AWIPS images of the GOES-12 6.5µm “water vapor channel” (above; QuickTime animation) revealed the large size of a cyclonic circulation off the southeast US coast on 08 May 2007. This system was eventually named Subtropical Storm Andrea by the National Hurricane Center the following morning. One noteworthy aspect of Andrea was the fact that it’s formation ended the longest period recorded in the satellite era (33 days) without a tropical cyclone in any ocean basin (the last tropical cyclone was Tropical Cyclone Cliff in the South Pacific Ocean, which dissipated on 06 April 2007).

GOES-12 water vapor winds (above) showed several upper-tropospheric targets of 50 knots (57 mph) or greater in the northern quadrant of the cyclone at 15:00 UTC on 08 May — Buoy 41013 off the coast of North Carolina reported a wind gust of 48 knots (55 mph) earlier that day. The strong winds around the periphery of the storm were causing ongoing wildfires in Georgia and Florida to intensify, creating very impressive smoke plumes which drifted southward across parts of Florida and the adjacent offshore waters of the Gulf of Mexico (GOES-12 visible images: Java animation). Thick smoke (which caused air quality problems and highway closures in some areas of Florida) was also very evident on MODIS true color imagery (below) and on the MODIS Aerosol Optical Depth (AOD) product.

View only this post Read Less

The largest outbreak of severe weather so far this season developed across a large portion of the central US on 04 May / 05 May / 06 May 2007, producing tornadoes from Texas to South Dakota, hail up to 4.25 inches in diameter in Nebraska, and wind gusts to 90 mph in Kansas. GOES-12 images of the 10.7µm InfraRed (IR) channel (above; QuickTime animation) show the development of the severe convection that spawned the deadly EF-5 tornado that destroyed much of Greensburg, Kansas (located near the center of the images) around 02:38 UTC on 05 May (9:38 PM on 04 May, local time). This was the first F5/EF-5 tornado damage in the US since May 1999.

One striking aspect of the IR satellite imagery on 06 May was the large areal coverage of unusually cold cloud top temperatures (colder than -80º C, purple enhancement) early in the day over eastern Nebraska and western Iowa (above; QuickTime animation). A comparison of 1-km resolution NOAA-18 IR and 4-km resolution GOES-12 IR (below) reveals cloud top temperatures as cold as -87º C (-125º F) and -85º C (-121º F), respectively; such a close agreement between AVHRR vs. GOES IR temperatures is also somewhat unusual, since the higher spatial resolution of the AVHRR instrument often senses cloud top temperatures that are as much as 10-20º C colder than GOES in the areas of convective storm tops.

View only this post Read Less

While the large (472,000 acre) Sweat Farm Road / Big Turnaround fire complex continued to burn for the 17th consecutive day south of Waycross, Georgia, a second fire (the 6000-acre Roundabout fire west of Waycross) was also beginning to produce very thick smoke on 02 May 2007. GOES-12 visible imagery (above; Java animation) showed the transport of the smoke — many surface stations reported smoke or haze across southeastern Georgia, northeastern Florida, and far southeastern South Carolina that day (and EPA AIRNow particle Air Quality Indices were in the “Moderate” to “Unhealthy for Sensitive Groups” category). It is interesting to note that parts of the smoke pall were thick enough to reduce surface heating to the point that afternoon cumulus cloud formation was inhibited — a similar effect was discussed a few days earlier on the UMBC “US Air Quality” blog.

The MODIS aerosol optical depth (AOD) product from the IDEA site (below) indicated very high AOD values of 0.8 to 1.0. The 02 May IDEA trajectory forecast suggested that much of this smoke would experience a local recirculation during the following 24-48 hours, along with a transport of some smoke northeastward along the coastal portions of South Carolina and North Carolina. The MODIS AOD product and MODIS visible imagery from the next day (03 May 2007) verified this forecast, with thick smoke remaining over the general source region, in addition to a filament of smoke reaching as far northeastward as the outer banks of North Carolina.

View only this post Read Less

An animation of 3-hourly water vapor channel image composites from AWIPS during the entire month of April 2007 (25.5 MB QuickTime animation; 1280×1024 screen resolution required) shows the diverse variety of synoptic scale features that affected the Northern Hemisphere during that particular month.

View only this post Read Less