Heavy rainfall and flooding associated with Tropical Cyclone Seroja

April 4th, 2021 |

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

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]

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]

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)

Flooding in Tennessee

March 28th, 2021 |

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

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]

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]

 


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)

Satellite-based detection of rain amounts

March 10th, 2021 |

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.

10-day rocking animation, 0000 UTC 28 February 2021 to 2300 UTC 10 March 2021 (and back) (Click to enlarge)

Heavy rainfall in Hawai’i

March 8th, 2021 |

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) revealed 2 bursts of back-building thunderstorms that produced heavy rainfall (as much as 19.21 inches) and flooding along the northern coast of the Hawaiian island of Maui on 08 March 2021. This heavy rain caused rockslides that closed some roads, and prompted evacuations of a few communities downstream of the Kaupakulua Dam (which began to experience over-topping).

The coldest 10.35 µm infrared brightness temperatures were around -48ºC — for example, at 0000 UTC on 09 March (below).

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 0000 UTC on 09 March [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 0000 UTC on 09 March [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

In closer views of GOES-17 Visible and Infrared images (above), USGS river and rain gauge locations are plotted in large yellow text — the abrupt rise in flow of the Honopau Stream near Huelo (HPOH1) and the rapid accumulation of 17 inches of rainfall at the Wailuaiki rain gauge near Keanae (WWKH1) are shown below.

Hydrograph for the Honopau Stream near Huelo [click to enlarge]

Hydrograph for the Honopau Stream near Huelo [click to enlarge]

Graph of West Wailuaiki rain gauge accumulation [click to enlarge]

Graph of West Wailuaiki rain gauge accumulation [click to enlarge]

GOES-17 Water Vapor images, with plots of mid-upper level Derived Motion Winds [click to enlarge]

GOES-17 Water Vapor images, with plots of mid-upper level Derived Motion Winds [click to enlarge]

GOES-17 Water Vapor images with plots of mid-upper level Derived Motion Winds (above) showed the circulation of an upper level low west of the Hawaiian Islands — and with an increase in southwesterly upper-tropospheric wind speeds (as shown in Lihue rawinsonde data). the corresponding upper-level divergence (below) was seen to increase across the island chain by 00 UTC on 09 March (providing a more favorable environment for the development of deep convection).

GOES-17 Water Vapor images, with contours of upper level divergence [click to enlarge]

GOES-17 Water Vapor images, with contours of upper level divergence [click to enlarge]

The MIMIC Total Precipitable Water product spanning the 2 day period leading up to the heavy rainfall (below) showed an axis of higher tropical moisture — with TPW values of 1.50 to 1.75 inches — moving westward across Hawai’i.

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

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

The TPW value calculated from Hilo, Hawai’i rawinsonde data increased from 37.8 mm to 42.3 mm (1.49 inches to 1.67 inches) during the day as the lobe of enhanced moisture began to move westward over the Big Island (below).

Plots of rawinsonde data from Hilo, Hawai'i [click to enlarge]

Plots of rawinsonde data from Hilo, Hawai’i [click to enlarge]