Heavy rain / flooding « CIMSS Satellite Blog

Severe weather across much of the Southeast US

May 4th, 2021 | Scott Bachmeier

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) include time-matched plots of SPC Storm Reports (predominantly widespread damaging winds, with some large hail and a few tornadoes) produced by a large and long-lived Mesoscale Convective System (MCS) that moved eastward across much of Mississippi and Alabama on 04 May 2021. The strong winds — with some gusts in excess of 70 mph — caused power outages which affected several hundred thousand residents (and persisted into the next day: MS | AL).

The corresponding 1-minute GOES-16 “Clean” Infrared Window (10.35 µm) images (below) showed numerous overshooting tops that exhibited infrared brightness temperatures in the -75 to -70ºC range (white pixels embedded within black areas). The MCS also produced heavy rainfall and flooding in parts of northern Alabama.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

? It rained a little yesterday…

Rainfall totals of 5-7″ (locally higher) fell across parts of the Birmingham metro & much of Shelby Counties. This lead to significant flooding in many areas. Thankfully, there were no fatalities. #alwx pic.twitter.com/ko0TmYhNUo

— NWS Birmingham (@NWSBirmingham) May 5, 2021

Larger-scale views of 5-minute CONUS Sector GOES-16 Visible and Infrared images are shown below. Several additional MCSs produced a variety of severe weather across other parts of the Southeast US.

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

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

Posted in GOES-16, Heavy rain / flooding, Severe convection | No Comments »

Heavy rainfall and flooding associated with Tropical Cyclone Seroja

April 4th, 2021 | Scott Bachmeier

MIMIC Total Precipitable Water product [click to play animation | MP4]

The incipient circulation of Cyclone Seroja moved very slowly across the island of Timor in Indonesia during the 03 April – 04 April 2021 period — and the MIMIC Total Precipitable Water product (above) depicted very high values over that area (just northwest of Australia).

At Kupang’s El Tari Airport, precipitation amounts included 547 mm (21.5 inches) during the 48 hours ending at 00 UTC on 05 April — with the heaviest amounts of 106 mm (4.2 inches) in 6 hours and 80 mm (3.1 inches) in 3 hours occurring during the 00-06 UTC period on 04 April when the pressure was falling as Cyclone Seroja began to slowly organize and intensify (below). Flash flooding affected much of the island, with multiple deaths being reported.

Time series plot of surface observations at El Tari Airport, Kupang [click to enlarge]

Time series plot of surface observations at El Tari Airport, Kupang, Indonesia [click to enlarge]

JMA 2.5-minute interval rapid scan Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) revealed a few convective bursts — with cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker shades of purple) — in the vicinity of Kupang (station identifier WATT) between 04 UTC on 04 April and 00 UTC on 05 April.

JMA Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

A NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC visualized using RealEarth (below) showed one lone -90ºC pixel within a convective burst centered just north of Kupang.

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC on 04 April [click to enlarge]

CMORPH estimates of 7-day precipitation (available in RealEarth) over the region show 300-400 mm over West Timor, and values exceeding 700 mm (!!) over the adjacent ocean.

7-day CMORPH accumulation of precipitation ending 0000 UTC 5 April 2021 (Click to enlarge)

Posted in Heavy rain / flooding, Himawari-8, Microwave, NOAA-20, RealEarth, Tropical cyclones, VIIRS | No Comments »

Flooding in Tennessee

March 28th, 2021 | Scott Bachmeier

GOES-16 “Clean” Infrared Window (10.35 µm) images, with hourly Precipitation Type plotted in cyan [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images centered on Nashville (above) displayed multiple clusters of thunderstorms that moved across Tennessee during the 27 March – 28 March 2021. The coldest overshooting top infrared brightness temperatures were in the -70 to -79C range. Precipitation ended and clouds cleared as a cold front moved eastward across the state on 28 March.

Hourly images of the MIMIC TPW product (below) showed the northward surge of moisture from the Gulf of Mexico beginning early on 27 March, providing an environment conducive to heavy rainfall.

MIMIC TPW product [click to play animation | MP4]

Plots of rawinsonde data from 00 UTC and 12 UTC on 27 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 27 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 27 March (above) and 28 March (below) illustrated the rapid increase in moisture on 27 March, followed by the gradual decease in the wake of the cold frontal passage.

Plots of rawinsonde data from 00 UTC and 12 UTC on 28 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 28 March [click to enlarge]

Here are some of our highest rainfall reports from Saturday morning through this morning and a map of combined radar estimates and observed precip. https://t.co/H9DHgOxCZW pic.twitter.com/Hk8qMxcRc3

— NWS Nashville (@NWSNashville) March 28, 2021

Nashville has measured another 0.94″ of rain since midnight. This gives us a 2-day rainfall total of 6.69″. This surpasses the 6.68″ measured on September 13-14, 1979, and gives us our 2nd largest 2-day rainfall total in Nashville’s history, trailing only May 1-2, 2010 (13.57″).

— NWS Nashville (@NWSNashville) March 28, 2021

CMORPH estimates of accumulated precipitation (available in RealEarth) are shown below, with 24-hour totals ending 23:59 on 27 March (left) and 28 March (right). The darker purple region denotes totals of >100 mm in 24 hours.

24-hour precipitation totals ending 23:59 on 27 March (left) and at 23:59 28 March (right) 2021 (Click to enlarge)

Posted in GOES-16, Heavy rain / flooding, Microwave | No Comments »

Satellite-based detection of rain amounts

March 10th, 2021 | Scott Lindstrom

Hydroestimator rainfall values for the 24 hours ending 1200 UTC on 9 March 2021 (Click to enlarge)

The system that produced the high-impact flooding event on Maui (discussed here) also caused flooding rains on Oahu on the 9th. (A Flash Flood Emergency was declared at 348 HST on 9 March: Link) How well did quantitative satellite estimates of this event perform? Hydroestimator values, above, from the 24 hours ending 1200 UTC on 9 March (from this website) show isolated maxima over northern Oahu for and over eastern Maui. Daily totals for the 24 hours ending 1200 UTC on 10 March are shown below. Again, heavy rain is diagnosed on Maui with lesser amounts over Oahu, where 48-hour totals were between 150 and 200 mm.

Hydroestimator rainfall values for the 24 hours ending 1200 UTC on 10 March 2021 (Click to enlarge)

GSMAP rain totals for the 24 hours ending 0000 UTC on 10 March 2021 (click to enlarge)

24-hour totals from JAXA’s GsMAP website, above, show large values mostly north of Oahu, and also just north of Maui. Values are between 100-150 mm. 24-hour CMORPH-2 values (from RealEarth), below, ending 0000 UTC on 10 March, show values between 50 and 100 mm. Values over Maui are less than 50 mm.

CMORPH-2 24-h precipitation ending 0000 UTC on 10 March 2021 (Click to enlarge)

The GOES-17 Enterprise algorithm totals, below (courtesy Bob Kuligowski, NOAA) , show values close to 50 mm over Oahu, and over 50 mm on Maui.

24-hour rain totals from the GOES-17 algorithm, 1200 UTC on 10 March 2021 (Click to enlarge)

None of these rain totals captured the exceptional nature (writeup is here; some totals are here) of this orographically enhanced rainfall. The widespread nature of the rain was captured however. All methods detected heaviest rain north of the Island chain.

GOES-17 animations, both visible and infrared, combined with situational awareness driven by animations of total precipitable water, such as that below (from this site) will help a forecaster anticipate heavy rains however — when they might start, and when they might end.