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Using the Night Microphysics RGB and LightningCast probabilities to anticipate nighttime convection and Lightning

The Nighttime Microphysics RGB, above, over central Wisconsin (that’s Green Bay at the northeastern edge, and southeast Minnesota/northeast Iowa over the southwestern part, of the animation), shows a field of low clouds stretching west-southwest to east-northeast. Note however, the occasional appearance of redder pixels within the field (as shown in... Read More

Nighttime MIcrophysics RGB, 0616 – 0811 UTC on 11 May 2022 (click to enlarge)

The Nighttime Microphysics RGB, above, over central Wisconsin (that’s Green Bay at the northeastern edge, and southeast Minnesota/northeast Iowa over the southwestern part, of the animation), shows a field of low clouds stretching west-southwest to east-northeast. Note however, the occasional appearance of redder pixels within the field (as shown in this annotated image from 0806 UTC), especially in Wood and Portage counties (Click here for a map of Wisconsin counties). That kind of signal suggests that vertical cloud growth is occurring. Do you think convection will occur shortly? What about lightning?


NOAA-20 overflew this region shortly after 0730 UTC, and NUCAPS profiles would have become available in AWIPS at about the time of the end of the animation. What do they show? The image below shows 850-mb Temperature and the 850-500 mb lapse rates computed from gridded NUCAPS fields. The steepest lapse rates and strongest instability is centered on a NUCAPS profiles in central WI (in Adams County) which is just south of the band of clouds identifiable in the Night Microphysics RGB shown above: NUCAPS profiles show ample instability just south of this line (and winds are southerly: 0000 UTC Green Bay sounding).

850-mb Temperatures, 850-500 mb Lapse Rate, and Total Totals Index, 0730 UTC on 11 May 2022 (click to enlage)

The individual NUCAPS soundings in Adams County and Green Lake County, below, show very steep mid-level lapse rates.

NUCAPS Profiles in Adams County (left) and Green Lake County (right) at 0735 UTC on 11 May 2022 (Click to enlarge)

The GOES animation of Nighttime Microphysics above ended at 0811 UTC. What happened in the next 15 minutes? Note a continued development in the amount of reddish pixels! During these 15 minutes, radar is also showing increasing returns.

Nighttime Microphsyics RGB, 0811-0826 UTC on 11 May 2022 (Click to enlarge)

If convection is expected, lightning might also occur. Lightning Cast is a product in the NOAA/CIMSS ProbSevere portfolio, and it’s available online here, and a short training video is here. LightningCast probabilities for the same 15-minute span as above are shown below. Low probabilites are present until 0826 UTC. When do you think lightning might occur with this developing line?

LightningCast probabilities, 0811-0826 UTC on 11 May 2022 (click to enlarge)

The animation below follows the developing cells through the next 15 minutes — from 0826 to 0841 UTC. Nighttime Microphysics (overlain by radar: note the parallax shift, and also note the continued reddening of pixels in the RGB where convection is occurring) is on the left, and LightningCast Probabilities are on the right. Do you think lightning is imminent?

Nighttime Microphysics RGB overlain with 0.5 Base Reflectivity (left) and LIghtningCast Probability (right), 0826 – 0841 UTC (Click to enlarge)

The first GLM observations (with a CONUS time cadence of every 5 minutes) of lightning occurred at 0846 UTC, as shown in the animation of the Nighttime Microphysics RGB below. (Here is LightningCast at 0846 UTC).

Nighttime Microphysics RGB and GLM Flash Extent Density (FED), 0616 – 0851 UTC on 11 May 2022 (click to enlarge)

The animation below shows the NightMicrophysics RGB overlain with LightningCast Probabilities, from 0816 to 0846 UTC.

GOES-16 Nighttime Microphysics RGB with LightningCast Probabilities and GLM FED observations, 0816 – 0846 UTC on 11 May 2022 (click to enlarge)

Gridded NUCAPS fields for this blog post were created using the NOAA/TOWR-S Cloud Instance of AWIPS. Thank you! And here is a link to a presentation detailing how the Nighttime Microphysics RGB can be used in winter!

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Calf Canyon Fire produces a pyrocumulonimbus cloud

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature derived product images (above) showed that the northern portion of the Calf Canyon Fire/Hermits Peak Fire in New Mexico produced a pyrocumulonimbus (pyroCb) cloud on 10 May 2022. Extreme fire behavior was aided by surface wind gusts in the 42-64 mph... Read More

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Infrared Window (10.35 µm, bottom left) and Cloud Top Temperature derived product (bottom right) [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature derived product images (above) showed that the northern portion of the Calf Canyon Fire/Hermits Peak Fire in New Mexico produced a pyrocumulonimbus (pyroCb) cloud on 10 May 2022. Extreme fire behavior was aided by surface wind gusts in the 42-64 mph range and very dry air within the boundary layer (along with very dry fuels from the ongoing drought); these large fires also burned very hot, with 3.9 µm Shortwave Infrared brightness temperatures reaching 138.71ºC — the saturation temperature of ABI Band 7 detectors. Coldest 10.35 µm cloud-top brightness temperatures exhibited by the pyroCb cloud were around -45ºC (lighter blue enhancement), with the Cloud Top Temperature product showing values as cold as -54ºC (red pixels).

In a comparison of NOAA-20 VIIRS True Color RGB, False Color RGB and Infrared Window (11.45 µm) images valid at 2057 UTC (below), the coldest cloud-top infrared brightness temperature was -59ºC. These images were acquired and processed using the Direct Broadcast ground station at SSEC/CIMSS.

NOAA-20 VIIRS True Color RGB, False Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

During the preceding nighttime hours, a toggle between Suomi-NPP VIIRS Day/Night Band and Shortwave Infrared images valid at 0847 UTC or 2:47 am MDT (below) showed the bright emitted light and hot thermal signature of active fires along the periphery of the burn area — especially along the northern fire front, which eventually produced the pyroCb cloud.

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

An evolution of the recent New Mexico wildfires using a series of VIIRS Day/Night Band images is available at this blog post.

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Day Night Band Imagery of fires in New Mexico

The Day Night Band on the VIIRS sensor that flies on both Suomi NPP and NOAA-20 will view emitted light (or reflected moonlight) at night. The animation above (derived from imagery at the VIIRS Today website — from this sector, specifically) shows the light emissions from cities in New Mexico (click here to see the annotated first image... Read More

The Day Night Band on the VIIRS sensor that flies on both Suomi NPP and NOAA-20 will view emitted light (or reflected moonlight) at night. The animation above (derived from imagery at the VIIRS Today website — from this sector, specifically) shows the light emissions from cities in New Mexico (click here to see the annotated first image with place names), and, notably, fires. Multiple fires are apparent in the animation. For example: the Calf Canyon (start on 19 April)/Hermits Peak (start on 6 April) fire start in the center of the animation; to the northeast of that fire, the Cooks Peak fire that started on 17 April is mostly contained as of 10 May; the Cerro Pelado fire (start on 19 April) to the west of Santa Fe is also apparent.

Suomi NPP Day Night Band imagery on 10 May 2022. Note the 3 faint smoke plumes emitted from the Calf Canyon and Hermits Peak fires. The moon had set by the time Suomi NPP overflew New Mexico.

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Bolt out of the blue

Florida is one of the lightning capitals of the world, so residents need to be constantly aware of lightning safety. NOAA/CIMSS LightningCast might be able to help with that. A tree and home in Sebring, Florida were suddenly struck by lightning on the morning of Saturday, May 7th. A line of storms was... Read More

Florida is one of the lightning capitals of the world, so residents need to be constantly aware of lightning safety. NOAA/CIMSS LightningCast might be able to help with that.

A tree and home in Sebring, Florida were suddenly struck by lightning on the morning of Saturday, May 7th. A line of storms was edging its way eastward. A neighbor who was outside at the time said, “It wasn’t raining. It was nice and warm. It was cloudy, but that was it. And then boom!” This underscores how easy it is to be caught unaware of potential lightning danger.

LightningCast can help with users’ situational awareness. LightningCast is an experimental deep-learning model trained on thousands of GOES-R ABI and GLM images to predict the probability of next-hour lightning occurrence. In the animation below, the red dot is Sebring, Florida.

LightningCast probability contours, GOES-16 ABI imagery (grayscale background), and GOES-16 GLM flash-extent density (shaded color). The red dot is the approximate location of the “bolt out of the blue”.
Florida homeowner stunned by nearby lightning strike. Credit: FOX13 Tampa Bay

Below is a time series of LightningCast probability and GLM observations around the home in Sebring. Lightning struck the tree and home at 8:21 EDT, marked by the vertical black line below. You can see a rapid increase in probability of lightning from 11:26 to 11:36 UTC (7:26 to 7:36 EDT), reaching 70%. This was about 25 minutes before the first nearby lightning strike and 45 minutes before the Sebring home was struck.

The animation below from the National Weather Service lightning safety page shows that most lightning casualties occur before a thunderstorm is fully overhead, or before it fully departs the area, when people might not realize their vulnerability to lightning and don’t seek shelter soon enough or leave shelter too soon.

Animation depicting the threat of lightning casualties as a function of a hypothetical storm moving into the area.

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