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NOUS41 KWBC 051851
PNSNMC
NATIONAL TECHNICAL INFORMATION MESSAGE 95-21
NATIONAL WEATHER SERVICE HEADQUARTERS
0245 PM EDT MON JUNE 5 1995
TO: WEATHER SERVICE FORECAST OFFICES
FAMILY OF SERVICES SUBSCRIBERS
OTHER USERS OF NWS MARINE FORECASTS
FROM: JOSEPH R. BOCCHIERI
CHIEF... SERVICES EVALUATION BRANCH
SUBJECT: REPLACEMENT OPERATIONAL HURRICANE MODEL
IMPLEMENTATION
REFERENCE: THE GFDL MULTIPLY-NESTED MOVEABLE MESH HURRICANE
MODEL SYSTEM... TECHNICAL PROCEDURES BULLETIN NO. 424
BY ROBERT TULEYA... MORRIS BENDER AND YOSHIO KURIHARA
(GEOPHYSICAL FLUID DYNAMICS LABORATORY NOAA/ERL
PRINCETON... NEW JERSEY) AND STEPHEN LORD (NATIONAL
METEOROLOGICAL CENTER... DEVELOPMENT DIVISION...
NOAA/NWS... WASHINGTON... D. C.). (IN PRESS)
THE NATIONAL HURRICANE CENTER RUNS DYNAMICAL AND STATISTICAL
MODELS TO FORECAST HURRICANES. THE CURRENT DYNAMICAL QUASI-
LAGRANGIAN MODEL IS BEING REPLACED BY A NEW HURRICANE FORECAST
MODEL SYSTEM... THE GFDL MULTIPLY-NESTED MOVEABLE MESH HURRICANE
MODEL SYSTEM. THIS IMPLEMENTATION WILL TAKE PLACE AS OF 1200 UTC
TUESDAY JUNE 6. THE MODEL HAS BEEN DEVELOPED AT GFDL OVER THE
LAST TEN YEARS AND REPRESENTS A STATE-OF-THE-ART CAPABILITY FOR
THE PREDICTION OF HURRICANE TRACK. THIS MODEL HAS A MORE
SOPHISTICATED PHYSICS PACKAGE AND INITIALIZATION SCHEME THAN ITS
PREDECESSOR... THE QLM. THE MODEL... DESIGNATED AS THE GFDL
HURRICANE MODEL (GHM)... WILL ALSO PRODUCE EXPERIMENTAL
FORECASTS OF HURRICANE INTENSITY FOR COMPARISON WITH OTHER
OPERATIONAL MODELS.
THE GHM IS A PRIMITIVE EQUATION MODEL FORMULATED IN
LATITUDE... LONGITUDE... AND SIGMA COORDINATES... WITH 18
VERTICAL LEVELS. THE OUTERMOST DOMAIN EXTENDS 75 DEGREES IN THE
MERIDIONAL AND LONGITUDINAL DIRECTIONS. THE GHM IS INTEGRATED
FOR 72 HOURS WITH SPECIFIED LATERAL BOUNDARY VALUES TAKEN FROM
GRID POINT FORECAST DATA AT 6-H INTERVALS FROM THE "AVIATION"
(AVN) GLOBAL MODEL RUN. THE MAJOR UNIQUE FEATURE OF THE GHM IS
ITS UNIQUE AND HIGHLY SUCCESSFUL METHOD OF VORTEX SPECIFICATION.
THIS METHOD USES TWO FILTERING PROCEDURES TO REMOVE THE ORIGINAL
VORTEX FROM THE AVN ANALYSIS AND THEN REPLACES IT WITH A
"SPIN-UP" VORTEX THAT IS COMPATIBLE WITH THE GHM.
IN A TEST SAMPLE FOR THE 1994 HURRICANE SEASON... THE
AVERAGE TRACK FORECAST ERRORS IN THE ATLANTIC AND EAST PACIFIC
BASINS WERE IMPROVED BY APPROXIMATELY 20% OVER THE QLM. THE GHM
WAS AMONG THE TOP PERFORMERS IN THE NHC FORECAST SUITE AT ALL
FORECAST HOURS. THE GHM PERFORMED EXTREMELY WELL FOR DIFFICULT
FORECAST CASES SUCH AS GORDON IN THE ATLANTIC AND LANDFALLING
STORMS SUCH AS ROSA IN THE EAST PACIFIC. THESE RESULTS ARE
CONSISTENT WITH ADDITIONAL TESTS PERFORMED FOR THE 1993
HURRICANE SEASON.
THE GHM FORECASTS WILL BE AVAILABLE AT APPROXIMATELY 5 HOURS
AFTER THE SYNOPTIC TIMES OF 0000 AND 1200 UTC. THE BASIC MODEL
FORECAST FOR EACH STORM IS TRANSMITTED IN THE STANDARD AUTOMATED
TROPICAL CYCLONE FORECAST (ATCF) SYSTEM FORMAT TO NHC. THE NEW
MODEL FORECASTS WILL BE STORED UNDER THE OLD QLM AFOS PIL...
MIAQLMMIA. THE GHM SYSTEM ALSO PRODUCES WIND SWATH MAPS THAT
SHOW THE STORM TRACK AND DISTRIBUTION OF THE MAXIMUM WINDS AT THE
SURFACE AND THE TOP OF THE BOUNDARY LAYER FOR THE PERIOD OF STORM
PASSAGE. INTENSITY FORECASTS ARE RECORDED IN THE SAME ATCF
FORMAT AS THE TRACK FORECASTS. INITIAL AND FORECAST BASIC
METEOROLOGICAL FIELDS ARE INTERPOLATED TO 1-DEGREE RESOLUTION AND
OUTPUT AT 6-H INTERVALS ON ISOBARIC SURFACES FROM 1000 TO 100 MB
EVERY 50 MB IN GRIB FORMAT. THE REFERENCED TPB NO. 424 SHOULD BE
SENT THIS WEEK FOR PRINTING AND DISTRIBUTION.
(INFORMATION FOR THIS MESSAGE HAS BEEN PROVIDED BY STEVE LORD OF
THE DEVELOPMENT DIVISION OF NMC)
END
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