GOES-12 and GOES-13 visible images

A comparison of GOES-12 and GOES-13 visible images (above) showed a long lake-effect cloud band that was oriented generally north-to-south across Lake Michigan on 20 January 2009. Convergence of surface winds was helping to sustain the cloud band over the lake, which was producing localized areas of heavy snowfall where it moved onshore in Illinois (5.0 inches reported in Chicago and Burnham) and Indiana (8.0 inches reported at Whiting). One thing that becomes immediately obvious in the above image comparison is the improved navigation on the new GOES-13 satellite: there is much less image-to-image wobble compared to GOES-12. As a result of this improved navigation, one is able to get a better sense of the actual drift of the ice that is floating in parts of the lake — ice along the eastern portion of the lake was drifting slowly westward away from the Michigan shore, while ice in the northwestern part of the lake was drifting slowly southward.

AWIPS images of the GOES-12 visible, 3.9 µm shortwave IR, 10.7 µm IR window, and Sounder Cloud Top Height product (below) suggested that the lake-effect cloud band was likely composed primarily of supercooled water droplets at 17:00 UTC — there was a strong signal of solar reflection on the shortwave IR image (darker gray enhancement), and IR window cloud top brightness temperature values were only as cold as -17 to -20º C  (cyan color enhancement). The GOES-12 sounder Cloud Top Height values were generally in the 10,000-12,000 foot range (green color enhancement). Note that there were only a few GOES-12 satellite-derived wind vectors associated with the cloud band; the number and accuracy of these atmospheric motion vectors would no doubt be improved using the better navigation of the GOES-13 visible imagery.

GOES-12 visible, shortwave IR, IR window, and sounder cloud top height

AWIPS images of the MODIS visible, 3.7 µm shortwave IR, 11.0 µm IR window, and Cloud Phase product (below) were similar to the GOES-12 images shown above — a strong “solar reflection signal” on the shortwave IR image (darker gray enhancement), with IR window cloud top brightness temperature values in the -17 to -20º C range (cyan color enhancement) — and the MODIS Cloud Phase product indicated that most of the cloud band was of the “Mixed Phase” or “Uncertain” category (gray colors).

MODIS visible, shortwave IR, IRT window, and cloud phase

It is interesting to view a series of 250-meter resolution MODIS true color images (below), using the CIMSS MODIS True Color Imagery Viewer on AWIPS (available to  NWS forecast offices in Wisconsin that have installed the CIMSS MODIS imagery scripts) — the ice increased in areal coverage on 15-16 January (when inland surface temperatures were as cold as -35º F or -37º C over southern Wisconsin), but then decreased somewhat on 18 January as temperatures slowly moderated.

250-meter resolution MODIS true color images (January 13-18)

View only this post Read Less

GOES-12 10.7 µm IR images

A strong “Alberta Clipper” system ushered in some of the coldest air of the 2008/2009 winter season on 12 January 2009 — in fact, it was so cold that AWIPS images of the GOES-12 10.7 µm IR channel data (above) showed that surface brightness temperatures as cold as -20º to -40º C (cyan to green color enhancement) were surging southward from south-central Canada into the north-central US in the wake of the clipper.

A closer view using GOES-12 IR imagery with a different color enhancement (below) displayed a large area of surface IR brightness temperatures colder than -40º C (violet colors) across much of eastern North Dakota and northwestern Minnesota during the pre-dawn hours of 13 January. The coldest GOES-12 IR brightness temperature values seen were -47º C (-53º F) at 13 UTC (7 AM local time) just to the north of Waskish (station identifier KVWU) in northeastern Minnesota.

GOES-12 10.7 µm IR images

The 1-km resolution MODIS 11.0 µm IR image at 08:57 UTC (3:57 AM local time) on 13 January (below) showed similar values of cold IR brightness temperatures, with a minimum of -48º C (-54º F). The coldest surface air temperature reported that morning was -42º C (-44º F) by the Cooperative Observer at Embarrass in northeastern Minnesota, with lows of -41º C (-42º F) at Babbit, Bigfork, Effie, and International Falls. Prior to this date, the coldest temperature recorded in the Lower 48 states this 2008/2009 winter season was -39º C (-38º F) at Simpson, Montana on 21 December 2008.

MODIS 11.0 µm IR image

— 15 January Update —

GOES-12 10.7 µm IR images

The coldest temperature recorded in the Lower 48 states during this particular cold outbreak was -44º C (-48º F) at Babbitt in northern Minnesota on 14 January. On the morning of 15 January, the core of the coldest air in the north-central US was found farther to the west, from central North Dakota into northeastern South Dakota: Garrison, North Dakota had a minimum temperature of -44º C (-47º F), Bismarck, North Dakota dropped to -42º C (-44º F) (only 1 degree F shy of their all-time record low), and Aberdeen, South Dakota recorded a low of -41º C (-42º F) (which was only 4 degrees F shy of their all-time record low). However, GOES-12 10.7 µm IR images (above) displayed surface IR brightness temperatures as cold as -47º C (-53º F) in North Dakota.

A comparison of 1-km resolution MODIS and 4-km resolution GOES-12 surface IR brightness temperatures at around 08:45 UTC or 3:45 AM local time (below) displayed very similar minimum values of -48º C (-54º F) and -47º C (-53º F), respectively.

MODIS 11.0 µm IR + GOES-12 10.7 µm IR images

With such a cold and dry air mass in place over the north, the GOES-12 6.5 µm “water vapor channel” imagery (below) was able to display a signature of the large surface temperature contrast between the relatively warm waters of the Great Lakes and the St. Lawrence River and the surrounding colder land surfaces. GOES-12 water vapor weighting functions calculated using the Detroit MI rawinsonde data indicated that many of the GOES imager and sounder water vapor channels were peaking at unusually-low altitudes.

GOES-12 6.5 µm water vapor images

MODIS true color imagery showed that ice formation was rapidly increasing over far western and southern Lake Michigan with the presence of the cold air over the Great Lakes region.

— 16 January Update —

The cold air continued to move eastward, and on the morning of 16 January had settled over the northeastern US.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CARIBOU ME
0955 AM EST FRI JAN 16 2009

**POTENTIAL STATEWIDE RECORD MINIMUM TEMPERATURE**

AT 0730 AM EST THIS MORNING A USGS GAGE AT BIG BLACK RIVER RECORDED A LOW TEMPERATURE OF -50F. THIS EXCEEDS THE CURRENT STATEWIDE RECORD LOW TEMPERATURE OF -48F SET ON JANUARY 19TH…1925 AT VAN BUREN. THIS REPORT IS CONSIDERED UNOFFICIAL UNTIL A REVIEW OF THE EQUIPMENT AND DATA BY THE STATE CLIMATE EXTREMES COMMITTEE AS TO THE VALIDITY OF THIS REPORT. IF THE COMMITTEE ASCERTAINS THAT THIS IS INDEED A VALID REPORT…A SEPARATE PUBLIC INFORMATION STATEMENT WILL BE ISSUED AT THAT TIME.

Several hours prior to this, 1-km resolution NOAA-18 10.8 µm IR imagery (below) showed cold air drainage into the valleys of northern Maine, with surface IR brightness temperatures as cold as -45.4º C (-49.7º F) at 06:41 UTC (02:41 AM local time). The low that morning of -38º C (-37º F) at Caribou, Maine was the coldest temperature recorded at that location for the entire month of January.

NOAA-18 10.8 µm IR image

View only this post Read Less

MODIS Sea Surface Temperature + RTG-SST model analysis

AWIPS images of the MODIS Sea Surface Temperature (SST) product at 16:22 UTC on 08 January 2009 and the closest corresponding RTG-SST model analysis at 00:00 UTC on 09 January (above) demonstrated some important advantages of the 1-km resolution MODIS satellite imagery for the analysis of small-scale water temperature details. The two obvious warm water features on the MODIS image were (1) a portion of the Gulf of Mexico Loop Current, and (2) the axis of the Gulf Stream over the far western Atlantic Ocean (off the Southeast US coast). While the RTG-SST model analysis did a good job with the placement of the position of the axis of the Loop Current, it was unable to capture many of the subtle water temperature structures and eddies that were present. In particular, note that the MODIS SST image displayed water temperatures that were slightly cooler (75-76º F) in the core of the Loop Current plume, which was surrounded by warmer SST values of 77-78ºF. The RTG-SST model analysis placed the “bulls-eye” of the warmest SST values just southwest of Buoy 42054, where the MODIS image indicated that the pocket of slightly cooler SST values were located.

The RTG-SST model analysis also appeared to have placed the axis of the Gulf Stream a bit far to the east.

View only this post Read Less

4-km resolution GOES-11 and 1-km resolution MODIS fog/stratus product

AWIPS images of the 4-km resolution GOES-11 fog/stratus product and the 1-km resolution MODIS fog/stratus product (above) showed widespread fog and stratus clouds in the central valleys of California as well as over the adjacent offshore waters of the Pacific Ocean on 08 January 2009. With the finer spatial resolution of the MODIS imagery, you can see several narrow fingers of fog that extended eastward into the smaller river valleys along the foothills of the Sierra Nevada Range — as well as the presence of several ship tracks in the stratus cloud deck over the ocean.

4-km resolution GOES-11 and 1-km resolution MODIS fog/stratus product

A closer view of the Sacramento Valley region (above) and the San Joaquin Valley region (below) reveals the intricate structure along the eastern edges of the fog and stratus features in those areas. The superior spatial resolution of the MODIS imagery can be very important to a variety of weather analysis and forecasting tasks: for example, trying to determine exactly which portions of Interstate 5 might have traffic slow-downs due to fog.

4-km resolution GOES-11 and 1-km resolution MODIS fog/stratus product

View only this post Read Less