Unusually dry air over the Upper Midwest

April 20th, 2019 |

GOES-16 Low-level (7.3 µm, left) and Mid-level (6.9 µm, right) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm, left) and Mid-level (6.9 µm, right) Water Vapor images, with hourly plots of surface reports [click to play animation | MP4]

GOES-16 (GOES-East) Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor images (above) revealed a southwest-to-northeast oriented band of anomalously-dry air along the northwest periphery of a slow-moving low pressure center over the eastern US on 20 April 2019. The hourly dew point dropped to 10ºF at Chicago O’Hare, with a Relative Humidity value of 12% — a new record low value for Chicago. In addition, the dew point dropped to 6ºF at the Chicago Midway and Chicago Executive airports. With this dry air in place, note that the coastline of a portion of southern Lake Michigan could be seen in the 7.3 µm (and to a lesser extent, the 6.9 µm) Water Vapor images.

AWIPS examples of the GOES-16 Low-level and Mid-level Water Vapor imagery are shown below.

GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor images [click to play animation | MP4]

A larger-scale view of the GOES-16 Low-level Water Vapor (7.3 µm) image at 1201 UTC (below) showed that the Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX) rawinsonde sites were located within the elongated zone of dry air.

GOES-16 Low-level Water Vapor (7.3 µm) image, with plots of rawinsonde sites [click to enlarge]

GOES-16 Low-level Water Vapor (7.3 µm) image at 1201 UTC, with plots of rawinsonde sites [click to enlarge]

Plots of GOES-16 Water Vapor weighting functions for Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX) at 12 UTC (below) showed significant contributions from Band 10 (7.3 µm, violet) radiation originating at the surface — this allowed the thermal signature of the outline of Lake Michigan to be easily seen in the 7.3 µm Water Vapor imagery. Although the contribution of Band 9 (6.9 µm, blue) radiation originating near the surface was small, it was still enough to enable a brief and subtle coastal signature to be seen in the 6.9 µm images.

GOES-16 Water Vapor weighting functions for Gaylord, Michigan and Lincoln, Illinois at 12 UTC [click to enlarge]

GOES-16 Water Vapor weighting functions for Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX)  at 12 UTC [click to enlarge]

Plots of Total Precipitable Water sounding climatology for Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX), with record minimum values for 20 April at 12 UTC highlighted within a red box (below) showed that the 0.10″ at KAPX and the 0.12″ at KILX set new records for that date/time.

Plots of Total Precipitable Water sounding climatology for Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX), with record minimum values for 20 April at 12 UTC highlighted within a red box [click to enlarge]

Plots of Total Precipitable Water sounding climatology for Gaylord, Michigan (KAPX) and Lincoln, Illinois (KILX), with record minimum values for 20 April at 12 UTC highlighted within a red box [click to enlarge]

Smoke in the Gulf of Mexico

April 18th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with surface fronts plotted in cyan [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed some clearing of the dense pall of smoke across the far western Gulf of Mexico in the wake of a cold front that was moving southward/southeastward off the Texas coast on 18 April 2019. The parallel wave clouds of an undular bore were also evident ahead of the cold front from 13-16 UTC — the bore was also causing horizontal convective roll perturbations in the smoke about 20-40 miles ahead of the wave clouds (1506 UTC image).

The hazy signature of smoke was better defined in GOES-16 True Color Red-Green-Blue (RGB) images from the AOS site (below). This smoke was the result of widespread annual Springtime agricultural burning across southern Mexico, Guatemala, Belize and Honduras. Toward the end of the day, additional small plumes of smoke and blowing dust could  be seen moving back across the Gulf of Mexico into the “cleaner” air behind the cold front.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

Thermal anomalies or “hot spots” (yellow to red pixels) associated with the larger fires in Mexico, Guatemala, Belize and Honduras could be seen in GOES-16 Shortwave Infrared (3.9 µm) images (below).

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

A map of fires detected by Suomi NPP VIIRS on the previous day is shown below, as viewed using RealEarth.

Fires detected by Suomi NPP VIIRS on 17 April [click to enlarge]

Fires detected by Suomi NPP VIIRS on 17 April [click to enlarge]

Severe weather outbreak across eastern Texas and the Deep South

April 13th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

An outbreak of severe weather began in eastern Texas on the morning of 13 April 2019, where thunderstorms produced hail up to 3.0 inches in diameter, tornadoes and damaging winds (SPC storm reports). 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed the clusters of thunderstorms that developed as a surface low and associated frontal boundaries moved eastward (surface analyses). The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed numerous overshooting tops with infrared brightness temperatures as cold as -70 to -75ºC. In addition, the storm producing 3.0-inch hail and damaging winds at 1428 UTC exhibited an Above-Anvil Cirrus Plume (Visible/Infrared toggle).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

A comparison of Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1650 UTC is shown below.

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Later in the day, the thunderstorms continued to produce a variety of severe weather as they moved eastward across Louisiana and Mississippi, as shown by GOES-16 Visible and Infrared images (below).

GOES-16 "Red" Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

After sunset, the thunderstorms continued to move eastward, spreading more serve weather across Mississippi into Alabama and far southern Tennessee (below).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP (below) provided additional views of the storms as they were moving across Mississippi and Alabama. Several bright lightning streaks were evident on the Day/Night Band images. Note: the NOAA-20 image (downloaded and processed from the Direct Broadcast ground station at CIMSS) is incorrectly labeled as Suomi NPP.

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 at 0645 UTC and Suomi NPP at 0734 UTC [click to enlarge]

On a NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC (below), an impressively-long (~400 mile) dark “post-saturation recovery streak” extended southeastward from where the detector sensed an area of very intense/bright lightning activity northeast of Mobile, Alabama.

NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC [click to enlarge]

Satellite signatures of a SpaceX rocket launch

April 11th, 2019 |

GOES-16 Low-level Water Vapor (7.3 µm), Mid-levell Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm), Shortwave Infrared (3.9 µm) and

GOES-16 Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm) and Shortwave Infrared (3.9 µm) images from 2231-2251 UTC [click to enlarge]

The launch of a SpaceX Falcon Heavy rocket from the NASA Kennedy Space Center in Florida occurred at 2235 UTC on 11 April 2019. Warm thermal signatures of pockets of air (which had been superheated by the booster rocket exhaust) were seen northeast of the launch site in GOES-16 (GOES-East) Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm) and Shortwave Infrared (3.9 µm) images (above). In addition, closer to the launch site a (thermally-cooler) signature of the lower-altitude rocket exhaust condensation plume was evident — for example, see an annotated comparison of the 2236 UTC images below (GOES-16 was scanning that exact location at 22:37:22 UTC, a little more than 2 minutes after launch).

GOES-16 Low-level Water Vapor (7.3 µm), Mid-levell Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm), Shortwave Infrared (3.9 µm) images at 2236 UTC [click to enlarge]

GOES-16 Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm), Shortwave Infrared (3.9 µm) and “Red” Visible (0.64 µm) images at 2236 UTC [click to enlarge]

Two portions of the lower-altitude rocket condensation plume — one moving northeastward, and one moving westward — were seen in higher-resolution GOES-16 “Red” Visible (0.64 µm) images (below).

GOES-16 "Red" Visible (0.64 µm) images [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) images [click to enlarge]

The different directions of rocket condensation plume motion were due to directional shear of wind within the lowest 2 km or 6500 feet of the atmosphere, as shown in a plot of 00 UTC rawinsonde data from Cape Canaveral, Florida (below).

Plot of 00 UTC rawinsonde data from Cape Canaveral, Florida [click to enlarge]

Plot of 00 UTC rawinsonde data from Cape Canaveral, Florida [click to enlarge]

Similar signatures of other rocket launches have been seen using GOES-16 and GOES-17.