Forecasters at the National Weather Service (NWS) Storm Prediction Center (SPC) are evaluating a machine learning model that uses satellite imagery to predict the probability of observing lightning from the GLM within the next hour. The model is called ProbSevere LightningCast, and was developed by CIMMS at the University of Wisconsin-Madison. While ProbSevere LightningCast received overwhelmingly positive reviews when demonstrated in the 2022 and 2023 Hazardous Weather Testbed from NWS forecasters in local Weather Forecast Offices (WFOs), it has yet to be demonstrated for SPC forecasters. To learn more about the LightningCast model, one can review the training materials page or Cintineo et al. (2021) in AMS Weather and Forecasting.
On 22 November 2023, an upper level low was moving into the southern Appalachian Mountains, and began to interact with a cold front along the mid-Atlantic coast. While the severe potential was limited that day, the 13 Z (8am EST) convective outlook from the SPC highlighted a small area with marginal risk for severe weather with thunderstorms generally forecast along the central and southern Atlantic coasts.
As the cold front moved off the east coast during the day, so did the region of ascent and instability that drove the thunderstorms. When viewing the LightningCast, we can watch the probability contours move eastward into the Atlantic between 1630 and 1830 Z.
Does this mean the potential for thunderstorms is over for today? Not yet! If we look closely at central North Carolina and northern South Carolina, we can see some 10% (blue) probability contours showing up just before 18 Z…
This signal was picked up by one of the SPC forecasters, who remarked:
‘The was a good signal from LightningCast about 30 min before lighting occurred with low-topped showers beneath a secondary upper low with minimal buoyancy across parts of central NC and northern SC. The 20Z D1 update adjusted general thunder lines to account for expected evolution of this activity.’
– SPC Forecaster
As a result of the observed LightningCast probabilities and subsequent thunderstorms, the forecaster was able to provide a short-term guidance update to the general thunder lines within the SPC outlook as shown below.