MDL has redeveloped Eta MOS guidance using a high-resolution archive in space and time. We are planning to implement several changes to the system in two stages. The tables below list the changes for the two implentations, and details follow.
First Implementation February 17, 2004
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1. 30 minute delay
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2. New forecast equations
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3. Remove 4 sites
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4. Update 3 sites
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Second Implementation February 24, 2004
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1. Addition of new sites
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2. MET text message format extended to 72 hours;
guidance available to 60 hours |
3. Total sky categories modified
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4. Snowfall amount and ceiling height added to MET
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Changes in the First Implementation - Effective February 17, 2004
Products Available 30 Minutes Later
The previous Eta MOS guidance used model data out to 48 hours to produce forecasts out to 60 hours in advance. The current Eta MOS forecasts are produced as soon as the 48-h model files are available (roughly 0245/1445 UTC). The redeveloped Eta MOS uses model data out to 84 hours to produce forecasts out to 84 hours in advance. Products will now be disseminated approximately 30 minutes later because we must wait until additional model files are available to use. Because of timing considerations, guidance will be available only out to 60 hours in this first implementation.
New Equations
New Eta MOS forecast equations for max/min temperature, spot temperatures and dewpoints, POP/QPF, wind speed and direction, and total sky cover will be implemented. Testing of these equations show that this guidance exhibits improved skill compared to the current Eta MOS. Verification scores can be viewed at the following link:.
http://www.nws.noaa.gov/mdl/synop/tin/eta32verif.htm
Changes to Stations: Deletions, Updates
MDL will make changes to the stations that are available in the Eta MOS MET text bulletins. Due to station closures, text products for 4 sites will be removed from the Eta MOS system:
KNZJ EL TORO... CALIFORNIA
KP07 SANDERSON... TEXAS
KRRF PORT RICHEY... FLORIDA
KY22 LEMMON... SOUTH DAKOTA
The call letters for 3 sites being updated in the Eta MOS text products are as follows:
SITE FROM TO
CECIL FIELD... FLORIDA KNZC KVQQ
CUSTER...SOUTH DAKOTA K0V1 KCUT
DENNISON...TEXAS KF39 KGYI
Please see Technical Information Notice #03-48 for the official notificiation for this first implementation, including the WMO headers for the products that will be affected.
Changes in the Second Implementation - Effective February 24, 2004
Eta MOS Available for Additional Sites Including Alaska
MDL will make changes to the stations that are available in the Eta MOS products.
Guidance for sites in Alaska and Hawaii will now be available, and 142 new sites in the CONUS will be added to the MET text messages. The complete list of WMO and AWIPS headers for the Eta MOS MET text bulletins are as follows:
WMO HEADING AWIPS ID
FOPA40 KWNO METPA0 PACIFIC ISLANDS
FOUS44 KWNO METNE1 NORTHEAST CONUS
FOUS45 KWNO METSE1 SOUTHEAST CONUS
FOUS46 KWNO METNC1 NORTH CENTRAL CONUS
FOUS47 KWNO METSC1 SOUTH CENTRAL CONUS
FOUS48 KWNO METRM1 ROCKY MOUNTAIN CONUS
FOUS49 KWNO METWC1 WEST COAST CONUS
FOAK47 KWNO METAJK SOUTHEAST ALASKA (JUNEAU)
FOAK48 KWNO METAFC CENTRAL ALASKA (ANCHORAGE)
FOAK49 KWNO METAFG NORTHERN ALASKA (FAIRBANKS)
A list of all the Eta MOS sites and their associated WMO and AWIPS headers can be found at http://www.nws.noaa.gov/mdl/synop/stadrg.html .
Eta MOS MET Text Messages Extended to 72 hours
The format of the Eta MOS MET text messages will be modified to allow for guidance out to 72 hours in advance. At this time, we will change the format of the text products to allow for guidance at 66 and 72 hours, but we will not be adding those forecasts, due to the current timing of the Eta model run. In early April, NCEP will be making changes to the Eta model run times, and then we will add the 66- and 72-h guidance to the messages with much less impact on delivery time. At this time, we will fill the 66- and 72-h positions with the appropriate missing indicators.
Sample 0000 and 1200 UTC MET messages with new elements out to 72 hours are available at
http://www.nws.noaa.gov/mdl/synop/tin/eta32.htm
New Total Sky Categories
The definition of categories of total sky cover will be modified to distinguish between FEW and SCATTERED clouds. The new categories are as follows:
CL - clear;
FW - > 0 to 2 octas of total sky cover;
SC - > 2 to 4 octas of total sky cover;
BK - > 4 to < 8 octas of total sky cover;
OV - 8 octas of total sky cover or totally obscured;
Addition of Snowfall Amount and Ceiling Height Guidance
Categorical forecasts of snowfall amount will be available in the Eta MOS text products for 24-h periods ending at approximately 36 and 60 hours after 0000 UTC (60-h forecast not available until April); and 24, 48, and 72 hours after 1200 UTC (72-h forecast not available until April). Snowfall amount forecasts will be available from September 1 through May 31 for most sites in the MOS system. The snowfall amount categories are as follows:
0 = no snow or a trace expected;
1 = > a trace to < 2 inches expected;
2 = 2 to < 4 inches;
4 = 4 to < 6 inches;
6 = 6 to < 8 inches;
8 = 8 inches or more.
Categorical forecasts of ceiling height will be available in the Eta MOS text products. These categories are not the same as those in the current GFS MOS. An additional category has been added to distinguish between 1000 - 1900 ft and 2000 - 3000 ft. The ceiling height categories are as follows:
1 = ceiling height of < 200 feet;
2 - ceiling height of 200 - 400 feet;
3 - ceiling height of 500 - 900 feet;
4 - ceiling height of 1000 - 1900 feet;
5 - ceiling height of 2000 - 3000 feet;
6 - ceiling height of 3100 - 6500 feet;
7 - ceiling height of 6600 - 12,000 feet;
8 - ceiling height of > 12,000 feet or unlimited ceiling;
Sample 0000 and 1200 UTC MET messages with new elements out to 72 hours are available at
http://www.nws.noaa.gov/mdl/synop/tin/eta32.htm
Please see Technical Information Notice #03-49 for the official notificiation for this second implementation, including the WMO headers for the products that will be affected.
A Technical Procedures Bulletin for the Eta MOS text products is posted on the website http://www.nws.noaa.gov/mdl/synop/tpb/etamsg2004.htm
If you have questions, please contact MDL_MOS.webmaster@noaa.gov
Return to MOS Changes Page
Page updated February 3, 2004