Lake effect clouds downwind of Fort Peck Lake, Montana

January 11th, 2019 |
GOES-17 (left) and GOES-16 (right)

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

A comparison of GOES-17 (soon to become GOES-West) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) revealed a plume of lake effect clouds streaming south of Fort Peck Lake in northeastern Montana on 11 January 2019. As a cold front moved south-southwestward across the region (surface analyses), surface winds shifted to northerly at Glasgow KGGW which brought a flow of colder air across the still-unfrozen lake. Note that before sunrise the initial formation of the lake effect clouds could be seen on Shortwave Infrared imagery — and after sunrise, the feature appeared progressively warmer (shades of orange) on 3.9 µm images as the supercooled water droplets at the cloud top reflected increasing amounts of incoming solar radiation.

An Aqua MODIS Sea Surface Temperature product at 1942 UTC (below) showed that mid-lake water temperatures south of Glasgow were as warm as 36ºF (lighter shades of blue) — significantly warmer than Glasgow’s early morning surface air temperatures that were as cold as 17ºF at 14 UTC.

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

A comparison of the Sea Surface Temperature product with the corresponding Aqua MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.9 µm) and Infrared Window (11.0 µm) images at 1942 UTC (below) showed the lake effect cloud plume as well as a patch of snow cover northeast of the lake — snow absorbs radiation at the 1.61 µm wavelength, making it appear dark on the “Snow/Ice” image.

Aqua MODIS Visible (0.65 µm), Near-Infrared

Aqua MODIS Sea Surface Temperature, Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.9 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra and Aqua MODIS True Color and False Color Red-Green-Blue (RGB) images viewed using RealEarth (below) showed that parts of the Missouri River upstream (to the west of) of Fort Peck Lake — in the area of the UL Bend National Wildlife Refuge — were beginning to freeze (ice and snow appear as shades of cyan on the False Color RGB images).

Terra and Aqua MODIS True Color and False Color RGB images [click to enlarge]

Terra and Aqua MODIS True Color and False Color RGB images [click to enlarge]

Hurricane Force low in the West Pacific

January 10th, 2019 |
GOES-17

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

* GOES-17 images shown here are preliminary and non-operational *

GOES-17 “Red” Visible (0.64 µm) images (above) revealed the low-level circulation of an occluded Hurricane Force low (surface analyses) over the West Pacific Ocean on 09 January – 10 January 2019. This storm was forecast to produce wave heights up to 40-60 feet.

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below) showed the circulation of the storm at higher altitudes.

GOES-17 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

GOES-17 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

Metop-A ASCAT surface scatterometer wind speeds were as high as 67 knots southwest of the storm center and 63 knots to the northeast (below).

GOES-17 Mid-level Water Vapor (6.9 µm) image with Metop-A ASCAT surface scatterometer winds [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image with Metop-A ASCAT surface scatterometer winds [click to enlarge]

A toggle between VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 — as viewed using RealEarth — is shown below.

NOAA-20 VIIRS True Color and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color and Infrared Window (11.45 µm) images [click to enlarge]

Hurricane Force low in the East Pacific Ocean

January 7th, 2019 |
GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

* GOES-17 images shown here are preliminary and non-operational *

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed the intensification of a Hurricane Force low over the East Pacific Ocean on 07 January 2019 (surface analyses).

A comparison of NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 2150 UTC as viewed using RealEarth is shown below.

NOAA-20 True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 2150 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 2150 UTC [click to enlarge]

First -50ºF of the season in Alaska

January 6th, 2019 |
Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

* GOES-17 images shown here are preliminary and non-operational *

The first official temperature of -50ºF or colder during Alaska’s 2018/2019 winter season was reported by the cooperative observer at Chicken on 06 January — the 24-hour high temperature at that site was -45ºF, with a low of -51ºF (NWS Fairbanks summary). A sequence of Suomi NPP VIIRS Infrared Window (11.45 µm) images (above) showed infrared brightness temperatures as cold as -46.5ªC or -51.7ºF (lighter green enhancement) in the river valleys between Tok and Eagle (Chicken is located about midway between those 2 cities).

A toggle between Infrared Window images from Suomi NPP VIIRS and GOES-17 (below) highlighted the advantage of polar-orbiting imagery at high latitudes — improved spatial resolution and a better viewing angle provides more detailed images. However, it should be noted that the Full Disk GOES-17 imagery that is displayed here using AWIPS is degraded from 2-km to 4-km resolution (at satellite sub-point).

Infrared Window images from Suomi NPP VIIRS (11.45 µm) and GOES-17 (10.3 µm) [click to enlarge]

Infrared Window images from Suomi NPP VIIRS (11.45 µm) and GOES-17 (10.3 µm) [click to enlarge]

A sequence of NOAA-20 VIIRS Infrared images displayed using RealEarth is shown below. The majority of the scene was cloud-free — except for some cyan-enhanced stratiform clouds moving eastward across parts of the Alaska Range — and although there was some slight diurnal warming seen in the higher terrain, little change was apparent with the signature of colder air (shades of green) that was trapped in the lower elevations and river valleys.

NOAA-20 VIIRS Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) images [click to enlarge]

Plots of Fairbanks rawinsonde data from 00 UTC on 06 and 07 January (below) displayed the strong low-level temperature inversion caused by the relatively shallow arctic air.

Plots of Fairbanks rawinsonde data from 00 UTC on 06 and 07 January [click to enlarge]

Plots of Fairbanks rawinsonde data from 00 UTC on 06 and 07 January [click to enlarge]

===== 07 January Update =====

Infrared Window images from GOES-17 ABI (10.33 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Infrared Window images from GOES-17 ABI (10.33 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Minimum temperatures of -50ºF and colder were again reported on 07 January, with lows of -56ºF at Chicken and -50ºF at North Pole (NWS Fairbanks summary). 1-minute imagery from a GOES-17 Mesoscale Domain Sector allowed for a more direct full-resolution comparison with Suomi NPP VIIRS imagery — and a toggle between 1926 UTC images (above) revealed significantly greater detail in terms of the cold air confined to river valleys on the VIIRS image. The enhancements used in this comparison have identical temperature ranges for each of the color segments (there are some color vs. temperature offsets with the GOES/VIIRS infrared comparison shown on the previous day). The coldest infrared brightness temperature values on the VIIRS image were -46.4ºC in the vicinity of Tok, Alaska and -49.4ºC across the Canadian border in Yukon — compared to -44.6ºC and -45.1ºC for those two locations on the GOES-17 image.