High wind event in Moscow, Russia

May 29th, 2017 |

Meteosat-10 Visible (0.8 µm, left) and Infrared Window (10.8 µm, right) images [click to play animation]

Meteosat-10 Visible (0.8 µm, left) and Infrared Window (10.8 µm, right) images [click to play animation]

High winds associated with a strong cold frontal passage were responsible for 16 fatalities and 168 injuries in Moscow, Russia on 29 May 2017 (CNN | BBC). EUMETSAT Meteosat-10 High Resolution Visible (0.8 µm) and Infrared Window (10.8 µm) images (above; MP4 ) showed the cluster of thunderstorms that moved through the region. Plotted in yellow are 4-letter station identifiers of the three principal Moscow airports (UUEE, UUWW and UUDD). The cloud-top Infrared brightness temperatures of the thunderstorm cluster exhibited a distinct bowing structure on Infrared imagery around the time of the highest winds (1230 UTC).

On the corresponding Meteosat-10 Water Vapor (6.25 µm) images (below; MP4), the well-defined signature of a middle-tropospheric vorticity center could be seen.

Meteosat-10 Water Vapor (6.25 µm) images [click to play animation]

Meteosat-10 Water Vapor (6.25 µm) images [click to play animation]

Time series plots of surface observations from the 3 major Moscow airports (below) showed that Sheremetyevo International Airport (UUEE) recorded a wind gust of 54 knots (62 mph) at 1230 UTC — also note the sharp drop in air temperature as the cold front passed.

Time series of surface observations at Sheremetyevo International Airport UUEE [click to enlarge]

Time series of surface observations at Sheremetyevo International Airport UUEE [click to enlarge]

Time series of surface observations at Vnukovo International Airport UUWW [click to enlarge]

Time series of surface observations at Vnukovo International Airport UUWW [click to enlarge]

Time series of surface observations at Domodedovo International Airport UUDD [click to enlarge]

Time series of surface observations at Domodedovo International Airport UUDD [click to enlarge]

Eruption of Bogoslof in Alaska’s Aleutian Islands

May 28th, 2017 |

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with hourly surface and ship reports plotted in yellow [click to play animation]

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with hourly surface and ship reports plotted in yellow [click to play animation]

The Bogoslof volcano in Alaska’s Aleutian Islands erupted around 2216 UTC on 29 May 2017. A comparison of Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (above; MP4) showed the volcanic cloud as it drifted north/northeastward.

A very oblique view of the volcanic cloud was captured by Korean COMS-1 satellite at 2315 UTC (below).

COMS-1 Visible (0.67 µm) images, with surface observations plotted in yellow [click to enlarge]

COMS-1 Visible (0.67 µm) images, with surface observations plotted in yellow [click to enlarge]

Himawaari-8 false-color images from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) revealed the initial signature of a volcanic cloud — however, this signature became less distinct after about 02 UTC on 29 May.

Himawari-8 false-color RGB images [click to play animation]

Himawari-8 false-color RGB images [click to play animation]

A different type of Himawari-8 false-color imagery (below) makes use of the 8.5 µm spectral band, which can help to infer the presence of sulfur dioxide within a volcanic cloud feature. A similar 8.4 µm band is available from the ABI instrument on the GOES-R series of satellites.

Himawari-8 false-color images [click to play animation]

3Himawari-8 false-color images [click to play animation]

A blend of Himawari-8 Infrared Window (10.4 µm) and radiometrically-retrieved Ash Cloud Height is shown below; the maximum ash cloud height was generally in the 10-12 km (33,000-39,000 feet above sea level) range (dark blue color enhancement). A volcanic ash signal was no longer apparent after 2320 UTC — this was likely due to enhanced ash particle removal via water (both liquid and ice) related processes.

Himawari-8 Infrared Window (10.4 µm) images and Ash Cloud Height retrievals [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images and Ash Cloud Height retrievals [click to play animation]

A DigitalGlobe WorldView image at 2234 UTC (below) provided remarkable detail of the Bogoslof volcanic cloud shortly after the eruption began.


Blowing Dust over northern Montana

May 24th, 2017 |

GOES-16 Visible Imagery (0.64 µm) from 1707 through 1802 UTC on 24 May 2017 (Click to enlarge)

GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing

The strong pressure gradient around a Low Pressure system over Alberta and Saskatchewan caused strong winds across northern Montana on 24 May 2017, and blowing dust was the result, especially in Hill and Blaine Counties. The visible animation, above, from 1707 to 1802 UTC on 24 May, shows a faint hazy signature along the border of Canada.  The emphasis is on the word ‘faint’ — it is very difficult to pick out the signature unless you know it’s there already  (Thanks to MIC Tanja Fransen at WFO Glasgow for alerting us to this event).  The ‘Blue’ Visible band animation (below) similarly shows the dust, but it is not distinct in this band either.  (*Note* — part of this, of course, is because the default enhancement for visible imagery has been used.  If the ‘low light’ enhancement is applied, the dust signature is more apparent. This visible animation from 1502-2122, courtesy Tanja Fransen, more obviously shows the dust).

GOES-16 Visible Imagery (0.47 µm) from 1707 through 1802 UTC on 24 May 2017 (Click to enlarge)

Brightness Temperature Difference products are routinely available in AWIPS. The Split-Window Difference (SWD), below, shows the difference between the ‘Clean Infrared Window’ (10.33 µm) and the ‘Dirty Infrared Window’ (12.3 µm) (‘Clean’ and ‘Dirty’ referring to a little and more, respectively, water vapor absorption) has historically been used to detect dust: dust will absorb 10.33 µm radiation but it will not absorb 12.3 µm radiation, thus the SWD can highlight regions of dust.  However, that difference is also influenced by water vapor above the dust, and by the type of dust being lofted.

Split Window Difference (10.33 µm – 12.2 µm) from 1707 to 1802 UTC, 24 May 2017 (Click to enlarge)

The Cloud Phase Difference (8.5 µm – 11.2 µm) also can highlight regions of dust, and for this case the signal of dust was a bit more distinct.

Cloud Phase Brightness Temperature Difference (8.5 µm – 11.2 µm) from 1707 to 1802 UTC, 24 May 2017 (Click to enlarge)

Surface data plotted over the 0.64 µm at 1712 UTC, below, show the strong winds in the region (Here is an image at 1802 UTC). Visibilities in the areas of blowing dust were reported to be near zero.

GOES-16 Visible (0.64 µm) at 1712 UTC and 1700 UTC surface observations (Click to enlarge)

A Terra MODIS true-color Red/Green/Blue (RGB) image at 1745 UTC, below, revealed that the source of some of the most dense dust plumes appeared to be uncultivated fields located north and northeast of Havre.

Terra MODIS true-color RGB image (Click to enlarge)

Terra MODIS true-color RGB image (Click to enlarge)

(Added: Stuart Lawrence, south of Rosetown in west-central Saskatchewan, tweeted out this video that showed the dust storm there. He reported winds up to 98 km/hour). Here is another image of the dust in Saskatchewan.

The GOES Aerosol/Smoke Products (GASP) showed a noticeable signal for this dust. Here is a large-scale animation from 1315-2145 UTC, with a closer view from 1015-2345 UTC here)

Middle/upper-level deformation zone over the East Pacific Ocean?

May 23rd, 2017 |

GOES-15 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]

GOES-15 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]

An interesting linear feature appeared over the East Pacific Ocean on GOES-15 (GOES-West) Water Vapor (6.5 µm) images (above) on 23 May 2017, which at first glance immediately nominated it for the “What the heck is this?” blog category. A contrail was ruled out, since it was not oriented along a common or busy flight route — so potential large-scale dynamic processes were briefly investigated. Since the linear feature was perpendicular to the busy California/Hawaii flight route, pilot reports of turbulence are plotted on the water vapor images; two reports of light turbulence at altitudes of 33,000-34,000 feet (at 0918 and 1109 UTC) appeared to be close enough to have possibly been related to the linear feature.

GOES-15 Water Vapor (6.5 µm) images, with contours of satellite wind derived upper-level divergence [click to enlarge]

GOES-15 Water Vapor (6.5 µm) images, with contours of satellite wind derived Upper-Level Divergence [click to enlarge]

Satellite atmospheric motion vector (AMV) derived products such as Upper-Level Divergence (above) calculated at 3-hour intervals (source) revealed an area of divergence focused near the area of the linear satellite image feature — around 30º N, 140º W, at the center of the images — which reached its peak intensity at 12 UTC; this suggested that the feature may have formed along the axis of the sharp deformation zone between two upper-level lows over the East Pacific Ocean (mid/upper level winds | 200 hPa Vorticity product).

GOES-15 sounder Water Vapor (6.5 µm, top; 7.0 µm, middle; 7.5 µm, bottom) images [click to enlarge]

GOES-15 sounder Water Vapor (6.5 µm, top; 7.0 µm, middle; 7.5 µm, bottom) images [click to enlarge]

Unfortunately, this region was not within the view of Himawari-8 or GOES-16 (each of which provide 2-km resolution water vapor imagery at 3 atmospheric levels). However, the GOES-15 sounder instrument has 3 similar water vapor bands (above) — albeit at a more coarse 10-km spatial resolution at satellite sub-point — which showed the linear “deformation axis cloud signature” at all 3 levels of the atmosphere. The GOES-15 sounder water vapor weighting functions for a “typical” US Standard Atmosphere are shown below.

GOES-15 sounder Water Vapor band weighting functions [click to enlarge]

GOES-15 sounder Water Vapor band weighting functions [click to enlarge]