Posted in: ABI
, Gulf of Mexico
, Hurricane Center
On the morning early of 04/06/17, TAFB forecasters noted a nice V-pattern to convection at the tail end of a front in the northeast Gulf of Mexico. The increased temporal and spatial resolution of GOES-16 compared to the GOES-13 (east) provided more details on the organization and maintenance of the convective line that would otherwise have been analyzed.
GOES-16 0.64 um “Red” visible animation showing strong convection in the eastern Gulf of Mexico, valid 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge
Hugh Cobb (TAFB Branch Chief) noted: “We also looked at the Red VIS Band 2 for this event. The VIS imagery was more striking in that you could see the shadows of the high cirrus cast on the lower cloud deck in the animation and the “beavertail” of of the low clouds feeding into and maintaining the deep convection.”
GOES-16 10.3 um “Clean” infrared animation (same as above), valid from 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge
GOES-16 10.3 “Clean” infrared imagery with 5-minute GLD-360 lightning density overlaid, valid 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge
Jorge Aguirre-Echevarria (TAFB Forecaster) noted that “the striking cloud/convective signature and associate lightning activity observed that day over the waters of the far southern Gulf of Mexico.” In particular, these events are rather rare at such a low latitude in the TAFB Offshore Zones. The GOES-16 10.3 μm infrared imagery proved to be very helpful in seeing the overshooting tops and the cold cloud canopy temperatures which signified the activity would persist west of Key West, FL.
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The Gulf of Mexico and Gulf Coast states have seen a plethora of thunderstorms since about mid-April. One of these episodes was a multi-day event that spanned April 16 – April 20. Multiple rounds of thunderstorms with very heavy rainfall (especially in and around Houston) and some significant severe weather (more hail and wind than tornadoes) traversed the region. The below animation shows these events and I included an example Mesoscale Precipitation Discussion (MPD) from WPC as a reference to the heavy rain.
GOES-13 Infrared imagery with GOES-R Lightning Detection (Density) spanning five days (04/16-4/20).
The Weather Prediction Center (WPC) Mesoscale Precipitation Discussion (MPD) for southeast Texas on 04/18/15.
More recently, on the evening of 04/22/15, a couple strong supercell thunderstorms moved off the Texas coast near the Corpus Christi area and traversed the offshore waters passing relatively close to a couple oil platforms. One of the more amazing attributes to the storms was the strong reflectivities of near 75 dbz! Although these were measured at high altitudes (based on the beam height), it’s interesting to note that large hail may have been occurring well offshore in the Tropical Analysis and Forecast Branch (TAFB) offshore zones. I have included a few animations showing the evolution of these supercells.
Animation of the GOES-R Convective Initiation product with GLD-360 lightning strokes overlaid valid 4/22-4/23.
National WSR-88D Mosaic base reflectivity with the Overshooting Top Magnitude (OTM) product overlaid highlighting the most intense updrafts associated with the supercells. The OTM product provides the difference between the overshoot and the surrounding cirrus clouds.
National WSR-88D Mosaic base reflectivity overlaid with the GOES-R Lightning Detection (Density) product in 5-minute increments. Note the extreme amount of lightning occurring with the dominant supercells in the Gulf of Mexico.
Here is a post from the National Weather Service Office in Houston-Galveston which nicely summarizes the threat posed to mariners from offshore supercells.
Thank you for reading!