Suomi-NPP and NOAA-20 overflew tropical depression Alberto, at 0722 and 0812 UTC, respectively (orbit paths from this site), on 30 May 2018, and the near-Full moon provided ample illumination for the Day Night Band imagery, shown above.  A motion to the northeast is apparent.  Convection developed far to the north of the storm as well, south of Chicago, and a streak of lightning occurs over Oklahoma in the later image.  (For individual Day Night Band images in the loop, click here for Suomi NPP and here for NOAA-20) A similar loop, below, shows the Window Channel (11.45 µm) from the VIIRS instrument on Suomi NPP and NOAA-20. A tip of the Hat to Will Straka, CIMSS, for the imagery.

Added: NOAA-20 was declared Operational on 30 May 2018. Welcome NOAA-20!

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A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0731 UTC or 3:31 am local time (above; courtesy of William Straka, CIMSS) showed Subtropical Storm Alberto when it was centered off the southwest coast of Florida on 27 May 2018. Note that NOAA-20 imagery is still considered preliminary and non-operational.

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below) revealed that dry air was wrapping into the circulation of Alberto during the day.

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) and “Clean” infrared Window (10.3 µm) images (below) showed that the low-level circulation center of Alberto became partially exposed, and the areal coverage and intensity of deep convection diminished somewhat during the day as the dry air was being entrained into the storm.

===== 29 May Update =====

A composite of GOES-16 1-minute Mesoscale Domain Sector “Clean” Infrared Window (10.3 µm) images for the period 1630 UTC on 26 May to 1000 UTC on 29 May 2018 (above; courtesy of Pete Pokrandt, AOS) showed Subtropical Storm Alberto as it moved northward across the Gulf of Mexico and eventually inland over Alabama.

 

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GOES-16 (GOES-East) “Red” Visible (0.64 um) images (above) showed an isolated supercell thunderstorm that moved south-southwestward across North Texas on 25 May 2018 — producing a nearly continuous swath of large hail and damaging winds (SPC Storm Reports). Beginning at 2000 UTC, a Mesoscale Domain Sector was positioned over the area, providing images at 1-minute intervals. In addition, a well-defined Above-Anvil Cirrus Plume could be seen with this thunderstorm, extending eastward from the core overshooting top region.

After sunset, GOES-16 Nighttime Microphysics Red-Green-Blue (RGB) images (below) revealed the northeast-to-southwest oriented hail swath.

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The National Hurricane Center has assigned the name ‘Alberto’ to region of low pressure that has persisted near the northwest Caribbean Sea for the past week. The low-level water vapor (7.34 µm) animation, above, shows abundant mid-tropospheric moisture to the east of the system. Dryer mid-level conditions are apparent west of Alberto: the storm structure is very asymmetric. Sheared systems such as this one typically do not strengthen quickly.

A plot of shear (from this site), below, shows Alberto in a region of westerly shear, with a forecast path towards a region that currently has higher shear — part of which is outflow. However, forecast models suggest the shear along the forecast path will decrease with time.  Sea-surface temperatures are warm enough to support tropical cyclones, and the forecast path is towards warmer waters.

Visible imagery, below, shows one low-level circulation center (others may be masked by the convection to the east) that is south and west of the main convection over the Caribbean.

Suomi-NPP overflew this region at 0723 UTC, and a toggle between the Window Channel Infrared (11.45 µm) and the Day Night Band Visible (0.70 µm) imagery (courtesy William Straka) is shown below. The low-level circulation is apparent in the Day Night Band to the west of the deep convection over the northwest Caribbean.

A MIMIC Total Precipitable Water animation, above, shows abundant moisture over the northwest Caribbean. As Alberto lifts to the north, that moisture will shift north as well, and flooding rains are possible over the southeastern United States. Flood Watches have been raised over Louisiana, Mississippi, Alabama and Georgia (below, from this site).

The Geostationary Lightning Mapper (GLM) on GOES-16 observed lightning in the deep convection to the east of the system center. GLM is overlain on both infrared (top) and visible (bottom) imagery below (animations courtesy Dave Santek, CIMSS). The updating infrared animations are available here. GLM data for this system can also be viewed in RealEarth.

Updates on this system are sent every six hours from the National Hurricane Center. You can find more information there, or at the CIMSS Tropical Weather Website.

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