Hurricane Epsilon

October 21st, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

Hurricane Epsilon underwent rapid intensification (ADT | SATCON) on 21 October 2020 — and 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed Epsilon as it intensified from a  Category 1 to a Category 3 storm.

GOES-16 Mid-level Water Vapor (6.9 µm) images with plots of Derived Motion Winds from CIMSS Tropical Cyclones site (below) displayed the broad upper-level anticyclonic outflow north of the hurricane.

GOES-16 Mid-level Water Vapor(6.9 µm) images, with plots of Derived Motion Winds [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with plots of Derived Motion Winds [click to enlarge]

Blowing dust from the Copper River Delta in south-central Alaska

October 20th, 2020 |

GOES-17

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

Strong gap winds accelerating out of the Copper River Valley along the southern coast of Alaska were lofting fine particles of glacial silt/sand and transporting those aerosols southward across the Gulf of Alaska on 20 October 2020. 1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Dust Red-Green-Blue (RGB) images (above) displayed the plume of airborne dust during the period of 1700-2300 UTC.

A good visualization of the dust plume was provided by GOES-17 True Color RGB images created using Geo2Grid (below).

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

A comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2040 UTC is shown below — note that the dust plume appeared warmer (darker shades of gray) on the Shortwave Infrared image, since the small dust particles were efficient reflectors of incoming solar radiation.

Suomi NPP VIIRS Visible, Shortwave Infrared and Infrared Window images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Thundersnow in South Dakota and Minnesota

October 20th, 2020 |

GOES-16 Day Cloud Phase Distinction RGB images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 (GOES-East) Day Cloud Phase Distinction Red-Green-Blue (RGB) images with a overlay of GLM Flash Extent Density (above) displayed clusters of convection — some with brief bursts of lightning activity — which were moving eastward and enhancing snowfall rates from Watertown, South Dakota (station identifier KATY) into far western Minnesota on 20 October 2020. The resulting snowfall amounts included 6.0 inches near Watertown and 8.0 inches near Ortonville, Minnesota.

Tropical Storm Epsilon in the Atlantic

October 19th, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed Tropical Depression 27 as further intensified to become Tropical Storm Epsilon at 15 UTC on 19 October 2020. While the low-level circulation (LLC) generally remained exposed during that time, deep convection was increasing around the LLC (including a small convective burst near the storm center forming around 1630 UTC).

GOES-16 Visible image with plots of available NUCAPS profiles [click to enlarge]

GOES-16 Visible image with plots of available NUCAPS profiles [click to enlarge]

A GOES-16 Visible image with plots of available NOAA-20 NUCAPS profiles (above) showed one valid infrared (CrIS) + microwave (ATMS) sounding (green dot) just southeast of the center of Epsilon at 1640 UTC — that sounding profile (below) revealed a moist (PW = 1.95″) and unstable (MU CAPE = 1066 J/kg, and LI = -3) atmosphere just after the time of development of the convective burst near Epsilon’s center.

NUCAPS profile just southeast of the center of Tropical Storm Epsilon [click to enlarge]

NUCAPS profile just southeast of the center of Tropical Storm Epsilon [click to enlarge]

GOES-16 Visible images with overlays of deep-layer wind shear and GLM Flashes from the CIMSS Tropical Cyclones site (below) indicated that Epsilon was in an environment of moderate shear, with limited lighting activity near the storm center.

GOES-16 “Red” Visible (0.64 µm) images, with overlays of deep-layer wind shear and GLM Flashes [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) images, with overlays of deep-layer wind shear and GLM Flashes [click to enlarge]

A toggle between the MIMIC Total Precipitable Water and Saharan Air Layer products (below) showed that Epsilon was embedded within a pocket of abundant moisture, with dry air situated to the north and northwest.

MIMIC Total Precipitable Water and Saharan Air Layer product [click to enlarge]

MIMIC Total Precipitable Water and Saharan Air Layer product [click to enlarge]

Tropical Storm Epsilon was located over water having Sea Surface Temperature values around 28ºC and a modest Ocean Heat Content (below).

Sea Surface Temperature and Ocean Heat Content [click to enlarge]

Sea Surface Temperature and Ocean Heat Content [click to enlarge]