Changes to the Eta MOS Products Effective Dates February 17th & 24th, 2004

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
1. 30 minute delay
2. New forecast equations
3. Remove 4 sites
4. Update 3 sites
 
Second Implementation
February 24, 2004
1. Addition of new sites
2. MET text message format extended to 72 hours;
    guidance available to 60 hours
3. Total sky categories modified
4. Snowfall amount and ceiling height added to MET

 

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. 

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)
Follow the link for a list of all the Eta MOS sites and their associated WMO and AWIPS headers.
 

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. 

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;
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.
 

For more details, see: Technical Procedures Bulletin for the Eta MOS text products (PDF)