GOES-15 Rapid Scan Operations (RSO) sector for American Samoa

December 15th, 2015 |

GOES-15 Visible (0.63 µm) images [click to play animation]

GOES-15 Visible (0.63 µm) images [click to play animation]

On 15 December 2015 NOAA/NESDIS conducted a test of the new GOES-15 (GOES-West) Rapid Scan Operations (RSO) sector for coverage of the American Samoa region (SSD message). GOES-15 Visible (0.63 µm, 1-km resolution) images during the test period between 1711 and 1957 UTC are shown above, with plots of surface observations for Pago Pago (station identifier NSTU) and Faleolo (station identifier NSFA). Note that visible images from the Full Disk scan at 1800 UTC and Southern Hemisphere sectors at :22 past each hour are also included in the animation; during routine operations, there are periods when only 1 image per hour is available (from the Southern Hemisphere sector) which covers American Samoa.

The full size of the American Samoa RSO sector is shown below.

GOES-15 Visible (0.63 µm) image showing the size of the American Samoa RSO sector [click to enlarge]

GOES-15 Visible (0.63 µm) image showing the size of the American Samoa RSO sector [click to enlarge]

Displayed below is the American Samoa RSO sector is relation to the typical GOES-West Full Disk scan coverage.

GOES-15 Visible (0.63 µm) image showing the location of the American Samoa RSO sector in relation to the GOES-15 Full Disk scan coverage [click to enlarge]

GOES-15 Visible (0.63 µm) image showing the location of the American Samoa RSO sector in relation to the GOES-15 Full Disk scan coverage [click to enlarge]

The American Samoa RSO sector images were also successfully broadcast over the Satellite Broadcast Network (SBN) for display in AWIPS II; a sample GOES-15 Infrared (10.7 µm, 4-km resolution) image is shown below.

GOES-15 Infrared (10.7 µm) image, displayed using AWIPS II [click to enlarge]

GOES-15 Infrared (10.7 µm) image, displayed using AWIPS II [click to enlarge]

As a preview to the upcoming GOES-R series of satellites, we can examine JMA Himawari-8 Visible (0.64 µm, 0.5 km resolution) images for the same 3-hour time period, as seen below (sun glint over the open water is high during this time of day, due to the sun-satellite geometry of Himiwari-8 positioned at 140º East longitude). The images are available from the AHI instrument every 10 minutes, and show the development of organized clusters of convection just north and south of the larger islands of Samoa and Apia. Remote locations such as American Samoa will receive similar images every 5 minutes from the ABI instrument on GOES-R/S/T.

Himawari-8 Visible (0.64 µm) images [click to play animation]

Himawari-8 Visible (0.64 µm) images [click to play animation]

Bore-like Gravity Wave Signatures over Texas

December 15th, 2015 |

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 (above) and GOES-15 (below) both captured the propagation of gravity waves that displayed Bore-like attributes along an inversion with a cold front over central Texas. (Click here for an animation of GOES-13 and GOES-15 side-by-side that includes observed surface winds).

GOES-15 Visible (0.63 µm) images [click to play animation]

GOES-15 Visible (0.63 µm) images [click to play animation]

There was a temperature drop across the front, and modest wind gusts occurred just after the lowest pressure associated with the feature passed, but those gusts occurred only in a narrow corridor in central Texas: KSNK (Snyder) reported gusts of 14 knots (0925 UTC); KSWW (Sweetwater) reported gusts of 15 knots (1035 UTC); KABI (Abilene) reported gusts to 17 knots (1152 UTC); KBWD (Brownwood) reported gusts to 24 knots at 1335 UTC; KMKN (Comanche) reported gusts of 22 knots at 1355 UTC (See also the image below). The narrowness of this corridor is likely related to the strength of the inversion along which the bore is propagating (The 1200 UTC Soundings from Fort Worth and from Del Rio both show a very strong inversion; perhaps there was a weakness in the inversion over central Texas that allowed for more vertical mixing).

GOES-13 Visible (0.63 µm) imagery at 1400 UTC; Station Locations are indicated, including the 5 stations with identifiable Wind Gusts associated with the Bore Feature [click to enlarge]

GOES-13 Visible (0.63 µm) imagery at 1400 UTC; Station Locations are indicated, including the 5 stations with identifiable Wind Gusts associated with the Bore Feature (Gust Strength in knots and time of Gust indicated) [click to enlarge]

During the preceding nighttime hours, the early stage of the undular bore feature was detected on an Aqua MODIS Water Vapor (6.7 µm) image, below, along the leading edge of the colder air and colder surface brightness temperatures (light to medium blue colors) seen on the corresponding MODIS Infrared (11.0 µm) image at 0807 UTC or 2:07 am local time.

Aqua MODIS Water Vapor (6.7 µm) and Infrared (11.0 µm) images [click to enlarge]

Aqua MODIS Water Vapor (6.7 µm) and Infrared (11.0 µm) images [click to enlarge]

(Hat tip to Mike Johnson, NWS in San Angelo for tweeting about this feature!)

Intense hurricane-force storm in the Bering Sea

December 13th, 2015 |

Himawari-8 Water Vapor (6.9 µm) images [click to play animation

Himawari-8 Water Vapor (6.9 µm) images [click to play animation

Japanese Meteorological Agency Himawari-8 Water Vapor (6.9 µm, 2-km resolution) images (above) showed the rapid intensification of a hurricane-force extratropical cyclone over the North Pacific Ocean and Bering Sea during the 12 December – 13 December 2015 period. The 6.9 µm is one of 3 water vapor spectral bands on the Himawari AHI instrument — GOES-R will feature 3 nearly identical water vapor bands on the ABI instrument.

According to surface analyses from the Ocean Prediction Center, the storm was centered over Japan at 00 UTC on 11 December, and began rapidly intensifying later that day as it continued moving northeastward; it eventually deepened to a minimum central pressure of 924 hPa (27.29 inches of mercury) over the far southern Bering Sea at 06 UTC on 13 December. This equaled the analyzed minimum central pressure of Post-Tropical Cyclone Nuri in November 2014, which was one of the strongest storms on record in the Bering Sea.

Corresponding GOES-15 Water Vapor (6.5 µm, 4-km resolution) images (below) offered a slightly closer view of the intensifying storm. The unique satellite signature — resembling a curved scorpion tail — of a phenomenon known as a sting jet was seen to begin developing around 20 UTC on 12 December south of the Aleutian Islands. Several hours after the middle-tropospheric sting jet feature on water vapor imagery moved over Adak Island (PADK on the images) around 0130 UTC, sustained surface winds of 82 knots (94 mph) with gusts to 106 knots (122 mph) were recorded just after 09 UTC. According a Tweet from the Ocean Prediction Center, winds from the storm also produced wave heights of 63 feet.

GOES-15 Water Vapor (6.5 µm) images [click to play animation]

GOES-15 Water Vapor (6.5 µm) images [click to play animation]

A time series of surface observations at Adak Island (below) indicated that the minimum station pressure of 939.0 hPa (27.73 inches of mercury) was recorded just after 04 UTC.

Time series of Adak Island, Alaska surface observation [click to enlarge]

Time series of Adak Island, Alaska surface observation [click to enlarge]

Additional imagery from this event can be found on the RAMMB GOES-R Proving Ground Blog.

Rain in the Pacific Northwest

December 8th, 2015 |
GOES-15 Band 3 Water Vapor (6.5 µm) imagery for 6-8 December 2015 [click to play animation]

GOES-15 Band 3 Water Vapor (6.5 µm) imagery for 6-8 December 2015 [click to play animation]

Persistent southerly to westerly flow over the Pacific Northwest has allowed a series of disturbances to produce rain each day so far this month in Seattle, including a record rainfall on December 7th (a day that was particularly dark, given the extensive clouds and the low sun angle: Link). (Update: Seattle also had record daily rainfall on 8 December.) The GOES-15 Water Vapor animation, above, from 0000 UTC on 6 December through 2100 UTC on 8 December (available here as an mp4 file) shows that series of impulses on the south side of a strong circulation in the Gulf of Alaska (Surface Analysis), and later scenes suggest a jet extending to the southwest. MIMIC Total Precipitable Water, below, for the 72 hours ending at 1700 UTC on 8 December, shows the signature of an atmospheric river moving moisture towards the Pacific Northwest coast, auguring rain. The broad southerly and southwesterly flow has meant above-normal temperatures as well (Seattle recorded a daily record high maximum — 60 F — on December 8).

MIMIC Total Precipitable Water for the 72 hours ending 1700 UTC on 8 December 2015 [click to enlarge]

MIMIC Total Precipitable Water for the 72 hours ending 1700 UTC on 8 December 2015 [click to enlarge]

The Aqua Satellite, carrying a MODIS (MODerate resolution Imaging Spectroradiometer) instrument, overflew the Pacific Northwest at about 2045 UTC on 8 December. The MODIS instrument senses radiation at 1.38 µm, a water vapor channel that is particularly sensitive to Cirrus Clouds (GOES-R will also detect radiation at this wavelength). The toggle below, between the 1.38 µm near-infrared and the 0.64 µm visible, shows that the storm in the Gulf of Alaska and the jet moving in from the southwest are prolific cirrus producers! Cirrus is present almost everywhere. The cirrus channel on MODIS is dark (that is, it is not detecting upper-level clouds that are inferred to be cirrus) only over the central Plains, over the Pacific Ocean west of California/Oregon and over parts of north-central Oregon and western Washington.

Aqua MODIS Cirrus Channel (1.38 µm) and Visible Channel (0.64 µm) imagery, 2045 UTC on 8 December 2015 [click to enlarge]

Aqua MODIS Cirrus Channel (1.38 µm) and Visible Channel (0.64 µm) imagery, 2045 UTC on 8 December 2015 [click to enlarge]