Atmospheric river events bring heavy precipitation to California

January 13th, 2017

MIMIC Total Precipatable Water product [click to play MP4 animation]

MIMIC Total Precipatable Water product [click to play MP4 animation]

A series of 3 atmospheric river events brought heavy rainfall and heavy snowfall to much of California during the first 10 days of January 2017 (NWS San Francisco/Monterey | WeatherMatrix blog). Hourly images of the MIMIC Total Precipitable Water product (above; also available as a 33 Mbyte animated GIF) showed the second and third of these atmospheric river events during the 06 January11 January 2017 period, which were responsible for the bulk of the heavy precipitation; these 2 events appear to have drawn moisture northeastward from the Intertropical Convergence Zone (ITCZ)..

Terra MODIS Visible (0.65 µm) and Near-Infrared

Terra MODIS Visible (0.65 µm) and Near-Infrared “Snow/Ice” (2.1 µm) images [click to enlarge]

A relatively cloud-free day on 13 January provided a good view of the Sacramento Valley and San Francisco Bay regions. A comparison of Terra MODIS Visible (0.65 µm) and Near-Infrared  “Snow/Ice” (2.1 µm) images (above) showed that snow cover in the higher terrain of the Coastal Ranges and the Sierra Nevada appeared darker in the Snow/Ice band image (since snow and ice are strong absorbers of radiation at the 2.1 µm wavelength) — but water is an even stronger absorber, and therefore appeared even darker (which allowed the areas of flooding along the Sacramento River and its tributaries to be easily identified). A similar type of 1.6 µm Near-Infrared “Snow/Ice” Band imagery will be available from the ABI instrument on the GOES-R series, beginning with GOES-16.

Better detail of the flooded areas of the Sacramento River and its tributaries was seen in 250-meter resolution false-color Red/Green/Blue (RGB) imagery from the MODIS Today site — water appears as darker shades of blue, while snow appears as shades of cyan (in contrast to supercooled water droplet clouds, which appear as shades of white). In the corresponding MODIS true-color image, rivers and bays with high amounts of turbidity (tan shades) were evident; the offshore flow of sediment from a few rivers could also be seen.

Terra MODIS true-color and false-color RGB images [click to enlarge]

Terra MODIS true-color and false-color RGB images [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]

Landsat-8 Imagery

January 16th, 2016

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

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

Landsat-8 imagery — with a spatial resolution of 15 to 30 meters — is available for viewing via the SSEC RealEarth web map server. An example of a swath of false-color Red/Green/Blue (RGB) imagery across the central US between the times of 1630-1640 UTC on 16 January 2016 is shown above. Snow cover and ice (as well as ice crystal clouds) appear as varying shades of cyan in this type of RGB image.  Let’s take a closer look at 3 regions along this overpass to examine some interesting features.

The northerly flow of arctic air over the still-unfrozen waters of Lake Superior was aiding the development of lake effect snow (LES) bands, some of which were moving inland over the eastern portion of the Upper Peninsula of Michigan. One of the more well-defined LES bands was seen to be moving across the Grand Marais area — a cooperative observer 10 miles south of the city reported 8.5 inches of new snow during the 24-hour period from 12 UTC on 16 January to 12 UTC on 17 January.

Landsat-8 false-color RGB image over Lake Superior [click to enlarge]

Landsat-8 false-color RGB image over Lake Superior [click to enlarge]

Looking farther to the south, an interesting feature was seen in the southern part of ice-covered Green Bay, Wisconsin (below): a channel through the ice (red arrows) had been cut by the US Coast Guard icebreaker Mackinaw during the evening of 14 January, to allow passage for a ship to unload cargo at a dock along the mouth of the Fox River (which empties into the southern end of Green Bay). Hat tip to the NWS Green Bay for providing the information on which icebreaker was involved.

Landsat-8 Panchromatic Visible (0.59 µm) and False-color RGB images [click to enlarge]

Landsat-8 Panchromatic Visible (0.59 µm) and False-color RGB images [click to enlarge]

Finally, a look to the southern portion of the overpass: the Mississippi River, between the states of Louisiana and Mississippi. The Landsat satellites fly over the same portion of the Earth every 17 days, so taking advantage of this fact we can visualize the profound changes in the southern Mississippi River due to the flow of large amounts of water resulting from heavy rainfall farther to the north — over the Middle Mississippi River and Ohio River Valley regions — during December 2015 (as discussed in this blog post). Water appears as darker shades of blue in these particular Landsat RGB images, aiding in the identification of areas where flooding is occurring.

Landsat-8 false-color RGB images on 31 December 2015 and 16 January 2016 [click to enlarge]

Landsat-8 false-color RGB images on 31 December 2015 and 16 January 2016 [click to enlarge]