Flooding continues along the Mississippi River

May 17th, 2011 |
MODIS 0.65 µm visible channel image + MODIS 2.1 µm near-IR "snow/ice channel" image

MODIS 0.65 µm visible channel image + MODIS 2.1 µm near-IR "snow/ice channel" image

AWIPS images of MODIS 0.65 µm visible channel data and MODIS 2.1 µm near-IR “snow/ice channel” data (above) demonstrated the utility of the snow/ice channel imagery for highlighting the areal extent of flooding along parts of the lower Mississippi River on 17 May 2011. Water is a strong absorber at the 2.1 µm wavelength, so it appears very dark on the MODIS snow/ice channel image.

CIMSS participation in GOES-R Proving Ground activities includes making MODIS imagery available for National Weather Service forecasters to add to their AWIPS workstations. The VISIT training lesson “MODIS Products in AWIPS” is also available to help users understand the products and their applications to weather analysis and forecasting.

A closer view using 250-meter resolution MODIS true color (using channels 1/4/3) and false color (using channels 7/2/1) MODIS Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) revealed the darker brown “muddy” appearance of much of the flooded areas adjacent to the Mississippi River, due to high sediment loading of the water. Water exhibited a very dark blue appearance on the MODIS false color image.

250-m resolution MODIS true color and false color Red/Green/Blue (RGB) images

250-m resolution MODIS true color and false color Red/Green/Blue (RGB) images

Stratospheric intrusion vortex over Wisconsin

May 17th, 2011 |
GOES-13 0.63 µm visible channel images (click image to play animation)

GOES-13 0.63 µm visible channel images (click image to play animation)

AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed that 17 May 2011 was a generally cloud-free day over the state of Wisconsin.

However, the GOES-13 6.5 µm “water vapor channel” images (below; click image to play animation) displayed a series of well-defined “dry cyclonic swirls” aloft that were propagating southwestward. Due to the dry air associated with these features, the weighting function of the GOES-13 imager water vapor channel was shifted downward, sampling a layer that peaked near 500 hPa. GOES imager and sounder weighting functions for a particular rawinsonde location are available here.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

A comparison of the 1-km resolution MODIS 6.7 µm water vapor image with the corresponding 4-km resolution GOES-13 6.5 µm water vapor image (below) demonstrated the advantage of improved spatial resolution for displaying the edges and gradients associated with such features. The effect of parallax (due to the large viewing angle of the geostationary satellite positioned at the Equator) acted to shift the location of the GOES-13 features slightly to the northwest compared to the image from the polar-orbiting satellite that carries the MODIS instrument.

MODIS 6.7 µm water vapor image + GOES-13 6.5 µm water vapor image

MODIS 6.7 µm water vapor image + GOES-13 6.5 µm water vapor image

Hourly images of the GOES-13 sounder Total Column Ozone product (below; click image to play animation) revealed that ozone levels were quite high (over 400 Dobson Units, darker red color enhancement) within the large “dry swirl” feature that was moving over Wisconsin — this suggests that the dry vortex features seen on the water vapor imagery were actually stratospheric intrusion vortices (since high ozone is a characteristic of stratospheric air).

GOES-13 sounder Total Column Ozone product (click image to play animation)

GOES-13 sounder Total Column Ozone product (click image to play animation)

The Advanced Baseline Imager (ABI) instrument on the future GOES-R satellite will have an ozone channel, which will allow for this type of total column ozone product to be generated at higher spatial and temporal resolution that the current GOES Sounder instrument can provide.

A northwest-to-southeast oriented vertical cross section using RUC13 model fields (below) illustrated how low the tropopause (taken to be the height of the “PV1.5” Potential Vorticity surface) had descended within the PV anomaly associated with the stratospheric intrusion vortex over Wisconsin at 16:00 UTC.

RUC-13 model northwest-to-southeast oriented vertical cross section

RUC-13 model northwest-to-southeast oriented vertical cross section

As is sometimes the case with these features, there were a few pilot reports of light to moderate turbulence around the periphery of the well-defined stratospheric intrusion vortex as it moved across the region (below; click image to play animation).

GOES-13 6.5 µm water vapor images + pilot reports of turbulence (click image to play animation)

GOES-13 6.5 µm water vapor images + pilot reports of turbulence (click image to play animation)

CIMSS participation in GOES-R Proving Ground activities includes making products such as the GOES Sounder Total Column Ozone and MODIS imagery available for National Weather Service forecasters to add to their AWIPS workstations. The VISIT training lessons “Water Vapor Imagery and Potential Vorticity Analysis” and “MODIS Products in AWIPS” are available to help users understand the products and their applications to weather analysis and forecasting.

GOES-13 captures Space Shuttle Endeavour rocket plume and thermal signal

May 16th, 2011 |
GOES-13 0.63 µm visible channel images

GOES-13 0.63 µm visible channel images

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (above) showed the rocket launch plume of the Space Shuttle Endeavour as it ascended from a morning launch from Cape Canaveral on the east coast of Florida on 16 May 2011. The shadow of the rocket plume could also be seen on the patch of low-level clouds that was drifting over the region at launch time.

The hot thermal signature of the shuttle booster rockets could be seen on 4-km resolution GOES-13 3.9 µm shortwave IR imagery (below). The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing imagery as frequently as every 5 minutes to monitor conditions leading up to the launch.

GOES-13 3.9 µm shortwave IR images

GOES-13 3.9 µm shortwave IR images

Convective outflow boundary and softball-size hail in southern Wisconsin

May 11th, 2011 |
GOES-13 0.63 µm visible channel images + surface reports (click image to play animation)

GOES-13 0.63 µm visible channel images + surface reports (click image to play animation)

AWIPS images of 1-km resolution GOES-13 0.63 µm visible channel data (above; click image to play animation) showed a convective outflow boundary (originating from strong thunderstorms earlier in the day over northeastern Wisconsin) propagating southward across the eastern portion of the state on 11 May 2011. The leading edge of the outflow boundary moved farther to the south over the nearshore waters of Lake Michigan, where surface friction was less than that over land. Later in the day, clusters of severe thunderstorms were seen to develop over southcentral and southeastern Wisconsin, along an advancing warm frontal boundary.

A 1-km resolution POES AVHRR 10.8 µm “IR window” image (below) at 19:08 UTC (2:08 pm local time) revealed a number of overshooting tops, which exhibited IR brightness temperature values as cold as -70 to -78º C (black to white color enhancement). Overlaid are the numerous SPC reports of hail that had occurred up through 22:06 UTC — hail was as large as 1.75 inches in diameter in Dane County (where observation station Madison KMSN is located), and as large as 4.25 inches (softball-size) just to the east in Jefferson county (where observation station Watertown KRYV is located). A subtle signature of outward-propagating concentric gravity waves could also seen on the IR image of this hail-producing storm, which was especially evident over the northern portion of the cold cloud shield.

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service forecasters to add to their AWIPS workstations. A “POES and AVHRR Satellite Products in AWIPS” VISIT training lesson is also available to help users understand the products and their applications to weather analysis and forecasting.

POES AVHRR 10.8 µm IR image + SPC hail reports

POES AVHRR 10.8 µm IR image + SPC hail reports

A closer look at the aforementioned leading edge of the outflow boundary over the nearshore waters of Lake Michigan is offered using 250-meter resolution MODS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below). Multiple wave fronts can be seen associated with this density current as it moved southward near the Wisconsin/Illinois border region.

MODIS true color and false color Red/Green/Blue (RGB) images

MODIS true color and false color Red/Green/Blue (RGB) images