Severe weather across southeastern Idaho

May 31st, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with plots of SPC storm reports [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed thunderstorms which produced hail, damaging winds and tornadoes (SPC storm reports) across southeastern Idaho on 31 May 2018. Note that after 2102 UTC a pronounced “enhanced-v” infrared storm top signature was exhibited by the larger supercell which produced most of the severe weather. The SPC storm reports on the imagery are “parallax-corrected”, such that they are plotted at a location matching the corresponding cloud-top features (applying the 10-km tropopause height from the 00 UTC Boise rawinsonde report).

As a surface cold front was moving through Idaho, large-scale forcing for ascent was increasing across the region within the middle troposphere as an upper-level trough moved eastward over California and Nevada — and strong southwesterly flow ahead of this trough was evident over eastern Idaho on GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below).

GOES-16 Lower-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play MP4 animation]

GOES-16 Lower-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play MP4 animation]



Suomi NPP and NOAA-20 view Tropical Depression Alberto over the lower Ohio River Valley

May 30th, 2018 |

Day Night Band Visible (0.7 µm) Imagery from Suomi NPP (0722) and NOAA-20 (0812 UTC) over Tropical Depression Alberto (Click to enlarge)

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.

VIIRS Window Channel (I05) Infrared (11.45 µm) Imagery from Suomi NPP (0722) and NOAA-20 (0812 UTC) over Tropical Depression Alberto (Click to enlarge)

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

Subtropical Storm Alberto gradually intensifies

May 27th, 2018 |

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

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.

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play MP4 animation]

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.

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of ship and buoy reports [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of ship and buoy reports [click to play MP4 animation]

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

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 [click to play YouTube video]

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.

 

Large hail in North Texas

May 25th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 um) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

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.

GOES-16 Nighttime Microphysics RGB images [click to play animation | MP4]

GOES-16 Nighttime Microphysics RGB images [click to play animation | MP4]