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.

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.

 

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

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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.

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).

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.

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).

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.

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).