Rapidly intensifying mid-latitude cyclone off the East Coast of the US

March 26th, 2014
Composite of GOES-15 (GOES-West) and GOES-13 (GOES-East) 6.5 µm water vapor channel images (click to play animation)

Composite of GOES-15 (GOES-West) and GOES-13 (GOES-East) 6.5 µm water vapor channel images (click to play animation)

AWIPS images of a composite of 4-km resolution GOES-15 (GOES-West) and GOES-13 (GOES-East) 6.5 µm water vapor channel data (above; click image to play animation) showed the development of a large mid-latitude cyclone off the East Coast of the US on 26 March 2014. This cyclone underwent rapid intensification as it moved northeastward, with the storm’s central pressure deepening 43 hPa in 24 hours and reaching a minimum value of 955 hPa (which was lower than the 960 hPa minimum central pressure of the March 1993 “Storm of the Century”). Wind gusts in excess of 100 mph were observed both on offshore buoys (44027) and at coastal sites: as the storm approached the Canadian Maritimes, Wreckhouse in Newfoundland experienced an all-time record maximum wind gust of 116 mph (186 km/hour).

A closer view of the storm’s evolution on GOES-13 6.5 µm water vapor channel imagery with overlays of buoy reports, cloud-to-ground lightning strikes, and analyzed surface pressure and surface fronts is shown below.

GOES-13 6.5 µm water vapor channel images (click to play animation)

GOES-13 6.5 µm water vapor channel images (click to play animation)

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (below; click image to play animation) revealed greater detail in the cloud structures near the center of the storm circulation. The appearance of dual vortices can be seen, with the northernmost vortex appearing to be the dominant one associated with the true storm center.

GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

A night-time view of the storm as it was beginning to intensify off the coast of Virginia at 05:56 UTC or 12:56 AM Eastern Time is seen in a comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel images (below). The bright white streaks appearing offshore on the DNB image are portions of the cloud illuminated by intense lightning — and there were a number of cloud-to-ground lightning strikes detected in the vicinity of these DNB lightning streaks.

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images at 05:56 UTC

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images at 05:56 UTC

As the period of rapid intensification continued off the eastern coast of the US, the GOES-13 sounder Total column Ozone product (animation) depicted very high values (400-450 Dobson Units, shades of red) just south of the storm center at 09:00 UTC, which was a signature of a potential vorticity anomaly (a lowering of the dynamic tropopause caused by an intrusion of dry, ozone-rich stratospheric air into the upper and middle troposphere). According to the GFS40 model, the height of the dynamic tropopause (taken to be the pressure of the PV1.5 surface) had descended to around the 450 hPa level at 06 UTC. The image comparison below shows that this pocket of high ozone was co-located with a pocket of dry middle-tropospheric air on the water vapor imagery, which became even drier with time to the point that it exhibited a light orange color enhancement around 12 UTC on the closer-view GOES-13 6.5 µm water vapor channel image animation seen above.

GOES sounder Total Column Ozone product and GOES imager 6.5 µm water vapor channel data

GOES sounder Total Column Ozone product and GOES imager 6.5 µm water vapor channel data

MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images at 15:40 UTC

MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images at 15:40 UTC

Daytime views of the storm structure were provided by comparisons of 1-km resolution MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images at 15:40 UTC or 10:40 AM Eastern Time (above) and 17:19 UTC or 12:19 PM Eastern Time (below).

MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images at 17:19 UTC

MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel images at 17:19 UTC

A comparison of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:19 UTC or 12:19 PM Eastern Time is shown below.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:19 UTC

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:19 UTC

SSEC RealEarth comparison of GOES-13 IR and Suomi NPP VIIRS true-color RGB images

SSEC RealEarth comparison of GOES-13 IR and Suomi NPP VIIRS true-color RGB images

The images above demonstrate using the SSEC RealEarth web map server to compare GOES-13 IR and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images of the storm, zooming in on the true-color image for more detail of dual vortex cloud features near the circulation center. The GOES IR image showed the impressively large size of the overall cloud structure associated with the mid-latitude cyclone.

The large size of the cyclone is also apparent in the VIIRS 1.38 µm imagery shown here. This wavelength highlights ice crystals — that is, high clouds — within the storm.

Additional details and satellite images of this storm can be found on the GOES-R and JPSS Satellite Liaison Blog.

Landsat-8 images of Washington State landslide site

March 23rd, 2014
Landsat-8 0.59 µm panochromatic visible image of the Washington State landslide site

Landsat-8 0.59 µm panochromatic visible image of the Washington State landslide site

Kudos to Russ Dengel of the SSEC RealEarth web map server development team for spotting this: a relatively cloud-free overpass of the Landsat-8 satellite which revealed the site of the massive landslide/mudslide near the small town of Oso in northwestern Washington State (north of Seattle). The animation shown above was made using RealEarth to zoom in with the Google Maps base layer, and then toggle between the base map and an overlay of 15-meter resolution Landsat-8 0.59 µm (Band 8) panochromatic visible imagery at 19:03 UTC or 12:03 PM local time on 23 March 2014. It can be seen that debris from the landslide — which occurred a day earlier — covered one mile of State Road 530, cutting off access to the town of Darlington (located east of the landslide site); it also blocked the North Fork of the Stillaguamish River, leading to fears of localized flooding both upstream and downstream of the landslide site.

The Landsat-8 visible image is shown below. The landslide was blamed on ground saturation due to heavy rainfall in the region over the past month (30-day total rainfall | depature from normal).

Landsat-8 0.59 µm panochromatic visible image

Landsat-8 0.59 µm panochromatic visible image

===== 01 April Update =====

Landsat-8 0.59 µm panochromatic visible image on 01 April

Landsat-8 0.59 µm panochromatic visible image on 01 April

14 days later, there was another overpass of the Landsat-8 satellite; it could be seen on the 0.59 µm panochromatic visible image (above) that the mudslide still covered a significant portion of State Road 530. The 1.61 µm near-IR image (below) revealed that the mudslide had altered the course of the North Fork of the Stillaguamish River, and highlighted areas where some localized flooding was occurring due to a widening of the river (water is a strong absorber at the 1.61 µm wavelength, so it appears dark on the near-IR image).

Landsat-8 1.61 µm near-IR image on 01 April

Landsat-8 1.61 µm near-IR image on 01 April

Widespread blowing dust across the south-central US

March 18th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed two very large blowing dust features during the afternoon hours on 18 March 2014: one moving southward out of southeastern Colorado, and another moving eastward out of New Mexico across Texas and Oklahoma. Winds gusted to 75 mph in southeastern Colorado, and 60 mph in the Texas Panhandle; surface visibilities were reduced to near zero at times at some locations. As a result, some highways were closed in southeastern Colorado. Another significant blowing dust event had impacted much of this same region one week earlier.

GOES-13 0.63 µm visible channel images with METAR surface reports (click to play animation)

GOES-13 0.63 µm visible channel images with METAR surface reports (click to play animation)

Taking a closer look at the large southward-moving dust plume with AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) and GOES-13 3.9 µm shortwave IR channel data (below; click image to play animation), it can be seen that a large wildfire began to burn around 19:15 UTC (2:15 PM local time) near the Texas/Oklahoma border as the strong winds associated with the leading edge of the dust storm moved through. The hot fire (yellow to red to black pixels on the shortwave IR images) produced pyrocumulus clouds and a smoke plume that rose above the top of the dust layer, high enough to cast a shadow due to the low sun angle at the end of the day. Note from the distance scale on the lower left portion of the visible images that this “wall of dust” was at least 300 miles wide.

GOES-13 3.9 µm shortwave IR images with METAR surface reports (click to play animation)

GOES-13 3.9 µm shortwave IR images with METAR surface reports (click to play animation)

The CLAVR-x POES AVHRR Cloud Top Height product (below) indicated that the top of the southward-moving dust layer was generally 1-2 km above ground level (cyan to light green color enhancement).

POES AVHRR Cloud Top Height product

POES AVHRR Cloud Top Height product

Terra and Aqua MODIS true-color Red/Green/Blue (RGB) images visualized using the SSEC RealEarth web map server (below) revealed that the composition of the dust from the 2 source regions took on a different appearance, indicating that the nature and composition of the aerosols were different.

Terra and Aqua MODIS true-color RGB images

Terra and Aqua MODIS true-color RGB images

AWIPS images of the Terra and Aqua MODIS “reverse absorption” 11-12 µm IR brightness temperature difference product (below) offered another method of identifying the areas where the airborne dust was the most dense.

Terra and Aqua MODIS 12.0-11.0 µm IR brightness temperature difference product

Terra and Aqua MODIS 12.0-11.0 µm IR brightness temperature difference product

Additional satellite images from this event can be found on the Wide World of SPoRT and RAMMB: GOES-R Proving Ground Blog sites.

===== 19 March Update =====

IDEA-I forecast aerosol trajectories (click to play animation)

IDEA-I forecast aerosol trajectories (click to play animation)

The IDEA-I MODIS Aerosol Optical Depth product indicated that much of the airborne dust remained over southern and eastern Texas on 19 March. Forecast forward trajectories (above; click image to play animation) suggested that some of this dust would get recirculated back northward across western Texas, and eventually move over Kansas in 24-48 hours.

Blowing dust from Baja California

March 16th, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-15 (GOES-West) 0.63 µm visible channel data (above; click image to play animation) revealed large plumes of blowing dust and sand, which were moving south/southwestward from the coast of Baja California and western Mexico on 16 March 2014. There were no surface observations in the immediate vicinity of the Baja California dust plume source regions, but farther to the southeast at Loreta (station identifier MMLT) winds gusted to 37 knots or 43 mph at 19 UTC (12 Noon local time), and surface visibility was reduced to 3 miles. Surface winds were likely channelled by the upstream mountainous terrain to reach higher speeds near the dust plume source regions.

A comparison of AWIPS images of Aqua MODIS 0.65 µm visible, 1.38 µm “cirrus detection”, 3.7 µm shortwave IR, 11.0 µm “IR window”, and 6.7 µm water vapor channel data at 21:40 UTC (below) showed the following: (1) the dust/sand plume could also be seen on the 1.38 µm “cirrus detection channel” image, since this channel can be used to identify any airborne particles that are effective scatterers of light (such as cirrus ice crystals, volcanic ash, haze, or dust/sand); (2) while there was no obvious dust/sand signal on the conventional IR window channel image, the much warmer (darker black) signature on the shortwave IR image was due to reflection of incoming solar radiation off the dust/sand particles; (3) on the water vapor image, an undular bore appeared to be developing near the leading edge of the dust/sand plume. According to 1-hour interval MADIS satellite-derived atmospheric motion vectors (green wind barbs), the plumes were moving toward the southwest at speeds as fast as 25 knots at the time.

Aqua MODIS 0.65 µm visible, 1.38 µm cirrus channel, 3.7 µm shortwave IR, 11.0 µm IR, and 6.7 µm water vapor channel images

Aqua MODIS 0.65 µm visible, 1.38 µm cirrus channel, 3.7 µm shortwave IR, 11.0 µm IR, and 6.7 µm water vapor channel images

Metop ASCAT surface scatterometer winds (cyan wind barbs) at 17:43 UTC (below) indicated that winds were northeasterly at speeds around 20 knots just off the western coast of Baja California; 18 UTC GOES-15 satellite-derived winds (green wind barbs) tracked the southwestward motion of the dust plumes at speeds of 20-31 knots.

GOES-15 0.63 µm visible image with GOES-15 satellite-derived winds and Metop ASCAT surface scatterometer winds

GOES-15 0.63 µm visible image with GOES-15 satellite-derived winds and Metop ASCAT surface scatterometer winds

A sequence of true-color Red/Green/Blue (RGB) images from Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS viewed using the SSEC RealEarth web map server (below) showed the southwestward progression of the tan-colored dense plumes of airborne dust/sand from Baja California. In the initial Terra MODIS image, the source region of many of the plumes appeared to be near the El Vizcaíno Biosphere Reserve.

Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS true-color RGB images

Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS true-color RGB images