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]

Heavy rainfall and high-elevation snowfall in Hawai’i

December 2nd, 2016

GOES-15 Water Vapor (6.5 µm) images, with overlays of GFS model 500 hPa geopotential height [click to play animation]

GOES-15 Water Vapor (6.5 µm) images, with overlays of GFS model 500 hPa geopotential height [click to play animation]

6-hour interval GOES-15 (GOES-West) Water Vapor (6.5 µm) images with overlays of GFS model 500 hPa geopotential height (above) showed middle to upper tropospheric moisture that was being drawn northwestward toward Hawai’i by the circulation of a closed low centered southwest of the state during the 01-02 December 2016 period.

A closer view using 15-minute interval GOES-15 Water Vapor images (below) showed 2 distinct pulses of moisture moving across the eastern portion of the island chain. Due to the prolonged flow of moisture and the variable terrain, Flood Warnings and Winter Storm Warnings were issued for the Big Island of Hawai’i (as shown using RealEarth).

GOES-15 Water Vapor (6.5 µm) images, with hourly surface reports [click to play MP4 animation]

GOES-15 Water Vapor (6.5 µm) images, with hourly surface reports [click to play MP4 animation]

Hourly images of the MIMIC Total Precipitable Water (TPW) product (below) showed the large plume of moisture, which had its roots within the Intertropical Convergence Zone (ITCZ). Maximum TPW values in the vicinity of Hawai’i were in the 50-55 mm (2.0-2.2 inch) range. 24-hour rainfall amounts were as high as 6.27 inches on the island of Hawai’i and 3.67 inches on the island of Kauai.

MIMIC Total Precipitable Water product, with tropical surface analyses [click to play animation]

MIMIC Total Precipitable Water product, with tropical surface analyses [click to play animation]

===== 03 December Update =====

GOES-15 Visible (0.63 µm) images (below) provided glimpses of the snow-covered peaks of Mauna Kea and Mauna Loa (circled in red) on the Big Island of Hawai’i early in the day on 03 December.

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]

Fires continue in the southeast United States

November 14th, 2016

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Fires (as seen on 07 and 10 November) continued to burn in parts of the southeast US on 14 November 2016. A sequence of 3 consecutive true-color Red/Green/Blue (RGB) images from Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) viewed using RealEarth, above, showed the aerial extent of the dense smoke that was most concentrated over Tennessee, Georgia, North Carolina and South Carolina. With the aid of some of the 16 spectral bands on the ABI instrument aboard GOES-R, true-color images like these will be available at least once every 5 minutes over the Lower 48 states and adjacent areas.

GOES-13 (GOES-East) Visible (0.63 µm) images with plots of surface weather and visibility (below; also available as an MP4 animation) revealed that visibility was restricted to 3 miles or less at one or more sites in all of the aforementioned states. A pair of pilot reports in eastern Tennessee indicated that he top of the smoke layer was at 6000 feet above ground level.

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

High loading of particulate matter (PM) due to smoke led to AIRNow Air Quality Index ratings of Unhealthy (red)  to Very Unhealthy (purple) over much of that 4-state region (below).

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

===== 15 November Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

A toggle between Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images (with and without METAR surface reports) at 0735 UTC or 3:35 am local time on 15 November (above) showed the “hot spot” signatures and bright glow from the larger fires that were burning in northern Georgia and western North Carolina. With ample illumination from the Moon — which was in the Waning Gibbous phase, at 99% of Full — smoke plumes from some of these fires could be seen drifting southward or southeastward,  thanks to the “visible image at night” capability of the Day/Night Band.

During the subsequent daytime hours, Terra MODIS and Suomi NPP VIIRS true-color RGB images (below) again revealed the vast coverage of the thick smoke — and VIIRS Aerosol Optical Depth values were quite high over South Carolina. Unhealthy AQI values persisted during much of the day across parts of Tennessee, Georgia and South Carolina.

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

A sampling of pilot reports (PIREPS) showed some of the impacts that the smoke was having on aviation (below).

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

===== 16 November Update =====

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true-color images (above) showed that much of the smoke had moved over the adjacent offshore waters of the Atlantic Ocean on 16 November.

 

Fires in the southeast United States

November 7th, 2016
terramodis_truecolor_7nov2016

Terra MODIS True-Color Imagery over the Smoky Mountains, 7 November 2016 (Click to enlarge)

Persistent moderate to severe drought (shown here, from this site) over the southeastern United States has supported the development of fires in and around the Great Smoky Mountains on 7 November 2016. True-color imagery from Terra MODIS, above, (source: MODIS Today) showed the active fires and plumes of smoke spreading northward into the Ohio River Valley.

Suomi NPP VIIRS true-color imagery also captured the smoke emanating from the active fires, and the Aerosol Optical Depth product, toggled below (data sources: RealEarth) showed the extent of the thickest smoke layer (click here for an animation that does not include the RealEarth framing).

Suomi NPP VIIRS true-color image with fire detection locations (red dots), and VIIRS Aerosol Optical Depth product [click to enlarge]

Suomi NPP VIIRS true-color image with fire detection locations (red dots), and VIIRS Aerosol Optical Depth product [click to enlarge]

A sequence of true-color Red/Green/Blue (RGB) images from Terra MODIS (1643 UTC), Suomi NPP VIIRS (1809 UTC) and Aqua MODIS (1824 UTC) is shown below.

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

The temporal evolution of the smoke was captured on GOES-13 Visible (0.63 µm) images (below; also available as an MP4 animation). Smoke reduced the surface visibility to 2.5 – 3.0 miles at some locations in Kentucky (KJKL | KLOZ) and Tennessee (KOQT), leading to EPA Air Quality Index values in the “Unhealthy” category.

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

===== 10 November Update =====

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

In the wake of a cold frontal passage on 09 November, northerly to northeasterly winds were transporting the smoke south-southwestward as the fires continued to burn on 10 November. GOES-13 Visible (0.63 µm) images, above, showed the dense smoke plumes — some of which were briefly reducing the surface visibility to less than 1 statute mile in far western North Carolina (Andrews | Franklin). In Georgia, smoke restricted the visibility to 2.5 miles as far south as Columbus.

A Pilot Report (PIREP) in northern Georgia at 1530 UTC, below, indicated that the top of the smoke layer was around 3500 feet (where the Flight Visibility was 4 miles).  Surface reports in the vicinity of that PIREP indicated a ceiling of 1500 to 1700 feet, suggesting that the dense smoke layer aloft was about 1800-2000 feet thick over northern Georgia.

GOES-13 Visible (0.63 µm) image, with cloud ceiling (hundreds of feet above ground level) and visibility (statute miles) plotted in cyan and a Pilot Report in yellow [click to enlarge]

GOES-13 Visible (0.63 µm) image, with cloud ceiling (hundreds of feet above ground level) and visibility (statute miles) plotted in cyan and a Pilot Report in yellow [click to enlarge]

The smoke plumes showed up very well on an Aqua MODIS true-color RGB image from the MODIS Today site, below.

Aqua MODIS true-color image [click to enlarge]

Aqua MODIS true-color image [click to enlarge]

The 1858 UTC Suomi NPP VIIRS true-color image (with fire detections) and the Aerosol Optical Depth product, below, depicted the aerial coverage of the smoke.

Suomi NPP VIIRS true-color image (with fire detection locations in red) and Aerosol Optical Depth product [click to enlarge]

Suomi NPP VIIRS true-color image (with fire detection locations in red) and Aerosol Optical Depth product [click to enlarge]