Blowing dust aided by a sting jet across the central Plains

December 15th, 2021 |

GOES-16 Dust RGB and Mid-level Water Vapor (6.9 µm) images [click to play animated GIF | MP4]

A sequence of 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Dust RGB and Mid-level Water Vapor (6.9 µm) images (above) showed the development of dense plumes of blowing dust (whose source regions were primarily in southeast Colorado and the Oklahoma/Texas Panhandles) on 15 December 2021. These dust plumes were being lofted by strong winds along and behind a cold front — which was associated with a rapidly-intensifying midlatitude cyclone. This storm then caused a broad swath of severe weather (SPC Storm Reports) as it moved rapidly northeastward toward the Great Lakes. 

GOES-16 Mid-level Water Vapor images with and without contours of hourly RAP model PV1.5 pressure (below) identified a Potential Vorticity (PV) anomaly which tracked northeastward across the region, indicating that the “dynamic tropopause” descended to the 700-750 hPa pressure level — which helped to transfer the momentum of strong winds aloft toward the surface. The general appearance of the water vapor imagery was similar to that seen in other cases when a “sting jet” helped to transport momentum aloft to the surface where high winds were observed (a sting jet is often found near the hook-shaped “scorpion tail” portion of the water vapor signature). The downward transport of dry mid/upper tropospheric air was supported by a rapid decrease in surface dewpoint temperature, seen at at a number of sites where the dewpoint dropped to below 0ºF (for example, from west to east across Kansas at Johnson KS | Ulysses KS | Pratt KS). Note that the brightest shades of pink/magenta on the GOES-16 Dust RGB images were located behind the primary eastward-moving cold front, where stronger winds associated with the sting jet had descended to the surface.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with and without contours of hourly RAP model PV1.5 pressure [click to play animated GIF | MP4]

A toggle between NOAA-20 NUCAPS-derived Tropopause Height, Total Column Ozone and Total Column Ozone Anomaly from the NASA SPoRT site (below) supported the presence of a PV anomaly over northwestern Kansas around that time, characterized by a low tropopause with anomalously-high total column ozone (2000 UTC GOES-16 Water Vapor image + PV1.5 pressure).

NOAA-20 NUCAPS Tropopause Height, Total Column Ozone and Total Column Ozone Anomaly around 1948 UTC [click to enlarge]

 

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

GOES-16 True Color RGB images created using Geo2Grid (above) highlighted the tan-colored blowing dust plumes (along with a couple of brighter-white wildfire smoke plumes) as they progessed northeastward across Kansas and Nebraska. A larger-scale view of GOES-16 Dust RGB images (below) showed that during the subsequent nighttime hours into the next morning, the brighter pink/magenta signature of blowing dust that became entrained into the circulation of the midlatitude cyclone could be followed as it eventually moved over parts of Minnesota, Wisconsin, Upper Michigan and Lake Superior — and eventually over far southern Ontario, Canada.  

GOES-16 Dust RGB images [click to play animated GIF | MP4]

Heavy rainfall and snowfall in Southern California

January 23rd, 2021 |

GOES-17 Air Mass RGB images, with contours of PV1.5 pressure [click to play animation | MP4]

GOES-17 Air Mass RGB images, with contours of PV1.5 pressure [click to play animation | MP4]

As an anomalously-deep 500 hPa low began to move inland over Southern California during the 23 January24 January 2021 period, GOES-17 (GOES-West)  Air Mass RGB images (above) showed a compact Potential Vorticity (PV) anomaly approaching the coast — and the RAP40 model indicated that the “dynamic tropopause” (defined here as the pressure of the PV1.5 surface) was descending to the 675 hPa pressure level at 18 UTC.

A west-to-east oriented cross section of RAP40 model fields along Line A-A’ (below) depicted the descending dynamic tropopause at 19 UTC.

Cross section of RAP40 model fields along line A-A' [click to enlarge]

Cross section of RAP40 model fields along line A-A’ [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) images (below) showed the increasing reports of rain and snow that resulted as the PV Anomaly moved inland and provided additional forcing for ascent. Near the coast, thunderstorms were reported at Fulton and Long Beach around 03 UTC. Storm total precipitation amounts included rainfall of 1.40 inch and snowfall of 12-18 inches.

GOES-17 Mid-level Water Vapor (6.9 µm) images, with plots of hourly surface weather type [click to play animation | MP4]

GOES-17 Mid-level Water Vapor (6.9 µm) images, with plots of hourly surface weather type [click to play animation | MP4]

GOES-17 Water Vapor images at 2301 UTC and 0246 UTC (below) revealed sporadic lightning activity (indicated by small clusters of GLM Groups).

GOES-17 Mid-level Water Vapor (6.9 µm) image at 2301 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 2301 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 0246 UTC, with GLM Groups plotted in red [click to enlarge]

GOES-17 Mid-level Water Vapor (6.9 µm) image at 0246 UTC, with GLM Groups plotted in red [click to enlarge]

===== 24 January Update =====

GOES-17 Day Snow-Fog RGB images [click t play animation | MP4]

GOES-17 Day Snow-Fog RGB images [click to play animation | MP4]

On the following day, as clouds began to clear the areal extent of resulting fresh snow cover (darker shades of red) was seen in GOES-17 Day Snow-Fog RGB images (above). Even parts of the high desert — north and east of the mountain ranges — received some snowfall (for example, 2-3 inches were reported at Hesperia).

Suomi NPP VIIRS True Color RGB and False Color RGB images (below) showed the snow cover (shades of cyan) at 2036 UTC.

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]

Cyclogenesis along the US East Coast

February 4th, 2019 |


The approach of an upper-tropospheric Potential Vorticity (PV) anomaly induced rapid cyclogenesis just off the US East Coast on 04 February 2019, with the surface low rapidly occluding (surface analyses). The eastward-propagating PV Anomaly was apparent on GOES-16 (GOES-East) Air Mass RGB images from the AOS site (below) as darker shades of orange — transitioning to shades of red as the tropopause descended to lower altitudes bringing more ozone-rich air from the stratosphere into the atmospheric column.

GOES-16 Air Mass RGB images [click to play MP4 animation]

GOES-16 Air Mass RGB images [click to play MP4 animation]

A sequence of Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm) (below) showed the cyclone at various stages of development. The surface low passed over  the Cape Lookout, North Carolina buoy as it was intensifying, with winds gusting to 44 knots around 12 UTC (winds/pressure | peak wind gusts).

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plot of fixed buoy reports [click to enlarge]

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plots of fixed buoy reports [click to enlarge]

A similar sequence of Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm) (below) showed the cyclone during daylight hours.

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

===== 05 February Update =====

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

After the primary center of circulation began to weaken, a pair of residual lower-tropospheric vortices (surface analyses) was seen to persist on GOES-16 “Clean” Infrared Window (10.3 µm) images (above), rotating around each other in a binary interaction known as the Fujiwhara effect. The two vortices were also evident in NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC (below) — in spite of the lack of illumination from a New Moon, airglow alone was sufficient to provide an impressive “visible image at night” with the Day/Night Band. (note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP)

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

During the early morning hours, an undular bore was evident on GOES-16 “Red” Visible (0.64 µm) images (below), moving toward the westernmost vortex. As the bore began to move over warmer waters of the Gulf Stream, it slowly dissipated.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Although not particularly intense, this slow-moving midlatitude cyclone was able to draw an appreciable amount of moisture northward from the tropics/subtropics as shown by the MIMIC Total Precipitable Water product (below).

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

Extratropical transition of Leslie

September 26th, 2018 |

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed Leslie as it transitioned from a Subtropical Storm at 00 UTC on 25 September to a Subtropical Depression at 03 UTC, then to a Post-Tropical Cyclone at 15 UTC, and eventually to a warm seclusion hurricane force cyclone with a classic “scorpion tail” sting jet signature by 00 UTC on 27 September.

Surface analyses during this 48-hour period are shown below; Leslie is located in the lower left corner. A longer animation (from 21-27 September) revealed the slowly-meandering circulation centers of pre- and post-Leslie (animated GIF | MP4).

Surface analyses at 6-hour intervals [click to play animation | MP4]

Surface analyses at 6-hour intervals [click to play animation | MP4]

The period of warm seclusion intensification of the remnants of Leslie, beginning after about 12-15 UTC on 26 September, was in response to the approach of an upper-level Potential Vorticity (PV) anomaly from the west-northwest (below). The “dynamic tropopause” — taken to be the pressure of the 1.5 Potential Vorticity Unit (PVU) surface — then descended to the 660 hPa pressure level (around 10,000 feet or 3 km) at 18 UTC on 26 September, according to GFS90 model fields.

GOES-16 Upper-level (6.2 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

GOES-16 Upper-level (6.2 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

GOES-16 Mid-level (6.9 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

GOES-16 Mid-level (6.9 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

GOES-16 Low-level (7.3 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

GOES-16 Low-level (7.3 µm) Water Vapor images, with contours of the PV1.5 pressure surface plotted in red [click to play animation | MP4]

This lowered tropopause brought ozone-rich air from the stratosphere down to very low altitudes — on GOES-16 Air Mass Red-Green-Blue (RGB) imagery (below), this ozone-rich air was highlighted by varying shades of red (the Air Mass RGB uses the 9.6 µm Ozone band to calculate the Green component).

GOES-16 Air Mass RGB images, with contours of PV1.5 pressure [click to play animation | MP4]

GOES-16 Air Mass RGB images, with contours of the PV1.5 pressure surface plotted in green [click to play animation | MP4]

A larger-scale view of the GOES-16 Air Mass RGB from the NWS Ocean Prediction Center (below) extends to 1115 UTC on 27 September.


An animation of the GOES-16 Air Mass RGB at 6-hour intervals from 00 UTC on 25 September to 12 UTC on 27 September is shown below, with and without contours of PV1.5 pressure. The dynamic tropopause descended to 850 hPa at 06 UTC on 27 September (when the storm was producing hurricane force winds) and eventually to 925 hPa at 12 UTC on 27 September (when it was producing storm force winds). The Air Mass RGB images highlighted the signature of the PV anomaly (shades of red) as it approached from the northwest then wrapped around the western and southern portion of the storm circulation.

GOES-16 Air Mass RGB images, with and without contours of GFS PV1.5 pressure [click to play animation | MP4]

GOES-16 Air Mass RGB images, with and without contours of GFS PV1.5 pressure [click to play animation | MP4]

The corresponding 6-hourly GOES-16 Split Water Vapor Difference (6.2 µm – 7.3 µm) images (below) show that a signature of the dry air aloft — associated with the aforementioned PV anomaly — was evident as a tongue of negative values in the -10 to -15ºC range (green to gray enhancement) that initially approached the storm from the northwest.

GOES-16 Split Water Vapor Difference (6.2 µm - 7.3 µm) images, with and without contours of PV1.5 pressure [click to play animation | MP4]

GOES-16 Split Water Vapor Difference (6.2 µm – 7.3 µm) images, with and without contours of PV1.5 pressure [click to play animation | MP4]

In cases such as this, the Air Mass RGB and Split Water Vapor Difference can be used in tandem to identify and track PV anomalies (18 UTC / 25 September | 12 UTC / 26 September). Note that east of the storm there also another small PV anomaly moving northward, associated with an upper-level low pressure feature — but this second PV anomaly played no role in the development/intensification of the post-tropical remnants of Leslie.

===== 27 September Update =====

Sequence of GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images from 09 UTC on 27 September to 00 UTC on 28 September [click to play animation | MP4]

Sequence of GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images from 09 UTC on 27 September to 00 UTC on 28 September [click to play animation | MP4]

A sequence of GOES-16 Low-level, Mid-level and Upper-level Water Vapor images from 09 UTC on 27 September to 00 UTC on 28 September (above) showed the classic wrapped dry/moist bands often seen with occluded mid-latitude cyclones.