Severe thunderstorms, as viewed by 4 GOES

August 2nd, 2017 |
GOES-15, GOES-14, GOES-16 and G0ES-13 Visible images, with SPC storm reports of hail size plotted in red [click to play animation]

GOES-15, GOES-14, GOES-16 and G0ES-13 Visible images, with SPC storm reports of hail size plotted in red [click to play animation]

* 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.

GOES-15, GOES-14, GOES-16 and GOES-13 Visible images, with SPC storm reports of hail size plotted in red [click to play animation]

GOES-15, GOES-14, GOES-16 and GOES-13 Visible images, with SPC storm reports of hail size plotted in red [click to play animation]

1 week of Upper Midwest MCS activity: a GOES-16 overview

July 26th, 2017 |
GOES-16 Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm) images [click to play MP4 animation]

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

During the week of 19 July26 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).

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

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).

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

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).

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

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

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

GOES-16 Infrared Window (10.3 µm) image [click to enlarge]

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.

7-day total precipitation, departure from normal and percent of normal [click to enlarge]

7-day total precipitation, departure from normal and percent of normal [click to enlarge]

Tornado in Maryland

July 24th, 2017 |

GOES-16 Infrared Window (10.3 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

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

An isolated thunderstorm that was moving eastward across Maryland just after Midnight on 24 July 2017 intensified as it crossed Chesapeake Bay, eventually producing a waterspout which moved onshore near Bay City (just southwest of Stevensville/Bay Bridge Airport, station identifier KW29) — this tornado was responsible for 1 injury and EF2-rated damage (NWS Mount Holly PNS  | SPC storm reports). GOES-16 “Clean” Infrared Window (10.3 µm) images (above; also available as a 23-Mbyte animated GIF) showed that there were 3 distinct “pulses” when cloud-top infrared brightness temperatures cooled to the -71 to -75º C range (lighter gray pixels embedded within dark black regions) before the storm produced the tornado at 0529 UTC. Since one of the default GOES-16 Mesoscale Sectors was providing coverage over the eastern US, imagery was available at 1-minute intervals.

A comparison of 1-minute GOES-16 vs 15-minute GOES-13 (GOES-East) Infrared Window images (below; also available as a 17-Mbyte animated GIF) provided a convincing demonstration of the value of more frequent image scan intervals for monitoring severe convection. The improved spatial resolution of GOES-16 Infrared imagery — 2 km at satellite sub-point, vs 4 km for GOES-13 — also allowed for a more accurate depiction of cloud-top IR brightness temperature patterns and values.

1-minute GOES-16 (10.3 µm, left) vs 15-minute GOES-13 (10.7 µm, right) Infrared Window images [click to play MP4 animation]

1-minute GOES-16 (10.3 µm, left) vs 15-minute GOES-13 (10.7 µm, right) Infrared Window images [click to play MP4 animation]

Midwest derecho

July 19th, 2017 |

GOES-16 Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

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

A long-lived mesoscale convective system (MCS) known as a derecho produced swath of damaging winds — as well as some large hail and a couple of tornadoes — that stretched from north-central South Dakota to northwestern Indiana on 19 July 2017 (SPC storm reports | TWC summary). GOES-16 “Clean” Infrared Window (10.3 µm) images (above) showed the southeastward propagation of the storm system.

Closer views of the early stages of the derecho as it moved across central and eastern South Dakota are shown below, using GOES-16 “Red” Visible (0.64 µm) and Infrared Window (10.3 µm) images. The highest measured wind gust was 100 mph near Polo (1522 UTC), with 83 mph recorded at Huron (1636 and 1730 UTC). Hail of 2.50 inches in diameter fell near Cavour (1703 UTC). Note that most of the severe reports were in the general vicinity of the persistent cold overshooting top (black to white enhancement) seen on the Infrared imagery; due to parallax, the apparent location of this storm-top feature was shifted slightly north of its true location.

GOES-16 Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

1-km resolution Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at (below) showed the MCS over the Huron (KHON) area at 1656 UTC. Since there is minimal parallax associated with polar-orbiter satellite imagery, the cluster of SPC storm reports (occurring within +/- 30 minutes of the time of the MODIS image) was much closer to the cold (-70 to -73º C, lighter gray enhancement) overshooting top. Another feature of interest seen on the Infrared image was a “warm trench” (exhibiting brightness temperatures as warm as -60º C, red enhancement) immediately surrounding the cold overshooting top — perhaps a result of compensating subsidence?

Terra MODIS Visible and Infrared Window (11.0 µm) images, with SPC storm reports [click to enlarge]

Terra MODIS Visible and Infrared Window (11.0 µm) images, with SPC storm reports [click to enlarge]

375-meter resolution Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1846 UTC (below) provided a detailed view of the MCS as it was centered near the South Dakota / Minnesota border. The coldest cloud-top IR brightness temperature was -83º C (violet enhancement).

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with SPC storm reports [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with SPC storm reports [click to enlarge]