Flooding continues along the Red River of the North

April 24th, 2011 |
MODIS false color image comparison between 11 April and 24 April 2011

MODIS false color image comparison between 11 April and 24 April 2011

 

A comparison of MODIS false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) shows the increase in areal coverage of flooding along the Red River of the North, from north of Grand Forks, North Dakota into southern Manitoba. Also evident is the melting of most of the snow cover across northeastern North Dakota, and the melting of portions of Devils Lake (snow and ice appear as cyan features on the false color images, while water has a darker blue appearance).

EF-4 tornado strikes the St. Louis, Missouri area

April 23rd, 2011 |
GOES-13 10.7 µm IR image (click image to play animation)

GOES-13 10.7 µm IR image (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed a large line of severe thunderstorms that moved eastward across the middle Mississippi River Valley region during the evening of 22 April 2011. This storm produced a significant number of large hail, damaging wind, and tornado reports (including one that did damage to the St. Louis airport). The initial storm damage survey has found EF-4 damage in the northern St. Louis county area.

A 1-km resolution POES AVHRR image very close to the time that the tornado was moving through the St. Louis area is shown below, with an overlay of the SPC hail, damaging winds, and tornado reports. Though the time stamp of the AWIPS image was “01:00 UTC”, the actual time that the NOAA-16 satellite was making its overpass of that region was about 01:12 UTC. Note that the storm exhibited a very well-defined “enhanced-v” signature near St. Louis (with a minimum cloud top IR brightness temperature of -83º C) — this enhanced-v IR storm top signature is often observed with areas of strong convection that are producing (or are about to produce) either large hail, damaging winds, or tornadoes.

POES AVHRR 12.0 µm IR image + severe weather reports

POES AVHRR 12.0 µm IR image + severe weather reports

On a larger-scale view, a comparison of the 1-km resolution POES AVHRR 12.0 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image (below) demonstrated two things: (1) how an improvement in spatial resolution can aid in the detection of small-scale cloud top features and signatures, and (2) the parallax shift of the high cloud top features on the GOES-13 image (features are shifted farther to the northwest compared to the POES AVHRR image, due to the large viewing angle from GOES-13). In spite of the AWIPS time stamps of the 2 images being different, the times of the images are actually about the same: the GOES image began scanning southward from southern Canada at 01:10 UTC, while the Miami ground station began to receive to NOAA-16 AVHRR image over the Gulf of Mexico at 01:00 UTC. Both images are scanning the St. Louis region around 01:12 UTC.

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

As the line of convection was organizing across western Missouri during the afternoon hours, GOES-13 sounder derived product images (below) of Convective Available Potential Energy (CAPE), Lifted Index (LI), and Total Precipitable Water (TPW) showed that the air mass south of the warm frontal boundary across eastern Missouri was moist (TPW values of 30-40 mm or 1.2 to 1.6 inches) and unstable (CAPE values exceeding 4000 J/kg and LI values of -5 to -9 C).

GOES-13 sounder Convective Available Potential Energy derived product image

GOES-13 sounder Convective Available Potential Energy derived product image

GOES-13 sounder Lifted Index derived product image

GOES-13 sounder Lifted Index derived product image

GOES-13 sounder Total Precipitable Water derived product image

GOES-13 sounder Total Precipitable Water derived product image

Earth Day 2011

April 22nd, 2011 |
Global montage of geostationary satellite images (click to play animation)

Global montage of geostationary satellite images (click to play animation)

The “spinning globe” satellite image montage (above; click image to play animation) showed the cloud formations around the planet on Earth Day (22 April 2011). This product is created by combining data from 5 of the currently operational geostationary orbiting meteorological satellites (GOES-East at 75º West longitude, GOES-West at 135º West longitude, Meteosat at 0º longitude, Meteosat at 63º East longitude, and MTSAT at 145º East longitude), polar orbiting satellites, and a topographic background map of the Earth. The spinning globe product is created every 3 hours, and is available for either the latest time period or an animation covering the last 3 weeks.

MODIS IR image atmospheric motion vectors over the Arctic region

MODIS IR image atmospheric motion vectors over the Arctic region

Polar-orbiting satellites such as the NASA Terra and Aqua platforms also provide us with valuable information over the polar regions of the Earth (which are not sampled well by geostationary satellites, due to the very large viewing angles). Cloud-tracked winds (or “atmospheric motion vectors”) can be calculated by comparing the location of features on successive images — examples of Terra and Aqua MODIS winds from 22 April 2011 over the Arctic region (above) and the Antarctic region (below) provide valuable input into numerical weather prediction models.

MODIS IR image atmospheric motion vectors over the Antarctic region

MODIS IR image atmospheric motion vectors over the Antarctic region

These are just a few examples of the diverse array of real-time satellite data and products that are available from the Space Science and Engineering Center at the University of Wisconsin – Madison every day.

Possible development of a subtropical or a tropical disturbance in the Atlantic Ocean?

April 20th, 2011 |
MIMIC Total Precipitable Water (TPW) product

MIMIC Total Precipitable Water (TPW) product

The National Hurricane Center initiated Invest 91 to monitor the potential development of a subtropical or even possibly a tropical cyclone over the western Atlantic Ocean on 20 April 2011. AWIPS images of the MIMIC Total Precipitable Water (TPW) product (above; click image to play animation) showed that a tongue of moisture was being advected northward from the band of higher moisture along the Inter-Tropical Convergence Zone (ITCZ) — and this moisture plume was being wrapped into the circulation of the developing disturbance.

A closer look at the MIMIC TPW product at 14:00 UTC along with an overlay of ASCAT scatterometer winds (below) revealed a well-defined cyclonic circulation at the surface, with gale force winds within the northwest quadrant of the storm.

MIMIC TPW product + ASCAT surface winds + Surface analysis

MIMIC TPW product + ASCAT surface winds + Surface analysis

===== 22 APRIL UPDATE =====

GOES-13 0.63 µm visible channel images

GOES-13 0.63 µm visible channel images

Animations of GOES-13 0.63 µm visible channel images (above) and GOES-13 10.7 µm IR channel images (below) from the CIMSS Tropical Cyclones site continued to show very well-defined cyclonic circulations associated with the feature on 22 April 2011.

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

GOES-13 6.5 µm water vapor channel images (below) indicated that dry mid-tropospheric air was wrapping into the system from the south and east.

GOES-13 6.5 µm water vapor channel images

GOES-13 6.5 µm water vapor channel images

A comparison of AWIPS images of the POES AVHRR 0.86 µm visible channel with ASCAT scatterometer surface wind data (below) revealed the development of deep convective elements just to the north of the low-level circulation center.

POES AVHRR 0.86 µm visible image + ASCAT scatterometer surface winds

POES AVHRR 0.86 µm visible image + ASCAT scatterometer surface winds

A sequence of three POES AVHRR 0.86 µm visible channel images (below) showed the evolution of the convective elements associated with the disturbance during the day.

POES AVHRR 0.66 µm visible channel images

POES AVHRR 0.66 µm visible channel images