Hurricane Matthew. . .a storm that will be remembered for the challenges, strange structures, maneuvering path, weird (sinister) face images in satellite imagery, and unusually low (observed) pressures regardless of satellite appearance.
As you can see in the GOES-13 infrared animation above, the structure of Matthew has gone through a few changes today with some northerly shear blunting the northern portion of the hurricane, although this hasn’t lead to any notable weakening as of yet. In the last couple of frames, very strong convection fires again as the hurricane is approaching Grand Bahama. Also of note is the strong area of convection that fired to the northeast of Matthew today, though not as strong as what was seen in the Caribbean over the weekend.
The GOES-13 infrared imagery with GLD-360 15-minute lightning density overlaid shows a couple distinct areas of lightning activity, the aforementioned convection to the northeast and another area in the northeast eyewall. This latter area has been pulsing all day and may suggest that the shear mentioned earlier was being fought off by the deep pulses of convection. Note that this area passed over the western portion of Providence Island and is getting ready to move ashore in southwest Grand Bahama. This is where the aircraft is showing the strongest winds (near 120 kts or 140 mph).
So, where did this shear originate from? I haven’t quite found the source, but I did pull up a NOAA Unique Combined Atmospheric Profiles (NUCAPS) sounding that may not be the most representative of the northern portion of the cyclone due to clouds, but does show an interesting drying at mid-levels. Note there are no winds as this is a satellite-borne sounding looking down, not to be confused with a raob.
Another product that has been available to forecasters at the National Hurricane Center, Weather Prediction Center, and NESDIS Satellite Analysis Branch is the GOES-R Rain Rate/QPE product provided by Bob Kuligowski at NESDIS. These are 15 minute rain rates that are derived using infrared brightness temperatures, then calibrated with microwave imagery. Note the values near the eyewall approaching 1″-1.50″ per 15 minutes!!!
The 7-day QPE accumulation image above shows many values over western Haiti and eastern Cuba approaching and exceeding 20″, which might even be conservative in the higher terrain areas. Note other interesting features like the rain shadow in northern Dominican Republic and amounts that exceed (then re-accumulate) 20″-45″ near where Matthew slowed north of Columbia. The now infamous “convective blob” is where the largest totals are located and might be reasonable for this case considering the extreme lightning and intensely cold cloud tops.
This final animation shows the very intense lightning activity associated with the inner core organization and infamous “convective blob” that was trailing Hurricane Matthew through the southern Caribbean. The persistent lightning in the northern eyewall is interesting in that it’s rather atypical for rapid intensification in Atlantic hurricanes. Meanwhile, the lightning associated with the blob is very intense at 15 minute increments and helps support those extreme rain amounts that fell over the Caribbean.
Thank you for reading and feel free to comment/ask questions!
Michael Folmer / Andrea Schumacher