Multiple rounds of severe thunderstorms moved northward across southern Arizona on 05 October 2010, producing hail as large as 2.5 inches in diameter, wind gusts as high as 75 mph, and rainfall in excess of 2 inches at some locations (SPC Storm Reports). According to NWS Phoenix, the 2.5 inch diameter hail was some of the largest hail ever reported in Arizona.

A 3-panel comparison of Visible channel images from GOES-11, GOES-15, and GOES-13 (above) showed the large clusters of convection, some of which moved through the Phoenix area (station identifier PHX). After 18:30 UTC, the GOES-11 satellite was placed into Rapid Scan Operations (RSO) mode, allowing images as frequently as every 5-7 minutes (in contrast to the standard operational 15-minute image interval on GOES-15 and GOES-13).

A comparison of GOES-11 Visible (0.65 µm) and Infrared Window (10.7 µm) images is shown below.

MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images (below) showed a closer view of the storms at 21:01 UTC or 3:01 pm local time. MODIS cloud-top infrared brightness temperatures were as cold as -61ºC (darker red color enhancement). Cloud-to-ground lightning strikes, severe reports of hail and wind, and surface METAR reports are also overlaid on the MODIS images.

The POES AVHRR Cloud Top Temperature (CTT) product (below) displayed a minimum CTT value of -63ºC just southeast of Chandler/Williams Air Force Base (station identifier KIWA) at 21:28 UTC or 3:28 pm local time.

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The series of three 250-meter resolution MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed the changes in color of the Fall foliage across parts of the Upper Peninsula of Michigan, far northern Wisconsin, and the Arrowhead of northeastern Minnesota on 4 different days: 19 September, 26 September, and 03 October 2010. These Red/Green/Blue images are created using MODIS Bands 01/04/03.

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The first lake-effect snow flurries of the season were observed in the Upper Peninsula of Michigan at Gwinn, Sawyer Airport (station identifier KSAW) on 02 October 2010. An AWIPS image of MODIS 11.0 µm IR channel data (above) showed a few disorganized cloud bands over Lake Superior, with the coldest cloud top IR brightness temperature values of -13.5º C over the KSAW area.

Looking at the buoy data and the ASCAT winds over Lake Superior (below), the wind speeds over the water were not particularly strong — but the winds at KSAW gusted as high as 36 mph during the day. The could be attributed in part to terrain interaction, as the surface winds encountered a rather abrupt change in topography immediately inland across the Upper Peninsula of Miichigan (where the elevations quickly rise to 1000-1800 feet).

The AVHRR Sea Surface Temperature (SST) product from late in the day on 01 October (below) indicated that SST values across much of the central and eastern part of Lake Superior were in the middle to upper 50s F (around 12 to 15º C). With 850 hPa air temperatures of 0º C to -5º C, the “Delta-T” values were not of sufficient magnitude for the formation of well-defined lake-effect snow bands.

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During the 26 September – 30 September 2010 period, copious amounts of moisture (which included the remnants of Tropical Storm Nicole) continually streamed northward along the US East Coast, causing historic rainfall totals (which were also accompanied by high winds and even several tornadoes: SPC Storm Reports). In Wilmington, North Carolina they received an amazing 23.36 inches of rainfall during the 5-day period. 

AWIPS images of GOES-13 6.5 µm water vapor channel data during the 29-30 September period (above) showed that a great deal of clouds and moisture were flowing northward along a stalled frontal boundary.

AWIPS images of the Blended Total Precipitable Water (TPW) product (below) showed TPW values as high as 60 to 75 mm (2.4 to 2.9 inches) moving northward along the Eastern Seaboard during much of the 5-day period.

These high TPW values were in excess of 200% of normal (below) for that region and for that time of year.

AWIPS images of the MIMIC Total Precipitable Water product (below) suggested that a portion of the moisture feed may actually have been coming from the tropical Pacific!

Within this plume of rich tropical moisture, vigorous convective cells were developing over the warm waters of the Gulf Stream and then feeding northward. AWIPS images of 1-km resolution MODIS 11.0 µm and POES AVHRR 10.8 µm IR channel data (below) revealed features with cloud top IR brightness temperatures in the -80º to -88º C range (light to dark purple color enhancement).

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