* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

Strong summer monsoon season thunderstorms developed over Arizona in the pre-dawn nighttime hours on 17 July 2017, producing damaging winds across the Phoenix area (SPC storm reports). A Terra MODIS Infrared Window (11.0 µm) image (above) revealed cloud-top brightness temperatures as cold as -77ºC at 0508 UTC.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed the development and eventual dissipation of the overnight convection.

During the following daytime hours, GOES-16 “Red” Visible (0.64 µm) images (below) displayed the circulation of a Mesoscale Convective Vortex (MCV) as it propagated west-southwestward across southern Arizona. Note that surface dewpoint temperatures were in the upper 60s to low 70s F across southern Arizona, an indicator of the monsoon moisture that was in place across the region. The MCV appeared to play a role in helping to force the development of new thunderstorms later in the afternoon in the vicinity of the Arizona/Mexico border.

On the previous evening, a Mesoscale Discussion from SPC (below) mentioned the presence of weak deep-layer wind shear over the portion of Arizona affected by these nighttime severe thunderstorms — MCVs often form in such a low-shear environment.

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GOES-16 ABI and GLM data posted on this page are preliminary, non-operational and are undergoing testing

Strong morning thunderstorms with a few severe weather reports, and abundant heavy rain (24-h totals ending 1200 UTC on 12 July 2017, from here), spread over the northern part of the GOES-16 default western Mesoscale Sector on the morning of 12 July 2017. The animation above shows the GOES-16 Advanced Baseline Imager (ABI) 10.3 µm imagery with Geostationary Lightning Mapper (GLM) Lightning Flash event locations superimposed, at 1-minute timescales. The top of the default Mesoscale Sector cuts through central Wisconsin.

Click here to see a graphic with the GLM Flashes for the 3 different hours.

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A comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images on 12 July 2017 (above; courtesy of William Straka, SSEC) shows the large iceberg (named A-68) that had separated from the Larsen-C ice shelf in Antarctica (Project MIDAS).

===== 13 July Update =====

A 12 July vs 13 July comparison of VIIRS Infrared Window and Day/Night Band images (below) revealed a slight expansion of the ice fracture, as Iceberg A-68 slowly drifted away from the Larsen-C ice shelf.

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* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

Severe thunderstorms developed in the warm sector of a mid-latitude cyclone that was moving eastward along the US/Canada border on 11 July 2017.  GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the storms that produced tornadoes, wind gusts to 80 mph and hail as large as 2.00 inches (SPC storm reports) across far eastern North Dakota and far northwestern Minnesota (NWS Grand Forks summary). Time-matched SPC storm reports are plotted on the images — the report locations are parallax-corrected to match the location of the cloud-top features. Overshooting tops were very evident on the Visible and Infrared imagery; in addition, pronounced cold/warm Thermal Couplets and/or Enhanced-V signatures were seen in the Infrared images.

Farther to the south, other storms (below) produced hail as large as 3.00 inches and wind gusts to 75 mph across northeastern South Dakota (NWS Aberdeen summary).

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