Hurricane Paula

October 11th, 2010
GOES-13 0.63 µm visible images

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

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

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

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

GOES-15 0.63 µm visible images

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

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

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

Valley fog across the Appalachian Mountains region

October 8th, 2010
MODIS and GOES-13 fog/stratus product images

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

POES AVHRR and GOES-13 fog/stratus product images

Severe thunderstorms in Arizona

October 5th, 2010
GOES-11 (left), GOES-15 (center), and GOES-13 (right) visible images

GOES-11 (left), GOES-15 (center), and GOES-13 (right) visible images

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 a Phoenix Public Information Statement, 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; also available as a QuickTime movie) 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).

AWIPS images of the MODIS 0.65 µm visible channel and 11.0 µm IR Window channel (below) showed a closer view of the storms at 21:01 UTC (3:01 pm local time). MODIS cloud top IR brightness temperatures were as cold as -61º C (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.

MODIS 0.65 µm visible and 11.0 µm IR Window images

MODIS 0.65 µm visible and 11.0 µm IR Window images

An AWIPS image of the POES AVHRR Cloud Top Temperature (CTT) product (below) displayed a minimum CTT value of -63º C just southeast of Chandler/Williams Air Force Base (station identifier KIWA) at 21:23 UTC (3:23 pm local time).

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product

First lake-effect snow flurries of the season in the Upper Peninsula of Michigan

October 2nd, 2010
MODIS 11.0 µm IR image + surface and buoy reports

MODIS 11.0 µm IR image + surface and buoy reports

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).

MODIS 11.0 µm IR image + surface and buoy reports + ASCAT surface winds

MODIS 11.0 µm IR image + surface and buoy reports + ASCAT surface winds

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.

AVHRR Sea Surface Temperature product + surface and buoy reports

AVHRR Sea Surface Temperature product + surface and buoy reports