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NOUS42 KWNO 301401
ADMNFD
SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD
1400Z THU JUL 30 2009
THE NEW NOAA NWS NCEP SUPERCOMPUTERS...STRATUS/CIRRUS...
ARE SCHEDULED TO BECOME OPERATIONAL IN AUGUST.
NCEP/NCO WILL BE PERFORMING TESTS DURING THE NEXT SEVERAL
WEEKS IN ORDER TO ENSURE THAT PRODUCT DELIVERY IS NOT
IMPACTED ON THE IMPLEMENTATION DATE. NCEP/NCO IS PLANNING
TO DISSEMINATE PRODUCTS OPERATIONALLY FROM CIRRUS AND
STRATUS ON THE DATES LISTED BELOW:
CIRRUS - 12Z CYCLE TUE AUG 4TH...ONE CYCLE ONLY
STRATUS - 12Z CYCLE MON AUG 10TH...ONE CYCLE ONLY
IMPLEMENTATION DATE: 12Z CYCLE TUE AUG 18TH
AS WITH PREVIOUS UPGRADES...THE MODEL FORECASTS FROM THE
NEW COMPUTER MAY BE DISCONTINUOUS FROM THOSE PRODUCED ON THE
OLD COMPUTER/PREVIOUS CYCLE ESPECIALLY AFTER DAY 5. WHY?
THE HARDWARE/COMPILERS USED BY THE TWO COMPUTERS DIFFER AND
THE DATA DECODERS/ASSIMILATION SYSTEMS HAVE BEEN RUNNING
INDEPENDENTLY ON EACH SYSTEM. THESE TWO FACTORS WILL CREATE
SMALL DIFFERENCES IN MODEL INITIAL CONDITIONS CAUSED BY
ASSIMILATING DIFFERENT AMOUNTS OF DATA AND USING SLIGHTLY
DIFFERENT FIRST GUESS FIELDS. SMALL NON-METEOROLOGICAL
DIFFERENCES EVOLVE QUICKLY INTO RANDOM NOISE - TRIGGERING
CONVECTION IN DIFFERENT LOCATIONS AT DIFFERENT TIMES.
THESE TYPES OF DIFFERENCES GROW QUICKLY AND TEND TO
SATURATE AFTER A FEW HOURS OF MODEL TIME. AVERAGED OVER A
LARGE NUMBER OF CASES THERE IS NO EVIDENCE THAT ONE MACHINE
IS BETTER THAN THE OTHER...OR DIFFERENT IN ANY OTHER
SYSTEMATIC WAY.
EMC HAS BEEN MONITORING THE MODEL SUITE RUNNING ON THE NEW
COMPUTER AND RESULTS HAVE SHOWN THAT THERE IS NO APPRECIABLE
DIFFERENCE IN SKILL SCORE BETWEEN THE SYSTEMS. THIS IS TO BE
EXPECTED SINCE THE MODELING SUITE HAS NOT CHANGED.
WE APOLOGIZE FOR ANY INCONVENIENCES THIS MAY CAUSE. ALSO...
THE SCHEDULE IS HIGHLY SUBJECT TO CHANGE IN THE EVENT OF A
CRITICAL WEATHER DAY DURING THE TEST PERIOD. WE WILL
STRIVE TO INFORM USERS AS SOON AS POSSIBLE IN THE EVENT OF
ANY SCHEDULE CHANGES.
$$
SDM/NCO/NCEP