Himawari-8 Dust RGB imagery, 0000 UTC 13 March 2021 through 2300 UTC 16 March 2021

 

 

 

The BBC reported that Beijing, the Capitol of China, was hit on 15 March by the worst sandstorm in a decade (link).  The linked-to article noted pollution levels 160 times the recommended limit! The dust and sand that overspread the city originated in Mongolia, and the dust RGB animation above (click here for an animated gif), shows dust appearing on 14 March and spreading rapidly southeast behind a propagating extratropical cyclone.  Multiple mid-layer clouds somewhat interfere with the dust/sand detection (bright red/magenta in the dust RGB shown), but the origins in Mongolia after 0600 UTC on 14 March, and the quick spread south by 1800 UTC on 15 March are apparent.

The toggle below compares Himawari-8 true-color imagery and the dust RGB at 0330 UTC on 15 March.  The dust/sand is apparent in the True Color imagery as well as in the RGB.

Himawari-8 imagery is courtesy JMA.  Image processing used Geo2Grid software.  This animation of surface analyses from 13-16 March 2021 (courtesy KMA) was created by Scott Bachmeier.

View only this post Read Less

The historic storm that affected the Rockies and Plains has shifted eastward, and is forecast to affect portions of the upper Midwest (link, from here).  There is abundant dry air that must be removed or eroded before the precipitation can fall around the Great Lakes.  The toggle above shows Rapid Refresh model esimates of 925-700 relative humidity and gridded NUCAPS observations of the same field. (This image shows the NUCAPS sounding availability points for this pass, plotted over the Day Night Band image).  Both relative humidity fields show dry air stretching northwest to southeast over the western Great Lakes.

The toggle below shows the Green Bay sounding at 0000 and 1200 UTC on 15 March (Click here to see the toggle for the Detroit sounding).  Northerly winds at 0000 UTC in Green Bay (except for low-level northeasterlies) shift to east-southeasterly at low levels at 1200 UTC.  Will that direction bring in moisture?  East-southeasterlies with the moisture field above will not moisten the atmosphere via advection.

Are there any satellite-derived winds showing southerly winds over the western Great Lakes?  The animation below shows Derived Motion wind vectors, alone, at first, and then overlain on GOES-16 low-level water vapor infrared imagery (7.34 µm). Note that an obvious land-sea contrast exists in the low-level water vapor imagery over lower Michigan; this is testimony to the very dry air in place. Derived-motion wind vectors do not indicate winds moving moisture into the western Great Lakes — but this is mostly due to high clouds preventing the satellite’s view of low-level motion.

The water vapor imagery does show strong deformation:  motion to the east-southeast over northeast Illinois, motion to the west-northwest over eastern Iowa and southeast Minnesota.

NUCAPS soundings give the most valuable moisture information in mid-troposphere. Perhaps the 925-700 mb fields, shown above, are not the optimal level. The comparison of 850-300 mb relative humidity fields, below, shows a very similar picture to the fields at the top of this post.

View only this post Read Less

As an anomalously-deep middle-tropospheric low migrated eastward over the Southwest US, severe thunderstorms developed ahead of a surface low and its associated cold front (surface analyses) as they moved from New Mexico into Texas on 13 March 2021 — as shown in 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) (above) and “Clean” Infrared Window (10.35 um) images (below). According to SPC Storm Reports, over a dozen tornadoes occurred (maximum intensity EF2), with hail as large as 2.5 inches in diameter and wind gusts as high as 87 mph.

South of the surface low, strong winds over the mountains of northern Mexico generated a significant amount of blowing dust (from deserts and dry lake beds), as seen in GOES-16 True Color RGB images created using Geo2Grid (above). This dust was then transported northeastward and eastward over parts of New Mexico and Texas, reducing the surface visibility at several sites. A pronounced dust signature (brighter shades of magenta) was also evident on GOES-16 Dust RGB images (below).

===== 14 March Update =====

Strong winds along the southern periphery of an intensifying winter storm over the central Rocky Mountains continued on 14 March — and GOES-16 True Color RGB images (above) showed another broad plume of blowing dust (along with a few narrow, brighter white smoke plumes from wildfires) that developed across northern Mexico, far southern New Mexico and western/southwestern Texas, which then moved northeastward during the day.

===== 15 March Update =====

GOES-16 Dust RGB images (above) indicated that a plume of dense airborne dust (brighter shades of magenta) which was initially transported northeastward across Texas on 14 March continued to move across Oklahoma during the subsequent overnight hours — where it appears to have merged with a patch of thickening clouds. These clouds continued to proceed northward across eastern Kansas and eventually passed over southeastern Nebraska and far northwestern Missouri, where there were reports of muddy residue from precipitation that had fallen upon vehicles:

Blowing dust from Texas + drizzle and light rain = muddy rain? pic.twitter.com/lZb8cLFsbH

— NWS Omaha (@NWSOmaha) March 15, 2021

This dust transport path was supported by HYSPLIT forward trajectories, initialized from a point centered on the dust plume in Texas (below).

In addition to the severe thunderstorms and strong winds / blowing dust discussed above, this complex and slow-moving system produced heavy snow in several states (WPC Storm Summary) — and a 2-day animation of GOES-16 Mid-level Water Vapor (6.9 µm) images covering the 13-15 March period (below) showed its large circulation.

View only this post Read Less

Clear skies over much of Alaska on 12 March meant that GOES-17 had a clear view of Denali.  The animation above, of GOES-17 CIMSS True Color imagery, shows the shadow of Denali (near the center of the imagery, due north of Cook Inlet) moving during the day.

A higher-resolution animation, below, using only the 0.64 µm visible imagery, from 1610 UTC on 12 March to 0240 UTC on 13 March 2021, also shows the changing of the shadow during the day.

View only this post Read Less