The NOAA/CIMSS ProbSevere portfolio contains AI models for nowcasting convective weather. I’ll use Monday’s severe weather over the Southern Plains to highlight several of them.

A strong cold front spawned numerous severe-hail, wind, and tornado producing storms over Texas and Oklahoma, aided by very large values of convective available potential energy (CAPE; > 4000 J/kg).  You can see numerous storm reports in Figure 1.

Probsevere version 2 (PSv2) is an operational set of models at NOAA, which predict the probability of severe hail, severe wind, and tornadoes, in the next 60 minutes. The models are storm-centric, and the models’ domain is the entire contiguous United States (CONUS).  These models use MRMS (radar), GOES (satellite), short-term NWP, and terrestrial-based lightning observations to generate probabilistic guidance of severe hazards. Figure 2 shows output from an experimental version (PSv3), which includes additional MRMS, GOES, and NWP fields as predictors in a machine learning model.

 

Another ProbSevere product is a convolutional neural network that uses GOES-R ABI and GLM images to detect regions of intense convection, and is often correlated with strong overshooting tops, “bubbly-like” texture in visible imagery, strong lightning cores, and the cold-U/above-anvil cirrus plume signature. The intense convection probability (ICP) can be run on the 1-minute mesoscale scans as well as 5-minute CONUS sector scans aboard the GOES satellites. The ICP does not require radar data, and may also be able to operate on data from satellites with similar intruments (e.g., Meteosat Third Generation). ICP output is being used as a predictor in the experimental ProbSevere v3.

 

Predicting when and where lightning will occur is also important for many users, such as mariners, aviators, and outdoor event managers. The probability of lightning model (PLTG) is also a convolutional neural network, using images of visible, near-infrared, and longwave-infrared channels to nowcast lightning occurrence in the next 60 minutes. The purple-to-orange shaded regions in the video below show GLM flash-extent density (i.e., flashes passing through a location).

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), CIMSS Natural Color RGB and Dust RGB images (above) showed a pulse of blowing dust moving southward within the outflow of a severe thunderstorm in southeastern Colorado on 02 May 2021. The storm produced a tornado, large hail and wind gusts as high as 93 mph at Lamar (KLAA) at 2309 UTC (SPC Storm Reports). The blowing dust eventually reduced surface visibility to 1 mile at Johnson City as it moved across far western Kansas.

1-minute GOES-16 True Color RGB images created using Geo2Grid (below) highlighted the characteristic tan-colored hues of blowing dust along and behind the thunderstorm outflow boundary.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images and “Clean” Infrared Window (10.35 µm) images (above) include time-matched plots of SPC Storm Reports of large hail produced by supercell thunderstorms that developed and moved eastward across southern Texas on 28 April 2021. Hail as large as 4.00 inches in diameter was listed in the SPC Storm Reports, but one giant hailstone was found whose diameter was 6.4 inches (Update: this hail was confirmed to be a Texas state record):

The NWS and @disastersafety surveyed a giant hailstone that fell in Hondo, TX on April 28th, measuring 6.4″ in diameter! The measurement will be presented to a State Climate Extreme Committee, who will be tasked to verify and determine what, if any, records were broken. pic.twitter.com/MPujiIXJBv

— NWS Austin/San Antonio (@NWSSanAntonio) May 7, 2021

Vigorous overshooting tops were seen in both the Visible and Infrared GOES-16 images, with the coldest IR brightness temperatures in the -80 to -89ºC range (shades of violet to purple) — and along the southern flank of the storms, inflow feeder bands were evident the Visible imagery. 00 UTC rawinsonde data from Del Rio, Texas (below) showed that parcel temperatures of -80 to -89ºC would indicate significant vertical overshoots of both the equilibrium level (-67ºC) and the tropopause (-74.7ºC).

Farther to the north, 1-minute GOES-16 Infrared images (below) showed other thunderstorms that produced large hail (up to 3.25 inches in diameter) in the Dallas/Fort Worth area after sunset.

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There have been recent changes to web browsers with a result that ftp:// protocols are only rarely supported (and that can be with difficulty). Accordingly, ftp access to UW-Madison CIMSS Direct Broadcast imagery has been altered so that https:// protocols can be used. This can allow direct visualization of imagery through a web-browser, eliminating the need to download it first. To access NOAA-20 data, for example, start at https://ftp.ssec.wisc.edu/pub/eosdb/j01/ (similar urls access Suomi-NPP, Terra and Aqua imagery);  then select an instrument (VIIRS or ATMS, for example), a day/time, and the type of imagery. The imagery shown above came from much larger images at https://ftp.ssec.wisc.edu/pub/eosdb/j01/viirs/2021_04_27_117_1716/images/. It shows True Color imagery over the Gulf Stream just east of North Carolina’s Outer Banks, along with M12 (3.7 µm) and M13 (4.05 µm) imagery. There is both a color change and temperature change to the water as one travels across the North Wall of the Gulf Stream.

The CIMSS Direct Broadcast site is one of very few that allows access to imagery for all 22 VIIRS channels: 5 I-bands, 16 M-bands, and the Day Night band.

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