AwesomeWow! A 600-mile long 'Roll Cloud'. That's amazing.! I would have been freaked out too.
Apocalyptic 'roll cloud' spanning hundreds of miles sparks mass panic on beach
“We believe the magnitude of the cloud on this occasion was about 1,000 km (621miles) in length and around 2km (1.24miles) wide,”
[Rio de Janeiro's Sao Conrado beach in Brazil]
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Things start to get more interesting on Tuesday as a stronger shortwave
begins to affect the area. Precipitable water values are expected
to rise to around 2 inches by the end of the day. Shear and
instability will increase through the day as well. The 00z NAM
suggests that there could be a non-zero risk of a severe storm or
two, although the other guidance is less aggressive with both
shear and instability. After some discussion with the Storm
Prediction Center, confidence is not yet high enough to include a
marginal risk on the day 3 outlook in our forecast area given the
model differences, although trends will continued to be monitored
in case that is warranted later. Broad timing on the greatest
coverage of activity currently appears to be from Tuesday
afternoon through Wednesday morning.
Still lots of ways to go with this one. May have some entrainment of a tropical system from the Pacific which may mess up lapse rates and thus instability.Interesting setup appears to be taking shape around the Oct 20-22nd timeframe, particularly on the GFS. This looks like something to keep an eye on and monitor trends. Not a ton of model agreement but it looks like a strong trough, 40-50 knot winds 925-700mb and 50-70+ knot 500mb winds. They appear fairly parallel at this time, wouldn't be surprised to see decent lightning rich QLCS scenario unfold.