September 30th, 2010 | Scott Bachmeier
GOES-13 6.5 Âµm water vapor images + surface frontal analyses
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.Â
AWIPS images of GOES-13 6.5 Âµm 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.
Blended Total Precipitable Water product (26 - 30 September)
These high TPW values were in excess of 200% of normal (below) for that region and for that time of year.
Percent of Normal Total Precipitable Water product (26 - 30 September)
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!
MIMIC Total Precipitable Water product (26 - 30 September)
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 Âµm and POES AVHRR 10.8 Âµm IR channel data (below) revealed features with cloud top IR brightness temperatures in the -80Âº to -88Âº C range (light to dark purple color enhancement).
MODIS 11.0 Âµm IR and POES AVHRR 10.8 Âµm IR images
September 29th, 2010 | Scott Bachmeier
MODIS false color images (13 September and 29 September 2010)
A comparison of 250-meter resolution MODIS false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) show dramatic changes in some of the larger rivers (primarily the Mississippi River and the Wisconsin River) before (13 September 2010) and after (29 September 2010) parts of the Upper Midwest region received very heavy rainfall. Two locations in Wisconsin are highlighted where there were evacuations ordered due to flooding: Arcadia (on 23 September) and Portage (on 27 September).
These false color Red/Green/Blue images are created using MODIS bands 7/2/1 — water shows as the very dark features, allowing the changes in river boundariesÂ (as well as areas that have experienced significant water inundation) to be easily seen.
September 27th, 2010 | Scott Bachmeier
GOES-13 night-time fog/stratus product + daytime visible imagery
AWIPS images of the night-time 4-km resolution GOES-13 fog/stratus product and the daytime 1-km resolution GOES-13 visible images (above) showed two features of interest on 27 September 2010: (1) narrow fingers of river valley fog forming during the overnight hours — and then burning off during the early morning hours — over parts of the Mississippi River valley and the Wisconsin River valley, and (2) a larger patch of stratus cloud that lingered over southern Lake Michigan and the Chicago region.
Note the improvement in the detection of the actual structure of the river valley fog features with the change from the 4-km resolution fog/stratus product images to the 1-km resolution visible images — the importance of spatial resolution for detecting river valley fog is also obvious on a comparison of the 1-km resolution MODIS fog/stratus product image with the corresponding GOES-13 fog/stratus product image (below).
1-km resolution MODIS vs 4-km resolution GOES-13 fog/stratus product images
POES AVHRR Cloud Top Height product
Other satellite products that could be utilized to further characterize the large patch of stratus cloud over southern Lake Michigan and the Chicago region are the 1-km resolution POES AVHRR Cloud Top Height (CTH) product (above), which showed CTH values of around 3 km, and the 1-km resolution POES AVHRR Cloud Top Temperature (CTT) product (below), which depicted CTT values of 0Âº C to -2Âº C across much of the feature.
POES AVHRR Cloud Top Temperature product
September 26th, 2010 | Scott Bachmeier
GOES-11 6.5 Âµm water vapor channel images
McIDAS images of GOES-11 6.5 Âµm water vapor channel data (above) showed evidence of a very strong jet stream oriented from southwest to northeast across the eastern North Pacific Ocean on 26 September 2010, approaching the coast of British Columbia, Canada. The features on the water vapor imagery were seen to be moving very quickly along the jet stream axis.
A GOES-11 water vapor image with an overlay of MADIS 1-hour atmospheric motion vectors at 00 UTC on 27 September (below) displayed one wind target with a speed of 216 knots at a pressure level of 250 hPa (located near 45 N latitude, 140 W longitude).
GOES-11 6.5 Âµm water vapor image + MADIS 1-hour atmospheric motion vectors
A comparison of these MADIS winds with a number of model forecasts of maximum wind speed at any level (below) demonstrated how much the models can underestimate the maximum wind speeds within the core of a strong jet stream: The ECMWF Low-Resolution model forecast maximum winds just over 140 knots, while the CRAS45 and the CMC Low-Resolution models had maximum winds of just over 150 knots. The GFS90 and the UKMET models were the strongest, with forecast winds speeds of just over 160 knots — but still far less then the 216 knots observed by the MADIS atmospheric motion vector product.
GOES-11 water vapor image + comparison of model maximum wind speeds