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]

Geostationary satellite views of the most rain over 72-hours in 2007

February 27th, 2021 |

The record for the most rain over a 72-hour period was in late February 2007, with 3.930m (154.72″)! This was on Reunion Island, associated with Tropical Cyclone Gamede in South Indian Ocean. The island is east of Madagascar. This island also holds the record for the most rain (4,869 mm (191.7 in)) over a 96-hour period, associated with the same event. More on this case can be found in this 2009 BAMS article.

Meteosat-8

While the view of the cyclone from EUMETSAT‘s MET-8 was on the edge of the viewing area, the infrared window loop was still impressive.

A 3-day color-enhanced infrared window loop from EUMETSAT’s Meteosat-8 geostationary imager.

A longer loops of 3 and 4 days were also generated. Which shows Tropical Cyclone Favio as well. For these images, the coldest brightness temperatures have the green/yellow/red/pink colors. A one-day loop (February 25, 2007) in both mp4 and animated gif formats.

Meteosat-7

EUMETSAT’s Meteosat-7, due to its location over the Indian Ocean, had a more direct view of these cyclones.

A 3-day color-enhanced infrared window loop from EUMETSAT’s Meteosat-7 geostationary imager.

Note that the view angle is improved over Meteosat-8, but the image frequency is reduced. A longer Meteosat-7 loop was also generated. Again, Tropical Cyclone Favio can be seen.

A loop of Meteosat-7 visible band from February 25, 2007.

Visible loops (mp4 format) from February 23 and 24 and 26, 2007. The same loops as animated gifs: February 23, 24, 25 and 26, 2007.

H/T

Thanks to @Weather_History for the post on this event.

The above satellite data are from EUMETSAT, accessed via the University of Wisconsin-Madison Space Science and Engineering Center (SSEC) Data Services. The images were generated with McIDAS-X. More on EUMETSAT’s Meteosat Third Generation will appear in the Bulletin of the AMS.

Using 1-minute GOES-17 imagery to monitor tropical convection near American Samoa

February 21st, 2021 |

GOES-17 Infrared images [click to play animation | MP4]

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

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Clean” Infrared Window (10.35 µm) images (above) showed thunderstorms associated with the South Pacific Convergence Zone (SPCZ) on 21 February 2021. The 3 METAR stations plotted on the imagery are, from left to right, Hihifo Airport, Wallis and Fotuna (NLWW), Apia, Samoa (NSFA) and Pago Pago, American Samoa (NSTU).

In spite of their degraded quality due to GOES-17 ABI Loop Heat Pipe thermal issues (which reaches one of its peaks at the end February), the Infrared images were still helpful in confirming that the primary SPCZ axis was remaining just north of the Samoan islands — and since the NWS Pago Pago office lacks radar coverage, they highlighted the importance of satellite imagery in one of their forecast discussions:

The active South Pacific Convergence zone (SPCZ) is lingering over the Samoan 
island chain, as seen on latest GOES-17 mesoscale this afternoon.
We have a very difficult time with confirming the wind forecast by model data, 
as there are no observations available of the persistent convection brewing 
just off-shore the islands. However, the models coupled with satellite are 
our only tools.

===== 22 February Update =====

GOES-17

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

The Fiji Meteorological Service determined that Tropical Depression 10F formed along the SPCZ  around 00 UTC on 22 February (surface analysis). Shortly after that time, a convective burst developed just east of the disturbance center, which exhibited cloud-top infrared brightness temperatures as cold as -94.3ºC — which indicated a significant overshoot of the Equilibrium Level as analyzed on 00 UTC rawinsonde data from Pago Pago, American Samoa.

GOES-17 Infrared images, with plots of upper-level satellite winds and contours of upper-level convergence [click to enlarge]

GOES-17 Infrared images, with plots of upper-level satellite winds and contours of upper-level convergence [click to enlarge]

GOES-17 Infrared images with plots of upper-level satellite winds and contours of upper-level convergence (above) and plots of low-level satellite winds and contours of low-level convergence (below) from the CIMSS Tropical Cyclones site showed that the deep convection developing within the SPCZ was sustained by an environment of favorable kinematic fields. Tropical Depression 10F was also located within a narrow ribbon of relatively low deep-layer wind shear.

GOES-17 Infrared images, with plots of low-level satellite winds and contours of low-level convergence [click to enlarge]

GOES-17 Infrared images, with plots of low-level satellite winds and contours of low-level convergence [click to enlarge]

The MIMIC TPW product (below) highlighted the rich tropical moisture within the NW-SE oriented SPCZ.

MIMIC TPW product [click to enlarge]

MIMIC TPW product [click to enlarge]

A closer look at the MIMC TPW product over the Samoan islands at 16 UTC on 22 February is shown below. With such high tropical moisture in place across the region, thunderstorms were producing heavy rainfall and/or wind damage in some of the islands (local storm reports).

MIMC TPW product over the Samoan islands at 16 UTC

MIMC TPW product over the Samoan islands at 16 UTC [click to enlarge]

===== 23 February Update =====

GOES-17 "Red" Visible (0.64 µm) images [click to play animation | MP4]

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

GOES-17 “Red” Visible (0.64 µm) images (above) showed that as deep convection began to diminish, the low-level circulation center of TD 10F slowly became more exposed as the tropical disturbance weakened — prompting the Fiji Meteorological Service to discontinue classifying feature as a tropical depression as of 2100 UTC on 23 February (below).

Surface analyses at 18 UTC and 21 UTC on 23 February (map time stamps are Fiji local time) [click to enlarge]

Surface analyses at 1800 UTC and 2100 UTC on 23 February (map time stamps are Fiji local time) [click to enlarge]

Heavy rainfall and snowfall in Southern California

January 23rd, 2021 |

GOES-17 Air Mass RGB images, with contours of PV1.5 pressure [click to play animation | MP4]

GOES-17 Air Mass RGB images, with contours of PV1.5 pressure [click to play animation | MP4]

As an anomalously-deep 500 hPa low began to move inland over Southern California during the 23 January24 January 2021 period, GOES-17 (GOES-West)  Air Mass RGB images (above) showed a compact Potential Vorticity (PV) anomaly approaching the coast — and the RAP40 model indicated that the “dynamic tropopause” (defined here as the pressure of the PV1.5 surface) was descending to the 675 hPa pressure level at 18 UTC.

A west-to-east oriented cross section of RAP40 model fields along Line A-A’ (below) depicted the descending dynamic tropopause at 19 UTC.

Cross section of RAP40 model fields along line A-A' [click to enlarge]

Cross section of RAP40 model fields along line A-A’ [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) images (below) showed the increasing reports of rain and snow that resulted as the PV Anomaly moved inland and provided additional forcing for ascent. Near the coast, thunderstorms were reported at Fulton and Long Beach around 03 UTC. Storm total precipitation amounts included rainfall of 1.40 inch and snowfall of 12-18 inches.

GOES-17 Mid-level Water Vapor (6.9 µm) images, with plots of hourly surface weather type [click to play animation | MP4]

GOES-17 Mid-level Water Vapor (6.9 µm) images, with plots of hourly surface weather type [click to play animation | MP4]

GOES-17 Water Vapor images at 2301 UTC and 0246 UTC (below) revealed sporadic lightning activity (indicated by small clusters of GLM Groups).

GOES-17 Mid-level Water Vapor (6.9 µm) image at 2301 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 2301 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 0246 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 0246 UTC, with GLM Groups plotted in red [click to enlarge]

===== 24 January Update =====

GOES-17 Day Snow-Fog RGB images [click t play animation | MP4]

GOES-17 Day Snow-Fog RGB images [click to play animation | MP4]

On the following day, as clouds began to clear the areal extent of resulting fresh snow cover (darker shades of red) was seen in GOES-17 Day Snow-Fog RGB images (above). Even parts of the high desert — north and east of the mountain ranges — received some snowfall (for example, 2-3 inches were reported at Hesperia).

Suomi NPP VIIRS True Color RGB and False Color RGB images (below) showed the snow cover (shades of cyan) at 2036 UTC.

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]