Portland, Oregon heavy snow event

January 11th, 2017 |

GOES-15 Infrared Window (10.7 µm) images, with hourly reports of surface weather type [click to play animation]

GOES-15 Infrared Window (10.7 µm) images, with hourly reports of surface weather type [click to play animation]

A surface low moving inland (3-hourly surface analyses) helped to produce widespread rain and snow across much of Oregon and southern Washington during the 10 January11 January 2017 period. 4-km resolution GOES-15 (GOES-West) Infrared images (above) and Water Vapor images (below) showed the development of a deformation band that helped to focus and prolong moderate to heavy snowfall over the Portland, Oregon area (accumulations | historical perspective). The GOES-15 images are centered at Portland International Airport (station identifier KPDX).

GOES-15 Water Vapor (6.5 µm) images, with hourly reports of surface weather type [click to play animation]

GOES-15 Water Vapor (6.5 µm) images, with hourly reports of surface weather type [click to play animation]

1-km resolution GOES-15 Visible (0.63 µm) images (below) during the last few hours of daylight on 10 January revealed the shadowing and textured signature of numerous embedded convective elements moving inland, which were helping to enhance precipitation rates (and even produce thundersnow at a few locations, a phenomenon which is very unusual for the Pacific Northwest).

GOES-15 Visible (0.63 µm) images, with hourly reports of surface weather type [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly reports of surface weather type [click to play animation]

===== 12 January Update =====

As clouds cleared in the wake of the storm, a comparison of 375-meter resolution Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images viewed using RealEarth (below) revealed the extent of the snow cover; snow appears as shades of cyan in the false-color image, in contrast to clouds which appear as shades of white. [Note: with 5 inches of snow remaining on the ground, a new record low temperature was set in Portland on 13 January]

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

The fresh snowfall was also apparent in a 30-meter resolution Landsat-8 false-color RGB image (below) along the south face of Mount Hood (located about 98 miles or 158 km east of Portland). The ski slopes of Timberline Lodge and  Mount Hood Meadows received 13-14 inches of new snow during this event; the snow base depth at Timberline was greater than the average amount for this time of year.

Landsat-8 false-color RGB image [click to play zoom-in animation]

Landsat-8 false-color RGB image [click to play zoom-in animation]

Oil well fire in Utah

January 6th, 2017 |

GOES-15 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-15 (GOES-West) Visible (0.63 µm) images (above) showed a small, short-lived black cloud that formed south/southwest of Vernal (station identifier KVEL) in northeastern Utah on 06 January 2017. This feature was the result of a fire at an oil well site (media report | well location) that apparently started around 11:30 am local time (1830 UTC); the black cloud from the burning oil tanks — which was first apparent on the 1930 UTC visible image — stood out well against the snow-covered ground. The initial northwestward transport of the smoke plume was consistent with lower-tropospheric winds in Grand Junction, Colorado rawinsonde data at 07 January/00 UTC, which showed southeasterly winds as high as 784 hPa (2185 meters or 7169 feet above ground level). The sounding profile also showed that this height was the top of a well-defined temperature inversion, which acted as a cap to prevent the smoke from reaching higher altitudes (photo).

GOES-13 (GOES-East) Visible (0.63 µm) images (below) also displayed the dark smoke plume. The viewing angles from the 2 satellites were similar (~53 degrees from GOES-15 vs ~57 degrees from GOES-13), but the time sampling was slightly better from GOES-15 (due to the extra “SUB-CONUS” scan images at :11 and :41 minutes nearly every hour). Image frequency will be even better with the GOES-R series of satellites (beginning with GOES-16), with routine scans every 5 minutes; the visible image spatial resolution will also be improved (to 0.5 km, vs 1.0 km with the current GOES).

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

MODIS Visible (0.645 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images from a 2036 UTC overpass of the Aqua satellite (below) showed the black smoke cloud in the Visible, but there was no evidence of a fire “hot spot” in the Shortwave Infrared (the media report indicated that the fire was extinguished about 2 hours after it started, which would have been around or just before the time of the MODIS images). On the Infrared Window image, the smoke plume actually did exhibit a slightly colder (darker blue color enhancement) signature, which is unusual since conventional fire and wildfire smoke is normally transparent to thermal radiation.

Aqua MODIS Visible (0.645 µm) and Shortwave Infrared (3.7 µm) images at 2036 UTC [click to enlarge]

Aqua MODIS Visible (0.645 µm) and Shortwave Infrared (3.7 µm) images at 2036 UTC [click to enlarge]

A view of the 250-meter resolution Aqua MODIS true-color Red/Green/Blue (RGB) image from the MODIS Today site is shown below.

Aqua MODIS true-color image at 2036 UTC [click to enlarge]

Aqua MODIS true-color image at 2036 UTC [click to enlarge]