Possible Sting Jet Associated with strong storm in Europe

October 28th, 2013 |
Meteosat-10 6.2 µm WV channel images (click to play animation)

Meteosat-10 6.2 µm WV channel images (click to play animation)

Sting jets are wind maxima near the end of bent-back fronts in cases of strong cyclones. As noted earlier on this blog, they can acquire a characteristic look in water vapor imagery, vaguely reminiscent of a scorpion’s stinger. In addition, strongly sinking air around the jet, usually associated with both a tropopause fold and a maximum in ozone, is manifest as a warm (dry) patch in the water vapor (WV) imagery. In the animation above, the sting jet is apparent moving across northern Denmark into southern Sweden between 1500 and 1800 UTC. This is in association with the ‘St. Jude’ storm that killed more than a dozen across northern Europe (Reuters news story; Sky News story).

The strong sinking near a sting jet can transport momentum down to the surface. You should therefore expect to see strong surface wind gusts near the water vapor satellite signature, and that was the case on October 28, as shown below.

Hourly Meteosat-10 6.2 µm WV channel images and Observed Surface Wind Gusts (click to play animation)

Hourly Meteosat-10 6.2 µm WV channel images and Observed Surface Wind Gusts (click to play animation)

Suomi/NPP viewed this storm early in the day on 28 October. The toggle between the VIIRS Day/Night Band and the 11.45 µm IR data, below, shows a developing baroclinic leaf over the British Isles.

Toggle between VIIRS Day/Night Band and 11.45 µm IR imagery at 0220 UTC on 28 October (click to enlarge)

Toggle between VIIRS Day/Night Band and 11.45 µm IR imagery at 0220 UTC on 28 October (click to enlarge)

A comparison of Aqua MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images visualized using the SSEC Web map Server (below; courtesy of Russ Dengel and Kathy Strabala, SSEC) showed the storm at 12:14 UTC on 28 October. The warm/dry signature of strongly-subsiding middle to lower tropospheric air was particularly evident on the water vapor image (yellow to orange color enhancement) as it was beginning to move eastward over Denmark.

Aqua MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images

Aqua MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images

For additional satellite images of this event, see the EUMETSAT Image Library and the Wide World of SPoRT.

Widespread turbulence over the Southwest US

October 28th, 2013 |
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)

As a large upper-level trough was deepening and moving inland across the western US on 28 October 2013, strong winds interacting with the rugged terrain of the Southwest produced widespread areas of mountain waves, as revealed on McIDAS images of 4-km resolution GOES-13 6.5 µm water vapor data (above; click image to play animation). The fast speed of the animation revealed the non-stationary, “fluid motion” of some of the mountain wave features (especially over northeastern Arizona) — perhaps a clue that they might be associated with turbulence that was of moderate or greater intensity. In general, mountain waves that are quasi-stationary (and non-interfering) do not seem to produce more than light turbulence.

AWIPS images of composites of GOES-15 (GOES-West) and GOES-13 (GOES-East) 6.5 µm water vapor channel data with pilot reports of turbulence (below; click image to play animation) showed numerous reports of moderate to severe turbulence at a wide range of altitudes. In fact, there was even a relatively rare occurrence of a pilot report of Extreme turbulence at 18:01 UTC over far northwestern Arizona (at an altitude of 41,000 feet). Not far to the north, there was also a report of Severe turbulence at 23,000 feet over southwestern Utah.

Composite of GOES-15 and GOES-13 6.5 µm water vapor images, with pilot reports of turbulence

Composite of GOES-15 and GOES-13 6.5 µm water vapor images, with pilot reports of turbulence

MODIS 0.65 µm visible channel and 6.7 µm water vapor channel images

MODIS 0.65 µm visible channel and 6.7 µm water vapor channel images

An AWIPS comparison of 1-km resolution MODIS 0.65 µm visible channel and 6.7 µm water vapor channel images at 20:19 UTC (above) showed that while some of the mountain wave features were at least partially marked by roll clouds on the visible image, many of the mountain waves were occurring in clear air.