Flooding in Louisiana

August 12th, 2016

Morphed MIRS observations of total precipitable water (TPW), 1500 UTC 11 August - 2100 UTC 12 August [click to play animation]

Morphed MIRS observations of total precipitable water (TPW), 1500 UTC 11 August – 2100 UTC 12 August [click to play animation]

Persistent convection in an atmosphere rich in moisture has led to life-threatening flooding over many Parishes in southern Louisiana. The animation above, taken from images at this site that morphs MIRS estimates of Total Precipitable Water (with values valid over both land and water) shows values around three inches over much of southeastern Louisiana. These TPW values agree with in situ observations such as the radiosonde from New Orleans at 1200 UTC on 12 August, where 2.70″ was observed. 24-hour rainfall totals ending at 1200 UTC on 12 August (Link) show a widespread region of more than 6″; raingauge observations of 6-hour totals at 1200 and 1800 UTC, below, show that the rain continued into the day on 12 August.

GOES-14 Visible (0.62 µm) images, with METAR observations of 6-hour precipitation, 1200 and 1800 UTC on 12 August 2016 [click to enlarge]

GOES-14 Visible (0.62 µm) images, with METAR observations of 6-hour precipitation, 1200 and 1800 UTC on 12 August 2016 [click to enlarge]

The flood-producing thunderstorms were very slow-moving, as evidenced in the animation of Infrared Window (10.7 µm) images from GOES-14, below (GOES-14 is in SRSO-R mode this month). Very little motion occurs in the two hours of this loop (using images at 5-minute time steps).

GOES-14 Infrared Window (10.7 µm) Imagery, 1625-1830 UTC on 12 August 2016 [click to play animation]

GOES-14 Infrared Window (10.7 µm) Imagery, 1625-1830 UTC on 12 August 2016 [click to play animation]

The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images from 0001-2358 UTC on 12 August is shown below.

GOES-14 Infrared Window (10.7 µm) images, with surface weather symbols plotted in yellow [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images, with surface weather symbols plotted in yellow [click to play MP4 animation]

This event is also discussed at the Satellite Liaison Blog, where the focus is on 1-minute visible imagery from GOES-14 and 1-minute lightning data.

===== 13 August Update =====

GOES-14 Infrared Window (10.7 µm) images, with hourly surface weather symbols plotted in yellow [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images, with hourly surface weather symbols plotted in yellow [click to play MP4 animation]

The heavy rainfall continued into 13 August, with storm total accumulations exceeding 31 inches in Louisiana (WPC storm summary). The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images spanning the period 1115 UTC on 11 August to 2159 UTC on 13 August, above, shows the development of multiple clusters of slow-moving thunderstorms, some of which exhibited cloud-top IR brightness temperatures of -80ºC or colder (violet color enhancement).

Heavy rainfall and flash flooding in Maryland

July 30th, 2016

GOES-13 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play animation]

GOES-13 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play animation]

A 2-panel comparison of GOES-13 (GOES-East) Visible (0.63 µm) and Infrared Window (10.7 µm) images (above) showed a band of thunderstorms oriented southwest-to-northeast across northern Virginia and northern Maryland late in the day on 30 July 2016. Cells within this band produced very heavy rainfall and extreme flash flooding at Ellicott City, Maryland — located northwest of Baltimore/Washington International Airport KBWI, and marked with a cyan * symbol — with a total of 6.60 inches of rain in just over 2 hours (NWS Baltimore/Washington Public Information Statement | Event summary). The coldest cloud-top IR brightness temperature was -67º C at 0045 UTC on 31 July (8:45 pm local time).

The MIMIC Total Precipitable Water product at 3-hour intervals (below) indicated the presence of TPW values in the 2.0 to 2.5 inch range over parts of the region.

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

Upstream rawinsonde data profiles from Washington Dulles International Airport in northern Virginia (below) showed TPW values of 46.8 mm or 1.83 inches at 12 UTC on 30 July, and 49.2 mm or 1.94 inches at 00 UTC on 31 July (although the later data looks suspect, given the balloon was launched as strong thunderstorms were approaching).

Washington Dulles VA rawinsonde profiles [click to enlarge]

Washington Dulles VA rawinsonde profiles [click to enlarge]

Severe thunderstorms and heavy rainfall/flooding in the Upper Midwest

July 12th, 2016

GOES-13 Infrared Window (10.7 µm) images, with SPC storm reports [click to play animation]

GOES-13 Infrared Window (10.7 µm) images, with SPC storm reports [click to play animation]

GOES-13 Infrared Window (10.7 µm) images (above; also available as an MP4 movie file) showed a series of mesoscale convective systems that moved across northeastern Minnesota, northwestern Wisconsin and the Upper Peninsula of Michigan during the 11 July12 July 2016 period. Some of these storms produced tornadoes, large hail, and damaging winds (SPC storm reports) in addition to heavy rainfall, with as much as 9.00 inches in Minnesota and 9.80 inches in Wisconsin (NWS Duluth storm summary). Several highways were closed due to flooding and/or washout, including a portion of Interstate 35 in Minnesota (interstates and highways are plotted in violet on the images).

A sequence of Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) (below) showed greater detail in the storm-top temperature structure at various times during the event.

Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to play animation]

Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to play animation]

===== 19 July Update =====

Comparison of before (09 July) and after (12 July through 19 July) Suomi NPP VIIRS true-color images [click to enlarge]

Comparison of before (09 July) and after (12 July through 19 July) Suomi NPP VIIRS true-color images [click to enlarge]

A comparison of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from before the event (09 July) and after the event (12 through 19 July) (above) revealed the large amounts of sediment flowing offshore into the southwestern portion of Lake Superior.

Another comparison of before (09 July) and after (13 through 19 July) true-color RGB images from Terra and Aqua MODIS is shown below.

Comparison of before (09 July) and after (13 through 19 July) Terra/Aqua MODIS true-color images [click to enlarge]

Comparison of before (09 July) and after (13 July through 19 July) Terra/Aqua MODIS true-color images [click to enlarge]

A toggle between a Terra MODIS Visible (0.65 µm) image and the corresponding MODIS Sea Surface Temperature (SST) product on 16 July (below) showed that the SST values in the sediment-rich nearshore waters were significantly warmer (middle 60s F, red enhancement) than those found closer to the center of Lake Superior (middle 40s F, cyan enhancement).

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]

Localized heavy rainfall and flooding in south-central Wisconsin

June 15th, 2016

GOES-13 Infrared Window (10.7 µm) images [click to play animation]

GOES-13 Infrared Window (10.7 µm) images [click to play animation]

GOES-13 Infrared Window (10.7 µm) images (above) showed the development of several rounds of deep convection which moved over parts of southern Wisconsin during the 14 June15 June 2016 period; these storms were responsible for heavy rainfall at some locations (NWS Milwaukee summary). As mentioned in a WPC Mesoscale Precipitation Discussion, some of these storms were focused along the nose of a low-level jet that was helping to push a warm frontal boundary (surface analyses) through the region. Moisture was also abundant south of the warm front, with a total precipitable water value of 55.1 mm (2.17 inches) seen in rawinsonde data from Davenport IA.

Landsat-8 false-color image [click to enlarge]

Landsat-8 false-color image [click to enlarge]

A timely cloud-free overpass of the Landsat-8 satellite on the morning of 15 June provided a 30-meter resolution false-color image as viewed using RealEarth (above), which showed areas of flooding — water appears as darker shades of blue — in the Black Earth area of western Dane County in southern Wisconsin. A before/after comparison of Landsat-8 images processed using an equation to highlight water as blue (below, courtesy of Shane Hubbard, SSEC/CIMSS) revealed the areas of inundation due to the 14-15 June thunderstorms.

Landsat-8 derived water change, 30 May vs 15 June 2016 [click to enlarge]

Landsat-8 derived water change, 30 May vs 15 June 2016 [click to enlarge]

Aerial footage from a drone flight (below) showed vivid images of the flooding along Black Earth Creek.

YouTube video from drone flight near Black Earth, Wisconsin [click to play]

YouTube video from drone flight near Black Earth, Wisconsin [click to play]