Another Valuable Use of the RGB Airmass Product

While perusing the RGB airmass product with Dave Novak (SOO-HPC) on 10/07/11, we noticed another possible use of the RGB airmass product. The location of the WAA regime ahead of an amplified trough and possible uses for model diagnostics.

Model Diagnostics

Current GOES-E WV imagery valid at 1215z on 10/07/11 with the yellow circle denoting the shortwave rounding the base of the western trough and the green line depicting the suspect trough axis.

The above water vapor image from 1215z on 10/07 shows a healthy trough in the Rockies with one shortwave ejecting north-northeast into Canada while a second shortwave (yellow circle) rounds the base of the trough over southern California and the Las Vegas area. Based on this conventional imagery, the trough axis looks to be over the Las Vegas area down towards Los Angeles (maybe even slightly east of the green line). Also note the very dry air in the subtropics over the Baja and northern Mexico.

The GOES-Sounder RGB Airmass product valid at 1201z on 10/07/11 overlaid with the 12z NAM (yellow lines) and 12 GFS (white lines) 500 mb initializations.

When looking at the GOES-Sounder RGB Airmass product, the trough axis position (green) shows up much better and is actually a bit to the east of the axis identified on WV imagery alone. This illustrates the usefulness of the RGB Airmass product in getting a more representative depiction of troughs and exactly how amplifed or sharp of an axis may be. As Dave pointed out, this could be quite useful for model diagnostics.

Warm Air Advection (WAA) Regimes

Current GOES-E WV imagery valid at 1615z on 10/07/11 with the yellow circle highlighting the shortwave rounding the base of the western trough and the green lines depicting the suspect warm/moist advection boundaries.

Again, starting with the water imagery that is currently available on GOES-E, the airmass ahead of the trough looks rather dry with a narrow tongue of moisture streaming north from the central Gulf coast states. An additional moist tongue extends from the Eastern Pacific into the Southwest, but note how dry the airmass appears when looking at this one wavelength which is reading ~400 mb.

The GOES-Sounder RGB Airmass product valid at 1601z on 10/07/11 with the yellow circle denoting the shortwave rounding the base of the western trough and the green lines depicting the edges of the suspect WAA regime.

The GOES-Sounder image above shows a much different picture of the associated WAA regime associated with this trough. The WAA appears displaced further west into Texas (light green shading) and extends back to the Baja and northern Mexico. This area shows up very dry on the water vapor image alone. After inspecting this with Dave, I decided to pull up the MODIS RGB Airmass product for confirmation.

MODIS RGB Airmass product valid at 1658z on 10/07/11 with the green lines highlighting the boundaries of the WAA regime.

The MODIS RGB Airmass product does a great job of showing the full extent of the WAA regime in the Plains and Mississippi Valley due to having more bands available to create finer resolution in the product. (The GOES-Sounder product is limited due to fewer available bands.) The green lines are highlighting the boundaries of the this flow with the green shading indicating warm, moist air flowing north from the Gulf of Mexico. The red area on the peripheries show the dry synoptic air to the east associated with the strong ridge over the Mid-Atlantic and the dry punch and possible stratopheric intrusion ejecting out of the norther Rockies with the associated shortwave.

These two examples show some alternative uses of the RGB Airmass product when no tropical cyclones or explosive extratopical cyclones are around. By using these products in conjuncion with the model initializations and available observations, more confidence will be gained in short-term forecasts.

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