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Eureka Marine Stratus Cloud Climatologies - Basic Information

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Fig 2: Cloud percent climatology for Jul 16-Aug 15, 1999 to 2009 for 1200 UTC, when MLD is 751-1250 ft at 12 UTC. 121 cases

1) Product Information:

- Who is developing and distributing this product?

The Cooperative Institute for Research in the Atmosphere (CIRA) in Fort Collins, Colorado, is developing the Marine Stratus Cloud Climatologies together with the Eureka, CA National Weather Service (NWS) Office.

- Who is receiving this product, and how?

The Eureka, CA NWS office is receiving this product from CIRA through an ftp site.

- What is the product size?

The size of one netCDF file, centered over Eureka, CA is 1.4 MB. This is a static database, so updates are not required.

2) Product Description:

- Purpose of this product:

A major forecast challenge for the Eureka NWS office during the summer is the marine stratus and fog layer that forms along the California coast. The formation and dissipation of this layer affects ceiling and visibility forecasts for local airports as well as visibility and temperature forecasts for the general public. This product will be used to help forecast the duration and burn off rate of the marine stratus deck based on the thickness of this layer at 1200 UTC.

- Why is this a GOES-R Proving Ground Product?

The terrain of the northern California coast is complex with sharp changes in elevation. The higher temporal and spatial resolution as well as the larger number of bands will offer improved Marine Stratus Cloud Climatology products during the GOES-R era.

- How is this product created now?

For this project, images for channels 1(visible), 2 (3.9 µm) and 4 (10.7 µm) from GOES West at 4 km resolution were collected every hour for May through July, 1999-2009 covering the western U.S., and sectorized to cover most of northern California, including the County Warning Area (CWA) for the Eureka office. Then the images were grouped by calendar month and hour for further processing. More Information...

3) Product Examples and Interpretation

Here are some examples of the Marine stratus climatology. Figure 1 shows a map of the Eureka area.

Fig 1: Map of Eureka CWA

Fig 2: Cloud percent climatology for Jul 16-Aug 15, 1999 to 2009 for 1200 UTC, when MLD is 751-1250 ft at 12 UTC. 121 cases

More Information...

Figure 2 is the climatology for 1200 UTC (5 am local) when the MLD is between 751-1250 feet thick (regime 3) in the Eureka area during the July 16 to August 15 period. This is also the time the MLD is measured. The cloud percent is in the 90% range over Eureka, with a tongue of higher percentage cloud cover penetrating inland southeast of the station, along the Eel river valley. There is also a large amount of fog/marine stratus that has penetrated inland around the San Francisco and Monterey areas to the south.

By knowing the depth of the marine stratus layer at 12 UTC, a Eureka forecaster will be able to chose a regime that best matches the situation, using the time series as a starting point for the marine stratus burnoff forecast during that day.

4) Advantages and Limitations

The advantage of this product is that it provides the forecaster with a visual series of time steps of how the marine stratus layer could burn off during the day under a given set of conditions (MLD). It also aids a new forecaster in understanding a common weather phenomenon of the area. More Information...