Atmospheric Bore structure over Wisconsin

September 20th, 2022 |
GOES-16 Visible imagery (0.64 ), 1056 – 1911 UTC on 20 September 2022

GOES-16 Visible Imagery, in the mp4 animation above (click here for an animated gif), shows convection initially over central Wisconsin at sunrise moving eastward over Lake Michigan into lower Michigan. In its wake, cloud lines extending east-west move southward into southward Wisconsin. Parallel lines such as these are typically associated with atmospheric bores, previously discussed many times on this blog (link). A bore is usually associated with stable air; note how the convective line over southwestern WI at around 1500 UTC dissipates after 1600 UTC as it encounters the stable air associated with the bore.

LightningCast Probabilities are consistent with the southern convective line encountering air that is more stable, as shown above in an animation that pauses at 1506 UTC; lightning probabilities decrease with the southern line as they increase with the northern line that eventually sweeps southward through southern Wisconsin, producing hail.

GOES-16 Visible imagery overlain with ProbSevere LightningCast probabilities and GLM Flash Extent Density, 1331 -1801 UTC on 20 September 2022 (Click to enlarge)

NOAA-20 overflew this region shortly after 1900 UTC on 20 September. The gridded 850-700 mb lapse rate, below, from this site, shows a region of more stable air over/around Chicago and southern Lake Michigan that is perhaps residual stability related to the bore feature.

Diagnosed 850-700 mb stability from NOAA-20 NUCAPS profiles, ca. 1915 UTC on 20 September 2022 (click to enlarge)

Shout-out to Rebecca, a forecaster at WFO GRB, for also noticing these lines!

The thunderstorms were followed by mammatus clouds over Madison, as shown in the image below, courtesy Bill Bellon, UW-Madison SSEC/CIMSS.

Mammatus clouds over Madison WI, 19 September 2022 (Click t0 enlarge). Photo Credit: Bill Bellon

TL;DR: Departing convection put down stable layer defined by atmospheric bore. Convection encountering this stable layer dissipated. Stronger convection moved in later, depositing hail.

ProbSevere LightningCast Probabilities for Guam

September 15th, 2022 |
RealEarth display of Himawari-8 Band 13 (10.4 µm) infrared imagery and LightningCast Probability contours, 1320 – 1420 UTC on 15 September 2022 (Click to enlarge)

At the request of the National Weather Service forecast office in Guam (where the National Weather Service’s day begins), CIMSS is computing a small region of LightningCast Probabilities that uses Himawari-8 data. The Guam forecast office issues a lightning ‘advisory’ if lightning is possible or occurring within 20 mi of the Guam Airport, and a lightning ‘warning’ if lightning is possible/occurring within 5 mi of the airport. LightningCast probabilities will help in this task. Forecasters will be evaluating its performance in the coming weeks.

LightningCast imagery is available in a RealEarth instance here (at that website, there is a small drop-down menu titled ‘Select Sector’; Choose Guam). An example animation is shown above. (Guam is located at the outer fringes of Typhoon Nanmadol in the image) In contrast to the scenes under GOES-East’s and GOES-West’s view, GLM data are not available. In the forecast office, ground-based lightning sources are available. This animation (from John Cintineo, CIMSS) shows LightningCast probabilities with Earth Networks Total Lightning. Animations online, as shown above, show only Himawari-8 data and LightningCast probability contours.

As with GOES-R LightningCast computations, Himawari-8 uses Visible (0.64 µm), near-infrared (1.61 µm) and infrared (10.41 µm and 12.3 µm) observations. Resolution differences at 1.61 µm (1 km for GOES-R and 2 km for Himawari-8) and slight differences in infrared spectral responses, especially for band 13 (centered near 10.33 µm for GOES-R and 10.41 µm for Himawari-8) may have an as-yet unknown impact on LightningCast probabilities.

LightningCast and Cape Canaveral

August 29th, 2022 |

NASA was supposed to launch its Artemis rocket to the moon this morning, at 8:33 AM EDT (12:33 UTC) from Cape Canaveral, FL. However, an engine problem caused NASA to scrub the launch for today. Even if all technical aspects of the launch were “go”, developing convection near Cape Canaveral might have posed a problem for the rocket launch.

ProbSevere LightningCast, an AI model developed by CIMSS and NOAA, uses GOES-R ABI images to predict lightning in the next 60 minutes. It was predicting elevated probabilities of lightning near Kennedy Space Center prior to the start of the launch window, reaching nearly 60% by 12:31 UTC. Lightning was eventually observed by the Geostationary Lightning Mapper by 13:11 UTC.

Figure 1: GOES-East Day-Land-Cloud-Convection RGB, LightingCast contours, and GLM flash-extent density (blue boxes). The red circles represent 5-mile and 10-mile range rings around Kennedy Space Center.
Figure 2: A time series of the LightningCast probability of lighting and GLM-observed lighting near Kennedy Space Center, in Cape Canaveral, FL.

Tools like LightningCast can help convert the rich information from GOES-R ABI into actionable information, helping decision-makers protect life and property. In this case, LightingCast could hypothetically be used to help protect billions of dollars of equipment, as well as the lives of NASA personnel preparing the launch pad. While this is a hypothetical case, experimental LightningCast output has been used routinely by the National Weather Service to provide guidance on lighting initiation and to inform their impacts-based decision support to key events and partners.

ProbSevere and LightningCast over La Crosse, Wisconsin

June 15th, 2022 |

ProbSevere is a weather product that uses GOES-16 data to help predict the probability of any severe weather (hail, wind, or tornados) happening in the next 60 minutes. ProbSevere LightningCast predicts the probability that a GLM Lightning observation will occur in the next 60 minutes. Below are examples of these products over the Western Wisconsin area as a convective system rolls through La Crosse, Wisconsin.

The ProbSevere probability product imaged as contours, overlayed with GOES-16 Day Cloud Convection RGB for 06-15-2022 from 20:00 to 20:22Z near La Crosse, Wisconsin [Click to enlarge].
The LightningCast probability product imaged as contours of 75, 50, 25, and 10 percent, overlayed with GOES-16 Day Cloud Convection RGB for 06-15-2022 from 20:00 to 20:22Z near La Crosse, Wisconsin [Click to enlarge].