H/T to Brian McNoldy for sending this out on Twitter:

#Miami‘s morning sounding observed 2.18″ of precipitable water, breaking the previous 17May 12Z record of 1.97″ pic.twitter.com/7Kh4Yokovc

— Brian McNoldy (@BMcNoldy) May 17, 2016

Hourly images of the MIMIC Total Precipitable Water (TPW) product (below) revealed the northward transport of deep tropical moisture from the Caribbean during the 16 May – 17 May 2016 period, with TPW values near Miami (KMFL) around 55 mm or 2.17 inches at 12 UTC on 17 May.

A comparison of the 00 UTC and 12 UTC Miami soundings (below) showed the increase of moisture within the middle to upper troposphere that helped contribute to the daily record maximum TPW value of 2.18 inches at 12 UTC.

The northward surge of tropical moisture also helped to fuel the development of a large mesoscale convective system over the eastern Gulf of Mexico, as seen in 4-km resolution GOES-13 Infrared Window (10.7 µm)  imagery (below). Cloud-top IR brightness temperatures were as cold as -80º C (violet color enhancement) at times with this storm.

A comparison of 1-km resolution Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1632 UTC is shown below.

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The GOES-14 satellite remained in Super Rapid Scan Operations for GOES-R (SRSO-R) mode for part of the day on 11 May 2016; Infrared Window (10.7 µm) images (above) showed the nocturnal development of a severe thunderstorm ahead of an approaching occluded front (surface analyses) that dropped large amounts of hail in the northwestern section of Omaha, Nebraska (station identifier KOMA), stripping trees of foliage and clogging some city streets (even requiring the use of snow plows and shovels: photo 1 | photo 2). The storm began to exhibit an “enhanced-V” signature just prior to the time that it started producing large hail in Omaha. Note: the plotted location of the SPC storm reports on this animation (and all animations on this blog post) have been parallax-corrected, moving them slightly north-northeastward to match the location of cloud top features having a mean altitude of 10 km. The letters UNK after a W wind report denotes “unknown intensity”.

During the late afternoon and early evening, GOES-14 Visible (0.63 µm) images (below; also available as a large 59 Mbyte animated GIF) revealed additional thunderstorms which produced hail and damaging winds across eastern Missouri and southern Illinois (SPC storm reports). These storms fired along an outflow boundary left in the wake of another mesoscale convective system (MCS)  that moved through the region earlier in the day.

Side note: there was a planned outage of GOES-14 SRSO-R imagery from 1059-2119 UTC. During this time, the GOES-13 (GOES-East) satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-7 minutes. Visible (0.63 µm) images (below) showed the mesoscale convective system that produced hail as large as 4.0 inches in diameter in the St. Louis, Missouri area.

Finally, late in the day another MCS developed in North Texas, just west of the Dallas/Fort Worth area. GOES-14 Visible (0.63 µm) images with parallax-corrected SPC storm reports (below; also available as a large 54 Mbyte animated GIF) showed the large hail and damaging winds produced by this storm. One feature of interest was the “storm-top plume” that emanated from the largest cluster of overshooting tops, and was blown northeastward.

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Widespread severe thunderstorms (SPC storm reports) developed across Nebraska, Kansas and Oklahoma in the warm sector of a surface low centered over western Kansas (surface analyses) on 09 May 2016. The GOES-14 satellite was operating in Super Rapid Scan Operations for GOES-R (SRSO-R) mode, providing images at 1-minute intervals; Visible (0.63 µm) images with overlays of SPC storm reports covering Nebraska/Kansas (above; also available as a large 133 Mbyte animated GIF) and Kansas/Oklahoma (below; also available as a large 130 Mbyte animated GIF) showed the development of the convection during the 1845 UTC to 0115 UTC (3:45 pm to 8:15 pm local time) period. The first EF4-rated tornado of the 2016 season (which was responsible for 1 fatality) occurred near Katie, Oklahoma; hail was as large as 4.25 inches in diameter Nebraska and 4.0 inches in Oklahoma.

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GOES-15 (GOES-West) Visible (0.63 µm) and Shortwave Infrared (3.9 µm) images (above) showed the hot spot (dark black to yellow to red pixels) and the development of pulses of pyrocumulonimbus (pyroCb) clouds associated with a large wildfire located just to the west of Fort McMurray, Alberta (station identifier CYMM) on 03 May 2016. The fire — which started on 01 May (Wikipedia) — caused a mandatory evacuation of the nearly 90,00 residents of the city (the largest fire-related evacuation in Alberta history). Note that the hourly surface plots indicated a temperature of 90º F (32.2º C) at 22-23 UTC — in fact, a new daily record high temperature of 32.6º C was set for Fort McMurray (time series plot of surface data).

The corresponding GOES-15 Visible (0.63 µm) and Infrared Window (10.7 µm) images (below) revealed cloud-top infrared brightness temperature values as cold as -58º C (darker red color enhancement) at 0030 and 0100 UTC on 04 May.

A comparison of Suomi NPP VIIRS false-color “Snow vs cloud discrimination” Red/Green/Blue (RGB), Visible (0.64 µm), Shortwave Infrared (3.74 µm), and Infrared Window (11.45 µm) images at 1834 UTC (above) showed that while a large fire hot spot was apparent on the Shortwave Infrared image, there was no clear indication of any pyrocumulus cloud development at that time. However, a similar image comparison at 2018 UTC (below) revealed that a well-defined pyroCb cloud had formed (with a cloud-top infrared brightness temperature as cold as -60º C, dark red color enhancement) which was drifting just to the north of the Fort McMurray airport (whose cyan surface report is plotted near the center of the images). A 2104 UTC NOAA-19 AVHRR image provided by René Servranckx showed a minimum IR brightness temperature of -59.6º C.

A closer look using Suomi NPP VIIRS true-color RGB and Shortwave Infrared (3.74 µm) images from the SSEC RealEarth site (below) showed the initial pyroCb cloud as it had drifted just east of Fort McMurray, with the early stages of a second pyroCb cloud just south of the city.

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 1015 UTC or 3:15 am local time (below; courtesy of William Straka, SSEC) showed the bright glow of the large Fort McMurray wildfire, as well as the lights associated with the nearby oil shale mining activity.

A sequence of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images covering the 02 April – 04 April period (below) showed the diurnal changes as well as the overall growth of the fire hot spot (darker black pixels).

===== 05 May Update =====

The GOES-14 satellite was operating in Super Rapid Scan Operations for GOES-R (SRSOR) mode, providing images at 1-minute intervals — and the scan sector was positioned to monitor the Fort McMurray wildfire on 05 May. GOES-14 Visible (0.63 µm) and Shortwave Infrared (3.9 µm) images (below; also available as a large 133 Mbyte animated GIF) showed the growth of the smoke plume and fire hot spot signature (black to yellow to red pixels).

A 30-meter resolution Landsat-8 false-color Red/Green/Blue (RGB) image (below) showed the size of part of the fire burn scar (darker brown) as well as the active fires (bright pink) along the perimeter of the burn scar.

===== 06 May Update =====

The Fort McMurray fire continued to produce a great deal of smoke on 06 May, and the coverage and intensity of fire hot spots increased during the afternoon hours as seen on 1-minute GOES-14 Visible (0.63 µm) and Shortwave Infrared (3.9 µm) images (below; also available as a large 180 Mbyte animated GIF).

===== 13 May Update =====

A comparison of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images at 0906 UTC or 3:06 am local time (above) showed the fire hot spots (dark gray to yellow to red pixels) and their nighttime glow.

A time series of VIIRS Shortwave Infrared (3.74 µm) images covering the 04-13 May period (below) revealed the rapid early growth of the fire, and the continued slow spread of the fire periphery toward the Alberta/Saskatchewan border. On 13 May the total size of the area burned by the Fort McMurray fire was estimated to be 241,000 hectares or 595,524 acres.

===== 16 May Update =====

Strong southerly winds ahead of an approaching trough axis (surface analyses) created favorable conditions for rapid fire growth on 16 May — GOES-15 Visible (0.63 µm) and Shortwave Infrared (3.74 µm) images (above) showed the development of pyrocumulus clouds (first on the far western flank of the fire around 1930 UTC, then later in the eastern portion of the fire area). This new flare-up of fire activity prompted additional evacuations of some oil sands work camps and facilities north of Fort McMurray.

A comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 1932 UTC (below) showed that a small pyroCb had developed, which exhibited a cloud-top IR brightness temperature of -41.48 C.

A toggle between the corresponding VIIRS true-color RGB image and Shortwave Infrared images is shown below.

A time series plot of surface weather conditions for Fort McMurray (below) shows that during prolonged periods of light winds, the surface visibility dropped below 1 mile at times. The air quality at Fort McMurray was rated as “extreme“, and deemed unsafe for residents to return to the city.

===== 17 May Update =====

A shift to westerly winds followed the passage of a surface trough axis on 17 May (surface analyses), which slowed the northward progress of the fire. GOES-15 Visible (0.63 µm) and Shortwave Infrared (3.9 µm) images (above; also available as an MP4 animation) continued to show a great deal of thick smoke over the region, with hot spots from active fires.

However, during the afternoon hours multiple pyroCb clouds were seen to develop along the eastern flank of the fire. A comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2054 UTC (below) revealed the pyroCb clouds, which exhibited cloud-top IR Window brightness temperatures as cold as -57º C (darker orange color enhancement).

A comparison of GOES-15 Shortwave Infrared (3.9 µm) and Infrared Window (10.7 µm) images (below; also available as an MP4 animation) showed the development of the pyroCb clouds around 2000 UTC, whose anvil debris moved rapidly southeastward; these pyroCb clouds exhibited a darker gray appearance on the shortwave IR images, along with cloud-top IR Window brightness temperatures as cold as -52º C (light orange color enhancement). Lightning strikes were detected during the early stages of pyroCb growth.

===== 18 May Update =====

Daily Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images covering the period 04 May to 18 May 2016 are shown above. The rapid growth of the perimeter of fire hot spots (yellow to red color enhancement) is quite evident during the first few days; patches of thick cloud cover tended to mask the fire hot spots during the middle of the period, but then another increase in hot spot growth is seen beginning on 16 May.

This event is also discussed here.

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