Severe thunderstorms in South Florida

April 10th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red and airport identifiers plotted in yellow [click to play MP4 animation]

1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the southward propagation of a pre-cold-frontal trough axis (surface analyses) which appeared to play a role in enhancing ongoing convection — some thunderstorms then produced weak tornadoes, damaging winds and hail over parts of South Florida during the afternoon hours on 10 April 2018 (KMFL PNS). SPC storm reports are plotted on the GOES-16 images.

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 1934 UTC tornado is shown below, at two-minute intervals from 1926-1946 UTC. ProbWind for this storm jumped as the tornado began, and the storm had the highest ProbWind values of those on the map.

NOAA/CIMSS ProbSevere All Hazards read-out from 1926-1946 UTC on 10 April 2018 (Click to enlarge)

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 2025 UTC tornado is shown below, at two-minute intervals from 2012-2034 UTC. ProbTor increased from 1% to 10% between 2020 UTC and 2028 UTC with this storm.  ProbWind exceeded 90%.

NOAA/CIMSS ProbSevere All Hazards read-out from 2012-2034 UTC on 10 April 2018 (Click to enlarge)

Severe weather across parts of the Mid-South, Ohio Valley and mid Mississippi Valley

April 3rd, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

An outbreak of severe weather occurred across parts of the Mid-South, Ohio Valley and mid Mississippi Valley on 03 April 2018. A GOES-16 Mesoscale Sector provided images at 1-minute intervals — “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) include plots of SPC storm reports.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

Looking farther to the southwest over parts of Texas, Louisiana and Arkansas, similar animations of 1-minute GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images are shown below.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

NOAA/CIMSS ProbSevere All Hazards (Prob Hail, Prob Wind, Prob Tor) use during this event is discussed here.

Unusual October Tornado in Wisconsin

October 7th, 2017 |

GOES-16 ABI Visible (0.64 µm) Imagery, 2042-2227 UTC on 7 October 2017 (Click to animate)

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

October is typically not a month when tornadoes are expected in Wisconsin. (And in fact, the month ranks fourth in the numbers of fewest tornadoes nationwide). Nevertheless, a brief tornado occurred on the east side of Madison WI late in the afternoon on 7 October (NWS Milwaukee/Sullivan). The visible animation, above, from GOES-16, shows a thin line of weak convection moving through the central part of the state. A slower animation centered on the reported time of the tornado (2200 UTC), is below. The dynamic state of the thunderstorm tops is apparent, and the 5-minute time-step may not be sufficient to resolve the small time-scale changes in the tornadic storm (the two GOES-16 Mesoscale sectors that provide 1-minute imagery were covering the pending landfall of Hurricane Nate at this time, and were giving severe weather support to Puerto Rico, radar-less in the wake of Hurricane Maria).

GOES-16 ABI Visible (0.64 µm) Imagery, 2152-2222 UTC on 7 October 2017 (Click to enlarge)

The Clean Window Channel, below, with the default AWIPS enhancement, shows little cloud-top structure.

GOES-16 ABI Infrared (10.3 µm) Imagery, 1917-2302 UTC on 7 October 2017, default enhancement (Click to animate)

Coldest cloud-top brightness temperatures with this event were in the -15º to -20º C range, and the default enhancement (with a range from -109º to 55º) showed little gradation in that range. By changing the coldest temperature in the enhancement from -109º C to -43º C, however, a structure in the cold clouds emerged, as shown below. Do not be afraid to change enhancements!

GOES-16 ABI Infrared (10.3 µm) Imagery, 1917-2302 UTC on 7 October 2017, adjusted enhancement (Click to animate)

The NOAA/CIMSS ProbSevere products for this event is shown below (from this site). ProbTor values were negligible; however, ProbWind values for the tornadic cell were around 20-24% leading up to the event. In addition, the cell that produced the tornado had the highest probabilities in the identified cells along the line of convection. The single exception occurred at 2235 UTC, after the severe weather event, when the cell to the north briefly (for only five minutes) showed Probabilities exceeding 40%.

NOAA/CIMSS ProbTor, 2130-2235 UTC on 7 October 2017 (Click to enlarge)


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The National Weather Service in Milwaukee/Sullivan WI determined that the tornado was an EF-0 based on a damage assessment. They provided radar imagery at the start of the tornado, during the tornado, at its end, and after dissipation.

NOAA/CIMSS ProbTor with a Severe Thunderstorm over Florida

April 6th, 2017 |

GOES-16 “Red” Band (0.64 µm) from 1222 through 1517 UTC on 6 April 2017 (Click to animate)

GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.

GOES-16 Visible Imagery early on 6 April 2017 showed a strong thunderstorm developing north of Lake Okeechobee and proceeding east towards the Atlantic Coast near Vero Beach (1-minute or 30-second imagery was not available over Florida because the GOES-16 Mesoscale Sectors were in their default locations; routine 5-minute CONUS imagery is shown above).

Clean Infrared  Window channel (10.33 µm) imagery from 1400-1500 UTC, taken from AWIPS, below, shows a well-developed albeit weakening storm that is moving off the coast. A pronounced Overshooting Top/Thermal Couplet is present at 1402 UTC; the brightness temperature of the overshoot is -77º C, and the downwind warm trench is -62º C.

GOES-16 Clean Infrared Window Band (10.3 µm) from 1402 through 1457 UTC on 6 April 2017 (Click to animate)

The NOAA/CIMSS ProbTor product was monitoring this storm as it moved eastward through central Florida. The animation below shows the cell strengthening rapidly after 1310 UTC, and maintaining large ProbTor values for about an hour, after which time values collapsed.

NOAA/CIMSS ProbTor product from 1256 through 1444 UTC on 6 April 2017 (Click to animate)

The time series below shows ProbTor as a function of time (1232-1444 UTC). The different parameters that are used in the computation of ProbTor are plotted as well. The times of the Severe Weather Warnings issued by the National Weather Service are drawn along the horizontal axis. The three wind events noted as vertical magenta lines (wind events taken from the Storm Prediction Center Storm Reports) occur within the envelope of highest ProbTor probabilities.

Plot of NOAA/CIMSS ProbTor values from 1232 through 1444 UTC on 6 April 2017. Vertical magenta lines are wind damage reports from SPC (Click to animate)

Note: NOAA/CIMSS ProbSevere Products — ProbHail, ProbWind, ProbTornado and the 2016 version of ProbSevere are all run using legacy GOES data (GOES-13 and GOES-15). GOES-16 data can be incorporated into this tool only after the statistical model has been trained on GOES-16 data, and that has not yet happened; A GOES-16 version is planned for the 2018 convective season.

With 16 Channels, the ABI on GOES-16 allows many different views of the same event. The animation below includes the 1/2-km resolution 0.64 µm “Red” Visible channel, the Snow/Ice channel (1.61 µm, 1-km resolution) that distinguished between clouds made of water droplets and clouds made of ice because ice strongly absorbs radiation at 1.61 µm and hence reflectances are smaller and the cloud appears less white, the Cirrus channel (1.378 µm, 2-km resolution) that highlights high clouds because radiation at the wavelength is very strongly absorbed by water vapor so reflectance from low-level clouds cannot escape to space before it is absorbed, and the Clean Infrared Window channel (10.33 µm, 2-km resolution) that affords a view that is least affected by water vapor absoption. In the animation below, the coastline does not become visible in the Cirrus channel because of strong absorption of radiation at that wavelength by water vapor. The Cirrus clouds in the 1.61 µm channel are considerably darker because of absorption by ice of radiation at that wavelength; a few water-based clouds do appear in the scene and are bright: 1.61 µm radiation is reflected quite well by water droplets.

GOES-16 “Red” Visible Band (0.64 µm), Snow/Ice Band (1.61 µm), Cirrus Band (1.378 µm) and Clean Infrared Window (10.33 µm) from 1222 through 1517 UTC on 6 April 2017 (Click to animate)

The GOES-R website has Quick Guide information on the Red Visible Band (0.64 µm), the Snow/Ice Band (1.61 µm), the Cirrus Band (1.378 µm) and the Clean Infrared Window Band  (10.33 µm) at this site.