A series of back-building thunderstorms produced very heavy rainfall and flash flooding (Public Information Statement | Local Storm Reports | CoCoRaHS) over the northern and eastern portion of Kauai on 14-15 April 2018. GOES-15 (GOES-West) Water Vapor (6.5 µm) and Infrared Window (10.7 µm) images (above) showed these deep convective storms, which exhibited cloud-top infrared brightness temperatures in the -60 to -70 ºC range (red to black enhancement). December 2018 Update: a new US record for 24-hour precipitation (49.69 inches) was confirmed by the National Climate Extremes Committee.

Even though the JMA Himawari-8 AHI instrument provides more frequent Water Vapor and Infrared Window images (every 10 minutes, compared to every 15-30 minutes with GOES-15) at a higher spatial resolution (2-km at satellite sub-point, vs 4-km with GOES-15),  Hawai’i is located near the limb of the Himawari-8 view — so parallax was playing a major role in the apparent location of the important convective features. Note how the primary thunderstorms were displayed to the east of Kauai on the Himawari-8 images, in contrast to directly over the island on GOES-15 images.

The MIMIC Total Precipitable Water product (above) showed that high amounts of tropical moisture were drawn northward across Hawai’i by the circulation of an upper-level trough — depicted by mid/upper-level atmospheric motion vectors — that was situated west/northwest of the islands (below).

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1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the development and rapid spread of grass fires in northwest Oklahoma on 12 April 2018. Hot fire pixels are highlighted as red on the Shortwave Infrared images — and the rapid northeastward run of the larger fires was very evident. The intense heat of the fires produced pyrocumulus clouds, which could be seen on the Visible images. Additional images are available on the Satellite Liaison Blog.

SPC had highlighted parts of New Mexico, Colorado, Texas and Oklahoma as having conditions favorable for Extreme wildfire behavior due to strong winds, hot temperatures and very dry air behind a dryline boundary (below). Note that the surface temperature / dew point depression at Woodward, Oklahoma (KWWR) at 2255 UTC on 12 April was 100 ºF (temperature = 97 ºF, dew point = -2 ºF), with southwesterly winds gusting to 35 knots or 40 mph.

===== 13 April Update =====

The fires in northwestern Oklahoma continued to burn into the following night — Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.9 µm) images at 0837 UTC or 3:37 AM local time (above) revealed the bright glow and hot fire pixels associated with the 2 large fire complexes in Woodward County (34 Complex Fire) and Dewey County (Rhea Fire). At least 2 fatalities (Wildfire Today | media report) have been attributed to the larger and longer-burning Rhea Fire in Dewey County (which had burned an estimated 241,280 acres by mid-day on 14 April).

During the following daytime hours of 13 April, GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (below) showed the smoke plumes and hot pixels of the northwestern Oklahoma fires. The surface cold front moved over these fires around 18 UTC, with smoke transport transitioning more toward the east then southeast.

Farther to the southwest, new grass fires which began burning west of the Texas/Oklahoma border after 17 UTC quickly raced eastward and crossed the border into southwestern Oklahoma after 20 UTC (below).

===== 14 April Update =====

Three nighttime comparisons of (Preliminary, non-operational) NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images — each image pair separated by 50 minutes — (below; courtesy of William Straka, CIMSS) showed the bright glow and thermal hot spots of the ongoing Rhea fire complex.

===== 15 April Update =====

250-meter resolution Terra MODIS true-color and false-color Red-Green-Blue (RGB) images from MODIS Today (below) showed the burn scars from the 34 Complex and the larger Rhea Fire at 1719 UTC on 15 April 2018.

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1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the southward propagation of a pre-cold-frontal trough axis (surface analyses) which appeared to play a role in enhancing ongoing convection — some thunderstorms then produced weak tornadoes, damaging winds and hail over parts of South Florida during the afternoon hours on 10 April 2018 (KMFL PNS). SPC storm reports are plotted on the GOES-16 images.

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 1934 UTC tornado is shown below, at two-minute intervals from 1926-1946 UTC. ProbWind for this storm jumped as the tornado began, and the storm had the highest ProbWind values of those on the map.

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 2025 UTC tornado is shown below, at two-minute intervals from 2012-2034 UTC. ProbTor increased from 1% to 10% between 2020 UTC and 2028 UTC with this storm.  ProbWind exceeded 90%.

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Upper-level Water Vapor (6.2 µm) infrared imagery on 9 April 2018 (above) revealed gravity waves propagating away from an isolated thunderstorm in the Gulf of Mexico.

The convective complex generated gravity waves that were visible in all 3 GOES-16 ABI Water Vapor Channels (6.19 µm, 6.95 µm and 7.34 µm).  The image below (produced using SIFT, the Satellite Information Familiarization Tool and data from NOAA CLASS) shows all three channels at 1812 UTC;  the color enhancement used is the same in each image, but the ranges were modified to make the gravity waves most visible.  Ranges used were -109 to 34 º C (Band 8); -109 to 55 º C (Band 9) and -80 to 42 º C (Band 10).

Weighting functions for the three water vapor infrared channels for three stations surrounding the Gulf of Mexico (Slidell, LA; Tallahassee FL; Tampa FL) suggest the gravity waves were in the 300-450 mb layer (6.2 µm) to the 450-600 mb layer (7.3 µm).

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