GOES-16 and Fog Detection

October 18th, 2017 |

GOES-16 Brightness Temperature Difference (10.3 µm – 3.9 µm) “Fog Product” from 0202 – 0357 UTC on 18 October 2017 (Click to animate)

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

Stratus and Fog formed over the valleys of Kentucky (and in surrounding states) early on 18 October 2017 (It was there on 17 October as well). When was the fog first obvious from Satellite imagery? It very much depends on the spatial resolution of the Satellite viewing the scene. The Brightness Temperature Difference field (10.3 µm – 3.9 µm) from GOES-16, shown above, can be used to identify regions of stratus clouds that are made up of water droplets. Carefully examine the animation; the time when fog is definitively present over valleys of eastern Kentucky (around 84º W Longitude) is around 0327 UTC.

GOES-16 has 2-km resolution (at the sub-satellite point — 89.5º W Longitude during GOES-16 Check-out); this is superior to GOES-13’s nominal 4-km resolution at the subpoint (75º West Longitude). The GOES-13 Brightness Temperature Difference Field (10.7 µm – 3.9 µm) at 0330 UTC shows no distinct indication of Fog/Stratus over eastern Kentucky. A series of animations of the GOES-13 Brightness Temperature Difference field, from 0215-0345 UTC, from 0415-0500, from 0545-0700 and from 0700-0815 suggest GOES-13 identified the region of fog about 4 hours after GOES-16, at 0730 UTC.

The GOES-13 vs. GOES-16 toggle below, from 0700 UTC on 18 October 2017, shows how the resolution improvement with GOES-16 facilitates earlier detection of fog and stratus as it develops overnight.

Toggle between 0700 UTC 18 October 2017 Brightness Temperature Differences from GOES-13 (10.7 µm – 3.9 µm) and GOES-16 (10.3 µm – 3.9 µm) (Click to enlarge)

GOES-16 Tools to Observe and Monitor Fires

October 9th, 2017 |

GOES-16 Visible (0.64 µm) Imagery, 1522-2017 UTC on 9 October 2017 (Click to animate)

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

GOES-16 provides many tools to the Operational Meteorologist, and to National Weather Service Incident Meteorologists (IMETs), to monitor fires when they occur, such as those over Napa and Sonoma Counties in California (Blog Post). Visible (0.64 µm) and Shortwave Infrared (3.9 µm) channels, above and below, respectively, are available routinely at 5-minute intervals over the Continental United States. During daytime, the Visible Imagery is useful for highlighting smoke palls and for alerting meteorologists to any wind changes. The Shortwave Infrared has long been used to detect fires; the shortwave infrared channel on GOES-16 can detect hotter and smaller fires than previous GOES Satellites because of improved spatial resolution and improved bit depth in the imagery.

GOES-16 Shortwave Infrared (3.9 µm) Imagery, 1522-2017 UTC on 9 October 2017 (Click to animate)

GOES-16 Channels can be combined to create Red Green Blue (RGB) Composites that also help identify fires qualitatively. The Fire RGB, below, combines the shortwave IR (3.9 µm) with the 2.2 µm and 1.6 µm channels; as fires get warmer, radiation is emitted at shorter and shorter wavelengths. When this RGB shows white values, you can be certain that the fire is very hot. At some times in the RGB animation, the 3.9 µm imagery is missing where the fire is exceptionally hot, meaning the ‘red’ component of the RGB has no value, and the RGB acquires a blue and green hue.

GOES-16 Fire Temperature RGB, 1522 – 2017 UTC on 9 October 2017 (Click to animate)

The Fire Temperature RGB like the visible imagery shown above offer qualitative information about fire. More quantitative information is available in GOES-16 Baseline Products that are an extension and refinement of the WF-ABBA products available for GOES-13 and GOES-15 (and other satellites). Fire-related products for GOES-16 include Fire Area and Fire Temperature, shown below. The products give the size of the fire within the pixel, and its temperature. These products are valuable in quickly evolving fires to monitor how things change, and the products are available every 5 minutes.

GOES-16 Fire Area Derived Product, 1522-2017 UTC on 9 October 2017 (Click to animate)

GOES-16 Fire Temperature, 1522-2017 UTC on 9 October 2017 (Click to animate)

Finally, GOES-16 has 1-minute Mesoscale Sectors that can be used to closely monitor quickly-evolving fire situations. The 3.9 µm shortwave infrared and Fire RGB images are shown below for a two-hour period. There can be significant changes to a fire in 1 minute, as was seen in this Blog Post! Note again that missing points in the 3.9 µm imagery will show up as green or blue regions in the RGB.

Fire RGB Product, 1931-2130 UTC on 9 October 2017 (Click to animate)

GOES-16 Shortwave Infrared (3.9 µm), 1933 – 2132 UTC on 9 October 2017 (Click to animate)

Unusual October Tornado in Wisconsin

October 7th, 2017 |

GOES-16 ABI Visible (0.64 µm) Imagery, 2042-2227 UTC on 7 October 2017 (Click to animate)

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

October is typically not a month when tornadoes are expected in Wisconsin. (And in fact, the month ranks fourth in the numbers of fewest tornadoes nationwide). Nevertheless, a brief tornado occurred on the east side of Madison WI late in the afternoon on 7 October (NWS Milwaukee/Sullivan). The visible animation, above, from GOES-16, shows a thin line of weak convection moving through the central part of the state. A slower animation centered on the reported time of the tornado (2200 UTC), is below. The dynamic state of the thunderstorm tops is apparent, and the 5-minute time-step may not be sufficient to resolve the small time-scale changes in the tornadic storm (the two GOES-16 Mesoscale sectors that provide 1-minute imagery were covering the pending landfall of Hurricane Nate at this time, and were giving severe weather support to Puerto Rico, radar-less in the wake of Hurricane Maria).

GOES-16 ABI Visible (0.64 µm) Imagery, 2152-2222 UTC on 7 October 2017 (Click to enlarge)

The Clean Window Channel, below, with the default AWIPS enhancement, shows little cloud-top structure.

GOES-16 ABI Infrared (10.3 µm) Imagery, 1917-2302 UTC on 7 October 2017, default enhancement (Click to animate)

Coldest cloud-top brightness temperatures with this event were in the -15º to -20º C range, and the default enhancement (with a range from -109º to 55º) showed little gradation in that range. By changing the coldest temperature in the enhancement from -109º C to -43º C, however, a structure in the cold clouds emerged, as shown below. Do not be afraid to change enhancements!

GOES-16 ABI Infrared (10.3 µm) Imagery, 1917-2302 UTC on 7 October 2017, adjusted enhancement (Click to animate)

The NOAA/CIMSS ProbSevere products for this event is shown below (from this site). ProbTor values were negligible; however, ProbWind values for the tornadic cell were around 20-24% leading up to the event. In addition, the cell that produced the tornado had the highest probabilities in the identified cells along the line of convection. The single exception occurred at 2235 UTC, after the severe weather event, when the cell to the north briefly (for only five minutes) showed Probabilities exceeding 40%.

NOAA/CIMSS ProbTor, 2130-2235 UTC on 7 October 2017 (Click to enlarge)

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The National Weather Service in Milwaukee/Sullivan WI determined that the tornado was an EF-0 based on a damage assessment. They provided radar imagery at the start of the tornado, during the tornado, at its end, and after dissipation.

Tropical Storm Nate forms near Nicaragua

October 5th, 2017 |

GOES-16 ABI Band 2 Visible (0.64 µm) Imagery, 1127 – 1324 UTC on 5 October 2017 (Click to animate)

GOES-16 Visible Imagery, above, shows convection (imagery at 1-minute intervals) surrounding Tropical Storm Nate, just onshore in northeastern Nicaragua.

GOES-16 ABI “Clean Window” Infrared (10.3 µm) Imagery, 4 October 2017 at 2300 UTC through 1130 UTC on 5 October 2017 (Click to animate)

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

The Tropical Depression (#16) in the western Caribbean Sea has strengthened to become a minimal Tropical Storm, acquiring the name Nate. The animation from GOES-16, above, shows disorganized convection over the entire basin, stretching into the Pacific Ocean south of central America. (The sheared remains of Pacific Tropical Storm Ramon are also present south of Mexico). The animation below, from 0000-1300 UTC on 5 October 2017, shows the mid-level Water Vapor Infrared Imagery (6.95 µm) from GOES-16. Convection develops over the center of Nate, over Nicaragua, at the end of the animation.

GOES-16 ABI “Mid-Level Water Vapor” Infrared (6.95 µm) Imagery, 0000-1300 UTC on 5 October 2017 (Click to animate)

Microwave Imagery, below, from SSMI/S at around 1000 UTC on 5 October, (from this site) suggests that Nate is centered very near the coast of Nicaragua. Nate is forecast to move north into the Gulf of Mexico; its path through the northwest Caribbean suggests strengthening is possible if Nate remains far enough from land. Very warm water is present in the northwest Caribbean; that warmth extends to great depth as shown by this plot of Oceanic Heat Content; that warmth extends into the central Gulf of Mexico.

85 GHz Brightness Temperatures, 1000 UTC on 5 October 2017 (Click to enlarge)

Nate formed at a time when the Moon was Full. Thus, Suomi NPP Day Night Band Visible Imagery showed excellent illumination. The image below is from 0627 UTC on 5 October.

Suomi NPP Day Night Band Visible (0.7 µm) Imagery, 0627 UTC on 5 October 2017 (Click to enlarge)

Total Precipitable Water in advance of Nate is plentiful, as shown in the loop below (from this site). There is dry air over the continental United States, however, associated with a strong High Pressure System. Easterly winds south of that system are apparent in Scatterometer winds from early in the morning on 5 October.

MIMIC Morphed Total Precipitable Water, 1200 UTC 4 October – 1100 UTC 5 October 2017 (Click to enlarge)