POES AVHRR visible, IR, and Mean Sea Level Pressure contours

AWIPS images of POES AVHRR visible and IR channel data with an overlay of Mean Sea Level Pressure contours (above) showed a very intense Storm Force low that was approaching the Alaska Panhandle region at 20:42 UTC on 12 October 2010. This large storm was producing widespread reports of strong winds and heavy rainfall, with wind gusts as high as 126 mph reported from a boat equipped with wind instruments in Thomas Basin near Ketchikan. There were also reports of multiple trees down in nearby Saxman.

The cloud features at 20:42 UTC could be further characterized examining the POES AVHRR Cloud Type, Cloud Top Temperature (CTT), and Cloud Top Height (CTH) products (below). CTT values within portions of the large “comma cloud” were as cold as -50 to -55º C, with CTH values as high as 8-9 km.

POES AVHRR Cloud Type, Cloud Top Temperature, and Cloud Height products

The evolution of this Storm Force low can be seen in a series of POES AVHRR IR images (below) — from the tell-tale “cusp” cloud feature indicative of strong cyclogenesis early in the day, to a closed-off, almost eye-like cloud structure later in the day.

POES AVHRR IR images

A POES AVHRR visible image with an overlay of 1-hour-interval GOES-derived Atmospheric Motion Vector (AMV) winds (below) showed the broad swath of strong winds associated with a low-level jet that was moving inland — a large number of AMVs had speeds in excess of 60 knots.

POES AVHRR visible image + GOES-derived Atmospheric Motion Vector winds

A comparison of an 8-km resolution GOES-11 water vapor image with the corresponding 1-km resolution MODIS water vapor image (below) revealed a well-defined dry slot moving inland. Strong momentum aloft was being transported downward to lower altitudes within this dry slot, contributing to the high winds that were being reported at the surface.

MODIS water vapor image + GOES-11 water vapor image

An animation of GOES-11 6.7 µm water vapor channel images (below) depicted the evolution of this dry slot during the day.

GOES-11 water vapor channel images

A comparison of the 12:00 UTC GOES-11 water vapor image with the corresponding MIMIC Total Precipitable Water product (below) indicated that a long atmospheric river of rich moisture was feeding into the developing cyclone. Note that not all  of the  “moist” features on the water vapor image necessarily correspond to areas of high total precipitable water content.

GOES-11 water vapor image + MIMIC Total Precipitable Water product

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GOES-13 0.63 µm visible images

Tropical Storm Paula formed just off the coast of Honduras on 11 October 2010. GOES-13 0.63 µm visible channel images from the CIMSS Tropical Cyclones site (above) showed the well-defined convective clusters associated with Paula.

The canopy of cold cloud tops was evident on GOES-13 10.7 µm IR channel images (below).

GOES-13 10.7 µm IR images

A comparison of a GOES-13 10.7 µm IR image with the corresponding Aqua AMSR-E 89 GHz microwave image (below) revealed a large area of heavy precipitation over a good portion of eastern Honduras.

GOES-13 IR image + Aqua AMSR-E 89 GHz microwave image

========== 12 OCTOBER UPDATE ==========

GOES-15 0.63 µm visible images

Paula rapidly intensified (CIMSS ADT plot) into a Category 2 hurricane on 12 October 2010. Paula briefly exhibited an eye during the morning hours on 1-km resolution GOES-15 0.63 µm visible channel imagery (above) and on 4-km resolution GOES-15 10.7 µm IR channel imagery (below). At 15:45 UTC,  ASCAT scatterometer winds were measured at 46 knots  surrounding the northern periphery of the center of Paula.

GOES-15 10.7 µm IR images

AWIPS images of the POES AVHRR Cloud Top Temperature (CTT), Cloud Top Height (CTH), and Cloud Type products at 18:46 UTC  (below) showed that the coldest CTT value was -86º C, with a large area of maximum CTH values of 16 km (much of that overshooting the tropopause, as indicated by the violet color enhancement on the Cloud Type product).

POES AVHRR Cloud Top Temperature, Cloud Top Height, and Cloud Type products

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MODIS and GOES-13 fog/stratus product images

AWIPS images showing comparisons of the 4-km resolution GOES-13 fog/stratus product with the 1-km resolution MODIS fog/stratus product (above) and also the 1-km resolution POES AVHRR fog/stratus product (below) offer further demonstration of the importance of improved spatial resolution for the detection of the small-scale filaments of valley fog that were forming across parts of the Appalachian Mountains region during the pre-dawn hours on 08 October 2010.

POES AVHRR and GOES-13 fog/stratus product images

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MODIS "color balanced" Red/Green/Blue (RGB) image

It’s not often that the entire state of Wisconsin is “cloud-free” — but the MODIS “color balanced” Red/Green/Blue (RGB) image (above; courtesy of Sam Batzli, SSEC / WisconsinView Project) shows a beautiful example of Wisconsin and adjacent areas on 05 October 2010. Note that we used quotation marks around the term “cloud free”: there was in fact a small smoke plume seen drifting northward from a fire that was burning in the far northwestern part of the state. Otherwise, the vast diversity of vegetation across the region was quite evident by their differences in appearance on the image — from the golden orange hues of Autumn tree leaf colors in northern Wisconsin and the Upper Peninsula of Michigan, to the tan-colored fields of harvested corn across parts of southern Wisconsin, northern Illinois, northeastern Iowa, and southeastern Minnesota.

Also of interest are the bright cyan-colored areas of water over far southern Lake Michigan and also over far northern Lake Superior — these were signatures of  algae blooms. MODIS Sea Surface Temperature values on this day ranged from the upper 40s F in western Lake Superior to the middle 60s F in southern Lake Michigan (below).

MODIS Sea Surface Temperature product

Back to the smoke plume seen in the MODIS image above: a comparison of AWIPS images of the 4-km resolution GOES-13 3.9 µm shortwave IR and the corresponding 1-km resolution MODIS 3.7 µm shortwave IR images (below) demonstrated the importance of spatial resolution for determining the exact location of small-scale features such as actively burning fires. The fire “hot spot” was significantly hotter on the MODIS image (48.5º C, orange color enhancement) than on the GOES-13 image (28.5º C, darker gray color enhancement).

GOES-13 3.9 µm shortwave IR + MODIS 3.7 µm shortwave IR images

===== 07 OCTOBER UPDATE =====

Yet another cloud-free day over Wisconsin two days later on 07 October, allowing a nice comparison of the changing Autumn tree colors (below).

MODIS true color images (05 October and 07 October 2010)

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