NWS forecast office use of MODIS TPW product
MODIS Total Precipitable Water product
The National Weather Service forecast office in Salt Lake City, Utah referred to the MODIS Total Precipitable Water (TPW) product (above) in their afternoon forecast discussion on 27 August 2011:
FXUS65 KSLC 272201 AFDSLCAREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UT 355 PM MDT SAT AUG 27 2011 .SYNOPSIS...HIGH PRESSURE NEAR THE FOUR CORNERS WILL DRIFT WEST AND WEAKEN ON SUNDAY. A VERY MOIST AIRMASS WILL REMAIN IN PLACE SUNDAY BRINGING SCATTERED THUNDERSTORMS TO UTAH. WESTERLY FLOW WITH A GRADUAL DRYING TREND IS THEN EXPECTED ON MONDAY AND TUESDAY. .DISCUSSION...UPPER LEVEL AREA OF HIGH PRESSURE REMAINS CENTERED NEAR THE FOUR CORNERS AREA THIS AFTERNOON...KEEPING A VERY MOIST AIRMASS IN PLACE ACROSS UTAH. GPS-MET SENSOR CONTINUES TO SHOW THAT COLUMN PRECIPITABLE WATER IS HOVERING AROUND 1.20 INCHES IN SALT LAKE CITY. AFTERNOON MODIS IMAGERY INDICATES THAT PRECIPITABLE WATER VALUES ARE GENERALLY 1.0 TO 1.25 INCHES STATEWIDE.
The MODIS TPW values were in general agreement with those seen on the GOES sounder TPW product (below), but with finer spatial resolution (4-km MODIS, vs 10-km GOES) the various TPW gradients appear smoother on the MODIS image.
GOES sounder Total Precipitable Water product
The Blended TPW product (below) displayed complete coverage (even in cloudy areas), but lacked the finer scale definition of the MODIS or GOES products due to the use of only Global Positioning System derived TPW data over inland areas.
Blended Total Precipitable Water product
The Percent of Normal TPW product (below) indicated that the TPW values present across the region were generally 150-200% above normal for the date.
Percent of Normal TPW product
Their forecast discussion went on to state:
AIRMASS QUICKLY DESTABILIZED IN THE EARLY AFTERNOON WITH SCATTERED CONVECTION FORMING IN THE SOUTH AND EAST AND MORE ISOLATED COVERAGE IN THE NORTHWEST.
The MODIS 0.65 µm visible channel image (below) showed the areas where organized convection had already developed across Utah and the surrounding states.
MODIS 0.65 µm visible chanel image
CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS. In addition, the VISIT training lesson “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.
