Widespread fires continue in eastern Kansas; resultant smoke pall aloft over Missouri

April 13th, 2011 |

 

POES AVHRR 3.7 µm shortwave IR image

POES AVHRR 3.7 µm shortwave IR image

An AWIPS image of POES AVHRR 3.7 µm shortwave IR data (above) revealed a large number of fire “hot spots” (black to red to yellow pixels) across much of eastern Kansas on 12 April 2011. The majority of these were grassland fires.

On the following day (13 April 2011), a well-defined area of dense smoke aloft could be seen stretching from Missouri into southwestwen Iowa on a MODIS 0.65 µm visible channel image (below).

MODIS 6.5 µm visible channel image

MODIS 6.5 µm visible channel image

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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)

GOES-13 0.63 µm visible images (above; click image to play animation) showed that the dense smoke feature moved very little during the day. An overlay of NAM12 850 mb winds (below) indicated that light southwesterly winds in the morning transitioned to a more organized southeasterly flow as a low-level cyclonic circulation moved southward across Nebraska into Kansas.

GOES-13 visible images + NAM12 850 mb winds

GOES-13 visible images + NAM12 850 mb winds

A MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; displayed using Google Earth) provided a better view of the smoke pall aloft as the northern end wrapped around the low-level cyclonic circulation.

MODIS true color RGB image (displayed using Google Earth)

MODIS true color RGB image (displayed using Google Earth)

MODIS Aerosol Optical Depth (AOD) products from the IDEA site (below) showed very high ADO values  (orange to red color enhancement) associated with this smoke feature.

MODIS Aerosol Optical Depth (AOD) products

MODIS Aerosol Optical Depth (AOD) products

Record April tornado outbreak in Wisconsin

April 10th, 2011 |

Supercell thunderstorms developed along and ahead of an advancing cold frontal boundary and moved rapidly eastward across parts of northern and central Wisconsin on 10 April 2011. These severe storms produced  widespread damaging winds, large hail (up to 3.0 inches in diameter), and a significant number tornadoes (see: NWS La Crosse | NWS Green Bay | NWS Milwaukee | SPC Storm Reports). With 11 tornadoes confirmed so far, this was the largest single-day April tornado outbreak on record in Wisconsin.

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

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

McIDAS images of GOES-13 0.65 µm visible channel data (above; click image to play animation; also available as a QuickTime movie) showed a number of overshooting tops associated with these severe thunderstorms. The corresponding GOES-13 10.7 µm IR images (below; click image to play animation; also available as a QuickTime movie) showed the cold cloud top IR brightness temperatures (as cold as -67º C at 01:33 UTC), as well as a few enhanced-v and cold/warm couplet signatures.

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

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

A comparison of a 1-km resolution NOAA-15 AVHRR 10.8 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image at 21:33 UTC (below) demonstrates the advantage of higher spatial resolution to aid in the detection of enhanced-v and cold/warm thermal couplet storm top signatures, as well as a more accurate depiction of the coldest cloud top IR brightness temperatures associated with the more vigorous overshooting tops (-71º C on the NOAA-15 AVHRR IR image, compared to -58º C on the GOES-13 IR image).

NOAA-15 AVHRR 10.8 µm IR and GOES-13 10.7 µm IR images at 21:33 UTC

NOAA-15 AVHRR 10.8 µm IR and GOES-13 10.7 µm IR images at 21:33 UTC

An AWIPS GOES-13 0.65 µm visible image at 23:45 UTC (below) was particularly interesting — a few overshooting tops could be seen over central Wisconsin, as well as long shadows being cast upon the hazy boundary layer by a narrow line of developing convection to the southwest. Cloud-to-ground lightning strikes and storm reports (damaging winds, large hail, and tornadoes) are also overlaid on the visible image.

GOES-13 0.63 µm visible image + cloud-to-ground lightning strikes + storm reports

GOES-13 0.63 µm visible image + cloud-to-ground lightning strikes + storm reports

In an effort to try and locate a satellite signature of the damage path of the EF3-rated tornado that moved from Hamburg to Merrill to Gleason in north-central Wisconsin, a comparison of 250-meter resolution MODIS true color images from 10 April (a few hours before the tornado) and 12 April (2 days after the tornado) were used (below). However, the lack of a deep snow cover or dense vegetation in this area made it very difficult to identify the tornado damage path. Note that on 10 April — the day of the tornado outbreak — there still was some light snow cover just to the northwest of the tornado track, with some sites reporting 2-3 inches of snow remaining on the ground that morning.

MODIS true color images on 10 April and 12 April (displayed using Google Earth)

MODIS true color images on 10 April and 12 April (displayed using Google Earth)

Ship condensation trails over the Eastern North Pacfic Ocean

March 31st, 2011 |
GOES-11 0.65 µm visible channel images (click image to play animation)

GOES-11 0.65 µm visible channel images (click image to play animation)

McIDAS images of GOES-11 0.65 µm visible channel data (above; click image to play animation) showed a number of well-defined ship condensation trails (or “ship tracks”) propagating southward within the marine boundary layer stratocumulus cloud field over the eastern North Pacific Ocean on 31 March 2011.

A comparison of AWIPS images of 1-km resolution POES AVHRR 0.86 µm visible channel data and the corresponding 1-km resolution POES AVHRR Cloud Particle Effective Radius product (below) revealed that the ship tracks were composed of slightly smaller particles (lighter cyan color enhancement) than the surrounding stratocumulus clouds that they were embedded within. Note that many of the ship tracks could not be seen on the visible image within the more overcast stratocumulus cloud deck that covered the southern portion of the image — but their detection was possible using the Cloud Particle Effective Radius product.

POES AVHRR 0.63 µm visible and Cloud Particle Effective Radius product images

POES AVHRR 0.63 µm visible and Cloud Particle Effective Radius product images

As can be seen below, the ship track features did not show up very well in 1-km resolution images of the POES AVHRR Cloud Type product (showing liquid type clouds, cyan color enhancement), the Cloud Top Temperature product (showing temperatures around +10º C, green color enhancement), or the Cloud Top Height product (showing cloud tops around 2-3 km, purple color enhancement).

POES AVHRR Cloud Type product

POES AVHRR Cloud Type product

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Height product

POES AVHRR Cloud Top Height product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

Mid-tropospheric gravity waves upwind of intense convection

March 30th, 2011 |
GOES-13 6.5 µm water vapor images (click image to play animation)

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

McIDAS images of 4-km resolution GOES-13 6.5 µm water vapor channel data (above; click image to play animation) showed a well-defined warm/dry “arc” feature (denoted by the brighter yellow color enhancement) just upwind of a large Mesoscale Convective System (MCS) that was moving eastward along the northern Gulf of Mexico and the adjacent Gulf Coast states on 30 March 2011. The MCS eventually produced a number of reports of damaging winds, large hail, and tornadoes across northern Florida. Also note that a subtle signature of what appeared to be gravity waves could be seen within portions of this warm/dry arc feature (especially in the southern portion, over the Gulf of Mexico).

AWIPS images of 1-km resolution MODIS 6.7 µm water vapor channel data (below) offered a more detailed view of the packet of gravity waves that was associated with the southern portion of the dry arc feature. This warm/dry arc seen on the water vapor imagery could have been a signature of a region of strong compensating subsidence along the rear edge of the intense deep convection.

MODIS 6.7 µm water vapor images

MODIS 6.7 µm water vapor images

A number of pilot reports of moderate turbulence were co-located within this warm/dry arc feature seen on the water vapor imagery (below; click image to play animation), especially around 14 UTC, 16 UTC, and 17 UTC. There was also a report of severe turbulence along the northern portion of the arc feature as it moved over far southern Alabama at 17:35 UTC. This supports the idea that the warm/dry arc was likely a signature of strong subsidence in the wake of the MCS.

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

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

Note that a small patch of clouds developed along the southern portion of the warm/dry arc which contained the gravity waves over the Gulf of Mexico after about 18 UTC — additional information about this cloud patch could offer some clues as to the approximate altitude of the gravity waves. The POES AVHRR Cloud Type product (below) indicated that the cloud patch associated with the gravity wave was a cirrus feature (orange color enhancement).

POES AVHRR Cloud Type product

POES AVHRR Cloud Type product

The corresponding POES AVHRR Cloud Top Height product (below) suggested that the tops of that cloud patch were generally in the 12-13 km range (darker green color enhancement). POES AVHRR cloud top temperatures were in the -55 to -65º C range with this feature.

POES AVHRR Cloud Top Height product

POES AVHRR Cloud Top Height product

All of the above satellite evidence suggests that the gravity waves seen on the water vapor imagery were not surface-based, but were located at a higher altitude within the middle troposphere. In fact, the GOES-13 water vapor weighting functions calculated using rawinsonde data from Lake Charles, Louisiana (upstream of the MCS) and Tampa, Florida (downstream of the MCS) both peaked around 450 hPa (below), which tells us that the thermal energy being sampled by the water vapor channel in non-cloudy air was originating from within a high-altitude layer.

Lake Charles, Louisiana water vapor weighting function plot

Lake Charles, Louisiana water vapor weighting function plot

Tampa, Florida water vapor weigting function plot

Tampa, Florida water vapor weigting function plot

CIMSS participation in GOES-R Proving Ground activities includes making a variety of  MODIS and POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.