GREAT LAKES STAT. GUID. TO BE NGM-BASED

• To: G.CARTER(REC), R.LIVINGSTON(REC), D.SMITH.DAN(REC),
• Subject: GREAT LAKES STAT. GUID. TO BE NGM-BASED
• From: C.ALEX
• Date: Wed, 3 Mar 1993 10:46:14 -0700

Posted: Mon, Mar  1, 1993   4:31 PM EST              Msg: IGJD-5576-4305
        K.MIELKE(REC), 
        G.HUFFORD(REC), G.TRAPP(REC), E.YOUNG.NWS(REC)
CC:     L.MILLER.UCAR(REC)
Subj:   GREAT LAKES STAT. GUID. TO BE NGM-BASED       
In a continuing series of NMC implementations, I sent the following NTIM out 
today........
-----------------------------------------------------------------------------
WSHPNSNMC
NOUS41 KWBC 012029
 
NATIONAL TECHNICAL INFORMATION MESSAGE 93-07
NATIONAL WEATHER SERVICE HEADQUARTERS
330 PM EST MON MAR 1 1993
 
TO:         ALL NWS OFFICES, DOMESTIC DATA SERVICE SUBSCRIBERS,
            CARSWELL AFB, CANADIAN AES
 
FROM:       MARY M. GLACKIN
            CHIEF, SERVICES DEVELOPMENT BRANCH
 
SUBJECT:    STATISTICAL GUIDANCE FOR GREAT LAKES TO BE CHANGED
            FROM LFM-BASED TO RAFS-BASED
 
(THE FOLLOWING INFORMATION WAS PROVIDED BY LARRY BURROUGHS OF
THE MARINE PREDICTION BRANCH OF THE DEVELOPMENT DIVISION OF THE
NATIONAL METEOROLOGICAL CENTER [NMC].)
 
Effective with the 1200 UTC cycle on Wednesday, March 3, 1993,
four revised guidance packages - the Great Lakes Wind Forecast
System, the Great Lakes Wave Forecast System, the Lake Erie Storm
Surge System, and the Lake Huron Storm Surge System - will be
implemented.  These four packages will be based on the Nested
Grid Model (NGM), rather than the Limited-area Fine-Mesh Model,
as they are currently.  The NGM is run as part of the Regional
Analysis and Forecast System (RAFS).  These changes are in
preparation for the phase-out of the LFM, which is planned for
(on or about) June 1st for the contiguous U.S.  Other changes
have been incorporated in the Great Lakes Forecast System because
it was fortuitous to do so.  A Technical Procedures Bulletin
(TPB) describing the changes is in preparation and will be
distributed to TPB subscribers when it becomes available.  The
highlights of the changes are given below:
 
1)   Great Lakes Wind Forecast System
 
In anticipation of the discontinuation of the LFM, new forecast
equations were derived from the modified perfect prognosis
approach with data from the LFM analyses and model output from
the 6-hour projections on each cycle.  For the warm season
(April-September), there are 10 sets of sector equations - one
equation set for each of the sectors in Lakes Erie, Huron,
Michigan, and Superior;  there is one set of regional equations
for Lake Ontario that is applied to both of its sectors.  For the
cool season (October-March), there is one set of regional
equations that is used for all 12 sectors.  These equations use
model output from the RAFS.  Wind speeds are inflated as before,
and the format of the messages remains the same.
 
The AFOS PIL for this guidance is cccMRPGLW;  the WMO header is
FZUS4 KWBC.  It is distributed on AFOS to the Eastern, Central,
Southern, and Western Region loops, and is also available on the
NWS's Family of Services Domestic Data Service circuit, the U.S.
Air Force's Automated Weather Network, and to the Canadian
Weather service (AES).
 
As a result of the change in models, the transmission time of
this product will change.  It will be available at approximately
0400 and 1600 UTC.
 
2)   Great Lakes Wave Forecast System, Lake Erie Storm Surge
     Forecast System, and Lake Huron Storm Surge Forecast System
 
The only change to these systems is that they now use RAFS output
data for input rather than LFM output data.
 
The AFOS PILs and WMO headers for these products are:
 
AFOS PIL     WMO HEADER    PRODUCT TITLE
 
cccMRPGLW    FZUS4 KWBC    Great Lakes Winds/Waves
cccMRPESS    FZUS1 KWBC    Lake Erie Storm Surge (also contains
                             Lake Huron Storm Surge)
 
The distribution of the MRPGLW product was discussed in 
Section 1, above.  The MRPESS product is distributed on AFOS to
the Eastern, Central, Southern, and Western Region loops, and is
also available on the NWS's Family of Services Domestic Data
Service circuit and to the Canadian Weather Service (AES).
 
As a result of the change in models, the transmission times of
the products mentioned above will change.  They will be available
at approximately 0400 and 1600 UTC.
 
If there are any questions or concerns, call the developers -
Larry Burroughs at (301)-763-8133 for the Great Lakes Wind
Forecast System, or Will Shaffer at (301)-713-1613 for the
storm surge guidance products.
 
END