Lake effect clouds in North Central Texas

December 18th, 2015 |

GOES-13 Fog/stratus product (10.7 µm - 3.9 µm) and Visible (0.63 µm) images [click to play animation]

GOES-13 Fog/stratus product (10.7 µm – 3.9 µm) and Visible (0.63 µm) images [click to play animation]

GOES-13 nighttime “Fog/stratus product” IR brightness temperature difference (10.7 µm – 3.9 µm, 4-km resolution) and daytime Visible (0.63 µm, 1-km resolution) images (above) showed the development of lake effect cloud bands that streamed southward across North Central Texas during the pre-dawn and early morning hours on 18 December 2015. As high pressured moved southward over the region in the wake of a cold frontal passage (surface analyses), colder air with surface temperatures in the upper 20s to middle 30s F flowed over the still-warm waters of the larger reservoirs located north and east of the Dallas/Fort Worth metroplex (below), creating instability which aided in the formation of the cloud bands (as seen using RealEarth).

GOES-13 Visible (0.63 µm) image at 1445 UTC, with Google maps background [click to enlarge]

GOES-13 Visible (0.63 µm) image at 1445 UTC, with Google maps background [click to enlarge]

The 1-km resolution MODIS Sea Surface Temperature product (below) indicated that lake water temperatures were still as warm as the lower to middle 50s F, with a maximum value of 57º F seen in Lake Tawakoni.

Terra MODIS Visible (0.65 µm) image and Sea Surface Temperature product [click to enlarge]

Terra MODIS Visible (0.65 µm) image and Sea Surface Temperature product [click to enlarge]

Hat tip to the NWS Fort Worth for alerting us to this interesting event via Twitter.

Meso-vortex over Qinghai Lake, China

December 18th, 2015 |

We received the following notification on Twitter from Walt Clark:

Good catch Walt, and thanks for the heads-up! Using the Location Search feature of RealEarth, we found that Qinghai Lake is located in central China, and Wikipedia told us it’s also the largest lake in China. (Qinghai Lake is slightly smaller than the Great Salt Lake in Utah) The mesoscale vortex can be seen over the lake on a Himawari-8 true-color Red/Green/Blue (RGB) image at 0400 UTC on 18 December 2015 (below).

Himawari-8 true-color image at 0400 UTC [click to play zoom-in animation]

Himawari-8 true-color image at 0400 UTC [click to play zoom-in animation]

Daytime Himawari-8 Visible (0.64 µm, 0.5-km resolution) images (below) showed the feature spinning cyclonically over Qinghai Lake as it slowly migrated northward.

Himawari-8 Visible (0.64 µm) images [click to play animation]

Himawari-8 Visible (0.64 µm) images [click to play animation]

However, we’re not certain that this was a Mesoscale Convective Vortex (MCV); while there was some convection over the mountains north of the lake during the preceding nighttime hours on 17 December which exhibited cloud-top IR brightness temperatures around -40º C (color-enhanced Himawari-8 Infrared animation), it appears more likely that this might have been a convective outflow boundary from those mountain thunderstorms which became trapped within the “bowl” of high terrain that nearly surrounds the lake. A long animation which concatenates the earlier nighttime Himawari-8 Infrared (10.4 µm, 2-km resolution) and the later daytime Himawari-8 Visible (0.64 µm, 0.5-km resolution) images is shown below. It is difficult to trace the origin of the vortex feature as being from the aforementioned convective activity.

Himawari-8 Infrared (10.4 µm) and Visible (0.64 µm) images [click to play animation]

Himawari-8 Infrared (10.4 µm) and Visible (0.64 µm) images [click to play animation]

The meso-vortex was also seen on a MODIS true-color RGB image from the Aqua satellite, which did an overpass of the region around 0642 UTC (below). While some small patches of ice did appear to be forming along the edges of Qinghai Lake, it remained predominantly ice-free (unlike the smaller and presumably more shallow Har Lake to the northwest, which looked to be totally ice-covered).

Aqua MODIS true-color RGB image, with Google maps background [click to enlarge]

Aqua MODIS true-color RGB image, with Google maps background [click to enlarge]