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

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GOES-11 6.7 µm water vapor channel images

AWIPS images of the GOES-11 6.7 µm water vapor channel (above) showed a very long and well-defined plume of moisture streaming northeastward from just north of the Hawaiian Islands to the Pacific Northwest on 07 January – 08 January 2009. The National Weather Service forecast office in Seattle, Washington said it best:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
340 PM PST WED JAN 7 2009

.SHORT TERM…HEAVY RAIN AND FLOODING EVENT IS UNDERWAY. A LONG PLUME OF MOISTURE EMANATING FROM WEST OF HAWAII IS CURRENTLY POINTED AT SW WA/NW ORE. THE AXIS OF THE MOISTURE PLUME HAS BEEN SLOWLY SAGGING SOUTH TODAY…THOUGH EVERYWHERE HAS GOTTEN AT LEAST SOME AMOUNT OF RAIN. SOME PEOPLE REFER TO THIS PATTERN AS THE PINEAPPLE EXPRESS…WHILE OTHERS CALL IT A METEOROLOGICAL FIRE HOSE. BOTH TERMS APPLY HERE. 850-700 MB WIND FLOW IS MORE WESTERLY THAN WITH MOST HEAVY RAIN EVENTS (AS OPPOSED TO SOUTHWESTERLY)…SO RAIN IS FOCUSING A BIT HARDER THAN USUAL ON RIVERS WITH HEADWATERS IN THE CASCADES. THIS FLOODING EVENT COULD HAVE MANY PARALLELS TO THE NOVEMBER 2006 EVENT.

Blended Total Precipitable Water product

AWIPS images of both the CIRA Blended Total Precipitable Water product (above) and the CIMSS  MIMIC Total Trecipitable Water product (below) showed that TPW values were generally in the 30-40 mm (1.2-1.6 inches) range within this moisture plume. With the larger areal coverage of the CIMSS MIMIC TPW product display, you can get a better feel for the fact that this moisture plume had connections to the rich moisture contained within the Inter-Tropical Convergence Zone (ITCZ) as it began to surge northeastward on 06 January.

MIMIC Total Precipitable Water product

Heavy rainfall amounts included 9.30 inches at June Lake in Oregon and 9.05 inches at Wickersham in Washington — and as a result, there were widespread reports of flooding, mudslides, and avalanches as this plume of moisture moved inland and interacted with the topography of the region (shown below). In addition, strong winds were reported in parts of the region (with a wind gust of 130 mph at the top of Magic Mile Ski Lift in Timberline, Oregon).

AWIPS-2 topography image

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GOES-12 6.5 µm water vapor images + QuikSCAT winds

AWIPS images of the GOES-12 6.5 µm water vapor channel data  with an overlay of polar-orbiting QuikSCAT winds (above) showed the a rapidly-occluding cyclone over the Labrador Sea on 07 January 2009. The classic “dry swirl” signature on the water vapor imagery is a tell-tale indicator that a mature cyclone has reached the occluded phase. Note that the GOES-12 satellite had just returned to service as the operational GOES-East satellite on the previous day.

QuikSCAT wind speeds were as high as 58 knots (red wind barbs) off the southern tip of Greenland at 09:00 UTC. A comparison of the atmospheric motion vector coverage derived from GOES-12 IR and water vapor channel data with those derived from the WindSat instrument on the polar-orbiting QuikSCAT satellite (below) demonstrate the advantage of the 12.5 km resolution data from the QuikSCAT satellite — however, the QuikSCAT winds are valid near the surface, while the GOES-12 winds are valid at higher levels within the lower, middle, and even upper the troposphere.

GOES-12 water vapor image + GOES-12 winds + QuikSCAT winds

The Blended Total Precipitable Water product (below) depicted a plume of higher PW values (in the 15-25 mm range) wrapping around the eastern and northern periphery of the occluding cyclone. The polar-orbiting AMSU instrument indicated that rainfall rates were as high as 7-9 mm/hour within this plume of PW.

Blended Total Precipitable Water product

GOES-12 water vapor image + 24-hour forecast of surface pressure

The 24-hour forecast had the position of the surface low a bit far to the southwest (above) — however,  using the “dry swirl” signature on the water vapor imagery, the well-trained analysts at HPC were able to accurately depict the location of the surface low center as it moved northwestward across the Labrador Sea (below).

GOES-12 water vapor images + HPC surface frontal and MSLP analysis

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GOES-13 fog/stratus product

AWIPS images of the  GOES-13 fog/stratus product (above) showed a patch of stratus cloud that developed quickly as it moved northeastward across southern Wisconsin during the pre-dawn hours on 06 January 2009. In advance of this cloud feature, air temperatures were dropping off as clear skies and light winds were promoting strong radiational cooling – in southern Wisconsin, Boscobel (station identifier KOVS) dropped to 2º F (-17º C) and Madison (station identifier KMSN) dropped to 6º F (-14º C) shortly after 08 UTC (2 AM local time). However, after the arrival of the cloud feature, surface air temperatures quickly began to rise into the middle to upper teens F as the cloud deck began to trap heat that was radiating from the surface.

Comparisons of the 4-km resolution GOES-13 fog/stratus product with the 1-km resolution MODIS fog/stratus product  during the early stages of formation of this stratus cloud deck (below) demonstrated the superior feature detection capability of the MODIS instrument. Also note that the GOES-13 fog/stratus product exhibited a “false signal” along the western coast of Lake Michigan, where colder water temperatures in the low-mid 30s F were “confusing” the product — the improved spatial and spectral resolution of the MODIS channels allowed the creation of a “cleaner” fog/stratus product.

GOES-13 and MODIS fog/stratus product

GOES-13 and MODIS fog/stratus product

The development and growth of the stratus cloud feature was also evident on the GOES-13 Low Cloud Base product (below), portrayed an an extensive area of clouds having bases less than 1000 feet above the surface (red color enhancement).

GOES-13 Low Cloud Base product

This cloud feature was apparently fairly deep, with the GOES-13 sounder Cloud Top Height product (below) indicating cloud tops in the 12,000 to 14,000 feet range (light green color enhancement).

GOES-13 Cloud Top Height product

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