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

With a Severe Thunderstorm Watch in place, storms developed over far northeastern Colorado late in the day on 02 August 2017 which produced hail as large as 2.0 inches in diameter (SPC storm reports). Since GOES-14 (which had been placed into on-orbit storage as a spare satellite) was briefly activated for testing and evaluation, it afforded the unusual opportunity to view these storms from 4 different GOES perspectives (above). The Visible images (0.63 µm for the 3 legacy GOES, and 0.64 µm for GOES-16) are displayed in the native projections for each satellite.

A closer look using a higher image zoom factor (below) helps to demonstrate the advantage of higher spatial resolution with the GOES-16 0.64 µm “Red” Visible band (0.5 km at satellite sub-point, vs 1.0 km for the 3 legacy GOES) — especially for clearly identifying features such as thunderstorm overshooting tops. Also note that the 3 legacy GOES visible images do not appear as bright as those from GOES-16; visible imagery from GOES degrades with time, and older GOES Imager instruments do not have on-board calibration to account for this. However, the GOES-16 ABI instrument does have on-board visible detector calibration, so dimming of visible imagery over time should not be as noticeable.

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

Tropical Storm Emily has formed in the eastern Gulf of Mexico on 31 July 2017, just to the west of Tampa/St. Petersburg, Florida. Its presence is possibly related to the surface front that has sagged south into Florida over the weekend.  (Sea Surface Temperatures in the area are very warm as well.) In the Visible (0.64 µm) animation above (a slower animation is available here), the curved bands of the low-level cloud field are noticeable just northwest of the large convective cluster near Tampa Bay.  Clean Window (10.3 µm) Infrared Imagery shows that offshore convection waned between 1100 and 1300 UTC, shifting to a location just south of Tampa.  (Click here for a slower animation)

About an hour after Emily made landfall, a toggle between Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images, below, showed the compact cluster of deep convection — cloud-top infrared brightness temperatures were as cold as -74º C just off the Florida coast.

For more information on Emily, refer to the National Hurricane Center website, or to the CIMSS Tropical Weather Pages.

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

Can you find the plane near Des Moines? #contrail #GOES16 pic.twitter.com/H6kQQzrlc6

— NWS Des Moines (@NWSDesMoines) July 28, 2017

An aircraft “dissipation trail” formed over far southern Iowa during the late morning hours on 28 July 2017 — which was seen on GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61  µm) and Shortwave Infrared (3.9) µm) imagery (below).

As explained in this blog post, these types of cloud features are caused by aircraft either ascending or descending through a cloud layer composed of supercooled water droplets. Cooling from wake turbulence (reference) — and/or the particles from the jet engine exhaust acting as ice condensation nuclei — then cause the small supercooled water droplets to change phase and transform into larger ice crystals (which often fall from the cloud layer, creating “fall streak holes“).

Therefore, the glaciated aircraft dissipation trail appears darker on the 1.61 µm “snow/ice” images (since ice is a strong absorber of radiation at that wavelength), and colder (brighter white) on the 3.9 µm shortwave infrared images.

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

During the week of 19 July – 26 July 2017, the Upper Midwest was affected  by a number of strong to severe Mesoscale Convective System (MCS) events, as shown in an animation of GOES-16 “Clean” Infrared Window (10.3 µm) images (above).

At the beginning of that time period, a derecho moved across the region on 19 July producing widespread damaging winds, large hail and a few tornadoes (blog post).

Following the derecho, a separate outbreak of thunderstorms exhibited well-defined “enhanced-V” storm top signatures in western Wisconsin (below).

Another MCS produced tornadoes and damaging winds across eastern Iowa and northern Illinois on 21 July (SPC storm reports) — at one point a storm in northern Illinois exhibited a seldom-seen “warm trench” surrounding an overshooting top (below).

Early in the day on 23 July, “transverse banding” — a signature indicating the likelihood of high-altitude turbulence — was seen around the northern periphery of an MCS that was centered in southern Illinois (below).

A pattern of mesoscale banding was displayed by thunderstorms that produced localized 1-2″ amounts of rainfall across southern Wisconsin on 26 July (below).

Also noteworthy was the swath of very heavy rainfall during this 1-week period across eastern Iowa, far southwestern Wisconsin and northern Illinois (below), which was responsible for flash flooding in those areas.

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