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 an unusual 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. Prior to that, the lake effect snow also affected portions of Interstate 80 in the Patrick area.

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 image 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 (ADT | SATCON) — rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images at 2.5 minute intervals (above) revealed cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels surrounded by darker purple) shortly after 00 UTC. Multiple convective bursts developed around the center of circulation, and evidence of eye formation was seen for a short time beginning around 1137 UTC.

Himawari-8 “Red” Visible (0.64 µm) images of Wutip (below) showed that a distinct cloud-free eye did not form during that time period.

Himawari-8 "Red" Visible (0.64 µm) images [click to play MP4 animation]

Himawari-8 “Red” Visible (0.64 µm) images [click to play MP4 animation]

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. A 24-hour animation of MIMIC-TC morphed microwave imagery is available here.

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

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

Prior to becoming a typhoon, Wutip had been moving over water with warm Sea Surface Temperatures 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]

===== 23 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]

2.5-minute rapid scan Himawari-8 Infrared Window (10.4 µm) images (above) revealed the formation of a large and well-define eye with an annular eyewall structure as Wutip rapidly intensified (ADT | SATCON) to Category 4 Super Typhoon status on 23 February. Mesovortices could be seen rotating within the eye. Wutip became the most intense February typhoon on record in the Northwest Pacific basin.

In a toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1602 UTC (below), these mesovortices were also apparent — with the help of reflected moonlight — in the Day/Night Band.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1604 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1604 UTC [click to enlarge]

As noted in a 21 UTC discussion from the JTWC, Wutip had a well-defined poleward outflow channel within the upper troposphere (below), which was a favorable factor for its intensification.

Himawari-8 Water Vapor (6.9 µm) images with plots of middle/upper-tropospheric derived motion winds [click to enlarge]

Himawari-8 Water Vapor (6.9 µm) images with plots of middle/upper-tropospheric derived motion winds [click to enlarge]

Stereoscopic views of Tropical Pacific Convection (and Tropical Storm Wutip) during Mode 6 Testing for GOES-17

February 21st, 2019 |

GOES-17 Band 2 Visible (0.64 µm) Imagery (Left) and Himawari-8 Band 3 Visible (0.64 µm) from 2000 UTC on 20 February to 0450 UTC on 21 February 2019 (Click to play animated gif)

GOES-17 is typically operational using Mode 3 Scanning, in which mode Full Disk images are acquired every 15 minutes (in addition to a PACUS sector every 5 minutes and two mesoscale sectors every minute).  NOAA/NESDIS plans a transition to operational Mode 6 scanning at some point in Spring, and testing for that is ongoing.  In Mode 6, Full Disk images are acquired every 10 minutes (while maintaining the 5-minute PACUS imagery and two 1-minute Mesoscale sectors), a Full Disk sequencing that aligns with Himawari-8 Full Disk image acquisition.  This means that stereoscopic views using GOES-17 (overhead at 137.2º W) and Himawari-8 (overhead at 140.8º E) can be created with a 10-minute time step when GOES-17 is in Mode 6 (vs. every 30 minutes when GOES-17 is operating in Mode 3, as shown here).

The stereoscopic animation above shows tropical convection that was trailing western Pacific then-Tropical Storm Wutip (link 1link 2 on Typhoon Wutip);  The three-dimensions apparent in the stereoscopic imagery allow for easy identification of vertical shear — over the southwestern corner of the image, for example.

Tropical Storm Wutip was on the extreme limb of GOES-17’s field of view on 20-21 February; nevertheless, data could be used to view the storm, in stereo, with Himawari-8. That animation is shown below.  Wutip is on the western edge of the imagery.

GOES-17 Band 2 Visible (0.64 µm) Imagery (Left) and Himawari-8 Band 3 Visible (0.64 µm) from 1900 UTC on 20 February to 0450 UTC on 21 February 2019 (Click to play animated gif)

Himawari-8 imagery is courtesy the Japan Meteorological Agency, JMA.