A longer animation of Himawari-8 Infrared Window (10.4 µm) images (below) revealed a very large convective burst as Kelvin meandered near the coast early on 17 February — periodic cloud-top infrared brightness temperatures of -90 ºC or colder were seen. After making landfall, the eye structure eventually deteriorated by 18 UTC on 18 February.The MIMIC-TC product (below) showed the development of Kelvin’s compact eye during the 17 February – 18 February period; the eye was well-defined around the time of landfall (2147 UTC image on 17 February), and persisted for at least 18 hours (1556 UTC image on 18 February) until rapidly dissipating by 21 UTC. Himawari-8 Deep Layer Wind Shear values remained very low — generally 5 knots or less — prior to, during and after the landfall of Kelvin, which also contributed to the slow rate of weakening. In addition, an upward moisture flux from the warm/wet sandy soil of that region helped Kelvin to intensify after landfall; land surface friction was also small, since that portion of Northwest Australia is rather flat. The eye of Cyclone Kelvin could also be seen in Terra MODIS and Suomi NPP VIIRS True-color Red-Green-Blue (RGB) images, viewed using RealEarth (below). The actual times of the Terra and Suomi NPP satellite overpasses were 0154 UTC and 0452 UTC on 18 February, respectively.
An Aqua MODIS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) showed the dense lower-tropospheric smoke drifting southward and southeastward from the fire source region, as well as the narrow upper-tropospheric anvil of the pyroCb cloud. Suomi NPP VIIRS fire detection locations are plotted as red dots on the final zoomed-in image. The actual time of the Aqua satellite pass over Argentina was 1812 UTC.According to Worldview the coldest MODIS Infrared Window (11.0 µm) cloud-top brightness temperature was -41.2 ºC, thus surpassing the -40 ºC threshold that is generally accepted to classify it as a pyroCb. This is believed to be the first confirmed pyroCb event in South America.
Approximately 120 km north-northeast of the pyroCb cloud, rawinsonde data from Santa Rosa, Argentina (below) indicated that the -41 ºC cloud-top temperature corresponded to altitudes in the 10.8 to 11.6 km range. The air was very dry at that level in the upper troposphere, contributing to the rapid dissipation of the pyroCb cloud material as seen in GOES-16 imagery.48-hour HYSPLIT forward trajectories originating from the center of the pyroCb cloud at altitudes of 7, 9 and 11 km (below) suggested that a rapid transport of smoke over the adjacent offshore waters of the Atlantic Ocean was likely at those levels. On 30 January, Suomi NPP OMPS Aerosol Index values (below; courtesy of Colin Seftor, SSAI at NASA Goddard) were as high as 4.3 over the South Atlantic (at 41.81º South latitude, 53.22º West longitude, 17:31:34 UTC) — consistent with the HYSPLIT transport originating at 7 km. Additional Suomi NPP VIIRS True-color and OMPS Aerosol Index images can be found on the OMPS Blog.
===== 01 February Update =====
This analysis of CALIPSO CALIOP data (courtesy of Mike Fromm, NRL) suggests that the upper-tropospheric smoke from this pyroCb event was transported as far as the eastern South Atlantic Ocean by 02 UTC on 01 February, having ascended to altitudes in the 9-10 km range.
Multi-spectral retrievals of the Ash Cloud Height (below) indicated that the ash reached altitudes of at least 10 km (dark blue).A plot of rawinsonde data from nearby Legaspi at 00 UTC on 22 January (below) indicated that the 10 km altitude corresponded to a pressure of 285 hPa. A Suomi NPP VIIRS True-color RGB image from RealEarth (below) revealed some of the lower-altitude ash (shades of tan to brown) drifting toward the west at the satellite overpass time of 0507 UTC. Thermal anomalies — signatures of hot lava flows — are indicated by red dots.
A toggle between 250-meter resolution Terra MODIS True-color and False-color Red-Green-Blue (RGB) images from the MODIS Today site (below) provided a more detailed view of the Lake Erie ice dam and upwind drift ice at 1615 UTC. Snow and ice appear as shades of cyan in the False-color image, in contrast to supercooled water droplet clouds which are shades of white.The Terra MODIS Visible (0.65 µm) image with an overlay of RTMA surface winds (below) showed the southwesterly flow across the long axis of the lake. A toggle between 1607 UTC Terra MODIS and 1757 UTC Suomi NPP VIIRS Visible images (below) showed the motion of the lake drift ice during that time period.
GOES-16 “Red” Visible (0.64 µm) images (below) showed some of the features which helped produce heavier rainfall and snowfall during the daylight hours on 09 January.The circulation of the upper-level low was easily seen on GOES-16 Mid-level Water Vapor (6.9 µm) images (below).
===== 10 January Update =====On the following day, a toggle between Suomi NPP VIIRS True-color and False-color Red-Green-Blue (RGB) images from RealEarth (above) showed (1) the large burn scar from the Thomas Fire (shades of reddish-brown), and (2) snow cover in the higher terrain (darker shades of cyan) on the False-color image. The True-color image revealed sediment from runoff flowing into the nearshore waters from Santa Barbara to Oxnard (shades of brown to light green).
A closer look at the Thomas Fire burn scar was provided by 30-meter resolution Landsat-8 False-color RGB imagery (below), which showed thin filaments of muddy sediment just offshore, as well as fresh snow cover (shades of cyan) along or immediately adjacent to the northeastern edge of the burn scar (in the Hines Peak area). On 10 January, the fire was listed as 92% contained (100% containment was declared on 12 January).
===== 11 January Update =====A comparison of Suomi NPP VIIRS True-color RGB images on 10 January and 11 January (above) showed that sediment was flowing farther offshore from the Thomas Fire burn scar area.
Farther to the south, offshore sediment transport was also seen in the San Diego area (below).
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.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. 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. 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).
— NWS Marquette (@NWSMarquette) January 6, 2018
For perspective, the daily morning minimum temperatures at Embarrass, Minnesota are also plotted on the images — on these 3 days Embarrass was the coldest official site in the US (including Alaska).
The VIIRS images were captured by the Space Science and Engineering Center direct broadcast ground station.
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:
Interpolating https://t.co/nNODxB61uj suggests in that vicinity/time. This is NAM nest 06z initialization, near time of https://t.co/NG2ytIaztM. In any event, sailed directly into core of what models correctly predicted to be one of most extreme #bombogenesis rates on record. pic.twitter.com/rcQK7IP2Qv
— Stu Ostro (@StuOstro) January 7, 2018
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.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). 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. 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).
A strong extratropical cyclone that deposited snow in the deep south developed explosively during the early morning hours of 4 January 2018. The GOES-16 Clean Window (10.3 µm) animation, above, from 0102 – 1337 UTC on 4 January, brackets the explosive development: from 993 hPa at 0000 UTC to 968 mb at 0900 UTC, a strengthening that easily meets the “Bomb” criteria set forth by Sanders and Gyakum (1980). The Clean Window animation shows the strong surface circulation with well-defined conveyor belts. Convection develops at the leading edge of the dry slot that is approaching southern New England at the end of the animation. The Low-Level Water Vapor (7.3 µm) animation for the same time, below, suggests very strong descent behind the storm, where brightness temperatures warmer than -10º C (orange in the enhancement used) are widespread.
This storm can also be viewed using Red-Green-Blue composites (in addition to the single-channel animations shown above). The Airmass RGB, below, combines the Split Water Vapor Difference (6.2 µm – 7.3 µm) as Red, Split Ozone (9.6 µm – 10.3 µm) as Green, and Upper level Water Vapor (6.2 µm) as Blue. (Other storms analyzed with the Airmass RGB can be seen here, here, and here). The strong red signal in the Airmass RGB south of the storm suggests very strong sinking motion.
ASCAT Scatterometer winds over the system at 0205 UTC showed an elongated surface circulation with multiple observations of winds exceeding 50 knots (in red), and a large region (in yellow) of winds exceeding 35 knots.
The 1520 UTC ASCAT pass, above, sampled half the storm, and hurricane-force winds were indicated.
The snow that was deposited in the Deep South by this storm (also discussed here) persisted through a cold night and was visible in the GOES-16 Visible (0.64 µm) imagery, below. Highly reflective snow can be difficult in a still image to distinguish from clouds — but the Snow/Ice Channel on GOES-16 (1.61 µm) detects energy at a wavelength that is strongly absorbed by ice. Thus, snow (and ice) on the ground (or in clouds), has a different representation. (Here are toggles between the two images, with and without a map). The snow cover over coastal Georgia, South and North Carolina appears dark in the Snow/Ice channel because the snow is absorbing, not reflecting, the 1.61 µm radiation. It is noteworthy that the 1.61 µm image is especially dark over far southeastern Georgia northeastward along the immediate coastline of South Carolina. These are regions where freezing rain and sleet fell, versus predominantly snow to the north and west (as also noted here; The National Weather Service in Tallahassee tweeted out an ice/snow accumulation map that also agrees with the 1.61 µm image). Ice in the cirrus clouds northeast of North Carolina is also apparent in the Snow/Ice 1.61 µm imagery.
Suomi NPP overflew the storm shortly after midnight on 4 January; Day Night band visible imagery (courtesy Kathleen Strabala, CIMSS), below, shows a well-developed cyclone covering much of the northeast Atlantic Ocean. Snow cover is apparent over the deep south of the United States.
(Added, 5 January 2018: This website shows a during-the-day CIMSS True Color Image animation of the storm on 4 January 2018. Animation courtesy Dave Stettner, CIMSS).
In a toggle between Suomi NPP VIIRS true-color and false-color Red-Green-Blue (RGB) images from RealEarth (below), the deeper snow cover in Georgia appears as darker shades of cyan.
===== 04 January Update =====A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC (1:20 AM Eastern time) on 04 January (above; courtesy of William Straka, CIMSS) showed a nighttime view of the rapidly-intensifying storm when it had an estimated minimum central pressure of 972 hPa or 28.70″. Note the signature of snow cover — extending from southeastern Georgia across eastern portions of South Carolina and North Carolina — which is evident on the “visible image at night” Day/Night Band (made possible by ample illumination from the Moon, which was in the Waning Gibbous phase at 92% of Full). A full-resolution version of the Day/Night Band image is available here.
During the following daytime hours, 30-second interval Mesoscale Sector GOES-16 “Red” Visible (0.64 µm) images (below) showed the evolution of the low pressure center of circulation as it continued to rapidly intensify (surface analyses) off the US East Coast.
Curious about the historical context of this system impacting the East Coast? Interestingly, there was a similar system WPC found that dated back to–oddly enough–January 4, 1989. pic.twitter.com/WcNbJUp2yp
— NWS WPC (@NWSWPC) January 4, 2018