Severe thunderstorms in Texas and Oklahoma

May 20th, 2019 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of widespread thunderstorms that produced tornadoes, large hail (up to 5.5 inches in diameter in Texas) and damaging winds (as high as 94 mph in Oklahoma) (SPC storm reports) across parts of Texas and Oklahoma on 20 May 2019.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) indicated that cloud-top infrared brightness temperatures were frequently as cold as -70 to -80ºC (black to white to violet enhancement) with the more vigorous thunderstorms.

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [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 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play MP4 animation]

Zoomed-in versions of the Visible images (above) and Infrared images (below) are centered at Childress, Texas — which provide a better view of the storms which produced the 5.5-inch hail (Visible | Infrared) at Wellington, Texas and the large tornado near Magnum, Oklahoma (Visible | Infrared | YouTube video).

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

One interesting aspect of this line of deep convection: it was effectively acting as an obstacle to the upstream southwesterly flow, resulting in the formation of a quasi-stationary band of gravity waves along its western edge — these waves were very evident in GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below).

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

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

GOES-16 Split Window Difference (10.3-12.3 µm) images (below) displayed the yellow signature of blowing dust in the vicinity of a cold front that was moving eastward across southeastern New Mexico and southwestern Texas. Blowing dust restricted surface visibility to 3 miles or less at El Paso in Texas and at Alamagordo and Artesia in New Mexico.

GOES-16 Split Window Difference (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window Difference (10.3-12.3 µm) images [click to play animation | MP4]

During the subsequent overnight hours, these thunderstorms produced heavy rainfall from northern Oklahoma into southern Kansas, causing flash flooding — and flooding from rising rivers across that region on the following day were captured by the Suomi NPP VIIRS Flood Detection Product (below).

Suomi NPP VIIRS True Color and False Color RGB images, along with the Flood Detection Product [click to enlarge]

Suomi NPP VIIRS True Color and False Color RGB images, along with the Flood Detection Product [click to enlarge]

The river flooding in northern/northwestern Oklahoma was also evident in a before/after comparison of Terra MODIS False Color RGB images from 15 May and 21 May (below). Water appears as darker shades of blue in the False Color images.

Terra MODIS False Color RGB images over northern Oklahoma on 15 May and 21 May [click to enlarge]

Terra MODIS False Color RGB images over northern Oklahoma on 15 May and 21 May [click to enlarge]

River flooding in the Lower Mississippi and Tennessee River Valley

February 24th, 2019 |

30-day Precipitation and Percent of Normal Precipitation [click to enlarge]

30-day Precipitation and Percent of Normal Precipitation [click to enlarge]

A toggle between Observed Precipitation and Percent of Normal Precipitation for the 30-day period ending at 12 UTC on 24 February 2019 (above) showed a large area that received 10-15 inches of rainfall — which was 200-400% of normal — across the Lower Mississippi River and Tennessee River Valleys.

A before/after comparison of Terra MODIS False Color Red-Green-Blue (RGB) images from 25 January and 24 February 2019 (below) revealed the extensive area of flooding that resulted. Flooded areas appear as varying shades of blue on the False Color imagery (source).

Terra MODIS False Color RGB images from 25 January and 24 February 2019 [click to enlarge]

Terra MODIS False Color RGB images from 25 January and 24 February 2019 [click to enlarge]

In a comparison of Terra MODIS True Color and False Color RGB images from 24 February (below), many of the flooded rivers exhibit a tan-colored appearance in the True Color image due to large amounts of sediment suspended in the water.

Terra MODIS True Color and False Color RGB images from 24 February [click to enlarge]

Terra MODIS True Color and False Color RGB images from 24 February [click to enlarge]

A Flood Map derived using NOAA-20 VIIRS data (below) quantitatively showed the extent of the flooding. CIMSS scientists Jay Hoffman and William Straka contributed to the development of this food monitoring product.

NOAA-20 VIIRS Flood Map [click to enlarge]

NOAA-20 VIIRS Flood Map [click to enlarge]

Flood wave along the Nueces River in Texas

October 27th, 2018 |

As pointed out by NWS Corpus Christi (above), GOES-16 (GOES-East) Near-Infrared “Vegetation” (0.86 µm) images revealed an interesting flood wave moving along the Nueces River on 27 October 2018 (following a recent period of heavy rainfall).

A toggle between before (10 October) and after (27 October) Aqua MODIS False Color Red-Green-Blue (RGB) images from the MODIS Today site (below) showed dramatic differences between the amount of water (darker shades of blue) flowing along portions of the Nueces River on those 2 days.

Before (10 October) and after (27 October) Aqua MODIS False Color RGB images [click to enlarge]

Before (10 October) and after (27 October) Aqua MODIS False Color RGB images [click to enlarge]

A comparison of Suomi NPP VIIRS Visible (0.64 µm), Near-Infrared Vegetation (0.86 µm) and Near-Infrared Snow/Ice (1.61 µm) images from 27 October (below) demonstrated the improved land/water contrast of the Near-Infrared imagery, which makes it helpful for diagnosing certain types of flooding signatures.

Suomi NPP VIIRS Visible (0.64 µm), Near-Infrared Vegetation (0.86 µm) and Near-Infrared Snow/Ice (1.61 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Near-Infrared Vegetation (0.86 µm) and Near-Infrared Snow/Ice (1.61 µm) images [click to enlarge]

===== 28 October Update =====

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Vegetation” (0.86 µm) images at 1552 UTC on 27 and 28 October [click to enlarge]

A toggle between GOES-16 Near-Infrared “Vegetation” (0.86 µm) images at 1552 UTC on 27 and 28 October (above) showed the advance of the flood wave during that 24-hour period.

A comparison of Suomi NPP VIIRS Near-Infrared “Vegetation (0.86 µm) and “Snow/Ice” (1.61 µm) images from the early afternoon hours on 27 and 28 October (below) displayed these 24-hour changes at a higher spatial resolution (375 meters, vs 1 km at satellite subpoint with GOES-16). The rear edge of the flood wave (located about 25 miles southeast of Cotulla) appeared to show up a bit better in the 0.86 µm images than the 1.61 µm.

Suomi NPP VIIRS Near-Infrared

Suomi NPP VIIRS Near-Infrared “Vegetation (0.86 µm) and “Snow/Ice” (1.61 µm) images from 27 and 28 October [click to enlarge]

Finally, in a toggle between 250-meter resolution Aqua MODIS False Color RGB images from 27 and 28 October (below), the advance of the leading edge of the flood wave can clearly be seen.

Aqua MODIS False Color RGB images from 27 and 28 October [click to enlarge]

Aqua MODIS False Color RGB images from 27 and 28 October [click to enlarge]

===== 29 October Update =====

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Vegetation” (0.86 µm) images from 1552 UTC on 27, 28 and 29 October [click to enlarge]

GOES-16 Near-Infrared “Vegetation” images from 1552 UTC on 27, 28 and 29 October (above) showed the continued eastward movement of the flood wave down the Nueces River.

Flash flooding in southern Wisconsin

August 20th, 2018 |

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed multiple clusters of convection which developed across far southern Wisconsin during the late afternoon and early evening hours on 20 August 2018, producing very heavy rainfall and flash flooding (with at least one fatality) that was focused in western Dane County (CoCoRaHS | AHPS). As much as 15.33 inches of rain was reported in Cross Plains (Local Storm Reports). which set a new record for 24-hour precipitation in the state of Wisconsin (the old record was 11.72 inches at Mellen in northern Wisconsin on 24 June 1946). Animations of radar base reflectivity and storm total precipitation (courtesy of Pete Pokrandt, UW-AOS) showed that the combination of slow overall motion — and a pivoting of precipitation bands, due to weak flow aloft within a deformation zone (300 hPa analysis) —  and cell mergers played a role in producing the heavy rainfall. There was also an EF-0 tornado at Delavan (NWS Milwaukee summary).

The corresponding 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) imagery (below) showed that cloud-top brightness temperatures were generally in the -50º to -60ºC range with these initial areas of convection.

GOES-16 Infrared images [click to play animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface reports [click to play animation]

A longer Infrared animation (below) with a different color enhancement (adapted for winter convection) better emphasized the colder cloud tops as convective development persisted into the subsequent overnight hours. Note the absence surface observations from Middleton KC29 after 03 UTC or 10 pm CDT — this was due to an extended power outage to that area and other parts of western Dane County.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) revealed the large circulation associated with an occluded low (surface analyses) over the lower Missouri River valley.

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

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

The GOES-16 Total Precipitable Water derived product (below) showed that values of 1.3 to 1.5 inches were being advected northward toward the area.

Composite of GOES-16 Water Vapor (6.9 µm) imagery and Total Precipitable Water product [click to play MP4 animation]

Composite of GOES-16 Water Vapor (6.9 µm) imagery and Total Precipitable Water derived product [click to play MP4 animation]

With widespread cloudiness prevailing across much of the Upper Midwest, the CIMSS All-Sky Total Precipitable Water product (below) was helpful to better track the transport of moisture into the region — TPW values of 40-43 mm (1.6-1.7 inches) were seen feeding into southern Wisconsin within a TROWAL airstream around the northern edge of the occluded low pressure system (WPC discussion). The All-Sky products blend GOES ABI clear-sky retrievals with GFS background fields in cloudy regions; these products have been evaluated by the NWS Hazardous Weather Testbed (see here).

GOES-16 AllSky Total Precipitable Water product [click to play animation | MP4]

GOES-16 All-Sky Total Precipitable Water product [click to play animation | MP4]

The Aqua MODIS Total Precipitable Water product at 1943 UTC (below) showed TPW values of 40-45 mm (1.6-1.8 inch) on either side of the frontal boundary in northern Illinois.

Aqua MODIS Total Precipitable Water product [click to enlarge]

Aqua MODIS Total Precipitable Water product [click to enlarge]

One example of the hydrologic impact of the heavy rain was seen at the Pheasant Branch Creek USGS gauge (map), where nearly 11 inches of rainfall were recorded. A dramatic time-lapse video showed the rise of the normally-small creek as it inundated the adjacent multi-use path on 21 August.

Pheasant Branch Creek flows into the northwest corner of Lake Mendota, which crested at 852.3 feet on the morning of 22 August. This was the third highest lake elevation on record — and the highest level on record for so late in the calendar year. Portions of the University of Wisconsin – Madison campus adjacent to the lake experienced some impacts due to the high water, as shown on the map below. There were also several road closures in Madison due to high water.

Map of flood impacts for portions of the UW-Madison campus adjacent to the southwestern shoreline of Lake Mendota [click to enlarge]

Map of flood impacts for portions of the UW-Madison campus adjacent to the southwestern shoreline of Lake Mendota [click to enlarge]

Farther downstream on the Yahara River chain of lakes, Lake Waubesa reached its 100-year flood level on 22 August.