Eruption of the Mount Cleveland volcano in Alaska

June 19th, 2012 |
MODIS volcanic ash mass loading, ash height, and ash effective radius products

MODIS volcanic ash mass loading, ash height, and ash effective radius products

According to the Alaska Volcano Observatory, the Mount Cleveland volcano erupted around 22:05 UTC on 19 June 2012 (volcanic activity notice). A comparison of AWIPS images of the MODIS volcanic ash mass loading, ash height, and ash effective radius products (above) showed the volcanic ash plume about 1 hour and 40 minutes later (23:44 UTC). The products indicated that the mass loading was as high as 5.1 tons per square km, the maximum ash height was 7.92 km, and the maximum ash effective radius was 11.95 µm.

A comparison of a 23:43 UTC POES AVHRR 0.86 µm visible image with the corresponding 12.0 µm IR image (below) showed no discernable signal of the volcanic ash plume.

POES AVHRR 0.86 µm visible channel image + 12.0 µm IR channel image

POES AVHRR 0.86 µm visible channel image + 12.0 µm IR channel image

A 375-meter resolution Suomi NPP VIIRS 3.74 µm shortwave IR image (below) revealed a “hot spot” (yellow to red color enhancement) associated with the Mount Cleveland volcanic eruption. The maximum IR brightness temerature within the volcanic hot spot was 337.46 K or 64.31º C.

Suomi NPP VIIRS 3.74 µm shortwave IR image

Suomi NPP VIIRS 3.74 µm shortwave IR image

Hot temperatures in the US Desert Southwest

June 17th, 2012 |
MODIS 0.65 µm visible channel image + Land Surface Temperature product

MODIS 0.65 µm visible channel image + Land Surface Temperature product

The daily maximum temperature reported by the cooperative observer at Death Valley, California was 119 F on 17 June 2012, which was the highest temperature in the Lower 48 states so far in the summer season. A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel data with the corresponding Land Surface Temperature (LST) product (above) showed LST values as high as 150 F (darker red color enhancement) in some parts of Death Valley (which is located just east of the Superior Valley Gunnery Range, station identifier K4SU). While there is not a direct 1:1 correspondence between LST and the air temperature measured by a thermometer in a standard instrument shelter at a height of 5 feet off the ground, the LST product can still be useful in terms of locating important temperature gradients or identifying which areas of a particular county might be the warmest or the coldest.

A 250-meter resolution MODIS true color Red/Blue/Green (RGB) image from the SSEC MODIS Today site (below) showed that some patches of snow cover still remained at the highest elevations of the Sierra Nevada mountain range. A wide range in surface air temperatures was seen across the region, dependent on elevation: morning low temperatures at high elevation sites included 42 F at Tuolumne Meadows and 46 F at Lodgepole in California, and 45 F at Mt. Charleston, NV.

 

MODIS true color Red/Green/Blue (RGB) image (viewed using Google Earth)

MODIS true color Red/Green/Blue (RGB) image (viewed using Google Earth)

Hurricane Carlotta and Flooding Potential

June 15th, 2012 |
Hourly GOES-13 Visible Imagery (click image to play animation)

Hourly GOES-13 Visible Imagery (click image to play animation)

Carlotta is the third named system, and second Hurricane, of the young eastern Pacific Tropical Season. Hourly imagery from GOES-East shows the increase in organization in the storm as it approaches the coast of Mexico on the morning of June 15 2012. AMSU imagery from Channel 7 at 11UTC on 15 June shows the characteristic warm core usually found in tropical cyclones.

During a period of rapid intensification in the morning, GOES-13 10.7 µm IR channel images (below; click image to play animation) exhibited unusually cold cloud top IR brightness temperature values (as cold as -85 C at 15:45 UTC). This IR temperature was quite a bit colder than the tropical tropopause as indicated on the Acapulco, Mexico rawinsonde data, suggesting a significant degree of overshooting.

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

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

Data from the Cooperative Institute for Meteorological Satellite Studies’ (CIMSS) Tropical Cyclones site show that Carlotta is in a region that favors intensification. Sea-Surface Temperatures are very warm and shear is (although not weak) modest. Warm surface SSTs do not extend to great depth this early in the season (as shown in this map of Oceanic Heat Content); Carlotta’s forward motion should inhibit any weakening that might arise due to mixing of cooler sub-surface waters, however.

GOES-15/GOES-13 composite of Water Vapor images

GOES-15/GOES-13 composite of Water Vapor images

Carlotta is embedded within a very moist airmass. GOES water vapor imagery from 1500 UTC on 15 June (above), shows very little dryness near the storm. A MIMIC animation of Total Precipitable Water (TPW), below, shows the rich values of TPW surrounding the storm. As this airmass interacts with the high terrain of central coastal Mexico, life-threatening heavy rains are likely. Note how moisture-rich air associated with the hurricane is approaching the coast of Mexico from the east-southeast as moisture-rich air farther offshore is approaching from the west-southwest.

MIMIC Total Precipitable Water Imagery (click image to play animation)

MIMIC Total Precipitable Water Imagery (click image to play animation)

Morphed Observations of Microwave Imagery

Morphed Observations of Microwave Imagery

Morphed microwave imagery shows the quick organization of Carlotta for the 24 hours ending mid-day on June 15th. A nearly complete eyewall has developed during this time.

Turbulence within a Mesoscale Convective System cirrus outflow region

June 14th, 2012 |
Radar reflectivity mosaic

Radar reflectivity mosaic

A radar reflectivity composite (above) showed a large Mesoscale Convective System (MCS) that was moving across parts of Minnesota and Wisconsin on 14 June 2012, producing heavy rainfall (2.99 inches at Zumbrota in southeastern Minnesota) and some hail (SPC storm reports).

AWIPS images of GOES-13 0.63 µm visible channel data (below; click image to play animation) showed a broad area of anticyclonic cirrus outflow around the southern periphery of the MCS as it was dissipating during the late morning and early afternoon hours. There were a number of pilot reports of moderate turbulence seen within this banded area of cirrus outflow.

GOES-13 0.63 µm visible images with pilot reports of turbulence (click image to play animation)

GOES-13 0.63 µm visible images with pilot reports of turbulence (click image to play animation)

The banding structure within the cirrus outflow region was clearly shown on a 375-meter resolution (re-mapped onto an AWIPS 1 km grid) Suomi NPP VIIRS 11.45 µm IR image at 18:35 UTC  (below). A comparison with the corresponding 4-km resolution GOES-13 10.7 µm IR image demonstrated the advantage of higher spatial resolution for depicting such features.

Suomi NPP VIIRS 11.45 µm IR image + GOES-13 10.7 µm IR image

Suomi NPP VIIRS 11.45 µm IR image + GOES-13 10.7 µm IR image

The pronounced anticyclonic motion of the cirrus outflow (also verfied using MADIS 1-hour cloud-tracked winds) was creating strong wind shear aloft over much of eastern Iowa, southern Wisconsin, and northern Illinois — note how different the satellite wind vector directions were from the NAM 500-100 hPa deep-layer wind flow streamlines over that region (below). This strong wind shear aloft may have been a factor contributing to the numerous pilot reports of moderate turbulence within the area of cirrus outflow.

VIIRS 11.45 µm IR image + MADIS cloud-tracked wind vectors + NAM deep layer mean wind

VIIRS 11.45 µm IR image + MADIS cloud-tracked wind vectors + NAM deep layer mean wind

A similar depiction of the pronounced wind shear aloft was seen a few hours earlier on a 16:40 UTC MODIS 11.0 µm IR image (below).

MODIS 11.0 µm IR image + MADIS cloud-tracked wind vectors + NAM deep layer mean wind

MODIS 11.0 µm IR image + MADIS cloud-tracked wind vectors + NAM deep layer mean wind