water Vapor (6.9 µm, lower left) and Lower-level Water Vapor (7.3 µm, lower right) images [click to enlarge]

It bears mention that the rawinsonde data from Lihue, Hawai’i at 0000 UTC on 13 January (below) indicated significant wind shear (both speed and directional) within the 200-300 hPa layer (text listing) — the layer in which many of the turbulence reports were found.

Rawinsonde data from Lihue, Hawai'i at 00 UTC on 13 January [click to enlarge]

Rawinsonde data from Lihue, Hawai’i at 00 UTC on 13 January [click to enlarge]

The packet of gravity waves was directly over Lihue (red asterisk) at that time (below).

GOES-15 Water Vapor (6.5 µm) image at 0000 UTC on 13 January, with pilot reports of turbulence plotted. The red asterisk denotes the location of Lihue [click to enlarge]

GOES-15 Water Vapor (6.5 µm) image at 0000 UTC on 13 January, with pilot reports of turbulence plotted. The red asterisk denotes the location of Lihue [click to enlarge]

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]

Record-setting lake effect snow event at Erie, Pennsylvania

December 26th, 2017 |

1-minute GOES-16 "Clean" Infrared Window (10.3 µm) images, with hourly surface reports plotted in cyan/yellow [click to play MP4 animation]

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly surface reports plotted in cyan/yellow [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images centered over Lake Erie (above) showed the evolution of lake effect snow bands on 25 December26 December 2017, which produced very heavy snowfall at locations such as Erie, Pennsylvania (station identifier KERI); a Mesoscale Sector provided images at 1-minute intervals. Some noteworthy snowfall records were set at Erie PA:

(27 December Update: additional lake effect snow at Erie on 27 December brought the final storm total accumulation to 65.1 inches: NWS Cleveland summary. NOHRSC plots showed a maximum snow depth of 49 inches just southwest of downtown Erie; the maximum snow depth at Erie International Airport was 28 inches on 26 December, which was still less than their all-time record snow depth of 39 inches on 21 December 1989)

A sequence of Infrared Window images captured by Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) is shown below. The coldest cloud-top infrared brightness temperatures associated with the dominant lake effect snow bands were in the -30 to -35 ºC range (dark blue to pale green color enhancement), similar to what was seen in the GOES-16 Infrared Window imagery.

Infrared Window images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm), with surface reports plotted in yellow [click to enlarge]

Infrared Window images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm), with surface reports plotted in yellow [click to enlarge]

Farther to the northeast, these Lake Erie lake effect bands also produced significant snowfall in far southwestern New York, with 32 inches reported at Perrysburg (located 20 miles west of Dunkirk, station identifier KDKK). In addition, lake effect snow bands over Lake Ontario were responsible for even higher snowfall amounts:


1-minute GOES-16 “Red” Visible (0.64 µm) images (below) showed the lake effect snow bands over Lake Ontario on 26 December.

1-minute GOES-16 "Red" Visible (0.64 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

1-minute GOES-16 “Red” Visible (0.64 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

Aircraft hole punch and distrail cloud features over southern Lake Michigan

December 20th, 2017 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm. bottom) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed a number of aircraft “hole punch clouds” and cloud dissipation or “distrail” features drifting eastward across southern Lake Michigan and adjacent states on 20 December 2017. These cloud features were caused by aircraft that were either ascending or descending through a layer of cloud composed of supercooled water droplets — cooling from wake turbulence (reference) and/or particles from the jet engine exhaust acting as ice condensation nuclei cause the small supercooled water droplets to turn into larger ice crystals (many of which then often fall from the cloud layer, creating “fall streak holes“). The darker gray appearance of the hole punch clouds on 1.61 µm images confirms that the features were composed of ice crystals (since ice is a strong absorber of radiation at that wavelength).

A good example of a hole punch cloud adjacent to a longer distrail feature was seen over far southeastern Minnesota and the Minnesota/Wisconsin border, using 250-meter resolution Aqua MODIS true-color and false-color Red-Green-Blue (RGB) images from the MODIS Today site (below). Glaciated (ice crystal) cloud features appeared as darker shades of cyan in the false-color image.

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

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

A very detailed view of a hole punch cloud over Lake Michigan was provided by 30-meter resolution Landsat-8 false-color imagery at 1635 UTC, viewed using RealEarth (below).

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

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

===== 21 December Update =====

Another example of numerous aircraft hole punch and distrail cloud features was seen on Terra MODIS true-color and false-color RGB images on 21 December. over northern Illinois and northern Indiana (below).

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

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