Lake effect snow in Nevada

February 21st, 2019 |


GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) showed a lake effect snow feature downwind of Pyramid Lake in northwestern Nevada on 21 February 2019 — the surface visibility dropped to 0.5 mile with moderate snow as ihe lake effect cloud moved over Reno-Tahoe International Airport around 16 UTC.

A morning overpass of the NOAA-19 satellite provided a 1-km resolution Infrared Window (10.8 µm) image of the lake effect cloud at 1254 UTC (below). The coldest cloud-top infrared brightness temperature on that images was -46ºC.

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

GOES-17 cloud-top infrared brightness temperatures associated with this feature were as cold as -47ºC just after 15 UTC, which were very close to the tropopause temperature of -47.9ºC on 12 UTC rawinsonde data from Reno (below).

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Although clouds often prevented a good view of Lake Pyramid, Terra MODIS Sea Surface Temperature values of 42º and 43ºF were sampled on 11 and 16 February (below). With a northerly flow of air having temperatures around 20ºF across such warm water, significant boundary layer instability was generated to aid the growth of the lake effect cloud feature.

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Although the view angle from GOES-16 (GOES-East) was rather large, a Land Surface Temperature pixel mapped to the northern portion of the lake had a value of 39.3ºF at 1701 UTC (below).

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

Typhoon Wutip in the West Pacific Ocean

February 21st, 2019 |

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1502 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1502 UTC [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 at 1502 UTC (above) and from Suomi NPP at 1552 UTC (below) showed Category 2 Typhoon Wutip in the West Pacific Ocean (southeast of Guam) on 21 February 2019. With Moon in the Waning Gibbous phase (at 95% of Full), ample illumination was provided to highlight the “visible image at night” capability of the Day/Night Band.

Notable features included deep convection near the storm’s center of circulation (with the presence of subtle cloud-top gravity waves), and transverse banding along the eastern periphery of the cold central dense overcast. Bright pixels seen in the Suomi NPP Day/Night Band image were the result of clouds being illuminated by lightning activity. VIIRS images courtesy of William Straka, CIMSS.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1552 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1552 UTC [click to enlarge]

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

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Typhoon Wutip intensified to a Category 3 storm on 22 February — JMA Himawari-8 Infrared Window (10.4 µm) images (above) revealed cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels surrounded by darker purple) shortly after 00 UTC.

A DMSP-17 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) showed a nearly complete ring of strong convection around the eye region at 0916 UTC.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

Wutip had been moving over water with warm Sea Surface Temperature and high Ocean Heat Content values (below).

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

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

Testing of GOES-16 and GOES-17 Mode 6 scan strategy

February 19th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation]

Both GOES-16 (GOES-East) and GOES-17 (GOES-West) were placed into the Mode 6 scan strategy for a 3-day period of testing beginning at 1500 UTC on 19  February 2019 — which provides Full Disk images every 10 minutes (instead of every 15 minutes for the more common Mode 3 scan strategy). Further details on GOES-R series scan modes are available here and here. GOES-16 Full Disk “Red” Visible (0.64 µm) images are shown above, with Mid-level Water Vapor (6.9 µm) images below.

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation]

One of the more striking features over the North Atlantic Ocean was a rapidly-intensifying Hurricane Force low — an animation that cycles through GOES-16 Visible and Water Vapor images of this system is displayed below.

GOES-16 "Red" Visible (0.64 µm) and Mid-level Water Vapor (6.9 µm) images [click to play animation]

GOES-16 “Red” Visible (0.64 µm) and Mid-level Water Vapor (6.9 µm) images [click to play animation]

GOES-16 Air Mass RGB images from the AOS site (below) exhibited the orange-to-red hues of ozone-rich air within the atmospheric column due to a lowered tropopause associated with the rapidly deepening North Atlantic storm.

GOES-16 Air Mass RGB images [click to play animation | MP4]

GOES-16 Air Mass RGB images [click to play animation | MP4]

Looking to the west with GOES-17, Full Disk animations of Visible and Water Vapor images are shown below.

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

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

GOES-17 Mid-level Water Vapor (6.9 µm) images [click to play animation]

GOES-17 Mid-level Water Vapor (6.9 µm) images [click to play animation]

The more frequent 10-minute images allowed a short-lived signature of orographic waves within a transient dry slot immediately downwind (northeast) of Atka (PAAK) in the Aleutian Islands of Alaska  (below) — such a signature often indicates a high potential of turbulence. There were also areas of transverse banding seen with the jet stream cirrus just southeast of Atka (another satellite signature of turbulence).

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

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

Similar to what was seen over the North Atlantic, GOES-17 Air Mass RGB images (below) exhibited the orange-to-red hues of ozone-rich air within the atmospheric column due to a lowered tropopause poleward of the jet stream axis as it moved northeastward across the Aleutians.

GOES-17 Air Mass RGB images [click to play animation | MP4]

GOES-17 Air Mass RGB images [click to play animation | MP4]

Strong jet streak over the Lower 48 states

February 17th, 2019 |


GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

An unusually strong jet streak was located over the Lower 48 states on 17 February 2019. GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images with plots of 6.2 µm Derived Motion Winds (above) showed numerous tracked targets along and south of the jet axis — within the jet streak exit region over the Mid-Atlantic states, some velocity values were as high as 181 knots (below).

GOES-16 Upper-level Water Vapor (6.2 µm) image, with plots of Derived Motion Winds at 0002 UTC [click to enlarge]

GOES-16 Upper-level Water Vapor (6.2 µm) image, with plots of Derived Motion Winds at 0002 UTC [click to enlarge]

A plot of rawinsonde data from Lincoln, Illinois at 00 UTC (below) showed wind speeds as high as 190 knots at a pressure of 231 hPa. The 250 hPa wind speed of 184.7 knots set both a daily and an all-time record speed for that pressure level (the old all-time record was 175 knots for a sounding on 10 Dec at 00 UTC).

Plot of 00 UTC rawinsonde data from Lincoln, Illinois [click to enlarge]

Plot of 00 UTC rawinsonde data from Lincoln, Illinois [click to enlarge]

GOES-16 Air Mass RGB images from the AOS site (below) provided a classic portrayal of the green hues of warm/moist tropical air south of and the orange/red hues of cold/dry polar air north of this strong jet stream.

GOES-16 Air Mass RGB images [click to play animation | MP4]

GOES-16 Air Mass RGB images [click to play animation | MP4]

===== 18 February Update =====

GOES-17 "Red" Visible (0.64 µm) and Near-Infrared "Snow/Ice (1.61 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice (1.61 µm) images [click to play animation | MP4]

The large southward dip of the polar jet stream — evident in the GOES-16 Air Mass RGB images from the previous day — brought cold air into the Desert Southwest, resulting in snowfall at lower-elevation locations such as Las Vegas, Nevada. GOES-17 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice (1.61 µm) images (above) revealed snow on the ground in the Las Vegas area — much of which quickly melted with increased surface heating after sunrise. Snow cover is a good absorber of radiation at the 1.61 µm wavelength, so it appeared as darker shades of gray on the Snow/Ice images; the distribution of the heavier snowfall amounts (which naturally melted more slowly) was influenced by the topography of the area. This snowfall forced the closure of Interstate 15 from Las Vegas to the Nevada/California border for several hours due to icy pavement and multiple traffic accidents.

The snow cover was apparent in Visible imagery from 4 GOES (below) — GOES-17 (GOES-West), GOES-15 (the backup GOES-West), GOES-16 (GOES-East) and GOES-13 (the backup GOES-East, which had been brought out of storage for annual maintenance activities).

Visible images from GOES-17, GOES-15, GOES-15 and GOES-13 [click to play animation | MP4]

Visible images from GOES-17, GOES-15, GOES-15 and GOES-13 [click to play animation | MP4]