The season’s second named tropical cyclone in the Atlantic Basin has formed.  GOES-16 visible imagery, above (click to play an animated gif), shows Tropical Storm Beryl moving westward just north of 10 º N Latitude between 40 º and 50 º W Longitude.  The infrared imagery (10.3 µm), the Clean Window, below shows a compact storm with cold cloud tops and a central dense overcast.

Much of the tropical Atlantic north of 10 N Latitude shows little convection.  This is because of a Saharan Air Layer, shown below (in red) from a screen capture from the CIMSS Tropical Website (Click here for the latest SAL analysis). An important component of the SAL analysis is the Split Window Difference field (10.3 µm – 12.3 µm) that can diagnose both moisture and dust. The SAL analysis shows considerable dry Saharan air over the Atlantic; Beryl has formed along its southern edge. Compare the SAL analysis to the Split Window Difference field, below, that shows dry air in blue. Similar features are present in both. The GOES-16 Low-Level Water Vapor Infrared Imagery (7.34 µm), here, shows similar features as well. There are multiple ways to diagnose dry air with GOES-16.

NUCAPS Soundings from Suomi NPP can be used to diagnose the thermodynamics of the atmosphere surrounding Beryl. The image below shows NUCAPS Soundings locations between 1500 and 1600 UTC on 5 July 2018, and the points are color-coded to describe the data (as discussed here). A Sounding near 16.3 N, 43.1 W (north of Beryl) shows dryness at mid-levels; total precipitable water is only 1.27″. A Sounding closer to the storm, at 10.3 N, 43.5 W (west of Beryl) is much wetter: total precipitable water is 2.12″. NUCAPS Soundings are available online (over the Continental US only) here.

Very small (in size) Beryl is forecast to strengthen in the short term. See the National Hurricane Center website and the CIMSS Tropical Website for more information.

==== Update 6 July 2018 ====Beryl has strengthened and is a hurricane, as of 0900 UTC on 6 July, the first hurricane of the 2018 Atlantic Hurricane season. The sandwich product animation below, courtesy Rick Kohrs and Joleen Feltz, CIMSS, that combines visible (0.64 µm) and clean window infrared (10.3 µm) imagery shows the appearance and subsequent disappearance of a very small eye.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed the merger of two Mesoscale Convective Systems over North Dakota and South Dakota during the nighttime (pre-sunrise) hours on 04 July 2018. In addition to hail of 1.00-2.00 inches in diameter, these thunderstorms produced widespread damaging winds up to 95 mph in north-central South Dakota (SPC storm reports).

Nighttime comparisons of VIIRS instrument Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) imagery from the Suomi NPP and NOAA-20 satellites are shown below (courtesy of William Straka, CIMSS). With illumination from the Moon (which was in the Waning Gibbous phase, at 68% of Full), the “visible image at night” capability of the Day/Night Band was demonstrated; numerous bright lighting streaks could also be seen, with many in the vicinity of the cold overshooting tops that were evident on Infrared imagery. The Infrared images also revealed cloud-top gravity waves which were propagating radially outward away from the primary clusters of cold overshooting tops.

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GOES-16 (GOES-East) False Color Red-Green-Blue (RGB) images from the NOAA/CIMSS Volcanic Cloud Monitoring site (above) showed another eruption of the Sierra Negra volcano on the Galapagos, which began late in the day on 01 July 2018. Since the volcanic plume was rich in SO2, it exhibited a cyan appearance in the RGB imagery.

As was demonstrated following the 26 June eruption, GOES-16 Low-level Water Vapor (7.3 µm) imagery (below) can also be used to initially track volcanic plumes that have high concentrations of SO2 (since this spectral band is also sensitive to SO2 absorption).

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The County Fire began burning in central California (northwest of Sacramento) around 2112 UTC or 2:12 pm local time on 30 June 2018 — GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke plume and thermal anomaly or “hot spot” (dark black to red pixels) of the fire during its initial 6.5 hours. Other features of interest in the imagery included reflection of sunlight from solar panel farms as seen here and here, as well as sun glint off the waters of the Sacramento River and the Sacramento-San Joaquin River Delta as seen here.

During the subsequent overnight hours, the thermal signature exhibited on GOES-16 Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images (below) revealed the rapid southward spread of the fire along the Napa/Yolo county line — the fire began in far western Yolo County, and eventually moved into far eastern Napa County. The smaller, less intense fire signature seen just to the northwest was that of the Pawnee Fire.

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images (below) showed the thermal anomaly and bright glow of the County fire at 1043 UTC or 3:43 am local time. Due to ample illumination from the Moon (in the Waning Gibbous phase, at 90% of Full), the smoke plume could be seen drifting southwest over the adjacent waters of the Pacific Ocean — note the shadow cast by the smoke plume upon the fog/stratus deck immediately off the coast.

A toggle between consecutive Suomi NPP VIIRS Day/Night Band (0.7 µm) images (below) showed the change in location of the smoke plume during the ~1 hour and 40 minutes separating the 2 satellite overpasses. The region was on the far western edge of the earlier swath. These images demonstrate the “visible image at night” capability of the VIIRS Day/Night Band.

The 00 UTC rawinsonde data from nearby Oakland (below) showed northeasterly winds at altitudes of 1500-2800 meters or 4900-9200 feet.

During the late morning and early afternoon of 01 July, the fire burn scar could be seen beneath the smoke plume on 250-meter resolution Terra and Aqua MODIS False Color Red-Green-Blue (RGB) images viewed using RealEarth (below).

===== 03 July Update =====

A 30-meter resolution Landsat-8 False Color RGB image (above) showed the areal extent of the County Fire burn scar on the morning of 03 July. Pink-colored pixels indicated hot signatures of actively-burning fires. The morning Incident Report listed the fire size at 70,000 acres and 5% containment.

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