Tropical Depression Three has formed in the Atlantic Ocean southeast of Cape Hatteras. The visible animation above (click the image to play an animated gif) shows strong convection with overshooting tops mostly south and west of a low-level circulation. The cold front over the eastern United States, and an upper-level Low that is moving inland over Florida, are also apparent. Because the depression is within GOES-16’s CONUS Domain, 5-minute imagery is available to monitor this system.

A variety of GOES-16 images and products can be used to discern whether this storm will develop (The National Hurricane Center suggests slow motion and slow development: Click here for details).

The low-level Water Vapor field, below (7.34 µm) from 2122 UTC, shows little dry air in the path of the storm. The Total Precipitable Water derived from GOES-16 ABI data similarly shows rich moisture surrounding the storm.

GOES-16 Estimates of Sea Surface Temperature, below, color-enhanced such that waters warmer than 27 º C are violet, shows warm surface waters. Gulf Stream temperatures, northwest of the Depression, are at 30-31 º C.

For more information on this system, please see the website of the National Hurricane Center and the CIMSS Tropical Weather Website.

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Typhoon Maria underwent a period of rapid intensification (ADT | SATCON) while it was just northwest of Guam late in the day on 05 July 2018, becoming the first Category 5 Super Typhoon of the 2018 West Pacific season. Rapid-scan Himawari-8 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed Maria during this period of rapid intensification. Cloud-top infrared brightness temperatures reached -80ºC (violet enhancement) at times in the eyewall of the storm.

A GPM GMI Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) showed the pinhole eye of Maria around the time it reached Category 5 intensity. The tropical cyclone was moving over water with high values of Ocean Heat Content — and was in an environment characterized by low values of Deep-layer Wind Shear.

Mesovortices could be seen within the eye on Himawari-8 Visible imagery (below). However, note how the eye became less distinct and increased in diameter toward the end of the animation.

Shortly after 00 UTC on 06 July, Maria began the process of an eyewall replacement cycle as shown in MIMIC TC morphed microwave imagery (below) — and during the following 6-12 hours a decreasing trend in storm intensity was seen (ADT | SATCON).

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1603 UTC on 06 July (below; courtesy of William Straka, CIMSS) showed Category 4 Typhoon Maria after the eye had filled following the eyewall replacement cycle.

===== 08 July Update =====

Super Typhoon Maria re-intensified to Category 5 intensity at 12 UTC on 08 July (SATCON) — Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) displayed a large (30 nautical mile wide) eye. The subtle signature of mesovortices could be seen rotating within the eye.

During the preceding daylight hours, Himawari-8 “Red” Visible (0.64 µm) images (below) showed the eye mesovortices in better detail.

However, Maria was again downgraded to a Category 4 storm at 00 UTC on 09 July, as another eyewall replacement cycle took place (DMSP-17 microwave image) and the storm began to move over water having slightly cooler Sea Surface Temperature and Ocean Heat Content. The eye and its mesovortices continued to be prominent in Himawari-8 Visible and Infrared imagery (below).

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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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