AWIPS images of the MIMIC Total Precipitable Water (TPW) product (above) showed the presence of  long, narrow  filaments of moisture (often described as “tropospheric rivers“) that were moving across the North Pacific Ocean and the North Atlantic Ocean during the 04 May – 05 May 2009 period. Studies by Newell and others suggest that these tropospheric rivers can persist for more than 10 days, and are capable of transporting as much water as the Amazon River!

Composite geostationary satellite water vapor imagery (below) showed a similar signature of enhanced clouds and moisture along the axis these two tropospheric rivers — however, the presentation on the water vapor imagery was a bit different in terms of width and location.

MIMIC TPW + surface analysis

Note that the surface frontal structure was more closely aligned with the atmospheric rivers seen on the TPW imagery (above), but there was more of a mismatch with the corresponding water vapor image features (below). This is due to the fact that the water vapor imagery is generally sensing a signal from moisture located within a fairly deep layer aloft in the middle to upper troposphere, at a level above which the bulk of the total column precipitable water is located.

Composite water vapor imagery + surface analysis

A 4-panel comparison of the MIMIC TPW, the Blended TPW, and the GOES Sounder TPW products (below) shows that there is good agreement to the general magnitude of the TPW values between the various products. An animation shows the various strengths and weaknesses of each in terms of their utility for tracking atmospheric rivers. The MIMIC and Blended TPW products (top 2 panels) had better  temporal continuity, while the GOES water vapor imagery and the GOES Sounder TPW product (bottom 2 panels) suffered from gaps in coverage due to either Spring eclipse or the variable GOES Sounder scanning strategy.

Comparison of MIMIC TPW, Blended TPW, GOES Sounder TPW, and water vapor imagery

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