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

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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 0º C to -2º C across much of the feature.

POES AVHRR Cloud Top Temperature product

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GOES-11 6.5 µm water vapor channel images

McIDAS images of GOES-11 6.5 µm 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 µm 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

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GOES-13 0.63 µm visible image (courtesy of Tony Cristaldi, NWS Melbourne FL)

Tony Cristaldi (National Weather Service Forecast Office in Melbourne, Florida) sent the following email (with the attached GOES-13 visible image shown above):

There is a very small cyclonic swirl to the southwest of Lisa near 12N 35W, that has been firing off central convection since Friday afternoon. Now, one wouldn’t expect a feature of this magnitude to be carried operationally as a TC, since these features are often times transient, being very vulnerable to even modest amounts of low level deformation and mid of upper level wind shear. Nevertheless, since it has persisted since early this morning, I thought I’d pose a couple questions: 1) Looking at visible imagery, does it appear that convection is persisting due to a warm core TC process (CISK) on a very small scale, or a more traditional low level mesoscale convective process? 2) Would you call this feature a “micro-midget?”

At his request, we created a 2-day animation covering the period 24-25 September 2010, using GOES-13 0.63 µm visible images during the daytime and GOES-13 3.9 µm shortwave IR images at night (below). The low-level “swirl” appeared to be propagating southeastward, and it was indeed firing off some impressive convective bursts (with a few cloud top IR brightness temperature values as cold as -70º C).

GOES-13 0.63 µm visible images (daytime) and 3.9 µm shortwave IR images (night-time)

Not quite sure exactly what to call it…but thanks to Tony for bringing this interesting feature to our attention!

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GOES-13 6.5 µm water vapor channel imagery

A strong mid-latitude cyclone intensified over the Lake Superior region on 24 September 2010. This storm produced wind gusts as high as 42 knots (48 mph), which caused some tree damage and some minor coastal flooding in parts of the Upper Peninsula of Michigan.

AWIPS images of 4-km resolution GOES-13 6.5 µm water vapor channel data (above) showed the evolution of the cyclone as it intensified during the day.

Greater detail could be seen in 1-km resolution MODIS 6.7 µm water vapor channel images at 16:21 UTC and 18:24 UTC (below).

MODIS 6.7 µm water vapor channel images

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