Persistent convection in an atmosphere rich in moisture has led to life-threatening flooding over many Parishes in southern Louisiana. The animation above, taken from images at this site that morphs MIRS estimates of Total Precipitable Water (with values valid over both land and water) shows values around three inches over much of southeastern Louisiana. These TPW values agree with in situ observations such as the radiosonde from New Orleans at 1200 UTC on 12 August, where 2.70″ was observed. 24-hour rainfall totals ending at 1200 UTC on 12 August (Link) show a widespread region of more than 6″; raingauge observations of 6-hour totals at 1200 and 1800 UTC, below, show that the rain continued into the day on 12 August.

The flood-producing thunderstorms were very slow-moving, as evidenced in the animation of Infrared Window (10.7 µm) images from GOES-14, below (GOES-14 is in SRSO-R mode this month). Very little motion occurs in the two hours of this loop (using images at 5-minute time steps).

The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images from 0001-2358 UTC on 12 August is shown below.

This event is also discussed at the Satellite Liaison Blog, where the focus is on 1-minute visible imagery from GOES-14 and 1-minute lightning data.

===== 13 August Update =====

The heavy rainfall continued into 13 August, with storm total accumulations exceeding 31 inches in Louisiana (WPC storm summary). The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images spanning the period 1115 UTC on 11 August to 2159 UTC on 13 August, above, shows the development of multiple clusters of slow-moving thunderstorms, some of which exhibited cloud-top IR brightness temperatures of -80ºC or colder (violet color enhancement).

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JetBlue Flight 429 encountered severe turbulence over south-central South Dakota around 0115 UTC on 12 August (7:15 pm local time on 11 August) 2016, which caused injuries to 22 passengers and 2 crew members (media story). The aircraft (flying from Boston MA to Sacramento CA) had to be diverted to Rapid City SD, as seen on the flight path map above (source: FlightAware.com).

1-km resolution GOES-13 Visible (0.63 µm) images (above) showed widespread thunderstorms across the region, with rapidly-developing new cells forming in the vicinity of the turbulence encounter. A Turbulence AIRMET had been issued around 23 UTC for that portion of the flight path, and Convective SIGMETs also advised of the potential for severe thunderstorms with tops above 45,000 feet (JetBlue 429 was cruising at an altitude of 32,000 feet).

The corresponding 4-km resolution GOES-13 Infrared Window (10.7 µm) images (below) indicated that cloud-top IR brightness temperatures were as cold as -54º C (orange color enhancement) just east of the pilot report at 0100 UTC.

1-km resolution POES AVHRR Visible (0.86 µm) and Infrared (12.0 µm) images at 0049 UTC (below) provided a more detailed view of the developing cells less than 30 minutes prior to the turbulence encounter.

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GOES-13 (GOES-East) Water Vapor (6.5 µm) images (above) showed the intensification of a strong cyclone over Hudson Bay, Canada during the 09 August – 10 August 2016 period; the cyclone deepened to a central pressure of 980 hPa (28.94″ of mercury) at 06 UTC on 10 August.

Daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images visualized using RealEarth (below) showed the storm on 08, 09 and 10 August.

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1-minute SRSO-R GOES-14 Visible (0.63 µm) images (above; also available as a 265 Mbyte animated GIF) showed the development of severe thunderstorms which produced large hail and damaging winds (SPC storm reports) in southeastern North Dakota, northeastern South Dakota and far western Minnesota on 10 August 2016. SPC noted a region of enhanced instability centered over southeastern North Dakota around 16 UTC (MCD); it is interesting to note that an orphan anvil was seen to form around 13 UTC between Valley City (KBAC) and Gwinner (KGWR) — near the northern edge of the pocket of instability — before the main convection began to develop just north of the North Dakota/South Dakota border around 1515 UTC.

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